Invited review: cross-bridge regulation by thin filament-associated proteins.

This minireview will cover current concepts on the identity and mechanistic function of smooth muscle actin binding proteins that may regulate actin-myosin interactions. The potential roles of tropomyosin, caldesmon, calponin, and SM22 will be discussed. The review, for purposes of brevity, will be nonexhaustive but will give an overview of available information on the in vitro biochemistry and potential in vivo function of these proteins. Preterm labor is discussed as a possible example of where thin filament regulation may be relevant. Considerable controversy surrounds the putative physiological significance of these proteins, and emphasis will be placed on the need for more experimental work to determine the degree to which tissue- and species-specific effects have clouded the interpretation of functional data.     

CaMKIIT287 and T305 regulate history-dependent increases in alpha agonist-induced vascular tone.

CaMKII is a calcium and calmodulin-activated kinase that has been shown to regulate learning and memory in the brain, and contractility in blood vessels. Following Ca activation, CaMKII autophosphorylates, gaining a calcium-independent autonomous activity that reflects a molecular memory of having previously come into contact with calcium. The present study addresses whether the molecular memory properties of CaMKII are involved in the modulation of sustained vascular tone. We demonstrate a history-dependence of alpha agonist-induced vascular tone and show that CaMKII activation in vascular cells is also history dependent. Autophosphorylation of Thr287, which is classically associated with autonomous activity, does not persist during tone maintenance after transient increases in intracellular calcium levels. However, we have found that another site, Thr305, known from in vitro studies to be inhibitory, is regulated by alpha agonists in that the inhibitory action is removed, thus leading to a delayed reactivation of CaMKII as measured by Thr287 phosphorylation. By the use of a small molecule CaMKII inhibitor (KN93) as well as a decoy peptide (autoinhibitory peptide; AIP) we show a cause and effect relationship between CaMKII reactivation and sustained vascular tone maintenance. Thus, it appears that a complex interplay between the regulation of Thr305 and Thr287 provides a novel mechanism by which a history-dependence is developed and contributes to a new facet of molecular memory for CaMKII of relevance to vascular tone maintenance.     

Role of the Met3534-Ala4271 region of the ryanodine receptor in the regulation of Ca2+ release induced by calmodulin binding domain peptide

CaMBP, a peptide corresponding to the 3614-3643 calmodulin (CaM) binding region of the ryanodine receptor (RyR1), is known to activate RyR1 Ca²⁺ channel. To analyze the mechanism of channel regulation by the CaMBP-RyR1 interaction, we investigated a), CaMBP binding to RyR1, b), induced local conformational changes in the CaMBP binding region of RyR1 using the fluorescent conformational probe badan attached to CaMBP (CaMBP-badan), and c), effects of “a” and “b” on SR Ca²⁺ release. We also monitored the interaction of CaMBP-badan with CaM and a peptide corresponding to the Met³⁵³⁴-Ala⁴²⁷¹ region of RyR1 (R3534-4271) as a control. At lower peptide concentrations (≤15 μM), CaMBP binding to RyR1 increased the intensity of badan fluorescence emission at a shorter wavelength (the state resembling CaMBP-badan/Ca-CaM) and induced Ca²⁺ release. Further increase in CaMBP concentration (up to ∼50 μM) produced more binding of CaMBP accompanied by further increase in the badan fluorescence emission but at a longer wavelength (the state resembling CaMBP-badan/apo-CaM) and inhibited Ca²⁺ release. Binding of CaMBP-badan to R3534-4271 increased the intensity of badan fluorescence, showing the similar concentration-dependent red-shift of the emission maximum. It is proposed that CaMBP interacts with two classes of binding sites located in the Met³⁵³⁴-Ala⁴²⁷¹ region of RyR1, which activate and inhibit the Ca²⁺ channel, respectively.     

Twin fetus in fetu in a child: a case report and review of the literature

Introduction

Necrotizing fasciitis is a rare condition with a mortality rate of around 34%. It can be mono- or polymicrobial in origin. Monomicrobial infections are usually due to group A streptococcus and their incidence is on the rise. They normally occur in healthy individuals with a history of trauma, surgery or intravenous drug use. Post-operative necrotizing fasciitis is rare but accounts for 9 to 28% of all necrotizing fasciitis. The incidence of wound infection following saphenofemoral junction ligation and vein stripping is said to be less than 3%, although this complication is probably under-reported. We describe a case of group A streptococcus necrotizing fasciitis following saphenofemoral junction ligation and vein stripping.

Case Presentation

A 39-year-old woman presented three days following a left sided saphenofemoral junction ligation with long saphenous vein stripping at another institution. She had a three day history of fever, rigors and swelling of the left leg. She was pyrexial and shocked. She had a very tender, swollen left groin and thigh, with a small blister anteriorly and was in acute renal failure. She was prescribed intravenous penicillin and diagnosed with necrotizing fasciitis. She underwent extensive debridement of her left thigh and was commenced on clindamycin and imipenem. Post-operatively, she required ventilatory and inotropic support with continuous veno-venous haemofiltration. An examination 12 hours after surgery showed no requirement for further debridement. A group A streptococcus, sensitive to penicillin, was isolated from the debrided tissue. A vacuum assisted closure device was fitted to the clean thigh wound on day four and split-skin-grafting was performed on day eight. On day 13, a wound inspection revealed that more than 90% of the graft had taken. Antibiotics were stopped on day 20 and she was discharged on day 22.

