CT-guided percutaneous marking of small pulmonary nodules with [99mTc]Tc-Macrosalb is very accurate and allows minimally invasive lung-sparing resection: a single-centre quality control.

PURPOSE: The detection of small lung nodules in thoracoscopic procedure is difficult when the lesions are not located within the outer border of the lung. In the case of ground-glass opacities, it is often impossible to palpate the lesion. Marking lung nodules using a radiotracer is a known technique. We analysed the accuracy and safety of the technique and the potential benefits of operating in a hybrid operating room. METHODS: 57 patients, including 33 (58%) females with a median age of 67 years (range 21-82) were included. In 27 patients, we marked and resected the lesion in a hybrid room. In 30 patients, the lesion was marked at the department of radiology the day before resection. [99mTc]Tc-Macrosalb (Pulmocis®) was used at an activity of 1 MBq in the hybrid room and at an activity of 3 MBq the day before to get technical feasible results. Radioactivity was detected using the Neoprobe® detection system. RESULTS: Precise detection and resection of the nodules was possible in 95% of the lesions and in 93% of the patients. Complete thoracoscopic resection was possible in 90% of the patients. Total conversion rate was 10%, but conversion due to failure of the marking of the nodule was observed in only 5% of the patients. Histology revealed 28 (37%) primary lung cancers, 24 (32%) metastases and 21 (28%) benign lesions. In 13 (23%) patients, minor complications were observed. None of them required additional interventions. CONCLUSION: The radio-guided detection of small pulmonary nodules is very accurate and safe after CT-guided injection of [99mTc]Tc-Macrosalb. Performing the operation in a hybrid room has several logistic advantages and allows using lower technetium-99m activities. The technique allows minimally invasive lung sparing resection and prevents overtreatment of benign and metastatic lesions.

The atomic structure of polar and non-polar InGaN quantum wells and the green gap problem.

We have used high resolution transmission electron microscopy (HRTEM), aberration-corrected quantitative scanning transmission electron microscopy (Q-STEM), atom probe tomography (APT) and X-ray diffraction (XRD) to study the atomic structure of (0001) polar and (11-20) non-polar InGaN quantum wells (QWs). This paper provides an overview of the results. Polar (0001) InGaN in QWs is a random alloy, with In replacing Ga randomly. The InGaN QWs have atomic height interface steps, resulting in QW width fluctuations. The electrons are localised at the top QW interface by the built-in electric field and the well-width fluctuations, with a localisation energy of typically 20meV. The holes are localised near the bottom QW interface, by indium fluctuations in the random alloy, with a localisation energy of typically 60meV. On the other hand, the non-polar (11-20) InGaN QWs contain nanometre-scale indium-rich clusters which we suggest localise the carriers and produce longer wavelength (lower energy) emission than from random alloy non-polar InGaN QWs of the same average composition. The reason for the indium-rich clusters in non-polar (11-20) InGaN QWs is not yet clear, but may be connected to the lower QW growth temperature for the (11-20) InGaN QWs compared to the (0001) polar InGaN QWs.

Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour.

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (~5 nm) interfacial layer of uranium hydride was observed at the oxide-metal interface. Exposure to deuterated water vapour produced an equivalent deuteride signal at the metal-oxide interface, confirming the hydride as originating via the water vapour oxidation mechanism. Hydroxide ions were detected uniformly throughout the oxide, yet showed reduced prominence at the metal interface. These results support a proposed mechanism for the oxidation of uranium in water vapour environments where the transport of hydroxyl species and the formation of hydride are key to understanding the observed behaviour.

Neutrophils negatively regulate induction of mucosal IgA responses after sublingual immunization.

