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Biomedical subjects

F W Scott

Publications and source records attributed to F W Scott.

At least 91 records · Page 5Linked to original sources
PubMed1983

Immunogenicity of foot-and-mouth disease virus type O1 replicated in either monolayer or suspended BHK cell system.

The efficacy of vaccines formulated from the 10th passage of foot-and-mouth disease virus (FMDV) type O1 in monolayer baby hamster kidney (BHK) cells and the 8th passage in suspension BHK cells was compared in steers. The vaccines were inactivated with ethylenimine, contained an equal amount of antigen and were emulsified in oil-adjuvant. Six animals were vaccinated with each vaccine. During the challenge of immunity (91 days post-vaccination, DPV), one out of the six steers from the monolayer vaccine group became infected with the challenge virus while none of the six steers from the suspension vaccine group contracted the disease during the test period. The neutralizing antibody titers (means) of the serum samples taken at different DPV also did not suggest significant variation between these vaccines. In addition exposure to FMDV infected animals demonstrated that both vaccines elicited an immune state in the vaccinates.

Animals↗
PubMed1983

Evaluation of a computer-assisted, kinetics-based enzyme-linked immunosorbent assay for detection of coronavirus antibodies in cats.

A computer-assisted, kinetics-based enzyme-linked immunosorbent assay was adapted for the detection of coronavirus antibodies in feline serum. An alkaline antigen diluent (carbonate-bicarbonate buffer, pH 9.6) used in initial experiments produced diffuse, nonspecific color reactions in both viral and control antigen cuvettes which were correlated, paradoxically, with coronavirus antibody levels in test sera. These interfering reactions were minimized by use of lower-pH antigen diluents such as water and phosphate-buffered saline. Background kinetics-based enzyme-linked immunosorbent assay reactivity directed against a noncoronaviral component of antigen tissue culture fluids could then detected in numerous sera, particularly in samples with lower titers. Much of this reactivity was shown to be associated with bovine gamma globulins in cell culture fluid. It was not serum lot or species specific, since a variety of bovine serum lots as well as individual lots of serum from other mammalian and avian species reacted. Reactivity was markedly reduced when cells for antigen preparation were grown in gamma globulin-free bovine serum. Generation of corrected slope values from the kinetics-based enzyme-linked immunosorbent assay made it possible to correct for residual background reactivity in individual test sera and thus eliminate a potentially major source of false-positive reactions. Collectively, these studies indicated that the control of nonspecific reactivity in feline coronavirus serology is absolutely essential to obtain useful estimates of specific antibody responses.

Animals↗
PubMed1983

Macrotiter assay for coronavirus-neutralizing activity in cats using a canine continuous cell line (A-72).

A heterologous neutralization assay for feline infectious peritonitis virus serology was developed using a single continuous cell line of canine origin, A-72, which is susceptible to cytopathic infection with both transmissible gastroenteritis virus of pigs and canine coronavirus. Of several coronavirus isolates tested, the 1-71 isolate of canine coronavirus demonstrated the most effective neutralization by serum and body fluids of cats with histopathologically confirmed feline infectious peritonitis.

Animals↗
PubMed1982

Isolation and characterization of a canine rotavirus.

Canine rotavirus particles were visualized by direct electron microscopy in the feces from a clinically normal dog. The virus was subsequently propagated in cell cultures; it was characterized and compared with rotaviruses from other species. Replication of the virus in cell culture was found to be less dependent upon trypsin than that of human, bovine and porcine rotaviruses. Reproducible, sharp-edged plaques of various sizes were produced by the canine rotavirus in an established cell line of fetal rhesus monkey kidney, MA 104, under overlays of carboxymethyl cellulose or agarose. Intracytoplasmic inclusion bodies of different sizes and shapes were produced in infected MA 104 cells. By plaque reduction neutralization assay, a two-way antigenic relationship was found between the canine (CU-1) and simian (rhesus MMU 18006 and SA-11) rotaviruses. The canine rotavirus had a one-way antigenic relationship with feline (Taka), bovine (NCDV), and porcine (OSU) rotaviruses.

Animals↗
PubMed1982

Variation of rat serum biochemical values following decapitation or anesthesia with ether, halothane or Innovar-VetR: rapid Innovar-VetR-induced hyperuricemia and hyperglycemia.

