Whole-Exome Sequencing identified Olfactory Receptor genes as a key contributor to extreme obesity with progression to nonalcoholic steatohepatitis in Mexican patients: Olfactory receptor genes in obese NASH patients.

INTRODUCTION AND OBJECTIVES: Obesity is a global health problem that triggers fat liver accumulation. The prevalence of obesity and the risk of non-alcoholic steatohepatitis (NASH) among young obese Mexican is high. Furthermore, genetic predisposition is a key factor in weight gain and disrupts metabolism. Herein, we used Whole-Exome Sequencing to identify potential causal variants and the biological processes that lead to obesity with progression to NASH among Mexican patients. MATERIALS AND METHODS: Whole-Exome Sequencing was performed in nine obese patients with NASH diagnosis with a BMI ≥30 kg/m2 and one control (BMI=24.2 kg/m2) by using the Ion S5TM platform. Genetic variants were determined by Ion Reporter software. Enriched GO biological set genes were identified by the WebGestalt tool. Genetic variants within ≥2 obese NASH patients and having scores of SIFT 0.0-0.05 and Polyphen 0.85-1.0 were categorized as pathogenic. RESULTS: A total of 1359 variants with a probable pathogenic effect were determined in obese patients with NASH diagnosis. After several filtering steps, the most frequent pathogenic variants found were rs25640-HSD17B4, rs8105737-OR1I1, rs998544-OR5R1, and rs4916685, rs10037067, and rs2366926 in ADGRV1. Notably, the primary biological processes affected by these pathogenic variants were the sensory perception and detection of chemical stimulus pathways in which the olfactory receptor gene family was the most enriched. CONCLUSIONS: Variants in the olfactory receptor genes were highly enriched in Mexican obese patients that progress to NASH and could be potential targets of association studies.

Autoantibodies to a miRNA-binding protein Argonaute2 (Su antigen) in patients with hepatitis C virus infection.

OBJECTIVES: Chronic liver diseases caused by hepatitis B (HBV) or C virus (HCV) are common worldwide. Despite reports on autoimmunity in viral hepatitis, studies on autoantibodies associated with systemic rheumatic diseases are inconsistent. Testing of a small number of selected autoantibody specificities using ELISA appears to be one reason for inconsistency. Sera from patients with viral hepatitis were tested by immunoprecipitation that will allow unbiased screening of autoantibodies found in systemic rheumatic diseases. METHODS: Ninety Mexican patients (37 male, 53 female, 26 HBV, 6 HBV+HCV, 58 HCV) with chronic viral hepatitis, confirmed by nested or RT-nested-PCR, HBsAg and anti-HCV antibodies, were studied. Autoantibodies were tested by immunofluorescence, immunoprecipitation and ELISA. Specificities were verified using reference sera. RESULTS: Antinuclear antibodies were found in 38% HBV, 17% HBV+HCV, and 28% in HCV. Autoantibodies to Argonaute (Ago2, Su antigen), a microRNA binding protein that plays a key role in RNA-induced silencing complex (RISC), was found in 5% (4/64) of HCV or HBV+HCV coinfected patients but not in HBV (0/26). Anti-Ago2/Su was found in 1/2 of I-IFN-treated case vs. 3/62 in cases without I-IFN. HCV did not have other lupus autoantibodies whereas 19% (5/26) of HBV had anti-U1RNP+Ku, Ro+La, RNA polymerase II, or possible U5snRNPs. CONCLUSIONS: Lupus autoantibodies were uncommon in HCV except anti-Ago2/Su. HCV and I-IFN have many ways to affect TLR signaling, miRNA and miRNA binding protein Ago2/Su. To understand the mechanism of specific targeting of Ago2 in HCV may provide a clue to understand the mechanism of specific autoantibody production.

Effect of Breathwalk on body composition, metabolic and mood state in chronic hepatitis C patients with insulin resistance syndrome.