Induction of mucosal immunoglobulin-A (IgA) capable of providing a first line of defense against bacterial and viral pathogens remains a major goal of needle-free vaccines given via mucosal routes. Innate immune cells are known to play a central role in induction of IgA responses by mucosal vaccines, but the relative contribution of myeloid cell subsets to these responses has not firmly been established. Using an in vivo model of sublingual vaccination with Bacillus anthracis edema toxin (EdTx) as adjuvant, we examined the role of myeloid cell subsets for mucosal secretory IgA responses. Sublingual immunization of wild-type mice resulted in a transient increase of neutrophils in sublingual tissues and cervical lymph nodes. These mice later developed Ag-specific serum IgG responses, but not serum or mucosal IgA. Interestingly, EdTx failed to increase neutrophils in sublingual tissues and cervical lymph nodes of IKKß(ΔMye) mice, and these mice developed IgA responses. Partial depletion of neutrophils before immunization of wild-type mice allowed the development of both mucosal and serum IgA responses. Finally, co-culture of B cells with neutrophils from either wild-type or IKKß(ΔMye) mice suppressed secretion of IgA, but not IgM or IgG. These results identify a new role for neutrophils as negative regulators of IgA responses.

Three cases of fatal paramethoxyamphetamine overdose.

Two recent cases of death due to paramethoxyamphetamine (PMA), a methoxylated phenylethylamine derivative, are described and compared with a previous PMA death that occurred in this province in 1985. The deceased were 18 or 19 years of age and were reported to have ingested either methylenedioxymethamphetamine (MDMA, Ecstasy) or methylenedioxyamphetamine (MDA) prior to their deaths. Concentrations of PMA were measured in both peripheral and heart blood samples using gas chromatography equipped with a nitrogen-phosphorus detector. PMA results in the most recent cases were 0.6 mg/L and 1.3 mg/L in the peripheral blood samples, and corresponding heart blood samples were 0.7 mg/L and 2.3 mg/L, respectively. In the 1985 case, the femoral blood concentration was 0.6 mg/L, and the heart blood concentration was 0.8 mg/L. Significant differences between heart and peripheral blood concentrations were observed in two of the three cases, which may indicate the potential for postmortem redistribution of PMA.

Monolayers of derivatized poly(L-lysine)-grafted poly(ethylene glycol) on metal oxides as a class of biomolecular interfaces.

We report on the design and characterization of a class of biomolecular interfaces based on derivatized poly(l-lysine)-grafted poly(ethylene glycol) copolymers adsorbed on negatively charged surfaces. As a model system, we synthesized biotin-derivatized poly(l-lysine)-grafted poly(ethylene glycol) copolymers, PLL-g-[(PEGm)((1-x)) (PEG-biotin)(x)], where x varies from 0 to 1. Monolayers were produced on titanium dioxide substrates and characterized by x-ray photoelectron spectroscopy. The specific biorecognition properties of these biotinylated surfaces were investigated with the use of radiolabeled streptavidin alone and within complex protein mixtures. The PLL-g-PEG-biotin monolayers specifically capture streptavidin, even from a complex protein mixture, while still preventing nonspecific adsorption of other proteins. This streptavidin layer can subsequently capture biotinylated proteins. Finally, with the use of microfluidic networks and protein arraying, we demonstrate the potential of this class of biomolecular interfaces for applications based on protein patterning.

Histological changes in the human anterior cruciate ligament after rupture.

