Effects of glucocorticoids on the rabbit carotid body

Weekly intramuscular injections of slow-release, depot methyl prednisolone to 15 adult Dutch rabbits did not bring about an increase in the volume of their carotid bodies. However, they caused swelling of chief cells with discrete areas of pallor in the cytoplasm. Factors responsible for these changes appear to be increased storage of catecholamines and an increased number of swollen mitochondria.     

Evaluation of serum chemistry values associated with avian malaria infections in African black-footed penguins (Spheniscus demersus)

The value profiles of 5 intracellular enzymes, 15 metabolites (with 2 associated ratios), and 3 electrolytes were monitored over time in 9 captive-reared African black-footed penguins (Spheniscus demersus) with different avian malaria clinical status: uninfected, subclinically infected, and clinically infected with fatal outcome. Fatal infections were caused byPlasmodium relictum. Numerous schizonts were visible in the lungs, liver, spleen, and interstitial tissue of the kidneys. The feference ranges of 23 serum clinical chemistry parameters and 2 ratios were established forS. demersus. The mean values obtained for 8 of 23 parameters of the infected penguins were signficantly different from those recorded for the uninfected birds, indicating impaired renal function, hepatic dysfunction, and nonspecific tissue damage related to the infestation with exoerythrocytic schizonts. Analysis of sensitivity, specificity, and negative and positive predictive values (PPVs) showed that gamma-glutamyltranspeptidase (GGTP), alanine aminotransferase (ALT), and creatinine reached PPVs and a specificity over 57% for avian malaria infections in penguins. Creatinine, ALT, and GGTP values should be consulted in evaluation of the clinical malaria status ofS. demersus.     

Distribution of alleles of the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism in familial spina bifida

Spina bifida cystica (SB) is one of the most common and disabling of birth defects. Folic acid supplementation in mothers during the periconceptional period has been shown to prevent more than 70% of neural tube defects (NTD) including SB. However, the mechanism is unknown. We tested a series of multicase SB families in which 224 individuals were genotyped and a group of 215 unrelated unaffected (external) control individuals for association of SB with the T allele of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism that produces a heat-labile enzyme protein. The data were analyzed using first the transmission/disequilibrium test (TDT) and second a modified case-control study design with Monte Carlo sampling methods. No association of SB with the MTHFR T allele was found by either method. Presently, association between SB and the T allele has been found in four studies, a Dutch study, an Irish study, a North American study, and an Italian study. But no association was found in four other studies, a British study, a French study, a Turkish study, and a German study. A California population-based study found only modestly increased risk of SB with this allele that was not significant at the P < 0.05 level. The present study finds no evidence of the association. Only one other study, the German study, has used TDT analysis. The present study is the first to use a modified case-control study design with Monte Carlo sampling methods to test this association. Thus, it appears that the MTHFR T allele is a risk factor for SB in some populations but not others. Major genetic risk factors for folate-related SB remain to be found.     

Pathology of chronic constipation in pediatric and adult coloproctology.

In colonic motility disorders, a pathohistological diagnosis based solely on formalin-fixed gut is often inconclusive. Classical histological techniques or immunohistochemistry represent a static staining. In contrast, native tissue submitted to enzyme histochemistry provides functional information about the effectiveness of the cellular performance. Routinely, a complementary set of reactions is performed and includes acetylcholinesterase (AChE), lactic and succinic dehydrogenase, as well as nitroxide synthase reactions. In this monograph, the whole spectrum of different anomalies of the colonic wall is illustrated in a systematic fashion: Hirschsprung's disease is characterized by an increase in AChE activity of parasympathetic nerve fibers of the rectosigmoid. In ultrashort Hirschsprung's disease, only enzyme histochemistry renders a reliable diagnosis possible in biopsies of the anal ring. Aganglionosis of the musculus corrugator cutis ani shows a localized increase of AChE activity in nerve fibers, similar to Hirschsprung's disease, not detectable in conventional histology. Immaturity, hypoganglionosis and neuronal dysganglionosis can be clearly recognized in dehydrogenase reactions. Enzyme histochemical reactions are complemented by picrosirius red staining for assessment of the collagen texture of the muscularis propria. Absence or intertenial interruption of the continuous connective tissue layer between circular and longitudinal muscle of the muscularis propria has been termed aplastic or atrophic desmosis, respectively. Many of the entities described are also observed in adults. Atrophic hypoganglionosis or atrophic desmosis with loss of the myenteric plexus connective tissue fascia is implied as a frequent cause of chronic constipation in adults. The essential contribution of a functional histopathological technique towards a reliable diagnosis of gut dysfunction in native tissue is extensively demonstrated in great detail in more than two hundred figures.     

The thickness of the alveolar capillary wall in guinea-pigs at high and low altitude

The thickness of the alveolar-capillary wall was measured in the lungs of seven guinea-pigs born and living at La Raya, in the Peruvian Andes, at an altitude of 4200 m and in seven sea-level representatives of the same species. This was achieved by carrying out morphometric studies on electron micrographs to obtain the so-called arithmetic and harmonic mean thicknesses. The arithmetic mean thickness was always the larger, this being due to the greater emphasis which the technique employed places on the copious amounts of connective tissue in the interstitial space of the alveolar capillary wall in this species. These thicker portions of the alveolar wall are not concerned with gaseous diffusion. The harmonic mean thickness probably gives a more physiologically realistic estimate of the magnitude of the diffusion barrier to oxygen. This proved to be smaller in the animals from high altitude and may facilitate diffusion of oxygen from alveolar spaces to blood, thus making less steep the "oxygen cascade" from inspired air to mitochondria.     

Saethre‐Chotzen syndrome: Notable intrafamilial phenotypic variability in a large family with Q28X TWIST mutation

Saethre‐Chotzen syndrome is an autosomal dominant disease characterized by craniosynostosis, ptosis, and limb and external ear abnormalities. Variable expressivity is a well‐known phenomenon in this disorder. A large Indian family has been recently identified as carrying a nonsense TWIST mutation (Q28 X) in 17 members, of whom 16 were examined in detail. Only 4 (25%) of the patients showed patent craniostenosis, namely, oxycephaly. The penetrance of craniosynostosis in this family is lower than previously reported in the literature. Fifteen patients (93%) had moderate to severe ptosis. Minor limb and external ear abnormalities were present in most patients. Eyelid features were the hallmark of the disease for 12 members of the family, suggesting that mutations in TWIST may lead to a phenotype with mainly palpebral features and no craniostenosis. The clinical analysis of this large family clearly illustrates the significant variable expressivity, probably related to haploinsufficiency because of the TWIST mutation. This phenotypic variability remains unclear but could be the result of modifier genes and/or genetic background effect, as noticed previously in the transgenic twist‐null heterozygous mice. © 2002 Wiley‐Liss, Inc.     

New polymers with coronand structure

New polymers with an alternating sequence of non-polar aliphatic chains and coronands were synthesized via Diels-Alder addition polymerization of bis(2-pyrones) with bismaleimides; number-average molecular weight M?_n: 18000 (vapour pressure osmometry), glass transition temperature T?_g: 250°C. The chemical structures of these polymers are supported by NMR spectra and model reactions. The reaction mechanism is discussed.