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Biomedical subjects

F W Scott

Publications and source records attributed to F W Scott.

At least 37 records · Page 2Linked to original sources
PubMed1997

Attempted immunization of cats with feline infectious peritonitis virus propagated at reduced temperatures.

OBJECTIVE: To protect cats by inoculating them intratracheally with feline infectious peritonitis virus (FIPV), followed by a second inoculation with virus propagated at reduced temperatures. ANIMALS: Twelve 12-week-old, specific-pathogen-free kittens. PROCEDURE: Ten to 400,000 plaque-forming units (PFU) of virulent (low passage) FIPV, strain FIPV-1146 were inoculated intratracheally, followed by intranasal inoculation with high-passage FIPV-1146 (10(4) to 10(6) TCID50) on day 133. Cats were allotted to 2 groups and challenge exposed on day 188 by aerosolization of either virulent FIPV-1146 or FIPV-UCD1. RESULTS: Two of the 3 severely affected kittens, given 3 dosages intratracheally, were euthanatized. The third kitten recovered. A serologic response was not detected in cats inoculated with 100 PFU or less and in 1 of 2 cats given 1,000 PFU. Clinical signs of infection were not observed in surviving cats after intranasal inoculation with high-passage FIPV-1146 133 days after the initial dose. All cats seroconverted. Aerosol challenge exposure of all kittens with either virulent FIPV-1146 or FIPV-UCD1 caused no adverse effects except in kittens previously affected after the first inoculation. Residual lesions of FIPV were observed histologically. CONCLUSIONS AND CLINICAL RELEVANCE: There appeared to be a beneficial effect clinically by intratracheal/intranasal inoculation, but not complete protection, as observed histologically.

Administration, Intranasal↗
PubMed1996

Raccoon poxvirus feline panleukopenia virus VP2 recombinant protects cats against FPV challenge.

An infectious raccoon poxvirus (RCNV) was used to express the feline panleukopenia virus (FPV) open reading frame VP2. The recombinant, RCNV/FPV, was constructed by homologous recombination with a chimeric plasmid for inserting the expression cassette into the thymidine kinase (TK) locus of RCNV. Expression of the VP2 DNA was regulated by the vaccinia virus late promoter P11. Southern blot and polymerase chain reaction (PCR) analyses confirmed the cassette was in the TK gene of the RCNV genome. An immunofluorescent antibody assay using feline anti-FPV polyclonal serum showed the expressed viral antigen in the cytoplasm of infected cells. Radioimmunoprecipitation with the same antiserum detected a 67-kDa VP2 protein which exactly matched the migration of the authentic FPV VP2 protein by SDS-polyacrylamide gel electrophoresis. Nine five-month-old cats were vaccinated and 21 days later were boosted with the recombinant virus. Peroral FPV challenge 2 weeks after the booster showed that the cats were fully protected as measured by examining clinical signs and total white blood cell counts in peripheral blood. Cats not immunized developed low to very low leukocyte counts following peroral FPV challenge. The nine vaccinated cats showed high FPV neutralization antibody prior to challenge, whereas nonvaccinated cats formed anti-FPV antibodies only after challenge.

Animals↗
PubMed1996

Cytokine gene expression in the BB rat pancreas: natural course and impact of bacterial vaccines.

