The ultrastructure of topical cutaneous calcinosis

Summary Mineralized plaques, which develop at the site of repeated subcutaneous injections of 100 g KMnO₄/0.2 H₂O in rats, were investigated by electron microscopy. The newly formed, delineated, white plaque tissue at the injection site consisted of numerous, mostly unaltered fibroblasts and collagen fibers, without participation of inflammatory cells. Some signs of cell injury were found in the center of the lesions. Numerous, irregularly distributed, small, mineralized foci were seen near the fibroblasts. These were formed by aggregation of small needle-like units (50 Å in diameter and 0.05–2.0 m long). These needle-shaped units were found either in vesicular, cell derived structures, considered to be shed cell processes or cell fragments, or on collagen fibers. Intramitochondrial deposits of such needle-like units were seen frequently. Fusion of smaller mineralized foci to larger plaques occured and then needle-shaped units were seen at the periphery of the electron-dense lesions. Hypotheses concerning the mechanism of experimental cutaneous calcinosis (soft tissue mineralization) are discussed and related to the findings of this study. Probable intracellular crystal deposition and mineralization in cell-derived structures were shown for the first time in topical cutaneous calcinosis.     

Glucagon-like peptide 1: evolution of an incretin into a treatment for diabetes

Glucagon-like peptide 1 (GLP-1) is a product of proglucagon that is secreted by specialized intestinal endocrine cells after meals. GLP-1 is insulinotropic and plays a role in the incretin effect, the augmented insulin response observed when glucose is absorbed through the gut. GLP-1 also appears to regulate a number of processes that reduce fluctuations in blood glucose, such as gastric emptying, glucagon secretion, food intake, and possibly glucose production and glucose uptake. These effects, in addition to the stimulation of insulin secretion, suggest a broad role for GLP-1 as a mediator of postprandial glucose homeostasis. Consistent with this role, the most prominent effect of experimental blockade of GLP-1 signaling is an increase in blood glucose. Recent data also suggest that GLP-1 is involved in the regulation of beta-cell mass. Whereas other insulinotropic gastrointestinal hormones are relatively ineffective in stimulating insulin secretion in persons with type 2 diabetes, GLP-1 retains this action and is very effective in lowering blood glucose levels in these patients. There are currently a number of products in development that utilize the GLP-1-signaling system as a mechanism for the treatment of diabetes. These compounds, GLP-1 receptor agonists and agents that retard the metabolism of native GLP-1, have shown promising results in clinical trials. The application of GLP-1 to clinical use fulfills a long-standing interest in adapting endogenous insulinotropic hormones to the treatment of diabetes.     

STING Millennium Suite: integrated software for extensive analyses of 3d structures of proteins and their complexes

Background  

The integration of many aspects of protein/DNA structure analysis is an important requirement for software products in general area of structural bioinformatics. In fact, there are too few software packages on the internet which can be described as successful in this respect. We might say that what is still missing is publicly available, web based software for interactive analysis of the sequence/structure/function of proteins and their complexes with DNA and ligands. Some of existing software packages do have certain level of integration and do offer analysis of several structure related parameters, however not to the extent generally demanded by a user.     

Granule-bound starch synthase: structure, function, and phylogenetic utility

Interest in the use of low-copy nuclear genes for phylogenetic analyses of plants has grown rapidly, because highly repetitive genes such as those commonly used are limited in number. Furthermore, because low- copy genes are subject to different evolutionary processes than are plastid genes or highly repetitive nuclear markers, they provide a valuable source of independent phylogenetic evidence. The gene for granule-bound starch synthase (GBSSI or waxy) exists in a single copy in nearly all plants examined so far. Our study of GBSSI had three parts: (1) Amino acid sequences were compared across a broad taxonomic range, including grasses, four dicotyledons, and the microbial homologs of GBSSI. Inferred structural information was used to aid in the alignment of these very divergent sequences. The informed alignments highlight amino acids that are conserved across all sequences, and demonstrate that structural motifs can be highly conserved in spite of marked divergence in amino acid sequence. (2) Maximum-likelihood (ML) analyses were used to examine exon sequence evolution throughout grasses. Differences in probabilities among substitution types and marked among-site rate variation contributed to the observed pattern of variation. Of the parameters examined in our set of likelihood models, the inclusion of among-site rate variation following a gamma distribution caused the greatest improvement in likelihood score. (3) We performed cladistic parsimony analyses of GBSSI sequences throughout grasses, within tribes, and within genera to examine the phylogenetic utility of the gene. Introns provide useful information among very closely related species, but quickly become difficult to align among more divergent taxa. Exons are variable enough to provide extensive resolution within the family, but with low bootstrap support. The combined results of amino acid sequence comparisons, maximum-likelihood analyses, and phylogenetic studies underscore factors that might affect phylogenetic reconstruction. In this case, accommodation of the variable rate of evolution among sites might be the first step in maximizing the phylogenetic utility of GBSSI.      

The function of communities in protein interaction networks at multiple scales

Background  

If biology is modular then clusters, or communities, of proteins derived using only protein interaction network structure should define protein modules with similar biological roles. We investigate the link between biological modules and network communities in yeast and its relationship to the scale at which we probe the network.     

