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Biomedical subjects

R Benson

Publications and source records attributed to R Benson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Magnetic resonance imaging mapping of brain function. Human visual cortex.

Magnetic resonance imaging (MRI) studies of human brain activity are described. Task-induced changes in brain cognitive state were measured using high-speed MRI techniques sensitive to changes in cerebral blood volume (CBV), blood flow (CBF), and blood oxygenation. These techniques were used to generate the first functional MRI maps of human task activation, by using a visual stimulus paradigm. The methodology of MRI brain mapping and results from the investigation of the functional organization and frequency response of human primary visual cortex (V1) are presented.

Brain Mapping↗
PubMed1990

Leuprolide with and without flutamide in advanced prostate cancer.

In a randomized, double-blind trial for metastatic prostate cancer (Stage D2), 603 men received leuprolide, a gonadotropin-releasing hormone analog that inhibits the release of gonadotropins, coupled with either placebo or flutamide, a nonsteroidal antiandrogen that inhibits the binding of androgens to the cell nucleus. The 303 men receiving androgen blockade with leuprolide and flutamide demonstrated a longer progression-free survival (16.9 vs. 13.9 months, P = 0.039) and an increased median length of survival (35.0 vs. 27.9 months, P = 0.035). In the subgroup of men with minimal disease and good performance status, the advantages of maximal androgen blockade were more pronounced. It is concluded that combined androgen blockade with leuprolide and flutamide was more effective than leuprolide alone for patients with metastatic cancer of the prostate. The therapeutic benefits, although greatest in patients with minimum disease, need to be evaluated in a prospective, randomized fashion in trials specifically designed for men with minimal disease and good performance status. Exploratory analyses using the black race as an explanatory variable were also performed. Black race is associated with shorter survival times and is also associated with other prognostic factors, including recent weight loss, anemia, elevated phosphatase levels, and pain. These findings suggest the need for future studies of the relationship of black race and response to prostate cancer therapy.

Adult↗
PubMed1990

The role of food consumption factors in establishing drug tolerances.

The Center for Veterinary Medicine's food consumption policy was adopted in 1978 before suitable data were available on the consumption of organ meats. Consumption is expressed in terms of amounts expected to be consumed daily by an adult human. Before the Center for Veterinary Medicine (Center) can choose a suitable database to develop a new guideline, the Center must resolve a number of difficult policy choices. After the policy issues are resolved, the Center could use the 1977-78 USDA National Food Consumption survey or an approach based on carcass yield to develop the new guideline.

Animals↗
PubMed1989

A controlled trial of leuprolide with and without flutamide in prostatic carcinoma.

To test the hypothesis that maximal androgen blockade improves the effectiveness of the treatment of prostatic cancer, we conducted a randomized, double-blind trial in patients with disseminated, previously untreated prostate cancer (stage D2). All 603 men received leuprolide, an analogue of gonadotropin-releasing hormone that inhibits the release of gonadotropins, in combination with either placebo or flutamide, a nonsteroidal antiandrogen that inhibits the binding of androgens to the cell nucleus. As compared with the 300 patients receiving leuprolide and placebo, the 303 patients randomly assigned to receive leuprolide and flutamide had a longer progression-free survival (16.5 vs. 13.9 months; P = 0.039) and an increase in the median length of survival (35.6 vs. 28.3 months; P = 0.035). The differences between the treatments were particularly evident for men with minimal disease and good performance status; however, further studies should be conducted in this subgroup. Symptomatic improvement was greatest during the first 12 weeks of the combined androgen blockade, when leuprolide alone often produces a painful flare in the disease. We conclude that in patients with advanced prostate cancer, treatment with leuprolide and flutamide is superior to treatment with leuprolide alone.

Aged↗
PubMed1988

Identification of motor neurons for accessory muscles of inspiration and expiration, pectoralis, trapezius and external oblique: comparison with non-respiratory skeletal muscle.

