Crosses of NOD mice with the related NON strain. A polygenic model for IDDM

Chromosome locations of non-major histocompatibility complex (MHC) genes contributing to insulin-dependent diabetes mellitus (IDDM) in mice have been determined by outcrossing NOD mice to other inbred strains congenic for the NOD MHC haplotype (H2g7). At least nine non-MHC IDDM susceptibility genes (Idd) were previously identified at first backcross (BC1) after outcross of NOD to C57BL/10.H2g7 congenic mice (B10.H2g7). We investigated whether the same set of Idd loci segregated with IDDM susceptibility after outcross of NOD to NON.H2g7 congenic mice. Since the outcrosses to NON.H2g7 and B10.H2g7 were performed in the same vivarium, direct comparisons were made of the chromosomal locations and relative strengths of Idd alleles in diabetic progeny from the two different outcrosses. In comparison with the NOD x B10.H2g7 outcross, the NOD x NON.H2g7 outcross produced significantly higher IDDM frequencies in F1, F2, and BC1 generations. The high F2 diabetes frequency allowed evaluation of the effects of homozygous expression of both the susceptibility and the resistance allele at Idd loci. This analysis demonstrated that no single non-MHC Idd locus was essential for the onset of diabetes in this cross. After outcross to NON.H2g7, Idd4 (chromosome [Chr] 11), Idd5 (Chr 1), and Idd8 (Chr 14) did not segregate with IDDM in either the BC1 or the F2 generation. Diabetogenic NOD-derived alleles at Idd2 (Chr 9), Idd3 (Chr 3), and Idd10 (Chr 3) were segregating in the BC1. An NON-derived allele contributing to susceptibility on Chr 7 (Idd7) was also detected. Dominant traits, detectable only in the F2 cross, were encoded by Chr 4 (Idd9) and two newly mapped loci on Chr 13 (Idd14) and 5 (Idd15). A third dominant trait was encoded by Chr 6 (possibly Idd6), but here, in contrast to Idd9, Idd14, and Idd15, the NON allele was diabetogenic. Stepwise logistic regression analysis of the BC1 and F2 data confirmed that the ability to identify certainty of the non-MHC Idd loci was contingent on the extent of homozygosity for NOD background genes. This study shows that the diabetogenic phenotype can be achieved through the actions of variable combinations of MHC-unlinked genes and a diabetogenic MHC haplotype.

Susceptibility to human type 1 diabetes at IDDM2 is determined by tandem repeat variation at the insulin gene minisatellite locus

The IDDM2 locus encoding susceptibility to type 1 diabetes was mapped previously to a 4.1-kb region spanning the insulin gene and a minisatellite or variable number of tandem repeats (VNTR) locus on human chromosome 11p15.5. By 'cross-match' haplotype analysis and linkage disequilibrium mapping, we have mapped the mutation IDDM2 to within the VNTR itself. Other polymorphisms were systematically excluded as primary disease determinants. Transmission of IDDM2 may be influenced by parent-of-origin phenomena. Although we show that the insulin gene is expressed biallelically in the adult pancreas, we present preliminary evidence that the level of transcription in vivo is correlated with allelic variation within the VNTR. Allelic variation at VNTRs may play an important general role in human disease.

Successful in vitro fertilization and pregnancy in a patient with autoimmune chronic active hepatitis and cirrhosis

Fertility is reduced in women with chronic active autoimmune hepatitis (AIH) and pregnancy is hazardous. This report describes a 33 year old woman with AIH and cirrhosis in whom a successful pregnancy was achieved following in vitro fertilization/embryo transfer. Disease exacerbation during pregnancy was controlled by azathioprine and an increased dose of prednisone, and a healthy child was delivered by Caesarean section at 36 weeks gestation. Since the perinatal care of preterm infants and the obstetric care available to women with complicated medical problems has improved markedly in recent years and since active disease can be controlled by adequate immunosuppressive therapy, we propose that it is justified to allow these patients access to in vitro fertilization programmes.

Low density lipoprotein receptor and 3-hydroxy-3-methylglutaryl coenzyme A reductase gene expression in human mononuclear leukocytes is regulated coordinately and parallels gene expression in human liver

