Fresh and fixed tissue from a resection specimen of a calcifying epithelial odontogenic tumour (CEOT) was prepared for histological, histochemical, immunological and biochemical investigation in order to study the nature of the amyloid-like material. The fixed tissue gave positive reactions with Congo-red, Thioflavin T and the dimethylamino benzene (DMAB)-method for tryptophan. The diazotization-coupling (DC) method for tyrosine was negative. The major protein purified from the unfixed tissue by sequential gel filtration had a molecular weight of 9,800. The amino acid analysis of this protein had similarities with tuft enamel protein, immune amyloid and the variable light chain component (VK). From the data obtained in this study, it is not possible to determine the precise nature of the amyloid-like material in this CEOT. However, the results do support the concept that 'amyloid' should be considered as a term describing a broad group of related proteins.

Adult↗

PubMed1981

Transferable tetracycline resistance in Clostridium difficile.

The transfer of tetracycline resistance among strains of Clostridium difficile is described. Transfer occurred by a conjugation-like event that was insensitive to deoxyribonuclease, could not be mediated by donor culture filtrates or chloroform-treated donor cultures, and required cell-to-cell contact. Tetracycline-resistant progeny recovered from matings displayed a resistance phenotype identical to that of the donor in level of resistance, constitutive expression, and transmissibility. Although the original tetracycline-resistant donor contained 5 x 10(6)- and 22 x 10(6)-dalton plasmids, standard physical analyses of antibiotic-resistant transconjugants revealed no plasmid deoxyribonucleic acid molecules in common with the donor strain. Furthermore, tetracycline-susceptible derivatives of the original donor always possessed a plasmid complement identical to that of the resistant parental strain as determined by restriction endonuclease digestion analysis. The results indicate that the tetracycline resistance determinant(s) was not encoded by readily detectable plasmid deoxyribonucleic acid and may be chromosomally located.

Clostridium↗

PubMed1981

Regulation of urease and ammonia assimilatory enzymes in Selenomonas ruminantium.

Urease and glutamine synthetase activities in Selenomonas ruminantium strain D were highest in cells grown in ammonia-limited, linear-growth cultures or when certain compounds other than ammonia served as the nitrogen source and limited the growth rate in batch cultures. Glutamate dehydrogenase activity was highest during glucose (energy)-limited growth or when ammonia was not growth limiting. A positive correlation (R = 0.96) between glutamine synthetase and urease activities was observed for a variety of growth conditions, and both enzyme activities were simultaneously repressed when excess ammonia was added to ammonia-limited, linear-growth cultures. The glutamate analog methionine sulfoximine (MSX), inhibited glutamine synthetase activity in vitro, but glutamate dehydrogenase, glutamate synthase, and urease activities were not affected. The addition of MSX (0.1 to 100 mM) to cultures growing with 20 mM ammonia resulted in growth rate inhibition that was dependent upon the concentration of MSX and was overcome by glutamine addition. Urease activity in MSX-inhibited cultures was increased significantly, suggesting that ammonia was not the direct repressor of urease activity. In ammonia-limited, linear-growth cultures, MSX addition resulted in growth inhibition, a decrease in GS activity, and an increase in urease activity. These results are discussed with respect to the importance of glutamine synthetase and glutamate dehydrogenase for ammonia assimilation under different growth conditions and the relationship of these enzymes to urease.

Ammonium Chloride↗

PubMed1981

Hospital proximity and public acceptance of the mentally ill.

Knowledge of the effect of the geographical proximity of a mental health facility on the public's attitudes toward the mentally ill is useful for community education efforts to reduce public opposition to a facility and rejection of its patients. To study the influence of proximity to a state mental hospital on neighborhood attitudes toward the mentally ill, the author surveyed 140 residents of two similar neighborhoods, one located adjacent to the hospital and the other half a mile away. Acceptance of individuals with symptoms of severe mental illness was significantly higher in the adjacent neighborhood, but there was no difference between the neighborhoods in acceptance of the moderately mentally ill. The results also suggested that residents living immediately adjacent to the hospital were less accepting than the norm for the neighborhood.

