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1.
Ceska Gynekol ; 83(1): 50-52, 2018.
Article in Cs | MEDLINE | ID: mdl-29510640

ABSTRACT

OBJECTIVE: To present a case of conservative - Fallopian tube preserving - surgical therapy of tubal pregnancy. DESIGN: Case report. SETTING: Department of Obstetrics and Gynecology, Strakonice Hospital. CASE DESCRIPTION: Due to the desire to preserve the Fallopian tube in a hemodynamically stable primigravida, we decided for laparoscopic salpingostomy using hysteroscopy for assisted removal of pregnancy tissue from the oviduct. CONCLUSION: In well-selected cases, this treatment is an effective method of choice and can be performed even under conditions of a smaller hospital performing a common spectrum of laparoscopic surgery.


Subject(s)
Laparoscopy , Pregnancy, Tubal , Salpingostomy , Fallopian Tubes , Female , Humans , Pregnancy , Pregnancy, Tubal/surgery
2.
Cardiovasc Res ; 65(1): 221-9, 2005 Jan 01.
Article in English | MEDLINE | ID: mdl-15621050

ABSTRACT

OBJECTIVE: Cardiac energetics and performance depend on the expression level of the fast (alpha-) and slow (beta-) myosin heavy chain (MHC) isoform. In ventricular tissue, the beta-MHC isoform predominates, whereas in atrial tissue a variable mixture of alpha- and beta-MHC is found. In several cardiac diseases, the slow isoform is upregulated; however, the functional implications of this transition in human myocardium are largely unknown. The aim of this study was to determine the relation between contractile properties and MHC isoform composition in healthy human myocardium using the diversity in atrial tissue. METHODS: Isometric force production and ATP consumption were measured in chemically skinned atrial trabeculae and ventricular muscle strips, and rate of force redevelopment was studied using single cardiomyocytes. MHC isoform composition was determined by one-dimensional SDS-gel electrophoresis. RESULTS: Force development in ventricular tissue was about 5-fold more economical, but nine times slower, than in atrial tissue. Significant linear correlations were found between MHC isoform composition, ATP consumption and rate of force redevelopment. CONCLUSION: These results clearly indicate that even a minor shift in MHC isoform expression has considerable impact on cardiac performance in human tissue.


Subject(s)
Adenosine Triphosphate/metabolism , Atrial Function/physiology , Myocardium/metabolism , Ventricular Function/physiology , Adult , Aged , Aged, 80 and over , Biomechanical Phenomena , Electrophoresis, Polyacrylamide Gel , Heart Atria , Heart Ventricles , Humans , Middle Aged , Myocardial Contraction/physiology , Myosin Heavy Chains/metabolism , Protein Isoforms/metabolism
3.
Circulation ; 104(10): 1140-6, 2001 Sep 04.
Article in English | MEDLINE | ID: mdl-11535570

ABSTRACT

BACKGROUND: During ischemia, the intracellular calcium and inorganic phosphate (P(i)) concentrations rise and pH falls. We investigated the effects of these changes on force development in donor and failing human hearts to determine if altered contractile protein composition during heart failure changes the myocardial response to Ca(2+), P(i), and pH. METHODS AND RESULTS: Isometric force was studied in mechanically isolated Triton-skinned single myocytes from left ventricular myocardium. Force declined with added P(i) to 0.33+/-0.02 of the control force (pH 7.1, 0 mmol/L P(i)) at 30 mmol/L P(i) and increased with pH from 0.64+/-0.03 at pH 6.2 to 1.27+/-0.02 at pH 7.4. Force dependency on P(i) and pH did not differ between donor and failing hearts. Incubation of myocytes in a P(i)-containing activating solution caused a potentiation of force, which was larger at submaximal than at maximal [Ca(2+)]. Ca(2+) sensitivity of force was similar in donor hearts and hearts with moderate cardiac disease, but in end-stage failing myocardium it was significantly increased. The degree of myosin light chain 2 phosphorylation was significantly decreased in end-stage failing compared with donor myocardium, resulting in an inverse correlation between Ca(2+) responsiveness of force and myosin light chain 2 phosphorylation. CONCLUSIONS: Our results indicate that contractile protein alterations in human end-stage heart failure alter Ca(2+) responsiveness of force but do not affect the force-generating capacity of the cross-bridges or its P(i) and pH dependence. In end-stage failing myocardium, the reduction in force by changes in pH and [P(i)] at submaximal [Ca(2+)] may even be less than in donor hearts because of the increased Ca(2+) responsiveness.


