Aorta--coronary artery revascularization with an expanded polytetrafluoroethylene vascular graft. A preliminary report

Patients requiring coronary artery surgery may have had bilateral saphenous vein stripping, and the arm veins may not be adequate for use for coronary artery grafting. The internal mammary artery may not be long enough for use for the circumflex or right coronary artery anastomoses. A suitable substitute would be most welcome for these patients or for those with marked varicosities of the saphenous vein. Five patients received expanded polytetrafluoroethylene (PTFE) grafts (Gore-Tex vascular grafts) for coronary artery revascularization because veins of adequate size or length were not available at the time of operation. These five patients are alive 9 to 14 months after graft insertion. Four of the five grafts were patent at the time of restudy 3 to 6 months postoperatively. More follow-up studies for far longer periods of time will be necessary before Gore-Tex vascular grafts can be recommended as the ideal material for coronary artery bypass surgery.

The binding of d-glucosyl-neoglycoproteins to the hepatic asialoglycoprotein receptor

The binding of D-glucosyl-neoglycoproteins and D-galactose-terminated glycoproteins to the hepatic asialoglycoprotein receptor of rabbit liver membranes were characterized and compared. The binding of both types of glycoproteins showed the same dependence on calcium concentration, sensitivity to neuraminidase, and degree of inhibition by various carbohydrate derivatives. These results, along with the observation that the rabbit liver membranes bound both the D-glucosyl- and D-galactosyl-terminated glycoproteins to the same extent, indicated that both types of glycoproteins bound to the same receptor. To confirm this hypothesis, receptors were isolated from rabbit livers by affinity chromatography using D-galactosyl-bovine serum albumin or D-glucosyl-bovine serum albumin immobilized on Sepharose. These receptors were shown to be identical by several chemical and immunological criteria as well as in their ability to bind equal amounts of D-galactosyl- and D-glucosyl-terminated glycoproteins. The conclusion is that the rabbit hepatic asialoglycoprotein receptor cannot discriminate between D-galactosyl and D-glucosyl-terminated glycoproteins and binds both.

Fine structure of a cerebellar neuroblastoma

A cerebellar neoplasm of an 18-month-old boy was examined with both the light and electron microscopes. The diagnosis of neuroblastoma was made on the basis of the presence of numerous synaptic vesicles in the great majority of cell processes and the occasional complete synapses within the tumor tissue.

Specific adhesion of rat hepatocytes to beta-galactosides linked to polyacrylamide gels

Rat hepatocytes, isolated by a collagenase perfusion technique, specifically bind to polyacrylamide gel containing covalently immobilized 6-aminohexyl beta-D-galactopyranosyl groups. Less than 5% of these cells bind to polyacrylamide or to gels with the following covalently linked ligands: 6-aminohexanol, or the 6-aminohexyl D-pyranosides of alpha-mannose, beta-glucose, beta-2-acetamido-2-deoxyglucose, beta-cellobiose, beta-maltose, or beta-melibiose. Cell binding to beta-D-galactoside gels occurs after a lag period at 37 degrees and 65 to 100% (depending on the cell preparation) of the cells adhere. The duration of the lag period is inversely related to the beta-D-galactoside content of the gel but preincubation of the cells at 37 degrees reduces the lag period. Cell-gel binding is a threshold phenomenon. Adhesion of cells to gels does not occur when the glycoside concentration is less than about 900 nmol per cm2 x 0.25 mm thick gel piece. Above this critical concentration, cell-gel binding occurs and becomes maximal when the concentration is increased by only 20%. If these in vitro results apply to cellular interactions in vivo, they suggest that slight changes in the levels of cell surface or extracellular matrix carbohydrates may profoundly influence the behavior of neighboring cells.

