Differential hepatic gene expression in a polygenic mouse model with insulin resistance and hyperglycemia: evidence for a combined transcriptional dysregulation of gluconeogenesis and fatty acid synthesis.

New Zealand obese (NZO) mice exhibit severe insulin resistance of hepatic glucose metabolism. In order to define its biochemical basis, we studied the differential expression of genes involved in hepatic glucose and lipid metabolism by microarray analysis. NZOxF1 (SJLxNZO) backcross mice were generated in order to obtain populations with heterogeneous metabolism but comparable genetic background. In these backcross mice, groups of controls (normoglycemic/normoinsulinemic), insulin-resistant (normoglycemic/hyperinsulinemic) and diabetic (hyperglycemic/hypoinsulinemic) mice were identified. At 22 weeks, mRNA was isolated from liver, converted to cDNA, and used for screening of two types of cDNA arrays (high-density filter arrays and Affymetrix oligonucleotide microarrays). Differential gene expression was ascertained and assessed by Northern blotting. The data indicate that hyperinsulinemia in the NZO mouse is associated with: (i) increased mRNA levels of enzymes involved in lipid synthesis (fatty acid synthase, malic enzyme, stearoyl-CoA desaturase) or fatty acid oxidation (cytochrome P450 4A14, ketoacyl-CoA thiolase, acyl-CoA oxidase), (ii) induction of the key glycolytic enzyme pyruvate kinase, and (iii) increased mRNA levels of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase. These effects were enhanced by a high-fat diet. In conclusion, the pattern of gene expression in insulin-resistant NZO mice appears to reflect a dissociation of the effects of insulin on genes involved in glucose and lipid metabolism. The data are consistent with a hypothetical scenario in which an insulin-resistant hepatic glucose production produces hyperinsulinemia, and an enhanced insulin- and substrate-driven lipogenesis further aggravates the deleterious insulin resistance of glucose metabolism.

Characterisation of the mouse diabetes susceptibilty locus Nidd/SJL: islet cell destruction, interaction with the obesity QTL Nob1, and effect of dietary fat.

AIMS/HYPOTHESIS: The diabetes susceptibility locus Nidd/SJL was identified in an outcross of New Zealand obese (NZO) and lean Swiss/Jackson Laboratory mouse strain (SJL) mice. Here we characterise its effects in a NZO x F1(SJLxNZO) backcross population raised on high-fat or standard diet, and describe its interaction with the obesity quantitative trait locus (QTL) Nob1. METHODS: NZO x F1(SJLxNZO) backcross mice were raised on a normal or high fat diet and were monitored (body weight, blood glucose, serum insulin) for 22 weeks. Genotypes of polymorphic markers were determined by PCR, and linkage analysis was done. Pancreas morphology was assessed by conventional staining and immunohistochemistry of insulin. RESULTS: In backcross mice raised on a high-fat diet, Nidd/SJL produced hyperglycaemia (maximum likelihood of the odds (LOD) score 9.9), hypoinsulinaemia, reduction of islet-cell volume, and loss of beta cells. No effect was observed on body weight and serum insulin concentrations before the onset of hyperglycaemia. The development of diabetes in carriers of Nidd/SJL was markedly accelerated and aggravated by the obesity/hyperinsulinaemia QTL Nob1; together, these loci were responsible for approximately 90% of the diabetes observed in the backcross population. When raised on a standard diet, Nidd/SJL carriers exhibited a fivefold higher prevalence of diabetes, but Nob1 failed to enhance the effect of Nidd/SJL. CONCLUSION/INTERPRETATION: Diabetes in this obese mouse model is the result of an interaction of genes responsible for obesity/insulin resistance (e.g. Nob1) and islet cell failure ( Nidd/SJL). The combined diabetogenic effects of Nidd/SJL and Nob1 were markedly enhanced by a high-fat diet, whereas that of Nidd/SJL alone was independent of the dietary fat content.

Type 2 diabetes-like hyperglycemia in a backcross model of NZO and SJL mice: characterization of a susceptibility locus on chromosome 4 and its relation with obesity.

