The effect of polymorphisms in FSHR gene on late follicular phase progesterone and estradiol serum levels in predicted normoresponders.

STUDY QUESTION: Does the presence of FSHR single-nucleotide polymorphisms (SNPs) affect late follicular phase progesterone and estradiol serum levels in predicted normoresponders treated with rFSH? SUMMARY ANSWER: The presence of FSHR SNPs (rs6165, rs6166, rs1394205) had no clinically significant impact on late follicular phase serum progesterone and estradiol levels in predicted normoresponders undergoing a GnRH antagonist protocol with a fixed daily dose of 150 IU rFSH. WHAT IS KNOWN ALREADY: Previous studies have shown that late follicular phase serum progesterone and estradiol levels are significantly correlated with the magnitude of ovarian response. Several authors have proposed that individual variability in the response to ovarian stimulation (OS) could be explained by variants in FSHR. However, so far, the literature is scarce on the influence of this genetic variability on late follicular phase steroidogenic response. Our aim is to determine whether genetic variants in the FSHR gene could modulate late follicular phase serum progesterone and estradiol levels. STUDY DESIGN, SIZE, DURATION: In this multicenter multinational prospective study conducted from November 2016 to June 2019, 366 patients from Vietnam, Belgium and Spain (166 from Europe and 200 from Asia) underwent OS followed by oocyte retrieval in a GnRH antagonist protocol with a fixed daily dose of 150 IU rFSH. All patients were genotyped for 3 FSHR SNPs (rs6165, rs6166, rs1394205) and had a serum progesterone and estradiol measurement on the day of trigger. PARTICIPANTS/MATERIALS, SETTING, METHODS: Included patients were predicted normal responder women <38 years old undergoing their first or second OS cycle. The prevalence of late follicular phase progesterone elevation (PE), as well as mean serum progesterone and estradiol levels on the day of trigger were compared between the different FSHR SNPs genotypes. PE was defined as >1.50 ng/ml. MAIN RESULTS AND THE ROLE OF CHANCE: The overall prevalence of PE was 15.8% (n = 58). No significant difference was found in the prevalence of PE in Caucasian and Asian patients (17.5% versus 14.5%). Estradiol levels on the day of trigger and the number of retrieved oocytes were significantly higher in patients with PE (4779 ± 6236.2 versus 3261 ± 3974.5 pg/ml, P = 0.003, and 16.1 ± 8.02 versus 13.5 ± 6.66, P = 0.011, respectively). Genetic model analysis, adjusted for patient age, body mass index, number of retrieved oocytes and continent (Asia versus Europe), revealed a similar prevalence of PE in co-dominant, dominant and recessive models for variants FSHR rs6166, rs6165 and rs1394205. No statistically significant difference was observed in the mean late follicular phase progesterone serum levels according to the genotypes of FSHR rs6166 (P = 0.941), rs6165 (P = 0.637) and rs1394205 (P = 0.114) in the bivariate analysis. Also, no difference was found in the genetic model analysis regarding mean late follicular phase progesterone levels across the different genotypes. Genetic model analysis has also revealed no statistically significant difference regarding mean estradiol levels on the day of trigger in co-dominant, dominant and recessive models for variants FSHR rs6166, rs6165 and rs1394205. Haplotype analysis revealed a statistically significant lower estradiol level on the day of trigger for rs6166/rs6165 haplotypes GA, AA and GG when compared to AG (respectively, estimated mean difference (EMD) -441.46 pg/ml (95% CI -442.47; -440.45), EMD -673.46 pg/ml (95% CI -674.26; -672.67) and EMD -582.10 pg/ml (95% CI -584.92; -579.28)). No statistically significant differences were found regarding the prevalence of PE nor late follicular phase progesterone levels according to rs6166/rs6165 haplotypes. LIMITATIONS, REASONS FOR CAUTION: Results refer to a population of predicted normal responders treated with a normal/low fixed dose of 150 IU rFSH throughout the whole OS. Consequently, caution is needed before generalizing our results to all patient categories. WIDER IMPLICATIONS OF THE FINDINGS: Based on our results, FSHR SNPs rs6165, rs6166 and rs1394205 do not have any clinically significant impact neither on late follicular phase serum progesterone nor on estradiol levels in predicted normal responders. These findings add to the controversy in the literature regarding the impact of individual genetic susceptibility in response to OS in this population. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by an unrestricted grant by Merck Sharp & Dohme (MSD, IISP56222). N.P.P. reports grants and/or personal fees from MSD, Merck Serono, Roche Diagnostics, Ferring International, Besins Healthcare, Gedeon Richter, Organon, Theramex and Institut Biochimique SA (IBSA). C.A. reports conference fees from Merck Serono, Medea and Event Planet. A.R.N., C.B., C.S., P.Q.M.M., H.T., C.B., N.L.V., M.T.H. and S.G. report no conflict of interests related to the content of this article. TRIAL REGISTRATION NUMBER: NCT03007043.

