Abnormalities of calcium cycling in the hypertrophied and failing heart

Progressive deterioration of cardiac contractility is a central feature of congestive heart failure (CHF) in humans. In this report we review those studies that have addressed the idea that alterations of intracellular calcium (Ca(2+)) regulation is primarily responsible for the depressed contractility of the failing heart. The review points out that Ca(2+)transients and contraction are similar in non-failing and failing myocytes at very slow frequencies of stimulation (and other low stress environments). Faster pacing rates, high Ca(2+)and beta-adrenergic stimulation reveal large reductions in contractile reserve in failing myocytes. The underlying cellular basis of these defects is then considered. Studies showing changes in the abundance of L-type Ca(2+)channels, Ca(2+)transport proteins [sarcoplasmic reticulum Ca(2+)ATPase (SERCA2), phospholamban (PLB), Na(+)/Ca(2+) exchanger (NCX)] and Ca(2+) release channels (RYR) in excitation-contraction coupling and Ca(2+)release and uptake by the sarcoplasmic reticulum (SR) are reviewed. These observations support our hypotheses that (i) defective Ca(2+)regulation involves multiple molecules and processes, not one molecule, (ii) the initiation and progression of CHF inolves defective Ca(2+)regulation, and (iii) prevention or correction of Ca(2+)regulatory defects in the early stages of cardiac diseases can delay or prevent the onset of CHF.

Transplantation of allograft chondrocytes embedded in agarose gel into cartilage defects of rabbits

OBJECTIVE

Durable healing of full-thickness articular cartilage defects has been considered for a long time as a highly desirable, but unlikely event to occur. In recent years, conflicting reports on the outcome of in vitro and in vivo studies on chondrocyte and cartilage grafting into animal and human joints have raised new arguments for and against controlled repair of articular cartilage following injury. Some of the problems result from insufficient characterization of implant and repair tissue, and from too short follow up phases. Here we describe a new approach to repair articular cartilage defects in rabbit knees by allografting chondrocytes cultured in agarose gels.

DESIGN

The implants were monitored over 6-18 months and graded histologically, immunohistochemically, and electron microscopically, using a grading scale based on seven evaluation criteria. Control implants of pure agarose produced poor fibrous substitute tissue, insufficient healing and incomplete filling of the cartilage defects. After transplantation of allogenic chondrocytes embedded in agarose, the quality of the newly formed repair cartilage was superior with respect to type II collagen and proteoglycan content and cellular architecture when compared with untreated defects. Superficial fibrillation and degradation were significantly diminished or prevented.

RESULTS

New subchondral bone formed at the level of the previous subchondral bone. In most cases the repair tissue merged with the host articular cartilage; normal calcified cartilage was the only tissue zone that did not participate in the integration of the transplant. By gross evaluation 24% of grafts showed an extent of recovery never observed in controls. The best results were obtained after 18 months when 47% of the grafts (N = 15) developed a morphologically stable hyaline cartilage.

CONCLUSION

These studies demonstrate that agarose-embedded chondrocyte may prove a valuable tool for controlled repair of articular cartilage defects.

Origin, development and regulation of human Leydig cells

Sex steroids are crucial regulators of sexual differentiation and the proper development of secondary sex characteristics and patterns of sexual behavior. Since Leydig cells are the primary major producers of these steroid hormones, maintenance of the normal functions of these cells determines the reproductive capacity and fertility of males. The present minireview discusses recent findings concerning endocrine and paracrine regulation of the proliferation, differentiation and involution of human Leydig cells. The physiology and function of the two distinct fetal and adult populations of human Leydig cells are described, with particular focus on the paracrine environment that triggers their differentiation and functional maturation. The roles of established and more recently discovered paracrine regulators of this maturation, including insulin-like factor 3, platelet-derived growth factor-alpha, desert hedgehog, ghrelin and leptin are considered. A brief description of the origin, ontogenesis and functional markers of human fetal and adult Leydig cells is presented.

