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Biomedical subjects

A Cornwell

Publications and source records attributed to A Cornwell.

10 recordsLinked to original sources
PubMed2002

Expression of the bilateral deficit during reflexively evoked contractions.

During maximal contractions, the sum of forces exerted by homonymous muscles unilaterally is typically larger than the sum of forces exerted by the same muscles bilaterally. This phenomenon is known as the bilateral deficit (BLD), and it is suggested that this deficit is due to neural inhibition. It remains unclear, however, whether such inhibition is mediated by supraspinal mechanisms or by reflex pathways at the level of spinal cord. To further study the origin of likely neural influences, we tested for the presence of BLD under the condition of reflexive force generation. Force output and integrated electromyogram (iEMG) (quadriceps femoris) were measured in 17 male participants after initiation of the myotatic patellar reflex under unilateral and bilateral conditions. A significant BLD of 9.26 +/- 1.19 (P = 0.004) and 16.76 +/- 4.69% (P = 0.001) was found for force and iEMG, respectively. However, because similar findings were not evident during maximal isometric knee extensions, it is difficult to predict the contribution of a spinal mechanism to the BLD under the condition of maximal voluntary activation.

Adult↗
PubMed2001

Chronic stretching and running economy.

Research demonstrates an inverse relationship between the range of motion of selected joint movements (flexibility) and running economy. Since stretching exercises have been shown to increase joint range of motion, stretching exercises may be contraindicated for endurance running performance. Hence, this study investigated the influence of a 10-week program of stretching exercises on the oxygen costs of a 10 min sub-maximal (approx. 70% peak VO(2)) treadmill run. Thirty-two (16 female, 16 male) physically active, treadmill accommodated, college students participated in the study. All participants maintained their current activity level, with half the participants (8 female, 8 male) adding a 40 min, 3 days per week session of thigh and calf muscle stretching exercises. After 10 weeks, the stretching group (STR) exhibited a significant (P<0.05) increase (3.1+/-2.2 cm) in the sit-and-reach, while the non-stretching group (CON) experienced no significant (P>0.05) change (0.0+/-0.4 cm). However, neither the STR nor the CON exhibited a significant (P>0.05) change in the O(2) cost for the submaximal run. It is concluded, therefore, that a chronic stretching program does not necessarily negatively influence running economy.

Adult↗
PubMed1997

Relative contributions to the net joint moment for a planar multijoint throwing skill: early and late in practice.

The purpose of this investigation was to determine, for a planar, multijoint throwing skill, if the relative contributions of the components of the net joint moment (NJM) at the elbow and shoulder change after practice. Each participant (N = 7) performed 200 throwing trials equally distributed across 5 consecutive days. Each participant threw a 0.15-kg ball as far as possible using the nondominant arm while the motion of the throwing arm was restrained to a horizontal plans. From video data and body segment inertial estimations, NJMs and NJM components (i.e., generalized muscle moments and motion-dependent moments) were calculated for selected early and late practice trials. Performance (throwing distance) showed an expected improvement from early to late practice. The dynamics analysis indicated that participants increased average NJMs and NJM components at both joints. However, the relative contribution of NJM components, expressed as ratios of those components to the NJM at each joint, did not change after extended practice. Restraining the throwing arm to a horizontal plane may partly explain why no changes were found in the relative contributions of NJM components. The lack of change in moment ratios support a motor strategy of scaling joint moments for faster movements.

Adult↗
PubMed1997

Nutritional status of urban homebound older adults.

