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Biomedical subjects

F W Scott

Publications and source records attributed to F W Scott.

At least 55 records · Page 3Linked to original sources
PubMed1992

Calories, fat, fibers, and cellular proliferation in Swiss Webster mice.

Increased cellular proliferation has been associated with the enhanced expression of several key stages in carcinogenesis. A standard protocol was used to investigate the effect of specific dietary regimens on cellular proliferation. Young adult Swiss Webster mice were fed for 30 days with modified AIN-76A semi-purified diets designed to illustrate the effects of the levels of dietary or calorie restriction, different fibers and bulking agents, and different fats on cellular proliferation. Female mice were used for the restriction and fat studies, males for the fiber and bulking agent studies. Vaginal smears were taken from females from treatment day 15, and the mice killed 2 days following the first estrus following 30 days feeding; males were killed on the 30th day. One hour before death, mice were injected ip with 0.25 micro Ci/g 3[H]-thymidine. Slides were prepared for radioautography and histopathology. Both dietary and calorie restriction led to reduced 3[H]-thymidine labeling indices in each of the seven tissues studied, the mammary gland being the most severely affected. Different fibers and bulking agents, in specific cases, reduced labeling in the duodenum but not to a consistent statistically significant extent in the colon or colo-rectal region. In the duodenum, oat bran and oat gum were the most effective while wood cellulose (alphacel) had no effect. Investigations on the effects of different fats is continuing. High levels of lard, menhaden oil, or cod liver oil as the fat component of the AIN-76A diet, led to much higher levels of labeled cells in the mammary gland or colo-rectal region than did fat components rich in vegetable oils. The labeling indices appeared to be inversely correlated with the level of linoleic acid in the diet, a presumption that has been confirmed by investigating a series of diets containing different levels of this acid. Anti-oxidants were not used in any of these fat-modified diets. The overall results obtained in these studies clearly indicate the utility of cellular proliferation studies in investigating the effects of dietary modifications.

Animals↗
PubMed1992

Effect of varying the type of fat in a semi-purified AIN-76A diet on cellular proliferation in the mammary gland and intestinal crypts in female Swiss Webster mice.

Young virgin female Swiss Webster mice were fed AIN-76A semi-purified diets containing equal weights of different fats for approximately 30 days. Using [3H]thymidine radioautography, it was established that mice fed 100% lard or high levels of fish oils (menhaden oil or cod liver oil) developed elevated cellular proliferation in the duct cells of the mammary gland and an increased number of labeled cells/crypt in the crypts of the colo-rectum accompanied by an increase in the size of the proliferative compartment. A possible inverse correlation between the level of [3H]thymidine labeling in the mammary gland, but not in the colo-rectum, and the linoleic acid content of individual diets may help to explain the significance of these observations. The effect of adding an antioxidant mixture to these diets was to reduce the excess proliferation induced in the intestinal crypts by lard or fish oil to the level induced by soybean oil, but only partially so in the duct cells of the mammary gland.

Animals↗
PubMed1992

Monoclonal antibody analysis of neutralization and antibody-dependent enhancement of feline infectious peritonitis virus.

Fifty-four monoclonal antibodies (MAbs) to feline infectious peritonitis virus (FIPV) were characterized according to protein specificity, immunoglobulin subclass, virus neutralization, reactivity with different coronaviruses, and ability to induce antibody-dependent enhancement (ADE) of FIPV infection in vitro. The MAbs were found to be specific for one of three structural proteins of FIPV. A total of 47 MAbs were specific for the 205-kDa spike protein (S), 3 MAbs were specific for the 45-kDa nucleocapsid protein (N), and 4 MAbs were specific for the 26- to 28-kDa membrane protein (M). The S-specific MAbs showed various degrees of cross-reactivity with strains of FIPV, feline enteric coronavirus, canine coronavirus, and porcine transmissible gastroenteritis virus. Nineteen S-specific MAbs neutralized FIPV. A total of 15 of the neutralizing MAbs induced ADE, and all but 1 were of the immunoglobulin G2a subclass. The remaining four neutralizing MAbs that did not induce ADE were of the immunoglobulin G1 subclass. Two S-specific MAbs induced ADE but were nonneutralizing. None of the N- or M-specific MAbs was neutralizing or induced ADE. On the basis of the reactivity patterns of the MAbs with FIPV and related coronaviruses, it was concluded that there is a minimum of five neutralizing sites on S. In most instances, neutralizing MAbs were able to induce ADE, demonstrating a direct relationship between neutralization and enhancement. The difference in immunoglobulin subclass between neutralizing MAbs that induced ADE and those that did not induce ADE suggests that there may be a restriction in the immunoglobulin subclasses capable of mediating ADE.

