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Biomedical subjects

R M Dougherty

Publications and source records attributed to R M Dougherty.

At least 37 records · Page 2Linked to original sources
PubMed1984

Studies on the effect of dietary fat on blood pressure.

The role of dietary fat in the origin of human hypertension has aroused interest recently. Results from five intervention studies and from a cross-sectional international study are presented. Three of the intervention studies were carried out in Beltsville, Maryland, USA, and two were carried out in North Karelia, Finland. All the studies involved healthy people and diets typical of the areas concerned. During the experimental periods the diets were modified in such a way that the energy percentage from fats was lowered and the P/S ratio raised. Energy and salt intake were kept constant. The results showed that the blood pressure levels were consistently changed using various dietary fat modifications. The results give strong support to the hypothesis that dietary fat is associated with blood pressure.

Blood Pressure↗
PubMed1983

The role of dietary polyunsaturated fatty acids and prostaglandins in reducing blood pressure and improving thrombogenic indices.

Evidence linking dietary fats to blood pressure and thrombogenic indices is reviewed. Results of dietary studies performed at Beltsville, Maryland, have demonstrated that under controlled dietary conditions, i.e., when total fat intake is maintained at 25% fat calories with a P/S ratio of 1, at either a fixed or free-choice salt intake and where the body weight is maintained relatively constant, blood pressure can be lowered and platelet aggregation indices can be improved in men and women in the 40-60 age group. Results of a pilot epidemiologic study of farmers aged 40-45 in Finland and Italy generally confirm the experimental nutrition studies reported above. A possible explanation of these results based on the conversion of linoleic acid to prostaglandins as well as the physiological actions of prostaglandins is discussed.

Adult↗
PubMed1983

Effect of dietary fat on blood pressure in a rural Finnish population.

Thirty couples living in Liperi, a community of North Karelia, aged 40 to 50 yr participated in a dietary intervention study to assess the influence of dietary fat on blood pressure and other parameters. After a weeklong base-line period the subjects consumed a low fat diet (24% of energy) with a polyunsaturated/saturated fat ratio (P/S) of 1.2 for 6 wk. After this 6-wk intervention period the subjects resumed their normal diets (36% energy from fat, P/S 0.15) for an additional 6-wk period. Body weight remained constant throughout the study and salt intakes were approximately 12 g/day. During the low fat, high P/S period a decrease of 7.5 and 2.8 mm Hg pressure occurred for systolic and diastolic blood pressure from the base-line level. When the normal diet was resumed, systolic and diastolic blood pressures increased by 7.7 and 6.3 mm Hg, respectively, from the levels observed at the end of the intervention period.

Adult↗
PubMed1981

Analysis of avian leukosis virus infections with an enzyme immunoassay.

An enzyme-linked immunosorbent assay (ELISA) for avian leukosis virus group-specific antigen was used to study infections with and shedding of avian leukosis virus in a commercial flock of chickens with a known high incidence of infection. Avian leukosis virus group-specific antigen was detected in serum or cloacal washings from 76% of a group of 100 61-week-old hens. With eggs collected during the next 3 weeks, antigen was detected in the albumen of 88% of the eggs from ELISA-positive hens and 2% of the eggs from ELISA-negative hens. Results of assays for infectivity correlated closely with the ELISA results. Serum and cloacal specimens were almost equally sensitive in detecting infection; however, a higher proportion of cloaca-positive hens (97%) than serum-positive hens (91%) shed virus in their eggs. Similar results were obtained from a second sampling of eggs taken when the hens were 84 weeks old, after an intervening molt. Avian leukosis virus infection was correlated with reduced egg production and increased mortality. Eggs were produced by 100% of the ELISA-negative birds during both sampling periods, whereas only 69% of the ELISA-positive birds produced eggs at 61 weeks and 76% produced eggs at 84 weeks. All birds that were ELISA negative at 61 weeks survived the experiment. Of 14 ELISA-positive birds that died and were examined postmortem between 61 and 84 weeks, 8 had malignancies, and the remainder died of a variety of nonmalignant diseases.

Animals↗
PubMed1981

Age as a factor affecting erythrocyte osmotic fragility in males.

