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Biomedical subjects

R Allen

Publications and source records attributed to R Allen.

At least 163 records · Page 9Linked to original sources
PubMed1991

A comparison of the cardiovascular effects of phenylpropanolamine and phenylephrine containing proprietary cold remedies.

1. The cardiovascular effects of the proprietary cold remedies, Mu-cron and Boots Cold Relief tablets were compared with 'placebo' Boots Pain Relief tablets in a double-blind study involving 16 healthy volunteers. Measurements (impedance cardiography, forearm plethysmography) were made over 4 h after oral drug administration. 2. Two Mu-cron tablets (containing phenylpropanolamine [(1R,2S)- plus (1S,2R)-norephedrine] 50 mg) increased blood pressure (maximal effect 18 +/- 1/8 +/- 1 mm Hg (mean +/- s.e. mean), P less than 0.001), stroke volume (4.9 +/- 0.8 ml m-2, P less than 0.05), total peripheral resistance (243 +/- 27 dyn s cm-5 m2, P less than 0.001) and forearm vascular resistance (1.3 +/- 0.3 mm Hg ml-1 min, P less than 0.01) and reduced the ratio of pre-ejection period to ventricular ejection time (-0.031 +/- 0.003, P less than 0.05) and forearm blood flow (-2.6 +/- 0.5 ml min-1, P less than 0.05) but did not affect heart rate or cardiac index. 3. Two Boots Cold Relief tablets (containing phenylephrine 10 mg and caffeine 60 mg) caused a small and short-lived increase in total peripheral resistance but did not have consistent effects on other measurements. Two Boots Pain Relief tablets (containing caffeine 60 mg) did not have important cardiovascular effects. 4. The cardiovascular effects of phenylpropanolamine, including vasoconstriction and an increase in cardiac performance, are consistent with its alpha- and beta 1-adrenoceptor agonist action. While it may help the symptoms of rhinitis, its use in patients with heart disease or hypertension is hazardous.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

Randomized, double-blind trial of deflazacort versus prednisone in juvenile chronic (or rheumatoid) arthritis: a relatively bone-sparing effect of deflazacort.

Thirty-four children with juvenile chronic (rheumatoid) arthritis were recruited to a randomized, double-blind study of deflazacort (an oxazolone derivative of prednisone) vs prednisone. All had been receiving glucocorticoid therapy for at least 1 year and required at least 5 mg/d of prednisolone (usually as 10 mg every 2 days). Thirty-one children completed the study. Bone density trends were measured in the spine by dual photon absorptiometry and in the forearm by single photon quantitative computed tomography at 3-monthly intervals. Trends (velocities) in bone and soft tissue growth were calculated. In the spine, bone growth correlated well with indices of soft tissue growth, but covariance analysis showed a significant advantage (P less than .007) of deflazacort when spinal bone mineral growth was compared to body surface area and weight. In part this was due to a temporary interruption in weight by children receiving deflazacort, whose gain in height was comparable with that of the prednisone group. Some children in both groups improved clinically and showed catch-up growth; in these children relative spinal bone mineral growth velocities were about twice those observed for height and weight. It is concluded that during the first year of deflazacort, their spinal bone mineral content at a level that was appropriate for their height and weight. Further observations are required to establish whether this advantage can be maintained subsequently. The anti-inflammatory effects of the two glucocorticoids appeared similar.

Adolescent↗
PubMed1991

Naproxen induced pseudoporphyria in juvenile chronic arthritis.

We report 6 cases of porphyria-like skin reactions in children taking naproxen for juvenile chronic arthritis. The lesions mimicked either erythropoietic protoporphyria or porphyria cutanea tarda, with both forms occurring in 2 patients. Biochemical studies excluded abnormal porphyrin metabolism.

Adolescent↗
PubMed1991

Preoperative screening for perioperative cardiac risk.

Preoperative screening for potential cardiac complications is crucial in making rational decisions about surgery. A number of classification schemes are available to aid the primary care physician in assessing a patient's perioperative cardiac risk. In general, these schemes enable the physician to place patients in low-risk, moderate-risk and high-risk categories. Patients at low risk can often be safely referred for surgery with minimal preoperative evaluation, while those at potentially high risk frequently need further assessment and medical or surgical treatment of cardiac disease prior to surgery. The classification schemes are most accurate in identifying patients at high risk for perioperative cardiac complications. However, patients with silent underlying cardiac disease are often underclassified with respect to potential risk. For those patients, accurate prediction of perioperative cardiac complications can be challenging.

