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Biomedical subjects

G Nash

Publications and source records attributed to G Nash.

At least 37 records · Page 2Linked to original sources
PubMed1995

The pathology of AIDS.

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AIDS-Related Opportunistic Infections↗
PubMed1994

The pathological manifestations of pulmonary toxoplasmosis in the acquired immunodeficiency syndrome.

Pulmonary toxoplasmosis, once considered a rare complication of human immunodeficiency virus infection, recently has been reported with increasing frequency in patients with the acquired immunodeficiency syndrome (AIDS). However, published descriptions of the pathologic changes have been scanty, involve mainly single cases, and appear to conflict. Four cases of pulmonary toxoplasmosis observed at autopsy in patients with AIDS were reviewed. Two of the patients presented with Toxoplasma pneumonia and in one the diagnosis was made antemortem by open lung biopsy. Two patterns of pulmonary lesions associated with Toxoplasma gondii pneumonia were identified and appeared to be related to the stage and intensity of the infection. A pattern of interstitial pneumonitis/diffuse alveolar damage with a fibrinous alveolar exudate appeared to antecede a necrotizing pneumonia characterized by large areas of parenchymal necrosis. In the former pattern T gondii tachyzoites were found in small numbers and were mainly intracellular, whereas in necrotic areas tachyzoites were numerous and were extracellular as well as intracellular. Histopathologic diagnosis of the infection required careful search for the organisms even when they were plentiful Immunohistochemistry identified far more organisms than could be appreciated with routine stains and confirmed the diagnosis.

AIDS-Related Opportunistic Infections↗
PubMed1992

Rapid switching to multiple antigenic and adhesive phenotypes in malaria.

Adhesion of parasitized erythrocytes to post-capillary venular endothelium or uninfected red cells is strongly implicated in the pathogenesis of severe Plasmodium falciparum malaria. Neoantigens at the infected red-cell surface adhere to a variety of host receptors, demonstrate serological diversity in field isolates and may also be a target of the host-protective immune response. Here we use sequential cloning of P. falciparum by micromanipulation to investigate the ability of a parasite to switch antigenic and cytoadherence phenotypes. Our data show that antigens at the parasitized cell surface undergo clonal variation in vitro in the absence of immune pressure at the rate of 2% per generation with concomitant modulations of the adhesive phenotype. A clone has the potential to switch at high frequency to a variety of antigenic and adhesive phenotypes, including a new type of cytoadherence behaviour, 'auto-agglutination' of infected erythrocytes. This rapid appearance of antigenic and functional heterogeneity has important implications for pathogenesis and acquired immunity.

Animals↗
PubMed1991

[Correlation between the results of Doppler velocimetry with spectral analysis and the viscosity of cord blood].

The contribution of rheological factors to be impedance of blood flow in the umbilical artery as determined by continuous wave Doppler ultrasound was investigated. Of the 51 pregnancies recruited, six were complicated by pre-eclampsia, 10 by intrauterine growth retardation, 15 by both pre-eclampsia and fetal growth retardation, and there were 20 controls. A significant correlation was demonstrated between both plasma viscosity and gestational age and the resistance index used to characterize the Doppler waveform. Multiple regression analysis demonstrated that changes in plasma viscosity explained 55 p. cent of the variance seen in the resistance index and that this was statistically significant. This finding is, however, unlikely to be of clinical significance as whole blood viscosity had an insignificant effect on the impedance in the umbilical artery. We postulate that vascular factors such as the number and calibre of the placenta arterioles are a more important determinant of umbilical artery impedance.

Blood Flow Velocity↗
PubMed1991

Abnormal neutrophil adhesion in sickle cell anaemia and crisis: relationship to blood rheology.

