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Biomedical subjects

R L Myerowitz

Publications and source records attributed to R L Myerowitz.

At least 37 records · Page 2Linked to original sources
PubMed1980

Legionnaires' disease and other newly recognized Legionella-like causes of bacterial pneumonia.

Three "new" pneumonias have recently been recognized which are old diseases whose etiology has only been newly-recognized. Legionella pneumophila (Legionnaires' disease), Pittsburgh Pneumonia Agent (PPA), and Legionella-like Organisms (the Family Legionellaceae) are "rickettsia-like" bacteria which require special media for cultivation. They can each cause nosocomial pneumonia in immunosuppressed patients and all but PPA cause community-acquired pneumonia. The Legionellaceae reside in the environment within water and soil. Diagnosis can be established by morphologic, microbiological, and immunologic analysis of respiratory secretions or lung tissue. It may be confirmed retrospectively by serology. Legionella pneumophila and PPA are susceptible to erythromycin and rifampin; erythromycin is the current drug of choice for treatment of these diseases.

Humans↗
PubMed1980

Experimental osteomyelitis due to Staphylococcus aureus or Pseudomonas aeruginosa: a radiographic-pathological correlative analysis.

A previously-described experimental model of bacterial osteomyelitis was used to investigate systematically the sequential radiographic and histopathological changes in the tibias of rabbits infected with either Staphylococcus aureus or Pseudomonas aeruginosa. The radiographic changes induced by both organisms were progressive, increasing in severity from the first to the fourth week after infection. The severity and extent of radiographic changes, especially that of bond destruction, were significantly greater for tibias infected with S. aureus. Histopathologically, staphylococcal disease was a severe, rapidly progressive purulent infection which led to extensive destruction of marrow and cortical bone, formation of sequestra, and frequent extraosseous extension. Disease due to P. aeruginosa was more indolent and less destructive, leading to earlier healing and no extraosseous extension. The sequential radiographic and pathological changes observed with this experimental model closely resemble those described in man and suggest that this model may be useful for future investigations of pathogenesis and therapy.

Animals↗
PubMed1980

The ultrastructural morphologic features of Pittsburgh pneumonia agent.

The fine structure of "Pittsburgh Pneumonia Agent" (PPA) was studied in infected human lung, guinea pig omentum, yolk sac membrane, Vero cell culture, and after cultivation of the organism on buffered charcoal yeast extract agar. The organism is a prokaryotic cell with the general features of a gram-negative bacillus. PPA is ultrastructurally distinctive because of an unusually thick, electron-dense band present within the periplasmic space adjacent to the outer membrane of the cell wall. This band, presumably a mucopeptide (peptidoglycan) layer, was seen in about 95% of organisms in human lung but less frequently under certain conditions of laboratory infection or cultivation. Future studies are required to determine whether this ultrastructural dimorphism of PPA is related to variation in other properties of this bacterium, eg, gram-variability, acid-fastness, colony morphology, and virulence.

Animals↗
PubMed1979

Opportunistic lung infection due to "Pittsburgh Pneumonia Agent".

Eight immunosuppressed patients had pneumonia due to Pittsburgh Pneumonia Agent (PPA), a gram-negative, weakly acid-fast bacterium cultivatable only in embryonated eggs and guinea pigs and distinct from Legionella pneumophila. The diagnosis was established by isolation of the agent from lung or visualization of the organism in lung tissue. The clinical presentations, radiographic abnormalities and pathology were not specific. The most consistent feature associated with the disease was the recent institution of daily high-dose corticosteriod therapy in all patients. Five of the eight patients died despite broad-spectrum antibiotic and antituberculous therapy. Anti-microbial activity against PPA was demonstrated for sulfamethoxazole combined with trimethoprim, for rifampin and for erythromycin with an egg-protection assay. Serologic studies with an indirect fluorescent-antibody technic suggested that seroconversion or high titers may be a sensitive test for PPA disease. PPA appears to be a newly recognized cause of life-threatening bacterial pneumonia in immunosupressed patients.

