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Biomedical subjects

D Bushnell

Publications and source records attributed to D Bushnell.

12 recordsLinked to original sources
PubMed1995

Delayed colonic transit in spinal cord-injured patients measured by indium-111 Amberlite scintigraphy.

OBJECTIVE: Constipation is a major problem for patients with chronic spinal cord injury (SCI). However, it is not clear whether abnormal colonic transit is restricted to the rectosigmoid region or involves the entire colon. We assessed regional colonic transit with emphasis on the ascending and transverse segments in patients with chronic SCI and compared the results with those of controls using scintigraphic techniques. METHODS: Seven patients with SCI below T1 and 10 control subjects were studied after oral ingestion of a capsule containing indium-111-labeled Amberlite (Sigma Chemical, St. Louis, MO) pellets. The capsule was coated with a pH-sensitive polymer that prevents disintegration until it reaches the ileocecal region. Assessments of the half-time of emptying and residence time of contents in ascending and transverse segments were made, as well as an assessment of the velocity of contents throughout the entire colon, including the descending colon. RESULTS: A significantly slower half-time of emptying was found in SCI patients (ascending: 29 +/- 27 hr in SCI, 6.81 +/- 3.03 hr in controls, p < 0.01; ascending + transverse: 42 +/- 12 hr in SCI, 15.3 +/- 7.16 hr in controls, p < 0.01). The residence time of the median position of the contents was significantly prolonged in SCI patients (ascending: 31 +/- 23 hr in SCI, 8.75 +/- 4.68 hr in controls, p < 0.05; transverse: 26 +/- 3 hr in SCI, 5.0 +/- 4.4 hr in controls, p < 0.05). Overall, the velocity of the median position of contents throughout the entire colon was significantly lower in SCI (0.63 +/- 0.33 cm/hr in SCI, 2.58 +/- 1.20 cm/hr in controls, p < 0.001). CONCLUSIONS: Patients with chronic SCI have prolonged colonic transit that involves the entire colon. Hence, treatment of constipation in these patients may need to include prokinetic agents as well as local rectal maneuvers.

Adult↗
PubMed1994

Radioimmunoscintigraphy with 111indium labeled CYT-356 for the detection of occult prostate cancer recurrence.

We assessed the safety and ability of the 111indium labeled immunoconjugate 7E11-C5.3-glycyl-tyrosyl-(N,e-diethylenetriaminepentaacetic acid)-lysine (CYT-356) to detect sites of occult prostate cancer in 27 subjects who had undergone radical prostatectomy and whose only evidence of recurrent disease was an increasing (0.8 ng./ml. or greater) serum prostate specific antigen (PSA). All subjects underwent whole body scintigraphy between 2 and 4 days following the radiopharmaceutical injection. Routine blood work and human anti-mouse antibody titers were monitored. Scintigraphic findings were compared with clinical parameters, prostatic fossa biopsy results and conventional imaging techniques. Except for transient hypotension in 1 subject following the second infusion, no side effects or human anti-mouse antibody titers were detected. In 22 subjects 1 or more lesions were detected, of which 11 (50%) were confirmed by biopsy, computerized tomography or magnetic resonance imaging. Of 14 subjects with lesions in the prostatic fossa 13 had biopsies performed, 8 (62%) of which were positive. Magnetic resonance imaging confirmed tumor in the spine and chest computerized tomography findings were compatible with lesions seen in the mediastinum in 1 subject each. There was a statistically significant relationship between detecting a scan abnormality and the initial pathological stage of disease but not with the serum PSA. These data provide preliminary evidence that 111indium labeled CYT-356 can be safely administered and readministered, and it detects sites of occult prostate cancer recurrence in subjects whose PSA is increasing following radical prostatectomy.

Humans↗
PubMed1992

Results of cholescintigraphy in a VA hospital.

In a review of 200 hepatobiliary imaging studies done in a VA hospital over a 5-year period, a sensitivity of 96% and a specificity of 88% were obtained. In a subgroup of 40 patients with alcoholic liver disease, the specificity dropped to 60% although the sensitivity remained high (100%). These data indicated that in patients with alcoholic liver disease a positive DISIDA scan is not diagnostic of acute cholecystitis and cannot be interpreted as an indication for cholecystectomy. Possible modifications of imaging techniques, including delayed imaging and morphine-augmented cholescintigraphy, may prove to increase the specificity of cholescintigraphy in these patients. A prospective study using these modifications would help in determining the current role of cholescintigraphy in the diagnosis of acute cholecystitis in patients with alcoholic liver disease.

Cholecystitis↗
PubMed1991

Cortical blindness and residual vision: is the "second" visual system in humans capable of more than rudimentary visual perception?

