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Biomedical subjects

M G Marin

Publications and source records attributed to M G Marin.

At least 37 records · Page 2Linked to original sources
PubMed1993

Oxidant injury alters barrier function of ferret tracheal epithelium.

To understand the influence of oxidant stress on the barrier function of airway epithelium, we conducted studies to determine the effects of chemically generated reactive oxygen species on permeability, permselectivity, and active ion transport of ferret trachea. We examined the consequences of oxidant injury using ferret trachea mounted in Ussing-type chambers and bathed with a modified Krebs-Henseleit solution containing mannitol and xanthine. We added xanthine oxidase to the luminal bathing solution, which reacted with the xanthine to generate reactive oxygen species. Tissue electrical conductance and short-circuit current were significantly increased after the addition of xanthine oxidase. Simultaneous measurement of mannitol flux (as a marker of paracellular conductance) and the backflux of chloride (lumen to submucosa) demonstrated a significant oxidant-induced increase in mannitol flux and backflux of chloride. Mannitol flux and the backflux of sodium (submucosa to lumen) also increased after oxidant stress. Comparison of the diffusion of sodium relative to the diffusion of chloride in relation to predicted diffusion in free solution indicated that the paracellular pathway was cation selective after oxidant stress. Active ion transport, as reflected by the short-circuit current, was significantly increased transiently after oxidant stress. Studies with furosemide, amiloride, and diphenylamine-2-carboxylate are suggestive that oxidant stress transiently stimulates the Na-K-ATPase. These studies demonstrated that exposure to reactive oxygen species significantly altered the permeability of the tracheal epithelium as well as active ion transport.

Animals↗
PubMed1993

Simultaneous legionellosis and invasive aspergillosis in an immunocompetent patient newly treated with corticosteroids.

Invasive pulmonary aspergillosis (IPA), although unusual, has been recognized in the immunocompetent host. Several cases of IPA with rapidly progressive respiratory failure have been reported in patients receiving short-term corticosteroid therapy for chronic obstructive pulmonary disease. Atypical pneumonia caused by dual infection with Legionella pneumophila and Mycoplasma pneumoniae has also been reported. We report an unusual case of simultaneous L pneumophila pneumonia and IPA in an asthma patient with suspected allergic bronchopulmonary aspergillosis newly treated with corticosteroids.

Adrenal Cortex Hormones↗
PubMed1992

Hepatitis C virus RNA and antibody response in the clinical course of acute hepatitis C virus infection.

Hepatitis C virus RNA, anti-hepatitis C virus immune response and biochemical markers of liver injury were investigated in 17 patients with acute non-A, non-B hepatitis. At the first observation, 1 to 3 wk from the clinical onset, all patients had hepatitis C virus RNA in their serum, and most (15 of 17) were positive for second-generation anti-hepatitis C virus enzyme immunoassay. Follow-up serum samples were available for 10 patients. The rate of recombinant immunoblot assay-confirmed anti-hepatitis C virus enzyme immunoassay reactivities increased from 67% in the first 3 wk to 86% after 21 wk. Elevated ALT levels were associated with hepatitis C virus RNA positivity in most of cases, but the viral nucleic acid was also detected in sera with normal or slightly increased enzyme values. None of the single antibodies tested were related to hepatitis C virus RNA positivity or to the clinical phase of the infection. Therefore hepatitis C virus RNA determination might provide important additional information as compared with anti-hepatitis C virus markers, allowing earlier diagnosis, discrimination of active infection and, possibly, prognostic evaluation.

Acute Disease↗
PubMed1992

Arachidonic acid increases cholinergic secretory responsiveness of ferret tracheal glands.