The motor neurons for the accessory muscles of respiration, pectoralis, trapezius, external oblique, and the rectus abdominis were studied in the spinal cord. The objective was to determine if the localization and morphology of the motor neurons for these muscles bear any distinct relationship to the specialized function of these muscles, serving both as supportive skeletal muscles and as accessory respiratory muscles. In addition, it was of interest to know if the inspiratory role of the pectoralis and trapezius muscles and the expiratory role of the external oblique and rectus abdominis are related to the spatial organization of the motor neurons; this knowledge may be important in the discrimination of influences from afferent connections. The motor neurons for these muscles were retrogradely labeled with true blue and were compared with the triceps motor neurons. All neurons occurred ipsilateral and most labeling occurred in C6-7. The motor neurons for the accessory muscles were mainly confined to the ventrolateral tip of the ventral gray matter. The triceps neurons were dorsolateral to the respiratory related neurons in C6-7. Within the confines of the ventrolateral area, the majority of neurons for the pectoralis were localized medial to ventromedial, those for the trapezius were ventrolateral, and those for the external oblique were in the extreme ventrolateral to ventral sections of C7. No neurons were observed in C2 to T2 for the rectus abdominis. A second neuronal column occurred medioventrally in the ventral gray of C4-6 for the trapezius, and is distinct and separated from the C6-7 cell column.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Photodynamic therapy with hematoporphyrin derivative in the treatment of superficial transitional-cell carcinoma of the bladder.

Photodynamic therapy involves light-induced destruction of tumors containing a photosensitizer such as hematoporphyrin derivative. We conducted a collaborative study to evaluate the efficacy of this form of therapy in treating superficial transitional-cell carcinoma of the bladder. Thirty-seven patients were evaluated and 20 were selected for treatment. A total of 50 papillary tumors and 3 areas of carcinoma in situ were treated. All except two tumors were smaller than 2.5 cm. Assessments for treatment response and toxicity were carried out three months after treatment. The initial diagnosis of one patient was revised after the biopsy material was reviewed, and this patient was not included in the analysis. Complete eradication of all tumors was observed in 9 of 19 patients (47 percent), including those with carcinoma in situ. In the remaining 10 of these 19 patients, 13 tumors could not be eradicated (the overall eradication rate was 37 of 50 tumors [74 percent]), but 9 of the 10 patients had a reduction in tumor size, number, or both of 50 percent or more. We conclude that photodynamic therapy is useful in the treatment of superficial transitional-cell carcinoma of the bladder, but controlled trials will be required to define its place in the treatment of cancer.

Adult↗
PubMed1987

Amebic liver abscess: MR imaging.

Hepatic magnetic resonance (MR) imaging was performed in 12 patients with 13 amebic liver abscesses. While no specific image or intensity pattern was noted, most lesions were round or oval with smooth, well-defined margins; had decreased signal intensity compared with that of liver parenchyma on T1-weighted images and increased signal intensity on T2-weighted images; and had prominent, often multiple rims of variable signal intensity. Signal homogeneity within the abscess was present more often on T1- than on T2-weighted images. Diaphragmatic disruption was seen in two cases on coronal MR images. An amebic empyema was differentiable from sympathetic pleural effusions by its hyperintensity on both T1- and T2-weighted images. In patients who also underwent computed tomography (CT) or ultrasonography (US), no lesion was missed with any modality, and except for shape, no consistent features were found among images obtained with the different modalities. The data suggest that CT, US, and MR imaging are comparably effective in the detection of amebic abscess.

Evaluation Studies as Topic↗
PubMed1986

Cockpit resource management: exploring the attitude-performance linkage.

Measured attitudes regarding cockpit management were contrasted for pilots whose line flying performance was independently evaluated by Check Airmen as above or below average. A highly significant discriminant function was obtained indicating that these attitudes are significant predictors of behavior. The performance of 95.7% of the pilots was correctly classified by the analysis. Implications of the results for cockpit resource management training and pilot selection are discussed.

Aerospace Medicine↗
PubMed1984

Use of extraneous conversation in the teaching of nursing skills.

The purpose of this study was to explore the use of extraneous conversation as a distractor while assessing students' level of skill acquisition in the laboratory. The sample consisted of 50 nursing students enrolled in Introduction to Nursing Methods at a large Midwestern university. Subjects were assigned randomly to experimental and control groups. Extraneous conversation was used as a distractor during skill demonstration of intramuscular injections by the 25 students in the experimental group. The 25 students in the control group were not verbally distracted during skill demonstration. These skill demonstrations were videotaped. Data were collected from three evaluations: during the skill demonstration, a rating was based on the inclusion of critical elements; later on viewing the video tapes, faculty assigned a score to the performance based on the number of elements included; students were re-evaluated in the clinical setting based on guidance given by the instructor, performance of critical and noncritical elements, and the smoothness of the performance. Analysis of data from the ratings of students in the laboratory and from the ratings of students from the video tapes with the Wilcoxon rank-sum test revealed no significant differences (a = .05) in performance for the experimental and control groups. Chi-square analysis of data from the evaluation in the clinical setting indicated that students in the experimental group performed at a higher level than students in the control group.

