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A Cooper

Publications and source records attributed to A Cooper.

At least 271 records · Page 15Linked to original sources
PubMed1989

Characterization of the yeast KEX1 gene product: a carboxypeptidase involved in processing secreted precursor proteins.

We have identified and partially characterized the Saccharomyces cerevisiae KEX1 gene product, Kex1p, to assess its role in processing secreted protein precursors. Anti-Kex1p antibodies identified a 113-kilodalton protein that was absent in cells in which the KEX1 gene has been disrupted and that was more abundant in cells overexpressing the KEX1 gene. Kex1p was found to be a membrane-associated glycoprotein with N-linked carbohydrate. The N-linked oligosaccharide(s) was modified in a progressive manner after synthesis, causing the glycoprotein to slowly increase in mass to 115 kilodaltons. After a Kex2p-mediated cleavage event at specific pairs of basic amino acids, alpha-factor and K1 killer toxin precursors have COOH-terminal dibasic residue extensions and require a carboxypeptidase B-like enzyme to process the precursors to maturity. A carboxypeptidase activity, with apparent specificity for basic amino acids, was detected in KEX1 cells. Disruption of the KEX1 gene abolished this activity, while overexpression of KEX1 increased it. Our results provide biochemical evidence consistent with earlier genetic work, that KEX1 encodes a serine carboxypeptidase involved in the processing of precursors to secreted mature proteins.

Base Sequence↗
PubMed1989

Kinetics of pulmonary platelet deposition and clearance during thrombin-induced microembolism in rabbits.

Using 111In-labeled autologous platelets, we studied the kinetics of pulmonary platelet deposition and clearance in relation to hemodynamic and structural events during thrombin-induced pulmonary microembolism in rabbits. Autologous platelets were radiolabeled and returned to animals prior to infusion of thrombin (100 units/kg over 15 min) (n = 20) or saline (n = 6). All animals were pretreated with tranexamic acid, an inhibitor of fibrinolysis. Thrombin-treated animals manifested progressive increases in mean pulmonary platelet activity, reaching a maximum of 38% above baseline (p less than .0001), whereas no change was observed in saline-treated controls. Animals that died during, or immediately following, thrombin infusion manifested significantly greater increases in pulmonary platelet uptake (mean 1.55 +/- 0.47 times baseline), compared to surviving animals (1.14 +/- 0.16; p less than .05 survivors vs. nonsurvivors). In surviving animals, following cessation of thrombin, pulmonary platelet activity cleared gradually, with a half-time of approximately 12 min. Thrombin reduced circulating platelet counts (p less than .001), increased mean pulmonary artery pressure (13 +/- 3 mm Hg to 18 +/- 6 mm Hg; p less than .0001), and reduced mean systemic arterial pressure (55 +/- 10 mm Hg to 44 +/- 7 mm Hg; p less than .001). The time courses of these events approximated that of thrombin-induced pulmonary platelet uptake. Furthermore, the increase in pulmonary artery pressure occurred predominantly in the group of animals in which the increase in pulmonary radiolabeled platelet activity exceeded the median value of 20%. Postmortem histology showed extensive pulmonary thrombus extending from small arterial to capillary levels in animals that died during, or immediately following, thrombin infusion, but not in surviving animals. Our findings suggest that platelet aggregation plays an important role in the pathogenesis of hemodynamic change following thrombin-induced pulmonary embolization.

Animals↗
PubMed1988

First trimester prenatal diagnosis of Sandhoff's disease.

Chorionic villus sampling was performed on two patients with a previous family history of Sandhoff's disease. Total beta-hexosaminidase (Hex) activity in case 1 was within the normal range (case 1: 6365 mumol/h/g protein; control range: 3227-24 495 mumol/h/g protein). The beta-hexosaminidase isoenzyme pattern was found to be normal. These results were confirmed on cultured amniotic fluid cells. In case 2, the total Hex activity was 672 mumol/h/g protein, i.e., 7 per cent of the control mean (10,085 mumol/h/g protein), and chromatography demonstrated that more than 50 per cent of this activity was due to the abnormal isoenzyme beta-hexosaminidase S (Hex S). The fetus was predicted to be affected by Sandhoff's disease and this was confirmed on fetal tissues after termination of pregnancy. This study demonstrates that a fetus affected by Sandhoff's disease can be reliably diagnosed during the first trimester of pregnancy.

