Novel mutations in the tyrosine hydroxylase gene in the first Czech patient with tyrosine hydroxylase deficiency.

Tyrosine hydroxylase deficiency manifests mainly in early childhood and includes two clinical phenotypes: an infantile progressive hypokinetic-rigid syndrome with dystonia (type A) and a neonatal complex encephalopathy (type B). The biochemical diagnostics is exclusively based on the quantitative determination of the neurotransmitters or their metabolites in cerebrospinal fluid (CSF). The implementation of neurotransmitter analysis in clinical praxis is necessary for early diagnosis and adequate treatment. Neurotransmitter metabolites in CSF were analyzed in 82 children (at the age 1 month to 17 years) with clinical suspicion for neurometabolic disorders using high performance liquid chromatography (HPLC) with electrochemical detection. The CSF level of homovanillic acid (HVA) was markedly decreased in three children (64, 79 and 94 nmol/l) in comparison to age related controls (lower limit 218-450 nmol/l). Neurological findings including severe psychomotor retardation, quadruspasticity and microcephaly accompanied with marked dystonia, excessive sweating in the first patient was compatible with the diagnosis of tyrosine hydroxylase (TH) deficiency (type B) and subsequent molecular analysis revealed two novel heterozygous mutations c.636A>C and c.1124G>C in the TH gene. The treatment with L-DOPA/carbidopa resulted in the improvement of dystonia. Magnetic resonance imaging studies in two other patients with microcephaly revealed postischaemic brain damage, therefore secondary HVA deficit was considered in these children. Diagnostic work-up in patients with neurometabolic disorders should include analysis of neurotransmitter metabolites in CSF.

EkoSonicSV endovascular system for recanalization of the basilar artery occlusion.

The interventional management of stroke may consist of the use of angioplasty, stenting or mechanical thrombus removal technique. For this purpose several retrieval devices are being used. Recently the new alternative device - EkoSonicSV has been introduced, which is particularly suitable for recanalization of the occluded basilar artery (BA). Here we are presenting a complete recanalization of BA using this device in two patients with stroke over a short period of time together with the intra-arterial use of recombinant tissue plasminogen activator and application of intravascular ultrasound.

Endovascular treatment of mycotic pseudoaneurysms.

The surgical correction of ruptured intracranial infectious pseudoaneurysms is associated with high morbidity and mortality. An endovascular therapeutic approach has been introduced recently. This treatment is, compared to surgical intervention, less invasive, faster, more effective and safer, thus making it a gentler option, particularly for pediatric patients. Lower morbidity and mortality have been achieved thanks to the combination of prolonged administration of antibiotics, coil embolization, and parent artery occlusion. Two pediatric cases of bleeding mycotic pseudoaneurysm treated successfully with fibered coil embolization and long-term antibiotics are dealt with in this manuscript.

The potential of RFID technology in Blood Center processes.

Current RFID technology deployment is limited by safety, procedural and physical limitations in healthcare field. It is important to define and ensure safe operation of technologies without actual deployment in real operation. Potential problems could arise due to the consequences of technical and physical characteristics of RFID technology and its improper location. This article deals with manipulation of blood products and the definition of suitable places for radio identification. Each suitable place must undergo laboratory experiments and tests. The results can provide a convenient base for defining efficient and safe deployment of RFID technology in Blood Centers with substantial financial savings for Czech healthcare.

Cell therapy, a new standard in management of chronic critical limb ischemia and foot ulcer.

