Paraneoplastic optic neuropathy in nasopharyngeal carcinoma--report of a case

A 31-year-old Chinese man developed left optic neuritis with left sectorial field loss as a remote effect of nasopharyngeal carcinoma. The field defect showed interesting fluctuations in response to the dosage of systemic steroid therapy. Neuropathologic findings from an exploratory craniotomy did not show any gross tumour mass around the left optic nerve nor any histological evidence of tumour infiltration. This case illustrates that "optic neuritis" could be a paraneoplastic effect of nasopharyngeal carcinoma.     

Dietary beta-carotene absorption by blood plasma and leukocytes in domestic cats

Three experiments were conducted to study the uptake of oral beta-carotene by blood plasma and leukocytes in domestic cats. In Experiment 1, mature female Tabby cats (12 mo old) were given once orally 0, 10, 20 or 50 mg of beta-carotene and blood taken at 0, 12, 24, 30, 36, 42, 48 and 72 h after dosing. Concentrations of plasma beta-carotene increased in a dose-dependent manner. Peak concentrations were observed at 12-24 h and declined gradually thereafter. The half-life of plasma beta-carotene was 12-30 h. In Experiment 2, cats were dosed daily for six consecutive days with 0, 1, 2, 5 or 10 mg beta-carotene. Blood was sampled once daily at 12 h after each feeding. Daily dosing of cats with beta-carotene for 6 d resulted in a dose-dependent increase in circulating beta-carotene. Experiment 3 was designed to study the uptake of beta-carotene by blood leukocytes. Cats were fed 0, 5 or 10 mg of beta-carotene daily for 14 d. Blood leukocytes were obtained on d 7 and 14 to determine beta-carotene content in whole lymphocytes and in subcellular fractions. Blood lymphocytes took up large amounts of beta-carotene by d 7 of feeding. Furthermore, beta-carotene accumulated mainly in the mitochondria (40-52%), with lower amounts accumulating in the microsomes (20-35%), cytosol (15-34%), and nuclei (1.5-6%). Therefore, domestic cats readily absorb beta-carotene across the intestinal mucosa and transfer the beta-carotene into peripheral blood leukocytes and their subcellular organelles. beta-Carotene uptake kinetics show that some aspects of beta-carotene absorption and metabolism in cats are similar to those of humans.     

Preliminary report on the association of apolipoprotein E polymorphisms, with postoperative peak serum creatinine concentrations in cardiac surgical patients

BACKGROUND: Renal dysfunction after cardiac surgery occurs in up to 8% of patients and is associated with major increases in morbidity, mortality, and cost. Genetic polymorphisms have been implicated as a factor in the progression of chronic renal disease, but a genetic basis for the development of acute renal impairment has not been investigated. The authors therefore tested the hypothesis that apolipoprotein E alleles are associated with different postoperative changes in serum creatinine after cardiac surgery. METHODS: The authors performed a prospective observational study with use of data from 564 coronary bypass surgical patients who were enrolled in an ongoing investigation of apolipoprotein E genotypes and organ dysfunction at a university hospital between 1989-1999. Renal function was assessed among apolipoprotein E genotype groups by comparisons of preoperative (CrPre), peak in-hospital postoperative (CrMax) and perioperative change (DCr) in serum creatinine values. RESULTS: The epsilon4 allele grouping (E2 = 2/2,2/3,2/4; E3 = 3/3; E4 = 3/4,4/4) was associated with a smaller increase in postoperative serum creatinine (perioperative change: E4, +0.17; E3, +0.26; E4, +0.27 mg/dl) and a lower peak postoperative creatinine than the epsilon2 and epsilon3 in univariate and multivariate analysis (peak in-hospital postoperative serum creatinine multivariate P = 0.015 vs. epsilon3, P = 0.038 vs. epsilon2). There was no difference in baseline creatinine among allele groups. CONCLUSIONS: Inheritance of the apolipoprotein epsilon4 allele is associated with reduced postoperative increase in serum creatinine after cardiac surgery, compared with the epsilon3 or epsilon2 allele. This is the first report of a possible genetic basis for acute renal impairment. These data may contribute to renal risk stratification for cardiac surgery and raise questions regarding apolipoprotein E and the pathophysiology of acute renal injury.     

Simulation of damage in a porcine prosthetic heart valve

A model of a bioprosthetic porcine valve has been produced which simulates the non-linear elastic behaviour of the fixed tissue and the re-inforcement of the leaflets by collagen fibre bundles. The loading on the model is a spatially uniform but temporally varying distribution of pressure. Bending is allowed in the tissue of the leaflets and is shown to be significant in determining the behaviour and failure modes of the leaflets. The simulation of the undamaged valve is validated against in vitro pulse duplicator studies and a simple fluid-solid interaction simulation. Progressive damage is introduced into three models of the valve at a location where tears have been commonly found in vivo. It was found that during the opening and closing of the valve the tip of the tears were subject to mode III or tearing displacements, but that in the fully closed or diastolic state the tear tip was subject to mode I or opening displacements such that it would be expected to propagate parallel to the line of attachment to the stent. The tear tip stresses increased with the length of the tear so that the rate of tearing would be expected to increase with length.     

Outcomes of Donation After Circulatory Death Heart Transplantation in Australia

Background

Transplantation of hearts retrieved from donation after circulatory death (DCD) donors is an evolving clinical practice.

A review of the safety and clinical utility of contrast echocardiography

There are limitations to the sensitivity and specificity of conventional two-dimensional echocardiograms in making an accurate diagnosis in certain patient populations. This led to the development of specific contrast-enhancing agents with the following characteristics: small enough to cross the pulmonary capillary bed, remain stable throughout the length of the procedure, do not dissolve in blood, and rapidly cleared from the body with low toxicity. Unfortunately, the use of contrast echocardiography has not taken off as expected. The low take-up rate among clinicians can largely be attributed to the black box warning by the United States Food and Drug Administration in 2007, after the coincidental occurrence of four patient deaths and about 190 severe cardiopulmonary reactions shortly after contrast agent administration. In this article, we address the clinical safety of contrast agents, share our institution’s experience in using it and elaborate on the clinical indications of contrast echocardiography.