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Biomedical subjects

R Allen

Publications and source records attributed to R Allen.

At least 73 records · Page 4Linked to original sources
PubMed1994

Organizational innovations that nourish staff leadership.

Health care is experiencing a paradigm shift that has the potential to redefine traditional roles, systems, and practices. At Albert Einstein Medical Center in Philadelphia, Pennsylvania, the nursing organization has capitalized on this potential and has been energized by the array of opportunities for innovation and experimentation. The results of these efforts suggest that many of these changes not only are positive approaches to patient care but also promote staff leadership and an entrepreneurial spirit at the front line.

Decision Making, Organizational↗
PubMed1994

The effects of sympathomimetics on the cardiovascular system of sheep.

1. Sheep hearts have been used to study the effects of beta-adrenoceptor (beta-AR) agonists in order to better understand the effects of common asthma treatment drugs on heart rate, cardiac power output and cardiac pathology. Hearts have been examined both in vivo and in vitro. 2. In whole anaesthetized sheep, isoprenaline, fenoterol and salbutamol induced dose-dependent increases in heart rate. Hypokalaemia in response to salbutamol was accentuated in hypoxia. Many of these hearts showed significant myocardial lesions. Hypoxia alone caused no significant cardiac response. 3. As expected, the beta 1-AR agonist dobutamine caused dose-dependent increases in heart performance (heart rate and cardiac power output). Both responses were blocked by metoprolol and propranolol. The beta 2-AR agonist salbutamol caused dose-dependent increases in heart rate and although cardiac output increased, cardiac power output remained unchanged as a consequence of the fall in peripheral resistance. The heart rate changes were blocked by metoprolol. Importantly, propranolol blocked both the heart rate response and the fall in peripheral resistance. 4. Isolated atrial strips showed a right shift of their dose-response curve to isoprenaline in the presence of the highly selective beta 2-AR antagonist ICI 118,551 at concentrations above 1 x 10(-8) mol/L. 5. We conclude that the sheep heart shows many pharmacological characteristics of the human heart which makes it a good pharmacological model in addition to its being amenable to many common techniques available for humans.

Albuterol↗
PubMed1994

Resorption patterns following intentional vital root transection in Macaca mulatta.

Previous studies have shown degeneration of nerve tissue as well as reorganization by periodontal tissue in dental pulp chambers following intentional vital root transection in Macaca mulatta. The supporting structures of the teeth, as well as the root itself, have not been fully studied following such surgery. The purpose of this study was to observe histopathologic changes in bone and root structure over a 1-year postoperative period. Three adult Macaca mulatta were evaluated for this study. Roots were transected within the apical one third and the areas were surgically closed. Following a postoperative soft diet for 7 days, the monkeys were allowed normal masticatory function. Maxillary and mandibular quadrants were removed following vascular perfusion of the animals at 1, 2, 3, 6, 24, and 52 weeks; quadrants were then demineralized, embedded, sectioned, and stained with Preece's trichrome. Resorption of cementum, dentin, and bone was independently evaluated on microslides for each tooth at consecutive intervals of approximately 70 microns. Resorption was rated as mild, moderate, or severe depending on the number of Howship's lacunae and the dimension of the resorptive area. Severe bone resorption was evident at 1 week, decreasing at 2 weeks, and then progressively decreasing up to 52 weeks. Most active inflammatory root resorption was noted on maxillary and mandibular premolars and molars on first-week specimens. Arrested resorptive areas were present in similar locations in second- and third-week specimens. New cementum was present along the cut surface on specimens from 2 to 52 weeks and within the pulp canal beginning at 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Endothelium-derived relaxing factor inhibition and the pressor response to norepinephrine in the pregnant rat.

OBJECTIVE: To determine whether endothelium-derived relaxing factor (EDRF) plays a role in the blunted pressor response to norepinephrine that is characteristic of normal pregnancy. METHODS: Eleven pregnant (mean +/- standard error of the mean 18 +/- 1 days of gestation) and 11 virgin conscious, unrestrained Sprague-Dawley rats with long-term indwelling vascular catheters were studied. Mean arterial pressure (MAP) and heart rate were measured in response to continuous infusions of either vehicle (5% dextrose) or increasing concentrations of norepinephrine (25, 100, and 200 ng/kg/minute) before and after administration of NG-monomethyl-L-arginine (LNMMA), a specific inhibitor of EDRF synthesis. RESULTS: Baseline MAP was lower in pregnant than in virgin rats (96 +/- 3 versus 105 +/- 3 mmHg; P < .05). Before LNMMA administration, the pregnant rats exhibited a significantly blunted pressor response to increasing concentrations of norepinephrine compared to that of virgin rats (P < .005). Given alone, LNMMA produced a greater increase in baseline MAP in virgin rats than in pregnant rats (rise in MAP of 44 +/- 2 versus 31 +/- 2 mmHg; P < .001). However, LNMMA abolished the blunted pressor response to norepinephrine in the pregnant animals and did not significantly affect the pressor response to norepinephrine in virgin rats. Heart rate responses to increasing concentrations of norepinephrine in the presence and absence of LNMMA were not significantly different in the two groups of animals. CONCLUSION: Stimulated EDRF production may contribute to the blunted pressor response to norepinephrine characteristic of pregnancy in the rat.

