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Prolactin response to suckling was studied in a group of fully breast feeding women (N = 58) between 4-6 weeks postpartum. Basal, suckling stimulated and the increment of prolactin showed wide individual variations. Basal prolactin concentrations varied from 140 to 4,600 mIU/l, suckling stimulated prolactin from 400 to 5,600 mIU/l and the increment of prolactin from 40 to 4,160 mIU/l. Basal (p = 0.0395) and suckling stimulated (p = 0.0423) prolactin concentrations significantly increased as the number of night breast feeds increased and the suckling stimulated (p = 0.0218) prolactin concentrations significantly increased as the number of breast feeds/24 h increased. However, the magnitude of the rise in prolactin in response to suckling was not dependent on basal prolactin concentration. Basal, suckling stimulated or the increment of prolactin were not significantly different between subjects having different breast feeding frequencies, when the subjects were grouped according to the number of breast feeds. These differences may be due to the large individual variation in prolactin concentrations seen in women having similar breast feeding frequencies which may arise from individual variations in hypothalamic--pituitary response to suckling.

A random sample of 503 individuals from five endogamous groups of Sri Lanka was studied for the genetic polymorphism of the group specific component (GC) and transferrin (TF) using isoelectric focusing. Both systems showed statistically significant heterogeneity among the five main populations of the island. The GC allele frequencies of Malays are significantly different from those of the other four populations (Sinhalese, Tamils, Moors and Burghers). However, the TF system shows less variation, since only the Moors show a significant heterogeneity compared to Tamils and Burghers. The frequencies found in the present study are very different from those reported for the populations of the Indian mainland.

Intervention measures against anemia available to plantation workers during pregnancy include fortified food supplements (thriposha) and iron-folate supplements containing 60 mg elemental Fe. The effectiveness of these intervention measures was studied in 195 subjects whose iron and nutritional status were assessed at < 24 and > 32 wk of gestation. Taking thriposha conferred no significant benefit on maternal nutritional status, probably because sufficient amounts were not consumed. An increase in the duration of iron-folate supplementation to > 17 wk caused a significant positive change (P < 0.01) in hemoglobin, whereas an increase in the dose frequency had no significant benefit. Anthelminthic therapy in addition to iron-folate supplements caused a significant positive change in hemoglobin (P < 0.001) and serum ferritin (P < 0.005) compared with no supplementation. Thus, anthelminthic therapy significantly increased the beneficial effects of iron supplementation on hemoglobin concentration and iron status.

The relationship of soil-transmitted nematode infections to the availability of latrines was studied among 1,614 children 3-12 years of age living on plantations in Sri Lanka. The majority (89.7%) of the children had at least one type of soil-transmitted nematode. There was a significantly lower mean count of hookworm eggs for children coming from plantations with good sanitary facilities. For Ascaris and Trichuris, a similar association was observed between the mean egg count and the availability of latrines for children from the low-country plantations, where people live in more scattered settlements, but not in the up-country area, where worker settlements are larger and more crowded. Congested living conditions in themselves consequently seem to be a major determinant for ascariasis and trichuriasis, and the provision of latrines and safe water does not substantially change that situation. However, improvements of sanitary facilities will probably have a more immediate effect on the prevalence of hookworm infection.

A highly repetitive DNA element from the genome of the filarial nematode Dirofilaria repens has been cloned and sequenced. The 176-base pair repeating units are arranged in direct tandem and are clustered in the parasite genome. All repeats appear to belong to a single family although some elements have diverged significantly. The repeats are present in about 15,000 copies and constitute approximately 3.0% of the parasite genome. The cloned repetitive sequence hybridized only to D. repens DNA and was sensitive enough to detect 250 to 500 pg of D. repens DNA, a single microfilariae in infected blood samples, and a single third stage larvae in mosquitoes. The high specificity and sensitivity of the cloned fragment makes it ideal as a diagnostic probe for detecting D. repens in both the host and the vector.

Objectives: To study the effect of working in health services on complications of pregnancy, preterm deliveries and low birthweight (LBW)., Methods: These indices were studied in 130 pregnancies that occurred within the preceding 5 years in 100 nursing officers (NOs) and 126 pregnancies in 100 clerical workers (CWs). Risk was assessed by calculating odds ratios. Confounding and interaction effects were studied by stratification., Results: Socio-economic background and antenatal care utilization in the two groups were similar. Occurrence of LBW was not significantly different (OR = 1.04; 0.57 < OR < 1.89; P = 0.89) although complications of pregnancy (OR = 2.18; 1.09 < OR < 4.38; P = 0.017) and preterm deliveries (OR = 5.64; 1.15 < OR < 37.73; P = 0.013) were higher in NOs. Further analysis showed that employment in health services has a positive effect in prevention of LBW among NOs in the presence of other risk factors., Conclusions: Working in the health services had a negative effect on some of the indices while benefits of such employment had a positive effect on birth-weight.

