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Biomedical subjects

S E Glickman

Publications and source records attributed to S E Glickman.

At least 19 recordsLinked to original sources
PubMed2007

Placental expression and molecular characterization of aromatase cytochrome P450 in the spotted hyena (Crocuta crocuta).

At birth, the external genitalia of female spotted hyenas (Crocuta crocuta) are the most masculinized of any known mammal, but are still sexually differentiated. Placental aromatase cytochrome P450 (P450arom) is an important route of androgen metabolism protecting human female fetuses from virilization in utero. Therefore, placental P450arom expression was examined in spotted hyenas to determine levels during genital differentiation, and to compare molecular characteristics between the hyena and human placental enzymes. Hyena placental P450arom activity was determined at gestational days (GD) 31, 35, 45, 65 and 95 (term, 110), and the relative sensitivity of hyena and human placental enzyme to inhibition by the specific inhibitor, Letrozole, was also examined. Expression of hyena P450arom in placenta was localized by immuno-histochemistry, and a full-length cDNA was cloned for phylogenetic analysis. Aromatase activity increased from GD31 to a peak at 45 and 65, apparently decreasing later in gestation. This activity was more sensitive to inhibition by Letrozole than was human placental aromatase activity. Expression of P450arom was localized to syncytiotrophoblast and giant cells of mid-gestation placentas. The coding sequence of hyena P450arom was 94% and 86% identical to the canine and human enzymes respectively, as reflected by phylogenetic analyses. These data demonstrate for the first time that hyena placental aromatase activity is comparable to that of human placentas when genital differentiation is in progress. This suggests that even in female spotted hyenas clitoral differentiation is likely protected from virilization by placental androgen metabolism. Decreased placental aromatase activity in late gestation may be equally important in allowing androgen to program behaviors at birth. Although hyena P450arom is closely related to the canine enzyme, both placental anatomy and P450arom expression differ. Other hyaenids and carnivores must be investigated to determine the morphological and functional ancestral state of their placentas, as it relates to evolutionary relationships among species in this important taxonomic group.

Animals↗
PubMed2006

Endocrine differentiation of fetal ovaries and testes of the spotted hyena (Crocuta crocuta): timing of androgen-independent versus androgen-driven genital development.

Female spotted hyenas (Crocuta crocuta) have an erectile peniform clitoris and a pseudoscrotum but no external vagina, all established by day 35 of a 110-day gestation. Recent studies indicate that these events are androgen-independent, although androgen secretion by fetal ovaries and testis was hypothesized previously to induce phallic development in both sexes. We present the first data relating to the capacity of the ovaries and testes of the spotted hyena to synthesize androgens at different stages of fetal life. Specifically, spotted hyena fetal gonads were examined by immunohistochemistry at GD 30, 45, 48, 65, and 95 for androgen-synthesizing enzymes, as related to the morphological development. Enzymes included 17alpha-hydroxylase/17,20-lyase cytochrome P450 (P450c17), cytochrome b5, 3beta-hydroxysteroid dehydrogenase (3betaHSD), and cholesterol side-chain cleavage cytochrome P450 (P450scc). Anti-Müllerian-hormone (AMH) expression was also examined. AMH was strongly expressed in fetal Sertoli cells from GD 30 and after. P450c17 expression was detected in Leydig cells of developing testes and surprisingly in Müllerian duct epithelium. Fetal ovaries began to organize and differentiate by GD 45, and medullary cells expressed P450c17, cytochrome b5, 3betaHSD, and P450scc. The findings support the hypothesis that external genital morphology is probably androgen-independent initially, but that fetal testicular androgens modify the secondary, male-specific phallic form and accessory organs. Fetal ovaries appear to develop substantial androgen-synthesizing capacity but not until phallic differentiation is complete, i.e. after GD 45 based on circulating androstenedione concentrations. During late gestation, fetal ovaries and testes synthesize androgens, possibly organizing the neural substrates of aggressive behaviors observed at birth in spotted hyenas. These data provide an endocrine rationale for sexual dimorphisms in phallic structure and reveal a potential source of androgenic support for neonatal aggression in female and male C. crocuta.

