Differential scanning calorimetric study of the complexes of modified myosin subfragment 1 with ADP and vanadate or beryllium fluoride

Summary The effects of various modifications of rabbit skeletal myosin subfragment 1 on thermal denaturation of subfragment 1 in ternary complexes with Mg-ADP and orthovanadate (V_i) or beryllium fluoride (BeF_x) have been studied by differential scanning calorimetry. It has been shown that specific modifications of SH₁ group of Cys-707 by different sulfhydryl reagents, trinitrophenylation of Lys-83, and reductive methylation of lysine residues promote the decomposition of the S1·ADP·V_i complex and change the character of structural transitions of the subfragment 1 molecule induced by the formation of this complex, but they have much less or no influence on subfragment 1 thermal stability in the S1·ADP·BeF_x complex. Thus, the differential scanning calorimetric studies on modified subfragment 1 preparations reveal a significant difference between S1·ADP·V_i and S1·ADP·BeF_x complexes. It is suggested that S1·ADP·V_i and S1·ADP·BeF_x complexes represent structural analogues of different transition states of the ATPase cycle, namely the intermediate states S1^**·ADP·P_i and S1^*·ATP, respectively. It is also proposed that during formation of the S1·ADP·V_i complex the region containing both Cys-707 and Lys-83 plays an important role in the spread of conformational changes from the active site of subfragment 1 ATPase throughout the structure of the entire subfragment 1 molecule. In such a case, the effects of reductive methylation of lysine residues on the subfragment 1 structure in the S1·ADP·V_i complex are related to the modification of Lys-83.     

Stability of Th1 and Th2 populations

Using an in vitro model for the development of IFN-y-producIng(Th1) and IL-4-produclng (Th1) cells from CD4 T lymphocytesexpressing a transgenlc TCR, we show that IL-12 and IL-4 arethe most potent stimuli for the differentiation of naive T cellsto effector populations. When combinations of cytokines arepresent during T cell priming, the effect of IL-4 Is dominant.Furthermore, differentiated Th1 cells can be converted intoIL-4 producers by exposure to IL-4, but the Th2 phenotype Isnot reversible. The stability of Th2 populations may limit theability to regulate Th2-domlnant responses In pathologic situations.     

Initial validation of the SLEEP-50 questionnaire

Initial psychometric properties of the SLEEP-50 questionnaire, designed to detect sleep disorders as listed in the Diagnostic and Statistical Manual of Mental Disorders (4th ed., Text Revision), were examined. The sample consisted of 377 college students, 246 sleep patients, 32 nightmare sufferers, and 44 healthy volunteers. The internal consistency was high (Cronbach's alpha = .85); test-retest correlations fell between .65 and .89. Principal component analysis with a direct oblimin rotation revealed a factor structure that closely matched the designed structure. Sensitivity and specificity scores were promising for all sleep disorders; the agreement between all clinical diagnoses and SLEEP-50-classifications was substantial (kappa = .77). These initial findings indicate that the SLEEP-50 seems able to detect a variety of sleep disorders. The SLEEP-50 can aid in screening for common sleep disorders in the general population.     

The importance of alcohol-induced muscle disease

Alcohol-induced muscle disease (AIMD) is a composite term to describe any muscle pathology (molecular, biochemical, structural or physiological) resulting from either acute or chronic alcohol ingestion or a combination thereof. The chronic form of AIMD is arguably the most prevalent skeletal muscle disorder in the Western Hemisphere affecting more than 2000 subjects per 100,000 population and is thus much more common than hereditary disorders such as Becker or Duchenne muscular dystrophy. Paradoxically, most texts on skeletal myopathies or scientific meetings covering muscle disease have generally ignored chronic alcoholic myopathy. The chronic form of AIMDs affects 40–60% of alcoholics and is more common than other alcohol-induced diseases, for example, cirrhosis (15–20% of chronic alcoholics), peripheral neuropathy (15–20%), intestinal disease (30–50%) or cardiomyopathy (15–35%). In this article, we summarise the pathological features of alcoholic muscle disease, particularly biochemical changes related to protein metabolism and some of the putative underlying mechanisms. However, the intervening steps between the exposure of muscle to ethanol and the initiation of the cascade of responses leading to muscle weakness and loss of muscle bulk remain essentially unknown. We argue that alcoholic myopathy represents: (a) a model system in which both the causal agent and the target organ is known; (b) a myopathy involving free-radical mediated pathology to the whole body which may also target skeletal muscle and (c) a reversible myopathy, unlike many hereditary muscle diseases. A clearer understanding of the mechanisms responsible for alcoholic myopathy is important since some of the underlying pathways may be common to other myopathies. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pituitary pathology in erdheim-chester disease