Attention↗
PubMed1982

Beclomethasone dipropionate enemas for treating inflammatory bowel disease without producing Cushing's syndrome or hypothalamic pituitary adrenal suppression.

Since beclomethasone dipropionate (BDP) is a very potent glucocorticoid and since small oral doses (1 mg) seem to be metabolised (possibly in the gut wall or liver) before they reach the systemic circulation, a study was conducted to find out whether patients with inflammatory bowel disease could be treated with enemas containing small doses of BDP without their acquiring Cushing's syndrome or hypothalamic pituitary adrenal (HPA) suppression. The BDP in the 100 ml enemas used was stable and present in a concentration likely to be therapeutic (0.5 mg/dl). Single overnight BDP enemas, unlike conventional betamethasone (5 mg) enemas, did not interfere with the HPA axis in 6 healthy volunteers. In the double-blind randomised part of the study 2-week courses of BDP or betamethasone enemas were assessed in 9 patients having exacerbations of distal inflammatory bowel disease. The clinical and sigmoidoscopic responses as well as adrenocortical function (judged by the 'Cosyntropin' test) were evaluated on the morning after the last day of a course of enemas. Both types of enemas had similar beneficial effects, but only BDP enemas did not interfere with HPA function. Over a prolonged period, a patient with distal ulcerative colitis had been completely dependent on regular treatment with betamethasone enemas to control his symptoms. Substitution with BDP enemas successfully controlled his bowel symptoms, whilst his cushingoid features and HPA suppression regressed.

Adult↗
PubMed1982

Photochemistry of NH3, CH4 and PH3. Possible applications to the Jovian planets.

Photolysis of NH3 at 185 nm in the presence of a two-fold excess of CH4 results in the loss of about 0.25 mole of CH4 per mole of NH3 decomposed (delta CH4/delta NH3). The loss arises from the abstraction of hydrogen atoms from CH4 by photolytically generated hot hydrogen atoms, the presence of which is established by the constancy of delta CH4/delta NH3 between 298 and 156 K and by the quenching of the abstraction reaction when either H2 or SF6 is added. From the latter result, it can be concluded that NH3 photolysis in the H2-abundant atmosphere of Jupiter is not responsible for the presence of the carbon compounds observed there such as ethane, acetylene, and hydrogen cyanide, but may have had a role in the early atmosphere of Titan. Photolysis of PH3 with a 206 nm light source gives P2H4, which in turn is converted to a red-brown solid (P4?). The course of the photolysis is not changed appreciably when the temperatures is lowered to 157 K except that the concentration of P2H4 increases. The presence of H2 has no effect on the P2H4 yield. Photolysis of 9:1 NH3:PH3 gives a rate of decomposition of PH3 that is comparable with that observed by the direct photolysis of PH3. Comparable amounts of P2H4 and the red-brown solid are also observed. The mechanisms of these photochemical reactions together with their implications to the atmospheric chemistry of Jupiter are discussed. The structures of the compounds responsible for the wide array of colors e.g., brown, red and white, observed in the atmosphere of Jupiter have been the subject of extensive speculation. One theory suggests that these colors are due to organic materials formed by the action of either solar ultraviolet light or electric discharges on mixtures of CH4, NH3 and NH4HS in the Jovian atmosphere (Ponnamperuma, 1976; Khare et al., 1978). An alternative hypothesis is that the colors are due to inorganic compounds resulting from the photolysis of NH4HS and PH3 (Lewis and Prinn, 1970; Prinn and Lewis, 1975). In this paper we will summarize our experiments which were designed to test some of these hypotheses.

Ammonia↗
PubMed1981

Systemic treatment of advanced prostatic cancer: development of a new system for defining response.

The low incidence of measurable or evaluable metastases in patients with prostatic cancer makes evaluation of response difficult. This is particularly true in patients with bone metastases only. With a digital model it is possible to measure quantitatively from the radioisotope bone scan the total area of skeletal involvement by metastatic tumor. Definitions of response in bone have been derived from this model. These response criteria have been compared to response in acid phosphatase determinations and clinical status in a study of 44 patients with advanced prostatic cancer treated with estramustine phosphate. Based on serial quantitative bone scans, serial measurements of acid phosphatase levels and repeat clinical evaluations a system is proposed for defining response to systemic therapy that is applicable to the majority of patients with metastatic prostatic cancer.

Acid Phosphatase↗