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Biomedical subjects

M M Everett

Publications and source records attributed to M M Everett.

16 recordsLinked to original sources
PubMed1990

Lung fibroblasts from animals breathing 100% oxygen produce growth factors for alveolar type II cells.

Type II cells were isolated from rats with a purity of 80-95% with less than 4% macrophages. These cells, after plating for approximately 16 h, were cultured with 50% RPMI 1640 and 50% (vol/vol) conditioned medium obtained from confluent hamster lung fibroblasts, together with 0.1% fetal calf serum (FCS). Conditioned media were obtained from either fibroblasts derived from normal hamsters breathing room air [normoxic-conditioned medium (NCM)] or from hamsters exposed for 4 days to 100% O2 [hyperoxic-conditioned medium (HCM)]. Controls consisted of 100% minimal essential medium (MEM) containing 0.1% FCS. Over a 96-h culture period, NCM stabilized cell populations but was unable to induce proliferation. In contrast, at low cell densities, HCM could cause a two- to threefold increase in type II cell number within 24-48 h after introduction. This effect could not be demonstrated at high cell densities. When tested with FCS concentrations ranging from 0 to 10%, maximum effects were obtained using 0.1-0.2% FCS. We conclude that lung fibroblasts from oxidant-injured hamsters produce growth factors that can stimulate at least one mitotic division in cultured type II cells, which are plated at low density. These factors are absent, or present in much lower concentration, in lung fibroblasts from normal animals.

Animals↗
PubMed1989

Tissue iron deposition in untransfused beta-thalassemic mice.

Homozygous beta-thalassemic mice show many of the features seen in human beta-thalassemia, such as decreased hemoglobin, hematocrit, and red blood cell count as well as increased reticulocyte count. They also exhibit splenomegaly and a decrease in osmotic fragility of red cells. beta-thalassemic mice were examined for spontaneous iron overload at ages ranging from 20 to 595 days. Accumulation of iron was shown to occur in the spleen, liver, and kidneys but not in the heart. Sections of spleen, liver, kidney, and heart were stained for iron and subjectively scored. Image analysis microscopy was used to examine sections of spleen and liver. Nonheme iron in the four tissues was quantitated using the bathophenanthroline sulfonate colorimetric assay. An increase in tissue iron occurred primarily in the spleen, even before weaning, despite the low iron content of milk. Iron accumulation in the absence of blood transfusion is of interest because iron overload is the major cause of death in human beta-thalassemia.

Aging↗
PubMed1986

Effects of fibronectin pretreatment on cardiovascular, acid-base, metabolic, and organ function indices during endotoxin shock in the dog.

Selected hemodynamic, pulmonary, acid-base, metabolic, hematological, and serum chemistry parameters were monitored for 6 hr in two groups of anesthetized dogs given an intravenous injection of Escherichia coli endotoxin. One group of animals was pretreated with purified human plasma fibronectin, and the other group received an equal volume of saline or dextrose. Between-group analysis showed that the fibronectin-treated group had significantly higher arterial blood pressure and glucose levels, and lower hemoglobin levels, at 4, 5, and 6 hr postendotoxin administration. This group also had higher arterial pH and base excess values at 5 and 6 hr postendotoxin administration. This study, along with others from our laboratory, suggests that exogenous administration of purified plasma fibronectin can be beneficial in the prophylactic treatment of impending sepsis or endotoxemia. However, the amount of benefit appears to be moderate. Whether combining fibronectin with other therapeutic modalities would be additive or synergistic cannot be ruled out and merits investigation.

Animals↗
PubMed1981

Histochemistry of lower vertebrate calcified structures. I. Enamel of the dogfish Squalus acanthius compared with mammalian enamel and homologous dentine.

The enameloid and dentine of Squalus acanthius have been compared histochemically with those of Bos taurus. Squalus enameloid is much less reactive to a variety of stains or reagents than dentine or bovine immature enamel but it does have positive reactions with picromethyl blue, Mallory's and Van Gieson's stains, and Alcian blue. It stains faintly with Biebrich scarlet, indicating some anionic groups. Specific reactions for tyrosine, tryptophane, lysine, histidine, arginine, and cysteine are negative. Bos immature enamel is positive for cationic, anionic, and aromatic reactive groups by all test procedures, and dentine was positive for the anionic components. Bovine maturing enamel, however, is more similar in terms of lack of reactivity to Squalus enameloid but differed because the bovine enamel was moderately positive for tyrosine; tryptophane, and anionic groups and negative with Mallory's picromethyl blue and Van Gieson's stains. A fibrous transitional area between Squalus dentine and enameloid has staining reactions characteristic of both collagen and keratins.

Animals↗
PubMed1979

Enamel matrix proteins in normal and abnormal amelogenesis.

Histochemical techniques have been used to study three stages of enamel maturation in normal (fetal calf, newborn human, adult human) and abnormal amelogenesis (odontodysplasia, fluorosis, a compound-complex odontome, and an invaginated odontome). The amount of Type I matrix secreted decreases as amelogenesis progresses. Pockets of Type II matrix may be left at the dentino-enamel junction after maturation of enamel to Type III. Fluorosed enamel contains pockets which may extend the width of the enamel. All stages of enamel maturation may be seen in the compound-complex odontoma.

Amelogenesis↗
PubMed1978

Differential dichrome staining of tissue culture monolayers: alternate dyes and possible mechanism.

A polyacid-dependent dichrome has been devised which will differentiate epithelial from mesenchymal cells in young dividing primary cultures. Epithelial cells and colonies and nuclei are stained with metanil yellow, the stain is fixed and differentiated with phosphotungstic acid, and the mesenchymal elements are stained with toluidine blue. Several other dyes are tested for substitution in this method. Biebrich scarlet and aniline blue could be substituted for the metanil yellow; Bismarck brown T, Janus green B, crystal violet, and neutral red could be substituted for the basic dye.

Cell Nucleus↗
PubMed1976

Enzyme separation techniques for the study of growth of cells from layers of bovine dental pulp.

Effects of the enzymes trypsin, papain, bromelains and ficin on bovine dental pulp tissue were studied. Minced or whole pulps were subjected to each enzyme at 17 degrees, 20 degrees and 37 degrees C for set time intervals, after which aliquots of supernatant fluid were removed for cell counts and viability tests. Pooled samples were subsequently cultured as monolayers in Eagle's MEM plus 10% calf serum. The dissociation characteristics were quite distinct for each enzyme, although quite similar between minced and whole pulp. A parallel histological study was made of the residual pulp tissue. Ficin was found to be the most suitable enzyme for future studies on the growth of isolated pulp cells from various layers of the bovine pulp, due to its even rate of cell removal, and the good initial viability and subsequent growth of the separated cells in monolayer culture. Further studies on ficin may show that it is more suitable for enzymatic separation of tissues generally than the more commonly used trypsin, a major advantage being its use in media containing Ca2+ and Mg2+.

Animals↗