PubMed Health⌕ Search

Biomedical subjects

R Benveniste

Publications and source records attributed to R Benveniste.

At least 19 recordsLinked to original sources
PubMed1997

Cryptosporidiosis in HIV-infected patients: diagnostic sensitivity of stool examination, based on number of specimens submitted.

OBJECTIVES: To determine the optimal number of stool specimens needed for the diagnosis of cryptosporidiosis. METHODS: Four hundred thirty-five admissions were reviewed (291 patients) in which stool specimens were examined for Cryptosporidium parvum oocysts (mean of 1.47 specimens per admission), using a modified acid-fast stain. The diagnostic yield of each specimen was determined. RESULTS: Cryptosporidium parvum oocysts were found in 81 of 435 admissions (18.6%). Ninety-six percent of the positive cases were detected on the first stool specimen analysis, and 100% were detected by the second specimen. CONCLUSIONS: Examination of one specimen is generally appropriate for the diagnosis of cryptosporidiosis in a hospitalized patient with AIDS presenting with diarrhea. Examination of a second specimen may be appropriate if the first specimen is negative and there is a high clinical index of suspicion.

AIDS-Related Opportunistic Infections↗
PubMed1992

Serum progesterone and 17-hydroxyprogesterone in the diagnosis of ectopic pregnancies and the value of progesterone replacement in intrauterine pregnancies when serum progesterone levels are low.

The corpus luteum function was evaluated in patients with surgically confirmed ectopic pregnancy (EP) in a multicenter study. In addition, the minimal threshold of serum progesterone (P) concentration required for salvaging intrauterine pregnancies (IUP) was also examined. Results show that single P or 17-OHP measurements are not diagnostic for EP, since mean P levels in EP were similar to those with spontaneous abortion though significantly lower than those in controls. 17-OHP levels in EP overlapped in 50% with IUP, and the mean levels were significantly lower only at 6-7 weeks. The 17-OHP levels when compared to hCG supports the view that corpus luteum defect is primary. In IUP, P levels < 8 ng/ml still were associated with viable (60%) pregnancy; thus no minimal threshold could be established.

17-alpha-Hydroxyprogesterone↗
PubMed1991

Gonadal and adrenal effects on hepatic epidermal growth factor receptor expression in a murine model.

We hypothesize that the actions of epidermal growth factor (EGF) may be modulated by changes in cell surface EGF receptor (EGF-R) expression under endocrine influences. Mouse liver cell membrane preparations were used in a RRA. During ontogenesis, both sexes showed a significant increase (P less than 0.005) in hepatic EGF-R numbers at puberty; however, males demonstrated significantly higher levels than females (P less than 0.005). Gonadectomy of adult males and females resulted in a significant (P less than 0.05) decrease and increase, respectively, in hepatic EGF-R expression. Prepubertal gonadectomy in both sexes resulted in EGF-R levels similar to those observed in adult females. Adrenalectomy of adult animals of both sexes had no effect on hepatic EGF-R numbers, but gonadectomy plus adrenalectomy virtually obliterated EGF-R expression. Short term treatment with testosterone of adult females or gonadectomized female and male mice significantly increased EGF-R numbers (P less than 0.05) to adult male levels. 17 beta-Estradiol given short term to adult males or gonadectomized male and female mice did not significantly alter EGF-R levels. EGF-R expression in androgen-insensitive male mice was significantly reduced (P less than 0.005) to female levels. We conclude that 1) hepatic EGF-R numbers increase post-pubertally in both sexes; 2) hepatic EGF-R expression is significantly stimulated by testosterone, and this effect depends on a functional androgen receptor; 3) the ovary has an inhibitory effect on adult hepatic EGF-R numbers; however, this effect does not appear to be mediated by estrogens; and 4) the adrenal gland has a stimulatory effect on adult hepatic EGF-R expression.

Adrenal Glands↗
PubMed1990

Serological survey for two simian retroviruses in macaques and African green monkeys.