Androgens↗
PubMed2003

Variation in ovarian morphology in four species of New World moles with a peniform clitoris.

Female moles of the Old World genus Talpa display a curious suite of reproductive features that include a peniform clitoris and ovaries with a discrete interstitial gland or testis-like region (so-called 'ovotestes'). The masculinization of the female external genitalia in Talpa has accordingly been linked with secretion of androgens from the interstitial gland region of the fetal gonad. Although their ovarian morphology has received less attention, some species of New World moles also have ovaries with a pronounced interstitial gland (for example star-nosed mole, Condylura cristata), whereas females of other species do not (for example eastern mole, Scalopus aquaticus). Although it is difficult to determine the sex of both Old and New World moles, published accounts describing the external genitalia of female moles are available only for Talpa. The hypothesis that masculinization of the female external genitalia in moles is associated with the presence of an ovarian interstitial gland (OIG) was tested in the present study by using a comparative approach to determine whether these features are ever found in isolation of one another. Three genera of North American moles (Scapanus, Condylura and Neurotrichus) were studied and a peniform clitoris was found in all three species, but OIG were found in only two of three genera. The ovaries of S. latimanus and S. orarius were unremarkable, with no evidence of a discrete interstitial gland or testis-like region. Mapping these results onto recent talpid phylogenies indicates that loss of the bipolar ovarian morphology is a derived trait in Scapanus, and conclusively demonstrates that masculinization of the external genitalia in female moles can develop in the presence or absence of 'ovotestes'.

Animals↗
PubMed2002

Exposure to naturally circulating androgens during foetal life incurs direct reproductive costs in female spotted hyenas, but is prerequisite for male mating.

Among all extant mammals, only the female spotted hyena (Crocuta crocuta) mates and gives birth through the tip of a peniform clitoris. Clitoral morphology is modulated by foetal exposure to endogenous, maternal androgens. First births through this organ are prolonged and remarkably difficult, often causing death in neonates. Additionally, mating poses a mechanical challenge for males, as they must reach an anterior position on the female's abdomen and then achieve entry at the site of the retracted clitoris. Here, we report that interfering with the actions of androgens prenatally permanently modifies hyena urogenital anatomy, facilitating subsequent parturition in nulliparous females who, thereby, produce live cubs. By contrast, comparable, permanent anatomical changes in males probably preclude reproduction, as exposure to prenatal anti-androgens produces a penis that is too short and has the wrong shape necessary for insertion during copulation. These data demonstrate that the reproductive costs of clitoral delivery result from exposure of the female foetus to naturally circulating androgens. Moreover, the same androgens that render an extremely unusual and laborious process even more reproductively costly in the female are apparently essential to the male's physical ability to reproduce with a normally masculinized female.

Androgen Antagonists↗
PubMed2002

Virilization of the female spotted hyena cannot be explained by alterations in the amino acid sequence of the androgen receptor (AR).

The external genitalia of the female spotted hyena are male in character, consistent with virilization by androgens during embryogenesis that results in the fusion of the vaginal labia to form a pseudo scrotum and enlargement of the clitoris to form a phallus. Explanations advanced to account for these anatomic differences have centered on the production or metabolism of androgens in utero or on abnormalities of the androgen receptor (such as a constitutively active AR). The structure of the spotted hyena AR was examined at the level of genomic DNA and cDNA. Southern analysis detected two Eco RI endonuclease cleavage fragments (4.4 and 4.7 kb) that encode the bulk of the AR hormone-binding domain. Isolation of the smaller fragment from a size fractionated genomic library revealed that it contained exons 6, 7 and 8. The remaining portions of the coding sequence were cloned by RT-PCR and RACE analyses. The spotted hyena cDNA sequence predicts protein 912 amino acids in length, which is most closely related to the sequence of the dog AR. Although a number of differences in the predicted amino acid sequence are identified, particularly within the amino terminus, only single amino acid substitutions are present in the DNA- and ligand-binding domains compared to the human AR. In transfection assays, the spotted hyena AR does not exhibit constitutive activity and responds normally to a range of androgenic and non-androgenic ligands. These findings suggest that the structural changes in the AR do not account for the abnormal virilization in the female spotted hyena. These results serve to focus attention on processes proximal (an abnormality of hormone formation in situ) or distal (activation by other mechanisms of processes normally regulated by androgen) to the AR as the cause of the virilization.

