Search PubMed⌕ Search

Biomedical subjects

F Green

Publications and source records attributed to F Green.

90 records · Page 5Linked to original sources
PubMed1983

The thymus dependency of acquired resistance to Trichophyton mentagrophytes dermatophytosis in rats.

Congenitally athymic "nude" (RNU/RNU) rats and euthymic (+/RNU) rats were cutaneously inoculated with Trichophyton mentagrophytes. Dermatophytosis, as evidenced by erythema and scaling, was observed in both athymic and euthymic rats by day 7 postinfection. Macroscopic lesions in +/RNU rats became intensely erythematous (climax days 10-14), were limited in spread and alopecia (days 16-20), and healed with hair regrowth by day 35. In nude rats, however, erythema peaked early (days 8-10) and a persistent, mild erythema and scaling spread over the animals' backs. Viable T. mentagrophytes was cultured from the skin of all infected nude rats for the duration of each experiment (90 days), while +/RNU rats became culture-negative by day 35. Following clearance of primary lesions, +/RNU rats manifest a delayed-type hypersensitivity skin test response to soluble trichophytin and an accelerated cutaneous inflammation and enhanced resistance to reinfection. Although T. mentagrophytes primarily invaded the keratinized layers of the epidermis in both nude and +/RNU rats, hyphae and arthrospores were also observed within the nucleated layers of the internal root sheath of hair follicles. Our observations are consistent with the hypothesis that thymus-dependent cell-mediated immunity is required to limit cutaneous spread and terminate cutaneous T. mentagrophytes infection. This acquired immunity against T. mentagrophytes in +/RNU rats was characterized histologically by: (1) an intense inflammatory migration of lymphocytes, monocytes, and macrophages into the epidermis, dermis, and follicular epithelium; (2) hyperplasia of the epidermis and follicular epithelium; and (3) elimination of arthrospores and hyphae from T. mentagrophytes-infected skin.

Animals↗
PubMed1980

Trichophyton mentagrophytes dermatophytosis in germfree guinea pigs.

Primary and secondary Trichophyton mentagrophytes dermatophytosis was studied in germfree and conventionally-reared Strain 2 guinea pigs. Although the onset and early development of the primary cutaneous lesions appeared similar in both groups, the T. mentagrophytes monoassociated guinea pigs exhibited more severe skin ulcerations and took twice as long to heal as their conventionally-reared counterparts. Cutaneous reinfection of T. mentagrophytes monoassociated guinea pigs was also protracted; however, these lesions healed in about the same time as a primary infection on conventionally-reared guinea pigs. Germfree guinea pigs, sensitized by cutaneous infection with T. mentagrophytes, manifested 3 correlates of systemic cell-mediated immunity: (1) delayed-type hypersensitivity to intracutaneous injection of trichophytin antigen, (ii) in vitro blastogenesis of spleen and lymph node cells to polyclonal mitogens and Trichophyton antigens, and (iii) allergic contact dermatitis 48 hr following cutaneous reinfection. In an additional experiment, we observed that the time course and severity of a primary T. mentagrophytes infection of germfree guinea pigs was reduced by prior feedings with heat-killed T. mentagrophytes culture. These experiments confirm that the normal microbial skin flora is not required for initiation, development or clearance of T. mentagrophytes dermatophytosis. The disease was protracted and severe in T. mentagrophytes monoassociated guinea pigs, but was abbreviated following either active infection or feeding heat killed mentagrophytes culture. These results support the hypothesis that cutaneous T. mentagrophytes infection is a cell-mediated hypersensitivity disease similar to contact dermatitis.

Animals↗
PubMed1980

Cutaneous basophil hypersensitivity and contact sensitivity after cutaneous Trichophyton mentagrophytes infection.

