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Biomedical subjects

D Todd

Publications and source records attributed to D Todd.

At least 199 records · Page 11Linked to original sources
PubMed1981

Isolation from chickens of a rotavirus lacking the rotavirus group antigen.

A virus, designated 132 virus, was isolated from the faeces of chickens in chick embryo liver cell cultures. The morphology and morphogenesis of 132 virus were indistinguishable from that of rotaviruses. The nucleic acid of 132 virus had the nuclease resistance of double-stranded RNA, and was separated by polyacrylamide gel electrophoresis into 11 segments with mol. wt. ranging from 2.07 x 10(6) to 0.20 x 10(6). SPF chickens were susceptible to oral infection with 132 virus, which replicated in the villous epithelial cells of the small intestine. 132 virus was therefore a rotavirus by morphological, biochemical and biological criteria. However, by immunofluorescence it was not possible to demonstrate an antigenic relationship between 132 virus and known avian and mammalian rotaviruses, indicating that 132 virus does not possess the group antigen shared by all previously characterized rotaviruses. This finding has implications for the diagnosis of rotavirus infections by serological tests.

Animals↗
PubMed1981

Rural out-migration in southern Manitoba: a simple path analysis of "push" factors.

"Rural out-migration from southern Manitoba over the period 1971-76 is subjected to a path-analytic model which claims that the exodus is due to unsatisfactory economic and social conditions. In particular, the model is structured so that migration and community satisfaction both depend upon the economic standing of a community. Results indicate that while economic conditions are key factors in rural out-migration, other variables, especially those representative of rural isolation, are also of great importance. These conclusions remain tenable even after allowing for feedback effects from the rural out-migration." (summary in FRE)

Americas↗
PubMed1980

An enzyme-linked immunosorbent assay for enzootic bovine leukosis virus antibodies.

An enzyme-linked immunosorbent assay (ELISA) for detecting antibodies to enzootic bovine leukosis (EBL) virus is described and its sensitivity compared with that of the agar gel immunodiffusion test (AGIDT) using 198 sera collected in Great Britain. There was 95 per cent agreement between the ELISA and AGIDT, when sera with positive/negative ratio (P/N) values of 1 . 5 or greater were considered positive. A total of 259 out of 264 sera (98 per cent) collected in Northern Ireland had P/N values of less than 1 . 5, the remaining sera having P/N values of 1 . 5 and 1 . 6. As Northern Ireland is clinically and serologically free of EBL infection it is proposed that sera with P/N values of 1 . 5 and 1 . 6, which account for approximately 3.5 per cent of the total sera tested, are considered doubtful and should be tested by another serological test.

Animals↗
PubMed1980

Effect of combination chemotherapy on pituitary-gonadal function in patients with lymphoma and leukemia.

After at least four courses of intermittent chemotherapy, 14 of the 15 men with malignant lymphoma had elevated serum follicle-stimulating hormone (FSH). In three of these subjects, serial studies showed progressive increases in basal FSH and exaggerated FSH responses to luteinizing hormone releasing hormone (LHRH). Although gonadal biopsies were not done, this elevation of FSH is indicative of progressive and severe damage to the germinal epithelium by chemotherapy. Elevated leutinizing hormone (LH) was found in seven and decreased testosterone (T) in two of these subjects. Increased LH responses to LHRH stimulation were also found in the three subjects studied. These findings suggest that the testicular damage is not restricted to the germinal tissue. In four male subjects with acute myeloid leukemia treated by intermittent chemotherapy not containing any alkylating agents, FSH, LH, and T levels were normal. Three of the 4 female patients with malignant lymphoma and two with acute myeloid leukemia had normal basal, serial, and LHRH-stimulated FSH, LH, and estradiol (E2) levels. Elevated gonadotropins and low E2 were found only in subjects who had received abdominal irradiation.

Adult↗
PubMed1980

Polyacrylamide gel electrophoresis of avian rotavirus RNA.