Attitude to Health↗

PubMed1981

Leukoplakia-like lesions developing in patients with oral discoid lupus erythematosus.

In a long-term follow-up of 52 patients with oral lesions of discoid lupus erythematosus (DLE) 8 patients showed a gradual transition of the typical DLE lesions to lesions which closely resemble leukoplakia. Histopathologically and immunopathologically the leukoplakia-like lesions generally showed features similar to those in leukoplakias not preceded by DLE. Ultrastructurally, the leukoplakia-like lesions showed the presence of cytoplasmic tubular structures in vascular endothelium in two out of three patients examined. The leukoplakia-like stage is considered to be an inactive or scar-like stage, which may be the mucous membrane counterpart of the atrophic scars following DLE lesions of the skin. A primary examination of a DLE patient presenting oral lesions at the leukoplakia-like stage may result in an incorrect diagnosis. Therefore, when investigating patients with leukoplakias, they should be questioned on previous or present skin lesions as well as symptoms of systemic lupus erythematosus.

Adult↗

PubMed1980

The teeth in osteogenesis and dentinogenesis imperfecta.

Explore the source record for details and available documents.

Dental Enamel↗

PubMed1980

Alpha-fetoprotein molecular heterogeneity. Physiologic correlations with normal growth, carcinogenesis and tumor growth.

Explore the source record for details and available documents.

Animals↗

PubMed1980

Stereological analysis of histological parameters in experimental premalignant hamster cheek pouch epithelium.

Hamster cheek pouch mucosa was treated with the carcinogen DMBA in order to provide samples of epithelium in the various pathological stages of carcinogenesis. Stereological techniques were applied to histological sections of normal and carcinogen-treated epithelium in order to quantify cytological and tissue parameters that may be related to the features of epithelial atypia. The results were compared with values previously obtained for benign epithelial hyperplasia induced by a solution of oil of turpentine. Of the parameters investigated, the nuclear-cytoplasmic ratio, nuclear numerical density and volume-to-interface area ratios were best able to distinguish between benign and premalignant epithelium. The ability to ascribe actual numerical values to histological features which are usually only subjectively evaluated may be a useful diagnostic aid.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1980

Verruciform xanthoma.

This rare lesion is described and what are believed to be the first three cases in the United Kingdom are reported making a total of twenty-nine cases reported in the literature.

Female↗

PubMed1980

Insulin-treated 3T3-L1 adipocytes and cell-free extracts derived from them incorporate 32P into ribosomal protein S6.

Differentiated 3T3-L1 preadipocytes preincubated for 60 min with 32Pi incorporate 32P into ribosomal protein S6 within 5 min after exposure to 0.1-1.0 nM insulin. Undifferentiated 3T3-L1 cells, which possess only 3-5% of the high-affinity cell surface insulin receptors present on the differentiated cells, are less sensitive to this stimulation. Under the same conditions used for insulin, epidermal growth factor, antibody to the insulin receptor, and a combination of isoproterenol and 1-methyl-3-isobutylxanthine also promote 32P incorporation into S6 in the differentiated cells although less effectively than insulin. Cell-free extracts derived from cells treated for 5-10 min with either physiological concentrations of insulin or epidermal growth factor (0.1 microgram/ml) reflect intact cells and catalyze the incorporation of 32P from exogenous [gamma-32P]ATP into ribosomal protein S6.

1-Methyl-3-isobutylxanthine↗

PubMed1980

Origin of amniocentesis-induced rises of alpha-fetoprotein concentrations in maternal serum.

An elevation of alpha-fetoprotein concentration in maternal serum occurred in 7 of 65 patients (11 per cent) following amniocentesis. Analysis of the molecular heterogeneity of the alpha-fetoprotein by chromatography on concanavalin A-agarose indicated that the source of the alpha-fetoprotein was fetal serum in three patients and amniotic fluid in four patients.

Amniocentesis↗

PubMed1980

Experimental dentigerous cysts and enamel hypoplasia: their possible significance in explaining the pathogenesis of human dentigerous cysts.

