PubMed Health⌕ Search

Biomedical subjects

S Handwerger

Publications and source records attributed to S Handwerger.

At least 109 records · Page 6Linked to original sources

Tuberculosis and the acquired immunodeficiency syndrome at a New York City hospital: 1978-1985.

Recent reports have described an increase in cases of tuberculosis in several urban centers. To investigate the possible relationship between tuberculosis and the acquired immunodeficiency syndrome (AIDS), we reviewed case records at a New York City hospital between 1978 and 1985. During this period, tuberculosis occurred in 15.1 percent of AIDS patients with a history of parenteral drug use and 4.4 percent of all other patients with AIDS. The yearly rate of tuberculosis more than doubled during the study period; this increase was entirely attributable to cases among patients with AIDS or AIDS-related complex and parenteral drug users, a group at high risk for the development of AIDS. Patients with AIDS and tuberculosis were younger and more frequently men than other patients with tuberculosis, and were more likely to have extrapulmonic disease. In the majority of patients, tuberculosis occurred prior to confirmation of CDC-defined AIDS. Forty-four percent of patients with AIDS-related complex at the time of diagnosis of tuberculosis subsequently developed AIDS. Mycobacterium tuberculosis appears to be yet another opportunistic agent to which patients with AIDS retroviral-induced immunodeficiency are susceptible.

AIDS-Related Complex↗

Failure of fasting and changes in plasma metabolites to affect spontaneous fluctuations in plasma concentrations of ovine placental lactogen.

The relationships between plasma concentrations of energy substrates and placental lactogen (PL) were investigated in pregnant ewes. In successive hourly samples of plasma PL, concentrations varied by +/- 30% but were not related to general activity or feeding of the ewes or the time of day. Fasting ewes for 72 h did not alter the pattern or the mean PL titres. Insulin-induced acute hypoglycaemia, hyperglycaemia and decreases or increases in free fatty acids (FFA) all failed to alter PL levels significantly during 5-h post-treatment periods. These experiments demonstrate that PL secretion in the ewe fluctuates markedly and is unaffected by changes in plasma glucose FFA concentrations.

Acetates↗

A comparative study of ovine placental lactogen and prolactin secretion patterns in genetically dissimilar fetal co-twins.

Simultaneous fetal and maternal ovine placental lactogen (oPL) and prolactin (oPRL) measurements were determined from blood samples collected from six mixed breed (MB; gestation = 141.5 +/- .7 d) pregnancies and single Rambouillet (n = 2; Ra gestation = 148 and 149 d) and Finnish Landrace (n = 2; Finn gestation = 141 and 143 d) pregnancies for the purpose of examining a possible relationship between fetal-maternal oPL and oPRL levels in the prepartal period. The MB pregnancies were produced by embryo transfer and consisted of genetically different fetuses co-existing in a common uterine environment. Despite the apparent prematurity of Ra co-twins in MB pregnancies, similar oPL and oPRL patterns during the final 14 d of gestation were observed for both Ra and Finn co-twins. Fetal oPL levels decreased at parturition (range 23 to 90 ng/ml) to approximately 60% of values recorded 8 d prepartum (range 100 to 150 ng/ml) in both fetal siblings. Increases in fetal oPRL concentrations, first observed at approximately 4 d prepartum in all fetuses, reached peak concentrations (40 to 60 ng/ml) at term. Results of this study suggest a similarity in regulation of fetal oPL and oPRL secretion, despite genetic differences for gestation period, in fetuses in the M.B. pregnancy.

Animals↗

Arachidonic acid stimulates 45calcium efflux and hPL release in isolated trophoblast cells.

Previous investigations from this laboratory have indicated that arachidonic acid stimulates a rapid, dose-dependent and reversible increase in hPL release which is not dependent on cyclooxygenase or lipoxygenase metabolism. To investigate further the mechanism by which arachidonic acid stimulates the release of hPL, the effect of arachidonic acid on the release of 45Ca from perifused cells prelabelled with 45CaCl was examined in an enriched cell culture population of term human syncytiotrophoblast. Arachidonic acid (10-100 microM) stimulated a dose-dependent, rapid, and reversible increase in the release of both 45Ca and hPL from the perifused placental cells. On the other hand, palmitic acid had little effect on either hPL release or 45Ca release even at concentrations as high as 100 microM. Ionophore A23187 (1-10 microM) also stimulated a dose-dependent and reversible increase in hPL release. Since arachidonic acid increases the mobilization of cellular calcium, as reflected by the increased 45calcium efflux, and since an increase in the intracellular calcium concentration appears to stimulate an increase in hPL release, these results suggest that the stimulation of hPL release by arachidonic acid may be due, at lease in part, to the effects of the fatty acid on cellular calcium mobilization.

