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Biomedical subjects

J Cross

Publications and source records attributed to J Cross.

At least 73 records · Page 4Linked to original sources
PubMed1984

Formation of unconjugated estrogens from estrone sulfate by dispersed cells from human fetal membranes and decidua.

Experiments were performed to determine the ability of isolated cells from human amnion, chorion, and decidua to hydrolyze estrone sulfate (E1S) to free estrone (E1) and estradiol (E2). Tissues were obtained from eight women after spontaneous onset of labor and vaginal delivery and from eight women undergoing elective cesarean section at term before the onset of labor. The tissues were obtained immediately after delivery, dispersed into isolated cell preparations using 0.05% collagenase, and incubated in Krebs-Ringer bicarbonate at 37 degrees C for 4 h. E1 and E1S were measured by specific RIAs. All three tissues from both patient groups produced E1 and E2 in a dose-dependent fashion from the E1S precursor. In both patient groups, chorion and decidua cells produced significantly more E1 and E2 than amnion cells. The chorion cells from the spontaneous labor group produced significantly more E1 than chorion cells from the cesarean section group. The chorion and decidua cells from the spontaneous labor group produced significantly more E2 than corresponding cells from the cesarean section group. The hydrolysis of E1S to E1 and E2 was significantly inhibited in a dose-dependent fashion by increasing concentrations of oxytocin and (Bu)2cAMP. Dispersed cells from amnion, chorion, and decidua also converted [3H]E1S to radiochemically pure [3H]E1. Chorion and decidua cells were significantly more active in this respect than amnion. The presence of excessive amounts of dehydroepiandrosterone sulfate (DHAS) did not significantly alter this reaction. All three tissues also hydrolyzed [3H]dehydroepiandrosterone sulfate, but in chorion and decidua, this activity was significantly less than the hydrolysis of [3H]E1S. We conclude that human amnion, chorion, and decidua possess the capability to hydrolyze E1S to free estrogen and that this activity in chorion and decidua is increased after spontaneous vaginal delivery. It is possible that this activity and its regulation are important factors in the local synthesis of free estrogen, which, in turn, may influence myometrial contractility.

Adult↗
PubMed1984

Sequential methotrexate and 5-FU in CMFP (cyclophosphamide, methotrexate, 5-FU, and prednisone) therapy for breast cancer.

Forty-one women with advanced breast cancer were treated with cyclophosphamide, methotrexate, 5-FU, and prednisone. Methotrexate (200 mg/m2) was given iv 1 hour before administering 5-FU (600 mg/m2). Leucovorin (10 mg orally every 6 hours for six doses) was begun 24 hours after the methotrexate. The response rate was 43%, with 19% of patients having a clinically complete remission. This overall objective response rate is lower than that achieved when this drug combination is given at standard doses of methotrexate and with no interval before 5-FU. Toxicity was primarily related to bone marrow suppression; eight women had wbc counts that fell to less than 1500/mm3.

Adult↗
PubMed1982

The Pima infant feeding study: the role of sociodemographic factors in the trend in breast- and bottle-feeding.

In 1978, a retrospective study of the influence of sociodemographic factors on the trend in breast- and bottle-feeding was conducted among a sample of Pima Indian women 15 to 44 yr old residing on the Gila River Reservation. Based on interviews with 257 Pima Indian women about their infant feeding experiences, the proportion of women who breast-fed dropped significantly between 1949 and 1977. The decline in breast-feeding was evident among women aged 35 to 44 in 1978 across three socioeconomic strata, while women aged 30 to 34 experienced an increase in breast-feeding across two socioeconomic strata. Between 1949 and 1963, women of 50 to 100 and 100% Pima Indian descent breast-fed significantly less than those with other tribal affiliations; however, the influence of tribal descent was reduced thereafter. Bottle-feeding was more prevalent in the high birth orders over time. Among women with first births before 1963, those with small families bottle-fed more than those with large families across birth order. Conversely, among women with first births during or after 1963, those with large families bottle-fed more than those with small families across birth order.

Adolescent↗
PubMed1981

Short-term fluctuations in the concentration of cortisol and progesterone in fetal plasma, maternal plasma, and amniotic and allantoic fluids from sheep during late pregnancy.

