Modulation of growth,ascorbate-glutathione cycle and thiol metabolism in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L. cv. MTU-1010) seedlings by arsenic and silicon

Arsenic is a carcinogenic metalloid, exists in two important oxidation states—arsenate (As–V) and arsenite (As-III). The influence of arsenate with or without silicate on the growth and thiol metabolism in rice (Oryza sativa L. cv. MTU-1010) seedlings were investigated. Arsenate was more toxic for root growth than shoot growth where the root lengths were short, characteristically fragile and root tips turned brown. The multiple comparison analysis using Tukey’s HSD (honest significant difference) tests indicated that the rate of arsenate accumulation and its conversion to arsenite by arsenate reductase were significantly increased in all arsenate treated seedlings while in seedlings treated jointly with arsenate and silicate, arsenate accumulation and its conversion to arsenite decreased. Silicate content was detected in the seedlings treated with silicate alone and under co-application of arsenate with silicate. In the test seedlings arsenic toxicity increased ascorbate and glutathione contents along with the activities of their regulatory enzymes, viz., ascorbate peroxidase, glutathione reductase, glutathione peroxidase and glutathione–s-transferase to reduce the toxicity level induced by arsenic whereas ascorbate oxidase activity was decreased to maintain sufficient ascorbate pool under arsenate treatment. Phytochelatins production were increased in both root and shoot of the test seedlings under arsenate exposure to alter the detrimental effects of arsenic by chelation with arsenite and their subsequent sequestration into vacuole. Thus, joint application of silicate along with arsenate showed significant alterations on all the parameters tested compared to arsenate treatment alone due to less availability of arsenic in the tissue leading to better growth and metabolism in rice seedlings. Thus use of silicon in arsenic contaminated medium may help to grow rice with improved vigour.     

Field validity, reproducibility and feasibility of diagnostic tests for visceral leishmaniasis in rural Nepal

OBJECTIVES: To assess the field accuracy, reproducibility and feasibility of the formol gel test (FGT), the urine latex agglutination test (KAtex) and a rK39 antigen-based dipstick for the diagnosis of visceral leishmaniasis (VL) in rural Nepal. METHOD: Patients with clinical suspicion of VL were recruited at Rangeli District Hospital (DH), a 15-bed government hospital located in south-eastern Nepal. FGT, KAtex and rK39 dipstick tests were performed on site and later repeated at a reference kala-azar diagnostic laboratory to assess reproducibility. Diagnosis of VL was confirmed by either a positive bone marrow aspirate examination or a positive direct agglutination test (DAT titre > or = 1:3200) in patients who later responded to anti-leishmanial therapy. RESULTS: Of 155 patients initially recruited, 142 (85 with VL and 57 with another diagnosis) were included in the study. The sensitivity of the rK39 dipstick [89%; 95% confidence interval (CI): 81-94] was significantly higher than that of the KAtex (57%; 95% CI: 46-67) and the FGT (52%; 95% CI: 41-62). All three tests had a specificity of at least 90%. Agreement was higher for the rK39 dipstick (kappa = 0.87) than for the FGT (0.68) and the KAtex (0.43). All tests required < or = 20 min of actual work and < or = 40 min to obtain the results. CONCLUSION: The rK39 dipstick was easy to do, more accurate and reproducible than other rapid diagnostic tests for VL in a DH of rural Nepal. It should be integrated into the field diagnostic algorithm of VL in this region and mechanisms to secure its availability should be found.     

Clinical analysis of glaucoma in hospital patients.

OBJECTIVES: (i) To determine the prevalence and pattern of glaucomas presented to Nepal Eye Hospital for strategic planning. (ii) To know the most common attributable factors giving rise to secondary glaucoma. (iii) To know the incidence of Glaucoma blindness. MATERIALS AND METHODS: A retrospective hospital based analysis of medical records of patients attending Nepal Eye Hospital Glaucoma clinic over a period of 2 years (Jan 2003-Jan 2005) was done in order to know the magnitude of the disease and its pattern, for planning purpose to upgrade Glaucoma clinic services in the hospital. RESULTS: Glaucoma patients comprised of 0.74% (827) of total outpatients (110794). Male and female ratio was 49.6%:50.4%. Primary Open Angle Glaucoma (POAG) found to be more common (57.3%), followed by secondary glaucoma (20.8%), Primary Angle Closure Glaucoma (PACG) 19.9% and Congenital/Juvenile and miscellaneous (2%). Incidence of Glaucoma blindness (Absolute Glaucoma) found to be 2.17%. Almost equal predelection to sex was seen in all types of glaucomas except PACG, Lens induced Phacomorphic glaucoma and uveitic glaucoma where female outnumbered males. The disease was found to be more common in age group above 40 years.     

