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O P Singh

Publications and source records attributed to O P Singh.

At least 19 recordsLinked to original sources
PubMed2006

Isolation of a Plasmodium vivax refractory Anopheles culicifacies strain from India.

Anopheles culicifaciessensu lato comprises five sibling species. We report the isolation of an An. culicifacies species B strain which is completely refractory to Plasmodium vivax sporogonic development and partially refractory to P. falciparum. Parasite development in this strain is arrested by a melanotic encapsulation mechanism in the mid-gut. We compare the infectivity of this refractory strain and four other species B strains from different epidemiological zones of India with P. vivax in the laboratory.

Analysis of Variance↗
PubMed2006

Identification of all members of the anopheles culicifacies complex using allele-specific polymerase chain reaction assays.

Anopheles culicifacies, a complex of five isomorphic sibling species, is a major vector of malaria in India and neighboring countries. The five species are provisionally designated as species A, B, C, D, and E. Polytene chromosome examination has been the only method available that differentiates four members of this complex in areas where species E is not prevalent. However, this technique requires the mosquitoes to be in the half-gravid stage and thus limits its application to only about one fourth to one third of the total adult collection and excludes immature stages completely. For species E, both polytene chromosome examination and mitotic chromosome examination of F1 males are required. A polymerase chain reaction (PCR) assay based on the D3 domain (D3-PCR) of 28S rDNA and a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay involving ITS2 of rDNA are available for the discrimination of the members of the An. culicifacies complex. However, both these can only differentiate species A and D from species B, C, and E. We report here two allele-specific PCR assays (AD-PCR and BCE-PCR) using sequence differences in the mitochondrial cytochrome oxidase II (CO II) subunit. The AD-PCR assay distinguishes species A and D, whereas the BCE-PCR assay distinguishes species B, C, and E. Thus, with a combination of two PCR assays, namely the D3-PCR/ITS2-RsaI assay, followed by either the AD-PCR or the BCE-PCR assay, it is possible to identify individual specimens of any of the species of this complex. This assay system is the first, and the best available at present to distinguish all sibling species and especially to discriminate non-vector, species B from all the vector species, A, C, D, and E, of the An. culicifacies complex. Until another DNA-based method involving fewer steps is developed, this assay system can be used in all malaria epidemiologic studies where An. culicifacies is prevalent.

Alleles↗
PubMed2005

Comparative susceptibility of three important malaria vectors Anopheles stephensi, Anopheles fluviatilis, and Anopheles sundaicus to Plasmodium vivax.

The 3 laboratory-colonized malaria vectors, i.e., Anopheles stephensi, An. sundaicus, and An. fluviatilis, were studied for their comparative susceptibility to Plasmodium vivax sporogony. There was no significant difference in oocyst and sporozoite recruitment by these 3 species, whereas the geometric mean (GM) of the oocyst number per midgut was significantly lower in An. fluviatilis as compared with that in the other 2 species. There was no difference in the GM of oocyst between An. stephensi and An. sundaicus. Adaptability to laboratory conditions and susceptibility to plasmodial infection suggest that An. fluviatilis and An. sundaicus can also be used as a vector model for vector-parasite interaction studies.

Animals↗
PubMed2005

Evaluation of bifenthrin treated mosquito nets against anopheline and culicine mosquitoes.

BACKGROUND AND OBJECTIVES: The main rural malaria vector Anopheles culicifacies has developed resistance to dichloro diphenyl trichloroethane (DDT), hexachloro cyclo hexane (HCH) and malathion in the state of Haryana in northern India. An alternative synthetic pyrethroid insecticide bifenthrin was therefore evaluated on mosquito nets against anopheline and culicine mosquitoes, in two villages Jagdishpur and Garh Mirakpur of Community Health Center (CHC) Badhkhalsa in district Sonipat, Haryana state. METHODS: Two formulations of bifenthrin, suspension concentrate (SC) and micro-emulsion (ME) were compared with micro-capsule suspension (CS) of lambdacyhalothrin. The impact of three doses of bifenthrin (10, 25 and 50 mg/m(2)) impregnated on mosquito nets was compared with lambdacyhalothrin (25 mg/m(2)) and untreated control. Quality assessment of treatment on treated nets was carried out by residue analysis and the persistence of the insecticide on nets was determined by contact bioassays. Efficacy of treated nets on mosquito density was assessed by calculating mosquito entry rate, immediate mortality, delayed mortality and excito-repellency to the insecticides. RESULTS: In susceptibility tests An. culicifacies was susceptible to bifenthrin (0.1% test papers) and to lambdacyhalothrin (0.05% test papers). Bioassays on treated nets against A. culicifacies recorded 100 per cent mortality up to tenth fortnight for all the doses of impregnation with bifenthrin (SC and ME) and lambdacyhalothrin (CS). Ring-net bioassays against An. culicifacies showed median knock-down time between 3.1 to 11.4 min. Behavioural indices were also studied for anopheline and culicine mosquitoes. The reduction in entry rates of anopheline and culicine mosquitoes into the rooms with treated nets compared to control indicated good efficacy with all the formulations and doses of the insecticides. INTERPRETAION AND CONCLUSION: Indoor (immediate) mortality of mosquitoes with bifenthrin ME formulation was relatively lower compared to SC fomulation of bifenthrin and based on delayed mortility and continued susceptibility in bioassays, bifenthrin ME at the rate of 10 mg/m(2) dose was found suitable for the impregnation of mosquito nets for phase III trial.