Animals↗
PubMed1992

Monoclonal antibodies to the spike protein of feline infectious peritonitis virus mediate antibody-dependent enhancement of infection of feline macrophages.

Antibody-dependent enhancement of virus infection is a process whereby virus-antibody complexes initiate infection of cells via Fc receptor-mediated endocytosis. We sought to investigate antibody-dependent enhancement of feline infectious peritonitis virus infection of primary feline peritoneal macrophages in vitro. Enhancement of infection was assessed, after indirect immunofluorescent-antibody labelling of infected cells, by determining the ratio between the number of cells infected in the presence and absence of virus-specific antibody. Infection enhancement was initially demonstrated by using heat-inactivated, virus-specific feline antiserum. Functional compatibility between murine immunoglobulin molecules and feline Fc receptors was demonstrated by using murine anti-sheep erythrocyte serum and an antibody-coated sheep erythrocyte phagocytosis assay. Thirty-seven murine monoclonal antibodies specific for the nucleocapsid, membrane, or spike proteins of feline infectious peritonitis virus or transmissible gastroenteritis virus were assayed for their ability to enhance the infectivity of feline infectious peritonitis virus. Infection enhancement was mediated by a subset of spike protein-specific monoclonal antibodies. A distinct correlation was seen between the ability of a monoclonal antibody to cause virus neutralization in a routine cell culture neutralization assay and its ability to mediate infection enhancement of macrophages. Infection enhancement was shown to be Fc receptor mediated by blockade of antibody-Fc receptor interaction using staphylococcal protein A. Our results are consistent with the hypothesis that antibody-dependent enhancement of feline infectious peritonitis virus infectivity is mediated by antibody directed against specific sites on the spike protein.

Animals↗
PubMed1992

Early infant diet and risk of IDDM in blacks and whites. A matched case-control study.

OBJECTIVE: To investigate the role of early infant feeding in the development of insulin-dependent diabetes mellitus (IDDM) and to determine whether an association exists in both blacks and whites. RESEARCH DESIGN AND METHODS: Black and white diabetic subjects were recruited from the Allegheny County and Children's Hospital of Pittsburgh IDDM Registries. Extensive infant diet histories were obtained from the diabetic subjects and their nondiabetic siblings, who were used as nondiabetic control subjects. Each diabetic subject was matched outside his/her family to an unrelated nondiabetic control subject on birth order, birth year (+/- 2 yr), and race, which resulted in 211 case-control pairs with a mean birth year of 1967. RESULTS: In whites, diabetic subjects were less likely to have been breast-fed than control subjects (odds ratio [OR] 0.5, 95% confidence interval [CI] 0.3, 0.9). Breast-feeding prevalence did not differ between black diabetic subjects and control subjects. Duration of overall and exclusive breast-feeding did not differ between diabetic and control subjects in the black and white cohorts. The following analyses, which examined whether the timing of the first breast milk substitute to which the infant was exposed differed between diabetic and control subjects, were conducted for exposure to any breast milk substitute and to breast milk substitutes that were cow's milk based. In whites, age at exposure to any breast milk substitutes and cow's milk-based substitutes were similar between diabetic and control subjects. In blacks, the first exposure to breast milk substitutes occurred significantly earlier for any substitute (5.1 vs. 11.9 wk, P = 0.02) and marginally earlier for cow's milk-based substitutes (3.9 vs. 8.5 wk, P = 0.07) in diabetic subjects compared with control subjects. The first exposure to breast milk substitutes was more likely to occur by 3 mo of age in black diabetic subjects compared with black control subjects (OR 3.3, 95% CI 1.1-10.0) after adjusting for maternal age at birth. The addition of breast-feeding status to the model only slightly weakened this association in blacks. CONCLUSIONS: The analyses of this study cohort suggest that the observed protective effect of breast-feeding on the risk of IDDM may be related to differences in the age at exposure to breast milk substitutes in blacks but not in whites.