Fifty percent of diabetics (7% of general population) suffer from peripheral arterial occlusive disease, which may lead to amputation due to critical limb ischemia (CLI). The aim of our study was to prevent major limb amputation (MLA) in this group of patients using a local application of autologous bone marrow stem cells (ABMSC) concentrate. A total of 96 patients with CLI and foot ulcer (FU) were randomized into groups I and II. Patients in group I (n = 42, 36 males, 6 females, 66.2 ± 10.6 years) underwent local treatment with ABMSC while those in group II (n = 54, control, 42 males, 12 females, 64.1 ± 8.6 years) received standard medical care. The frequency of major limb amputation in groups I and II was 21% and 44% within the 120 days of follow up, respectively (p < 0.05). Only in salvaged limbs of group I both toe pressure and toe brachial index increased (from 22.66 ± 5.32 to 25.63 ± 4.75 mmHg and from 0.14 ± 0.03 to 0.17 ± 0.03, respectively, mean ± SEM). The CD34(+) cell counts in bone marrow concentrate (BMC) decreased (correlation, p = 0.024) with age, even though there was no correlation between age and healing. An unexpected finding was made of relative, bone marrow lymphopenia in the initial bone marrow concentrates in patients who failed ABMSC therapy (21% of MLA). This difference was statistically significant (p < 0.040). We conclude ABMSC therapy results in 79% limb salvage in patients suffering from CLI and FU. In the remaining 21% lymphopenia and thrombocytopenia were identified as potential causative factors, suggesting that at least a partial correction with platelet supplementation may be beneficial.

Autologous bone marrow stem cell transplantation in patients with end-stage chronical critical limb ischemia and diabetic foot.

A total 37 patients suffering from end stage-IV Fontaine (CLI and diabetic foot) with an ulcerated limb in whom all previous therapeutic strategies failed (e.g. surgical revascularization and endovascular repair) were selected and underwent local transplantation of Autologous Bone Marrow Stem Cells (ABMSCs). The efficacy/safety ofthis therapy was assessed by using several endpoints such as (a) prevention of amputation, (b) wound healing and (c) degree of angiogenesis. In order to assess the limb ischemia and hypoxia the several tests and measurements were performed pre- and post transplantation at a variety of time intervals. The measurements include: TP-toe pressure measurements (by Periflux 5000 Laser Doppler and Oxymetry system), SPP-skin perfusion pressure, ABI-ankle brachial index, LDP-Laser Doppler baseline and heat perfusion assessment, TcpO2 without and with O2 provocation inhalation test. In addition, a battery of biochemical and hematological tests of peripheral venous blood samples and bone marrow analysis were performed. Limb salvage was 81% in 30 patients, 7 patients (19%) were amputated for terminal severe ischemia and gangrene progression. In the group of limb salvage patients initial Toe pressure 23.119 (std. error 5.358) increased in 90 days follow-up into 29.888 (std. error 5.99), Toe brachial index increased from 0.1469 (std. 0.0326) to 0.1991(std. 0.401). In LASER doppler and TcpO2, TcpCO2 tissue perfusion examination TcpO2% Increase after O2 provocation inhalation test was elevated from 162.95 (%) to 229.86% which confirmed a very good tissue vasoreactivity after BMSC transplantation.

[Prevention of venous thromboembolism in surgery, laparoscopic surgery and urology]. / Prevence zilního tromboembolizmu v chirurgii, laparoskopické chirurgii, urologii.

Deep venous thrombosis and pulmonary embolism are major health problems with potential serious outcomes. Acutely, pulmonary embolism may be fatal. In the long term, pulmonary hypertension can develop from recurrent pulmonary embolism. Often overlooked is post-thrombotic chronic venous insufficiency occurring as a result of deep venous thrombosis causing deep venous reflux or obstruction with skin changes and ulceration with adverse impact on quality of life and escalation of health care costs. Almost all hospitalized patients have at least one risk factor for venous thrombosis and approximately 40% have three or more risk factors. Without thromboprophylaxis, the incidence of objectively confirmed, hospital-acquired deep venous thrombosis is approximately 10 to 40% among medical or general surgical patients and 40 to 60% following major orthopedic surgery. Abundant data from metaanalysis and blinded, randomized clinical trials have demonstrated strong evidence that primary thromboprophylaxis reduces deep venous thrombosis and pulmonary embolism and little or no increase in the rates of clinically important bleeding with prophylactic doses of low-dose unfractionated heparin, low-molecular-weight heparin or fondaparinuxem.

[Bleeding complications of anticoagulant therapy]. / Krvácivé komplikace antikoagulacní lécby.

