👤 Charles W Hogue

Alcohol abuse is associated with the development of fatty liver disease and also with significant osteopenia in both genders. In this study, we examined ethanol-induced pathology in response to diets with differing fat/carbohydrate ratios. Male Sprague-Dawley rats were fed intragastrically with isocaloric liquid diets. Dietary fat content was either 5% (high carbohydrate, HC) or 45% (high fat, HF), with or without ethanol (12-13 g/kg/day). After 14, 28, or 65 days, livers were harvested and analyzed. In addition, bone morphology was analyzed after 65 days. HC rats gained more weight and had larger fat pads than HF rats with or without ethanol. Steatosis developed in HC + ethanol (HC + EtOH) compared to HF + ethanol (HF + EtOH) rats, accompanied by increased fatty acid (FA) synthesis and increased nuclear carbohydrate response element binding protein (ChREBP) (p < 0.05), but in the absence of effects on hepatic silent mating type information regulation 2 homolog (SIRT-1) or nuclear sterol regulatory binding element protein (SREBP-1c). Ethanol reduced serum leptin (p < 0.05) but not adiponectin. Over time, HC rats developed fatty liver independent of ethanol. FA degradation was significantly elevated by ethanol in both HC and HF groups (p < 0.05). HF + EtOH rats had increased oxidative stress from 28 days, increased necrosis compared to HF controls and higher expression of cytochromes P450, CYP2E1, and CYP4A1 compared to HC + EtOH rats (p < 0.05). In contrast, HC + EtOH rats had no significant increase in oxidative stress until day 65 with no observed increase in necrosis. Unlike liver pathology, no dietary differences were observed on ethanol-induced osteopenia in HC compared to HF groups. These data demonstrate that interactions between diet composition and alcohol are complex, dependent on the length of exposure, and are an important influence in development of fatty liver injury. Importantly, it appears that diet composition does not affect alcohol-associated skeletal toxicity. Show less

Women are at higher risk than men for neurologic complications from cardiac operations. This study identified risk factors for neurocognitive dysfunction after cardiac operations in elderly women. One hundred thirteen postmenopausal women undergoing primary coronary artery bypass grafting, with or without valve operation, underwent psychometric testing and neurologic evaluation the day before operation and 4 to 6 weeks postoperatively. Risk factors assessed for neurologic complications included atherosclerosis of the ascending aorta and apolipoprotein epsilon4 genotype. Postoperative neurocognitive dysfunction was defined as the composite end point of a one standard deviation decrement from baseline on two or more psychometric tests or a new neurologic deficit. Neurocognitive dysfunction was present in 25% of the women 4 to 6 weeks postoperatively. Women with a neurocognitive deficit tended to be older than those without a deficit (72.1 +/- 8.1 vs 69.4 +/- 8.9 years, p = 0.144) and were more likely to have mild atherosclerosis of the ascending aorta, a history of congestive heart failure, longer duration of cardiopulmonary bypass (CPB) and aortic cross-clamping, lower nadir blood pressure during CPB, higher rates of postoperative atrial fibrillation, and longer postoperative hospitalization. Mild atherosclerosis of the ascending aorta, duration of CPB, duration of aortic cross-clamping (p = 0.051), and length of postsurgical hospitalization were independently associated with postoperative neurocognitive dysfunction. Mild atherosclerosis of the ascending aorta, duration of CPB, aortic cross-clamping time, and length of hospitalization, but not apolipoprotein epsilon4 genotype, identified risk for neurocognitive dysfunction after cardiac operation in postmenopausal women. Show less

The EXT family of putative tumor suppressor genes affect endochondral bone growth, and mutations in EXT1 and EXT2 genes cause the autosomal dominant disorder Hereditary Multiple Exostoses (HME). Loss of heterozygosity (LOH) of these genes plays a role in the development of exostoses and chondrosarcomas. In this study, we characterized EXT genes in 11 exostosis chondrocyte strains using LOH and mutational analyses. We also determined subcellular localization and quantitation of EXT1 and EXT2 proteins by immunocytochemistry using antibodies raised against unique peptide epitopes. In an isolated non-HME exostosis, we detected three genetic hits: deletion of one EXT1 gene, a net 21-bp deletion within the other EXT1 gene and a deletion in intron 1 causing loss of gene product. Diminished levels of EXT1 and EXT2 protein were found in 9 (82%) and 5 (45%) exostosis chondrocyte strains, respectively, and 4 (36%) were deficient in levels of both proteins. Although we found mutations in exostosis chondrocytes, mutational analysis alone did not predict all the observed decreases in EXT gene products in exostosis chondrocytes, suggesting additional genetic mutations. Moreover, exostosis chondrocytes exhibit an unusual cellular phenotype characterized by abnormal actin bundles in the cytoplasm. These results suggest that multiple mutational steps are involved in exostosis development and that EXT genes play a role in cell signaling related to chondrocyte cytoskeleton regulation. Show less

