Hormonal and metabolic responses of hypophysectomized rats with head-down suspension

The primary purpose of this investigation was to secure select anatomical and physiological measurements from hypophysectomized rats and their sham-operated control to determine how various endocrine influences could be modified by conditions of simulated microgravity. The focal point of the study was the exercise responses after head-down suspension; however, we were also interested in obtaining insights on nonexercise-related mechanisms. Since more details and information concerning this study will be published elsewhere, we will highlight those findings which warrant further research.     

Growth hormone/IGF-I and/or resistive exercise maintains myonuclear number in hindlimb unweighted muscles

Allen, David L., Jon K. Linderman, Roland R. Roy, Richard E. Grindeland, Venkat Mukku, and V. Reggie Edgerton. Growth hormone/IGF-I and/or resistive exercise maintains myonuclearnumber in hindlimb unweighted muscles. J. Appl.Physiol. 83(5): 1857-1861, 1997.In the presentstudy of rats, we examined the role, during 2 wk ofhindlimb suspension, of growth hormone/insulin-like growth factor I(GH/IGF-I) administration and/or brief bouts of resistance exercise in ameliorating the loss of myonuclei in fibers of the soleusmuscle that express type I myosin heavy chain. Hindlimb suspensionresulted in a significant decrease in mean soleus wet weight that wasattenuated either by exercise alone or by exercise plus GH/IGF-Itreatment but was not attenuated by hormonal treatment alone. Both meanmyonuclear number and mean fiber cross-sectional area (CSA) of fibersexpressing type I myosin heavy chain decreased after 2 wk of suspensioncompared with control (134 vs. 162 myonuclei/mm and 917 vs. 2,076 µm², respectively). NeitherGH/IGF-I treatment nor exercise alone affected myonuclear number orfiber CSA, but the combination of exercise and growth-factor treatmentattenuated the decrease in both variables. A significant correlationwas found between mean myonuclear number and mean CSA across allgroups. Thus GH/IGF-I administration and brief bouts of muscle loadinghad an interactive effect in attenuating the loss of myonuclei inducedby chronic unloading.

     

Invitro responsiveness of hamster corpora lutea undergoing luteolysis to luteinizing hormone

Corpora lutea removed from pregnant hamster deprived of endogenous luteinizing hormone for varying periods were compared for their responsiveness to externally added luteinizing hormone. The corpora lutea removed on the 8th day of pregnancy exhibited a dose-dependent increase in progesterone production in response to added luteinizing hormone upto a concentration of 2.5 Μg/ml. The total progesterone synthesised by the corpora lutea decreased with increase in the duration ofin vivo luteinizing hormone deprivation. However, the hormone deprivation had to be for a minimum period of 24 h before a marked reduction in thein vitro responsiveness could be seen. Neutralisation of endogenous luteinizing hormone increased the luteal cholesterol ester concentration, whilein vitro incubation of such tissue with luteinizing hormone resulted in a marked reduction in cholesterol ester levels. Corpora lutea removed from hamsters on day 8, 15 and 16 of pregnancy when compared for their responsivenessin vitro to added luteinizing hormone showed that the luteal tissue of day 8 produced more progesterone relative to those of day 15/16. In contrast, depletion of free and esterified cholesterol increased with the increase in age of corpora lutea (from 15% on day 8 to 67% on day 16).     

A microsatellite-based consensus linkage map for species of Eucalyptus and a novel set of 230 microsatellite markers for the genus

Background  

Eucalypts are the most widely planted hardwood trees in the world occupying globally more than 18 million hectares as an important source of carbon neutral renewable energy and raw material for pulp, paper and solid wood. Quantitative Trait Loci (QTLs) in Eucalyptus have been localized on pedigree-specific RAPD or AFLP maps seriously limiting the value of such QTL mapping efforts for molecular breeding. The availability of a genus-wide genetic map with transferable microsatellite markers has become a must for the effective advancement of genomic undertakings. This report describes the development of a novel set of 230 EMBRA microsatellites, the construction of the first comprehensive microsatellite-based consensus linkage map for Eucalyptus and the consolidation of existing linkage information for other microsatellites and candidate genes mapped in other species of the genus.     

Quantification of angiogenesis in estrogen receptor-positive and negative breast carcinoma

Background

The objective of this study was to evaluate angiogenesis according to CD34 antigen expression in estrogen receptor (ER)-positive and negative breast carcinomas.