Anticoagulant therapy is one of the most common forms of medical intervention. It is the mainstay of prevention and treatment of thrombotic events. Omission of adequate anticoagulant prophylaxis at least for moderate-risk and high-risk patients is a widely recognized medical error. Bleeding is one of the most feared complications of anticoagulant therapy, and is a risk of all anticoagulants. Whereas unfractionated heparin and warfarin, the oldest and most widely used anticoagulants, have specific antidotes for their anticoagulant effect, many of the newer agents (direct and indirect inhibitors of coagulation factors Xa and/or IIa) do not have specific antidotes to reverse their actions. The use of novel anticoagulants is further complicated by a lack of easily available laboratory tests to measure their levels and thereby optimize their benefit and safety in clinical practice. In this review, we evaluate the risk of bleeding associated with current anticoagulants, review the data available on current and experimental agents used for the reversal of anticoagulation, and provide recommendations for the management of major bleeding associated with anticoagulant therapy and for the management of asymptomatic overdosing of the anticoagulants.

A combined approach to treatment of the dissecting middle cerebral artery fusiform aneurysm. A case report.

SUMMARY: A fusiform aneurysm in the terminal M1 middle cerebral artery (MCA) segment was treated by a construction of a high-flow arterial extracranial-intracranial (EC-IC) bypass. Due to severe bypass vasospasms, local vasodilating agents together with percutaneous angioplasty and stent implantation were applied, but failed due to subsequent bypass occlusion. To remedy this complication a new bypass was created from a segment of the saphenous vein, followed by MCA aneurysm embolization and parent artery occlusion. One year after the surgery, the venous bypass remains patent and the aneurysm occluded, with the patient fully active, without any neurological sequelae.

Emerging anticoagulants: mechanism of action and future potential.

Medical needs associated with diverse thromboembolic conditions are not fully met by currently available anticoagulants. Of those, unfractionated heparin (UFH) is gradually replaced by low molecular weight heparin (LMWH) for prevention and treatment of venous thromboembolism and acute coronary syndromes, along with supportive treatment with oral anticoagulants, such as warfarin derivatives. While generally effective these agents have several shortcomings involving compliance, delivery, efficacy and safety considerations in various disease settings, and for these reasons new anticoagulants are sought, to target more specifically the critical effectors and steps in the blood coagulation process, namely: (i) initiation, (ii) propagation and (iii) the phase of thrombin activity. The emerging agents that block tissue factor/factor VIIa-dependent initiation phase of the coagulation cascade, include: recombinant tissue factor pathway inhibitor (rTFPI), nematode anticoagulant peptide (NAPc2), active site-blocked factor VIIa (FVIIai) and TF targeting antibodies. Some of them are currently evaluated in clinical trials with promising results. Propagation phase of thrombus formation (e.g. the activity of factors IXa, Xa, VIIIa or Va) is targeted mainly by various indirect, direct and bimodal inhibitors, such as fondaparinux, indraparinux, tick anticoagulant peptide (TAP), antistatin (ANT) and antithrombin-heparin covalent complex (ATH), all endowed mostly with an anti-Xa activity. Although promising, some of these agents (TAP, ANT and ATH) have not progressed beyond animal testing while others (fondaparinux) was already assessed for prevention and treatment of venous thromboembolism and for treatment of arterial thrombosis. Lastly, inhibitors of thrombin activity are composed of either indirect (UFH, LMWH), or direct thrombin (FIIa) inhibitors including: hirudin, argatroban, melagatran, ximelagatran, dabigatran, and bivalirudin. These agents are either in advanced development or already approved for clinical use. Bimodal FIIa inhibitory activity of ATH was demonstrated in animal models of venous and arterial thrombosis, but is in need of further development. In conclusion, while some of these emerging anticoagulants, such as fondaparinux, idraparinux, ximelagatran and ATH appear to possess superior efficacy-safety profile, as compared to their conventional predecessors (UFH, LMWH and warfarin), their cost-effectiveness, side effects and antidote availability have to be considered. More importantly, coagulation factors that are targets of these inhibitory activities also affect coagulation independent processes, such as wound healing, inflammation, angiogenesis, mitogenesis and cell survival. Thus the consequences of both coagulation-dependent and -independent effects of new agents should be carefully considered before proper clinical indications are established.

Genetic determinants of cancer coagulopathy, angiogenesis and disease progression.

