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A R Dal Nogare

Publications and source records attributed to A R Dal Nogare.

18 recordsLinked to original sources
PubMed1998

Conserved sequences in enzymes of the UDP-GlcNAc/MurNAc family are essential in hamster UDP-GlcNAc:dolichol-P GlcNAc-1-P transferase.

The UDP-GlcNAc/MurNAc family of eukaryotic and prokaryotic enzymes use UDP-GlcNAc or UDP-MurNAc-pentapeptide as donors, dolichol-P or polyprenol-P as acceptors, and generate sugar-P-P-polyisoprenols. A series of six conserved sequences, designated A through F and ranging from 5 to 13 amino acid residues, has been identified in this family. To determine whether these conserved sequences are required for enzyme function, various mutations were examined in hamster UDP-GlcNAc:dolichol-P GlcNAc-1-P transferase (GPT). Scramble mutations of sequences B-F, generated by scrambling the residues within each sequence, demonstrated that each is important in GPT. While E and F scrambles appeared to prevent stable expression of GPT, scrambling of B-D resulted in GPT mutants that could be stably expressed and bound tunicamycin, but lacked enzymatic activity. Further, the C and D scramble mutants had an unexpected sorting defect. Replacement of sequences B-F with prokaryotic counterparts from either the B.subtilis mraY or E.coli rfe genes also affected GPT by preventing expression of the mutant protein (B, F) or inhibiting its enzymatic activity (C-E). For the C-E replacements, no acquisition of acceptor activity for polyprenol-P, the fully unsaturated natural bacterial acceptor, was detected. These studies show that the conserved sequences of the UDP-GlcNAc/MurNAc family are important, and that the eukaryotic and prokaryotic counterparts are not freely interchangeable. Since several mutants were efficiently expressed and bound tunicamycin, yet lacked enzymatic activity, the data are consistent with these sequences having a direct role in product formation.

Amino Acid Sequence↗
PubMed1994

Buccal cell carbohydrates are altered during critical illness.

Cell-surface carbohydrates mediate the adherence of many pathogenic bacteria to epithelial cells. Because gram-negative bacteria adhere especially well to respiratory epithelial cells obtained from severely ill patients, we compared respiratory epithelial cell-surface carbohydrate levels of normal subjects with those of critically ill patients. Lectins were used to quantitate the amount of mannose, galactose, fucose, and sialic acid on buccal and tracheal cells. Fifteen critically ill patients, 20 normal subjects, and 10 minimally ill hospitalized patients were studied. The severely ill patients' buccal cells had decreased amounts of sialic acid and galactose. No differences were found between the normal and critically ill patients' tracheal-cell carbohydrates. The results obtained with a sialic acid-specific lectin were confirmed by direct measurement of buccal-cell sialic acid. We conclude that severely ill patients have decreased amounts of galactose and sialic acid on their upper-airway epithelial cells, and that loss of these two monosaccharides may explain the high prevalence of gram-negative bacterial colonization and pneumonia in the critically ill.

Adult↗
PubMed1994

Increased salivary exoglycosidase activity during critical illness.

Exoglycosidases remove peripheral monosaccharides from oligosaccharides and hence are capable of altering respiratory epithelial cell surface carbohydrates. We obtained saliva and tracheal secretions from 34 critically ill patients and saliva from 23 healthy subjects. Compared with the normal subjects, the ill patients had large amounts of mannosidase, fucosidase, hexosaminidase, and sialidase activity. Sialidase increased adherence of several gram-negative bacteria to epithelial cell monolayers and pure glycoproteins. Pretreatment of glycoproteins with some of the patients' saliva samples also increased bacterial adherence to the glycoproteins. We conclude that respiratory tract exoglycosidase activity increases during critical illness. By altering normal cell surface carbohydrates, exoglycosidases may facilitate bacterial adherence and respiratory tract colonization.

Bacterial Adhesion↗
PubMed1994

Treatment of AIDS-related spontaneous pneumothorax. A decade of experience.

Spontaneous pneumothorax (SP) secondary to the acquired immunodeficiency syndrome (AIDS) emerged in the decade of the 1980s. It has become an increasingly difficult condition to treat successfully both for the pulmonary internist and the surgeon. AIDS-related SP is complicated by a virulent form of necrotizing subpleural necrosis that results in diffuse air leaks that are refractory to the standard, traditional forms of therapy which enjoy good success for SP related to classic subpleural bleb disease. AIDS-related SP carries a high mortality rate despite treatment, independent of the development of primary respiratory failure. In reviewing our experience of 46 patients from a single institution treated over the past 10 years, we found that due to the high primary and secondary treatment failure rates, an aggressive stepped-care management of large-bore intercostal tube drainage, chemical pleurodesis, and early video-assisted talc poudrage is recommended in an attempt to shorten the duration of hospital stay, hospital costs, and mortality.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Sleep apnea.