Colonies of nonhuman primates at the Bowman Gray School of Medicine (BGSM) were tested for antibodies to two retroviruses associated with immunodeficiency by indirect immunofluorescence (IFA) and western blot. A total of 471 cynomolgus macaques (Macaca fascicularis), 144 rhesus monkeys (M. mulatta) and 67 stumptail monkey M. arctoides) were tested for SRV-1, and 152 African green monkeys (Cercopithecus aethiops) were tested for SIV. Of the macaques tested, 170 (36%) cynomolgus, 5 (3%) rhesus and 8 (12%) stumptails were positive for SRV-1 antibodies by IFA. Of the African green monkeys, 54 (36%) were IFA positive for SIV antibodies. A total of 143 African green monkeys tested by IFA also were tested by western blot. In the African green monkeys, the IFA had a positive predictive value of 98% and a negative predictive value of 96%. Of 176 IFA positive macaque sera tested by western blot, 49 (28%) were positive, 55 (31%) were considered equivocal (only one band, usually to p27 core protein), and 72 (41%) were negative.

Animals↗
PubMed1989

Evaluation of the human gonadotroph free alpha-subunit secretory pools by administration of gonadotropin hormone-releasing hormone into normal subjects at different phases of the ovarian cycle.

The specificity of a monoclonal antibody RIA for the measurement of free alpha-subunit in plasma is presently documented. This RIA was used to explore the pituitary gonadotroph free alpha-subunit reserve in normal ovulating women stimulated with gonadotropin hormone-releasing hormone (GnRH). RIA specificity was established by means of competitive inhibition curves with various glycoprotein hormone preparations, and Sephadex G-100 exclusion chromatography of purified hFSH (1-2), hLH (LER 960) and pituitary extract. The 3.8% and 5.5% crossreactivities of hFSH 1-2 and hLH LER 960 were shown by exclusion chromatography to result in part from free alpha-subunit contamination in these purified preparations. Pituitary extract chromatography indicated hFSH and hLH cross-reactivity below 2.5% and 1.5%, respectively. Normal females were stimulated with GnRH throughout the cycle: 3 tests were performed on Day 7, 1 test on Day 13, 16, 17 and 22, respectively, and 2 tests on Day 24. GnRH stimulation consisted of an initial 100 micrograms bolus (time 0) followed at 2 h by a 12.5 micrograms/h constant infusion, and a second 100 micrograms bolus at 5 h. In all subjects, baseline free alpha-subunit values were below 2 ng/ml. Total free alpha-subunit secretion was markedly enhanced in subjects Day 13 and 16, in concert with total hLH and hFSH secretion. In the three subjects Day 7, free alpha-subunit was released only after the second GnRH bolus. In periovulatory subjects, free alpha-subunit secretion became apparent after the initial bolus and with constant GnRH infusion. In the three subjects Day 22 and 24, peak levels of free alpha-subunit were obtained after the second GnRH bolus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Effect of lipoxygenase products on choriogonadotropin secretion by cultured human choriocarcinoma JEG-3 cells pre- and post-stimulation with epidermal growth factor and a phorbol ester.

Previous studies using arachidonic acid and preferential inhibitors of the arachidonic acid pathway have implicated the lipoxygenase system in choriogonadotropin (hCG) secretion by JEG-3 cells. Presently, JEG-3 cells are used in order to examine the effect of lipoxygenase products on hCG secretion. Results show that 30 microM 15-hydroxyeicosatetraenoic acid (15-HETE) induces an approximately 3-fold increase in basal hCG secretion, while 5-HETE, 12-HETE, and leukotriene LTA4 have no significant effect. In addition, 15-HETE potentiates the stimulation of hCG secretion induced by 3 nM epidermal growth factor (EGF), but has no significant effect on the stimulation of hCG induced by 22 nM tetradecanoylphorbol acetate (TPA). The present study further implicates the arachidonic acid pathway in the control of hCG secretion and documents that the effect of EGF can be rate-limited by a product of the lipoxygenase system.

