Chemopreventive effect of orange oil on the development of hepatic preneoplastic lesions induced by N-nitrosodiethylamine in rats: an ultrastructural study.

Orange peel oil is used extensively as an approved flavour enhancer in fruit drinks, carbonated beverages and as a scenting agent in soaps and cosmetics. Limonene, which is a monocyclic monoterpene is present in orange peel oil from 90 to 95% (w/w). Monoterpenes have been shown to be very effective chemopreventive agents against several rodent tumors and are currently in clinical trials. However, not much information is available regarding the ultrastructural changes associated with the chemopreventive effects of the monoterpenes. The effect of orange oil on the suppression of preneoplastic hepatic lesions during N-nitrosodiethylamine (DEN) induced hepatocarcinogenesis was studied electron microscopically. Rats were administered 200 ppm DEN through drinking water for a period of 1 month. After an interval of 2 weeks, the animals were administered orange oil by gavage for a period of 5 1/2 months. The chemopreventive effect of orange oil was monitored on the basis of liver weight profile, histological pattern by light microscopy and ultrastructural alterations by electronmicroscopy. Orange oil administration following DEN treatment showed decreased liver weights, increased intercellular gap junctional complexes, cell density and polarity when compared with only the DEN treated rats. In the present study chemopreventive effect of orange oil on DEN-induced hepatic preneoplasia in rats which is associated with the restoration of the normal phenotype and upregulation of junctional complexes has been demonstrated.

Susceptibility status of Mansonia annulifera to Brugia malayi parasites in Cherthala, Alappuzha district, Kerala.

Laboratory studies conducted on Ma. annulifera collected from Cherthala region, Kerala, endemic for Brugian filariasis indicated that this species is highly susceptible to B. malayi parasites. The experimental infection index of this species was relatively higher (2.74). No significant loss of larvae during development was recorded. The extrinsic incubation period was estimated to be 8 days.

Current status of filariasis in Chavakad taluk, Trichur district, Kerala.

A sample survey using parasitological, clinical and entomological indicators was carried out in all the 18 administrative units of Chavakad taluk, Trichur district, Kerala, India to assess the current filariasis situation. Cluster sampling procedure was followed to screen individuals. Both Wuchereria bancrofti and Brugia malayi species were found to be prevalent in this taluk. Microfilaria (mf) carriers with W. bancrofti were detected in eight areas while B. malayi was recorded only from one area. The two species were found to co-exist in another area. The highest infection rate registered for W. bancrofti was 1.51 while it was 0.3 for B. malayi. Infection due to W. bancrofti constituted 87.88% of the total 33 microfilaria cases. Prevalence of B. malayi was very low. Cases with clinical manifestation of filariasis were recorded in all the four areas surveyed. The present trend in the prevalence of infection (mf) and disease showed a decline in both the species when compared to earlier surveys of 1960s. At least 11 areas are still endemic for filariasis in this taluk. Although prevalence of mf was recorded for the first time in one of the areas viz., Elavalli, the rate was only 0.16%. Entomological surveys revealed the presence of 14 mosquito species, of which Culex quinquefasciatus contributed 84.85% and Mansonia 0.77%. While C. quinquefasciatus was recorded in all the 18 areas, Mansonia spp were found only in 8 areas. Only C. quinquefasciatus was found to harbour different developmental stages of W. bancrofti, with overall infection and infectivity rates of 1.94 and 0.97 respectively. The possible reason for the decline in vector density and infection in man are postulated.

Efficacy of diethylcarbamazine-medicated salt for microfilaraemia of Brugia malayi.

BACKGROUND: Pilot studies in India and abroad have demonstrated the benefit of cooking salt fortified with diethylcarbamazine citrate (DEC) for the control of lymphatic filariasis. In India, DEC-medicated salt has been introduced on a commercial basis in the Cherthala region of Kerala, which is endemic for Brugia malayi (B. malayi). We studied the efficacy of DEC-medicated salt in the clearance of microfilaraemia of B. malayi. METHODS: Eighteen cases of microfilaraemia (11 men; 7 women) were selected; 14 in the experimental group (i.e. treated with 0.2% w/w DEC-medicated salt) and the rest as the control group who were given a placebo. The consumption of salt and the status of parasitaemia were monitored till all the microfilaria carriers became negative. RESULTS: There was a significant reduction in the density of microfilariae (intensity) among the treated individuals over a period of time. The duration required for the clearance of microfilariae ranged from 9 to 30 [mean (SD) 19.4 (1.7)] weeks. All microfilaraemics except one reported side-effects which were mild-to-moderate and persisted for a maximum period of one month. CONCLUSION: DEC-medicated salt effectively clears microfilariae within 30 weeks in parasitaemic individuals. No 'endemic normals' reported any side-effects, though these were common among the microfilaria carriers.