AIM: To identify the anthropometric, metabolic and mood state in hepatitis C virus (HCV)-infected patients from the west of Mexico and to evaluate the effect of Breathwalk (BW), a combination of walking, synchronized breathing and focussed attention, on those patients. METHODS: In an experimental study, 17 patients with serological and molecular diagnosis of HCV, not receiving pharmacological treatment, were studied. One hour sessions of BW were practiced 3 times at week for six months. Body composition was assessed by electric impedance. Biochemical profiles and insulin resistance (IR) risk was assessed by conventional methods. Mood state was evaluated with specific and open questions at the beginning and at the end of the program. RESULTS: Seventy percent of patients were overweight or obese, and 77% of the patients presented with IR at the beginning of the study. Improvements were observed at the 3rd mo, and statistically significant differences were recorded at the 6th mo using the fitness score (76 vs 83, P < 0.01), in alanine aminotransferase (ALT) (106 +/- 93 U/L vs 59 +/- 32 U/L, P < 0.01), total bilirubin (0.09 +/- 1 mg/dL vs 0.62 +/- 0.2 mg/dL, P < 0.01), ALT/AST ratio (1.04 vs 0.70, P < 0.01), triglycerides (165 +/- 86 mg/dL vs 124 +/- 49 mg/dL, P < 0.01) and the IR risk (4.0 vs 2.7). Most patients (88%) indicated to feel better at the end of BW (P < 0.01). CONCLUSION: Breathwalk has an important effect on body composition, lipid profile and liver enzymes. It is also easy, inexpensive and has a beneficial effect on metabolic and mood state in HCV patients.

Difference of hepatitis B virus genotype distribution in two groups of mexican patients with different risk factors. High prevalence of genotype H and G.

BACKGROUND: Hepatitis B virus (HBV) has been classified in eight genotypes, from A to H (HBV/A to HBV/H). HBV genotypes were determined in two groups with different risk factors. METHODS: Group I consisted of 42 patients with chronic and acute hepatitis and group II with 25 men who have sex with men (MSM). HBV genotypes were determined by DNA sequencing of the S-gene. RESULTS: Both groups differed with respect to genotype distribution (p < 0.001). In group I, there were 31 (74%), 9 (21%) and 2 patients (5%) with HBV/H, HBV/D and HBV/A; respectively. In group II, HBV/H, HBV/A, and HBV/G were found in 13 (52%), 8 (32%) and 4 (16%) cases, respectively. By using an HBV/G-specific PCR, 3 more cases of HBV/G were identified in group II, rising to a total 28%. All HBV/G strains were present in coinfection with other HBV genotypes, 86% with HBV/H, and 14% with HBV/A. CONCLUSIONS: HBV/H predominated in both groups. A high frequency of HBV/G was found in MSM, which was always coinfected with HBV/H or HBV/A. Significant differences in HBV genotype distribution were also found, since HBV/D was present only in patients with liver disease, whereas HBV/G was present only in MSM.

Influence of the -308 TNF-alpha and -174 IL-6 polymorphisms on lipid profile in Mexican subjects.

Polymorphisms in the promoter region of several cytokine genes have been associated with differential cytokine production. Several reports indicate that polymorphisms in the tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) genes are associated with lipid abnormalities. The aim of this study was to identify the genotype frequencies for -308G/ATNF-alpha and -174G/CIL-6 polymorphisms in Mexican subjects and to determine the influence of both polymorphisms on serum lipid levels. Serum lipid concentrations were measured in 100 healthy Mexican subjects. Screening of the -308G/ATNF-alpha and -174G/CIL-6 polymorphisms was performed in all participants using PCR-RFLPs. Genotype frequency for TNF-alpha polymorphism was: 87% GG and 13% GA, whereas IL-6 polymorphism was: 77% GG and 23% GC. The polymorphism frequencies obtained in this study were significantly different to Caucasian populations. High serum levels of triglycerides and total cholesterol were associated with GG genotype of the -308 TNF-alpha polymorphism, as well as low HDL-c levels, but no association was found between the -174 IL-6 polymorphism and serum lipid concentrations. We observed a significant association of the -308 TNF-alpha polymorphism with lipid profile in Mexican subjects. Furthermore, the genotype distribution of -308 TNF-alpha and -174 IL-6 polymorphisms in Mexican Mestizo population similar to populations in different continents may be due to our genetic background influenced by the mixture of Spaniards, Indian and black genes.

