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Biomedical subjects

J Remme

Publications and source records attributed to J Remme.

At least 55 records · Page 3Linked to original sources
PubMed1989

Ocular onchocerciasis and intensity of infection in the community. I. West African savanna.

A method is introduced for the analysis of community patterns of ocular onchocerciasis in relation to the intensity of infection as measured by the Community Microfilarial Load (CMFL). Specific features of this method are the clear definition of ocular lesions and their separation into early and advanced stages, and the estimation of the prevalence of onchocercal blindness after exclusion of other causes of blindness. The method is applied to the ophthalmological and parasitological data from 33 villages from the West African savanna in order to obtain a reference pattern for subsequent analyses of ocular onchocerciasis patterns from other bioclimatic zones. In the savanna, there exists a clear linear relationship between most indices of ocular onchocerciasis and the CMFL. Mean ocular microfilarial loads, prevalences of the advanced lesions of the anterior and posterior segment of the eye and prevalences of different classifications of blindness show a high degree of correlation with the CMFL, as does also early sclerosing keratitis. The correlation is poor for the other early ocular lesions. All relationships are similar for the two sexes with the exception of posterior segment lesions which remain more common in males after correction for intensity of infection. The CMFL is superior to the prevalence of microfilariae in the skin as an index of endemicity. It allows a good prediction of the severity of onchocercal ocular disease in savanna communities using parasitological information only.

Adolescent↗
PubMed1989

A community trial of ivermectin in the onchocerciasis focus of Asubende, Ghana. I. Effect on the microfilarial reservoir and the transmission of Onchocerca volvulus.

A community trial of the microfilaricide ivermectin was undertaken in an isolated focus of hyperendemic savanna onchocerciasis in Ghana. One of the objectives was to determine the effect of mass treatment on the microfilarial reservoir and on the transmission of Onchocerciasis volvulus. Since 1978 the focus has been under entomological surveillance. This was intensified from 1 September 1987 till 11 February 1988 with daily vector collection and dissection of over 30,000 flies. A total of 14,991 people were treated with ivermectin on 7-10 October 1987. Skin snip surveys were done pre-treatment, and at two and four months after treatment. The mean skin microfilarial load in treated persons had fallen by more than 96% two months after treatment. During the next two months there was an increase in microfilaria loads which appeared to be faster than reported in the clinical trials. The total reservoir of skin microfilariae available for transmission had been reduced by an estimated 68%-78% two months after treatment. This was consistent with the entomological results which indicated a reduction in transmission of 65%-85% during the first three post-treatment months. The present study has shown for the first time that mass chemotherapy can significantly reduce onchocerciasis transmission. However, the remaining level of transmission was still unacceptably high and further studies are required to predict the long term impact of repeated mass treatment.

Animals↗
PubMed1989

A community trial of ivermectin in the onchocerciasis focus of Asubende, Ghana. II. Adverse reactions.

A community trial of the microfilaricide ivermectin undertaken in an hyperendemic focus of blinding onchocerciasis in Ghana. One objective was to investigate the safety of this new drug when used in mass treatments. 14,911 persons (61.5% of the census population) were treated with ivermectin. Of these, 15% reported with adverse reactions which were generally similar to those reported in the clinical trials. However, cutaneous reactions were relatively less frequent while brawny oedema of the limbs and inguinal gland pain were important. The severe reactions consisted of 37 cases of Severe Symptomatic Postural Hypotension (SSPH), 13 cases of severe fever and two cases of severe dyspnoea. The latter two cases represented life threatening situations, but there was no evidence that they were complications of ivermectin treatment. Only four of the SSPH cases required treatment. All severe adverse reactions were managed successfully and recovered within one day, usually within a few hours. The incidence of adverse reactions was highest the first day after treatment. Thirteen cases of delayed reactions were reported during a four-week follow-up. There was a highly significant relationship between incidence of adverse reactions and intensity of infection but no relation with ivermectin dosage within the range of 130-200 mcg/kg. The results suggest that ivermectin is sufficiently safe to be used in mass treatments. However, mass distribution of this drug should not be undertaken without adequate monitoring.

Adolescent↗
PubMed1989

Adverse reactions after large-scale treatment of onchocerciasis with ivermectin: combined results from eight community trials.

