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Biomedical subjects

J McDowell

Publications and source records attributed to J McDowell.

At least 55 records · Page 3Linked to original sources
PubMed1986

Chlamydia trachomatis infection in women with ectopic pregnancy.

Fifty women with ectopic pregnancy and 49 control women with intrauterine pregnancy were interviewed and evaluated for evidence of Chlamydia trachomatis infection. Among women with ectopic pregnancy, 14 women were wearing an intrauterine contraceptive device or had a tubal ligation (group A), and 36 women had no readily identifiable risk factors (group B). Group B women had greater total numbers of sexual partners than did control women with intrauterine pregnancy (P less than .005). Group B women more often had C trachomatis antibody than group A (P = .03) and control women (P = .002). Of 27 C trachomatis cultures from fallopian tube tissue from women with ectopic pregnancy, none were positive. Fallopian tube tissue distant from the site of ectopic implantation was available for histopathology of 41 cases. Nine (22%) had extensive subepithelial plasma cell infiltration. All nine were among group B women (P = .06) and all seven with plasma cell salpingitis who were tested for C trachomatis antibody were seropositive (P = .004). It is concluded that a subset of women with ectopic pregnancy were at increased risk for acquiring a sexually transmitted disease by virtue of their sexual behavior and that women in this subset frequently have serologic evidence of C trachomatis infection and histologic evidence of plasma cell salpingitis. Because few of these women recall having had pelvic infection, the authors speculate that subclinical C trachomatis tubal infection producing plasma cell salpingitis may commonly underly ectopic pregnancy.

Adolescent↗
PubMed1986

Development of delta-opioid receptors in rat brain characterised by [3H]-[D-Pen2,D-Pen5] enkephalin binding.

The development of rat brain delta-opioid receptors has been studied in the postnatal period using the highly selective delta-site ligand [3H]-[D-Pen2, D-Pen5] enkephalin (DPDPE) in binding studies. Between day 10 and day 25 there was a three-fold increase in the number of binding sites (expressed per mg protein) and the KD was constant throughout the postnatal period. Specific binding could not be detected earlier than day 10.

Aging↗
PubMed1986

Recycling class I MHC antigens: dynamics of internalization, acidification, and ligand-degradation in murine T lymphoblasts.

We have previously shown that activated T lymphocytes spontaneously internalize their own surface class I MHC antigens and that this phenomenon is specific for these cells since it does not occur in B lymphocytes even after activation. The present work was aimed at defining the quantitative aspects of this phenomenon and, in particular, at the elucidation of the route of the internalized class I MHC antigens. We intended to determine if the internalized molecules are delivered to the lysosomal compartment and digested there or if instead they are brought back to the plasma membrane in a recycling pathway similar to that described for various cell surface proteins known to be engaged in the process of receptor-mediated endocytosis. We have devised a flow cytometric assay based on the use of fluorochrome-labeled monoclonal anti-H-2K antibodies to measure the kinetics of H-2K internalization. Comparison of the time necessary for the internalization of one-half of the surface H-2K molecules in activated T lymphocytes, which is approximately 1 hour, with the half-life of these molecules on the same cells, which is 14 hours, clearly indicates that the internalized molecules are not degraded but are instead recycled. The recycling takes place in an endosomal compartment with an average pH of about 5.6. The monoclonal anti-H-2K antibody used in these studies was not eluted from the H-2K molecules at this pH and is recycled along with them. On the other hand, protein A bound to the Fc of the anti-H-2K antibody was eluted at the low pH of the endosomes, delivered to lysosomes, and digested. We have therefore defined a novel phenomenon, namely the recycling of class I MHC antigens, which occurs selectively in T lymphocytes. The features of this phenomenon are similar to the recycling of surface receptors which mediate the endocytosis of a variety of extracellular ligands in different cells. However, no physiological extracellular ligand is known for class I MHC antigens. It is a reasonable speculation that upon activation T lymphocytes recycle their own surface class I MHC antigens as part of the complex machinery whereby these lymphocytes recognize and respond to non-self moieties on the plasma membranes of presentor or target cells.

Animals↗
PubMed1985

Use of fluorescence-activated cell sorter to isolate mutant mammalian cells deficient in an internal protein, dihydrofolate reductase.

Dihydrofolate reductase-deficient mutants of Chinese hamster ovary cells have been selected based on their inability to bind a fluorescent derivative of methotrexate, a substrate analog. Nonfluorescent mutant cells were isolated from mutagenized populations using a fluorescence-activated cell sorter. After multiple rounds of sorting plus regrowth, the mutant cell frequency was increased from an initial 10(-5) to greater than 0.9. This use of the cell sorter to isolate mutants deficient in an internal protein should be applicable to any gene product that is able to bind a fluorescent ligand tightly. The method has the advantage of allowing the screening of large numbers of cells and of selecting for partially expressed phenotypes.

