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Biomedical subjects

R Rajendran

Publications and source records attributed to R Rajendran.

At least 55 records · Page 3Linked to original sources
PubMed1997

Japanese encephalitis in south Arcot district, Tamil Nadu, India: a three-year longitudinal study of vector abundance and infection frequency.

In the South Arcot district, an area endemic for Japanese encephalitis in Tamil Nadu, Culex tritaeniorhynchus Giles, Culex vishnui Theobald, Culex gelidus Theobald and Culex fuscocephala Theobald constituted 93.6% of 422,621 adult females representing 27 culicine species collected between August 1991 and July 1994. Vector abundance was lowest in the hot and dry season (April-June) and highest in the cool and wet season (October-December). Overall, 285,531 adult female mosquitoes (5,710 pools) were tested for virus using an enzyme-linked immunosorbent assay or by inoculation into larvae of Toxorhynchites splendens Wiedemann and identification by immunofluorescent test using JE virus specific monoclonal antibody or by both. In total, 91 isolations were made, of which 80 (88%) were identified as JE virus; 58 isolations were from Cx. tritaeniorhynchus, 22 from Cx. vishnui, 6 from Cx. fuscocephala and 5 from Cx. gelidus, giving similar minimum infection rates (MIR) of 0.28, 0.41, 0.39, and 0.52, respectively. Vector abundance and MIR increased from July concurrently with the initiation of rice cultivation. MIR peaked in September followed by a decrease in October, but mosquitoes remained abundant until March. The decrease in MIR from October onward coincided with rising herd immunity in pigs. Although MIRs in October (0.47) and November (0.42) were lower than in September (0.92), a comparable high risk of infection for humans continued because of high vector abundance and human biting rates. In the South Arcot district, the probability of a child receiving an infective bite was 0.53 per JE transmission season.

Animals↗
PubMed1996

Radiographic mimics of pneumonia. Pulmonary disorders to consider in differential diagnosis.

Pinpointing the source of roentgenographic lung abnormalities can be challenging because many noninfectious pulmonary disorders mimic pneumonia. The authors of this article discuss the most common radiographic presentations of lung disorders that may be mistaken for pneumonia, including focal and diffuse infiltrates, nodules, cavities, and pleural effusion. They also outline the role of thorough history taking and examination in prompt and accurate diagnosis of pulmonary disorders.

Diagnosis, Differential↗
PubMed1996

An appraisal of some recent diagnostic assays for Japanese encephalitis.

A study was undertaken in South Arcot district of Tamil Nadu, India to assess relative merits of selected diagnostic techniques for Japanese encephalitis. During the transmission seasons of 1993-1995, a total of 85 patients (mostly pediatric) clinically diagnosed as acute encephalitis or other related central nervous system (CNS) disorders were examined; in 53 (62.4%) a laboratory diagnosis of JE was established. In terms of diagnostic value, immunoglobulin M (IgM) antibody capture ELISA (MAC ELISA) on convalescent serum had the highest sensitivity (89%) and negative predictive value (NPV) (50%). This was followed by MAC ELISA on acute serum and CSF which had similar sensitivity (84%) and NPV (40%). The hemagglutination inhibition test and Toxorhynchites splendens inoculation technique for virus isolation were also similar in sensitivity (68%) and NPV (25%). The virus antigen detection technique by IFA in cells of cerebrospinal fluid (CSF) was the least sensitive (58%). The distinct advantage of the acute serum ELISA is that it can be carried out on a single finger-prick blood specimen. The IFA on CSF cells is the most rapid diagnostic test since it requires only 2-3 hours to complete. Therefore, both these tests also offer potential tools for JE surveillance programs.

Adult↗
PubMed1995

Prospects and problems of intermittent irrigation for control of vector breeding in rice fields in southern India.