The histopathology of cutaneous lesions and trichophytin skin test responses was examined by light microscopy after the infection of strain 2 guinea pigs with Trichophyton mentagrophytes. Skin biopsies were fixed and stained with procedures which allowed differentiation of the polymorphonuclear granulocytic leukocytes that were present in lesions or skin test reactions. Basophils comprised about one-third of the leukocytes infiltrating the 24 to 48-h trichophytin skin test reactions of guinea pigs sensitized by a cutaneous T. mentagrophytes infection. These results were comparable to the percentage of basophils counted in skin test lesions elicited by the contact agent dinitrochlorobenzene and are consistent with previously published descriptions of cutaneous basophil hypersensitivity. In contrast, the active T. mentagrophytes lesion in the skin of guinea pigs sacrificed at defined intervals after infection or reinfection did not appear to contain similarly elevated numbers of basophils. The early inflammation in primary T. mentagrophytes-induced skin lesions can be characterized histologically as a primary irritant dermatitis which evolves, during the course of the disease, into a chronic mononuclear inflammation. This shift apparently results from host sensitization to fungal antigens during infection and the concurrent development of acquired immunity. Reinfection of guinea pigs with T. mentagrophytes resulted in an accelerated cutaneous inflammation that was temporally and histologically similar to allergic contact dermatitis. These results support the hypothesis that contact sensitivity to T. mentagrophytes develops during the primary cutaneous infection of guinea pigs and is an early component of the hypersensitivity response to reinfection.

Animals↗
PubMed1980

Immunoglobulin-containing cells in jejunal mucosa of children with protein-energy malnutrition and gastroenteritis.

Jejunal biopsies from 20 well nourished children (average age 12.8 months) with gastroenteritis, and 20 children (average age 20 months) with protein-energy malnutrition were examined by immunofluorescent technique for immunoglobulins A, G, M, E, and D, and for epithelial glycoprotein secretory component. Compared with previous studies on normal infants, the children with gastroenteritis showed a moderate increase in IgA-containing cells, a large increase in IgM-containing cells, and no change in IgG-containing cells. These findings are similar to previously recorded findings on adults with gastroenteritis. In contrast there was a pronounced and highly significant decrease in IgA-containing cells in the jejunal mucosa of the children with protein-energy malnutrition. No significant differences were noted between the populations of IgG-, IgM-, IgE-, and IgD-containing cells in the two groups. It is suggested that this selective deficiency in mucosal IgA results from a delay in maturation of the secretory IgA system, and the mechanisms of such a deficiency are discussed.

Child, Preschool↗
PubMed1979

Suppression of in vitro lymphocyte transformation during an experimental dermatophyte infection.

During primary Trichophyton mentagrophytes infection of strain 2 guinea pigs, the colony-forming units (CFU) of fungi present within the lesion peaked between days 7 and 14, whereas the severity of the lesion itself peaked between days 11 and 16. Concomitant with the latter peak, a pronounced depression in the in vitro mitogenic activity of spleen cells (SPC) and lymph node cells (LNC) was observed. Only after resolution of the primary infection (day 21) did LNC show increased deoxyribonucleic acid (DNA) synthesis in the presence of fungal antigens. During cutaneous reinfection, there was no distinct peak fungal load and CFU appeared to decrease steadily during the accelerated course of a reinfection disease. LNC from guinea pigs with severe, ulcerated reinfection lesions generally exhibited a heightened response to fungal antigen in vitro. LNC from guinea pigs with mild reinfection dermatophytosis had depressed in vitro reactivity to mitogens and dermatophyte antigen. The suppression of blastogenic activity during dermatophyte infection appeared to be associated with autologous serum components, since increased DNA synthesis resulted when SPC or LNC were cultured with fetal calf serum. The depressed in vitro DNA synthesis of lymphocytes (cultured with dermatophyte antigens) that were harvested during reinfection was not accompanied by an impaired ability of infected guinea pigs to respond with a delayed-type hypersensitivity skin test in vivo. These results support the hypothesis that experimental T. mentagrophytes dermatophytosis is a cell-mediated hypersensitivity disease that can be modified by immunosuppressive control mechanisms elaborated or induced by the fungus.

Animals↗
PubMed1978

Enzyme changes in rat small intestine during pregnancy and lactation.

Small fluctuations in the activity of a number of important enzymes have been found during the intestinal hyperplasia and hypertrophy of pregnancy and lactation. The pattern of change differs between the enzymes studied, and for individual enzymes often varies between the jejunum and ileum. These results suggest that there must be a complex response to the signals that trigger hyperplasia in the mucosal epithelium.

Animals↗
PubMed1973

Ultrastructure and capsule of Mycoplasma meleagridis.

