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Biomedical subjects

G D Smith

Publications and source records attributed to G D Smith.

At least 271 records · Page 15Linked to original sources
PubMed1996

Cardiovascular and catecholamine changes induced by supine exercise and upright posture in vasovagal syncope. Comparisons with normal subjects and subjects with sympathetic denervation.

The haemodynamic and catecholamine responses to supine leg exercise were studied in vasovagal syncope (n = 10), pure autonomic failure (n = 10) and in control (n = 10) subjects. With exercise, blood pressure increased in controls; with a smaller rise in vasovagal syncope, and a substantial fall in pure autonomic failure. Heart rate increased similarly in controls and vasovagal syncope, but less in pure autonomic failure. The increase in cardiac index was less in controls and pure autonomic failure than vasovagal syncope; the fall in systemic vascular resistance was greatest in pure autonomic failure, but also fell more in vasovagal syncope than controls. Plasma noradrenaline levels increased in controls; with a smaller rise in vasovagal syncope and no increase in pure autonomic failure. Plasma adrenaline levels increased in vasovagal syncope only. The blood pressure responses to standing before and after exercise were similar in controls and vasovagal syncope, with no postural blood pressure fall; in pure autonomic failure there was a greater postural blood pressure fall post exercise. In conclusion, with supine exercise, blood pressure rose in controls and vasovagal syncope, and fell in pure autonomic failure. Systemic vascular resistance fell more in vasovagal syncope and pure autonomic failure, than controls. Noradrenaline responses differed and adrenaline rose in vasovagal syncope only. Standing post exercise did not induce syncope in vasovagal syncope, but increased postural hypotension in pure autonomic failure. There are clear differences in response to exercise in vasovagal syncope and pure autonomic failure. The differences between vasovagal syncope and control subjects suggest an underlying abnormality which may predispose to vasodepression in subjects with vasovagal syncope.

Adult↗
PubMed1996

Sperm motility development in the epididymis is associated with decreased glycogen synthase kinase-3 and protein phosphatase 1 activity.

Immotile bovine caput epididymal sperm contain levels of protein phosphatase activity twofold higher than do mature motile caudal sperm. Comparison of the inhibition profiles of endogenous phosphatase activities detected by okadaic acid (OA) and calyculin A (CA) revealed a pattern consistent with the predominance of a type 1 protein phosphatase (PP1). Immunoblot analysis identified PP1 gamma 2 (the testis-specific isoform of PP1) as the only PP1 isoform in sperm and showed little protein phosphatase 2A (PP2A). In addition, of the known PP1 inhibitors, i.e., DARPP-32, inhibitor 1 (I1), and inhibitor 2 (I2), only I2-like activity was detected in sperm. Inhibition of PP1 by the heat-stable I2-like activity purified from sperm could be reversed with purified glycogen synthase kinase-3 (GSK-3). Furthermore, sperm extracts contain an inactive complex of PP1 and I2 (termed PP1I) that could also be activated by purified GSK-3. The presence of GSK-3 in sperm was demonstrated by activation of purified PP1I, and quantitation revealed that immotile caput sperm contained sixfold higher GSK-3 activity than motile caudal sperm. Immunoblot analysis confirmed the expression of GSK-3 in sperm and revealed the occurrence of both the alpha and beta isoforms. Our findings suggest that the higher PP1 activity measured in immotile sperm, presumably due to higher GSK-3 activity, is responsible for holding motility in check. This conclusion was supported by the observation that the phosphatase inhibitors OA and CA, at micromolar and nanomolar levels, respectively, were able to induce motility in completely immotile bovine caput epididymal sperm and to stimulate the kinetic activity of mature caudal sperm. The intrasperm levels of cAMP, pH, and calcium were unaltered by treatment with these inhibitors. The results suggest a biochemical basis for the development and regulation of sperm motility and a possible physiological role for the PP1/I2/GSK-3 system.