The liver plays a key regulatory role in cholesterol metabolism. Two proteins are central in this role; the LDL receptor and 3-hydroxy-3-methylglutaryl CoA reductase (HMG CoA reductase), the rate-limiting enzyme in cholesterol biosynthesis. In the current investigation, we have used a sensitive nonradioactive method to study the regulation of LDL receptor and HMG CoA reductase mRNA levels in liver biopsy samples and freshly isolated mononuclear leukocytes from 13 patients who underwent cholecystectomy for gallstones. mRNA copy numbers were determined by PCR amplification of reverse-transcribed RNA using synthetic RNA as an internal standard. Incorporation of digoxigenin-11-dUTP during amplification allowed direct detection and quantitation of mRNA levels by chemiluminescence. These experiments showed that the average number of LDL receptor mRNA molecules in liver (21 +/- 3 x 10(4)/micrograms of RNA) and mononuclear leukocytes (24 +/- 3 x 10(4)/micrograms of RNA) are indistinguishable, whereas the number of HMG CoA reductase molecules in liver (107 +/- 15 x 10(4)/micrograms of RNA) is smaller than that in mononuclear leukocytes (158 +/- 21 x 10(4)/micrograms of RNA, P < 0.05). These numbers correspond to an average of 1-6 copies of LDL receptor mRNA and 5-42 copies of HMG CoA reductase mRNA per cell. There was a significant correlation between the numbers of LDL receptor (P = 0.0005) and HMG CoA reductase (P = 0.003) mRNA molecules in liver and mononuclear leukocytes. Furthermore, the numbers of copies of HMG CoA reductase and LDL receptor mRNA were correlated with each other in both liver (P = 0.02) and mononuclear leukocytes (P = 0.01), consistent with coordinate regulation. These data demonstrate that the mechanisms which regulate mRNA levels in liver and mononuclear cells are similar and suggest that freshly isolated mononuclear cells can be used to predict HMG CoA reductase and LDL receptor mRNA levels in liver.

Measurement of mRNA by quantitative PCR with a nonradioactive label

This report describes the development of a method to measure mRNA in small samples of human tissue by the polymerase chain reaction with a nonradioactive label. In this method RNA is reverse-transcribed in the presence of a control RNA, and subsequently amplified by the polymerase chain reaction during which a nonradioactive label (digoxigenin-11-dUTP) is incorporated. Gel blotting and immunological detection of digoxigenin followed by a chemiluminescent reaction provide an intense signal on film. This allows the detection and quantitation of 3-hydroxy-3-methylglutaryl (HMG) CoA reductase mRNA in 12 ng of RNA. We demonstrate that this is a sensitive and reproducible method, and that quantitation is linear with respect to the amount of mRNA present. The application of this method to the measurement of low density lipoprotein receptor and 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA levels in circulating peripheral blood mononuclear cells and human liver biopsy samples is discussed. The use of chemiluminescent reagents instead of radioactive labels allows this procedure to be performed safely in laboratories not equipped for radioactivity.

Liver, lipoproteins and disease: I. Biochemistry of lipoprotein metabolism

Cholesterol is a structural component of biological membranes and an immediate precursor for steroid hormones and bile acids. The liver is central to the production and removal of cholesterol-rich lipoproteins and bile acids. The basic biochemical aspects of hepatic lipoprotein and cholesterol metabolism and how abnormalities in liver function impair these metabolic pathways are reviewed.

Liver, lipoproteins and disease: II. Clinical relevance of disordered cholesterol metabolism in liver disease

The alterations in the concentration and composition of lipoproteins that occur in liver disease indicate the central role of the liver in lipoprotein metabolism. A number of studies have characterized plasma lipoproteins in patients with liver disease, although in most cases the underlying molecular defects responsible for the changes are still undetermined.

Markers of chronic alcohol ingestion in patients with nonalcoholic steatohepatitis: an aid to diagnosis

We report here the use of the biochemical marker desialylated transferrin to aid in the diagnosis of nonalcoholic steatohepatitis. Conventional biochemical tests used for the detection of chronic alcohol consumption fail to differentiate nonalcoholic steatohepatitis patients from alcoholic subjects. In addition, even in those alcoholic subjects with alcoholic liver disease in whom biopsy has been performed, it is impossible to differentiate these two disease states on the basis of morphological examination alone. In this study we have examined two new markers of excessive alcohol intake, desialylated transferrin and mitochondrial AST in subjects with nonalcoholic steatohepatitis and in patients consuming excessive amounts of alcohol. All nonalcoholic steatohepatitis patients consumed minimal or no alcohol and were diagnosed by morphological criteria based on liver biopsy specimens. Alcoholic subjects were consuming in excess of 80 gm/day ethanol, often with clinical evidence of overt alcoholism. Control subjects included both healthy controls and patient controls with liver diseases unrelated to alcohol. The ratio of desialylated transferrin/total transferrin was elevated only in patients who consumed excessive amounts of alcohol, whereas the ratio of mitochondrial AST to total AST (mitochondrial AST/total AST) was not significantly different between alcoholic subjects and patients with nonalcoholic steatohepatitis. The sensitivity and specificity for the ratio desialylated transferrin/total transferrin was 81% and 98%, respectively, whereas the sensitivity for the mitochondrial AST/total AST ratio was 92%; the specificity was only 50%, indicating that there were a large number of false-positives. All the conventional markers were less sensitive and less specific than the ratio desialylated transferrin/total transferrin.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in chronic hepatocerebral degeneration following liver transplantation