BACKGROUND: Four phases in the response to injury of the ruptured human anterior cruciate ligament are observed histologically; these include an inflammatory phase, an epiligamentous repair phase, a proliferative phase, and a remodeling phase. One objective of this study was to describe the histological changes that occur in the ruptured human anterior cruciate ligament during these phases. Myofibroblast-like cells that contain alpha-smooth muscle actin are present in the midsubstance of the intact human anterior cruciate ligament. A second objective of this study was to determine whether an increased number of myofibroblast-like cells is found in the midsubstance of the ruptured human anterior cruciate ligament because it was thought that those cells might be responsible in part for the retraction of the ruptured anterior cruciate ligament. In the early phase of this study, it was found that the number of myofibroblast-like cells in the midsubstance of the ruptured anterior cruciate ligament was actually decreased, and this hypothesis was abandoned. During the epiligamentous repair phase, synovial tissue was formed that covered the ends of the ruptured anterior cruciate ligament. Most of the synovial lining cells were myofibroblast-like cells that contained alpha-smooth muscle actin. The primary objective of this study was to determine the location and the characteristics of the alpha-smooth muscle actin-containing myofibroblast-like cells that appear in the human anterior cruciate ligament following rupture. METHODS: Twenty-three ruptured and ten intact human anterior cruciate ligaments were evaluated for cellularity, nuclear morphology, blood vessel density, and percentage of cells containing a contractile actin isoform, alpha-smooth muscle actin. The histological features of the synovial and epiligamentous tissues were also described. RESULTS: At no time after rupture was there evidence of tissue-bridging between the femoral and tibial remnants of the anterior cruciate ligament. The ruptured ligaments demonstrated a time-dependent histological response, which consisted of inflammatory cell infiltration up to three weeks, gradual epiligamentous repair and resynovialization between three and eight weeks, and neovascularization and an increase in cell number density between eight and twenty weeks. Compared with the intact ligaments, there was a decrease in the percentage of myofibroblast-like cells containing alpha-smooth muscle actin within the remnant of the ligament. However, many of the epiligamentous and synovial cells encapsulating the remnants contained alpha-smooth muscle actin. CONCLUSIONS: After rupture, the human anterior cruciate ligament undergoes four histological phases, consisting of inflammation, epiligamentous regeneration, proliferation, and remodeling. The response to injury is similar to that reported in other dense connective tissues, with three exceptions: formation of an alpha-smooth muscle actin-expressing synovial cell layer on the surface of the ruptured ends, the lack of any tissue bridging the rupture site, and the presence of an epiligamentous reparative phase that lasts eight to twelve weeks. Other characteristics reported in healing dense connective tissue, such as fibroblast proliferation, expression of alpha-smooth muscle actin, and revascularization, also occur in the ruptured human anterior cruciate ligament. CLINICAL RELEVANCE: Unlike extra-articular ligaments that heal after injury, the human intra-articular anterior cruciate ligament forms a layer of synovial tissue over the ruptured surface, which may impede repair of the ligament. Moreover, a large number of cells in this synovial layer and in the epiligamentous tissue express the gene for a contractile actin isoform, alpha-smooth muscle actin, thus differentiating into myofibroblasts. These events may play a role in the retraction and lack of healing of the ruptured anterior cruciate ligament.

Reconstruction of Achilles tendon defect with a free quadriceps bone-tendon graft without anastamosis.

We report a method of Achilles tendon reconstruction using a free quadriceps bone-tendon graft. The patient had a prior repair of a re-ruptured Achilles tendon, following which he developed massive necrosis of his skin and Achilles tendon leaving a 10 cm defect. First stage reconstruction consisted of soft tissue coverage of the skin defect with a sural fasciocutaneous flap. Reconstruction of the Achilles tendon followed, with the patellar bone block fixed to the calcaneus and the quadriceps tendon sutured proximally.

Suprascapular neuropathy. Results of non-operative treatment.

We retrospectively reviewed the results of non-operative treatment of suprascapular neuropathy in fifteen patients seen between November 1983 and February 1991. The clinical diagnosis was confirmed with electrodiagnostic studies. The treatment consisted of a program of physical therapy to improve the range of motion of the shoulder and to strengthen the surrounding muscles. The average duration of follow-up was three years and eleven months (range, one year to eight years and ten months). The latest evaluation included electrodiagnostic studies of the affected extremity and dynamic isokinetic testing of both upper extremities. The result was excellent for five patients and good for seven. The three remaining patients had operative treatment because of persistent symptoms; one of these patients had an excellent result, one had a good result, and one had a poor result. The results suggest that, in the absence of a well defined lesion producing mechanical compression of the suprascapular nerve, suprascapular neuropathy should be treated non-operatively.

Rapid immune activation by CpG motifs in bacterial DNA. Systemic induction of IL-6 transcription through an antioxidant-sensitive pathway.