Explore the source record for details and available documents.

Airway Obstruction↗
PubMed1992

Chinese hamster ovarian cell glycoproteins that mediate type 1 piliated gram-negative bacterial adherence.

We used Chinese hamster ovary (CHO) cell lines to define the structures of glycoproteins responsible for Type 1 piliated bacterial adherence. CSH 50 Escherichia coli, a Type 1 piliated bacteria, adhered significantly better than an isogenic nonpiliated E. coli to all CHO lines tested. CSH 50 E. coli adhered least well to CHO cells expressing intact complex type oligosaccharides on cell surface glycoproteins. CSH 50 adherence increased when shorter oligosaccharides were present and was maximal when mannose groups were present in terminal, nonreducing positions. Five high mannose type glycoproteins, with molecular weights of 79, 75, 55, 50, and 37 kD, were identified as high affinity ligands for Type 1 piliated bacteria. Our results suggest that alterations in cell surface carbohydrates may increase adherence of Type 1 piliated gram-negative bacteria to cells.

Animals↗
PubMed1992

Respiratory epithelial carbohydrate levels of rats with gram-negative bacillary colonization.

One mechanism by which severe illness or stress might facilitate adherence and colonization of GNB to respiratory epithelium is by altering epithelial cell surface carbohydrates. To investigate this possibility we used radiolabeled lectins to quantitate carbohydrate levels on intact buccal and tracheal epithelium. A rat model of GNB colonization, in which renal infarction was performed to produce colonization, was used. Buccal and tracheal epithelial surface carbohydrate levels from normal rats and rats 48 hours after renal infarction were compared. Buccal and tracheal epithelium from the renal infarction animals had decreased amounts of sialic acid and fucose, and decreased levels of these sugars occurred at the same time that heavy oropharyngeal GNB colonization developed. Tracheas obtained from the infarcted animals bound three times more Type 1 piliated GNB than normal tracheas. Sialic acid and fucose levels are decreased early after stress, and we speculate that altered epithelial carbohydrates may predispose to GNB colonization by exposing binding sites for GNB.

Animals↗
PubMed1991

Characteristics of aerobic gram-negative bacteria colonizing critically ill patients.

Adherence of gram-negative bacteria (GNB) to epithelial surfaces is important for GNB colonization to occur. Pili, rodlike structures projecting from the outer membrane of GNB, and GNB surface hydrophobicity have been shown to enhance GNB adherence. We investigated the types of pili and the hydrophobicity of aerobic GNB colonizing the stomach, oropharynx, and trachea of critically ill patients. Piliation and hydrophobicity of oral, tracheal, and gastric GNB were compared with that of commensal GNB isolated from patients' rectums. Significantly more oropharyngeal than rectal GNB were piliated, and the most common type of pili present was type 1, or mannose-sensitive pili. Mannose-resistant and P pili were present less often, and no colonizing GNB had S pili. Colonizing GNB were hydrophilic rather than hydrophobic, and no differences in hydrophobicity were noted between colonizing GNB and rectal isolates. Our results suggest that pili may be important for oropharyngeal GNB colonization.

Bacterial Adhesion↗
PubMed1991

Septic shock.

Septic shock (SS) is the most common type of shock encountered by internists, and its prevalence appears to be increasing. SS complicates all types of infections. The hemodynamic characteristics of SS include a low systemic vascular resistance and an elevated, but relatively inadequate, cardiac output. A cardiomyopathy frequently occurs. The major endogenous mediator of SS is tumor necrosis factor, and interleukins-1 and -2 may also contribute. Important secondary phenomena include release of platelet activating factor, vasodilator prostaglandins, and upregulation of adhesion molecules on polymorphonuclear leukocytes and endothelial cells. Current therapy is often ineffectual, and potentially promising new therapeutic approaches are reviewed.

Animals↗
PubMed1990

Characteristics of alveolar macrophages in an animal model of resolving pulmonary inflammation.

