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Biomedical subjects

C White

Publications and source records attributed to C White.

At least 163 records · Page 9Linked to original sources
PubMed1995

Use of performance ratios to calculate the economic impact of thin cows in a beef cattle herd.

OBJECTIVE: To determine gross income lost that was attributable to thin cows in a beef cattle herd, to estimate the cost of added nutrition necessary to prevent thin cows in the herd, and to determine the financial outcome of the improved nutritional practices. DESIGN: Prospective, observational study. ANIMALS: Four hundred and twenty-two Santa Gertrudis cows and their calves. PROCEDURE: At pregnancy examination in the fall of 1992, cows were assigned a body condition score (BCS), using a scale of 1 (emaciated) to 9 (obese), and the ratio of the productivity of BCS-3 and BCS-4 cow groups (thin cows), compared with the mean productivity of BCS-5 and BCS-6 cows (cows in good condition), was determined. Measures of productivity evaluated included pregnancy rates, weaning weights, and prices per hundredweight of calves. The performance ratios of BCS-3 and BCS-4 cows were multiplied by the mean gross income of BCS-5 and BCS-6 cows to calculate their gross income. This was then subtracted from the mean income of BCS-5 and BCS-6 cows to estimate the amount of lost gross income per thin cow. The cost of a nutritional program that would prevent thin cows in the herd was subtracted from the lost gross income of the thin cows to yield the amount of increased net income that could be generated from a nutritional program that would maintain cows in the herd at a BCS of 5 or 6. RESULTS: Cows with a BCS of 3 were 0.48 as productive, and cows with a BCS of 4 were 0.74 as productive as the average of the BCS-5 and BCS-6 cows combined. Each BCS-3 cow generated $215.06 less, and each BCS-4 cow generated $107.53 less gross income than the average gross income of BCS-5 and BCS-6 cows. The added cost of nutrition that would have reconditioned BCS-3 and BCS-4 cows to a BCS of 5.5 was $91.48/BCS-3 cow and $43.67/BCS-4 cow. Implementation of the reconditioning nutrition program the previous fall would have resulted in an extra net income of $123.58/BCS-3 cow and $63.86/BCS-4 cow, received over a 2-year period. The 262 thin cows in the herd accounted for a total net income loss of $19,897. CLINICAL IMPLICATIONS: The time of pregnancy examination is a strategic intervention point to estimate the past negative economic impact of thin cows and to implement a plan to prevent these losses in the future. Pregnancy examinations should be performed at least 100 days before the beginning of the calving season, and thin pregnant cows should be sorted into a special group and fed a reconditioning diet that will improve their body condition to an average BCS of 5.5 by the onset of the calving season.

Animal Husbandry↗
PubMed1995

Reduction of patellofemoral contact forces following anterior displacement of the tibial tubercle.

Retropatellar pain often accompanies malalignment syndromes and frequently is attributed to excessive patellofemoral contact stresses. Elevation (anterior displacement) of the tibial tubercle has been recommended to relieve these conditions. The degree to which patellar contact forces are decreased and the extent to which elevation alters medial-lateral forces have not been studied directly. We performed anterior translation of the tibial tubercle in knees from cadavers and measured the effect on the magnitude of the three-dimensional patellofemoral contact force with use of a specially designed 6-degrees-of-freedom force transducer, with the natural patellar articular surface in place. Measurements were made in nine knees (average age 67 years, range 46-92 years). The resultant contact force decreased linearly with increasing tubercle elevations of as much as 2.5 cm. The average reduction per centimeter of elevation was 17% of the force measured with no elevation. Elevation of the tubercle had an inconsistent effect on the medial-lateral component of the contact force. As the elevation was increased, six knees exhibited an increase in the medial-lateral component of the contact force acting medially on the knee and three knees exhibited a decrease in this force component. The results of this study show that, while elevation of the tubercle without medialization reduced the total contact force on the patella, the medial-lateral component of this force was altered in an unpredictable way.

Aged↗
PubMed1995

Clinical experience with patient-controlled and staff-administered intermittent bolus epidural analgesia in labour.