Unmethylated CpG dinucleotides (CpG motif) in bacterial DNA or synthetic oligodeoxynucleotides (CpG DNA) rapidly activate murine B cells to secrete IL-6 and IgM, as well as to proliferate. Within 30 min after CpG DNA stimulation in vivo, IL-6 mRNA levels were increased in liver, spleen, and thymus cells. Serum IL-6 protein was markedly increased within 1 h of stimulation. Treatment of a B cell line with CpG DNA led to an increase in the transcriptional activity of the IL-6 promoter. This CpG DNA-induced IL-6 production was not mediated via either a protein kinase C (PKC)-, protein kinase A (PKA)-, or nitric oxide (NO.)-dependent pathway but was inhibited by an antioxidant. In addition, the level of intracellular reactive oxygen species was increased within 20 min after CpG DNA, but not control non-CpG DNA, treatment. These results suggest that CpG DNA-induced IL-6 production is mediated through a reactive oxygen intermediate-dependent pathway. CpG DNA-mediated IL-6 production was enhanced by simultaneous signals delivered through the Ag receptor. The addition of neutralizing Abs against IL-6 to B cell cultures along with CpG oligodeoxynucleotides essentially abolished the CpG DNA-induced increased IgM secretion but had no significant effect on the B cell proliferation induced by the CpG motif. Our results suggest that the induction of IL-6 expression in response to CpG motifs in bacterial DNA may be an important immune defense mechanism that facilitates a rapid response to microbial infection.

Physician and patient prevention practices in NIDDM in a large urban managed-care organization.

OBJECTIVE: To examine physician and patient adherence to prevention guidelines in non-insulin-dependent diabetes mellitus (NIDDM) with attention to possible differences in adherence by patient race or ethnicity. RESEARCH DESIGN AND METHODS: We performed a cross-sectional chart review study of prevention practices, complications, and risk factors in 378 NIDDM patients (at least 5 years known duration) who were Permanente Medical Care Program, Oakland, CA. There were 232 blacks, 81 whites, 29 Hispanics, and 36 members of other races/ethnicities. RESULTS: Age- and duration-adjusted prevalence of 14 complications was low and, with the exception of diabetic retinopathy, did not differ significantly by race. An eight-point prevention score that reflected recommended use of glucose, HbA1c, high-density lipoprotein/total cholesterol, blood pressure and proteinuria testing, ophthalmology a and foot examinations, and diabetes education during a 2-year period did not differ by race/ethnicity (P = 0.36). The mean score (4.9 +/- 1.6) indicated that on average, five of eight guidelines were performed appropriately. Compliance was poorest for annual proteinuria checks (32.2%). No differences were noted by race/ethnicity in referrals to ophthalmology, weight reduction, or smoking cessation or in missed appointments or failure to keep referral visits. CONCLUSIONS: The absence of racial differences in either prevention practices or complication rates in this insured prepaid setting suggests that improved access to preventive services may be effective in reducing such differences nationally. However, adherence to several guidelines was < or = 50%, indicating that physicians are not sufficiently convinced of the necessity for these prevention measures.

Proximal tibial osteotomy with compression plate fixation for tibia vara.

A surgical technique for the accurate intraoperative correction of tibia vara deformities with maintainence of postoperative alignment is presented. This was a retrospective study of 13 knees of nine patients with tibia vara deformities treated by proximal tibial and fibular osteotomies using compression-plate fixation. Average age of the patients was 9 + 1 years, with a range of 3 + 1 to 14 + 11 years. The average preoperative deformity was 20 degrees of varus with a range of 15-36 degrees. Average follow-up was 3 + 3 years, with a range of 2 to 4 + 1 years. All patients had intraoperative correction to an average valgus of 5 degrees (range 4-8 degrees valgus), with an overall valgus correction of 25 degrees (range 20-40 degrees). There was one reoperation for unilateral recurrence of deformity in a child who progressed from stage III to stage VI postoperatively. Proximal tibial osteotomy with compression-plate fixation provides an accurate and reliable method for the correction of multiplanar deformities in children and adolescents.

Ovulatory and endocrine responses after active immunization of gilts against a synthetic fragment of bovine inhibin.

