Effect of continuous and interval exercise training on the PETCO2 response during a graded exercise test in patients with coronary artery disease

OBJECTIVE:

The purpose of this study was to evaluate the following: 1) the effects of continuous exercise training and interval exercise training on the end-tidal carbon dioxide pressure (PETCO₂) response during a graded exercise test in patients with coronary artery disease; and 2) the effects of exercise training modalities on the association between PETCO₂ at the ventilatory anaerobic threshold (VAT) and indicators of ventilatory efficiency and cardiorespiratory fitness in patients with coronary artery disease.

METHODS:

Thirty-seven patients (59.7±1.7 years) with coronary artery disease were randomly divided into two groups: continuous exercise training (n = 20) and interval exercise training (n = 17). All patients performed a graded exercise test with respiratory gas analysis before and after three months of the exercise training program to determine the VAT, respiratory compensation point (RCP) and peak oxygen consumption.

RESULTS:

After the interventions, both groups exhibited increased cardiorespiratory fitness. Indeed, the continuous exercise and interval exercise training groups demonstrated increases in both ventilatory efficiency and PETCO₂ values at VAT, RCP, and peak of exercise. Significant associations were observed in both groups: 1) continuous exercise training (PETCO₂VAT and cardiorespiratory fitness r = 0.49; PETCO₂VAT and ventilatory efficiency r = -0.80) and 2) interval exercise training (PETCO₂VAT and cardiorespiratory fitness r = 0.39; PETCO₂VAT and ventilatory efficiency r = -0.45).

CONCLUSIONS:

Both exercise training modalities showed similar increases in PETCO₂ levels during a graded exercise test in patients with coronary artery disease, which may be associated with an improvement in ventilatory efficiency and cardiorespiratory fitness.     

流行性腮腺炎病毒性脑膜炎短程高效治疗临床观察

目的：探讨流行性肋腺炎病毒性脑膜炎（肋脑）短程高效的治疗方法。方法：以临床和实验室确诊的155例肋脑患者为观察组，采用地塞米松一次性鞘内注射治疗方法，并与同期入院的常规对症治疗组对照。结果：观察组退热时间、头痛和脑膜刺激症状消失时间及治愈时间分别是32h、15h、12h、3．1d，明显优于对照组的58h、24h、32h、6.5d，且差异有非常显著性或差异有显著性（P＜0．01或0．05）。结论：地塞米松一次性鞘内注射疗法治疗肋脑短程、高效，安全。     

Comparison of two nucleic acid extraction and testing systems for HCMV-DNA detection and quantitation on whole blood specimens from transplant patients

Quantitative detection of human cytomegalovirus (HCMV) DNA on whole blood is currently the primary choice for virological monitoring in transplant patients and for determining the appropriate antiviral strategy, however specific issues of variability remain in terms of extraction methods, amplification efficiency, and variability. This study compared the performance characteristics of two nucleic acid extraction and testing systems for HCMV-DNA quantitation, the artus^® CMV QS-RGQ kit, associated with a fully automated DNA extraction and assay set up by Qiagen (system 1) and the Q-CMV Real Time Complete kit by Nanogen, associated with a semiautomated nucleic acid extraction system by Biomérieux (system 2) in 189 specimens from transplant patients and 10 from 2012 HCMV Quality Control for Molecular Diagnostics (QCMD). The two systems exhibited a 80.4% concordance. Differences between the two systems were within ±1 log₁₀ copies/ml of the averaged log₁₀ results for 88.9% of the tested specimens. For all qualitatively discordant specimens, mean viral load was ≤3 log₁₀ copies/ml. Considering viral load measurement, system 1 gave earlier positives that system 2, with a 14.8% of specimens resulted positive at low viral loads with system 1 and negative with system 2. In QCMD specimens, difference was below 0.7 log₁₀ copies/ml for both the systems.     

