Control of lymphocyte migration into brain: selective interactions of lymphocyte subpopulations with brain endothelium.

The protein antigens conalbumin (CA) and ovalbumin (OVA) are known to require uptake into antigen-presenting cells (APC) for their presentation to major histocompatibility complex (MHC) class II-restricted T cells. In both cases proteolytic cleavage is thought to be a necessary step for the generation of the respective antigenic peptides. A specific inhibitor of the endosomal protease cathepsin B, Cbz-Phe-Ala-CHN2, blocks the presentation of both CA and OVA, whereas this inhibitor has no effect on the presentation of a processing-independent OVA peptide. Furthermore, the presentation of insulin, an antigen that needs processing but no proteolytic cleavage, is enhanced when cathepsin B is inhibited during antigen pulsing. When the APC were treated with an inhibitor of acid proteases, the CA response was not affected, while the presentation of OVA was diminished under these conditions. To estimate the relevance of these findings for the generation of the antigenic CA peptide, extracellular digestions of CA by cathepsin B were carried out. The fragment(s) present in these digests was recognized by T cells without further processing. Furthermore, the time-course of intra- and extracellular CA processing with respect to the capacity to stimulate T cells was similar. Taken together these data suggest that degradation by cathepsin B may be sufficient in vivo to generate the antigenic CA fragment. On the other hand, the blocking of cathepsin B does not appear to have an adverse effect on the general mechanisms of antigen presentation.     

Coronary artery lesions in Takayasu's arteritis--clinical and angiographic study

Two hundred and twenty five patients of Takayasu's arteritis were studied over 13 years. Male:Female ratio was 1:7. Mean age of the study population was 19 +/- 4 years. Of these 225 patients, 75 patients had symptoms and/or signs of cardiac involvement and these patients were subjected to coronary angiography. Significant coronary artery occlusion (i.e. more than 50% narrowing of luminal diameter) was present in 9 patients. Incidence of coronary artery lesions in Takayasu's arteritis is 12% in this study. The proximal segments of coronary arteries were involved while the distal segments were spared. Out of 34 patients with angina pectoris, only 3 patients had significant coronary arterial narrowing.     

Complementation of coat protein-defective TMV mutants in transgenic tobacco plants expressing TMV coat protein

Transgenic tobacco plants (Nicotiana tabacum cv. Xanthi) which express tobacco mosaic virus (TMV) U1 strain coat protein (CP) can complement both the assembly and the long-distance spread of CP-defective (DT1) or coat proteinless (DT1G) mutants of TMV. Both mutants arose spontaneously from PM2 and exist only as unencapsidated RNA in the inoculated leaves of control tobacco plants, where they are unable to form virus particles or to spread systemically. TMV CP expressed in transgenic tobacco plants [CP+ line 3404; P. Powell Abel, R. S. Nelson, B. De, N. Hoffman, S. G. Rogers, R. T. Fraley, and R. N. Beachy, 1986, Science 232, 738-743] was able to package some of either mutant viral RNA into TMV-like particles in vivo and resulted in the long-range spread of infection. In vivo encapsidated DT1 RNA was recovered and reinoculated onto control or new CP+ transgenic tobacco plants. Localized infection of control plants confirmed that no RNA recombination or reversion of the mutant RNA to wild-type had occurred during passage in the first CP+ plant. In contrast, encapsidated DT1 RNA was unable to produce even local infection in CP+ transgenic plants confirming that CP-mediated protection operates during the early stages of virus infection, including particle uncoating. By positive complementation, these results also confirm that TMV CP is required for the long-distance spread of infection.     

Effect of sodium arsenite on peripheral lymphocytes in vitro: individual susceptibility among a population exposed to arsenic through the drinking water

Arsenic (As) contamination in ground water has affected more than 19 countries. Approximately 36 million people in the Bengal delta alone are exposed to this toxicant via drinking water (>50 microg/l) and are at potential health risk. Chronic ingestion of As via drinking water is associated with occurrence of skin lesions, cancer and other arsenic-induced diseases in West Bengal, India. An in vitro cytogenetic study was performed utilizing chromosomal aberrations (CA) in lymphocytes treated with sodium arsenite (0-5 microM) in six symptomatic (having arsenic-related skin lesions) individuals, six age- and sex-matched As-exposed asymptomatic (no arsenic-related skin lesions) individuals and six control individuals with similar socio-economic status residing in non-affected districts of West Bengal with no evidence of As exposure. The mean As content in nails and hair was 9.61 and 5.23 microg/g in symptomatic, 3.48 and 2.17 microg/g in asymptomatic and 0.42 and 0.33 microg/g in the control individuals, respectively. The main aim of our study was to determine whether genotoxic effects differed in the lymphocytes of the control (no exposure to arsenic), asymptomatic and symptomatic individuals after in vitro treatment with sodium arsenite. Although both the exposed groups had chronic exposure to As through the drinking water, individuals with skin lesions accumulated more As in their nails and hair and excreted less in urine (127.80 versus 164.15 microg/l). The results show that sodium arsenite induced a significantly higher percentage of aberrant cells in the lymphocytes of control individuals than in the lymphocytes of both the exposed groups. Within the two exposed groups As induced higher incidences of CA in the symptomatic than the asymptomatic individuals. These results suggest that asymptomatic individuals have relatively lower sensitivity and susceptibility to induction of genetic damage by As compared with the symptomatic individuals.     

