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Biomedical subjects

D J Fisher

Publications and source records attributed to D J Fisher.

At least 19 recordsLinked to original sources
PubMed1999

Evaluation of wheat-based thin stillage as a water source for growing and finishing beef cattle.

Two trials were conducted to evaluate the nutritional value of wheat-based thin stillage as a water source for cattle. In Trial 1, 20 large-framed steers were fed a basal diet based primarily on barley grain and barley silage, with ad libitum access to water or thin stillage at one of three DM concentrations (2, 4, and 6.7%) in a completely randomized design. The trial consisted of a 70-d growing period and a finishing phase. In Trial 2, total-tract nutrient digestibility coefficients of the basal diet and water treatments fed in the growing period were determined in a randomized complete block design using 12 medium-framed steers. The results showed that when only DMI from the basal diet was considered, there was a linear reduction (P<.01) in DMI and a linear improvement (P<.01) in the gain:feed ratio with no effect on daily gain as thin stillage DM concentration increased. No differences were detected in DMI or efficiency of gain when total DMI (basal diet and thin stillage) was considered. Carcass traits indicated a trend toward increased (P<.06) carcass fat with increasing thin stillage DM concentration. Results of Trial 2 indicated a linear improvement (P<.05) in apparent digestibility of DM, CP, NDF, and energy of the total diet (basal diet and thin stillage) as thin stillage DM concentration increased. We concluded that supplementing growing and finishing cattle with thin stillage reduced the amount of the basal diet required for gain and improved nutrient utilization.

Animals↗
PubMed1998

Primary hyperparathyroidism caused by a functional parathyroid adenoma in a horse.

A 14-year-old Arabian gelding had weight loss and anorexia of 3 weeks' duration. Results of repeated laboratory tests revealed persistent hypercalcemia and serum phosphorus concentration that was within or less than the reference range. Parathyroid hormone concentration was high. Histologic examination of specimens obtained at necropsy revealed parathyroid adenoma. A diagnosis of primary hyperparathyroidism attributable to a functional parathyroid adenoma was made. Abnormalities in calcium and phosphorus concentrations were similar to those seen with primary hyperparathyroidism in dogs, in which this syndrome is best described. Primary hyperparathyroidism should be considered to be a potential cause of hypercalcemia in horses in which other more common causes of hypercalcemia, such as humoral hypercalcemia of malignancy, nutritional secondary hyperparathyroidism, chronic renal failure, vitamin D toxicosis, and bony or granulomatous disease, are ruled out.

Adenoma↗
PubMed1998

Antigenic properties of recombinant glycosylated and nonglycosylated Pneumocystis carinii glycoprotein A polypeptides expressed in baculovirus-infected insect cells.

Since a continuous culture system is not yet available for the opportunistic fungal pathogen Pneumocystis carinii, obtaining suitable amounts of purified P. carinii antigens free of mammalian-host lung contaminants is difficult. Hence, production of recombinant antigen possessing epitopes found in native P. carinii antigens is critical for immunological studies. We utilized the baculovirus expression vector system (BEVS) in insect cells to determine whether B-cell epitopes present in the protein core of a native P. carinii surface glycoprotein were conserved in the recombinant polypeptide, and to investigate its glycosylation by insect cells. B-cell epitopes were retained, but the insect cells appeared to hyperglycosylate the recombinant protein.

Animals↗
PubMed1998

Biotic factors modifying acute toxicity of aqueous cadmium to estuarine amphipod Leptocheirus plumulosus.

