Relationship between action potential, contraction-relaxation pattern, and intracellular Ca2+ transient in cardiomyocytes of dogs with chronic heart failure

Abnormalities of contractile function have been identified in cardiomyocytes isolated from failed human hearts and from hearts of animals with experimentally induced heart failure (HF). The mechanism(s) responsible for these functional abnormalities are not fully understood. In the present study, we examined the relationship between action potential duration, pattern of contraction and relaxation, and associated intracellular Ca2+ transients in single cardiomyocytes isolated from the left ventricle (LV) of dogs (n = 7) with HF produced by multiple sequential intracoronary microembolizations. Comparisons were made with LV cardiomyocytes isolated from normal dogs. Action potentials were measured in isolated LV cardiomyocytes by perforated patch clamp, Ca2+ transients by fluo 3 probe fluorescence, and cardiomyocyte contraction and relaxation by edge movement detector. HF cardiomyocytes exhibited an abnormal pattern of contraction and relaxation characterized by an attenuated initial twitch (spike) followed by a sustained contracture ('dome') of 1 to 8 s in duration and subsequent delayed relaxation. This pattern was more prominent at low stimulation rates (58% at 0.2 Hz, n = 211, 21% at 0.5 Hz, n = 185). Measurements of Ca2+ transients in HF cardiomyocytes at 0.2 Hz manifested a similar spike and dome configuration. The dome phase of both the contraction/relaxation pattern and Ca2+ transients seen in HF cardiomyocytes coincided with a sustained plateau of the action potential. Shortening of the action potential duration by administration of saxitoxin (100 nM) or lidocaine (30 microM) reduced the duration of the dome phase of both the contraction/relaxation profile as well as that of the Ca2+ transient profile. An increase of stimulation rate up to 1 Hz caused shortening of the action potential and disappearance of the spike-dome profile in the majority of HF cardiomyocytes. In HF cardiomyocytes, the action potential and Ca2+ transient duration were not significantly different from those measured in normal cells. However, the contraction-relaxation cycle was significantly longer in HF cells (314 +/- 67 ms, n = 21, vs. 221 +/- 38 ms, n = 46, mean +/- SD), indicating impaired excitation-contraction uncoupling in HF cardiomyocytes. The results show that, in cardiomyocytes isolated from dogs with HF, contractile abnormalities and abnormalities of intracellular Ca2+ transients at low stimulation rates are characterized by a spike-dome configuration. This abnormal pattern appears to result from prolongation of the action potential.     

Restoration of peak vascular conductance after simulated microgravity by maximal exercise

Free radical-mediated injury is implicated in hypoxic-ischemic encephalopathy observed in neonates. We investigated in utero free radical production and injury following hypoxia-ischemia to premature fetal brain utilizing a rabbit model of acute placental insufficiency. Pregnant rabbits at 29 days gestation were randomized to uterine ischemia for 50 minutes (min) (hypoxia) or nonischemic controls. Fetal brains were obtained immediately after ischemia for oxidative and acute-injury markers or 24 hours (h) post-ischemia for histopathology. Nitrotyrosine formation, a marker of NO-derived species such as peroxynitrite, was observed only in hypoxic brains. Hypoxia resulted in a significant increase in nitrogen oxides, lipid peroxidation, and protein oxidation, with a concomitant decrease in total antioxidant capacity, compared with controls. Peroxynitrite addition to brain homogenate increased nitrogen oxides linearly (1:1), although protein carbonyls were unchanged. Concomitantly, in vitro cortical and hippocampal cell viability and ATP levels decreased, with an increase in brain edema in hypoxic brains. Fetuses delivered 24 h post-ischemia had increased hippocampal nuclear karyorrhexis on histology compared with controls. Antioxidant administration (ascorbic acid and Trolox) intraperitoneally ameliorated changes in cellular viability and brain edema. Acute fetal hypoxia-ischemia without reoxygenation results in increased nitrogen and oxygen free radical production that may cause brain injury. The merits of the described model are discussed.     

The triggering signal dictates the effect of docosahexaenoic acid on lymphocyte function in vitro

Three of the proteins protecting cells from autologous lysis by complement are: membrane cofactor protein (MCP; CD46), an inhibitor of the membrane attack complex formation (CD59), and decay accelerating factor (DAF; CD55). We have investigated the expression of these proteins in breast and colorectal carcinoma by immunohistochemistry and immunoblotting of breast tissue for CD46. CD46 was consistently and strongly expressed in the epithelial compartment in 26/28 ductal carcinomas of the breast, 9/9 fibroadenomas, and 9/11 cases of control non-neoplastic breast tissue. CD59 showed a similar degree of expression in the fibroadenomas (9/9), but was less strongly expressed in carcinomatous (22/28) and control (5/11) tissues. In marked contrast, no CD55 expression was detected in tissue from 15 ductal carcinomas. Immunoblotting of breast tissue for CD46 showed the same size of the molecule as for lymphocytes. It had however considerably stronger expression in tumour tissue than in non-neoplastic tissue. CD46 and CD59 were either lacking or only weakly expressed in the epithelial component of control colorectal mucosa: 2/15 and 5/15, respectively. In contrast, tissue samples from colorectal adenocarcinomas showed clear staining for both CD59 (10/18) and, more markedly, CD46 (15/18). There was no association between the pattern or intensity of CD46 and CD59 expression and tumour differentiation. As the complement regulatory proteins CD46 and CD59 are also strongly expressed by trophoblast at the feto-maternal tissue interface, these results support the concept that similar mechanisms are employed both by the genetically dissimilar fetus and certain tumours to evade immune attack by their host.     