The RNAs of 4 avian rotavirus isolates were analysed by polyacrylamide gel electrophoresis. One of these isolates was made from chickens, the other three were from turkeys. The RNAs were separated into 8 or 9 bands consisting of 11 segments, ranging in molecular weight from 0.24 X 10(6) to 2.09 X 10(6). In contrast to calf rotavirus, segments 10 and 11 of avian rotavirus RNA had very similar or identical electrophoretic mobilities. This may be a unique feature of avian rotavirus RNA. Co-electrophoresis experiments showed that the RNAs of 2 of the turkey isolates were electrophoretically identical. However, differences existed between these 2 isolates, the chicken isolate and the remaining turkey isolate with respect to segments 5, 6, the 7, 8, 9 complex and 10. Segment 5 of the chicken isolate was sometimes resolved into 2 components, and was further anomalous in that it was absent in some (analyses).

Animals↗
PubMed1980

Prevalence of Toxoplasma gondii antibodies in the Chinese population of Hong Kong.

Sera from 2,499 randomly selected Chinese inhabitants of Hong Kong were tested for the presence of Toxoplasma gondii antibodies using the indirect fluorescent antibody test. The over-all prevalence was 9.8%. The prevalence was significantly higher in the 10 to 19 and 30 to 39 year age group and the highest level of titres was found in the 20 to 29 group. There was no significant difference in prevalence between the male and female population and between the rural and city dwellers. The distinctly low prevalence of toxoplasmosis in Hong Kong can probably be attributed to the absence of cats in most domestic households and the preference of the people to eat well-cooked meat (commonly beef and pork).

Adolescent↗
PubMed1980

Globin chain synthesis in haemoglobin New York (beta 113 replaced by glutamic acid).

The presence of Hb New York was confirmed in a Chinese family in which affected members have occasional red cells with Hb-H-like inclusions and a relative decrease in alpha chain synthesis, suggestive of a coexisting alpha thalassaemia trait. However, globin gene mapping and DNA hybridization revealed no deletion of the alpha genome. Timed-incubation experiments showed that the rate of synthesis of beta NY chain was greater than that of normal beta chain in the early periods. Chromatographic separation of Hb NY and Hb A before chain analysis revealed preferential binding of newly synthesized alpha chains to beta NY, with a four-fold increase in specific activity of the alpha Hb NY chains. It is concluded that beta NY chain is being synthesized more rapidly and its increased turnover may account for this presentation of apparent alpha chain deficiency.

Adult↗
PubMed1980

Deep vein thrombosis and changes in coagulation and fibrinolysis after gynaecological operations in Chinese: the effect of oral contraceptives and malignant disease.

Of 154 Chinese patients who underwent gynaecological operations, four showed a positive 125I fibrinogen leg scan for venous thrombosis, and overall incidence of 2 . 6%. In those who were on oral contraceptives and had major pelvic surgery for benign conditions, the incidence was 10 . 5%; in those who had Wertheim hysterectomy for carcinoma of cervix, it was 6 . 7%. This confirms the rarity of post-operative thromboembolism in the Chinese. Fragment E showed a biphasic rise after major operation due to tissue injury and venous thrombosis. In patients with malignancy, the postoperative 'fibrinolytic shutdown', represented by decreased plasminogen activator together with increased alpha 1 antitrypsin and C1- inhibitor levels, was more marked. In addition, alpha 2 macroglobulin level was lower and fell significantly after operation. In patients on oral contraceptives, fragment E levels were higher after surgery and there was no decrease in plasminogen activator levels. Antithrombin III levels did not fall except in three of the four patients with venous thrombosis. A marked increase in fragment E level and a decrease in antithrombin III level might be useful diagnostic markers for postoperative venous thrombosis.

Asian People↗
PubMed1980

Two different molecular organizations account for the single alpha-globin gene of the alpha-thalassemia-2 genotype.

The alpha-thalassemia-2 (alpha-thal-2) genotype or mild alpha-thalassemia gene consists of a single structural alpha-globin gene on the chromosome that normally bears two alpha-globin genes. We used blot hybridization to investigate variation in the molecular organization of this genotype and to determine the distributions of these variations in the world population. Two different patterns of gene organization responsible for the alpha-thal-2 genotype were found: the first was the result of a 4.2-kilobase pair deletion involving the normal 5' alpha-globin gene (leftward deletion alpha-thal-2 genotype), and the second probably the result of a crossover deletion of a DNA fragment bridging the two normal alpha-globin genes (rightward deletion alpha-thal-2- genotype). The rightward deletion was found in all 9 Black subjects, all 8 Mediterranean subjects, and 4 of 13 Chinese subjects. The leftward deletion was found in four and the nondeletion alpha-thalassemia lesion was found in five of the nine remaining Chinese subjects. It is likely that these deletions are related to specific DNA sequences that determine DNA recombinational events.