Arachidonic Acid↗

Episodic luteinizing hormone release in hyperprolactinemic women.

Episodic luteinizing hormone (LH) secretion was studied in 16 hyperprolactinemic women (microprolactinoma, 12; idiopathic, 4) with amenorrhea of 1.4 to 7 years' duration. Blood samples obtained through an indwelling venous catheter at 20-minute intervals over 5 hours were assayed for LH, follicle-stimulating hormone (FSH), prolactin (PRL), and estrogen (E) (selected samples). LH pulse patterns were divided arbitrarily into high-amplitude release (LH pulse greater than 10 mIU/ml) (n = 7), low-amplitude release (LH pulse less than 10 mIU/ml (n = 6), and no release (n = 3). Mean pulse frequencies in women with high-amplitude and low-amplitude release were 2.4 +/- 0.3 (mean +/- standard error) and 1.3 +/- 0.2 pulses/5 hours and differed significantly (P greater than 0.02), whereas mean percentages of secretory increment were 155% and 62%, respectively. Mean LH concentrations in the high-amplitude (18.0 +/- 0.8 mIU/ml), low-amplitude (13.2 +/- 0.6 mIU/ml), and no-pulse groups (7.5 +/- 0.2 mIU/ml) differed significantly (P greater than 0.02). Despite the different pulse patterns, mean serum FSH, PRL, and total E concentrations were similar. The lack of episodic LH release and/or low infrequent LH release could account for the absence of cyclic hypothalamic pituitary ovarian function, although other mechanism(s) may be operative in women with augmented LH secretory pulses.

Adult↗

Listeria monocytogenes: a rare cause of opportunistic infection in the acquired immunodeficiency syndrome (AIDS) and a new cause of meningitis in AIDS. A case report.

A forty-two year-old male homosexual with the acquired immunodeficiency syndrome (AIDS) developed Listeria monocytogenes septicemia and meningitis. The gastrointestinal tract was the likely portal of entry. The patient was treated with intravenous ampicillin with complete and permanent resolution of his listerial infection. Although L. monocytogenes infection has been reported as an uncommon complications of AIDS, we are unaware of Listeria meningitis being previously reported in an AIDS patient. It is hoped that this case report will alert health care workers to the possibility of Listeria infection in AIDS patients, particularly since this infection responds well to readily-available antibiotic therapy. The microbiology, epidemiology, clinical, and neurologic aspects of listerial infection and general aspects of the acquired immunodeficiency syndrome are discussed.

Acquired Immunodeficiency Syndrome↗

Alterations in penicillin-binding proteins of clinical and laboratory isolates of pathogenic Streptococcus pneumoniae with low levels of penicillin resistance.

Several recent surveys of clinical isolates have indicated that substantial fractions of naturally occurring populations of Streptococcus pneumoniae have undergone a distinct upward move in the required minimal inhibitory concentration (MIC) of benzylpenicillin (from a range of 0.006-0.008 to 0.03-0.05 microgram/ml). Evidence is presented that in clinical pneumococcal isolates, penicillin-binding proteins (PBPs) groups 1 and 2 have a decreased affinity for radioactive benzylpenicillin as compared with penicillin-sensitive isolates from the same locale. Exposure of a penicillin-sensitive type 2 strain (MIC, 0.006 microgram/ml) to sequentially increasing concentrations of penicillin allowed the isolation of spontaneous resistant mutants with stepwise increases in the MIC of penicillin required (0.01-0.02, 0.025-0.05, and 0.1 microgram/ml), and in these laboratory isolates too, PBP groups 1 and 2 showed decreased affinity for labeled benzylpenicillin. DNA from the low-level resistant clinical or laboratory isolates could be used to transform the appropriate levels of penicillin resistance into penicillin-sensitive laboratory isolates. These findings suggest that significant fractions of natural pneumococcal populations may have acquired one or two of the low-level penicillin resistance genes.

