Combined myofibrillar and mitochondrial creatine kinase deficiency impairs mouse diaphragm isotonic function

Creatine kinase (CK) is an enzyme central to cellular high-energy phosphate metabolism in muscle. To characterize the physiological role of CK in respiratory muscle during dynamic contractions, we compared the force-velocity relationships, power, and work output characteristics of the diaphragm (Dia) from mice with combined myofibrillar and sarcomeric mitochondrial CK deficiency (CK[-/-]) with CK-sufficient controls (Ctl). Maximum velocity of shortening was significantly lower in CK[-/-] Dia (14.1 +/- 0.9 Lo/s, where Lo is optimal fiber length) compared with Ctl Dia (17.5 +/- 1.1 Lo/s) (P < 0.01). Maximum power was obtained at 0.4-0.5 tetanic force in both groups; absolute maximum power (2,293 +/- 138 W/m2) and work (201 +/- 9 J/m2) were lower in CK[-/-] Dia compared with Ctl Dia (2,744 +/- 146 W/m2 and 284 +/- 26 J/m2, respectively) (P < 0.05). The ability of CK[-/-] Dia to sustain shortening during repetitive isotonic activation (75 Hz, 330-ms duration repeated each second at 0.4 tetanic force load) was markedly impaired, with CK[-/-] Dia power and work declining to zero by 37 +/- 4 s, compared with 61 +/- 5 s in Ctl Dia. We conclude that combined myofibrillar and sarcomeric mitochondrial CK deficiency profoundly impairs Dia power and work output, underscoring the functional importance of CK during dynamic contractions in skeletal muscle.     

Minimal dissipation theory and shear bands in biaxial tests

True biaxial tests of granular materials are investigated by applying the principle of minimal dissipation and comparing to two dimensional contact dynamics simulations. It is shown that the macroscopic steady state manifested by constant stress ratio and constant volume is the result of the ever changing microscopic structure which minimizes the dissipation rate. The shear band angle in the varying shear band structures is found to be constant. We also show that introducing friction on the walls reduces the degeneracy of the optimal shear band structures to one for a wide range of parameters which gives a non-constant stress ratio curve with varying aspect ratio that can be calculated.     

MMP and TIMP expression pattern in pleural effusions of different origins

The matrix metalloproteinases (MMP) are proteolytic enzymes that are essentially involved in the turnover of the extracellular matrix (ECM). Their activity is counterbalanced by specific antagonists, the tissue inhibitors of metalloproteinases (TIMP). In this study, we sought to analyze the expression of MMP and TIMP isoforms in pleural effusions from 88 patients. We compared MMP and TIMP isoform expression in transudates (n = 21) and exudates (n = 67), the latter divided into exudates of paraneoplastic (n = 46) or parainfectious (n = 21) origin. Zymographic and Western blot analyses revealed constant expression of interstitial collagenase (MMP-1), gelatinase-A (MMP-2), and TIMP-1 in all 88 samples. In contrast, analyses of gelatinase-B (MMP-9) demonstrated a specific expression pattern, with high expression in exudates and lack of expression in transudates. Neutrophil collagenase (MMP-8) was detected in trace amounts, and correlated with the number of neutrophils in the effusion. Low levels of TIMP-2 were detected only in exudates and not in transudates. Quantitative analysis of the expression ratio of gelatinase-B to gelatinase-A revealed statistically significant differences between effusions of different origin. The ratio was highest in exudates of paraneoplastic origin and lowest in transudates. Our data thus suggest that interstitial collagenase, gelatinase-A, and TIMP-1 play a role in homeostasis of the pleural space in vivo as constitutively expressed proteins, whereas gelatinase-B and TIMP-2 expression are induced in specific disease states. These observations contribute to the understanding of the pathophysiology of pleural effusions, and may help to characterize and possibly distinguish effusions of different origin.     

Cytomegalovirus disease occurring before engraftment in marrow transplant recipients

We developed a novel approach for the high-level production of a microbial transglutaminase (TGase) from Streptoverticillium in E. coli. The direct expression of the TGase gene in E. coli cells did not cause overproduction, probably due to the harmful influence of TGase activity, which introduces covalent crosslinks between proteins. Therefore, we fused the chemically synthesized TGase gene coding for the entire 331 amino acid residues at the amino terminus to a bacteriophage T7 gene 10 leader peptide (260 amino acids) using an inducible expression vector. The TGase gene was expressed as inclusion bodies in the E. coli cytoplasm. Restoring 15 amino acid residues upstream of the amino terminus of the mature TGase by a two-step deletion of the fusion sequence facilitated solubilization and subsequent proteolytic cleavage, thus releasing mature TGase. Although the mature form had less TGase activity than native TGase, because of the poor refolding rate, these results suggest that this system is suitable for the efficient production of TGase.     

The regulatory mechanisms of the blood respiratory function in iron-deficiency anemias

Experience of vascular thrombosis prophylaxis and treatment after reconstructive operation conduction on abdominal aorta and peripheral arteries in 244 patients, including 112 of them immediately after the operation, 32-up to one year time, 100-in long-term follow-up period was summarized. Main aetiological cause for thrombosis occurrence immediately after the operation were technical and tactical failures committed during its conduction, in the early postoperative period-the neointima hyperplasia in the anastomosis area, in late terms-the blood outflow disorder from the reconstructed segment due to the atherosclerosis progression. Original methods of reoperation conduction for the transplant thrombosis and the outflow arteries reconstruction were proposed. Mortality lowering from 8.8 to 5.3% and the extremity revascularization occurrence, in 75% of patients immediately after the operation and in 84%-in long-term period was promoted owing to tactics of postoperative thrombosis treatment elaborated.     

Sj?gren''s syndrome in patients with newly diagnosed untreated non-Hodgkin''s lymphoma

A prfA gene encoding polypeptide release factor RF1 was cloned from Thermus thermophilus. T thermophilus RF1 shares 68% homology with Escherichia coli RF1, and its overproduction reduced readthrough translation of UAG, not of UGA, in the lacZ gene. Rapid purification of T thermophilus RF1 was achieved by T7-RNA polymerase driven overexpression of T thermophilus RF1 protein with a C-terminal histidine tag.