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Biomedical subjects

R Greene

Publications and source records attributed to R Greene.

At least 145 records · Page 8Linked to original sources
PubMed1985

Two calcium-sensitive spike after-hyperpolarizations in visceral sensory neurones of the rabbit.

Intracellular recordings were made from rabbit nodose neurones in vitro. Two temporally distinct spike after-hyperpolarizations (a.h.p.s) were identified in a subpopulation of C-type neurones. The fast a.h.p. after a single spike lasted no longer than 500 ms, while the slow a.h.p. persisted for seconds. Both a.h.p.s. were increased in amplitude in low K+ (0.56 mM) solutions and decreased in amplitude in high K+ (11.2 mM) solutions, and both were reversed at hyperpolarized membrane potentials. The slow a.h.p. was reduced in low Ca2+ (0.22 mM), in the presence of Ca2+ antagonists (Ni2+, 1 mM; Cd2+, 100 microM; or Co2+, 1 mM) and was enhanced in tetraethylammonium (5 mM). In approximately half of the cells tested, the fast a.h.p. was reduced in low Ca2+ and in the presence of the Ca2+ antagonists. In the remaining cells the fast a.h.p. was insensitive to these procedures. Prostaglandin (PGE1, 1-10 micrograms/ml) reduced the slow a.h.p. in all cells tested. Neither the Ca2+-sensitive nor the Ca2+-insensitive fast a.h.p. was affected by the prostaglandin. It is concluded that there is a subpopulation of C-type nodose neurones possessing a slow a.h.p. which is due to a Ca2+-dependent K+ current. This subpopulation of neurones can further be divided on the basis of the presence of a Ca2+-sensitive fast a.h.p. Furthermore, PGE1 pharmacologically separates the fast and slow a.h.p.s by selectively blocking the slow one. The blockage by the PGE1 is most probably not due to a reduction in Ca2+ influx.

Action Potentials↗
PubMed1985

Supplementary tissue-core histology from fine-needle transthoracic aspiration biopsy.

Biopsies of 150 consecutive suspected lung cancers were performed with fine needles having circumferentially beveled tips that produced cytology and tiny tissue cores suitable for histology. Visible tissue cores were aspirated in 92% (n = 138) and histologic diagnoses were obtained in 72% (n = 108). There were 118 (79%) proven malignant and 27 (18%) proven benign lesions. Sensitivity and specificity of cancer diagnoses were 97% and 100%, respectively. Biopsy histology was the only positive cancer specimen in two biopsies (1.7%). Biopsy cytology was the only positive cancer specimen in 20 cases (17.2%). Biopsy cytology and histology agreed with the proven cell type in 71.8% and 78.6% of cancers, respectively. As expected, when large-cell undifferentiated carcinoma was regarded as a nonspecific cell type consistent with either poorly differentiated adenocarcinoma or poorly differentiated epidermoid carcinoma, biopsy-cell-type accuracy increased greatly. Specific benign diagnoses were obtained in 44% of the 27 biopsies of proven benign lesions: cytology (four), core histology (five), and bacteriology (nine). Simple and complicated pneumothorax occurred in 10% and 4% of biopsies, respectively. It was concluded that biopsy with fine, circumferentially beveled needles can produce useful histology to supplement biopsy cytology.

Adenocarcinoma↗
PubMed1984

Septic bursitis in systemic lupus erythematosus.

Septic olecranon bursitis developed in three patients with systemic lupus erythematosus. Although promptly treated with systemic antibiotics, the clinical course in two patients became prolonged and eventually required bursectomy to eradicate the infection. The occurrence of septic bursitis was a manifestation of the general susceptibility of SLE patients to infections.

Adult↗
PubMed1984

Asbestos-related pleural thickening: effect of threshold criteria on interpretation.

Radiographic evidence of pleural thickening was evaluated in 1,216 shipyard workers (high-risk group) and 214 executives (low-risk group) and classified according to two threshold levels: low (any detectable thickening) and high (thickening less than or equal to 2 mm excluded). Results were markedly different, affecting the low-risk group more than the high-risk group. Changing from the high to the low threshold markedly increased pleural findings and scores as well as inter-reader correlation while reducing both differences between risk groups and detection of additional findings on supplementary oblique views. When data on prevalence and extent of pleural thickening were combined, differences between risk groups were maximized; however, when only prevalence was considered, such differences were minimized, particularly with a low threshold. These findings indicate that different or ambiguous threshold criteria produce divergent results in screening surveys for asbestos-related disease. The authors recommend that explicit minimal pleural threshold criteria be adopted.

Adult↗
PubMed1983

Respiratory distress syndrome with new considerations.

To help maximize the salvage rate of patients with ARDS, radiologists must become active participants in a multidisciplinary team. A clear understanding of the nature of ARDS is a prerequisite. The authors briefly consider the pathogenesis of the syndrome and then discuss at length the usefulness of plain radiography and balloon occlusion pulmonary angiography in examining the patient with ARDS.