Birth Order↗
PubMed1992

Retrospective serologic survey for the presence of feline immunodeficiency virus antibody: a comparison of ELISA and IFA techniques.

A total of 878 samples from the New York State Diagnostic Laboratory (NYSDL), dating from January 1984 to May 1987, were examined to detect antibodies to feline immunodeficiency virus (FIV). We used 2 screening methods; an indirect immunofluorescence assay (IFA) and an enzyme-linked immunosorbent assay (ELISA). Of these, 211 samples were from cats that tested negative for feline leukemia virus (FeLV) and exhibited disease signs consistent with immunodeficiency disease; 19 (9.0%) serum samples were determined to be positive. An additional 508 samples were from cats that tested FeLV-negative and were asymptomatic; 6 (1.2%) sera were determined to be positive. The final 159 samples were from FeLV-positive cats and included symptomatic and asymptomatic animals; this population of cats produced 6 (3.8%) positives. Additionally, 521 samples from the Cornell Feline Health Center (CFHC) serum bank, dating back to 1966, were tested to determine the earliest sample in which FIV antibodies could be detected. Five (2.7%) 1971 and 3 (3.3%) 1969 CFHC samples tested positive. The IFA for FIV antibody proved to be a sensitive (97.4%) and specific (100%) test. The ELISA also had high sensitivity (100%) and specificity (99.6%); however, the IFA proved to be more specific than the ELISA when assaying FeLV-positive cats.

Animals↗
PubMed1991

Comparison and interpretation of diagnostic tests for feline immunodeficiency virus infection.

Feline sera were submitted to the Cornell Feline Health Center (n = 497) or to the New York State Diagnostic Laboratory (n = 1,565) for feline immunodeficiency virus (FIV) testing. Some sera (n = 166) were submitted for confirmation of previous FIV-positive results; 151 of these sera had been tested at the referring veterinary practice or laboratory, using an in-house ELISA. Excluding the samples submitted for confirmation, a total of 173 samples (9.1%) were FIV-positive; 11.6% of the clinically ill or high-risk cats and 0.49% of the healthy, low risk cats were positive for FIV antibody. A commercially available ELISA for detection of antibody to FIV was evaluated in relation to the immunofluorescent antibody (IFA) test and the immunoblot assay. The ELISA was interpreted according to the manufacturer's instructions, with the ratio of sample optical density to positive control optical density (S/P) determining a positive or negative result. The ELISA results based on the S/P interpretation were compared with a kinetics-based (KELA) interpretation of the ELISA. The KELA values were reported as positive, negative, or equivocal. Using the immunoblot as the standard, ELISA (S/P interpretation) had sensitivity of 0.93 and specificity of 0.98, whereas the IFA test had sensitivity of 0.95 and specificity of 0.98. However, the sensitivity and specificity of the ELISA (S/P interpretation) were markedly reduced for sample results falling in the KELA equivocal range, indicating that equivocal results were valid interpretations for some sera. A high number (22.5%) of the samples submitted for confirmation of a positive result from use of the in-house ELISA were determined to be negative for FIV antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Oat gum lowers glucose and insulin after an oral glucose load.