Eight community trials were carried out by the Onchocerciasis Control Programme in West Africa to determine the safety of the new microfilaricide ivermectin during large-scale treatment of onchocerciasis. The trial areas were located in eight different countries and varied greatly in endemicity level; a total of 50,929 persons were treated and monitored for 72 hours. Overall treatment coverage was 60% of the census population, the main reasons for non-treatment being the exclusion criteria. Of those treated, 9% reported with adverse reactions, 2.4% with moderate reactions, and 0.24% with severe reactions. Most reactions were reported during the first day of follow-up, the most frequent severe reaction being severe symptomatic postural hypotension (in 49 cases). Three cases of severe dyspnoea were life-threatening but their relationship with ivermectin treatment is uncertain. The incidence of adverse reactions was directly related to skin microfilarial load and was highest in the foci with the highest endemicity levels. Treatment resulted in 98% reductions in mean microfilarial loads at all endemicity levels. The benefit of treatment largely compensated for the discomfort due to adverse reactions, which were all transient and managed successfully. Ivermectin thus appears to be sufficiently safe for large-scale treatment but monitoring by resident nurses for at least 36 hours is recommended.

Africa, Western↗
PubMed1987

Population dynamics of Onchocerca volvulus after 7 to 8 years of vector control in West Africa.

In an attempt to describe the changing population dynamics of Onchocerca volvulus during a period of vector control, nodulectomies were undertaken in 256 patients from ten villages in the Onchocerciasis Control Programme (OCP) and in 74 patients from two villages in an area with ongoing transmission. A total of 1198 nodules were excised and 4350 adult worms were isolated and examined for viability and productivity. In the OCP villages, the worm population is ageing and dying without replacement by new generations of parasites and various findings signal a breakdown of the worm population after about 12 years interruption of transmission. The sexual activity of the worms was significantly reduced. A Productivity Index was developed to measure the microfilariae production at the nodule level. The reduction in this index for the OCP villages correlates closely with the decline over the control period in the community microfilarial loads in the skin. The results show that it is not only the longevity of the parasite which will determine the duration of vector control, but that the reduced productivity of the ageing parasite population is of equal importance.

Africa, Western↗
PubMed1987

[Role of children in the evaluation of the Onchocerciasis Control Program in West Africa].

Incidence of onchocercal infections is studied in children borne since the start of the larvicidal treatments of the Onchocerciasis Control Programme in West Africa (OCP). A total of 8088 children, originating from 155 villages widely distributed throughout the initial area of the OCP were examined for microfilariae of O. volvulus. 37 were found infected. If there had not been control measures, 652 children would normally have become infected in such a sample. It is considered that in the centre of the OCP area which constitutes approximately 90% of the total, transmission has been interrupted (1 child infected among 5,886 examined in the centre). The remaining 36 cases are spread over two quite distinct marginal zones of the OCP where transmission persisted because of reinvasion by blackflies coming from untreated areas, or because of insecticide vector resistance, or because of occasional treatment failures. The entomological indices confirm perfectly the epidemiological findings in the central region as well as in the marginal zones.

Africa, Western↗
PubMed1986

A force-of-infection model for onchocerciasis and its applications in the epidemiological evaluation of the Onchocerciasis Control Programme in the Volta River basin area.

A simple force-of-infection model for onchocerciasis has been developed for a study of the age-specific epidemiological trends during a period of vector control in the Onchocerciasis Control Programme in the Volta River basin area (OCP). The most important factors included in the model are the longevity of an infection, the aspect of super-infection, age-specific exposure, and the intensity of transmission during the pre-control period. The aim of the study was to determine the most appropriate statistics for the epidemiological evaluation in the OCP. There was generally good agreement between the epidemiological trends, predicted by the model, and the observed trends in the prevalence and mean load of microfilariae in skin snips taken from a cohort population from 23 villages in an area with 8 years of successful vector control in the OCP. It is concluded that the epidemiological trends during the control period are not uniform but depend on the initial age and the initial endemicity level of the population. The epidemiological indices for cohorts of children, born before the start of control, will not show a decrease during the first 8 years of interruption of transmission. The prevalence is too insensitive to be useful for the evaluation in hyperendemic villages during most of the control period. The most sensitive and meaningful statistic for a comparative analysis and for the assessment of epidemiological changes is the geometric mean microfilarial load in a cohort of adults. This index, which is called the Community Microfilarial Load (CMFL), is now routinely used in the OCP. The new analytical methodology has enabled a much better appreciation of the significant epidemiological impact of 8 years of vector control in the OCP. Several related aspects of the pre- and post-control dynamics of onchocerciasis infection are also discussed and priorities are formulated for further work on applied modelling of onchocerciasis.