Osmotic fragility and erythrocyte dimensions were measured in 40 normal males between the ages of 18 and 78 years. The principal independent variables correlating with osmotic fragility were mean cell haemoglobin concentration and the age of the donor. The age-related effect was shown to increase both the mean fragility of the cells and the variability of the fragilities of the cells within the individual blood sample. The physical basis for the change is an increase in the degree of isometric sphering of the erythrocytes at isotonicity. The change in shape does not appear sufficient to affect capillary perfusion significantly in normal subjects, but suggests that cell shape will increase the vulnerability of the elderly to abnormalities of the microvasculature.

Adolescent↗
PubMed1981

Immunohistochemical comparison of ocular zonules and the microfibrils of elastic tissue.

Antibody to bovine zonules raised in rabbits gave diffuse staining of zonular fibrils with prominent accumulations at 35 to 45 nm sites of overbanding by means of the indirect immunoperoxidase technique. Antibody binding occurred in both fresh and paraffin-embedded material and was not species specific. The same pattern of heavy antibody binding and 35 to 45 nm periodicity was found on the microfibrils of elastic tissue in human and bovine ciliary body, calf ligamentum nuchae, and chick aorta. This cross reaction is the first direct evidence of a structural similarity or identity between components of the zonules and the microfibrils of elastic tissue, correlating with similarities in their morphology and amino acid profiles. Interstitial collagen fibers appear to have a minimal quantity of antigenically similar material at cross-banding sites. These relationships may hold important clues to the site of systemic involvement in connective tissue diseases associated with lens dislocation. Zonular antibody should prove useful in investigating abnormalities of the zonular-elastic microfibrillar system and cross-banding sites.

Animals↗
PubMed1980

Detection of avian oncovirus group-specific antigens by the enzyme-linked immunosorbent assay.

A three-step sandwich enzyme-linked immunosorbent assay was developed for the detection of avian oncovirus group-specific (gs) antigens. The assay procedure was to coat the wells of microtitre plates with hamster anti-gs IgG, react with crude or purified antigen and finally with hamster anti-gs IgG linked to horseradish peroxidase. The sensitivity was 8 picograms (pg) of input avian myeloblastosis virus (AMV) protein, with negligible background. As the ELISA takes less than 2 h to perform, large-scale screening for infected birds is feasible. A blocking assay was also developed for detecting anti-gs antibodies by adding unlabelled antiserrum after the antigen step.

Animals↗
PubMed1979

Effects of dietary calcium on blood and tissue lipids, tissue phospholipids, calcium and magnesium levels in rabbits fed diets containing beef tallow.

Levels of lipids, calcium and magnesium in blood and tissue were examined in rabbits to determine the effects of 20% beef tallow diets containing three levels of calcium, less than 0.02, 0.8 or 1.6%. In plasma, the calcium-deficient (less than 0.02%) diet contributed to elevated cholesterol and phospholipid, but had no effect on triglyceride levels. Plasma calcium decreased in the calcium-deficient group and plasma magnesium decreased in the high-calcium (1.6%) group of rabbits. Lipid levels of some tissues varied with the level of dietary calcium. Cholesterol, total phospholipid, sphingomyelin and phosphatidylethanolamine were generally elevated in livers of calcium-deficient rabbits, but the individual phospholipids were decreased in skeletal muscle. Lungs of the calcium-deficient group also had lower phospholipid levels than the high-calcium group. Liver, kidneys, brain and adipose tissue triglyceride levels were highest in the high-calcium group. The calcium level of skeletal muscle was lower in the calcium-deficient group than in the high-calcium group. Calcium in brain and adipose tissue were highest in the calcium-deficient group. Except for adipose tissue, magnesium levels of the tissues studied were not affected by dietary calcium.

Animals↗
PubMed1978

Pilot epidemiological studies in thrombosis.

Some differences in the blood of farmers in Nurmijarvi, Finland, Canino, Italy, and Beltsville, Maryland in the United States apparently were associated with differences, among the areas, in the farmers' diets. Those associations suggested that diets that are high in saturated fats (Nurmijarvi) could predispose humans to develop intravascular disease. Such predisposition has been observed in experimental animals. Low levels of the parameters that are considered active in such predisposition apparently were associated with diets that were low in saturated fats (Canino) or with diets that were low in saturated and high in unsaturated fats (Beltsville). Within the limits of the experimental design, the data from the three population groups indicated that a more comprehensive study might establish a relation between diet and intravascular disease in humans.

Adult↗
PubMed1977

Contact transmission of avian leukosis virus.

