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At least 1,801 records · Page 100Linked to original sources
PubMed1988

Maximal twitch tension in intact length-clamped ferret papillary muscles evoked by modified postextrasystolic potentiation.

A modified test of postextrasystolic potentiation achieved with a brief episode of rapid pacing followed by a 6-second pause (RPP maneuver) was used to evoke maximal force in isolated intact ferret right ventricular papillary muscles. Maximal RPP tensions were examined under length-clamped conditions and compared with the steady-state forces obtained when further increases in [Ca2+]o, did not further increase force and to the tensions recorded at the point of saturation of force when similarly length-clamped muscles were subjected to caffeine-induced tetanization. The results show that the calculated maximal twitch tension achieved with RPP is comparable to the 25-35 g/mm2 observed in intact single skeletal muscle fibers. The study also shows that the beat-to-beat decay of the potentiated contraction is exponential. While the amount of the constant fractional beat-to-beat decay is a function of [Ca2+]o, it is not influenced by length. During the decay of potentiation, the ratio of the potentiation of any beat divided by that of the previous beat is a constant, called (X). With certain assumptions, it is shown that (X) is a measure of the fraction of activator calcium taken up by the sarcoplasmic reticulum in each beat and, in the steady state, the fraction of activator calcium that comes from the sarcoplasmic reticulum. The (X) amounted to 33%, 50%, and 65% when [Ca2+]o was 1.25, 2.50, and 5.0 mM, respectively. Thus, at 1.25 mM [Ca2+]o, some two thirds of the total calcium required to activate the myofilaments comes from the extracellular compartment during excitation and only one third is contributed via release from the sarcoplasmic reticulum. In the region of optimal myofilament overlap, RPP force-length curves are remarkably shallow and almost indistinguishable from the sarcomere length-tension relation observed in skinned single cardiac cells. Tetanus plateau tensions are significantly smaller than RPP forces at any length, and the slope of the tetanus force-length curves is greater than that obtained with RPP. Thus, and by exclusion, we also suggest that caffeine may exert significant downstream inhibitory effects.

Algorithms↗
PubMed1992

Swelling-induced chloride-sensitive current in canine atrial cells revealed by whole-cell patch-clamp method.

An isoproterenol-induced chloride current has been detected in ventricular myocytes from guinea pig and rabbit but has not been found in canine ventricular cells. This investigation was undertaken to determine whether canine atrial cells possessed such a current. Steady-state currents were examined with potassium currents blocked by cesium. In whole-cell patch-clamp experiments, an isoproterenol-induced chloride current could not be detected shortly after patch rupture. However, whole-cell current in the absence of isoproterenol increased over time after patch rupture. The spontaneously activating steady-state current was outwardly rectifying with a reversal potential of approximately -25 mV. The current that developed over time was sensitive to variation in extracellular chloride concentration and was partially blocked by anthracene-9-carboxylic acid. Isoproterenol could enhance the amplitude of this current once it developed. Although isosmotic pipette filling and extracellular solutions were used, cell swelling was found to be the cause of the increase in whole-cell conductance that was observed during whole-cell patch-clamp experiments. The development of the current and the associated cell swelling could be prevented with the addition of 50-75 mM mannitol to the extracellular solution. The current could be observed in perforated patch recordings with nystatin when extracellular osmolarity was low (221 mosm/kg) but not when the extracellular solution was isosmotic (293 mosm/kg). Cardiac chloride currents have the potential to depolarize the resting membrane potential and cause abnormal automaticity. Chloride currents can also decrease the refractory period through a reduction in action potential duration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Measurement of Na(+)-K+ pump current in isolated rabbit ventricular myocytes using the whole-cell voltage-clamp technique. Inhibition of the pump by oxidant stress.

