Search PubMed⌕ Search

Biomedical subjects

D Bushnell

Publications and source records attributed to D Bushnell.

At least 19 recordsLinked to original sources
PubMed2003

Energy balance of human locomotion in water.

In this paper a complete energy balance for water locomotion is attempted with the aim of comparing different modes of transport in the aquatic environment (swimming underwater with SCUBA diving equipment, swimming at the surface: leg kicking and front crawl, kayaking and rowing). On the basis of the values of metabolic power (E), of the power needed to overcome water resistance (Wd) and of propelling efficiency (etaP=Wd/Wtot, where Wtot is the total mechanical power) as reported in the literature for each of these forms of locomotion, the energy cost per unit distance (C=E/v, where v is the velocity), the drag (performance) efficiency (etad=Wd/E) and the overall efficiency (etao=Wtot/E=etad/etaP) were calculated. As previously found for human locomotion on land, for a given metabolic power (e.g. 0.5 kW=1.43 l.min(-1) VO2) the decrease in C (from 0.88 kJ.m(-1) in SCUBA diving to 0.22 kJ.m(-1) in rowing) is associated with an increase in the speed of locomotion (from 0.6 m.s(-1) in SCUBA diving to 2.4 m.s(-1) in rowing). At variance with locomotion on land, however, the decrease in C is associated with an increase, rather than a decrease, of the total mechanical work per unit distance (Wtot, kJ.m(-1)). This is made possible by the increase of the overall efficiency of locomotion (etao=Wtot/E=Wtot/C) from the slow speeds (and loads) of swimming to the high speeds (and loads) attainable with hulls and boats (from 0.10 in SCUBA diving to 0.29 in rowing).

Algorithms↗
PubMed2003

Association between clinically depressed subgroups, type of treatment and patient retention in the LIDO study.

BACKGROUND: Few data are available with which to evaluate the association between depressed subgroups, type of treatment and patient retention during episodes of major depression. METHOD: This observational study followed 1117 depressed patients over a 12-month period in the primary care setting of six different international sites. The patients were divided into three severity-linked subgroups: moderate to severe depression; moderate depression co-morbid with serious medical conditions; and mild depression. RESULTS: In general, a low dropout rate was found, with significant differences in the rates across the six sites. However, while there was no statistical significance in the association between the three subgroups of depression and overall dropout rates, we did find that older patients were less likely to drop out, more depressed patients were more likely to drop out, and if patients were on antidepressants they were less likely to drop out. Among the three subgroups of depression, patients with moderate depression co-morbid with serious medical conditions received the lowest amount of antidepressants and had the lowest quality of life. CONCLUSION: Although the overall dropout rate in this study was found very low and did differ between the six sites, an association between the use of antidepressants and patient retention was seen. The group of patients with serious co-morbid medical conditions received fewer antidepressants even when the level of their depressive states was taken into consideration. This group was the least satisfied with treatment and had the lowest self-reported quality of life.

Adolescent↗
PubMed2002

111In-pentetreotide versus bone scintigraphy in the detection of bony metastases of neuroblastoma.

Bone scintigraphy (BS) is widely utilized for the assessment of bone metastases (BMs) of neuroblastoma (NB). Since 111In-pentetreotide scintigraphy (PS) has been used to image NB with high sensitivity, we compared the sensitivity and specificity of PS with that of BS for the detection of BMs of NB. Nine patients with NB underwent both PS and BS for staging and/or restaging of their disease. The sensitivity and specificity of both imaging approaches were compared based on the findings of histopathology, other conventional imaging methods and subsequent clinical follow-up. In five of the nine patients, both PS and BS were negative for BMs. Radiographic bone surveys (RBSs) were also negative in these patients, except in one who showed a suspicious tibial lesion, but a computed tomography-guided biopsy failed to show evidence of disease. These patients remained without clinical evidence of BMs after a median duration of more than 15 months (range, 6-19 months). In three of four remaining patients, both PS and BS were positive for BMs, whilst only PS was positive in one patient. Overall, PS showed a greater number of BMs (30 vs. 7) with greater conspicuity compared with BS. The initial experience comparing BS with PS suggests that PS may provide a better assessment of the extent of BMs of NB, and that it may be useful as an adjunct to BS at institutions in which 131I- or 123I-metaiodobenzylguanidine is not available, particularly if BS is negative. In patients with similarly positive BS, PS might still provide unique prognostic information beyond that provided by BS. Further studies are therefore warranted.

3-Iodobenzylguanidine↗
PubMed2000

Promoting mental health after childbirth: a controlled trial of primary prevention of postnatal depression.

