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Biomedical subjects

M Warren

Publications and source records attributed to M Warren.

At least 73 records · Page 4Linked to original sources
PubMed1985

Assessment of exposure to organophosphate insecticides during spraying in Haiti: monitoring of urinary metabolites and blood cholinesterase levels.

Measurement of blood cholinesterase activity and of the urinary metabolites of fenitrothion (p-nitrocresol) and malathion (monocarboxylic acid) was used to assess the exposure to these insecticides of workers in the Haitian malaria control programme and of residents in the sprayed houses. Cholinesterase activity was significantly reduced at the end of the working week in 3 out of 28 fenitrothion workers. Urinary levels of p-nitrocresol (PNC) in the spraymen ranged from 2.2 to 25.2 mg/l. In fenitrothion workers who had no direct contact with spraying (weighers and supervisors), the cholinesterase activity remained >/= 75% of the normal control value, and the urinary PNC levels were relatively low. Urinary malathion monocarboxylic acid (MCA) levels at the end of the working week ranged between 1.1 and 5.3 mg/l in workers using malathion and their blood cholinesterase activity remained essentially normal. In both groups of workers the cholinesterase levels improved and the urinary excretion of metabolites decreased after 2 days of rest from the spraying operations. In the residents of the sprayed houses, low concentrations of PNC and MCA were detected in the urine 1 day after spraying and measurable but reduced levels were still present after 7 days. In all these cases the cholinesterase activity remained >/= 75% of the normal control value.

Carboxylic Acids↗
PubMed1985

Infectivity of two strains of Plasmodium vivax to Anopheles albitarsis mosquitoes from Colombia.

Anopheles albitarsis obtained from Villavicencio, Colombia, were colonized in the laboratory using force-mating techniques. Laboratory reared mosquitoes were allowed to feed on Aotus monkeys infected with the Salvador II or the Rio Meta strains of Plasmodium vivax from El Salvador and Colombia, respectively. In comparison with other species, the An. albitarsis were less susceptible than Anopheles freeborni, Anopheles culicifacies and strains of Anopheles albimanus from El Salvador, Panama and Colombia and more susceptible than a strain of An. albimanus from Haiti.

Animals↗
PubMed1984

Two case reports of trazodone-induced mania.

Two unipolar depressed patients developed manic symptoms when treated with trazodone. The symptoms resolved when the drug was discontinued. The authors believe these to be the first two cases of such a reaction reported in the literature.

Adult↗
PubMed1983

Cardiovascular responses in rats with glycerol-induced acute renal failure.

Autonomic and cardiovascular function were assessed in rats with glycerol-induced acute renal failure (ARF). Rats with ARF had significantly lower mean arterial blood pressure and heart rates and significantly elevated plasma noradrenaline concentrations. The chronotropic responses to right cervical sympathetic and vagal stimulation were diminished in rats with ARF. The pressor and depressor responses to noradrenaline and nitroprusside respectively when expressed as a change in mmHg pressure were significantly reduced in rats with ARF when compared to controls. However, when the depressor responses to nitroprusside were expressed as a percentage fall in basal mean arterial pressure, with the exception of the response to a dose of 10 micrograms kg-1, there were no significant differences between control and uraemic rats. The present findings show that in the rat, changes in cardiovascular responsiveness occur after a brief period of uraemia which are similar to those observed in patients and rats with chronic renal failure.

Acute Kidney Injury↗
PubMed1983

Observations on the infectivity of two strains of Plasmodium vivax from Vietnamese refugees to Aotus monkeys and anopheline mosquitoes.

Two strains of Plasmodium vivax (NAM and ONG) were isolated from Vietnamese refugees and established in splenectomized Aotus monkeys from Colombia and Bolivia. Mosquito infections were readily obtained from animals with no prior malarial experience or with a history of infection with P. falciparum only. Those animals with previous infections with P. vivax supported only low parasitemias, and the mosquito infections were minimal. Complete development of the sporogonic cycle was obtained with all species of mosquitoes tested. The most susceptible mosquito was An. dirus. Other mosquitoes readily infected with these strains were An. culicifacies, An. maculatus, An. gambiae, An. stephensi, and the two North American species, An. freeborni and An. quadrimaculatus. Transmission from one monkey to another was obtained via the bites of infected An. dirus, An. stephensi, and An. maculatus mosquitoes.