Progression of human malignancies is accompanied by vascular events, such as formation and remodeling of blood vessels and systemic coagulopathy. Though long appreciated as comorbidity of cancer (Trousseau syndrome), vascular involvement is increasingly recognized as a central pathogenetic mechanism of tumor growth, invasion and metastasis. The major outstanding question in relation to this role has been, whether vascular perturbations are simply a reaction to the conditions of the tumor microenvironment, or are linked to the known genetic lesions causal for the onset and progression of malignancy. In this regard, we have previously hypothesized, and recently demonstrated experimentally that deregulation of certain hemostatic mechanisms, namely upregulation of tissue factor (TF) and possibly other changes (e.g. expression of thrombin receptor - PAR-1) are controlled by cancer-associated oncogenic events, such as activation of K-ras, epidermal growth factor receptor (EGFR), or inactivation of the p53 tumor suppressor gene in various human cancer cells. It appears that these respective transforming alterations exert their impact on both, cell-associated and soluble/circulating (microvesicle- associated) TF, i.e. may cause a systemic hypercoagulable state. Other genes, which more recently emerged as regulators of cancer coagulopathy include: PML-RARalpha, PTEN, and MET. While the spectrum of procoagulant targets of these genes may vary somewhat it includes: TF, PAI-1, COX-2 and possibly other hemostatic proteins. It is noteworthy that these prothrombotic changes may impact the malignant process directly (e.g. stimulate angiogenesis, tumor growth or metastasis) as a consequence of both coagulation-dependent and -independent effects. The latter are mostly related to cellular signaling events and changes in gene expression which are now known to be induced by the TF/FVIIa/Xa complex, thrombin and PARs, expressed on the surface of cancer cells, as well as tumor-associated endothelium. Interestingly, certain anticoagulants possess antimetastatic and anticancer properties (e.g. LMWH), an observation that further suggests that hypercoagulability may act as an effector mechanism of genetically driven tumor progression. Conversely, we suggest that oncogene-directed (targeted) anticancer agents could, at least in some cases, ameliorate not only cellular transformation itself, but also some of the chronic components of the cancer-related coagulopathy, something that may be relevant to therapeutic efficacy of these drugs. We also postulate that since TF is the oncogene target, circulating TF (microparticles) could serve as surrogate marker of the biological activity oncogene-directed agents exert in vivo. Thus, both genetic and epigenetic factors appear to conspire to activate various components of the hemostatic system in cancer patients, both locally and systemically. These activities act as mediators of cancer coagulopathy, angiogenesis, metastasis and other events involved in disease progression and should be recognized in designing better anticancer therapies.

Heparin compromises streptokinase-induced arterial patency in rabbits.

INTRODUCTION: Little is known with regard to efficacy of heparin as an adjunct to fibrinolytics under conditions of severe vascular damage. In this study, we compared the effects of unfractionated heparin (UH), low-molecular weight heparin (LMWH), and recombinant desulfohirudin (HIR) in combination with streptokinase (SK) in such settings. MATERIALS AND METHODS: We used an established rabbit model, in which thrombosis, critical stenosis, and vascular wall damage were introduced to a segment of the abdominal aorta and the effects of the respective therapies were assessed by time to patency (TTP in minutes), cumulative patency (CP (%)), lysis of original clot (CL (%)), and net clot accretion (NCA (%)). Treatments were administered over 90 min at the following doses: SK: 33,000 U/kg, UH: 125-250 U/kg, LMWH: 1.25-2.5 mg/kg, HIR: 0.25-0.55 mg/kg. RESULTS: Unexpectedly, UH and LMWH had a paradoxical and detrimental effect on SK-mediated recanalization as measured by both TTP and CP. Thus, administration of SK vs. SK+UH or SK+LMWH resulted in TTP values of 43+/-8 min vs. 70+/-11 min (p<0.05) and 67+/-12 min. (p<0.08), respectively. For CP, the corresponding values were 21+/-7%, 0.5+/-0.3% and 9+/-8%. This delay in vessel recanalization occurred despite excessive systemic anticoagulation (activated partial thromboplastin time (aPTT) and thrombin clotting time (TCT) ratios >6 and >34, respectively). Of interest, both heparinoids completely inhibited SK-induced fibrinogen consumption (FC). In contrast, recombinant desulfohirudin (HIR) shortened SK-induced TTP (4.97+/-0.81 min) without preserving fibrinogen. CONCLUSIONS: Our findings suggest that caution needs to be exercised, when using the combination of SK and heparinoids for the treatment of arterial thrombosis under conditions of severe vascular damage and stenosis.

