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Biomedical subjects

M Sepulveda

Publications and source records attributed to M Sepulveda.

13 recordsLinked to original sources
PubMed1998

Adherence of Acinetobacter baumannii to rat bladder tissue.

Acinetobacter baumannii, an important nosocomial pathogen, causes severe infections in patients of intensive care units, but its pathogenic attributes are unknown. Previously, the adherence of A. baumannii to cell lines has been negative in the authors' laboratory. In this work, the adherence of strains of A. baumannii of various biotypes to small pieces of rat bladder tissue was investigated. Tissue pieces were submerged into cultures of A. baumannii and sessile cells were counted after removing planktonic bacteria. Fimbriae and sessile cells were examined by transmission and scanning electron microscopy, respectively. In contrast to a uropathogenic strain of Escherichia coli, all cultures exhibited a mannose- and galactose-resistant agglutination of human group O red blood cells as well as mannose- and galactose-resistant adherence to the bladder tissue. Inhibition of exopolysaccharide synthesis did not modify adherence. Indeed, adherence, apparently unrelated to these fimbriae or to the exopolysaccharide, may be a factor contributing to the pathogenicity of A. baumannii in the urinary tract or in other tissues.

Acinetobacter↗
PubMed1997

Ethodin: pharmacological evidence of the interaction between smooth muscle and mast cells in the myometrium.

Ethodin has been used to induce labor through a mechanism that does not involve the estrogen-preparatory process being postulated as necessary for ensuring the events in a normal labor. The cellular mechanisms involved in that process are unknown. We used an isolated organ bath preparation for mouse uterine horns and a primary culture of mouse myometrial smooth muscle cells to analyze the cellular mechanisms involved in the contractile action of this drug in the myometrium. Ethodin at a concentration of 10 microM and Compound 48/80 (1 microg/ml) evoked contractions of uterine horns in an isolated organ bath preparation. Uterine contractile responses showed a transient increase in contractile tension that lasted 2 to 3 min. Tachyphylaxis was observed after four or five successive stimuli, which consisted in additions and washings of the drug at an interval of 10 min. The primary smooth muscle mouse myometrium cells contained a high proportion of relaxed cells that varied widely in length (5-160 microm). Cell lengths decreased in response to the application of serotonin (10 microM) and oxytocin (0.1 microM) but were not affected after the addition of ethodin (10 microM). However, the cells contracted after a purified fraction of mast cells that had been degranulated by the action of the drug ethodin, which was added to the culture medium. These results provide some evidence related to the mechanism of myometrial contractile action of ethodin and support the hypothesis that mast cells may be involved in the regulation of myometrium contractility.

Animals↗
PubMed1994

Measuring second-order selection bias in a work site health program.

Magnitude and direction of second-order self-selection bias were assessed in a sample of 93,807 IBM employees who participated in the company's Voluntary Health Assessment (VHA) Program, by comparing repeat participants with one-time participants and by simulating selection into the repeat sample. One-time and repeat VHA participants differed systematically but not uniformly in several health characteristics. Repeat participants improved significantly in risk-relevant behaviors and health risk measures. Simulation of selection bias by excluding healthier or less healthy participants from the repeat VHA sample showed findings of gain to be robust. In studies of gain, second-order selection bias cannot automatically be assumed to inflate gain nor to be of sufficient magnitude to affect conclusions about program effects. Simulation is a useful tool for gauging direction and magnitude of selection bias.

Adult↗
PubMed1994

[Continuous hemodialysis with cuprophan membranes in critical patients].

The aim of this work was to evaluate the use of 1 m2 Cuprophan hollow fiber filters for continuous arteriovenous hemodialysis procedures. Thirty one critically ill patients (18 male) aged between 20 and 80 years old, subjected to 35 hemodialysis procedures were studied. Sixteen patients had acute renal failure (10 of these had multiorgan failures) and 15 terminal chronic renal failure. Femoral vessels were used for vascular access and isotonic peritoneal dialysis solution flowing at 16.6 ml/seg as dialyzing solution. No extracorporeal pump assistance was used. Mean procedure time was 76 +/- 69.7 h, filter consumption was 2.8 +/- 2.1 filters/procedure, ultrafiltration rate was 168 ml/min and urea clearance was 19.9 +/- 4.4 ml/min. No replacement solutions were required and good electrolyte and circulating volume control was achieved with excellent hemodynamic stability. Blood urea fell from 116.9 +/- 49.1 to 64 +/- 27.2 mg/dl after the procedure (p < 0.001). Hyperglycemia was observed in eight procedures, six patients developed non infectious vascular access complications and two patients catheter related sepsis. We conclude that continuous arteriovenous hemodialysis using cuprophan membranes is a good renal substitution technique for critically ill patients.

Acute Kidney Injury↗
PubMed1994

Association of IBM's "A Plan for Life" health promotion program with changes in employees' health risk status.