A 96-h exposure to aqueous cadmium (Cd) is the recommended reference toxicity test for 10-day sediment bioassays with the estuarine amphipod, Leptocheirus plumulosus (US EPA 1994). This water-only test was used to assess the influence of organism size, sex, and nutritional status on the sensitivity of laboratory-cultured L. plumulosus to Cd. In addition, the response of field-collected amphipods was compared to similarly sized laboratory animals to assess potential seasonal changes in Cd sensitivity. Lipid content of test organisms was measured in these seasonal experiments and those evaluating effects of nutritional status because of its potential as an indicator of physiological condition. LC50 values of laboratory animals size-sorted on nested 500-, 710-, and 1000-micron mesh sieves, increased with size class: 0.36, 0.65, and 0.88 mg Cd/L, respectively. Gravid females were less sensitive than males or mature females to aqueous Cd. Studies on the influence of the molt cycle on Cd toxicity indicated enhanced sensitivity of immediate postmolt animals that may explain some of the observed differences in Cd tolerance. Nutritional effects were investigated by comparing the sensitivity of fed and starved laboratory-reared amphipods. Starved juveniles and adults were significantly smaller than their fed counterparts and exhibited a 28-43% reduction in lipid content, respectively. However, comparison of LC50 values indicated no significant differences in sensitivity to Cd between starved and fed juveniles (0.23 vs 0.30 mg Cd/L) or adults (0.37 vs 0.52 mg Cd/L). Field-collected amphipods were typically more sensitive to Cd than laboratory animals, regardless of the season, although their lipid content varied, ranging from 6.6% in August to 13.7% in November. Results are discussed with respect to the use and interpretation of toxicity tests with this species.

Animals↗
PubMed1998

Clinical experience with the video-assisted saphenectomy procedure for coronary bypass operations.

BACKGROUND: Leg wound complications after saphenectomy are frequent after coronary bypass operations and have a detrimental effect on postoperative quality of life and treatment cost. To reduce morbidity, we evaluated a new technique of video-assisted vein harvest. METHODS: Between March 1996 and October 1996, 50 patients had video-assisted saphenectomy (VAS) and 40 patients had the standard open technique (control group). An additional 13 patients had both procedures (hybrid group). Level of pain, edema, and wound complications were evaluated at discharge and at 2, 4, and 6 weeks postoperatively. RESULTS: The mean operating time for VAS patients was slightly higher than for control (60.6+/-24.7 minutes versus 53.2+/-21.1 minutes; p > 0.05). The average incision length in VAS patients was 13.8+/-8.8 cm for an average of 3.3 grafts per patient. Three VAS procedures were aborted, two because of time constraints, and one because of bleeding, and a segment of vein was lost to injury. The VAS group had considerably less early postoperative pain than the control group (1.7+/-1.2 versus 4.1+/-1.4 [1 = mild, 10 = severe]; p < 0.005) and edema was similar for both groups. Patients in the hybrid group reported less pain in the VAS-operated leg. Serious wound infection occurred in 4 patients, with 2 patients in the control group requiring reoperation for drainage and flap reconstruction. CONCLUSIONS: Based on this initial experience, VAS harvesting, although initially more time consuming, is a rapidly mastered technique, results in shorter overall incision length, and is associated with considerably less postoperative pain than the standard open technique.

Coronary Artery Bypass↗
PubMed1997

Serratia marcescens outbreak associated with extrinsic contamination of 1% chlorxylenol soap.

OBJECTIVES: To determine risk factors for Serratia marcescens infection or colonization, and to identify the source of the pathogen and factors facilitating its persistence in a neonatal intensive-care unit (NICU) during an outbreak. DESIGN: Retrospective case-control study; review of NICU infection control policies, soap use, and handwashing practices among healthcare workers (HCWs); and selected environmental cultures. SETTING: A university-affiliated tertiary-care hospital NICU. PATIENTS: All NICU infants with at least one positive culture for S marcescens during August 1994 to October 1995. Infants who did not develop S marcescens infection or colonization were selected randomly as controls. RESULTS: Thirty-two patients met the case definition. On multivariate analysis, independent risk factors for S marcescens infection or colonization were having very low birth weight (< 1,500 g), a patent ductus arteriosus, a mother with chorioamnionitis, or exposure to a single HCW. During January to July 1995, NICU HCWs carried their own bottles of 1% chlorxylenol soap, which often were left standing inverted in the NICU sink and work areas. Cultures of 16 (31%) of 52 samples of soap and 1 (8%) of 13 sinks yielded S marcescens. The 16 samples of soap all came from opened 4-oz bottles carried by HCWs. DNA banding patterns of case infant, HCW soap bottle, and sink isolates were identical. CONCLUSIONS: Extrinsically contaminated soap contributed to an outbreak of S marcescens infection. Very-low-birth-weight infants with multiple invasive procedures and exposures to certain HCWs were at greatest risk of S marcescens infection or colonization.