Foods containing soluble dietary fibers delay glucose absorption and lower postprandial plasma glucose. This effect of oat bran has been attributed to oat gum (80% beta-glucan). However, purified oat gum has previously not been available for human studies. In this study the glucose and insulin responses to consuming 14.5 g of specifically prepared oat gum with 50 g glucose were compared with the response to guar gum with glucose and to glucose alone in nine healthy, fasting subjects. Plasma glucose and insulin increases after the glucose drink were greater than after both gum meals between 20 and 60 min (P less than 0.01). The responses to the two gum meals were nearly identical. These results establish that the more palatable oat gum lowers postprandial plasma glucose and insulin concentrations in humans and may be comparable with or of greater benefit than guar gum.

Adult↗
PubMed1991

Dietary plant materials and development of diabetes in the BB rat.

The present study was designed to examine further the impact of individual plant protein sources found in a diabetogenic, cereal-based, rodent laboratory diet, NIH-07 [open formula, nonpurified rat and mouse diet (positive control)], on the development of diabetes. Diabetes-prone BB rats that were pan-T(OX19+)-lymphopenic were fed a low diabetogenic diet during gestation and lactation. Progeny of these rats were fed a normal or autoclaved NIH-07 diet, or one of eight other diets based on the AIN-76A formulation, with modified protein sources as follows: hydrolyzed casein (HC), soybean meal, HC+ trypsin inhibitor (TI) in water (2 mg/mL, wheat germ, alfalfa seeds, Brewer's yeast, red lentils and a plant protein mixture. Feeding soybean meal increased the incidence of diabetes compared with the negative control, HC diet (47% vs. 12% incidence, P = 0.02). Wheat germ, alfalfa seeds and plant protein mixture resulted in an intermediate incidence of diabetes of 33%; the incidence was lower for Brewer's yeast and lentils (20% and 13%). Autoclaving (121 degrees C, 10 min) the NIH-07 diet or the presence of TI in drinking water had a minimal effect on diabetes frequency, suggesting heat-labile plant toxicants were not directly involved. Thus, certain dietary plant protein sources or associated agents may influence the development of spontaneous diabetes in the BB rat.

Age Factors↗
PubMed1991

Conference summary: diet as an environmental factor in development of insulin-dependent diabetes mellitus.

An international symposium on diet as an environmental factor in development of insulin-dependent diabetes mellitus (IDDM) was held in Ottawa, Ont., Canada, September 1989. Several environmental factors such as viruses and chemicals, as well as diet modifications per se, were reviewed in both human and animal diabetes. Although the pathophysiology in the BB rat and nonobese diabetic (NOD) mouse may have different immunological mechanisms, both these animal syndromes of spontaneous IDDM are markedly affected by diet. In them, cereal-based rodent diets are the most diabetogenic and hydrolyzed casein-based purified diets are least diabetogenic. In two different NOD mouse colonies, diabetogenicity of cereal-based diets can be markedly decreased by extracting the diet with chloroform-methanol or water, reflecting either the different composition of the diets used in each colony or the chemical extraction and (or) alteration of certain diabetogenic agents. Thus, dietary lipids can be potent immune system modulators in several systems and the role of chloroform-methanol soluble agents in initiation and (or) promotion of the disease process is being studied. Attention was focused on protein sources previously identified by some groups as diabetogenic such as skim milk powder and wheat products, both of which can be found in natural ingredient rodent feeds. Circulating antibodies to dietary antigens such as bovine serum albumin and (crude) wheat gliadin may be elevated in diabetes-prone rodents and newly diagnosed patients, but their relationship to the pathogenesis of IDDM remains to be established. Because diet components can clearly influence the expression of the diabetic syndromes in the BB rat and NOD mouse, it will be crucial to identify the chemical nature of such components as a first step in understanding their mode of action.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes Mellitus, Type 2↗
PubMed1990

Calorie restriction and cellular proliferation in various tissues of the female Swiss Webster mouse.

Two experiments have been conducted to determine the effects of calorie restriction on cellular proliferation in female mouse tissues. In the first experiment, 25% calorie restriction led to a decrease in cellular proliferation, measured by the [3H]thymidine labeling index, in each of the 7 tissues examined. The duct lining cells of the mammary gland were the most affected. This conclusion was confirmed in the second experiment in which levels of 0, 10, 20, 30 and 40% calorie restriction were employed. The difference in response of the duct cells of the mammary gland and the crypt cells of the colo-rectum is discussed in light of the opinion that the formation of cancer of these tissues in humans may be markedly affected by diet.