The impact of water management on the abundance and interaction of aquatic stages of mosquitoes and some important groups of their predators was studied in a 22.3-ha plot of rice in southern India. Many pools persisted even in a year when intermittent irrigation (II) was properly implemented (fields being re-irrigated as soon as they were dry) and these acted as microrefuges for the immature stages of mosquitoes and for their predators. Although the abundance of all predators, particularly of Notonectidae, was reduced by II in this year, increased predation efficiency in the confined spaces of the persistent pools resulted in a 75%-88% reduction in the abundance of mosquito pupae, as measured by two independent sampling methods. In another year there was insufficient irrigation water for proper II and re-irrigation took place whenever water was available rather than when it was required, frequently resulting in only partial drying. This reduced predator populations without enhancing their efficiency, and so mosquito abundance was slightly higher than in conventionally irrigated fields. The implications for vector control are discussed.

Agriculture↗
PubMed1995

Development of a high level of resistance to Bacillus sphaericus in a field population of Culex quinquefasciatus from Kochi, India.

Field resistance to Bacillus sphaericus was observed in a population of Culex quinquefasciatus in Kochi, India, exposed to 35 rounds of spraying with a formulation of B. sphaericus 1593 M over a 2-year period. Larvae from the sprayed area gave LC50 and LC90 values that were 146 and 180 times greater than corresponding values for a susceptible strain from an unsprayed locality. When the resistant strain was colonized in the laboratory and subjected to moderate selection pressure at each generation, resistance rapidly increased and by the 18th generation it was 6,223 and 31,325 times greater at the LC50 and LC90 levels in comparison with the susceptible strain. There were no significant differences among 6 susceptible strains tested. Tests were repeated and validated using the standard primary powder SPH88, B. sphaericus 2362. No cross resistance was observed against B. thuringiensis H-14.

Animals↗
PubMed1995

Comparative evaluation of bioassay and ELISA for detection of Japanese encephalitis virus in field collected mosquitos.

Comparative evaluation of enzyme-linked immunosorbent assay (ELISA) and bioassay (virus isolation in Toxorhynchites splendens larvae and identification by immunofluorescence test using virus specific monoclonal antibody) was carried out in order to define a suitable strategy for monitoring Japanese encephalitis virus infection in field mosquitos. A total of 8,850 adult female mosquitos in 177 pools (Culex tritaeniorhynchus 91, Cx. vishnui 59 and Cx. fuscocephala 27) collected from an endemic area of Tamil Nadu were examined by both the techniques. In ELISA, 9 pools which had optical densities (OD) equal to the mean of normal infected pools plus > or = 4 standard deviations (SD) mean considered positive and all of them were virus positive by the bioassay also. Sixty-five pools had OD = Mean + 2-3 SD and 103 pools had OD = Mean + < 2 SD of normal pools. From these groups, 12 (18.5%) and 8 (7.8%) pools respectively were found to be virus positive by the bioassay. In total 29 (16%) pools were positive by the bioassay as against 9 (5%) by ELISA. This study demonstrated that the bioassay is sensitive for estimation of true positives and ELISA is a rapid screening system. A protocol has now been developed for surveillance in which field pools are first screened by ELISA and only those with OD = Mean + > or 2 SD are assayed in Toxorhynchites. By excluding a large majority of pools with low OD (Mean + < 2 SD), which are likely to yield to only a small percentage of true positives, the cost, time and labor involved are greatly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Profile of intersex children in south India.

Thirty five children with ambiguous genitalia admitted to our centre between January 1986 to December 1991, were followed up and their clinical, laboratory and management strategies were analyzed. Most of them presented between 1 month and 2 years of age and only 2 presented in the newborn period. Sixteen were female pseudohermaphrodites. Eighteen out of 31 children were assigned female sex. One genetic female with congenital adrenal hyperplasia was assigned male sex. We practised more than one type of clitoroplasty in our centre. Parents prefer the intersex children to be reared as male possibly because of the less social stigma attached to an impotent male than to sterile female, and because males are socially independent.

Adolescent↗
PubMed1995

Megalourethra.

Explore the source record for details and available documents.

Abnormalities, Multiple↗
PubMed1994

A laboratory study on the life cycle and feeding behaviour of Arrenurus madaraszi (Acari: Arrenuridae) parasitizing Anopheles mosquitoes.

