Limits on gravitational-wave emission from selected pulsars using LIGO data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Surface antigen variability and variation in Giardia lamblia

Recent studies show that Giardia isolates are heterogeneous but fall into at least three groups as determined by a number of complementary techniques. Giardia undergoes surface antigenic variation, both in vitro, and in humans and other animal model infections. Many of the characteristics of antigenic variation and the proteins involved, called variant-specific surface proteins (VSPs), are unique. The sequences of five VSPs reveal a family of cysteine-rich proteins. Here Theodore Nash reviews the relationship between antigenic variation and Giardia heterogeneity.

Cell column chromatography: a new research tool to quantify cerebral cell volume changes following chemically-induced anoxia/re-oxygenation

OBJECTIVE

The roles of individual types of cerebral cells in contributing to brain edema are undefined. The objective of this study was to determine the role of cerebral cell-column chromatography in quantifying cell volumes of individual cerebral cell lines, under chemically-induced anoxia/re-oxygenation (A/R).

METHODS

Cerebral endothelial cells (4 experiments) or type II astrocytes (4 experiments) were cultured to confluence on microcarrier beads. A chromatographic cell-column of 1.5 cm height was filled with non-treated cell-covered beads. The column was perfused at 1 ml/min with a balanced perfusate for one hour (Baseline). The perfusate was then switched to that containing 5 mM thioglycolic acid for one hour (Anoxia). Then the column was perfused with the normal perfusate for another two hours (Re-oxygenation). The total free space in the column, reversely reflecting cell volumes, was determined by averaged transit time (TTa) of a non-permeable flow tracer blue dextran. Decreased TTa means that cells swell, and vice versa.

RESULTS

TTa in endothelial cell columns increased with a peak at 60 minutes of re-oxygenation. TTa in astrocyte columns decreased with a nadir at 30 minutes of re-oxygenation.

CONCLUSION

Cell column chromatography can be used to determine the cerebral cell volume changes following chemically-induced anoxia/re-oxygenation.

Gamma interferon influences intestinal epithelial hyperplasia caused by Lawsonia intracellularis infection in mice

Lawsonia intracellularis is a recently identified bacterial pathogen which causes disease in a broad range of animals. Invasion of intestinal epithelial cells and the resultant hyperplasia of infected cells are central processes in disease pathogenesis. In this study, we aimed to establish whether immunocompetent mice were susceptible to infection and whether gamma interferon (IFN-gamma) contributed to the pathogenesis of infection. Wild-type 129-Sv-Ev mice (129 mice) and IFN-gamma receptor knockout mice based on the 129 background (IFN-gammaR(-)) were challenged orally with approximately 5.5 x 10(7) L. intracellularis cells. Both 129 and IFN-gammaR(-) mice became infected, although the extent of infection (as determined by the proportion of infected crypts) was substantially lower in 129 mice than in IFN-gammaR(-) mice. Despite these differences, infected crypts showed characteristics typical of proliferative enteropathies of other animals, i.e., intracellular colonization of epithelial cells by L. intracellularis with resultant epithelial hyperplasia. Infection in 129 mice was cleared between days 21 and 28 postchallenge, whereas infection in IFN-gammaR(-) mice was evident in 100% of animals from day 21 onward. Additionally, in IFN-gammaR(-) mice the infection was so extensive that fatalities resulted. IFN-gamma therefore plays a significant role in limiting intracellular infection and increased cellular proliferation associated with L. intracellularis. L. intracellularis infection is generally associated with modest cellular infiltration; therefore, further comparative examinations will be necessary to determine pathogenicity factors and define the role of IFN-gamma in controlling this infection.

Lung epithelial cells are a major site of murine gammaherpesvirus persistence

It is currently believed that latently infected, resting B lymphocytes are central to gammaherpesvirus persistence, whereas mucosal epithelial cells are considered nonessential. We have readdressed the question of nonlymphoid persistence using murine gammaherpesvirus 68 (MHV-68). To dissect lymphoid from nonlymphoid persistence, we used microMT transgenic mice that are defective in B cells. MHV-68 DNA persisted in the lungs of intact and B cell-deficient mice. Both episomal and linear forms of the virus genome were present in lungs, implying the presence of both latency and productive replication. In situ hybridization for virus tRNA transcripts revealed latent MHV-68 in pulmonary epithelial cells. Infectious virus was recovered from the lungs of microMT mice after T cell depletion, showing that the persisting virus DNA was reactivatable. Finally, using adoptive transfer of B cells into B cell-deficient mice, it was shown that virus persisting in lungs seeded splenic B cells, and virus resident in the spleen seeded the lungs. These results show that mucosal epithelia can act as a nonlymphoid reservoir for gammaherpesvirus persistence, and that there is a two-way movement of virus between lymphoid and nonlymphoid compartments during persistence.