Analysis of Variance↗
PubMed1990

Cow milk and insulin-dependent diabetes mellitus: is there a relationship?

Various cow-milk preparations have, with some variation, been reported to be diabetogenic in two animal models of insulin-dependent diabetes mellitus (IDDM), the BioBreeding (BB) rat and the nonobese diabetic (NOD) mouse. However, the suggestion of an inverse relationship between breast-feeding and IDDM based on epidemiological studies, remains controversial. There is a significant positive correlation between consumption of unfermented milk protein and incidence of IDDM in data from various countries. Conversely, a possible negative relationship is observed between breast-feeding at age 3 mo and IDDM risk. Diet may be an important permissive factor in the development of IDDM.

Age Factors↗
PubMed1989

Sensitivity and specificity of blood test kits for feline leukemia virus antigen.

Enzyme-linked immunosorbent assay (ELISA) test kits have been used widely to diagnose FeLV infection. Several companies have licensed such kits, but because these test kits are designed somewhat differently, a demonstration of their relative merits was needed. Differences in the sensitivity and specificity of 7 commercial test kits were determined by testing sera that induce false-negative (limiting dilution of FeLV group specific antigen, p27), and false-positive (cat anti-mouse antibody) test results. Among the panels of sera used in this study, significant differences in test kit sensitivity were not observed, but differences in specificity were identified. An interim report of these studies, supplied to the manufacturers, prompted changes in some of the kits, resulting in improved specificities. Generally, FeLV test kits are now more efficient in accurately detecting p27 in blood, serum, or plasma of cats. Nevertheless, some kits still lack specificity attributable to reagents supplied by the manufacturer.

Animals↗
PubMed1989

Intrinsic resistance of feline peritoneal macrophages to coronavirus infection correlates with in vivo virulence.

Cats infected with virulent feline coronavirus strains develop feline infectious peritonitis, an invariably fatal, immunologically mediated disease; avirulent strains cause either clinically inapparent infection or mild enteritis. Four virulent coronavirus isolates and five avirulent isolates were assessed by immunofluorescence and virus titration for their ability to infect and replicate in feline peritoneal macrophages in vitro. The avirulent coronaviruses infected fewer macrophages, produced lower virus titers, were less able to sustain viral replication, and spread less efficiently to other susceptible macrophages than the virulent coronaviruses. Thus, the intrinsic resistance of feline macrophages may play a pivotal role in the outcome of coronavirus infection in vivo.

Animals↗
PubMed1988

Isolation and identification of feline peritoneal macrophages for in vitro studies of coronavirus-macrophage interactions.

Feline peritoneal cells were collected by lavage with isotonic saline without the use of irritants or need for euthanasia of the cats. Macrophages were purified by centrifugation on Percoll followed by selective adherence. Although few macrophages could be obtained from an initial lavage, a second lavage performed on the same cat 9-11 days later yielded six times as many macrophages as the first lavage, providing sufficient numbers of cells for characterization and infection experiments. Macrophages from these subsequent lavages were not more functionally activated in phagocytosis assays than the resident macrophages from the initial lavage, and they were equally susceptible to infection with feline infectious peritonitis virus (FIPV). Infected cultures produced peak titers of 10(5.0) TCID50 per ml, and FIPV antigen was detected in a small subset (0.1-1.0%) of cells by indirect immunofluorescence. The FIPV-infected cells were identified as macrophages by their characteristic morphology and ability to phagocytize rhodamine-labeled latex beads. The successful isolation of large numbers of unactivated feline macrophages will permit in vitro studies of feline coronavirus-macrophage interactions that otherwise would not have been possible. Such studies will undoubtedly provide valuable insights into the pathogenesis of feline infectious peritonitis, an invariably fatal disease of domestic and exotic cats.

Animals↗