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Biomedical subjects

J R Anderson

Publications and source records attributed to J R Anderson.

At least 289 records · Page 16Linked to original sources
PubMed1989

Esophageal tamponade in the management of acute variceal hemorrhage.

Over a seven-year period, 138 patients with portal hypertension presented on 223 occasions with endoscopically proven acute variceal hemorrhage. Hemorrhage ceased spontaneously on 92 occasions (41%). On 126 occasions (57%) passage of the four-lumen modification of the Sengstaken-Blakemore tube was required, and hemorrhage was successfully controlled in 98%. Intubation was refused on five occasions (2%). Hemorrhage recurred during these 223 admissions on 47 occasions (21%); on 11 occasions a second rebleed occurred and on two occasions, a third. Tamponade was required during all of these rebleeds and arrest of hemorrhage was achieved in 87%. Hemorrhage in patients with poorer modified Child's grade was less likely to cease with intubation. The overall rate of control in the 186 episodes of hemorrhage requiring tamponade was 94%. There were 28 complications attributed to the use of tamponade in 186 episodes of hemorrhage (15%). On 12 occasions these complications proved fatal (6.4%). In four further patients failure of tamponade to control hemorrhage was fatal.

Adolescent↗
PubMed1989

Increased incidence of infections in intravenous drug users.

To ascertain the incidence of infections in intravenous users of illicit drugs, we performed a retrospective study of 270 intravenous drug users (IVDUs) and 562 controls who did not use drugs over a seven-year period from 1978-1985. IVDUs had an increased overall incidence of infections (P less than 0.001) compared to controls, which was explained to a large degree by an increased incidence of hepatitis. Endocarditis and disseminated gonococcal infection were seen with increased frequency in IVDUs (P less than 0.05), but abscess and cellulitis were not. Neither acquired immunodeficiency syndrome (AIDS), tuberculosis, Pneumocystis pneumonia, nor disseminated viral or fungal infection were seen in IVDUs or controls. Heroin users, but not other IVDUs, had an increased incidence of infections not thought to be associated with needle use, suggesting impaired immunity. This study demonstrates that IVDUs have an increased incidence of infection compared to control subjects, but the kinds of infections have changed substantially over the past two decades. The presence of opportunistic pathogens in these patients should suggest concurrent infection with human immunodeficiency virus (HIV).

Adult↗
PubMed1989

Blood-feeding drive inhibition of Aedes sierrensis (Diptera: Culicidae) induced by the parasite Lambornella clarki (Ciliophora: Tetrahymenidae).

Female Aedes sierrensis (Ludlow) infected with the parasitic ciliate Lambornella clarki Corliss and Coats were significantly less responsive toward a human host than uninfected females. The proportion of infected females that were inhibited in host-seeking and blood-feeding remained high in all daily exposures to the host. Those that did respond took approximately twice as long to land on the host and 25% longer to complete probing as did uninfected females. In contrast, nearly all uninfected females more than 5 d old rapidly responded to and blood fed on the host. Uninseminated females were more similar in their behavior to infected females than to uninfected inseminated females. For females allowed to ingest blood, the time from completion of probing to engorgement was not significantly different for infected versus uninfected females. Some blood-fed, uninfected females took one additional small blood meal 1-3 d after the first blood meal, but most (56%) were inhibited in blood feeding until after ovipositing. Overall feeding time and most sequential behaviors associated with blood feeding were similar to those reported for other mosquito species. Parasite-induced inhibition of the blood-feeding drive may explain low capture rates of L. clarki-infected mosquitoes at human bait.

Aedes↗
PubMed1989

Emergence characteristics of Aedes sierrensis (Diptera: Culicidae) from California treeholes with particular reference to parasite loads.