Bacterial Proteins↗

Alterations in kinetic properties of penicillin-binding proteins of penicillin-resistant Streptococcus pneumoniae.

Earlier studies have shown that the highly penicillin-resistant South African Strains of pneumococci contain altered penicillin-binding proteins (PBPs) (S. Zighelboim and A. Tomasz, Antimicrob. Agents Chemother. 17:434-442, 1980). We now describe a detailed quantitative characterization of the reaction of radioactively labeled penicillin with the PBPs of the penicillin-susceptible and penicillin-resistant pneumococci and several intermediate-resistance-level genetic transformants as well. The altered binding of the antibiotic by the PBPs of resistant cells appears to be due to a combination of two factors: lower drug affinity and change in the cellular amounts of PBPs. No alteration in the rates of deacylation of the penicilloyl-PBPs of the resistant cells was detected.

Bacterial Proteins↗

Penicillin-binding proteins of penicillin-susceptible and -resistant pneumococci: immunological relatedness of altered proteins and changes in peptides carrying the beta-lactam binding site.

There are several major differences between the penicillin-binding proteins (PBPs) of highly penicillin-resistant and -susceptible strains of pneumococci. The highest-molecular-size PBP 1a (98 kilodaltons [kDa]) of susceptible pneumococci is not detectable in resistant bacteria. Instead, resistant strains contain a PBP of smaller size: 92 and 94 kDa in South African strains 8249 and A95210, respectively, and 96 kDa in New Guinea strain 2955 (S. Zighelboim and A. Tomasz, Antimicrob. Agents Chemother. 17:434-442, 1980). Using antibodies prepared against PBP 1a of penicillin-susceptible pneumococci, we demonstrated that these anomalous-sized proteins in the resistant strains are immunologically related to PBP 1a of penicillin-susceptible bacteria. A second difference between the PBP patterns of strain 8249 and the susceptible pneumococci is that the 78-kDa PBP 2b is not detectable by the radioactive penicillin binding assay in the resistant strain. Using antibodies prepared against PBP 2b of susceptible cells, we demonstrated the presence of PBP 2b in membrane preparations from strain 8249 cells. Thus, the poor detection of this PBP appears to be related to its greatly decreased affinity for the antibiotic molecule. We also compared the patterns of penicillin-labeled peptides derived from PBPs of resistant and susceptible cells during partial proteolysis by V8 protease. Several changes were observable in small peptides carrying the beta-lactam binding site generated from the high Mr (PBP 1a-related) binding proteins. In contrast, no differences in the pattern of penicillin-labeled peptides were seen when the pattern of PBP 2a of susceptible pneumococci was compared with the peptide pattern of PBP 2a from resistant strains. One of the resistant isolates (strain 2955) also had a PBP 3 with a higher-than-normal molecular weight. This protein gave strong positive reaction with antibodies against PBP 3 of susceptible cells. Examination of the pattern of penicilloyl peptides generated from the susceptible and resistant PBP 3s during partial proteolysis revealed only differences which seem to reside distant from the beta-lactam binding site.

Anti-Bacterial Agents↗

Activation of protein kinase C inhibits synthesis and release of decidual prolactin.

Activation of calcium-activated, phospholipid-dependent protein kinase C by diacylglycerol and phorbol esters has been shown to mediate release of hormones in many systems. To determine whether protein kinase C activation is also involved in the regulation of prolactin release from human decidua, we have examined the effects of various acylglycerols and phorbol esters on the synthesis and release of prolactin from cultured human decidual cells. sn-1,2-Dioctanoylglycerol (diC8), which is known to stimulate protein kinase C in other systems, inhibited prolactin release in a dose-dependent manner with maximal inhibition of 53.1% (P less than 0.01) at 100 microM. Diolein (100 microM), which also stimulates protein kinase C activity in some systems, inhibited prolactin release by 21.3% (P less than 0.05). Distearin and dipalmitin, which are much less effective in activating protein kinase C, and monopalmitin and tripalmitin, which do not activate protein kinase C, had no significant effect on prolactin release. Phorbol 12-myristate 13-acetate (PMA), phorbol 12,13-didecanoate, and 4 beta-phorbol 12,13-dibutyrate, which activate protein kinase C in other systems, also inhibited the release of prolactin, while the protein kinase C inactivate 4 alpha-phorbol-12,13-didecanoate was without effect. The inhibition of prolactin release was secondary to a decrease in prolactin synthesis. The amounts of prolactin synthesized by cells exposed to diC8 (300 microM) or PMA (10(-7) M) for 30 min were 56.3 and 50.0% less than that synthesized by control cells (P less than 0.01 in each instance).(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗

Placental lactogen and GH receptors in sheep liver: striking differences in ontogeny and function.

To determine whether changes in the relative biological potencies of ovine placental lactogen (oPL) and ovine growth hormone (oGH) during development derive from ontogenetic changes in the binding of these hormones to hepatic receptors, we have compared the binding of 125I-oPL and 125I-oGH to hepatic membranes from fetal lambs and pregnant sheep at mid- and late gestation and from postnatal sheep at 1 day to 7 mo of age. Specific high-affinity 125I-oPL binding sites in ovine fetal liver were detected as early as day 70 of gestation (term = 145 days), and the number of fetal 125I-oPL binding sites increased progressively throughout the latter half of gestation, reaching a maximum (11.2 fmol/mg protein) at 3-7 days before parturition. The potency of oPL (Kd 0.27 nM) in competing for 125I-oPL binding sites was 90 and 1,300 times greater than that of oGH and ovine prolactin, respectively. Although the number of fetal 125I-oPL binding sites increased throughout pregnancy, there was little or no specific binding of 125I-oGH noted in the fetus. Treatment of fetal liver membranes with 4 M MgCl2 did not enhance the subsequent specific binding of 125I-oGH, suggesting that the low specific binding of oGH did not result from occupation of hepatic receptors by endogenous circulating oPL or oGH. In contrast, MgCL2 treatment markedly increased the apparent number of fetal 125I-oPL binding sites, suggesting that oPL receptors in fetal liver are partly saturated in vivo by oPL.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

The glycogenic effects of placental lactogen and growth hormone in ovine fetal liver are mediated through binding to specific fetal ovine placental lactogen receptors.

To examine the relative roles of placental lactogen (PL) and GH in fetal metabolism, we have examined the effects of ovine PL (oPL), ovine GH (oGH), and ovine PRL (oPRL) on glycogen metabolism in cultured ovine fetal hepatocytes and have examined the binding of these hormones to hepatic membranes from fetal and neonatal lambs. In ovine fetal hepatocytes, oPL (150 ng/ml-20 micrograms/ml) stimulated dose-dependent increases in [14C]glucose incorporation into glycogen (18-167%) and total cellular glycogen content (10-69%). oGH and oPRL also stimulated glycogen synthesis in fetal hepatocytes, but the potencies of these hormones were only 12% and 4% that of oPL. The dose-response curves of the three hormones were parallel, and their maximal effects were identical, suggesting a common mechanism of action. In hepatic membranes from fetal lambs, the maximal specific binding of [125I]oPL was 26.3% while the maximal specific binding of [125I]oGH was only 0.9-1.5%. The binding of [125I]oPL was saturable and reversible and varied with incubation time and temperature. Unlabeled oPL (1 ng/ml-5 micrograms/ml) caused a dose-dependent inhibition of the binding of [125I]oPL to fetal hepatic membranes, with half-maximal displacement of [125I]oPL by 5-7 ng unlabeled oPL/ml. oGH and oPRL caused parallel displacement of [125I]oPL, but with potencies only 2% and 0.1% that of oPL. Scatchard analysis of oPL dose-response curves indicated that the hormone bound to a single class of receptors with a dissociation constant of 1.1 X 10(-10) M. The maximal specific binding of [125I]oGH to hepatic membranes of neonatal lambs (20.1%) greatly exceeded the binding of oGH to fetal hepatic membranes. In addition, the potency of oGH in competing for [125I]oPL binding sites in neonatal liver greatly exceeded the potency of oGH in competing for [125I]oPL binding sites in fetal liver. Although the biological effects of both oPL and oGH in postnatal subprimate tissues may be mediated through binding to nonprimate GH receptors, the results of these studies suggest that the glycogenic effects of oPL in ovine fetal liver are mediated through binding to specific fetal oPL receptors. The relatively weak biological effects of oGH and oPRL in ovine fetal liver appear to be mediated through the binding of the hormones to fetal oPL receptors. The presence of specific, high affinity PL receptors in ovine fetal tissues provides a mechanism whereby oPL may function as a GH in the ovine fetus.

