Effect of continuous slow-speed running for 12 weeks on 10-14-year-old Indian boys.

Endurance training was conducted on a group of 41 East Indian boys aged 10-14 years and was compared with 25 untrained boys of the same age. A continuous slow-running method was adopted for 12 weeks. The intensity of the training was 80-85% of maximum heart rate and frequency was 3 days per week. The boys were trained for a 1500-m event and therefore they covered three to five times their racing distance. For psychological reasons the training was carried out in a playground. The investigations included different physical and motor fitness tests: measurement of flexibility, agility, speed, leg muscle strength etc. Their performance times were also recorded before and after training. From statistical analysis we concluded that this particular type of training programme did not produce any detrimental effects on 10-14-year-old boys. On the other hand, this type of training did have some influence on improving physiological parameters in this age group of boys when compared with untrained boys of the same age.     

Intestinal neuronal disorders--a study of seven cases

Intestinal neuronal dysplasia (IND) has been reported as an innervation disorder that can present as isolated disease or may be associated with Hirschsprung's disease (HD). The interest in this disorder is growing as it mimics HD at clinical level but can be managed with a more conservative approach if an accurate diagnosis can be made. Many workers have tried to set up diagnostic criteria of this condition. But the importance of one criterion varied from one study to another. In our study we analysed seven cases of suspected innervation disorder that had undergone resection. A detailed histological study on these cases was performed and four of them were found to fulfill the diagnostic criteria of IND laid down by Kobayashi and his co-workers. These patients had hyperganglionosis, giant ganglia and ectopic ganglion cells in the lamina propria. In the other three cases some features were highly suggestive of the diagnosis of the IND and can be considered to be so if we follow other workers who have not given much importance to the simultaneous presence of all three criteria in a single case.     

Selection for high and low mating propensity inDrosophila ananassae

InDrosophila ananassae, artificial selection was carried out for high and low mating propensity for 15 generations. Response to selection was from about F₅, with rapid divergence in mating frequencies in replicates of both fast and slow lines. To assess the effect of selection on the two sexes, females and males of the selected lines were tested against their respective counterparts of the control line after 15 generations. Significant differences in mating propensity were observed when selected males were tested against the control females, which suggests that males were much more affected by selection than females. After 15 generations the fast and slow lines (both replicates) were crossedinter se and mating frequencies of F₁ hybrids were studied in the same way as during the selection experiment. F₁ flies had a higher mating activity compared to their parental lines when males were derived from fast lines to produce hybrids. On the other hand, F₁ hybrids produced by crossing slow-line males with fast-line females showed mating frequencies similar to those of the slow parental lines. These findings suggest that mating propensity inD. ananassae is under the control of polygenes. Furthermore, the significant differences in mating propensity of hybrids produced by the fast and slow males indicate the possibility of a Y-linked influence on mating propensity inD. ananassae.The present investigation was carried out during the tenure of a senior research fellowship of the CSIR, New delhi, to S.C.     

Transmission of lac by the sex factor E in Erwinia strains from human clinical sources

Lactose-utilizing (Lac(+)) strains of Erwinia spp. from human clinical material transfer lac by conjugation to plant strains of Erwinia herbicola and Erwinia amylovora, to other Erwinia strains from human clinical sources, and also to Escherichia coli, Paracolobactrum arizonae, Salmonella typhimurium, and Shigella dysenteriae. The frequency of this transfer varies with the donor and recipient strains employed. The lac genes appear stable in these exconjugants, and they are not cured by acridine orange. The Lac(+) exconjugants transfer lac to an Escherichia coli F(-) Lac(-) strain; the frequency of this transfer is high with E. herbicola and S. typhimurium exconjugants and relatively low with other exconjugants. The most studied Erwinia donor strain from human clinical material (EH133) and its Lac(+) exconjugants are insensitive to the F-specific phage, M13. P1-mediated transduction of lac, by using a Lac(+) exconjugant of E. coli as the donor and an E. coli F(-) Lac(-) strain as the recipient, revealed that all 50 Lac(+) transduced clones tested also inherited donor ability, suggesting a close linkage between the Erwinia sex factor (designated as E) and the lac genes. The E. coli culture harboring E-lac (E and the lac genes linked to it) does not restrict phages T1, T7, and lambdavir. E-lac is compatible with F'his, R100 drd-56 (F-like), and R64 drd-11 (I-like); cells harboring F'his or one of the R factors do not show super-infection immunity to the incoming E-lac, and E-lac plus one of the other plasmids can coexist stably in the same cell. The fertility of cells harboring F'his or R100 drd-56-as determined by the frequency of conjugal transfer of his or of the resistance determinant (Tet(r) in case of R100 drd-56) and also by sensitivity to F-specific phage (M13)-is not altered by the presence of E-lac, and this suggests that the sex factor E might belong to the fi(-) class.     