Outcomes of balloon coronary angioplasty of bifurcation stenoses in patients with ischemic heart disease

Specialists of the Research Institute of Urology have practiced combination of transurethral resection (TUR) with electrovaporization in endoscopic treatment of bladder cancer (BC) since 1995. A total of 46 patients with transient cell BC (29 males and 17 females aged 49-87) stage Ta-T1 (32 patients) and T2-T3b (14 patients) underwent TUR or electrovaporization (if morphologically verified) of the exophytic part of the tumor. In addition, electrovaporization of the base of the tumor was made. Main indications for such treatment were standard indications for TUR in contraindications for more radical treatment. 6-24-month follow-up was possible in 23(71.9%) patients with superficial BC (group 1) and in 9(64.2%) patients with invasive BC (group 2). Endoscopically, the recurrence was detected in 3(13%) and 5(55.5%) patients of group 1 and 2, respectively. They were reoperated on with electrovaporization. It is inferred that TUR-vaporization of the bladder is an effective endoscopic treatment of superficial BC. Electrovaporization is a good palliative treatment in patients with invasive BC when radical surgery is impossible. It inhibits the progression of the disease, prevents hemorrhages due to the tumor destruction, reduces intraoperative blood loss, improves endoscopic visualization. It may also increase the operation ablasticity.     

The past, present and future of cell pathology problems

Three stages of development in cellular pathology are analyzed. Evaluation of important achievements in the past which permitted the advance to the present stage in cellular pathology is given. New methods in experimental pathology resulted in the appearance of a new direction--molecular morphology and molecular cell pathology. The basic features of this direction and new problems to be resolved are formulated.     

Elevation of the serum bilirubin diconjugate fraction provides an early marker for cholestasis in the rat

OBJECTIVES: To determine whether the sisters of women with premature ovarian failure (POF) showed a response to gonadotropin stimulation comparable to that of anonymous ovum donors. DESIGN: Historical cohort study. SETTING: Records of 228 consecutive ovum recipients in an academic assisted reproductive technology program. PATIENT(S): Criteria for inclusion were oocyte recipients age < or = 40 years, FSH > 18 mIU/mL (conversion factor to SI unit, 1.00), and/or failure to respond appropriately to controlled ovarian hyperstimulation (COH). Seventy-nine recipients were classified on the basis of whether they received oocytes from anonymous donors (group I, n = 66) or sister donors (group II, n = 13). MAIN OUTCOME MEASURE(S): Controlled ovarian hyperstimulation response, pregnancy rates (PRs), and implantation rates. RESULT(S): The ages of the donors to groups I and II were comparable (31.1 +/- 16.7 versus 29.8 +/- 7.2 years), but those in group II exhibited a higher baseline FSH level (12.8 +/- 2.1 versus 8.6 +/- 5.8 mIU/mL). Group II versus I had a relative risk of 5.1 for cancellation (4 of 13 [30.8%] versus 4 of 66 [6.1%], respectively). In completed cycles of groups I and II, respectively, there was no difference in serum E2 on the day of hCG administration (2,356 +/- 826 versus 1,847 +/- 843 pg/mL; conversion factor to SI unit, 3,671), number of oocytes retrieved (25 +/- 14 versus 22 +/- 13), number of embryos transferred (4.4 +/- 2.1 versus 4.0 +/- 1.0), spontaneous abortion rate (22.7% versus 25.0%), PR (35.5% versus 36.4%), and implantation rate (16.2% versus 16.4%). CONCLUSION(S): There is an increased cancellation rate and, consequently, an overall trend toward decreased ovarian response to gonadotropin stimulation in the sisters of patients with POF. Despite these factors, the implantation rates and PRs of embryos derived from patients reaching retrieval were similar to those from anonymous donors. We recommend counseling women with POF that their sisters may not be ideal ovum donors.     

Genetic aspects of rheumatic diseases

The paper presents the results of the long-term studies of the pattern of hereditary predisposition to rheumatism, rheumatoid arthritis (RA), ankylosing spondyloarthritis (AS), osteoarthrosis which have been conducted at the Institute of Rheumatology, Russian Academy of Medical Sciences. It gives data on the type of inheritance of these diseases, the affliction heritability ratio, the penetrance of three genotypes within the model of an autosomal one-allele locus (SAL-2) for rheumatism and RA. The contribution of additive and dominant components in the determination of rheumatism and RA, the results of tests of their genetic heterogeneity, associations with HLA antigens are assessed. The paper outlines the results of tests of the candidate genes COLIA2, TCRB, TCRD as major RA predisposition genes via analysis of adherence and DNA polymorphism.     

The optimization of instrumental hemofiltration

47 hemofiltration procedures were performed in 10 patients. A self-made balancer based on the volumic hydrodynamics dependent on substitute from filtrate was used. An APD-02 peritoneal dialysis machine served the source of the substitute. It provided change of the concentration and was used for prophylaxis of osmodisturbances, massive dehydration and for obtaining bicarbonate substitute. The technology for F-60 cartridges reuse has been elaborated and tested. One of the patients received the isolated hemofiltration programme for more than 2 months. Antiuremic efficacy of hemofiltration was studied.