Purification and properties of a beta-mannosidase from Aspergillus niger

A beta-mannosidase (beta-D-mannoside mannohydrolase, EC 3.2.1.25) was purified to apparent homogeneity from the culture filtrate of the fungus, Aspergillus niger. The enzyme had an estimated molecular weight of about 120,000 and was a glycoprotein. Radioactive enzyme was prepared by growing the fungus in [14C]fructose, and this enzyme was used for the preparation of 14C-glycopeptides. The glycopeptides were purified on Sephadex G-25 and G-50 and were then hydrolyzed for sugar analysis. Two radioactive sugars were found in the glycopeptides and these were identified as mannose and glucosamine in a ratio of 2.5 or 3:1. Based on susceptibility of the enzyme to alkaline treatment and the formation of [3H]glucosaminitol in the presence of NaB3H4, the oligosaccharide is apparently attached to the protein in a GlcNAc-asparagine linkage. The beta-mannosidase had good activity on p-nitrophenyl-beta-D-mannoside but was inactive on p-nitrophenyl-alpha-D-mannoside as well as on other p-nitrophenyl glycosides. It also showed good activity on the beta(1 leads to 4)-linked trisaccharide of mannose and somewhat lower activity of the corresponding disaccharide. With each of these substrates the Km was about 1 mM, whereas with the p-nitrophenyl-beta-D-mannoside the Km was about 2 mM. The beta-mannosidase also released [14C]mannose from the Man-GlcNAc-GlcNAc trisaccharide isolated from the lipid-linked oligosaccharides of aorta and released mannose from the disaccharides, Man-(beta1 leads to 4)GlcNAc and Man-(beta1 leads to 4)ManNAc. The pH optimum for the enzyme was about 3.5 to 4.0 in glycine or acetate buffer.

Molecular interactions between adriamycin and x-ray damage in mammalian tumor cells

The effect of the anthracycline antibiotic, Adriamycin (Ad), on the sedimentation properties of pre-labelled mammalian DNA has been studied. Ad induces DNA degradation in vivo in both excision repair-competent (HeLa and Me-180) cells and in excision repair-deficient (REQ) cells. When X-irradiated cells are exposed to Ad during the period of repair of DNA single-strand breaks, small numbers of residual breaks persist following completion of repair. These are attributable to those induced by Ad alone. The effects of Ad and X-rays therefore appear to be similar and additive. No clear-cut evidence that Ad can inhibit the repair of X-ray-induced DNA single-strand breakage was found. Ad also induced the formation of DNA double-strand breaks and inhibits the repair of X-ray-induced base damage (repair replication). The induction of DNA strand breakage may be responsible for Ad cell toxicity and may contribute to its capacity to enhance primary X-irradiation damage when the two types of lesions co-exist.

Binding of microtubules to pituitary secretory granules and secretory granule membranes

Microtubules assembled in vitro were bound to purified porcine pituitary secretory granules and to isolated granule membranes. The interaction between microtubules and whole secretory granules was demonstrated by alteration in the sedimentation properties of the microtubules. Incubation of secretory granules with microtubules resulted in pelleting of microtubules which increased as a function of the number of granules added. Binding was quantitated by measurement of the tubulin remaining in the supernate after centrifugation. The interaction of secretory granules and microtubules was inhibited by nucleoside triphosphates and augmented by adenosine 5'-monophosphate and adenosine. When depolymerized protein from microtubules was incubated with secretory granules, the granules did not appear to bind the soluble tubulin dimer present in these preparations. However, the high molecular weight protein associated with microtubules was adsorbed by secretory granules during the binding process. Incubation of isolated secretory granule membranes with microtubules followed by centrifugation to density equilibrium in a discontinuous sucrose density gradient caused pelleting of the membranes, which otherwise banded higher in the gradient. The visible alteration in membrane sedimentation was confirmed by measurements of the membrane-associated magnesium-ATPase activity and by a shift in radioactivity in iodinated membrane preparations. Our data suggest a role for microtubules in the intracellular movement of secretory granules; this movement is perhaps brought about by dynein-like cross bridges which link the tubulin backbone and granule surface.