Little is known about the functions of alveolar macrophages during the later resolving phases of pulmonary inflammation. We have used an animal model of resolving pulmonary inflammation to obtain inflammatory macrophages (IMs) and have compared several IM functions with those of resident macrophages (RMs). IMs were frequently peroxidase positive and contained large amounts of myeloperoxidase activity. IMs also contained significant amounts of a serine protease type of elastase. The procoagulant activity of IMs was less than that of RMs, and IMs exhibited increased plasminogen activator activity when incubated on fibrin matrices. IMs also degraded fibrin directly, without plasminogen, and this activity was due to two different enzymes of molecular weights 39 and 63 kD that were present in IM granules and plasma membranes. These results suggest that, in vivo, IMs take up PMN enzymes and alter their procoagulant and fibrinolytic activity to maximize fibrin removal. These IM functions may be important for successful resolution of inflammatory injury.

Animals↗
PubMed1990

Type I pili mediate gram-negative bacterial adherence to intact tracheal epithelium.

We have investigated the role of pili in mediating gram-negative bacterial adherence to an intact tracheal epithelium. Type 1 pili, but not P or Pseudomonas pili, markedly increased bacterial adherence. The adherence-promoting effect of Type 1 pili was due to the mannose-binding Type 1 pili adhesin, as both alpha-methyl mannoside and concanavalin A blocked adherence of Type 1 piliated bacteria. The Type 1 pili-binding site on tracheal epithelium appears to be a mannose-containing glycoprotein. Clearance of Type 1 piliated bacteria from the lung parenchyma was assessed by depositing the bacteria into a lobe; no difference in clearance rates between Type 1 and nonpiliated bacteria was present. Type 1 pili may enhance the ability of gram-negative bacteria to adhere to and colonize the lower respiratory tract.

Adhesins, Bacterial↗
PubMed1990

Cytolytic human lung lymphocytes: characterization of intragranular protease content and response to interleukin-2.

Cytolytic lymphocytes play an important role in defense against viral and neoplastic disease. Integral to the function of these cells is the content of lysosomal granules. Recent attention has focused on a family of proteases present in the granules of natural killer (NK) cells, interleukin-2 (IL-2)-activated NK cells (LAK cells), and cytotoxic T lymphocytes (CTL). In the current investigation, lymphocytes were obtained from human lung parenchyma and peripheral blood. Following activation with IL-2, both groups of lymphocytes exhibited comparable cytolytic activity against K562 targets. Lysosomal granules obtained from these cells contained two serine proteases with molecular weights of 30 and 28 kD. These proteases were capable of hydrolyzing benzyloxycarbonyl-L-lysine thiobenzyl ester (BLT-ester), a substrate of cytolytic lymphocyte proteases. When compared to blood, unactivated lung lymphocytes contained significantly higher levels of protease content. Although IL-2 produced a significant increase in blood lymphocyte protease content, no change in lung lymphocyte granule protease activity was observed. We conclude that cytolytic lung lymphocytes contain high levels of lysosomal granule protease but differ from blood lymphocytes in the ability to increase protease content following activation with IL-2. The high level of protease content in cytolytic lung lymphocytes suggests that these cells could produce local tissue injury during the release of lysosomal granules.

Cytoplasmic Granules↗
PubMed1990

Fibronectin is not detectable on the intact buccal epithelial surface of normal rats or humans.

Fibronectin (FN) has been postulated to prevent gram-negative bacillary (GNB) colonization of the oropharynx by covering epithelial cell GNB receptors. We investigated the distribution of FN along the luminal surface of oropharyngeal epithelium in animals and humans. Examination of buccal epithelial biopsies obtained from normal rats revealed no luminal surface FN by either immunofluorescent or immunoperoxidase staining. Extraction of epithelial surface proteins and quantitation of FN by rocket immunoelectrophoresis and electrophoretic transfer to nitrocellulose followed by immunologic detection also detected no FN from normal animals' oropharyngeal biopsies. Buccal epithelial biopsies from three normal humans were examined for FN using electrophoretic transfer to nitrocellulose followed by immunologic detection, and no FN was demonstrable. Our results suggest that FN is not present on the oral epithelial surface of healthy rodents or humans, and that FN may not be involved in the pathogenesis of bacillary colonization.

Animals↗
PubMed1989

Adult respiratory distress syndrome.

The Adult Respiratory Distress Syndrome (ARDS) is a fulminant form of respiratory failure affecting many seriously ill patients. The early manifestations of ARDS are caused by increased permeability of the alveolo-capillary barrier leading to pulmonary edema, stiff lungs, and a large right-to-left intrapulmonary shunt. Polymorphonuclear leukocytes (PMNS) are involved in the pathogenesis of most ARDS, and multiple PMN mechanisms can effect pulmonary injury; interactions between PMN adherence, proteolytic enzyme release, and oxygen radical production are emphasized. ARDS therapy remains largely supportive and has had little impact on mortality. The complications of infection and multiorgan failure play important roles in determining ARDS outcome.