Amino Acid Sequence↗
PubMed1996

Primate sperm contain protein phosphatase 1, a biochemical mediator of motility.

Sperm motility initiation, capacitation, and hyperactivation are modulated by an interplay of intracellular Ca2+, cAMP, and pH. Mechanisms by which these mediators alter sperm function have not been elucidated but may involve reversible alterations in regulatory protein phosphorylation. Studies were designed 1) to investigate the influence of the protein phosphatase (PP) inhibitor calyculin A (CA) on human sperm motility and 2) to characterize the CA-sensitive PP and its endogenous regulators in human and rhesus monkey sperm. CA (50 nM) treatment of human sperm resulted in an increase in percentage motility and an acceleration in mean path velocity. Inhibition of either protein phosphatase-1 (PP1) or protein phosphatase-2A (PP2A) could be responsible for this motility stimulation, since both of these phosphatases are sensitive to nanomolar quantities of CA. PP activity in human (n = 4) and rhesus monkey (n = 4) sperm sonicates was measured using [32P]-phosphorylase-a, the preferred substrate for PP1 and PP2A, in the absence of divalent cations. Human (6.2 +/- 4.5 x 10(-2) mU/10(6) sperm) and monkey (4.3 +/- 0.8 x 10(-2) mU/10(6) sperm) sonicates contained activity tentatively identified as PP1 on the basis of inhibition profiles in okadaic acid (OA) and CA. Western blot analysis with antibodies against various isoforms of PP1 subsequently documented the presence of PP1 gamma 2 in human and monkey sperm. PP1 activity in most tissues is regulated by the heat-stable inhibitors I1 or I2. Sperm sonicates contained inhibitor activity similar to I2 as well as glycogen synthase kinase-3 (GSK-3) activity, which is involved in the activation of the PP1-I2 complex. These results indicate, for the first time, that human and rhesus monkey sperm contain PP1 and regulators of PP1 and that inhibition of PP1 activity by CA can enhance motility.

Adult↗
PubMed1996

Immunolocalization of tissue inhibitor of metalloproteinases-1 within ovine periovulatory follicular and luteal tissues.

In previous studies, tissue inhibitor of metalloproteinases (TIMP)-1 mRNA increased in follicular tissue after the preovulatory gonadotropin surge and was expressed in luteal tissue. However, the localization of TIMP-1 protein within ovine periovulatory follicular and luteal tissues is unknown. The objectives of the present study were to 1) localize TIMP-1 within follicles collected before and after a preovulatory gonadotropin surge and within Day 3 and Day 10 corpora lutea (CL), 2) determine whether TIMP-1 was colocalized to Day 10 luteal cells with oxytocin or TIMP-2, and 3) determine whether TIMP-1 was present within secretory granules of large luteal cells. Ovaries were removed from ewes before (presurge; n = 4) or 12-14 h after (postsurge; n = 5) an LHRH-induced gonadotropin surge (36 h following PGF2 alpha-induced luteolysis; objective 1). Additionally, ovaries containing CL were collected on Days 3 (n = 5; objective 1) and 10 (n = 4, 3, and 2 for objectives 1, 2, and 3, respectively). TIMP-1 immunoreactivity was observed within the granulosa cells of postsurge but not presurge follicles. On Days 3 and 10, TIMP-1 was localized within luteal tissue in a cell-specific manner. On Day 10, many of the cells that were immunopositive for TIMP-1 were judged to be large luteal cells on the basis of morphology (diameter > 22 microns; round nucleus) and colocalization with oxytocin and TIMP-2. Electron microscopy demonstrated that TIMP-1 was localized to secretory granules undergoing exocytosis from Day 10 large luteal cells. These data indicate that TIMP-1 is produced by granulosa cells following a gonadotropin surge and is packaged in secretory granules by large steroidogenic cells of the ovine CL.

Animals↗
PubMed1996

Steady-state luteinizing hormone receptor messenger ribonucleic acid levels and endothelial cell composition in bovine normal- and short-lived corpora lutea.

