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Biomedical subjects

M Arce

Publications and source records attributed to M Arce.

13 recordsLinked to original sources
PubMed1997

Massive subcutaneous and intraosseous fat necrosis associated with pancreatitis. Natural evolution of the radiographic picture.

A 44-year-old man developed high fever, polyarthralgias, erythematous tender nodules and plaques on feet, ankles, knees and dorsum of the hands, as well as swelling of ankles and several joints of hands and feet. Laboratory evaluation showed high serum pancreatic amylase and lipase. Histological study of a subcutaneous nodule demonstrated fat necrosis. X-ray examination revealed numerous lytic lesions involving cancellous and cortical bone in phalanges, metacarpals, radius, tibia, tarsus and metatarsals, with areas of widened bone. The patient never referred any abdominal symptom. He evolved favourably within the following months. A year later, resolution of most of the bone lesions was observed.

Bone Diseases↗
PubMed1995

Danazol distribution in plasma and cell membranes as related to altered cell properties: implications for mechanism.

Concentrations of danazol in patient plasma and red blood cells (RBC) were assayed over a 6-month period in 75 patients on danazol therapy using a high-pressure liquid chromatography (HPLC) method more reliable than previous radioimmunoassay (RIA) methods. It was found that plasma danazol rose regularly for 15 days after the beginning of treatment, reaching a steady state plateau of 175 +/- 76 ng/ml in 20 patients on normal dose, and less for lower dose schedules. After stopping danazol, concentrations declined to near zero in a similar time frame. RBC concentrations on a packed volume basis were similar to plasma levels. However, the membrane ghosts of RBC contained about 50% of the total RBC danazol, implying about 100-fold higher concentration in membranes than in plasma. Similar distributions were obtained in vitro with both RBC and platelets, and were confirmed by 14-C-labeled danazol. These findings tend to support the hypothesis that the benefits of danazol in immune disorders may be attributable in part to its intercalation in the lipid bilayer of the plasma membrane, altering antigen/receptor expression to modulate immune reactions. This hypothesis was first suggested when it was observed that the RBC of patients on danazol therapy showed morphological changes and increased resistance to osmotic lysis. It was later shown that danazol in vitro reduces binding of autoantibodies, and protects against complement-mediated lysis, suggesting direct action of danazol on the membranes. This hypothesis is discussed, and danazol's effect in protecting against complement-mediated lysis is described.

Blood Platelets↗
PubMed1994

[Bacterial infections in hepatic cirrhosis].

The aim of this work was to study the prevalence of bacterial infections in hospitalized patients with liver cirrhosis and to compare clinical, bacteriological and evolution features of patients with (group 1) and without bacterial infections (group 2). One hundred thirty two hospitalized patients with liver cirrhosis were prospectively studied and 61 episodes of bacterial infections were diagnosed in 52 (27 spontaneous bacterial peritonitis (44.3%), 16 urinary tract infections (26.2%), 10 pneumonias (16.4%), 3 spontaneous bacteremias (4.9%9, and 5 miscellaneous infections (8.2%)). Twenty six percent of infections were nosocomial. Child-Pugh score was 12 +/- 2 in group 1 vs 10 +/- 2 in group 2 (p = 0.047). Sixty five percent of identified microorganisms were gram negative and 61.5% of these were E. coli. Hospital mortality of group 1 was 29% and that of group 2 was 9% (p = 0.002). It is concluded that there is a high prevalence of bacterial infections in hospitalized cirrhotic patients, that is associated to a high mortality.

Adult↗
PubMed1992

Clinical significance of platelet microparticles in autoimmune thrombocytopenias.