Animals↗
PubMed2004

An allele-specific polymerase chain reaction assay for the differentiation of members of the Anopheles culicifacies complex.

Anopheles culicifacies, the principal vector of malaria in India, is a complex of five cryptic species which are morphologically indistinguishable at any stage of life. In view of the practical difficulties associated with classical cytotaxonomic method for the identification of members of the complex, an allele-specific polymerase chain reaction (ASPCR) assay targeted to the D3 domain of 28S ribosomal DNA was developed. The assay discriminates An. culicifacies species A and D from species B, C and E. The assay was validated using chromosomally identified specimens of An. culicifacies from different geographical regions of India representing different sympatric associations. The assay correctly differentiates species A and D from species B, C and E. The possible use of this diagnostic assay in disease vector control programmes is discussed.

Alleles↗
PubMed2004

Differentiation of members of the Anopheles fluviatilis species complex by an allele-specific polymerase chain reaction based on 28S ribosomal DNA sequences.

Anopheles fluviatilis, one of the major vectors of malaria in India, is a complex of at least three cryptic species provisionally designated as species S, T, and U. Identification of the cryptic species of An. fluviatilis complex is of paramount importance in disease control program due to contrasting differences in their vectorial efficiency, preference for feeding on humans, and resting behavior. Species S, T, and U are morphologically indistinguishable at any stage of their life cycle and can be identified only by the examination of species-specific fixed inversions in the polytene chromosomes. We report an allele-specific polymerase chain reaction assay for the differentiation of members of An. fluviatilis complex, which is based on differences in nucleotide sequences in D3 domain of 28S ribosomal DNA. The assay was evaluated against chromosomally examined individuals from different localities with different sympatric associations and was found to differentiate unambiguously all the members of the complex.

Alleles↗
PubMed2003

Peripheral nerve complications in hemophilia.

AIM: Muscle bleed in hemophilics can result in compressive neuropathy and permanent disability if not treated properly in time. Twenty cases of peripheral nerve involvement in hemophilics are presented with an aim to highlight its features and the role of pulsed ultrasound in the management. METHODOLOGY: Between January, 1999 and 2000 June, 134 patients of bleeding disorders were examined. Twenty of them presented with features of nerve palsy. In addition to usual conservative treatment, pulse ultrasound electrotherapy of 10-15 sittings was used in all the cases. RESULTS: Femoral nerve was involved in majority (15), followed by sciatic (4) and peroneal nerve in one case. Femoral nerve involvement was associated with iliacus bleed in 13 patients and inguinal bleed in two cases. All the four cases of sciatic nerve palsy were associated with gluteal hematoma. Only case of peroneal nerve palsy was associated with hematoma at upper leg and calf. Twelve cases improved completely within six months whereas another four recovered around 10 months. Remaining four showed only partial recovery even when followed up to 12 months. CONCLUSIONS: Recognition of nerve complications in hemophilics is important to avoid long-term disability. Conservative therapy starting early was associated with favourable results. Pulsed ultrasound therapy at the site of haematoma helped in early regression of hematoma and neural recovery.

Adolescent↗
PubMed2001

Functional diversity of hnRNP proteins.

The hnRNP proteins bind to pre-mRNA concomitant with transcription and form ribonucleoprotein complex essential for post-transcriptional events. More than 20 different groups of hnRNP proteins are known in humans. The number seems to be similar in other organisms too. The hnRNP proteins possess different types of RNA binding domains which directly interact with RNA, most likely in a sequence specific manner. The functions of hnRNP proteins range from mRNA packaging and transport, to mRNA splicing and silencing. Further, indirectly, their role has also been implicated in oogenesis. Hence, hnRNP proteins play diversified roles both in nucleus and cytoplasm, and regulate the gene expression at various levels.

Amino Acid Motifs↗
PubMed2000

Susceptibility of species A, B, and C of Anopheles culicifacies complex to Plasmodium yoelii yoelii and Plasmodium vinckei petteri infections.