Subject(s)
Calcium/pharmacology , Heart Failure/physiopathology , Heart Ventricles/drug effects , Phosphates/pharmacology , Adult , Aged , Aged, 80 and over , Dose-Response Relationship, Drug , Electrophoresis, Gel, Two-Dimensional , Female , Heart Failure/pathology , Heart Ventricles/cytology , Humans , Hydrogen-Ion Concentration , Male , Middle Aged , Myocardial Contraction/drug effects , Myosin Light Chains/drug effects , Myosin Light Chains/metabolism , Phosphorylation/drug effects , Ventricular Function
4.
J Appl Physiol (1985) ; 99(6): 2189-95, 2005 Dec.
Article in English | MEDLINE | ID: mdl-16051711

ABSTRACT

Isometric force production and ATPase activity were determined simultaneously in single human skeletal muscle fibers (n = 97) from five healthy volunteers and nine patients with chronic heart failure (CHF) at 20 degrees C. The fibers were permeabilized by means of Triton X-100 (1% vol/vol). ATPase activity was determined by enzymatic coupling of ATP resynthesis to the oxidation of NADH. Calcium-activated actomyosin (AM) ATPase activity was obtained by subtracting the activity measured in relaxing (pCa = 9) solutions from that obtained in maximally activating (pCa = 4.4) solutions. Fiber type was determined on the basis of myosin heavy chain isoform composition by polyacrylamide SDS gel electrophoresis. AM ATPase activity per liter cell volume (+/-SE) in the control and patient group, respectively, amounted to 134 +/- 24 and 77 +/- 9 microM/s in type I fibers (n = 11 and 16), 248 +/- 17 and 188 +/- 13 microM/s in type IIA fibers (n = 14 and 32), 291 +/- 29 and 126 +/- 21 microM/s in type IIA/X fibers (n = 3 and 5), and 325 +/- 32 and 205 +/- 21 microM/s in type IIX fibers (n = 7 and 9). The maximal isometric force per cross-sectional area amounted to 64 +/- 7 and 43 +/- 5 kN/m(2) in type I fibers, 86 +/- 11 and 58 +/- 4 kN/m(2) in type IIA fibers, 85 +/- 6 and 42 +/- 9 kN/m(2) in type IIA/X fibers, and 90 +/- 5 and 59 +/- 5 kN/m(2) in type IIX fibers in the control and patient group, respectively. These results indicate that, in CHF patients, significant reductions occur in isometric force and AM ATPase activity but that tension cost for each fiber type remains the same. This suggests that, in skeletal muscle from CHF patients, a decline in density of contractile proteins takes place and/or a reduction in the rate of cross-bridge attachment of approximately 30%, which exacerbates skeletal muscle weakness due to muscle atrophy.


Subject(s)
Adenosine Triphosphatases/metabolism , Heart Failure/pathology , Heart Failure/physiopathology , Isometric Contraction , Muscle Fibers, Fast-Twitch/pathology , Muscle Fibers, Slow-Twitch/pathology , Muscle, Skeletal/pathology , Muscle, Skeletal/physiopathology , Adult , Aged , Cells, Cultured , Enzyme Activation , Female , Humans , Male , Middle Aged , Stress, Mechanical
5.
Cardiovasc Res ; 57(2): 505-14, 2003 Feb.
Article in English | MEDLINE | ID: mdl-12566123

