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Biomedical subjects

R Parker

Publications and source records attributed to R Parker.

285 records · Page 16Linked to original sources
PubMedDate not supplied

Depletion of protein-bound furazolidone metabolites containing the 3-amino-2-oxazolidinone side-chain from liver, kidney and muscle tissues from pigs.

Ten 3-month-old pigs were treated with feed containing 300 mg furazolidone per kg for a period of 7 days, followed by withdrawal periods of 0, 1, 2, 3 or 4 weeks (two per group). The treatment resulted in the formation of protein-bound metabolites containing an intact 3-amino-2-oxazolidinone (AOZ) side-chain that could be chemically released and then detected in liver, kidney and rump muscle tissues even 4 weeks after dosing. In tissues from animals killed at the end of the medication period, 993, 600 and 124 ng of AOZ were released from 1 g of liver, kidney and muscle respectively. In the tissues of the animals killed after a further 4 weeks the corresponding levels were 41, 7 and 10 ng/g respectively. It may be concluded that long withdrawal periods prior to slaughter for human consumption are required for pigs treated with furazolidone, because of the long residence time of protein-bound AOZ and the possibility that it might be released from its protein-bound form in the stomach and subsequently be transformed into a hydrazine.

Animals↗
PubMedDate not supplied

Study of the relationships of physical and mental health to patient satisfaction.

This study examined the relationships of patients' self-report of their physical and mental health to their satisfaction with care received during recent hospitalization. These associations were examined within and across 11 service groups in a mid-Atlantic academic medical center. The sample size of 944 patients was distributed among the service groups, with 68-105 patients in each service. The instruments were a portion of the institution's patient satisfaction survey and the SF-12 (a 12-item generic measure of health status), both administered through telephone interviews. Across all hospital services, the relationships between satisfaction and health were too weak to interpret, with only 0.36% and 0.81% of the variance explained between overall satisfaction with care delivery and physical and mental health, respectively. At the service level, however, a number of significant but weak associations were found between satisfaction and health status in the otolaryngology, orthopedic, cardiothoracic, and transplant populations. Mental health and patients' likelihood to return to the hospital were negatively correlated in the neurology/neurosurgery populations, indicating that at higher levels of mental function, patients reported lower likelihood of their returning to the hospital.

Academic Medical Centers↗
PubMedDate not supplied

Factor structures of Taiwanese teachers' ratings of ADHD: a comparison with U.S. studies.

The purpose of this study was to compare factor structures from Taiwanese teachers' ratings with diagnostic definitions of attention-deficit/hyperactivity disorder (ADHD) as described in the DSM-III-R, DSM-IV, and ICD-10; to examine how factor structures of Taiwanese teachers' ratings of ADHD symptoms compare with factor structures reported in research using school-based American participants; and to examine gender differences. One hundred and twenty-one homeroom teachers from six public elementary schools in Taipei County, Taiwan, rated two boys and two girls randomly selected from their homerooms using the ADHD checklist. Findings from this study support the concurrent validity of the DSM-IV ADHD factor structures of hyperactivity-impulsivity and inattention. Comparability of these findings with school-based U.S. studies suggests the cross-cultural congruency of behaviors associated with ADHD.

Adult↗
PubMedDate not supplied

The effect of allograft meniscal replacement on intraarticular contact area and pressures in the human knee. A biomechanical study.

To define the biomechanical effects of total lateral meniscectomy and of subsequent lateral meniscal allograft replacement on load transmission and distribution across the human knee, we mounted 10 fresh-frozen young human cadaveric knees on a mechanical testing system. Peak pressure and contact area profiles were determined at 0 degrees, 30 degrees, and 60 degrees of knee flexion using pressure-sensitive film and a densitometer. Load transmission profiles were determined for each knee in a sequential test order: 1) intact knee, 2) after lateral meniscectomy, 3) after implantation of size-matched meniscal allograft fixed with bone plugs, and 4) after release of the anterior and posterior horn attachments of the allograft. Total lateral meniscectomy resulted in a 45% to 50% decrease in total contact area. Allograft replacement increased total contact area by 42% to 65% as compared with total meniscectomy at all flexion angles. After release of the anterior and posterior horn attachments, contact area was identical to that after total meniscectomy. Total lateral meniscectomy resulted in a 235% to 335% increase in peak local contact pressure. Allograft replacement decreased these pressures by 55% to 65% at all flexion angles, but they remained significantly greater than those in the intact state. After release of the anterior and posterior horn attachments, contact pressures were identical to those after total meniscectomy. Compared with total meniscectomy, meniscal allograft transplantation significantly increases contact area and decreases peak local contact pressures, but any biomechanical advantages are lost without bone plug fixation of the anterior and posterior horns.

Adult↗
PubMedDate not supplied

Reactivities of an anti-CEA peptide monoclonal antibody.