Mattancherry urban agglomeration, a diminishing focus of lymphatic filariasis in Kerala.

Parasitological survey conducted recently in Mattancherry, Kerala showed a low prevalence of microfilariae (mf), with a mf rate of 1.81%, compared to that of 1956 when the mf rate was 14.7%. No brugian infection was encountered in the present investigation, though both bancroftian and brugian infections were reported earlier. Culex quinquefasciatus, the vector of bancroftian filariasis was the most predominant (93.3%) mosquito species, and its infection and infectivity rates were 0.76% and 0.54% respectively. Mansonioides spp., the vectors of brugian filariasis constituted only 0.2% of the total mosquitoes and with no infection. The overall reduction in the prevalence of mf cases and vector infection rates over the years is attributed to the continued activities of the National Filaria Control Programme. The disappearance of brugian filariasis could mainly be due to the drastic reduction in the Mansonioides breeding habitats, as a result of rapid urbanization coupled with improved socio economic conditions.

Brackish water mosquito problem of Vypeen Island, Cochin, Kerala.

A preliminary study has shown that the marshy terrain and brackish water bodies associated with mangrove forests contributed profuse breeding of mosquitos in Vypeen island, causing a severe menace to the island population. A total of 14 species belonging to four genera viz, Aedes, Anopheles, Armigeres and Culex was recorded from different habitats. Culex sitiens was found to be the predominant mosquito in all the perennial breeding habitats. The extent of different habitats in the production of mosquitos, and its possible abatement, using environmental and/or biocontrol methods are discussed.

Response of gravid Phlebotmus papatasi females to an oviposition attractant/stimulant associated with conspecific eggs.

Oviposition response of gravid P. papatasi females to conspecific eggs was studied in laboratory colonized sandflies. It was observed that significantly higher number of eggs were laid in the vicinity of conspecific eggs. However, a certain minimum number of eggs were required to be placed on the substratum to influence the rate of oviposition. The fecundity of females (mean = 56.5 +/- 4.9 eggs) exposed to conspecific eggs was significantly higher (P < 0.05) than that of blank control group. Perhaps, the chemical substances/pheromone of egg origin stimulated the oviposition rate. In an attempt to isolate the active ingredient, solvent washing of the conspecific eggs were tested. No increase in the rate of oviposition was noticed when the test site was treated with distilled water extract, whereas, significantly larger number of eggs were laid at the site treated with di-ethyl ether extract. This indicated that the oviposition attractant associated with the eggs dissolved in the organic solvent, but not in water. The possible application of this attractant for wild sandflies in nature and for regulating the site of oviposition on the substratum in the laboratory colonized sandflies needs to be explored.

Aquatic vegetation and their natural hospitability to the immatures of Mansonia mosquitos, the vectors of Brugia malayi in Shertallai, Kerala, India.

Prevalence of various aquatic vegetation and their role in supporting vector breeding were studied by drawing plant samples from natural fresh water habitats in Shertallai region which is endemic for Brugia malayi. As many as 30 aquatic plant species were identified in addition to the most abundant and preferred host plants such as Pistia stratiotes, Salvinia molesta and Eichhornia crassipes which are of major concern due to their contribution for vector proliferation. Fallow lands and paddy fields recorded relatively a higher number of plant species. Natural breeding of Mansonia, the vector mosquitos was observed in 16 of them. Using the data on the prevalence, proportion of samples positive for Mansonia breeding and immature density, two indices viz, natural hospitability Index (NH) and Mansonia host plant Index (MHI) were developed for each plant species. Ranking of these plants in relation to Mansonia breeding was done based on these indices. Monochoria vaginalis has been identified to be one of the most important auxiliary host plant. Three grasses viz, Hygrorhiza aristata, Sacciolepis interrupta and Leersia hexandra were found to support all the three species of Mansonia viz, Ma. annulifera, Ma. uniformis and Ma. indiana with considerable immature density. The inclusion of these plants for weed/vector control is emphasized.