A prospective, randomized study was performed to detail clinical experience with both patient-controlled epidural analgesia (PCEA) and midwife-administered intermittent bolus (IB) epidural analgesia during labour, under the conditions pertaining in a busy obstetric delivery unit. Both methods used 0.125% bupivacaine plus fentanyl, and similar rescue supplementation, although management decisions related to epidural analgesia were made principally by attending midwives. One hundred and ninety-eight women were recruited and data analysed from 167 (PCEA n = 82, IB n = 85). The groups were demographically similar. Median hourly pain scores, ratings of analgesia and satisfaction did not differ. Maximum pain scores were significantly higher in those receiving IB epidural analgesia (P < 0.05). The PCEA group had a significantly higher rate of supplementation and bupivacaine use (P < 0.01), and a longer duration of the second stage of labour (P < 0.03). The relative risk of instrumental delivery with PCEA versus the IB method was 1.57 (CI 1.07-2.38). Experience within our unit with PCEA is contrasted with that of IB epidural analgesia, the method most commonly used; and with that of controlled trials comparing these two methods.

Adolescent↗
PubMed1995

Effects of racist provocation and social support on cardiovascular reactivity in African American women.

It has been speculated that exposure to the chronic stress of racism contributes to the high rates of hypertension among African Americans. Social support may buffer the effects of stress on cardiovascular (CV) health by attenuating stress-induced CV responses that have been linked to hypertension. In this study we investigated the effects of racism and social support on CV reactivity in African American women. Participants showed greater increases in CV and emotional responses while responding and listening to racist provocation. Augmented blood pressure (BP) persisted through recovery following racial stress. Participants receiving no support showed the greatest increases in anger during racist provocation. No significant effects were seen for support on CV reactivity. These results provide some of the first evidence that interactive confrontation with racism elicits significant increases in CV reactivity and emotional distress. Furthermore, individuals receiving less support may be at greater risk for the potentially health-damaging effects of racial stress. These findings may have significant implications for the health of African Americans.

Journal Article↗
PubMed1995

Effectiveness of venlafaxine in patients hospitalized for major depression and melancholia.

BACKGROUND: This study was undertaken to compare the antidepressant efficacy and short-term safety of venlafaxine with those of placebo in hospitalized patients with major depression and melancholia. METHOD: Ninety-three inpatients with a minimum prestudy Montgomery-Asberg Depression Rating Scale (MADRS) score of 25 were treated for up to 4 weeks with either venlafaxine or placebo. Dosage averaged approximately 350 mg/day during Weeks 2 to 4. Efficacy and safety were assessed throughout the study. Efficacy was evaluated using the MADRS, the 21-item Hamilton Rating Scale for Depression (HAM-D), and the Clinical Global Impressions (CGI) scale. Recorded study events, vital signs and body weight measurements, laboratory determinations, physical examinations, and ECG recordings were used to assess safety. RESULTS: Venlafaxine provided significantly greater improvement in the MADRS scores after 4 days and in the HAM-D scores after 1 week than did placebo. Response rate (based on a 50% decrease in MADRS scores) was 65% (30 of 46 patients) for venlafaxine and 28% (13 of 47 patients) for placebo. Significantly more placebo-treated patients (40%; N = 19) than venlafaxine-treated patients (9%; N = 4) discontinued treatment early because of lack of efficacy. Nausea and sweating were the most common events, occurring at a significantly higher rate in the venlafaxine group. CONCLUSION: Venlafaxine is an effective and well-tolerated antidepressant in hospitalized patients with major depression and melancholia.

Adult↗
PubMed1994

High-performance liquid chromatographic assay of cefazolin in rat tissues.

A rapid, sensitive and reproducible high-performance liquid chromatographic (HPLC) assay for cefazolin in rat tissues was developed. Tissue samples were homogenized in distilled water, acidified with 8.5% phosphoric acid, and centrifuged. Cefazolin was isolated from the supernatant by solid-phase extraction on C18 cartridges. The eluate containing cefazolin and internal standard, cephalexin, was injected onto a reversed-phase C18 column and eluted with a mobile phase of 23% methanol in 0.02 M sodium phosphate monobasic (pH 5.0) and detected with UV absorbance at 270 nm. Recoveries of cefazolin were 33.7 +/- 2.5%, 45.4 +/- 2.1%, and 42.9 +/- 1.0% from liver, spleen and lung, respectively. The calibration curves for cefazolin were established at 0.5-1500 micrograms/g in spleen, 0.1-250 micrograms/g in liver and 0.1-75 micrograms/g in lung. The assay was reproducible with within-day and between-day variations of 1-2 and 1-4%, respectively. Application of the assay for tissue distribution of cefazolin in liposomal targeting study was demonstrated.

Animals↗