The effect of polymorphisms in FSHR and FSHB genes on ovarian response: a prospective multicenter multinational study in Europe and Asia.

STUDY QUESTION: Does the presence of single nucleotide polymorphisms (SNPs) in the FSH receptor gene (FSHR) and/or FSH beta subunit-encoding gene (FSHB) influence ovarian response in predicted normal responders treated with rFSH? SUMMARY ANSWER: The presence of FSHR SNPs (rs6165, rs6166, rs1394205) has a statistically significant impact in ovarian response, although this effect is of minimal clinical relevance in predicted normal responders treated with a fixed dose of 150 IU rFSH. WHAT IS KNOWN ALREADY: Ovarian reserve markers have been a breakthrough in response prediction following ovarian stimulation. However, a significant percentage of patients show a disproportionate lower ovarian response, as compared with their actual ovarian reserve. Studies on pharmacogenetics have demonstrated a relationship between FSHR or FSHB genotyping and drug response, suggesting a potential effect of individual genetic variability on ovarian stimulation. However, evidence from these studies is inconsistent, due to the inclusion of patients with variable ovarian reserve, use of different starting gonadotropin doses, and allowance for dose adjustments during treatment. This highlights the necessity of a well-controlled prospective study in a homogenous population treated with the same fixed protocol. STUDY DESIGN, SIZE, DURATION: We conducted a multicenter multinational prospective study, including 368 patients from Vietnam, Belgium, and Spain (168 from Europe and 200 from Asia), from November 2016 until June 2019. All patients underwent ovarian stimulation followed by oocyte retrieval in an antagonist protocol with a fixed daily dose of 150 IU rFSH until triggering. Blood sampling and DNA extraction was performed prior to oocyte retrieval, followed by genotyping of four SNPs from FSHR (rs6165, rs6166, rs1394205) and FSHB (rs10835638). PARTICIPANTS/MATERIALS, SETTING, METHODS: Eligible were predicted normal responder women <38 years old undergoing their first or second ovarian stimulation cycle. Laboratory staff and clinicians were blinded to the clinical results and genotyping, respectively. The prevalence of hypo-responders, the number of oocytes retrieved, the follicular output rate (FORT), and the follicle to oocyte index (FOI) were compared between different FSHR and FSHB SNPs genotypes. MAIN RESULTS AND THE ROLE OF CHANCE: The prevalence of derived allele homozygous SNPs in the FSHR was rs6166 (genotype G/G) 15.8%, rs6165 (genotype G/G) 34.8%, and rs1394205 (genotype A/A) 14.1%, with significant differences between Caucasian and Asian women (P < 0.001). FSHB variant rs10835638 (c.-211 G>T) was very rare (0.5%). Genetic model analysis revealed that the presence of the G allele in FSHR variant rs6166 resulted in less oocytes retrieved when compared to the AA genotype (13.54 ± 0.46 vs 14.81 ± 0.61, estimated mean difference (EMD) -1.47 (95% CI -2.82 to -0.11)). In FSHR variant rs1394205, a significantly lower number of oocytes was retrieved in patients with an A allele when compared to G/G (13.33 ± 0.41 vs 15.06 ± 0.68, EMD -1.69 (95% CI -3.06 to -0.31)). A significantly higher prevalence of hypo-responders was found in patients with the genotype A/G for FSHR variant rs6166 (55.9%, n = 57) when compared to A/A (28.4%, n = 29), ORadj 1.87 (95% CI 1.08-3.24). No significant differences were found regarding the FORT across the genotypes for FSHR variants rs6166, rs6165, or rs1394205. Regarding the FOI, the presence of the G allele for FSHR variant rs6166 resulted in a lower FOI when compared to the A/A genotype, EMD -13.47 (95% CI -22.69 to -4.24). Regarding FSHR variant rs6165, a lower FOI was reported for genotype A/G (79.75 ± 3.35) when compared to genotype A/A (92.08 ± 6.23), EMD -13.81 (95% CI -25.41 to -2.21). LIMITATIONS, REASONS FOR CAUTION: The study was performed in relatively young women with normal ovarian reserve to eliminate biases related to age-related fertility decline; thus, caution is needed when extrapolating results to older populations. In addition, no analysis was performed for FSHB variant rs10835638 due to the very low prevalence of the genotype T/T (n = 2). WIDER IMPLICATIONS OF THE FINDINGS: Based on our results, genotyping FSHR SNPs rs6165, rs6166, rs1394205, and FSHB SNP rs10835638 prior to initiating an ovarian stimulation with rFSH in predicted normal responders should not be recommended, taking into account the minimal clinical impact of such information in this population. Future research may focus on other populations and other genes related to folliculogenesis or steroidogenesis. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by an unrestricted grant by Merck Sharp & Dohme (MSD). N.P.P. reports grants and/or personal fees from MSD, Merck Serono, Roche Diagnostics, Ferring International, Besins Healthcare, Gedeon Richter, Theramex, and Institut Biochimique SA (IBSA). N.L.V. and M.T.H. report consultancy and conference fees from Merck, Ferring, and MSD, outside the submitted work. P.D. has received honoraria for lecturing and/or research grants from MSD, Ferring International, and Merck. D.S. reports grants and/or personal fees from MSD, Ferring International, Merck Serono, Cook, and Gedeon Richter. A.R.N., B.A.M., C.S., J.M., L.H.L., P.Q.M.M., H.T., and S.G. report no conflict of interests. TRIAL REGISTRATION NUMBER: NCT03007043.