Platelet microparticles (PMPs) are vesicles derived from platelet membranes that are too small (less than 0.5 micron) to be detected in routine platelet counting. They arise in association with platelet activation and other unknown causes. Elevated PMPs have been observed in idiopathic thrombocytopenic purpura (ITP), a disorder in which autoantibody interacts with platelets and the opsonized platelets are destroyed by macrophages. However, the clinical significance of PMP has been unknown. Using flow cytometry, we examined PMP concentrations in 62 patients with ITP and in 33 normal control subjects to assess the clinical significance of PMP in ITP. When compared with PMP levels in control subjects, PMP levels were significantly higher (p less than 0.005) in patients with ITP, but considerable variation among individual patients was observed. Patients with platelet counts less than or equal to 60,000 were evaluated for correlation of PMP levels with manifestations of thrombocytopenias; patients without symptoms (free of petechiae or mucosal bleeding) are found to have significantly higher PMP levels (p less than 0.05) than patients with symptoms, suggesting hemostatic protection by PMP. Additionally, we identified a group of patients with ITP who experienced neurologic complications resembling transient cerebral ischemic attacks (TIAs): recurrent episodes of dizzy spells or weakness in mild cases, and coma, seizure, or progressive dementia in advanced cases. Small cerebral infarcts were demonstrated by computed axial tomography scan or magnetic resonance imaging in spite of severe thrombocytopenias. Patients with this syndrome are often found to have higher PMP levels (p less than 0.005) when compared with the group free of neurologic complications. It is concluded that PMPs play an important role in hemostasis in patients with thrombocytopenia, and that high concentrations of hemostatically active PMP can be thrombogenic in certain clinical settings. Quantitation and characterization of PMP is important in assessment and management of patients with thrombocytopenia.

Aged↗
PubMed1989

[Prevalence of serologic markers of viral hepatitis in various population groups in Peru].

A review was undertaken of 7,521 serum samples that had been tested to detect or confirm the presence of different hepatitis A, B, and delta serologic markers. The sources of the samples included a national reference laboratory, several outbreaks of viral hepatitis in civilian and military populations, and a serologic survey. They were examined using the enzyme-linked immunosorbent assay (ELISA). The prevalence of antibody to hepatitis A virus was very high (means = 92.2%), and it was uniform. Prevalence of hepatitis B markers was more variable and inconsistent; it was high in samples from the jungle region of Peru, where the average prevalence of hepatitis B surface antigen (HBsAg) was 4.9%. Antibodies to delta hepatitis were present in 28.6% of the carriers of HBsAg identified in the outbreaks. All the outbreaks had similarities, including a high, cyclic case-fatality rate associated with the delta virus. Hepatitis A is highly endemic in Peru, while hepatitis B has average endemicity. It will be necessary to do more etiologic diagnosis of cases and conduct more research in order to better understand the epidemiology of viral hepatitis in this country.

Enzyme-Linked Immunosorbent Assay↗
PubMedDate not supplied

[Clostridium difficile diarrhea: frequency of detection in a medical center in Buenos Aires, Argentina].

Clostridium difficile has been recognized as the most important enteric pathogen of nosocomial antibiotic-associated diarrhea (CDAD) in adults from industrialized countries. The importance of C. difficile as a cause of diarrhea in ambulatory patients appears underestimated or under-recognized. Since the 1980's, outbreaks of CDAD have been increasingly reported, but there are few data available in Argentina. We developed a retrospective study to provide some information about CDAD in our country. From July 1998 to November 1999, a total of 245 fecal specimens from hospitalized and some ambulatory patients were tested in order to confirm the diagnosis of CDAD. C. difficile cytotoxin (toxin B) was identified by detecting its cytopathic effect on monolayers of McCoy culture cells. For culture and isolation of C. difficile, stool samples were prepared by ethanol shock prior to plating onto a selective medium which contained blood, cefoxitin and fructose. Of the 245 samples, 14 (5.8%) were identified as positive by the cell cytotoxicity assay. Using the criteria of isolation of cytotoxigenic C. difficile positivity increased to 6.5% (16 samples). Thirteen of the positive results were from hospitalized patients (81.3%) and 3 (18.7%) from outpatients. The mean age of inpatients was 72.9 years (ranging from 47 to 88). All patients had received 2 or more antimicrobial agents (most of them beta-lactams) 2 months before the appearance of diarrhea. There was one patient who had received only chemotherapy. The prevalence of CDAD in this study was less than in others previously reported. This difference may be due to the fact that not all general practitioners include testing for C. difficile when the patient with diarrhea had previously received antibiotics. More educational programs should be directed to all physicians, concerning the role of C. difficile as an important enteric pathogen in patients who have undergone treatment with antimicrobial or chemotherapeutic agents.

Adult↗