Biomedical subjects

Larry Nichols

Publications and source records attributed to Larry Nichols.

3 recordsLinked to original sources

PubMed2006

Iron binding saturation and genotypic testing for hereditary hemochromatosis in patients with liver disease.

We compared the results of HFE genotype with tests for iron binding saturation (IBS) in 190 consecutive patients with liver disease using 2 IBS cutoff levels: 45% and 60%. Saturation was more than 45% in 117 patients (61.6%) and more than 60% in 89 (46.8%). The number of patients (10) with the highest-risk HFE genotype (C282Y homozygote) was higher than expected. Elevated IBS cannot be used to predict genotype. There was a modest association of C282Y homozygosity with increased IBS (7 of 10, saturation >45% and 6 of 10, >60%). There was poor correlation of elevated saturation with other genotypes containing 1 or more HFE variants. Patients with a wild-type genotype (lacking HFE variants) and elevated IBS were far more likely to have an iron binding capacity less than 250 microg/dL (<44.8 micromol/L) than those with saturation values less than 45%, suggesting that a significant percentage of elevated IBS test results in liver disease are false-positives associated with decreased synthetic capacity. Nevertheless, an appreciable number of patients with elevated IBS had normal iron binding capacity, indicating the complexity of relationships among iron absorption and binding, disease status, HFE genotype, and other potential modifying factors in liver disease.

Genotype↗

PubMed2003

Smooth muscle cell hypertrophy of renal cortex arteries with chronic continuous flow left ventricular assist.

BACKGROUND: Pathophysiology of long-term continuous flow left ventricular assist is not well described. With many of these devices becoming available, it is important to examine for possible pathologic effects. In this study we examined the relationship between diminished pulsatility and pathologic changes in renal cortical arteries. METHODS: Twenty-nine calves were implanted with various continuous flow left ventricular assist systems in a left ventricle-descending thoracic aorta bypass configuration. Pulsatility was quantified by pulse pressure and pulsatility index. Pathologic changes of the renal cortex arteries were described and evaluated by medial thickness, medial/vascular cross-sectional area ratio, and smooth muscle cell count, to quantify hypertrophy or hyperplasia. Seven calves, which underwent a sham-implant, were used as controls. RESULTS: Systolic arterial pressure, pulse pressure, and pulsatility index were significantly lower and diastolic pressure was significantly higher than before implant in pump-implanted animals. Twenty-three of 29 pumpimplanted calves (79.3%) had medial smooth muscle cell hypertrophy in renal cortex arteries, whereas none of sham-implanted calves had any abnormal lesions. When the pump-implanted calves were grouped according to the presence of smooth muscle cell hypertrophy, there was a clear trend toward lower pump flow rate in calves with lesions. Renal function was within the normal range in all calves. CONCLUSIONS: There appears to be a relationship between smooth muscle cell hypertrophy in renal cortex arteries and continuous flow left ventricular assist. Furthermore, although the pathologic changes are likely multifactorial, these lesions appear to be related to lower pump assist rates.

Animals↗

PubMed2002

Experimental off-pump coronary bypass using a robotic telemanipulation system.

We hypothesized that a high-quality anastomosis between the left internal thoracic artery and the left anterior descending coronary artery could be constructed off-pump using a 4-degrees-of-freedom robotic telemanipulation system, endoscopic myocardial stabilization, and two-dimensional visualization. Nine swine were used. Three ports were created on the left chest for the endoscope and the two robotic arms, and another port was created on the right chest for the endostabilizer. Quality of anastomosis was assessed by angiography, analysis of flow, survival after proximal coronary ligation, and histopathology. All nine anastomoses were completed successfully in 22 +/- 3.6 minutes without the need for repair stitches. Left internal thoracic artery flow was 21.6 +/- 2.5 ml/min with diastolic dominant pattern. Eight animals (89%) survived for 60 minutes with the proximal left anterior descending coronary ligated. Angiographic patency was 100% with Fitzgibbon grade A in all. Histopathology of the anastomosis demonstrated minor changes in the integrity of the endothelium and the internal elastic lamina and absence of medial necrosis. We have demonstrated in our robotic off-pump coronary bypass model that a high-quality anastomosis can be constructed between the left internal thoracic artery and the left anterior descending coronary artery. These results support continued research towards robotic endoscopic off-pump CABG.

Anastomosis, Surgical↗