Effect of GnRHa ovulation trigger dose on follicular fluid characteristics and granulosa cell gene expression profiles.

PURPOSE: A recent dose-finding study showed no significant differences in number of mature oocytes, embryos and top-quality embryos when triptorelin doses of 0.2, 0.3 or 0.4 mg were used to trigger final oocyte maturation in oocyte donors co-treated with a gonadotropin-releasing hormone (GnRH) antagonist. This analysis investigated whether triptorelin dosing for triggering final oocyte maturation in oocyte donors induced differences in follicular fluid (FF) hormone levels and granulosa cell gene expression. METHODS: This single-centre, randomised, parallel, investigator-blinded trial was conducted in oocyte donors undergoing a single stimulation cycle at IVFMD, My Duc Hospital, Ho Chi Minh City, Vietnam, from August 2014 to March 2015. A total of 165 women aged 18-35 years with body mass index <28 kg/m2, anti-Müllerian hormone >1.25 ng/mL, and antral follicle count ≥6 were randomised to three different triptorelin doses for trigger. The main outcome was concentration of steroid hormones in FF collected from the first punctured follicle on each side. Moreover, luteinising hormone receptor (LHR), 3ß-hydroxy-steroid-dehydrogenase (3ßHSD) and inhibin-Ba (INHB-A) gene expression in cumulus and mural granulosa cells were investigated in a subset of women from each group. RESULTS: Progesterone and oestradiol levels in FF did not differ significantly by trigger doses; findings were similar for 3ßHSD, LHR and INHB-A gene expression in both cumulus and mural granulosa cells. CONCLUSIONS: In women co-treated with a GnRH antagonist, no significant differences in FF steroid levels and granulosa cell gene expression were seen when different triptorelin doses were used to trigger final oocyte maturation.

Corifollitropin alfa vs recombinant FSH for controlled ovarian stimulation in women aged 35-42 years with a body weight ≥50 kg: a randomized controlled trial.

STUDY QUESTION: Is corifollitropin alfa 150 µg equivalent to follitropin beta 300 IU/day for controlled ovarian hyperstimulation (COS) in older women weighing ≥50 kg undergoing IVF and/or ICSI in Vietnam? SUMMARY ANSWER: Corifollitropin alfa 150 µg was equivalent to follitropin beta 300 IU/day with respect to the number of oocytes retrieved, the ongoing, cumulative and live birth rates and obstetric outcomes. WHAT IS KNOWN ALREADY: Corifollitropin alfa is a recombinant FSH (rFSH) preparation with slow absorption and a long half-life allowing administration of a single dose for COS lasting 7 days. Several randomized, controlled clinical trials have reported that COS with corifollitropin alfa is associated with similar outcomes compared with COS using daily rFSH. However, limited data are available in Asian patients. STUDY DESIGN SIZE DURATION: This randomized controlled trial was conducted at a single large IVF centre in Vietnam from June 2015 to August 2016. A total of 400 patients were included, 200 in each treatment group. The primary outcome measure was the number of oocytes retrieved. Patients were followed for 1 year after randomization. PARTICIPANTS /MATERIALS SETTING METHODS: Participants aged 35-42 years with a body weight ≥50 kg who were undergoing an IVF cycle were randomized to undergo COS with a single dose of corifollitropin alfa 150 µg on Day 2 or 3 of the menstrual cycle, or follitropin beta 300 IU/day for 7 days starting on Day 2 or 3 of the menstrual cycle. All underwent ICSI according to standard institutional protocols. A beta hCG test was performed 17 days after ovum pick-up, and positive tests were confirmed on vaginal and/or abdominal ultrasound at 5-6 weeks after embryo transfer (clinical pregnancy) and at ≥10 weeks (ongoing pregnancy). Rates of ovarian hyperstimulation syndrome, and maternal and foetal outcomes after one cycle of ICSI were monitored over 12 months. MAIN RESULTS AND THE ROLE OF CHANCE: Patients in the corifollitropin alfa and follitropin beta groups were well matched at baseline (mean age 37.5 ± 1.9 vs 37.7 ± 2.0 years, mean body weight 53.7 ± 5.4 vs 52.5 ± 4.8 kg). There was no significant difference between the corifollitropin alfa and follitropin beta groups in the number of oocytes retrieved (11.4 ± 5.9 vs 10.8 ± 5.8; P = 0.338). The ongoing pregnancy rate (31.5 vs 32.0%; P = 0.99) and live birth rate (30.5 vs 32.0%; P = 0.83) (both per initiated cycle at 12 months after randomization) were also similar in the two treatment groups. Complication rates were low and similar in the corifollitropin alfa and follitropin beta groups, and there were no significant between-group differences in obstetric outcomes. LIMITATIONS REASONS FOR CAUTION: This study had an open-label design, and therefore, the potential for bias cannot be excluded. The findings are only applicable to patient populations with similar characteristics to those enroled in the study. WIDER IMPLICATIONS OF THE FINDINGS: This study adds to the body of evidence supporting the equivalence of corifollitropin alfa and follitropin beta for COS in a variety of patients undergoing IVF and/or ICSI. The ability to provide COS with corifollitropin alfa has the potential to reduce the burden of treatment for patients. STUDY FUNDING/COMPETING INTERESTS: This study was supported by Merck Sharp and Dohme. The authors state that they have no financial or commercial conflicts of interest. TRIAL REGISTRATION NUMBER: The trial was registered with clinicaltrials.gov (NCT02466204). TRIAL REGISTRATION DATE: 2 June 2015. DATE OF FIRST PATIENT'S ENROLMENT: 19 June 2015.

