Pioneer study: PPARgamma activation results in overall improvement of clinical and metabolic markers associated with insulin resistance independent of long-term glucose control.

New scores and biochemical markers have recently been published for diagnosis of insulin resistance and beta-cell dysfunction (such as intact proinsulin, adiponectin, IRISII-score). One goal of this 6-month prospective controlled study was to evaluate the impact of pioglitazone (45 mg) vs. glimepiride (1-6 mg, in the intend to optimize therapy) on these markers. Observation parameters were: IRIS-II score, HOMA-score, ATP III score, HbA (1c), fasting glucose, lipids, intact proinsulin, adiponectin, and adverse events. The study was completed by 173 patients (66 female, 107 male, age +/- STD: 63 +/- 8 years, disease duration: 7.2 +/- 7.2 years, HbA (1c): 7.53 +/- 0.85 %, pioglitazone arm: 89 patients). The groups were not different for any of the observation parameters at baseline, and a similar reduction in HbA (1c) was seen in both groups (p < 0.001). In the pioglitazone group, reductions were observed for the IRIS-II and HOMA scores (p < 0.001 vs. glimepiride at endpoint) fasting glucose (p < 0.001), insulin (p < 0.001), LDL/HDL ratio (p < 0.001), hsCRP (p < 0.05), intact proinsulin (p < 0.001), and an increase was seen in HDL (p < 0.001), adiponectin (p < 0.001) and BMI (p < 0.001). In conclusion, treatment with pioglitazone resulted in an improvement of markers for insulin resistance and beta-cell dysfunction, independent from blood glucose control. Adiponectin, intact proinsulin, and the IRIS-II score may be suitable parameters for monitoring of these additional beneficial therapeutic effects.

IRIS II study: the IRIS II score--assessment of a new clinical algorithm for the classification of insulin resistance in patients with Type 2 diabetes.

AIMS: With the increasing availability of new drugs for the treatment of insulin resistance in patients with Type 2 diabetes, simple methods for their identification is an important challenge. The aim of our study was to compute a new algorithm for estimating insulin resistance in a routine clinical setting. METHODS: Clinical data and blood samples were collected from 4265 Type 2 diabetic patients from 149 clinical sites. A clinical algorithm to estimate insulin resistance was developed by stepwise multiple regression analysis. The new generated score was compared with the HOMAIR-score, calculated from fasting insulin and glucose levels measured in a central laboratory. In a subgroup of 48 patients, the score was verified against a frequently sampled intravenous glucose tolerance test with subsequent modified minimal model analysis according to Bergman. RESULTS: Multiple regression analysis revealed fasting blood glucose, BMI, triglycerides and HDL as the most powerful predictors of insulin resistance which were used for further computation of the IRIS II score. A significant overall correlation was found between the HOMAIR-score and the new clinical IRIS II score (r = 0.42; P < 0.0001). Compared with HOMAIR, the new score revealed a specificity of 0.95, a sensitivity of 0.34 and a positive predictive value of 0.95. This was in good agreement with the subset analysis of the intravenous glucose tolerance test, where a sensitivity of 0.37 and a specificity of 0.85 of the IRIS II score was calculated. Patients with insulin resistance according to the IRIS II score revealed an increased odds ratio for overall vascular complications (1.28; 1.11-1.46; P < 0.001). CONCLUSIONS: The new IRIS II score can identify insulin resistance in Type 2 diabetic patients with high predictive value and high specificity.

Stimulation of protein (collagen) synthesis in sponge cells by a cardiac myotrophin-related molecule from Suberites domuncula.

The body wall of sponges (Porifera), the lowest metazoan phylum, is formed by two epithelial cell layers of exopinacocytes and endopinacocytes, both of which are associated with collagen fibrils. Here we show that a myotrophin-like polypeptide from the sponge Suberites domuncula causes the expression of collagen in cells from the same sponge in vitro. The cDNA of the sponge myotrophin was isolated; the potential open reading frame of 360 nt encodes a 120 aa long protein (Mr of 12,837). The sequence SUBDOMYOL shares high similarity with the known metazoan myotrophin sequences. The expression of SUBDOMYOL is low in single cells but high after formation of primmorph aggregates as well as in intact animals. Recombinant myotrophin was found to stimulate protein synthesis by fivefold, as analyzed by incorporation studies using [3H] lysine. In addition, it is shown that after incubation of single cells with myotrophin, the primmorphs show an unusual elongated, oval-shaped appearance. It is demonstrated that in the presence of recombinant myotrophin, the cells up-regulate the expression of the collagen gene. The cDNA for S. domuncula collagen was isolated; the deduced aa sequence shows that the collagenous internal domain is rather short, with only 24 G-x-y collagen triplets. We conclude that the sponge myotrophin causes in homologous cells the same/similar effect as the cardiac myotrophin in mammalian cells, where it is involved in initiation of cardial ventricular hypertrophy. We assume that an understanding of sponge molecular cell biology will also contribute to a further elucidation of human diseases, here of the cardiovascular system.