Observation on the host parasitoid interaction between Periplaneta americana, the American cockroach and Tetrastichus hagenowii, an oothecal parasitoid

Investigations were carried out on the host parasitoid interaction between Periplaneta americana, the American cockroach and Tetrastichus hagenowii, an oothecal parasitoid. This gregarious female parasitoid infected and or oviposited in only one host and caused 100 por cento mortality of the infected host. However, increase in parasitoid density decreased the progeny production and influenced the sex ratio. The progenies produced were male biased. When host preference was tested by offering oothecae of different species of cockroaches, T. hagenowii showed a predilection towards the oothecae of P. americana, suggestings its host specificity.

Ultrastructural changes in mild gastroesophageal reflux disease: results of a pilot study.

Few studies have examined the ultrastructural changes in mild reflux esophagitis. Endoscopic esophageal biopsies were obtained from 10 patients with reflux symptoms and mild endoscopic esophagitis (grade 0:3 patients, grade I: 7 patients) and 9 patients with erosive esophagitis (grade II-IV), at least 5 cm above the Z line. The biopsies were evaluated by light and transmission electron microscopy. Ultrastructural changes were present in one patient with grade 0, 7 with grade I and 9 with grade II-IV esophagitis. Four of the 10 patients with grade 0-I esophagitis and 6 of 9 with grade II-IV esophagitis had light microscopic abnormalities. The ultrastructural abnormalities in patients with mild esophagitis were seen in the cell membrane, cytoplasmic organelles, desmosomes, and nuclei of all the three layers of esophageal mucosa and the basal lamina. Ultrastructural studies by transmission electron microscopy on endoscopic pinch biopsies may be a sensitive research tool to study the pathogenesis of mild reflux esophagitis.

Laboratory observations on the biology of the phlebotomid sandfly, Phlebotomus papatasi (Scopoli, 1786).

Investigations on the biology of Phlebotomus papatasi were carried out under laboratory conditions at 28 +/- 2 degrees C and 80 +/- 1% RH. Fecundity of the female varied between 61 and 48 (mean 56.2 +/- 5.46) and the incubation period of eggs ranged from 7-9 (mean 7.81 +/- 0.61) days. The developmental duration of larvae and pupae varied from 24 to 31 (mean 28.57 +/- 2.71) and 9 to 11 (mean 10.38 +/- 1.51) days, respectively. The rate of insemination, determined from the females that laid fertile eggs, was found to be maximum when the females were three days old. Autogeny was observed from female sandflies, emerged from the larvae fed on animal liver powder. The duration of first and second gonotrophic cycles under ambient conditions was shortest in summer and longest in winter. Studies on adult longevity showed that the females fed on mouse blood survived for 6 to 27 days (mean 14 +/- 12.5 days).

Biting rhythm & biting activity of phlebotomid sandflies.

The biting behaviour of Phlebotomid sandflies was studied in a rural village of Pondicherry through all night collections for a period of one year, using human volunteers and cattle as baits. Phlebotomus papatasi was caught only on human bait, showing anthropophily while Ph. argentipes was caught on cattle baits, showing zoophily. The biting activity was seen throughout the night, reaching a peak of 0100 h in Ph. papatasi and 0200 h in Ph. argentipes.

An improvised method of laboratory colonization of Phlebotomus papatasi, the vector of cutaneous leishmaniasis.

A cyclic colony of P. papatasi was successfully established, using wild caught females. The major obstacle in the colonization was infestation of fungus, which was solved when bentonite, a dehydrant was mixed in the larval diet i.e., powdered and sterilized faecal pellets of rabbit. The average duration of development from egg to adult was 46.41 +/- 3.26 days. Females readily engorged on mouse, which was kept immobilized inside restrainer cages Majority of the fed females laid viable eggs, when confined in improvised styro-foam humidity chambers and survived after oviposition. In this process a stable, cyclic colony was established and it is now in F39 generation.

Identification of bloodmeals of phlebotomine sandflies using the agarose gel diffusion method.

The source of blood meal of wild caught Phlebotomid sandflies collected in areas around Pondicherry was identified using an agarose gel diffusion method. A total of 497 blood samples obtained from freshly engorged Phlebotomid sandflies were tested. Of these 66.8% were positive to human antisera, 29.2% to bovine antisera and the remaining 4.0% to avain antisera. The human blood indices of P. papatasi and P. argentipes were 0.91 and 0.04, respectively.

Larvivorous potential of some indigenous fishes of Sherthallai region with special reference to their efficacy in control of mansonioides.