Ultra-broad gain quantum cascade lasers tunable from 6.5 to 10.4 µm.

We present a quantum cascade laser structure with an ultra-broad gain profile that covers the wavelength range from 6.5 to 10.4 µm. In a grating-tuned external cavity, we demonstrated continuous tuning from 1027 cm(-1) to 1492 cm(-1) with this broad gain laser chip. We also fabricated distributed feedback quantum cascade laser arrays with this active region design and varied grating periods. We demonstrated single wavelength lasing from 962 (10.4) to 1542 cm(-1) (6.5 µm). The frequency coverage (580 cm(-1)) is about 46% of center frequency.

Recombinant follicle-stimulating hormone and recombinant luteinizing hormone versus recombinant follicle-stimulating hormone alone during GnRH antagonist ovarian stimulation in patients aged ≥35 years: a randomized controlled trial.

STUDY QUESTION: Does luteinizing hormone (LH) supplementation improve live birth rate after in vitro fertilization (IVF) in patients aged ≥35 years receiving a gonadotrophin-releasing hormone (GnRH) antagonist protocol? SUMMARY ANSWER: There was no difference in live birth rate with use of LH during IVF in patients aged ≥35 years undergoing IVF treatment using a GnRH antagonist protocol. WHAT IS KNOWN ALREADY: Use of GnRH analogues as part of a controlled ovarian hyperstimulation protocol during IVF treatment cycles decreases the amount of LH available to developing follicles. The role of LH supplementation for improving outcomes in patients undergoing controlled ovarian hyperstimulation as part of assisted reproduction treatments, particularly those involving a GnRH antagonist protocol, is unclear. It has been suggested that higher risk patients (e.g. age ≥35 years, poor ovarian reserve) may benefit from LH supplementation. STUDY DESIGN, SIZE, DURATION: This single-centre, randomized controlled trial was conducted from 1 October 2012 to 30 June 2014. A total of 240 women aged ≥35 years undergoing IVF received ovarian stimulation using a GnRH antagonist protocol, with recombinant follicle-stimulating hormone (r-FSH; Gonal-F(®)) starting from cycle day 2 or 3. GnRH antagonist (Cetrotide(®)) was administered on Day 5 of r-FSH administration. On Day 6, patients in the LH supplementation group were switched to r-FSH/r-LH (Pergoveris(®)) 150/75 IU/day. Randomization to study treatments was performed in blocks of 4 via a computer-generated random number list. PARTICIPANTS/MATERIALS, SETTING, METHODS: Of the 240 patients randomized to treatment, 120 received r-FSH/r-LH and 120 received r-FSH. Patients were recruited from the IVFAS, An Sinh Hospital, Ho Chi Minh City, Vietnam. MAIN RESULTS AND THE ROLE OF CHANCE: Live birth rate did not differ significantly (P > 0.05) between r-FSH/r-LH and r-FSH recipients (16.7 versus 17.5%; between-group difference 0.8, 95% confidence interval [CI] -9.5, 11.2). In addition, there were no significant differences between the r-FSH/r-LH and r-FSH groups with respect to the number of oocytes retrieved, implantation rate, miscarriage rate and clinical pregnancy rate. LIMITATIONS, REASONS FOR CAUTION: The open-label design could have introduced bias, and the relatively small sample size may have allowed detection of only the most common adverse events. In addition, the study was likely to be underpowered based on differences between the response rate assumptions used in the sample size calculation and the actual response rate during the study. WIDER IMPLICATIONS OF THE FINDINGS: The results of this study found no additional benefit from adding LH supplementation to ovarian stimulation with a GnRH antagonist protocol in women aged ≥35 years, and add to the body of evidence in this area. However, findings across studies are still inconsistent and additional research is needed before any clear recommendations for clinical practice can be made. STUDY FUNDING/COMPETING INTERESTS: This study was supported by the Research Center for Genetics and Reproductive Health, School of Medicine, Vietnam National University HCMC. The authors state that they have no financial or commercial conflicts of interest. TRIAL REGISTRATION NUMBER: The trial was registered with clinicaltrials.gov (NCT02244866).