The purpose of this study was to determine if arachidonic acid could alter ferret tracheal gland secretory responsiveness to a cholinergic agonist. We prepared glandular explants and incubated the explants in medium containing [3H]glucosamine. Secretory responsiveness was expressed as the percent change in basal secretion of acid-precipitable [3H]glucosamine-labeled glycoconjugates induced by the addition of agonist with and without arachidonic acid [mean +/- SE (n)]. Addition of 10(-3) M arachidonic acid caused a significant increase in secretion [28 +/- 6% (n = 6)] compared with untreated control tissues [-10 +/- 4% (n = 7), P less than or equal to 0.05]. Carbachol (10(-7) M) increased secretion 39 +/- 9% (n = 7). The combination of 10(-3) M arachidonic acid and 10(-7) M carbachol elicited a significantly greater change in secretion compared with either agent alone [173 +/- 50% (n = 5)]. The addition of nordihydroguaiaretic acid (10(-6) M) or indomethacin (10(-6) M) partially attenuated the arachidonic acid-enhanced secretory responsiveness to carbachol. Treatment with both blockers completely inhibited the arachidonic acid-enhanced secretory responsiveness to carbachol. The effect of arachidonic acid on cholinergic stimulation was also abolished by treating the explant cultures with tetrodotoxin (10(-7) M). This hypersecretory state is most likely mediated by eicosanoid-induced release of neurotransmitters from nerve terminals.

Animals↗
PubMed1992

Cat tracheal gland cells in primary culture.

Conditions for the primary culture of isolated cat tracheal gland cells were established. Cells plated onto glutaraldehyde-fixed gels of rat tail collagen grew to confluency after 8 days of culture forming a monolayer of cuboidal cells with ultrastructural characteristics of epithelial cells and immunoreactivity to antikeratins. Cultured cells synthesized and released radiolabeled high-molecular-weight glycoconjugates. Glycoconjugate secretion was increased approximately 10% in response to the cholinergic agonist, carbachol. Secretion of glycoconjugates was unrelated to regulated exocrine secretion, since these cells were devoid of secretion granules as assessed by light and electron microscopy. Confluent cultures also generated a spontaneous potential difference and short-circuit current, which were both inhibited by ouabain and increased by carbachol. This suggested gland cells contribute to fluid secretion by active ion-transport mechanisms. We also plated cells onto unfixed collagen gels that were released from the culture dish at confluency. Cells were columnar with apically oriented secretion granules that stained with alcian blue and for blood group A immunoreactivity. Secretion of radiolabeled high-molecular-weight glycoconjugates was increased 27% by carbachol. These cell culture systems may serve as models to investigate glandular secretory mechanisms and their regulation.

Animals↗
PubMed1991

Variable effects of soman on macromolecular secretion by ferret trachea.

The purpose of this study was to examine the effect of the anticholinesterase agent, soman, on macromolecular secretion by ferret trachea, in vitro. We mounted pieces of ferret trachea in Ussing-type chambers. Secreted sulfated macromolecules were radiolabeled by adding 500 microCi of 35SO4 to the submucosal medium and incubating for 17 hr. Soman added to the submucosal side produced a concentration-dependent increase in radiolabeled macromolecular release with a maximal secretory response (mean +/- SD) of 202 +/- 125% (n = 8) relative to the basal secretion rate at a concentration of 10(-7) M. The addition of either 10(-6) M pralidoxime (acetylcholinesterase reactivator) or 10(-6) M atropine blocked the response to 10(-7) M soman. At soman concentrations greater than 10(-7) M, secretion rate decreased and was not significantly different from basal secretion. Additional experiments utilizing acetylcholine and the acetylcholinesterase inhibitor, physostigmine, suggest that inhibition of secretion by high concentrations of soman may be due to a secondary antagonistic effect of soman on muscarinic receptors.

Acetylcholine↗
PubMed1991

Effects of ozone on the cholinergic secretory responsiveness of ferret tracheal glands.