This study examined the antifertility effects of tamsulosin, a highly potent and a selective, alpha 1-adrenoceptor antagonist, on male rats. The drug was administered subcutaneously as a single dose (0.15 mg kg-1). The drug caused a significant reduction in fertility (measured by number of uterine implants, quantal pregnancy, and fertility index). The antifertility effect was short lived and rapid in both onset (no later than 7 h of administration) and recovery (within 7 d). Libido and mating performance remained essentially uninhibited. On the other hand, the antifertility effect was accompanied by significant impairment in ejaculatory competence and enhancement of pre-implantation losses. Based on the results of this study and our previous studies it is concluded that alpha 1-adrenoceptor blockade has a potent antifertility effect in male rats.

The percentage of peripheral blood mononuclear cells (PBMC) bearing the CD3+ phenotype and the alpha/beta and gamma/delta T cell receptors (TCR) in PBMC were examined in Plasmodium vivax malaria patients and convalescents. The cells were labeled with monoclonal antibodies, stained with either fluorescence or phycoerythrin, and examined by ultraviolet (UV) microscopy. A highly significant increase in both the proportion and the absolute numbers of gamma/delta T cells (p < 0.005 and < 0.001, respectively, Student's t test) was observed in nonimmune P. vivax patients during clinical paroxysms compared to nonmalarial controls. These T cells, which normally constitute not more than 3-5% of PBMC, constituted < or = to 30% of PBMC during paroxysms in these nonimmune patients in whom the clinical symptoms were severe. A less significant increase of gamma/delta T cells were also observed in these nonimmune patients during infection, between paroxysms and during convalescence. In contrast, in an age-matched group of semi-immune patients resident in a malaria-endemic region of the country, in whom the clinical disease was comparatively mild, there was no increase in gamma/delta T cells either during infection, even during paroxysms, or convalescence. The severity of disease symptoms in patients as measured by a clinical score correlated positively with the proportion of gamma/delta T cells in peripheral blood (r = 0.53, p < 0.01), the most significant correlation being found between the prevalence and severity of gastrointestinal symptoms, nausea, anorexia, and vomiting, and the proportion of gamma/delta T cells (r = 0.49, p = 0.002). These findings suggest that gamma/delta T cells have a role to play in the pathogenesis of malaria, possibly in the general constitutional disturbances and particularly in gastrointestinal pathology in malaria.

The active principle of chilli is capsaicin which when inhaled induces cough and transient increase in airway resistance through selective stimulation of sensory nerves in the airway. The present study was aimed at determining whether workers exposed to chilli dust showed ventilatory changes as in the pharmacological model. Twenty-five men with an average age of 28.5 years employed in five chilli grinding factories in Sri Lanka for an average of 6.6 years (range 3 months to 20 years) were clinically examined. Their ventilatory measurements were recorded before and after a Monday workshift. A control group was similarly examined. Dust levels in the respective chilli grinding factories were monitored. Fifteen men (60 per cent) had initial symptoms including cough on recruitment, but these passed off in 3 weeks to 6 months. There was no statistically significant across-shift change in ventilatory indices in chilli grinders when compared to the controls, nor was there a significant difference in the pre-shift measurements in the two groups. It is concluded that the airway resistance that occurs in the pharmacological model is too fleeting, if present in chilli grinders, to be recorded under ordinary conditions.

The effect of moderate son preference on family size is analysed using data from the 1982 Sri Lanka Contraceptive Prevalence Survey whose respondents were followed-up in the 1985 Sri Lanka Contraceptive Survey. Reported reproductive intentions on desire for additional children were not always reflected in overall contraceptive use. Complicating factors were the use of modern and traditional methods and the role of induced abortion. Longitudinal observations of the 1982-85 period relating women's individual reproductive behaviour to their intentions show no consistent behavioural difference between those with and without sons. However, at any given parity, the proportion reporting at least one additional child born during the intersurvey period was higher among those women who intended to have at least one additional child than among those who wanted to stop childbearing. This analysis suggests that son preference finds expression more through reproductive intentions than through actual fertility behaviour in the follow-up period.

The serum and coproantibody response (IgG and IgA) to naturally acquired rotavirus infections and reinfections in the first two years of life were studied in 13 cases and 12 control children using enzyme-immunoassay. A 100% IgG seroconversion and coproconversion occurred after tertiary and quaternary infections respectively. Unlike the IgA coproantibody response, serum IgG was detected more frequently after symptomatic (89%) than asymptomatic (50%) infections, and its duration and titre were boosted by reinfections. The durations of both responses was prolonged when reinfection occurred at 15 months versus 8 months. Both responses were observed after primary infection in the first two months of life. Higher instances of virus reinfections were detected serologically (72.5%) than virologically (27%). The results suggest that at least 3 doses of a rotavirus vaccine will be required before 4 months plus boosters around the 10th and 15th months. Further, during vaccine trials, virus infections should be monitored virologically and serologically.