Wing lengths, emergence times, and parasite loads were determined for 8,444 newly emerged adult Aedes sierrensis (Ludlow) collected from 17 treehole emergence traps during a sampling period of 149 d. Peak adult emergence occurred in late spring and early summer, but a small second cohort developed in treeholes retaining water through the dry season. Mosquito production was significantly and positively correlated with the maximum volumes of treeholes. Male and female wing lengths and eclosion times varied significantly among populations from different treeholes; within a population, these variables were highly correlated, suggesting that larvae of both sexes respond similarly to treehole conditions. Egg number (but not longevity) was correlated with adult size for laboratory-maintained females collected from emergence traps. These results suggest variation in the vector potential of adult populations produced from different treeholes. Newly emerged mosquitoes were infected by five parasite species that depend on adult hosts for their dispersal. The mermithid nematode Octomyomermis troglodytis Poinar and Sanders and the ciliate Tetrahymena sp. were very rare in adult populations. Gamontocysts of the ascogregarine Ascogregarina clarki Sanders and Poinar infected the Malpighian tubules of adults from six treeholes. Ectoparasitic larval water mites (near Euthyas) were found on 12% of all adults eclosing from eight treeholes and selectively parasitized female hosts over males. The ciliate Lambornella clarki Corliss and Coats was the most common parasite; it infected males and females from seven treeholes in equal proportions. L. clarki had a significant negative impact on adult populations in that 13% of all females from L. clarki-positive treeholes were infected with ciliates, and infected females are parasitically castrated.

Aedes↗
PubMed1989

Use of deer models to study larviposition by wild nasopharyngeal bot flies (Diptera: Oestridae).

Deer models baited with CO2 and with CO2 plus 1-octen-3-ol and Deer Trail Scent attracted and induced female Cephenemyia apicata Bennett & Sabrosky and C. jellisoni Townsend to larviposit on them. Larvae were not deposited on unbaited models. Females of both species were seen at baited models, and an insect trapping adhesive applied to the nostrials, muzzle, and lips of models revealed that all larvae were stuck to the lips and bottom part of the muzzle. The models also attracted and caught most other parasitic Diptera known to attack California black-tailed deer, Odocoileus hemionus columbianus (Richardson), in the study area.

Animals↗
PubMed1989

Effects of beta-adrenergic activity on T-wave amplitude.

This study addresses the hypothesis that electrocardiographic T-wave amplitude is influenced by beta-adrenergic stimulation of the heart. Beta-adrenergic activity was manipulated both pharmacologically and through behavioral challenge. Under resting conditions, 12 healthy men underwent infusion of placebo and then the beta-agonist, isoproterenol, and the beta-blocker, propranolol, in a counterbalanced, crossover design. During infusion of placebo, subjects also underwent two behavioral challenges, a structured interview and mental arithmetic. Analysis of the resting data indicated that propranolol produced a significant increase in T-wave amplitude, and isoproterenol produced significant T-wave amplitude attenuation. As previously reported, drug effects were also in evidence for heart rate. Behaviorally-induced reduction of T-wave amplitude was observed for mental arithmetic but not structured interview, which again paralleled heart rate data. Both pharmacological and behavioral data reported in this study support the hypothesis that the T-wave is significantly affected by beta-sympathetic influence on the heart. However, a nonspecific effect of heart rate change on T-wave amplitude would also account for these results. The findings are discussed in terms of their implications for the utility of T-wave amplitude in psychophysiological research.

Adult↗
PubMed1989

Simple avulsion of onychogryphotic toenails: a justifiable treatment?

Twenty-nine consecutive patients with onychogryphotic toenails in whom conservative treatment had failed, were entered into the study over a one year period and followed-up prospectively for a further year. All patients were treated by simple nail avulsion. The incidence of recurrence was 27 out of 29 patients (93%); only five of these were symptomatic (17%). Only two patients required further surgery. We conclude that simple avulsion of onychogryphotic toenails offers symptomatic relief in the majority of patients, particularly in this elderly population in whom the use of a tourniquet may be contraindicated.

Adolescent↗
PubMed1989

Comparison of several different trapping methods for Culicoides variipennis (Diptera: Ceratopogonidae).