ABSTRACT

OBJECTIVE: Phosphorylation of the myosin light chain 2 (MLC-2) isoform expressed as a percentage of total MLC-2 was decreased in failing (21.1+/-2.0%) compared to donor (31.9+/-4.8%) hearts. To assess the functional implications of this change, we compared the effects of MLC-2 dephosphorylation on force development in failing and non-failing (donor) human hearts. METHODS: Cooperative effects in isometric force and rate of force redevelopment (K(tr)) were studied in single Triton-skinned human cardiomyocytes at various [Ca(2+)] before and after protein phosphatase-1 (PP-1) incubation. RESULTS: Maximum force and K(tr) values did not differ between failing and donor hearts, but Ca(2+)-sensitivity of force (pCa(50)) was significantly higher in failing myocardium (Deltap Ca(50)=0.17). K(tr) decreased with decreasing [Ca(2+)], although this decrease was less in failing than in donor hearts. Incubation of the myocytes with PP-1 (0.5 U/ml; 60 min) decreased pCa(50) to a larger extent in failing (0.20 pCa units) than in donor cardiomyocytes (0.10 pCa units). A decrease in absolute K(tr) values was found after PP-1 in failing and donor myocytes, while the shape of the K(tr)-Ca(2+) relationships remained unaltered. CONCLUSIONS: Surprisingly, the contractile response to MLC-2 dephosphorylation is enhanced in failing hearts, despite the reduced level of basal MLC-2 phosphorylation. The enhanced response to MLC-2 dephosphorylation in failing myocytes might result from differences in basal phosphorylation of other thin and thick filament proteins between donor and failing hearts. Regulation of Ca(2+)-sensitivity via MLC-2 phosphorylation may be a potential compensatory mechanism to reverse the detrimental effects of increased Ca(2+)-sensitivity and impaired Ca(2+)-handling on diastolic function in human heart failure.


Subject(s)
Calcium/physiology , Cardiac Myosins/metabolism , Heart Failure/metabolism , Myocytes, Cardiac/metabolism , Myosin Light Chains/metabolism , Adult , Calcium/pharmacology , Cardiac Myosins/physiology , Cells, Cultured , Electrophoresis, Gel, Two-Dimensional , Female , Heart Failure/physiopathology , Humans , Male , Middle Aged , Myocardial Contraction/drug effects , Myocardial Contraction/physiology , Myocytes, Cardiac/physiology , Myosin Light Chains/physiology , Phosphoprotein Phosphatases/pharmacology , Phosphorylation , Protein Phosphatase 1
6.
Cardiovasc Res ; 57(1): 37-47, 2003 Jan.
Article in English | MEDLINE | ID: mdl-12504812

ABSTRACT

OBJECTIVE: The alterations in contractile proteins underlying enhanced Ca(2+)-sensitivity of the contractile apparatus in end-stage failing human myocardium are still not resolved. In the present study an attempt was made to reveal to what extent protein alterations contribute to the increased Ca(2+)-responsiveness in human heart failure. METHODS: Isometric force and its Ca(2+)-sensitivity were studied in single left ventricular myocytes from non-failing donor (n=6) and end-stage failing (n=10) hearts. To elucidate which protein alterations contribute to the increased Ca(2+)-responsiveness isoform composition and phosphorylation status of contractile proteins were analysed by one- and two-dimensional gel electrophoresis and Western immunoblotting. RESULTS: Maximal tension did not differ between myocytes obtained from donor and failing hearts, while Ca(2+)-sensitivity of the contractile apparatus (pCa(50)) was significantly higher in failing myocardium (deltapCa(50)=0.17). Protein analysis indicated that neither re-expression of atrial light chain 1 and fetal troponin T (TnT) nor degradation of myosin light chains and troponin I (TnI) are responsible for the observed increase in Ca(2+)-responsiveness. An inverse correlation was found between pCa(50) and percentage of phosphorylated myosin light chain 2 (MLC-2), while phosphorylation of MLC-1 and TnT did not differ between donor and failing hearts. Incubation of myocytes with protein kinase A decreased Ca(2+)-sensitivity to a larger extent in failing (deltapCa(50)=0.20) than in donor (deltapCa(50)=0.03) myocytes, abolishing the difference in Ca(2+)-responsiveness. An increased percentage of dephosphorylated TnI was found in failing hearts, which significantly correlated with the enhanced Ca(2+)-responsiveness. CONCLUSIONS: The increased Ca(2+)-responsiveness of the contractile apparatus in end-stage failing human hearts cannot be explained by a shift in contractile protein isoforms, but results from the complex interplay between changes in the phosphorylation status of MLC-2 and TnI.