Cell Line↗
PubMed1988

Epidermal growth factor receptor numbers in male and female mouse primary hepatocyte cultures.

Epidermal growth factor receptors (EGF-R) were measured in adult male and female mouse primary hepatocyte cultures. On culture day 1, female hepatocytes had significantly fewer EGF-R than male hepatocytes (1.3 x 10(4) versus 6.2 x 10(5) per cell). Over the next three days, morphological changes consistent with progressive heptocyte dedifferentiation were observed. During this period, EGF-R numbers progressively increased in female cultures and decreased in male cultures, and by day 4 the sexual difference in EGF-R numbers was obliterated. These results indicate that a relationship exists between the degree of differentiation in hepatocyte cultures and the expression of EGF-R on the cell surface.

Animals↗
PubMed1988

Evidence for a local change in the progesterone/estrogen ratio in human parturition at term.

The purpose of this study was to determine if a local change in the concentrations of estrogen and progesterone occurs in the amniotic fluid during human parturition at term. Amniotic fluid was retrieved from 20 women in active labor and from 20 women not in labor. Patients were matched for maternal age and gestational age. Estradiol, estriol, progesterone, and dehydroepiandrosterone sulfate were measured in amniotic fluid by radioimmunoassay. For women in active labor, the median concentrations (range) of these steroid hormones were 2.4 ng/ml (1 to 9.2 ng/ml), 1661.2 ng/ml (556.6 to 3928.1 ng/ml), 12.3 ng/ml (4.7 to 41.4 ng/ml), and 187.5 ng/ml (61.2 to 470 ng/ml), respectively. The median concentrations (range) for women not in labor were 1.6 ng/ml (0.3 to 5.7 ng/ml), 684.2 ng/ml (70.6 to 2103.1 ng/ml), 13.2 ng/ml (7.5 to 63 ng/ml), and 65.6 ng/ml (20 to 334 ng/ml), respectively. Thus spontaneous human parturition at term was associated with significantly increased amniotic fluid concentrations of estradiol, estriol, and dehydroepiandrosterone sulfate (p = 0.02, p = 0.002, p = 0.003, respectively). The progesterone/estrogen ratios (progesterone/estradiol and progesterone/estriol) were significantly lower for women in active labor compared with those not in labor (p = 0.002 and p = 0.0006, respectively). We conclude that a local change in the progesterone/estrogen ratio occurs during human parturition at term.

Amniotic Fluid↗
PubMed1987

Free alpha-subunit response to gonadotropin-releasing hormone in women with polycystic ovaries.

The response of glycoprotein hormone free alpha-subunit to gonadotropin-releasing hormone (GnRH) was evaluated in 12 women with polycystic ovaries (PCOs). Six of these women were premedicated for 3 days with micronized 17 beta-estradiol before receiving a 100-micrograms bolus of GnRH. In nonmedicated PCO patients, GnRH did not significantly alter basal free alpha-subunit levels. In four of the six PCO patients receiving estrogen premedication, a significant increase in free alpha-subunit was observed; these four patients had low progesterone levels at the time of the GnRH test. Among the six premedicated patients, two had elevated (greater than 4 ng/ml) progesterone levels, and the GnRH tests showed no significant effect on the levels of free alpha-subunit. The study revealed a dissociation between the free alpha-subunit responses to GnRH and the responses of luteinizing hormone; a closer relationship was observed between free alpha-subunit and follicle-stimulating hormone responses. It was concluded that the lack of a free alpha-subunit response to GnRH in PCO patients is not due to a primary inability of the pituitary gonadotroph to produce free alpha-subunit but is a consequence of an altered estrogenic milieu, and a free alpha-subunit response to GnRH may reflect the replenishment of both follicle-stimulating hormone and luteinizing hormone in the gonadotrope.

