Tyrosine phosphatase regulation of MuSK-dependent acetylcholine receptor clustering

During vertebrate neuromuscular junction (NMJ) development, nerve-secreted agrin induces acetylcholine receptor (AChR) clustering in muscle by activating the muscle-specific tyrosine kinase MuSK. Recently, it has been recognized that MuSK activation-dependent AChR clustering occurs in embryonic muscle even in the absence of agrin, but how this process is regulated is poorly understood. We report that inhibition of tyrosine phosphatases in cultured C2 mouse myotubes using pervanadate enhanced MuSK auto-activation and agrin-independent AChR clustering. Moreover, phosphatase inhibition also enlarged the AChR clusters induced by agrin in these cells. Conversely, in situ activation of MuSK in cultured Xenopus embryonic muscle cells, either focally by anti-MuSK antibody-coated beads or globally by agrin, stimulated downstream tyrosine phosphatases, which could be blocked by pervanadate treatment. Immunoscreening identified Shp2 as a major tyrosine phosphatase in C2 myotubes and down-regulation of its expression by RNA interference alleviated tyrosine phosphatase suppression of MuSK activation. Significantly, depletion of Shp2 increased both agrin-independent and agrin-dependent AChR clustering in myotubes. Our results suggest that muscle tyrosine phosphatases tightly regulate MuSK activation and signaling and support a novel role of Shp2 in MuSK-dependent AChR clustering.     

A modification of segment III intrahepatic cholangiojejunostomy

Segment III bypass can achieve excellent palliation in jaundiced patients with unresectable malignancy of the hepatic duct confluence. However, the long-term benefits are often offset by early morbidity and mortality associated with surgery. Bile leakage is a common postoperative complication. Several approaches to the segment III duct have been described. The "round ligament approach" identifies the segment III duct by following the round ligament into the recessus of Rex, in the umbilical fissure. It is the approach adopted by most units, including our own. The liver is often split to a depth of 5 to 6 cm to expose the duct. Fashioning an intrahepatic cholangiojejunostomy within the recess of the umbilical fissure can be technically difficult due to lack of space. We describe a modification of the round ligament approach, creating a long and tension-free cholangiojejunostomy, which we believe reduces the incidence of postoperative bile leakage.     

Healing potential of Anogeissus latifolia for dermal wounds in rats

Wound healing potential of ethanolic extract of Anogeissus latifolia bark (ALE) for treatment of dermal wounds in rats was studied on excision and incision wound models. HPTLC of the total extract was recorded for the purpose of standardization. Various parameters of incision wound, viz. epithelization period, scar area, tensile strength and hydroxyproline measurements along with wound contraction, were used to evaluate the effect of A. latifolia on wound healing. The results obtained indicate that A. latifolia accelerates the wound healing process by decreasing the surface area of the wound and increasing the tensile strength. Nitrofurazone ointment was used as a positive control. Complete epithelization was observed within 15 days with ALE. Measurements of the healed area and the hydroxyproline level were in agreement. Antibacterial activity of ALE was studied against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) compared to erythromycin and tetracycline. Moderate activity was observed against all organisms. The present study provides a scientific rationale for the traditional use of Anogeissus latifolia in the management of skin diseases such as sores, boils and itching.     

Use of polymerase chain reaction in the diagnosis of fungal endophthalmitis

OBJECTIVE: To evaluate the usefulness of polymerase chain reaction (PCR) compared with the conventional mycologic methods in the diagnosis of fungal endophthalmitis. DESIGN: Prospective comparative validation of diagnostic testing-case-control study. PARTICIPANTS AND CONTROLS: Thirty subjects in whom fungal endophthalmitis was suspected and 20 controls with noninfections. INTERVENTION TESTING: Collection of intraocular specimens and testing for the presence of fungus by PCR and conventional methods. MAIN OUTCOME MEASURES: Detection of fungus by microscopy, growth by culture, and fungal DNA by PCR for definitive and rapid diagnosis of fungal endophthalmitis. RESULTS: None of the controls was positive by microscopy, culture, or PCR. Among the 43 intraocular specimens from 30 subjects, 24 were positive by conventional mycologic methods and 32 were positive by PCR. PCR increased the sensitivity of detection by 18.6%, which was statistically significant (McNemar test: P = 0.039). CONCLUSIONS: PCR was a more sensitive and rapid diagnostic tool compared with the conventional mycologic methods in the diagnosis of fungal endophthalmitis.     

Genetics of anesthetic response: autosomal mutations that render Drosophila resistant to halothane

Molecular mechanisms of anesthetic action are poorly understood. Genetic approaches to investigate mechanisms of anesthesia, although sparse and rather new, are turning out to be informative and add a new perspective. Before beginning a systematic investigation of anesthesia by this approach, it is necessary to have at hand a large collection of mutations in different loci that alter anesthetic response. We report here the isolation and characterization of six mutant autosomal lines that show a decreased sensitivity to the inhalation of anesthetic halothane. Two of these mutations, Omar(82) and Qajjem(211) are shown to map to separate loci on the third chromosome.