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Biomedical subjects

M Tanner

Publications and source records attributed to M Tanner.

At least 199 records · Page 11Linked to original sources
PubMed1994

Screening Tanzanian medicinal plants for antimalarial activity.

Forty-three different plant species commonly used in traditional medicine for the treatment of malaria were selected and screened for their antimalarial activity against Plasmodium falciparum in vitro. Thirteen of the 43 species were obtained directly from traditional healers who use these plants for the treatment of malaria. The other plant species were collected on the basis of ethnomedicinal information in the literature. The plant material was collected from Morogoro, Dar es Salaam and Kagera regions in Tanzania. Fifty-eight plant samples from these 43 plant species, including leaves, roots and stem bark, were investigated. Apart from the crude EtOH extracts, petroleum ether (PE), ethyl acetate (EtAc) and H2O fractions of these extracts were also tested. The in vitro testing revealed that 37% of the investigated plants showed strong antimalarial activity with IC50 values below 10 micrograms/ml. The four most active plants included Cissampelos mucronata, Maytenus senegalensis, Salacia madagascariensis and Zanthoxylum chalybeum.

Animals↗
PubMed1994

A trial of the synthetic malaria vaccine SPf66 in Tanzania: rationale and design.

The development of a safe, affordable and effective malaria vaccine to form part of control schemes in malaria endemic countries is a priority for researchers and public health officials. SPf66 is the first malaria vaccine to have shown partial protection against natural challenge in a phase III trial carried out in a hypoendemic area of Colombia. This paper describes the rationale and design of the first field trial of SPf66 outside South America, and the first to be conducted in an area of high perennial transmission.

Adult↗
PubMed1994

Controlling schistosomiasis: the cost-effectiveness of alternative delivery strategies.

Sustainable schistosomiasis control cannot be based on large-scale vertical treatment strategies in most endemic countries, yet little is known about the costs and effectiveness of more affordable options. This paper presents calculations of the cost-effectiveness of two forms of chemotherapy targeted at school-children and compares them with chemotherapy integrated into the routine activities of the primary health care system. The focus is on Schistosoma haematobium. Economic and epidemiological data are taken from the Kilombero District of Tanzania. The paper also develops a framework for possible use by programme managers to evaluate similar options in different epidemiological settings. The results suggest that all three options are more affordable and sustainable than the vertical strategies for which cost data are available in the literature. Passive testing and treatment through primary health facilities proved the most effective and cost-effective option given the screening and compliance rates observed in the Kilombero District.

Child↗
PubMed1994

Molecular cytogenetics of human breast cancer.

Our studies of human breast cancer using CGH and FISH with precisely mapped probes have revealed a surprising amount of intratumor and intertumor heterogeneity in human breast cancers. However, some regions of abnormal copy number are found frequently. We believe that the regions of frequent abnormality harbor novel cancer genes, and that identification of these is important for diagnosis, prognostication, and the development of new therapies.

Breast Neoplasms↗
PubMed1994

Do high levels of C-reactive protein in Tanzanian children indicate malaria morbidity.

Children under 6 years of age living in an area of Tanzania highly endemic for malaria were tested for C-reactive protein (CRP) in order to determine how the acute-phase response is related to malaria in children of different ages and to investigate whether serum CRP concentrations might be useful in the qualification of morbidity in such children. The median CRP level in the 629 finger-prick blood samples measured, 6.0 mg/liter, was much higher than that reported in the blood of children in Europe. The CRP concentration was correlated with recent illness reported by the parents. High CRP levels were most strongly associated with Plasmodium falciparum parasitemia in children under 1 year of age. In older children, lower levels of CRP were associated with parasitemia, and fewer children had increased CRP levels attributable to parasitemia. The levels of malaria-attributable CRP appear to track the acquisition of parasitological and clinical tolerance in this area with very high levels of P. falciparum transmission. Determination of CRP levels should be useful in the rapid assessment of the overall burden of morbidity, especially in infants. In areas where malaria is endemic, CRP associated with increased parasite densities provides an objective measure of malaria-specific morbidity. This would be an efficient approach to estimating malaria morbidity risks from small-scale serological surveys.