Modeling energy expenditure associated with isometric, concentric, and eccentric muscle action at the knee

This study was designed to derive and test a model of energy expenditure (dE/dt) during different modes of human muscle actionin vivo dE/dt for the quadriceps muscle was expressed as: dE_quad/dt=K1(ω)+K2(Tiso)+dW/dt, where K1 and K2 are constants, (ω) is joint angular velocity (^o/sec), (Tiso) represents the knee extension torque that could be developed by the active muscle if the muscle action were isometric (N-m), and (dW/dt) is the rate of work performed (W). Volunteers performed a series of repetitive 2- to 4-min knee extension exercises, while varying either the knee extension torque or velocity. The average joint torque, angular velocity, rate of work performed, and net energy expenditure (E) above resting and dE/dt were determined for each muscle action. The best fit values for K1 and K2 for concentric, eccentric, and isometric muscle actions were 0.044, −0.55, and 0 W/^c/sec, and 4.14, 5.28, and 2.17 W/N-m, respectively. The coefficients of determination (r ²) for the model predictions of dE_quad/dt for the three modes of muscle action were 0.78, 0.71, and 0.71, respectively. The correlation coefficient between predicted and experimental dE/dt for all modes of muscle action combined was 0.93. These findings indicate the model provides a useful tool for predicting the rate of energy expenditure associated with cyclic knee extension efforts.     

Mechanical and energy characteristics during shortening in isolated type-1 muscle fibres from Xenopus laevis studied at maximal and submaximal activation

 The mechanical and energy characteristics of isolated fast-twitch muscle fibres (type 1) of Xenopus laevis in isometric- and isovelocity contractions were measured at 20°C. The fibres were stimulated at either 60 Hz or 20 Hz to produce contractions at different levels of activation. The high stimulation frequency gave fused contractions, while at the low stimulation frequency tension fluctuated. When maximum isometric force had been reached, the fibres were shortened by 10% of the fibre length at different velocities. At 60 Hz stimulation during shortening the rate of heat production increased above the isometric rate of heat production. At 20 Hz stimulation during shortening, however, the rate of heat production was not different from the isometric rate of heat production. Mechanical efficiency was the same at the high and low level of activation. The actomyosin efficiency (i.e. the mechanical efficiency corrected for ”activation heat”) was highest at the low level of activation. We conclude that in fast-twitch muscle fibres from X. laevis, actomyosin efficiency is highest for partially activated muscle. From a comparison of the present results with those obtained from a study of slow-twitch muscle fibres presented earlier, it is concluded that fast-twitch muscle fibres are less efficient than slow-twitch muscle fibres. Received after revision: 13 May 1997 / Accepted: 1 July 1997     

Energy balance of human locomotion in water

In this paper a complete energy balance for water locomotion is attempted with the aim of comparing different modes of transport in the aquatic environment (swimming underwater with SCUBA diving equipment, swimming at the surface: leg kicking and front crawl, kayaking and rowing). On the basis of the values of metabolic power (Ė), of the power needed to overcome water resistance (_d) and of propelling efficiency (_P=_d/_tot, where _tot is the total mechanical power) as reported in the literature for each of these forms of locomotion, the energy cost per unit distance (C=Ė/v, where v is the velocity), the drag (performance) efficiency (_d=_d/Ė) and the overall efficiency (_o=_tot/Ė=_d/_P) were calculated. As previously found for human locomotion on land, for a given metabolic power (e.g. 0.5 kW=1.43 l·min^–1 O₂) the decrease in C (from 0.88 kJ·m^–1 in SCUBA diving to 0.22 kJ·m^–1 in rowing) is associated with an increase in the speed of locomotion (from 0.6 m·s^–1 in SCUBA diving to 2.4 m·s^–1 in rowing). At variance with locomotion on land, however, the decrease in C is associated with an increase, rather than a decrease, of the total mechanical work per unit distance (W_tot, kJ·m^–1). This is made possible by the increase of the overall efficiency of locomotion (_o=_tot/Ė=W_tot/C) from the slow speeds (and loads) of swimming to the high speeds (and loads) attainable with hulls and boats (from 0.10 in SCUBA diving to 0.29 in rowing).     

Adequacy and efficiency of nursing staff in a child-welfare-clinic at Umtata General Hospital, South Africa

Background

South Africa has a serious shortage of human and financial resources to provide primary healthcare services especially in the historically under-served areas. It is a tedious task to carry out healthcare delivery for the masses without rationalizing human resources in the form of re-allocation and re-deployment of healthcare personnel. This study aimed to establish the level of adequacy and efficiency of nursing staff in the former Transkei region. The study was carried out in the child and family welfare clinic of the Umtata General Hospital.

Objective

To assess adequacy and efficiency of nursing staff in a child welfare clinic.

Method

This was a retrospective study. The workload of two nurses allocated to the child welfare clinic at Umtata General Hospital South Africa was calculated based on the patient numbers and hours of work per week. Calculations excluded time breaks for tea, lunch and annual leave. This work load was compared to the norms of standard examination time that is 12 minutes per patient obtained from the sub directorate of Natalia Office of the Department of Health. Information regarding number of patients attended to by the nurses and their disease conditions was obtained from retrospective review of hospital records.