Objective: Delineation of change in male hormone and gonadotropin levels from age 21 to 85., Subjects: Healthy married volunteers with one or more children., Methods: A 5-mL venous blood sample, serum separated within one hour; testosterone measured by direct RIA, FSH and LH by immunoradiometric assay and magnetic separation., Results: FSH significantly higher from 6th decade, LH from 7th decade; testosterone lower from 6th decade., Conclusions: Apparently, a rise in FSH and reduction in testosterone precede a rise in LH concentration.

Integrated hourly concentrations of day-time prolactin and LH showed significant positive correlations (p < 0.05-0.001) on the day of the pre-ovulatory mid cycle LH surge (n = 3) and during the mid luteal phase (n = 6) in a group of regularly cyclic women. No correlations between these two hormones were seen during any other stage of the cycle. Consistent significant correlations were not evident between prolactin and oestradiol, prolactin and progesterone, LH and oestradiol or LH and progesterone during any other stage of the cycle.

Many factors influence the regulation of pharmaceuticals in a country. The essential drugs concept, formulated by the World Health Organization to assist developing countries in selecting appropriate drugs, also provides a basis for regulation. Sri Lanka has long regulated pharmaceuticals as part of its health policy. Over 70% of 3436 pharmaceutical product registrations were found to be drugs (or alternatives) named in the country's essential drugs list. This is despite the fact that product registrations are mainly for the private health care sector, and the list is for the state sector. The essential drugs concept therefore appears to have influenced the pharmaceuticals registered in Sri Lanka.

The assessment of malarial infectivity, for example in the evaluation of transmission blocking immunity, is generally based on counting oocysts in mosquitoes fed on infected blood. Ultimate transmission of the disease may, however, depend on the sporozoite load in the mosquito and its relationship to the size of the inoculum introduced to man. We conducted a laboratory study on Anopheles tessellatus infected with 108 different natural isolates of Plasmodium vivax from patients and 24 of P. falciparum to determine the relationship between oocyst numbers, sporozoite loads, and the effect of these on mosquito mortality. It was found that the P. vivax parasite density was positively correlated with the proportion of mosquitoes infected by a given feed at both the midgut and gland stages of parasite development (correlation coefficient [r] = 0.77, P < 0.001 and r = 0.6, P < 0.05 respectively). A significant positive linear correlation was observed between the number of oocysts and sporozoites in P. vivax (r = 0.5; P < 0.05); the proportions of mosquitoes infected with oocysts and sporozoites were also similarly related, although in general about 15% of mosquitoes infected with oocysts failed to develop salivary gland infections with sporozoites. The number of mosquitoes infected with P. falciparum parasites was too low for statistical analysis. Infection with either species of parasite did not appear to affect mosquito survival, nor was parasite density in the mosquito correlated with mosquito mortality.

Duchenne muscular dystrophy (DMD) is an X-chromosome-linked myopathy caused by a defect in the DMD gene. Intragenic deletions appear to be the most common gene defect leading to DMD, and the deletion frequency has been estimated to be 66%. Results of this study using a group of 24 DMD patients of Sri Lankan origin employing the technique of multiplex DNA amplification using the polymerase chain reaction indicated a deletion frequency of 62.5%. Eighty per cent of these deletions were localized in a region of the DMD gene regarded as a 'hot spot' for DMD deletions. Our results are in agreement with the results of other studies carried out on Caucasian populations.

Dichloromethane-methanol (1:1) extracts of ten species of alcyonacean soft corals were screened for post-coital interceptive effects on female rats, using oral administration, from day 1 to day 7 of pregnancy. Significant suppression of fertility was observed in the animals treated with the crude extracts of Sarcophyton ehrenbergi (250 mg/kg/day, P less than 0.05; 500 mg/kg/day, P less than 0.001), Sinularia crispa (500 mg/kg/day, P less than 0.05; 1000 mg/kg/day, P less than 0.001), Sinularia abrupta (1000 mg/kg/day, P less than 0.001), Sinularia spp--III (500 mg/kg/day, P less than 0.05). This antifertility effect appears to be due to interruption of embryonic events during implantation and/or pre-implantation periods.

Serum effects on gametocyte infectivity, that is, transmission blocking/enhancing immunity, were measured in the sera of 196 acute Plasmodium vivax patients who were residents of a malaria region in Kataragama, southern Sri Lanka. Direct mosquito feedings were also performed on 170 of these patients. Sera of about 48% of patients suppressed gametocyte infectivity significantly (by more than 75%) and of a smaller proportion (12%) had pronounced infectivity enhancing effects. Transmission immunity did not increase with age of patients, rather, immunity tended to be higher in younger patients. Data suggest that immunity levels are boosted by reinfections only if they occur within a period of 4 months from the previous infection, i.e., that immune memory for boosting does not last beyond 4 months. Enhancing effects in the sera of patients correlated with the absence of gametocytes at the time of investigation suggesting that enhancement occurs early during the course of a blood infection, and blocking later, when serum antibodies reach higher levels. The blocking and enhancing effects of serum appears to depend not only on the antibody concentration in serum, but also on the intrinsic infectivity of the parasite isolate against which it is tested: thus, infectivity enhancing effects were potentiated by low intrinsic infectivities of the parasite isolate. The direct infectivity of patients to mosquitoes correlated with transmission immunity indicating that transmission immunity is an influential factor determining infectivity of malaria patients.