Adult↗
PubMed1988

Human beta-mannosidase deficiency: biochemical findings in plasma, fibroblasts, white cells and urine.

Marked deficiencies of beta-mannosidase activity were demonstrated in plasma, leukocytes, fibroblasts and urine of a patient with beta-mannosidosis, similar deficiencies were observed in the proband's sibling. All other lysosomal enzymes measured, including sulphamidase, exhibited normal activity. Both parents showed reduced plasma and leukocyte beta-mannosidase activity. Urinary glycosaminoglycan excretion was normal but TLC of urinary oligosaccharides revealed an abnormal band with the mobility of a disaccharide. This finding was confirmed by Bio-Gel P2 column chromatography. Further purification of this compound revealed two disaccharides, both of which yielded mannose and glucosamine following acid hydrolysis and mannose and N-acetylglucosamine following enzymic digestion. These two compounds are thought to be structural isomers of the disaccharide Man beta-GlcNAc.

Adult↗
PubMed1988

Resection with primary anastomosis for necrotizing enterocolitis: a contrasting view.

Resection with primary anastomosis is currently being advocated for treatment of infants with necrotizing enterocolitis. To determine whether our own data would support such an approach, we reviewed retrospectively our experience with this disease since 1974. Since that time, 173 infants have been admitted for treatment of advanced (surgical) disease in its acute phase, of whom 143 underwent resection for cure; the remainder either underwent laparotomy with decompression (3), laparotomy with drainage (3), laparotomy alone (14), died at operation (1), or could not be resuscitated sufficiently to withstand operation (9). Excluded were patients who underwent operative repair of late stricture (6), all of whom survived with no morbidity. Among those resected for cure, 27 infants were carefully selected by the operating surgeon for treatment by means of resection with primary anastomosis, based on the limited and apparently discrete nature of their disease; in three the procedure was combined with a decompressing enterostomy. In the majority of cases (14), the disease was found to involve multiple areas of intestine, but was limited to a particular anatomic region, usually distal ileum and/or ascending colon; in the remainder, it was due to discrete ileal or jejunal perforation or ulcer. Overall survival among those resected for cure was 65% (96/143). It was 48% (13/27) among those treated by means of resection with primary anastomosis but 72% (83/116) among those who underwent resection with enterostomy. However, if the early years of the series (1974 to 1976) are excluded, a time when resection with enterostomy had not yet become established as standard therapy, overall survival was 77% (77/100), 64% (9/14) among those anastomosed primarily.

Colon↗
PubMed1988

Major blunt abdominal trauma due to child abuse.

We reviewed 15 years' experience with childhood trauma at two hospitals in different cities, one a city hospital, the other a children's hospital, to learn the extent, circumstances, presentations, and consequences of major blunt abdominal trauma due to child abuse. Some 10,000 children admitted to these hospitals for treatment of injuries from 1972 through 1986 provided the basis for the study; the incidence and severity of pediatric trauma at the two hospitals was similar, in that 13% of the visits to both hospitals' emergency rooms were for trauma, of which 5% resulted in admission. Major blunt abdominal trauma due to child abuse accounted for 22 of these cases, six at the former, 16 at the latter, and represented less than 0.50% of all abused children seen at both institutions. The average age was 24 mo; 14 were boys and eight were girls. In only two instances was the family unit intact; in both, the child was abused by the babysitter. Otherwise, the father, or the mother's "boyfriend," was responsible. Overall mortality was 45%, and was related both to type of injury and presenting signs. Of one who presented with an epigastric mass due to a pancreatic hematoma, none died; the pseudocyst which subsequently developed resolved on bowel rest and TPN. Of three who presented with bilious vomiting due to duodenal hematoma, none died; one required operative evacuation. Of five who presented with peritonitis due to duodenojejunal rupture, one died; this child presented greater than 24 hr following injury in profound septic shock. Of three who presented with hypovolemia due to moderate hemorrhage, none died; the former two were managed conservatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Injuries↗
PubMed1988

Characterization of apoB, E receptor function in the luteinized ovary.