Putative multiadhesive protein from the marine sponge Geodia cydonium: cloning of the cDNA encoding a fibronectin-, an SRCR-, and a complement control protein module.

Sponges (Porifera) representing the simplest metazoan phylum so far have been thought to possess no basal lamina tissue structures. One major extracellular matrix protein that is also a constitutive glycoprotein of the basal lamina is fibronectin. It was the aim of the present study to identify the native protein from the marine sponge Geodia cydonium and to isolate the corresponding cDNA. In crude extracts from this sponge protein(s) of M(r) of approximately 230 and approximately 210 kDa could be visualized by Western-blotting using an anti-fibronectin [human] antibody. By PCR cloning from a cDNA library of G. cydonium we isolated a cDNA comprising one element of fibronectin, the type-III (FN3) module. The cDNA (2.3 kb long), encoding a 701 amino acid [aa] long putative "multiadhesive protein" termed MAP_GEOCY, was found to contain (i) a fibronectin-, (ii) a scavenger receptor cysteine-rich [SRCR]-, and (iii) a short consensus repeat [SCR] module. The 89 aa long fibronectin module comprises the characteristic topology and conserved aa found in fibronectin type-III (FN3) elements. The SRCR module (101 aa) features the characteristics of group B SRCR molecules. The predominant proteins belonging to this group are the mammalian WC1-, M130-, CD6- and CD5 antigens that probably are involved in immunological reactions. The SCR module (54 aa) shows the characteristics of type III SCR modules found in complement receptors. Phylogenetic analyses performed with all three building blocks of the "multiadhesive protein" showed that the respective sponge modules form independent, possibly basal, lineages in trees that include the corresponding modules from higher metazoan animals. In summary, these data demonstrate for the first time that the phylogenetically oldest Metazoa, the sponges, contain protein modules seen in higher animals in proteins of the extracellular matrix and in molecules involved in cell-mediated immune reactions in vertebrates.

Isolation and characterization of a cDNA encoding a potential morphogen from the marine sponge Geodia cydonium that is conserved in higher metazoans.

Species belonging to the lowest metazoan phylum, the sponges (Porifera), exhibit a surprisingly complex and multifaceted Bauplan (body plan). Recently, key molecules have been isolated from sponges which demonstrate that the cells of these animals are provided with characteristic metazoan adhesion and signal transduction molecules, allowing tissue formation. In order to understand which factors control the spatial organization of these cells in the sponge body plan, we screened for a cDNA encoding a soluble modulator of the behaviour of endothelial cells. A cDNA encoding a putative protein, which is highly similar to the human and mouse endothelial monocyte-activating polypeptide (EMAP) II has been isolated from a library of the marine sponge Geodia cydonium. The sponge EMAP-related polypeptide (EMAPR) has been termed EMAPR1_GC. The full-length cDNA clone, GCEMAPR1, has a size of 592 nucleotides (nt) and contains a 447 nt-long potential open reading frame; the molecular weight (MW) of the deduced amino acid sequence, 16,499 Da, is close to that of mature mammalian EMAP II (ca. 18 kDa). The sponge polypeptide is also closely related to a deduced polypeptide from the cosmid clone F58B3 isolated from Caenorhabditis elegans. A phylogenetic analysis revealed that the sponge and the nematode EMAPR molecules form a cluster which is significantly separated from the corresponding mammalian EMAP molecules. The function of the first cloned putative soluble modulator of endothelial cells in sponges remains to be determined.

Neuroactive compounds produced by bacteria from the marine sponge Halichondria panicea: activation of the neuronal NMDA receptor.

Previous studies revealed that the marine sponge Halichondria panicea habors symbiotic- and commensalic bacteria (Althoff et al., 1998. Marine Biol. 130, 529-536). In the present study the hypothesis was tested whether some of those bacteria synthesize neuroactive compounds. For the first time the effect of bacterial bioactive compounds on the neuronal ionotropic glutamate receptors [iGluR], subtype N-methyl-d-aspartate (NMDA) receptor, was checked. In cortical neurons from rats as cell system the supernatant of two bacterial cultures isolated from H. panicea proved to agonize the NMDA receptor. The response of the NMDA receptor to the bioactive compounds was determined by measuring the intracellular Ca(2+) level. The supernatants of cultures 697 and 698 were found to upregulate the intracellular Ca(2+) level. To validate the specificity of the effects, inhibition studies with Memantine and d-AP5 were performed. The two bacteria were identified by polymerase chain reaction-amplification of the 16S rDNA genes and subsequent sequencing; they displayed highest identity to Antarcticum vesiculatum and to Psychroserpens burtonensis, respectively. Based on these data first experimental evidence is presented indicating that bacteria associated with sponges display neuroactivity by agonizing the NMDA receptor.