The comparative susceptibilities of colonized species A, B, and C of Anopheles culicifacies complex and Anopheles stephensi were determined for 2 rodent malaria parasites Plasmodium vinckei petteri and Plasmodium yoelii yoelii. All the 3 members of the complex were found to support complete sporogony with varying success. Controls, A. stephensi, become readily infected, with >70% developing oocysts. Of the test groups, species A had the highest percentage of mosquitoes with oocysts (>25%) and sporozoites (>15%). Anopheles culicifacies species B were least susceptible; less than 10% had oocysts and sporozoites in the salivary glands. The results demonstrate that A. culicifacies species A is most susceptible and species B is least susceptible to infections with both the parasites.

Animals↗
PubMed1999

The intranuclear movement of Balbiani ring premessenger ribonucleoprotein particles.

Specific premessenger ribonucleoprotein (pre-mRNP) particles, the Balbiani ring (BR) granules in the salivary glands of the dipteran Chironomus tentans, can be visualized in the electron microscope when they assemble on the genes, move through nucleoplasm, and bind to and translocate through the nuclear pores. As shown by BrUTP labeling and immunoelectron microscopy, newly synthesized BR RNP particles, released from the BR genes, appear early in all nucleoplasmic regions of the cell nucleus and they saturate the nucleoplasmic pool of BR particles after 2 h of labelling. It is concluded that within the nucleus the BR particles move randomly. Furthermore, estimates of minimum diffusion coefficients for the BR particles are compatible with the view that the particles diffuse freely in the interchromosomal space, although it is not excluded that the random movement could be slightly retarded. Once the particles get bound to the nuclear pore complexes, they seem committed to translocation through the nuclear pores.

Animals↗
PubMed1998

The frequency of sexual dysfunctions in patients attending a sex therapy clinic in north India.

Analyzed data on 1000 consecutive patients with sexual disorders attending the psychosexual clinic at the All India Institute of Medical Sciences. The majority of patients were educated males between 21 and 30 years of age, belonging to the middle class. There was a slight preponderance of married patients. Fifty-two percent of patients had premarital or extramarital sexual contact; less than 5% had had homosexual contact; 10% had no sexual contact. Most patients had more than one complaint. Premature ejaculation (77.6%) and nocturnal emission (71.3%) were the most frequent problems followed by a feeling of guilt about masturbation (33.4%) and small size of the penis (30%). Erectile dysfunction was a complaint of 23.6%. Excessive worry about nocturnal emission, abnormal sensations in the genitals, and venereophobia was reported in 19.5, 13.6, and 13% of patients, respectively. Only 36 female patients attended the clinic with their spouses.

Adult↗
PubMed1996

Head and chest circumferences as predictors of low birth weight in Indian babies.

This study attempts to select predictors for indirect estimation of low birth weight from three important anthropometric measurements (viz. body length, head and chest circumferences) taken at birth. The data of 422 Indian low birth weight babies have been used to select the best combination of predictors by examining the separate effect of each of the three concomitant variables on birth weight using the technique of multivariate regression analysis. The combination of head and chest circumferences was found to be the best combination of predictors for estimation of birth weight in view of the simplicity and non-invasiveness of measuring these two body circumferences. A nomogram has also been constructed to predict low birth weight from head and chest circumferences. This nomogram will serve as a simple and quick procedure for predicting low birth weight from head and chest circumferences whenever the direct weighing at birth is not feasible.

Anthropometry↗
PubMed1996

Dynamics of malaria transmission in forested and deforested regions of Mandla District, central India (Madhya Pradesh).

A longitudinal malaria study was undertaken in 1990-91 in 2 adjacent ecological zones in central India: villages in forest and villages away from the forest. The prevalence of Anopheles species varied widely between the 2 ecological settings. In the villages in forest, Anopheles culicifacies and An. fluviatilis were mainly exophilic, whereas in the villages away from forest, An. culicifacies was predominantly endophilic and An. fluviatilis was equally prevalent both indoors and outdoors. The seasonal patterns of malaria transmission were also different between the 2 zones. Plasmodium falciparum was the dominant parasite species in the villages in forest, whereas malaria infection was mainly due to Plasmodium vivax in the villages away from forest. The annual parasite incidence was high in the villages in forest. The failure to control malaria in forested areas is rooted in the terrain and a variety of poorly understood sociological factors.

Animals↗
PubMed1994

Electrophysiological studies (MNCV and H-RL) in twin babies.

Twenty-six fullterm and eight preterm babies born of twin pregnancies were studied. Offsprings were subjected to measurements of weight, crown heel length and head circumference along with motor nerve conduction velocity (MNCV) and H-reflex latency (H-RL) at right median nerve. The preterm twins had significantly lower MNCV and higher H-RL. The electrophysiological parameters did not vary in first and second born twins as well as in heavier and lighter twins. Three pairs of twins were available for follow-up study.

Birth Weight↗