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Biomedical subjects

D Howard

Publications and source records attributed to D Howard.

At least 145 records · Page 8Linked to original sources
PubMed1983

Mechanisms of abnormal erythropoiesis in malignancy.

In order the investigate mechanisms of diminished red cell production in malignancy, we assayed erythroid progenitor cell proliferative responses to erythropoietin in plasma clot cultures of bone marrow cells from 34 cancer patients. Erythroid colony growth by marrow cells of 11 healthy donors (means of 58 CFU-E and 19 BFU-E derived colonies/6 X 10(4) cells) was similar to that in cultures of cells from patients either with (means of 44 CFU-E and 22 BFU-E derived colonies/6 X 10(4) cells) or without (means of 50 CFU-E and 19 BFU-E derived colonies/6 X 10(4) cells) myelophthisis. Colony formation was normal at all erythropoietin concentrations tested, indicating that both the CFU-E and BFU-E retain normal erythropoietin sensitivity in vitro. CFU-E proliferation correlated negatively (r = -0.56; P less than 0.001) with the level of hemoglobin. In contrast to marrow cell proliferative responses to erythropoietin, serum erythropoietin levels were inappropriately reduced in all 19 patients in whom they were measured, a finding which may be important in the pathogenesis of anemia in patients with cancer.

Carcinoma, Squamous Cell↗
PubMed1983

Multiple laryngeal papillomatosis requiring laryngectomy.

Laryngectomy has been performed on two of the 63 cases of laryngeal papillomatosis treated at the Royal National Throat, Nose, and Ear Hospital, London, over 24 years. Their case histories are reported to illustrate the difficulties in managing extremely diffuse and recurrent forms of the disease. Whole organ laryngeal sections of one case are presented. Both patients experienced an improved life-style and fewer hospitalizations following laryngectomy. Although improved microsurgical methods are now available, the search continues for a treatment that will significantly alter the course of the disease.

Adolescent↗
PubMed1983

Plasma levels of catecholamines and dihydroxyphenylglycol during antidepressant drug treatment.

Plasma norepinephrine, epinephrine, and 3,4-dihydroxyphenylglycol levels were measured in depressed outpatients treated in a double-blind controlled clinical trial with 150 mg/day of amitriptyline or 60 mg/day of phenelzine for 6 weeks. Both antidepressant drug treatments were associated with a significant decline in plasma dihydroxyphenylglycol concentrations, which was more pronounced with phenelzine. Plasma norepinephrine levels also declined during phenelzine but not amitriptyline treatment, and the posttreatment values correlated with clinical improvement with the monoamine oxidase inhibiting drug. Reductions in norepinephrine and dihydroxyphenylglycol correlated highly with the degree of platelet monoamine oxidase inhibition. Mechanisms of these antidepressant drug effects on amine metabolism and their implications are discussed.

Adult↗
PubMed1982

Correlation of clinical and in vitro erythropoietic responses to androgens in renal failure.

To assess in vitro erythropoietic cultures as a tool to discriminate between patients whose anemia improves with and those whose anemia fails to improve with androgens, bone marrows of 24 anemic patients receiving maintenance hemodialysis in hormone-depleted plasma clots were cultured. While erythroid colony proliferation in the presence and absence of androgens by cells of seven patients with good clinical outcomes who were initially studied was similar to that of normal donors, it was reduced (P less than 0.001) in cultures of cells from seven patients whose clinical responses were ultimately poor. Fewer than 25 colonies/6 X 10(4) cells at optimal erythropoietin concentrations, and less than a 25% enhancement in colony growth by androgens were observed in only those cultures derived from clinical nonresponder marrows. Using these criteria, nine of ten prospectively classified patients (five clinical responders and four nonresponders) were identified correctly.

Adult↗
PubMed1982

Parental knowledge of child development and injury risks.

The hypothesis that the risk of injury to children is related to (1) parents' assessment of the child's developmental abilities, and (2) parents' knowledge of injury prevention measures was tested by a two-part self-administered questionnaire, completed by 118 parents. The developmental score correlated with the score on the safety questionnaires and with educational level of the respondent. There was a small but nonsignificant correlation of both scores with injury in the preceding month. Knowledge of safety practices was low for many items. Results indicate the need to improve parental knowledge of injury prevention and to educate parents about normal childhood development.

Accident Prevention↗
PubMed1979

Effect of winter sleep on pituitary-thyroid axis in American black bear.