Animals↗
PubMed1994

Apical acidification induces paracellular injury in canine gastric mucosal monolayers.

We used primary monolayer cultures of enzyme-dispersed canine oxyntic mucosal cells mounted in Ussing chambers to characterize the apical barrier to H+. [3H]mannitol flux (MF) and [14C]inulin flux (IF) were used as size probes for tight junctions. Apical H+ produced a three-phase effect. In phase 1, as the apical pH was decreased from 7 to about 2.5, resistance (R) increased, but short-circuit current (Isc) did not change. In phase 2, an increased paracellular permeability developed at pH below 2.5-1.7, evidenced by decreased R and increased MF but not IF. Size sieving and monolayer integrity were preserved, and this paracellular leak was either fully reversed or stabilized by apical neutralization, depending on the duration of the paracellular leak. In phase 3, after sustained exposure to an apical pH below approximately 2, transepithelial integrity was lost; R decreased to fluid R, and both MF and IF increased. Basolateral acidification below pH 5.5 produced rapid monolayer disruption. Low concentrations of cytochalasin D (CD) decreased R and increased MF but not IF; apical acidification to pH 4 after CD increased R and decreased the MF, indicating reduced paracellular permeability by apical H+. Apical amiloride did not alter Isc; however, after 48 h of treatment with hydrocortisone and insulin, an amiloride-sensitive Isc component became evident. Our data indicate that the increase in R observed with apical acidification reflects decreased paracellular permeability and that the earliest injury with apical acidification is a selective paracellular leak.

Animals↗
PubMed1994

Who are the other players in the health reform proposal game?

The debate over health care reform is not just about details. It is also about power and the role of government. The type of health care reform that passes will determine whether, and to what degree, one seventh of the U.S. economy will be controlled by government. And, it will determine to what degree some of our most personal and private decisions are controlled by government. This is not an issue where compromises should come lightly. Certainly, they should not come preemptively.

Health Benefit Plans, Employee↗
PubMed1993

The effects of house spraying with DDT or lambda-cyhalothrin against Anopheles arabiensis on measures of malarial morbidity in children in Tanzania.

The effects of house spraying of DDT and lambda-cyhalothrin against populations of Anopheles arabiensis were assessed in children aged between 1 and 10 years with regard to fever episodes and parasite prevalences. DDT and lambda-cyhalothrin treatment did not reduce the prevalence of malaria episodes as defined by fever (temperatures > or = 37.4 degrees C and/or fever reported) combined with high parasitaemia (> or = 100 parasites/200 leucocytes). However, the prevalence of malaria parasitaemia, of the episodes of fever with any level of malaria parasitaemia and of high parasitaemia alone were significantly reduced. Furthermore, the reduction in mean parasite densities was greater in children of the 1-2 years age group for both insecticides and also for children of 3-5 years age group with lambda-cyhalothrin. Measured and/or reported fever and high parasitaemia were correlated and the data indicated that most of the fevers in these children could be attributed to malaria. Using this criterion it is concluded that the population of An. arabiensis responded to both DDT and lambda-cyhalothrin house spraying which in turn also reduced malaria-related morbidity.

Age Factors↗
PubMed1993

Absence of seasonal variation in malaria parasitaemia in an area of intense seasonal transmission.

Parasitological surveys carried out in two villages of the Kilombero district of Tanzania indicated a very high prevalence of Plasmodium falciparum parasitaemia throughout the year (all ages mean prevalence = 69.2%) and a low, unstable prevalence of P. malariae (all ages mean prevalence = 4.5%). Fevers (temperature > or = 37.5 degrees C) in both children and adults showed irregular changes in prevalence over time, but there was no seasonal pattern. Neither was there seasonal variation in either P. falciparum parasite prevalence or parasite densities. This was despite marked seasonality in vectors caught in CDC light-traps and in estimated sporozoite inoculations determined by ELISA. The estimated mean annual inoculation rate was extremely high, over 300 infectious bites per person per year, the main vectors being members of the A. gambiae complex and Anopheles funestus. There was considerable variation between houses but even in houses with relatively low mosquito numbers the inoculation rate was sufficient to maintain a maximal P. falciparum prevalence. Heterogeneities in exposure cannot explain why the parasite prevalence is not always 100%. In areas of such high transmission, parasitaemias are likely to be determined mainly by the interaction of schizogony and anti-blood stage immunity, since parasites arising from new inoculations generally comprise only a small proportion of the total in the circulation. In any one individual, this will lead to periodic fluctuations in levels of parasitaemia. These are unlikely to show a close relationship to either seasonal variation in inoculations or to differences between households in the local inoculation rate.