Animals↗

Sn-1,2-diacylglycerols and phorbol esters stimulate the synthesis and release of human placental lactogen from placental cells: a role for protein kinase C.

Activation of calcium-stimulated phospholipid-dependent protein kinase C (PKC) by diacylglycerols and phorbol esters has been shown to mediate the release of secretory proteins in several systems. To determine whether PKC activation is involved in regulation of the release of human placental lactogen (hPL) from the placenta, we examined the effects of various acylglycerols and phorbol esters on the release of hPL from cultured human trophoblast cells. Sn-1,2-dioctanoylglycerol (diC8) and phorbol-12-myristate-13-acetate (PMA), both of which stimulate placental protein kinase C activity, caused dose-dependent increases in hPL release over a 0.5-h period. The maximal amounts of hPL released in response to diC8 (300 microM) and PMA (10(-8) M) were 200-300% and 150-225% greater, respectively, than that released in response to diluent alone. Acylglycerols and phorbol esters, which are less potent stimulators of PKC activity in other systems, stimulated hPL release to a lesser extent than either diC8 or PMA. PKC-inactive acylglycerols and phorbol esters were without effect. After 0.5 h of exposure, diC8 (300 microM)- and PMA (10(-8) M)-exposed cells synthesized 257.5% and 250.3% more hPL than control cells. Cycloheximide at a dose (50 micrograms/ml) that inhibited the synthesis of trichloroacetic acid-precipitable [35S]methionyl placental proteins by more than 80% completely blocked the stimulatory effects of diC8 and PMA on hPL synthesis and release. Although diC8 and PMA stimulated the synthesis and release of hPL, these compounds had no effect on the release of hCG and did not cause the release of the cytosolic enzymes lactic dehydrogenase and alkaline phosphatase. The demonstration that acylglycerols and phorbol esters stimulate the synthesis and release of hPL strongly implicates protein kinase C activation in the mechanisms of hPL synthesis and release.

Cycloheximide↗

Characterization and partial purification of a serum protein which stimulates the release of human placental lactogen in vitro.

The factors that regulate the release of human placental lactogen (hPL) are poorly understood. To determine whether hPL is regulated by a factor(s) in pregnancy serum, placental explants were exposed for up to 9 h to a pool of serum samples from 50 women in the third trimester. In static explant cultures, the addition of the serum (0.6-10.8 mg protein/ml) caused a dose-dependent and reversible increase in hPL release during a 6-h period. The maximum release by the explants exposed to pregnancy serum was 200-250% greater than that of control explants, and the half-maximal dose was 2-3 mg/ml. Perifusion of placental explants with 15% pregnancy serum (final concentration, 10.5 mg protein/ml) also caused a significant release in hPL within 15 min, which reached a maximum of 200-225% above control levels. Two other pools of pregnancy serum samples as well as individual samples from four pregnant women also stimulated hPL release. Although pregnancy serum significantly stimulated hPL release, there was no increase in either the release of hCG or trichloroacetic acid-precipitable 35S-labeled proteins. Serum from nonpregnant women and men, as well as bovine serum, also stimulated hPL release, but their potencies were only 20-25% that of pregnancy serum. Chicken and porcine serum (10.8 mg/ml each) caused only small (less than 10%) increases in hPL release, and purified human albumin and ovalbumin had no effect. Dialysis or ultrafiltration of pregnancy serum using membranes with mol wt exclusions of 10K daltons caused no loss of activity. Delipidation of pregnancy serum with acetone-ethanol or acid-charcoal also caused no loss of activity, but treatment with trypsin caused greater than 95% loss of activity. Purification of the stimulatory activity by successive chromatographies on Sephadex G-150, Cibacron blue, and Sephadex G-75 resulted in an approximately 800-fold increase in specific activity. Approximately 90% of the total activity eluted from Sephadex G-75 with an apparent mol wt of 31,000, the remainder eluted in the void volume. Although partially purified pregnancy serum stimulated hPL release, the active fractions did not affect the release of rat LH, FSH, or GH from rat pituitary cells or the release of PRL from human decidual explants. Incubation of placental explants in calcium-deficient medium blocked the stimulatory effect of the partially purified pregnancy serum by greater than 90%. These studies indicate that human serum contains a protein(s) that causes a specific, rapid, dose-dependent, and reversible increase in hPL release.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

Human chorionic gonadotropin alpha-subunit of normal placenta: characterization of synthesis and association with beta-subunit.