Amino Acid Sequence↗
PubMed1999

Testis-like steroidogenesis in the ovotestis of the European mole, Talpa europaea.

The female European mole (Talpa europaea) presents a vivid paradox in relation to our contemporary understanding of mammalian sexual differentiation. These animals are exceptional among female mammals in that they possess bilateral ovotestes. The ovotestis contains a morphologically normal ovarian component that develops during the spring breeding season and a histologically defined testicular region, the interstitial gland, which enlarges during autumn when the ovarian component decreases in size. In correlation with this unusual gonadal situation, the female mole displays a penile clitoris traversed by a urethral canal. Although the histology of the ovotestis is well documented and has recently been extended to an additional three species of the genus Talpa, there have been no clear indications of the physiological function, particularly androgen production, of the ovotestis in these female moles. This paper presents the first clear evidence of seasonal variation in plasma testosterone concentrations, which parallel the growth and regression of the "testicular" interstitial gland, in T. europaea. Plasma androstenedione did not show significant seasonal variation, but plasma testosterone (1.06 +/- 0.2 ng/ml) and gonadal testosterone concentration (1.57 +/- 0.65 microgram/mg protein) in females in autumn were significantly higher (p < 0.02) than plasma (0.4 +/- 0.2 ng/ml) and gonadal (0.24 +/- 0.21 microgram/mg) concentrations in pregnant or immediately postpartum females in spring. Our data also reveal selective metabolic production of testosterone from radiolabeled steroid precursors (progesterone and androstenedione) by these ovarian interstitial tissues and male testes; estradiol is produced by ovarian tissue but not interstitial gland or testis.

Androstenedione↗
PubMed1998

Androgens and masculinization of genitalia in the spotted hyaena (Crocuta crocuta). 1. Urogenital morphology and placental androgen production during fetal life.

According to common understanding of sexual differentiation, the formation and development of a penile clitoris in female spotted hyaenas requires the presence of naturally circulating androgens during fetal life. The purpose of the present study was to determine potential source(s) of such fetal androgens by investigating the timing of urogenital development and placental production of androgen during early and mid-gestation. Fetuses determined to be female by molecular techniques (lack of SRY gene) at days 33 and 48 of gestation had undifferentiated gonads, but the clitoris was already 'masculinized' and was generally similar to the phallus of a 50-day-old male fetus. Wolffian and Müllerian ducts terminated at the urogenital sinus in both sexes and a urethra was present along the entire length of the clitoris and penis. The adrenal gland was large and histologically differentiated at 33 days. Steroid gradients across the uterus (a drop in delta 4-androstenedione, with increases in oestrogen and androgen), and high androstenedione in ovarian veins indicated that ovarian androstenedione was metabolized and secreted as testosterone by the placenta throughout gestation. In vitro, whole or homogenized placentae at days 48 and 58 of gestation (110 days total) metabolized radiolabelled androstenedione into testosterone and oestradiol; the specific enzymatic activity of early placental tissues was higher than at later stages. A human placental homogenate had higher aromatase activity but did not produce testosterone unless aromatase was inhibited. Infusion of labelled androstenedione into the uterine arteries of hyaenas demonstrated the conversion of this substrate into testosterone and oestradiol and their secretion into the fetal circulation. Evidently, androgen is produced by the placenta and secreted into the fetal circulation from early in pregnancy when masculinization is first evident, before differentiation of the fetal ovary.

Androgens↗
PubMed1998

Androgens and masculinization of genitalia in the spotted hyaena (Crocuta crocuta). 2. Effects of prenatal anti-androgens.