Polymorphism of the beta3-adrenergic receptor and lipid profile in patients with rheumatoid arthritis and systemic lupus erythematosus treated with chloroquine.

We investigated the effect of beta 3-adrenergic receptor (beta(3)AR) polymorphism on lipid profiles in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) treated with chloroquine. One hundred sixty-eight subjects were classified into three groups: 61 RA patients, 57 SLE patients, and 50 healthy subjects. All patients fulfilled the 1987 and 1982 classification criteria for RA and SLE, respectively, of the American College of Rheumatology. Demographic data and clinical characteristics of the patients were registered. Fasting lipid profile determination and leukocyte genomic DNA isolation from peripheral blood was performed in all the participants. Screening of the beta(3)-AR gene polymorphic region (exon 1) was done by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Quantitative and qualitative variables were analyzed using analysis of variance (ANOVA) with the LSD and chi(2) tests, respectively. An association between the arg64/arg64 beta(3)-AR genotype and high levels of triglycerides (TG) and very low-density lipoprotein cholesterol (VLDL-c) was found in three RA patients ( P=0.01), two of them taking chloroquine. Arg64/arg64 beta(3)-AR polymorphism may contribute to increased TG and VLDL-c in RA patients, independently of chloroquine treatment.

Genotypes and S-gene variability of Mexican hepatitis B virus strains.

The genotypes and subtypes of 15 Mexican hepatitis B virus strains were determined by sequencing and phylogenetic analysis of the small S-gene. The most predominant strains were found to be divergent genotype/subtype F/adw4 strains (66.6%), followed by A/adw2 (20.0%), D/ayw3 (6.7%), and G/adw2 (6.7%). The S-genes of the Mexican genotype F strains and two Nicaraguan strains described previously formed a subcluster with more than 4% divergence from the other strains within this genotype. The Mexican strains within genotypes A and D showed the highest homology with strains from Europe and the United States. Ten amino acid substitutions not described previously were found in the S-genes of strains from nine chronic carriers, whereas the S gene in strains from six acute hepatitis B patients were highly conserved as compared to their respective genotypes. One genotype F strain from an HBsAg positive chronic carrier had a T to A mutation at position 647, forming a translational stop at codon 216. Two genotype F strains from HBsAg negative chronic carriers had a Val180 instead of an Ala found in the other genotype F strains. This study shows that a divergent genotype F predominates in Mexican strains analyzed, which presented amino acid substitutions not reported previously outside the a determinant.

Evaluation of lipid profile, macular toxicity and clinical manifestations according to APO E genotype in systemic lupus erythematosus and rheumatoid arthritis patients treated with chloroquine.

OBJECTIVE: To investigate the effect of APO E gene polymorphism over lipid profile, macular toxicity and clinical manifestations in RA and SLE patients treated with chloroquine. MATERIALS AND METHODS: We studied 45 RA and 29 SLE patients treated with chloroquine who were classified based on the therapeutic regime of chloroquine into three groups: A) Cumulative dose of 100-300 g, B) >300 g and C) Never received chloroquine. Clinical evaluation, fasting lipid profile, visual field testing and stereoscopic photos of the retina were performed. APO E genotype was determined by PCR-RFLP. RESULTS: Reduced apo B levels in RA and SLE according to the cumulative dose of chloroquine 2/3 APO E genotype in a subset of SLE patients were observed. Macular toxicity was independent of both APO E genotype and cumulative chloroquine dose. CONCLUSIONS: Reduced apo B levels were observed associated to chloroquine treatment and 2/3 APO E genotype.