Gunshot wounds of the esophagus

During a 4 year period between 1970 and 1974 there were eleven esophageal gunshot wounds representing 52 per cent of the total esophageal perforations. The increased incidence of esophageal gunshot wounds reflects the higher rate of civilian gunshot injuries. There were six perforations in the cervical portion of the esophagus and five in the thoracic portion, with three located above the aortic arch, one in the midesophagus, and one in the lower third. Symptoms are less diagnostic than in esophageal perforations from other causes because the gunshot wound tends to mask the complaints related to mediastinitis. The signs are similar. In 9 patients free air was present in the neck or mediastinum and in 10 patients the diagnosis was confirmed by barium swallow. Of the 2 patients without free air, one had a lateral thoracic wound and esophageal injury was not suspected; the diagnosis was made by drainage of oral feeding through a thoracostomy and confirmed by barium swallow. In the other patient the perforation was found during surgery for hemothorax. Primary repair with drainage was done in the group with cervical injuries. All survived with no serious complications. In the group with thoracic injuries, fistulas developed in 2 of 3 patients who had primary repair with drainage. Two patients with extensive injuries of the esophagus treated by defunctionalization did well but required a second procedure. It is concluded that gunshot wounds of the cervical esophagus, if treated promptly by suture and drainage, will do well. Thoracic injuries represent a more difficult problem and it is suggested that defunctionalization of the esophagus is the safest procedure, particularly if damage is extensive.

Attachment of thioglycosides to proteins: enhancement of liver membrane binding

Thioglycosides of D-galactose, D-glucose, N-acetyl-D-glucosamine, and D-mannose were covalently attached to Aspergillus oryzae alpha-amylase, hen's eggs lysozyme, and bovine serum albumin by amidination, diazo coupling, and amide formation. The binding of the newly formed glycoproteins (neoglycoproteins) to rabbit liver membranes was measured, using asialoorosomucoid as a reference. Attachment of D-galactosides by any of the three methods enhanced binding by several orders of magnitude. Coupling of a comparable number of D-mannosides or N-acetyl-D-glucosaminides had little or no effect. Attachment of D-glucosides also enhanced binding but to a variable extent depending on the method of attachment. Thus, the behavior of neoglycoproteins toward rabbit liver membranes closely paralleled that of serum glycoproteins (Ashwell and Morell, 1974) with respect to sugar specificity.

2-Imino-2-methoxyethyl 1-thioglycosides: new reagents for attaching sugars to proteins

Cyanomethyl 1-thioglycosides ofD-galactose, D-glucose, 2-acetamido-2-deoxy-D-glucose, and D-mannose were prepared from the respective pseudothiourea derivatives and chloroacetonitrile. The nitrile group in these cyanomethyl thioglycosides can be converted to a methyl imidate group by treatment with sodium methoxide or HC1 in dry methanol to yield 2-imino-2-methoxyethyl 1-thioglycosides (IME-thioglycosides). The factors influencing the yield of IME-thioglycosides were investigated. The most convenient method of preparing IME-thioglycosides was treating 0.1 M cyanomethyl thioglycoside peracetate in dry methanol with 0.01 M sodium methoxide at room temperature for 24-48 h (50-60% yield). These IME-thioglycosides reacted readily with simple amines, amino acids, and proteins in mildly alkaline buffer solutions. Alpha-amylase and lysozyme modified with these reagents under appropriate conditions retained full activities. Thus the IME-thioglycosides constitute a new group of reagents for attaching sugars to proteins.

Abrupt propranolol withdrawal and myocardial contractility. A study of effects in normal man

Acute coronary artery syndromes, including unstable angina and myocardial infarction, have been desribed after the abrupt withdrawal of beta-adrenergic blocking agents. One possible mechanism is a hyperinotropic state resulting from a rebound hypersensitivity to endogenous catecholamines. Propranolol hydrochloride was administered to 21 healthy subjects for 15 days. Systolic time intervals and 24-hour urinary excretion of vanillylmandelic acid (VMA) were measured serially before, during, and after administration. Serial serum propranolol levels were measured during and after administration. Inhibition of exercise-induced tachycardia by propranolol was established before and during drug administration.