Burst firing induces postsynaptic LTD at developing mossy fibre-CA3 pyramid synapses.

Synaptic development is an activity-dependent process utilizing coordinated network activity to drive synaptogenesis and subsequent refinement of immature connections. Hippocampal CA3 pyramidal neurons (PYRs) exhibit intense burst firing (BF) early in development, concomitant with the period of mossy fibre (MF) development. However, whether developing MF-PYR synapses utilize PYR BF to promote MF synapse maturation remains unknown. Recently, we demonstrated that transient tonic depolarization of postsynaptic PYRs induces a persistent postsynaptic form of long-term depression (depolarization-induced long-term depression, DiLTD) at immature MF-PYR synapses. DiLTD induction is NMDAR independent but does require postsynaptic Ca(2+) influx through L-type voltage gated Ca(2+) channels (L-VGCCs), and is expressed as a reduction in AMPAR function through the loss of GluR2-lacking AMPARs present at immature MF-PYR synapses. Here we examined whether more physiologically relevant phasic L-VGCC activation by PYR action potential (AP) BF activity patterns can trigger DiLTD. Using combined electrophysiological and Ca(2+) imaging approaches we demonstrate that PYR BF effectively drives L-VGCC activation and that brief periods of repetitive PYR BF, produced by direct current injection or intrinsic network activity induces NMDAR-independent LTD by promoting Ca(2+) influx through the activated L-VGCCs. This BF induced LTD, just like DiLTD, is specific for developing MF-PYR synapses, is PICK1 dependent, and is expressed postsynaptically. Our results demonstrate that DiLTD can be induced by phasic L-VGCC activation driven by PYR BF, suggesting the engagement of natural PYR network activity patterns for MF synapse maturation.

Cost-effectiveness of HIV nonoccupational post-exposure prophylaxis in Australia.

OBJECTIVE: The aim of the study was to determine the cost-effectiveness of HIV nonoccupational post-exposure prophylaxis (NPEP) in Australia. METHODS: A retrospective cost analysis of a population-based observational cohort of 1601 participants eligible for NPEP in Australia between 1998 and 2004 was carried out. We modelled NPEP treatment costs and combined them with effectiveness outcomes to calculate the cost per seroconversion avoided. We estimated the cost-utility of the programme, and sensitivity and threshold analysis was performed on key variables. RESULTS: The average NPEP cost per patient was A$1616, of which A$848 (52%) was for drugs, A$331 (21%) for consultations, A$225 (14%) for pathology and A$212 (13%) for other costs. The cost per seroconversion avoided in the cohort was A$1 647,476 in our base case analysis, and A$512,410 when transmission rates were set at their maximal values. The cost per quality-adjusted life-year (QALY) was between A$40,673 and A$176,772, depending on the risks of HIV transmission assumed. CONCLUSIONS: In our base case, NPEP was not a cost-effective intervention compared with the widely accepted Australian threshold of A$50,000 per QALY. It was only cost-effective after receptive unprotected anal intercourse exposure to an HIV-positive source. Although NPEP was a relatively well-targeted intervention in Australia, its cost-effectiveness could be improved by further targeting high-risk exposures.

Brain opioid receptor adaptation and expression after prenatal exposure to buprenorphine.

Previous in vivo studies revealed that buprenorphine can down-regulate mu and up-regulate delta2 and kappa1 opioid receptors in adult and neonatal rat brain. To assess gestational effects of buprenorphine on offspring, pregnant rats were also administered this drug and opioid receptor binding parameters (Kd and Bmax values) were measured by homologous binding assays of postnatal day 1 (P1) brain membranes. Buprenorphine concentrations of 2.5 mg/kg injected into dams elicited an up-regulation of kappa1 opioid receptors as detected with the kappa1-selective agonist 3H-U69593. Parallel studies with the mu-selective agonist [D-ala2, mephe4,gly-ol5] enkephalin revealed a buprenorphine-induced down-regulation in receptor density at 0.3, 0.6 or 2.5 mg/kg drug treatment. A greater down-regulation of mu receptors for P1 males than for their female counterparts was observed. Buprenorphine did not cause a reduction in binding affinity in these experiments. Changes in opioid receptor adaptation induced by buprenorphine were further supported by data from cross-linking of 125I-beta-endorphin to brain membrane preparations. RT-PCR analysis of opioid receptor expression was also estimated in P1 brains. However, significant changes in neither mu nor kappa receptor message were detected in P1 brains as a result of prenatal buprenorphine treatment under the conditions of these experiments. Since buprenorphine is being evaluated in clinical trials for the treatment of heroin abuse, the in utero actions of the drug have ramifications for its use in the treatment of maternal drug abuse.

Buprenorphine differentially alters opioid receptor adaptation in rat brain regions.