A backcross model of New Zealand obese mice (NZO) with the lean, atherosclerosis-resistant SJL strain was established to locate genes responsible for obesity, insulin resistance, and type 2 diabetes-like hyperglycemia. In male NZO x F1 backcross mice, a major susceptibility locus for the development of hyperglycemia and hypoinsulinemia (Nidd/SJL) was identified on chromosome 4 between the markers D4Mit278 and D4Mit232, 10-28 cM distal of the previously described Nidd1 locus. The diabetogenic allele has presumably been contributed by the SJL genome, and it appeared to be responsible for approximately 60% of the total prevalence of hyperglycemia. The presence of Nidd/SJL did not alter body weight or weight gain by week 12. Thereafter, it was associated with reduced weight gain or weight loss, presumably as a consequence of decompensated hyperglycemia. In all male backcross mice, the prevalence of hyperglycemia at week 22 increased with the body weight at week 12, suggesting that the development of hyperglycemia was dependent on the degree of obesity. In the absence of Nidd/SJL, mice weighing <50 g at week 12 did not develop hyperglycemia by week 22. In contrast, in animals carrying the diabetogenic allele, the prevalence of hyperglycemia was 20 and 64% when the 12-week weight was <45 and 45-50 g, respectively. These data are consistent with the conclusion that Nidd/SJL represents a diabetes gene that lowers the obesity threshold for the development of hyperglycemia and hypoinsulinemia.

[Insulin resistance and metabolic syndrome]. / Insulinresistenz und metabolisches Syndrom.

The metabolic syndrome represents a complex combination of the symptoms obesity, insulin resistance, dyslipoproteinemia, hypertension, and type 2 diabetes. These components have a heterogeneous genetic basis and appear to be closely linked. Obesity is determined by a polygenic constellation and produces insulin resistance, hypertension and dyslipidemia. In addition, defects in the signal transduction of insulin appear to aggravate the insulin resistance independent of obesity. Type 2 diabetes is produced by a third genetic predisposition and is precipitated by the failure of pancreatic beta-cell to compensate insulin resistance. Because prevalence and course of the diabetes markedly depend on the extent of obesity and insulin resistance, these symptoms of the metabolic syndrome represent crucial targets for preventive and therapeutic strategies.

Targeting of the gene product encoded by ORF UL56 of human cytomegalovirus into viral replication centers.

The highly conserved DNA-binding protein pUL56 of human cytomegalovirus (HCMV) was found to be predominantly localized throughout the nucleus as well as in viral replication centers of infected cells. The latter localization was abolished by phosphono acetic acid, an inhibitor of viral DNA replication. Immunofluorescence revealed that pUL56 co-localized in replication centers alongside pUL112-113 and pUL44 at late times of infection. By co-immunoprecipitations, a direct interaction with pUL44, a protein of the replication fork, was detected. These results showed for the first time that HCMV pUL56 is localized in viral replication centers, implicating that DNA replication is coupled with packaging.

A metabolic syndrome of hypertension, hyperinsulinaemia and hypercholesterolaemia in the New Zealand obese mouse.

BACKGROUND: New Zealand obese (NZO) mice exhibit a polygenic obesity associated with hyperinsulinaemia and hyperglycaemia. Here we show that the strain presents additional features of a metabolic syndrome, i.e. elevated blood pressure, serum cholesterol and serum triglyceride levels. MATERIALS AND METHODS: A back-cross model of NZO mice with the lean Swiss Jackson Laboratory (SJL) strain was established in order to investigate further the correlation between hypertension, obesity, serum insulin and hyperglycaemia. RESULTS: Systolic blood pressure was significantly elevated at 6 weeks of age and appeared to parallel the weight gain of the animals. Serum insulin levels, presumably reflecting insulin resistance, and systolic blood pressure values were significantly correlated with the body mass index (r2 = 0.707 and 0.486, respectively) in the back-cross mice. In contrast, blood pressure was only weakly correlated with serum insulin (r2 = 0.288) in non-diabetic mice, and was independent of serum insulin levels in diabetic animals. CONCLUSION: The data are consistent with the concept that hypertension and insulin resistance are a characteristic consequence of the genetic constellation leading to obesity in the NZO strain, and that these traits reflect related mechanisms. It appears unlikely, however, that hypertension is a direct consequence of hyperinsulinaemia.

Quantitative trait loci for obesity and insulin resistance (Nob1, Nob2) and their interaction with the leptin receptor allele (LeprA720T/T1044I) in New Zealand obese mice.

AIMS/HYPOTHESIS: To locate genes responsible for obesity and insulin resistance, a backcross model of New Zealand obese (NZO) mice with the lean Swiss/Jackson Laboratory (SJL) strain was stablished. RESULTS: In female NZO x F1 backcross mice, two major quantitative trait loci for variables of obesity (body weight, body mass index, total body fat) and insulin resistance (hyperinsulinaemia) were identified on chromosomes 5 (Nob1) and 19 (Nob2) close to the markers D5Mit392 and D19Mit91. The aberrant alleles have presumably contributed by the NZO genome. Whereas Nob1 contributed mainly to higher body weight, Nob2 seemed to mainly aggravate insulin resistance independent of obesity. The leptin receptor variant of NZO (LeprA720T/T1044I) failed to alter any of the variables of obesity. It seemed, however, to enhance the effect of Nob1 on body weight and that of Nob2 on serum insulin concentration. When expressed in COS-7 cells, LeprA720T/T10441 produced a normal basal and maximum activation with a minor increase in the EC50 of leptin. CONCLUSIONS/INTERPRETATION: The data identify two new quantitative trait loci that are responsible for a major part of obesity and hyperinsulinaemia as produced by recessive genes in NZO mice. LeprA720T/T1044I alone cannot produce obesity, but may enhance the effects of other obesity/insulin resistance genes in this mouse model.