Defects in neutrophil adhesion and migration may contribute to the susceptibility to infection seen in sickle cell anaemia (SCA). These dynamic defects may be influenced by abnormalities in blood rheology found in this disorder. A whole blood model was used to study neutrophil adhesion in SCA patients: neutrophil adhesion to protein coated glass was quantitated by measuring the rate of disappearance of neutrophils from heparinized whole blood circulating through a perfusion chamber. Twenty-three adult patients (Hb SS) were studied in asymptomatic steady state, of whom nine were also studied during pain crisis, both before and 4-7 d after conventional therapy. Red cell and granulocyte filterability and whole blood and plasma viscosity were also measured. The half-time for disappearance from the perfusion system (t1/2) of neutrophils from patients in the steady-state was 93.5 +/- 8.4 min, compared to 49.1 +/- 2.8 min in normal age-matched controls (P = 0.001). In crisis t1/2 was further prolonged to 170.0 +/- 16.1 min (P = 0.01 v. steady state). After therapy, t1/2 decreased to 57.0 +/- 4.5 min (P = 0.001 v. pre-therapy state and P = 0.009 v. steady state) and was comparable to Hb AA controls. These findings reveal a neutrophil adhesion defect in SCA which worsens in crisis but is corrected following supportive therapy. Red cell filterability (expressed as average resistance to flow and pore-clogging particles) and white cell filterability (expressed as pore-clogging particles) were also abnormal in SCA and were found to correlate with neutrophil adhesion. Plasma viscosity also correlated with adhesion t1/2. The defect appears to be related to abnormal blood flow properties in SCA but the rheological factors cannot fully explain either the steady-state defect or the marked changes in neutrophil adhesion during crisis.

Adult↗
PubMed1991

Zirconium compound-induced pulmonary fibrosis.

Despite suspicion that inhalation of zirconium should be capable of causing human pulmonary disease, documentation of zirconium pneumoconiosis in humans has been lacking. We studied a likely case of zirconium compound-induced pulmonary fibrosis. The diagnosis was based on the following: (1) a history of gradual increase in symptoms and slowly progressing pulmonary fibrosis by chest roentgenogram compatible with a pneumoconiosis; (2) an appropriate history of exposure and a latency period of about 15 years before the onset of dyspnea and of roentgenographic changes; (3) analysis of open lung biopsy material revealing end-stage fibrosis and honeycombing, a moderate number of birefringent particles, and extremely high levels of a variety of zirconium compounds; and (4) no other potential cause of fibrosis. We conclude that zirconium should be considered a likely cause of pneumoconiosis and that appropriate precautions should be taken in the workplace.

Humans↗
PubMed1990

Parietal pleural changes in empyema: appearances at CT.

The parietal pleura bordering pleural space collections was analyzed with computed tomography (CT) in 35 patients with thoracic empyema, 30 patients with malignant effusion, and 20 patients with transudatory effusion. Enhancement of the parietal pleura was present in 96% of the 25 patients with empyema who underwent contrast material-enhanced examinations. Of the 35 patients with empyema, 86% showed thickening of the parietal pleura, 60% showed thickening of the extrapleural subcostal tissues, and 35% showed increased attenuation of the extrapleural fat. None of the 20 patients with transudatory effusion showed these findings. Of the 30 patients with malignant effusion, eight patients (27%) showed chest wall changes similar to those of the patients with empyema. However, two-thirds of these patients had a recognized superimposed complication (ie, sclerotherapy). Contrast-enhanced CT appears to be sensitive to chest wall changes in patients with empyema. CT study of the parietal pleura may help suggest occult pleural space infections and may influence therapeutic decisions that vary with the stage of empyema.

Adult↗
PubMed1990

Primary testicular choriocarcinoma with pulmonary metastases presenting as ARDS.

We report a case in which ARDS was the presenting manifestation of testicular choriocarcinoma with numerous metastases to the lungs. We also review the literature on other cases in which ARDS developed as a result of neoplastic infiltration of the lungs and stress the fact that it may be indistinguishable from ARDS from other causes. Because potentially effective chemotherapy for the neoplastic processes most commonly involved (ie, germ cell tumors, acute leukemia and lymphoma) is available, we emphasize the importance of considering a neoplastic disorder in the differential diagnosis of cases of otherwise unexplained ARDS. Early accurate diagnosis could conceivably result in an improved outcome in these cases.