The purposes of this study were to assess comprehensively the nutritional status of frail older adults living in an urban area and to identify factors associated with nutritional insufficiency. Subjects were 49 adults aged > or = 65 y followed by the Jefferson County Home Health Department. Twenty-nine percent of the women and 63% of the men had a body mass index (BMI; in kg/m2) < 24. Nineteen percent had serum albumin concentrations < 35 g/L (3.5 g/dL). More than one-half of the subjects reported symptoms of oral health problems. The key dependent variables were serum albumin concentration and BMI. In univariate analyses, a lower BMI correlated with oral symptoms, male sex, increased age, and less education. Lower serum albumin concentrations were associated with advanced age, increased dependence in Activities of Daily Living (ADL), oral symptoms, and presence of a caregiver. A stepwise multiple-regression model for BMI and serum albumin showed that predictors of low BMI were increased age, less education, difficulty in chewing, and absence of dentures. Variables in the model for lower serum albumin concentrations were sex, increased age, increased dependence in ADLs, and wearing of dentures. In a secondary analysis that controlled for age, education level, functional status, and sex, oral symptoms remained associated with lower BMI but not with lower serum albumin concentrations. This study found a high prevalence of undernutrition in urban homebound older adults and suggests that oral health disability may affect nutritional status in this population.

Black or African American↗
PubMed1995

Quantitative electroencephalographic analyses in cocaine-preferring polysubstance abusers during abstinence.

Quantitative electroencephalographic (QEEG) analyses are presented for a group of 90 subjects recovering from polysubstance abuse (median = 90 days abstinent) who preferentially used cocaine. QEEGs showed significant decreases from normal in both absolute and relative delta power and decreased theta power in both absolute and relative power. Significantly increased relative but not absolute alpha and beta power was found. Asymmetry of frontal delta, theta, and alpha power differed from normal with right power greater than left. Globally, reduced interhemispheric coherence was found in delta and theta bands and frontally in the beta band. An atypical EEG pattern was observed in about half of the subjects. This was a paroxysmal-like EEG alpha pattern reminiscent of vertex waves typically associated with drowsiness but lacking the waxing and waning of alpha and the slow lateral eye drift associated with drowsiness.

Adult↗
PubMed1985

Corpus and cervix cancer: a nutritional comparison.

Nutritional parameters of patients with cervical cancer and endometrial cancer were prospectively evaluated. Analysis of anthropometric assessments that were abnormal in as many as 52% of patients indicated little difference between organ sites in mean values or percentage of patients with abnormal values. Biochemical parameters included serum albumin, total iron-binding capacity, copper, zinc, and creatinine height index. An abnormal value was present in as many as 60% of patients. Multiple abnormal values were more likely to be present in patients with endometrial cancer. Abnormal vitamin levels were more commonly present in patients with cervical cancer. When compared to control values, levels of plasma folate, beta carotene, and vitamin C were significantly lower in patients with cervical cancer. Patients with endometrial cancer had significantly lower levels of beta carotene and vitamin C. Analysis of surgical complications suggested a correlation with specific nutritional deficits.

Adult↗
PubMed1985

Nutritional status of patients with untreated cervical cancer. I. Biochemical and immunologic assessment.

A prospective nutritional evaluation of 78 patients with untreated cervical cancer was undertaken. Stage-related abnormal anthropometric measurements were present in 60% of patients. Abnormal biochemical nutritional measurements were found in 67% of patients. Thirty percent of these patients were anergic to usual skin test antigens. The overall incidence of protein-calorie malnutrition was 12.5%; however, the risk was stage-related. Measured parameters were usually adversely affected following a surgical procedure. Although surgical complications were few, the implications of these findings as to the appropriate method and timing of nutritional assessment as well as the possible benefit from nutritional support in malnourished patients with cervical cancer are discussed.

Adult↗
PubMed1985

Nutritional status of patients with untreated cervical cancer. II. Vitamin assessment.

Prospective vitamin assessment was undertaken in 78 patients with untreated cancer of the uterine cervix. At least one abnormal vitamin level was present in 67% of patients while individual levels were abnormal in as many as 38% of patients. Significantly lowered levels of plasma folate, vitamin A, and vitamin C were present. Although most of these vitamins did not correlate with other parameters of protein-calorie malnutrition, the possible preventative and treatment effects of these vitamins require additional investigation.

Avitaminosis↗