Free radical-induced oxidant stress has been implicated in ischemia and reperfusion-induced injury in the heart. A number of studies have reported that oxidant stress reduces the activity of isolated Na+,K(+)-ATPase enzyme. We have studied the effects of oxidant stress on the Na(+)-K+ pump current recorded in isolated rabbit ventricular myocytes using the whole-cell voltage-clamp technique. Singlet oxygen and superoxide were generated by the photoactivation of rose bengal (50 nM). The compositions of Tyrode's and pipette solutions were designed to block channel currents and electrogenic Na(+)-Ca2+ exchange. Cells were dialyzed with a pipette solution containing 30 mM sodium via wide-tipped (1-2-M omega) electrodes, and outward Na(+)-K+ pump current was recorded during a voltage-ramp protocol. The validity of using such a ramp protocol was confirmed by comparison with steady-state Na(+)-K+ pump current measurements made at the end of 200-msec square-clamp steps. Active currents were abolished by potassium-free Tyrode's solution or ouabain (100 microM), and Na(+)-K+ pump current was defined as the Ko-sensitive fraction of recorded currents. The activation of Na(+)-K+ pump current by intracellular sodium and extracellular potassium revealed a concentration of potassium necessary for half-maximal activation of 18.7 mM for Nai and 1.88 mM for Ko. Oxidant stress inhibited Na(+)-K+ pump current at all voltages, such that after a 10-minute exposure to photoactivated rose bengal, Na(+)-K+ pump current measured at 0 mV was reduced by approximately 50%. The voltage dependence of Na(+)-K+ pump current was, however, not profoundly affected by oxidant stress. Passive membrane currents recorded in the absence of all major electrogenic ion channels, exchangers, or pumps were unaffected by oxidant stress. This observation suggests that, over the time course during which Na(+)-K+ pump inhibition and calcium overload occur, oxidant stress does not cause nonspecific membrane damage and changes in the passive resistance of the lipid bilayer. The inhibition of Na(+)-K+ pump activity by oxidant stress may contribute to ischemia/reperfusion injury and reperfusion-induced cellular calcium overload.

Animals↗
PubMed1995

Effects of action potential duration on excitation-contraction coupling in rat ventricular myocytes. Action potential voltage-clamp measurements.

Although each of the fundamental processes involved in excitation-contraction coupling in mammalian heart has been identified, many quantitative details remain unclear. The initial goal of our experiments was to measure both the transmembrane Ca2+ current, which triggers contraction, and the Ca2+ extrusion due to Na(+)-Ca2+ exchange in a single ventricular myocyte. An action potential waveform was used as the command for the voltage-clamp circuit, and the membrane potential, membrane current, [Ca2+]i, and contraction (unloaded cell shortening) were monitored simultaneously. Ca(2+)-dependent membrane current during an action potential consists of two components: (1) Ca2+ influx through L-type Ca2+ channels (ICa-L) during the plateau of the action potential and (2) a slow inward tail current that develops during repolarization negative to approximately -25 mV and continues during diastole. This slow inward tail current can be abolished completely by replacement of extracellular Na+ with Li+, suggesting that it is due to electrogenic Na(+)-Ca2+ exchange. In agreement with this, the net charge movement corresponding to the inward component of the Ca(2+)-dependent current (ICa-L) was approximately twice that during the slow inward tail current, a finding that is predicted by a scheme in which the Ca2+ that enters during ICa is extruded during diastole by a 3 Na(+)-1 Ca2+ electrogenic exchanger. Action potential duration is known to be a significant inotropic variable, but the quantitative relation between changes in Ca2+ current, action potential duration, and developed tension has not been described in a single myocyte. We used the action potential voltage-clamp technique on ventricular myocytes loaded with indo 1 or rhod 2, both Ca2+ indicators, to study the relation between action potential duration, ICa-L, and cell shortening (inotropic effect). A rapid change from a "short" to a "long" action potential command waveform resulted in an immediate decrease in peak ICa-L and a marked slowing of its decline (inactivation). Prolongation of the action potential also resulted in slowly developing increases in the magnitude of Ca2+ transients (145 +/- 2%) and unloaded cell shortening (4.0 +/- 0.4 to 7.6 +/- 0.4 microns). The time-dependent nature of these effects suggests that a change in Ca2+ content (loading) of the sarcoplasmic reticulum is responsible. Measurement of [Ca2+]i by use of rhod 2 showed that changes in the rate of rise of the [Ca2+]i transient (which in rat ventricle is due to the rate of Ca2+ release from the sarcoplasmic reticulum) were closely correlated with changes in the magnitude and the time course of ICa-L.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1999

Ca(2+) influx through Ca(2+) channels in rabbit ventricular myocytes during action potential clamp: influence of temperature.