In diabetes prone BB rat pancreas the Th1/ Th2 cytokine balance and the expression of inducible nitric oxide synthase (iNOS) was determined by mRNA analysis before and after the onset of insulitis. Specific mRNA was amplified by reverse transcriptase polymerase chain reaction, quantitated with radiolabelled probes by phosphoimaging and calibrated with the amount of co-amplified beta-actin mRNA. At 50 days of age, prior to recognizable insulitis, there was already significantly enhanced expression of both, Th1 and Th2 cytokines, and of iNOS mRNA, when compared to Wistar rat pancreas (p < 0.001). This supports the concept of an inconspicuous early phase of islet infiltration by single immunocytes, called single cell insulitis. At 70 days of age mononuclear infiltration of islets had begun and was associated with upregulation of interferon gamma (IFN gamma) and iNOS, but downregulation of interleukin-10 and transforming growth factor beta mRNA (p < 0.001). These findings correlate the onset of insulitis with a shift of the Th1/Th2 cytokine balance towards Th1 cell reactivity. Indeed there was a close correlation of the Th1/Th2 cytokine ratio but not of absolute IFN gamma mRNA levels with the insulitis score. Vaccination at day 50 with tetanus toxoid did not affect cytokine gene expression while diphtheria toxoid and even more strongly BCG administration induced a shift towards Th2 reactivity (p < 0.001) while iNOS mRNA was decreased (p < 0.01). Oral dosing with immunostimulatory components of Escherichia coli also changed the quality of inflammation. Oral lipopolysaccharide (LPS) from E. coli and OM-89, an endotoxin free extract containing immunostimulatory glycolipopeptides and heat shock protein (hsp) 65, both downregulated IFN gamma mRNA while only OM-89 in addition suppressed iNOS mRNA and enhanced Th2 cytokine gene expression (p < 0.001). We conclude that the onset of insulitis is associated with a shift towards Th1 cytokine and iNOS gene expression. Diphtheria toxoid and BCG vaccination stimulates Th2 reactivity but does not downregulate Th1. The latter can be achieved through oral administration of LPS or a glycopeptide fraction (OM-89) from E. coli.

Administration, Oral↗
PubMed1996

A meta-analysis of infant diet and insulin-dependent diabetes mellitus: do biases play a role?

We evaluated the relation between early infant diet and insulin-dependent diabetes risk with a meta-analysis of 17 case-control studies. A summary of all studies indicated a moderate effect for exposure to breast-milk substitutes [odds ratio (OR) = 1.38; 95% confidence interval (CI) = 1.18-1.61] and cow's milk-based substitutes (OR = 1.61; 95% CI = 1.31-1.98) before 3 months of age. Fourteen studies relied on retrospectively collected infant diet data based on long-term maternal recall, which may be biased or inaccurate; three studies used existing infant diet records to assess exposure, thus lessening the possibility of recall bias or inaccurate data. The studies using existing records demonstrated little association compared with the studies relying on long-term recall. Studies in which the controls had a participation rate that was more than 20% lower than that of the cases showed a stronger diabetogenic effect of never being breast-fed (OR = 1.58) than studies whose cases and controls had similar participation rates (OR = 1.06). Thus, differences in the participation rates of cases and controls may have biased the results of these studies. This meta-analysis indicates that the weak association between infant diet and risk of diabetes mellitus may have methodologic explanations.

Australia↗
PubMed1995

The effect of different levels of dietary alpha-linolenic and other fatty acids on mammary gland ductular cell proliferation in female Swiss Webster mice.

In previous work we have shown that changing the fatty acid composition of a constant amount of fat in a modified AIN-76A diet affected the level of ductular cell proliferation in the mammary glands of young virgin female Swiss Webster mice. In particular, linoleic acid concentrations of 5-10% of the total fat in the diet led to variable but appreciably higher levels of proliferation than did higher levels of linoleic acid. In this report it is shown that feeding low levels of the total fat as alpha-linolenic acid (0-5%) resulted in a similar effect. In addition the effects of other fats including menhaden oil, were further investigated.

Animals↗
PubMed1995

Low incidence of autoimmune type I diabetes in BB rats fed a hydrolysed casein-based diet associated with early inhibition of non-macrophage-dependent hyperexpression of MHC class I molecules on beta cells.