Efficacies of zinc-finger-active drugs against Giardia lamblia

Twenty-nine of 34 (85%) Zn-finger-active compounds at 300 microM or less inhibited the growth of Giardia lamblia. The most active compound, disulfiram (Antabuse), was cidal at 1.23 +/- 0.32 microM. In the adult mouse model, significant in vivo activity was demonstrated by increased cure rates and decreased parasite burdens.

Nonsurgical therapy for pulmonary hydatid cyst disease

Therapeutic and diagnostic aspiration of Echinococcus granulosus liver cysts, but not pulmonary cysts, are increasingly being performed. Documented herein is the utility of percutaneous drainage and of albendazole treatment in a patient with a large recurrent, isolated, pulmonary echinococcal cyst for whom traditional therapy would have resulted in severe morbidity. Therapeutic options and possible complications are discussed.

Bilateral bronchoalveolar lavage in the diagnosis of opportunistic pulmonary infections

To further improve the diagnostic value of bronchoscopy in the immunosuppressed population presenting with diffuse pulmonary infiltrates, we prospectively investigated the utility of bilateral bronchoalveolar lavage (BAL). We performed 62 bronchoscopies on 52 immunosuppressed patients. Of the 52 patients, 33 had pulmonary infections. The yield for Pneumocystis carinii pneumonia on bilateral BAL was 94 percent (31/33), compared to the 84 percent (51/61) previously obtained with unilateral BAL in our institution. The recovery of P carinii was unilateral in four of five patients without AIDS and in four of 26 patients with AIDS. Transbronchial biopsy gave a yield of 85 percent (11/13). In ten patients with definitive cytomegalovirus (CMV) pneumonia, recovery of CMV by combined culture and cytology was 100 percent. Of nine bronchoscopies with positive cytology for CMV, five showed cytopathologic changes in the BAL from both sides and four in the BAL from one side only. No complications were seen in the 14 patients with thrombocytopenia or the five patients receiving mechanical ventilation. Our findings indicate that bilateral BAL significantly increases the yield for recovery of P carinii (p less than 0.02) and CMV (p less than 0.001) in immunosuppressed patients.

Variant surface antigens of Giardia lamblia are associated with the presence of a thick cell coat: thin section and label fracture immunocytochemistry survey

Giardia lamblia undergoes surface antigenic variation. The ultrastructural location of antigens on four different variants was studied by label fracture and immunocytochemistry with four monoclonal antibodies (MAbs), each of which recognized the predominant variant in a particular clone. Each Giardia clone and its reacting MAb showed similar findings. The entire surface of the organism was covered by a surface coat which contained the variant surface protein. The surface coat was densely and uniformly labeled. Unreacting MAbs failed to label the surface. Label-fractured Giardia trophozoites exposed to reactive MAb revealed a planar distribution of reactivity with no discernible relationship to visualized intramembranous particles. Unexpectedly, some Giardia trophozoites lacked a surface coat and consequently failed to react with the appropriate MAb. The biological relevance of coatless Giardia trophozoites is unknown. These findings localize the variant antigens to the surface coat of the parasite and identify a minority of the population which lacks a surface coat.

Oesophageal varices in a region of the Sudan endemic for Schistosoma mansoni

In a field study of two villages in the Gezira, an area of the Sudan endemic for Schistosoma mansoni, liver ultrasonography was used to detect subjects with Symmers' hepatic periportal fibrosis, some of whom underwent oesophagoscopy to detect oesophageal varices. The prevalence of oesophageal varices in subjects undergoing oesophagoscopy was 54 per cent and 67 per cent respectively, occurring mainly in males aged about 30 years. The varices were usually asymptomatic. Symptomatic varices (with a positive history of haematemesis) occurred in 4 per cent and 3 per cent respectively of subjects with sonographic evidence of liver periportal fibrosis. By detecting oesophageal varices in an asymptomatic phase, hepatic ultrasonography and fibreoptic oesophagoscopy may elucidate the natural history of the varices and their response to periodic anti-schistosomal chemotherapy.