Oxidant air pollutants exacerbate several pulmonary diseases. Inhalation of ozone has been shown to induce airway smooth muscle hyperresponsiveness. Oxidant injury could also affect airway secretory mechanisms. We postulated that oxidant exposure would alter the glycoconjugate secretory function of airway submucosal glands. To test this hypothesis we examined the effects of in vivo ozone exposure on the in vitro secretory responsiveness of ferret tracheal glands. Ferrets were exposed to 1 ppm ozone, 24 hr/day for 3 or 7 days. Following exposure, glandular explants, denuded of surface epithelial cells, were prepared and incubated in medium containing 3H-glucosamine for 18 hr. Basal secretion of labeled glycoconjugates was significantly increased 31% following 3 days of ozone exposure (P less than or equal to 0.05) and remained elevated 11% after 7 days of exposure compared to the air-exposed group. After 3 or 7 days of exposure to ozone, tracheal gland responsiveness to carbachol was increased as indicated by significantly lower EC50 values (log molar concentration) of -6.43 +/- 0.04 (n = 6) and -6.50 +/- 0.11 (n = 5), respectively; compared to -6.20 +/- 0.08 (n = 6) for the air-exposed group. There was no difference in carbachol EC50 values for air and 7-day ozone-exposed animals treated with dexamethasone. Dexamethasone did not attenuate the ozone-induced increase in basal secretion. Tracheal gland responsiveness to alpha- or beta-adrenergic agonists was not changed by oxidant exposure. These experiments suggest that oxidant injury not only increases basal secretion of respiratory glycoconjugates but also increases tracheal gland sensitivity to a cholinergic agonist.

Animals↗
PubMed1991

Utility of pleural fluid analysis in predicting tube thoracostomy/decortication in parapneumonic effusions.

Recommended criteria for surgical drainage of parapneumonic effusions include evidence of frank purulence, a glucose level less than 40 mg/dl, a pH of less than 7.00, or an LDH greater than 1,000 IU/L. To test the utility of these criteria, we reviewed the three-year experience of three Rochester, NY, hospitals. We identified 133 patients undergoing thoracentesis for putative parapneumonic effusions. Of 91 patients with neutrophilic exudates, 43 met one or more criteria for tube thoracostomy: 48 did not. Twenty-one of the 43, including 9 with frank empyema, underwent immediate drainage. Of the 22 who did not, 11 eventually required tube thoracostomy and/or decortication. Of the 48 not meeting any of the criteria, 7 also came to surgery. Using whether the patients eventually underwent surgery as a measure of outcome, we calculated for those patients not undergoing immediate drainage the sensitivity, specificity, positive predictive values, and negative predictive values for each of the criteria. The four criteria have relatively high specificity ranging from 82 to 96 percent, but have low sensitivity varying from only 18 percent for a positive Gram stain to 53 percent for a fluid LDH greater than 1,000 IU/L. We conclude that these criteria have limited usefulness in predicting the need for eventual chest tube drainage/decortication. Patients not meeting the criteria require close follow-up as well.

Chest Tubes↗
PubMed1990

Efficacy of hepatic computed tomography to detect iron overload in chronic hemodialysis.

The diagnostic efficacy of hepatic computed tomography density (HCTD) in comparison with serum ferritin for the detection of iron overload was investigated in uremic patients on maintenance hemodialysis (HD) and in patients with idiopathic hemochromatosis (IHC). Ten IHC patients, 38 HD patients and 40 healthy subjects underwent the CT scanning of the liver and determination of percent saturation of transferrin, serum ferritin concentration and HLA typing. Liver iron content was determined by histochemical grading and direct measurement of liver iron concentration either in IHC patients or in HD patients. Nineteen HD patients were considered to have iron overload on the basis of liver iron concentration exceeding 3.6 mumol/100 mg dry weight. The mean +/- SD values of HCTD in healthy subjects, IHC patients, HD patients with iron overload and without iron overload were 60.2 +/- 5.6, 79 +/- 5.6, 71.4 +/- 3.6, 58 +/- 3.8 Hounsfield units, respectively. HCTD showed positive correlations with liver iron concentration and serum ferritin either in IHC patients or in HD patients. The analysis of the diagnostic efficacy of HCTD in comparison with serum ferritin for the detection of excessive hepatic iron in HD patients demonstrated that HCTD had higher sensitivity, specificity, positive and negative predictive values. Cut-off points were arbitrarily fixed to 66 Hounsfield units for HCTD, 400 micrograms/liter for serum ferritin and 3.6 mumol/100 mg dry weight for liver iron concentration. Seventeen HD patients who possessed the histocompatibility antigens associated with IHC, namely HLA-A3 and/or HLA-B7 and/or HLA-B14, had liver iron concentration, serum ferritin and HCTD values higher than those of the HD patients without these "hemochromatosis alleles".(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Alpha-adrenergic regulation of secretion by tracheal glands.