Air trapping on chest CT is associated with worse ventilation distribution in infants with cystic fibrosis diagnosed following newborn screening

Background

In school-aged children with cystic fibrosis (CF) structural lung damage assessed using chest CT is associated with abnormal ventilation distribution. The primary objective of this analysis was to determine the relationships between ventilation distribution outcomes and the presence and extent of structural damage as assessed by chest CT in infants and young children with CF.

Methods

Data of infants and young children with CF diagnosed following newborn screening consecutively reviewed between August 2005 and December 2009 were analysed. Ventilation distribution (lung clearance index and the first and second moment ratios [LCI, M₁/M₀ and M₂/M₀, respectively]), chest CT and airway pathology from bronchoalveolar lavage were determined at diagnosis and then annually. The chest CT scans were evaluated for the presence or absence of bronchiectasis and air trapping.

Results

Matched lung function, chest CT and pathology outcomes were available in 49 infants (31 male) with bronchiectasis and air trapping present in 13 (27%) and 24 (49%) infants, respectively. The presence of bronchiectasis or air trapping was associated with increased M₂/M₀ but not LCI or M₁/M₀. There was a weak, but statistically significant association between the extent of air trapping and all ventilation distribution outcomes.

Conclusion

These findings suggest that in early CF lung disease there are weak associations between ventilation distribution and lung damage from chest CT. These finding are in contrast to those reported in older children. These findings suggest that assessments of LCI could not be used to replace a chest CT scan for the assessment of structural lung disease in the first two years of life. Further research in which both MBW and chest CT outcomes are obtained is required to assess the role of ventilation distribution in tracking the progression of lung damage in infants with CF.     

Comparative analysis of ACTH and corticosterone sampling methods in rats

A frequently debated question for studies involving the measurement of stress hormones in rodents is the optimal method for collecting blood with minimal stress to the animal. Some investigators prefer the implantation of indwelling catheters to allow for frequent sampling. Others argue that the implantation of a catheter creates a chronic stress to the animal that confounds stress hormone measures and therefore rely on tail vein sampling. Moreover, some investigators measure hormones in trunk blood samples obtained after anesthesia, a practice that may itself raise hormone levels. To address these controversies, we 1) compared plasma ACTH and corticosterone (Cort) concentrations in pre- and poststress rat blood samples obtained via previously implanted vena cava catheters, tail vein nicks, or clipping the tip off the tail and 2) compared plasma ACTH and Cort in rat blood samples obtained by decapitation with and without anesthesia. Rats sampled via indwelling catheters displayed lower prestress ACTH levels than those sampled by tail vein nick if the time to acquire samples was not limited; however, elevated basal ACTH was not observed in samples obtained by tail clip or tail nick when the samples were obtained within 3 min. Baseline Cort levels were similar in all groups. After restraint stress, the profile of the plasma ACTH and Cort responses was not affected by sampling method. Decapitation with prior administration of CO2 or pentobarbital sodium increased plasma ACTH levels approximately 13- and 2-fold, respectively, when compared with decapitation without anesthesia. These data indicate that tail vein nicking, tail clipping, or indwelling venous catheters can be used for obtaining plasma for ACTH and Cort during acute stress studies without confounding the measurements. However, the elevation in basal ACTH seen in the tail vein nick group at baseline suggests that sampling needs to be completed rapidly (<3 min) to avoid the initiation of the pituitary stress response. Death by CO2 and pentobarbital sodium injection before trunk blood collection cause significant stress to animals, as reflected in the elevated plasma ACTH levels. These results support the use of either chronic vascular cannulas or sampling from a tail vein. However, collection of blood under pentobarbital sodium or CO2 anesthesia is likely to confound the results of stress studies when ACTH is an important endpoint.     

Weight loss through ileal transposition is accompanied by increased ileal hormone secretion and synthesis in rats

Bariatric surgeries, such as gastric bypass, result in dramatic and sustained weight loss that is usually attributed to a combination of gastric volume restriction and intestinal malabsorption. However, studies parceling out the contribution of enhanced intestinal stimulation in the absence of these two mechanisms have received little attention. Previous studies have demonstrated that patients who received intestinal bypass or Roux-en-Y surgery have increased release of gastrointestinal hormones. One possible mechanism for this increase is the rapid transit of nutrients into the intestine after eating. To determine whether there is increased secretion of anorectic peptides produced in the distal small intestine when this portion of the gut is given greater exposure to nutrients, we preformed ileal transpositions (IT) in rats. In this procedure, an isolated segment of ileum is transposed to the jejunum, resulting in an intestinal tract of normal length but an alteration in the normal distribution of endocrine cells along the gut. Rats with IT lost more weight (P < 0.05) and consumed less food (P < 0.05) than control rats with intestinal transections and reanastomosis without transposition. Weight loss in the IT rats was not due to malabsorption of nutrients. However, transposition of distal gut to a proximal location caused increased synthesis and release of the anorectic ileal hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY; P < 0.01). The association of weight loss with increased release of GLP-1 and PYY suggests that procedures that promote gastrointestinal endocrine function can reduce energy intake. These findings support the importance of evaluating the contribution of gastrointestinal hormones to the weight loss seen with bariatric surgery.