Animals↗
PubMed1983

The seroepidemiology of malaria in Middle America. V. Antibody responses in an indicator population from an endemic area with attack phase antimalaria activities.

Serologic assessment was carried out in a sample of the population living in an area endemic for malaria in which control measures were being applied. The study area was in El Salvador, Central America, and antimalarial activities consisted of the residual application of the pesticide, propoxur, and drug distribution through a combination of active and passive case detection. Indirect fluorescent antibody (IFA) responses to Plasmodium vivax and P. falciparum antigens were determined on four occasions, at approximately 6-month intervals. The study population consisted of one resident from each of 268 widely distributed houses. Each person was treated with a curative course of chloroquine and primaquine at the beginning of the investigation. An increase in the proportion of positive IFA responses (greater than or equal to 1:20) and an increasing number of serologic conversions (i.e., from negative to positive or a 2-fold increase in titer) during the course of the 18-month study confirmed continued transmission of malaria. The presence of parasites in some individuals without associated serologic changes is discussed.

Antibodies↗
PubMed1982

Observations on two strains of plasmodium falciparum from Haiti in Aotus monkeys.

Two strains of Plasmodium falciparum originating in Haiti were studied in the Aotus monkey. The Haitian I/CDC strain was first adapted to in vitro cultivation and subsequently inoculated into monkeys. The Haitian III/CDC strain was inoculated directly from a human patient into the Aotus monkey. The strains varied in their levels of pathogenicity to the animals. The Haitian I/CDC strain was highly virulent in six splenectomized animals; in one intact animal, the infection could be controlled but not eliminated with periodic doses of quinine and chloroquine. After subsequent splenectomy, the animal developed high parasitemias and died. No gametocytes developed in any of the Haitian I infections. The Haitian III strain was lethal to five of the 14 splenectomized monkeys inoculated, but some were able to control their infections without drug intervention. Gametocytes developed in all infections that persisted for an adequate length of time, and infections of mosquitoes were obtained both during the primary attack and the first recrudescence of the parasitemia. Of the mosquitoes tested, Anopheles freeborni was most susceptible to infection, followed by An. culicifacies, An. dirus, An. maculatus, and An. albimanus. The Haitian III strain was successfully transmitted to four other splenectomized Aotus monkeys via sporozoite inoculation using An. freeborni.

Animals↗
PubMed1981

Experimental Babesia microti infections in Macaca mulatta: recurrent parasitemia before and after splenectomy.

To learn more about the course of Babesia microti infections in primates, six Macaca mulatta monkeys with blood-induced B. microti infections were followed for 270 days with regular thick blood smears. Three of the monkeys experienced from 1--3 recurrences of parasitemia defined here as greater than or equal to 200 organisms/mm3 blood. Following splenectomy on day 297, parasitemia recurred in all animals, reaching levels of 1.9 x 10(5) to 2.7 x 10(6) organisms/mm3, and was associated with a moderately severe hemolytic anemia. These findings suggest that similar recurrences of parasitemia may occur in human cases, and that splenectomy may present a risk to persons with a past history of B. microti infection.

Animals↗
PubMed1981

The 48-hour exoerythrocytic stage of Plasmodium cynomolgi bastianellii.