Adult↗
PubMed1987

Immunohistochemical localization of human and simian immunodeficiency viral antigens in fixed tissue sections.

Antigens of human (HIV) or simian immunodeficiency viruses (SIV) were identified with polyclonal or monoclonal antibodies and avidin-biotin complex (ABC) immunohistochemistry in fixed surgical pathology and autopsy specimens of humans or monkeys with the acquired immunodeficiency syndrome. With B-5 fixative, viral antigens were readily detected in lymph nodes of 8 of 13 patients with follicular hyperplasia, but in only 1 of 12 patients with follicular atrophy. Antigen was detected in follicular dendritic reticular cells and rare blastlike cells, extracellularly, and in postcapillary venules, medullary lymphocytes, sinus histiocytes, and macrophages in some lymph nodes. In the brain at autopsy, antigen could be found in gliomesenchymal-cell nodules, astrocytes, vascular endothelial cells, multinucleated cells, and astrocytes and macrophages associated with demyelination. In contrast, 4 rhesus monkeys with experimental SIV infection had abundant antigen in sinus histiocytes, macrophages, and multinucleated giant cells of lymph nodes and spleen and in thymic epithelial cells. Brain lesions of monkeys resembled those of humans, with antigen found in macrophages and multinucleated giant cells. Antibodies to HIV also were immunoreactive in formalin-fixed tissue sections of monkeys containing SIV antigens. The ABC technique provided a fast and efficient method for localizing HIV and SIV antigens in fixed surgical and autopsy specimens. These findings are consistent with those found with in situ hybridization, ultrastructural studies, frozen sections of lymph nodes, and permanent sections of brain.

Acquired Immunodeficiency Syndrome↗
PubMed1986

The effect of dehydroepiandrosterone sulfate on de novo and low-density lipoprotein-stimulated progesterone secretion by human choriocarcinoma JEG-3 cells.

It has been suggested that fetal adrenal steroids affect the secretion of progesterone by the human trophoblast and decrease the progesterone/estrogen secretory ratio at the time of parturition. In the present study, cultured human choriocarcinoma JEG-3 cells were used as an experimental model in order to examine the effect of dehydroepiandrosterone sulfate on both de novo and low-density lipoprotein-stimulated progesterone secretion. In serum-free and cholesterol-free Dulbecco's modified Eagle's medium, JEG-3 cell cultures demonstrated a significant secretion of both pregnenolone and progesterone. A 200% to 300% increase in pregnenolone and progesterone secretion was achieved by physiologic low-density lipoprotein concentrations added to Dulbecco's modified Eagle's medium while androgens and estrogens remained undetectable. Dehydroepiandrosterone sulfate added to Dulbecco's modified Eagle's medium was actively converted into C-19 and C-18 steroids but had no significant effect (up to 20 micrograms/ml) on basal (de novo) progesterone secretion. In contrast, the addition of dehydroepiandrosterone sulfate (1 to 5 micrograms/ml) to cultures grown in Dulbecco's modified Eagle's medium plus low-density lipoprotein induced a dose-related inhibition of progesterone and a return of that secretion to basal levels.

Cell Line↗
PubMed1986

Characterization of glycoprotein hormone free alpha-subunit from human pituitary and placenta extracts.

Standard alpha-subunit dissociated from glycoprotein hormones differs from individual (free) alpha-subunit found in sera or in cell culture media; secreted free alpha-subunit is larger, more acidic and lacks the ability of recombining in vitro with standard hCG-beta. It is unclear whether the large free alpha-subunit is only a secretory product or whether it is also present in tissue. Herein were studied the molecular size, the isoelectric pH, and the recombining activity of free alpha-subunit obtained from pituitary and placenta extracts. Sephadex exclusion chromatography showed the presence of both a large and a small form, and a changing large/small free alpha-subunit ratio in the various extracts. Most of the large form obtained from placenta extracts electrofocused into two peaks of pI 4.8 and 5.1. The large form showed no recombining activity with standard hCG-beta while the small free alpha-subunit recombined as well as did standard hCG-alpha. The observation of three common characteristics (a larger size, a pI 4.8, and a lack of recombining activity) suggests a similarity between the large secreted form and a fraction of the free alpha-subunit in tissue.