The benefit-to-risk profile of melagatran is superior to that of hirudin in a rabbit arterial thrombosis prevention and bleeding model.

Although hirudin is better than heparin at preventing recurrent ischemia in patients with unstable angina, hirudin produces more bleeding. The purpose of this study was to use a rabbit arterial thrombosis prevention and ear bleeding model to determine whether for equivalent efficacy, melagatran, a synthetic direct thrombin inhibitor, is safer than hirudin. A combination of balloon injury and stasis was used to induce thrombosis in the distal aorta, and patency and blood flow were continuously monitored with ultrasonic flow probes. Rabbits were randomized to melagatran (in total doses of 78-313 nmol kg(-1)), hirudin (in total doses of 18-107 nmol kg(-1)), or saline over 90 min. To assess safety, blood loss from standardized ear incisions was measured. Both melagatran and hirudin produced dose-dependent increases in patency and blood flow. At doses that maintained the highest levels of patency, however, melagatran produced 2-3-fold less bleeding than hirudin. Thus, at maximally effective doses, melagatran causes less bleeding than hirudin in this model. These findings raise the possibility that some direct thrombin inhibitors are safer than others.

[Variation in manifestations of heteroplasmic mtDNA mutation 8993 T>G in two families]. / Rozmanitost projevu heteroplazmické mtDNA mutace 8993 T > G ve dvou rodinách.

BACKGROUND: The most frequent manifestations of heteroplasmic mitochondrial DNA (mtDNA) mutation 8993 T > G are Leigh syndrome or NARP syndrome (Neurogenic Muscle Weakness, Ataxia, and Retinitis Pigmentosa). The authors describe heterogeneity of clinical symptoms and results of biochemical and molecular analyses in seven severely clinically affected children from two unrelated families with heteroplasmic mtDNA mutation 8993 T > G. METHODS AND RESULTS: Seven clinically affected children from two unrelated families were born in term after an uneventful pregnancy. The failure to thrive, psychomotor retardation, hypotonic or spastic quadruparesis, hypertrophic cardiomyopathy, hepatopathy and hyperlactacidaemia developed after birth. Five children died in the first year of life during acute respiratory infection, one girl died at the age of 3 months with sudden death syndrome, only one boy with spastic quadruparesis and severe psychomotor retardation survived to the age of 8 years. Molecular analyses in all investigated children and their clinically non-affected mothers revealed the presence of heteroplasmic mtDNA mutation 8993 T > G. Mutated copies of mtDNA molecules in maternal tissues were in the range of 15-22%. The mutation load in all analysed children's tissues was higher than 90%. CONCLUSIONS: A broad spectrum of clinical symptoms may be observed in families with heteroplasmic mtDNA mutations 8993 T > G. Affected children with a mutation load higher than 90% usually do not survive after infancy. In both investigated families, a profound increase in the levels of heteroplasmy of mtDNA mutation 8993 T > G was observed in two subsequent generations.

Blood-compatible biomaterials by surface coating with a novel antithrombin-heparin covalent complex.

Covalent antithrombin-heparin complex (ATH) was covalently grafted to a polycarbonate urethane (Corethane) endoluminal graft (a kind gift of Corvita Corporation) after being activated using 0.3% m/m NaOCl in 0.15 M phosphate pH 6.0. ATH graft density (1.98 x 10(-7) mol/m2) was 6 times the maximum amount of unfractionated heparin (UFH) that could be bound to polycarbonate urethane surfaces. Surface-bound ATH could be stored in sterile 0.15 M NaCl at 4 degrees C for at least 2 months with good antithrombotic activity before being implanted into rabbits. Analysis of ATH-coated tubing showed that it contained significant direct thrombin inhibitory activity. In vivo testing in a rabbit model was compared to non-activated non-coated surfaces, activated-non-coated surfaces, hirudin-coated surfaces and antithrombin (AT)-coated surfaces. The weight of the clot generated in the ATH-coated graft tubing was significantly less than the weight of the clot generated within the hirudin-coated graft (p = 0.03 with a 1-tailed Student's t test). The anticoagulant nature of ATH grafts in vivo was shown to be due to bound ATH because boththe AT-coated surfaces and non-coated but activated surfaces showed similar thromboresistant efficacy to that of untreated material (ANOVA; p < 0.05). Apart from the direct antithrombin activity that contributed to much of the prolonged patency in vivo, surface-bound ATH likely catalyzed AT inhibition of thrombin, as evidenced by a significant number of 125I-AT binding sites (> or = 1.5 x 10(-8) mol/m2). Thus, ATH appears to be a good candidate for coating cardiovascular devices, such as endoluminal grafts, with high levels of substitution and significant long-term blood-compatibility.