Diabetes-prone BioBreeding (DPBB) rats were fed a diabetogenic, mainly plant-based rodent diet, Purina Chow 5001, or a diabetes-retardant, hydrolysed casein-based diet. The expression of MHC class I antigens on pancreatic beta cells occurred at around 25 days of age in Purina Chow-fed rats, and progressively increased with the length of time of feeding with the Purina diet. Most of the Purina Chow-fed DPBB rats revealed hyperexpression of MHC class I antigens on their pancreatic beta cells by 50 days of age. Approximately 92% of the hyperexpressed Purina Chow-fed DPBB rats developed severe insulitis and diabetes. In contrast, the majority of hydrolysed casein-fed DPBB rats did not show MHC class I antigen hyperexpression and these rats failed to develop insulitis or diabetes. Purina Chow-fed Wistar-Furth rats and diabetes-resistant BioBreeding (DRBB) rats showed only very weak background staining for MHC class I antigens on their beta cells. When Purina Chow-fed (DPBB rats were treated with silica to inhibit macrophage infiltration into the pancreatic islets, the hyperexpression of MHC class I antigens was seen even more clearly, as beta cells remained intact. MHC class II antigens were not detected on pancreatic beta cells from DPBB, DRBB or Wistar-Furth rats, regardless of their diet. On the basis of these observations, we concluded that hyperexpression of MHC class I antigens on pancreatic beta cells was mainly restricted to Purina Chow-fed DPBB rats and that suppression of non-macrophage-dependent MHC class I antigen hyperexpression on pancreatic beta cells by a hydrolysed caseinbased diet resulted in the prevention of insulitis and diabetes.

Aging↗
PubMed1995

Isolation of a highly cytopathic lentivirus from a nondomestic cat.

A feline immunodeficiency virus-like virus (FIV-Oma) isolated from a Pallas' cat (Otocolobus manul) is highly cytopathic in CrFK cells, in contrast to the chronic, noncytolytic infection established by an FIV isolate from a domestic cat (FIV-Fca). The virions have typical lentivirus morphology, density, and magnesium-dependent reverse transcriptase activity. The major core protein is antigenically cross-reactive with that of FIV-Fca; however, FIV-Oma transcripts do not cross-hybridize with FIV-Fca. A conserved region of the FIV-Oma pol gene has 76 to 80% nucleic acid identify with the corresponding pol regions of other feline lentiviruses and 64 to 69% identity with those of human, ovine, and equine lentiviruses.

Animals↗
PubMed1994

Detection of feline coronaviruses in cell cultures and in fresh and fixed feline tissues using polymerase chain reaction.

Feline coronavirus infections in cell cultures and in fresh and fixed feline tissues were detected using a polymerase chain reaction (PCR) test. Cell cultures were inoculated with feline infectious peritonitis virus (FIPV), feline enteric coronavirus (FECV) or sham inoculum. The tissue samples of liver, kidney and spleen were taken from specific-pathogen-free (SPF) cats that were inoculated intranasally with 10(3) TCID50 of FIPV 79-1146 (n = 10), FIPV UCD1 (n = 3) or sham inoculum (n = 3), from clinical cats (n = 43), and from formalin-fixed archived feline tissues (n = 49), respectively. Additional tissue samples were taken from the FIPV-inoculated cats (n = 6) and were kept at 4 degrees C, room temperatures (20-24 degrees C) and 37 degrees C respectively for 0, 6, 12, 24, 48, 72, and 96 hours before frozen (-70 degrees C) for PCR to evaluate the effects of the ambient temperatures and post-mortem intervals on the test. The samples were also fixed in 10% neutrally buffered formalin, 95% ethanol, and Bouin's solution respectively to evaluate the effects of the fixatives on the test. Positive PCR results were obtained from the cell cultures that were inoculated with FIPV and FECV and from the FIPV-inoculated cats (13/13). Negative PCR results were obtained from the sham-inoculated cell cultures and cats (3/3). Of the 92 clinical cats, 7 of the 8 FIP-suspected cats (87.5%) and 51 of the 84 non-FIP-suspected cats (60.7%) were shown to be virus-positive in at least one of the tissue samples. There was no significant difference in the PCR results between the fresh and the formalin-fixed tissues of the clinical cats (P > 0.05). Of the FIPV inoculated cats, the virus was detectable equally well in fresh and formalin-, Bouin's solution- or ethanol-fixed tissues. However, the amounts of total RNA extracted from the fixed tissues were significantly less than those from fresh tissues (P < 0.01). In tissues that were kept at 4 degrees C, the virus was detectable up to 96 h; at room temperatures, up to 48 h; and at 37 degrees C, up to 24 h, respectively.