Subject(s)
Calcium/metabolism , Contractile Proteins/metabolism , Heart Failure/metabolism , Myocytes, Cardiac/metabolism , Adult , Aged , Atrial Myosins/metabolism , Blotting, Western , Cardiac Myosins/metabolism , Case-Control Studies , Cells, Cultured , Electrophoresis, Gel, Two-Dimensional , Female , Humans , Male , Middle Aged , Myosin Light Chains/metabolism , Phosphorylation , Protein Isoforms/metabolism , Troponin I/metabolism , Troponin T/metabolism
7.
Adv Exp Med Biol ; 538: 3-15, 2003.
Article in English | MEDLINE | ID: mdl-15098650

ABSTRACT

The increased Ca(2+)-responsiveness in end-stage human heart failure cannot be attributed to contractile protein isoform changes, but rather is the complex resultant of changes in degree of phosphorylation of VLC-2 and TnI. Despite the decreased basal level of VLC-2 phosphorylation the response to VLC-2 dephosphorylation is enhanced in failing myocytes, which might result from differences in endogenous phosphorylation of thin and thick filament proteins between donor and failing hearts. Taken together decreased VLC-2 phosphorylation in end-stage human heart failure might represent a compensatory process leading to an improvement of myocardial contractility by opposing the detrimental effects of increased Ca(2+)-responsiveness of force and impaired Ca(2+)-handling on diastolic function.


Subject(s)
Heart Ventricles/pathology , Myocardium/cytology , Myosin Light Chains/chemistry , Animals , Calcium/metabolism , Heart Failure/pathology , Humans , Models, Biological , Models, Chemical , Phosphorylation , Protein Isoforms , Pyrazoles/metabolism , Pyrimidines/metabolism
8.
Ginekol Pol ; 60(1): 33-7, 1989 Jan.
Article in Polish | MEDLINE | ID: mdl-2477313

ABSTRACT

The paper discusses the problem of treating Asherman's syndrome, which due to common procedures in gynaecology and obstetrics becomes more and more frequent occurrence in gynaecological practice. The genesis of this syndrome is often a result of a too intensive excochleation of the uterus, accompanying infection and lack of endometrial reaction to oestrogens. The authors discussed 14 cases of patients in whom, after excochleation of the uterus, there appeared intrauterine adhesions followed by amenorrhoea. The therapy consisted in removing the adhesions by means of a hysteroscope and inserting an intrauterine device the shape of which was selected depending on the character and localization of adhesions and applying oestrogens locally into the uterus cavity. In order to have the menstrual cycle reconstructed, the patients were administered orally hormones during 4 successive artificially reconstructed cycles. Among the patients undergoing therapy, 86% of them began to menstruate again and 57% of them got pregnant. The use of hysteroscopy reduced maximally the risk of breaking the continuity of the uterus during the resection of large adhesions. Inserting a proper device prevented the recurrence of adhesions and local administering oestrogens into the uterine cavity provided good conditions for the reconstruction of the endometrium.


Subject(s)
Amenorrhea/drug therapy , Administration, Oral , Adult , Amenorrhea/etiology , Chlormadinone Acetate/administration & dosage , Clinical Trials as Topic , Drug Therapy, Combination , Estradiol/administration & dosage , Female , Humans , Mestranol/administration & dosage
12.
J Mol Cell Cardiol ; 41(3): 467-77, 2006 Sep.
Article in English | MEDLINE | ID: mdl-16901501

ABSTRACT

The cellular mechanisms responsible for contractile dysfunction associated with atrial fibrillation (AF) are still poorly understood. Atrial fibrillation is often preceded by atrial dilatation. This study aimed to explain contractile alterations associated with AF and their relation to atrial dilatation, by studying the relationships between atrial dimensions, contractile protein composition, force production and Ca(2+)-sensitivity. Force development was determined in mechanically isolated single skinned cardiomyocytes from right atrial appendages from patients with sinus rhythm without (SR;n=9), or with atrial dilation (SR+AD;n=11) or atrial fibrillation (AF;n=16). Echocardiography showed that, compared to the SR group, mean right atrial dimensions were increased by 18% and 35% in the SR+AD and AF group, respectively (P<0.05). Protein composition was determined by 1- and 2-dimensional gel electrophoresis. Compared to the SR group, the AF group exhibited: a reduction in the kinetics of force redevelopment (K(tr)) in isolated atrial cardiomyocytes, enhanced protein expression of the slow myosin heavy chain isoform (beta-MHC), an increase in troponin T (TnT) phosphorylation and a marked increase (70%) of the cytoskeletal protein desmin. Significant correlations were observed between the right atrial major axis (RA(major)) and beta-MHC expression as well as the desmin/actin ratio. Our findings indicate that dilatation may influence cardiomyocyte stability through altered desmin expression, but that it does not predispose to the alterations in contractile function observed in AF.