Angiography↗
PubMed1983

The pulmonary vascular lesions of the adult respiratory distress syndrome.

Specimen arteriography, morphometry, and light and electron microscopy were used for examination of the pulmonary vasculature of 22 patients who died with the adult respiratory distress syndrome (ARDS), for the purpose of defining the lesions that contribute to pulmonary hypertension in this setting. The different lesions correlated with the duration rather than the cause of ARDS. Thromboemboli occurred in 21 patients, and macrothrombi found at autopsy correlated with the number of filling defects on antemortem angiography. Acute endothelial injury was documented ultrastructurally even in intermediate and late-stage patients. Fibrocellular intimal obliteration of arteries, veins, and lymphatics and infective vasculitis were prominent in those surviving beyond 10 days. In long-term survivors, tortuous arteries and irregularly dilated capillaries were striking features. Peripheral extension of vascular smooth muscle and a significant increase in the percentage of medial thickness of muscular arteries with duration of ARDS were noted. The pathogenesis and clinical significance of these lesions is discussed.

Angiography↗
PubMed1982

Incremental value of oblique chest radiographs in the diagnosis of asbestos-induced pleural disease.

To assess the value of oblique chest radiographs in the diagnosis of asbestos-related pleural disease, we identified 100 asbestos-exposed construction workers and provided separate interpretations of the postero-anterior (PA), left anterior oblique (LAO), and right anterior oblique (RAO) projections using the International Labour Office (ILO) system. We found that the LAO projection identified left-sided pleural thickening more effectively than the PA view and the RAO view improved diagnosis of right-sided disease comparably. Of 62 cases of bilateral pleural thickening, only 43 (68%) were diagnosed by the PA projection alone. The increased diagnostic efficiency of approximately 50% in identifying bilateral pleural thickening appears to justify the routine use of oblique chest films in screening asbestos-exposed populations. Since bilateral pleural thickening among asbestos-exposed workers is an indicator of significant asbestos exposure and increased risk of other asbestos-induced conditions, early detection of this abnormality can lead to interventions designed to reduce asbestos-related morbidity and mortality.

Adult↗
PubMed1982

Mitomycin C: phase I study of a constant infusion ambulatory treatment schedule.

Thirty patients received mitomycin C by constant infusion for 5 consecutive days (16 patients ) or for extended period by an ambulatory infusion pump (Cor-Med model) for 9 to 30 days (14 patients). The short-term 5-day infusions were delivered at dose rates of 2, 3, 4, 5 and 6 mg/m2/d with a cumulative dose of 15-50 mg. The protracted infusions were delivered at dose rates of 0.75-3 mg/m2/d with a cumulative dose of 21.6-65.2 mg. Marrow suppression was dose-limiting and occurred in 5/6 evaluable patients receiving more than 30 mg in the short-term infusion schedule and 8/10 evaluable patients receiving more than 20 mg in the protracted infusion schedule. The characteristics of the marrow suppression are that: a) thrombocytopenia precedes or is observed without concomitant leukopenia and b) the nadir day is delayed (WBC day 42, platelet day 36). Mitomycin C delivered by constant infusion leads to dose-limiting marrow toxicity at 20 to 30 mg cumulative dose depending upon the dose rate and duration of treatment. For short-term 5-day therapy, 3 mg/m2/d and for protracted therapy (up to 30 d) 0.75 mg/m2/d are the recommended dose rates for the constant infusion schedule.

Adult↗
PubMed1981

The pulmonary aspergilloses: three distinct entities or a spectrum of disease.

The fungus Aspergillus can cause any of three clinical presentations--invasive aspergillosis, mycetoma, or allergic bronchopulmonary aspergillosis--or a disease process in which one of these entities overlaps with another process such as mucoid impaction, eosinophilic pneumonia, bronchocentric granulomatosis, "farmer's lung," or asthma. More than one form of the disease may be present at the same time; in addition, limited invasion may occur even in "noninvasive" forms of the disease, and the clinical and pathological aspects of allergic aspergillosis are often indistinguishable from those of unrelated allergic conditions. Thus it is no longer possible to compartmentalize the various types of pulmonary aspergillosis into exclusive forms of the disease; rather, the radiologist should be aware that various factors can modify the mode of growth of the fungus as well as the patient's response.

Aspergillosis↗
PubMed1981

Results of exercise tests and prognosis in postinfarction patients below age 40.

In a follow-up study (mean = 3.6 years) of 555 men under 40 years of age (mean = 35.7 years) who had recently suffered transmural myocardial infarction, 44 patients (7.9%) suffered cardiac death with an annual rate of 2.2%. In a bivariate analysis a significant correlation was found between cardiac death and work capacity (p less than 0.02), vessel involvement (greater than 50% stenosis), left ventricular impairment as evaluated by ventriculography (p less than 0.001) and heart volume enlargement (p less than 0.01). There was no significant correlation between the degree of ST-segment depression and ventricular premature depolarisation (during exercise test). Complex results from non-invasive approaches can identify groups with good and bad prognosis as effectively as invasive techniques.

Adult↗