The purpose of the present study was to begin to characterize, pharmacologically, the alpha-adrenergic regulation of glycoconjugate secretion from airway glands. Using isolated gland cells from cat trachea, we determined the binding characteristics of [3H]dihydroergocryptine ([3H]DHE), an alpha-adrenergic antagonist, with equal affinities for alpha 1- and alpha 2-adrenergic receptors. Specific binding of [3H]DHE to gland cell homogenates was saturable, of high affinity (KDapp = 4.2 nM) and inhibited with greater efficacy by epinephrine much greater than isoproterenol. Competition experiments with alpha 1- and alpha 2-adrenergic selective antagonists (prazosin and yohimbine, respectively) demonstrated high- and low-affinity sites for each antagonist, indicating the presence of both receptor subtypes. In studies of glycoconjugate secretion by cat tracheal explants, secretion was stimulated by adrenergic agonists with the rank potency: norepinephrine greater than or equal to phenylephrine greater than epinephrine much greater than clonidine. alpha-Adrenergic-stimulated secretion (epinephrine + propranolol) was inhibited by low concentrations of prazosin, but was unaffected by 100 nM yohimbine. The alpha 2-adrenergic agonists, clonidine and UK-14,304, each markedly inhibited beta-adrenergic-stimulated secretion. Collectively, these results demonstrate alpha 1-adrenergic regulation of glandular glycoconjugate secretion and suggest alpha 2-adrenergic receptors may modulate beta-adrenergic-stimulated secretion.

Animals↗
PubMed1989

Effects of soman and its antidotes on tracheal mucociliary transport of ferrets.

The purpose of this study was to examine the role of acetylcholinesterase on mucociliary transport by use of a potent anticholinesterase agent, soman, and potential antagonists, atropine (muscarinic antagonist) and pralidoxime (acetylcholinesterase reactivator). Initial measurements of mucociliary transport rate were obtained in anesthetized ferrets at 30-min intervals for 5.5 h. These rates remained constant at a mean of 18.2 +/- 1.0 (SE) mm/min. We studied the effects of intravenously administered soman (1-8 micrograms/kg) and observed a dose-related change in the rate of mucociliary transport [-1.1 +/- 2.7 (SE) mm/min after 1 microgram/kg, 9.8 +/- 2.9 mm/min after 5 micrograms/kg, and 14.4 +/- 4.3 mm/min after 8 micrograms/kg of soman]. Pretreatment with atropine completely prevented the response to soman, whereas pretreatment with pralidoxime did not significantly alter the response. We postulate that soman's effect on mucociliary transport relates directly to its cholinergic activity. Failure of pralidoxime to inhibit the effects of soman may relate to pralidoxime's inability to reactivate acetylcholinesterase successfully.

Animals↗
PubMed1989

[Results of diet treatment in 100 adult obese patients after 1-year follow-up].

One hundred overweight adult patients were subjected to a hypocaloric diet with periodic controls during a one year observation period. During the first 4 months, 98% of the patients adhered to the dietary regimen, with an initial mean percentage loss of body weight of 9.3% for the females and 8.9% for the males. The weight loss was more conspicuous during the first two months of the diet therapy and in patients with an initially higher BMI. With time, the rate of drop-out from the diet therapy increased, which resulted in a follow-up of 49% and 87% of cases at 6 and 12 months respectively, with no significant differences between the two sexes. The drop-out phenomenon resulted to be more frequent in patients with an initially lower BMI.

Energy Intake↗
PubMed1988

Influenza virus infection of tracheal gland cells in culture.

Influenza virus-induced tracheobronchitis causes limited epithelial deciliation but markedly decreased mucociliary transport. This suggests that virus-induced alterations in airway mucus play a role in decreased mucociliary transport. Airway submucosal glands are a primary source of mucus. Therefore, we examined virus-gland cell interactions by exposing primary cultures of isolated feline tracheal gland cells to influenza A/Scotland/840/74 H3N2 virus for 1 h at a multiplicity of infection of 0.1. Virus production and release into the culture medium first occurred between 8 and 12 h postinfection and eventually reached a steady state that continued for at least 8 days. Virus which was produced and released by infected cells infected other monolayers, resulting in viral production similar to that after infection with stock virus. Hemadsorption assays conducted 24 h after infection demonstrated that most of the cells in a monolayer became infected. The infection was nonlytic according to cell morphology, trypan blue dye exclusion, and release of lactate dehydrogenase. Because lysis of a cell subpopulation could have been masked by subsequent cell division, we compared the uptake of [3H]thymidine by infected and control monolayers. There was no increase in uptake by infected monolayers. These results demonstrate that feline tracheal gland cells in primary culture undergo productive and nonlytic infection with influenza A virus. This model provides a unique system for the study of virus-gland interactions isolated from the influence of other tissues.