Asian People↗
PubMed1980

Rural out-migration and economic standing in a prairie setting.

"This study attempts to trace the determinants of rural out-migration for a typical portion of the Canadian Prairies, namely agricultural Manitoba. In concentrating on the 'push' factors responsible for gross out-migration over the period 1966-71, the study considers aspects of several dimensions: spatial, economic, social, ethnic and demographic. However, in order to explore the ramifications of interaction between migration and these multifaceted factors, a model is construed which dwells not only on the forces responsible for out-migration, per se, but also on those capable of regulating rural economic structure and agricultural welfare."

Americas↗
PubMed1979

Histologic prognostic indicators in hepatocellular carcinoma.

Survival and histologic features were studied in 80 patients with proven hepatocellular carcinoma (HCC). The overall survival was 50% at 3.5 weeks with a statistically significant drop in mortality rate after 8.5 weeks. Patients with diffuse clear-cell pattern, focal clear-cell pattern, and no clear cells in their tumors had a 50% survival rate at 14 weeks, 6 weeks, and 3 weeks respectively; the differences in survival rates were statistically significant between any pair (p less than 0.001). No correlation was found between survival and (1) cytologic differentiation, (2) histologic architecture, (3) degree of pleomorphism, or (4) presence of bile production, proteinaceous secretion, giant cells, or cytoplasmic hyaline bodies. Eosinophilic HCC with lamellar fibrosis was not observed in any of our materials. We concluded that the presence of clear cells was the only histologic feature of prognostic significance in our patients.

Carcinoma, Hepatocellular↗
PubMed1979

Biochemical studies with infectious bursal disease virus: comparison of some of its properties with infectious pancreatic necrosis virus.

Infectious bursal disease (IBD) virus was purified from the bursae of infected chickens. Two morphologically indistinguishable populations of virus particles were separated in sucrose gradients and possessed sedimentation coefficients of 295S and 460S. Both populations contained RNA and had identical polypeptide compositions. IBD virus banded at a density of 1.31 g/ml in CsCl and at 1.24 g/ml in sodium potassium tartrate. IBD virus contained two RNA segments with mol. wts. of 2.4X10(6) and 2.2X10(6) as estimated by polyacrylamide-agarose gel electrophoresis, but sedimented in sucrose gradients at 15S. Virus RNA was resistant to 0.1 micrograms/ml ribonuclease treatment under conditions in which ribosomal RNA was completely hydrolysed, but was sensitive to 1.0 and 10 micrograms/ml treatments. These results suggest that the RNA consists of either double-stranded or highly ordered single-stranded molecules. IBD virus contained seven polypeptides with mol. wts. in the range 97,000 to 24,000. Two polypeptides were absent in empty particles of IBD virus. IBD and infectious pancreatic necrosis (IPN) viruses were morphologically indistinguishable. IPN virus possessed a sedimentation coefficient of 440S and banded at a density of 1.32 g/ml in CsCl. In addition the electrophoretic mobilities of IBD and IPN virus RNAs were almost identical. Polyacrylamide slab gel electrophoresis showed that while the number and size of the polypeptides were different for each virus there were similarities in the overall pattern.

Animals↗
PubMed1979

Isolation and cell culture propagation of rotaviruses from turkeys and chickens.

Rotaviruses were detected by electron microscopy in the faeces of turkey poults and broiler chickens with diarrhoea. Apparently symptomless infection was also observed in broilers. The avian rotaviruses could not be isolated in cell cultures by conventional techniques, but were adapted to serial growth in chick cell cultures following trypsin treatment of the virus and the cells. Immunofluorescence studies showed that the avian and mammalian rotaviruses are antigenically related. Antibodies to rotavirus were widespread in sera collected from turkeys, chickens and ducks.

Animals↗
PubMed1979

Studies of the replication of a bovine enterovirus RNA.