Although mosquitoes of several genera were collected from one locality in Thiruvananthapuram, Kerala State, India, only Anopheles spp. carried larval Arrenurus madaraszi; 21.5% of the An. hyrcanus and 19.0% of the An. vagus were infested. However, the whole life cycle of Arr. madaraszi could be replicated in the laboratory using Aedes albopictus, Ae. vittatus or Armigeres subalbatus as foster hosts. The host specificity observed in the field is therefore ecological, not physiological. In the laboratory, the nymphs and adult mites were free-living and when offered ostracods, copepods and larvae of Ae. albopictus, Ae. vittatus, An. hyrcanus, An. vagus and Arm. subalbatus as food, they showed a preference for first instar mosquito larvae, particularly those of Ae. albopictus.

Aedes↗
PubMed1994

Oral submucous fibrosis: etiology, pathogenesis, and future research.

Oral submucous fibrosis (OSMF), a precancerous condition of the oral cavity, has been studied by a number of workers in the field. The available epidemiological data showed a clear-cut geographical and ethnic predisposition, which suggested that certain customs/habits prevalent among the population groups in south-east Asia might be possible etiological factors. However, none of these customs was shown to be causally linked and the association in many cases was 'casual'. This led some workers to consider the importance of systemic predisposition, in addition to the effects of local factors on the oral mucosa. More research is needed to elucidate this problem.

Female↗
PubMed1992

Silver-binding nucleolar organizer region proteins as a possible prognostic indicator in oral submucous fibrosis.

Silver-binding nucleolar organizer region proteins (AgNORs) were counted in sections from formalin-fixed, paraffin-embedded tissue blocks of oral submucous fibrosis (OSMF) and oral squamous cell carcinoma (SCC). Moderately advanced and advanced cases OSMF, and well-differentiated and poorly differentiated cases of SCC, were studied with respect to the relation between AgNOR counts and histologic grading. Normal oral mucosa collected from age- and sex-matched subjects constituted the control group. The pooled mean (+/- SD) AgNOR counts were as follows: normal mucosa, 2.50 +/- 0.52 (n = 5); moderately advanced OSMF, 5.24 +/- 1.23 (n = 10); advanced OSMF, 7.26 +/- 1.12 (n = 10); well-differentiated SCC, 8.29 +/- 1.47 (n = 5); and poorly differentiated SCC, 9.49 +/- 0.74 (n = 5). The pooled mean AgNOR counts in advanced OSMF were higher than in moderately advanced cases (t = 3.84; p < 0.005) and those in poorly differentiated SCC were higher than those of well-differentiated SCC, although the comparison was not significant in the latter (t = 1.63, p > 0.10). AgNOR counts could hold promise for predicting the biologic behavior of OSMF because this study demonstrated a correlation with clinical and histologic grading.

Adult↗
PubMed1992

Prevalence of oral submucous fibrosis in the high natural radiation belt of Kerala, south India.

Oral submucous fibrosis (OSMF) is a crippling disorder which is confined almost exclusively to the Indian subcontinent. Despite its association with a significantly increased risk of cancer, the etiology is still not clear. An epidemiological assessment showed 0.4% prevalence for OSMF in Kerala, South India, which is among the highest recorded. Recently the National Tumour Registry in Trivandrum reported the highest recorded site-specific incidence rate for oral cancer (ICD 140-145) in this area. The coastal belt of the Trivandrum and Quilon districts of Kerala has a very high natural radioactivity (over 1500 mR (387 microC) per year); about 500 mR (129 microC) per year is considered to be the maximum permissible dose for populations in general. An epidemiological survey in this area and in a comparable population (without exposure to high background radiation) as a control showed that the percentage prevalence of OSMF in the study area was 0.27 and in the control area 0.32. It appears highly improbable that the OSMF in the study area was induced by high background radiation.

Adolescent↗
PubMed1991

Evaluation of the water fern Azolla microphylla for mosquito population management in the rice-land agro-ecosystem of south India.