Rapid and efficient detection of extra-pulmonary Mycobacterium tuberculosis by PCR analysis.

SETTING: The diagnosis of extra-pulmonary tuberculosis (EPTB) remains an important clinical problem, primarily because of the inadequate sensitivity of conventional bacteriologic methods for detecting Mycobacterium tuberculosis in extra-pulmonary specimens. OBJECTIVE: To evaluate whether a IS6110-based polymerase chain reaction (PCR) method can be utilized to detect M. tuberculosis in non-pulmonary specimens. DESIGN: Specimens from 286 Mexican patients with a presumptive clinical diagnosis of EPTB were prospectively examined by Ziehl-Neelsen staining, mycobacterial culture on Löwenstein-Jensen slants, and by PCR. The DNA for PCR was extracted by the buffer lysis method and phenol-guanidine thiocyanate-chloroform. Primers that amplify a 200 bp fragment from the insertion-like M. tuberculosis sequence element IS6110 were utilized. RESULTS: Our results demonstrate that this PCR method is highly specific (100%) for identifying M. tuberculosis from a variety of specimens including cerebrospinal fluid (CSF), pleural fluid, ascitic fluid, pericardial fluid, urine, and lymph node exudate. Moreover, the sensitivity of PCR for detecting M. tuberculosis in CSF (94%), pleural fluid (94%), ascitic fluid and other extrapulmonary specimens (93%) greatly exceeds the sensitivity of conventional smear and culture methods. CONCLUSION: These results demonstrate that PCR can be a highly specific and sensitive aid in the detection of M. tuberculosis from extra-pulmonary specimens.

Metabolism of levormeloxifene, a selective oestrogen receptor modulator, in the Sprague-Dawley rat, Cynomolgus monkey and postmenopausal woman.

1. The metabolic fate of levormeloxifene in the Sprague-Dawley rat, Cynomolgus monkey and postmenopausal volunteer has been investigated. 2. Two doses of [14C]levormeloxifene, 0.7 and 50 mg/kg, were given to the male and female rat and monkey, and a single 20-mg dose to the postmenopausal volunteer. 3. The primary route of excretion in all three species was the faeces. Metabolism was similar in all three species, with demethylation forming the major metabolite in the rat and postmenopausal volunteer. One of the major metabolites in the monkey involved an oxidative ring opening of a pyrrole ring. 4. The main site of metabolism of levormeloxifene is the liver and the majority of the drug and its metabolites is excreted via the faecal route. Metabolic pathways appear to be similar in the three species studied.

Polymorphisms at the Werner locus: II. 1074Leu/Phe, 1367Cys/Arg, longevity, and atherosclerosis.

Werner syndrome (WS) is a progeroid syndrome caused by autosomal recessive null mutations at the WRN locus. The WRN gene encodes a nuclear protein of 180 kD that contains both exonuclease and helicase domains. WS patients develop various forms of arteriosclerosis, particularly atherosclerosis, and medial calcinosis. The most common cause of death in Caucasian subjects with WS is myocardial infarction. Previous studies have identified specific polymorphisms within WRN that may modulate the risk of atherosclerosis. Population studies of the 1074Leu/Phe and 1367Cys/Arg polymorphisms were undertaken to evaluate the role of WRN in atherogenesis. Frequencies of the 1074Leu/Phe polymorphisms in Finnish and Mexican populations revealed an age-dependent decline of 1074Phe/Phe genotype. In Mexican newborns, but not in Finnish newborns, the 1074Leu/Phe and 1367Cys/ Arg polymorphisms were in linkage disequilibrium. Among coronary artery disease subjects, there was a tendency for the 1074Phe allele to be associated with coronary stenosis in a gene dose-dependent manner. Furthermore, the 1367Arg/Arg genotype predicted a lower degree of coronary artery occlusion, as measured by NV50, when compared to the 1367Cys/Cys or 1367Cys/Arg genotypes. However, these tendencies did not achieve statistical significance. Samples from Mexican patients with ischemic stroke showed a trend of haplotype frequencies different from that in a control group of Mexican adults. These data support the hypothesis that WRN may mediate not only WS, but may also modulate more common age-related disorders and, perhaps, a basic aging process.