Detection and specific identification of the 48-hour exoerythrocytic stage of the primate malaria parasite, Plasmodium cynomolgi bastianellii, was accomplished by means of a highly specific indirect immunofluorescence technique (IFA) applied to hepatic tissue fixed in Carnoy's solution. The 48-hour forms appeared as round-to-slightly-oval bodies of average mean diameter 3.0 micrometers (9 parasites) and lying with the cytoplasm of individual hepatic parenchymal cells; each possessed one to three non-fluorescent nuclei or nuclear sections (mean 1.6) within the brightly fluorescent parasitic cytoplasm. In contrast, 72-hour parasites (6) had an average mean diameter of 4.0 micrometers and a mean of 2.2 nuclei. Restaining of IFA preparations with the Giemsa-colophonium method confirmed the plasmodial nature of fluorescent forms, despite some modification of staining characteristics produced by the prolonged exposure of sections to the aqueous phase of the IFA procedure. Exoerythrocytic forms could not be detected in biopsies obtained 24 hours following sporozoite inoculation.

Animals↗
PubMed1981

Tick transmission of Babesia microti to rhesus monkeys (Macaca mulatta).

To determine whether Ixodes dammini is capable of transmitting Babesia microti to primates, infected nymphal ticks were allowed to feed on five Macaca mulatta. The monkeys were then followed for at least 60 days with daily thick blood smears for evidence of infection. Patent B. microti parasitemia developed in four of the five animals. Prepatent periods were 13, 18, 20, and 28 days. Maximum parasitemia ranged from 83 to 7,068 organisms/mm3 blood. Splenectomy 15-17 months after exposure to ticks results in recurrences of parasitemia in three of the four infected monkeys.

Animals↗
PubMed1981

The enzyme-linked immunosorbent assay (ELISA) for malaria. III. Antibody response in documented Plasmodium falciparum infections.

Serum specimens from patients in El Salvador, Central America, with slide-proven Plasmodium falciparum infections were examined for antibodies to P. falciparum using the enzyme-linked immunosorbent assay (ELISA) and the indirect fluorescent antibody (IFA) methods. Both serologic tests were positive in 78.1% of the 827 samples, both negative in 5.4%, the ELISA positive alone in 6.3%, and the IFA alone in 10.2%. Agreement between the serologic tests was better in the specimens with high positive titers (high IFA = high ELISA). Seropositivity rates and geometric mean titers were higher in the older (greater than or equal to 15 years) age groups for both ELISA and IFA; in such persons, the IFA was positive in 92% and the ELISA in 88%. The lowest seropositivity rates found by the ELISA were observed in children; 27.6% of 98 children less than or equal to 4 years of age were negative. A longer duration of infection as evidenced by the presence of gametocytes on the blood slide resulted in higher positivity rates by both ELISA and IFA. This phenomenon, particularly apparent in young children, supports the belief that the more important variable in determining the proportion of false negatives is previous malaria experience and not age. The results indicate that, while neither serologic test is appropriate as a diagnostic aid, both the ELISA and the IFA would be useful in epidemiologic investigations.

Adolescent↗
PubMed1981

Relationship of constructional apraxia and body scheme disorders in dressing performance in adult CVA.

The relationship between constructional apraxia and body scheme disorders and failure of post-cerebral vascular accident (CVA) patients to achieve independence in upper extremity dressing was investigatged in this study. One hundred and one subjects with right- and left-CVA were given tests that measured body scheme dysfunction and constructional apraxia on admission to an inpatient rehabilitation unit, and then rated on upper extremity dressing performance at discharge. Scores on the apraxia and body scheme tests were statistically correlated with dressing performance. The results indicated that both constructional apraxia and body scheme dysfunction contribute to failure in achieving upper exremity dressing, but that body scheme performance is a better predictor of dressing ability. In addition, the presence of visual field deficits, medical complications, and aphasia were found to exert significant influence on subject performance.

Activities of Daily Living↗
PubMed1980

Anopheles pseudopunctipennis: laboratory maintenance and malaria susceptibility of a strain from El Salvador.

The techniques involved in the establishment of a strain of Anopheles pseudopunctipennis pseudopunctipennis from El Salvador, Central America are presented. Results of experimental susceptibility studies using coindigenous strains of Plasmodium falciparum and P. vivax as well as P. vivax from Colombia indicated that this anopheline strain does not possess the biologic capability for malaria transmission. The usefulness of biological susceptibility data in establishing the vector status of anophelines, especially in areas with multiple species as potential vectors, is discussed.

Animals↗