Stem cell-derived interneuron transplants as a treatment for schizophrenia: preclinical validation in a rodent model.

An increasing literature suggests that schizophrenia is associated with a reduction in hippocampal interneuron function. Thus, we posit that stem cell-derived interneuron transplants may be an effective therapeutic strategy to reduce hippocampal hyperactivity and attenuate behavioral deficits in schizophrenia. Here we used a dual-reporter embryonic stem cell line to generate enriched populations of parvalbumin (PV)- or somatostatin (SST)-positive interneurons, which were transplanted into the ventral hippocampus of the methylazoxymethanol rodent model of schizophrenia. These interneuron transplants integrate within the existing circuitry, reduce hippocampal hyperactivity and normalize aberrant dopamine neuron activity. Further, interneuron transplants alleviate behaviors that model negative and cognitive symptoms, including deficits in social interaction and cognitive inflexibility. Interestingly, PV- and SST-enriched transplants produced differential effects on behavior, with PV-enriched populations effectively normalizing all the behaviors examined. These data suggest that the stem cell-derived interneuron transplants may represent a novel therapeutic strategy for schizophrenia.

Differential escape patterns within the dominant HLA-B*57:03-restricted HIV Gag epitope reflect distinct clade-specific functional constraints.

UNLABELLED: HLA-B*57:01 and HLA-B*57:03, the most prevalent HLA-B*57 subtypes in Caucasian and African populations, respectively, are the HLA alleles most protective against HIV disease progression. Understanding the mechanisms underlying this immune control is of critical importance, yet they remain unclear. Unexplained differences are observed in the impact of the dominant cytotoxic T lymphocyte (CTL) response restricted by HLA-B*57:01 and HLA-B*57:03 in chronic infection on the Gag epitope KAFSPEVIPMF (KF11; Gag 162 to 172). We previously showed that the HLA-B*57:03-KF11 response is associated with a >1-log-lower viral setpoint in C clade virus infection and that this response selects escape mutants within the epitope. We first examined the relationship of KF11 responses in B clade virus-infected subjects with HLA-B*57:01 to immune control and observed that a detectable KF11 response was associated with a >1-log-higher viral load (P = 0.02). No evidence of HLA-B*57:01-KF11-associated selection pressure was identified in previous comprehensive analyses of >1,800 B clade virus-infected subjects. We then studied a B clade virus-infected cohort in Barbados, where HLA-B*57:03 is highly prevalent. In contrast to findings for B clade virus-infected subjects expressing HLA-B*57:01, we observed strong selection pressure driven by the HLA-B*57:03-KF11 response for the escape mutation S173T. This mutation reduces recognition of virus-infected cells by HLA-B*57:03-KF11 CTLs and is associated with a >1-log increase in viral load in HLA-B*57:03-positive subjects (P = 0.009). We demonstrate functional constraints imposed by HIV clade relating to the residue at Gag 173 that explain the differential clade-specific escape patterns in HLA-B*57:03 subjects. Further studies are needed to evaluate the role of the KF11 response in HLA-B*57:01-associated HIV disease protection. IMPORTANCE: HLA-B*57 is the HLA class I molecule that affords the greatest protection against disease progression in HIV infection. Understanding the key mechanism(s) underlying immunosuppression of HIV is of importance in guiding therapeutic and vaccine-related approaches to improve the levels of HIV control occurring in nature. Numerous mechanisms have been proposed to explain the HLA associations with differential HIV disease outcome, but no consensus exists. These studies focus on two subtypes of HLA-B*57 prevalent in Caucasian and African populations, HLA-B*57:01 and HLA-B*57:03, respectively. These alleles appear equally protective against HIV disease progression. The CTL epitopes presented are in many cases identical, and the dominant response in chronic infection in each case is to the Gag epitope KF11. However, there the similarity ends. This study sought to better understand the reasons for these differences and what they teach us about which immune responses contribute to immune control of HIV infection.

Risk behaviour, healthcare access and prevalence of infection with Chlamydia trachomatis and Neisseria gonorrhoeae in a population-based sample of adults in Barbados.

