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Biomedical subjects

D H Roberts

Publications and source records attributed to D H Roberts.

At least 73 records · Page 4Linked to original sources
PubMed1986

The reproducibility of limb blood flow measurements in human volunteers at rest and after exercise by using mercury-in-Silastic strain gauge plethysmography under standardized conditions.

A study to assess the reproducibility of limb blood flow measurements by venous occlusion plethysmography using mercury-in-Silastic strain gauges was performed in six normal volunteers under standardized conditions. Using this technique forearm and calf blood flow were measured at rest and between 2 and 3 min after submaximal exercise on six separate occasions over a 1 month period. The mean coefficient of variation for resting forearm blood flow was 10.5% (range 7.8-15.6%). The mean coefficient of variation for resting calf blood flow was 11.5% (range 7.4-14.2%). The mean coefficient of variation for post-exercise calf blood flow was 13% (range 11.5-16.4%). The results suggest that limb blood flow measurement by this technique may be useful in studies where serial measurements are required.

Extremities↗
PubMed1986

Drug-specific antibodies in patients receiving captopril.

IgG anti-captopril (CP) antibody activity was detected by enzyme-linked immunosorbent assay (ELISA) in serum from two out of 45 patients receiving the drug (25-75 mg day-1). Five of the 45 patients, including one whose serum was antibody-positive, suffered skin rashes which were thought to be drug-induced. The specificity of the antibody for the disulphide-conjugated form of captopril was established as follows: serum IgG bound to disulphide-linked captopril-human albumin (CP-S-S-HSA) conjugate but not to HSA; binding of IgG to CP-S-S-HSA was inhibited by disulphide-linked captopril-ovalbumin (CP-S-S-OVA) conjugate and captopril disulphide (CP-S-S-CP). The structurally related drug D-penicillamine (PA) in disulphide-linked form (PA-S-S-OVA and PA-S-S-PA) was without inhibitory activity. The inhibitory preparations of CP-S-S-OVA and CP-S-S-CP were shown to be inactive in an ELISA for human IgG directed against the unrelated benzylpenicilloyl antigen. Since disulphide-linked CP-plasma protein conjugates are formed extensively in vivo, and since the antibodies we describe are directed against CP in disulphide-linked form, it appears that CP may be immunogenic in some patients receiving the drug.

Adult↗
PubMed1986

Spread of bovine syncytial virus in a dairy herd over a two year period.

During a two year period the spread of bovine syncytial virus was monitored in a closed herd of 50 to 100 milking cows. Out of a nucleus of 49 nonpregnant and pregnant heifers, six were found to be infected with bovine syncytial virus. Virus was detected only in the progeny of infected cows and not in the progeny of uninfected animals. Nineteen progeny of the bovine syncytial virus infected cows were studied in detail and virus was isolated from only four. Horizontal spread of the virus did not occur.

Animals↗
PubMed1985

An attempt to protect calves against experimental bovine leukosis using allografts.

Six calves sensitised by implanting skin from a calf were later inoculated with lymphocytes from the same calf after the calf had been infected with bovine leukosis virus (BLV). Two out of 6 calves challenged did not develop BLV antibodies and BLV was not isolated from these animals, whereas all of the 5 control calves became infected with BLV.

Animals↗
PubMed1982

Detection of bovine leukosis virus in bronchoalveolar lung washings and nasal secretions.

Cattle and sheep persistently infected with bovine leukosis virus (BLV) were studied for the presence of the virus in bronchoalveolar lung washings and nasal secretions. The virus was demonstrated in the cellular fraction of the lung washings in six out of nine cattle and in one out of six sheep. In no instance was bovine leukosis isolated from the cell-free bronchoalveolar lung washings. The virus was isolated from the nasal secretion of only one of six naturally infected milking cows despite frequent sampling; the virus-infected nasal secretion was from a sick 10-year-old cow. Bovine leukosis virus was not isolated from cellular fractions of nasal secretions.

Animals↗
PubMed1982

An investigation into the susceptibility of cattle to bovine leukosis virus following inoculation by various routes.

The effect of different routes of inoculation on the incubation period, as indicated by the detection of antibody and by the detection of bovine leukosis virus (BLV) in lymphocytes, were compared. None of the 12-month-old steers exposed to BLV by the oral route developed BLV infection. Intratracheal, subcutaneous and intradermal inoculations were found to be particularly effective in establishing BLV infection, which was detected three to four weeks after inoculation. In the majority of animals, serum antibody and virus were detected at the same time. One out of four in-oestrus heifers inoculated via the uterus with mixtures of BLV infected lymphocytes and semen became infected. It appears that there is an inhibitory factor in fresh semen that prevents BLV infection from becoming established. Viral antigen was detected earlier in BLV infected lymphocytes using the cocultivation method than by electron microscopy to demonstrate BLV particles in mitogen stimulated lymphocytes.

Animals↗
PubMed1982

Protection against bovine leukosis virus infection in sheep with the BL 20 bovine lymphoblastoid cell line.

The bovine lymphoblastoid BL 20 cell line derived from a case of sporadic bovine leukosis when inoculated into sheep did not induce an antibody response directed against bovine leukosis virus (BLV) structural proteins. Sheep were inoculated twice with the BL 20 cell line and then challenged with BLV infected lymphocytes. Three out of four sheep challenged four weeks after BL 20 inoculation did not develop BLV antibodies. Of the 12 sheep challenged later, three sheep did not develop BLV antibodies. BLV was isolated from all the seropositive animals and from none of the seronegative animals.

Animals↗
PubMed1981

Investigation of the possible role of the tuberculin intradermal test in the spread of enzootic bovine leukosis.

The single intradermal comparative test was used with both avian and bovine tuberculin. Three cattle infected with bovine leukosis virus (BLV) were used as a source of infection. BLV-positive and susceptible animals were tuberculin tested alternately. Fifteen susceptible calves and 15 susceptible sheep were tested. A further three valves and three sheep were used as controls; the needles of the tuberculin syringes were deliberately contaminated with blood from the BLV-infected cattle, before being used in the test. Whereas all three calves and the three sheep inoculated intradermally with contaminated needles developed BLV infections, all of the other 30 animals have remained serologically negative to BLV for 10 months. Transmission of BLV with needles contaminated with BLV-infected blood was prevented by wiping the needles with absorbent cotton wool.

Animals↗
PubMed1981

Pharmacokinetics of cephradine given intravenously with and without probenecid.

1 In the light of questions raised by an earlier oral study (Welling, Dean, Selen, Kendall & Wise, 1979) the influence of probenecid on the pharmacokinetics of intravenously administered cephradine has been investigated. 2 Intravenous administration of cephradine resulted in a bi-exponential curve and the level of antibiotic after 15 min was significantly greater when subjects received probenecid than when they did not. The influence of probenecid on urinary excretion of cephradine was similar to that observed previously. 3 The increase in serum of cephradine due to probenecid could be accounted for by the decrease in the elimination rate of the antibiotic. These results are discussed in the light of other observations.

Adult↗
PubMed1979

The demonstration of maedi/visna virus in sheep in Great Britain.

A virus indistinguishable from that causing maedi/visna has been isolated from a sheep flock in Great Britain. The virus was identified in cell cultures using immunofluorescent and electron microscopical techniques. The complement fixation test and the agar gel immunodiffusion test were used to assess the proportion of serological reactors within the flock. There has been no evidence of clinical disease in the flock into which foreign imports were introduced in the years prior to 1976.

Animals↗