The short-lived corpus luteum (CL) contributes to reproductive inefficiency during the postpartum period in beef cows. The cause for the early demise of the short-lived CL is not fully understood but is believed to involve a premature release of prostaglandin F2 alpha. The objectives of this study were to evaluate norgestomet-hCG-induced normal-lived CL and hCG-induced short-lived CL in postpartum cows with respect to serum progesterone (P4) and 13,14-dihydro-15-keto, prostaglandin F2 alpha (PGFM) concentrations and luteal LH receptor (LH-R) concentrations, LH-R mRNA levels, and vascularity. Although serum P4 profiles from the time of hCG administration (Day 0) until luteectomy (Day 6, 7, or 8) were similar between CL life span groups, PGFM concentrations were elevated (p < 0.05) on Day 8 in cows expected to have short-lived CL compared to normal-lived CL. The LH-R concentrations were similar between normal- and short-lived CL on all days measured. Irrespective of luteal life span and day of luteectomy, all CL possessed a 4.4-kb LH-R transcript. Actin-normalized LH-R mRNA levels were similar between normal- and short-lived CL on Days 6 and 7; however, Day 8 short-lived CL contained less (p < 0.05) LH-R mRNA than Day 8 normal-lived CL. Although the area of luteal tissue occupied by capillaries in normal- and short-lived CL was similar on Days 6 and 7, the area occupied by capillaries in short-lived CL was lower (p < 0.05) than that for normal-lived CL on Day 8. Collectively, these results indicate that there is a decrease in steady-state LH-R mRNA and a reduction in luteal vascularity in CL expected to be short-lived. These changes occur concomitantly with a rise in serum PGFM, but prior to a decline in serum P4.

Animals↗
PubMed1996

Observer variability in histopathological reporting of non-small cell lung carcinoma on bronchial biopsy specimens.

AIMS: To evaluate the ability of histopathologists to sub-classify non-small cell lung carcinomas on bronchial biopsy material using the current World Health Organisation (WHO) classification. METHODS: Twelve histopathologists each reviewed 100 randomly selected bronchial biopsy specimens which had originally been reported as showing non-small cell lung carcinoma. For each case, two sections were circulated, one stained by haematoxylin and eosin and the other by a standard method for mucin (alcian blue/periodic acid Schiff). The participants were allowed to indicate their degree of confidence in their classification of each case. A standard proforma was completed and the results were analysed using kappa statistics. RESULTS: Where the participants were confident in their classification, they were actually quite good at sub-classifying the non-small cell carcinoma sections (kappa = 0.71, standard error = 0.058). Overall, however, the results were only fair (kappa = 0.39, standard error = 0.034). CONCLUSIONS: The majority of non-small cell lung carcinomas can be correctly categorised on adequate bronchial biopsy material. Where a confident diagnosis was made, both squamous carcinoma (kappa = 0.73) and adenocarcinoma (kappa = 0.83) were well recognised.

Adenocarcinoma↗
PubMed1996

Differences in cardiovascular responses to supine exercise and to standing after exercise in two clinical subgroups of Shy-Drager syndrome (multiple system atrophy).

BACKGROUND: In chronic autonomic failure of varying aetiologies, there are differences in the cardiovascular responses to supine leg exercise and to standing after exercise. Whether this occurs between the different subgroups with Shy-Drager syndrome (SDS) is unknown. METHODS: Fourteen patients with the cerebellar form (SDS-C) and 11 patients with parkinsonian features (SDS-P) were studied. RESULTS: Both groups had a similar degree of autonomic failure and postural hypotension. Their responses were compared with nine patients with idiopathic Parkinson's disease (IPD) and 15 normal subjects (controls), all with normal autonomic function. With supine exercise, blood pressure and heart rate rose similarly in controls and patients with IPD and there was no fall in blood pressure on standing after exercise. In both SDS groups there were abnormal responses to exercise: blood pressure fell in SDS-C, but did not fall or rise in SDS-P. Heart rate increased similarly in both SDS groups, calculated systemic vascular resistance fell similarly, but cardiac index rose more in SDS-P than SDS-C. Resting plasma noradrenaline concentrations were subnormal in both forms of SDS, and did not increase with exercise. Postural hypotension was enhanced after exercise to the same extent in SDS-C and SDS-P. CONCLUSIONS: The greater cardiovascular abnormalities in response to exercise in SDS-C suggests that cerebellar or brain stem autonomic pathways are impaired to a greater extent in SDS-C than in SDS-P. Pooling SDS subgroups, therefore, may obscure pathophysiological differences to certain stimuli. Clinically when postural hypotension is being assessed, separation of the subgroups may not be essential, as they responded similarly.