When battery operated CDC miniature incandescent and black light traps (with and without light bulbs) were operated with and without CO2, the rank of trap effectiveness for total numbers of female Culicoides variipennis caught was: black light plus CO2; CO2-baited trap without light bulb; black light without CO2; incandescent light plus CO2 and incandescent light without CO2. In 1983, the black light trap plus CO2 caught significantly more males and females than any other traps, and the incandescent light trap without CO2 caught significantly fewer females than any other traps. There were significant differences also in times gnats were collected, as well as in the gonotrophic condition of females caught in traps and that different traps caught different physiological/reproductive segments of the population. All catches revealed that gravid females began flying only a few min before sunset and peaked in the 1st h after sunset. Because it caught significantly larger numbers of females than other traps and because it was selectively attractive to gravid and parous females, the black light trap would be the trap of choice when large numbers of parous females are desired in arbovirus isolation studies.

Analysis of Variance↗
PubMed1989

The frequency of gastrointestinal endocrine tumours in a well-defined population--Northern Ireland 1970-1985.

The reported incidence of gastrointestinal endocrine tumours is variable. In Northern Ireland circumstances allowing such an assessment are favourable with a central diagnostic laboratory and register established to collect data on tumours from a well-defined population of 1.5 million people. From 1970 to 1985, 368 cases were recorded of which 85 per cent were carcinoid tumours. The annual incidence of carcinoid tumours was 1.3 per 100,000 of the population and the majority occurred in the appendix (61 per cent). No patients presented with the carcinoid syndrome. The annual incidence for other tumours was 0.12 per 100,000 for insulinomas; islet cell tumours of unknown type 0.07; Zollinger-Ellison syndrome 0.05; and multiple endocrine neoplasia (MEN) 0.05. There were two cases of VIPoma, one glucagonoma, one neurotensinoma and one tumour producing ACTH. It is possible that some tumours are more uncommon than others because of difficulty in diagnosis.

Adenoma, Islet Cell↗
PubMed1988

Predator-induced trophic shift of a free-living ciliate: parasitism of mosquito larvae by their prey.

Larvae of the treehole mosquito, Aedes sierrensis, release a waterborne factor that induces morphogenesis of one of their prey, the tetrahymenid ciliate Lambornella clarki. Induced free-living trophonts of L. clarki undergo a synchronous response in which cells divide and transform into parasitic cells (theronts) that encyst on larval predators. Parasitic ciliates penetrate the cuticle, enter the hemocoel, and ultimately kill their predator-host. In nature, this trophic shift can lead to predator extinction and dramatic changes in microbial populations. Facultative parasitism by this polymorphic ciliate may have evolved as an antipredator strategy. The experimentally inducible parasitic response of L. clarki provides a novel model for studying cellular morphogenesis of ciliated protozoa.

Aedes↗
PubMed1988

Hydrofluoric acid burns of the hand: mechanism of injury and treatment.

Hydrofluoric acid is one of the strongest inorganic acids and is used extensively in industry and research. It differs from other acids in that the fluoride ion readily penetrates the skin, causing destruction of deep tissue layers and even bone. Authors have previously described numerous topical treatments. This report describes one method of treatment emphasizing immediate skin cleansing and the application of calcium gluconate gel, which is followed by calcium gluconate subcutaneous injections when necessary. An accurate occupational history and physical examination are important aspects of patient assessment. Prompt treatment resulted in relief of pain and a satisfactory clinical result in all cases. A significant delay in treatment was responsible for permanent impairment in 2 of 14 patients.

Adult↗
PubMed1988

Periumbilical pain secondary to persistent urachal band.

An eight-year-old boy had periumbilical pain associated with micturition; the disorder was secondary to a persistent urachal band. Surgical excision of the urachus resulted in resolution of the symptoms. Although urachal anomalies are unusual, they should be considered in the differential diagnosis of periumbilical pain with micturition.

Child↗