Role of imprint cytology in the diagnosis of gastrointestinal tract malignancies

Endoscopic biopsies obtained from 275 patients (180 from the upper gastrointestinal tract and 95 from the lower gastrointestinal tract) were studied to compare the accuracy of biopsy imprint cytology and histology in the diagnosis of gastrointestinal lesions, and also to establish the degree of reliability of imprint cytology alone for an early diagnosis of malignancy. Biopsy histology results were found to be correct in 100% cases. Imprint cytology had an overall accuracy of 100%, 96.7%, 95.8% and 95.8% for the diagnosis of malignancies of the oesophagus, stomach, duodenum and colorectum respectively. False negative results were obtained with lymphomas. Regenerative cellular atypia was an important cause for false positive results. It was concluded that imprint cytology can serve as a useful and simple tool for an immediate diagnosis of malignancy. This should be subsequently correlated with histopathology which facilitates exact tumour typing and assessment of tumour invasion.     

First histological observations on the incorporation of a novel calcium phosphate bone substitute material in human cancellous bone

Calcium phosphates are frequently used as bone substitute materials because of their similarity to the mineral phase of bone, absence of antigenicity, and excellent osteoconductivity. However, in most currently available mineral substitutes, resorption occurs slowly if at all. In contrast, calcium phosphate cements have shown rapid resorption and remodeling in animal studies. In two prospective studies, a novel amorphous calcium phosphate cement (Biobon) was implanted in human patients for the first time. After 2-12 months, ten biopsies were obtained from nine individuals during secondary surgical interventions, for example, for implant removal. In all specimens, partial replacement of the material by new bone was observed, while residues of the cement were still visible. Undecalcified sections revealed extensive bone formation in immediate contact to the cement without fibrous interface. Polynucleated cells and superficial lacunae were indicative of resorptive activity, but inflammatory tissue response was absent. The new bone displayed regular trabecular and osteonal patterns. The histologic findings are in accordance with the excellent biocompatibility observed in the clinical follow-up. Though still incomplete, the resorbability of this cement appears superior to sintered calcium phosphates in these biopsy specimens. Presumably this is due to its amorphous crystalline structure. Biobon merits further studies as a promising substance for bone defect reconstruction in non-stress-bearing areas.     

Immobilization of antibodies on a new solid phase for use in ELISA

Antibodies to myoglobin were immobilized by covalent linkage to polyester film for use in a solid-phase ELISA. The covalent linkage of antibody to this new solid phase was accomplished by partial acid hydrolysis of the film followed by periodate oxidation. About 60 ng of protein could be immobilized per cm2 of film and the binding was stable. Antimyoglobin IgM immobilized on the films was used in the ELISA technique to detect myoglobin within the range 0.25-10 ng. The assay procedure was found to be very accurate and the coefficient of variation of each concentration ranged from 0.63 to 2.1%. Furthermore the immobilized film could be re-used after dissociating the antigen antibody complexes.     

Development and evaluation of a phage typing scheme for Vibrio cholerae O139

The scenario of cholera that existed previously changed in 1992 and 1993 with the emergence of toxigenic Vibrio cholerae O139 in India. The genesis of the new serogroup formed the impetus to search for O139 phages in and around the country. A total of five newly isolated phages lytic to V. cholerae O139 strains were used for the development of this phage typing scheme. These phages differed from each other and also differed from the existing O1 phages in their lytic patterns, morphologies, restriction endonuclease digestion profiles, and immunological criteria. With this scheme, 500 V. cholerae O139 strains were evaluated for their phage types, and almost all strains were found to be typeable. The strains clustered into 10 different phage types, of which type 1 (38.2%) was the dominant type, followed by type 2 (22.4%) and type 3 (18%). Additionally, a comparative study of phage types in 1993 and 1994 versus those from 1996 to 1998 for O139 strains showed a higher percentage of phage type 1 (40.5%), followed by type 3 (18.8%) during the period between 1993 and 1994, whereas phage type 2 (32. 1%) was the next major type during the period from 1996 to 1998. This scheme comprising five newly isolated phages would be another useful tool in the study of the epidemiology of cholera caused by V. cholerae O139.     

Effect of lycoriside,an acylglucosyloxy alkaloid,on mast cells

The effect of lycoriside, an acylglucosyloxy alkaloid from Crinum asiaticum Linn, (family Amaryllidaceae), with or without sitosterol-3-O--D-glucoside, was studied on the rate of degranulation of peritoneal mast cells of albino rats. Lycoriside, at lower concentrations (1–20 µg/ml), in vitro, produced statistically significant protection against Tween 80-induced degranulation, as also to sensitized mast cells challenged with an antigen (horse serum). It also provided protection against compound 48/80-induced degranulation of mast cells when administered in vivo (1–5 mg/kg, po). At higher concentrations (100 µg/ml and above), in vitro, however, it had a mast-cell degranulation effect per se. The addition of sitosterol-3-O--D-glucoside to lycoriside did not modify the effect of the latter compound. The mechanism of the dual response elicited by lycoriside is appraised in view of a concentration-dependent anti- or prerelease effect on mast-cell mediators.