True reference values (TRV) should ultimately be determined in blood from inactive, unstimulated rats but in practice, acceptable reference values (ARV) may be established using blood from decapitated or anesthetized animals if one is cognizant of variations associated with blood sampling procedures. Data reported here illustrate some variations in serum biochemical values following decapitation or anesthesia. Decapitation does not provide serum in which ARV for sodium, potassium or lactate dehydrogenase can be found but ARV can be determined for glucose, insulin and several other parameters. It is suggested that both TRV and ARV for serum electrolytes be determined using serum from cannulated rats. All three anesthetics raised glucose levels and ether and halothane increased alkaline phosphatase activity. Both halothane and Innovar-VetR decreased insulin:glucose ratios suggesting inhibition of insulin release from the pancreas. Innovar-VetR also produced hypoxia due to severe respiratory depression and bradycardia as well as hyperuricemia, hyperglycemia and hyperphosphatemia. Techniques most likely to provide ARV should be of the shortest possible duration, afford least respiratory and cardiovascular suppression and minimize stimulation of the sympathetic nervous system.

Anesthetics↗
PubMed1981

Detection of astroviruses in feces of a cat with diarrhea. Brief report.

Astroviruses were detected by electron microscopy in the feces from a 4 month old kitten with diarrhea. The mean diameter of the viral particles was 28.7 nm, and they showed characteristic five- or six-pointed star-shaped surface configurations. The clinical disease manifested by the cat and the observed morphology of the viral particles are consistent with previous reports on astroviruses of other species.

Animals↗
PubMed1981

Antibody-mediated enhancement of disease in feline infectious peritonitis: comparisons with dengue hemorrhagic fever.

Non-immune kittens passively immunized with feline serum containing high-titered antibodies reactive with feline infectious peritonitis virus (FIPV) developed a more rapid disease after FIPV challenge than did kittens pretreated with FIPV antibody-negative serum. Antibody-sensitized, FIPV challenged--kittens developed earlier clinical signs (including pyrexia, icterus, and thrombocytopenia) and died more rapidly than did non-sensitized, FIPV-challenged kittens. Mean survival time in sensitized kittens was significantly (P less than 0.05) reduced compared to non-sensitized kittens (mean +/- SEM, 10.0 +/- 0.6 days vs. 28.8 +/- 8.3 days, respectively). Lesions induced included fibrinous peritonitis, disseminated pyogranulomatous inflammation and necrotizing phlebitis and periphlebitis. FIPV antigen, immunoglobulin G, complement (C3) and fibrinogen were demonstrated in lesions by immunofluorescence microscopy. The pathogenesis of dengue hemorrhagic fever (DHF) in persons bears striking resemblance to that of FIP in experimental kittens. In both FIP and DHF, non-neutralizing antibody may promote acute disease by enhancement of virus infection in mononuclear phagocytes or by formation of immune complexes, activation of complement and secondary vascular disturbances.

Animals↗
PubMed1981

Isolation and characterization of feline rotavirus.

Feline rotavirus was detected by electron microscopy in the faecal samples of a cat, and was propagated in an established cell line of foetal rhesus monkey kidney, MA104, cell cultures. Morphologically, feline rotavirus was indistinguishable from known rotaviruses. Complete particles showed a characteristic "spoke-like' arrangement of inner capsomers surrounded by an outer layer. Intracytoplasmic inclusion bodies in different sizes and shapes were produced in infected MA104 cells. Reproducible clear-cut plaques were produced by feline rotavirus in MA104 cells under the overlay of carboxymethylcellulose in the presence of trypsin. Feline rotavirus was distinct from human, canine, bovine, porcine and simian rotaviruses by the plaque reduction neutralization test. Feline rotavirus, like canine and simian rotaviruses, was found to be less dependent upon trypsin than human, bovine, porcine, chicken and turkey rotaviruses. A seroepidemiological survey (September 1979 to August 1980) showed that 20 out of 61 (32.8%) randomly sampled hospitalized cats at the Cornell Veterinary Teaching Hospital in Ithaca, New York had antibody titres against feline rotavirus. Oral inoculation of cats with feline rotavirus did not produce any clinical disease, but most cats did mount an immune response to the virus following inoculation.

