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Biomedical subjects

R Allen

Publications and source records attributed to R Allen.

At least 127 records · Page 7Linked to original sources
PubMed1994

Cloning and sequencing of the gene encoding spinach ferredoxin-dependent glutamate synthase.

The nucleotide sequences of two cDNA clones, totalling 4948 bp in length, encoding 98% of the 1483 amino acids of the mature form of the ferredoxin-dependent glutamate synthase of spinach chloroplasts have been determined. The amino-terminal sequence of the enzyme has been determined by direct sequencing of the protein. The deduced amino-acid sequence of the spinach enzyme is 83% identical to that of the ferredoxin-dependent maize enzyme and shows significant sequence homology to two prokaryotic NAD(P)H-dependent glutamate synthases. Analysis of spinach genomic DNA indicates the presence of a single-copy gene for the spinach enzyme. Northern analysis reveals the presence of a single 5.5 kb transcript, which is present in higher levels in young spinach leaves than in older leaves.

Amino Acid Sequence↗
PubMed1994

Phase II study of fotemustine in untreated inoperable non-small-cell lung cancer.

A total of 43 patients with advanced, previously untreated non-small-cell lung cancer (NSCLC) were treated with a novel nitrosourea, fotemustine, given at 100 mg/m2 on days 1 and 8. Maintenance treatment consisted of a single injection of 100 mg/m2 given every 21 days. 37 patients were evaluable for response. Of these, 5 patients had a partial response (13.5%; 95% confidence interval, 6%-28%). Toxicity comprised mainly anaemia and thrombocytopenia. Other toxicities were mild. This phase II study confirms that fotemustine is a moderately active and well-tolerated drug in NSCLC.

Aged↗
PubMed1994

Prospective, multicenter study of managing lower extremity venous ulcers.

Seventy patients with 90 venous ulcers were randomly assigned to hydrocolloid or conventional dressing and compression therapy at four study centers. The ulcers had been present for a mean of 47.8 in the control and 46.2 weeks in the treatment group and 42% of all patients had recurrent ulcers. Ulcers treated with hydrocolloid dressings reduced 71% and control treated wounds reduced 43% in area after 7.2 weeks of treatment. Thirty-four percent of all ulcers healed. Mean time to healing was 7 weeks for the hydrocolloid dressing group and 8 weeks for the control group. Most ulcers were less painful at final evaluation, but reduction in pain was more pronounced in hydrocolloid-dressed ulcers (p = 0.03). At baseline as well as during follow-up, significant differences between study centers were observed. Ulcers in patients in the United Kingdom were larger and less likely to heal (p = 0.001). Size of the ulcer at baseline was associated with treatment response and time to healing (p = 0.002). Percent reduction in ulcer area after 2 weeks was also correlated with treatment outcome (p = 0.004) and time to healing (p = 0.002). When all treatment outcome predictors were analyzed together, only percent reduction in area after 2 weeks remained statistically significant (p = 0.002), with percent reduction during the first 2 weeks of treatment > 30% predicting healing.

Aged↗
PubMed1994

Correlates of ventricular ectopic activity in isolated systolic hypertension. SHEP Cooperative Research Group.

Ventricular ectopic activity was recorded at baseline in 5.6% of the 12-lead electrocardiograms and 8.2% of the 2-minute rhythm strips of 4674 subjects with isolated systolic hypertension (systolic blood pressure 160 to 219 mm Hg, diastolic blood pressure < 90 mm Hg) participating in the Systolic Hypertension in the Elderly Program (SHEP). In this study 1.3% had 6 to 10 ventricular premature beats (VPB), and 0.7% had > 10 VPB on the 2-minute rhythm strip. Correlates of VPB presence on the 12-lead ECG were older-age male sex, presence of Q/QS pattern and higher heart rate. Participants with serum potassium < 3.5 mmol/L had a higher prevalence of VPB. Similarly, the number of VPB on the 2-minute rhythm strip was associated with male sex, increasing age, with lower serum potassium, history of palpitations, and presence of Q/QS patterns.

Aged↗
PubMed1994

Atrial natriuretic peptide metabolism during pregnancy in the rat.

OBJECTIVE: Our purpose was to determine whether plasma clearance rates and production rates of atrial natriuretic peptide 99-126 are altered during pregnancy in the rat. STUDY DESIGN: Twelve virgin and 12 late-pregnant chronically instrumented, conscious, unrestrained Sprague-Dawley rats were studied. Mean arterial pressure, heart rate, and plasma atrial natriuretic peptide levels were measured before and during a 40-minute continuous infusion of atrial natriuretic peptide (10 ng/kg/min). RESULTS: Control mean arterial pressure was 106 +/- 5 mm Hg in virgin rats versus 97 +/- 4 mm Hg in pregnant rats. Atrial natriuretic peptide infusion did not significantly affect mean arterial pressure in either group of animals but decreased heart rate in virgin rats. Basal plasma atrial natriuretic peptide levels were significantly higher in virgin than in pregnant rats (107 +/- 10 vs 78 +/- 7 pg/ml, respectively, p < 0.05). Atrial natriuretic peptide infusion significantly increased plasma levels in both groups to similar (183 +/- 19 and 154 +/- 14 pg/ml, virgin vs pregnant rats). Calculated plasma clearance rates were similar in virgin and pregnant rats (166 +/- 27 vs 155 +/- 17 ml/kg/min). Estimated production rates of atrial natriuretic peptide were higher in virgin then in pregnant rats (15.1 +/- 1.4 vs 11.4 +/- 1.1 ng/kg/min, p < 0.05). CONCLUSIONS: Plasma atrial natriuretic peptide levels are lower in chronically instrumented near-term pregnant rats compared with levels in virgin rats. This is not related to differences in plasma atrial natriuretic peptide clearance rates but rather to a decrease in production rates in late pregnancy.

Animals↗
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

HIMAA workforce survey 1991/1992.

In 1991, and again in 1992, the Health Information Management Association of Australia (HIMAA), formerly Medical Record Association of Australia (MRAA), distributed a Workforce Survey to all members to collect information about the demographic, professional and employment characteristics of HIMAA members. There was a response rate 66.8% in 1991 and 40% in 1992, which rise to 80.9% in 1991 and 51.7% in 1992 for responses from full members. The collection will continue on an annual basis, providing a cumulative database and the opportunity for trend analysis.

Age Distribution↗
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↗