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C Schoenfeld

Publications and source records attributed to C Schoenfeld.

At least 19 recordsLinked to original sources
PubMed2006

Prostaglandin-induced programmed cell death in Trypanosoma brucei involves oxidative stress.

Recently, we reported the induction of a programmed cell death (PCD) in bloodstream forms of Trypanosoma brucei by prostaglandin D(2) (PGD(2)). As this prostanoid is readily metabolized in the presence of albumin, we were prompted to investigate if PGD(2) metabolites rather than PGD(2) itself are responsible for the observed PCD. In fact, J series metabolites, especially PGJ(2) and Delta(12)PGJ(2), were able to induce PCD more efficiently than PGD(2). However, the stable PGD(2) analog 17phenyl-trinor-PGD(2) led to the same phenotype as the natural PGD(2), indicating that the latter induces PCD as well. Interestingly, the intracellular reactive oxygen species (ROS) level increased significantly under J series metabolites treatment and, incubation with N-acetyl-L-cysteine or glutathione reduced ROS production and cell death significantly. We conclude that PGJ(2) and Delta(12)PGJ(2) formation within the serum represents a mechanism to amplify PGD(2)-induced PCD in trypanosomes via ROS production.

Animals↗
PubMed1998

A splice variant of trkB and brain-derived neurotrophic factor are co-expressed in retinal pigmented epithelial cells and promote differentiated characteristics.

There is evidence suggesting reciprocal trophic interactions between photoreceptors and the retinal pigmented epithelium (RPE), but the factors involved have not been identified. In this study, we investigated the hypothesis that one or more known neurotrophic factors act upon the RPE. Cultured human and freshly isolated bovine RPE cells demonstrated saturable specific binding for [125I]labeled BDNF, NT-4/5 and NT-3 with little specific binding for CNTF and none for NGF. Cross-competition experiments showed that BDNF is the preferred ligand and cross-linking of [125I]BDNF resulted in a doublet at 160 kd that was increased in RPE cells incubated in all-trans retinoic acid. There was basal phosphorylation of a 145 kd protein recognized by an anti-trk antibody that was increased in RPE cells pulsed with BDNF. RT-PCR with primers spanning the transmembrane domain demonstrated that RPE cells express trkB mRNA lacking a region homologous to exon 9 of chicken trkB, a splice variant that has been demonstrated to preferentially interact with BDNF. Northern blots demonstrated that cultured RPE cells also express mRNA for BDNF. BDNF did not stimulate proliferation or increase survival of RPE cells in serum-free medium, but promoted a differentiated morphology and increased the expression of cellular retinaldehyde binding protein, a marker of the differentiated state in RPE cells. An RPE cell line that spontaneously shows differentiated features showed a high level of BDNF mRNA. These data demonstrate that RPE cells express a short splice variant of trkB whose activation correlates with expression of differentiated characteristics and the cells themselves are capable of producing a ligand for the receptors. Signaling through trkB could play a role in differentiation of RPE cells during development and maintenance of the differentiated state in adult RPE.

Animals↗
PubMed1987

Human semen relaxin and its correlation with the parameters of semen analysis.

The relaxin content of 92 normal semen samples and 85 semen samples selected at random was correlated to the parameters measured on routine semen analysis in those samples. The concentration of immunoactive relaxin in a sample of semen plasma did not correlate with any of the parameters commonly used for semen analysis: count, percent motility, grade of forward progression, volume, and morphology.

Humans↗
PubMed1986

Partial purification of relaxin from human seminal plasma.

Human seminal plasma contains approximately 50 ng/ml of relaxin (specific activity = 1.3 ng/mg protein). During preliminary purification, semen plasma was delipidated, rehydrated, and loaded onto small octadecyl silica columns that were eluted with a TEAF/acetonitrile gradient system. Results were monitored by radioimmunoassay. The resultant partially purified human relaxin demonstrated biologic activity in the rat uterine segment bioassay. Nine liters of semen plasma was delipidated, rehydrated in TEAF, and subjected to high-performance liquid chromatography by a step gradient followed by a linear gradient. The active eluate was further purified by ion exchange chromatography. Pooled recovery fractions provided a total of 45.8 micrograms of relaxin. An aliquot flash evaporated and desalted by gel filtration chromatography provided 1.85 micrograms of relaxin in 25.2 mg protein, specific activity 73.4. This material is being used as immunogen in the production of antihuman relaxin antibodies by monoclonal technique. Our procedure represents the first and only successful partial purification of human relaxin to yield sufficient quantity and purity for antibody production.

Animals↗
PubMed1986

The effect of relaxin and prostaglandin E2 on the motility of human spermatozoa.

Relaxin and prostaglandin E2 (PGE2) are present in human semen and have been shown to affect sperm motility. The authors further examined the effects of porcine relaxin and PGE2 on the motility of human spermatozoa. A dose-response study revealed that PGE2 at a concentration of 25 micrograms/ml is most effective in improving the motility of washed human sperm. Relaxin (100 ng/ml), PGE2 (25 micrograms/ml), or the two combined have no effect on the motility of spermatozoa in fresh, normal semen, suggesting that the constituents of fresh semen are optimal for motility. Relaxin and PGE2 individually improve the motility of washed spermatozoa. However, relaxin, but not PGE2, improves the motility of sperm in semen incubated at 37 degrees C for 5 hours (aged). In contrast to the individual substances, a combination of relaxin + PGE2 has no effect on the motility of washed spermatozoa or aged spermatozoa, suggesting that these two substances antagonize each other's actions on sperm motility. The presence of both relaxin and PGE2 in seminal plasma with normal motility spermatozoa suggests that other factors in seminal plasma regulate the effects of these substances on sperm motility.