Adult↗
PubMed1996

Frequency of the apolipoprotein E epsilon 4 allele in a case-control study of early onset Parkinson's disease.

OBJECTIVES: It has been suggested that Parkinson's disease and Alzheimer's disease may share a common or at least overlapping aetiology. The prevalence of dementia among cases of Parkinson's disease is known to be greater than expected in the general population. The frequency of the apolipoprotein epsilon 4 allele in a large case-control study of early onset Parkinson's disease has been examined. METHODS: 215 patients and 212 population based controls were recruited from the Republic of Ireland between 1992 and 1994. Cases had to have disease onset at 55 years or younger and be born after 1925. RESULTS: The frequency of the epsilon 4 allele was almost identical between cases of Parkinson's disease (14.6%) and healthy controls (13.3%). There was no relation between epsilon 4 status and disease onset, disease duration, Hoehn and Yahr score, and disease progression. The frequency of the epsilon 4 allele was not increased among 10 patients with Parkinson's disease with dementia (10.0%) compared with the other patients without dementia (14.8%). There was no association between epsilon 4 allele status and either a history of smoking, family history of dementia, or Parkinson's disease, or being born in a rural area. The odds ratio for the ApoE epsilon 4 allele associated with Parkinson's disease was 1.10 (95% confidence interval (95% CI) 0.68-1.79), adjusting for age group, sex, and residential status. The pooled odds ratio from a meta-analysis of six studies of ApoE epsilon 4 status and Parkinson's disease was 0.94 (95% CI 0.69-1.27). CONCLUSIONS: The results from our study as well as the pooled meta-analysis exclude any important role for ApoE epsilon 4 status in the development of Parkinson's disease. Our results similarly do not support its role either in dementia associated with Parkinson's disease or disease prognosis.

Age of Onset↗
PubMed1996

Genital chlamydial infection among women in Nicaragua: validity of direct fluorescent antibody testing, prevalence, risk factors and clinical manifestations.

OBJECTIVE: To validate the performance of a direct fluorescence antibody (DFA) test and to determine the prevalence, risk factors and clinical manifestations of cervical chlamydia infection in different groups of women in Nicaragua. STUDY POPULATION: 926 women, 863 routine clinic attenders (mean age 27 years) and 63 sex workers (mean age 25 years) attending health centres in León, Corinto, Matagalpa and Bluefields. METHODS: Cervical specimens were examined using the Syva MicroTrak test system with a cut-off of 10 or more elementary bodies (EBs). The DFA results were validated by a one-step polymerase chain reaction (PCR) assay. Discordant results were further examined in nested PCR assays directed at two different target genes. An interviewer-administered questionnaire and a standard gynaecological examination were completed. RESULTS: Sensitivity of DFA was 80.1%, specificity 98.3%, and positive and negative predictive values 62.5% and 99.3%, respectively. Values were lower in locations where samples thawed because of electricity breaks and higher among sex workers. The majority of discordant results was confirmed as positive in nested PCR assays. Prevalence of cervical chlamydia infection based on positivity in DFA and/or PCR ranged from 2% among routine clinic attenders aged 35 years or older, to 8% among adolescent clinic attenders, and to 14% among sex workers. Among routine clinic attenders, young age (odds ratio [OR] 3.6, 95% confidence intervals [95% CI] 1.4-8.9 for women aged 15-19 years as compared with 1 in women 25 years of age or older) and use of oral contraceptives (OR 4.0, 95% CI 1.7-9.6) were the only statistically significant risk factors identified in multivariate logistic regression analysis. Presence of mucopurulent cervical discharge (OR 5.9, 95% CI 3.0-11.5) and presence of ectropion (OR 2.6, 95% CI 1.1-6.5) were the clinical signs independently associated with infection. CONCLUSIONS: Our results indicate that the DFA test was sensitive and specific while the performance of the PCR assay depends on adequate storage of samples. Genital C trachomatis infection is a common health problem among women in Nicaragua. The wide implementation of syndromic STD management algorithms together with health education programmes aimed at young people is the most promising approach to control STD in Nicaragua.

