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Biomedical subjects

J C Davis

Publications and source records attributed to J C Davis.

At least 19 recordsLinked to original sources
PubMed1992

Adjuvant hyperbaric oxygen in malignant external otitis.

Necrotizing invasive pseudomonal infection of the external auditory canal (malignant external otitis) is an uncommon but important disorder in the elderly. The high morbidity, and even mortality, of this disorder has been reduced by the early and intensive use of combination antipseudomonal antibiotics. However, in severely immunocompromised patients or in infection involving the base of the skull, multiple cranial nerves, or the meninges, conventional therapy has been prolonged, intensive, and relatively ineffective. We treated 16 patients with malignant external otitis with adjuvant hyperbaric oxygen therapy. In six patients, infection was in advanced stages, infections were recurrences after previous treatment, and repeated treatment with antipseudomonal antibiotics had failed. All 16 cases responded promptly when a 30-day course of hyperbaric oxygen was added to the antibiotic regimen, and all patients remained free of infection or neurologic deficit during 1 to 4 years of follow-up. No complications of this treatment modality were noted. Hyperbaric oxygen therapy reverses tissue hypoxia, which enhances phagocytic killing of aerobic microorganisms, and stimulates neomicroangiogenesis. In addition, hyperbaric oxygen augments the action of aminoglycoside antibiotics. Adjuvant hyperbaric oxygen therapy should be considered in advanced or recurrent cases of malignant external otitis.

Aged↗
PubMed1992

Psychobiologic responses to exercise at different times of day.

The primary purpose of this investigation was to determine whether selected psychobiologic responses to running exercise vary as a function of the time of day at which exercise is performed. Twelve adult males completed four bouts of randomly assigned, submaximal exercise (20-min runs at 70% VO2max) at 0800, 1200, 1600 and 2000 h. Since selected personality traits have previously been shown to influence circadian rhythms, personality assessments (i.e., Eysenck Personality Questionnaire, EPQ; Morningness-Eveningness Questionnaire, MEQ; Spielberger's State-Trait Anger Expression Inventory, STAIX; and State-Trait Anxiety Inventory, STAI) were made during the initial testing session. The group studied scored within the normal range on the traits assessed by the EPQ, STAIX, and STAI. Also, subjects were not able to be classified as either "morning" or "evening" types based on MEQ scores. Ten minutes before as well as 10 and 20 min following the exercise bouts, state anxiety, state anger, blood pressure, and heart rate were assessed. Multivariate ANOVAs (four time of day conditions x three trials) revealed significant main effects for the trial factor for state anxiety, state anger, heart rate, and systolic blood pressure. State anxiety, state anger, and systolic blood pressure were found to be reduced at both the 10 and 20 min post-exercise assessment periods when compared with pre-exercise levels. ANOVAs performed on the difference scores showed that the mood improvements and cardiovascular changes were independent of the time of day that exercise was performed, and these findings were confirmed by ANCOVAs, which adjusted for differences in initial values across the four time of day conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Vertical transmission of human immunodeficiency virus from seronegative or indeterminate mothers.

UNLABELLED: OBJECTIVE--To describe the identification of human immunodeficiency virus (HIV)-infected infants born to women who were seronegative or indeterminate during pregnancy. RESEARCH DESIGN--Longitudinal cohort study. SETTING--Inner-city medical center. PARTICIPANTS: A series of children born to women with histories of risk factors for HIV infection were followed up for studies of the natural history of HIV-infected infants. These children were identified through risk factor assessment of pregnant women presenting for obstetric care. INTERVENTIONS--Counseling and testing to detect HIV. RESULTS--Three women were retrospectively identified who were infected with HIV during pregnancy but whose test results showed them to be either seronegative or indeterminate. Two of these women transmitted HIV infection to their children. Subsequently, all three women were confirmed to be infected. CONCLUSIONS--Standard serologic testing to detect HIV infection will not identify all infected pregnant women. Perinatal transmission of HIV can occur in women with negative results of enzyme-linked immunosorbent assay or indeterminate results of Western blot analysis during pregnancy.

AIDS Serodiagnosis↗
PubMed1979

Hyperbaric oxygen. A new adjunct in the management of radiation necrosis.

Radiation necrosis is a significant complication of surgery for previously irradiated head and neck malignant neoplasms. We used hyperbaric oxygen therapy (HBO) as adjunctive therapy in 52 cases of radiation necrosis. Thirty-nine cases involved the head and neck. Nineteen of 23 cases of osteoradionecrosis of the mandible remain arrested after as much as two years of follow-up. Fifteen of the 16 cases of soft-tissue radionecrosis of the head and neck were successfully managed with HBO therapy as an adjunct to surgery and antibiotics. Fibroblastic proliferation, collagen formation, and capillary budding require at least 20 to 30 mm Hg of wound Po2. This effect can be achieved in wounds that are rendered hypoxic by radiation endarteritis and ischemia with high-dose or hyperbaric oxygenation.

Adult↗
PubMed1979

Testicular endocrine function in paraplegic men.

The responses of FSH and LH to the injection of LHRH were studied in fifteen paraplegic men and ten normal controls. The basal FSH levels in the paraplegic men were elevated in eight cases, basal LH being raised in nine cases. The responses of FSH were exaggerated in fourteen patients, and LH responses were exaggerated in nine patients. Only one patient was normal in respect of both hormones. Subnormal plasma testosterone was found in three patients. This depressed testicular function could not be explained as being due to spread of urinary tract infection and a direct neurological effect is the probable explanation.

Adolescent↗
PubMed1979

Follicle-stimulating hormone-induced, adenosine 3',5'-monophosphate-mediated movement of immature rat sertoli cells in primary culture.

