Serum and Plasma Levels of Vascular Endothelial Growth Factors in Relation to Quality of Glucose Control, Biomarkers of Inflammation, and Diabetic Nephropathy

Levels of vascular endothelial growth factors (VEGF) are regulated in a complex network of adipokines, glucose control, and low grade inflammation together with activated platelets, leucocytes, and endothelial dysfunction. Increased levels of VEGF are associated with enhanced angiogenesis and impaired repair mechanisms of vascular lesions in endorgans. Little is known about the interaction of systemic VEGF levels with quality of diabetes control, biomarkers of inflammation, and diabetic nephropathy. Moreover, it is unclear, whether serum and plasma VEGF levels are similarly suited to reflect risk associated with VEGF.In this case control study, we analyzed these parameters in serum and plasma of age and sex matched controls without diabetes (n=99) and type 2 diabetes (n=302). Serum VEGF-A was significantly increased in patients with T2DM while plasma levels were in the same range as for controls. Individual levels varied in a wide range. Serum levels were 4.9 times higher in controls and 7.3 times higher in T2DM as compared to plasma levels. T2DM was associated with significantly higher levels of hsCRP, ALAT, and albumin/creatinine ratio. When calculated for tertiles of HbA1c, we observed a highly significant increase from tertile one to the upper tertile for serum VEGF-A but not for plasma VEGF-A. Correlation analysis revealed a significant relationship between VEGF-A, HbA1c, inflammation, and diabetic nephropathy. Our results indicate that increased VEGF-A levels in T2DM significantly depend on quality of HbA1c control. Serum levels of VEGF-A, with a strong contribution of platelet derived VEGF, better reflect the glycemic burden than plasma levels of VEGF-A. Mechanistic studies are needed to explore links to inflammation and diabetic nephropathy.

Effects of pioglitazone versus simvastatin on biomarkers of inflammation in patients on high cardiovascular risk

High levels of fetuin-A has been linked to cardiovascular disease, possibly via modulating low-grade systemic inflammation. We performed a subanalysis from the PIOSTAT study to investigate a possible link between fetuin-A and the inflammatory biomarker hs-CRP. 66 nondiabetic individuals at cardiovascular risk were randomized to either pioglitazone, simvastatin, or the combination of both, and followed for 12 weeks. At study endpoint, correlations between serum fetuin-A, hs-CRP, blood lipids, PAI-1, MMP-9, HOMA-IR, and liver transaminases were investigated by Spearman rank correlation. Changes in fetuin-A concentration did not correlate to changes in hs-CRP (r=0.19, p=0.16). A positive correlation was found for change of HOMA-IR value (r=0.33, p=0.01) and for the AST/ALT ratio (p<0.05). Our data suggest that the previously observed correlation between elevated circulating fetuin-A and hs-CRP in epidemiological studies may not reflect a causal relationship in nondiabetic patients on high cardiovascular risk.

Differences in the histogenesis of EDL and diaphragm in rat

We have examined the histogenesis of the diaphragm and extensor digitorum muscle in rat embryos, with the aim of defining differences in developmental patterns that can be related to the functional requirements of these muscles during and after development. Patterns of interactions between myotubes and other cells, and frequency of gap junctions are quite different in the two muscles. In diaphragm, primary myotubes (at day 16 in utero) are closely associated with each other, forming parallel sheets or palisades and communicating by gap junctions. Secondary myotubes have formed by day 18, but are immature, and the frequency of gap junctions is lower. The arrangement in palisades is maintained even after fibers are separated from each other by their individual basal lamina. In EDL primary fibers at day 16 have fewer gap junctions, and the peak in communication occurs after the appearance of secondary myotubes (day 18 and 21). Secondary myotubes are more mature than in diaphragm at day 18.