The hemostatic system and angiogenesis in malignancy.

Coagulopathy and angiogenesis are among the most consistent host responses associated with cancer. These two respective processes, hitherto viewed as distinct, may in fact be functionally inseparable as blood coagulation and fibrinolysis, in their own right, influence tumor angiogenesis and thereby contribute to malignant growth. In addition, tumor angiogenesis appears to be controlled through both standard and non-standard functions of such elements of the hemostatic system as tissue factor, thrombin, fibrin, plasminogen activators, plasminogen, and platelets. "Cryptic" domains can be released from hemostatic proteins through proteolytic cleavage, and act systemically as angiogenesis inhibitors (e.g., angiostatin, antiangiogenic antithrombin III aaATIII). Various components of the hemostatic system either promote or inhibit angiogenesis and likely act by changing the net angiogenic balance. However, their complex influences are far from being fully understood. Targeted pharmacological and/or genetic inhibition of pro-angiogenic activities of the hemostatic system and exploitation of endogenous angiogenesis inhibitors of the angiostatin and aaATIII variety are under study as prospective anti-cancer treatments.

[Prenatal diagnosis in families with cytochrome C oxidase disorder]. / Prenatální diagnostika v rodinách s poruchou aktivity cytochrom C oxidázy.

OBJECTIVE: Cytochrome c oxidase (COX) deficiency presents with severe impairment of brain, muscle or heart. Prenatal diagnosis in affected families is difficult because the disease may be caused by mutations in nuclear or mtDNA. This study shows the results of prenatal diagnosis in two families where the first child died because of a generalised COX defect. In both cases the low activity of COX was accompanied by a low content of the enzyme. SUBJECTS: In the first family the amniocentesis was performed during the second pregnancy and cultured amniocytes showed a marked decrease of COX activity and ATP production. Based on decision of the parents the pregnancy was terminated. Analysis of the foetal tissues confirmed a generalised COX defect. In the second family the nuclear origin of the COX defect was found using transmitochondrial cybrids derived from COX-deficient fibroblasts of the affected child. In the successive pregnancy with dizygotic twins a combined amniocentesis and chorionic villi biopsy has been performed. Prenatal diagnosis was based in both foetuses on three independent approaches. COX activity, the ATP production and protein content of COX complex was measured in cultivated foetal cells. The results of all investigations excluded a putative COX defect and both children are healthy at the age of 2 and half years. CONCLUSION: Prenatal diagnosis of COX disorders is available in families with the generalised form of the disease based on a nuclear origin of COX deficiency. Three independent approaches to characterise COX at a functional, enzymatic and protein level may be used.

A novel approach to arterial thrombolysis.