Chromatography, Gel↗
PubMed1986

Progesterone, estradiol, and alpha-human chorionic gonadotropin secretion in patients with ectopic pregnancy.

Plasma free alpha hCG, estradiol (E2), and progesterone (P4) concentrations were measured in 38 patients with histologically confirmed ectopic pregnancy (EP). The menstrual gestational ages ranged from 6-10 weeks. Free alpha hCG levels, although significantly lower than those in women with a normal intrauterine pregnancy, increased markedly during this time period, from 1.5 to 11 ng/ml, a 7-fold increase. In women with an intrauterine pregnancy, only 0.6-fold increase occurred during the same time period. Plasma P4 and E2 concentrations in patients with EP were significantly lower, except at 6 weeks for E2 and in the sixth and seventh weeks for P4. The ectopically implanted trophoblast undergoes impairment of its ability to synthesize beta hCG, but not alpha hCG. The lack of utilization of alpha hCG in EP causes it to increase, while the level of intact hCG is low. These observations suggest that the levels of alpha hCG are a sensitive marker for placental well-being, and that it could serve as an additional diagnostic tool for the early diagnosis of EP. The placenta is only partially able to compensate for the reduced ovarian production of E2 and P4.

Chorionic Gonadotropin↗
PubMed1986

Competitive studies with dehydroepiandrosterone sulfate and 16 alpha-hydroxydehydroepiandrosterone sulfate in cultured human choriocarcinoma JEG-3 cells: effect on estrone, 17 beta-estradiol, and estriol secretion.

The estradiol (E2) to estriol (E3) ratio during human pregnancy depends on fetal liver hydroxylation of fetal adrenal dehydroepiandrosterone sulfate (DHEAS) and conversion by the trophoblast of DHEAS and 16 alpha-hydroxy-DHEAS (16 OH-DHEAS) to estrone (E1), estradiol (E2), and estriol (E3), respectively. It is not known whether the conversion of DHEAS into E1 and E2 influence the conversion of 16OH-DHEAS into E3 and vice versa. To examine this question, we studied these interactions in human choriocarcinoma JEG-3 cells. In serum-free medium (Dulbecco's Modified Eagle's Medium), JEG-3 cells secreted hCG [27 +/- 3 (+/- SEM) ng/mg cellular protein X 24 h] and progesterone (22 +/- 2.5), but neither C-19 nor C-18 steroids. The addition of DHEAS resulted in secretion of E1 and E2; at a concentration of 500 ng DHEAS/ml, the secretion of E1 (1 +/- 0.16) and E2 (11 +/- 3.1) was maximal, while E3 remained undetectable. The addition of 1000 ng 16 OH-DHEAS/ml resulted in maximum E3 secretion (13 +/- 1.8), while E1 and E2 remained undetectable. The addition of increasing concentrations of DHEAS to cultures exposed to 1000 ng 16OH-DHEAS/ml caused a decrease in E3 secretion and increased secretion of E1 and E2. Conversely, addition of increasing concentrations of 16OH-DHEAS in cultures exposed to 500 ng DHEAS/ml resulted in inhibition of E1 and E2 secretion and increased E3 secretion. A concentration of 16OH-DHEAS that inhibited the conversion of DHEAS into E1 and E2 neither altered the intracellular to extracellular steroid ratios (approximately 0.1) nor reduced the secretion of DHEA, androstenedione, and testosterone. The inhibitory effect of 16OH-DHEAS was minimal at low DHEAS concentrations (favoring the secretion of E1 and E2) and was greatly enhanced at concentrations of DHEAS that induced maximum E1 and E2 secretions. The results indicate that in trophoblastic cells, the metabolism of DHEAS can modulate E3 secretion, and the metabolism of 16OH-DHEAS can modulate the secretion of E1 and E2; and this regulatory mechanism appears to take place at the level of the aromatase system.