Ca(2+) influx via Ca(2+) current (I(Ca)) during the action potential (AP) was determined at 25 degrees C and 35 degrees C in isolated rabbit ventricular myocytes using AP clamp. Contaminating currents through Na(+) and K(+) channels were eliminated by using Na(+)- and K(+)-free solutions, respectively. DIDS (0.2 mmol/L) was used to block Ca(2+)-activated chloride current (I(Cl(Ca))). When the sarcoplasmic reticulum (SR) was depleted of Ca(2+) by preexposure to 10 mmol/L caffeine, total Ca(2+) entry via I(Ca) during the AP was approximately 12 micromol/L cytosol (at both 25 degrees C and 35 degrees C). Similar Ca(2+) influx at 35 degrees C and 25 degrees C resulted from a combination of higher and faster peak I(Ca), offset by more rapid I(Ca) inactivation at 35 degrees C. During repeated AP clamps, the SR gradually fills with Ca(2+), and consequent SR Ca(2+) release accelerates I(Ca) inactivation during the AP. During APs and contractions in steady state, total Ca(2+) influx via I(Ca) was reduced by approximately 50% but was again unaltered by temperature (5.6+/-0.2 micromol/L cytosol at 25 degrees C, 6.0+/-0.2 micromol/L cytosol at 35 degrees C). Thus, SR Ca(2+) release is responsible for sufficient I(Ca) inactivation to cut total Ca(2+) influx in half. However, because of the kinetic differences in I(Ca), the amount of Ca(2+) influx during the first 10 ms, which presumably triggers SR Ca(2+) release, is much greater at 35 degrees C. I(Ca) during a first pulse, given just after the SR was emptied with caffeine, was subtracted from I(Ca) during each of 9 subsequent pulses, which loaded the SR. These difference currents reflect I(Ca) inactivation due to SR Ca(2+) release and thus indicate the time course of local [Ca(2+)] in the subsarcolemmal space near Ca(2+) channels produced by SR Ca(2+) release (eg, maximal at 20 ms after the AP activation at 35 degrees C). Furthermore, the rate of change of this difference current may reflect the rate of SR Ca(2+) release as sensed by L-type Ca(2+) channels. These results suggest that peak SR Ca(2+) release occurs within 2.5 or 5 ms of AP upstroke at 35 degrees C and 25 degrees C, respectively. I(Cl(Ca)) might also indicate local [Ca(2+)], and at 35 degrees C in the absence of DIDS (when I(Cl(Ca)) is prominent), peak I(Cl(Ca)) also occurred at a time comparable to the peak I(Ca) difference current. We conclude that SR Ca(2+) release decreases the Ca(2+) influx during the AP by approximately 50% (at both 25 degrees C and 35 degrees C) and that changes in I(Ca) (and I(Cl(Ca))), which depend on SR Ca(2+) release, provide information about local subsarcolemmal [Ca(2+)].

Action Potentials↗
PubMed1991

In vivo stimulation of the insulin receptor kinase in human skeletal muscle. Correlation with insulin-stimulated glucose disposal during euglycemic clamp studies.

To assess the relationship between insulin receptor (IR) kinase activity and insulin action in vivo in humans, we measured glucose disposal rates (GDR) during a series of euglycemic clamp studies. Simultaneously, we measured IR kinase activity in IRs extracted from skeletal muscle obtained by needle biopsy at the end of each clamp. By preserving the phosphorylation state of the receptors as it existed in vivo at the time of biopsy, we could correlate GDR and IR kinase in skeletal muscle. Eight nondiabetic, nonobese male subjects underwent studies at insulin infusion rates of 0, 40, 120, and 1,200 mU/m2 per min. Kinase activity, determined with receptors immobilized on insulin agarose beads, was measured at 0.5 microM ATP, with 1 mg/ml histone, followed by SDS-PAGE. Insulin increased GDR approximately sevenfold with a half-maximal effect at approximately 100 microU/ml insulin and a maximal effect by approximately 400 microU/ml. Insulin also increased IR kinase activity; the half-maximal effect occurred at approximately 500-600 microU/ml insulin with a maximal 10-fold stimulation over basal. Within the physiologic range of insulin concentrations, GDR increased linearly with kinase activation (P less than 0.0006); at supraphysiologic insulin levels, this relationship became curvilinear. Half-maximal and maximal insulin-stimulated GDR occurred at approximately 20 and approximately 50% maximal kinase activation, respectively. These results are consistent with a role of the kinase in insulin action in vivo. Furthermore, they demonstrate the presence of a large amount of "spare kinase" for glucose disposal.

Adenosine Triphosphate↗
PubMed1984

Circumcision using the Mogen clamp.

The purpose of this study was to analyze the results of 313 circumcisions using the Mogen clamp. This procedure was done between 1 day and 2 years of age in all but four patients. The complication rate was low (1.6%). Two patients had local infection, one mild hemorrhage, one concealed penis, and one postcircumcision phimosis. Circumcision using the Mogen clamp is a simple, quick, and safe procedure.