The floating water fern Azolla microphylla Kaulfess was evaluated as a biocontrol agent against mosquitoes breeding in rice fields in Tamil Nadu, South India. Anopheles subpictus Grassi, Culex pseudovishnui Colless and Culex tritaeniorhynchus Giles were the predominant species of mosquitoes, with peak densities of late instar larvae and pupae occurring during the second week after transplantation of rice seedlings of short-term (c. 80 days from transplantation to harvest) or medium-term (c. 95 days) varieties. Immature mosquito populations were reduced by mats of Azolla microphylla covering more than 80% of the water surface. However, since 80% coverage by Azolla was achieved only 13-14 days after rice transplantation, its usefulness for mosquito control was limited. Azolla may have a greater potential in an integrated control programme, or in areas where long-term varieties of rice are predominantly grown.

Agriculture↗
PubMed1990

Serum levels of iron and proteins in oral submucous fibrosis (OSMF).

Serum proteins, serum iron and total iron binding capacity were estimated in 50 patients with oral submucous fibrosis and 50 patients with oral leukoplakia. The values were compared with that of 50 age- and sex-matched controls. A significant depression in hemoglobin and serum iron was observed in both groups of patients, whereas total iron binding capacity showed significant change only in the oral submucous fibrosis patients. Serum protein values were significantly lower in all the patients. The role of iron deficiency anemia in the causation of this premalignant lesion is discussed.

Adult↗
PubMed1990

Space-spraying with malathion as a supplementary measure for operational malaria control.

Entomological studies showed that due to outdoor resting by the vector Anopheles culicifacies as well as poor spray coverage, indoor residual spraying with malathion was ineffective in malarious villages of the Thenpennai riverine tract in Tamil Nadu. Over a 4 yr period during which residual spraying was supplemented with ground applications of malathion space spraying, the slide positivity among patients with fever fell from 21.04 to 1.1 per cent. In mass blood surveys 0.7 per cent persons surveyed at the beginning of the study were positive for the malarial parasite, but no positives were detected in the last survey, in 1984. There was a rising trend in malaria incidence in riverine villages outside the programme.

Animals↗
PubMed1990

Total hemolytic complement (CH50) and its fractions (C3 and C4) in the sera of patients with premalignant and malignant lesions of the oral cavity.

Total hemolytic complement (CH50) and its fractions (C3 and C4) were estimated in the sera of 50 patients with oral leukoplakia, 50 patients with oral submucous fibrosis and 50 oral cancer patients. The values were compared with that of 50 normal controls. No significant alterations in the values of CH50, C3 or C4 were observed in the sera of patients with either leukoplakia or oral submucous fibrosis whereas the values were found to be altered significantly in oral cancer (P less than 0.001). In the case of oral submucous fibrosis the mean complement levels were slightly lower than those of normal controls and leukoplakia. Age and sex had no influence either on the total complement activity or its fractions (C3 and C4). The serum complement levels may be useful as a biological marker for the early detection of tissue dysplasia.

Adult↗
PubMed1989

An alternative pathogenetic pathway for oral submucous fibrosis (OSMF).

Oral submucous fibrosis is a potent pre-cancerous condition which occurs almost exclusively in Indians but cases have been reported from several countries. The definite aetiology of OSMF is still unknown and there is no known treatment for it. Chilles, tobacco use, vitamin deficiencies and betel quid chewing have been implicated. Ramanathan is of the view that OSMF seems to be the Asian version of sideropenic dysphagia. He suggests that OSMF appears to be an altered oral mucosa following prolonged period of chronic deficiency of iron and/or vitamin "B" complex especially folic acid. This changed state of the oral mucosa subsequently appears to develop more easily a hypersensitivity to oral irritants such as spices especially chillies and to the betel quid. We hold that the hypersensitivity caused by local irritants and the resultant persistent juxta epithelial inflammatory response noted in OSMF (in a host system already primed by an intrinsic genetic defect) act as the initiating factor leading to a defective inflammatory--reparative response, culminating in fibrotic healing. The role of iron and "B"complex together with others may be contributory (promotor) to this pre-existing pathologic response of the lamina propria.

Anemia↗