Recent findings from this laboratory have led to the suggestion that the hormone-producing cells of the rat luteinized ovary in situ may obtain a large share of low density lipoprotein (LDL) cholesterol without actually internalizing the intact lipoprotein particles. We have shown that the lipoproteins are trapped at the surface of the luteal cells in a rich network of "microvillar channels" and have theorized that these channel membranes, with their large surface area for interacting with lipoprotein particles, may function in the cholesterol transfer process. In the current study, we try to establish what proportion of the human (h)LDL-cholesterol transfer in the in situ perfused tissue occurs by a classical apoB, E receptor-mediated process versus a surface extraction process. We examine the tissue for the presence of apoB, E receptors, and characterize the structural/functional interaction of hLDL with the apoB, E receptor utilizing a variety of modified hLDL particles as probes. Then, using nonmetabolizable radiolabels for both the protein and cholesteryl ester moieties of these LDL probes, we attempt to quantify the extent to which apoB, E receptors in the ovary contribute to the uptake of hLDL-cholesterol during steroidogenesis. Our experiments show that although the luteinized ovary contains apoB, E receptor protein, hLDL interacts with the tissue atypically. That is, despite modifications of LDL amino acid residues to prevent interaction with the apoB, E receptor, the modified ligands continue to contribute cholesterol for luteal cell internalization and/or steroidogenesis. We conclude, therefore, that in this tissue much of the LDL-cholesterol is not delivered by the apoB, E receptor pathway.

Animals↗
PubMed1988

Monoclonal antibodies that recognize distinct epitopes of the macrophage type three complement receptor differ in their ability to inhibit binding of Leishmania promastigotes harvested at different phases of their growth cycle.

The macrophage receptor CR3 has been shown by several investigators to be involved in the binding of Leishmania promastigotes to host macrophages. This receptor is known to recognize iC3b and to mediate direct lectin-like attachment of particles such as yeast zymosan. In the present study, two anti-CR3 monoclonal antibodies, M1/70 and 5C6, which ligate different epitopes of murine CR3, have been used in conjunction with sodium salicyl hydroxamate (Saha; inhibits covalent ester linkages of C3 to an activator surface) to block binding of L. donovani and L. major promastigotes harvested at different phases of their growth cycle. M1/70 inhibited all promastigote binding. 5C6 and Saha blocked in parallel only the binding of peanut agglutinin (PNA)-positive late log and early stationary phase parasites. These results suggest that the binding PNA-positive parasites to CR3 is iC3b-mediated, while entry of the more infective PNA-negative late stationary phase promastigotes into host macrophages may involve direct lectin-like binding to CR3.

Animals↗
PubMed1987

Malignant ovarian tumors in children and adolescents.

Eighteen patients aged 4 to 18 years (median, 10 years) were treated at the Children's Cancer Research Center of The Children's Hospital of Philadelphia (CHP) from September 1973 to September 1983 for malignant ovarian tumors. The pathologic categories were endodermal sinus tumor (eight patients), embryonal carcinoma (three patients), pure dysgerminoma (three patients), adenocarcinoma (three patients), and malignant granulosa-cell tumor (one patient). In 1973 and 1975, respectively, two patients with endodermal sinus tumors were treated with surgical removal with or without radiation therapy (RT) and chemotherapy with vincristine (Vc) and actinomycin D+ cyclophosphamide + Adriamycin (Adria Laboratories, Columbus, OH) (ACAdr); both developed local recurrence within 12 months and died of tumor. Since 1977, four of six patients with endodermal sinus tumors have been managed successfully with surgery followed by chemotherapy with cisplatin (P), bleomycin (B), vinblastine (Vb), and ACAdr; none received RT. One died of recurrent tumor and the other died of congestive heart failure attributed to Adriamycin (Adr). All three patients with embryonal carcinoma were well after surgical excision alone (one patient) or surgery and chemotherapy with cisplatin + bleomycin + vinblastine (PBVb) + ACAdr (two patients). Treatment of the remaining seven patients included excision alone (two patients) or excision and chemotherapy (five patients) with various combinations of Vc, ACAdr, and P. One patient with granulosa-theca cell tumor also received whole abdominal RT (3000 rad by external beam), and died of congestive heart failure attributed to Adr. The other six children were free of detectable tumor 16 months to 8 years from diagnosis. Chemotherapy with PBVb and actinomycin D + cyclophosphamide (AC) should be used in the postoperative management of young persons with malignant ovarian tumors. Adr is of doubtful value and may be considerably toxic. RT is of limited use and usually is not indicated.