Role of a large plasmid of Salmonella typhi encoding multiple drug resistance

Twenty isolates of Salmonella typhi from cases of typhoid during the 1989-1990 epidemic in Calcutta were examined. Most isolates (84% of all isolates in the epidemic) were resistant to chloramphenicol, ampicillin, tetracycline and streptomycin but were sensitive to nalidixic acid and ciprofloxacin. Plasmids of 120 kb and 14 kb were identified amongst the multi-drug resistant isolates of S. typhi. However, there was no plasmid in the antibiotic-sensitive isolates. The 120-kb plasmid was transferable and transconjugants were resistant to chloramphenicol, ampicillin, tetracycline and streptomycin. Restriction endonuclease analysis patterns after EcoRI digestion of the 120-kb antibiotic-resistance plasmids from the S. typhi isolates and transconjugants were similar.     

A conserved peptide sequence of the Plasmodium falciparum circumsporozoite protein and antipeptide antibodies inhibit Plasmodium berghei sporozoite invasion of Hep-G2 cells and protect immunized mice against P. berghei sporozoite challenge.

Minutes after injection into the circulation, malaria sporozoites enter hepatocytes. The speed and specificity of the invasion process suggest that it is receptor mediated. The region II sequence of Plasmodium falciparum circumsporozoite (CS) protein includes a nonapeptide (WSPCSVTCG) which is highly conserved in all of the CS proteins sequenced to data, including the one from Plasmodium berghei. We have found that two peptides based on the P. falciparum region II sequence, P18 (EWSPCSVTCGNGIQVRIK) and P32 (IEQYLKKIKNS ISTEWSPCSVTCGNGIQVRIK), significantly inhibited P. berghei sporozoite invasion into Hep-G2 cells in vitro. This inhibition was enhanced if either peptide was preincubated with Hep-G2 cells prior to sporozoite invasion. We confirm that region II is a sporozoite ligand for the hepatocyte receptor; moreover, despite the few differences between P. falciparum and P. berghei region II sequences around the nonapeptide sequence (66% homology), the functional characteristics of the motif sequences are not affected. Since the conserved motifs represent a crucial sequence involved in Plasmodium sporozoite invasion of hepatocytes, antibodies to region II should inhibit sporozite invasion into hepatocytes. Indeed, we found that polyclonal antibodies generated to the P. falciparum-based peptide P32 inhibited P. berghei sporozoite invasion of Hep-G2 cells. Furthermore, inbred mice (C57BL/6) immunized with P32 were protected against a lethal challenge of P. berghei sporozoites. Our results suggest that the conserved region II of the CS protein contains crucial B- and T-cell epitopes, that such peptide sequences from the human malaria parasite P. falciparum can be screened in the P. berghei rodent model, and, finally, that region II can be considered useful as one of the components of a malaria vaccine.     

Mechanisms of nitric oxide interplay with Rho GTPase family members in modulation of actin membrane dynamics in pericytes and fibroblasts

Migration of pericytes such as hepatic stellate cells is fundamentally important for diverse biological and pathological processes including tumor invasion and fibrosis. In prototypical migratory cells such as fibroblasts, the small GTPases Rac1 and RhoA govern the assembly of lamellipodia and stress fibers, respectively, cytoskeletal structures that are integral to the cell migration process. The gaseous signaling molecule nitric oxide (NO) influences growth factor chemotactic responses, although this occurs primarily in cell-type-specific ways and through cell biological effects that are poorly characterized. In this study, we use complementary molecular and cell biological approaches to delineate important roles for Rac1, RhoA, and NO in migration of the human hepatic stellate cell line LX2 and primary rat hepatic stellate cells. Both platelet-derived growth factor (PDGF) and Rac1 overexpression drove migration through formation of actin-positive filopodia spikes in LX2 as compared to the formation of lamellipodia in fibroblasts. NO inhibited PDGF- and Rac1-driven migration in LX2 by abrogating filopodia formation and inhibited migration of fibroblasts by attenuating lamellipodial protrusions. Additionally, RhoA conferred resistance to NO inhibition of migration and restored chemotactic responses to PDGF in the absence of functional Rac1 in LX2. In conclusion, these studies identify novel crosstalk between small GTPases, cytoskeletal structures, and NO in pericyte-specific pathways, providing counterbalances in the chemotactic responses to growth factors.