Quantitation of Ca ATPase, feet and mitochondria in superfast muscle fibres from the toadfish, Opsanus tau

The muscle band surrounding the swimbladder of the toadfish (Opsanus tau) is one of the fastest known muscles in vertebrates. Rapid, non-fused twitches are responsible for the characteristic sound produced by the organ by both male and female toadfish. We have quantitated the membrane systems (transverse (T) tubules, sarcoplasmic reticulum (SR) and mitochondria), and some of their proteins (Ca2+ ATPase, or calcium pump, and foot protein or Ca2+ release channel) in these muscle fibres. As expected from the well-known morphology, the content of Ca2+ release and Ca2+ uptake proteins are considerably higher than in slower twitch fibres (e.g. fast-twitch and slow-twitch fibres in hind legs of mammals). Unexpectedly, the increment in ATPase is much larger than the increment in foot protein. The ATPase to foot ratio in muscle fibres from the swimbladder of males and females is higher by a factor of five to seven than in guinea pig fast-twitch fibres. We conclude that calcium uptake is a limiting factor in the ability to sustain the trains of high frequency, non-fused synchronous contractions of which these fibres are capable. Sexual dimorphism is demonstrated in the content of mitochondria (higher in males) and in the density of junctional feet (higher in females). The former is probably related to the more continuous activity during the males' mating call but the latter is to be demonstrated.

[In vivo effects of high density lipoprotein rich serum fractions (HDLF) in the human. 1. Modification of circulating thrombocyte aggregates, cardiovascular parameters and lipid metabolism by HDLF]

By means of the modified Cohn-method 6 Cohn-IV-1-fractions were prepared in the small pool technique as sterile, pyrogen-free and HDL-rich serum fractions (HDLF), the HDL-concentrations of which were 15-20 g/l. In in-vitro investigations they inhibited the spontaneous aggregation of erythrocytes as well as the ADP-induced aggregation of thrombocytes and activated the molar and fractional initial cholesterol estirification rates as well as the prostacyclin synthesis. From HDLF intravenously applied in people as immediate effects result significant decreases of the cardiac pre- and afterload, an increase of the cardiac ejection fraction as well as a complete dissolution of circulating aggregates of thrombocytes. In 35 patients with hyperlipidaemias after infusion of 100 ml HDLF up to the 5th day increasing and for 14 days remaining increases of concentration of biliary bile acids, total phospholipids and of cholesterol were observed in lithogenic indices remaining in the normal region. The plasmatic lipo- and apolipoproteins reacted with increases, decreases or constancy of concentration which might be based on the different ethryopathogeneses of the hyperlipoproteinaemias.

Quantitation of 'junctional feet' content in two types of muscle fiber from hind limb muscles of the rat

1. Transverse tubules in fibers from rat soleus and extensor digitorum longus (EDL) muscles of the rat were infiltrated with silver dichromate (black reaction of Golgi). This provides a faithful, high-contrast outline of the tubules, which allows distinction between segments involved in junction formation with the sarcoplasmic reticulum and segments that are free. 2. Electron micrographs of semithin transverse sections were used to quantitate T tubule parameters and to measure cross-sectional area and perimeter of individual fibers. Thin sections and data from the literature were used to obtain the contribution of caveolae to external surface area and the frequency of junctional feet along the junctional T tubule membrane. 3. From the above data we calculate the ratio of number of feet to total external surface area for a given fiber segment. The ratio is compared with data in the literature on the total amount of 'charge movement' (in nC/uF of total external surface area). 4. The average feet/surface area ratio is twice as large in EDL than in soleus fibers, while the charge movement is up to five-fold larger. Probably some of the total charge movement is not directly associated with events related to the turning on of the SR permeability to calcium.

Golgi stain identifies three types of fibres in fish muscle

Using Golgi infiltration we have studied the structure and disposition of transverse tubules in muscle fibres from the sand dab fin musculature. Three types of fibres differ significantly from each other in the extent and disposition of junctions between transverse tubules and the sarcoplasmic reticulum. These correlate with the three groups of fibres having different relaxation times shown in the accompanying paper (Gilly & Aladjem, 1987). Fibres with very slow relaxation (tonic fibres) correspond to those which have an unusual disposition of T tubules and very rare T-SR junctions. In the fast twitch fibres the peripheral T tubules segments converge into tangentially arranged tubules before joining the plasmalemma.