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At least 379 records · Page 21Linked to original sources
PubMed1987

Bancroftian filariasis in coastal north Trinidad: the effects of mass chemotherapy using spaced doses of diethylcarbamazine citrate on human microfilaraemias and vector infection rates.

The effects of a mass chemotherapy programme using spaced doses of diethylcarbamazine citrate on Wuchereria bancrofti microfilaraemias and vector infection rates were studied in an isolated rural community of 650 people in north Trinidad where a microfilaria rate of 15% had previously been recorded. A single oral dose of 6 mg/kg body weight was given at monthly intervals for one year. After 6 months, 79% (52/66) of persons previously microfilaraemic had become negative. After 12 months the negative proportion had increased to 90% (63/70). The geometric mean microfilaria density of those still microfilaraemic was reduced from 19.7 to 4.6 per 100 mm3 of blood. Of 147 initially negative persons, none had become positive following treatment. Filarial infection rates in Culex quinquefasciatus from randomly sampled houses fell from 6.4% to zero; in houses where occupants with microfilaraemia had been identified before treatment, the rate was reduced from 15.8% to zero. In a supplementary study, however, weekly collections from one initially positive house showed a rapid decline in the vector infection rate from 43% to 2% after three months but an additional 3 months elapsed before the index reached zero. There was negligible microfilarial uptake by the vectors from residual low-density microfilaraemias (less than 10 microfilariae per 100 mm3 of blood) after chemotherapy.

Animals↗
PubMedDate not supplied

Immunoaffinity purification of the neuropeptide prothoracicotropic hormone from Manduca sexta.

The prothoracicotropic hormones (PTTH) are cerebral peptides that control insect postembryonic development by stimulating the prothoracic glands to synthesize ecdysteroids. Using immunoaffinity chromatography and SDS-PAGE, a 25.5 kDa big PTTH has been purified from Manduca sexta. Based upon SDS-PAGE and Western blot analysis, the native form of big PTTH appears to be a dimer with monomers of 16.5 kDa. Four HPLC-separated fragments of this acidic peptide were sequenced and exhibited no sequence similarity with Bombyx mori PTTH. In agreement with this finding, the basic Bombyx PTTH had no PTTH bioactivity in Manduca. One sequenced fragment of the Manduca PTTH is approximately 70% similar to the vertebrate cellular retinoid binding proteins, suggesting these binding proteins may be present in insects.

Amino Acid Sequence↗
PubMed1989

Maserlike nonlinear scatter from human breath, a surface-enhanced far infrared scatter effect.

A cotton tip applicator was utilized to stimulate far IR scatter (emission) from human breath. The reticulated cotton tip was vibrated at 200 Hz, the acoustic frequency that matches the average vibration frequency of common species of mosquitoes. Mosquitoes have open resonator dielectric sensillae (spines) on their antenna that match the 643 cm-1 (15.5) Cabannes line in the 667 cm-1 region of CO2 rotation line, acoustic Stokes Brillouin and Stokes Raman lines are noted. Implications of such maserlike (coherent or partial coherent) scatter lines to insect control and disease diagnostics are discussed.

Animals↗
PubMed1995

Pyrethroids, nerve poisons: how their risks to human health should be assessed.

The extensive worldwide efforts of structural modification of natural pyrethrins for better performances have resulted in successful development of a wide variety of synthetic pyrethroids with tremendously high efficacy, knock-down activity or vapor action, and/or with acceptable environmental stability and safety. Currently these pyrethroids including their preferentially manufactured stereoisomers are widely used in agriculture, and for public health as well as household insect control. The detailed toxicology and metabolism studies intended to attain human risk assessment have revealed that with voltage-dependent sodium channel as target site pyrethroids induce pronounced repetitive activity characterized grossly by tremor, hypersensitivity, choleoathetosis, and salivation. In addition, so-called cyano-pyrethroids cause transient skin paresthesia in workers. With regard to tumorigenicity, mutagenicity, teratogenicity and developmental toxicity, no significant findings have been reported. Pyrethroids are eliminated from the animals quite rapidly and completely, undergoing oxidation and ester hydrolysis followed by various conjugations, with low tissue residues. Thus, overall, sound scientific bases exist for human risk assessment under the present usage conditions.

Animals↗
PubMed1990

A survey of medicinal plants of minas gerais. Brazil.

A list of fifty-two plant species used for medicinal purposes or to control arthropods by peasants near Belo Horizonte, Minas Gerais (Brazil) has been compiled. Preparation procedures are also noted. The use of plants for controlling insects and to heal a condition known as "ferida brava" is discussed. The role of indigenous plant remedies within the local health care system is worthy of a closer investigation.

Botany↗
PubMed1994

Linkage of kdr-type resistance and the para-homologous sodium channel gene in German cockroaches (Blattella germanica).

Pyrethroids are an important class of insecticides for controlling insect pests, including the German cockroach. Unfortunately, many insects have developed resistance to pyrethroids. One of the most important mechanisms of resistance is kdr (knockdown resistance) which is characterized by neural insensitivity to pyrethroids and DDT. To investigate whether the voltage-dependent sodium channel is involved in kdr-type resistance in the German cockroach, we isolated a 120 bp DNA fragment of the para-homologous sodium channel gene from German cockroaches. Using this fragment as a probe, we identified a restriction fragment length polymorphism (RFLP) of the para-homologous sodium channel gene between susceptible and kdr-type resistant German cockroaches. RFLP analysis of F2 and backcross cockroach populations (total of 331 individuals) showed that all homozygous resistant individuals had a 3.7 kb EcoRI fragment, all homozygous susceptible individuals had a 3.0 kb EcoRI fragment, and all heterozygous individuals had both 3.7 and 3.0 kb fragments. No recombination was detected between the kdr-type resistance locus and the para-homologous sodium channel gene. This suggests that the kdr-type resistance locus and para-homologous sodium channel gene are identical or tightly linked (< 0.2 cM) in German cockroaches. Our results provide strong evidence that modification of para-homologous sodium channels is associated with kdr-type resistance.

Amino Acid Sequence↗