Replicative intermediate (RI), replicative form (RF) and single-stranded (SS) RNA have been isolated from BHK cells infected with a bovine enterovirus by salt precipitation and gel filtration techniques. Kinetic experiments showed that at no time up to 16 h post-infection (p.i.) did the amount of RF exceed that of RI or SS RNA. Electrophoresis of RF on 1.5% polyacrylamide-agarose gels showed that at least three species of double-stranded RNA were present, one of which was associated with an accessible poly(A)-containing tract. All of the RF was denatured by 99% dimethylsulphoxide (DMSO), although reannealling occurred rapidly when samples were returned to aqueous conditions. No evidence for circular structures in the RF molecular population was found by use of caesium sulphate density gradients containing ethidium bromide. Treatment of RI with ribonuclease produced double-stranded RNA molecules, some of which were smaller in size than intact RF. Denaturation with DMSO and analysis on 99% DMSO sucrose gradients showed that the RI did not contain single strands of greater length than virion RNA. A portion of the RI bound to poly(U)-Sepharose 4B columns. The poly(A) tracts involved were present only in the nascent RNA strands with greatest sedimentation coefficients (30 to 35S). Bovine enterovirus induced SS RNA was heterogeneous with regard to both sedimentation through sucrose gradients and mobility on acrylamide gels compared to purified virion RNA. The reason for this difference has never been satisfactorily resolved. Sedimentation through 99% DMSO-sucrose gradients showed that the heterogeneity was due to aggregation rather than any variation in chain length or conformational differences. Our results support the single-stranded template model rather than a circular model for picornavirus RNA replication.

Animals↗
PubMed1979

The determination of antithrombin III by radioimmunoassay and its clinical application.

A radioimmunoassay (RIA) had been developed for the determination of antithrombin III (AT III) in man. The detection limit was 25 microgram/dl. AT III-RIA level and biological activity (anti-Xa) was significantly correlated (r = 0.737, P less than 0.001). Plasma levels in 36 healthy males (mean +/- SD, 19.9 +/- 2.5 mg/dl) and 21 healthy females (19.1 +/- 2.4 mg/dl) were similar. Serial AT III measurements in normal menstruating females showed lower levels during midcycle and higher concentrations during menstruation. In carcinomas, the AT III levels were lower than normal, particularly in hepatocellular carcinoma. In cirrhosis of liver, the levels were markedly decreased and in some patients were below that found in congenital AT III deficiency. Patients with deep vein thrombosis and patients with heart valve replacement had lower levels than normal, while patients with cerebral vascular occlusion had normal levels. The possible use of AT III as a diagnostic tool of post-operative deep vein thrombosis was demonstrated in one patient after hysterectomy. The increased sensitivity, specificity and precision of this type of assay offer distinct advantages over existing methods of AT III estimation.

Adult↗
PubMed1979

The alpha-globin gene adjacent to the gene for HbQ-alpha 74 Asp replaced by His is deleted, but not that adjacent to the gene for HbG-alpha 30 Glu replaced by Gln; three-fourths of the alpha-globin genes are deleted in HbQ-alpha-thalassemia.

Two Chinese patients with HbQ-alpha 2 74 Asp replaced by His beta 2-alpha-thalassemia, one HbQ-alpha 2 74 or 75 Asp replaced by His beta 2 carrier, and one HbG-alpha 2 30 Glu replaced by Gln beta 2 carrier were studied to determine the number of alpha-globin genes in their chromosomes. DNA was isolated from white blood cells and bone marrow cells and studied by liquid hybridization and by hybridization of DNA fragments obtained by restriction enzyme endonuclease digestion (Ecr to nitrocellulose filters. The liquid hybridization analysis showed that in HbQ-alpha 2 74 Asp replaced by His beta 2-alpha-thalassemia, as in HbH disease, only one-fourth of the usual number of alpha-globin genes is present. Hybridization patterns of DNA restriction enzyme fragments showed that in HbQ-alpha 2 74 Asp replaced by His beta 2-alpha-thalassemia one chromosome has both alpha-globin genes deleted and the other chromosome, which carries the alpha-mutant gene, has one alpha-globin gene deleted. Our results show that the HbQ-alpha 74 Asp replaced by His structural gene is located adjacent to a deleted alpha-globin gene, whereas the alpha-globin gene adjacent to HbG-alpha 30 Glu replaced by Gln gene is not deleted.

Aspartic Acid↗