OBJECTIVES: To estimate the prevalence of urogenital infection with Chlamydia trachomatis and Neisseria gonorrhoeae in people 18 to 35 years of age in Barbados, and to examine factors associated with infection. METHODS: Cross-sectional survey of randomly selected people from the voters' register of one electoral district and the collection of urine samples for testing by PCR. RESULTS: The response rate was 82%; 408 people (195 males and 213 females) completed a questionnaire and had their urine collected. 397 urine samples were satisfactorily tested. Prevalence of C trachomatis urogenital infection was 11.3% (95% CI +/-2.9) and N gonorrhoeae 1.8% (95% CI +/-1.2) with 12.6% (95% CI +/-3.1) having either or both infections. The difference in prevalence by gender was not significant. Multivariate logistic regression showed that prevalence of C trachomatis and/or N gonorrhoeae decreased with increasing age (per year OR 0.89, 95% CI 0.84 to 0.96, p = 0.001), and decreasing time (6 months) since last medical consultation (OR 0.44, 95% CI 0.22 to 0.88, p = 0.02). Most (76%) infected people were asymptomatic. Condom use at last intercourse with a partner not being lived with was not protective (reported by 52%, p = 0.617). The usual source of health care was evenly distributed between the public and private sectors and was not associated with infection. Only 30% of people had ever heard of chlamydia, whereas 92% were aware of gonorrhoea. CONCLUSIONS: Asymptomatic infection with C trachomatis is an important reservoir of infection, which will remain undetected unless physicians and young people are made aware of this and screening is introduced.

Evaluation of a commercial latex agglutination assay for serological diagnosis of leptospirosis.

Leptospirosis is a febrile zoonosis of worldwide distribution. A latex agglutination assay was evaluated in two studies, the first using a panel of well-characterized sera from patients with leptospirosis and from patients with other disease states and the second, a prospective hospital-based study, evaluating sera from 186 consecutive patients admitted to hospital with acute febrile illness. The confirmed leptospirosis serum panel included paired acute- and convalescent-phase specimens from 40 cases, of which 34 gave positive latex tests (case sensitivity, 85%; 95% confidence interval [95% CI], 70 to 94%). The other diseases represented in the panel of 112 specimens from nonleptospirosis patients included autoimmune diseases, brucellosis, dengue, melioidosis, malaria, syphilis, toxoplasmosis, viral hepatitis, and a number of other viral infections. The specificity of latex agglutination using this panel was 81% (95% CI, 73 to 87%). Among the patients with acute febrile illness, there were 25 cases of leptospirosis and 161 patients with other diagnoses. The sensitivity and specificity of latex agglutination in this group were 88% (95% CI, 72 to 97%) and 98% (95% CI, 95 to 100%), respectively. In this evaluation, the two distinct groups of specimens gave similar results for sensitivity, but specificity was different in each study. The sensitivity and specificity observed for the hospital study were similar to those obtained in evaluations of other rapid tests in the same population. The results of this study suggest that multiple evaluations of new diagnostic assays should be performed, because performance characteristics may vary in different populations.

Characteristics of lymphocyte subsets in a normal Afro-Caribbean population and the implications in HIV management.

The Caribbean relies on normal lymphocyte subsets ranges established in other geographical locations and from different racial ethnic groups for the basis of the clinical management of HIV and AIDS with Highly Active Anti Retroviral Therapy (HAART). Normal ranges of these parameters have not been previously established in an Afro-Caribbean population. So we set out to determine how the normal lymphocyte subset ranges compare to those reported in other, races and geographical locations. A prospective study was done on 112 healthy Afro-Caribbean clients who attended the Blood Collection Unit, Queen Elizabeth Hospital, Barbados from July 15th to November 12th 2004. Analysis for lymphocyte subsets was done by flow cytometry, which allows simultaneous identification and enumeration of total T Helper, cytotoxic T, natural killer and B lymphocyte cells. HIV-1, Hepatitis B and C, HTLV-1 and full blood count test were done as part of the normal screening routine of all blood donors. Absolute white blood cell counts and percentage lymphocytes for males and females were not significantly different, and the absolute and percentage of the T-Helper CD4 positive lymphocyte cells were not significantly higher in females than in males. Absolute Cytotoxic T cell CD8 positive lymphocyte cells were higher in males than in females. CD56 Natural Killer cells absolute and percentage counts were higher in males than females however CD19 B Lympocyte absolute and percentage counts were not different between the two sexes in this sample population. Compared to published normal ranges published by the WHO and CDC, there were no significantly differences observed in any of the lymphocyte subsets. These finding are very similar to what has been reported in previous studies. We conclude that WHO/CDC recommendations established for the treatment and monitoring of HIV/AIDS patients based on CD4 levels can be safely utilized in our population.