Previous in vivo studies revealed that the mixed agonist-antagonist buprenorphine can down-regulate mu and up-regulate delta 2 and kappa 1 opioid receptors in rat brain. In this report brain regional differences in opioid receptor adaptation were addressed. Rats received i.p. injections with buprenorphine (0.5-2.5 mg/kg) and were killed 20 h later. Membranes from 7 brain regions were analyzed for mu (3H-[D-Ala2,N-mephe4,Gly-ol5] enkephalin), kappa 1 (3H-U-69593), delta 1 (3H-[D-Pen2, D-Pen5] enkephalin) and delta 2 (3H-deltorphin II) receptor binding parameters. Buprenorphine induced down-regulation of mu receptors in frontal cortex, occipital cortex, thalamus, hippocampus, striatum and brain stem. Kd values for 3H-[D-Ala2,N-mephe4,Gly-ol5] enkephalin were unchanged from controls. Up-regulation of kappa 1 receptors was observed in frontal, parietal, occipital cortexes and striatum. Binding to delta 2 sites was elevated in frontal and parietal cortexes. Buprenorphine did not alter delta 1 binding in any of the regions examined. Changes in opioid receptor adaptation induced by buprenorphine were further supported by data from cross-linking of 125I-beta-endorphin to cortical membrane preparations. A reduction in a 60- to 65-kDa band was detected in frontal and occipital cortices in which binding assays revealed down-regulation of mu receptors. In parietal cortex neither the 60- to 65-kDa product nor Bmax changes were observed. These results indicate that buprenorphine is a useful tool to study brain opioid receptor adaptation in vivo and the information accrued may be relevant to the mode of action of this drug in the treatment of heroin and cocaine abuse.

Reasons patients with chest pain delay or do not call 911.

STUDY OBJECTIVE: To determine the reasons patients with suspected acute myocardial infarction (AMI) delay seeking medical care or do not call 911. DESIGN: Telephone interview of patients hospitalized with suspected AMI. SETTING: Nine hospitals in King County, Washington. PARTICIPANTS: Patients admitted to a CCU or ICU between October 1, 1986, and December 31, 1987, with suspected AMI occurring out-of-hospital. Spouses of patients who met criteria but died during the hospitalization also participated. INTERVENTIONS: Hospital records were reviewed, and a 20-minute telephone interview was conducted of patients who reside in King County but do not live in an extended care facility. MEASUREMENTS: Patient demographics, cardiac history, symptoms, time of acute symptom onset, time of emergency department arrival, method of transportation, discharge diagnosis, and hospital outcome were abstracted from hospital records. Circumstances leading to the hospitalization, reasons for delay in seeking care, and reasons for not calling 911 were determined in the telephone interview. RESULTS: In a 15-month period, 5,207 patients were hospitalized for suspected AMI in King County, Washington. Twenty-seven percent had AMI. Median patient delay between symptom onset and hospital arrival was 2 hours. Paramedics transported 45% of all patients. A representative subset of patients (2,316) were interviewed. The main reasons for delay were because the patient thought that the symptoms would go away, because the symptoms were not severe enough, and because the patient thought that the symptoms were caused by another illness. The main reasons for not calling 911 were because the symptoms were not severe enough, because the patient did not think of calling 911, and because the patient thought that self-transport would be faster because of his or her close location to the hospital. CONCLUSION: Maximal benefit from thrombolytic therapy is not realized in a substantial proportion of patients with AMI because of delays in seeking medical care. Knowledge of the reasons patients delay or do not call 911 can help focus efforts on achieving more rapid treatment of patients with AMI.

Transient down-regulation of neonatal rat brain mu-opioid receptors upon in utero exposure to buprenorphine.

Gestational actions of the mixed agonist-antagonist buprenorphine on mu- and kappa 1-opioid binding in neonatal and maternal rat brain were investigated. Upon exposure of pregnant rats to 0.5 mg/kg buprenorphine for 7 days prior to birth, postnatal day-one (P1) and P7 offspring brain mu-binding parameters (Kd and Bmax) were assessed with 3H-labeled [D-Ala2,Mephe4,Gly-ol5] enkephalin (DAMAGE). DAMAGE binding was attenuated by 64% in P1 membranes, whereas P7 preparations showed no changes. The same buprenorphine regimen resulted in diminished DAMGE Bmax values in mothers' brains, 2 but not 7 days after cessation of drug administration. Receptor density changes were not accompanied by alteration of mu-binding affinities. Although the postnatal developmental profile of kappa 1 opioid receptors in rat brain measured with [3H]U69593 revealed the presence of an ample number of sites for detection, their binding parameters in P1, P7 pups and mothers were unaffected by 0.5 mg/kg buprenorphine. In summary, buprenorphine administration to pregnant rats transiently down-regulates mu opioid receptors in neonatal and maternal brain.

Hypervolemic hemodilution may protect the rat's striatal neurons from ischemic injury by reducing the extracellular dopamine.