Influence of mild hypothermia on myocardial contractility and circulatory function

Myocardial contractility depends on temperature. We investigated the influence of mild hypothermia (37-31 degrees C) on isometric twitch force, sarcoplasmic reticulum (SR) Ca2+-content and intracellular Ca2+-transients in ventricular muscle strips from human and porcine myocardium, and on in vivo hemodynamic parameters in pigs. In vitro experiments: muscle strips from 5 nonfailing human and 8 pig hearts. Electrical stimulation (1 Hz), simultaneous recording of isometric force and rapid cooling contractures (RCCs) as an indicator of SR Ca2+-content, or intracellular Ca2+-transients (aequorin method). In vivo experiments: 8 pigs were monitored with Millar-Tip (left ventricle) and Swan-Ganz catheter (pulmonary artery). Hemodynamic parameters were assessed at baseline conditions (37 degrees C), and after stepwise cooling on cardiopulmonary bypass to 35, 33 and 31 degrees C. Hypothermia increased isometric twitch force significantly by 91 +/- 16 % in human and by 50 +/- 9 % in pig myocardium (31 vs. 37 degrees C; p < 0.05, respectively). RCCs or aequorin light emission did not change significantly. In anesthetized pigs, mild hypothermia resulted in an increase in hemodynamic parameters of myocardial contractility. While heart rate decreased from 111 +/- 3 to 73 +/- 1 min(-1), cardiac output increased from 2.4 +/- 0.1 to 3.1 +/- 0.31/min, and stroke volume increased from 21 +/- 1 to 41 +/- 3 ml. +dP/dtmax increased by 25 +/- 8% (37 vs. 31 degrees C; p < 0.05 for all values). Systemic and pulmonary vascular resistance did not change significantly during cooling. Mild hypothermia exerts significant positive inotropic effects in human and porcine myocardium without increasing intracellular Ca2+-transients or SR Ca2+-content. These effects translate into improved hemodynamic parameters of left ventricular function.

Role of growth factors in rabbit articular cartilage repair by chondrocytes in agarose

OBJECTIVE

Novel approaches to intervention in joint diseases consist of the replacement of diseased cartilage by in vitro engineered, viable cells or graft tissues. Two major obstacles remain to be overcome: (1) Hyaline cartilage in vitro often loses differentiated traits. (2) Grafts frequently are not integrated satisfactorily into host cartilage and/or the tissue is remodelled in situ into functionally inferior fibrocartilage. Therefore, we have explored the possibility whether chondrocytes embedded into agarose gels provided better graft tissues in a repair model of full thickness defects in rabbit joint cartilage.

DESIGN

Experimental defects of knee joint cartilage was filled with articular chondrocytes cultured in agarose gels. Chondrocytes in vitro either remained unstimulated or were treated with several growth factors. Repair of the defects was assessed by histology and was scored between 0 (no healing) and 1 (perfect healing) as judged by the follwing parameters: intensity of proteoglycan staining, organization of the superficial zone, ossification at the border between repair cartilage and subchondral bone, tidemark formation in the repaired area, arrangement of chondrocytes, and integration of repair cartilage into host.

RESULTS

Treatment of chondrocyte cultures with bFGF had a stabilizing effect on the differentiated state of the cells in implanted grafts whereas bone morphogenetic proteins stimulated ingrowth of subchondral bone reducing repair cartilage thickness and preventing normal tide mark formation; TGF-beta did not significantly affect evaluation parameters in comparison with untreated controls.

CONCLUSION

Growth factor treatment resulted in an ambiguous quality of graft development. Only FGF had a clear beneficial effect to the graft tissues after 1 month. Further studies are required to define the precise conditions and sequence of growth factor treatment of in vitro engineered cartilage which benefits graft quality.

Elimination of plasmids by new 4-quinolones

Nalidixic acid and six of the new 4-quinolones eliminated F'lac and various native R plasmids from Escherichia coli at one half or one quarter the MIC. Four of eight plasmids tested were cured by all derivatives, with frequencies from 10 to 98%. Quinolones did not eliminate all plasmids that were cured by novobiocin, and vice versa.