Differential effect of CCl4 on renal function in cirrhotic and non-cirrhotic rats.

The pathogenesis of renal function alteration associated with liver disease remains to be elucidated. Although different experimental animal models have been utilized in order to explain such pathophysiological state, none of them have completely explained the mechanisms involved. In this study we performed differential hemodynamic, hepatic and renal function alteration studies after induction of acute liver damage via intragastric administration of a single dose of CCl4 to cirrhotic and non-cirrhotic rats. Cirrhotic rats with acute liver damage exhibited a significant decrease in mean arterial pressure followed by a decreased glomerular filtration rate, urinary sodium concentration and an induction of plasma renin concentration and activity. At the same time, a significant association between oliguria and mortality was observed. The renal histopathological studies revealed glomeruli with mesangial hypercellularity and thickening of capillary wall, but not tubular epithelial injury. All these alterations were not detected in the control group, i.e. by non-cirrhotic rats with acute liver damage. This study suggests that the effect of CCl4 on kidney structure and function depends on the functional state of the liver. Since this experimental model of acute liver damage in cirrhotic rats presents hemodynamics and renal function alterations similar to those observed in the hepatorenal syndrome in man, it could be utilized to study the pathogenesis of renal function alterations associated with liver damage.

Polymorphisms at the Werner locus: I. Newly identified polymorphisms, ethnic variability of 1367Cys/Arg, and its stability in a population of Finnish centenarians.

The Werner syndrome gene (WRN) encodes a novel helicase of 1,432 amino acids. Homozygous mutations, all of which result in the truncation of the protein, lead to Werner syndrome. However, little is known about the role of WRN in "normal" aging. We have identified four missense polymorphisms and four conservative polymorphsims in WRN gene. A single study showed that a polymorphism at amino acid 1367 Cys(TTG)/ Arg(CTG) is associated with a variation in risk of myocardial infarction among a Japanese population. The 1367 Cys/Arg polymorphism was examined during aging in three different populations: Finnish, Mexican, and North American. The frequencies of 1367 Cys were higher than those of 1367 Arg in all the populations examined, though the frequencies varied among populations. The frequency of the 1367 Arg allele, thought to be protective against myocardial infarction in a Japanese population, was approximately three times higher in the North American and Finnish adult populations. When newborns and centenarians were compared within the Finnish population, no differences were observed in the proportions of 1367 Cys/Arg across age groups. Within the Finnish population, we confirmed a significant decrease of the APOE epsilon2 allele and an increase in the epsilon4 allele in newborn infants compared with centenarians. Thus, unlike the APOE polymorphism, there is no evidence of an association of this WRN polymorphism with longevity.

Treatment with anti-transforming growth factor beta antibodies influences an altered pattern of cytokines gene expression in injured rat liver.

The role of transforming growth factor beta1 (TGF-beta1) in mediating hepatic inflammation and regeneration after acute liver injury is beginning to be elucidated, yet its in vivo effect on the gene expression of the major pro-inflammatory and anti-inflammatory cytokines produced during that process is unknown. Our previous experiments demonstrated that anti-TGF-beta-treated animals presented profound histological changes as compared with control animals. Therefore, our hypothesis was that by blocking in vivo TGF-beta1 action, with polyclonal anti-TGF-beta antibodies, we could monitor by RT-PCR significative alterations on the gene expression of IL-1beta, IL-6, TGF-beta, TNF-alpha, IL-4 and IL-10 in liver-regenerated rats after administration of a single CCl4 dosing. Accordingly, we here report a completely different pattern of cytokines gene expression amidst those groups of rats. Pro-inflammatory cytokines gene expression in control animals showed a clear-cut pattern peaking at 1-2 days postinjury and declining thereafter. Interestingly, IL-6 was present in the control animals only between 12 and 24 h after CCl4 dosing. In the experimental animals, TGF-beta1 was mainly increased at 4 and 6 days, while IL-6 mRNA was completely absent. IL-1beta mRNA expression was also altered in the experimental rats, albeit TNF-alpha was nearly unaffected. IL-4 was fully absent in control rats, but remarkably expressed in experimental animals throughout the study. IL-10 was also more expressed in experimental animals.