The objective of this study was to determine whether neutralizing endogenous inhibin would affect ovulation rate and serum concentrations of FSH, LH, estradiol-17 beta, and progesterone in gilts. At wk 0, during their second postpubertal estrous cycle, gilts (195 +/- 2.4 d of age) were given a primary immunization against the 1-26 gly-tyr NH-terminal amino acid sequence of bovine inhibin-alpha conjugated to human alpha globulin (INH; n = 10) or against human alpha globulin alone (control; n = 10). The primary immunization mixed with Freund's complete adjuvant contained .915 mg of the inhibin peptide. Booster immunizations in Freund's incomplete adjuvant contained .3 and .183 mg of the inhibin peptide and were given at wk 8 and 12, respectively. Free, unconjugated inhibin was given to INH gilts at 16 wk. Blood samples for determination of hormones were collected every 4 h beginning on d 15 of the first estrous cycle beyond wk 16 (first cycle) and continuing until d 5 of the second estrous cycle following wk 16 (second cycle). Ovulation rate was estimated by laparoscopy during the second cycle. Antibody titers were estimated by determining the percentage of [125I]-INH bound by serum diluted 1:4,000. The antibody titers were 17 +/- 2, 22 +/- 3, and 9 +/- 1% at wk 9, 17, and 23 for INH gilts, respectively, and 0% at all times for control gilts. Duration of three consecutive estrous cycles terminating with the first experimental cycle did not differ between treatments (INH, 20.7 +/- .3 vs control, 20.4 +/- .3 d).(ABSTRACT TRUNCATED AT 250 WORDS)

Active immunization of heifers against a synthetic fragment of bovine inhibin.

Two experiments were conducted in cyclic beef heifers to determine whether active immunization against bovine inhibin alpha 1-26 Gly-Tyr (bINH) affected follicular dynamics, hormone concentration or ovulation rate. In Expt 1, heifers (n = 9) were actively immunized against bINH conjugated to human alpha globulins (HAG) using bis-diazotized benzidine in non-ulcerative Freund's adjuvant (NUFA; primary on day 0; booster injections on days 53, 84 and 116 using conjugated bINH and on days 176 and 366 using unconjugated bINH; ten heifers were used as controls). Ovaries were examined daily using ultrasound scanning (days 70-155 and 384-391) and corresponding blood samples were collected for bINH antibody titre, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and oestradiol determinations. Four treated and four control heifers were injected with 10 micrograms gonadotrophin-releasing hormone (GnRH) on day 386 (day 2 of the oestrous cycle). Although bINH-immunized heifers had variable antibody titres ranging from 4 to 50% I125-labelled bINH bound to serum diluted 1:2000, ovulation rate was unaffected. In oestrous cycles with three dominant follicles, the ovulatory follicles grew faster (2.5 +/- 0.2 versus 1.6 +/- 0.3 mm day-1; mean +/- SEM), had shorter durations of growth (5.7 +/- 0.8 versus 9.6 +/- 1.6 days) and duration of detection (7.5 +/- 0.8 versus 12.0 +/- 2.4 days) in immunized heifers. Mean concentrations of FSH, LH and oestradiol were unaltered in most cases during oestrous cycles in bINH-immunized compared with control heifers. There was no significant difference in the percentage increase in FSH or LH, after GnRH injection, between control and immunized heifers. As ovulation rate was unaltered in the first experiment, a second similar study was designed using a different immunization protocol. In Expt 2, heifers were immunized with bINH conjugated to human serum albumin using glutaraldehyde with the following doses: 0.0 (control; n = 7), 0.33 (n = 7), 1.0 (n = 8) and 3.0 (n = 7) mg. Three booster immunizations were given 33, 66 and 209 days after primary immunization. Immunization increased the number of oestrous cycles with multiple ovulations (42 of 132 (32%) oestrous cycles examined) compared with controls (1 of 30 (3.3%) oestrous cycles examined). Neither titre nor ovulation rate was affected by dose of bINH used. In summary, following bINH immunization, ovulation rate was not increased despite changes in follicular dynamics in Expt 1, but was increased in 32% of oestrous cycles in Expt 2.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunoneutralization of inhibin suppresses reproduction in female mink.