Ca(2+) handling in isolated human atrial myocardium

Physiologically, human atrial and ventricular myocardium are coupled by an identical beating rate and rhythm. However, contractile behavior in atrial myocardium may be different from that in ventricular myocardium, and little is known about intracellular Ca(2+) handling in human atrium under physiological conditions. We used rapid cooling contractures (RCCs) to assess sarcoplasmic reticulum (SR) Ca(2+) content and the photoprotein aequorin to assess intracellular Ca(2+) transients in atrial and ventricular muscle strips isolated from nonfailing human hearts. In atrial myocardium (n = 19), isometric twitch force frequency dependently (0. 25-3 Hz) increased by 78 +/- 25% (at 3 Hz; P < 0.05). In parallel, aequorin light signals increased by 111 +/- 57% (P < 0.05) and RCC amplitudes by 49 +/- 13% (P < 0.05). Similar results were obtained in ventricular myocardium (n = 13). SR Ca(2+) uptake (relative to Na(+)/Ca(2+) exchange) frequency dependently increased in atrial and ventricular myocardium (P < 0.05). With increasing rest intervals (1-240 s), atrial myocardium (n = 7) exhibited a parallel decrease in postrest twitch force (at 240 s by 68 +/- 5%, P < 0.05) and RCCs (by 49 +/- 10%, P < 0.05). In contrast, postrest twitch force and RCCs significantly increased in ventricular myocardium (n = 6). We conclude that in human atrial and ventricular myocardium the positive force-frequency relation results from increased SR Ca(2+) turnover. In contrast, rest intervals in atrial myocardium are associated with depressed contractility and intracellular Ca(2+) handling, which may be due to rest-dependent SR Ca(2+) loss (Ca(2+) leak) and subsequent Ca(2+) extrusion via Na(+)/Ca(2+) exchange. Therefore, the influence of rate and rhythm on mechanical performance is not uniform in atrial and ventricular myocardium.

Functional properties of failing human ventricular myocytes

Reduced peak systolic Ca2+ and slow decay of the Ca2+ transient are common features of the end-stage failing human ventricular myocyte and are thought to underlie abnormal ventricular contractility in congestive heart failure (CHF). Individual changes in the expression or activity of Ca2+ transport proteins of the sarcoplasmic reticulum (SR Ca2+ ATPase, SERCa) or the sarcolemmal (sodium-calcium exchanger, NCX) have not always been observed in CHF and cannot per se consistently explain these Ca2+ transient defects. We review recent data that suggests that the normal balance of transport activities of SERCa and NCX is deranged in failing human myocytes. We hypothesize that an increase in the NCX/SERCa transport capacity in failing myocytes can explain the abnormal Ca2+ homeostasis of the failing human ventricular myocyte.

The erythrocyte-perfused "working heart" model: hemodynamic and metabolic performance in comparison to crystalloid perfused hearts

A brief period of ischemia was used to evaluate an erythrocyte-enriched Krebs-Henseleit (KH) buffer (n=8) compared to KH only (n=8) in an isolated working rabbit heart. Experimental protocol was as follows: preischemic baseline, 5 min of global ischemia followed by 45 min of reperfusion. Preischemic heart rate was identical, coronary flow was significantly lower (2.7 versus 5.6 mL/min/g wet wt, p<0.01), the other hemodynamic and biochemical values were significantly higher in erythrocyte-perfused hearts: aortic flow 23.5 versus 12.0, p<0.01; cardiac output 26.2 versus 17.6, p<0.01; all in mL/min/g wet wt; dp/dt max 1286 versus 997 mmHg/s, p<0.01; myocardial oxygen consumption 3.5 versus 2.3 micromol/min/g wet wt, p<0.05. During early reperfusion, in the erythrocyte-perfused hearts, coronary flow further increased (p<0.003), the other hemodynamic parameters returned to baseline values in both groups. High-energy phosphates showed significantly higher values (ATP 2.0+/-0.1 versus 1.3+/-0.1, p<0.05; CrP 2.0+/-0.2 versus 1.6+/-0.1, p<0.05 all in micromol/g wct wt), water content was significantly lower (81% versus 74%, p<0.05) in erythrocyte-perfused hearts. It can be concluded that the erythrocyte-perfused working heart model provides excellent oxygenation, leading to superior hemodynamic and metabolic performance. Additionally, in the erythrocyte-perfused hearts preservation of coronary flow reserve underlines the physiological competency of this preparation.