Visual outcome and IOP control after cataract surgery in lens induced glaucomas

Lens induced glaucoma is one of the important cause of secondary glaucoma in our population. Retrospective analysis of 40 cases of lens induced glaucoma presenting to Nepal Eye Hospital from January 2002 to December 2004 were analyzed to find the prevalence of sex, age, visual outcome, IOP control, and duration between appearance of symptoms and surgical invention. Females out numbered male (55:45 percent). Phacomorphic glaucoma was seen more than phacolytic type (65:35). Visual recovery was good in 45% cases (6/12-6/60) and moderately fair in 30% cases (VA <6/60). Preoperative IOP ranged from 24.0-59.0 mmHg. Postoperative IOP ranged from 14-22 mmHg. Duration between symptoms and surgery was 1 week to 4 months.     

Gender variations in the prevalence of parasitic infections and the level of awareness in adolescents in rural Nepal

The study was conducted in rural school adolescent children to investigate the awareness and its association in parasitic infections in boys and girls. Of the 182 children examined 119 (65.3%) were male and 63 (34.6%) were female, age ranged 12-20 years with median age 15 years. Out of 182 stool samples examined 73 (40%) were found to be positive for parasites in which two or more parasites were found in 10 stool samples. Giardia lamblia 33 (18.1%) was the predominant parasite followed by hook worm 27 (14.8%) Entamoeba histolytica 13 (7.1%), Ascaris lumbricoides 05 (2.7%), Hyminolepis nana 02 (2.2%) and Trichuris trichiuria 01 (0.5%). Thirty-one (49.2%) in 63 females and 40 (33.6%) of the 119 males were positive for parasitic infections. The prevalence of worm infection was significantly higher in female children than male (p < or = 0.05). In contrast to the high parasitic prevalence rate in females they possessed significantly higher levels of awareness about parasitic infections. Out of 119 males 99 (83.2%) and 61 (96.8%) of the 63 females (p < or = 0.05) knew that worms suck food from host body. Similarly, 62.2% of males and 96.85 of females (p < or = 0.05) knew that parasites suck blood from human body. More study should be carried out to find out the gender difference in parasitic infection and level of exposure to risk factors.     

The sensitivity of clinical isolates of Leishmania from Peru and Nepal to miltefosine

Clinical isolates of Leishmania, from visceral leishmaniasis (VL) cases in Nepal and from cutaneous leishmaniasis (CL) cases in Peru, were cultured using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to type species and strain. Promastigotes from 38 isolates, within eight passages from isolation, were used to infect mouse peritoneal macrophage cultures in vitro, and the amastigote sensitivity to miltefosine was determined. The concentration required to kill 50% of intracellular amastigotes from Nepalese VL isolates, all typed as Leishmania (L.) donovani (N = 24) from both Sbv responders and nonresponders, ranged from 8.7 to 0.04 microg/mL. In contrast, the concentration required to kill 50% intracellular amastigotes from isolates from Peru, typed as L.(V.) braziliensis (N = 8), was > 30 to 8.4 microg/mL, L.(V.) guyanensis (N = 2) > 30 to 1.9 microg/mL, L.(L.) mexicana (N = 1) > 30 microg/mL, and L. (V.) lainsoni (N = 4) was 3.4 to 1.9 microg/mL. This demonstrates a notable difference in the intrinsic sensitivity of Leishmania species to miltefosine in vitro. If this model can be correlated to therapeutic outcome, it may have implications for the interpretation of clinical trials.     

PCR and direct agglutination as Leishmania infection markers among healthy Nepalese subjects living in areas endemic for Kala-Azar

Objective  To compare a PCR assay and direct agglutination test (DAT) for the detection of potential markers of Leishmania infection in 231 healthy subjects living in a kala-azar endemic focus of Nepal.
Methods  The sample was composed of 184 (80%) persons without any known history of KA and not living in the same house as known kala-azar cases (HNK), 24 (10%) Healthy Household Contacts (HHC) and 23 (10%) past kala-azar cases which had been successfully treated (HPK).
Results  PCR and DAT positivity scores were, respectively: HNK, 17.6% and 5.6%; HHC, 12.5% and 20.8%; HPK, 26.1% and 95.7%. The ratio PCR-positives/DAT-positives was significantly higher in HNK (ratio = 3.1) than in HHC (ratio = 0.6, P  = 0.036) and in HPK (ratio = 0.2, P  = 0.012). The ratio PCR-positives/DAT-positives did not significantly differ between HHC (ratio = 0.6) and HPK (ratio = 0.2, P  = 0.473). The positive agreement index between PCR and DAT in HNK was 5%; in HHC, 0%; in HPK, 43%.
Conclusions  Our study highlights the specific character of PCR and DAT for the exploration of Leishmania asymptomatic infections. PCR is probably more informative for very recent infections among HNK, while DAT provides more information among HHC and HPK, a feature likely related to the power of serology to track less recent infections.