Animals↗
PubMed1994

Effect of dose and modification of viscous properties of oat gum on plasma glucose and insulin following an oral glucose load.

An extract from oats known as oat gum (OG) is composed mainly of the polysaccharide (1-->3) (1-->4)-beta-D-glucan, which is highly viscous in aqueous solution. Viscous polysaccharides are known to attenuate postprandial plasma glucose and insulin responses. The purposes of this study were to determine the dose-response to OG and establish quantitatively the effect of viscosity on plasma glucose and insulin levels of healthy humans consuming 50 g glucose. Increasing the dose of OG successively reduced the plasma glucose and insulin responses relative to a control without gum. Reduction of the viscosity of OG by acid hydrolysis reduced or eliminated the capacity to decrease postprandial glucose and insulin levels. The ability of OG to modify glycaemic response was unchanged following agglomeration in the presence of maltodextrin. Agglomerated gum dispersed smoothly in a drink without formation of lumps, and development of maximum viscosity was delayed. These properties improve palatability. There was a highly significant linear relationship between log[viscosity] of the mixtures consumed and the glucose and insulin responses. The relationship shows that 79-96% of the changes in plasma glucose and insulin are attributable to viscosity, and that changes occur at relatively low doses and viscosities.

Adult↗
PubMed1994

High beta-glucan oat bran and oat gum reduce postprandial blood glucose and insulin in subjects with and without type 2 diabetes.

The aim of the current study was to characterize the effects of isolated and native sources of beta-glucan, oat gum, and oat bran, respectively, when incorporated into a complete meal. Fasting control subjects and subjects with Type 2 diabetes were fed porridge meals containing either wheat farina, wheat farina plus oat gum or oat bran. Blood samples were collected for 3 h after the test meals and plasma glucose and insulin were measured. Oat bran and wheat farina plus oat gum meals reduced the postprandial plasma glucose excursions and insulin levels when compared with the control wheat farina meal in both control and Type 2 diabetic subjects. This study shows that both the native cell wall fibre of oat bran and isolated oat gum, when incorporated into a meal, act similarly by lowering postprandial plasma glucose and insulin levels. A diet rich in beta-glucan may therefore be of benefit in the regulation of postprandial plasma glucose levels in subjects with Type 2 diabetes.

Adult↗
PubMed1994

Oat beta-glucan reduces blood cholesterol concentration in hypercholesterolemic subjects.

OBJECTIVE: Several studies have indicated that consumption of oat bran lowers blood cholesterol and this effect has been attributed specifically to oat bran's soluble fiber (beta-glucan). This study was designed to test this hypothesis. DESIGN: The purified fibre (oat gum, 80% beta-glucan) was isolated, and agglomerated in the presence of maltodextrin to facilitate dispersion in a drink. Subjects consumed the oat gum (2.9 g beta-glucan), or maltodextrin placebo, twice daily for 4 weeks, in a randomized, cross-over design with a 3 week wash-out between phases. Consumption was equivalent to a daily dose of about 70 g of oat bran. SETTING: The study was with free-living individuals. SUBJECTS: Twenty hypercholesterolemic male and female adults entered, and 19 completed, the study. INTERVENTIONS: Blood lipids from fasting individuals were measured weekly throughout the study. Diet was monitored using 3 day food diaries. RESULTS: There were no significant changes (P > 0.05) in blood lipids during the placebo phase. Mean initial total cholesterol (6.76 +/- 0.13 mmol/l) and low density lipoprotein (LDL) cholesterol (4.59 +/- 0.14 mmol/l) levels fell throughout the oat gum phase, and at week 4 each was reduced 9% relative to initial values (P = 0.0004 and 0.005 respectively). When oat gum was discontinued, total and LDL cholesterol returned to initial levels. There were no significant changes in high density lipoprotein (HDL) cholesterol. Triglyceride levels also remained unchanged except for a singular decrease at week 4 of the oat gum phase relative to the initial value, but not compared to the placebo value. The lowered mean total and LDL cholesterol levels occurred in the absence of any dietary changes. CONCLUSIONS: The main component of the soluble fibre of oats, beta-glucan, significantly reduced the total and LDL cholesterol levels of hypercholesterolemic adults without changing HDL cholesterol.