Inhibition of R-plasmid transfer in Escherichia coli by 4-quinolones

Inhibition of transfer of four conjugative R plasmids by ciprofloxacin, enoxacin, norfloxacin, ofloxacin, and pipemidic acid was investigated in an Escherichia coli mating system. The absolute concentrations needed for inhibition of conjugation varied from 0.12 microgram/ml for ciprofloxacin to 16 micrograms/ml for pipemidic acid, but the relationship to the MICs for the parent strains was identical for all substrates. Concentrations for a 90% reduction of transconjugants were in the range of one to six times the MIC for the parent strains, which also had lethal effects on donors and recipients. A similar effect on conjugation was found with chloramphenicol. These observations question the specificity of transfer inhibition by quinolones and cast doubt on the clinical importance of such an effect.

Increased basal contractility of cardiomyocytes overexpressing protein kinase C epsilon and blunted positive inotropic response to endothelin-1

OBJECTIVE

Protein kinase C (PKC) is thought to be involved in the regulation of the mammalian cardiac excitation-contraction coupling process by vasoactive peptides like endothelin-1 (ET-1). However, the demonstration of a causal link between activation of specific PKC isoforms and the increase in contractility mediated by ET-1 is still inferential.

METHODS

By means of adenovirus-mediated gene transfer, we specifically overexpressed PKC epsilon in cultured adult rabbit ventricular myocytes (Ad-PKC epsilon). Myocyte shortening and [Ca2+]i transients under basal and ET-1-stimulated conditions were measured in Ad-PKC epsilon and Ad-LacZ control transfected cells.

RESULTS

Infection with Ad-PKC epsilon resulted in a strong, virus dose-dependent increase in PKC epsilon protein levels, whereas protein expression of other PKC isoforms remained unchanged. Using a multiplicity of infection of 100 plaque-forming units/myocyte, basal and cofactor-dependent PKC epsilon kinase activity was increased 28- and 90-fold, respectively, when compared to control. Myocyte basal fractional shortening and [Ca2+]i transient amplitude were both increased by 21% (P < 0.05 each) in Ad-PKC epsilon transfected myocytes when compared to Ad-LacZ transfected control myocytes. The positive inotropic effect of ET-1 in control myocytes was markedly blunted in PKC epsilon-overexpressing myocytes.

CONCLUSION

Specific overexpression of PKC epsilon in rabbit ventricular myocytes increases basal myocyte contractility and [Ca2+]i transients, and modifies their responsiveness to ET-1.

Steroidogenesis and steroidogenic gene expression in postnatal fetal rat Leydig cells

We studied steroidogenesis and the regulation of Leydig cell-specific gene expression in primary cultures of highly purified postnatal fetal Leydig cells (PFLCs). PFLCs activated by hCG and (Bu)(2)cAMP demonstrated transient capacity to produce testosterone (T) in vitro. A time dependent decline in T production by (Bu)(2)cAMP-stimulated PFLCs was observed and associated with the accumulation of progesterone in the culture media and complete suppression of P450c17 expression at the translational but not transcriptional level. PFLCs was found to lose their capacity to express Leydig cell-related genes (e.g., 3βHSD, P450c17, Insl3), which was restored by treatment with (Bu)(2)cAMP. It was also found that PDGFα alone and in combination with (Bu)(2)cAMP significantly stimulated proliferation of the isolated PFLCs in vitro. Our data indicate that cAMP-activated signaling pathway(s) play an important role in the regulation of PFLC differentiation and function.

Capping of lymphocytes for carrier detection in Duchenne muscular dystrophy: technical problems and a review of the literature

There has been considerable interest in capping of lymphocytes in patients with Duchenne muscular dystrophy (DMD). However, the results from different authors are controversial. We have investigated cap formation in thirteen families with DMD, using a method standardized in our laboratory, and could establish diminished capping in all 12 patients and in 12 of the 13 mothers. By examining cap formation simultaneously with whole polyvalent antiserum, with F(ab)2 fragment of polyvalent antiserum, and with monospecific antisera we could also confirm this observation of defective capping in 7 patients and 4 carriers, as compared to 9 control subjects likewise examined. We have indications that treatment of the lymphocytes under unfavourable conditions e.g. preincubation in buffer solution might accentuate the decrease of lymphocyte capping in patients and carriers.

