Effects of a fixed time schedule and body weight on ethanol self-administration.

Two experiments are reported. The first study showed that the patterns of ethanol acquisition using the schedule induced self-injection paradigm, are more similar to those of heroin than methadone or nicotine but dissimilar to that of d-amphetamine. The second study showed that ethanol intake once established was not maintained by removal of the schedule. The results also showed that schedule induced behavior may be stressful as indexed by a significant increase of plasma corticosterone levels.     

Heterozygote detection in glucose-6-phosphate dehydrogenase deficiency: limitation of hair follicle analysis

Glucose-6-phosphate dehydrogenase deficiency was demonstrated in a case of favism. The X-linked enzyme defect was expressed in erythrocytes but not in hair root cells. Predictably, the mother shown to be a heterozygous carrier on the basis of intermediate erythrocyte glucose-6-phosphate dehydrogenase activity could not be identified as a carrier by means of hair root study. It seems to be necessary to test the hair roots of at least one enzyme-deficient member of the family to exclude false negative results, if hair root analysis is used for carrier detection. Because of the more or less clonal origin of hair roots, they remain a convenient biopsy material with which to study heterozygosity in X-linked inborn errors of metabolism.     

Reactions to ischemic pain: Interactions between individual,situational and naloxone effects

Fifty-two paid volunteers participated in two separate factorial investigations of the effects of naloxone on time tolerance of and affective reactions to ischemia, as a function of the interaction between expectations of involvement in the experimental situation and experimental variables involving stress or suggestions of analgesia. Naloxoneinduced reduction in tolerance to ischemia interacted significantly with the level of involvement expectancies. The suggestion of analgesia provided no significant naloxonesaline discriminations, but there was a significant interaction between variable memory task conditions and drug effects on the time ischemia was tolerated. These findings suggest that naloxone-opiate receptor interactions may depend on individual differences in attitudes to the situation, but may be potentiated by select environmental stimuli. Analyses of the effects of treatment on affective reactions to ischemia failed to show consistent results.     

The effect of premature delivery on the development of gluconeogenic enzymes in the guinea pig.

The activities of key gluconeogenic enzymes in the livers of newborn guinea pigs were monitored as a function of time following birth either vaginally at term or prematurely by cesarian section at 62 days of gestation. The activity of hepatic glucose-6-phosphatase rose dramatically from 1.40 +/- 0.26 mumol/min/g at birth to a maximum of 6.8 +/- 0.9 mumol/min/g at 24 hr in prematurely delivered animals although there was little significant change in activity in full term animals. The activity of hepatic fructose-1,6-diphosphatase and mitochondrial phosphoenolpyruvate carboxykinase changed little over the first 3 days of life in either full term or premature animals. Cytosolic phosphoenolpyruvate carboxykinase, on the other hand, had low activity at birth being 0.11 +/- 0.03 mumol/min/g in full term and 0.06 +/- 0.04 mumol in premature animals rising to values of 0.71 +/- 0.06 and 1.12 +/- 0.12 mumol/min/g, respectively, at 24 hr of life. Pyruvate carboxylase activities in the premature animals remained significantly lower than those in full term animals in the first 72 hr of life. Transient hypoglycemia was evident in the prematurely delivered animals, but not in the full term animals, the blood glucose values being 82 +/- 7 mg/100 ml for the full term animals and 20 +/- 8 mg/100 ml for the premature infants at 2 hr of life.     

Basilar venous plexus of the posterior fossa: a potential source of error in petrosal sinus sampling

Sampling of serum from the inferior petrosal sinus can provide important information about the source of elevated adrenocorticotropic hormone (ACTH) levels. This often leads to improved results of pituitary surgery for Cushing disease. The authors describe a successful catheterization technique and illustrate the venous anatomy of the inferior petrosal sinuses and basilar plexus.     

Platelet adhesion to collagen types I through VIII under conditions of stasis and flow is mediated by GPIa/IIa (alpha 2 beta 1-integrin)

Platelet adhesion to fibrillar collagens (types I, II, III, and V) and nonfibrillar collagens (types IV, VI, VII, and VIII) was investigated in the presence of physiologic concentrations of divalent cations under conditions of stasis and flow. Under static conditions, platelet adhesion was observed to collagen types I through VII but not to type VIII. Under flow conditions, platelet adhesion to collagen types I, II, III, and IV was almost independent of shear rates above 300/s. Collagen type V was nonadhesive. Platelet adhesion to collagen type VI was shear rate-dependent and optimal at a rate of 300/s. Collagen types VII and VIII showed minor reactivity and supported platelet adhesion only between shear rates 100 to 1,000/s. Monoclonal antibody (MoAb) 176D7, directed against platelet membrane glycoprotein Ia (GPIa; very late antigen [VLA]-alpha 2 subunit), completely inhibited platelet adhesion to all collagens tested, under conditions of both stasis and flow. Platelet adhesion to collagen type III at shear rate 1,600/s was only inhibited for 85%. The concentration of antibody required for complete inhibition of platelet adhesion was dependent on the shear rate and the reactivity of the collagen. An MoAb directed against GPIIa (VLA-beta subunit) partially inhibited platelet adhesion to collagen. These results show that GPIa-IIa is a major and universal platelet receptor for eight unique types of collagen.     

Changes in cognitions for social drinkers in a naturalistic setting

Ten light and eight heavy social drinkers were used in a study designed to investigate the role of cognitions of light and heavy social drinkers during a normal drinking session in a bar. The results showed that there was no significant difference between the light and heavy drinkers for neutral and emotive statements, however, there was a significant difference between the two groups for alcohol dependent and alcohol non-dependent self-statements. A significant interaction was also found for groups x time for the alcohol dependent statements. No significant difference was found for the amount of alcohol consumed. The findings suggest that not all cognitions changed during a drinking session and that emotive and factual statements were unchanged. The results of this study confirm earlier findings which found differences in alcohol related cognitions between light and heavy social drinkers.     

Comparison of the use of L-tyrosine apodecarboxylase and D-serine apodehydratase for plasma pyridoxal phosphate assay

The enzymatic methods for plasma pyridoxal 5'-phosphate (PLP) assay using L-tyrosine apodecarboxylase (apo-LTD) and D-serine apodehydratase (apo-DSD) were compared with respect to their operating characteristics, accuracy and precision. With the apo-LTD assay, the recovery of authentic PLP added to irradiated plasma was 96-100% and the precision for within-run and run-to-run replicates was 4-5% (coefficient of variation). The recovery of authentic PLP with the apo-DSD assay tended to be lower (viz., 95%) and the within-run and run-to-run coefficients of variation tended to be higher (viz., 5-6%), but these differences were not statistically significant. When these two assay methods were directly compared in determining the plasma PLP levels of 67 hospitalized patients, the regression lines exhibited correlation coefficients of 0.89 and 0.92 and slopes of 0.77 and 0.78, respectively. When the plasma PLP values were less than 7.5 ng/ml, the values determined by the apo-DSD assay tended to be higher than those measured by the apo-LTD method and vice versa. The lack of better agreement between the two assay methods may be explained by the fact that an inhibitor exists in plasma extracts that impairs the binding of PLP to apo-DSD and that the correction for this interference may not be uniform from one plasma sample to another. However, if one is willing to tolerate the small discrepancies between the values obtained by the apo-DSD and apo-LTD assays, these assay methods can be used interchangeably. The apo-DSD assay has the advantage of being easily adapted to a modern automated spectrophotometric centrifugal analyzer.