In vivo voltammetry (IVV) was used in rats with transient brain ischemia to measure changes in extracellular concentrations of dopamine (DA) and its metabolites in the corpus striatum. Striatal neuronal damage were also rated on a scale of 0-3 (0 = no damage; 3 = maximum cell loss). The striatal extracellular levels of DA and its metabolites increased by 12-fold during the 30 min of brain ischemia and returned to control values at 30 min after reperfusion. In another group treated with 4-5 ml of 10% human albumin intravenously infused 30 min before brain ischemia, both augmented striatal DA (and its metabolites) levels and striatal neuronal damages were reduced as compared to the ischemic control group (P < 0.05, unpaired Student's t-test). These results suggest that hypervolemic hemodilution protects the striatal neurons from ischemic injury by reducing the extracellular striatal DA release in rats.

A simplified method for selecting a carbon-fiber electrode in pulse voltammetry.

A method for selecting a usable carbon-fiber electrode using the equivalent resistance and capacitance is presented. This method uses an instrument with a PC-based look-up table for measuring the electrical characteristics of a carbon-fiber electrode in pulse voltammetry. Using this instrument, the equivalent resistance and capacitance of the carbon-fiber electrode in saturated sodium chloride solution can be obtained. This instrument includes a decade resistance box, a peak current detection and hold circuit, a half peak comparator and a decay duration counter. A look-up table is established by using RC circuits to emulate the electrochemical reaction of the carbon-fiber electrode in pulse voltammetry. The equivalent resistance is obtained from the decade resistance box according to Kirchhoff's law. Then the equivalent capacitance is determined from the decay duration counter reading and equivalent resistance with the look-up table via a PC interpolation program. After obtaining the equivalent resistance and capacitance of an electrode, the values are compared with the usable thresholds. This method provides an effective quality evaluation index of carbon-fiber electrode for the user in order to reduce electrode-induced experimental failure. The method is also available for other kinds of carbon-fiber electrodes as long as their look-up table and desired thresholds are established.

Differential down- and up-regulation of rat brain opioid receptor types and subtypes by buprenorphine.

The induction of opioid receptor adaptation by mixed agonist-antagonists such as buprenorphine has not been investigated. To this end, neonatal rats were given injections of buprenorphine (0.1-2.5 mg/kg/day) and mu binding (Kd and Bmax) to brain membranes was measured with [3H][D-Ala2,MePhe4,Gly-ol5]enkephalin. At doses of buprenorphine of > or = 0.5 mg/kg, mu sites were reduced 47-75%, without changes in affinity. Chronic administration of the structurally related partial agonist diprenorphine (2.5-75 mg/kg) failed to alter mu binding. Apparent loss of sites due to receptor blockade by residual buprenorphine was ruled out by several lines of evidence. Bmax values for delta ([3H][D-Ser2,L-Leu5]enkephalyl-Thr) and kappa ([3H]U69593) binding were elevated 1.9-4.2-fold by buprenorphine treatment. In adult rats buprenorphine (0.5-2.5 mg/kg) reduced mu-opioid binding to forebrain membranes dose dependently, by 25-77%. [3H][D-Ser2,L-Leu5] Enkephalyl-Thr-labeled delta subtype receptors and kappa sites in adult forebrain membranes were up-regulated 2-3-fold. The delta subtype receptors that bind [3H][D-Pen2,D-Pen5]enkephalin in neonatal or adult brain membranes were unaffected by 0.5-2.5 mg/kg buprenorphine treatment. Down-regulation (70-74%) of mu sites and up-regulation (1.9-6.7 fold) of delta and kappa receptors were also observed in synaptic plasma membrane-enriched and microsomal fractions from buprenorphine-treated adult rat brain. Because agonist-induced opioid receptor down-regulation is difficult to elicit in adult mammalian brain, these data indicate that buprenorphine is a useful tool to study brain opioid receptor adaptation in vivo.

Stimulation of the nigrostriatal dopamine system inhibits both heat production and heat loss mechanisms in rats.

The effects of stimulating the pars compacta of the substantia nigra (SNC) on thermoregulation were assessed in normal rats, in rats with chemical lesion of the SNC dopamine (DA) pathways and in rats with striatal DA receptor blockade. Electrical stimulation of the SNC produced hypothermia, decreased metabolism and/or cutaneous vasoconstriction in rats at ambient temperatures (Ta) below 22 degrees C, as well as hyperthermia and cutaneous vasoconstriction in rats at Ta of 30 degrees C. Microinjection of an excitotoxic amino acid (kainic acid) at the same brain sites also produced the same thermal responses. In vivo voltammetric studies revealed that electrical or chemical stimulation of the SNC produced an increase in striatal DA release. The enhanced striatal DA release induced by SNC stimulation was attenuated in rats after selective destruction of the nigrostriatal DA pathway by administration of 6-hydroxydopamine into the medial forebrain bundle. In addition, the magnitude of the thermal responses produced by the SNC stimulation in the cold was attenuated by selective bilateral destruction of the nigrostriatal DA pathways or selective blockade of the striatal DA produced by intrastriatal infusion of haloperidol, a DA receptor antagonist. The results indicate that stimulation of the SNC inhibits both heat production and heat loss mechanisms in the rat.