Anti-Infective Agents, Local↗
PubMed1996

Influence of age on the effect of bidirectional cavopulmonary anastomosis on left ventricular volume, mass and ejection fraction.

OBJECTIVES: We sought to identify age-related differences in the ventricular response of patients after bidirectional cavopulmonary anastomosis (CPA) and to compare changes in the ventricular response among children < 3 years of age who underwent CPA with that of age-matched control subjects who had a systemic to pulmonary artery shunt alone. BACKGROUND: Pre-Fontan CPA has been advocated over a systemic to pulmonary artery shunt alone in patients with a single ventricle to facilitate ventricular volume unloading and minimize risk of the Fontan operation. METHODS: Our study evaluated 23 patients who initially received a systemic to pulmonary artery shunt as an initial procedure before subsequent Fontan palliation. In eight of these patients (group I), bidirectional CPA was performed before age 3 years, and in four (group II), it was performed after age 10 years. The remaining 11 patients (group III, age and weight control group for group I) were maintained with their initial shunt until they underwent Fontan palliation. Serial echocardiographic analysis was used retrospectively to evaluate left ventricular volume and mass and systolic pump function (ejection fraction) before and after bidirectional CPA. RESULTS: Through 10 months of follow-up, group I patients showed significant decreases in indexed end-diastolic volume both after CPA (120 ml/m1.5 body surface area vs. 78 ml/m1.5, p = 0.001) and in comparison with values in patients in group II and III, who showed no changes in end-diastolic volume (p < 0.001). Indexed ventricular mass decreased moderately after bidirectional CPA in group I (from 228 g/m1.5 body surface area to 148 g/m1.5) but remained unchanged in groups II and III. The differences in trends between groups I and III were significant (p = 0.03). Ejection fraction decreased significantly in group II versus group I patients (0.48 to 0.27 vs. 0.51 to 0.52, p < 0.05) after CPA. Oxygen saturation measurements before and after bidirectional CPA revealed a significant increase in group I (73% to 86%, p < 0.001) and a decrease in group II (82% to 73%, p < 0.01). CONCLUSIONS: Bidirectional CPA facilitates ventricular volume unloading and promotes regression of left ventricular mass in younger children (< 3 years) in preparation for a Fontan operation. In contrast, bidirectional CPA is of questionable value in older children as a staging procedure for Fontan palliation.

Aging↗
PubMed1996

Echo-planar FLAIR imaging in evaluation of intracranial lesions.

Fluid-attenuated inversion-recovery (FLAIR) imaging is a magnetic resonance imaging technique that improves lesion detection in the brain. This technique suppresses signal from free water in cerebrospinal fluid and maintains the hyperintense lesion contrast of T2-weighted spin-echo imaging. Unfortunately, conventional FLAIR imaging requires a long acquisition time and provides a limited number of sections. A combination of echo-planar imaging and FLAIR imaging offers the image contrast effects of FLAIR imaging and the speed of echo-planar imaging. Clinically, the echo-planar FLAIR technique is most helpful in detecting subtle, early lesions that do not enhance, such as early infarct, demyelinating disease, early infection, and trauma. The increased magnetic susceptibility effect associated with the echo-planar technique can be clinically useful in detecting subtle hemorrhage and cavernous angioma. Echo-planar FLAIR imaging is a practical and efficient means of screening the entire brain in a short time.

Brain Diseases↗
PubMed1996

Regulation of SERCA 2 expression by thyroid hormone in cultured chick embryo cardiomyocytes.

