Biomedical subjects
Publications and source records attributed to M Schechter.
Pulmonary hyalinizing granulomata are unusual, noninfectious lesions of the lung of uncertain etiology that probably represent an exaggerated immune response. They present radiographically as noncalcified solitary or multiple pulmonary nodules, thereby mimicking primary or metastatic malignancy. The article discusses a case of this rare entity that presented as a solitary pulmonary nodule.
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Percutaneous cecostomy (PCC) was evaluated in dogs and cadavers and by means of review of intraperitoneal contrast material-enhanced computed tomographic (CT) scans and clinical experience in five patients with Ogilvie syndrome. It was shown that PCC can be accomplished with a variety of techniques (e.g. Seldinger or trocar puncture, tacking) and instruments (various types and sizes of retention and nonretention catheters). Anatomic studies revealed that the cecum is surrounded by the peritoneum for as much as 270 degrees of its circumference, so that a retroperitoneal approach to PCC would probably be unfeasible in most patients. PCC was effective in treating all five patients in this study, despite their advanced age and complicated medical conditions. Decompression of colonic gas was achieved with 8-12-F catheters, and no major complications occurred. Endoscopic decompression had been unsuccessfully attempted in four of the patients previously. It is concluded that PCC may be an important option in the treatment of Ogilvie syndrome and that the procedure may obviate surgery and be lifesaving in certain high-risk patients.
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A survey of six geriatric experts concerning the normative role content of physicians providing primary care for the elderly emphasizes the importance of distinguishing reversible and irreversible components of a patient's problems and of conducting multidimensional functional assessments. Appreciation of the role of the environment in maintaining functional capacity should be inculcated in practitioners treating the elderly. Medicare payment methods should recognize that the elderly require more professional time for adequate care, and should address transportation needs.
Evidence of the degree of fit between the special needs of the elderly and the service mix and payment level of ambulatory services offered under the Medicare program is presented in this second part of a two-part study of geriatric office care. Results from interviews with a focus group of 60 practicing clinicians, incorporating diversity of geography and practice setting, are described and compared with the view of geriatricians. Between 30 and 57% of the clinicians are aware of negative effects of Medicare's benefit structure on specific aspects of their practice.
An attempt was made to reconcile published data on the cell surface profile of Trypanosoma cruzi epimastigotes. Cloned parasites were used to compare the effects of centrifugal forces, radioiodination catalyst and protein solubilization methods on the autoradiographic profile of putative surface antigens. Harvesting and washing procedures, and antigen extraction methods, greatly influenced the results obtained, whilst the iodination catalyst was not of critical importance. Mobility in different gel electrophoresis systems, Western blots and partial proteolysis maps indicated that two previously described epimastigote-specific surface antigens (GP72 and Mr 75,000) possibly are distinct molecules.
Airways responsiveness to a bronchodilator is frequently measured to assist in determining the cause of respiratory symptoms. Clinically, a greater than 15% improvement in the FEV1 is often used to define the "increased" response indicative of asthma. However, unlike other tests of lung function, reference standards derived from "healthy" members of a general population sample have never been reported. As part of a health survey carried out in Alberta, Canada, 2,609 subjects completed a standardized respiratory symptom questionnaire and had FEV1 measured before and 20 min after inhaling terbutaline sulfate via a 750-ml spacer device. Among asymptomatic never-smoking subjects with a FEV1 greater than 80% of predicted, the upper 95th percentile of bronchodilator response (BDR), when expressed as 100 x (FEV1 postBDR - FEV1 preBDR)/predicted baseline FEV1 averaged 9%. This value remained remarkably stable across gender, age (7 to 75 yr), and height groups, and deviated to 6% only when baseline FEV1 was greater than 120% of predicted. Consistent with other respiratory function variables, in which the upper limit of normal is often defined as the upper 95th percentile, our population-derived reference values provide a conceptual definition of BDR that can easily be applied to define "increased" response in the clinical setting.
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We have recently described the application of a purified glycoprotein of 25,000 Mr (GP25) of Trypanosoma cruzi in serodiagnosis of Chagas' disease. Purified GP25 lacks appreciable immunogenicity in some animal species, in spite of being generally antigenic to parasitized hosts. The underlying cause for these contrasting observations has not been determined, but it may relate to the drastic extraction conditions used in the original isolation procedure, and possible damage inflicted to the native form of this antigen. This report describes the molecular properties of a GP25-related primary antigen, and a fast performance liquid chromatographic (FPLC) procedure to attain its isolation under gentle conditions. The expression of GP25-related antigen by epimastigotes or bloodstream forms was investigated with a high-affinity monoclonal antibody to GP25, SC11G10, as well as with monospecific antisera to GP25. Immunochemical analysis of Nonidet P-40 lysates supplemented with protease inhibitors indicated that GP25 is not synthesized as such; instead, a 57,000 Mr component (GP57) was identified as the primary antigen product. Partial enzymatic conversion to GP25 was observed when inhibitors were deliberately omitted from cell extracts. Most significantly, GP57 was established as the primary biosynthetic product in [35S]-labeled bloodstream trypomastigotes after immunoprecipitation with SC11G10 antibody. This analysis when applied to metabolically labeled epimastigotes has consistently revealed a minor antigen component of 51,000 Mr (GP51), in addition to GP57. The former was identified as the antigenically related product exposed at the parasite cell surface after external radioiodination of viable trypanosomes. Access to the native form of this widely distributed surface glycoprotein should stimulate the investigation of functional and structural aspects of its immunologic activity.
Three competitive inhibition enzyme-linked immunosorbent assays were developed to examine the expression of the 72-kilodalton glycoprotein (GP72) and of a GP72 carbohydrate epitope in Trypanosoma cruzi strains and clones. A total of 148 strains and clones of known isozyme phenotype (principal zymodeme, Z) were tested. With monoclonal antibody 8G2B9 the enzyme-linked immunosorbent assay confirmed that the majority of Z1 strains and clones derived from them had undetectable levels of the carbohydrate epitope identified by antibody 8G2B9. This epitope was, however, readily detectable in all Z2, Z2(h), and Z3 strains and clones (P less than 0.001; 148 strains and clones tested). Zymodeme-associated differences in GP72 expression were not apparent from the enzyme-linked immunosorbent assay with monoclonal antibody WIC 226.4 (raised against periodate-treated GP72) or from that with rabbit anti-GP72 antiserum (84 or 119 strains and clones tested, respectively). Mice infected with culture-form metacyclic trypomastigotes of Z1, Z29, and Z3 or with blood-form trypomastigotes of Z1 and Z3 developed antibodies to affinity-purified GP72, showing that at least some GP72 epitopes are neither zymodeme specific nor stage specific. A total of 128 serum samples from patients with acute or clinically classified chronic Chagas' disease were assayed for immunoglobulin G (IgG) or IgM anti-GP72 antibodies. During the acute phase anti-GP72 IgM antibodies were elevated, whereas anti-GP72 IgG antibodies were low. There were no significant differences in anti-GP72 antibody levels among chronic-phase patient groups. Anti-GP72 antibodies were detected irrespective of the geographical origin of patients and irrespective of whether acute-phase blood parasitemias were due to Z1 (four patients) or Z2 (two patients).