This study determined whether immunoneutralization of inhibin affected gonadotropin secretion, embryo development, and ovarian function in mink. Adult female mink (n = 10) were immunized with bovine inhibin alpha 1-26 gly-tyr (bINH, 100 micrograms) conjugated to human alpha globulins (HAG), or with HAG alone (n = 10, controls), mixed with Freund's complete adjuvant. A series of five boosters containing bINH or HAG were then administered during a 2-yr period. Titers of bINH antibodies and serum concentrations of gonadotropins were determined for each breeding season in 1990 and 1991. Each year after whelping, we determined gestation length; sex, number, and weight of live and dead kits per litter at birth; and number and weight of kits per litter 3 wk after whelping. Results were pooled for statistical analysis. Bovine INH antibody titers (percent 125I-bINH bound to serum diluted 1:8000) were 53 +/- 3% vs. 2 +/- 0.6%, and serum concentrations of FSH were higher (p < 0.05) in bINH-immunized mink compared with controls (144 +/- 23 vs. 67 +/- 12 ng/ml). However, number (3.8 +/- 0.2 vs. 5 +/- 0.4) and weight (8 +/- 0.3 vs. 9.7 +/- 0.4 g) of kits per litter at birth and number of kits per litter alive 3 wk after birth (2.9 +/- 0.5 vs. 4.7 +/- 0.4) were lower (p < 0.05) in bINH-immunized mothers compared with controls. During the nonbreeding season in 1991, a single injection of hCG (100 IU) was administered to bINH-immunized and control mink; 24 h later blood was sampled, and organ weights were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoneutralization of inhibin modifies hormone secretion and sperm production in bulls.

The objective of this study was to examine the role of endogenous inhibin in the regulation of FSH, LH, and testosterone secretion and sperm production in bulls. Bulls were actively immunized against bovine inhibin alpha 1-26 gly-tyr (bINH) conjugated to human alpha globulin (HAG) or HAG alone (controls) and emulsified in Freund's complete adjuvant. Primary immunization was at 14 wk of age, followed by booster immunizations in Freund's incomplete adjuvant at 28, 30, and 34 wk of age. Ten days after each booster immunization, scrotal circumferences and body weights were measured, and blood was sampled for determination of bINH antibody titer. Ten days after the third booster, blood was sampled at 1-h intervals for 8 h to quantify serum concentrations of FSH, LH, and testosterone. After this blood sampling period, bulls were castrated and testicular sperm production was determined. Serum diluted 1:4,000 from bINH-immunized bulls bound 36%, 52%, and 53% of radioiodinated bINH after the first, second, and third boosters, respectively. Serum from controls bound less than 1% radioiodinated bINH. After the third booster, serum concentrations of FSH and testosterone were increased (p less than 0.05) and LH concentrations were decreased (p less than 0.001) in bINH-immunized bulls compared with controls. After the third booster, daily sperm production per gram of testicular parenchyma was increased (p less than 0.05) in bINH-immunized bulls compared with controls. Scrotal circumferences and body weights were similar between treatment groups throughout the experiment. We concluded that inhibin has a role in regulation of secretion of gonadotrophins and testosterone and testicular sperm production, but not testicular growth, in bulls.(ABSTRACT TRUNCATED AT 250 WORDS)

Concentrations of inhibins and steroids in follicular fluid during development of dominant follicules in heifers.