We investigated the role of thyroid hormone in the physiological perinatal increase in cardiac sarcoplasmic reticulum (SR) Ca(2+)-adenosinetriphosphatase (ATPase) expression. We isolated and cultured the cardiomyocytes in 10(-8) M triiodothyronine (T3) for 48 h and then measured SR Ca(2+)-ATPase mRNA and immunodetectable protein contents as well as SR-dependent 45Ca2+ uptake rate. We also examined the effect of T3 on expression of the same gene in monkey kidney CV-1 cells, which do not express thyroid hormone receptors. T3 increased cardiomyocyte SR Ca2+ pump mRNA content by 289 +/- 35%, and immunodetectable SR Ca2+ pump protein content by 255 +/- 44%, and SR-specific 45Ca2+ uptake rate by 189 +/- 22% (P < 0.01 for each). In contrast, T3 had no significant effect on the total cellular RNA or protein contents in the cardiomyocyte, and there was no effect of T3 on Ca(2+)-ATPase mRNA content in the thyroid hormone receptor-negative CV-1 cells. These data demonstrate that T3 increases expression of the cardiac SR Ca2+ pump, that the effect can be localized to the cardiomyocyte, and that the effect is dependent on thyroid hormone receptors. These data are consistent with pretranslational and possibly transcriptional level effect of thyroid hormone on the cardiac SR Ca2+ pump gene (SERCA 2). The gestation-associated increase in thyroid hormone may be at least partially responsible for the previously demonstrated perinatal increase in cardiac SR Ca2+ pump expression.

Animals↗
PubMed1996

Usefulness of turbo spin-echo MR imaging in the evaluation of meniscal tears: comparison with a conventional spin-echo sequence.

OBJECTIVE: Fast (turbo) spin-echo imaging techniques have replaced conventional spin-echo protocols in a large proportion of MR applications, with the principle advantage of decreased imaging time. The choice of echo train length is a key determinant of time savings realized, but the echo train length can also adversely affect image quality if too many echoes are incorporated into an image. Several recent studies have shown conflicting results regarding the usefulness of turbo spin-echo imaging in the evaluation of meniscal tears. We compare a turbo spin-echo sequence that has an echo train length of five with a conventional spin-echo sequence for evaluating meniscal tears. SUBJECTS AND METHODS: Forty knees in 39 consecutive patients referred for MR study of the knee were imaged using both conventional spin-echo and turbo spin-echo sequences. The turbo spin-echo sequence provided both proton density-weighted and T2-weighted images (dual echo technique) with an effective echo-train length of five. Nineteen knees (38 menisci) were studied arthroscopically. The arthroscopic findings were considered the reference standard. Spin-echo and turbo spin-echo images were reviewed retrospectively, and results were compared statistically. RESULTS: Of the 80 menisci evaluated with MR imaging, spin-echo and turbo spin-echo images provided concordant results in 95% of cases, with no statistically significant difference found between the two techniques (p < .05). Seventeen tears were found at arthroscopy in 38 menisci studied. Spin-echo and turbo spin-echo imaging had identical specificities (90%) and similar sensitivities (88% and 82%, respectively). CONCLUSION: This study shows that proton density-weighted sequences with an echo train length of five preserve sufficient high-spatial-frequency information to provide performance similar to that of conventional spin-echo sequences. Our data support the conclusion that fast spin-echo imaging with short echo train length is a reasonable substitute for conventional spin-echo imaging in the evaluation of the knee.

Adult↗
PubMed1995

Resurgence of rabies. A historical perspective on rabies in children.

Wildlife rabies in certain parts of the United States has been increasing. With greater urbanization, many areas have seen an influx of wild animals such as raccoons and foxes that are known wildlife reservoirs of rabies. Rabies encephalitis has been a fatal illness recognized by humans throughout history. The purpose of this review is to examine the history of rabies throughout the world to elucidate the evolution of popular and scientific knowledge of the disease in animals and humans. By examining this development from a pediatric perspective, we gain insight into the prevention and treatment protocols recommended for children today. Pediatricians need to include education about prevention and treatment of rabies exposures in their anticipatory guidance sessions with families.