Animals↗
PubMed1985

Impairment of ketocyclazocine antinociception in rats by perinatal lead exposure.

The development of ketocyclazocine antinociception has been measured in lead-exposed rats as an indirect determinant of kappa-opioid receptor system development. Perinatal lead administration (at 300 and 1000 ppm) in the maternal drinking water from conception to weaning, impaired the antinociceptive activity of ketocyclazocine (using the paw pressure test) in 10-day-old rats. Lead caused a dose-dependent impairment of ketocyclazocine antinociception, the paw pressure threshold for 0.4 mg/kg being reduced from 207 g to 135 g in the 1000 ppm lead dose-group. Ketocyclazocine antinociception was impaired in the high-lead dose-group at 21 days, but unaffected at 30 days. Blood lead levels in 10-day-old animals were below 35 micrograms/100 ml in the low-lead dose-group and below 50 micrograms/100 ml in the high-lead dose-group. It is suggested that lead may disrupt the development of kappa-opioid receptor systems in the central nervous system and that this disruption occurs early in development.

Animals↗
PubMed1984

In vitro fertilization in Norfolk, Virginia, 1980-1983.

Three years of progress of the Vital Initiation of Pregnancy (VIP) Program in Norfolk is reported. No conception resulted from 41 oocyte aspirations during spontaneous menstrual cycles in 1980. An average of 3.7 oocytes per cycle, or a 73.5% recovery rate, resulted in 362 human menopausal gonadotropin/human chorionic gonadotropin-induced cycles from January 1981 to March 1983. Forty percent of the oocytes recovered from these cycles were preovulatory, 35% atretic, and 25% immature. Immature oocytes were often matured in vitro, fertilized, and found to produce pregnancies. A total of 62 pregnancies occurred, which represents a 17 or 23% pregnancy rate, based on laparoscopies or embryo transfers, respectively. There were 11 preclinical and 7 clinical miscarriages. Twenty-nine normal babies have been delivered, including a set of twins. The remainder appears to be normally progressing pregnancies. Polyspermia was observed in 8.8% of the fertilizable oocytes.

Adult↗
PubMed1984

Low-level lead exposure alters morphine antinociception in neonatal rats.

Administration of lead (at 300 and 1000 ppm) in the maternal drinking water from conception to weaning impaired the antinociceptive activity of morphine in 10-day-old neonatal rats. Blood lead levels in these animals were below 50 microgram/100 ml in the high lead dose group and below 35 microgram/100 ml in the low lead dose group. The differences in the antinociceptive potency of morphine between normal and lead-exposed animals were not observed at later time points (21 and 30 days). It is suggested that lead disrupts the development of opioid receptor systems in the central nervous system and that this disruption occurs early in development.

Analgesia↗
PubMed1984

Hamster ova/human sperm penetration: correlation with count, motility, and morphology for in vitro fertilization.

In an analysis of 38 proven-fertile donor samples and 84 patient samples of either unproven fertility or suspected infertility, the number of hamster ova penetrated by human sperm (% HOP) was significantly different (p less than 0.05) between the donor and suspected-infertile groups. Lowest percent HOP rates; which were recorded for patients with oligozoospermia (less than 20 X 10(6) sperm per milliliter), were significantly different from donor rates (p less than 0.01). Sperm samples from 15 patients of unknown fertility were incubated with human eggs and were simultaneously incubated in the hamster ova-sperm penetration assay. All 13 patients fertilizing at least one human ovum also penetrated hamster ova at greater than 10%. The two samples failing to fertilize any human ova had one HOP above 10% and one below 10%. Interassay ranges were low over short periods of time (weeks), but the range was high (41%) for one individual when the SPA was performed months later. Fluctuations in % HOP over extended periods of time may be due to changes in male fertility status and not to unreliability of the assay.

Animals↗
PubMed1983

The importance of the follicular phase to success and failure in in vitro fertilization.

One hundred seventy-five cycles in patients with irreparable tubal disease were stimulated by human menopausal gonadotropin/human chorionic gonadotropin for the purpose of in vitro fertilization. As judged by the height of the peripheral estradiol response, the patients were classified as high, intermediate, or low responders. In addition, the estradiol pattern of the response was found to be separable into six categories. The pregnancy rate was found to be related to the height and to the pattern of peripheral response. The overall pregnancy rate in this consecutive series was 19% but varied according to the height and pattern of response from 40% to 0%.