Adrenal Cortex Hormones↗
PubMed1988

Bacterial species-dependent inhibition of human granulocyte elastase.

Lung infection with Streptococcus pneumoniae causes the recruitment of many granulocytes (PMN) to the alveoli, but little damage to lung structure ensues, as opposed to infections with other bacterial species that induce a similar PMN response and cause lung damage. Elastase, a proteolytic enzyme of PMN, has been implicated as an agent of lung injury. We studied the interaction of different bacterial species with human PMN in vitro to determine if PMN elastase activity is affected by the species of bacteria ingested. Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, and S. pneumoniae were grown, opsonized, and incubated with human PMN. After 1 h of incubation, intracellular and extracellular elastase activity was measured. S. pneumoniae reduced PMN elastase activity by 48%, whereas the other 3 species tested had only minimal effects on elastase activity. Loss of elastase activity occurred with S. pneumoniae: PMN ratios as low as 2:1. Adherence or ingestion of bacteria by the PMN was necessary for the decrease in elastase activity to occur; interventions that decreased phagocytosis, such as not opsonizing the bacteria, pretreatment of the PMN with cytochalasin B, and separation of bacteria from PMN by 0.22-mu filters, increased elastase activity. ELISA and Western blot analysis of elastase levels in these experiments suggested that normal amounts of elastase were present. Thus, the loss of elastase activity we observed may be due to an elastase inhibitor present in S. pneumoniae.

Bacterial Physiological Phenomena↗
PubMed1987

Increased salivary elastase precedes gram-negative bacillary colonization in postoperative patients.

The upper airway epithelium is coated with fibronectin, a glycoprotein that covers receptor sites for gram-negative bacteria and prevents them from colonizing the oropharynx. We investigated the identity of salivary proteolytic enzymes capable of degrading fibronectin in a group of 16 patients who had elective cardiac surgery. Six patients became colonized with gram-negative bacteria (Group C) and 10 did not (Group NC). Salivary elastase activity was low in both groups preoperatively. Twenty-four hours after surgery, salivary elastase activity increased in Group C, and it remained elevated at 48 and at 72 h. Fibronectin digestive activity of the saliva of patients in Group C was also increased within 24 h of surgery, and salivary elastase and fibronectin digestive activity were highly correlated (r = 0.86, p less than 0.001). Enzyme inhibition experiments showed that most of the fibronectin digestive activity was due to elastase from polymorphonuclear cells (PMN), and the molecular weight of the salivary enzyme digesting fibronectin was 30,000 daltons (similar to the molecular weight of elastase). Levels of antileukoprotease, the major elastase inhibitor in saliva, were normal in patients with increased elastase activity. We conclude that salivary elastase is of PMN origin, increases prior to gram-negative bacillary colonization of the pharynx, and is responsible for most of the fibronectin digestive activity of the saliva.

Cardiac Surgical Procedures↗
PubMed1986

The effects of hydralazine on exercise capacity in pulmonary hypertension secondary to chronic obstructive pulmonary disease.

Vasodilator therapy of pulmonary hypertension has been shown to improve hemodynamics in some patients, but the clinical benefits of this therapy have not been evaluated. We studied 14 patients who had pulmonary hypertension secondary to chronic obstructive pulmonary disease to determine the effect of hydralazine treatment on hemodynamics and maximal exercise. Baseline exercise in these subjects showed an abnormal pattern of excessive tachycardia and low stroke volumes, and the stroke volume correlated inversely with the pulmonary vascular resistance during exercise (r = -0.61, p less than 0.05). After 48 h of hydralazine there were decreases in the mean pulmonary artery pressure (43 +/- 8 to 38 +/- 8 mmHg, p less than 0.06) and pulmonary vascular resistance (3.97 +/- 0.97 to 2.88 +/- 1.28 units, p less than 0.05) measured at maximal exercise, and the maximal cardiac output was increased (8.05 +/- 2.57 to 10.13 +/- 2.79 L/min, p less than 0.05), but there was no change in symptom-limited maximal oxygen consumption (747 +/- 266 to 752 +/- 244 ml/min, p = NS). Significant increases in resting and maximal exercise values of minute ventilation and mixed venous oxygen tension were also noted with hydralazine. Repeat exercise testing after 2 to 4 months of chronic hydralazine therapy demonstrated no change in symptom-limited maximal oxygen consumption. We conclude that vasodilator therapy with hydralazine, although hemodynamically efficacious, does not increase exercise capacity in patients with severe chronic obstructive pulmonary disease and secondary pulmonary hypertension.

Exercise Test↗