Adenocarcinoma↗
PubMed1987

Aryl sulphatase isoenzymes of chorionic villi: implications for prenatal diagnosis.

Prenatal diagnosis of metachromatic leucodystrophy (MLD) is based on demonstrating a deficiency of aryl sulphatase A (ASA) in the fetus. To evaluate the place of chorionic villus sampling for prenatal diagnosis of this condition, the properties of ASA were compared in chorionic villi and cultured skin fibroblasts. Considerable differences with respect to pH optimum, Km values and linearity with incubation time were found. These differences can be explained by the presence of aryl sulphatase C (ASC), a major component in chorionic villi and placenta. This isoenzyme was shown to have activity towards p-nitrocatechol sulphate (NCS) thereby interfering in the colorimetric assay most often used to detect MLD (Baum et al., 1959)

Cerebroside-Sulfatase↗
PubMed1987

Krabbe's disease: first trimester diagnosis confirmed on cultured amniotic fluid cells and fetal tissues.

Chorionic villi obtained during the first trimester from a pregnancy at risk for Krabbe's disease were shown to have reduced cerebroside-beta-galactosidase (E.C.3.2.1.46) activity using the artificial substrate trinitrophenylaminolauryl galactocerebroside (TNPAL-galactocerebroside). Assay of this enzyme in cultured amniotic fluid cells following amniocentesis, performed at the patient's request confirmed the diagnosis. Termination of pregnancy was performed and subsequent enzyme studies of the fetal tissues were consistent with the diagnosis of Krabbe's disease, thus confirming that chorionic villi can be used for first trimester diagnosis of this condition.

Amniocentesis↗
PubMed1987

Acid beta-mannosidase of human plasma: influence of age and sex on enzyme activity.

Optimum conditions for assay of human plasma beta-mannosidase activity were determined. Maximum activity was observed at pH 3.0-3.4, the apparent Km was 0.9 mmol L-1 and enzymatic hydrolysis was linear for at least 60 min. Assays were performed on plasma from two siblings with the recently described condition beta-mannosidosis and their parents and controls. Both beta-mannosidosis patients showed a marked deficiency of beta-mannosidase activity. Control samples showed no variation between sexes (p greater than 0.05) but enzyme activity varied significantly with age (p less than 0.05). Highest activity was observed in the 0-1 year age group, activity then decreasing to adulthood, Both mother and father of the affected individuals showed reduced activity (34% and 53%, respectively) compared to age-matched controls. This suggests that heterozygote detection in this condition is possible using plasma, provided the variation of activity with age is taken into consideration.

Adolescent↗
PubMed1987

Fifteen years' experience with penetrating trauma to the head and neck in children.

To determine the extent and consequences of penetrating trauma to the head and neck in children, as well as the safety and efficacy of selective management of penetrating wounds of the face and neck, we reviewed our experience with these injuries since 1970. During this interval, 45 children aged 2 to 17 years were admitted for treatment of 37 missile wounds (MW) and eight stab wounds (SW). Most patients reached the hospital within 30 minutes of injury. The greatest single number of these injuries were due to accidents; violent crimes accounted for the remainder of injuries in which a motive for attack was known. Craniotomy was performed in neurologically viable patients only; neck exploration was reserved for those patients who presented with profuse hemorrhage, an expanding or pulsatile hematoma, respiratory distress, or violation of the esophagus, trachea, or great vessels seen on fluoroscopy, endoscopy, or angiography. Overall survival was 87% (MW 84%, SW 100%). Three of the nonsurvivors presented in extremis with gunshot (GSW) wounds to the head, and died shortly thereafter, while two who presented with similar injuries survived craniotomy but died subsequently from irreversible brain damage; one presented in shock due to massive hemorrhage (internal jugular vein transection flush with the base of the skull) and exsanguinated during attempted repair. Among the 39 survivors, 15 sustained multiple wounds, but only two presented in shock, due in both instances to tension pneumothorax. Soft tissue injuries of the scalp, face, and neck accounted for 36 of the 39 nonfatal wounds; five of these involved major cervical structures, but only four required immediate exploration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