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Biomedical subjects

C Villarreal

Publications and source records attributed to C Villarreal.

24 records · Page 2Linked to original sources
PubMed1992

Gonotrophic cycle and survivorship of Anopheles albimanus (Diptera: Culicidae) in southern Mexico.

The length of the gonotrophic cycle of Anopheles albimanus was estimated by 12 mark-release-recapture studies conducted in corrals in southern Mexico from 1987 to 1990. The initial set of three mark-release studies indicated that the gonotrophic cycle takes at least 4 d based on the day when gravid mosquitoes were first recaptured. However, in later experiments, mosquitoes recaptured seeking hosts at 48 h after release were in Sella's and Christophers' stages I and II, but parity rates had nearly doubled, indicating that eggs may have developed in less than 48 h and that mosquitoes returned to refeed immediately following oviposition. Two gonotrophic cycles probably exist, one of 48 h dominated by parous mosquitoes and one of 4 d comprised of nulliparous, pregravid mosquitoes. Daily survivorship was estimated by regression from the decrease in the daily recapture rate (0.46-0.68) was less than that estimated by the parity rates (0.67-0.69), with no important differences found between wet and dry seasons. Estimates of the probability of a mosquito living long enough to transmit malaria were 2% (range, 1.8-2.5%).

Animals↗
PubMed1992

Tests for the existence of genetic determination or conditioning in host selection by Anopheles albimanus (Diptera: Culicidae).

The existence of sympatric populations within Anopheles albimanus Wiedemann with specific host preferences and the question of whether host selection has a genetic basis or is a learned characteristic were investigated. Progeny of wild females collected from corrals or human bait were reared in an insectary. F1 females were fed on a cow or on a human host, allowed to oviposit, and then were released in an experimental hut divided into three compartments. The side rooms occupied by two human or one calf baits were connected by a "funnel-like" cone with the central room in which mosquitoes were released. Females were released at 2000 hours and recaptured the next morning at 0600 hours. A fixed proportion of mosquitoes selected either host (approximately 65% cow and 35% human), irrespective of their parental origin or source of the first blood meal. The data indicate that the existence of cryptic populations with anthropophilic habits is unlikely and that a "learned" host selection also may be ruled out.

Animals↗
PubMedDate not supplied

Much ado about nothing: methicillin-resistant Staphylococcus aureus.

The pathogenic methicillin-resistant Staphylococcus aureus (MRSA) has received a voluminous amount of notoriety. The four major reasons are its morbidity, mortality rate, cost of treatment, and constant appearance in intensive care units. Both Staphylococcus aureus and S. epidermidis (MRSE) account for 82% of our gram-positive wound isolates, whereas the gram-negative account for 34% of all isolates. Therefore we compared the morbidity, mortality rate, and cost factors related to MRSA-MRSE and gram-negative infections for a 4-year period, assessing more than 214 documented infections. Morbidity and mortality rates were minor for MRSA. Pseudomonas aeruginosa and Escherichia coli accounted for 57.5% of the total gram-negative isolates. Gram-negative antimicrobial therapy usually requires two therapeutic drugs, which increases morbidity and costs, whereas the staphylococci usually can be treated by one antimicrobial. During this period there were 47 gram-negative infections requiring 10 to 15 additional days of hospital stay, with a daily antibiotic cost of $293.40. Costs for MRSA or MRSE are 28% less. Therefore our preoccupation with MRSA or MRSE infections is unwarranted and unsubstantiated.

Adolescent↗
PubMedDate not supplied

An approach to the timely treatment of acute stress disorder.

A convergent postburn psychopharmacologic treatment for children for acute stress disorder (ASD) symptoms has not been established. Both the application of what has been learned through treatment of similar symptoms experienced by adults with posttraumatic stress disorder and the examination of safe treatment options for children led to the clinical decision to use imipramine for 25 pediatric patients with acute burns. The treatment histories of these patients were retrospectively reviewed to see if further exploration into the efficacy of imipramine was warranted. Eighty percent of the children experienced remission of hyperarousal symptoms (eg, trouble staying asleep, trouble falling asleep) and intrusive reexperiencing symptoms (eg, nightmares). Twelve percent of the children experienced a decrease in the frequency or intensity of ASD symptoms. Eight percent had no relief of ASD symptoms. Initial findings suggest that imipramine assists children who have postburn ASD symptoms by decreasing the hyperarousal and intrusive reexperiencing symptoms of ASD.

Adult↗
PubMedDate not supplied

[Effectiveness of a carbamate insecticide as a household low-volume spray for malaria control].

A comparative regional-scale evaluation of the epidemiological impact of low volume (LV) spray of bendiocarb and the conventional spray of DDT against malaria in an endemic area of northern Chiapas was carried out. Three Anopheline species were found: Anopheles pseudopunctipennis, An. albinanus and An. argyritarsis. The most prevalent was An. pseudopunctipennis, a species we suspect may be involved in the transmission of most malaria cases. This species showed high levels of resistance to DDT. However, this insecticide had a long residual effect in wall bioassays, with mortalities > or = 95 per cent for up to 21 weeks in wood, sticks and plaster. Susceptibility to bendiocarb was total, and mortality to LV bendiocarb was > or = 75 per cent for up to 16 weeks in wood, sticks and straw. Very low numbers of mosquitoes were found throughout the evaluation, although malaria transmission continued in control villages (sprayed with DDT), as well as treated villages (sprayed with LV bendiocarb). No plasmodium infected mosquitoes were found, perhaps due to a very small sample size. The LV spray methodology was found to be 1.7 times more effective than conventional spraying in reducing malaria incidence. A net reduction of 1.6 times in insecticide application time was also found, which would allow spraying at the right time, especially when urgent control measures have to be applied, such as in malaria outbreaks. Finally, the new methodology costs 2.2 times more than the conventional ddt spraying, but if the potential of using spray workers in other activities is considered, costs would be comparable to those of DDT spraying.

Aerosols↗