Echocardiographic-cineangiographic correlation in detecting left ventricular aneurysm: A prospective study of 422 patients

Four hundred twenty-two consecutive patients with a documented myocardial infarction underwent cardiac catheterization and echocardiographic examination. Adequate two dimensional echocardiograms were obtained in 386 patients (91 percent). Left ventricular aneurysm was defined echocardiographically and cineangiographically as a well demarcated bulge in the contour of the left ventricular wall during both diastole and systole, demonstrating dyskinesia or akinesia. Cineangiography was considered as the standard for the diagnosis of left ventricular aneurysm. The site of aneurysm was mainly anteroapical.An aneurysm was judged present on cineangiography in 111 patients and on echocardiography in 118 patients. The presence and absence of an aneurysm echocardiographically correlated in 103 and 260 patients, respectively, with cineangiography. In 8 patients a cineangiographically identified aneurysm was not manifested echocardiographically, whereas in 15 patients an aneurysm identified on echocardiography was not evident on cineangiography. Thus two dimensional echocardiography can detect or exclude a left ventricular aneurysm with a high level of sensitivity (93 percent) and specificity (94 percent).     

Estimate of capillary permeability coefficients of canine heart to sodium and glucose

Measurements of fractional extraction (E) were used to study the transcapillary diffusion of sodium and glucose in isolated, nonworking, spontaneously beating dog hearts, perfused with blood of low hematocrit at controlled flows. Papaverine, dipyridamole, and norepinephrine were used, in separate experiments, to increase vascular conductance and capillary density. E-Sodium fell from 0.77 to 0.23 and E-glucose from 0.70 to 0.11 as plasma flow (F) was varied from 23 to 422 ml/min · 100 g. Permeability-surface area products (PS), calculated from PS = ?F ln (1 ? E), for both molecules increased progressively over the range of flows. Assuming S to be 500 cm²/g, capillary permeability coefficients were estimated from the maximal mean PS observed. Calculated P values (× 10^?5 cm/sec) for sodium and glucose were 3.91 and 2.13, respectively. The ratio of P-Na to P-glucose was analyzed statistically at various flow ranges. Mean $\text{P-}\text{Na}\text{P-}\text{glucose}$ ratios were proportional to the $\text{D-}\text{Na}\text{D-}\text{glucose}$ ratio (D, free-diffusion constant) at all flows greater than 40 ml/min · 100 g. Comparison of $\text{D-}\text{Na}\text{D-}\text{glucose}$ to $\text{D′-}\text{Na}\text{D′-}\text{glucose}$ (D′, restricted diffusion constant) at various pore radii showed that proportionality between Ps and Ds ratios is not a sufficient argument for free diffusion of Na and glucose across capillary walls.     

Effect of interaction between insulin and glucagon on glucose turnover and FFA concentration in normal and depancreatized dogs

We showed previously that arginine increased glucose production (R_a) and utilization (R_d) synchronously in normal dogs and suggested that this was due to concurrent insulin and glucagon release. In order to investigate the metabolic effects of coincidently elevated insulin and glucagon levels on R_a and R_d, glucagon was infused (1.55 μg/kg/hr) into normal dogs and into depancreatized dogs coincident with graded amounts of insulin (250–3000 μU/kg/min) until the metabolic response of the normal dog was achieved in depancreatized dogs. Main observations: Concurrent insulin and glucagon elevations increased glucose turnover (100%) in normal and depancreatized dogs while maintaining normoglycemia. Glucagon had no appreciable effect on peripheral glucose clearance in depancreatized dogs maintained on basal insulin. The effect of glucagon on R_a was not inhibited by concurrent insulin infusion at rates up to 3000 μU/kg/min. The effect of glucagon on R_a waned with time, indicating that a given insulin/glucagon ratio did not have a sustained effect. Near normal metabolic effects with respect to glucose turnover and FFA concentration were achieved in depancreatized dogs when the normal IRI response to glucagon was reproduced, indicating that the spike pattern of insulin release reflects not only the inherent secretory characteristic of β cells, but also serves an important glucoregulatory function. Glucagon induced an increase in ¹⁴C-glucose recycling, suggesting that it enhanced gluconeogenesis.     