Larvivorous potential of some indigenous fishes collected from natural habitats of Sherthallai region in Kerala state, India, was studied under laboratory as well as controlled field conditions. Ophiocephalus striatus was observed to consume significantly higher number of mansonioides larvae (354/g body wt/day), followed by Macropodus cupanus (231/g body wt/day). The proportion of adult vector mosquito emergence was significantly (P less than 0.05) lower in cages with fish species studied, as compared to that of control group of cages without fishes. Natural food preference of the selected fish species was also studied indirectly through gut content analysis.

Seasonal abundance, natural survival & resting behaviour of Phlebotomus papatasi (Diptera: Phlebotomidae) in Pondicherry.

A study was carried out on the seasonal abundance, natural survival and resting behaviour of Ph. papatasi in four ecologically different areas of Pondicherry. The average indoor resting density ranged from 2.25 (May 1989) to 16.70/man hour (October 1989). Ph. papatasi was observed to be predominantly endophilic in its resting behaviour. A significant positive correlation was observed between rainfall and relative density. The daily survival of adult population ranged from 0.893 to 0.949 and showed significant positive correlation with relative humidity. Examination of the abdomen of indoor resting females showed that the entire period of gonotrophic cycle was spent indoors.

The resting and house frequenting behavior of Mansonia annulifera, Ma. uniformis and Ma. indiana, the vectors of Malayan filariasis in Kerala State, India.

Mansonia annulifera, was recorded to be an endophilic species, preferring to rest indoors, while Ma. uniformis was exophilic, having a predilection for outdoor resting habitats, eg bushes and shrubs. Ma. indiana did not show a clear preference to either of these biotopes. In indoor resting collections, the unfed proportion of Ma. uniformis was significantly higher during post-dusk compared to day hours (p < 0.05), indicating that this exophilic species enters houses during dusk hours for feeding. The full fed proportion was higher during day hours compared to dusk/night hours. The semigravid proportion showed a significant reduction during post-dusk hours (p < 0.05). These findings suggest that after having a blood-meal this species rest indoors and leave the houses for outdoor resting sites during the dusk hours on the subsequent night.

Daily diethylcarbamazine for the treatment of Brugia malayi microfilaria carriers.

BACKGROUND. Diethylcarbamazine is effective for the treatment of brugian filaria carriers. However, the 12-day course with a daily dose of 6 mg per kg body weight is rarely completed. The World Health Organization has indicated the need for better regimes to control filariasis. METHODS. We evaluated the long term effects of three different dosage regimes of diethylcarbamazine--6, 9 and 12 mg per kg body weight--to a total of 72 mg on 93 microfilaria carriers of Brugia malayi. RESULTS. All cases treated with the 6 mg daily dose showed complete clearance of microfilaria immediately after the treatment. However, at the 9 and 12 mg daily doses only 91% and 85% of cases respectively showed complete clearance. There was a close association between the daily dose and the proportion of cases developing side-effects. The mean initial microfilaria counts were significantly higher in those who had side-effects than in those who did not. An 11-month follow up showed that with the 6 mg daily dose the recurrence rate of microfilaraemia was 29% while with the 12 mg daily dose it was 67%. Four per cent of patients on a daily dose of 6 and 9 mg discontinued treatment while 21% of those on the 12 mg daily dose did so. CONCLUSION. The 6 mg daily dose of diethylcarbamazine was the most effective and best accepted regime.

A cost benefit analysis of fish culture strategy towards the control of mansonioides in Shertallai, Kerala state.

The cost benefit analysis of fish culture as a means for vector control towards the containment of Brugian filariasis in Shertallai, a highly endemic tract for this disease in Kerala was carried out. While the financial gain accrued to the community was to the tune of Rs. 1,82,052 in ponds (under monoculture) with Chinese grass carp from 763 ponds, it was Rs. 1,83,740 from 1000 ponds under polyculture with Catla catla, Cyprinus carpio, Labeo rohita, Labeo fimbriatus, Cirrhina mrigala and Ctenopharyngodon idella (Chinese grass carp). Monoculture with Giant gourami (Osphronemous goramy) fetched an income of Rs. 7,654 to the community from 128 ponds. A marked reduction in weed reinfestation/vector breeding was observed in ponds under fish culture than other without fishes. The study clearly indicates that fish culture is an ideal strategy for Mansonioides control as it can bring perceptible benefits to the community.