Animals↗
PubMed1981

Pathogenesis of feline infetious peritonitis: pathologic changes and immunofluorescence.

Feline infectious peritonitis (FIP) was experimentally induced in FIP virus (FIPV) antibody-positive and antibody-negative kittens after challenge exposure to live-virus aerosol. Seropositive kittens developed antiviral immunofluorescence and lesions more rapidly after challenge exposure than did seronegative kittens. In seropositive kittens, FIPV antigen was present in macrophages and large mononuclear cells in tracheobronchial lymph nodes, lungs, and trachea on postchallenge-exposure day (PCD) 2; in liver and spleen on PCD 3; in kidneys and omentum on PCD 4; and subsequently in nasal turbinates, thoracic and abdominal lymph nodes, thymus, bone marrow, parotid salivary gland, eyes, and brain. Initial antiviral immunofluorescence on PCD 2 coincided with the onset of viremia and vascular lesions. Systemic lesions characterized by perivascular necrotizing pyogranulomatous inflammation, phlebitis and thrombosis, fibrinous serositis, and generalized lymphoid necrosis developed on PCD 3 and 4. Coronavirus-like particles were observed by electron microscopy in cytoplasmic vacuoles or smooth endoplasmic reticulum of degenerating macrophages in inflammatory lesions. In seronegative kittens, antiviral immunofluorescence in tracheobronchial lymph nodes was first detected on PCD 5, and viremia occurred on PCD 6. Systemic necrotizing lesions, comparable with those observed in seropositive kittens on PCD 3 or 4, did not occur in seronegative kittens until PCD 13 or 16. In both groups of kittens, initial viral infection in regional lymphoreticular tissue was followed by viremia and infection of macrophages in reticuloendothelial organs (liver, spleen, lymph nodes) and perivascular locations. The accelerated onset of infection and lesions indicative of an Arthus-type reaction in challenge-exposed seropositive vs seronegative kittens further supports the immune-mediated pathogenesis of FIP.

Animals↗
PubMed1980

Isotope-dilution analysis of the effects of deoxyguanosine and deoxyadenosine on the incorporation of thymidine and deoxycytidine by hydroxyurea-treated thymus cells.

It is presumed that the dGTP and dATP needed for replicative DNA synthesis can be formed by way of either ;salvage' pathways or biosynthesis de novo. This was examined by adding hydroxyurea to cultures of rat thymus cells to inhibit ribonucleoside diphosphate reductase, a key enzyme of the ;de novo' pathway. Most of the inhibition of the incorporation of [Me-(3)H]thymidine and deoxy[5-(3)H]cytidine by low concentrations of hydroxyurea (100-500mum) was prevented by substrates of the salvage pathway (400mum-deoxyguanosine and, to a lesser extent, 200mum-deoxyadenosine). However, isotope-dilution studies indicated that the purine deoxyribonucleosides prevented inhibition by decreasing pyrimidine deoxyribonucleotide competitor pools. Evidence was obtained that a hydroxyurea-induced increase in the thymidine-competitor pool (probably dTTP) was prevented to an equal extent by deoxyguanosine and by the inhibitor of thymidylate synthase, deoxy-5-fluorouridine. These compounds had almost identical effects on hydroxyurea dose-response curves and on thymidine isotope-dilution plots. The evidence suggests that exogenous purine deoxyribonucleosides cannot prevent the inhibition by hydroxyurea of thymus-cell DNA synthesis. This could mean that, with respect to the metabolism of purine deoxyribonucleotides, ribonucleoside diphosphate reductase is tightly coupled to DNA polymerase in a multienzyme complex. The complex would not permit entry of exogenous metabolic intermediates into the ;de novo' pathway, but would still be subject to the regulatory effects of these intermediates. Thus dGTP and dATP formed from exogenous purine deoxyribonucleosides by salvage pathways might deplete pyrimidine deoxyribonucleotide competitor pools by inhibiting relatively hydroxyurea-insensitive activities of ribonucleoside diphosphate reductase.

Animals↗
PubMed1980

Coronavirus-like particles in the feces of normal cats.

Coronavirus-like particles, morphologically indistinguishable from coronavirus-like particles seen in human, canine, and simian feces, were detected by electron microscopy in the feces from both feline infectious peritonitis antibody-positive and antibody-negative cats.

Animals↗