Subject(s)
Atrial Fibrillation/metabolism , Gene Expression Regulation , Heart Atria/pathology , Myocardial Contraction , Aged , Biopsy , Calcium/metabolism , Densitometry , Echocardiography , Electrophoresis, Gel, Two-Dimensional , Electrophoresis, Polyacrylamide Gel , Female , Humans , Male , Middle Aged , Myocytes, Cardiac/metabolism , Phosphorylation , Protein Isoforms , Troponin T/metabolism
13.
J Muscle Res Cell Motil ; 26(1): 39-48, 2005.
Article in English | MEDLINE | ID: mdl-16088376

ABSTRACT

Changes in myosin heavy chain (MHC) isoform expression and protein composition occur during cardiac disease and it has been suggested that even a minor shift in MHC composition may exert a considerable effect on myocardial energetics and performance. Here an overview is provided of the cellular basis of the energy utilisation in cardiac tissue and novel data are presented concerning the economy of myocardial contraction in diseased atrial and ventricular human myocardium. ATP utilisation and force development were measured at various Ca(2+) concentrations during isometric contraction in chemically skinned atrial trabeculae from patients in sinus rhythm (SR) or with chronic atrial fibrillation (AF) and in ventricular muscle strips from non-failing donor or end-stage failing hearts. Contractile protein composition was analysed by one-dimensional gel electrophoresis. Atrial fibrillation was accompanied by a significant shift from the fast alpha-MHC isoform to the slow beta-MHC isoform, whereas both donor and failing ventricular tissue contained almost exclusively the beta-MHC isoform. Simultaneous measurements of force and ATP utilisation indicated that economy of contraction is preserved in atrial fibrillation and in end-stage human heart failure.


Subject(s)
Arrhythmia, Sinus/physiopathology , Atrial Fibrillation/physiopathology , Heart/physiopathology , Myocardial Contraction , Myocardium/metabolism , Myosin Heavy Chains/metabolism , Adenosine Triphosphate/metabolism , Biopsy , Chronic Disease , Electrophoresis, Polyacrylamide Gel , Female , Humans , Male , Myocardial Contraction/physiology , Myocardium/chemistry , Myosin Heavy Chains/analysis , Myosin Heavy Chains/genetics , Protein Isoforms/analysis , Protein Isoforms/genetics , Protein Isoforms/metabolism
14.
Health Care Manage Rev ; 16(1): 41-56, 1991.
Article in English | MEDLINE | ID: mdl-2004910

ABSTRACT

Research on organizational control and multihospital systems has focused on operational and performance characteristics. Little attention has been directed to the role of marketing as an operational strategy. This article examines the practice of marketing across interorganizational types and develops comparative profiles.


Subject(s)
Hospitals, Voluntary/organization & administration , Marketing of Health Services/organization & administration , Multi-Institutional Systems/organization & administration , Attitude to Health , Hospitals, Proprietary/organization & administration , United States
15.
J Physiol ; 482 ( Pt 1): 109-22, 1995 Jan 01.
Article in English | MEDLINE | ID: mdl-7730976