Conclusion

Necrotizing fasciitis is a very serious complication for a relatively minor, elective procedure. To the best of our knowledge, this is the first report in the English-language literature of this complication arising from a standard saphenofemoral junction ligation and vein stripping. It highlights the need to be circumspect when offering patients surgery for non-life-threatening conditions.     

A study on the prevalence of upper extremity repetitive strain injuries among the handloom weavers of West Bengal

Handloom is one of the oldest cottage industries in India, particularly in West Bengal, where a considerable number of rural people are engaged in weaving. Purposes of the present investigation were to clarify the prevalence of repetitive strain injuries in upper extremities among the handloom weavers and to identify the risk factors leading to its development. Fifty male handloom weavers were randomly selected from the population. A questionnaire (Kourinka et al., 1987) method including Borg scale assessment of pain, checklist analyses of the work, and time-motion studies for analyzing the repetitiveness/non-repetitiveness of the job were implemented. The time-motion analyses demonstrated that weaving occupied over 50% of the work cycle time for majority of subjects, and thus could be regarded as a repetitive activity. Statistical analyses revealed a highly significant correlation between the intensity of pain feeling and the repetitiveness on one hand, and the year of experience as a weaver on the other. By contrast, no significant relationship was observed between chronological ages of weavers and the pain intensity. These results suggested that highly repetitive works engaged for a long time could increase the intensity of the pain felt and would lead to repetitive strain injuries.     

Mannich reaction: an approach for the synthesis of water soluble mulundocandin analogues

Semisynthetic modifications at Hydroxy tyrosine (Htyr) unit of mulundocandin (1) were carried out to improve its aqueous solubility. A single step introduction of substituted aminomethyl groups at the ortho position(s) of phenolic hydroxyl of HTyr unit of mulundocandin has been achieved in 7-85% yield. The in vitro screening of Mannich products against Candida albicans and Aspergillus fumigatus, retained the in vivo activity of parent by oral and intraperitoneal route. Compound 20, showed significant improvement in activity over mulundocandin (1) and activity compares well with that of fluconazole.     

Characterization of an oligopeptide transporter in renal lysosomes

Renal lysosomes play a major role in catabolism of plasma proteins. Final products of this catabolism include dipeptides and tripeptides that must be exported to the cytosol for hydrolysis. The aim of the present study was to determine whether an oligopeptide transporter is present in the renal lysosomal membrane that could mediate this export. The existence of an oligopeptide transporter was probed with the uptake of glycylglutamine (Gly-Gln) by membrane vesicles prepared from renal lysosomes. Kinetic analysis showed the presence of a single transporter with a K(m) of 8.77 mM for the uptake of Gly-Gln. The Gly-Gln uptake was energized by the imposition of an inwardly directed proton gradient (pH(out) 5.0/pH(in) 7.3) and membrane potential (outside positive/inside negative) resulting in overshoot. The Gly-Gln uptake was inhibited by the presence of dipeptides and tripeptides, but not amino acids. Western blot analysis of lysosomal membrane proteins with Pept-1 (an oligopeptide transporter) antibody as the probe showed the presence of an immunoreactive protein. This immunoreaction was abolished when the antiserum was preabsorbed with the Pept-1 epitope (0.5 microg/ml). In conclusion, the present data show the existence of a low-affinity dipeptide transporter in the renal lysosomal membrane that appears to belong to the Pept family of transporters. The function of this transporter appears to be to prevent accumulation of dipeptides in renal lysosomes.     

Molecular pathogenesis of Wilson disease: haplotype analysis, detection of prevalent mutations and genotype–phenotype correlation in Indian patients

Wilson disease (WD) is an autosomal recessive disorder caused by defects in the copper-transporting P-type ATPase gene (ATP7B) resulting in the accumulation of copper in the liver and the brain. We identified prevalent mutations in the ATP7B of Indian WD patients and attempted to correlate those with the disease phenotype. Patients from 62 unrelated families and their first-degree relatives comprising 200 individuals were enrolled in this study. Three dinucleotide repeat markers flanking WD locus and a few intragenic SNPs were used to determine the genotypes and construct haplotypes of the patients. Seven recurring haplotypes accounting for 58% of the total mutant chromosomes were identified, and four underlying defects in the ATP7B representing 37% of WD chromosomes were detected. In addition, five other rare mutations were characterized. Thus a total of nine mutations including five novel changes were identified in the ATP7B of WD patients. Interestingly, homozygotes for different mutations that would be expected to produce similar defective proteins showed significant disparity in terms of organ involvement and severity of the disease. We also observed WD patients with neurological symptoms with little or no manifestation of hepatic pathogenesis. In one WD family, the proband and a sib had remarkably different phenotypes despite sharing the same pair of mutant chromosomes. These findings suggest a potential role for yet unidentified modifying loci for the observed phenotypic heterogeneity among the WD patients.