Fluctuations in the concentrations of cortisol and progesterone in fetal plasma, maternal plasma, and amniotic and allantoic fluids were measured in samples taken at 10-min intervals over a 90-min period from three groups of sheep sampled at different times during late pregnancy. During the last 30 days of gestation there was a significant rise in the mean concentration of cortisol in fetal plasma and amniotic fluid and a significant correlation between the cortisol concentration in these two fluids. The concentration of cortisol in allantoic fluid exceeded that in amniotic fluid. The concentration of cortisol in fetal plasma varied in a pulsatile manner, however the coefficient of variation (CV) within animals was greater (36%) on days -11 to -20, relative to the day of parturition (day 0), than on days -21 to -30 or days -5 to 0(15-19%). The CV values for cortisol in amniotic fluid and maternal plasma during the last 30 days of pregnancy were 20-50% and two at five times greater than the intraassay CV. The concentration of progesterone in amniotic fluid increased after day -20 but was not correlated with that in maternal plasma or fetal plasma. The concentrations of progesterone in paired samples of amniotic fluid and allantoic fluid were similar. The CV values for progesterone (18-34%) were similar in fetal and maternal plasma and amniotic fluid and did not change significantly during late pregnancy. Changes in the concentration of progesterone were unrelated to changes in cortisol. Interpretation of steroid profiles in fetal plasma and fluids through late pregnancy should take into account these short-term fluctuations in hormone concentrations.

Allantois↗
PubMed1978

Search for heat-labile enterotoxigenic Escherichia coli in humans, livestock, food, and water in a community in the Philippines.

Environmental sources of heat-labile enterotoxigenic Escherichia coli are unknown. The feces of 1,086 inhabitants (approximately 5%) of a small town in the Philippines, 28 pigs, and 10 water buffalo were cultured for enteric bacterial pathogens. Twenty-seven persons harbored pathogenic bacteria: five individuals had enterotoxigenic E. coli, 11 Salmonella species, nine Vibrio parahaemolyticus, one Shigella boydii, and one nonagglutinable Vibrio. Enterotoxigenic E. coli were isolated from two of 28 pigs and from one of 10 water buffalo. Cultures of 26 pieces of beef, 25 pieces of pork, and 52 leafy vegetables obtained from a community market failed to grow enterotoxigenic E. coli. None of 47 samples of contaminated surface water contained this pathogen. Serotypes of human and animal strains of enterotoxigenic E. coli were different, although E. coli O78:H12 isolated from a pig has previously been incriminated in human diarrheal disease. In this limited survey of a Philippine community, enterotoxigenic E. coli were isolated from humans and livestock. The possibility that enterotoxigenic E. coli infections are zoonotic warrants further investigation.

Animals↗
PubMed1976

Temperature-sensitive breakdown in vivo of polysomes with mutants of Chlamydomonas reinhardii.

Two temperature-sensitive mutants of Chlamydomonas reinhardii Dangeard which are defective in protein synthesis were examined. Both show breakdown of their polysomes at the restrictive temperature into monosomes which do not contain fragments of mRNA. Many of the ribosomes still contain nascent peptides able to react with puromycin. The polysome breakdown involves only cytoplasmic (80S) ribosomes and is prevented or reversed when ribosome translocation is inhibited with cyloheximide.

Chlamydomonas↗
PubMed1976

Chloral hydrate causes breakdown of polysomes in Chlamydomonas reinhardi in vivo.

Chloral hydrate produces a biphasic change in the proportion in the cell. Within 1 to 2 min after addition to cells, it inhibits protein synthesis and causes polysomes to break down. The ribosomes dissociate from mRNA by a process which requires protein synthesis but which is apparently abnormal. Released ribosomes do not appear to be bound to fragments of mRNA, but do carry a nascent polypeptide chain. Protein synthesis remains inhibited by more than 85% for over 24 hours, but the apparently normal polyteraction of the cells with chloral hydrate itself and not from its conversion of its usual metabolic products, trichloroethanol or trichloroacetic acid.

Chlamydomonas↗