Adolescent↗
PubMed1986

The effect of 7-8 years of vector control on the evolution of ocular onchocerciasis in West African savanna.

The evolution of ocular onchocerciasis was studied in a cohort of 1170 persons over 5 years of age who were examined before the start of and after 7-8 years of effective vector control in 12 originally hyperendemic villages in the central part of the OCP area. The proportion of the cohort which at the outset of vector control was free from ocular onchocerciasis or had an early or recent infection in the form of punctate keratitis only, remained largely free of or lost their signs of ocular infection respectively and only a very insignificant proportion acquired microfilariae in the eyes or developed a severe onchocercal eye lesion at the initial stage. The proportion of the cohort with a heavy ocular microfilarial load had a reduced risk of developing severe eye lesions and no risk of going blind. The proportion of the cohort with already existing severe eye lesions at the advanced stage remained largely unchanged and some lesions at the initial stage disappeared. Blindness occurred only in those who had severe eye lesions at the outset and was comparatively less than in areas of on-going transmission.

Adolescent↗
PubMed1985

The properties of the complex between ribosomal protein L2 and tRNA.

Escherichia coli ribosomal protein L2 interacts with fMet-tRNAfMet and NacPhe-tRNAPhe in solution, protecting their 3'-ends from enzymatic degradation. At the same time L2 enhances the rate of spontaneous hydrolysis of the ester bonds between terminal riboses and amino acyl moieties of these two peptidyl-tRNA analogues. L2 has, however, only a slight effect on the rate of spontaneous deacylation of aminoacyl-tRNAs. We suggest that the role of L2 is in the fixation of the aminoacyl stem of tRNA to the ribosome at its P-site, and speculate that this protein is directly involved in the peptidyl transferase (PT) reaction.

Bacterial Proteins↗
PubMed1984

Ribosomal protein L16 binds to the 3'-end of transfer RNA.

Escherichia coli 50 S ribosomal subunits were reconstituted with and without protein L16 present. The latter particles, although active in puromycin reaction, were unable to use CACCA-Phe as an acceptor substrate. We also found that L16 interacts directly with this oligonucleotide and, in the complex with tRNA, protects its 3'-end from pancreatic ribonuclease digestion. We suggest that the role of L16 is in the fixation of the aminoacyl stem of tRNA to the ribosome at its A-site.

Binding Sites↗
PubMed1984

The force of measles infection in East Africa.

Catalytic models were applied to age-specific incidence data from two East African studies in order to study the force of measles infection in relation to age. The results are compared with the pattern observed in England and Wales. In East Africa the force of measles infection appears to be independent of age, probably as a result of sociocultural factors. Consequently the incidence of measles is highest in the second half of the first year of life and decreases with increasing age. Major vaccination efforts will raise the average age of measles attack, but the peak incidence will remain in the first year of life. This complicates the decision on the optimal age for vaccination and the need for incidence surveillance is stressed. The simple catalytic model, which is based on the assumption of an age-independent force of infection may play an important role in measles surveillance. With this model simple and economic surveillance studies could be designed which use cross-sectional data only.

Age Factors↗
PubMed1983

The interaction of ribosomal protein L16 and its fragments with tRNA.

Two large proteolytic fragments of Escherichia coli 50 S ribosomal subunit protein L16 were generated by limited hydrolysis with chymotrypsin (missing 9 N-terminal amino acids) and trypsin (missing 16 N-terminal amino acids). It was found that while intact L16 and its chymotryptic fragment both interact with tRNA (Kd = 5.4 x 10(-7) M), the tryptic fragment does not. These results are interpreted in terms of possible significance of the residues 10-16 in the peptidyl transferase activity.

Electrophoresis, Polyacrylamide Gel↗
PubMed1978

Hairy cell leukaemia. Clinical features and effect of splenectomy.

