Effect of coitus on serum levels of testosterone and LH in male and female rabbits.

Levels of testosterone (T) and LH in the peripheral serum of male and female rabbits were measured and compared following coitus. Blood was collected by heart puncture from restrained, unanesthetized animals of both sexes. In male rabbits, basal serum T levels were highly variable, ranging from 131 to 12,149 pg/ml, and if low preceding coitus they tended to rise; whereas, if high, they usually dropped as they did in nonmated males subjected to repeated heart punctures. In contrast, basal serum LH levels in males were quite constant (mean +/- SE, 1993 +/- 152 pg/ml) and were not significantly altered after coitus unless blood T levels had been drastically lowered by two priming doses of estradiol benzoate. In intact does, on the other hand, copulation which resulted in ovulation induced an approximately 20-fold increase in serum LH concentration which was sustained for about 4 hr. Postcoital elevations in serum LH also occurred in estrogen-primed intact and estrogen-primed ovariectomized does. Under the conditions of our experiments, the parallel elevations in serum LH and T observed postcoitally in the female rabbit could not be demonstrated in the male.     

Programmed Instruction: New Bottle for Rediscovered Wine

Programmed instruction is attracting attention at all educational levels. While this approach is new, the educational principles it incorporates are well established: instructional goals are defined in advance, the content is meticulously organized, active student participation is demanded, immediate feedback is provided to students, and each instructional unit is subjected to testing and revision. With its established effectiveness as a vehicle for introducing new topics, and for providing remedial and supplementary instruction, it can free the medical teacher to devote his time to matters which are more deserving of his attention, such as identifying and responding to individual student needs, exploring complex concepts, and working directly with students to provide a model and critical supervision. A more important potential contribution of programming may be that it has reminded us of sound educational precepts which deserve our attention in all forms of instruction.     

Glycan characterization of the NIST RM monoclonal antibody using a total analytical solution: From sample preparation to data analysis

Glycosylation is an important attribute of biopharmaceutical products to monitor from development through production. However, glycosylation analysis has traditionally been a time-consuming process with long sample preparation protocols and manual interpretation of the data. To address the challenges associated with glycan analysis, we developed a streamlined analytical solution that covers the entire process from sample preparation to data analysis. In this communication, we describe the complete analytical solution that begins with a simplified and fast N-linked glycan sample preparation protocol that can be completed in less than 1 hr. The sample preparation includes labelling with RapiFluor-MS tag to improve both fluorescence (FLR) and mass spectral (MS) sensitivities. Following HILIC-UPLC/FLR/MS analyses, the data are processed and a library search based on glucose units has been included to expedite the task of structural assignment. We then applied this total analytical solution to characterize the glycosylation of the NIST Reference Material mAb 8761. For this glycoprotein, we confidently identified 35 N-linked glycans and all three major classes, high mannose, complex, and hybrid, were present. The majority of the glycans were neutral and fucosylated; glycans featuring N-glycolylneuraminic acid and those with two galactoses connected via an α1,3-linkage were also identified.     

Chirality of azelastine and flezelastine: Investigation of their enantiomers

The racemic phthalazinone derivatives azelastine and flezelastine were resolved via formation of diastereomeric salts and fractional crystallization thereof. The optical purity of the enantiomers was checked by HPLC. Pharmacological investigations in vitro and in vivo related to antiallergic/antiasthmatic activity revealed some stereospecific differences. However, chiral discrimination could not be observed with regard to overall activity of azelastine and flezelastine. © 1993 Wiley-Liss, Inc.     

The influence of environmental variables on the density of larval lampreys in different seasons

Summary The objective of the study was to identify a subset of a set of twenty environmental variables which could explain variations in the density of larval lampreys (Geotria australis) in a south-western Australian stream. Generalised linear modelling, assuming Poisson distributions for the larval counts, led to a different model for each of the four seasons, with variations in larval density being explained in each season by a combination of between five and eight environmental variables. The influence of stream region also had to be taken into account in the model for winter.Four environmental variables (substrate organic material and chlorophyll a, macrophyte roots and low-angle shading) were present in three of the four seasonal models. A further six variables (water depth, substrate depth and profile, medium-sized sands, light intensity, and the presence of an eddy) were each found useful for two models. Two variables (current velocity and substrate profile) were each retained in one model. Eight of the twenty variables were not required for any of the seasonal models. The importance of organic material, shade, eddies, current velocity substrate particle size and a sufficient depth of substrate in our models agree with the largely subjective assessments of larval lamprey habitats made in the field by many previous workers for other lamprey species in diverse geographical localities.Our finding that larval density increased with increases in organic material and unicellular algae in the substrate and with shade, contrasts with the results of a different model based on data collected in a northern European stream. These differences can be related to our use of a more rigorous and comprehensive sampling regime and a more appropriate form of statistical analysis.     

Loss of H-2Kk gene product(s) from an AKR spontaneous leukaemia

Serological absorption analyses and immunochemical studies of the H-2 antigenic specificities on the AKR (H-2^k) spontaneous leukaemia K36 have been performed. The results confirm the absence of the H-2K^k gene product from the cell surface and from detergent solubilised tumour cells. A genetic mechanism is considered for this phenotypic alteration.