ABSTRACT

1. A method has been developed to discriminate between the rate of ATP hydrolysis associated with calcium uptake into the sarcoplasmic reticulum (SR) and force development of the contractile apparatus in mechanically or saponin-skinned skeletal muscle fibres. The rate of ATP hydrolysis was determined in fibres of different types from the iliofibularis muscle of Xenopus laevis by enzymatic coupling of ATP re-synthesis to the oxidation of NADH. 2. The ATPase activity was determined before and after exposure of the preparations for 30 min to a solution containing 0.5% Triton X-100, which effectively abolishes the SR ATPase activity. The fibres were activated in a solution containing 5 mM caffeine to ensure that calcium uptake into the SR was maximal. 3. At saturating Ca2+ concentrations the actomyosin (AM) and SR ATPase activities in fast-twitch fibres, at 4.3 degrees C, amounted to 1.52 +/- 0.07 and 0.58 +/- 0.10 mumol s-1 (g dry wt)-1, respectively (means +/- S.E.M.; n = 25). The SR ATPase activity was 25% of the total ATPase activity. At submaximal calcium concentrations the AM ATPase activity varied in proportion to the isometric force. 4. The calcium sensitivity of the SR ATPase was larger than that of the AM ATPase and its dependence on [Ca2+] was less steep. The AM ATPase activity was half-maximal at a pCa of 6.11 (pCa = -log [Ca2+]) whereas the SR ATPase activity was half-maximal at a pCa of 6.62. 5. In Triton X-100-treated fibres, at different 2,3-butanedione monoxime (BDM) concentrations, the AM ATPase activity and isometric force varied proportionally. The SR ATPase activity determined by extrapolation of the total ATPase activity in mechanically skinned or saponin-treated fibres to zero force, was independent of the BDM concentration in the range studied (0-20 mM). The values obtained for the SR ATPase activity in this way were similar to those obtained with Triton X-100 treatment. 6. The AM ATPase activity in slow-twitch fibres amounted to 0.74 +/- 0.13 mumol s-1 (g dry wt)-1, i.e. about a factor of two smaller than in fast-twitch fibres. The SR ATPase activity amounted to 0.47 +/- 0.07 mumol s-1 (g dry wt)-1, i.e. rather similar to the value in fast-twitch fibres. The proportion of the total ATPase activity that was due to SR ATPase (40%) was larger than in fast-twitch fibres. 7. The temperature dependence of the AM and SR ATPase activities in fast-twitch fibres differed. In the temperature range 5-10 degrees C, the relative changes in AM and SR ATPase activities for a 10 degrees C temperature change (Q10) were 3.9 +/- 0.3 and 7.2 +/- 1.5, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)


Subject(s)
Adenosine Triphosphate/metabolism , Calcium/metabolism , Muscle Contraction/physiology , Muscle Fibers, Skeletal/metabolism , Sarcoplasmic Reticulum/metabolism , Actomyosin/metabolism , Adenosine Triphosphatases/drug effects , Adenosine Triphosphatases/metabolism , Animals , Diacetyl/analogs & derivatives , Diacetyl/pharmacology , Female , Hydrolysis , In Vitro Techniques , Muscle Contraction/drug effects , Octoxynol/pharmacology , Sarcoplasmic Reticulum/drug effects , Temperature , Xenopus laevis
16.
J Physiol ; 518 ( Pt 3): 735-44, 1999 Aug 01.
Article in English | MEDLINE | ID: mdl-10420010

ABSTRACT

1. The influence of 30 mM inorganic phosphate (Pi) and pH (6.2-7.4) on the rate of ATP utilization was determined in mechanically skinned bundles of myofibrils from the iliofibularis muscle of Xenopus laevis at approximately 5 C. 2. BDM (2,3-butanedione monoxime; 10 mM) depressed isometric force production and actomyosin (AM) ATPase activity equally. Therefore sarcoplasmic reticular (SR) ATPase activity could be determined by extrapolation of the total ATPase activity to zero force. 3. The SR ATPase activity without added Pi at pH 7.1 was 42 +/- 2 % of the total ATPase activity. Addition of 30 mM Pi reduced SR ATPase activity slightly, by 9 +/- 5 %, and depressed force by 62 +/- 2 % and AM ATPase activity by 21 +/- 6 %. 4. At pH 6.2, force, SR ATPase activity and AM ATPase activity were reduced by 21 +/- 5, 61 +/- 5 and 10 +/- 4 % of their respective values at pH 7.1. 5. The SR ATPase activity at 30 mM Pi and pH 6.2 was reduced markedly to 20 +/- 6 % of the value under control conditions, suggesting that the maximum rate of Ca2+ uptake during muscle fatigue was strongly depressed. This reduction was larger than expected on the basis of the effects of Pi and pH alone.