Adolescent↗
PubMed1996

Effect of Ca2+ influx on intracellular free Ca2+ responses in antigen-stimulated RBL-2H3 cells.

We undertake a quantitative investigation of changes in intracellular free Ca2+ concentration ([Ca2+]i) in antigen-stimulated rat basophilic leukemia (RBL-2H3) cells, which include contributions of both Ca2+ store release and Ca2+ influx from the medium. Following Keizer and De Young (J. Keizer and G. De Young. Biophys. J. 61: 649-660, 1992), we develop a highly constrained mathematical model for [Ca2+]i oscillations in RBL-2H3 cells, which includes activation of the inositol trisphosphate receptor (IP3R) by inositol 1,4,5-trisphospate, indirect Ca2+ activation of the IP3R via Ca2+ -dependent activity of phospholipase C-gamma, slow inhibition of the IP3R by cytosolic Ca2+, refilling of Ca2+ stores by a Ca2+ -ATPase (SERCA)-type pump, and a simple representation of the dependence of plasma membrane (PM) fluxes on experimental conditions. Using this full (open cell) model, we simulate [Ca2+]i responses for protocols in which antigen concentration and external Ca2+ are manipulated and compare out calculations with experimental data. In protocol A, cells are stimulated in the presence of external Ca2+, in protocols B and C, cells are stimulated in the absence of external Ca2+, with external Ca2+ later reapplied in protocol C. We are able to reproduce quantitatively the important features of all three protocols, including the dose response of protocol B, the [Ca2+]i response to thapsigargin, and lag time results, and we provide qualitative explanations for the responses derived from our calculations. We also develop a simplified (closed cell) version of the model in which PM fluxes are neglected and total free Ca2+ concentration ([Ca2+]T) is a slowly varying parameter. This permits us to explain in a simple graphical fashion how PM fluxes may influence [Ca2+]i responses in RBH-2H3 cells through modulation of [Ca2+]T.

Animals↗
PubMed1996

Altered regulation of hepatic glucose output in the male offspring of protein-malnourished rat dams.

Offspring of protein-malnourished rat dams have permanent alterations in hepatic enzyme activities associated with glucose homeostasis. Hormonal control of hepatic glucose output (HGO) was studied in male offspring of dams fed either a 20% (control) or 8% (low protein) protein diet during pregnancy and lactation. Glucagon (210 pM) stimulated HGO significantly more (P < 0.04) in controls (from 0.72 +/- 0.11 to 3.18 +/- 0.30 mumol.min-1.g liver-1) compared with low-protein animals (from 0.53 +/- 0.11 to 2.05 +/- 0.24 mumol.min-1.g liver-1). Insulin (1 nM) decreased (P < 0.001) HGO in controls to 2.39 +/- 0.37 mumol.min-1.g liver-1 after 10 min but increased HGO (to 2.82 +/- 0.40 mumol.min-1.g liver-1; P < 0.04) in low-protein rats. There were fivefold fewer (P = 0.01) glucagon receptors but a threefold increase (P < 0.05) in hepatic insulin receptor number in the low-protein rats, which was reflected by increased in insulin degradation (P < 0.001). The glucose transporter GLUT-2 was also raised threefold in the low-protein group (P < 0.001). The anomalous response to insulin indicates changes in its metabolic signaling, but normal insulin binding suggests that this alteration is a postreceptor event.