Health Status↗
PubMed1991

Referral patterns and the results of antireflux operations in patients more than sixty years of age.

The role of antireflux operations in the elderly is ill-defined. Often, these patients are managed medically despite refractory symptoms for fear of surgical morbidity and mortality by referring physicians. This investigation was done to review the referral patterns and results of antireflux operations for patients more than 60 years old. The charts of all patients undergoing operation for reflux were reviewed during an eight year period from 1981 to 1989. One hundred and three patients underwent Nissen fundoplication. All patients had been treated with H2 blockers or antacids, or both, prior to referral for operation. Group 1 (N = 43) consisted of all patients who were 60 years of age and group 2 (N = 60), all patients less than 60 years of age. The mean age of those in group 1 was 70.6 years versus 43.7 years for those in group 2. The mean duration of symptoms was far greater in the elderly group versus the younger group (14.4 versus 4.1 years) (p less than 0.001). Twenty-eight patients in group 1 were referred for surgical treatment because of complications of reflux versus only four in group 2 (p less than 0.01) in whom intractability was the main indication for surgical treatment. The specific complications of gastroesophageal reflux disease that led to the referral of elderly patients for operation were stricture, bleeding, aspiration and Barrett's esophagus. There was one death and this occurred in a 46 year old woman who had a massive pulmonary embolism postoperatively. The mean duration of follow-up study was 5.1 years. Improvement in symptoms was noted by 37 patients in group 1 versus 56 in group 2. We conclude that elderly patients are most often referred for antireflux operations for complications of reflux versus younger patients in whom intractability is the most common indication. Earlier referral is warranted if reflux symptoms persist despite adequate medical therapy. Despite advanced esophageal disease, the results of antireflux operations are good, and surgical morbidity and mortality rates are low enough to warrant intervention in this group of patients, provided no medical contraindications exist.

Adult↗
PubMed1991

Risk factors for shoulder dystocia: an engineering study of clinician-applied forces.

We report on engineering risk factors associated with clinician-applied forces during vaginal delivery of newborns. Specifically, we present and interpret data from a series of experiments using force-sensing devices on 29 randomly selected vaginal births, including two shoulder dystocia deliveries and one birth injury. The results indicate that clinician-applied peak forces are typically about 47 N for routine deliveries, 69 N for difficult deliveries, and 100 N for a shoulder dystocia delivery (P less than .01). The time required to deliver fetal shoulders doubles for nonroutine deliveries (P less than .01). In addition, impulse and rate of application of force distinguish between routine and nonroutine deliveries (P less than .03). We conclude that, if properly perceived, force, force rate, and the duration of force are objective parameters that can be used in recognizing and managing shoulder dystocia and in predicting thresholds for birth injury.

Biophysical Phenomena↗
PubMed1991

Caring for the uninsured. The Oregon experience.

A commission was appointed by the governor of Oregon to develop strategies to increase health care access for the estimated 400,000 Oregonians who were without health insurance. Because of real or perceived financial barriers to access, these uninsured usually had more expensive, acute, and episodic care that resulted in the shifting of cost to the insured and in higher health care costs. After studying the problem for 6 months, the commission made specific recommendations that if fully implemented, would ensure access to health care for virtually all uninsured Oregonians. The recommendations support existing medical and insurance systems, foster public and private partnerships, and provide for the leveraging of federal Medicaid dollars in a favorable ratio to the state. The implementation of these recommendations should ultimately reduce costs and at the same time provide more care.

Delivery of Health Care↗
PubMed1990

Human neutrophils exhibit disparate chemotactic factor gene expression.