Induction of DNA degradation in vivo by adriamycin

The anthracycline antibiotic adriamycin (Ad) induced degradation (single-strand breaks) of cell DNA in vivo in murine L1210 leukemia cells. Measurement was made by alkaline sucrose gradient methods. Exposure of isolated DNA to Ad had little effect; the in vivo DNA strand breaks were probably due to the action of nucleases on DNA distorted by bound Ad. Toxicity of Ad to postmitotic cells such as cardiac cells could be mediated by this mechanism, since it could be demonstrated in periods substantially shorter than the cell generation time and thus could be responsible for interphase death.

Analysis of ion distribution in subcellular myocardial particulates separated by density gradient centrifugation with nonpolar liquid under ion immobilization conditions

Methods have been developed for the measurement of the Ca and Mg contents of subcellular particulates, separated by nonpolar liquid density gradient ultracentrifugation. After rapid deep freezing and removal of water by freeze-drying the frozen crushed tissue, homogenization and sonification a nonpolar liquid were carried out. Application of this technique has yielded evidence that the relative amounts of Mg and Ca are greatly different in the several subcellular particulates of normal heart muscle separated by density gradient centrifugation. It also appears that the comparative specific activity of Ca, after loading the perfusates with 45Ca, is very different in the several density fractions of the normal heart. The density site of greatest loading with 45Ca is changed in Ca2+-lack arrest and is very greatly altered by the induction of paradoxical Ca contracture. The method of ion-immobilization separation for water-free particulates of different densities in nonpolar liquids appears to be applicable to analysis for various constituents of other biological materials.

Molecular interactions of the combined effects of bleomycin and x-rays on mammalian cell survival

The interactions between bleomycin and X-ray damage and repair have been examined in rat and human tumor cells. Bleomycin itself indices extensive DNA single-strand breaks but does not appear to inhibit the repair of X-ray-induced DNA single-strand breaks. Quantitative analysis of these interactions is complicated by the retention of active bleomycin within cells that remains capable of further DNA degradation even under the conditions of alkaline sucrose gradient cell lysis. DNA double-strand breaks and/or disruptions of DNA-lipid complexes also occur following bleomycin exposure. X-ray-induced excision repair replication is only minimally influenced by even high concentrations of bleomycin. A small amount of excision repair is demonstrable in nonirradiated cells treated with high concentrations of bleomycin consistent with repair of bleomycin-induced nucleotide damage in cellular DNA by a "cut and patch" repair mechanism. Repair of bleomycin-induced DNA single-strand breaks also occurs. The data indicate that bleomycin and X-ray damage are quite similar both in their induction and repair, but that lesions occur and are repaired independently. The enzymatic mechanisms appear similar in the two cell types despite substantial differences in their sensitivity to bleomycin.

Small-bowel obstruction due to congenital anomaly of the falciform ligament

A patient who initially had a small-bowel obstruction was found, at laparotomy, to have an internal hernia through a defect of the falciform ligament. Simple resection of the round ligament was curative. The defect is presumed to have been congenital in origin. No previous report could be found in our review of the literature.

A screening method for determining nitrofuran drug residues in animal tissues

A method was developed for measuring low levels of total nitrofurans in animal tissues and milk. The antimicrobial nitrofurans (5 or more products) used in agriculture are extracted from tissue with aqueous acid in the presence of ethyl acetate. After centrifugation and evaporation, the organic residue is washed with hexane and the nitrofurans are hydrolyzed to 5-nitrofuraldehyde in aqueous acid at 70 degrees C. The hydrolysis product is extracted with benzene and measured by gas-liquid chromatography with electron capture detection. Recoveries of nitrofurazone and furazolidone from fortified poultry and swine tissues at the levels of 0.5 and 0.1 ppm are 75 and 65%, respectively. This procedure can be used to detect the total nitrofuran content of as little as 10 ppb muscle tissues and milk, 100 ppb liver, and 50 ppb fat with no interference from related veterinary nitrodrugs.