Effect of inhibitors of proteolysis and arachidonic acid metabolism on burn-induced protein breakdown

A rat model has been developed to study the local effects of burn injury on the underlying muscle tissue. Protein turnover was measured in soleus muscle incubated in vitro in which both tyrosine release and protein synthesis was measured. A scald injury (3 seconds) to a small area of one hindlimb produces an increase in muscle proteolysis and is without effect on the soleus muscle of the contralateral leg. A very high concentration of indomethacin (40 mumol/L) had no effect on proteolysis in the control muscle but specifically inhibited burn-induced protein breakdown. However, since other cyclooxygenase inhibitors (aspirin and ibuprofen), lipoxygenase inhibitors (ETYA, NDGA, and esculetin), and mepacrine (a phospholipase inhibitor) had no effect on protein breakdown, it is unlikely that a product of arachidonic acid metabolism maintains the increased proteolysis in vitro. In addition, endogenous production of prostaglandin E2 (PGE2) was not different in muscles from burned and control legs. Probes of the proteolytic pathway using inhibitors show that the burn-induced stimulation of proteolysis is consistent with the stimulation of lysosomal protease activity. These results are supported by the observation of increased acid protease activity in muscle homogenates from the burned leg. The best hypothesis that explains these data is that a lysosomal pathway of protein degradation may be enhanced by burn. Products of arachidonic acid metabolism do not appear to maintain burn-induced proteolysis in muscle, although their role in initiating the pathological changes in vivo cannot be excluded.     

虚拟仿真实验在中职生理学"教学做"一体化教学中的应用

目的:探讨虚拟仿真实验在中职护理专业生理学"教学做"一体化教学中的应用效果,构建适应现代护理职业教育的生理学课程教学模式.方法:将某校2014级护理4班60名护生为对照组、6班58名护生分为实验组,对照组采用传统的教学方法,实验组采用虚拟仿真实验系统进行一体化教学.结果:实验组的教师、学生的满意度及考核成绩高于对照(P<0.05).结论:虚拟仿真实验系统运用于中职护理专业生理学"教学做"一体化教学效果明显,可以提高护生的综合素质.     

The physiological and biomechanical effects of forwards and reverse sports wheelchair propulsion

Objective

To explore the physiological and biomechanical differences between forwards (FOR) and reverse (REV) sports wheelchair propulsion.

Design

Fourteen able-bodied males with previous wheelchair propulsion experience pushed a sports wheelchair on a single-roller ergometer in a FOR and REV direction at three sub-maximal speeds (4, 6, and 8 km/hour). Each trial lasted 3 minutes, and during the final minute physiological and biomechanical measures was collected.

Results

The physiological results revealed that oxygen uptake (1.51 ± 0.29 vs. 1.38 ± 0.26 L/minute, P = 0.005) and heart rate (121 ± 19 vs. 109 ± 14 beats/minute, P < 0.0005) were significantly greater during REV than FOR only during the 8 km/hour trials. From a biomechanical perspective, push frequencies were similar between FOR and REV across all speeds (P > 0.05). However, greater mean resultant forces were applied during FOR (P < 0.0005) at 4 km/hour (66.7 ± 19.5 vs. 49.2 ± 10.3 N), 6 km/hour (90.7 ± 21.9 vs. 65.3 ± 18.6 N), and 8 km/hour (102.5 ± 17.6 vs. 68.7 ± 13.5 N) compared to REV. Alternatively, push times and push angles were significantly lower (P ≤ 0.001) during FOR at each speed.

Conclusions

The current study demonstrated that at higher speeds physiological demand becomes elevated during REV. This was likely to be associated with an inability to apply sufficient force to the wheels, thus requiring kinematic adaptations in order to maintain constant speeds in REV.     