Animals↗
PubMed1988

Utility of fiberoptic bronchoscopy in patients with hemoptysis and a nonlocalizing chest roentgenogram.

The need for fiberoptic bronchoscopy in the patient with hemoptysis and a normal or nonlocalizing chest roentgenogram remains a subject of debate. Currently, diagnostic fiberoptic bronchoscopy is recommended as the investigative procedure of choice. To develop predictors that identify the patient in whom fiberoptic bronchoscopy is most likely to be diagnostic, we reviewed our community's experience with this population over a five-year period. We identified 196 patients with hemoptysis and a normal or nonlocalizing chest roentgenogram who underwent fiberoptic bronchoscopy. Three quarters were active or previous smokers. We examined the relationship of advancing age, sex, smoking, nonspecific roentgenographic findings and the amount, duration, and previous bouts of hemoptysis to the incidence of a diagnostic fiberoptic bronchoscopy. Twelve patients (6 percent) had bronchogenic carcinoma and 33 (17 percent) another specific cause for the hemoptysis identified by fiberoptic bronchoscopy. By univariate and discriminant analyses, we found that the three factors of age of 50 years or more, male sex, and smoking of 40 pack-years or more best predicted a diagnosis of malignancy. Bleeding in excess of 30 ml daily was associated with an increase in overall diagnostic yield. The presence of two of the three factors associated with malignancy or bleeding in excess of 30 ml daily (or both) identified 100 percent of the patients with bronchogenic carcinoma and 82 percent of all of the diagnostic fiberoptic bronchoscopic procedures. use of these criteria in selecting the patient for fiberoptic bronchoscopy could have reduced our use of the bronchoscope by 28 percent, with the remaining patients safely observed.

Adolescent↗
PubMed1987

Abnormal myocardial texture demonstrated by ultrasound in two patients with idiopathic haemochromatosis.

We studied by cross-sectional echocardiography seven patients affected by idiopathic haemochromatosis without clinical signs of heart failure. In two patients the heart muscle showed a peculiar echocardiographic texture at the level of the endocardium. No differences were noticed in clinical and haematological findings of the patients with and without abnormal texture. Increased echogenicity of the subendocardial myocardium should be looked for in patients with idiopathic haemochromatosis.

Adult↗
PubMed1986

Characterization of muscarinic cholinergic receptors in cat tracheal gland cells.

Studies of airway glands indicate a muscarinic cholinergic regulation of secretion. Because of the cellular complexity of the airways, receptor characterization in whole tissue is unfeasible. Therefore, we utilized homogenates of disaggregated gland cells isolated from cat trachea and the muscarinic antagonist [1-3H]quinuclidinyl benzilate ([3H]QNB) to characterize glandular muscarinic receptors. Receptors of isolated cells were functionally intact as assessed by carbachol (10(-4) M) stimulation of O2 consumption 86 +/- 6% (+/- SE, n = 20). Stimulation was dose dependent (mean effective concentration = 3.5 microM), inhibited by atropine [dissociation constant (KD) = 4.2 nM] but not phentolamine nor propranolol. Specific binding of [3H]QNB to cell homogenates was saturable, of high affinity (KD = 36 pM) and to a single population of receptors. Maximum binding was 58 fmol/10(6) cells or about 35,000 receptors per cell. Estimated affinities for muscarinic agents were in the micromolar range for agonists and nanomolar range for antagonists. Histamine, alpha-adrenergic, and beta-adrenergic agonists and antagonists did not inhibit specific binding. These results suggest that muscarinic receptors on tracheal gland cells are of high affinity and density.

Acetylcholine↗