Cells, Cultured↗
PubMed1985

Binding characteristics of epidermal growth factor receptors in male and female rat liver cell membrane preparations.

The binding characteristics of epidermal growth factor (EGF) receptors were studied in cell membrane preparations from adult male (n = 14) and female (n = 13) rat livers. Results indicate a significant lower (about 65%) number of EGF receptors in female preparations. The possibility that the decrease in EGF receptors was only a reflection of an excess free EGF in female preparations was ruled out by means of acid extraction, ultrafiltration, and measurement of EGF in the acid extracts. In view of the known role of EGF in cell differentiation, it may be important to recognize that the number of its receptors, at least in liver preparations, is markedly different between sexes.

Animals↗
PubMed1985

Effects of epidermal growth factor, phorbol myristate acetate, and arachidonic acid on choriogonadotropin secretion by cultured human choriocarcinoma cells.

Epidermal growth factor (EGF) binds specifically (Ka = 4 X 10(9) M-1; 1.3 X 10(11) receptors/mg cellular protein) to JEG-3 cells, which respond in the succeeding 24 h by a 400% increase in hCG secretion without a significant change in cell number. Since JEG-3 cells store less than 2% of the 24-h hCG secretion, a significant increase in hCG in the culture medium reflects increased hCG biosynthesis. It is observed that a tumor promoter, phorbol myristate acetate (PMA), binds specifically to the cells (Ka = 5 X 10(8) M-1; 3.9 X 10(11) receptors/mg), reduces (33%) the affinity but not the number of EGF receptors, and stimulates hCG to the same extent as does EGF. The relative potencies of PMA (100%), phorbol dibutyrate (25%), and nonesterified phorbol (no effect) to stimulate hCG parallel their known tumor-promoting activities. Since phospholipids and fatty acids have been implicated in the mechanism of action of EGF and PMA, the effects of arachidonic acid (AA) and inhibitors of its metabolism were studied. The addition of AA had no effect on basal or PMA-stimulated hCG secretion, but it potentiated the effect of EGF by 200%. Indomethacin (a cyclooxygenase inhibitor) had an effect similar to that of AA. Nordihydroguairetic acid (a cyclooxygenase and lipoxygenase inhibitor) reduced by 90% basal and EGF- or PMA-stimulated hCG secretion. These results indicate that the AA pathway can influence the effects of EGF and PMA on hCG secretion and suggest an intermediary role for the lipoxygenase system.

Arachidonic Acid↗
PubMed1983

Ontogenesis and characteristics of epidermal growth factor receptors in human placenta.

Epidermal growth factor promotes growth in many cell types. The role of epidermal growth factor during gestation and fetal development is unknown. This study investigates the presence and binding characteristics of epidermal growth factor receptors in placentas throughout gestation. Cell membrane preparations were obtained from first-, second-, and third-trimester placentas and hydatidiform moles. Specific epidermal growth factor receptors were observed as early as 6 weeks of gestation. Throughout gestation, Scatchard analysis of epidermal growth factor binding was curvilinear, and dissociation studies were consistent with site-to-site interaction with negative cooperativity. Affinity constants at high (Ke = 9.9 +/- 0.79 X 10(9) L/mol) and low (Kf = 3.0 +/- 0.25 X 10(9) L/mol) receptor occupancy were unchanged throughout normal gestation. However, the number of receptors per milligram of protein significantly increased with advancing normal gestation (correlation coefficient, r = 0.81). In hydatidiform moles, the number of receptors was reduced when compared to that of normal tissue of similar gestational age. Our study provides a quantitative basis for further evaluation of epidermal growth factor as a possible factor in embryogenesis and fetal development.

Cell Membrane↗