The objective of this study was to examine changes in intrafollicular concentrations of inhibins and steroids in heifers during growth of dominant follicles. To obtain dominant ovulatory follicles, heifers received injections of prostaglandin (PG) on Day 9 of an estrous cycle and were ovariectomized (OVX) 0, 24, 48, 60, or 72 h after injection. To obtain dominant nonovulatory follicles, heifers were OVX on Day 3, 6, or 9 of a cycle. Follicular size was determined, follicular fluid (FF) was collected from follicles 6 mm or greater in diameter, and RIA was used to quantify concentrations of inhibins, estradiol, and progesterone in FF. During growth of dominant ovulatory follicles, concentrations of estradiol and progesterone increased, whereas inhibins decreased when compared with dominant follicles on Day 9 before PG treatment. Concentrations of inhibins were inversely correlated with size and concentrations of estradiol in dominant ovulatory follicles. As dominant nonovulatory follicles increased in size, concentrations of inhibins, estradiol, and progesterone increased. Concentrations of inhibins were positively correlated with size and with progesterone concentrations in dominant nonovulatory follicles. Concentrations of inhibins were greater in dominant nonovulatory follicles than in atretic follicles. In summary, intrafollicular concentrations of inhibins decreased during growth of dominant ovulatory follicles, but increased during growth of dominant nonovulatory follicles. Because of the well-known suppressive action of inhibins on FSH secretion, we hypothesize that inhibins are involved in growth and atresia of dominant follicles during the bovine estrous cycle.

Effect of histone H2A on progesterone production by bovine luteal cells.

Histone H2A competitively inhibits binding of GnRH to high affinity rat ovarian receptor sites and blocks gonadotropin-stimulated steroid and cAMP accumulation during culture of rat granulosal or luteal cells. The objective of our study was to examine the progesterone suppressive effects of histone H2A on bovine luteal cells. In the first study, luteal cells were treated at Time = 0 h with a partially purified preparation of bovine ovarian histone H2A (3 ng GnRH equivalents, 800 micrograms protein), equivalent amounts of GnRH (3 ng), or BSA (800 micrograms) and incubated for a total of 4 h. At Time = 2 h, cells were treated with 5 ng bovine LH (bLH) or with medium. Histone H2A completely blocked both basal and LH-induced accumulation of progesterone compared with untreated cultures or cultures treated with bLH. Neither BSA nor GnRH suppressed LH-induced progesterone accumulation. In the second study, histone H2A was added to cultures at Time = 0 h and bovine luteal cells were cultured for 8 h. After 2 h of treatment, histone H2A (3 ng GnRH equivalents) was removed from selected cultures and replaced with fresh medium. Four hours later cultures were treated with 5 ng bLH or medium. LH treatment of cultures from which histone H2A had been removed resulted in an increase in accumulation of progesterone compared with control cultures treated throughout the treatment period with histone H2A. The third study examined the effect of 9-181 pg GnRH equivalents (1.7-34 micrograms protein) of a highly purified preparation of bovine ovarian histone H2A on basal and LH-induced progesterone production during 2 or 3 h of culture.(ABSTRACT TRUNCATED AT 400 WORDS)

Response of the bovine corpus luteum to increased secretion of luteinizing hormone induced by exogenous gonadotropin releasing hormone.

Two experiments were conducted to investigate the response of the bovine corpus luteum to surges of luteinizing hormone (LH) induced by natural gonadotropin-releasing hormone (GnRH) administered twice during the same estrous cycle. In experiment 1, eight mature beef cows, each cow serving as her own control, were injected intravenously (iv) with saline on days 2 and 8 of the cycle (day of estrus = day 0 of the cycle), then with 100 micrograms GnRH on days 2 and 8 of the subsequent cycle. Jugular blood samples were taken immediately prior to an injection and at 15, 30, 45, 60, 120 and 240 min postinjection, to quantitate changes in serum luteinizing hormone. Blood was also collected on alternate days after an injection until day 16 of the cycle, to characterize changes in serum progesterone concentrations. Although exogenous GnRH caused release of LH on days 2 and 8 of the cycle, the quantity of LH released was greater on day 8 (P less than .025). Serum levels of progesterone after treatment with GnRH on day 8 of the cycle did not differ significantly from those observed during the control cycles of the heifers. Because exposure of the bovine corpus luteum to excess LH, induced by GnRH early during the estrous cycle, causes attenuated progesterone secretion during the same cycle, these data suggest that a second surge of endogenous LH may ameliorate the suppressive effect of the initial release of LH on luteal function. Duration of the estrous cycle was not altered by treatment (control, 20.4 +/- .5 vs. treated, 20.4 +/- .4 days).(ABSTRACT TRUNCATED AT 250 WORDS)