Adrenal Cortex Hormones↗
PubMed1979

New bacterial agent of pneumonia isolated from renal-transplant recipients.

A gram-negative, weakly acid-fast bacillus has been isolated in embryonated eggs and in guineapigs from lung tissue of two renal-transplant recipients with acute purulent pneumonia. Culture of infected lung tissue and subculture of the egg isolate on artificial media, including media for legionnaires' disease bacterium (Legionella pneumophila), failed to produce growth. Ultrastructural analysis showed that the organism is a prokaryote with a cell-wall structure typical of a gram-negative bacillus but different from that of L. pneumophila. In both patients serum antibody to both isolates developed in high titre. In its microbiological, tinctorial, and ultrastructural characteristics this bacterium differs sufficiently from L. pneumophila and other pulmonary pathogens to indicate that it may be a new agent of bacterial pneumonia.

Acute Disease↗
PubMed1979

Diagnostic yield of transbronchoscopic biopsies.

Transbronchoscopic biopsies of lung (transbronchial) or bronchus (endobronchial) have a high diagnostic of yield when performed by a single expert bronchoscopist or a small group of expert bronchoscopists. This procedure's diagnostic yield was evaluated in a general hospital where biopsies are performed by a diverse group of individuals. One hundred fifty-one consecutive biopsies were reviewed, including 53 transbronchial biopsies and 98 endobronchial biopsies. Only 44% of endobronchial biopsies and 21% of transbronchial biopsies were diagnostic. The diagnostic yield was significantly greater in patients with suspected neoplasms (48%) than in patients with suspected infections (13%). Of 97 patients who ultimately had definitive diagnoses established, 43 (44%) had negative biopsy results, including 36% of those with cancers and 80% of those with infections. Failure to obtain alveolar parenchyma by transbronchial biopsy (probably related to the absence of fluoroscopic control) and failure to obtain multiple tissue fragments during each procedure contributed to the low diagnostic yield. The especially disappointing results of transbronchial biopsy for diagnosis of infection suggest that, in this hospital setting, open lung biopsy may be the procedure of choice when infection is suspected.

Biopsy↗
PubMed1979

Diagnostic value of candida precipitins determined by counterimmunoelectrophoresis in patients with acute leukemia: a prospective study.

Thirty-nine patients receiving chemotherapy for acute leukemia had weekly determinations of Candida precipitins by use of counterimmunoelectrophoresis. The only two patients who had proven disseminated candidiasis both had diagnostic (greater than or equal to 1/8) titers. However, most patients with "possible" disseminated candidiasis did not have diagnostic titers. The test's specificity was high (90%), and only one of five patients infected with other fungi had diagnostic titers. However, because there were so few "true positives" in this small series, the relatively small number of "false positives" resulted in a low predictive value for this test. Based on a review of the literature and the authors' experience, the value of this test for patients who have acute leukemia does not appear to be well established.

Adult↗
PubMed1979

Diffuse parenchymal amyloidosis of lungs and breast. Its association with diffuse plasmacytosis and kappa-chain gammopathy.

A patient had systemic amyloidosis that extensively involved the lungs and breasts. Diffuse parenchymal pulmonary amyloidosis is rare but well described. Involvement of the breast in systemic amyloidosis is, however, most unusual. This patient's amyloidosis was associated with diffuse plasmacytosis and a kappa-chain gammopathy. The plasmacytosis was most prominent in the renal interstitium. Immunoperoxidase staining of the renal infiltrate and breast demonstrated IgG/kappa-staining plasma cells exclusively, suggesting that these cells were a monoclonal proliferation that contributed to the patient's M-protein and possibly to the patient's amyloid deposits.

Amyloidosis↗
PubMed1978

Patho-radiologic correlation of invasive pulmonary aspergillosis in the compromised host.

