The alpha7beta1 integrin mediates adhesion and migration of skeletal myoblasts on laminin.

Many aspects of myogenesis are believed to be regulated by myoblast interactions with specific components of the extracellular matrix. For example, laminin has been found to promote adhesion, migration, and proliferation of mammalian myoblasts. Based on affinity chromatography, the alpha7beta1 integrin has been presumed to be the major receptor mediating myoblast interactions with laminin. We have prepared a monoclonal antibody, O26, that specifically reacts with both the X1 and the X2 extracellular splice variants of the alpha7 integrin chain. This antibody completely and selectively blocks adhesion and migration of rat L8E63 myoblasts on laminin-1, but not on fibronectin. In contrast, a polyclonal antibody to the fibronectin receptor, alpha5beta1 integrin, blocks myoblast adhesion on fibronectin, but not on laminin-1. The alpha7beta1 integrin also binds to a mixture of laminin-2 and laminin-4, the major laminin isoforms in developing and adult skeletal muscle, but O26 is a much less potent inhibitor of myoblast adhesion on the laminin-2/4 mixture than on laminin-1. Based on affinity chromatography, we suggest that this may be due to higher affinity binding of alpha7X1 to laminin-2/4 than to laminin-1.

Fungal galectins, sequence and specificity of two isolectins from Coprinus cinereus.

Galectins are members of a genetically related family of beta-galactoside-binding lectins. At least eight distinct mammalian galectins have been identified. More distantly related, but still conserving amino acid residues critical for carbohydrate-binding, are galectins in chicken, eel, frog, nematode, and sponge. Here we report that galectins are also expressed in a species of fungus, the inky cap mushroom, Coprinus cinereus. Two dimeric galectins are expressed during fruiting body formation which are 83% identical to each other in amino acid sequence and conserve all key residues shared by members of the galectin family. Unlike most galectins, these have no N-terminal post-translational modification and no cysteine residues. We expressed one of these as a recombinant protein and studied its carbohydrate-binding specificity using a novel nonradioactive assay. Binding specificity has been well studied for a number of other galectins, and like many of these, the recombinant C. cinereus galectin shows particular affinity for blood group A structures. These results demonstrate not only that the galectin gene family is evolutionarily much older than previously realized but also that fine specificity for complex saccharide structures has been conserved. Such conservation implies that galectins evolved to perform very basic cellular functions, presumably by interaction with glycoconjugates bearing complex lactoside carbohydrates resembling blood group A.

Identification of insulin-like growth factor-binding protein-3 (IGFBP-3) and IGFBP-2 in human follicular fluid.

Two major insulin-like growth factor-binding proteins, IGFBP-2 and IGFBP-3, were identified by Western ligand blotting of human follicular fluid (FF) aspirated from luteinizing follicles during ovarian stimulation with human menopausal gonadotropin (LH and FSH). IGFBP-1 was also present in FF, and an IGFBP with a mol wt of 24000 daltons, present in serum, appeared to be absent in FF. Identification of IGFBP-1, IGFBP-2, and IGFBP-3 was confirmed using IGFBP-specific antisera. IGF-I and IGF-II levels were measured in patient serum and FF at the time of oocyte harvest, and serum levels of both peptides were consistently higher than FF levels. The finding of three major serum IGFBPs in human FF suggests that IGF regulation in the ovary is probably under complex control by this set of regulatory BPs.

Insulin-like growth factor binding proteins in maternal serum throughout gestation and in the puerperium: effects of a pregnancy-associated serum protease activity.

The cDNAs encoding three major insulin-like growth factor-binding proteins (IGFBPs) have been cloned and sequenced. We have examined, by Western ligand blotting, the profiles of these binding proteins in human female serum in the normal menstrual cycle, throughout pregnancy, and during the postpartum period. There was no change in the serum profile of any of the binding proteins in early pregnancy compared to that in the secretory phase of the menstrual cycle. However, there was a marked decrease in circulating levels of the main serum IGFBP, IGFBP-3, after 6 weeks of gestation, continuing progressively to term and returning to nonpregnant levels by 5 days postpartum. IGFBP-2 decreased steadily throughout gestation. In contrast, IGFBP-1 levels were found to rise by the second trimester. Endoglycosidase-F digestion did not enhance detection of IGFBP-3 by ligand blotting. Immunoprecipitations with two separate antibodies against IGFBP-3 and IGFBP-2, followed by Western ligand blotting, confirmed the marked decrease in IGFBP-3 levels after 6 weeks of gestation and the more gradual decrease in IGFBP-2. In contrast, immunoprecipitations with IGFBP-1 monoclonal antibodies confirmed the increase in IGFBP-1 during gestation. Endogenous serum IGFs were separated from serum IGFBPs by acid chromatography, and an 80% decrease in total IGF-binding activity in the IGFBP fraction of chromatographed pregnancy vs. nonpregnancy serum was detected by charcoal absorption assay. Furthermore, immunoprecipitations of IGF affinity cross-linked IGFBP fractions with IGFBP-3-specific antiserum confirmed a marked diminution of IGFBP-3 in pregnancy compared to nonpregnancy serum, and revealed, only in pregnancy serum, the concomitant appearance of a band with a mol wt of 34K and three less intense bands with mol wt between 20-26K on sodium dodecyl sulfate gels. Incubation of nonpregnancy serum with 6-week pregnancy serum at 37 C for 5 h, followed by Western ligand blotting, showed only a slight reduction in the amount of IGFBP-3 in the mixture compared to that in controls. However, incubation of term pregnancy with nonpregnancy serum at 37 C for 5 h revealed a marked reduction of IGFBP-3 in the mixture. When iodinated recombinant IGFBP-3 was incubated with term pregnancy serum under the same conditions, the appearance of a 29K protein was identified by gel electrophoresis and autoradiography, along with three less intense bands with mol wt between 17-22K.(ABSTRACT TRUNCATED AT 400 WORDS)

Coronary endarterectomy. An adjunct to coronary artery bypass grafting.