Cysts lined by epithelium were often found in association with tooth-germ isografts in hamster cheek pouch. They developed from odontogenic epithelium and were in close relation to the crowns of involved teeth. Cysts associated with tooth-germ isografts from 5-day-old animals (17 out of 36) commenced their formation shortly after transplantation as a result of enamel organ degeneration. Teeth associated with these cysts often showed enamel hypoplasia. Accordingly, 86 teeth involved in human dentigerous cysts were examined and 43 were found to possess areas of enamel hypoplasia on their occlusal surfaces or incisal edges. It is suggested that the pathological process initiating cystic degeneration in the enamel organ was also accompanied by degeneration of ameloblasts. When tooth germs from 2-day-old hamsters were transplanted, cystic spaces developed only after completion of enamel formation, 6 weeks following transplantation (in six out of 11 transplants), as a result of separation between the cells of the reduced enamel epithelium. Enamel hypoplasia was not a conspicuous feature. These experimental and clinical observations suggest that there may be at least two types of dentigerous cyst, perhaps with different causes, arising at different stages of tooth development.

Animals↗

PubMed1980

Ammonia assimilation and glutamate formation in the anaerobe Selenomonas ruminantium.

Selenomonas ruminantium was found to possess two pathways for NH4+ assimilation that resulted in net glutamate synthesis. One pathway fixed NH4+ through the action of an NADPH-linked glutamate dehydrogenase (GDH). Maximal GDH activity required KCl (about 0.48 M), but a variety of monovalent salts could replace KCl. Complete substrate saturation of the enzyme by NH4+ did not occur, and apparent Km values of 6.7 and 23 mM were estimated. Also, an NADH-linked GDH activity was observed but was not stimulated by KCl. Cells grown in media containing non-growth-rate-limiting concentrations of NH4+ had the highest levels of GDH activity. The second pathway fixed NH4+ into the amide of glutamine by an ATP-dependent glutamine synthetase (GS). The GS did not display gamma-glutamyl transferase activity, and no evidence for an adenylylation/deadenylylation control mechanism was detected. GS activity was highest in cells grown under nitrogen limitation. Net glutamate synthesis from glutamine was effected by glutamate synthase activity (GOGAT). The GOGAT activity was reductant dependent, and maximal activity occurred with dithionite-reduced methyl viologen as the source of electrons, although NADPH or NADH could partially replace this artificial donor system. Flavin adenine dinucleotide, flavin mononucleotide, or ferredoxin could not replace methyl viologen. GOGAT activity was maximal in cells grown with NH4+ as sole nitrogen source and decreased in media containing Casamino Acids.

Ammonia↗

PubMed1980

Alpha-fetoprotein concanavalin A-binding variants in the diagnosis of neural tube defects and other communicating fetal abnormalities.

We have extended our initial observations (Smith et al., 1979) on th use of determining the alpha-fetoprotein (AFP) concanavalin A-binding variant patterns in amniotic fluid for the detection of certain fetal malformations. We report here our complete series of amniotic fluids between 14 and 36 weeks of gestation from 52 normal pregnancies and 28 abnormal pregnancies including anencephaly, open spina bifida, Turner's syndrome, omphalocele, osteogenesis imperfecta congenita, meningomyelocele, meningocele, spinal cysts, spontaneous abortion and fetal death. The percentage of the total amniotic fluid AFP which was not reactive with concanavalin A was significantly lower in the presence of a communicating fetal abnormality (mean = 4.8%, P less than 0.001), one in which the fetal/amniotic fluid barrier is defective, than in the presence of a normal fetus (mean = 24.7%) (or of a noncommunicating fetal abnormality. We applied the concanavalin A-binding assay to two of the above amniotic fluids from pregnancies in progress and correctly classified the gestations as abnormal. Our results indicate that measurement of the percentage of concanavalin A-non-reactive amniotic fluid AFP is a valuable adjunct in the diagnosis of a communicating fetal abnormality, especially when the elevation of amniotic fluid AFP concentration is equivocal (between 2 and 5 S.D. above the mean), when gestational aging is uncertain or when the total amniotic fluid AFP concentration and ultrasonographic data are inconsistent.

Amniotic Fluid↗