Methods

This study comprised 64 cases of infiltrating ductal carcinoma in postmenopausal women divided into two groups: Group A: ER-positive, n = 35; and Group B: ER-negative, n = 29. The anti-CD34 monoclonal antibody was used as a marker for endothelial cells. Microvessel count was carried out in 10 fields per slide using a 40× objective lens (magnification 400×). Statistical analysis of the data was performed using Student's t-test (p < 0.05).

Results

The mean number of vessels stained with the anti-CD34 antibody in the estrogen receptor-positive and negative tumors was 23.51 ± 1.15 and 40.24 ± 0.42, respectively. The number of microvessels was significantly greater in the estrogen receptor-negative tumors (p < 0.001).

Conclusion

ER-negative tumors have significantly greater CD34 antigen expression compared to ER-positive tumors.

     

Comparative analysis of the zeta-crystallin/quinone reductase gene in guinea pig and mouse

zeta-Crystallin is a novel nicotinamide adenine dinucleotide phosphate:quinone reductase, present at enzymatic levels in various tissues of different species, which is highly expressed in the lens of some hystricomorph rodents and camelids. We report here the complementary DNA (cDNA) cloning of zeta-crystallin from liver libraries in guinea pig (Cavia porcellus), where zeta-crystallin is highly expressed in the lens, and in the laboratory mouse (Mus musculus), where expression in the lens occurs only at enzymatic levels. A 5' untranslated sequence different from the one previously reported for the guinea pig lens cDNA was found in these clones. We also report the isolation of genomic clones including the complete guinea pig zeta-crystallin gene and the 5' region of this gene in mouse. These results show the presence of two promoters in the guinea pig zeta-crystallin gene, one responsible for expression at enzymatic levels and the other responsible for the high expression in the lens. The guinea pig lens promoter is not present in the mouse gene. This is the first example in which the recruitment of an enzyme as a lens crystallin can be explained by the acquisition of an alternative lens- specific promoter.      

Quantification of the magnification and distortion effects of a pediatric flexible video-bronchoscope

Background

Flexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object.

Methods

Using images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived.

Results

Magnification changes as a linear function between 100 mm (×1) and 10 mm (×9.55) and then as an exponential function between 10 mm and 3 mm (×40) from the object. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification also varies across the field of view with the central magnification being 39% greater than at the periphery of the field of view at 15 mm from the object. However, in the paediatric situation the diameter of the orifices is usually less than 10 mm and thus this limits the exposure to these peripheral limits of magnification reduction. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Distortion of geometric type ranges up to 30% at 3 mm from the object but may be as low as 5% depending on the position of the object in relation to the optic axis.

Conclusion

We conclude that the optimal working distance range is between 40 and 10 mm from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements.     

Isomerization of a single aspartyl residue of anti-epidermal growth factor receptor immunoglobulin gamma2 antibody highlights the role avidity plays in antibody activity

A new isoform of the light chain of a fully human monoclonal immunoglobulin gamma2 (IgG2) antibody panitumumab against human epidermal growth factor receptor (EGFR) was generated by in vitro aging. The isoform was attributed to the isomerization of aspartate 92 located between phenylalanine 91 and histidine 93 residues in the antigen-binding region. The isomerization rate increased with increased temperature and decreased pH. A size-exclusion chromatography binding assay was used to show that one antibody molecule was able to bind two soluble extracellular EGFR molecules in solution, and isomerization of one or both Asp-92 residues deactivated one or both antigen-binding regions, respectively. In addition, isomerization of Asp-92 showed a decrease in in vitro potency as measured by a cell proliferation assay with a 32D cell line that expressed the full-length human EGFR. The data indicate that antibodies containing either one or two isomerized residues were not effective in inhibiting EGFR-mediated cell proliferation, and that two unmodified antigen binding regions were needed to achieve full efficacy. For comparison, the potency of an intact IgG1 antibody cetuximab against the same receptor was correlated with the bioactivity of its individual antigen-binding fragments. The intact IgG1 antibody with two antigen-binding fragments was also much more active in suppressing cell proliferation than the individual fragments, similar to the IgG2 results. These results indicated that avidity played a key role in the inhibition of cell proliferation by these antibodies against the human EGFR, suggesting that their mechanisms of action are similar.