There is a wide variation in the reported results of endarterectomy in conjunction with coronary artery bypass grafting. Operative mortality ranges from 0 to 10 per cent, perioperative infarction ranges from 5 to 30 per cent, and patency rates range from 38 to 100 per cent, with 74 to 95 per cent being asymptomatic or improved. This wide discrepancy in clinical outcome occurs for a number of reasons. First, there is nonhomogeneity of patient populations resulting from a lack of standardized patient selection criteria. Second, the operative experience of most published reports spans a decade throughout which major advances in cardiac surgery have occurred. Finally, endarterectomy is a technically challenging procedure with its own learning curve. Differences in technique and expertise almost certainly contribute to the variability of results. Patients with diffuse coronary artery disease pose a challenge to the cardiac surgeon. Endarterectomy entails the risks of increased morbidity and mortality and therefore should be done only if conventional bypass grafting is precluded. However, the risks of these complications must always be weighed against the possible benefits. At the present time carefully selected patients can benefit from this procedure. Unfortunately, until such time as controlled randomized studies are carried out on a prospective basis, statistical support for this procedure will not be available. Given that such a study is questionable from an ethical point of view, clinical decisions for this select group of patients must be done on a case-by-case basis. The best that can currently be done is to carefully follow these patients and scrutinize existing data to ensure optimal clinical management.

Extravasation of contrast material due to rupture of the intrahepatic duct: eight additional cases.

We have reported eight additional cases of contrast extravasation due to rupture of the intrahepatic duct. Although this phenomenon is usually caused by blind instrumentation of the biliary ducts, it can also result from excessive pressure during injection of contrast material. Undetected extravasation can lead to transient hemorrhage, abscess formation, hematobilia, intraductal obstruction, and cholangitis. Rupture can best be prevented by increased care on the part of the surgeon.

Pulsed excimer laser angioplasty of human cadaveric arteries.

Laser angioplasty has been limited by the lack of precise control of thermal and acoustic vascular injury. Pulsed excimer lasers, by contrast, have a capacity to affect target tissue without heat dispersion or damage to surrounding structures. The ablative properties of three excimer wavelengths, krypton fluoride (249 nm), xenon chloride (308 nm), and xenon fluoride (351 nm), were investigated with the use of fresh human cadaveric normal and atherosclerotic femoral arteries. Light and electron microscopy demonstrated clean cuts with histologically normal edges. There was no evidence of either thermal or acoustic damage with any of the wavelengths studied. The depth of ablation varied directly with the number of pulses and inversely with tissue density while the incision width remained constant. The excimer laser appears to offer significant advantages over its conventional counterparts for the ablation of atherosclerotic plaque.

Functioning insulinoma with a twenty-year history.

A case of functioning beta islet cell tumor (insulinoma) producing incapacitating hypoglycemia for 20 years before being diagnosed by means of pancreatic angiography is presented. Laparotomy with local tumor excision was curative.

Low-energy direct defibrillation of the human heart following cardioplegic arrest.

In this study of direct defibrillation, 130 patients underwent coronary artery bypass procedures with cardiopulmonary bypass, moderate systemic hypothermia, and cardioplegic arrest. No patient required more than 10 watt-seconds of energy for defibrillation, and in 90.91% of those who required defibrillation, 5 watt-seconds or less was sufficient.

Tracheostomy tube insertion in the pretracheal fascia.

A case of massive dissecting emphysema secondary to attempted emergency tracheostomy is reported. Malpositioning of the tube in the pretracheal fascia and positive pressure ventilation were the cause of the dissecting emphysema. This problem was recognized with subsequent removal of the tracheostomy tube, but unfortunately the skin was sutured which prevented air from escaping. The diagnosis was made by physical examination and chest roentgenogram. It was successfully treated by reopening of the wound and evacuation of clots. Careful technique performed under optimal conditions is of paramount importance in avoiding this complication.

Percutaneous infraclavicular subclavian catheterization.

A series of 510 percutaneous infraclavicular subclavian venipunctures performed by the authors is presented. Complications included five cases of simple pneumothorax (0.98%) and one instance of subcutaneous emphysema without pneumothorax (0.20%). No mortality was associated with the procedure.

Postoperative acalculous cholecystitis.

Two cases of acute acalculous cholecystitis occurring after major surgical procedures unrelated to the biliary tract are described. Symptoms are usually masked by postsurgical pain. Gangrene and perforation usually occur; this explains why the mortality rate is high. Awareness of this complication is essential; it leads to the early performance of cholecystostomy or cholecystostomy, lifesaving procedures.