Altered hox gene expression and cellular pathogenesis of 5-aza-2'-deoxycytidine-induced murine hindlimb dysmorphogenesis.

The DNA demethylating agent, 5-aza-2'-deoxycytidine (d-AZA), elicits temporally related morphological defects and altered gene expression in mouse hindlimbs. Segmental formation of limb regions (stylopod, zeugopod. and autopod) is partially dependent on Hox gene activation. The objective of this study was to understand the role of altered expression of key hox genes in the early pathogenesis of d-AZA-induced hindlimb defects in mice. Semiquantitative RT-PCR was used to analyze hox gene expression (Hox C-11 and Hox A and D homologs, paralogs 9-13). Untreated and treated fore and hindlimb buds were collected 12 and 24 hours after IP injection (1 mg/kg) of d-AZA at 9 am on gestational (GD) 10 and processed for RT-PCR. Additional pregnant mice were treated similarly and whole embryos collected 12 and 24 hours posttreatment and processed for histopathological analysis. No changes in hox gene expression were detected in the forelimb tissue. There was a 2-fold down-regulation of hoxA-11 and C-11 in the 12-hour hindlimb bud tissue. No changes in the HoxD series were detected in the hindlimb bud tissue. The 12- and 24-hour untreated mice exhibited some of the morphological features consistent with physiological apoptosis. Most tissues of the treated mice exhibited cellular changes consistent with cell death associated with the cytotoxicity of the compound. The data reported supports the hypothesis that altered gene expression and not cytotoxicity alone is associated with d-AZA-induced hindlimb dysmorphogenesis.

Two methods for rapid serological diagnosis of acute leptospirosis.

Leptospirosis is a common and underdiagnosed zoonosis. Two rapid assays for serological diagnosis of acute leptospirosis in diagnostic laboratories, the immunoglobulin M (IgM)-dipstick assay and the indirect hemagglutination assay (IHA), were evaluated and compared with standard assays. Sera were examined from 104 patients admitted to a hospital for investigation in a leptospirosis diagnostic protocol. Specimens for serology were taken on days 1 and 4 of the patients' hospital stay. Antibodies were detected using an IgM-enzyme-linked immunosorbent assay (ELISA), microscopic agglutination test (MAT), an IgM-dipstick assay, and an IHA. Fifty-one patients were found to have leptospirosis. The sensitivity of the IgM-dipstick assay was 98%, its specificity was 90.6%, its positive predictive value was 90.9%, and its negative predictive value was 98%. The sensitivity of the IHA was 92.2%, its specificity was 94.4%, its positive predictive value was 95.9%, and its negative predictive value was 92.7%. The standard IgM-ELISA and MAT, were positive in the first samples tested from 67 and 55% of the cases, respectively, and the rapid IgM-dipstick assay and IHA were positive in 71 and 49%, respectively, in the first sample tested. Both rapid assays are highly sensitive and specific. Neither requires specialized equipment, and both are suitable for use in diagnostic laboratories.

ERCP-induced Pancreatitis.