The forms of human chorionic gonadotropin (hCG) alpha-subunit synthesized and released by normal placental tissue were examined in explants of first trimester placenta that had been incubated for 30 min with [35S]methionine and then incubated for 6 h in medium containing unlabeled methionine. The media and tissue extracts collected at 0, 0.5, 1, 2, 4, and 6 h after the exposure to [35S]methionine were chromatographed on Sephadex G-100 and the amounts of radioimmunoassayable alpha-subunit and immunoprecipitable 35S-labeled alpha-subunit were determined. In tissue extracts, a single form of alpha-subunit was observed at 0 h that had an apparent molecular weight smaller (Ve/Vo = 1.90) than that of a urinary hCG alpha reference preparation (Ve/Vo = 1.81). With chase times of 0.5, 1, 2, and 4 h, a second peak of alpha-subunit was detected that had a larger apparent molecular weight (Ve/Vo = 1.68), and the ratio of large to small forms increased progressively with incubation time. In contrast to that in the extracts, the 35S-labeled alpha-subunit in the culture medium consisted entirely of the large form. Large and small intracellular forms of free alpha-subunit exhibited less than 2% recombination with beta-subunit, as evidenced by gonadotropin receptor binding activity. These studies suggest that normal placental tissue synthesizes a small precursor form of free hCG alpha-subunit that is converted to a larger form prior to secretion and that the free forms of alpha-subunit do not bind to purified hCG beta-subunit.

Chorionic Gonadotropin↗

Ovine placental lactogen inhibits glucagon-induced glycogenolysis in fetal rat hepatocytes.

The effect of ovine placental lactogen (oPL) on glucagon-stimulated glycogenolysis was studied in cultured hepatocytes from 20-day-old fetal rats. Pretreatment of hepatocytes with oPL (0.5-5 micrograms/ml) significantly attenuated the inhibitory effect of glucagon on glycogen synthesis. Hepatocytes exposed to glucagon alone at 1, 5, and 20 nM incorporated 32.0, 43.2, and 62.1% less [14C]glucose into glycogen than control hepatocytes. However, hepatocytes pretreated for 1 h with oPL (1 microgram/ml) and then exposed to the same concentration of glucagon incorporated only 5.8, 9.2, and 22.1% less [14C]glucose than control cells (P less than 0.01 vs. glucagon alone). In cells preincubated for 24 h in medium containing [14C]glucose, glucagon reduced cellular [14C]glycogen and total glycogen content by 47.1 and 51.0% while oPL increased total cellular glycogen content by 105.8% and attenuated the glycogen-degradative effect of glucagon. While oPL alone had no effect on basal phosphorylase a (Pa) activity, oPL (1-10 micrograms/ml) caused a 15.3-91.6% inhibition of glucagon-stimulated Pa activity (P less than 0.01). The maximal inhibition by oPL of glucagon-stimulated Pa activity occurred within 2 min of exposure to oPL, and the effect was not blocked by cycloheximide. oPL also caused a 49.4-95.0% inhibition of (Bu)2cAMP-stimulated Pa activity (P less than 0.01), suggesting that the inhibitory effect of oPL on glucagon action is exerted, at least in part, at a site distal to the intracellular accumulation of cAMP. Insulin (1 microM) reduced basal Pa activity, abolished the stimulation of Pa activity by glucagon, and markedly attenuated the stimulation of Pa by (Bu)2-cAMP. These studies demonstrate that oPL acutely inhibits glycogen degradation in fetal rat hepatocytes and suggest that oPL promotes glycogen storage in fetal liver both by antagonizing the glycogenolytic effects of glucagon and by stimulating fetal hepatic glycogenesis.

Animals↗