Plasmodium vivax malaria infections in non-immune individuals manifest as periodic clinical episodes of fever with chills and rigors known as paroxysms. We have demonstrated that in non-immune patients the period of paroxysm is associated with the transient presence of plasma factors which kill gametocytes, the intra-erythrocytic sexual stages of the malaria parasite which transmit the infection from humans to mosquito, rendering them non-infectious to mosquitoes. Gametocyte killing in paroxysm plasma is mediated by tumour necrosis factor (TNF) acting in conjunction with other essential serum factor(s). Plasma TNF levels were elevated during a paroxysm. In semi-immune individuals from a P. vivax-endemic area clinical symptoms of malaria are mild and the parasite killing factors are not induced during paroxysm. Serum TNF levels were correspondingly lower in endemic patients during a paroxysm. Human peripheral blood mononuclear cells (PBMC) can be stimulated in vitro by extracts of P. vivax blood stage parasites to produce TNF and associated parasite killing factor(s), thus simulating in vitro the events that occur during a paroxysm, this being the release of parasite exo-antigens by rupturing schizonts and the subsequent induction of PBMC to produce TNF and other parasite-killing factors. We were able to show that convalescent serum from P. vivax semi-immune individuals block the induction of TNF and parasite-killing factors by malaria antigens in vitro, presumably through antibodies that neutralize parasite exo-antigens. Thus, individuals living in malaria-endemic areas appear to acquire clinical immunity to malaria by avoiding their induction during infection; we have shown that one such mechanism is the neutralization of parasite exo-antigens that induce the production of parasite killing factors.

Paroxysms are sharp episodes of high fever accompanied by chills and rigors that occur periodically, once in every 48 hr in Plasmodium vivax infections. We have measured the changing levels of serum tumor necrosis factor (TNF) during paroxysms in non-immune patients infected with P. vivax malaria. The changes in TNF levels closely paralleled the rise and fall in temperature during the paroxysms but tended to precede them by 30-60 min. These observations suggest that the rise and fall in temperature during P. vivax paroxysm may be directly related to the periodic changes in TNF levels induced during these infections. The peak TNF levels reached during P. vivax infections were much higher than even those which have been recorded during severe and fatal P. falciparum infections in which TNF has been postulated to contribute to the severe manifestations of this disease.

The usual form of the Mantel-Haenszel test statistic assumes independent observations. This is inappropriate for data from a stratified multistage survey. Two alternative adjustments to the test statistic are developed to deal with this: (a) a modification of the effective sample size for each row of each table, using the design effects, extending a method proposed by Donald and Donner for familial aggregation studies; (b) a Taylor series approximation to the variance of the square root of the numerator of the Mantel-Haenszel statistic. Both methods are evaluated by application to both simulated and real data. The two methods perform equally well, and offer a considerable improvement over the unadjusted test statistic when observations from the same cluster are highly correlated. A simplified adjustment is also considered, as is the need for correction to the variance of the odds ratio estimator.

A mathematical expression was derived to estimate the relative malaria transmission efficiency of an anopheline species with respect to a standard well-characterized species for which all vector parameters can be sufficiently determined. The method is particularly useful in situations where multiple anopheline species contribute to human malaria transmission and requires the estimation of the man-biting rate, the sporozoite rate, and the human malaria incidence. Under stable conditions of vector abundance, the average sporozoite rate in a species during a transmission season would by itself reflect its relative transmission efficiency. This "efficiency" then was used to calculate the "effective human-biting rate"; i.e., the human-biting rate of that species if it were to have ecological properties identical to those of the standard species. The standard well-characterized species then could be used with the effective human-biting rate of all species to quantify transmission, thus overcoming the need to measure vector parameters for all anopheline species contributing to transmission. An expression also was derived to calculate the relative contribution made by each species to malaria transmission. The usefulness of this method was illustrated using entomological and epidemiological data from Kataragama, Sri Lanka.

The inhibitory effects of the prostanoid receptor antagonist, di-4-phloretin phosphate (DPP), upon washed human sperm motility were determined in vitro (up to 60 min of incubation). Concentrations tested were: 0.001, 0.01, 0.1, 0.25, 0.5, 2.5, 5.0 and 10.0 mM. All concentrations of DPP investigated caused cessation of sperm movement (percentage motility and average forward velocity) and the antimotility effect was essentially irreversible. The concentrations producing 50% inhibition were: percentage motility--1.31 +/- 0.56 mM (mean +/- SEM) and average forward velocity--1.95 +/- 0.68 mM. The mode of antimotility action appears to be multi-faceted. At high (10 mM) and intermediate (2.5 mM) concentrations, changes in fluidity of sperm plasmalemma (hypoosmotic swelling test) and loss of viability (nigrosin-eosin stain technique) constitute the primary means by which motility was disrupted. In contrast, these two parameters of motility remained unaltered at a lower concentration (0.25 mM) of DPP, and the mechanism precipitating the antimotility effect may involve mobilization of stored calcium ions and modulation of cyclic AMP levels.