The most important consideration in preventing ERCP-induced pancreatitis is patient selection. If you want to avoid pancreatitis, avoid performing ERCP in young patients for sphincter of Oddi dysfunction. Sphincter of Oddi manometry, difficult biliary cannulations (repeated pancreatic duct cannulations/injections), and precut and pancreatic sphincterotomy are associated with increased risk of pancreatitis. Pancreatic endotherapy, precut sphincterotomy, and Sphincter of Oddi manometry should be reserved for expert endoscopists. Short-term pancreatic stenting appears to decrease the risk of pancreatitis in patients undergoing these higher-risk procedures. Chemoprevention for ERCP-induced pancreatitis appears promising, but needs further critical study with larger patient populations and agents amenable to outpatient use. Fortunately, most ERCP-induced pancreatitis is mild. More severe pancreatitis requires a team approach to management with surgery, radiology, gastroenterology, and other specialists (eg, nephrologist) as indicated participating in the patient's care.

Glut-1 expression and its response to hypoglycemia in the embryonic mouse heart.

The embryonic heart depends on glucose during early organogenesis. Glut-1 functions in constitutive glucose uptake in adult tissues and is the predominant glucose transporter in embryonic and fetal tissues. This study focuses on Glut-1 expression in the heart during normal organogenesis using immunohistochemistry for Glut-1 distribution, Western analysis for Glut-1 protein levels, and reverse transcriptase polymerase chain reaction for Glut-1 mRNA levels. The role of Glut in glucose uptake response to hypoglycemia in the embryonic heart is evaluated using the Glut inhibitor cytochalasin B. Cardiac Glut-1 expression is also evaluated after in vitro hypoglycemic exposure. Glut-1 levels are highest on gestational days 9-10, intermediate on gestational day 10.5, and lowest on gestational days 11.5-13.5 in the normal embryonic heart. Cardiac Glut-1 mRNA levels similarly decline between gestational days 9.5 and gd 13.5. Cytochalasin B produces a dose-dependent decrease in glucose uptake in hearts exposed to hypoglycemia for 30 min or 6 h, implicating Glut in this response. Glut-1 protein expression is unchanged after 2 or 6 h but increased after 12 and 24 h of hypoglycemia in the gestational day 9.5 heart. Thus, Glut-1 expression is prominent in the embryonic heart and is correlated with changes in cardiac glucose requirements during normal organogenesis. Glut activity increases in response to acute hypoglycemia and the expression of Glut-1 increases in response to prolonged hypoglycemia. These results support the importance of Glut-1 during normal cardiogenesis and in response to hypoglycemia in the embryonic heart.

Detection of dengue infection in patients investigated for leptospirosis in Barbados.

The annual incidence of leptospirosis in Barbados is approximately 13 severe cases/100,000. The peak incidence occurs in October to December of each year, coinciding with the months of heaviest rainfall. During the second half of 1995, an epidemic of dengue type 1 infection produced almost 1,000 laboratory-confirmed cases. During the same period, leptospirosis mortality was twice the average, suggesting that some cases of leptospirosis were being misdiagnosed and treated inappropriately. Sera from patients investigated for dengue or leptospirosis were analyzed retrospectively to determine the extent of misdiagnosis. During 1995 and 1996, 31 of 139 and 29 of 93 patients, respectively, were confirmed as having leptospirosis. Sera from the remaining leptospirosis-negative patients were tested for IgM antibodies to dengue virus. During 1995 and 1996, 48 of 108 patients and 21 of 64 patients, respectively, were found to have dengue. In 1997, sera from all patients investigated for leptospirosis were also tested prospectively for IgM antibodies to dengue: 38 of 92 leptospirosis-negative patients (41%) were dengue IgM-positive, while 2 of 25 leptospirosis cases also had serologic evidence suggesting acute dengue infection. A second large outbreak of dengue caused by serotype 2 occurred in 1997. During the 1995 and 1997 dengue epidemics in Barbados, dengue cases outnumbered leptospirosis cases investigated in the leptospirosis diagnostic protocol. During 1997, patients investigated but negative for dengue were also tested for anti-leptospiral IgM: 7.3% (19 of 262) were IgM-positive. Substantial misdiagnosis of both dengue and leptospirosis can occur and greater public awareness and clinical suspicion of the similar presentations of these two diseases are necessary.