The EXT genes are a group of putative tumor suppressor genes that previously have been shown to participate in the development of hereditary multiple exostoses (HME), HME-associated and isolated chondrosarcomas. Two HME disease genes, EXT1 and EXT2, have been identified and are expressed ubiquitously. However, the only known effect of mutations in the EXT genes is on chondrocyte function as evidenced by aberrant proliferation of chondrocytes leading to formation of bony, cartilage-capped projections (exostoses). In this study, we have characterized exostosis chondrocytes from three patients with HME (one with EXT1 and two with EXT2 germline mutations) and from one individual with a non-HME, isolated exostosis. At the light microscopic level, exostosis chondrocytes have a stellate appearance with elongated inclusions in the cytoplasm. Confocal and immunofluorescence of in vitro and in vivo chondrocytes showed that these massive accumulations are composed of actin bundled by 1.5-microm repeat cross-bridges of alpha-actinin. Western blot analysis shows that exostosis chondrocytes from two out of three patients aberrantly produce high levels of muscle-specific alpha-actin, whereas beta-actin levels are similar to normal chondrocytes. These findings suggest that mutations in the EXT genes cause abnormal processing of cytoskeleton proteins in chondrocytes. Show less

Hereditary multiple exostoses (EXT) is an autosomal dominant disorder characterized by the formation of cartilage-capped prominences that develop from the growth centers of the long bones. EXT is genetically heterogeneous, with three loci, currently identified on chromosomes 8q24.1, 11p13, and 19q. The EXT1 gene, located on chromosome 8q24.1, has been cloned and is encoded by a 3.4-kb cDNA. Five mutations in the EXT1 gene have been identified--four germ-line mutations, including two unrelated families with the same mutation, and one somatic mutation in a patient with chondrosarcoma. Four of the mutations identified resulted in frameshifts and premature termination codons, while the fifth mutation resulted in a substitution of leucine for arginine. Loss of heterozygosity (LOH) analysis of chondrosarcomas and chondroblastomas revealed multiple LOH events at loci on chromosomes 3q, 8q, 10q, and 19q. One sporadic chondrosarcoma demonstrated LOH for EXT1 and EXT3, while a second underwent LOH for EXT2 and chromosome 10. A third chondrosarcoma underwent LOH for EXT1 and chromosome 3q. These results agree with previous findings that mutations at EXT1 and multiple genetic events that include LOH at other loci may be required for the development of chondrosarcoma. Show less

Hereditary multiple exostoses (EXT) is an autosomal dominant condition characterized by short stature and the development of bony protuberances at the ends of all the long bones. Three genetic locl have been identified by genetic linkage analysis at chromosomes 8q24.1, 11p11-13 and 19p. The EXT1 gene on chromosome 8 was recently identified and characterized. Here, we report the isolation and characterization of the EXT2 gene. This gene shows striking sequence similarity to the EXT1 gene, and we have identified a four base deletion segregating with the phenotype. Both EXT1 and EXT2 show significant homology with one additional expressed sequence tag, defining a new multigene family of proteins with potential tumour suppressor activity. Show less

Hereditary multiple exostosis (EXT) is an autosomal dominant disorder characterized by bony exostoses at the ends of the long bones. Linkage studies have recently suggested that there are three chromosomal locations for EXT genes, 8q24.1 (EXT1), the pericentric region of 11 (EXT2), and 19p (EXT3). As part of a larger study to determine the frequencies of the three EXT types in the United States, we have ascertained a large multigenerational family with EXT and one family member with a chondrosarcoma. This family demonstrated linkage of the disease to chromosome 11 markers. The constitutional and tumor DNAs from the affected family member were compared using short-tandem-repeat markers from chromosomes 8, 11, and 19. Loss of heterozygosity (LOH) in the tumor was observed for chromosome 8 and 11 markers, but chromosome 19 markers were intact. An apparent deletion of the marker D11S903 was observed in constitutional DNA from all affected individuals and in the tumor sample. These results indicate that the EXT2 gene maps to the region containing marker D11S903, which is flanked by markers D11S1355 and D11S1361. Additional constitutional and chondrosarcoma DNA pairs from six unrelated individuals, two of whom had EXT, were similarly analyzed. One tumor from an individual with EXT demonstrated LOH for chromosome 8 markers, and a person with a sporadic chondrosarcoma was found to have tumor-specific LOH and a homozygous deletion of chromosome 11 markers. These findings suggest that EXT genes may be tumor-suppressor genes and that the initiation of tumor development may follow a multistep model. Show less