Studies on synthesis of 1,2-cis-D-galactosides with partially benzylated intermediates

The 1-bromides of p-nitrobenzoylated 2-O-benzyl- (1) and 2,3- (8) and 2,6-di-O-benzyl-D-galactose (14) and 2-O-benzyl-D-glucose (20) were treated under Koenigs-Knorr conditions with 6-(trifluoroacetamido)-1-hexanol. Examination of the products by p.m.r. spectroscopy, g.l.c., and mass spectrometry revealed that, whereas the major product derived from 14 was the pyranoside (19), the glycosides derived from both 1 and 8 were mainly furanosides. The corresponding glycoside from 20 was entirely the pyranoside (23).

Polyacrylamide gels copolymerized with active esters. A new medium for affinity systems

A new and versatile method for linking biologically active ligands to a polyacrylamide matrix is reported. Active esters of acrylic acid (N-succinimicyl acrylate and N-phthalimidyl acrylate) were synthesized, then copolymerized with acrylamide and N,N'-methylenebisacrylamide. Displacement of the active ester in the gel thus formed by various ligands containing aliphatic amino groups resulted in the formation of stable amid bonds between the ligands and the polyacrylamide gel. The affinity gel thus prepared has the following advantages: (i) resistance to chemical and microbiological degradation, (ii) ease of control of ligand level and higher levels of ligand possible, (iii) ease of control of porosity, and (iv) total displacement of the active ester under suitable conditions. Efficacy of this system was tested by preparation of 6-aminohexyl 2-acetamido-2-deoxy-beta-D-glucopyranoside derivative polyacrylamide gel by the described method. It was found to be more effective for purification of wheat germ agglutinin than the previously published affinity chromatography systems and the wheat germ hemagglutinin was obtained in crystalline form. In addition, partial resolution of isolectins was obtained from the affinity gel witha pH gradient.

Echocardiographic and electrocardiographic criteria for diagnosing left atrial enlargement

Electrocardiographic criteria for left atrial enlargement (LAE) were evaluated in a group of 100 patients with a wide spectrum of cardiovascular diseases and compared with the echocardiographic measurement of left atrial dimension (LAD). Data analysis showed a high degree of correlation between the echocardiographic measurement of LAD and the EKG criteria for LAE. The magnitude of the P terminal force in lead V1 was the most specific of the EKG criteria evaluated, while the P/P-R segment ratio was least specific. Concordance between the two methods of measuring left atrial size increased when multiple positive EKG criteria were present.

Radiosensitization of a human cell line lacking repair replication

A human cell line has been isolated that is deficient in X-ray-induced repair replication. The slope of the radiation survival curve is greater in the presence of the anthracycline antibiotic, adriamycin. The results suggest that radiosensitization by DNA-binding drugs is more probably related to DNA strand breakage phenomena than to the polymerase step of excision-repair.

Adhesion of cultured fibroblasts to insoluble analogues of cell-surface carbohydrates

Animal cells are coated with complex carbohydrates. Insoluble analogues of these substances were prepared by coupling monosaccharides to Sephadex beads (crosslinked dextran), and the interactions between these derivatives and three established cell lines were studied. A virally transformed fibroblast, simian virus 40-transformed 3T3 cells, adhered to the beads derivatized with D-galactose, but did not adhere to the corresponding beads derivatized with D-glucose or N-acetyl-D-glucosamine. Cells that adhered to the galactose-beads appeared to initiate a nucleation process in that they became more adhesive towards the cells in suspension, leading to the formation of large aggregates containing both cells and galactose-beads. The results suggest that specific carbohydrates are involved in the processes of cell recognition or cell adhesion, or both.