Estradiol↗
PubMed1983

What is a pregnancy? A question for programs of in vitro fertilization.

Pregnancy outcome in studies of normal reproduction and in programs of in vitro fertilization (IVF) is usually classified as "chemical beta-human chorionic gonadotropin (beta-hCG) abortion," "trimester abortion," and "term delivery." The distinction between a chemical beta-hCG abortion and a first-trimester abortion is not clearly stated in the literature, although such terms are commonly used. It is proposed that in programs of IVF pregnancy outcome be classified as "menstrual abortion," "preclinical abortion," "clinical abortion," or "viable pregnancy." Pregnancy outcome of 190 consecutive cycles induced by human menopausal gonadotropin/human chorionic gonadotropin in the program of IVF at Norfolk is compared with contemporary studies of pregnancy outcome in normal reproduction. The in vitro data indicate that the Norfolk program has recorded no menstrual abortions, a 33% preclinical and clinical abortion rate, and a viable pregnancy rate that approaches but does not equal the term delivery rate of normal reproduction. However, these results have been achieved by the transfer of multiple concepti, whereas normal reproduction depends on the fertilization of a single oocyte.

Abortion, Spontaneous↗
PubMed1979

Markers of human T cell subsets identified by alloantisera.

Analysis by the indirect fluorescence test followed by fluorescence-activated cell sorter (FACS) analysis has shown that antisera recognizing subsets of human T lymphocytes can be produced by planned immunizations involving HLA-A and HLA-B compatible donors. The reactivity of these antisera against some individuals of a population but not others shows that they recognize a polymorphic cell surface component. The reactive subpopulation largely overlaps with the JRA+ subset, which was previously shown to possess regulatory properties in functional assays. The specificity of the antisera for a T cell subset and the unrelatedness of the anti-B cell activity of the same antisera has been confirmed by two-color fluorescence tests.

Antibody Specificity↗
PubMed1978

Chromatographic separation and automated analysis of flavanols.

Flavanols from barley or hops were separated chromatographically and assayed automatically by reaction with the chromogen, 4-dimethylaminocinnamaldehyde. For separating the flavanols on Sephadex G-25, gradient elution with water-methanol mixtures was necessary. The chromogen was specific for flavanols and well suited to AutoAnalyzer methods. The method appears generally applicable in flavanol analysis of plant materials.

Chromatography, Gel↗
PubMed1978

Direct evidence for loss of human suppressor cells during active autoimmune disease.

These studies indicate that a regulatory subset of lymphocytes is missing in patients with juvenile rheumatoid arthritis but these patients have antibodies in their serum that react with normal T cells. This regulatory subset of T cells is, however, present in patients whose serum shows little or no reactivity with normal T cells. In addition, patients who are deficient in this regulatory subset of lymphocytes significantly higher numbers of cells secreting Ig as measured by a hemolytic plaque assay. The significance of these observations is twofold: first, they represent a positive relationship among the loss of regulation overproduction of immunoglobulin, and the presence of anti-T cell antibodies and second and perhaps of equal importance, is the indication that serum from patients with autoimmune diseases may give us a readily available reagent with which to dissect further functionally distinct subsets of normal T cells in man.

Adolescent↗
PubMed1977

A longitudinal chart audit of hypertension in a family practice center.

This is a paper in which a practice looks critically at itself through a longitudinal chart audit of 40 patients with hypertension of at least one year's duration. Diagnosis was properly made in all of the patients. The evaluation by physical examination and laboratory studies seemed appropriate and adequate. Therapy was effective. Optimal patient education toward eliminating risk factors was precluded by poor recording of the family history and past medical history of the patient. To overcome these deficiencies a new history data base sheet was designed and a chronic disease flow sheet was developed. This flow sheet is adaptable to any office practice setting and not only affords better patient care, but sets the stage for future prospective studies.

Adult↗
PubMed1969

Antibiotics.

Explore the source record for details and available documents.

Penicillins↗
PubMedDate not supplied

Pediatric infection with the human immunodeficiency virus (HIV): head, neck, and oral manifestations.

The increasing incidence of HIV infection in the pediatric population is of concern for the practicing dentist. Long incubation periods of the virus, combined with difficulty in detection, results in many undiagnosed cases of prenatal and natal infections with HIV. As a result, many dentists will unknowingly treat HIV-positive children. This article presents most common features of pediatric HIV infection, placing special emphasis on manifestations which affect the head, neck, and oral tissues.

AIDS Dementia Complex↗