The formation of a test system for assessing the safety of different types of pertussis preparations: their cytotoxic action on mouse thymocytes in vitro

The test for the evaluation of the toxicity of different types of pertussis preparations as manifested by their in vitro influence on mouse thymic cells (T test) has been finally worked out. The use of the T test has made it possible to reveal the nonstandard character of the production lots of adsorbed diphtheria-pertussis-tetanus vaccines, both whole-cell vaccine and Japanese acellular vaccine. The degree of the in vitro damaging action of pertussis preparations on mouse thymic cells greatly depends on the residual content of Bordetella pertussis nontoxoidized toxin which, in contrast to B. pertussis lipopolysaccharide and filamentous hemagglutinin, produces pronounced cytotoxic action on mouse thymic cells.     

Vaccination status of infants discharged from a neonatal intensive care unit.

OBJECTIVE: To determine the vaccination rate among infants discharged from a neonatal intensive care unit (NICU) and factors affecting that rate. DESIGN: Cross-sectional survey conducted when the children were 12 to 18 months of age. SETTING: NICU at the Royal University Hospital, Saskatoon, Sask. PARTICIPANTS: All 395 infants discharged from the NICU between Jan. 1 and June 30, 1992. MAIN OUTCOME MEASURES: Vaccination rate, ethnic background (native or non-native), place of residence (urban or rural), health status (number of days spent in the NICU), reasons for delay in or incomplete vaccinations (those involving parents'' responsibility, infant illness or contraindications). RESULTS: Of the 395 infants, 20 (5.0%) had died and incomplete information was available for 30 (7.6%). Complete data were available for 345 (87.3%). Of the infants for whom data were available, 8 (2.3%) had never been vaccinated and 142 (41.2%) had a delayed vaccination schedule or had not completed their scheduled vaccinations. Only 195 (56.6%) of the infants had received a full vaccination series. Non-native ethnic background was a predictor of completed vaccinations (odds ratio [OR] 5.40, 95% confidence interval [CI] 3.05 to 9.52). In a univariate model, urban area of residence was not a significant predictor of vaccination status, but when ethnic background was controlled for in a multivariate logistic regression analysis, urban area of residence was found to be inversely associated with completed vaccinations (OR 0.34, 95% CI 0.15 to 0.79). The number of days the child had spent in the NICU was not a significant predictor of vaccination status. CONCLUSION: The vaccination rate of infants discharged from the NICU is not optimal. Urban native children appears to be at risk of not being vaccinated. Non-native infants are five times more likely than native infants to have completed all of their scheduled vaccinations. Methods to improve the rate of completed vaccinations, especially for native children, must be sought and tested.     

Warm temperatures lead to early onset of incubation, shorter incubation periods and greater hatching asynchrony in tree swallows Tachycineta bicolor at the extremes of their range

The onset of incubation varies in birds, with many species beginning incubation prior to clutch completion. Here we examine whether early onset is more likely to occur during high temperatures, a critical prediction of the egg-viability hypothesis, which suggest that birds begin incubation prior to clutch completion in order to maintain egg-viability. We examined onset of incubation in tree swallows Tachycineta bicolor at two locations at the extremes of their breeding range, Alaska and Tennessee. A majority of individuals (68%) began incubation prior to clutch completion. While females in Tennessee were more likely to begin incubation early, there was no difference between sites when differences in temperatures inside nestboxes were controlled in analyses. Rather, early onset of incubation was predicted by the proportion of daily temperatures above physiological zero during laying, a critical prediction of the egg viability hypothesis. Both warm weather and early onset led to shorter incubation periods and increased levels of hatching asynchrony. We found no effect of timing of nesting, female body condition index or clutch size on the probability of beginning incubation prior to clutch completion. Our results are consistent with the egg viability hypothesis, not consistent with a threshold clutch size rule, and do not support the hurry-up hypothesis, that individuals breeding later in the season would begin incubation early to reduce the time spent nesting. Overall, our results suggest that broad scale geographic differences in incubation behaviour may be explained by individual-level responses to environmental conditions.     