Analysis of Variance↗
PubMed1993

Diary keeping in asthma: comparison of written and electronic methods.

OBJECTIVE: To determine the extent to which symptom diaries of asthmatic patients are inaccurate or based on retrospective recall. DESIGN: Comparison of electronic and pencil and paper diaries. Both forms were completed twice daily at home for 14 days. SETTING: Outpatient clinic. SUBJECTS: 24 asthmatic outpatients also tested for severity of asthma and for anxiety. RESULTS: More sessions were missed in the evening than in the morning for both types of diaries. Significantly more retrospective entries were made in the evening (26 entries, 14 patients) than in the morning (6 entries, 3 patients). Discrepant entries of peak expiratory flow accounted for 15% of those made on the appropriate day, and three quarters of patients made at least one discrepant entry. Variation in peak expiratory flow was significantly related to number of discrepancies and number of missing days, and anxiety score was significantly related to number of missing days. About a fifth of written entries may have errors. CONCLUSION: Poor diary completion may result from having unreasonable expectations of patients and giving incomplete instructions. Electronic, time coded diaries could ensure better quality of records.

Asthma↗
PubMed1993

Pharmacokinetics of 10-ethyl-10-deaza-aminopterin, edatrexate, given weekly for non-small-cell lung cancer.

We studied the pharmacokinetics of 10-ethyl-10-deaza-aminopterin (10-EdAM), edatrexate and its 7-hydroxy metabolite during a phase II trial of treatment in advanced non-small-cell lung cancer. A dose of 80 mg/m2 was given weekly, with dose reduction being undertaken for mucositis or haematological toxicity. A triphasic pattern of plasma elimination was seen, the mean half-lives being 0.10 +/- 0.07, 0.8 +/- 0.3 and 7 +/- 7 h, respectively. The mean plasma clearance was 25 +/- 14 l/h, with 18% +/- 11% of the dose appearing unchanged in the urine. The serum concentration at 1 h accurately predicted the area under the curve (AUC) with r2 = 0.976. There was considerable variation of the clearance both within and between patients but there was no evidence of a dependence on time or dose. The 1-h concentration of the drug was shown to be related to the incidence of toxicity requiring dose reduction. The change in WBC due to the initial dose was shown to be related to both the AUC of the drug and that of its 7-OH metabolite.

Aminopterin↗
PubMed1993

Body-image distortion and mental imagery.

This study explored whether body-image distortion is a function of difficulties with imagery or problems with judgment. 49 subjects were given the Modified Video Camera Technique to measure body-image distortion. Mental imagery was measured by a modified version of the Vividness of Visual Imagery Questionnaire and the Spatial Relations subtest of the Woodcock-Johnson Psycho-educational Battery. Visual recall was assessed on the Meier Art Judgment Test. Judgment bias was assessed by the Stunkard Silhouette Method and the shape and weight subscales of the Eating Disorder Examination. Subjects who distorted body-image scored significantly more poorly on mental imagery than those who did not distort. No differences were found between groups on visual memory recall or in judgment bias.

Adult↗
PubMed1993

Facial and auditory affect recognition in senile geriatrics, the normal elderly and young adults.

A group of young adults, normal elderly, and senile people were tested for the recognition of facial, auditory and musical affect, as well as nonemotional voice inflections. With respect to the affect recognition tasks, the musical stimuli generated the greatest number of errors and the facial stimuli the fewest. The senile group performed significantly more poorly than the other two groups and the normal elderly made reliably more mistakes than the young adults to affective voice tones and melodies. Also, the normal elderly made more mistakes than the young people to nonemotional voice tones. The senile group responded at chance level to these stimuli. The number of errors to emotional and nonemotional voice tones did not differ within the young and normal elderly groups. However, the senile people responded with significantly greater accuracy to the affective voice inflections. It was concluded that aging is a factor that negatively affects the recognition of tonal inflections, be they vocal or musical. In addition, the recognition of emotional and nonemotional voice inflections are independent of one another.

Adolescent↗
PubMed1993

Juvenile chronic arthritis--diagnosis and management.

Juvenile chronic arthritis (JCA) is actually a collection of conditions that together constitute the major forms of chronic arthritis in childhood. The author outlines the diagnosis and management of this condition, which should be considered as a distinct entity from the arthritides of adulthood.

Adolescent↗
PubMed1993

Who will practise emergency medicine? Survey of family medicine graduates.

A survey of recent family medicine graduates showed that two thirds were doing no emergency work. Those who had originally planned to practise emergency medicine were more likely to be doing it than those who had not. More women than men dropped their plans to do emergency work. Two thirds of those who had dropped their plans thought their training had influenced the decision.

Attitude of Health Personnel↗
PubMed1993

Cigarette smoking during pregnancy: acute effects on uterine flow velocity waveforms.