The variation in the healing and the relapse rates of peptic ulcer disease has led to the search for other factors in the pathogensis of peptic ulcer disease. Helicobacter pylori is believed to be responsible for these different patterns of healing. The results of a study to detect Helicobacter pylori in Sri Lankan patients having duodenal ulcer, gastric ulcer, gastritis and non-ulcer dyspepsia are presented in this paper. The method employed was the urease test which detects the urease enzyme of H. pylori in gastric mucosal biopsies taken during upper gastrointestinal endoscopy. There is a high incidence in those with gastritis and duodenitis.

The achievement or reproductive intentions of Sri Lankan women was examined by using longitudinal data for the period 1982-85. Aggregate consistency between reproductive intentions and behavior was almost perfect, but at the individual level there were inconsistencies. Among those who wanted to have no more children, 23 per cent reported a birth in the intersurvey period of 3 years and 2 months, while failures to have a wanted birth stood at 36 per cent. There was a clear declining trend in the former type of inconsistencies in Sri Lanka, but the latter type has increased, possibly due to a continuing decline in family size ideals or due to deferred childbearing. Even though inconsistencies existed, expressed fertility intentions in 1982 significantly influenced the fertility outcome. The study also has a methodological focus on whether to include sterilized women when fertility intentions and behavior are examined longitudinally, but no specific problems were found with their inclusion. Results indicate that, apart from the intention variable, age, marital duration, family size, and education of husband and wife variables all influenced fertility in the follow-up period.

Antibodies to two peptides DDAAD and (NANP)40 representing the repetitive sequence of circumsporozoite antigens (CS protein) of P. vivax and P. falciparum respectively were measured in a cohort of 149 and 107 individuals respectively at four, 6 monthly blood surveys performed on residents of Kataragama, a P. vivax malaria endemic region in southern Sri Lanka. The prevalence of antibodies to the CS protein of both species was relatively low being less than 20% to either peptide in the population as a whole, this being consistent with the low entomological inoculation rates in the area. A marked age related prevalence pattern was evident, with the prevalence of antibodies increasing with age to reach between 25 to 30% in the 25-50 year age group in both P. vivax and P. falciparum. The population had had a life long exposure to P. vivax malaria but not to P. falciparum, an epidemic of which occurred in this region a few months prior to the beginning of this study. Nevertheless, the age-related prevalence of these antibodies was identical with respect to the two species. This suggests that the age-related prevalence pattern reflected differences in inoculation rates between the age groups due to differences in exposure to inoculation rather than an age acquired response resulting from a cumulative experience over several years. An analysis of antibody prevalence in individuals showed first, that sporozoite inoculations must have been clustered rather than homogeneously distributed in the population and secondly, that sero-conversion did not correlate with malaria infections in these individuals.

The cytokine tumor necrosis factor and other as yet unidentified factor(s) which together mediate the killing of intraerythrocytic malaria parasites are transiently elevated in sera during paroxysms in human Plasmodium vivax infections in non-immunes. These factors which included TNF and parasite killing factor(s) are associated with the clinical disease in malaria to the extent that their transient presence in infection sera coincided with paroxysms, the the most pronounced clinical disturbances of P. vivax malaria and secondly because their levels were markedly lower in paroxysm sera of semi-immune patients who were resident of an endemic area. Further, a close parallel was obtained between serum TNF levels and changes in body temperature that occur during a P. vivax paroxysm in non-immune patients, suggesting a causative role for TNF in the fever in malaria. P. vivax rarely if ever cause complicated clinical syndromes. Nevertheless serum TNF levels reached in acutely ill P. vivax patients were as high as in patients suffering from cerebral complications of P. falciparum malaria as reported in studies from the Gambia. Cytokine profiles and other changes accompanying clinical disease in P. vivax and P. falciparum malaria are compared in this paper with a view to discussing the potential role of cytokines in the causation of disease in malaria.

The immunogenicity of multiple antigen peptides (MAP) constructs containing T and B cell epitopes of the repeat region of the P. falciparum circumsporozoite (CS) protein was examined in vitro, using a human T cell clone, and in vivo, using four different strains of mice. All the MAP constructs that contained the T cell epitope, (DPNANPNVDPNANPNV), stimulated proliferation and interferon-gamma production by a human T cell clone specific for this epitope which is located in the 5' end of the repeat region of the P. falciparum CS protein. These human T cells did not recognize MAP that contained only the B cell epitope, (NANP)3, which is located in the 3' repeat region. Optimal antibody responses were obtained in mice immunized with MAP containing four copies of tandemly arranged T and B cell epitopes, (TB)4. The murine immune response to the MAP constructs was genetically restricted. Mice of a high responder strain, C57BL, recognized both the 5' and 3' repeat sequences in the MAP as T, as well as B, cell epitopes and developed very high anti-MAP and anti-sporozoite antibody titers. A/J and C3H mice, which were intermediate responders, developed lower antibody titers which varied according to the orientation of the T vs. the B cell epitopes within the MAP constructs. BALB/c mice were nonresponders and did not develop antibodies following immunization with any of the MAP constructs containing the 5' and 3' repeats of the P. falciparum CS protein.

