Sensitivity of the generator of spontaneous motility in chick embryos to the acute and chronic administration of MPTP.

The acute and chronic effect of 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) on spontaneous motor activity and its development was studied in chick embryos. 1. From the 13th day of incubation, the acute effect of MPTP (30 mg/kg e.w., up to 60 min after administration) consisted in significant depression of spontaneous motility. From the 17th day, the effect of MPTP in supraspinal compartments of the CNS also began to participate in this depression. 2. The subacute effect of MPTP (up to 24 h after a single dose) was lethal for 11-day-old embryos. Conversely, in older embryos resting motility partly recovered, with signs of an inverse correlation to the embryo's age. The final effect, however, consisted in absolute failure of the hatching process 3. The chronic effect of MPTP (3.57 mg/kg e.w./24 h, from the 4th to the 16th day of incubation) led to a developmental reduction of spontaneous motor activity, chiefly from the 8th to 12th day of incubation. 4. The interaction of nialamide (25 mg/kg e.w.), a blocker of monoaminooxidase produced disparate results with the effect of MPTP in young and old embryos.     

Effect of tubocurarine on the central generator of embryonic spontaneous motility.

The continuous administration of d-tubocurarine (6.5 +/- 0.4 mg/kg e.w./24 h) to chick embryos from the 4th to the 12th day of incubation had a positive effect on defects produced in the development of spontaneous motility either by decentralization of the spinal cord or by chemical phenobarbital depression, or by a combination of both experimental factors. In normal embryos, d-tubocurarine had no effect on the development of spontaneous motility.     

Progebiophilus bruscai (Isopoda:Bopyridae) parasitizing the shrimp Upogebia dawsoni (Thalassinoidea:Upogebiidae), in Baja California Sur, Mexico)]

Parasitism of the isopod Progebiophilus bruscai Salazar-Vallejo & Leija-Tristán over the common mud shrimp, Upogebia dawsoni Williams, was analysed in the Ensenada and Bahia de La Paz, Baja California Sur, Mexico. Mud-shrimps were collected in three similar sites that differ in grain size and in the anthropogenic organic matter enrichment. Four-hundred-nine mud-shrimps were collected; the largest abundance was registered in the organically enriched site, but they were significantly smaller and more heavily parasited than the animals from the site lacking such organic enrichment. The size of the parasite is clearly dependent on the size of the mud-shrimp. This is the first study of the upogebiid-bopyris relationship in Mexico.     

Lectin binding sites on head structures of the spermatid and spermatozoon of the mosquito Culex quinquefasciatus (Diptera,Culicidae)

The presence of intranuclear and acrosomal lectin binding sites in spermatids and spermatozoa of the mosquito Culex quinquefasciatus was analysed. Direct and indirect lectin-gold techniques were used on LR White-embedded cells. The nuclear compartment was the structure most intensely labelled. Early spermatid nucleus showed moderate labelling for peanut agglutinin (PNA), Griffonia simplicifolia IB4 (GS-IB4) and Ricinus communis agglutinin (RCA), and light labelling for the other lectins tested. The sperm nucleus was intensely labelled by all lectins. The acrosome, an enzyme-containing structure, was labelled by some lectins. The anterior acrosomal region was labelled by PNA, while the proximal acrosomal region was labelled by PNA and G. simplicifolia II (GS II) lectins, and showed the presence of fucose residues with the use of Ulex europaeus I (UEA-I) lectin. The spermatozoa stored in the spermatheca showed the same pattern of labelling as that observed in spermatozoa localized in testis and seminal vesicles for all lectins tested. Carbohydrate residues in the nuclear compartment may be involved with the process of chromatin condensation. In the acrosomal region these residues may play a role in the process of spermoocyte interaction.     

Influence of the curing of the killer phenotype inSaccharomyces cerevisiae wine strains on their fermentative behaviour

Fermentative behaviour and cell growth have been studied in grape juice inoculated either with two killerSaccharomyces cerevisiae wild strains or with their Acridine Orange-cured isogenic counterparts. The number of viable cells/ml at the beginning of the fermentation, as well as during exponential growth, were higher in grape juices inoculated with the cured strains. The CO₂ production, fermentative rate and ethanol and acetic acid production were also higher in the cured strains, particularly during the stage of active fermentation. These differences, however, were minimal at the end of the fermentations.     

Helicobacter pylori in Barrett's esophagus.

Barrett's esophagus is an anatomicoclinical state in which, due to the prolonged action of gastroesophageal reflux, the squamous epithelium is replaced by columnar epithelium. Helicobacter pylori has been implicated in the pathogenesis of various gastrointestinal disorders and has occasionally been observed in Barrett's esophagus. The aim of this study is to determine the incidence of H. pylori in Barrett's esophagus and try to establish its role in the pathogenesis of this disorder. H. pylori was observed in 31 biopsies (44.3%) of the 70 studied, mainly when the epithelium is of the gastric atrophic-fundic type (p less than 0.01). Its presence shows no relation to the degree of inflammatory activity and does not seem, therefore, to play an important role in the pathogenesis of the lesion.     