During winter sleep the black bear has decreased levels of serum total and free thyroxine (T4) and triiodothyronine (T3) and a prolonged, delayed response of serum thyrotropin (TSH) (bioassay) to thyrotropin-releasing hormone (TRH). Four weeks after the end of winter sleep, levels of serum thyroid hormones increase, and TSH response to TRH is short and brisk. Serum T4 and T3 rise after TRH administration both during and after winter sleep; however, the maximum increment in serum T3 is greater during winter sleep when the TSH rise is also prolonged and exaggerated. These observations suggest that transient hypothyroidism of possible hypothalamic origin occurs in bears during winter sleep.

Animals↗
PubMed1979

Metastatic tumors of the penis.

The penis is a rare site of metastatic neoplasm in spite of its rich blood supply, abundant vascular space, proximity of the pelvic organs and interconnections with the pelvic and vertebral veins as well as lymphatics. The location of primary tumor has varied widely. The urinary bladder, prostate, rectum and rectosigmoid were common primary sites. In our series the bladder was the primary site in 3 patients, prostate in 2, and lung in 1. In 1 patient the metastatic lesion was secondary to lymphoma and in another to leukemia. The mode of metastasis, symptoms, treatment and prognosis are discussed.

Aged↗
PubMed1979

Modulation of erythropoietin concentrations by manipulation of hypercarbia.

The present studies were done to determine whether preventing the respiratory alkalosis, which is known to occur with acute "hypoxic" stimuli, would lead to alterations in plasma concentrations of erythropoietin (Ep). Rats were subjected to two acute stresses, hypoxia and blood loss, separately and in combination, with and without the added stress of hypercarbia. Hypercarbia in all experimental groups was associated with a decrease in plasma concentrations of Ep. This reduction in plasma Ep with hypercarbia could not be fully explained by the higher arterial pO2S or p50S of the hypercarbic rats. Hypercarbia may have indirectly suppressed Ep production by increasing blood flow to the site of Ep production. Alternatively, the cell of origin of Ep could be sensitive to changes in pH and/or PCO2. It was further demonstrated that neither the onset nor the degree of reticulocytosis could be predicted by the plasma Ep concentrations. It is likely that the removal of red blood cells led to a decrease in marrow transit time with the early emergence of reticulocytes after acute blood loss.

Anemia↗
PubMed1978

Strain-specific markers for the major structural proteins of highly oncogenic murine mammary tumor viruses by tryptic peptide analyses.

Tryptic peptide analyses were performed on the major structural 52,000- and 36,000-dalton glycoproteins (gp52 and gp36-38) and the nonglycosylated 28,000-, 14,000-, and 10,000-dalton proteins (p28, p14, and p10) of the highly oncogenic murine mammary tumor viruses (MMTVs) of C3H, RIII, and GR mice, i.e., MMTV(C3H), MMTV(RIII), and MMTV(GR), respectively. Each virus was grown in both murine and feline cells to ensure the virus-coded nature of each peptide analyzed. The gp36-38 peptide maps of all three MMTVs were indistinguishable, as were the p14 maps of the different MMTVs. Both the p28 and the gp52 of MMTV(C3H), however, could be clearly distinguished from the corresponding proteins of MMTV(RIII) and MMTV(GR), regardless of whether the viruses were grown in feline or murine cells. The p1o of MMTV(RIII) was clearly different from that of MMTV(C3H) and MMTV(GR). Therefore, tryptic peptide analysis of three proteins, gp52, p28, and p10, can serve to distinguish these three viruses from one another. These studies further characterize the heterogeneity in polypeptides among MMTVs.

Animals↗
PubMed1978

Megakaryocytic responses to thrombocytopenia and thrombocytosis in Sl/Sld mice.

Sl/Sld mice maintain normal platelet counts in spite of a reduced number of megakaryocytes, but their megakaryocytes are macrocytic. The present studied were done to analyze platelet turnover in the steady state and thrombocytopoietic responses to perturbations of the platelet count. Platelet production, estimated with 35S incorporation in the steady state, blood volume, and total complement of peripheral platelets were normal. Sl/Sld mice responded to thrombocytopenia with normal degrees of macromegakaryocytosis and production of macrocytic platelets, but rebound thrombocytosis did not occur. Their megakaryocytes were unusually responsive to transfusion-induced thrombocytosis, showing a prompt and substantial reduction in size. Platelet turnover was normal in undisturbed Sl/Sld mice, and feedback regulation occurred. However, increased numbers of platelets were not produced in response to stimulation. The findings are consistent with the possibility that their megakaryocytes are large because of stimulation rather than a direct local effect of the abnormal microenvironment.

Animals↗