Extracellular and cell-associated forms of beta-glucosidase in Thermomonospora curvata

The thermophilic actinomycete, Thermomonospora curvata , released 16-times the beta-glucosidase when grown on protein-extracted lucerne fibre compared with growth on cellobiose or purified cellulose. The intracellular and extracellular betaglucosidases had the same mol. wts (66 kD), but the extracellular enzyme had higher affinities for both p -nitrophenyl glucoside and cellobiose and was more resistant to thermal inactivation.     

Role of membranes and energy-producing reactions in cellular processing of insulin in primary cultures of rat hepatocytes

Incubation of primary cultures of rat hepatocytes with the local anesthetics, procaine or lidocaine, had little or no effect on insulin uptake or degradation but caused an inhibition of insulin-stimulated glycogenesis. While exposure of cultures to the amines, monodansylcadaverine or CH3NH2, resulted in significant dose-dependent decreases in glycogenesis, only monodansylcadaverine (an inhibitor of receptor clustering) decreased uptake whereas CH3NH2 (a lysosomotropic agent) caused increases in both insulin uptake and degradation. When cells were treated with agents which inhibit glycolysis (NaF, 2-deoxy-D-glucose) or oxidative metabolism (2,4-dinitrophenol, carbonyl cyanide m-chlorophenyl hydrazone, NaN3, antimycin A), pronounced inhibitions of each of the bioactivities studied (syntheses of glycogen, protein, lipid) were observed, but only the glycolytic inhibitors decreased insulin uptake. These results suggest that insulin is internalized by an endocytotic process involving receptor clustering and requiring metabolic energy derived from glycolysis. The post-receptor biosynthetic processes involved in the expression of the biological activities of insulin (syntheses of glycogen, protein, lipid) require energy produced by oxidative metabolism while the degradation of insulin is carried out by nonlysosomal mechanisms which are not energy-requiring.     

Photoconversion of 7-dehydrocholesterol to vitamin D3 in synthetic phospholipid bilayers

The incorporation of 7-dehydrocholesterol into synthetic phospholipid bilayers altered the distribution of products after photolysis. In liposomes, the relative amounts of 7-dehydrocholesterol and lumisterol were elevated, and tachysterol was reduced from the levels observed in hexane solution. Z to E isomerization of the previtamin to tachysterol is favored in organic solvents. The inhibition of this process is evidence that an ordered lipid matrix places a new constraint on the conformation of the ring B fission product--one in which the configuration is favorable for a return to a cyclized diene. Further, rate enhancements of up to 15-fold were observed for the thermal isomerization of the previtamin to vitamin D3 in liposomes. The free energies of activation for the reaction at 25 degrees C were reduced by 1.3-1.5 kcal/mol in the bilayer environment compared to that of hexane. As this reaction involves the concerted transfer of a hydrogen via a cyclic intermediate, it provides additional evidence for membrane stabilization of an all-cis conformation of the previtamin. Photoproduct ratios were also studied for 7-dehydrocholesterol adsorbed to a variety of solid supports. That nonspecific interactions of 7-dehydrocholesterol with lipid can influence product formation may have important implications with respect to the mechanism of vitamin D3 biosynthesis.     

Cyclic nucleotide alterations in mixed leukocyte reaction: a preliminary report

Endogenous cyclic adenosine and guanosine monophosphate (cAMP, cGMP) levels were studied in human peripheral blood lymphocytes during mixed leukocyte reactions (MLR). cAMP level was consistently elevated in one-way MLR, with good correlation to 3H-thymidine uptake in these reactions. In contrast, cGMP level was practically unchanged. Irradiation of reacting cell populations resulted in inhibition of cyclic nucleotide phosphodiesterase (PDE) activity. These results suggest that metabolic alterations in cAMP may be associated with immune reactions of cellular recognition.