Animals↗
PubMed1996

Altered muscle insulin sensitivity in the male offspring of protein-malnourished rats.

Insulin sensitivity of skeletal muscle was studied in male offspring of rat dams fed either a 20% (control) or 8% (low-protein) diet during pregnancy and lactation. Freshly isolated muscle strips took up more [3H]methylglucose from low-protein animals than from controls (19.2 +/- 2.5 and 4.26 +/- 0.45 nmol.min-1.mg muscle-1, respectively, P < 0.001). However, after a 60-min preincubation there was no significant difference in basal glucose transport (4.02 +/- 0.42 and 4.23 +/- 0.35 nmol.min-1.mg-1 for control and low-protein animals, respectively). Insulin (300 pM) had a significantly greater (P < 0.001) effect on stimulation of glucose transport into preincubated low-protein muscle strips than into controls (to 14.14 +/- 1.25 and 9.61 +/- 0.71 nmol.min-1.mg-1, respectively). There were no differences in total GLUT-4 protein content. However, subcellular fractionation revealed significantly (P < 0.001) more GLUT-4 in muscle plasma membranes of low-protein animals compared with controls. Insulin increased (P < 0.001) the GLUT-4 content of control plasma membranes but had no effect in low-protein animals. There were twofold more insulin receptors in low-protein muscle membranes compared with controls (2.35 +/- 0.17 x 10(11) and 1.28 +/- 0.10 x 10(11) and insulin receptors/mg muscle membrane protein, respectively, P < 0.01). These results suggest that programming of muscle insulin sensitivity can occur during fetal life.

Animals↗
PubMed1996

Socioeconomic differentials in mortality risk among men screened for the Multiple Risk Factor Intervention Trial: I. White men.

OBJECTIVES: This study examined socioeconomic differentials in risk of death from a number of specific causes in a large cohort of White men in the United States. METHODS: For 300 685 White men screened for the Multiple Risk Factor Intervention Trial between 1973 and 1975, data were collected on median income of White households in the zip code of residence, age, cigarette smoking, blood pressure, serum cholesterol, previous myocardial infarction, and drug treatment for diabetes. The 31 737 deaths that occurred over the 16-year follow-up period were grouped into specific causes and related to median White family income. RESULTS: There was an inverse association between age- adjusted all-cause mortality and median family income. There was no attenuation of this association over the follow-up period, and the association was similar for the 22 clinical centers carrying out the screening. The gradient was seen for many-but not all-of the specific causes of death. Other risk factors accounted for some of the association between income and coronary heart disease and smoking-related cancers. CONCLUSIONS: Socioeconomic position, as measured by median family income of area of residence, is an important determinant of mortality risk in White men.

Adult↗
PubMed1996

Socioeconomic differentials in mortality risk among men screened for the Multiple Risk Factor Intervention Trial: II. Black men.

OBJECTIVES: This study examined socioeconomic differentials in risk of death from a number of causes in a large cohort of Black men in the United States. METHODS: For 20 224 Black men screened for the Multiple Risk Factor Intervention Trial between 1973 and 1975, data were collected on median family income of Black households in zip code of residence, age, cigarette smoking, blood pressure, serum cholesterol, previous heart attack, and drug treatment for diabetes. The 2937 deaths that occurred over the 16-year follow-up period were grouped into specific causes and related to median Black family income. RESULTS: There was an inverse association between age-adjusted all-cause mortality and median family income. There was no attenuation of this association over the follow-up period, and the association was similar for the 22 clinical centers carrying out the screening. The gradient was seen for most of the specific causes of death, although the strength of the association varied. Median income was markedly lower for the Black men screened than for the White men, but the relationship between income and all-cause mortality was similar. CONCLUSIONS: Socioeconomic position is an important determinant of mortality risk for Black men. Even though Blacks lived in areas with substantially lower median family income than Whites, the association of income with mortality was similar for Blacks and Whites.