Circumcision, Male↗
PubMed2001

Results of group-circumcision of Muslim boys in Malaysia with a new type of disposable clamp.

This study evaluates the safety and results of surgery usingTaraKlamp Circumcision Device during a group circumcision. Atotal of 64 circumcisions of Muslim boys were performed by Medical Assistants supervised by Medical Doctors in a hall in Kuala Lumpur, Malaysia. A new type disposable clamp was used, which was removed 4 days after the operation. No major complications occurred and the boys experienced in general mild pain postoperatively. Mostly good cosmetic results were obtained and 90% of the parents would recommend this new clamp to others. Group circumcisions withTaraKlamp Circumcision Device (Kuala Lumpur, Malaysia) are safe, although proper patient selection and adequate training in using the device are mandatory.

Child↗
PubMed1999

Rubber ring clamping of the umbilical cord: a randomized trial.

A randomized trial to compare two methods of umbilical cord tying in neonates, immediately after birth, was undertaken from February to April 1997 in the Department of Obstetrics & Gynaecology, Zewditu Memorial Hospital, Addis Ababa, Ethiopia. In less than 3 months, we investigated 300 neonates, of whom 150 infants were randomly assigned to the traditional ligation of the umbilical cord (using a piece of thread) and the rest to a rubber ring clamping method. Among the former group, 13.3% (20/150) of the neonates bled from their umbilical cords which necessitated re-tying, whereas in the later group, there was no sign of haemorrhage or infection within 12 h of clamping. We suggest that the rubber ring method described is a superior procedure and can easily replace the traditional, cumbersome and time-consuming umbilical cord ligation.

Ethiopia↗
PubMedDate not supplied

Hormonal and metabolic responses to glucose infusion in sepsis studied by the hyperglycemic glucose clamp technique.

Although nutritional support is vital to treatment of severe sepsis, the septic patient does not respond normally to glucose infusion. We have used the hyperglycemic glucose clamp technique to investigate the initial hormonal and metabolic responses of the septic patient to glucose under controlled conditions. The plasma glucose concentration was raised to and maintained at 12 mmol/liter for 2 hr in 12 septic patients and 11 normal controls. Glucose utilization, assessed from the amount infused, was significantly depressed in the patients, despite similar plasma insulin concentrations in the two groups. Forearm glucose uptake was similarly impaired. Despite very similar plasma free fatty acid concentrations in the two groups, which were suppressed equally by the glucose infusion, whole-body fat oxidation was elevated in the patients compared with the controls, and suppressed to a lesser extent in response to glucose. Glycerol and ketone body concentrations were elevated in the patients in keeping with a picture of accelerated release, clearance, and oxidation of fatty acids. Plasma cortisol, epinephrine, and norepinephrine concentrations were elevated in the septic patients in a severity-related manner, but not to high levels compared with experimental work. Norepinephrine showed no response to the glucose infusion in either group. Plasma glucagon concentrations were not significantly elevated in the septic patients. We conclude that the hyperglycemic glucose clamp provides a useful model for studying glucose intolerance in sepsis. Impaired glucose utilization in septic patients is associated with increased fat oxidation, although the hormonal basis for these changes is still unclear.

Adult↗
PubMed1978

Some cardio-pulmonary effects of infra-renal clamping of the abdominal aorta.

No significant changes were found in heart rate, blood pressure, cardiac output, arterial blood gases or physiological deadspace: tidal volume ratio before and after clamping and unclamping the abdominal aorta below the renal vessels. Nevertheless, drugs should be available to reduct the afterload on the heart if any evidence of myocardial ischaemia appears during the period of aortic clamping. The importance of maintaining an adequate circulating blood volume at all times is stressed.

Adult↗
PubMed2006

Sodium pump reduction correlates with aortic clamp time in pediatric heart surgery.