Evaluation of two methods for rapid serological diagnosis of acute leptospirosis

OBJECTIVE: To evaluate two rapid assays for serological diagnosis of acute leptospirosis in diagnostic laboratories. DESIGN AND METHODS: 209 specimens were examined from 104 patients admitted to hospital for investigation in a leptospirosis diagnostic protocol. Specimens for serology were taken on days 1 and 4 of the hospital admission. Antibodies were detected using IgM-ELISA, microscopic agglutination (MAT), an IgM-dipstick assay and indirect haemagglutination assay. RESULTS: 51 patients were found to have leptospirosis. The sensitivity of the IgM-dipstick was 98 percent, specificity was 90.6 percent, positive predictive value was 90.9 percent and the negative predictive value was 98 percent. The sensitivity of IHA was 92. percent, specificity was 94.4 percent, positive predictive value was 95.9 percent and negative predictive value was 92.7 percent. The IgM-dipstick assay was positive in 71 percent of the cases in the first sample tested. CONCLUSIONS: Both assays are highly sensitive and specific. Neither requires specialized equipment, and both are suitable for use in diagnostic laboratories.(Au)

Detection of dengue infection in patients investigated for leptospirosis in Barbados

The annual incidence of leptospirosis in Barbados is approximately 13 severe cases/100,000. The peak incidence occurs in October to December of each year, coinciding with the months of heaviest rainfall. During the second half of 1995, the epidemic of dengue type 1 infection produced almost 1.000 laboratory-confirmed cases. During the same period, leptospirosis mortality was twice the average, suggesting that some cases of leptospirosis were being misdiagnosed and treated inappropriately. Sera from patients investigated for dengue or leptospirosis were analyzed retrospectively to determine the extent of misdiagnosis. During 1995 and 1996, 31 of 139 and 29 of 93 patients, respectively, were confirmed as having leptospirosis. Sera from the remaining leptospirosis-negative patients were tested for IgM antibodies to dengue virus. During 1995 and 1996, 48 of 108 patients and 21 of 64 patients, respectively, were found to have dengue. In 1997, sera from all patients investigated for leptospirosis were treated prospectively for IgM antibodies to dengue: 38 of 92 leptospirosis-negative patients (41 percent) were dengue IgM-positive, while 2 of 25 leptospirosis cases also had serologic evidence suggesting acute dengue infection. A second large outbreak of dengue caused by serotype 2 occurred in 1997 dengue epidemics in Barbados, dengue cases outnumbered leptospirosis cases investigated in the leptospirosis diagnostic protocol. During, 1997, patients investigated but negative for dengue were also tested for anti-leptospiral IgM: 7.3 percent (19 of 262) were IgM-positive. Substantial misdiagnosis of both dengue and leptospirosis can occur and greater public awareness and clinical suspicion of the similar presentations of these two diseases are necessary. (AU)

Hexokinase I expression and activity in embryonic mouse heart during early and late organogenesis.

Hexokinase (HK) catalyzes the first step in glucose metabolism, that is, the conversion of glucose to glucose-6-phosphate (G6P). Four HK isoforms have been identified, of which HK-I is predominant in embryonic and fetal tissues. HK-I has been studied in preimplantation embryos and in fetal stages, but little is known about its activity or expression in the early postimplantation embryo. We evaluated HK-I expression, HK-I activity, and glycolytic metabolism in the embryonic mouse heart during early [gestational day (gd) 9.5] and late (gd 13.5) organogenesis. Immunohistochemistry demonstrated that HK-I is localized mainly in the heart at both stages, with stronger expression on gd 13.5. Densitometry after SDS-PAGE/western analysis confirmed higher immunodetectable HK-I protein levels in hearts on gd 13.5 vs gd 9.5. By contrast, RT-PCR demonstrated higher HK-I mRNA expression on gd 9.5 vs gd 13.5. Similarly, cardiac HK-I activity (conversion of glucose to G6P) and glycolysis (conversion of glucose to lactate) were higher on gd 9.5 than on gd 13.5. These results suggest a complex regulation of HK-I expression and activity in the embryonic heart during organogenesis, involving a change in the intrinsic activity of the enzyme with development. HK-I appears to play an important role in glucose metabolism during this critical stage of cardiogenesis.