Adult↗
PubMed1993

Spinal lymphosarcoma and disseminated mastocytoma associated with feline immunodeficiency virus infection in a cat.

The course of naturally acquired infection with feline immunodeficiency virus was monitored in a cat over an 18-month period after diagnosis. The cat was admitted with diarrhea, poor body condition, a bite wound abscess, gingivitis, chronic fever, and splenomegaly. The cat's condition improved after splenectomy and remained stable for approximately 15 months, then began to deteriorate, as gingivitis, polyuria, polydipsia, pyrexia, multiple cutaneous masses, and hind limb paresis developed. The in vitro response of the cat's lymphocytes to mitogens was suppressed, and absolute lymphocyte counts were low. Spinal lymphosarcoma, disseminated mastocytoma, and presumptive diabetes mellitus were diagnosed after euthanasia. Decreased immune surveillance associated with feline immunodeficiency virus-related immunosuppression possibly played a role in the development of neoplastic disease in this cat.

Animals↗
PubMed1993

Identification of antigenic sites mediating antibody-dependent enhancement of feline infectious peritonitis virus infectivity.

We have previously demonstrated antibody-dependent enhancement of feline infectious peritonitis virus (FIPV) infection of macrophages using both virus-specific antisera and monoclonal antibodies (MAbs) to the spike (S) protein of FIPV. To increase our understanding of this phenomenon, six representative MAbs from a previously documented group of 12 enhancing MAbs were used to identify epitopes that mediate antibody-dependent enhancement of FIPV infectivity. Analysis of the results of kinetics-based competitive ELISA (K-cELISA) among these six enhancing MAbs grouped the epitopes into two clusters. Because transmissible gastroenteritis virus (TGEV) and FIPV are so closely related antigenically, we also conducted K-cELISA experiments between the FIPV MAbs and TGEV S protein-specific MAbs for which the epitopes had previously been mapped to specific sites on the TGEV S protein. Results of these assays indicated that the two FIPV epitope clusters are homologues of the previously defined TGEV S protein sites A and E/F. In addition, two TGEV S protein-specific MAbs also induced antibody-dependent enhancement of FIPV infection of macrophages. This functional cross-reactivity provides further support for the close antigenic relationship between FIPV and TGEV. Our results provide a preliminary localization of several enhancing epitopes within the amino acid sequence of the FIPV S protein.

Animals↗
PubMed1993

Seroprevalence of infectious disease agents in free-ranging Florida panthers (Felis concolor coryi).

Serum samples obtained from 38 free-ranging Florida panthers (Felis concolor coryi) in southern Florida, March 1978 through February 1991, were tested for antibodies against eight bacterial, parasitic, and viral disease agents. Sera were positive for antibodies against feline panleukopenia virus (FPV) (78%), feline calicivirus (56%), feline immunodeficiency virus/puma lentivirus (37%), feline enteric coronavirus/feline infectious peritonitis virus (19%), and Toxoplasma gondii (9%). All samples were seronegative for Brucella spp., feline rhinotracheitis virus, and pseudorabies virus. In addition, all the animals tested were negative for feline leukemia virus p27 antigen as determined by enzyme-linked immunosorbent assay. Feline panleukopenia virus was considered to be a potentially significant disease agent; FPV antibodies occurred in the highest prevalences in older age classes (P = 0.027) and in panthers living in the dense mixed hardwood swamps in the western portion of their range compared to the open cypress and sawgrass prairies to the east (P = 0.096). Because < 50 animals remain in this relict population and the probable resultant depression of genetic diversity and lowered disease resistance, FPV or other disease agents could contribute to the extinction of this endangered subspecies.

Animals↗