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Biomedical subjects

R A Higgins

Publications and source records attributed to R A Higgins.

9 recordsLinked to original sources
PubMed2002

Modeling the development of resistance by stalk-boring lepidopteran insects (Crambidae) in areas with transgenic corn and frequent insecticide use.

We simulated the population dynamics and population genetics of two bivoltine species of corn borers, the European corn borer, Ostrinia nubilalis (Hübner), and the southwestern corn borer, Diatraea grandiosella Dyar, in a hypothetical region of irrigated transgenic and nontransgenic corn where insecticide was applied only to the nontransgenic refuge crop. Over the 100-yr time horizon, resistance developed quickly in both species and to both transgenic corn and the insecticide when the allele for resistance to the respective toxin was dominant. When the allele for transgenic resistance was not dominant and the refuge location was constant over the time horizon, spraying the refuge to control southwestern corn borer had no effect on how quickly resistance to the transgenic corn developed. In contrast, the European corn borer developed resistance to transgenic corn much sooner when the refuge was sprayed once per year, and the time to 3% resistance allele frequency decreased as efficacy of the insecticide increased. Only when the refuge was treated less than once every 5 yr (10 generations) did the frequency of application decline enough to permit resistance management for the European corn borer to approximate the effectiveness of an unsprayed refuge. A consistently sprayed refuge <40% of the corn acreage was an inadequate resistance management strategy for the European corn borer even when a low efficacy insecticide (70% mortality) was used. When assumptions about European corn borer adult behavior were changed and the adults behaved similarly to adult southwestern corn borer, the development of resistance to the transgenic crop was slowed significantly.

Animals↗
PubMed2001

Evidence of evolving carbaryl resistance in western corn rootworm (Coleoptera: Chrysomelidae) in areawide-managed cornfields in north central Kansas.

Susceptibility of adult populations of the western corn rootworm, Diabrotica virgifera virgifera LeConte, to carbaryl was determined by a survey in 1996 before the implementation of an areawide management program near Scandia in north central Kansas. Subsequently, the susceptibility of western corn rootworm adults to carbaryl has been monitored throughout the program from 1997 to 2000 in both control and managed areas. In 1996, adults were highly susceptible to carbaryl with a mean LC50 value of 0.64 microg/vial. This value was comparable to those for adults collected from other regions within Kansas. However, adult susceptibility to carbaryl decreased rapidly within the managed area, where the cucurbitacin- carbaryl-based bait SLAM has been used as the primary tool to control adults in this project since 1997. In 1999, adults collected from the managed area were 9- and 20-fold less susceptible to carbaryl at the LC50 and LC90 levels, respectively, than those evaluated in 1996. In contrast, adults collected from the control area were only 2- and 3-fold less susceptible to carbaryl at the LC50 and LC90 levels, respectively, than adults evaluated in 1996. Although field adult populations of western corn rootworm were relatively low in 2000, evaluations showed trends similar to those in 1999 regarding their carbaryl susceptibility in the managed and control areas. These results provide evidence that western corn rootworm has been evolving carbaryl resistance rapidly in response to the use of SLAM in areawide-managed cornfields near Scandia.

Animals↗
PubMed1990

Cantharidin decreases in vitro digestion of alfalfa and smooth bromegrass.

Blister beetles (Coleoptera:Meloidae) containing the toxin cantharidin can be incorporated with alfalfa (Medicago sativa L) during forage conservation. Cantharidin inadvertently ingested with animal feed may cause illness or death. Little information is available on the effects of cantharidin on ruminant microbial digestion. The objective of our study was to determine cantharidin effects on digestibility of alfalfa and smooth bromegrass (Bromus inermis Leyss) by measuring in vitro digestible dry matter (IVDDM) and cell wall digestion (CWD). Alfalfa dry matter digestibility, measured after IVDDM at 48 and 96 h fermentation periods, decreased as cantharidin concentration increased. Increasing cantharidin concentration also significantly reduced IVDDM of smooth bromegrass at 24 and 96 h digestion time. The CWD of alfalfa and smooth bromegrass decreased as cantharidin concentration increased. These results indicate that ingestion of cantharidin by ruminants may decrease microbial digestion of fibrous feeds and therefore may decrease the efficiency of feed utilization by ruminants.

Animals↗
PubMed1985

Two years' experience with laser trabeculoplasty.

A series of 115 argon laser trabeculoplasties on 109 eyes in 84 patients over a two-year period is reviewed. Control of glaucoma was achieved in 85%. There was correlation of a greater fall in intraocular pressure with initial height of intraocular pressure and degree of pigmentation of the angle. Gonioplasty proved an effective means of treating cases with a narrowed angle to gain access to the trabecular meshwork.

Acetazolamide↗
PubMed1984

Neovascular glaucoma associated with ocular hypoperfusion secondary to carotid artery disease.

Three cases of neovascular glaucoma associated with ocular hypoperfusion secondary to carotid artery disease are reported. In two cases, anastomosis of the internal and external carotid artery systems via a superficial temporal artery to the middle cerebral artery (Yasargil procedure) resulted in resolution of the rubeosis, relief of the ocular pain and improvement of the circulation of the globe. The third case, which did not have this procedure, resulted in a blind eye with severe rubeotic glaucoma.

Carotid Artery Diseases↗
PubMed1983

Laser trabeculoplasty. Early experience with a new procedure.

Twenty-five laser trabeculoplasty procedures were performed on 20 patients. All patients were treated as inpatients so that early changes in intraocular pressure could be monitored. The range of fall was recorded: in four cases there was a significant rise in intraocular pressure in the first four hours which, if sustained, could have lead to a further visual field loss in patients with advanced chronic simple open-angle glaucoma. Patients with a high initial intraocular pressure had the greatest fall in intraocular pressure. Those patients with a more pigmented trabecular meshwork with wide open angles were the easiest to treat and gave the best signs of effective laser endpoint reaction. Gonioplasty was performed in many patients with narrow angles, which gave much better access to the posterior trabecular meshwork.

Aged↗
PubMed1977

Applicability of some of the assumptions used to estimate the weight of the skeleton in the growing pig and beagle.

Assumptions used in indirectly estimating skeletal weight were tested on 55 pigs (ages day 0-week 12) and 42 beagles (ages day 0-1 year). One of the assumptions was that skeletal weight constitutes a constant proportion of lean body mass (fat-free wet weight). In the beagle the skeletal weight was not constant, but a decreasing proportion of LBM during growth. In the pig there were no significant changes comparable to those in the beagle, probably because only a small part of the growth period was studied. Also, the assumption that bone mineral was 65% of fat-free dry weight of the skeleton was not applicable to the beagle, where it increased from 55% (day 0-week 12) to 70% (mouth 4-1 year). In both species skeletal growth was a function of total fat-free dry weight (FFDWt), but in the beagle the ratio Kt/FFDWt increased from 130 (day 0-week) 12) to 160 (month 4-1 year) and reflected changes in the contribution of body cell mass and skeletal to FFDWt.

Animals↗
PubMedDate not supplied

Three hospitals' survey experiences.

The Joint Commission on Accreditation of Healthcare Organizations has made major alterations in its standards and survey process under the Agenda for Change, by emphasizing cross-functional healthcare. The Joint Commission published the changes in its 1994 Accreditation Manual for Hospitals, under which criteria these hospitals were surveyed. Surveyors concentrated on evaluating the following major issues: care of patients, particularly restraint policies and procedures; uniform performance of processes, particularly as related to conscious sedation; staff competency; and process improvement. The authors detail why a thorough, detailed preparation for the document review session is essential for a successful survey.

Accreditation↗