Chronic overnutrition and modern lifestyles are causing a worldwide epidemic of obesity and associated comorbidities, which is creating a demand to identify underlying biological mechanisms and to devise effective treatments. In rats receiving a high-fat diet (HFD), we analyzed the effects of a 4-wk administration of a novel functional analog of iodothyronines, TRC150094 (TRC). HFD-TRC rats exhibited increased energy expenditure (+24% vs. HFD rats; P<0.05) and body weight (BW) gain comparable to that of standard chow-fed (N) rats [N, HFD, and HFD-TRC rats, +97 g, +140 g (P<0.05 vs. N), and +98 g (P<0.05 vs. HFD)]. HFD-TRC rats had significantly less visceral adipose tissue (vs. HFD rats) and exhibited altered metabolism in two major tissues that are very active metabolically. In liver, mitochondrial fatty acid import and oxidation were increased (+56 and +32%, respectively; P<0.05 vs. HFD rats), and consequently the hepatic triglyceride content was lower (-35%; P<0.05 vs. HFD rats). These effects were independent of the AMP-activated protein kinase-acetyl CoA-carboxylase-malonyl CoA pathway but involved sirtuin 1 activation. In skeletal muscle, TRC induced a fiber shift toward the oxidative type in tibialis anterior muscle, increasing its capacity to oxidize fatty acids. HFD-TRC rats had lower (vs. HFD rats) plasma cholesterol and triglyceride concentrations. If reproduced in humans, these results will open interesting possibilities regarding the counteraction of metabolic dysfunction associated with ectopic/visceral fat accumulation.

Advanced glycation end products (AGEs) contribute significantly to diabetic complications, both macro- and microvascular. TRC4186 is an AGE-breaker that has been evaluated in vitro and in vivo and shown to reduce AGE burden. The aim of this study was to determine the effect of TRC4186 on diabetic cardiomyopathy and nephropathy in obese Zucker spontaneously hypertensive fatty rats (Ob-ZSF1), an animal model of diabetes with progressive cardiac and renal dysfunction. Ob-ZSF1 rats loaded with 0.5% salt were treated with TRC4186, 9 or 27 mg/kg twice daily intraperitoneally or vehicle control and monitored telemetrically throughout the study. Cardiac function was assessed terminally by Millar catheter. Markers of cardiac and renal dysfunction were measured and changes evaluated histopathologically. TRC4186 at 27 mg/kg prevented rise in blood pressure (BP) and also improved cardiac output (CO) secondary to better diastolic relaxation as well as systolic emptying in association with the reduction in afterload. At 9 mg/kg, CO was improved by compensatory increase in pre-load however afterload reduction was not adequate to allow efficient systolic emptying. Brain natriuretic peptide (BNP) and interleukin-6 (IL-6) expression was reduced with treatment. Deterioration in renal function was retarded as evident from albumin to creatinine ratio and renal histopathology. TRC4186, an AGE-breaker, clearly preserved cardiac function and reduced the severity of renal dysfunction in Ob-ZSF1, an animal model with persistent severe hyperglycemia leading to diabetic heart failure and renal failure.

During growth arrest and di erentiation, activity of the E2F family of transcription factors is inhibited by interactions with pRb and the related proteins, p107 and p130. To determine which members of the E2F and pRb families may contribute to growth arrest as lens epithelial cells di erentiate into ®ber cells, we examined the expression of individual E2F species and characterized the E2F protein complexes formed in rat lens epithelia and ®bers. RT/PCR detected all ®ve known members of the E2F family in lens epithelial cells, but only E2F-1, E2F-3, and E2F-5 in ®ber cells. Proteins extracted from lens epithelia of newborn rats formed at least two speci®c complexes with an E2F consensus oligonucleotide. Proteins from lens ®ber cells formed three speci®c complexes, one of which comigrated with an epithelial cell complex. Incubation of epithelial and ®ber cell extracts with an antibody speci®c for p107 demonstrated that two ®ber cell complexes and one epithelial cell complex contained p107. Although the remaining ®ber cell complex did not react with antibodies to pRb or p130 in this assay, a strong reaction with pRb antibody was observed when the electromobility shifted complexes were subsequently immunoblotted (shift/Western assay). Immunocytochemistry con®rmed that pRb protein is present in the nuclei of both epithelial cells and ®ber cells. Immunoblotting of whole cell extracts with pRb antibody showed multiple, phosphorylated forms of pRb in the epithelial cells, but predominantly hypophosphorylated pRb in the ®ber cells. None of the complexes formed with E2F were recognized exclusively by the p130 antibody, although the previously identi®ed p107 complexes reacted weakly. The absence of p130/E2F complexes was correlated with the presence of multiple ubiquitinated forms of p130, especially in the ®ber cells. Thus, although p130/E2F complexes are implicated in the terminal di erentiation of many cell types, in di erentiating lens ®ber cells pRb and p107 seem to be the primary regulators of E2F activity.

The brain is the most compartmentalized organ. It is also highly aerobic. Because nerve cells grow but do not regenerate, the brain is the organ best suited for the accumulation of metabolic errors colocalized in specific areas of the brain over an extended period. Alzheimer's disease (AD) is primarily a neurological disorder of the elderly. It is suggested that this disorder results from the accumulation of such errors, and that AD onset aluminum and iron contribute to but do not necessarily initiate the onset of the disease. In vitro and in vivo evidence summarized here suggests that this is effected by interfering in the utilization of glucose and glucose-6-phosphate, and sequestration of iron by ferritin. 3,Bamyloid precursor proteins (3,-APPs) are normal components of the human brain and some other tissues. Proteolysis of these, presumably by serine proteases, generates a 39 to 42 amino acid long peptide, the a-amyloid (f,-AP). In AD brains, ,B-AP aggregates into plaque, the hallmark of AD brains. Some of the a-APPs also contain a 56 amino acid long segment which inhibits serine proteases. We show that in vitro, at pH 6.5, aluminum activates ,Bchymotrypsin 2-fold and makes it dramatically resistant to protease inhibitors such as bovine pancreatic trypsin inhibitor (bPTI) or its mimic present in the fVamyloid precursor proteins (,B-APPs). Iron and oxygen are reported to favor cross-linking of ,-AP in vitro. Because iron and ferritin are components of neurotic plaques, and acidic pH are reported in AD brains, we suggest that deregulation of iron and aluminum homeostasis permit their colocalization, and contribute to the accumulation of metabolic errors leading to neuronal disorders including the formation of AD (senile) plaques. -Environ Health Perspect 102(Suppl 3): 207-213 (1994)