Tamoxifen fails to block estradiol accumulation,yet is weakly accumulated by the juvenile zebra finch anterior hypothalamus: An autoradiographic study

In experiment 1, we used autoradiographic procedures to examine whether tamoxifen could displace ³H-estradiol labeling in the anterior hypothalamus and the caudal nucleus of the ventral hyperstriatum (HVc) of ovariectomized 20-day-old female zebra finches. There was no significant reduction in labeling of cells by ³H-estradiol in birds preinjected with unlabeled tamoxifen. In experiment 2, we found that injections of ³H-tamoxifen causedweak labeling of cells in the anterior hypothalamus of 20-day-old male and female zebra finches. These results are compatible with the idea that tamoxifen does not block the action of estradiol in the brain of zebra finches, and suggest that the effects of early tamoxifen treatment on the morphology of the song system may reflect central action of tamoxifen.     

Stimulus parameters and temporal evolution of the olfactory evoked potential in rats

Evoked potentials were recorded from olfactory bulb, piriformcortex and scalp in urethane anesthetized rats in response tobrief odorant stimuli (amyl acetate, phenylethyl alcohol, eugenol)presented through a nasal cannula by means of a constant flowolfactometer. The effects of stimulus duration, nasal cannulaposition, flow rate, concentration and interstimulus intervalwere examined. The highest amplitude potentials were evokedby 10% amyl acetate at 20 ms duration, 1000 ml/min flow rateand a 60-s interstimulus interval with the stimulus deliveredat the nares. Odorant evoked potentials from deep within theolfactory bulb consisted of a triphasic wave with major componentsat 60 ms (P60), 90 ms (N90) and 140 ms (P140) with the lattertwo reversing polarity close to the surface of the bulb. Potentialsrecorded from layer I of piriform cortex were of similar amplitude,but opposite in polarity to the deep olfactory bulb potentials.Recordings from the skin over the nose elicited waveforms ofsimilar morphology to the deep olfactory bulb potentials, butone-quarter the amplitude and of opposite polarity The evokedpotentials changed with repetitive stimulation The N90 componentwas not present initially and only appeared after several stimuli.The appearance of the N90 component depended on the integrityof the olfactory peduncle. Thus, olfactory evoked potentialsto odorant stimuli reflect dynamic aspects of the encoding ofolfactory information dependent on connections between olfactorybulb and piriform cortex     

The use of bis(mercaptoacetato-S,O)hydroxoiron(III) complex for the determination of hydroxamates

A rapid, indirect, spectrophometric procedure for the determination of hydroxamates, based on the competition for ferric ions of the bis(mercaptoacetato-S,O)hydroxoiron(III) complex, has been developed. The assay is remarkably free of interferences by common ions, thus rendering it useful in the quantitative determination of hydroxamates in culture fluids and crude preparations.     

Expression of SV40 tumor antigen in SV40 transformed teratocarcinoma-derived cell lines

The relative importance of viral tumor antigen expression and the cellular background in the maintenance of a transformation phenotype was examined in five SV40-transformed teratocarcinoma-derived cell lines. These cell lines show qualitative differences in growth characteristics associated with transformation, and vary in their state of differentiation. Viral T antigen expression was evaluated by two criteria: 1) the amount of immunoprecipitated antigen in growing cells, and 2) the amount and rate of antigen synthesis in density-inhibited cells. There was no direct correlation found between retention, or rate of synthesis, of the viral T antigen and the degree of transformation. These findings imply that the cellular environment has a more important influence on the growth properties of a stably transformed cell than the quantitative levels of viral T antigen expression.     

Genetic heterogeneitiy of Crigler-Najjar syndrome type I: A study of 14 cases

Crigler-Najjar syndrome type I (CN-I) is an autosomal recessive condition characterized by severe unconjugated hyperbilirubinemia caused by the lack of bilirubin-UDP-glucuronosyltransferase (B-UGT) activity in the liver. Two B-UGTs are coded for by a gene complex (UGT1) that maps to chromosome 2q37 and that also encodes two phenol-UDP-glucuronosyltransferases. Here, we report eleven mutations (including nine novel mutations) of the B-UGT1 gene in a large series of 14 unrelated CN-I children of various geographic origins: France (seven patients: A401P, Q357X, W335X, A368T, 1223insG, A291V, K426E, K437X); Portugal (two patients: G308E); Tunisia (two patients: Q357R); Turkey (one patient: S381R); Italy (two siblings: S381R). Interestingly, 6/14 mutant alleles carried by unrelated probands of French ancestry bore the A401P mutation, indicating a founder effect; this effect is probably also present in Portugal, Turkey, and Tunisia. Since mutations occurred in exons 2-5 shared by all mRNAs species of the gene, a combined deficiency of B-UGT and P-UGT was observed in the liver of five patients in whom these activities were measured. The present study confirms that CN-I is genetically heterogeneous and suggests that different founder effects are involved in Western Europe, the Middle East, and North Africa.These results were presented in part at the American Association for the Study of Liver Diseases, Chicago, November 4–7, 1993     

Effect of bacterial heterogeneity on adhesion to uniform collectors by monoclonal populations

Abstract Transport of bacteria over significant distances through aquifer sediments occurs primarily among bacteria with low affinity for sediment materials. Bacterial affinity for a uniform collector surface has been represented quantitatively by a collision efficiency (α), defined as the fraction of colliding cells that adhere to the collector surface. Using a new method for estimating α during advective transport of monoclonal bacterial populations through a uniform bed of 40-μm borosilicate glass spheres, we found that α decreased 10-fold over a bed depth of only 1 cm. Depth-dependent differences in α were not related to variation in bacterial size or intra-strain genetic variation. Intra-population heterogeneity in biocolloid-collector affinity may be important determinant of subsurface bacterial transport characteristics, with critical implications for pathogen transport and dispersal of bacteria for the remediation of hazardous waste.