Age-adjusted Charlson Comorbidity Index Does Not Predict Outcomes in Patients Submitted to Noninvasive Ventilation

Introduction

Comorbidities are thought to have prognostic impact on outcomes of patients submitted to noninvasive ventilation (NIV). Our goal was to determine if age-adjusted Charlson comorbidity index (ACCI) could predict outcomes in patients undergoing NIV due to acute respiratory failure.

Lipoprotein lipase activity and cellularity in brown and white adipose tissue in Zucker obese rats

The genetically obese adult Zucker rat (fafa) exhibits reduced thermogenesis when stimulated by physiological agents (cold, catecholamines). Recent evidence suggests that this thermogenic defect may be important in the manifestation of the animal's obesity and that it reflects a reduced thermogenic contribution from brown adipose tissue, the major nonshivering thermogenic site in many mammals. The present study describes the effects of the obese genotype on brown (and white) adipocyte size, number, and lipid content and tissue lipoprotein lipase (LPL) activity. In the obese rats, brown fat depots were increased in mass. This increase could be accounted for by brown fat hypertrophy (due primarily to an increase in the amount of triglyceride present in each cell) rather than hyperplasia (there being no increase in the number of brown fat cells). In addition, unlike the situation in white fat, the brown fat from the obese rats did not exhibit higher LPL activity than did the brown fat from their lean littermates. This absence of an increased capacity for triglyceride uptake, coupled with the greater amount of triglyceride per brown adipocyte, is consistent with a reduction of triglyceride oxidation (and, thus, heat production) in the cells from the obese (v the lean) rats.     

Left atrial physiology and pathophysiology: Role of deformation imaging

The left atrium (LA) acts as a modulator of left ventricular (LV) filling. Although there is considerable evidence to support the use of LA maximum and minimum volumes for disease prediction, theoretical considerations and a growing body of literature suggest to focus on the quantification of the three basic LA functions: (1) Reservoir function: collection of pulmonary venous return during LV systole; (2) Conduit function: passage of blood to the left ventricle during early LV diastole; and (3) Contractile booster pump function (augmentation of ventricular filling during late LV diastole. Tremendous advances in our ability to non-invasively characterize all three elements of atrial function include speckle tracking echocardiography (STE), and more recently cardiovascular magnetic resonance myocardial feature tracking (CMR-FT). Corresponding imaging biomarkers are increasingly recognized to have incremental roles in determining prognosis and risk stratification in cardiac dysfunction of different origins. The current editorial introduces the role of STE and CMR-FT for the functional assessment of LA deformation as determined by strain and strain rate imaging and provides an outlook of how this exciting field may develop in the future.     

Are hotshots always hot? A longitudinal study of hormones, behavior, and reproductive success in male marine iguanas

Polygynous lek-mating systems are characterized by high reproductive skew, with a small number of males gaining a disproportionate share of copulations. In lekking species, where female choice drives male mating success and patterns of reproductive skew, female preferences for ‘good genes’ should lead to preferred males having high reproductive success in all years. Here we investigate whether these ‘hotshot’ males have steroid hormone patterns that are consistent over time (between two mating seasons), and whether hormone levels consistently predict display behavior. We test these questions in the Galápagos marine iguana (Amblyrhynchus cristatus), a lekking vertebrate with high male reproductive skew. We found that male mating success and testosterone levels were not consistent across years. The most successful males showed an inverse relationship in copulation success between years. Similarly, territorial males that had high testosterone in one year had low levels in the next. Across years, testosterone was strongly associated with head-bob display, suggesting that this steroid plays a key role in mate attraction. These results suggest that female marine iguanas are not choosing the same ‘hotshot’ males in every year, but instead base their reproductive decisions on male behavioral traits that are hormonally mediated and variable across years. By using testosterone to regulate their costly display behaviors male marine iguanas appear to have a mechanism that allows them to adjust their reproductive effort depending on extrinsic and/or intrinsic factors.