The ultrastructural study of Mycoplasma meleagridis utilized the electron microscope techniques of sectioning, histochemical staining, critical-point drying, and freeze etching. The predominant morphotype was a spherical form ranging in diameter from 200 to 700 nm. The other morphotypes were dumbbell-shaped cells interconnected by membranous tubules, and chains of streptococcal-like cells. These forms suggest replication by binary fission. An extracellular structure in the form of a capsular matrix was observed by staining with ruthenium red and potassium tellurite, and was also seen in specimens prepared by critical-point drying and freeze etching.

Antibody Specificity↗
PubMed1973

The mechanics of esophageal muscle contraction. Evidence of an inotropic effect of gastrin.

To compare the mechanical properties of lower esophageal sphincter (LES) and esophageal circular smooth muscle, force-velocity determinations were made under various physiological conditions. Isotonic and isometric recordings of opossum circular muscle were used to obtain the velocity of shortening and force, respectively, during alterations in: (a) initial muscle length (preload), (b) afterload, (c) calcium concentration, and (d) gastrin I. Muscle contraction was elicited to the neurogenic response at the termination of electrical stimulation. A change in preload (muscle length) altered the peak force (Po) developed during an afterloaded contraction, but had only a minor effect on the maximum velocity of shortening (V max). At the length of optimal tension development, Lo, (preload, 1.5 g), the LES muscle had a V max of 6.1+/-0.2 mm/s and a Po of 17.7+/-0.7 g. The esophageal muscle at its Lo (preload, 2.0 g) had a V max of 6.3+/-0.5 mm/s and a Po of 18.1+/-1.2 g. A decrease in calcium from 2.5 mM to 1.0 mM significantly reduced the V max and Po of all muscle, but an increase in calcium to 5.0 mM increased these parameters only minimally. At a calcium of 1.0 mM, gastrin I increased both V max and Po of all muscle. This inotropic effect of gastrin I occurred at lower concentrations in LES muscle than in muscle from the upper esophagus. The power (force x velocity) and work (force x muscle shortening) of esophageal and LES muscle were calculated from these data. Both the work and power generated during esophageal and LES muscle contraction were determined by: (a) the initial muscle length as produced by the preload, (b) the afterload against which the muscle was contracting, and (c) the contractility of inotropism of the muscle, that is, the force-velocity curve on which the muscle was operating.

Animals↗
PubMedDate not supplied

Roles of epidemiology, pathology, molecular biology, and biomarkers in the investigation of occupational lung cancer.

The pathology and molecular biology of lung cancer demonstrate that these tumors evolve through a series of mutations, molecular changes, and corresponding morphologic changes. To elucidate how occupational and environmental factors influence lung cancer histogenesis it is important not only to understand epidemiology and the interactions between etiologic agents but also to integrate information from pathology, biochemistry and molecular biology. This review focuses on the range of techniques currently available for characterizing lung cancer and how their prudent use can be beneficial in the identification of occupational carcinogens. Because many occupational and environmental lung cancers are caused by multiple etiologic agents, the integration of histology with cellular, biochemical and molecular biomarker techniques may provide new approaches for understanding the disease process.

Biomarkers↗
PubMedDate not supplied

A common genetic polymorphism associated with lower coagulation factor VII levels in healthy individuals.

We have identified a genetic polymorphism of factor VII that is strongly associated with plasma factor VII coagulant activity (factor VIIc) in healthy individuals from the United Kingdom. This polymorphism was detected after Msp I digestion of polymerase chain reaction-amplified genomic DNA. In a sample of 284 men, the frequency of the M2 allele (loss of cutting site) is 0.1, and individuals with the M1M2 genotype have factor VIIc levels 22% below the sample mean (p less than 0.0001). Msp I genotype was found to be the strongest predictor of factor VIIc, accounting for 20.2% of the variance, with cholesterol accounting for an additional 3.5%. The base change that gives rise to the Msp I polymorphism is a G-to-A substitution in the codon for amino acid 353, leading to replacement of arginine (Arg) with glutamine (Gln) in the protein product of the M2 allele (designated Gln 353). Three individuals homozygous for the M2 allele have both low factor VIIc and low factor VII protein concentrations. The conformation of the Gln 353 molecule may be different from that of the Arg 353 protein, affecting its intracellular processing, secretion, turnover in plasma, or activity. In view of its association with lower factor VIIc levels, possession of the M2 allele may confer protection against thrombosis and myocardial infarction.

Aged↗
PubMedDate not supplied

Asking for money.

Explore the source record for details and available documents.

Financial Management↗