Pregnant spotted hyaenas were treated with anti-androgens to interfere with the unusually masculine 'phallic' development that characterizes females of this species. The effects on genital morphology and plasma androgen concentrations of infants were studied during the first 6 months of life. Although there were consistent 'feminizing' effects of prenatal anti-androgen treatment on genital morphology in both sexes, such exposure did not produce males with extreme hypospadia, as it does in other species, nor did it produce females with a 'typical' mammalian clitoris and external vagina. 'Feminization' of males resulted in a penis with the morphological features of the hyaena clitoris, and 'feminization' of females exaggerated the sex differences that are typical of this species. The effects of treatment were present at birth and persisted for at least 6 months. Treatment of pregnant females with flutamide and finasteride also markedly reduced circulating concentrations of testosterone and dihydrotestosterone in maternal plasma during pregnancy. Plasma delta 4-androstenedione was reduced in the female, but not the male, infants of treated mothers, consistent with an epigenetic hypothesis previously advanced to explain hormonal 'masculinization' of females. The present 'feminizing' effects of prenatal anti-androgen treatment are consistent with contemporary understanding of sexual differentiation, which accounts for morphological variation between the sexes in terms of steroids. However, current theory does not account for the basic genital structure of females and the present data suggest that development of the male penis and scrotum, and the female clitoris and pseudoscrotum, in spotted hyaenas may involve both androgen-dependent and androgen-independent components.

5-alpha Reductase Inhibitors↗
PubMed1998

Androgens and masculinization of genitalia in the spotted hyaena (Crocuta crocuta). 3. Effects of juvenile gonadectomy.

Studies involving the administration of anti-androgens to spotted hyaenas during fetal development have raised questions concerning the precise contributions of steroids to phallic growth in these animals. If gonadal androgens promote postnatal penile growth in males, the following would be expected: (a) a period of accelerated growth accompanying achievement of puberty, and (b) a marked reduction in adult penile size and density of penile spines after gonadectomy. If a similar androgenic pubertal process stimulates clitoral growth in these highly 'masculinized' hyaenas, parallel observations in females would be expected; however, the role of oestrogens in accounting for female-typical clitoral development would also have to be considered. The results of the present study suggest a limited role, if any for androgenic stimulation of phallic growth. That is, penile growth was greater during the 10 month period preceding puberty, than during an 18-month period that included the traditional increase in pubertal androgens. In addition, pre-pubertal castration had minimal effects on penile length, diameter, or the presence of penile spines. In females, most clitoral growth also occurred before puberty, although pre-pubertal ovariectomy produced significant reductions in clitoral diameter and the elasticity of the urogenital meatus. These feminine characteristics which normally distinguish the female from the male phallus in this species, were partially restored by a brief period of oestrogen administration. Both sexes displayed erections many years after pre-pubertal castration. The results of the present study suggest that postnatal phallic growth is largely independent of gonadal steroids, with oestrogenic facilitation of female-typical clitoral characteristics in spotted hyaenas.

Androgens↗
PubMed1997

A continuing survey of drug-resistant tuberculosis, New York City, April 1994.

BACKGROUND: A 1991 survey showed high levels of drug resistance among tuberculosis patients in New York, NY. As a result, the tuberculosis control program was strengthened, including expanded use of directly observed therapy and improved infection control. METHODS: We collected isolates from every patient in New York City with a positive culture for Mycobacterium tuberculosis during April 1994; results were compared with those in the April 1991 survey. RESULTS: From 1991 to 1994, the number of patients decreased from 466 to 332 patients. The percentage with isolates resistant to 1 or more antituberculosis drugs decreased from 33% to 24% (P < .01); with isolates resistant to at least isoniazid decreased from 26% to 18% (P < .05); and with isolates resistant to both isoniazid and rifampin decreased from 19% to 13% (P < .05). The number of patients with isolates resistant to both isoniazid and rifampin decreased by more than 50%. Among never previously treated patients, the percentage with resistance to 1 or more drugs decreased from 22% in 1991 to 13% in 1994 (P < .05). The number of patients with consistently positive culture results for more than 4 months decreased from 130 to 44. A history of antituberculosis treatment was the strongest predictor of drug resistance (odds ratio = 3.1; P < .001). Human immunodeficiency virus infection was associated with drug resistance among patients who never had been treated for tuberculosis. CONCLUSIONS: Drug-resistant tuberculosis declined significantly in New York City from 1991 to 1994. Measures to control and prevent tuberculosis were associated with a 29% decrease in the proportion of drug resistance and a 52% decrease in the number of patients with multidrug-resistant tuberculosis.