Animals↗
PubMed1995

Recent insights into the regulation of cardiac Ca2+ flux during perinatal development and in cardiac failure.

Systolic and diastolic cardiac function improve during the transition from fetus to newborn to adult. This perinatal maturation is temporally correlated with and at least partially dependent on subcellular changes in the expression of several gene products that regulate cytosolic Ca2+ concentration. Expression of the Na(+)-Ca2+ exchanger of the sarcolemma is highest in the fetus, whereas expression of the sarcoplasmic reticulum Ca2+ pump and the voltage-dependent Ca2+ channel of the sarcolemma increase in conjunction with the perinatal maturation of cardiac function. Whereas cardiac relaxation in the normal mature heart depends primarily on the sarcoplasmic reticulum Ca2+ pump, relaxation in the fetal heart appears to be more dependent on transsarcolemmal Ca2+ flux. Like the fetal heart during prolonged relaxation, the failing human heart exhibits impaired relaxation and abnormal Ca2+ flux regulation. Although altered expression of several gene products has been demonstrated in the failing heart, the responsible factor(s) remains unknown.

Adult↗
PubMed1995

The effect of contrast dose, imaging time, and lesion size in the MR detection of intracerebral metastasis.

PURPOSE: To evaluate the effect of MR contrast dose versus delayed imaging time on the detection of metastatic brain lesions based on lesion size. METHODS: Contrast MR examinations with gadoteridol were obtained in 45 patients with brain metastases. The patients were divided into two groups: 16 received cumulative standard dose (0.1 mmol/kg) and 29 received cumulative triple dose (0.3 mmol/kg). Both groups were evaluated at two dose levels (lower dose and higher dose) with two separate injections. Each patient received an initial bolus injection of either 0.05 (cumulative standard dose) or 0.1 (cumulative triple dose) mmol/kg of gadoteridol to reach the lower-dose level and underwent imaging immediately and 10 and 20 minutes later. Thirty minutes after injection, an additional bolus injection of 0.05 (cumulative standard dose) or 0.2 (cumulative triple dose) mmol/kg was administered to reach the cumulative higher-dose level (cumulative standard dose, 0.1 mmol/kg; cumulative triple dose, 0.3 mmol). Images were acquired immediately. RESULTS: There was no difference in the detection rate for lesions larger than 10 mm among T2-weighted, lower-dose immediate and delayed, or immediate higher-dose images in both study groups. Lesions smaller than 10 mm had improved detection with delayed imaging in both study groups; however, the immediate higher-dose studies still had the highest detection rate. CONCLUSION: In the evaluation of small central nervous system metastases, either delayed imaging after the injection of standard contrast dose or higher contrast dose may improve their detection, and therefore affect clinical management. Higher contrast dose (cumulative triple dose) studies appear to be more effective than delayed imaging with standard dose.

Brain↗
PubMed1995

Lifelong management of patients with a single functional ventricle: a protocol.

Of the wide variety of congenital heart defects, the single functional ventricle continues to be one of the most enigmatic. Compared with patients who have complex congenital heart defects and 2 functional ventricles, patients with a single functional ventricle have greater surgical and long-term morbidity and mortality, and use more medical resources. Recent investigations have shown that patients with a single functional ventricle often have very satisfactory hemodynamics soon after a modified Fontan repair but then develop dilated cardiomyopathy during the subsequent decade. The cause and pathogenesis of the cardiomyopathy have not yet been determined. Many publications have examined individual aspects of the care of these patients based on retrospective reviews, but very few have provided comprehensive prospective methods for managing patients with a single functional ventricle. We hypothesized that a comprehensive management protocol with regular review of the results would provide a better understanding of the problems encountered in these patients and thus improve long-term outcome. Herein, we present our initial protocol for the lifelong management of patients with a single functional ventricle.

Clinical Protocols↗