运动员心功能评估新方法和新指标的研究

目的：探讨无创检测和评估心功能的新指标和新方法。方法：随机抽取81名体育系学生（买验组,n=81）和41名普通系学生（对照组,n=41）,完成规定运动量的台阶运动后,通过采集心音信号,进行了心率,D／S比值以及S1／S2比值的对照研究。结果：在静息状态下,体育系学生的心率为66．2±8．7,D／S比值为2．04±0．33;晋通系学生的心率为70．8±8．0,D／S比值为1．82±0．27;在全运动量下,体育系学生的S1／S2比值为7．34±4．04;普通系学生的S1／S2比值为5．22±2．38。,结论：体育系学生比普通系学生具有较高水平的心脏储备：该方法可用来评估运动员与一般人的心脏储备,为运动员选拔以及一般人体质评估提供一种客观量化的新指标。     

Pneumococcal meningitis in childhood: a longitudinal prospective study

After implementation of programmes for active immunization against Haemophilus influenzae b, Streptococcus pneumoniae and Neisseria meningitidis became the most common agents of bacterial meningitis in childhood. Over a 9-year period, children showing clinical and laboratory findings of meningitis on the basis of their positive cultures of blood or cerebro-spinal fluid (CSF) for S. pneumoniae were enrolled. Predisposing conditions, clinical and laboratory findings, and microbiological and imaging studies were considered. Meningitis-related death or neurological sequelae defined an unfavourable outcome. Sixty-four patients met the inclusion criteria. Thirty-one (48%) children had predisposing conditions to pneumococcal meningitis. Fever and neck stiffness were the main symptoms; 14 patients (22%) reported seizures before admission. Twenty-one patients required treatment in the intensive care unit (ICU). Streptococcus pneumoniae strains were penicillin susceptible in 54 cases (84%). Forty-eight children (75%) showed complete recovery. Two patients (3%) died, and 14 (22%) had sequelae. Patients with a low CSF cell count, low neutrophils, early admission to ICU or infection by penicillin-nonsusceptible strains of S. pneumoniae had an unfavourable outcome more frequently. Low blood neutrophils, low CSF cell count, early admission to ICU and infection by penicillin-nonsusceptible strains are the main factors predicting an unfavourable outcome in children with pneumococcal meningitis.     

Racial differences in cardiac structure and function in essential hypertension.

OBJECTIVE--To assess racial differences in cardiac structure and function in patients presenting with previously untreated hypertension. DESIGN--Untreated black patients with hypertension were compared with untreated white patients matched for age and sex. Both groups had similar body mass indices, blood pressures, and reported duration of hypertension. SETTING--Cardiovascular risk factor clinic for outpatients. SUBJECTS--36 men and 22 women with untreated essential hypertension. MAIN OUTCOME MEASURES--Variables of heart structure and function on cross sectional and Doppler echocardiography. RESULTS--The black patients had a significantly greater interventricular septal thickness (mean 1.23 (95% confidence interval 1.14 to 1.33) v 1.09 (1.02 to 1.16) cm; P = 0.02) and posterior wall thickness (mean 1.14 (1.07 to 1.22) v 0.96 (0.88 to 1.03) cm; P = 0.001) than the white patients, although left ventricular internal diameter was not significantly different (mean 4.90 (4.68 to 5.12) v 4.82 (4.64 to 5.01) cm; P = 0.59). This resulted in a significantly greater left ventricular mass index (mean 151 (137 to 164) v 120 (107 to 133) g/m2; P = 0.001) and relative wall thickness (mean 0.47 (0.43 to 0.51) v 0.40 (0.37 to 0.42) cm; P = 0.004) in the black patients. Comparison of Doppler measures of left ventricular diastolic function showed a significantly longer isovolumic relaxation time in black patients (mean 107 (98 to 116) v 92 (83 to 101) ms; P = 0.02) compared with white patients, although peak early to atrial filling ratios were similar in both groups (mean 1.14 (0.95 to 1.32) v 1.04 (0.94 to 1.15); P = 0.37). CONCLUSION--Among previously untreated hypertensive patients, black subjects compared with white subjects have significantly higher left ventricular mass index and relative wall thickness, as well as more impairment of left ventricular function during diastole.     