Adult↗
PubMed1989

Correlation between Doppler flow velocity waveforms and cord blood viscosity.

The contribution of rheological factors to the impedance of blood flow in the umbilical artery as determined by continuous-wave Doppler ultrasound was investigated. Of the 51 pregnancies recruited, six were complicated by pre-eclampsia, 10 by intrauterine growth retardation, 15 by both pre-eclampsia and fetal growth retardation, and there were 20 controls. A significant correlation was demonstrated between both plasma viscosity and gestational age and the resistance index used to characterize the Doppler waveform. Multiple regression analysis demonstrated that changes in plasma viscosity explained 55% of the variance seen in the resistance index and that this was statistically significant. This finding is, however, unlikely to be of clinical significance as whole blood viscosity had an insignificant effect on the impedance in the umbilical artery. We postulate that vascular factors such as the number and calibre of the placental arterioles are a more important determinant of umbilical artery impedance.

Blood Flow Velocity↗
PubMed1989

Spontaneous disseminated panarteritis in laboratory beagle dogs in a toxicity study: a possible genetic predilection.

Disseminated panarteritis was found in 16 (9 males and 7 females) of 49 laboratory beagle dogs (25 males and 24 females) from one breeding kennel. The dogs had been used in a 6-month oral toxicity study. Panarteritis was not associated with clinical or gross abnormalities. The incidence was similar in the control and test article-treated groups. Mainly medium-sized arteries throughout the body, particularly intercostal arteries (at their aortic origin), and coronary, epididymal and thymic vessels were affected. Chronic mononuclear-cell periarteritis was the predominant feature. Mixed cellular inflammation of the wall, proliferation or degeneration of muscle cells, focal "fibrinoid" material in the tunica media, fragmented internal elastic lamina and intimal thickening associated with myointimal cellular proliferation also occurred. These histologic changes are compatible with those of immune arteritis. Round worm intestinal infestation and granulomas of visceral larva migrans were common in several organs. Statistical analyses suggested that the pedigree of dogs is related to panarteritis, but the presence or absence of parasitization alone is not. The possible roles of genetic predilection and/or parasites in the pathogenesis are discussed. This panarteritis is spontaneous and may complicate the interpretation of lesions in toxicity studies.

Animals↗
PubMed1989

Idiopathic bronchiolitis obliterans organizing pneumonia with peripheral infiltrates on chest roentgenogram.

We report five patients with chest roentgenograms showing peripheral infiltrates similar to that described for chronic eosinophilic pneumonia (CEP). While lung biopsy specimens (transbronchial and open in two and transbronchial only in three cases) revealed typical changes of bronchiolitis obliterans organizing pneumonia (BOOP) as the predominant finding in all cases, two cases had changes consistent with a resolving CEP. We speculate that (1) it may be common for BOOP to present with peripheral infiltrates, (2) chest roentgenograms showing peripheral infiltrates are not diagnostic of any specific entity, (3) idiopathic BOOP may represent the evolution of untreated CEP, (4) a lung biopsy may be a more appropriate initial approach than the therapeutic trial of corticosteroids when peripheral infiltrates of unknown origin are present, and (5) transbronchial biopsy may be adequate to establish a working clinical diagnosis of BOOP.

Adult↗
PubMed1988

Maternal blood viscosity and uteroplacental blood flow velocity waveforms in normal and complicated pregnancies.

According to the Poiseuille-Hagen law, viscosity influences flow resistance. A possible effect of blood viscosity upon the resistance index of the uteroplacental circulation as measured by continuous wave Doppler ultrasound was investigated in 50 pregnant women. It was found that blood viscosity variables explained only about 10% of the variation in the resistance index in all patients, which was not statistically significant. It is suggested, therefore, that the vascular contribution to flow resistance may be more important.

Blood Flow Velocity↗