AIDS-Related Opportunistic Infections↗
PubMed1997

Pattern and source of secretion of relaxin in the reproductive cycle of the spotted hyena (Crocuta crocuta).

Female spotted hyenas are highly masculinized at birth and have no external vagina. Copulation with males and birth of young are accomplished through the central urogenital canal of the clitoris. This unusual adaptation requires remarkable changes in the elasticity of the connective tissues of the clitoris, without which neither copulation nor birth would be possible. We hypothesized that relaxin, a hormone that increases the extensibility of the connective tissues of the uterus and cervix of many other mammalian species, plays a role in the clitoral changes observed in hyenas. Serum relaxin was determined by specific RIA. Relaxin was not detected in serum of males, pubertal or nonpregnant adult females, or ovariectomized females. Immunoactive relaxin was detected in serum of juveniles at the time of initial growth of the urogenital meatus. High concentrations of immunoactive relaxin appeared in the serum of pregnant hyenas in the 2 wk preceding parturition. Immunoassays of extracts of hyena tissues and serum obtained from uterine and ovarian veins indicated that the placenta was the predominant source of relaxin, with possible ovarian contributions. Circulating relaxin decreased promptly following cesarean section near term. We conclude that relaxin secretion coincides with changes in extensibility of clitoral connective tissues 1) during growth of the clitoris in juveniles and 2) near the time of parturition in adults.

Animals↗
PubMed1996

Sexual dimorphism of perineal muscles and motoneurons in spotted hyenas.

Female spotted hyenas are known for their male-like genitalia, high levels of aggression, and dominance over males, characteristics which are attributed to exposure to elevated levels of testosterone in utero. Although the nervous system of spotted hyenas has not previously been examined, one might predict that neural systems which are sexually dimorphic in other mammals would be monomorphic in this species. Spinal motoneurons which innervate muscles associated with the phallus are located in Onuf's nucleus and are more numerous in males than in females in a wide array of mammals. Onuf's nucleus was examined in adult and neonatal spotted hyenas and, contrary to expectation, was found to be sexually dimorphic in the typical mammalian pattern: Males have significantly more motoneurons in Onuf's nucleus than do females. This dimorphism was correlated with a previously undescribed dimorphism in the relevant target musculature. Specifically, the morphology of the bulbocavernosus muscle is distinctly different in male and female spotted hyenas. Pregnant hyenas were treated with anti-androgen in an attempt to interfere with the actions of androgen during fetal development. Motoneuron number in Onuf's nucleus and the morphology of the bulbocavernosus muscle were feminized in males exposed to anti-androgen in utero.

Androgen Antagonists↗
PubMed1996

Identification of a novel oxazolidinone (U-100480) with potent antimycobacterial activity.

During the course of our investigations in the oxazolidinone antibacterial agent area, we have identified a subclass with especially potent in vitro activity against mycobacteria. The salient structural feature of these oxazolidinone analogues, 6 (U-100480), 7 (U-101603), and 8 (U-101244), is their appended thiomorpholine moiety. The rational design, synthesis, and evaluation of the in vitro antimycobacterial activity of these analogues is described. Potent activity against a screening strain of Mycobacterium tuberculosis was demonstrated by 6 and 7 (minimum inhibitory concentrations or MIC's < or = 0.125 micrograms/mL). Oxazolidinones 6 and 8 exhibit MIC90 values of 0.50 micrograms/mL or less against a panel of organisms consisting of five drug-sensitive and five multidrug-resistant strains of M. tuberculosis, with 6 being the most active congener. Potent in vitro activity against other mycobacterial species was also demonstrated by 6. For example, 6 exhibited excellent in vitro activity against multiple clinical isolates of Mycobacterium avium complex (MIC's = 0.5-4 micrograms/mL). Orally administered 6 displays in vivo efficacy against M. tuberculosis and M. avium similar to that of clinical comparators isoniazid and azithromycin, respectively. Consideration of these factors, along with a favorable pharmaco-kinetic and chronic toxicity profile in rats, suggests that 6 (U-100480) is a promising antimycobacterial agent.