Insulin inhibits myocardial ischemia-induced apoptosis and alleviates chronic adverse changes in post-ischemic cardiac structure and function

Insulin has been shown to possess significant anti-apoptotic effect in myocardial ischemia/reperfusion (MI/R). However, the contribution by this protection of insulin to the prolonged cardiac function in rats subjected to ischemia remains unclear. The present study attempted to test whether early insulin treatment influences adverse prolonged post-ischemic cardiac structural and functional changes. Adult male rats were subjected to left anterior descending coronary artery occlusion and were randomized to receive one of the following treatments: saline (4 ml/kg/h i.v. injection beginning 10 min before the ischemia and continuing for 2 h), insulin (60 U/l, i.v. injection following the same routine, and hypodermic injection of insulin (0.5 U/ml, 1 ml/kg/d) for 3 days after the ischemia surgery) or insulin plus wortmannin (15 μg/kg i.v. injection 15 min before each insulin administration). Treatment with insulin significantly reduced infarct size, decreased plasma creatine kinase and lactate dehydrogenase activities, decreased apoptosis index and caspase-3 activity (all P < 0.01 vs. saline), and improved cardiac function 24 h after ischemia. Importantly, at the end of 4 weeks after the ischemia surgery, MI rats receiving insulin treatment showed smaller left ventricle (LV) cavity and thicker systolic interventricular septum, and increased cardiac ejection fraction and LV fractional shortening (all P < 0.05 vs. saline). Inhibition of insulin signaling with wortmannin not only blocked insulin’s anti-apoptotic effect, but also almost completely abolished effects of insulin on cardiac structure and function. These data indicate that inhibition of apoptosis by early insulin treatment alleviates chronic adverse changes in post-ischemic cardiac structure and function. Wenjuan Xing and Wenjun Yan contributed equally to this study.     

Rheumatic symptoms after cardiac surgery: a prospective study.

The incidence of different types of shoulder pain after open heart surgery was studied prospectively. Of 101 patients studied, 45 developed rheumatic symptoms during the first six weeks after the operation. Thirty eight patients reported pain in the region of the shoulder girdle with no loss of shoulder function (postpericardiotomy rheumatism). Three of these patients also had features compatible with the postpericardiotomy syndrome (fever, malaise, or pleuritic chest pain), and seven developed the syndrome without pain in the shoulder girdle. Of these 10 patients, one had generalised myalgia. Postpericardiotomy rheumatism alone was not associated with increased inflammation (measured by the erythrocyte sedimentation rate and concentration of C reactive protein); immunological tests including measurement of antibodies to cardiac muscle yielded inconclusive results. Replies to a postal questionnaire showed that symptoms of postpericardiotomy rheumatism were present for over three months in 18 patients and for six months or longer in 14. In view of the large number of patients now having open heart surgery postpericardiotomy rheumatism should be considered when patients report pain around the shoulders so that it is not misdiagnosed as angina.     

Peak exercise stroke volume: associations with cardiac structure and diastolic function.

One of the most debilitating effects of primary aging is the decline in aerobic exercise capacity. One of its causes is an age-related decline in peak exercise stroke volume. This study's main purpose was to determine the cardiovascular adaptations to aging that most influence peak exercise stroke volume in the elderly. We hypothesized that increased left ventricular (LV) filling and mild concentric LV remodeling would be associated with an increase in peak exercise stroke volume corrected for lean body mass (LBM) and that an increased augmentation index (AI), which is a marker of arterial stiffness, would be associated with a decrease. A second aim was to determine the adaptations to aging that most influence LV concentric remodeling in the elderly. We hypothesized that AI would be a predictor of LV mass/LBM and the LV posterior wall thickness-to-LV radius ratio (h/r). We performed a cross-sectional study of cardiac and vascular adaptations to aging in 52 sedentary, elderly subjects. LV filling [as measured by the early-to-late transmitral flow velocity ratio (E/A)] was inversely correlated with and was an independent predictor of peak exercise stroke volume/LBM and was also a predictor of LV remodeling. AI was a predictor of LV remodeling (LV mass/LBM) but not of peak exercise stroke volume/LBM. We conclude that 1) maintenance of LV filling (E/A <1) is associated with a higher peak exercise stroke volume/LBM in very elderly subjects and thus may be a useful adaptation that enhances stroke volume during peak exercise, 2) LV remodeling and AI are less influential on peak exercise stroke volume/LBM, and 3) AI was the most important predictor of LV remodeling.     