Synthetic peptides representing different areas of the CEA molecule were used as immunogens for the development of anti-CEA antibodies. Both polyclonal and monoclonal antibodies were generated using peptides composed of CEA amino acid positions 99-128 and 585-613, respectively. One MAb, designated CP4, generated using the CEA peptide 99-128, was chosen for a more detailed analysis of reactivity. MAb CP4 reacts in solid phase RIAs with CEA peptide 99-128 immunogen and purified native CEA. CP4 did not react with purified non-specific cross reacting antigen (NCA), even though there were two single amino acid differences between NCA and CEA in the 29 amino acid peptide. The affinity constants of CP4 for the CEA peptide 99-128 and native CEA are 4.07 x 10(9) M-1 and 5.75 x 10(8) M-1, respectively. When CP4 was reacted with purified CEA in Western blotting experiments, the Mr 180,000 glycoprotein characteristic of CEA was detected, but CP4 reacted to various size entities in tumor cell extracts. The results of liquid competition RIAs showed that the epitope that MAb CP4 recognized on native CEA is not available for binding when CEA is in solution. Physical (adsorption to a solid matrix) or chemical (deglycosylation or formalin-fixation) alteration of CEA is required for binding of CP4 to CEA. MAb CP4 reacted approximately 1,000-fold greater to deglycosylated CEA than native CEA. Immunohistochemical studies using formalin-fixed paraffin-embedded tissue sections demonstrated that, among carcinomas, CP4 reacts selectively with colorectal carcinomas, while normal colon is negative. Although stomach carcinoma is negative, dysplastic lesions and areas of intestinal metaplasia are reactive. Two of 7 normal stomach tissues showed focal cytoplasmic reactivity of the surface epithelium. CP4, therefore, appears to react with an epitope with highly restricted expression in colorectal carcinoma. These studies demonstrate the complexities in dealing with an anti-peptide MAb with reactivity to an epitope which is accessible only under certain conditions.

Amino Acid Sequence↗
PubMedDate not supplied

Comparison of intermittent warm and cold blood perfusion during hypothermic myocardial preservation on functional and metabolic recovery.

Numerous techniques are used to maintain intraoperative heart viability. The studies presented here evaluated heart function and metabolism after various periods of preservation up to 4 hours with intermittent warm and cold blood perfusion. Using a heterotopic heart model cooled to 10 degrees C and maintained for 1, 2, 3, and 4 hours, various preservation techniques were compared. Changes in myocardial metabolism were determined from substrate uptakes and biopsy samples of the left ventricular muscle for high-energy phosphates. Preservation techniques included: (1) sustained hypothermia, (2) 1 or 2 hours of sustained warm blood perfusion with fibrillation, (3) intermittent cold blood perfusion during 2, 3, and 4 hours of preservation, (4) intermittent warm blood perfusion during 2, 3, and 4 hours of preservation and (5) a control group (no preservation). Normothermic fibrillation had no effect on postpreservation functional or metabolic parameters. Sustained hypothermia reduced functional recovery proportional to the length of ischemia. The cold intermittent procedures maintained function and metabolism better than sustained hypothermia, while warm intermittent preservation maintained function and metabolism at control levels throughout the recovery period for all preservation techniques. Changes in ATP mirrored the functional changes. Creatine phosphate (CP) was markedly reduced during heart isolation and preservation and exceeded the control by 100% during reperfusion. For operative procedures of 2 hours or less, functional and metabolic recovery was not affected by the various preservation methods applied. Warm intermittent perfusion during hypothermic preservation offered the best protection for the myocardium. The warming cycles during hypothermia may provide some degree of preconditioning and protect the myocardium during reperfusion.

Animals↗
PubMedDate not supplied

Simplified scoring and psychometrics of the revised 12-item Short-Form Health Survey.

The 12-item Short-Form Health Survey was developed to describe mental and physical health status of adults and to measure the outcomes of healthcare services. Based on testing of the original SF-12 with a group of older adults, a revised scoring system and measurement model of the SF-12 Health Survey was proposed. The purpose of this study was to test the reliability and validity of this revised measurement model and scoring system. Testing was done with a sample of 187 older adults in a continuing care retirement community and a sample of 211 older adults discharged from an acute care setting. There was sufficient evidence for the internal consistency of the revised SF-12 (Cronbach alpha coefficients of 0.72 to 0.89); test retest reliability (r = 0.73-0.86); reliability based on R2 values; and validity based on confirmatory factor analysis, contrasted groups, and hypothesis testing. The revised SF-12 is a valid and reliable measure that can be used with confidence to measure outcomes for older adults.

Aged↗
PubMedDate not supplied

Optimal management of amiodarone therapy: efficacy and side effects.

OBJECTIVES: To review management and dosing guidelines for amiodarone therapy, and discuss the drug's adverse event profile. METHODS: Review of relevant studies and reports. RESULTS: Amiodarone is a highly effective antiarrhythmic drug, but is associated with adverse effects involving several organs. Amiodarone-induced arrhythmia is rare, with frequency of 0.3% in one study. Pulmonary toxicity is the most serious noncardiac side effect (2-17% of patients). Hypersensitivity pneumonitis can appear early in the course of therapy. Interstitial pneumonitis is a more common but insidious pulmonary reaction characterized by cough, low-grade fever, and dyspnea that occurs after months or years of therapy. Clinically important hypothyroidism and hyperthyroidism occur in 2-10% of patients. Optic neuritis or neuropathy in which patients experience decreased or blurred vision may progress to permanent blindness. Abnormalities in liver function tests, especially elevated aminotransferase and alkaline phosphatase levels, are seen in 4-25% of patients. Neurologic side effects were reported in 20-40% of patients, at times associated with tremor, ataxia, peripheral neuropathy, malaise or fatigue, sleep disturbances, dizziness, and headaches. Several types of dermatologic reactions have been reported, including allergic rash, photosensitivity, and blue-gray skin discoloration. The best strategy for early detection of pulmonary toxicity is vigilant clinical follow-up with monitoring of cardiac status and liver and thyroid function, and prescription of the lowest effective dosage. After an initial loading dose, 200 mg/day in many patients maintains arrhythmia control and minimizes the frequency of side effects. CONCLUSION: Amiodarone is a safe and efficacious antiarrhythmic agent when lower dosages are given to patients who are closely monitored and subject to careful follow-up.

Amiodarone↗