Cypermethrin increases apo A-1 and apo B mRNA but not hyperlipidemia in rats.

The hepatotoxic effect of cypermethrin and the expression of hepatic genes at the mRNA level, as molecular markers of liver damage, were evaluated in rats following exposure to cypermethrin. The expression of hepatic genes was compared with conventional liver functional tests, and correlations were made by studying the liver at the ultrastructural level. Cypermethrin treated rats presented a significant decrease, of 79% and 22%, on the expression of albumin and apo E genes at 5 days, respectively. The levels of apo A-1 and apo B mRNA were increased up to four- and fivefold, respectively. This increase did not correlate with the serum values of HDL and VLDL lipoprotein particles. Intracytoplasmic lipid droplets were observed after the first 2 days following cypermethrin administration, suggesting that apo A-1 and B mRNA were translated but not secreted. There were significant correlations between the low values of the albumin gene expression, the decrease in the HDL concentrations, and the ultrastructural alterations, respectively. These alterations were mainly a large amount and increased size of mitochondria in the animals exposed to cypermethrin. It is concluded that under the experimental conditions used, cypermethrin may alter the metabolism of lipids and proteins in rat liver.

Viscosity regulates apolipoprotein A-1 gene expression in experimental models of secondary hyperlipidemia and in cultured hepatocytes.

This study analyzes the relationship of plasmatic colloid osmotic pressure (PCO) and viscosity with the different hyperlipidemic stages observed in rats with acute liver damage induced by carbon tetrachloride (CCl4) and in rats with nephrotic syndrome induced by puromycin amino nucleoside (PAN). In both animal models viscosity increases were associated with the induction of the hyperlipidemic stage characterized by an increase of high density lipoproteins (HDL) and steady-state levels (SSL) of apo A-1 mRNA. In both animal models PCO decreased at early stages of the disease when hyperlipidemia was characterized principally by an increase of total cholesterol and triacylglycerols, but was not associated with the induction of HDL and apo A-1 mRNA. To confirm the in vivo findings, we studied the effect of viscosity on apo A-1 gene expression in an in vitro model using cultured hepatocytes. When medium viscosity was maintained below physiological values, an induction of the SSL of apo A-1 mRNA was observed. By contrast, when medium viscosity was raised to values similar or higher than the physiological range, the SSL of apo A-1 mRNA decreased steadily and after 24 h incubation an almost total inhibition was observed. These results suggest that in both experimental animal models of secondary hyperlipidemia, small viscosity changes below the physiological range, most probably in the interstitial fluid, can induce apo A-1 gene expression at the mRNA level, and that when viscosity reaches physiological values, apo A-1 gene expression is inhibited. Both effects were shown in cultured hepatocytes.

Antisense S-oligodeoxynucleotides down-regulate TGFbeta-production by Kupffer cells from CCl4-injured rat livers.