Hairy-cell leukaemia (leukaemic reticuloendotheliosis) is a well-defined clinical entity. Most of the recent reports are almost entirely concerned with the pathological and functional aspects of the disease. In the present retrospective study the clinical features and laboratory data of 12 patients were analyzed together with a series of 123 adequately clinically documented cases from the literature. The Hb level and the sex of the patient proved to be the only parameters having some prognostic value for the survival time after diagnosis. The effect of splenectomy was assessed in two comparable groups of 24 splenectomized and 51 non-splenectomized patients. The operation seemed to be beneficial, but after 2 years the difference was not significant(.05 less than P less than .10). Analysis of subgroups showed that splenectomy was definitely beneficial in women, in patients with a Hb level over 8.0 g/dl or a platelet level above 50 X 10(9)/1, in patients with leucocytes below 3 X 10(9/1, , and also in patients with hepatomegaly (P less than .05 in all cases). These findings suggest that splenectomy is beneficial in cases where anaemia and thrombocytopenia are not very severe; in severe cytopenia the operation does not increase the life expectancy.

Adult↗
PubMedDate not supplied

Changes in ocular onchocerciasis four and twelve months after community-based treatment with ivermectin in a holoendemic onchocerciasis focus.

The impact of ivermectin mass treatment on ocular onchocerciasis was studied in a holoendemic focus of blinding onchocerciasis in Ghana. A cohort of 417 persons, 369 of whom were treated, was followed up at 4 and 12 months after treatment. The mean ocular microfilarial load in the anterior chamber of the eye and in the cornea of treated persons was reduced to less than 20% and 10% of the pretreatment levels respectively at the 4 months follow-up but had increased significantly by 12 months. Lesions of the eye at the advanced stage of development remained stable. There was significant regression of early lesions of the anterior segment of the eye, particularly iridocyclitis, after ivermectin treatment. In view of the substantial increase of ocular microfilarial loads after 12 months, 6-monthly treatment may be indicated in such highly endemic foci. However, long-term observation is needed to give a correct estimate of the full benefit to be derived from mass treatment with ivermectin.

Adolescent↗
PubMedDate not supplied

Changes in ocular onchocerciasis after two rounds of community-based ivermectin treatment in a holo-endemic onchocerciasis focus.

In a longitudinal study to determine the effect of annual community-based treatment of ocular onchocerciasis with ivermectin, the population living in the 3 most affected villages in the holo-endemic onchocerciasis focus of Asubende in Ghana were re-examined 16 and 24 months after initiating treatment. Ocular microfilarial loads had decreased to very low levels in nearly all of the 334 examined persons who were treated twice. Only very few subjects had ocular loads of 32 microfilariae or more in the anterior chamber of the eye, but this was not associated with deterioration of ocular lesions. Important regression of both early and advanced lesions of the anterior segment of the eye was observed, which was highly statistically significant with respect to iridocyclitis. Lesions of the posterior segment of the eye remained stable. Though no systematic change in the visual acuity of the population was observed, 3 new cases of blindness occurred in persons who already had eye lesions at such an advanced stage that ivermectin treatment could no longer affect the outcome. The results suggest that annual ivermectin treatment is adequate to control onchocercal ocular disease even in populations with very high endemicity levels.

Adolescent↗
PubMedDate not supplied

Onchocerciasis infection in children born during 14 years of Simulium control in West Africa.

The incidence of onchocerciasis infection in children born since the start of vector control is one of the indicators used in the epidemiological evaluation of the Onchocerciasis Control Programme in West Africa (OCP). Though initially of littel value, after a decade of control it has become a sensitive indicator of residual transmission. The results of 14 years of control are reported. In 179 villages parasitological surveys were undertaken at intervals of 3-4 years. 15,286 children were examined and 110 were found to be infected, compared to an expected number of 2467 infected had there been no control. There was considerable geographical variation in the results. In the large central OCP area the results were excellent. Of 12,172 children examined in 127 villages, only 23 were found to be infected compared to an expected number of 1960 without control. This suggests that larviciding had achieved a 99% reduction in the incidence of infection in children. Additional surveys in 2 foci in the central OCP area where transmission had relapsed showed that these problems were very localized. Most villages with infected children were found in OCP border areas in the east and west, which had been reinvaded by infective vectors from elsewhere, and in the intermediate area between forest and savanna in Côte d'Ivoire where there had been partial control failures because of resistance. The incidence of infection in children was reduced by an estimated 68% in the eastern reinvaded area, by 87% in the western reinvaded area, and by 84% in the intermediate area.

Adolescent↗