Intravenous inoculation of four age groups of White Leghorn chicks with ALV-F42, a group A field strain of avian leukosis virus (ALV), indicated that persistent tolerant infection could be induced as late as 2 weeks post hatch, though most birds responded with neutralizing antibody. Contact infection by environmental exposure to ALV was 100% effective in newly hatched and 28-day-old chicks. All contact-infected birds responded immunologically after transient viremia. A follow-up of immune birds from these six groups demonstrated that active multiplication of ALV continued despite neutralizing antibody. Infectious virus was shed by oral and cloacal routes, as well as through vertical transmission by hens to their embryos. Up to 10(8) infectious units of virus/g of feces was shed by 12-day-old viremic birds, and to a lesser extent virus was also shed in saliva as measured by oral washing. The cycle of contact transmission was also evaluated by the assessment of the efficacy of four portals of entry, where exposed skin was most effective in permitting infection, followed by oral, nasal, and conjunctival routes.

Administration, Intranasal↗
PubMed1977

Characterization of human papovavirus RFV: comparison with SV40 and BKV.

Human papovavirus, RFV, isolated from urine of a renal transplant patient was compared with two strains of SV40 and with the prototype human papovavirus, BKV. Neutralization tests showed that RFV and BKV are indistinguishable, while large-plaque (LP) and small-plaque(SP) isolates of SV40 gave a low but significant level of cross-reaction with rabbit or human antisera against RFV. DNA reassociation saturation tests using 125I-labelled RFV DNA show that BKV has 88% homology, and SP-SV40 has 29% homology to RFV. We conclude that RFV and BKV are nearly, if not totally, identical and are not SV40 variants.

Antigens, Viral↗
PubMed1976

Pheasant virus: new class of ribodeoxyvirus.

Cocultivation of cells derived from embryos of golden pheasants or Amherst pheasants with chicken embryo cells infected with Bryan strain of Rous sarcoma virus resulted in the detection of viruses which appear to be endogenous in these pheasant cells. The pheasant viruses (PV) were similar to avian leukosis-sarcoma viruses (ALSV) in their gross morphology, in the size of their RNA, in the presence of a virion-associated RNA-dependent DNA polymerase (DNA nucleotidyltransferase; deoxynucleoside triphosphate: DNA deoxynucleotidyltransferase; EC 2.7.7.7), and in their growth characteristics. PV also serves as a helper for the glycoprotein-defective Rous sarcoma virus. However, PV was shown to be different from both ALSV and reticuloendotheliosis virus in the following properties: (i) PV does not have ALSV group specific antigens; (ii) the protein composition of PV is different from those of the other two groups of viruses; (iii) PV fails to complement the defective polymerase of alpha type Rous sarcoma virus; and (iv) PV RNA shows no detectable homology with nucleic acids of the other two groups of viruses. Thus, PV appears to be a new class of RNA viruses which contain RNA-dependent DNA polymerase.

Alpharetrovirus↗
PubMed1976

Induction of tumors in Syrian hamsters by a human renal papovavirus, RF strain.

Injection of RF virus (RFV), a papovavirus isolated from human urine, into newborn Syrian hamsters induced subcutaneous sarcomas in 50% of the recipients with 18- to 48-week latent periods. Transplantation of 2 X 10(6) primary RFV-induced tumor cells into weaning hamsters caused tumors in 100% of the recipients within 1-2 weeks. Continuous tissue culture cell lines were established from two primary tumors; one of these was transplantable. An in vitro-transformed continuous cell line (RF-194) obtained by infection of primary hamster embryo fibroblasts with RFV was transplantable in weaning hamsters. Neither infectious RFV nor virion antigens were detected in transformed cells. No RFV was recovered when transformed cells were fused with permissive, human embryo kidney cells by means of inactivated Sendai virus. Immunoperoxidase staining was used to show that all three RFV-transformed cell lines contained an intranuclear T-antigen closely similar to that of simian virus 40(SV40)-infected cells. Most hamsters (84%) with primary or transplanted RFV tumors responded with antibodies that reacted with RFV T-antigen and the T-antigen of SV40-infected cells. Likewise, hamster antisera against SV40 T-antigen cross-reacted with RFV T-antigen. Adsorption of RFV T-antisera with an excess of lyophilized SV40-transformed cells removed all detectable activity against SV40 T-antigen but left significant activity against RFV T-antigen. The reciprocal adsorption produced an antiserum spedicic for SV40 T-antigen. Thus human and simian papovavirus T-antigens were related but immunologically separable.

Animals↗