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Biomedical subjects

F H White

Publications and source records attributed to F H White.

At least 73 records · Page 4Linked to original sources
PubMed1982

Isolations of Leptospira interrogans serovars hardjo, balcanica, and pomona from cattle at slaughter.

Kidneys were cultured for leptospires and blood was collected for leptospiral serologic examination from 306 cattle slaughtered in Florida during June, July, and August 1980. Leptospires were found in 82(36%) of 226 otherwise bacterial-free cultures. Forty-five isolates were identified as Leptospira interrogans serovar hardjo, 3 as serovar balcanica, and 3 as serovar pomona. Leptospiral antibodies were found in 218 (71%) of the cattle. Serum titers to hardjo were found in 162 cattle (53%) and to pomona in 28 (9%). Low titers to tarassovi were found in 14 cattle (4.5%).

Animals↗
PubMed1981

A quantitative study of lamina densa alterations in hamster cheek pouch carcinogenesis.

Lesions produced by topical application of 0.5 per cent. DMBA to the hamster cheek pouch epithelium were classified as hyperplasia, dysplasia and carcinoma groups using strict histological criteria. Untreated epithelium served as a control. Tissue samples from five animals in each group were processed for electron microscopy and electron micrographs from the epithelial-connective tissue junction were obtained from 5 blocks per animal. The micrographs were subjected to stereological intersection counting to determine the relative surface (SSLD, BM) of lamina densa which was in normal relationship to the basal cell plasma membranes. Quantitative results indicated a progressive loss of lamina densa during carcinogenesis and this was accompanied by the extrusion of pseudopodia from the basal cells through the gaps. The pseudopodia were frequently related to peripheral cytoplasmic microfilaments. Quantitative data confirmed the progressive nature of this loss, with values for SSLD,BM being of the order of 98 per cent., 88 per cent., 76 per cent, and 42 per cent. for normal epithelium and for the hyperplastic, dysplastic and carcinomatous lesions respectively. The loss of lamina densa is discussed in relation to the specificity of the response and to the development of features indicative of motility in transforming cells.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1981

Quantitative studies of hemidesmosomes during progressive DMBA carcinogenesis in hamster cheek-pouch mucosa.

The present study was designed to establish whether there are changes in hemidesmosomal distribution during defined stages of chemical carcinogenesis in hamster cheek-pouch epithelium. 0.5% DMBA in liquid paraffin was applied thrice weekly to hamster pouches and tissue samples were obtained at regular intervals and assigned to hyperplastic, dysplastic and carcinomatous groups on the basis of histological criteria. Untreated pouches served as controls. Following a strict sampling regime, electron micrographs were obtained from the epithelial-connective tissue junction and, using stereological intersection counting, the relative surface area of basal plasma membrane (BPM) occupied by hemidesmosomes was estimated. In normal epithelium 40% of the BPM is occupied by hemidesmosomes. During carcinogenesis, values decrease progressively and significantly to 35% in hyperplasia, 28% in dysplasia and 13% in carcinoma. A decrease in the relative area of hemidesmosomes would therefore appear to contribute to the increased motility of epithelial cells during a connective-tissue invasion and cellular metastasis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1981

A microbiologic and ultrastructural investigation of germ-tube formation by oral strains of Candida tropicalis.

Presumptive germ tube-positive and -negative Candida tropicalis strains have been obtained from both normal children and patients who have candidiasis. Examination of these strains by conventional microbiologic tests confirmed them to be C. tropicalis. Ultrastructural examination of the filaments produced by the positive strains revealed two types: true germ tubes and those with basally constricted cytoplasm. A fluctuation analysis of the positive strains showed two subgroups: germ tube-positive and -negative. It is suggested that C. tropicalis strains may be divided into germ tube-positive and -negative strains, and that germ-tube formation must therefore not be used as a sole criterion for identification of C. albicans.

Adult↗
PubMed1981

Variations in the nuclear-cytoplasmic ration during epithelial differentiation in experimental oral carcinogenesis.

An increased nuclear-cytoplasmic ratio is one of the cytological features of epithelial atypia taken into account when the histopathologist subjectively assesses whether an epithelial lesion is likely to become malignant. The present work evaluates this ratio ultrastructurally in the DMBA-treated hamster cheek pouch model with a view to assessing whether alterations of this feature represent a valid indicator of malignant transformation. Following DMBA treatment, lesions obtained were assigned to three defined histopathological categories, namely epithelial hyperplasia, epithelial dysplasia and squamous cell carcinoma. Untreated pouches served as controls. Electron micrographs were obtained of basal, spinous and granular layer cells from each of these categories and the N/C ratio was evaluated using stereological point counting techniques. The results indicated that progressive decreases in the ratio occurred in all pathological stages during differentiation (i.e., between basal and granular cells). During carcinogenesis there was a tendency for the ratios to decrease in each cell layer but significant differences were not detected between normal and premalignant lesions.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1980

Ultrastructural morphometry of isolated cells: methods, models and applications.

