Contribution to the primary tissue culture technique. A new method for mechanical cell dispersion

Summary A new technique for preparing primary tissue cultures by mechanical cell dispersion was idealized. The time required to prepare a culture by this procedure was greatly reduced and the cultures obtained are morphologically and physiologically of better quality than that obtained by the classical methods of enzymatic cell dispersion.This work was supported by the Conselho Nacional de Pesquisas, Fundo Especial de Despesas do Instituto Butantan and DivisãoNacional do Cancer. The authors wish to thank Mrs.Sibylle Heller for the translation.     

Detection of HLA-E and -G DNA alleles for population and disease studies

HLA-E and -G genes show a restricted polymorphism encoding for molecules whose variability is limited at the peptide binding site. Fourteen alleles that give rise to only three productive proteins for HLA-G (*0101, *0103 and *0104) and five alleles with three different proteins for HLA-E (*0101, *0102 and *0103) have been described. Expression of these molecules is low and found in many tissues for HLA-E; HLA-G protein is expressed in extravillous trophoblast cells and thymic epithelium. Molecular studies have shown how HLA-G and HLA-E bind to natural killer (NK) cells immunoglobulin and lectin-type inhibitory receptors. HLA-E may act as a sentinel of the cell; if classical class I and HLA-G are being expressed, HLA-E molecules may reach the cell surface and inhibit the lysis by NK cells. Most findings are consistent with the hypothesis that HLA-E and -G proteins may be tolerogenic molecules at either the T-cell receptor (TcR) (inflammation, graft rejection) or NK level, switching off cells which usually attack foreign (including foetus) or self (autoimmune) antigens. A low HLA-E and -G polymorphism is observed in humans, and their allele frequencies are mostly homogeneous in the populations tested so far. Many studies to detect these alleles are now being performed in isolated populations and also in pregnancy-associated pathologies. In the present paper, standard and detailed techniques to detect HLA-E and -G DNA polymorphism are reported and discussed. Received 14 July 1999; received after revision 25 August 1999; accepted 25 August 1999     

Quantification of digoxin by enzyme immunoassay: synthesis of a maleimide derivative of digoxigenin succinate for enzyme coupling

Summary We synthesized the m-maleimidobenzoyl derivative of digoxigenin-3-0-succinate (through a p-phenylenediamine bridge) as a hapten derivative directed towards coupling to sulfhydryl groups of -galactosidase. Prepared enzyme conjugate had about 97% of the enzyme labeled with the hapten derivative while retaining full enzyme activity. The enzyme immunoassay for digoxin we prepared showed a maximum sensitivity of 30 pg per assay (c.v.=3%) with minimal cross-reaction with digotoxin (3.8%). Our method for hapten conjugation to -galactosidase is highly efficient and is simple and easily replicated.     

Failure of medial forebrain bundle or raphe ablation to alter the daily temperature rhythm of the rat

Summary The data presented in the present study suggest that neither the ascending noradrenergic fibres confined to the MFB nor the serotonergic fibres originating in or passing through the mesencephalic raphe are essential for periodicity in body temperature. Both control and experimental groups, i.e., rats subjected to medial forebrain bundle or raphe ablation presented circadian periodicity in body temperature and neither the phase, amplitude or overall mean of experimentals differed significantly from controls.     

Morphometric characterization of central molluscan neurons

Resumen Se realiza en la masa ganglionar ventral del moluscoCryptomphallus aspersa (Gasteropoda, Pulmonata) la caracterización morfologico-estadística de las neuronas centrales y células gliales. Se establece la existencia de tres tipos neuronales, las características de su basofilia y la relación entre los tipos, lo que se discute en relación a los hallazgos obtenidos en otras especies por diversos autores.     

Ectopic human chorionic gonadotropin in breast carcinoma.

Immunoreactive human chorionic gonadotropin (hCG) was found in 9 of 65 surgically removed malignant breast tumors. Concentrations ranged from 5 to greater than 500 mIU hCG/g tumor. hCG was measured by a beta-chain specific readiommunoassay. In further study of these specimens, an immunoperoxidase staining technique was used to stain for hCG in formalin-fixed sections. The hCG was shown to be localized within the cytoplasm and on the surface of the malignant cells.     

Control of glass microelectrodes for intracellular recordings

Résumé Une méthode pour vider et examiner des microélectrodes de verre au microscope électronique est décrite. On a trouvé une corrélation entre le diamètre du bout et la résistance électrique. Le diamètre de l'extrémité des électrodes dépend du procédé de remplissement et les meilleurs résultats sont obtenus par la méthode deTasaki modifiée.     

Effect of a restricted diet on the in vitro glucose-induced insulin release of aging rats

To study the effect of a sudden loss of body weight on the -cell function of aging rats, basal and glucose-induced insulin secretion was measured in pancreatic islets obtained from young (2-month-old), adult (12-month-old) and aging (24-month-old) rats, either fed ad libitum or fed a restricted diet (50% caloric restriction). Basal insulin secretion was similar in islets of young, adult and older rats. Glucose stimulated insulin release was significantly reduced in aging rats as compared to young animals. Animals fed a restricted diet showed a prolonged and higher secretory rate during first phase release when compared to animals fed ad libitum.