OBJECTIVES: To investigate the effectiveness of a psychosocial intervention for the prevention of postnatal depression. DESIGN: A controlled trial. METHOD: Women expecting their first or second child and designated as 'more vulnerable' by the Leverton Questionnaire (LQ) or Crown Crisp Experiential Index (CCEI) were allocated to a preventive intervention (N = 47) or control group (N = 52) by expected date of delivery to provide groups expecting their babies around the same time. Women were assessed at 3 months postnatal. An additional group of women designated as 'less vulnerable' (N = 88) were assessed to confirm the validity of the LQ as a vulnerability measure. RESULTS: Questionnaire measures of mood in first-time mothers invited to the Preparation for Parenthood groups revealed significantly more positive mood than in the group receiving routine care. The median Edinburgh Postnatal Depression Scale (EPDS) score for those invited was 3, compared to 8 for those not invited (p < .005). The diagnosis of depression using the Present State Examination revealed differences for both groups, though it reached statistical significance only with the first-time mothers. Only 19% of the 'more vulnerable' invited first-time mothers were 'borderline' or 'cases' at any time in the first 3 months postnatally compared to 39% of those not invited. The Surviving Parenthood groups for second-time mothers were not successful. CONCLUSION: Some depressions following childbirth can be prevented by brief interventions that can be incorporated with existing systems of antenatal classes and postnatal support groups.

Adult↗
PubMed2000

Two years of intensive glycemic control and left ventricular function in the Veterans Affairs Cooperative Study in Type 2 Diabetes Mellitus (VA CSDM).

OBJECTIVE: The Veterans Affairs Cooperative Study in Type 2 Diabetes Mellitus (VA CSDM) was a multicenter randomized prospective study of 153 male type 2 diabetic patients to assess the ability to sustain clinically significant glycemic separation between intensive and standard treatment arms. A trend toward an excess of combined cardiovascular events in the intensive treatment arm of this trial was reported earlier. The present analysis was done to evaluate the effect of 2 years of intensive glycemic control on the left ventricular (LV) function. RESEARCH DESIGN AND METHODS: The patients were randomized to intensive step treatment with insulin alone or with sulfonylurea (intensive treatment arm [INT], n = 75) or to standard once-daily insulin injection (standard treatment arm [STD], n = 78) treatment. A total of 136 patients (standard treatment arm [STD], n = 70; INT, n = 66) had radionuclide ventriculography at entry and at 24 months for the assessment of LV function. RESULTS: There was no difference in the mean LV ejection fraction (at entry: STD 57.1+/-9.51%; INT 58.1+/-8.7%; at 24 months: STD 57.3+/-10.8%, INT 59.5+/-10.7%), peak filling rate (at entry: STD 2.6+/-0.7 end diastolic volume per second, INT 2.4+/-0.8 end diastolic volume per second; at 24 months: STD 2.7+/-1.0 end diastolic volume per second, INT 2.5+/-0.7 end diastolic volume per second), or time to peak filling rate (at entry: STD 195.3+/-69.5 ms, INT 185.6 +/-62.4 ms; at 24 months: STD 182.6+/-64.8 ms, INT 179.2+/-61.2 ms) between the 2 treatment arms. A subgroup analysis of 104 patients (STD, n = 53; INT, n = 51) that omitted individuals with intervening cardiac events/revascularization or a change in cardioactive medications also showed no difference in the LV function at entry and at 24 months between the 2 groups. Abnormal LV ejection fraction at baseline predicted cardiac events (interval between cardiac beats [RR] = 2.5). CONCLUSIONS: Two years of intensive glycemic control does not affect the LV systolic or diastolic function in patients with type 2 diabetes.

Blood Glucose↗
PubMed1998

NeuroSPECT findings in patients with posttraumatic anosmia: a quantitative analysis.

OBJECTIVE: To investigate quantitative neuroSPECT findings, particularly from orbital frontal cortex, in patients rendered totally anosmic from head injury. SETTING: Veterans Administration (VA) Medical Center. SUBJECTS: Eighteen patients with head injury resulting in severe anosmia and five normal controls. All 18 patients had sustained their head injuries at least 5 years prior to involvement in the study. MEASURES: Quantitative neuroSPECT (count density) from sagittal regions of interest (ROIs) ranging circumferentially from orbital frontal cortex to occipital pole. RESULTS: Quantitative evaluation of neuroSPECT findings for anosmic patients as a group showed substantial orbital frontal hypoperfusion compared with controls, with 67% of individual anosmic patients showing orbital frontal hypoperfusion at a level two or more standard deviations below that of the worst control subject. By contrast, there were no between-group differences for five other ROIs (inferior frontal pole, superior frontal pole, posterior superior frontal lobe, the parasagittal region, and occipital pole), and individual abnormalities were infrequent in these areas. In addition, orbital frontal count was significantly correlated with ratings of outcome, the only ROI to have such a relationship. CONCLUSIONS: Findings strongly suggest that posttraumatic anosmia and the neuropsychological deficits typically associated with posttraumatic anosmia are closely and specifically associated with hypoperfusion in orbital frontal cortex. The results also underscore the importance of posttraumatic anosmia as a clinical sign of orbital frontal damage, which is particularly important in patients with mild head injury who have normal computed tomography and magnetic resonance imaging scans.

Adult↗
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↗