Metacarpophalangeal length changes in humans during adulthood: a longitudinal study.

Total lengths of the 19 diaphyseal hand bones were measured from standardized radiographs of healthy American whites as young adults (ca. 21 years) and again at ca. 55 years of age. The four hand-bone rows exhibit distinctive length changes: Distal and middle phalanges continue to increase significantly in length, proximal phalanges constitute a transition zone of little change, and metacarpals uniformly decrease in length. Clear-cut sex differences are noteworthy: Males change more (lose more in some bone rows, gain more in others) than females. Progressive elongation was greatest in the distal phalanges where apposition around the distal aspect ("tufting") is not constrained by a joint or epiphysis. Loss of bone length in the metacarpals by subchondral resorption is consistent with documented reductions in activity levels and grip strength with age, as well as diminished joint spaces which alter loading of the joints.     

Muscle fiber size and function in elderly humans: a longitudinal study.

Cross-sectional studies are likely to underestimate age-related changes in skeletal muscle strength and mass. The purpose of this longitudinal study was to assess whole muscle and single muscle fiber alterations in the same cohort of 12 older (mean age: start of study 71.1+/-5.4 yr and end of study 80+/-5.3 yr) volunteers (5 men) evaluated 8.9 yr apart. No significant changes were noted at follow-up in body weight, body mass index, and physical activity. Muscle strength, evaluated using isokinetic dynamometry, and whole muscle specific force of the knee extensors were significantly lower at follow-up. This was accompanied by a significant reduction (5.7%) in cross-sectional area of the total anterior muscle compartment of the thigh as evaluated by computed tomography. Muscle histochemistry showed no significant changes in fiber type distribution or fiber area. Experiments with chemically skinned single muscle fibers (n=411) demonstrated no change in type I fiber size but an increase in IIA fiber diameter. A trend toward an increase in maximal force in both fiber types was observed. Maximum unloaded shortening velocity did not change. In conclusion, single muscle fiber contractile function may be preserved in older humans in the presence of significant alterations at the whole muscle level. This suggests that surviving fibers compensate to partially correct muscle size deficits in an attempt to maintain optimal force-generating capacity.     

Preserved autonomic function in amenorrheic athletes.

Reproductive hormones such as estradiol and progesterone are known to influence autonomic cardiovascular regulation. The purpose of this study was to determine whether amenorrheic athletes (AA) have impaired autonomic cardiovascular regulation compared with eumenorrheic athletes (EA). Thirty-five athletes were tested: 13 AA (19 +/- 1 yr), 13 EA (21 +/- 1 yr), and 9 EA (23 +/- 1 yr) on oral contraceptives (EA-OC). Multiple indexes of autonomic cardiovascular regulation were assessed: respiratory sinus arrhythmia (RSA), cardiovagal baroreflex sensitivity (BRS) via phase IV and phase II of the Valsalva maneuver, a spontaneous index of BRS, and the heart rate and blood pressure responses to orthostatic stress (20-min 60 degrees head-up tilt). RSA was not different among the groups. There were no group differences in the spontaneous index of BRS (AA = 30 +/- 6, EA = 24 +/- 3, EA-OC = 29 +/- 5 ms/mmHg) or in phase II (AA = 8 +/- 2, EA = 7 +/- 1, EA-OC = 8 +/- 1 ms/mmHg) of the Valsalva. There was a difference in BRS during phase IV (AA = 21 +/- 3, EA = 15 +/- 1, EA-OC = 26 +/- 6 ms/mmHg; ANOVA P = 0.04). Tukey's post hoc test indicated that BRS was greater in the EA-OC group compared with the EA group (P = 0.04). There were no differences in cardiovascular responses to orthostatic stress among the groups. In conclusion, AA do not display signs of impaired autonomic function and orthostatic responses compared with EA or EA-OC during the follicular phase of the menstrual cycle.     

Sperm competition games: a prospective analysis of risk assessment.