Achieving early, complete, and sustained reperfusion after acute myocardial infarction does not occur in approximately 50% of patients, even with the most potent established thrombolytic therapy. Bleeding is observed with increased concentrations of thrombolytics as well as with adjunctive antithrombotic and antiplatelet agents. A novel approach to enhance thrombolytic therapy is to inhibit the activated form of thrombin-activatable fibrinolysis inhibitor (TAFI), which attenuates fibrinolysis in clots formed from human plasma. Identification of TAFI in rabbit plasma facilitated the development of a rabbit arterial thrombolysis model to compare the thrombolytic efficacy of tissue-plasminogen activator (tPA) alone or with an inhibitor, isolated from the potato tuber (PTI), of activated TAFI (TAFIa). Efficacy was assessed by determining the time to patency, the time the vessel remained patent, the maximal blood flow achieved during therapy, the percentage of the original thrombus, which lysed, the percentage change in clot weight, the net clot accreted, and the release of radioactive fibrin degradation products into the circulation. The results indicate that coadministration of PTI and tPA significantly improved tPA-induced thrombolysis without adversely affecting blood pressure, activated partial thromboplastin time, thrombin clotting time, fibrinogen, or alpha-2-antiplasmin concentrations. The data indicate that inhibitors of TAFIa may comprise novel and very effective adjuncts to tPA and improve thrombolytic therapy to achieve both clot lysis and vessel patency.

A novel deficiency of mitochondrial ATPase of nuclear origin.

We report a new type of fatal mitochondrial disorder caused by selective deficiency of mitochondrial ATP synthase (ATPase). A hypotrophic newborn from a consanguineous marriage presented severe lactic acidosis, cardiomegaly and hepatomegaly and died from heart failure after 2 days. The activity of oligomycin-sensitive ATPase was only 31-34% of the control, both in muscle and heart, but the activities of cytochrome c oxidase, citrate synthase and pyruvate dehydrogenase were normal. Electrophoretic and western blot analysis revealed selective reduction of ATPase complex but normal levels of the respiratory chain complexes I, III and IV. The same selective deficiency of ATPase was found in cultured skin fibroblasts which showed similar decreases in ATPase content, ATPase hydrolytic activity and level of substrate-dependent ATP synthesis (20-25, 18 and 29-33% of the control, respectively). Pulse-chase labelling of patient fibroblasts revealed low incorporation of [(35)S]methionine into assembled ATPase complexes, but increased incorporation into immunoprecipitated ATPase subunit beta, which had a very short half-life. In contrast, no difference was found in the size and subunit composition of the assembled and newly produced ATPase complex. Transmitochondrial cybrids prepared from enucleated fibroblasts of the patient and rho degrees cells derived from 143B. TK(-)human osteosarcoma cells fully restored the ATPase activity, ATP synthesis and ATPase content, when compared with control cybrids. Likewise, the pattern of [(35)S]methionine labelling of ATPase was found to be normal in patient cybrids. We conclude that the generalized deficiency of mitochondrial ATPase described is of nuclear origin and is caused by altered biosynthesis of the enzyme.

Defective kinetics of cytochrome c oxidase and alteration of mitochondrial membrane potential in fibroblasts and cytoplasmic hybrid cells with the mutation for myoclonus epilepsy with ragged-red fibres ('MERRF') at position 8344 nt.

We have investigated pathogenic effects of the tRNA(Lys) A8344G mutation associated with the syndrome myoclonus epilepsy with ragged-red fibres (MERRF) by using fibroblasts and fibroblast-derived cytoplasmic hybrid cells harbouring different percentages of mutated mitochondrial DNA (mtDNA). The activity of cytochrome c oxidase (COX) in patient fibroblasts with 89% mutated mtDNA was decreased to 20% of the control levels. COX exhibited altered kinetics, with a decreased V(max) for both the low-affinity and high-affinity phases; however, the K(m) values were not significantly changed. The substrate-dependent synthesis of ATP was decreased to 50% of the control. Analysis of the mitochondrial membrane potential, DeltaPsi, in digitonin-treated cells with tetramethylrhodamine methyl ester (TMRM) with the use of flow cytometry showed a 80% decrease in DeltaPsi at state 4 and an increased sensitivity of DeltaPsi to an uncoupler in fibroblasts from the patient. The investigation of transmitochondrial cytoplasmic hybrid clones derived from the patient's fibroblasts enabled us to characterize the relationship between heteroplasmy of the MERRF mutation, COX activity and DeltaPsi. Within the range of 87-73% mutated mtDNA, COX activity was decreased to 5-35% and DeltaPsi was decreased to 6-78%. These results demonstrate that the MERRF mutation affects COX activity and DeltaPsi in different proportions with regard to mutation heteroplasmy and indicate that the biochemical manifestation of the MERRF mutation exerts a very steep threshold of DeltaPsi inhibition.