Sertoli cells dissociated from 10-day-old rat testes form colonies in primary culture in response to FSH. FSH and dibutyryl cAMP stimulated the attachment of Sertoli cells to an equal extent; however, FSH-treated cultures contained a small number of large colonies while dibutyryl cAMP-treated cultures contained a large number of small colonies. This relationship was not altered by the addition of a number of other peptide or steroid hormones. Extracellular cAMP levels and colony density were negatively correlated. Colony size at 24 h of culture was diminished in FSH-treated cultures by the addition of a cAMP antibody at 6 or 12 h of incubation. The addition of cAMP at 24 h to FSH-treated cultures caused a dose-dependent stimulation of colony size but not colony density at 48 h of culture. A point source of cAMP (4 x 10(-3) M in agar) inhibited migration of cells toward the agar spot. An agar spot on the dish substratum containing Sepharose-bound FSH exhibited a halo of cells next to the spot, with a zone lacking cells distal to it. Radioautographs of [125I]iodo-FSH-treated cultures exhibited a nonhomogeneous distribution of silver grains; colony size increased faster than the number of labeled cells. Taken together, the results suggest that 1) FSH is stimulating the attachment of Sertoli cells through an increase in intracellular cAMP, 2) FSH is promoting active aggregation of Sertoli cells in culture through a modulation of extracellular cAMP, and 3) cells with a large amount of bound FSH are acting as centers for aggregation.

Animals↗
PubMed1978

Failure to suppress adrenal function in congenital adrenal hyperplasia (21-hydroxylase deficiency). Three case reports.

Three patients, aged 14, 16, and 32 years respectively, with congenital adrenal hyperplasia (21-hydroxylase deficiency) are described. Excessive adrenal activity and ACTH secretion could not be suppressed with doses of corticosteroids sufficient to cause iatrogenic Cushing's syndrome, even though part of the steroid dosage was administered in the late evening. The resistance to feed-back suppression was of the same order as that seen in Cushing's syndrome. Adrenalectomy was performed in the 16-year-old girl, and was followed by a menarche. Adrenalectomy was considered inadvisable in the other two patients.

Adolescent↗
PubMed1978

Morphogenesis by dissociated immature rat testicular cells in primary culture.

Dissociated cells from immature (15-day) rat testes maintained in primary culture were shown to undergo morphogenesis. Dissociated cells (1-4 X 10(6)) were cultured in 2 ml medium NCTC-135 containing 10% rat serum at 32.5 degrees C under an air; CO2 atmosphere (95%:5%). During the initial culture period (1-3 days) the dissociated cells attached to the culture dish and formed a monolayer. After 4-5 days of culture, aggregates of cells formed at discrete foci within the monolayer; these structures averaged 50 micrometer in diameter and numbered 3-4 X 10(3)/dish. Within 5-6 days of culture some of these aggregates (2-3 X 10(2)) released their contact with the substratum. Histological examination of released aggregates indicated a more regular, tissue-like organization with increasing time in culture. Aggregates at earlier time periods (4-5 days) exhibited concentric rings of cell while by day 6 some aggregates exhibited a vesicular appearance with a single layer of columnar epithelium surrounding a fluid-filled lumen. The type of structure formed varied with plating density; at densities less than 2 X 10(6)/dish the structures were spheroid while at greater densities tubes were formed. Time-lapse observations indicated that spheres formed by movements of cells into an aggregating center while tubes formed by a rolling from the edge of the monolayer. The cells comprising the vesicle epithelium appeared to be predominantly one cell type as determined by light microscopy. These results therefore indicate that dissociated testicular cells have the ability to reform tissue-like associations in culture.

Animals↗
PubMed1977

Feto-maternal bidirectional mixed lymphocyte reaction and survival of fetal allograft.

Maternal and fetal lymphocytes were tolerant of each other in the bidirectional mixed lymphocyte reaction. This seems to be the principal reason why the mother does not reject the fetal allograft. Tolerance between maternal and fetal cells must be largely due to a genetic mechanism, because the bidirectional mixed lymphocyte reaction between parents and older children was much reduced compared with that between randomly selected pairs of controls. This weak reaction disappeared when immunosuppressive agents were given to one member of the parent/child pair, whereas the mixed lymphocyte reaction between unrelated individuals was not abolished by similar immunosuppression. It is suggested that this genetic mechanism is distinct from the HLA system. Tolerance between maternal and fetal cells was not demonstrated in the unidirectional mixed lymphocyte reaction, suggesting that this tolerance requires the viability of the two cell populations.

Female↗
PubMed1977

Altitude decompression sickness: hyperbaric therapy results in 145 cases.

Most cases of decompression sickness that occur at altitude resolve upon descent to lower altitudes. Before the use of hyperbaric therapy, cases that did not resolve accounted for some of the most difficult medical management problems in military aerospace medicine. On 27 March, 1941, the U.S. Navy Diving School successfully used hyperbaric therapy for a case of altitude-induced decompression sickness that did not resolve on return to ground level. Since then, over 145 such cases have been treated by hyperbaric therapy. At first, treatments involved using compressed air, with varying success. Current medical management of altitude-induced decompression sickness requires immediate compression to 2.8 ATA, equivalent to 60 ft of sea water (FSW) pressure, and a series of intermittent oxygen and air breathing periods during the subsequent slow decompression to surface. This report confirms the treatment recommendations set forth by Behnke and Downey, and crystallized by Goodman in 1964. Conclusions are based on treatment experience in the management of 120 cases in U.S. Air Force hyperbaric chambers, and a survey of hyperbaric facilities which have treated 25 other cases.

Adult↗