The infectious reservoir of Plasmodium vivax and P. falciparum in a malaria endemic region in Sri Lanka was defined in a population of 3,625 by directly feeding mosquitoes on a sample of infected individuals during a period of 17 months. The malaria case incidence in this population was concurrently monitored. P. vivax gametocyte densities were highest in the youngest age groups, and decreased steadily with increasing age. However, the infectivity per gametocyte appeared to be lower in the younger age groups than in the older ones. There was no significant correlation between the age of patients and their gametocyte densities for P. falciparum, to which this population was only recently exposed, nor was there a discernible trend in the infectivity per gametocyte in different age groups. The average infectivity of patients was lowest in the youngest (0-5 years) and the oldest (greater than 50) age groups. The contribution made by P. vivax patients in the different age groups to the reservoir of infection was estimated. Patients in the 6-25 year age groups made the largest contribution to the reservoir, followed by those in the 26-50 year age group. Patients in the youngest and the oldest age groups contributed least to the infectious reservoir. When population sizes in the different age groups were taken into consideration, the age groups between 6 and 50 years contributed almost equally to approximately 87% of the infectious reservoir. The reservoir of P. falciparum malaria was very small, being confined to 9% of the patients, and this appears to be a characteristic of epidemic malaria, as was the case with P. falciparum.

Vitamin A status was assessed in early and late stages of pregnancy in 496 pregnant women living in Colombo, Kurunegala, Kegalle, Badulla and Galle districts, using clinical, dietary and biochemical parameters. Serum vitamin A concentration was determined by a fluorometric method and the retinol binding protein concentration by radial immunodiffusion. The serum vitamin A levels of subjects in the lowest socioeconomic group in Galle and Kegalle districts were significantly lower than those living in Colombo. The percentage of subjects having serum vitamin A levels less than 20 micrograms/dl, increased in late pregnancy in all areas, with the highest value (27.8%) in the Galle district. None of the subjects had severe ocular manifestations of vitamin A deficiency. The higher incidence of subclinical vitamin A deficiency noted among subjects in Galle and Kegalle districts could be attributed at least in part to a low dietary intake of vitamin A and carotenoids.

The occurrence of malaria infections due to Plasmodium vivax and P. falciparum was monitored in a population of 3,023 people living in six contiguous villages in Kataragama, an area of endemic malaria in southern Sri Lanka, over a period of 17 months. The annual incidence of malaria in this population during the study period was 25.8%. Malaria attacks were clustered, occurring more frequently than expected in certain individuals and housing groups and less frequently than expected in others. In one of these villages, the distribution of cases was examined in relation to locality and to the type of house construction. There was a strong association between the malaria incidence and house construction, independent of location. The risk of getting malaria was greater for inhabitants of the poorest type of house construction (incomplete, mud, or cadjan (palm) walls, and cadjan thatched roofs) compared to houses with complete brick and plaster walls and tiled roofs. Houses that were better constructed had a significantly lower malaria incidence rate (10.5%) than those that were poorly constructed (21.2%; P less than 0.01, by Student's t-test). There was also a significantly higher number of indoor resting mosquitoes collected from the poorly constructed houses than from those better constructed; the average (geometric mean) of mosquito densities found in houses of better versus poor construction were 0.97 and 1.89 per collection in the dry season, and 1.95 and 3.42 per collection in the wet season, respectively (P less than 0.05 in both seasons). This indicated that the higher malaria risk associated with poorly constructed houses was at least partly due to higher human-mosquito contact among their inhabitants.

The biologically active luteinizing hormone concentrations (as measured by testosterone production by mouse Leydig cells in response to LH) were measured in integrated hourly blood samples collected over 24-hour study periods during different stages of the menstrual cycle from a group of regularly cyclic women. Time series analyses were used to analyse the ultradian rhythms in each individual 24-hour LH profile. Fast Fourier transform (FFT) showed the presence of several ultradian rhythms with different periodicities (varying from 4.4 to 22 hours) in most of the LH profiles. In some of the LH profiles several ultradian rhythms appeared to co-exist. The commonest significant rhythm as detected by the FFT had a periodicity of 7-9 hours during both the follicular phase (40% of the subjects) and the mid cycle (50% of the subjects) and a periodicity of 5-7 hours during the luteal phase (44% of the subjects).

