Glial growth factor 2 induces proliferation and structural changes in ensheathing cells

Ensheathing cells were isolated from neonatal rat olfactory bulbs and cultured in the presence of glial growth factor 2 (GGF2). Proliferation assay showed that at concentrations of up to 60 ng/ml GGF2, ensheathing cells underwent a modest increase in proliferation rate. This stimulation was not maintained at high doses of GGF2 at 100 ng/ml or more. Chemotaxis chambers and scanning electron microscopy were used to determine whether GGF2 was a chemoattractant for ensheathing cells. Although the results showed no chemotactic response to GGF2, ensheathing cells demonstrated structural changes when cultured in the presence of 20 ng/ml GGF2. Ultrastructural observations revealed that GGF2 promoted increased deposition of extracellular matrix on the cell membrane, more cytoskeletal elements in the processes and as a possible consequence, contributed to a more rigid support. Ensheathing cells cultured in the absence of GGF2 often extended thinner and curved processes. Reverse transcription-polymerase chain reaction confirmed the presence of GGF2 transcripts in ensheathing cells, suggesting that ensheathing cells themselves are a source of GGF2.

Pulmonary aspergillosis in acquired immune deficiency syndrome: autopsy study of an emerging pulmonary complication of human immunodeficiency virus infection

Pulmonary aspergillosis has recently been described as an emerging infection in patients with acquired immune deficiency syndrome (AIDS), but the pathological changes have not been well documented. In this autopsy study, 17 cases of AIDS-related pulmonary aspergillosis were identified from the files of two institutions. With the exception of hypersensitivity reactions, the entire spectrum of pulmonary aspergillosis was represented. Thirteen patients exhibited acute invasive aspergillosis, and seven patients had evidence of subacute or chronic invasive infection, four of whom also had areas of acute invasion. One patient had necrotizing bronchial aspergillosis as well as acute invasive infection, and one individual had saprophytic colonization of a cavity caused by previous Pneumocystis carinii pneumonia (PCP) without evidence of invasive aspergillosis. The same conditions known to predispose immunocompromised individuals without human immunodeficiency virus (HIV) infection to invasive pulmonary aspergillosis were also identified in these patients with AIDS and included neutropenia, steroid therapy, and underlying lung disease. Additional pulmonary conditions were identified in all but one case and consisted mainly of infection or some form of chronic lung disease. In particular, half of the cases were associated with pulmonary fibrosis related to prior PCP. All cases occurred in or after 1990, confirming the perception of the recent emergence of aspergillosis in AIDS. As suggested by this study, one reason for this may be that patients with AIDS are now living long enough to develop one or more of the predisposing conditions for pulmonary aspergillosis.

Prevention of remote organ injury in cardiopulmonary bypass: the impact of flow generation technique

The purpose of this study was to investigate the effects of 3 different types of flow generation for cardiopulmonary bypass on gastrointestinal permeability and on neutrophil expression of CD11b, a surface marker of neutrophil activation. Fourteen patients undergoing elective coronary revascularization were selected randomly to receive 1 of the 3 flow generation techniques (roller, pulsatile, or centrifugal). Intestinal permeability was assessed by the fraction of an oral dose of 51chromium-ethylenediaminetetraacetate (51Cr-EDTA) recovered in the urine over 24 h. Neutrophil activation was determined by expression of CD11b markers at 6 time points. Overall, the 14 patients showed significant increases in intestinal permeability. It was not possible to demonstrate statistically significant differences among the flow generation groups; however, when compared to both roller pump groups, the centrifugal pump group showed a 3.2% reduction in intestinal permeability. There was no change in the expression of CD11b receptors throughout the time points, nor was there a relationship of CD11b markers to the flow generation technique.

Do fish acclimated to low temperature improve microcirculatory perfusion by adapting red cell rheology?

We have measured the rheological properties of individual red blood cells from fishes inhabiting different thermal environments and have also investigated the effects on red cells of acute in vitro temperature changes. The membrane shear elastic modulus (rigidity) increased markedly with decreasing temperature, and the dependence was similar if temperature was varied acutely in vitro or if cells were measured at normal body temperatures. Red cells from trout and Notothenia coriiceps had almost equal membrane rigidity at comparable temperatures and showed similar temperature-sensitivity in acute experiments. Entry times of trout cells into narrow (approximately 4 microm diameter) micropipettes also increased during in vitro reduction of temperature, and this could be explained largely by the temperature-dependence expected of aqueous solutions. Perhaps surprisingly, entry times did not vary when trout living at different temperatures were tested at these temperatures. Transit times of individual cells through somewhat larger pores (5 microm) in oligopore filters again increased with decreasing temperature in vitro (partly due to increasing fluid viscosity), but such transit times did show a similar temperature-dependence for cells from trout living at different temperatures. Thus, the temperature-dependence of cellular flow resistance appears to arise from variations in membrane rigidity and in the viscosity of fluid components, along with unquantified variations in components such as microtubular structures (which we found did not influence membrane rigidity but did affect pore entry time) and the cell nucleus. Thermal acclimation did not involve adaptation to compensate for increased membrane rigidity or a large pore transit time, with, at most, minor compensation in entry times into smaller pores. We conclude that impaired cellular rheology is not a major factor influencing circulation in fish at low temperature.

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.

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.

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.

Overwhelming necrotizing tracheobronchitis due to inadequate humidification during high-frequency jet ventilation

Necrotizing tracheobronchitis (NT) associated with conventional mechanical ventilation or high-frequency jet ventilation (HFJV) is a lesion reported most often in neonates. In most cases, a specific cause is not identified. We describe a case of NT in an adult that occurred during HFJV and was attributable to inadequate humidification.

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.

[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.

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.