Myocardial depression after cardiac surgery is modulated by cardiopulmonary bypass (CPB) and the underlying heart disease. The sodium pump is a key component for myocardial function. We hypothesized that the change in sodium pump expression during CPB correlates with intraoperative and postoperative laboratory and clinical parameters in neonates and children with various congenital heart defects. Sodium pump isoforms alpha1 (ATP1A1) and alpha3 (ATP1A3) mRNA expression in right atrial myocardium, excised before and after CPB, was quantified. Groups were assigned according to presence (VO group, n = 8) or absence (NO group, n = 8) of right atrial volume overload. CPB and aortic clamp time correlated with postoperative troponin-I values and ICU stay. ATP1A1 (P = 0.008) and ATP1A3 (P = 0.038) mRNA expression were significantly reduced during CPB. Longer aortic clamp times were associated with lower postoperative ATP1A1 (P = 0.045) and ATP1A3 (P = 0.002) mRNA expression. Low postoperative ATP1A1 (P = 0.043) and ATP1A3 (P = 0.002) expressions were associated with high troponin-I values. These results were restricted to the VO group. No correlation of sodium pump mRNA expression was found with the duration of ICU stay or ventilation. The postoperative troponin-I and clinical parameters correlated with the length of CPB, regardless of volume overload. In contrast, only dilated right atrium seemed to be susceptible to CPB in terms of sodium pump expression, showing a reduction during the operation and a correlation of sodium pump with postoperative troponin-I values.

Aorta↗
PubMed1995

Maximal expiratory flows generated by rapid chest compression following end-inspiratory occlusion or expiratory clamping in young children.

Partial forced expiratory flow-volume curves obtained by the rapid chest compression technique are being widely used to assess pulmonary function in infants and young children. The aim of this study is to assess whether in this age group flow limitation is achieved with the partial forced expiratory flow-volume curve with rapid chest compression. In eight infants and young children sedated with chloral hydrate, flow-volume curves were obtained by regular rapid chest compression technique, end-inspiratory airway occlusion prior to rapid chest compression, and expiratory clamping prior to rapid chest compression. In each technique, beginning with a cuff pressure of 20 cmH2O, the cuff pressure was increased by 10 cmH2O increments until the compression pressure reached 90 cmH2O. Maximal flow-volume curves were generated by each technique. End-inspiratory occlusion prior to rapid chest compression caused higher flows over the entire phase of expiration than the regular rapid chest compression. This increase could be observed over the entire phase of expiration. Forced expiratory flow at 50% and at 75% of vital capacity (V50 and V75) with regular rapid chest compression were 207 +/- 44 ml.s-1 (mean +/- SD) and 138 +/- 59 ml.sec-1, respectively. When end-inspiratory occlusion preceded rapid chest compression, V50 and V75 increased to 283 +/- 114 and 206 +/- 61 ml.sec-1 respectively, with a mean increase in V50 of 34% and in V75 of 31%. When expiratory clamping preceded the compression, even higher expiratory flows resulted.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1995

Replacement with recombinant human inhibin immediately after orchidectomy in the hypophysiotropically clamped male rhesus monkey (Macaca mulatta) maintains follicle-stimulating hormone (FSH) secretion and FSH beta messenger ribonucleic acid levels at precastration values.

This study directly tested the inhibin hypothesis by examining the ability of replacement with recombinant human (rh-) inhibin, either alone or in combination with testosterone (T), to maintain FSH secretion and FSH beta messenger RNA (mRNA) at intact levels after orchidectomy in the hypophysiotropically clamped juvenile rhesus monkey. Thirteen male monkeys (11-21 months of age) received an intermittent i.v. infusion of GnRH (0.1 microgram/min for 3 min every 3 h). After 4-6 weeks of GnRH stimulation, 10 animals were orchidectomized, and 3 monkeys were sham castrated. Hormone replacement was initiated at castration and maintained for 4 days. Three monkeys received a combination of inhibin and T replacement, 4 monkeys received replacement with inhibin alone, and 3 monkeys received T replacement alone. A continuous i.v. infusion of rh-inhibin (832 ng/h.kg) was used to replace the testicular protein, whereas SILASTIC capsules were implanted sc for T replacement. The FSH response to castration and hormone replacement was determined by measuring circulating concentrations of this gonadotropin before a GnRH pulse and for 3 h thereafter on the day before surgery and on days 2 and 4 postcastration. Circulating immunoactive inhibin was measured by a RIA that recognizes the free alpha-subunit of inhibin as well as inhibin dimers. At the end of the study, anterior pituitaries were collected for analysis of steady state levels of FSH beta, LH beta, and alpha-subunit mRNAs. Steroid replacement alone, which produced circulating T concentrations in the upper physiological range, failed to prevent the postcastration increases in circulating FSH concentrations and pituitary FSH beta mRNA levels. In contrast, when circulating immunoactive inhibin in T-replaced monkeys was maintained at precastration levels (approximately 2 ng/ml) by infusion of rh-inhibin, FSH secretion and synthesis were held at control values. When T was omitted from combined replacement, the FSH-suppressing action of the recombinant hormone was not compromised. These results demonstrate that rh-inhibin is biologically active in the monkey, and the action of inhibin to suppress FSH synthesis and secretion does not require a concomitant action of T. Moreover, because the hypophysiotropic drive to the pituitary-testicular axis was clamped, the FSH-suppressing action of rh-inhibin must be at the pituitary.