OBJECTIVE: To determine the acute effects of smoking during pregnancy on selected characteristics of the flow velocity waveform of the uterine artery. METHODS: We studied 19 chronic smokers at a mean (+/- standard error) gestational age of 28 +/- 1 weeks. After informed consent was given, the uterine artery was located using ultrasound imaging with color flow mapping. The characteristic waveform was imaged by pulsed Doppler ultrasonography. Maternal heart rate and blood pressure and the systolic-diastolic ratio (S/D) and resistance index of the uterine artery were measured before (-10 and -1 minutes), during (+5 and +10 minutes), and after (+20 and +30 minutes) smoking two standard cigarettes in succession. RESULTS: Maternal heart rate increased 27%, systolic blood pressure increased 8%, and diastolic blood pressure increased 19% with smoking (P < .001). The uterine artery S/D and resistance index decreased from 2.33 to 2.02 and from 0.55 to 0.49, respectively (P < .001). CONCLUSION: The acute effects of smoking on maternal systemic hemodynamics probably influence the flow velocity waveform of the uterine artery and preclude any definitive interpretation of acute changes in downstream resistance.

Adult↗
PubMed1992

Targeted disruption of the mouse transforming growth factor-beta 1 gene results in multifocal inflammatory disease.

Transforming growth factor-beta 1 (TGF-beta 1) is a multifunctional growth factor that has profound regulatory effects on many developmental and physiological processes. Disruption of the TGF-beta 1 gene by homologous recombination in murine embryonic stem cells enables mice to be generated that carry the disrupted allele. Animals homozygous for the mutated TGF-beta 1 allele show no gross developmental abnormalities, but about 20 days after birth they succumb to a wasting syndrome accompanied by a multifocal, mixed inflammatory cell response and tissue necrosis, leading to organ failure and death. TGF-beta 1-deficient mice may be valuable models for human immune and inflammatory disorders, including autoimmune diseases, transplant rejection and graft versus host reactions.

Animals↗
PubMed1992

Phase II study of Edatrexate in stage III and IV non-small-cell lung cancer.

A total of 49 patients with advanced, previously untreated non-small-cell lung cancer (NSCLC) were treated with a new antifolate, Edatrexate (10-ethyl-10-deaza-aminopterin; 10-EdAM). Patients received 80 mg/m2 weekly for 12 weeks, and responders received a further 6 cycles at 2-week intervals. Dose reductions were carried out for haematological toxicity and mucositis. Response was assessed prior to each treatment according to WHO criteria. Among the 45 evaluable patients, 6 [13.3%; 95% confidence interval (CI), 6%-26%] achieved a partial response (PR) and 9 (20%; 95% CI, 11%-34%) showed a minor response (MR; 25%-50% reduction in the sum of 2 perpendicular tumour diameters). In those receiving four or more cycles of treatment, the PR and MR rates were 17.6% and 26.4%, respectively. The resultant toxicity mainly constituted skin rash, mucositis and myelosuppression. Edatrexate is active against NSCLC and produces toxicity profile similar to that of methotrexate.

Aged↗
PubMed1991

Sequence of a small subunit rRNA gene of Schistosoma mansoni and its use in phylogenetic analysis.

The complete sequence of a small ribosomal RNA gene of Schistosoma mansoni contained within plasmids pSM389 and pSM889 is presented. It was found to be 1992 bp in length, larger than that of most eukaryotes. Extra nucleotides occur in regions known to be variable (V4 and V7). The predicted secondary structure of the nucleotides 660-853 revealed additional helices which have been designated E21-1A and E21-1B. The other region to differ from higher eukaryotes lies between nucleotides 1457 and 1569. Secondary structure prediction demonstrated that a single extended helix may be formed from this part of the schistosome small subunit rRNA sequence. Nucleotides that could be unambiguously aligned with those of 12 other eukaryotes were used to estimate phylogenetic relationships. The consensus tree obtained by Maximum Parsimony analysis showed the schistosome as a sister taxon to the flatworm Dugesia tigrina.

Amino Acid Sequence↗
PubMed1991

Structure of Sm25, an antigenic integral membrane glycoprotein of adult Schistosoma mansoni.

Sm25 is the principal antigen recognised by antibodies from mice protectively vaccinated with isolated tegumental membranes of adult Schistosoma mansoni. The full-length amino acid sequence of this protein has been deduced from the sequence of two cDNAs, one isolated by screening a cDNA library and the other, including the 5' end of the gene, amplified directly from adult worm RNA using the polymerase chain reaction. The predicted sequence represents a nascent polypeptide of Mr 21,500. Following cleavage of a predicted signal sequence, the Mr of the resulting polypeptide is 17,600. The polypeptide contains 2 potential sites for N-linked glycosylation and a hydrophobic domain at the C-terminus that could facilitate membrane association. Analysis of the mature gene product confirmed that Sm25 is an N-glycosylated integral membrane protein and that the Mr of the deglycosylated polypeptide is between 15,000 and 20,000.

Amino Acid Sequence↗