Elimination of plasmids by enoxacin and ofloxacin at near inhibitory concentrations

The abilities of the 4-quinolones enoxacin and ofloxacin, inhibitors of DNA gyrase subunit A, to eliminate plasmids from Escherichia coli have been studied in a narrow concentration range just below the MIC. These compounds cured most efficiently at the highest concentration which still allows cell growth and produced 20% to 100% plasmid-free cells, depending upon the plasmid tested. Higher concentrations were required to eliminate plasmids from a gyrANalr strain, consistent with their higher MICs, but maximal curing frequencies were similar to those obtained with the Nals strain. Kinetics of plasmid elimination indicated that plasmid loss occurred by inhibition of plasmid replication, which seems to be somewhat more sensitive to the action of 4-quinolones than chromosome replication. Low or high curing frequencies with a given curing agent seem to be a property of the plasmid tested.

Inhibition of RNA- and DNA-synthesis by citrinin and its effects on DNA precursor-metabolism in V79-E cells

1. The RNA synthesis of V79-E cells was inhibited by the mycotoxin citrinin time- and concentration-dependently. 2. Among the different RNA species mainly the rRNA synthesis was found to be inhibited by 200 microM citrinin. 3. At different precursor concentrations DNA synthesis was inhibited by citrinin after 30 min at least whereas labelling of the acid soluble fractions was found to be 3-fold higher than in untreated cells. 4. Remarkable perturbation of the DNA precursor metabolism, including release of precursor into the medium, was found to occur during citrinin treatment.

[Transmission of the human immunodeficiency virus by a dry heat-treated Factor VIII concentrate?]

Short presentation of the common procedures to avoid transmission of human-immunodeficiency-virus (HIV) by hemoderivates especially clotting-factor-preparations. The stepwise seroconversion (ELISA, IFT, Western-blot) of HIV is shown in a 7 5/12 ys old boy with hemophilia A after administration of a dry-heated factor VIII-preparation. Seven similar observations were reported in the literature. On the other hand HIV-seroconversion could not be observed during treatment with wet-heated factor VIII-preparations. In consequence only wet-heated factor VIII-preparations and factor IX-preparations respectively should be administered to hemophiliacs without HIV-antibodies. By this precaution transmission of non-A, non-B-hepatitis may be avoided simultaneously.

Improving CD4+ lymphocyte counts in HIV-infected hemophilia patients. A favorable prognostic indicator?

CD4+ lymphocyte counts of 91 HIV+ hemophilia patients were monitored for a mean of 4 years (range: 15-69 months). CD4+ lymphocytes decreased in 55 but increased in 36 patients over time. The CD4+ cell increases were persistent in 5 patients, whereas they fluctuated in 31. Of the 36 patients with increasing CD4+ counts 3 developed AIDS and 1 LAS. The other 32 patients were clinically asymptomatic (CDC II), but had immunological abnormalities, such as increased serum neopterin (N = 18) and impaired in vitro T cell responses to pooled allogenic stimulator cells (N = 15) or mitogens (N = 18). In contrast, of the 55 patients whose CD4+ cells decreased, 24 developed AIDS and 5 ARC (P less than 0.0005). Only 2 of these 55 patients had normal mitogen stimulation in vitro and normal serum neopterin levels.

[Inhibition of gyrase by 4-quinolones: effect on the structure of DNA]

DNA gyrase is an essential enzyme in bacterial metabolism. Its function is the introduction of negative supercoils into DNA. These favour the unwinding of certain parts of DNA und thus are likely to facilitate processes like replication and transcription. Inhibition of DNA gyrase by quinolones and possible effects on the structure of DNA are reviewed.

[Glutaric acidemia/glutaric aciduria I as differential chorea minor diagnosis]

Glutaracidemia/glutaraciduria type I is an acute or subacute neuropathic disorder of infancy or early childhood. The following symptoms characterize the clinical course: macrocephalus present at birth, cerebral atrophy revealed by CT or MRI scans, most striking in the frontal and temporal lobes, choreoathetosis and dystonia as neurological handicaps. The deficiency of glutaryl-CoA-dehydrogenase leads to glutaracidemia and glutaraciduria. It is reported on a three year old girl. The glutaraciduria is an important differential diagnosis to chorea minor.