The evolution of acute inflammation from initiation through resolution is associated with the changing character of the infiltrating leukocytes. Recruitment of these leukocytes is dependent upon the generation of chemotactic factors that have either global or specific activity for a particular leukocyte. In this manuscript we present data demonstrating that human neutrophils can express mRNA for neutrophil chemotactic factor/interleukin 8 (IL-8), but fail to express mRNA for monocyte chemotactic protein (MCP-1). The expression of IL-8 was observed upon adherence or in response to stimulation with lipopolysaccharide. Maximal IL-8 antigenic production was noted at 24 hrs. These studies demonstrate a disparate expression of chemotactic cytokines by neutrophils.

Acute Disease↗
PubMed1990

The genetics of six neurotic disorders: a twin study.

Persons who had met criteria for specific anxiety or depressive neuroses during their lifetime were identified from a sample of 446 pairs of adult twins. Although there was a genetic contribution to neuroticism and to symptoms, there was no inheritance of specific disorders. This concurs with previous work in a sample from the same Australian Twin Registry and with those from a Norwegian sample. It is concluded that while there is a genetic contribution to the predisposing trait, and therefore to the intermittent appearance of symptoms, this contribution is obscured by the grouping of symptoms into diagnoses and by the help seeking which is a prerequisite to clinical diagnosis.

Adolescent↗
PubMed1990

Chronic toxicity/carcinogenicity studies of sulphamethazine in Fischer 344/N rats: two-generation exposure.

Fischer 344 rats were given 10, 40, 600, 1200 or 2400 ppm sulphamethazine (SMZ) in the diet to determine the toxicity and potential carcinogenicity of SMZ. There were 225 rats of each sex in the control groups and 135 of each sex in each dose group. Animals were killed after 3, 12, 18 or 24 months of continuous dosing. Body weights, feed consumption, clinical observations, organ weights and histopathology data were collected. A slight decrease in body-weight gain was observed in the high-dose groups compared with the controls. No difference in feed consumption was found between the control and dosed rats. Mortality was inversely related to SMZ dose, especially in females, that is mortality was highest in the controls and decreased as the dose of SMZ increased. A statistically significant dose-related increase in the incidence of follicular cell adenocarcinomas of the thyroid gland was observed in the animals killed after 24 months. The incidences of non-neoplastic lesions of the thyroid gland in treated animals were significantly higher among treated animals than among controls; these lesions included follicular cell hyperplasia, follicular cell focal cellular change and multilocular cysts. The incidences of retinal atrophy, atrophy of the acinar pancreas (males), and dilatation of the uterine lumen also increased with increasing SMZ dose.

Adenocarcinoma↗
PubMed1990

Effect of electrocautery on wound healing in midline laparotomy incisions.

The effect of electrocautery on midline fascial wound healing was studied in 108 Sprague-Dawley rats. Midline wound tensile strength was significantly reduced in fascia incised with the coagulation current compared with the cutting current or scalpel. In addition, tissue necrosis and inflammation as well as adhesion formation between the incision and abdominal viscera were more extensive in animals with incisions made using coagulation current. The results of the study indicate that the use of electrocautery coagulation current is associated with increased tissue damage and a significant reduction in the tensile strength of healing wounds. The contribution of electrocautery to wound complications in patients needs further evaluation.

Abdominal Muscles↗
PubMed1990

Snap-gauge compared to a full nocturnal penile tumescence study for evaluation of patients with erectile impotence.

A total of 50 consecutive male patients underwent simultaneous Snap-Gauge and full nocturnal penile tumescence evaluation with objective rigidity measurements to determine the correlation between the 2 studies. Subsequent clinical evaluation was conducted in patients in whom the 2 tests differed regarding diagnoses to determine which test more accurately predicted the clinical outcome. One patient was excluded from the study for technical reasons. Of 14 patients who had a normal Snap-Gauge evaluation, defined by breakage of all 3 bands, 12 (86%) had a normal and 2 (14%) had an abnormal nocturnal penile tumescence evaluation. A total of 28 patients failed to break any of the Snap-Gauge bands and 7 broke only 1 or 2 bands. Of these 35 patients with an abnormal Snap-Gauge study 14 (40%) had a normal and 21 (60%) had an abnormal nocturnal penile tumescence evaluation. In a subsequent clinical evaluation 1 of the 2 patients with a normal Snap-Gauge study and an abnormal nocturnal penile tumescence test reported continued inadequate sexual function and, subsequently, he received a penile prosthesis. Of the 14 patients with an abnormal Snap-Gauge study and a normal nocturnal penile tumescence test 11 were located and 8 were sexually active with adequate erections for intercourse without further medical treatment other than counseling. We conclude that the correlation between Snap-Gauge and nocturnal penile tumescence is not good, and that the nocturnal penile tumescence test is more accurate to determine the clinical diagnosis.