TGFbeta is a pleiotropic cytokine involved in multiple physiological and pathophysiological regulatory mechanisms. Since TGFbeta is a disparate modulator of cell recruitment, proliferation and extracellular matrix phenotype for mesenchymal and nonmesenchymal cells, we have been investigating the role of this cytokine in the pathophysiology of liver. In the present paper we investigate which hepatic cell types from CCl4-injured rat livers express TGFbeta mRNA and produce TGFbeta in culture, with the aim of further obliterating its biological activity by means of antisense technology. We performed a series of comprehensive molecular studies of in situ hybridization, northern blots, and RT-PCR and we found that only non-parenchymal cells produce TGFbeta while its expression in hepatocytes was absent. Consistent with the in situ hybridization findings, we observed that Kupffer cells expressed high steady-state levels of TGFbeta mRNA, while circulating monocytes expressed a smaller amount of TGFbeta transcripts. We did not detect TGFbeta gene expression in endothelial cells. These findings were further confirmed by RT-PCR analyses. TGFbeta activity, as measured by inhibition of [3H]thymidine incorporation by Mv 1 Lu mink lung epithelial cells, was down-regulated in culture by antisense phosphorothioate oligonucleotides. These effects of antisense oligomers were dose-dependent and the sense oligonucleotides had no effect at the same concentration.

Hepatic phenylalanine-hydroxylase and tyrosine-aminotransferase mRNA levels in rats adapted to diets with different concentrations of protein.

The effect of dietary protein concentrations on the hepatic expression of phenylalanine hydroxylase (PAH) and tyrosine aminotransferase (TAT) mRNA concentrations was studied in rats adapted to consume diets (18 or 50% casein) in a restricted schedule of 7 h (0900 to 1600) for 5 days. After 6 hours of feeding, TAT mRNA concentrations of rats adapted to 18% casein diet and fed acutely 6, 18 and 50% casein diet were 0.15, 0.84 and 5.08 fold respectively higher than mRNA concentrations of rats before feeding. After 17 hours of fasting, TAT mRNA concentrations of rats previously fed 6, 18 or 50% casein diet were -0.45, 1.76 and 9.11 fold respectively higher than mRNA concentrations of rats before they were fed. PAH mRNA concentrations showed a similar pattern. There was a -0.68, 1.63 and 2.5 fold rise of PAH mRNA concentrations in rats fed 6,18 and 50% casein diet during the feeding period, and -0.86, 2.32 and 9.33 fold rise after 17 hours of fasting. TAT and PAH mRNA concentrations of rats adapted to consume 50% casein diet and then changed to 6% or kept on the 50% casein diet showed a maximum peak 6 hours after the rats began to consume the diet; however, they decreased 5 hours after fasting. These results suggest that increasing concentrations of protein in the diet were able to increase the concentration of TAT and PAH mRNA, possibly in order to eliminate the excess of amino acids consumed. The concentration of TAT and PAH mRNA depended more on the protein content of the diet to which the rats were previously adapted.

Regulation of apo B mRNA expression in liver and intestine during liver regeneration induced by CCl4.

Acute liver damage in CCl4-treated rats is accompanied by a decrease of the lipoprotein particles HDL and VLDL. However, once the regenerative process has occurred both lipoproteins increase to values higher than control. In this study we have further analyzed the molecular mechanism involved in the induction of the hyperlipidemia during liver regeneration in rats treated with CCl4. The expression of apolipoprotein (apo) B gene at the apo B mRNA editing level has been analyzed during the regenerative process of the liver. The percent of apo B-48 and apo B-100 mRNA was determined and compared to the plasma levels of LDL and VLDL. These results confirm the existence of two different hyperlipidemic stages during liver regeneration. Total apo B mRNA is increased in liver and intestine during both hyperlipidemic stages. The ratio of apo B-100/apo B-48 mRNA remains constant during the first hyperlipidemic stage but the serum levels of VLDL are decreased. Then once the regenerative process has occurred, the steady-state levels of total apo B mRNA remaining, increased with higher amounts of apo B-100 than apo B-48. At this experimental time point the high levels of total apo B mRNA correlate with serum levels of VLDL that are significantly higher than control. These results indicate that apo B gene expression is induced at the mRNA level in liver and intestine during liver regeneration affecting the apo B mRNA editing mechanism in a complex manner and suggest further regulation at the translational or post-translational level.