Glycation changes the charge distribution of type I collagen fibrils

In aging and diabetes, glycation of collagen molecules leads to the formation of cross-links that could alter the surface charge on collagen fibrils, and hence affect the properties and correct functioning of a number of tissues. The electron-optical stain phosphotungstic acid (PTA) binds to positively charged amino acid side-chains and leads to the characteristic banding pattern of collagen seen in the electron microscope; any change in the charge on these side-chains brought about by glycation will affect the uptake of PTA. We found that, upon glycation, a decrease in stain uptake was observed at up to five regions along the collagen D-period; the greatest decrease in stain uptake was apparent at the c1 band. This reduction in PTA uptake indicates that the binding of fructose leads to an alteration in the surface charge at several sites along the D-period. Not all lysine and arginine residues are involved; there appear to be specific residues that suffer a loss of positive charge.     

Transgenic A1 adenosine receptor overexpression markedly improves myocardial energy state during ischemia-reperfusion

A1 adenosine (A1AR) activation may reduce ischemia-reperfusion injury. Metabolic and functional responses to 30 min global normothermic ischemia and 20 min reperfusion were compared in wild-type and transgenic mouse hearts with approximately 100-fold overexpression of coupled cardiac A1ARs. 31P-NMR spectroscopy revealed that ATP was better preserved in transgenic v wild-type hearts: 53 +/- 11% of preischemic ATP remained after ischemia in transgenic hearts v only 4 +/- 4% in wild-type hearts. However, recovery of ATP after reperfusion was similar in transgenic (46 +/- 5%) and wild-type hearts (37 +/- 12%). Reductions in phosphocreatine (PCr) and cytosolic pH during ischemia were similar in both groups. However, recovery of PCR on reperfusion was higher in transgenic (67 +/- 8%) v wild-type hearts (36 +/- 8%), and recovery of pH was greater in transgenic (pH = 7.11 +/- 0.05) v wild-type hearts (pH = 6.90 +/- 0.02). Bioenergetic state ([ATP]/[ADP].[Pi]) was higher in transgenic v wild-type hearts during ischemia-reperfusion. Time to ischemic contracture was prolonged in transgenic (13.6 +/- 0.8 min) v wild-type hearts (10.4 +/- 0.3 min). Degree of contracture was lower and recovery of function in reperfusion higher in transgenic v wild-type hearts. In conclusion, A1AR overexpression reduces ATP loss and improves bioenergetic state during severe ischemic insult and reperfusion. These changes may contribute to improved functional tolerance.     

Thrombopoietin requires additional megakaryocyte-active cytokines for optimal ex vivo expansion of megakaryocyte precursor cells

Little is known concerning the interaction of thrombopoietin (TPO) with other megakaryocyte-active cytokines in directing the early events of megakaryocyte development. Culture of CD34(+) cells in interleukins (IL) -1, -6, -11, plus stem cell factor (SCF; S) results in a 10- to 12-fold expansion in total cell numbers, whereas total CD41(+) megakaryocytes are expanded approximately 120-fold over input levels. Addition of TPO to IL-1, -6, -11, S generates a biphasic proliferation of CD41(+) cells, accelerates their rate of production, and results in an ex vivo expansion of more than 200-fold. The addition of Flt-3 ligand (FL) increases CD41+ cell expansion to approximately 380-fold over input levels. In the absence of TPO, approximately 95% of the expanded cells show the phenotype of promegakaryoblasts; TPO and/or FL addition increases CD41 antigen density and ploidy in a subpopulation of promegakaryoblasts. A moderate (approximately sevenfold) expansion of megakaryocyte progenitor cells (colony-forming unit-megakaryocyte) occurs in the presence of IL-1, -6, -11, S, and the addition of TPO to this cocktail yields an approximately 17-fold expansion. We conclude that early proliferative events in megakaryocyte development in vitro are regulated by multiple cytokines, and that TPO markedly affects these early developmental steps. However, by itself, TPO is neither necessary nor sufficient to generate a full proliferative/maturational in vitro response within the megakaryocyte compartment. TPO clearly affects terminal differentiation and the development of (some) high-ploidy human megakaryocytes. However, its limited in vitro actions on human cell polyploidization suggest that additional megakaryocyte-active cytokines or other signals are essential for the maximal development of human megakaryocytes.     