Analysis of Variance↗
PubMed1984

Posterior stabilization with an interlaminar clamp in cervical injuries: technical note and review of the long term experience with the method.

An alternative method of cervical fixation utilizing a stainless steel clamp is described. The clamp is applied to the adjoining laminae of involved vertebrae in those cervical dislocations and subluxations with posterior instability. The long term results of this method have been most satisfactory, as indicated by our follow-up of 51 patients treated during the last decade.

Cervical Vertebrae↗
PubMed2004

Identification of single base-pair mutation on uidA gene of Escherichia coli O157:H7 by Peptide Nucleic Acids (PNA) mediated PCR clamping.

Peptide Nucleic Acids (PNA) is a new type of DNA analogue with a peptide backbone. We developed a rapid identification system of Escherichia. coli O157:H7 using PNA mediated PCR clamping. Firstly, we confirmed a single nucleotide alteration in the uidA gene (T93G), which is specific to E. coli O157: H7. We designed forward mutant DNA primer, wild type PNA, and a reverse DNA primer corresponding to the uidA sequence. PCR cycle consisted of four steps including dual annealing temperatures, 57 degrees C and 45 degrees C. Among 20 E. coli strains with various serotypes and 4 neighboring strains, the amplified bands (517 bp) were detected only in E. coli O157:H7 strains. PNA has specifically inhibited the PCR amplification from a wild type uidA gene. We successfully developed a multiplex PCR system, which detects both shigatoxin (stx) and uidA genes at once, to get reliable results by easier and rapid operation. We also analyzed kinetic parameters of PNA/DNA association using surface plasmon resonance and melting temperature using fluorescence resonance energy transfer (FRET). We discussed a selection mechanism of PCR clamping from these results.

Base Pair Mismatch↗
PubMed1992

[Spatial and quantitative analysis of the QRS and T waves by Frank-lead orthogonal electrocardiography in normal children. Comparative study in an early and late cord-clamping groups in newborns].

We studied a spatial and quantitative analysis of QRS and T waves by Frank-lead orthogonal electrocardiography (afterwards; ECG) in 50 cases of normal newborns, 30 cases of infants, 50 cases of adults, and also the variation in age was investigated. In the newborns, the comparative study was made serially, longitudinally in 21 infants with an early clamping of the cord and 29 infants with a late clamping of the cord. The results are mainly as follows. 1) The parameters reflecting the cardiac electromotive force of the right ventricle such as Sx, Qz and Sx+Qz decreased with aging. 2) Rx, i.e., the maximum leftward projection of QRS vector increased until the children, probably because the left ventricle was dominant in their growth and development and in the increased amount of work. A subsequent reduced value in the adults was considered to be mainly due to an increase of the distance between the heart and electrode by the increase in the thorax, particularly the transverse diameter and due to the growth in subcutaneous fat and muscle. 3) The values of Rx/Sx increased with aging. Rx and Sx in the adults were less than those in the children, but Rx/Sx was larger than that of Rx because Sx was less than Rx. 4) Age-related changes of Tz was most characteristic and was negative up to several days after birth. T vector was in forward direction and then turned positive (in backward). This was greatest at the period of the infants. Subsequently, it turned negative in the childhood, and extent was maximum in the adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

[A new test procedure to examine the stability of external fixation clamps--demonstrated with the Stuhler-Heise external fixation system (author's transl)].

Experimental investigation of stabilty for examination of the efficiency of external fixation clamps required different testing procedures and measuring arrangementsz which is due to variant assessment parameters and natures of load. Here is a description of a measuring equipment which could be applied for all important cases of load. In relation to the entire experimental arrangement it also enables the testing of all external fixation assemblies. Deviations of the poroximal fragment caused by loading, are considered as assessment parameters of the stability. This measuring set was practically applied on simulated defect fractures, stabilized by the Stuhler-Heise external fixation system. During a combined bending strain the stability degree of various two-dimensional as well as three-dimensional external fixation clamps for application on tibias was determined.

Bone Nails↗

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