Adult↗
PubMed1990

Use of [11C]aminocyclohexanecarboxylate for the measurement of amino acid uptake and distribution volume in human brain.

A quantitative positron emission tomographic (PET) method to measure amino acid blood-brain barrier (BBB) transport rate and tissue distribution volume (DV) has been developed using 11C-labeled aminocyclohexanecarboxylate (ACHC), a nonmetabolized amino acid analogue. Dynamic PET data were acquired as a series of 15 scans covering a total of 60 min and analyzed by means of a two-compartment, two-parameter model. Functional images were calculated for the amino acid transport rate constants across the BBB and the amino acid DV in the brain. Results show [11C]ACHC to have an influx rate constant in gray matter of approximately 0.03-0.04 ml g-1 min-1, indicating a single-pass extraction fraction of approximately 5-7%. The intersubject coefficient of variation was approximately 15% while intrasubject variability of repeat scans was only slightly greater than 5%. Studies were performed in 15 young normal volunteer control subjects, 5 elderly controls, 7 patients with probable Alzheimer's disease, and one patient with phenylketonuria. Results indicate that [11C]-ACHC will serve as the basis of a method for measuring amino acid transport rate and DV in the normal and pathological human brain.

Adult↗
PubMed1990

Discrimination between HIV-1 and HIV-2-seropositive individuals using mouse monoclonal antibodies directed to HIV transmembrane proteins.

Mouse monoclonal antibodies directed against the transmembrane proteins of HIV-1 or HIV-2 provided site-directed, unambiguous discrimination between HIV-1 and HIV-2 antibody-positive sera, when employed in immunoassays as competitive probes against serum antibodies. These monoclonal antibodies mapped to epitopes outside of the well-characterized immunodominant regions (IDR) of the transmembrane proteins. The monoclonal competitive immunoassay was a superior method for discrimination compared with immunoprecipitation of metabolically radiolabeled HIV envelope glycoproteins, Western blot against viral envelope glycoproteins, or noncompetitive enzyme immunoassays employing HIV recombinant transmembrane proteins or synthetic IDR peptides as serological targets. The monoclonal competitive assay was not affected by antigenic cross reactivity or nonspecific reactivity exhibited by selected serum samples toward envelope proteins or peptides, respectively. Results of the monoclonal competitive immunoassay were supported by results of a peptide inhibition assay employing free IDR peptides in competition with IDR peptides on a solid support for binding of serum antibody. IDR peptide inhibition clearly demonstrated non-cross-reactive antigenic specificity of sera toward either the HIV-1 IDR or the HIV-2 IDR. The monoclonal competitive assay also identified samples containing antibody to both HIV-1 and HIV-2 transmembrane proteins. Analysis of these samples by IDR peptide inhibition indicated they contained two distinct, non-cross-reactive populations of antibodies, one directed to the HIV-1 IDR and the other directed to the HIV-2 IDR.

AIDS Serodiagnosis↗
PubMed1990

Transplacental transfer of aflatoxin in humans.

This study quantified aflatoxin (AFB1, AFG1 and AFQ1) by enzyme-linked immunosorbent assay in human cord sera obtained at birth and in serum obtained immediately after birth from the mother. The subjects of the study were residents of Songkhla, Thailand. Of the 35 samples of cord sera, 17 (48%) contained aflatoxin in concentrations from 0.064 to 13.6, mean 3.1 nmol/ml. By comparison only two (6%) of 35 maternal sera contained aflatoxin (mean 0.62 nmol/ml). These results demonstrate transplacental transfer and concentration of aflatoxin by the feto-placental unit which may be of biological importance. Aflatoxins are mutagenic, carcinogenic and teratogenic and cause immunosuppression in animals. The implications of these findings are potentially profound and deserve further study.

Aflatoxin B1↗