Correlation analysis of twin data with repeated measures based on generalized estimating equations

Repeated measures allow additional tests of common assumptions in twin correlation analysis. Analysis of log serum triglyceride level in NHLBI male twins using generalized estimating equations disclosed that the mean and variance shifted across exams, presumably because of changes in laboratory practice.     

The HELLP syndrome: its association with unexplained elevation of MSAFP and MShCG in the second trimester

In this study, we examined the relationship between concentrations of maternal serum alpha-fetoprotein (MSAFP) and maternal serum human chorionic gonadotropin (MShCG) in the second trimester and the haemolysis, elevated liver enzymes, low platelet count (HELLP) syndrome. The concentrations of both serum markers, expressed in multiples of the median (MOM), in 16 women with the HELLP syndrome were compared with those in 10443 women without this syndrome who were screened for Down's syndrome and neural tube defects. All the women with a singleton pregnancy and a known pregnancy outcome were included in this study. At a cut-off level of 2.5 MOM, 37.5 per cent of the pregnancies with the HELLP syndrome had an elevated MShCG level, compared with 4.8 per cent in the whole population (P < 0.0001). 12.5 per cent of the women with the HELLP syndrome had an elevated MSAFP level, compared with 1.3 per cent in the whole population (P < 0.025). Women with a combined elevation of MSAFP and MShCG levels (0.3 per cent of the screened population) had a 47 time greater risk of developing the HELLP syndrome than the others (P < 0.01). The HELLP syndrome should be taken into account in the case of unexplained elevated levels of MShCG and MSAFP, especially in the rare event of combined elevation of both markers.     

Exhaled nitric oxide is not elevated in the inflammatory airways diseases of cystic fibrosis and bronchiectasis

Airways inflammation has been associated with increased nitric oxide (NO) in the exhaled breath. It was, therefore, questioned whether exhaled NO could act as an indicator of the severity of airways inflammation in the chronic suppurative lung diseases cystic fibrosis (CF) and bronchiectasis. NO levels in a single exhalation were measured using a chemiluminescence analyser. Thirty-six patients with CF and 16 with bronchiectasis were studied and compared with 22 normal subjects and 35 asthmatic patients. All subjects were nonsmokers and all measurements were made when patients were clinically stable. In addition, exhaled NO was measured in 10 CF patients at the time of onset of an acute infective exacerbation and followed for 7 days during the treatment of the exacerbation in eight of the 10 patients. No significant differences were found in NO levels in patients with CF or bronchiectasis compared with normals (median 4.0, 5.5 and 4.4 parts per billion (ppb), respectively), but all were lower than in asthma patients (10.4 ppb). The NO levels in the CF patients at time of exacerbation were not increased and did not change during treatment. These data show that nitric oxide levels in the exhaled breath of patients with chronic suppurative lung diseases, in contrast to asthma, are not elevated, despite the presence of substantial airways inflammation. Possible explanations include poor diffusion of nitric oxide across increased and viscous airway secretions, removal of nitric oxide by reaction with reactive oxygen species in the inflamed environment and failure of upregulation of epithelial inducible nitric oxide synthase in chronic suppurative conditions.     

Biostereometric quantification of clinical denture tooth wear

In this study the wear of mandibular acrylic resin teeth opposed by porcelain maxillary teeth arranged in a lingualized occlusal scheme over a period of 3 years was measured. Six edentulous subjects received complete dentures as above and with three baseline markers of amalgam. At yearly intervals casts were made of the mandibular occlusal surfaces, including markers, and plotted by stereophotogrammetry. Volumetric loss of material was quantifiable. Ranges of 0.62-3.33 mm3/mm2 on the left side and 0.71-1.64 mm3/mm2 on the right were recorded. Friedman two-way ANOVA test indicated significant wear on teeth 35, 36, 45 and 46 but not on 34 and 44. A one-sided chewer displayed greater wear on the contralateral side, a finding difficult to explain.     

Biosynthesis and conformational state of 17-kDa and 27-kDa N-terminal fragments of elongation factor EF-2 in solution

N-Terminal fragments of the rat liver elongation factor EF-2 containing 162 (17 kDa) and 244 (27 kDa) amino acid residues of 857 (95 kDa) residues of the native protein were synthesized in E. coli cells and in a wheat germ cell-free translation system, and their conformations were studied. Both fragments were synthesized as inclusion bodies (nonspecific molecular aggregates). The conformations of the fragments in a solution were studied at neutral pH values by CD, fluorescence spectroscopy, scanning microcalorimetry, viscosimetry, gel-filtration, limited proteolysis, and interaction with monospecific anti-EF-2 antibodies and GroEL/ES molecular chaperone. Under nondenaturing conditions, both fragments existed in a solution as associates within a broad range of molecular masses, contained a considerable amount of elements of the intramolecular secondary structure, and represented globules without rigid tertiary structure (molten globules). A rigid tertiary structure was not formed even after the interaction of the fragments with the GroEL/ES molecular chaperone, thus indicating that the C-terminal fragment is essential for the formation of the rigid tertiary structure. Both fragments contained conformational antigenic determinants similar to those in the whole protein; i.e., despite the absence of the rigid tertiary structure, the fragments contained elements whose structure was similar to that of the corresponding regions in the whole protein.     

Drug-induced alterations of the hypothalamus-hypophysis axis

Omitting hormonal variations caused by other drugs already objects of research, the behaviour pattern of GH, PRL, TSH, following acute administration of cimetidine, nomifensine, domperidone has been considered in normal subjects, in patients with pituitary non-secreting and PRL-secreting adenomas and in patients with amenorrhea-galactorrhea syndrome without evidence of adenoma. The results confirm the influence which drugs employed in the therapy of non-endocrine diseases provide a way to alter the functions of the hypothalamus, sometimes relatively specifically, and the secretion of pituitary hormones provides us with a possibility of analyzing the CNS output.     

Use of the swarming phenomenon for the purpose of isolating pure cultures of salmonellae from feces. I

The authors elaborated and tested a number of elective-differential media for swarming of salmonellae. When pure cultures of Proteus, E. coli and salmonellae were seded on these media the latter exeeded the rest of enteric bacteria by the intensity of swarming. In the capacity of saprophyte inhibitors the most effective were media with the addition of penicillin and sodium selenite. Satisfactory results were obtained on the mentioned media in isolation of salmonellae from the artificially contaminated feces by the method of swarming     

Postural adaptations to workbench modifications in standing workers

Surveys have shown that many workers operate under conditions that require constrained standing. The aim of this study was to investigate postural adaptations in constrained standing to facilitate the development of design guidelines for standing workspaces. Standing postures were observed in six different workspaces that were designed using combinations of task distance (which was either constrained or unconstrained) and foot position (which was constrained, unconstrained or employed a footrest). Subjects at work were recorded stereophotogrammetrically and postural variables were obtained in three dimensions. Postural adaptation to increased task distance was found to be characterized by increased trunk flexion and increased hip flexion while adaptation to close work was found to be characterized by increased neck flexion and increased thoracic kyphosis. Constrained foot position resulted in increased hip flexion accompanied by increased plantar flexion. Although use of the footrest resulted in some reduced lumbar lordosis, it increased trunk flexion and was not associated with significantly less discomfort than any of the other workspaces.