Subject(s)
Adenosine Triphosphatases/metabolism , Muscle Fibers, Skeletal/enzymology , Phosphates/pharmacology , Sarcoplasmic Reticulum/enzymology , Adenosine Triphosphatases/antagonists & inhibitors , Animals , Diacetyl/analogs & derivatives , Diacetyl/pharmacology , Enzyme Inhibitors/pharmacology , Female , Hydrogen-Ion Concentration , Isometric Contraction/drug effects , Kinetics , Muscle Fibers, Skeletal/drug effects , Muscle Fibers, Skeletal/ultrastructure , Myofibrils/drug effects , Myofibrils/enzymology , Sarcoplasmic Reticulum/drug effects , Sarcoplasmic Reticulum/metabolism , Xenopus laevis
17.
J Muscle Res Cell Motil ; 19(6): 675-87, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9742451

ABSTRACT

Isometric ATP consumption and force were investigated in mechanically skinned fibres from iliofibularis muscle of Xenopus laevis. Measurements were performed at different [Ca2+], in the presence and absence of caffeine (5 nM). In weakly Ca2+-buffered solutions without caffeine, spontaneous oscillations in force and ATPase activity occurred. The repetition frequency was [Ca2+]-and temperature-dependent. The Ca2+ threshold (+/- SEM) for the oscillations corresponded to a pCa of 6.5 +/- 0.1. The maximum ATP consumption associated with calcium uptake by the sarcoplasmic reticulum (SR) reached during the oscillations was similar to the activity under steady-state conditions at saturating calcium concentrations in the presence of caffeine. Maximum activity was reached when the force relaxation was almost complete. The calculated amount of Ca2+ taken up by the SR during a complete cycle corresponded to 5.4 +/ 0.4 mmol per litre cell volume. In strongly Ca2+-buffered solutions, caffeine enhanced the calcium sensitivity of the contractile apparatus and, at low calcium concentrations, SR Ca uptake. These results suggest that when the SR is heavily loaded by net Ca uptake, there is a massive calcium-induced calcium release. Subsequent net Ca uptake by the SR then gives rise to the periodic nature of the calcium transient.


Subject(s)
Calcium/metabolism , Muscle Contraction , Muscle Fibers, Skeletal/physiology , Muscle, Skeletal/physiology , Sarcoplasmic Reticulum/metabolism , Adenosine Triphosphatases/metabolism , Animals , Caffeine/pharmacology , Calcium/physiology , Calcium Signaling/physiology , Female , Muscle Contraction/drug effects , Muscle Fibers, Skeletal/enzymology , Muscle, Skeletal/enzymology , Sarcomeres/physiology , Sarcoplasmic Reticulum/enzymology , Sarcoplasmic Reticulum/physiology , Temperature , Xenopus laevis
18.
J Health Care Mark ; 12(2): 8-21, 1992 Jun.
Article in English | MEDLINE | ID: mdl-10119216

ABSTRACT

Multihospital systems are an important and growing component in the health care delivery system in the United States. Because formalized marketing is relatively new in multihospital systems, the potential to increase the marketing productivity of member hospitals is great. The more is known about how these systems function, the more effective will be the public and private decision making involving these systems. To that end, the authors position marketing in multihospital systems as an innovative technology and examine comparative profiles of innovative and noninnovative multihospital systems. More innovative systems, scoring higher on the marketing innovation attribute index, are characterized by greater information systems and communication support, as well as a stronger commitment to the marketing function. Strategic implications and future research directions are explored.


Subject(s)
Marketing of Health Services/statistics & numerical data , Multi-Institutional Systems/organization & administration , Organizational Innovation , Analysis of Variance , Chi-Square Distribution , Decision Making, Organizational , Evaluation Studies as Topic , Health Services Research , Marketing of Health Services/organization & administration , Multi-Institutional Systems/statistics & numerical data , Ownership/statistics & numerical data , Surveys and Questionnaires , United States
19.
Pflugers Arch ; 443(1): 102-11, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11692273