Delays in the treatment of acute myocardial infarction: an overview.

Delays in treatment of acute myocardial infarction prevent a substantial portion of patients from receiving maximal benefit from reperfusion therapy. Median delay between onset of symptoms and arrival at the hospital is 2 to 4 hours. Average time between arrival at the hospital and initiation of thrombolytic therapy is 84 minutes. Approximately 50% of patients hospitalized for suspected acute myocardial infarction do not use the emergency medical service system. Delay before treatment can be divided into several components: patient delay, emergency medical service delay, and hospital delay. Factors contributing to delay in each component and possible approaches to decreasing these delays are discussed. The effects of treatment delay on prognosis and future care-seeking behavior of patients hospitalized with suspected acute myocardial infarction are also discussed.

Effect of age on use of thrombolytic therapy and mortality in acute myocardial infarction. The MITI Project Group.

The findings in 3,256 consecutive patients hospitalized for acute myocardial infarction were tabulated to assess the history, treatments and outcome in the elderly; 1,848 patients (56%) were greater than 65 years of age, including 28% who were aged greater than or equal to 75 years. The incidence of prior angina, hypertension and heart failure (only 3% of patients less than 55 years of age had a history of heart failure compared with 24% greater than or equal to 75 years old) was found to increase with age. Twenty-nine percent of patients less than 75 years of age were treated with a systemic thrombolytic drug compared with only 5% of patients older than 75 years. Mortality rates increased strikingly with advanced age (less than 2% in patients less than or equal to 55, 4.6% in those 55 to 64, 12.3% in those 65 to 74 and 17.8% in those greater than or equal to 75 years). Both the incidence of complicating illness and a nondiagnostic electrocardiogram (ECG) increased with age. In a multivariate analysis of outcome in older patients (greater than or equal to 65 years), adverse events were related to both prior history of heart failure (odds ratio 3.9) and increasing age (odds ratio 1.4 per each decade of age). Outcome was not improved by treatment with thrombolytic drugs, but these agents were prescribed to only 12% of patients greater than 65 years of age, thereby reducing the power for detecting such an effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Accuracy of computer-interpreted electrocardiography in selecting patients for thrombolytic therapy. MITI Project Investigators.

A prehospital computer-interpreted electrocardiogram (ECG) was obtained in 1,189 patients with chest pain of suspected cardiac origin during an ongoing trial of prehospital thrombolytic therapy in acute myocardial infarction. Electrocardiograms were performed by paramedics 1.5 +/- 1.2 h after the onset of symptoms. Of 391 patients with evidence of acute myocardial infarction, 202 (52%) were identified as having ST segment elevation (acute injury) by the computer-interpreted ECG compared with 259 (66%) by an electrocardiographer (p less than 0.001). Of 798 patients with chest pain but no infarction, 785 (98%) were appropriately excluded by computer compared with 757 (95%) by an electrocardiographer (p less than 0.001). The positive predictive value of the computer- and physician-interpreted ECG was, respectively, 94% and 86% and the negative predictive value was 81% and 85%. Prehospital screening of possible candidates for thrombolytic therapy with the aid of a computerized ECG is feasible, highly specific and with further enhancement can speed the care of all patients with acute myocardial infarction.

Characteristics of black patients admitted to coronary care units in metropolitan Seattle: results from the Myocardial Infarction Triage and Intervention Registry (MITI).

Since 1988, 641 black and 11,892 white patients with chest pain of presumed cardiac origin have been admitted to coronary care units in 19 hospitals in metropolitan Seattle. Black men and women were younger (58 vs 66, p less than 0.0001), more often admitted to central city hospitals (p less than 0.0001), and developed evidence of acute myocardial infarction (AMI) less often (19 vs 23%, p = 0.01). In the subset of 2,870 AMI patients, blacks (n = 121) were younger (59 vs 67, p less than 0.0001) and had less prior coronary artery bypass graft surgery (2 vs 10%, p = 0.005) and more prior hypertension (67 vs 46%, p less than 0.0001). During hospitalization, whites (n = 2,749) had higher rates of coronary angioplasty (18 vs 10%, p = 0.03) and coronary artery bypass graft surgery (10 vs 4%, p = 0.04), although thrombolytic therapy and cardiac catheterization were used equally in the 2 groups. Hospital mortality was 7.4% for black and 13.1% for white patients (p = 0.07). However, after adjustment for key demographic and clinical variables by logistic regression, this difference was not as apparent (p = 0.38). Questions about the premature onset of coronary artery disease, excess systemic hypertension, and the differential use of interventions in black persons have been raised by other investigators. Despite differences in age, referral patterns and the use of coronary angioplasty and bypass surgery, black and white patients with AMI in metropolitan Seattle had similar outcomes.