Isolated cells constitute a favourable experimental model for the pathologist interested in ultrastructural morphometry. A particular advantage is that the same sampling regime may be appropriate for both normal and pathologically-altered material. Often this is not the case with other model systems. This report reviews alternative methodologies for analysing isolated cells, including free cells and dissociated cells in culture. We begin by attempting to define problems of more general concern: preparative techniques, methods of sampling, selection of stereological parameters and possible sources of error. A generalised morphometric model for isolated cells is followed by descriptions of models devised for specific cell types, notably mononuclear phagocytes and cells of the lymphocyte family. Typical results obtained by stereological analyses of these models are presented.

Animals↗
PubMed1980

An epizootic of avian botulism in a phosphate mine settling pond in northern Florida.

Type C botulism was determined to be the cause of an epizootic among waterfowl and shorebirds in a phosphate mine settling pond in northern Florida during May and June of 1979. Several hundred birds, the most common of which were American coots (Fulica americana), wood ducks (Aix sponsa), common gallinules (Gallinula chloropus), and northern shovelers (Anas clypeata), were afflicted over about a three-week period. A second smaller outbreak occurred in the same pond in early December of 1979. This is apparently the first time that botulism has been reported in waterbirds of Florida.

Animals↗
PubMed1979

Mycotic pneumonia in mariculture-reared green sea turtles.

Microbiologic examination of 29 juvenile green sea turtles with a buoyancy abnormality revealed pulmonary infection with Sporotrichium sp, Cladosporium sp, and Paecilomyces sp. Histologic examination of the lungs revealed granulomatous lesions containing branching septate hyphae. The diagnosis was mycotic pneumonia.

Animals↗
PubMed1979

Antimicrobial resistant Salmonella spp. isolated from double-crested cormorants (Phalacrocorax auritus) and common loons (Gavia immer) in Florida.

Antimicrobial resistant Salmonella spp. were found in double-crested cormorants and common loons in Florida. Single or multiple resistance occurred in all Salmonella agona isolates from cormorants, primarily to ampicillin, sulfonamids, streptomycin, neomycin, and kanamycin. Similar patterns of resistance were found in S. agona isolates from common loons. In addition, isolates of S. Saint paul from loons were found resistant to tetracycline and streptomycin, while 2 of 7 isolates of S. infantis were resistant to tetracycline only.

Ampicillin↗
PubMed1979

Hemolysins of Edwardsiella tarda.

Isolates of Edwardsiella tarda from four sources produced nonfilterable hemolsin in trypticase soy broth. The cell-associated hemolysin was partially heat labile, destroyed by formalin and sensitive to treatment with trypsin. These characteristics, and the observation that Ca++ or Mg++ ions enhanced activity, suggest that a proteinaceous, enzymic component may be responsible for the hemolytic activity.

Animals↗
PubMed1977

Starvation-pesticide unteraetions in juvenile brown pelicans.

Nineteen 9-week-old brown pelicans (Pelecanus occidentalis), obtained from a colony in Vero Beach, Florida, containing environmentally acquired p,p'-DDE residues, were subjected to a food deprivation experiment. Samples of brain, liver, muscle, and fat taken after one and two week periods of starvation indicated that starved birds contained significantly greated residue levels in fat compared to non-starved controls. Such differences were not observed in residues in the other tissues. The significance of these findings is discussed in relation to the biology of brown pelicans.

Animals↗
PubMed1977

An epizootic among knots (Calidris canutus) in Florida. I. Disease syndrome, histology and transmission studies.

About 150 knots found sick or dead had distention of serosal blood vessels, and small, raised hemorrhagic foci on the serosal surface of the jejunum and ileum. The principal finding was endaortitis with large intimal multinucleated cysts that contained a protozoan parasite within a cytoplasmic vacuole. There was endarteritis of mesenteric arteries and muscular arteries of the external layers of the intestinal tract. Single or multiple schizont-like stages containing zoites were in the wall of the small intestine and close to affected muscular arteries. The more usual intestinal lesion was an aneurysm of the inflamed muscular artery. It was concluded that endarteritis led to colonic infarction. Schizonts in medullary renal tubular cells were smaller than stages in the intestine. There was necrosis of epithelial cells of themedullary collecting ducts and inflammatory and regenerative changes. Schizonts and zoites were free in collecting ducts and ureters.

Animals↗
PubMed1977

An epizootic of waterfowl associated with a red tide episode in Florida.

During February and March, 1974, an epizootic involving lesser scaup (Aythya affinis) occurred in the Tampa Bay area on the west coast of Florida. Several thousand ducks are estimated to have died. Concurrent with this epizootic was a red tide caused by heavy blooms of the toxic dinoflagellate Gymnodinium breve intoxication were evident in some of the lesser scaup. A controlled experimental feeding of G. breve toxic material to White Pekin ducklings produced illness and death with signs comparable to some of those seen in the scaup.

Animals↗