[Familial paroxysmal choreoathetosis. Clinical course, L-dopa-effect (author's transl)]

The clinical course of two boys with familial paroxysmal choreoathetosis was traced. As far as the medical history could be retrieved, their family has been affected by this disease for three generations. Except for this disorder, the patients' development and psychophysical state are unremarkable. Both boys responded well but at times incompletely to anticonvulsants. Therefore L-Dopa was introduced to the therapeutic regime of the younger, more severely affected boy. L-Dopa caused an appreciable decline of the frequency of the paroxysms.

[Cross stability in conventional shoes by the use of spring steel insoles: a pedobarographic effect study with observational application]

BACKGROUND

From an orthopedic point of view, wearing conventional ready to wear shoes negatively affects the front transverse arch of the human foot by forcing it into an unnatural inverted position.

OBJECTIVES

The aim of the present orthopedic application study was to conduct a standardized assessment of the biomechanical effect of a newly developed, longitudinally flexible and cross stable spring steel insole by means of pedobarographic measurements and by means of a supplementary questioning of the participants.

MATERIAL AND METHODS

In order to do this a total of 33 healthy adult participants were recruited in summer 2013. The randomized, blinded and controlled main study compared the cross stable insole made from spring steel with a flat, ordinary control insole made from ethylene vinyl acetate by means of pedobarographic in-shoe measurements at the forefoot. Additionally, the subjectively perceived effect of the steel insole with respect to comfort, restricted mobility and pain was assessed in a randomized, blinded and controlled ancillary study, using a cross-over design.

RESULTS

Both the plantar peak pressure and the plantar force-time integral were significantly higher with the spring steel insole, especially in the central forefoot. In the subsequent test phase lasting several weeks during which the participants were asked to wear the spring steel insole, they rarely complained about problems and in particular did not report negative effects regarding comfort, restricted mobility and pain compared to the ordinary control insoles.

CONCLUSION

The present study was conducted according to high methodological standards and proved for the first time that the tested spring steel insoles have a positive effect on the human forefoot. The cross stability increases the pressure in the median ball area, prevents the unnatural inverted position of the forefoot and thus creating an effect which is comparable to walking barefoot. As the participants did not judge this orthopedic effect of the cross stability as being uncomfortable, such an insole could be used a millionfold as a primary prevention in conventional shoes.

Design of oligolactone-based scaffolds for bone tissue engineering

Novel difunctional oligolactone macromers have been synthesized by ring-opening oligomerization of various lactones (L-lactide, glycolide, p-dioxanone) in the presence of suitable diols (propane-1,2-diol, dianhydro-D-glucitol) and subsequent endcapping of the formed oligolactones with methacrylate moieties. Based on these macromers, two fabrication procedures were developed to fabricate highly porous scaffolds and the material properties including in vitro biodegradation behaviour of the resulting polymeric scaffolds were investigated. Preliminary in vitro studies on the cytocompatibility of the fabricated scaffolds and on osteoblast cultivation on the optimized polymeric materials demonstrated that the oligolactide based polymer networks possess an excellent biocompatibility and that they are promising candidates as scaffolds in bone tissue engineering.

[Macrocephaly as the initial manifestation of glutaryl-CoA-dehydrogenase deficiency (glutaric aciduria type I)]

Glutaric aciduria type I is due to an impaired glutaryl-CoA-dehydrogenase with an increased urinary excretion of glutaric and 3-OH glutaric acid. Typically, the clinical course until the sixth month or even 3rd year of life is symptom free, and only later an encephalopathic crisis develops. The only symptom of our 4 patients was macrocephaly (head circumference greater than 97. percentile) in early infancy. 3 of them suffered from an encephalopathic crisis at 8 months to 3 years of age; during that time they lost already established abilities as sitting, walking and speaking, and developed choereoathetotic movements. One child aged 15 months was normal beside it's macrocephalus. All children were treated with a diet low in lysine (80 mg/kg BW/day), tryptophane (21 mg/kg BW/day), and by supplementation of L-carnitine (200 mg/kg BW/day) and riboflavine (200 mg/day) and the motorically disturbed children received Lioresal 1 mg/kg BW/day. The effect of this treatment cannot be evaluated so far, but there is evidence that the dietetic therapy together with carnitine supplementation may prevent further deterioration in affected, or an encephalopathic crisis in unaffected patients. Therefore we suggest to investigate organic acids in urine in every child or infant with macrocephalus to exclude glutaric aciduria type I.