We studied 12 patients with static cortical blindness to evaluate residual vision after destruction of area 17 and to assess the visual capacity of the subcortical "second" visual system in humans. In each case, the cause was bilateral infarction of the occipital lobes. Five patients had total blindness, and four had residual rudimentary vision (RRV), characterized by homonymous areas of light perception in the peripheral field and ability to detect moving objects. Only three patients had the ability to read; two of these had spared macular vision, and the other had spared left homonymous hemimaculae and spared temporal crescent. Neuroimaging and visual evoked potentials (VEPs) correlated with the extent of the visual dysfunction. Total destruction of area 17 bilaterally was associated with total permanent visual loss. The larger the amount of spared visual cortex, the better the vision. Positron emission tomography (PET) or single photon emission computed tomography (SPECT) demonstrated retained metabolic activity in islands of preserved area 17 in patients with some residual vision. VEPs were present in totally blind individuals. We conclude that, in humans, useful visual function is preserved only when a critical amount of area 17 is spared. The subcortical second system may participate in the generation of VEPs, but is incapable of conscious visual perception.

Aged↗
PubMed1990

The effect of acute and chronic ethanol administration on gastric emptying in cats.

There continues to be disagreement regarding the effects of ethanol on gastric emptying. This study was designed to assess different degrees of ethanol exposure on gastric emptying. Scintigraphic gastric emptying studies were performed in healthy adult cats and the half time (t1/2) of gastric emptying was obtained from each study. Repeat measures of gastric emptying were again obtained in these cats under the conditions of both acute and chronic ethanol exposure and 24 hr following ethanol withdrawal. Gastric emptying half times were prolonged significantly during acute and chronic exposure to ethanol. The mean value for t1/2 under control conditions was 46.46 min, while for acute and chronic exposure to ethanol the mean t1/2 values were 69.34 and 91.33 min, respectively. In addition, we demonstrated a similar delay in gastric emptying during active withdrawal from alcohol (t1/2 = 70). We conclude that both acute and chronic alcohol exposure significantly delay gastric emptying.

Alcoholic Intoxication↗
PubMed1989

Energetics of kayaking.

The metabolic cost of paddling at low speeds (v) was measured from oxygen uptake (VO2) and anaerobic glycolysis in an annular pool or calculated from submaximal VO2 measured at higher speeds when the kayaker was assisted in overcoming water resistance. Also calculated were the total drag (D) and the net mechanical efficiency (e). Each of the above variables was determined in male (n = 17) and female (n = 7) kayakers ranging in experience from beginners to elite. The VO2 increased with v to a peak of approximately 3.4 l.min-1 (80%-100% of peak VO2 during running) in men and of approximately 2.8 l.min-1 in women, while at higher speeds the additional energy was accounted for by anaerobic glycolysis. In all subjects the energy cost to paddle a given distance (C) increased according to a power function with increasing v. The C was lower for the elite male paddlers than for the unskilled group, while that for elite women was slightly less than that for the elite men. Also the rates of increase of C appeared to be inversely proportional to the subjects' skill. Total D for elite men increased from approximately 15 to 60 N over a range of speeds from 1 to 2.2 m.s-1 while those of unskilled men and skilled women for the same speed range were 10-20 N greater and slightly less, respectively. The e increased linearly, but at a different rate, with increases in v for the unskilled and the elite kayakers (males and females) being 4.2% and 6%, respectively, at v = 1.2 m.s-1.

Adult↗
PubMed1988

Alteration in hematopoietic stem cell seeding and proliferation by both high and low dose rate irradiation of bone marrow stromal cells in vitro.

The mechanism of physiologic alteration by high (HDR) or low dose rate (LDR) (5 or 120 cGy/min) irradiation of plateau-phase bone marrow stromal cell cultures was investigated using a technique of in vitro bone marrow transplantation. Purified stromal cell cultures from C57BL/6J, C3H/HeJ, or (C57BL/6J X DBA2/J)F1 (B6D2F1) mouse marrow were irradiated to doses of 2.5 to 10 Gy at LDR or 10-100 Gy at HDR and were then engrafted in vitro with nonadherent hematopoietic cells from murine continuous bone marrow cultures. Parameters of engraftment quantitated included: (1) numbers of adherent proliferating hematopoietic cell colonies, "cobblestone islands" (2) cumulative production of nonadherent hematopoietic cells over 8 weeks after engraftment, (3) M-CSF, GM-CSF and multi-CSF (IL-3) dependent hematopoietic progenitor cells forming greater than or equal to 50 cell colonies in semisolid medium, (4) cumulative production of CFUs, and (5) number of adherent stromal cells positive for detectable extracellular laminin or collagen type IV (markers of endothelial cells, reticular adventitial cells, or sinus lining cells). There was a decrease in cobblestone island formation between 5 and 10 Gy and this parameter possibly increased at doses of 50 and 100 Gy. There was no difference between HDR and LDR irradiation to 10 Gy. Irradiation to doses above 10 Gy decreased support of engrafted cells forming CFU-GM and CFU-GEMM. Measures of CFUs after 10 Gy were variable but indicated a possible increase with HDR and no effect of LDR at 1 week and a decrease in both HDR and LDR groups at 3 weeks after engraftment. Thus, LDR and HDR irradiation in vitro alter several specific parameters of marrow stromal cell support for engrafted hematopoietic stem cells.

Animals↗