The autopsy findings and antemortem radiographic abnormalities were correlated in 20 patients with invasive pulmonary aspergillosis to define typical radiographic patterns, their progression and anatomic basis. Sixteen (80%) patients had radiographic abnormalities due to aspergillosis. Fifty-nine percent of the specific radiographic abnormalities seen in these patients were caused by anatomic lesions of asperigillosis and 67% of such anatomic lesions were radiographically definable. The most common initial radiographic pattern was a patchy density (single or multifocal) or a well defined nodule. The densities remained stable in half the patients but progressed, over several weeks to either diffuse consolidation or cavitation in the others. Most anatomic lesions were categorized as either nodular ("target") lesions (1-3 cm in diameter) or hemorrhagic infarctions (5-10 cm in diameter), both due to vascular invasion causing thrombosis and ischemic necrosis. Unlike pulmonary candidiasis, which is usually radiographically undetectable, invasive pulmonary asperigillosis frequently caused radiographically visible lesions.

Adult↗
PubMed1978

Case report: subependymal and leptomeningeal spread of systemic malignant lymphoma demonstrated by cranial computed tomography.

Secondary involvement of the central nervous system by systemic malignant lymphoma is uncommon, although increasingly recognized. Histologically perivascular, leptomeningeal, and subependymal infiltration by tumor cells is characteristic. Less frequently, single or multiple macroscopic masses resembling other metastatic deposits are found. A patient is presented in whom periventricular and leptomeningeal involvement by systemic histiocytic lymphoma produced prominent symmetric surface oriented enhancement on computed tomography following intravenous infusion of contrast medium. Differential diagnosis is discussed.

Aged↗
PubMed1978

Significance of noncapsular antigens in protection against experimental Haemophilus influenzae type b disease: cross-reactivity.

A bacterial strain, tentatively identified as an Actinobacillus species, was found to asymptomatically colonize the pharynx of some rats and to bear cell wall antigens which cross-react with noncapsular antigens of Haemophilus influenzae type b (HIb). The cross-reacting antigens appeared to be a heterogeneous mixture with varying molecular size and charge. The antigenic moieties are probably carbohydrate in nature. Antisera raised with this strain had both immunochemical and biological (bactericidal, opsonizing, and protective against experimental infection) activity against HIb. These findings lend further evidence to the idea that noncapsular antigens are important in the induction of resistance to HIb disease. The findings also raise the possibility of using bacteria which cross-react with noncapsular antigens for immunization against HIb disease in humans through nasopharyngeal or enteric colonization.

Animals↗
PubMed1978

Ultrastructural observations in disseminated candidiasis.

Infected tissues from four patients with disseminated candidiasis were examined by electron microscopy in order to study the host-parasite relationship at the cellular level. Blastospores and pseudohyphae were capable of invading parenchymal cells in the spleen, liver, myocardium, kidney, and esophageal and rectal mucosa. The Candida cells were typically well preserved despite the autolytic changes in parenchymal cells. Extracellular fungi were often coated with fibrin or associated with capillary thrombi, which suggests that Candida cells synthesize a procoagulant substance. The outer flocular coat of the yeast cell appeared to be partially of host origin since it diminished in thickness when organisms were cultured in media devoid of serum protein. Organisms cultured in vitro were ultrastructurally similar to those that invaded tissue.

Candida↗
PubMed1977

Pathoradiologic correlation of pulmonary candidiasis in immunosuppressed patients.

The diagnosis of pulmonary candidiasis can only be made with certainty when tissue invasion by the organism is demonstrated histologically. In order to ascertain whether characteristic radiographic patterns are seen in patients with pulmonary candidiasis, antemortem radiographic abnormalities were correlated with autopsy findings in 25 immunosuppressed patients who had histoinvasive pulmonary candidiasis. Pathological analysis enabled division of patients by route of infection into hematogenous and endobronchial groups, characterized by disseminated nodules and patchy bronchopneumonia, respectively. However, no specific radiographic patterns emerged in either patient group due to the small size of lesions and the high frequency of other pulmonary infections, edema, and hemorrhage. Since the radiographic patterns described for other opportunistic fungi do not appear to apply to this organism, a decision to institute antifungal therapy should not await evolution of radiographic changes.

Candidiasis↗