Animals↗
PubMed1986

Effect of relaxin on human spermatozoa.

To study its effect on the motility of human spermatozoa, relaxin was added at different concentrations to human semen samples of various qualities as well as to washed spermatozoa. Relaxin in physiologic concentrations (10-100 ng/mL) had no significant effect on sperm motility in normal semen samples. However, the addition of relaxin to semen samples with low sperm motility significantly increased the motility. Addition of relaxin similarly increased the motility of spermatozoa from normal semen samples that were either aged or washed; the treatment resulted in a decrease in motility. When sperm motility was optimal, as in normal samples, addition of relaxin did not increase motility. However, in some situations of decreased motility, addition of relaxin resulted in improvement of spermatozoan motility. Relaxin may have clinical value in the treatment of male infertility.

Animals↗
PubMed1985

The effect of relaxin on the motility of sperm in freshly thawed human semen.

In an attempt to improve the motility of thawed spermatozoa after 1 week of its being frozen, we treated ten normal semen samples with 16.7 nmol relaxin and 6 mmol caffeine. Motility and grade of forward progression were examined after thawing. Caffeine significantly improved motility of spermatozoa. Relaxin, when added to semen at the time of thawing, improved motility and grade of forward progression significantly. This effect was not seen if relaxin was added before freezing. These results suggest that the biologic activity of relaxin is adversely affected by freezing and thawing in seminal plasma. These observations may have clinical importance for the improvement of motility of frozen spermatozoan samples at the time of artificial insemination and for the possible improvement of pregnancy rates.

Caffeine↗
PubMed1985

The use of voided urine temperature in the determination of basal body temperature.

The temperature of freshly voided urine has been shown to be a reliable predictor of body temperature. This relationship was confirmed for the measurement of BBT. A method was described for patients to obtain their BBT in a way that they may find more convenient than obtaining either oral or rectal temperature. The BBT graph patterns generated from the temperature of freshly voided urine closely paralleled those generated by oral temperature.

Body Temperature↗
PubMed1984

Stimulation of human sperm cervical mucus penetration in vitro by relaxin.

The effect of relaxin, a peptide hormone present in seminal plasma, on the penetration of cervical mucus by washed human sperm in vitro was studied. Penetration was analyzed by two methods. The total number of sperm per 100 X field at the 10-mm, 20-mm, and 30-mm points along a mucus-filled capillary tube was counted and the farthest distance 100 sperm and 5 sperm/100 X field penetrated the capillary tube was measured. These measurements were made at 30, 60, and 90 minutes. Treating washed sperm with physiologic concentrations of relaxin resulted in significantly increased sperm penetration as compared with sperm treated with albumin or buffer. Replacing seminal plasma to washed sperm resulted in equivalently increased penetration. The findings strongly suggest that relaxin is necessary for proper penetration of cervical mucus by human sperm.

Albumins↗
PubMed1984

The effect of an anti-insulin antiserum on human sperm motility.

Inhibition of sperm motility by anti-relaxin antiserum has been previously reported. This effect may be secondary to a nonspecific effect of immunoglobulins binding to sperm or to a specific inhibition of relaxin activity at the sperm surface. The current investigation demonstrates that an anti-insulin antiserum does not inhibit sperm motility in the same system in which an anti-relaxin antiserum results in inhibition. This supports the hypothesis that the anti-relaxin antiserum effect is specific.

Humans↗
PubMed1983

Effect of anti-relaxin antiserum on sperm motility in vitro.

Rabbit anti-relaxin antisera, but not normal rabbit sera, causes a rapid decline of motility of washed human sperm. Preincubation of the antisera with relaxin eliminates this effect. This sperm immobilization effect can serve as a basis of a rapid screening test for anti-relaxin antisera and as a novel adjuvant to barrier contraceptive methods.

Antigen-Antibody Complex↗
PubMed1982

Stimulation of human sperm motility by relaxin.

Relaxin has recently been identified in human seminal plasma (SP). This investigation was undertaken to determine the effect of relaxin on sperm motility. Washed ejaculated human sperm were incubated with or without porcine relaxin. In a series of 37 normal specimens (motility greater than or equal to 60%) relaxin attenuated the decline in grade of forward progression and percentage of motile sperm. Relaxin had a similar effect on a series of 47 subfertile specimens (motility 30% to 40%). Endogenous relaxin may play a role in delaying declines of motility and grade of forward progress in ejaculated sperm.

Animals↗
PubMed1980

Sperm motility.

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Alcoholism↗
PubMed1979

Successful management of infertility due to polyzoospermia.

Polyzoospermia is a rare cause of male infertility. In our clinical practice, patients with exceedingly high sperm counts (ranging from 650 million/ml to 1.75 billion/ml) have invariably been found to have associated poor sperm motility and poor sperm migration in postcoital tests, although the sperm appear morphologically normal. Cases of two infertile couples are presented in which each husband had sperm counts greater than 1 billion/ml. Two methods are reported for the successful management of their infertility problems: (1) precoital dilutional douching and (2) in vitro seminal fluid dilution with 5% dextrose-Ringer's lactate solution and artificial insemination homologous. Each method resulted in improved sperm motility, postcoital tests, and pregnancy.

Adult↗