Acetamides↗
PubMed1996

In vitro activities of U-100592 and U-100766, novel oxazolidinone antibacterial agents.

Oxazolidinones make up a relatively new class of antimicrobial agents which possess a unique mechanism of bacterial protein synthesis inhibition. U-100592 (S)-N-[[3-[3-fluoro-4-[4-(hydroxyacetyl)-1-piperazinyl]- phenyl]-2-oxo-5-oxazolidinyl]methyl]-acetamide and U-100766 (S)-N-[[3-[3-fluoro-4-(4-morpholinyl)phenyl]- 2-oxo-5-oxazolidinyl]methyl]-acetamide are novel oxazolidinone analogs from a directed chemical modification program. MICs were determined for a variety of bacterial clinical isolates; the respective MICs of U-100592 and U-100766 at which 90% of isolates are inhibited were as follows: methicillin-susceptible Staphylococcus aureus, 4 and 4 micrograms/ml; methicillin-resistant S. aureus, 4 and 4 micrograms/ml; methicillin-susceptible Staphylococcus epidermidis, 2 and 2 micrograms/ml; methicillin-resistant S. epidermidis, 1 and 2 micrograms/ml; Enterococcus faecalis, 2 and 4 micrograms/ml; Enterococcus faecium, 2 and 4 micrograms/ml; Streptococcus pyogenes, 1 and 2 micrograms/ml; Streptococcus pneumoniae, 0.50 and 1 microgram/ml; Corynebacterium spp., 0.50 and 0.50 micrograms/ml; Moraxella catarrhalis, 4 and 4 micrograms/ml; Listeria monocytogenes, 8 and 2 micrograms/ml; and Bacteroides fragilis, 16 and 4 micrograms/ml. Most strains of Mycobacterium tuberculosis and the gram-positive anaerobes were inhibited in the range of 0.50 to 2 micrograms/ml. Enterococcal strains resistant to vancomycin (VanA, VanB, and VanC resistance phenotypes), pneumococcal strains resistant to penicillin, and M. tuberculosis strains resistant to common antitubercular agents (isoniazid, streptomycin, rifampin, ethionamide, and ethambutol) were not cross-resistant to the oxazolidinones. The presence of 10, 20, and 40% pooled human serum did not affect the antibacterial activities of the oxazolidinones. Time-kill studies demonstrated a bacteriostatic effect of the analogs against staphylococci and enterococci but a bactericidal effect against streptococci. The spontaneous mutation frequencies of S. aureus ATCC 29213 were <3.8 x 10(-10) and <8 x 10(-11) for U-100592 and U-100766, respectively. Serial transfer of three staphylococcal and two enterococcal strains on drug gradient plates produced no evidence of rapid resistance development. Thus, these new oxazolidinone analogs demonstrated in vitro antibacterial activities against a variety of clinically important human pathogens.

Acetamides↗
PubMed1996

Characterization of streptomycin resistance mechanisms among Mycobacterium tuberculosis isolates from patients in New York City.

From a collection of 367 isolates of Mycobacterium tuberculosis from patients in New York City in 1994, 45 isolates (12.3%) were resistant in vitro to 2 micrograms or more of streptomycin (SM) per ml. We further evaluated these isolates for levels of SM resistance and for mutations previously associated with resistance in the rpsL (S12 ribosomal protein) gene and the rrs (16S rRNA)-coding region. Twenty-four isolates, representing nine distinct patterns of susceptibility to antituberculosis drugs, were resistant to 500 micrograms of SM per ml and shared a common point mutation at nucleotide 128 in the rpsL gene. This mutation, which substitutes lysine for arginine in the S12 ribosomal binding protein, was not present in isolates with low-level SM resistance or in SM-susceptible control isolates. Among 20 isolates with low-level SM resistance, one possessed a substitution (C-->G865) in the 912 loop of the rrs gene. No mutations in the 530 loop of the rrs coding region were detected, suggesting the presence of an alternative SM resistance mechanism in 19 isolates. Single-strand conformation polymorphisms of mutants were readily detected by a nonradioactive gel screen.

Antibiotics, Antitubercular↗