Adult↗
PubMed1996

Inguinal hernia and a single strenuous event.

A study of 129 consecutive patients, who had a total of 145 inguinal hernias, showed that in only 7% of the patients was the hernia subjectively attributable to a single muscular strain. Guidelines are suggested to assist in assessing 'cause' in claims for industrial injury in such patients.

Adult↗
PubMed1996

Role of CD4+, CD8+ and double negative T-cells in the protection of SCID/beige mice against respiratory challenge with Rhodococcus equi.

To evaluate the contributions of T-lymphocyte subsets in pulmonary immunity against Rhodococcus equi, C.B-17 SCID/beige mice were adoptively transferred with splenic lymphocytes from congenic BALB/c mice previously infected with R. equi. Spleen cells were enriched for either CD4+ or CD8+ populations before inoculation, Flow cytometry showed that each enriched population contained less than 0.5% cross contamination. Groups of adoptively transferred SCID/beige mice were sacrificed 6 and 13 d after intranasal infection with R. equi. Bacterial clearance was measured in the lungs, liver and spleen. Lesion development was assessed by gross and histopathological score and the fate of transferred cells assessed by flow cytometry and by immunohistochemistry. SCID/beige mice receiving either CD4+ or CD8+ T-cells were able to clear the infection better than control mice. On d 6 post-infection, bacterial numbers were significantly lower in the lungs of CD4+ transferred mice as compared to CD8+ mice. By d 13, both groups had cleared R. equi from all organs. CD4+ cells were however identified in the lung and spleen of CD8+ recipients at d 13 making conclusions about the role of CD8+ cells in R. equi clearance impossible. By contrast, no significant increases in CD8+ lymphocytes were observed in the organs of CD4+ recipients. All mice developed suppurative bronchopneumonia but lesions were most severe in the CD4+ group. Immunohistochemistry and flow cytometry confirmed that CD4+ and CD8+ cells had migrated to the lungs of adoptively transferred mice. Serum antibody against R, equi was not detected by ELISA in the recipients. SCID/beige mice receiving CD4-CD8- cells were unable to clear R. equi. The study supports the suggestion that CD4+ cells have a central role in R. equi clearance in mice.

Actinomycetales Infections↗
PubMed1996

Enhancement of primate oocyte maturation and fertilization in vitro by inhibin A and activin A.

OBJECTIVE: A role for inhibin and activin in primate oocyte maturation was investigated. DESIGN: The maturation and fertilization of rhesus monkey oocytes recovered from the excised ovaries of nine regularly cycling animals was compared for untreated germinal vesicle (GV)-intact controls versus oocytes cultured in the presence of inhibin, activin, inhibin + activin, or in a combination with follistatin. SETTING: Nonhuman primates in a research institute environment. INTERVENTIONS: Bilateral oophorectomy. MAIN OUTCOME MEASURE: Oocyte maturation from germinal vesicle breakdown (GVBD) to metaphase II (MII) and fertilization. RESULTS: Germinal vesicle breakdown, progression to MII and fertilization was monitored in oocytes cultured for 48 hours. Activin alone, at an optimum concentration of 100 ng/mL, stimulated GVBD whereas both GVBD and MII development was enhanced in the presence of inhibin + activin. The latter also accelerated the rate of maturation to MII. All treatment groups exhibited a higher incidence of GVBD compared with controls. When follistatin was added, the stimulatory effect of activin or activin + inhibin was abolished. Exposure to medium containing inhibin + activin significantly increased the percentage of MII oocytes that fertilized compared with controls (68% versus 25%, respectively). CONCLUSIONS: Inhibin and activin are potent stimulators of primate oocyte maturation, producing mature oocytes in vitro that fertilize with high efficiency.

Activins↗