Frequency of lyme borreliosis and diagnostic titers of antibodies to borrelia burgdorferi in patients with neurological diseases in endemic region of Russia

The frequency of diagnostic titers of antibodies to Borrelia burgdorferi in 289 examinees suffering from neurological diseases made up 10.4%, while in the population this figure was under 1.9%. Lyme-borreliosis was detected in 11 (3.8%) patients, 2 of them had mixed infection with tick-borne viral encephalitis. In 10 patients (3.5%) the diagnosis of neuroborreliosis required verification with other techniques. It is thought valid to perform serological screening for neuroborreliosis only in patients with tick-born encephalitis to identify mixed infection.     

Middle ear infection and sixth nerve palsy

Three cases of patients with acute middle ear infections complicated by a sixth nerve palsy are described. The possible causes of sixth nerve palsy in such cases are discussed. We propose that where there is a sixth nerve palsy without petrositis and without raised intracranial pressure, it can arise as a result of spreading phlebitis along the inferior petrosal sinus from the lateral sinus.     

Synovectomy of the elbow and radial head excision in rheumatoid arthritis. Predictive factors and long-term outcome

We carried out a survival analysis of elbow synovectomy (ES) and excision of the radial head (RHE) performed on 171 rheumatoid elbows. The failure criteria were revision surgery (performed or desired) and/or the presence of significant or severe pain. The cumulative survival was 81% at one year which thereafter decreased by an average of 2.6% per year. The strongest predictor for success was a low preoperative range of supination-pronation when corresponding survival curves were compared. A low range of flexion-extension also predicted failure. Combining both factors gave better prediction (failure: 6.3% v 67%), but a long duration of elbow symptoms before surgery predicted failure (72%, p = 0.04). At review, there was a mean gain of 50 degrees in supination-pronation and 11 degrees in flexion-extension; both correlated with success. Failure correlated with recurrence of synovitis, elbow instability, ulnar neuropathy, poor general mobility and poor upper-limb function. The last was independently affected by the severity of RA in the ipsilateral shoulder. Our findings show that although the short-term result of ES and RHE in rheumatoid arthritis is good, the long-term outcome is poor except in a subgroup with more than 50% limitation of forearm rotation.     

Production, uptake, and metabolic effects of cyclic AMP in the bivascularly perfused rat liver

Production, uptake, and metabolic effects of cyclic AMP (cAMP) were measured in the bivascularly perfused rat liver in anterograde and retrograde perfusion. Glucagon, cAMP, N6,2'-O-dibutyryl cAMP and N6-monobutyryl cAMP were infused into the portal vein (anterograde perfusion), the hepatic vein (retrograde perfusion), or the hepatic artery (anterograde and retrograde perfusion) in order to reach different cell populations. The following results were obtained: (1) cAMP release caused by glucagon was directly proportional to the cell spaces that were accessible via the hepatic artery in anterograde and retrograde perfusion; since the metabolic effects of glucagon were not proportional to the accessible cell spaces, this observation also implies a disproportion between cAMP release and metabolic effects of the hormone; (2) when cAMP and N6,2'-O-dibutyryl cAMP were given to all liver cells (e.g. when infused into the portal vein), their metabolic effects were qualitatively and quantitatively the same and qualitatively equal to the effects of glucagon; (3) the changes caused by cAMP were a function of the cell spaces that can be reached via the hepatic artery in anterograde and retrograde perfusion; this behaviour contrasts markedly with that of glucagon, whose metabolic effects were practically independent of the accessible cell spaces; and (4) the effects of N6,2'-O-dibutyryl cAMP and N6-monobutyryl cAMP were independent of the cell spaces that were accessible via the hepatic artery in anterograde and retrograde perfusion; in this respect their behaviour was equal to that of glucagon. It is apparent that exogenously added cAMP mimicked the metabolic effects of glucagon in the liver only when it was supplied to all liver cells. Since glucagon, N6,2'-O-dibutyryl cAMP, and N6-monobutyryl cAMP were able to produce a full response even when given to only 30% of the liver parenchyma, it was concluded that cAMP production under the stimulus of glucagon or in consequence of the metabolic transformation of N6,2'-O-dibutyryl cAMP and N6-monobutyryl cAMP occurs in a compartment to which exogenous cAMP has no access. cAMP generated within this compartment is possibly able to diffuse from cell to cell.