Glial development in the Drosophila CNS requires concomitant activation of glial and repression of neuronal differentiation genes.

Two classes of glial cells are found in the embryonic Drosophila CNS, midline glial cells and lateral glial cells. Midline glial development is triggered by EGF-receptor signalling, whereas lateral glial development is controlled by the gcm gene. Subsequent glial cell differentiation depends partly on the pointed gene. Here we describe a novel component required for all CNS glia development. The tramtrack gene encodes two zinc-finger proteins, one of which, ttkp69, is expressed in all non-neuronal CNS cells. We show that ttkp69 is downstream of gcm and can repress neuronal differentiation. Double mutant analysis and coexpression experiments indicate that glial cell differentiation may depend on a dual process, requiring the activation of glial differentiation by pointed and the concomitant repression of neuronal development by tramtrack.

CNS midline development in Drosophila.

The first cells specified during CNS development of vertebrates and invertebrates are the cells located at the midline of the neuroepithelium. In Drosophila the development of these cells requires inductive signals from the mesoderm. Later in CNS development, the midline cells are in turn influencing the flanking neuroectoderm, contributing to the establishment of dorsoventral positional information. During axonal pattern formation the midline cells are required in guiding commissural growth cones towards and across the midline. The midline consists of only few, easily identifiable neuronal and glial cells per segment. The development of midline glial cells is relatively well understood. Their differentiation appears to be controlled by the concomitant expression of two different sets of transcription factors. Activation of glial differentiation mediated by the ETS transcription factor encoded by pointed (whose activity depends on EGF-receptor signalling) occurs in concert with repression of neuronal differentiation mediated by the Zn-finger transcription factor encoded by tramtrack.

[Aspergillosis of the antrum]. / Aspergillose der Kieferhöhle.

Aspergillus falls into the class of hyphae-forming molds and is ubiquitous. It is known as a facultatively pathogenic opportunist. It is incorporated by breathing in spores from the air and develops its pathogenicity only in predisposed subjects with a weakened systemic or local defense mechanism. While systemic mycosis involves a weakening of the defense condition by an underlying disease, immune suppressant therapy, metabolic disorder or the like, isolated antral affections usually appear in otherwise healthy subjects. Our observations in one case are presented.

[Homologous collagen implants in oral surgery in hemorrhagic patients]. / Homologe Kollagenvlies-Implantation in der zahnärztlichen Chirurgie bei blutungsgefährdeten Patienten.

In 154 hospitalized hemorrhagic patients 883 oro-surgical procedures were done under continuous anticoagulation. Human collagen material combined with fibrin adhesive offered a safe hemostatic effect. A total of 12, mostly minor, postoperative bleedings occurred, which did not lead to delayed wound healing. Good tissue tolerance towards both homologous partners and healing by primary intention should be emphasized. These observations are to be corroborated by further clinical trials. Human collagen can make surgical treatment in hemorrhagic patients safer yet.

[Use of fibrin adhesive in maxillary sinus surgery]. / Die Anwendung von Fibrinkleber in der operativen Therapie der Kieferhöhle.

For haemostasis and to guarantee the drainage following operative procedures on the maxillary sinuses, the sinus is usually plugged with a gauze strip or balloon tamponade through the drainage window in the inferior nasal meatus. This generally causes massive edema of the face and subjective complaints of the patient, the risk of an anaerobe infection is increased. By using fibrin glue that is applied by a spray catheter into the maxillary sinus, there is no need of a tamponade as a haemostypt. The sinus is drained by a small vinyl tube through the window in the inferior nasal meatus.

[Application of fibrin adhesive systems in the maxillary sinus as an alternative to tamponage]. / Die Anwendung von Fibrinkleber in der Kieferhöhle als Alternative zur Tamponade.

During the past two years 22 patients with a chronic maxillary sinusitis have been operated in our clinic using a special catheter set for the application of fibrin glue instead of a gauze strip tamponade as a hemostypt. With 20 of these patients the results of this method were evaluated in a clinical investigation. All investigated sinuses were clinically, roentgenologically and sonographically asymptomatic, as were also sinuscopic controls with a part of these patients.