ABSTRACT

The dependency of ATP utilization and isometric force on [MgATP] was studied in skinned rat trabeculae under normal (pH 7.0) and simulated ischaemic (pH 6.2, 30 mM added Pi) conditions at 20+/-1 degrees C. At saturating [Ca2+], mean (+/-SEM) ATP utilization at 5 mM MgATP (A0) was 0.48+/-0.03 mM/s and force (F0) was 37+/-2 kN/m2. At 10 microM MgATP under normal conditions ATP utilization decreased gradually to 66+/-3% of A0, and force increased to 169+/-7% of F0. Under ischaemic conditions at 10 microM MgATP, ATP utilization decreased from 30+/-5% to 11+/-2% of A0 whereas force increased eightfold from 12+/-4% to 97+/-7% of F0. The [MgATP] at half-maximal ATP utilization (Km) under ischaemic conditions was 21+/-3 microM. At pH 7.0, Km was estimated to be less than 10 microM. These results show that tension cost decreases markedly with decreasing MgATP. Under ischaemic conditions parallel changes in Ca2+ sensitivity of force and ATP utilization were observed, corresponding to 1.3 pCa units. Reducing [MgATP] from 0.5 to 0.05 mM caused a modest reversal of this change in Ca2+ sensitivity. These changes in Ca2+ sensitivity are consistent with a marked reduction in active force and force-related ATP utilization during ischaemia but are insufficient to explain the ischaemic contracture on the basis of active force development.


Subject(s)
Adenosine Triphosphate/metabolism , Adenosine Triphosphate/pharmacology , Myocardial Ischemia/metabolism , Adenosine Diphosphate/metabolism , Adenosine Triphosphatases/metabolism , Animals , Calcium/metabolism , Hydrogen-Ion Concentration , Kinetics , Male , Myocardial Contraction/drug effects , NAD/analysis , Rats
20.
J Physiol ; 531(Pt 2): 393-403, 2001 Mar 01.
Article in English | MEDLINE | ID: mdl-11230512

ABSTRACT

The contractile properties and ATPase activity of skinned human skeletal muscle fibres from vastus lateralis were examined. Fibre types were resolved from single fibre segments by SDS-polyacrylamide gel electrophoresis. ATPase activity was determined by enzymatic coupling of ATP resynthesis to the oxidation of NADH. The partitioning of ATPase activity into (a) calcium-activated activity due to actomyosin (AM) interaction, (b) calcium-activated activity of the sarcoplasmic reticular (SR) calcium pump, and (c) basal (calcium independent) activity was investigated by comparing ATP utilization before and after exposure of the preparations for 30 min to a solution containing 0.5 % Triton X-100, which effectively abolished the SR ATPase activity. Partitioning of ATPase activity was also determined by measuring ATP utilization and force at different concentrations of butanedione monoxime (BDM), which inhibits AM interaction. The results obtained with Triton X-100 and BDM were similar. At saturating Ca2+ concentrations and 20 degrees C, the AM, SR and basal ATPase activities per litre cell volume (+/- S.E.M.) amounted to 46 +/- 4, 51 +/- 4 and 19 +/- 2 muM s-1 in type I fibres (n = 21), 139 +/- 14, 69 +/- 8 and 30 +/- 3 muM s-1 in type IIA fibres (n = 25), 137 +/- 22, 175 +/- 28 and 26 +/- 8 muM s-1 in type IIA/B fibres (n = 4) and 108 +/- 13, 169 +/- 42 and 32 +/- 8 muM s-1 in type IIB fibres (n = 2). These results indicate that ATP utilization for SR Ca2+ pumping in fast fibres is considerably larger than in slow fibres. The SR ATPase activity in human muscle represents a considerable fraction of the total (AM + SR + basal) ATPase activity.


Subject(s)
Adenosine Triphosphate/metabolism , Calcium/metabolism , Diacetyl/analogs & derivatives , Muscle, Skeletal/physiology , Adenosine Triphosphatases/metabolism , Adult , Dactinomycin/pharmacology , Diacetyl/pharmacology , Humans , Male , Middle Aged , Muscle Contraction/physiology , Muscle Fibers, Skeletal/drug effects , Muscle Fibers, Skeletal/physiology , Muscle, Skeletal/drug effects , Myosins/metabolism , Octoxynol/pharmacology , Osmolar Concentration , Sarcoplasmic Reticulum/enzymology
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