This study examined the inhibitory effects of a methanol extract of Abrus precatorius seeds on the motility of washed human spermatozoa. The extract caused a concentration-related impairment of percentage sperm motility; with the EC50 concentration being 2.29 mg/ml. This effect on motility was essentially irreversible. With the highest concentration tested (20.0 mg/ml), the onset of the antimotility action was almost immediate. In addition, this concentration impaired the functional integrity of the plasma membrane (hypoosmotic swelling test) and viability (nigrosin-eosin stain) of spermatozoa. In contrast, with a lower concentration (5.0 mg/ml), such effects were not evident. It is concluded that at the lower concentrations the antimotility action may result from a rise in intracellular calcium (not via influx) and/or a decline in cAMP content and/or enhanced generation of a reactive oxygen species.

Aqueous extracts of the seeds of Nigella sativa and mature leaves of Dregea volubilis were administered orally under light ether anaesthesia to male Sprague-Dawley rats for 14 days. Key hepatic enzyme concentrations and histopathological changes in the liver in both treatment groups at the end of 14 days were compared with a control group which received distilled water under identical conditions for 30 days and with a group of normal animals. Serum gamma-glutamyl transferase concentrations were significantly increased in both extract groups while serum alkaline phosphatase concentrations were significantly increased following administration of only D. volubilis when compared with either the control or the normal group. Serum alanine aminotransferase concentrations were significantly increased in both extract groups when compared with the normal group but not with the control group. Degenerative changes in hepatocytes were seen following administration of D. volubilis while consistent significant histopathological changes were not evident following administration of N. sativa.

Malaria infection crisis, at which the parasitemia drops precipitously and the parasite loses infectivity to the mosquito vector, occurs in many natural malaria systems, and has not been explained. We demonstrate that in a simian malaria parasite (Plasmodium cynomolgi in its natural host, the toque monkey), the loss of infectivity during crisis is due to the death of circulating intraerythrocytic gametocytes mediated by crisis serum. These parasite-killing effects in crisis serum are due to the presence in the serum of cytokines tumor necrosis factor and interferon gamma, which are produced by the host as a result of the malaria infection. The killing activity of each cytokine is absolutely dependent upon the presence of additional, as yet unidentified factor(s) in the crisis serum.

Malarial infections do not readily evoke an effective protective immunity against re-infection. Possible reasons for this include the ability of the parasites to interfere with the host's immune response and to evade the response in an immune host, by, for example, exploiting antigenic polymorphism or variation. Antigenic polymorphism undoubtedly exists in malaria parasite populations but does this polymorphism actually contribute to immune evasion by the parasite? Here, Kamini Mendis and colleagues examine the evidence for this and its implications for future malaria vaccines.

Identification of self-perceived learner needs is important in continuing education programmes for health professionals. This paper describes the use of a self-evaluation skill inventory as a method of determining priorities for continuing education of a category of middle-level health professionals.

The importance of acute poisoning as a cause of morbidity and mortality in many developing countries has been highlighted in recent times. This study discusses the utilization of routinely collected data from hospitals for background information required in planning and implementing preventive programs. The high prevalence of poisoning and its distribution countrywide were highlighted by the routinely collected data, while the retrospective study of hospital admissions identified the wide range of toxic agents and age and sex differentials in the pattern of poisoning. Even though the overall case fatality rate was 7.6%, there was wide variation among the different toxic agents.

A retrospective hospital-based study in Sri Lanka showed that out of 4556 cases of poisoning, 2.5% were caused by plants and mushrooms. Gloriosa superba (44%), and Ricinus communis (24%) were the commonest plants responsible for poisoning; 39% of the victims were less than 15 y old. Gastric lavage and iv fluids were the most common therapeutic measures used. There were 8 deaths, all due to G superba. There is a need for public education to prevent poisoning, which is a major health concern.

Ninety-three females in the age group 14-18 years were randomly selected from three schools in Colombo. Their iron and nutritional status was assessed using clinical, anthropometric, haematological, and biochemical parameters. Haemoglobin levels less than 12 g/dl were seen in 3.7 per cent of adolescent females. Free erythrocyte protoporphyrin levels greater than 70 micrograms/dl and serum percentage transferrin saturation values less than 16 per cent indicate iron deficiency and were seen in 10 per cent and 14 per cent of the subjects, respectively. Serum ferritin levels less than 12 micrograms/l indicate depleted iron stores and were seen in 59 per cent of the subjects studied. Our results suggest that although overt anaemia was not common among the subjects studied, a large number of subjects belonging to the lower socio-economic groups were in the early stages of iron deficiency and had depleted iron stores. These subjects are, therefore, at risk of developing clinical manifestations of iron deficiency when the demand for iron is increased, as in pregnancy.