Expression of glucose-regulated proteins (GRP78 and GRP94) in hearts and fore-limb buds of mouse embryos exposed to hypoglycemia in vitro.

Hypoglycemia, the classic inducer of glucose-related protein (GRP) synthesis, is dysmorphogenic in rodent embryos and detrimentally affects the heart. This study compares GRP induction in a target vs non-target tissue by evaluating GRP expression in hearts and fore-limb buds of mouse embryos following exposure to hypoglycemia in vitro. Gestational day 9.5 embryos were exposed to 2, 6, and 24 h of either mild (80 mg/dl glucose) or severe (40 mg/dl glucose) hypoglycemia using the method of whole-embryo culture. GRP78 increased in a dose- and time-dependent fashion in embryonic hearts exposed to either 40 mg/dl or 80 mg/dl glucose, whereas GRP94 levels increased in hearts only after 24 h of hypoglycemia. In contrast to the heart, GRP induction in fore-limb buds occurred only with GRP78 following the most severe level and duration of hypoglycemia. RT-PCR analysis demonstrated an elevation in GRP78 and GRP94 message levels in embryonic hearts following severe hypoglycemia. However, mRNA levels did not increase in response to mild hypoglycemia. Overall, these data demonstrate the preferential induction of GRPs in the heart as compared to fore-limb buds in mouse embryos exposed to hypoglycemia. Increases in GRP protein levels may be a more reliable biomarker of stress than message levels. However, both tissues and methods should be examined for enhanced biomarker sensitivity.

5-AZA-2'-deoxycytidine-induced dysmorphogenesis in the rat.

5-aza-2'-deoxycytidine (d-AZA) causes temporally related defects in the developing mouse. Treatment of 1.0 mg/kg on gestation day (GD) 8 results in axial skeletal defects; on GD9, cleft palate and vertebral defects; on GD10, hindlimb phocomelia; and on GD11, digital defects. An unusual aspect of d-AZA teratogenicity in mice is that the phocomelia appears to be specific to the hindlimb, and the forelimb is not similarly affected regardless of treatment day. The current study was initiated to evaluate the embryonic response of another species, the rat, to this unique teratogen. Pregnant Sprague Dawley (CD) rats were treated with d-AZA or vehicle control. The compound was administered i.p. on GD9, 10, 11, or 12 to parallel developmental staging of the mouse. The highest dose (1.0 mg/kg) elicited effects indicating increased sensitivity to the compound in the rat as compared to the mouse. GD9 treatment was characterized by massive resorptions; GD10, by a predominance of axial skeletal defects and cleft palate; GD11, by a predominance of forelimb phocomelia and missing ribs; and GD12 by hindlimb phocomelia and forelimb digit defects. These data indicate significant differences in the developmental responses to d-AZA of the mouse and the rat. This may reflect interspecies differences in the temporal expression of genes involved in morphogenesis and/or the methylation patterns of such genes. Molecular data generated in the mouse will be compared to that of the rat to further characterize the developmental dynamics responsible for the interspecies differences. Teratogenesis Carcinog. Mutagen. 19:329-338, 1999.

Enhancement of sterol synthesis by the monoterpene perillyl alcohol is unaffected by competitive 3-hydroxy-3-methylglutaryl-CoA reductase inhibition.