Results

While each nurse was on duty for 8 hours per day each had only 6 reproductive hours. The two nurses examined only 310 patients giving staff utilization of 2.46% (i.e. 310/12600) and adequacy of staff of 0.0492 or 310/6300.

Conclusion

There is under-utilization of the staff in Umtata General Hospital, South Africa.

Recommendation

To increase utilization of the nurses a process of sharing and merging with a clinic or a ward with similar type of work is recommended.     

Stability, Controllability, and Observability of the “Four State” Model for the Sarcomeric Control of Contraction

A model of the sarcomeric control of contraction at various loading conditions has to maintain three cardinal features: stability, controllability (where the output can be controlled by the input), and observability (where the output reflects the effects of all the state variables). The suggested model of the sarcomere couples calcium kinetics with cross-bridge (XB) cycling and comprises two feedback mechanisms: (i) the cooperativity, whereby the number of force-generating (strong) XBs determines calcium affinity, regulates XB recruitment, and (ii) the mechanical feedback, whereby shortening velocity determines XBs cycling rate, controls the XBs contractile efficiency. The sarcomere is described by a set of four first-order nonlinear differential equations, utilizing the Matlab's Simulink software. Small oscillatory input was imposed when the state variables trajectories reached a steady state. The linearized state-space representations of the model were calculated for various initial sarcomere lengths. The analysis of the state-space representation validates the controllability and observability of the model. The model has four poles: three at the left side of the complex plane and one integrating pole at the origin. Therefore, the system is marginally stable. The Laplace transform confirms that the state representation is minimal and is therefore observable and controllable. The extension of the model to a multi-sarcomere lattice was explored, and the effects of inhomogeneity and nonuniform activation were described.     

Occlusal traits in a group of school children in an isolated society in Jerusalem.

Abstract

The prevalence of occlusal features in 939 children, aged 6-13 years, belonging to an ultra-orthodox community of Jewish Ashkenazi descent living in Jerusalem was studied clinically. Sexual dimorphism was found for overjet, overbite, and habit practising. About one-quarter of the sample exhibited some degree of occlusal mutilation due to caries, thus creating a 'caries-affected' subgroup, the rest forming the 'caries-free' subgroup. In the latter set, normocclusion was scarce (7.4 per cent), Class I being the most frequent malocclusion (49.1 per cent). Caries had a significant effect on the symmetry of bilateral occlusal relationships, lower dental midline deviation, and on crowding/spacing conditions in the mixed dentition stage (except for the maxilla in late mixed dentition). The low prevalence of normocclusion can be attributed to genetic background, environmental influences and the definition attached to normal occlusion.     

Measuring the performance of patient-specific solutions for minimally invasive transforaminal lumbar interbody fusion surgery

Pre-surgical planning using 3D-printed BioModels enables the preparation of a “patient-specific” kit to assist instrumented spinal fusion surgery. This approach has the potential to decrease operating time while also offering logistical benefits and cost savings for healthcare. We report our experience with this method in 129 consecutive patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) over 27 months at a single centre and performed by a single surgeon. Patient imaging and surgical planning software were used to manufacture a 3D-printed patient-specific MIS TLIF kit for each patient consisting of a 1:1 scale spine BioModel, stereotactic K-wire guide, osteotomy guide, and retractors. Pre-selected pedicle screws, rods, and cages were sourced and supplied with the patient-specific kit. Additional implants were available on-shelf to address a size discrepancy between the kit implant and intraoperative measurements. Each BioModel was used pre-operatively for surgical planning, patient consent and education. The BioModel was sterilised for intraoperative reference and navigation purposes. Efficiency measures included operating time (153 ± 44 min), sterile tray usage (14 ± 3), fluoroscopy screening time (57.2 ± 23.7 s), operative waste (19 ± 8 L contaminated, 116 ± 30 L uncontaminated), and median hospital stay (4 days). The pre-selected kit implants exactly matched intraoperative measurements for 597/639 pedicle screws, 249/258 rods, and 46/148 cages. Pedicle screw placement accuracy was 97.8% (625/639) on postoperative CT. Complications included one intraoperative dural tear, no blood products administered, and six reoperations. Our experience demonstrates a viable application of patient-specific 3D-printed solutions and provides a benchmark for studies of efficiency in spinal fusion surgery.