The infectivity of Plasmodium cynomolgi in its natural host, the toque monkey, Macaca sinica, to Anopheles tessellatus mosquitoes was studied in relation to the evolution of anti-sexual-stage immunity in the host during the course of a blood-induced infection. The effects of serum on the infectivity of gametocytes and the intrinsic infectivity of gametocytes to mosquitoes on each day were assessed in membrane feeding experiments. Mosquitoes were also directly fed on the animal on each day. Our results demonstrate that during the very early patent period, before the peak of gametocytemia, the infection serum enhanced the infectivity of gametocytes up to two to three times above their infectivity in normal monkey serum. Subsequently, serum drawn post-peak of parasitemia ceased to enhance, and began to suppress, infectivity. After 2-3 months, long after parasitemias ceased patency, the serum no longer suppressed and between 3 and 4 months the serum again tended to enhance gamete infectivity before losing any significant effect. Serum infectivity enhancing effects were consistent with low indirect immunofluorescence test antibody titers against blood stage parasites first during the very early days of a blood infection before reaching blocking levels, and again during convalescence when antibodies were declining. The serum infectivity blocking effects on gametocytes were seen at the peak of antibody titers from about Days 9 to 23 of an infection. From 78 to 95% of the total infectivity of the parasite to mosquitoes during an infection occurred when infectivity enhancing activity was present in the serum. Hence, the infectivity of the parasite to mosquitoes was largely dependent on infectivity enhancing antibodies in host serum.

The oral hypoglycaemic activity of Momordica charantia fruit juice was investigated in rats with streptozotocin-induced diabetes. Oral administration of the juice (10 ml/kg for 30 days) did not show a significant effect, either acute or cumulative, on the ability to tolerate an external glucose load. The glycosylated haemoglobin concentrations were significantly elevated in both juice-treated and untreated diabetic rats and there was no significant difference between the two groups. Viable beta-cells capable of secreting insulin upon stimulation appear to be required for M. charantia to exert its oral hypoglycaemic activity.

Cytokines induced during natural malaria infections, e.g., at crisis of a blood infection of Plasmodium cynomolgi, and during clinical paroxysms in human Plasmodium vivax infections, mediate killing of intra-erythrocytic blood stage malaria parasites. These cytokines, TNF and IFN-gamma, require additional, yet unidentified complementary factors that are present in "crisis" and "paroxysm" serum to kill intra-erythrocytic blood stage parasites. In contrast, cytokines, (mainly IFN-gamma) are able to effect killing of intra-hepatic stages of the parasite by themselves independent of serum complementary factors, suggesting that the mechanisms of killing may be different with respect to the two parasite stages. Cytokines also appear to be critical intermediates in mechanisms of clinical disease in malaria. Serum cytokine (TNF) levels and killing effects on blood stage malaria parasites were lower in patients who were exposed to endemic P. vivax malaria who had partial clinical immunity, than in non-immune patients. Evidence suggest that individuals acquire natural immunity to the disease by avoiding the induction of high levels of cytokines and complementary factors.

Electrocution is a rare mode of suicide. In Sri Lanka, where the suicide rate is extremely high, ingestion of liquid pesticides is the commonest method used. The case of a 34-year-old labourer of the Electricity Board, who committed suicide using 220-240 volt domestic electricity supply is described. He had been suffering from a depressive illness for some time. Suicide by electrocution has not been documented in Sri Lanka before.

Studies on the natural immune responses to the sexual stages of malaria parasites have been reviewed in the context of human malaria transmission-blocking vaccines. Antibodies against the sexual stages of the malaria parasite, gametocytes and gametes, are readily evoked by natural malaria infections. These antibodies that suppress infectivity at high concentrations can, at low concentrations, enhance the development of the parasite in the mosquito; however, because enhancing antibodies are prevalent during natural malaria infections, it is likely that a vaccine would rapidly boost these antibodies to blocking levels. The immunogenicity of sexual stage antigens appears to be constrained in the human host, probably due to T epitope polymorphism and MHC restriction in humans. These constraints apply mainly to those antigens that are sensitive targets of host immunity such as the gamete surface antigens and not to internal gamete antigens, indicating that antigenic polymorphism may have evolved in response to immune selection pressure. Evidence for immunosuppression of the host by exposure to endemic malaria is presented and its consequences on vaccine development are discussed.

A panel of 20 anti-Plasmodium vivax female gamete mAb has been established and was characterized with respect to their transmission-blocking properties in membrane-feeding experiments and their target Ag identified. Seven mAb suppressed the infectivity of P. vivax parasites to Anopheles tesselatus mosquitoes. The m.w. of the Ag recognized by these mAb were ascertained by SDS-PAGE and Western blots. Three sets of polypeptides of low Mr--20, 24, and a doublet of 37/42 kDa--have been defined as target Ag of transmission-blocking antibodies of P. vivax. All epitopes of these target Ag were found to be dependent on the tertiary conformational structure of the Ag. Polymorphism of target Ag of transmission-blocking immunity was investigated in over 30 natural isolates of P. vivax in Sri Lanka based on the reactivity of a mAb with an isolate as assessed by the indirect immunofluorescent test with the use of live extracellular female gametes, and in Western blots with the use of extracted gametes. The functional consequences of antigenic polymorphism on immunity was investigated in transmission-blocking assays by using membrane-feeding experiments. A majority of target Ag of transmission-blocking immunity were found to be polymorphic, exhibiting size as well as epitope polymorphism. Results indicate that failure of a mAb to affect the infectivity of a parasite isolate of P. vivax to mosquitoes can be caused by polymorphism of the target Ag among isolates.