Adolescent↗
PubMed1993

Endogenous somatostatin inhibits histamine release from canine gastric mucosal cells in primary culture.

The effects of somatostatin on histamine release were studied using primary cultures of canine oxyntic mucosal cells in which mast cell content was reduced by density gradient. The S6 monoclonal antibody to somatostatin, but not control antibodies, enhanced gastrin-stimulated histamine release. In the presence of S6, the somatostatin analogue SMS-201-995 (10(-7) M) inhibited gastrin-stimulated histamine release by 95%. The dose producing 50% inhibition for this inhibition was approximately 3 x 10(-10) M and was completely reversed by pertussis toxin treatment. In contrast to somatostatin, epinephrine failed to inhibit this gastrin stimulation. However, the lectin concanavalin A (ConA) also stimulated histamine release from these cultures, and this response was inhibited by epinephrine but not by somatostatin. Thus somatostatin selectively inhibited the gastrin-responsive histamine pool, which presumably is stored in oxyntic mucosal endocrine cells. In contrast, epinephrine selectively inhibits histamine release from the ConA-sensitive pool, which is presumably stored in mast cells. Furthermore, enhancement of gastrin-stimulated histamine release by immunoneutralization of somatostatin indicates an important role for endogenous somatostatin as a paracrine inhibitor of non-mast cell histamine release.

Animals↗
PubMed1992

A review of the literature on the use of ultrasonography in schistosomiasis with special reference to its use in field studies. 1. Schistosoma haematobium.

This review presents an outline of the pathology resulting from Schistosoma haematobium infections, and the ways in which the lesions can be investigated. The use of ultrasonography is covered in detail. Ultrasonography can provide direct information about lesions in internal organs, and thus provide information about patterns of morbidity and about the regression of pathological changes after treatment. The method has the advantages that it is non-invasive, and is also relatively inexpensive and can be used under field conditions. Ultrasonography has already been used in a number of epidemiological studies in areas where S. haematobium is endemic. The method has proved to be feasible and useful. However, the methodology used for ultrasound studies has varied considerably, so that it is difficult to make valid comparisons between results obtained in different places or at different times. A standardized methodology for making observations and recording the results is needed if the full potential benefit of using ultrasound in the monitoring of schistosomiasis control projects is to be realised. The correlation of results obtained using ultrasound with the results of clinical, parasitological and other observations has been investigated in a number of studies, but many questions remain to be answered.

Confounding Factors, Epidemiologic↗
PubMed1992

A review of the literature on the use of ultrasonography in schistosomiasis with special reference to its use in field studies. 2. Schistosoma mansoni.

This review presents an outline of the pathology resulting from Schistosoma mansoni infections, and the ways in which it can be investigated. The use of ultrasonography is covered in detail. Ultrasonography can provide direct information about lesions in internal organs, and thus provide information about patterns of morbidity and about the regression of pathological changes after treatment. The method is non-invasive, and can be used under field conditions. Ultrasonography is valuable for the study of hepatosplenic pathology, to detect lesions such as the development of periportal fibrosis and the enlargement of the portal vein, which can indicate the development of portal hypertension. This may lead to a severe outcome, including bleeding from oesophageal varices, which is a principal cause of death from S. mansoni infection. A problem with the use of ultrasonography is that the mild lesions likely to be observed in population surveys are not always easy to assess. Ultrasonography has already been used in a number of epidemiological studies of S. mansoni infection, and has proved to be feasible and useful. However, the methodology used for ultrasound studies has varied considerably, so that it is difficult to make valid comparisons between results obtained in different places or at different times. A standardized methodology for making observations and recording the results is needed if the full potential benefit of using ultrasound in the monitoring of schistosomiasis control projects is to be realised.

Diagnosis, Differential↗