Monoterpenes such as limonene and perillyl alcohol (PA) are currently under investigation for their chemotherapeutic properties which have been tied to their ability to affect protein isoprenylation. Because PA affects the synthesis of isoprenoids, such as ubiquinone, and cholesterol is the end product of the synthetic pathway from which this isoprenoid pathway branches, we investigated the effects of this compound upon cholesterol metabolism in the colonic adenocarcinoma cell line SW480. PA (1 mM) inhibited incorporation of 14C-mevalonate into 21-26 kDa proteins by 25% in SW480 cells. Cholesterol (CH) biosynthesis was assessed by measuring the incorporation of 14C-acetate and 14C-mevalonate into 27-carbon-sterols. Cells treated with PA (1 mM) exhibited a fourfold increase in the incorporation of 14C-acetate but not 14C-mevalonate into cholesterol. Mevinolin (lovastatin), an inhibitor of 3-hydroxy-3-methylglutaryl-CoA(HMG-CoA) reductase, at 2 microM concentration, inhibited CH synthesis from 14C-acetate by 80%. Surprisingly, concurrent addition of mevinolin and PA did not significantly alter the stimulatory effects of PA. As observed differences in 14C-acetate and 14C-mevalonate precursor labeling could indicate PA affects early pathway events, the effects of this monoterpene on HMG-CoA reductase activity were evaluated. Unexpectedly, 1 mM PA did not stimulate activity of this enzyme. Consistent with its action as a reversibly bound inhibitor, in washed microsomes, 2 microM mevinolin pretreatment increased reductase protein expression causing a 12.7 (+/- 2.4)-fold compensatory HMG-CoA reductase activity increase; concurrent treatment with 1 mM PA attenuated this to a 5.3 (+/- 0.03)-fold increase. Gas chromatographic analysis confirmed CH was the major lipid present in the measured thin-layer chromatography spot. Since 14C-acetate incorporation into free fatty acid and phospholipid pools was not significantly affected by PA treatment, nonspecific changes in whole acetate pool sizes were not indicated. Because increases in endogenous CH synthesis should result in compensatory changes in exogenous sterol utilization, the effects of PA upon low density lipoprotein (LDL) receptor activity were evaluated. Consistent with the observed increases in CH synthesis, 1 mM PA decreased 125I-LDL internalization to 50% of the fetal bovine serum control; concurrent addition of 2 microM mevinolin attenuated this effect to a reduction of 80% of the control value. Data suggest that in certain colonic tumor cells PA strongly affects cholesterol metabolism via a mechanism of action that is insensitive to the HMG-CoA reductase inhibitor mevinolin.

Evaluation of four methods for detection of immunoglobulin M antibodies to dengue virus.

Dengue has become hyperendemic in many islands of the Caribbean region. The performance in a diagnostic laboratory of four commercial assays for detection of immunoglobulin M (IgM) antibodies was evaluated. Sera from 62 patients with dengue virus infection were studied. These included 18 patients from whom dengue virus type 2 was isolated in a 1997 outbreak (specimens collected a mean of 14 days after onset of symptoms), 8 patients with dengue hemorrhagic fever (mean time after onset, 11 days), and 36 patients in whom dengue was previously confirmed by serology (mean time after onset, 10 days). Thirty serum specimens from blood donors in a country where dengue is not endemic were used as negative controls. The methods evaluated were two IgM-capture enzyme-linked immunosorbent assays (ELISA) (MRL Diagnostics, Cypress, Calif., and PanBio, Queensland, Australia), a dot ELISA dipstick assay (Integrated Diagnostics, Baltimore, Md.), and a rapid immunochromatographic assay for dengue IgG and IgM (PanBio IC). IgG antibodies were also detected by an ELISA method (MRL Diagnostics). The sensitivities of the four assays were as follows: MRL Diagnostics IgM ELISA, 98.4%; PanBio IgM ELISA, 85.5%; Integrated Diagnostics IgM dot ELISA, 96. 8%; and PanBio IC, 83.9%. The specificities of all tests were 100%. Evidence of secondary dengue was found in all patients with dengue hemorrhagic fever and in 83% of the remaining patients. The MRL Diagnostics IgM ELISA appears to be more sensitive than the PanBio IgM ELISA, and this may be significant when IgM titers are low, particularly in patients with secondary dengue infections. The dot ELISA dipstick assay is equally sensitive and may be more appropriate for use in laboratories with lower workloads.

Endoscopic band ligation of Dieulafoy's lesion: report of two cases and review of the literature.

Two cases of endoscopic band ligation as lone therapy for Dieulafoy's lesions are presented. Neither patient has experienced further gastrointestinal bleeding; one patient has been followed for 27 months. Endoscopic band ligation is an alternative and attractive treatment modality for Dieulafoy's lesions.