To evaluate the association of participation in IBM's "A Plan for Life" program with changes in blood pressure, serum total, high-density lipoprotein, and non-high-density lipoprotein cholesterol, body mass index, and cigarette smoking, we compared changes in these measures over a 1- to 5-year period among program participants and nonparticipants initially found to be at risk. After adjustment for age, sex, time to follow-up, and baseline values, the proportion of participants no longer at high risk was significantly greater than the corresponding proportion of nonparticipants in the areas of blood pressure total and non-high-density lipoprotein cholesterol and smoking cessation.

Adolescent↗
PubMed1978

Histology of human tubulo-interstitial nephritis associated with antibodies to renal basement membranes.

Twenty-seven patients with diffuse "crescentic" glomerulonephritis (CSGN) were identified in 1,174 renal biopsies from nephritic patients. Patients were assigned to three groups on the basis of the immunofluorescent study of renal biopsy specimens and serologic findings. Group I included eight patients with antibodies to glomerular (anti-GBM) and tubular (anti-TBM) basement membranes; group II had eight patients with only anti-GBM antibodies; and group III had eleven patients with CSGN unassociated with antibodies to either GBM or TBM. Patients with anti-GBM/anti-TBM antibodies (group I) had severe tubulointerstitial (TI) nephritis, as characterized by the infiltration of polymorphonuclear leukocytes and macrophages along the TBM and peritubular vessels. In some patients, focal proliferation of epithelial cells of proximal convoluted tubules (PCT), gaps or extensive destruction of TBM, lesions in the walls of small peritubular vessels, and interstitial giant cells were also observed. Patients with anti-GBM antibodies (group II) had mild to moderate interstitial cellular infiltration and mild tubular changes. Five patients with CSGN not associated with antibodies to renal basement membranes (group III) had mild to moderate interstitial cellular infiltration and tubular changes. A sixth patient, with Wegener's disease had severe granulomatous TI lesions. The results of this study show that TI nephritis is most frequent and severe with anti-TBM antibodies are demonstrable and suggest that anti-TBM antibodies contribute to the development of TI lesions.

Adult↗
PubMed1977

Disseminated immune deposits in lupus erythematosus.

Immunohistologic studies were performed on autopsy tissues of 2 patients with systemic lupus erythematosus. All tissues examined--the kidney, lung, spleen, liver, intestine, peritoneum, and choroid plexus--contained immune deposits. Antinuclear antibody concentration in immunoglobulin G eluted from lung and spleen tissue was higher than in serum immunoglobulin G. These findings support the assumption that in systemic lupus erythematosus the renal as well as the extrarenal lesions can be attributed to vascular deposition of immune complexes.

Adolescent↗
PubMed1976

Immune deposit nephritis in infectious mononucleosis.

A 22-year-old white male (L.V.) died of gram-negative septicemia complicating infectious mononucleosis (IM) that was associated with jaundice and oliguric renal failure. The kidney showed mesangial granular deposits of IgM and C3, mesangial electrondense deposits, and interstitial infiltrates of infiltrates of mononuclear cells, including atypical lymphocytes. Eluates obtained from kidney, spleen and liver contained Paul--Bunnell (PB) antibodies. Presence of PB antigens in these tissues was indicated by absorption of PB antibodies from IM sera, with the sediments resulting from tissue elutions. The IgM mesangial deposits were partially eluted with acid buffer at 56 degrees C and then reconstituted by incubation with IM sera or with immunoglobulins eluted from tissues of patient L.V. The presence in renal structures of PB antigens, IgM heterophile antibody, C3 and electron-dense deposits is consistent with the hypothesis that heterophile immune complexes were localized in the kidney and that they contribute in the pathogenisis of IM nephritis.

Adult↗
PubMed1975

Interstitial immune complex nephritis in patients with systemic lupus erythematosus.

Interstitial immune complex nephritis in patients with systemic lupus erythematosus (SLE). Renal tissues from 45 patients with SLE nephritis, 34 patients with idiopathic membranous nephropathy (IMN) and 77 patients with minimal glomerular disease (MGD) were studied by light, immunofluorescence and electron microscopy. Interstitial nephritis characterized by focal or diffuse infiltration of inflammatory cells, tubular damage and interstitial fibrosis was observed in 66% of SLE patients. Fluorescein-conjugated antibodies to immunoglobulins or complement or both were bound to peritubular capillaries, interstitium and tubular basement membranes (TBM) in 53% of patients with a granular pattern corresponding to opaque deposits seen by light or electron microscopy or both. Antibodies reactive with thymidine or cytosine or both were bound to interstitial structures in 19% of patients tested and showed the same granular distribution. Interstitial cellular infiltration was rare and deposits of immunoglobulins and complement were rare or absent in IMN and MGD, whereas deposits of DNA products were never observed. The findings are consistent with the interpretation that in patients with SLE nephritis immune deposits, presumably containing DNA-anti-DNA complexes, localize in peritublular capillaries, TBM and interstitum, thereby producing an inflammatory reaction which contributes to development and evolution of renal diseases.

Antibodies↗