Effects of denervation on the contents of cholesterol and membrane systems involved in muscle contraction in rabbit fast-twitch sarcotubular system.

Denervated fast-twitch rabbit muscles were progressively losing their fresh weight and the yield of sarcotubular protein was increasing. The activity of Ca(2+)-ATPase was affected but very slightly, the basal Mg(2+)-ATPase and the Mg(2+)-ATPase/Ca(2+)-ATPase ratio however increased together with a simultaneous depression of the membrane-bound acetylcholinesterase activity. We did not observe any differences in density properties of sarcotubular fractions between control and denervated muscle. However, a relative enrichment in SM and H fraction could be seen after denervation with small changes in the content of the Ca(2+)-pump protein, increased levels of calsequestrin and cholesterol, mostly in the heavy and the SM fraction. After denervation the binding sites for 3H-PN-200-110 did not show any changes in receptor affinity, but the number of putative Ca(2+)-channels increased twice along with a depression of 3H-ouabain binding sites. We suggest that the denervation of fast-twitch muscle leads to the hypertrophy of the junctional sarcoplasmic reticulum and the T-system. Changes in the cholesterol content, in the number of putative Ca(2+)-channels and in Na+, K(+)-ATPase can affect the muscle contraction.     

Cholesteryl hemisuccinate's inductive effect on membrane rigidization regarding both, its remodelling of the cells' surface receptor pattern and its decreasing the natural killer susceptibility of K-562 cells.

The relationship of changes in membrane fluidity to natural killer susceptibility of K-562 target cells was investigated. Membrane rigidization was performed by the chemical modulator cholesteryl hemisuccinate. Steady-state fluorescence polarization measurements of the diphenyl hexatriene labelled, modified K-562 cells revealed that cholesteryl hemisuccinate increased the structural order of the hydrophobic region of membranes in a dose dependent way. Investigation of natural killer susceptibility followed by 51Cr release assay indicated that modified cells are less sensitive to natural killer attack. To elucidate whether surface structures such as transferrin and lectin receptors are associated with the altered susceptibility, the surface density of these receptors was followed by (I-125)-transferrin binding assay and quantitative immunofluorescence. We found that the number of transferrin and concanavalin A receptors increased by a factor of 2.44 and 2.00, respectively, whereas that of the wheat germ agglutinin receptor failed to exhibit any changes upon rigidization. From the results we concluded that i the membrane structural order does influence the natural killer susceptibility, ii changes in membrane structural order result in alteration of the number of cell surface transferrin and lectin receptors, iii however, no direct relationship seems to exist between these two events.     

Expression of two cytochromes P450 involved in carcinogen activation in a human colon cell line

Cytochrome P450 is known to cause carcinogen activation and correspondingly increased cancer risk in animal models. In order to determine whether P450 in the colon may be involved in cancer development in the human, the human colon cell line LS174T was examined for the presence of various cytochromes P450. Two isozymes of P450 were identified in the human cell line. Expression of P450IAl or IA2 was increased by treatment of the cell line with benzanthracene; the induction was demonstrated by an increase in RNA hybridizing to a probe for P4501Al and by ethoxyresorufin deethylation activity. Western analysis of microsomes isolated from human colon tissue also demonstrated the presence of P4501A1, as well as a form which cross-reacted to an antibody to human P450IIC9. Another isozyme, P450IIE1, was identified by polymerase chain reaction amplification of RNA from LS174T cells. These results underscore the presence of cytochromes P450 in colonic tissue and provide a basis for the involvement of isozyme-specific P450 mediated reactions in carcinogenesis of the colon.Some of the data presented here were taken from a thesis submitted by D.K.H. in partial fulfillment of the requirements for the Ph.D. degree in the University of Texas Graduate School of Biomedical Sciences.     

Properties and participation of “free” endotoxin in the toxic activity ofMorganella morganii

"Free" and "bound" Morganella morganii endotoxin was characterized by chemical (determination of proteins, saccharides and 3-deoxy-2-octulosonic acid) and immunochemical (double-diffusion test, immunoelectrophoresis, tandem crossed immunoelectrophoresis) methods. Chemical analysis showed that "free" endotoxin contains more protein and phosphorus and less saccharides than bound endotoxin. Immunochemical tests revealed differences in the structure of polysaccharide portions of both endotoxins, and, on the other hand, identity of certain antigenic determinants. Free endotoxin possessed a higher biological activity.