Chronic progressive hepatocerebral degeneration with spastic paraparesis, dementia, dysarthria, ataxia, tremor, and neuropsychiatric symptoms follows long-standing portal-systemic shunting, is associated with structural changes in the central nervous system, and does not respond to conventional therapy for hepatic encephalopathy. A case of advanced chronic liver disease with severe, progressive hepatocerebral degeneration after 23 yr of portal-systemic shunting is reported in whom there was significant objective improvement in intellectual function and in the chronic neurological signs 3 mo after orthotopic liver transplantation and further improvement 12 mo after transplantation.

The natural history of nonalcoholic steatohepatitis: a follow-up study of forty-two patients for up to 21 years

Forty-two patients with nonalcoholic steatohepatitis were followed for a median of 4.5 yr (range = 1.5 to 21.5 yr). Except for two patients with lipodystrophy, all were obese; 35 of 42 were women, 26 of 32 were hyperlipidemic and 15 were hyperglycemic. Upper abdominal pain was the most common reason for presentation. Initial liver biopsy specimens showed the presence of macrovesicular fatty infiltration, lobular (acinar) inflammation, apoptosis, Mallory bodies (in four cases) and fibrosis (in 18 cases). Cirrhosis was present at initial diagnosis in one subject and in another two subjects liver biopsy showed marked fibrosis with disturbed architecture. Serial liver biopsy specimens revealed minimal or no apparent progression of the disorder in most of the patients, in keeping with their benign clinical course. However, one patient showed progression from fibrosis to cirrhosis during the 5-yr observation period, and in the patients with extensive fibrosis the liver disease evolved from one of active inflammation to one of inactive cirrhosis without fat or inflammation. The patient with cirrhosis later died of hepatocellular carcinoma. The severity or type of hepatic change did not correlate with the degree of obesity, hyperlipidemia or hyperglycemia. However, in individual patients, poorly controlled diabetes and rapid weight loss preceded the onset of steatohepatitis. We conclude that nonalcoholic steatohepatitis is a cause of hepatic inflammation histologically resembling that of alcohol-induced liver disease but usually slowly progressive and of low-grade severity. However, the disorder may ultimately result in cirrhosis. Nonalcoholic steatohepatitis should be distinguished from alcoholic steatohepatitis and recognized as a further cause of "cryptogenic cirrhosis."

Steatohepatitis associated with limb lipodystrophy

Two patients who presented with steatohepatitis had acquired partial lipodystrophy. This association has not previously been well documented. A common pathophysiological mechanism in lipodystrophy, obesity-associated nonalcoholic steatohepatitis, and alcoholic liver disease is possible.

Liveweight gains and carcass traits of high grade Simmental, Hereford, Africander x Hereford and Brahman x Hereford feedlot yearling steers

Sixty-three high grade Simmental (S), 40 Hereford (H), 96 Africander x Hereford (AH) and 33 Brahman x Hereford (BH) steers were fed high concentrate feedlot rations from about 8 months of age to slaughter at about 12 months to compare their suitability for producing feedlot beef. Selection for slaughter was made when estimated fat cover and liveweight were closest to market requirements (6-10 mm rib fat and 320-360 kg, respectively). The steers were slaughtered in 3 groups and their carcasses electrically stimulated. Mean slaughter liveweights and carcass weights were 398 and 212, 350 and 182, 349 and 189, 335 and 181 kg for S, H, AH and BH, respectively. Daily liveweight gains during the 4 months on feedlot rations were 1.53, 1.37, 1.24 and 1.25 kg/steer, respectively. Fat depths at rib 12-1 3 and sacral crest sites for S, H, AH and BH were 6.2 and 8.1, 7.3 and 10.3, 8.0 and 10.4,7.3 and 10.0 mm, respectively. In the same order, yield of saleable meat was 77.4, 75.7, 76.3 and 77.2%, and the S and BH had less fat trim than H and AH. Warner-Bratzler peak force shear values (kg) and cooking loss (%) were 3.4 and 33, 3.6 and 34, 3.9 and 34, 5.0 and 35 for S, H, AH and BH, respectively. There were no commercially important differences between H, AH and BH in terms of fat cover at preferred carcass weights and tenderness. However, feedlot liveweight gain favoured the H. Although S steers had highest liveweight gains, many steers did not have sufficient fat cover until liveweights were above the preferred range.