Pituitary morphologic changes in patients with Erdheim-Chester disease have not been described in detail. We report here the histologic and immunohistochemical findings in the autopsy obtained pituitary of a 35-yr-old woman with extensively disseminated Erdheim-Chester disease. The posterior lobe was completely replaced by xanthogranulomatous infiltrates, providing an explanation for the patient’s diabetes insipidus. The anterior lobe was intact and immunohistochemistry demonstrated expression of GH, TSH, FSH, LH, and alpha subunit within the normal range. A clinically observed decrease of anterior pituitary function was interpreted as hypothalamic in origin due to massive destruction of the hypophysial stalk and compression of the hypothalamus. Prolactin immunoreactive cells were numerous, consistent with the view that prolactin cell hyperplasia resulted from the loss of hypothalamic dopaminergic inhibition. Massive Crooke’s hyalinization in the ACTH-producing cells was considered unrelated to Erdheim-Chester disease and was the consequence of treatment with pharmacologic doses of glucocorticoid hormones. It can be concluded that prolactin cell hyperplasia may be the only finding in the adenohypophysis of patients with disseminated Erdheim-Chester disease. It appears that in our patient the clinically apparent anterior hypopituitarism was not due to the lack of storage but rather to insufficient release of adenohypophysial hormones caused by the defect in hypothalamic regulation.     

Effect of hydroxyapatite/tricalcium-phosphate coating on osseointegration of plasma-sprayed titanium alloy implants

This study determined the effects of a plasma-sprayed hydroxyapatite/tricalcium phosphate (HA/TCP) coating on osseointegration of plasma-sprayed titanium alloy implants in a lapine, distal femoral intramedullary model. The effects of the HA/TCP coating were assessed at 1, 3, and 6 months after implant placement. The HA/TCP coating significantly increased new bone apposition onto the implant surfaces at all time points. The ceramic coating also stimulated intramedullary bone formation at the middle and distal levels of the implants. Fluorescent bone labeling indicated that new bone formation occurred primarily during the first 3 months after implantation, with comparatively little activity detected in the latter stages of the study. There was no associated increase in pullout strength at either 3 or 6 months; however, post-pullout evaluation of the implants indicated that the HA/TCP coating itself was not the primary site of construct failure. Rather, failure was most commonly observed through the periprosthetic osseous struts that bridged the medullary cavity. The demonstrated osteoconductive activity of HA/TCP coating on plasma-sprayed titanium alloy implant surfaces may have considerable clinical relevance to early host-implant interactions, by accelerating the establishment of a stable prosthesis-bone interface.     

Decay-accelerating factor in the cardiomyocytes of normal individuals and patients with myocardial infarction

Summary The presence of decay-accelerating factor (DAF) was clearly demonstrated on the surface of normal cardiomyocytes. In patients who had died of myocardial infarction (MI) cardiomyocytes displayed different appearances: outside the ischaemically damaged region the myocytes showed no significant variations in DAF expression when compared with controls without MI. Within myocardial zones damaged by ischaemia, however, apparently normal myocytes showed large gaps in surface staining of DAF or formed clusters which were entirely devoid of reactivity with anti-DAF antibodies. The number of DAF-deficient myocytes increased with the extent of necrosis and also with the number of days between onset of MI and death. Even though injury to myocytes is to a large extent related to anoxia and to the presence of free oxygen radicals, the complement system also appears to be involved; DAF may have protective functions against complement-mediated injury. We speculate that phospholipase may be involved in the removal of DAF from the cardiomyocyte surface.This work was supported in part by grant no. 3.157.88 from the Swiss National Foundation for Scientific Research and a contribution from Sandoz Ltd. Pharma Division, Basel     

Detection of Borrelia lonestari,putative agent of southern tick-associated rash illness,in white-tailed deer (Odocoileus virginianus) from the southeastern United States

To determine if white-tailed deer may serve as a reservoir host for Borrelia lonestari, we used a nested PCR for the Borrelia flagellin gene to evaluate blood samples collected from deer from eight southeastern states. Seven of 80 deer (8.7%) from 5 of 17 sites (29.4%) had sequence-confirmed evidence of a B. lonestari flagellin gene by PCR, indicating that deer are infected with B. lonestari or another closely related Borrelia species. Our findings expand the known geographic range of B. lonestari and provide the first evidence of this organism in a vertebrate other than humans.     

Integrative repair of cartilage with articular and nonarticular chondrocytes

Articular chondrocytes can synthesize new cartilaginous matrix in vivo that forms functional bonds with native cartilage. Other sources of chondrocytes may have a similar ability to form new cartilage with healing capacity. This study evaluates the ability of various chondrocyte sources to produce new cartilaginous matrix in vivo and to form functional bonds with native cartilage. Disks of articular cartilage and articular, auricular, and costal chondrocytes were harvested from swine. Articular, auricular, or costal chondrocytes suspended in fibrin glue (experimental), or fibrin glue alone (control), were placed between disks of articular cartilage, forming trilayer constructs, and implanted subcutaneously into nude mice for 6 and 12 weeks. Specimens were evaluated for neocartilage production and integration into native cartilage with histological and biomechanical analysis. New matrix was formed in all experimental samples, consisting mostly of neocartilage integrating with the cartilage disks. Control samples developed fibrous tissue without evidence of neocartilage. Ultimate tensile strength values for experimental samples were significantly increased (p < 0.05) from 6 to 12 weeks, and at 12 weeks they were significantly greater (p < 0.05) than those of controls. We conclude that articular, auricular, and costal chondrocytes have a similar ability to produce new cartilaginous matrix in vivo that forms mechanically functional bonds with native cartilage.