We develop the logic of assessment of sperm competition risk by individual males where the mechanism of sperm competition follows a ''loaded raffle'' (first and second inseminates of a female have unequal prospects). Male roles (first or second to mate) are determined randomly. In model 1, males have no information about the risk associated with individual females and ejaculation strategy depends only on the probability, q, that females mate twice. Evolutionarily stable strategy (ESS) ejaculate expenditure increases linearly from zero with q, and reduces with increasing inequality between ejaculates, though the direction of the loading (which role is favoured) is unimportant. In model 2, males have perfect information and can identify each of three risk states: females that will (1) mate just once (''no risk''), (2) mate twice but have not yet mated (''future risk''), and (3) mate twice and have already mated (''past risk''). The ESS is to ejaculate minimally with ''no risk'' females, and to expand equally with ''past'' and ''future'' risk females; the direction of the competitive loading is again unimportant. Expenditure again increases with risk, but is now non-zero at extremely low risk. Model 3 examines three cases of partial information where males can identify only one of the three risk states and cannot distinguish between the other two: they therefore have just two information sets or ''contexts''. Expenditure in both contexts typically rises non-linearly from zero with q, but (whatever the loading direction) expenditure is higher in the context with higher risk (e.g. if contexts are ''mated'' and ''virgin'', males spend more with mated females). However, in highly loaded raffles, sperm expenditure can decrease over part of the range of risk. Also, the direction of the loading now affects expenditure. Biological evidence for the predictions of the models is summarized and discussed.     

Abnormal cardiac structure and function in mice expressing nonphosphorylatable cardiac regulatory myosin light chain 2.

A role for myosin phosphorylation in modulating normal cardiac function has long been suspected, and we hypothesized that changing the phosphorylation status of a cardiac myosin light chain might alter cardiac function in the whole animal. To test this directly, transgenic mice were created in which three potentially phosphorylatable serines in the ventricular isoform of the regulatory myosin light chain were mutated to alanines. Lines were obtained in which replacement of the endogenous species in the ventricle with the nonphosphorylatable, transgenically encoded protein was essentially complete. The mice show a spectrum of cardiovascular changes. As previously observed in skeletal muscle, Ca(2+) sensitivity of force development was dependent upon the phosphorylation status of the regulatory light chain. Structural abnormalities were detected by both gross histology and transmission electron microscopic analyses. Mature animals showed both atrial hypertrophy and dilatation. Echocardiographic analysis revealed that as a result of chamber enlargement, severe tricuspid valve insufficiency resulted in a detectable regurgitation jet. We conclude that regulated phosphorylation of the regulatory myosin light chains appears to play an important role in maintaining normal cardiac function over the lifetime of the animal.     

Bacterial community structure of a pesticide-contaminated site and assessment of changes induced in community structure during bioremediation

The introduction of culture-independent molecular screening techniques, especially based on 16S rRNA gene sequences, has allowed microbiologists to examine a facet of microbial diversity not necessarily reflected by the results of culturing studies. The bacterial community structure was studied for a pesticide-contaminated site that was subsequently remediated using an efficient degradative strain Arthrobacter protophormiae RKJ100. The efficiency of the bioremediation process was assessed by monitoring the depletion of the pollutant, and the effect of addition of an exogenous strain on the existing soil community structure was determined using molecular techniques. The 16S rRNA gene pool amplified from the soil metagenome was cloned and restriction fragment length polymorphism studies revealed 46 different phylotypes on the basis of similar banding patterns. Sequencing of representative clones of each phylotype showed that the community structure of the pesticide-contaminated soil was mainly constituted by Proteobacteria and Actinomycetes. Terminal restriction fragment length polymorphism analysis showed only nonsignificant changes in community structure during the process of bioremediation. Immobilized cells of strain RKJ100 enhanced pollutant degradation but seemed to have no detectable effects on the existing bacterial community structure.     

Microscopic assessment of membrane protein structure and function

Membrane proteins represent an important class of proteins that are encoded by about 40% of all genes, but compared to soluble proteins structural information is sparse. Most of the atomic coordinates currently available are from bacterial membrane proteins and have been obtained by X-ray crystallography. Recent results demonstrate the imaging power of the atomic force microscope and the accuracy of electron crystallography. These methods allow membrane proteins to be studied while embedded in the bilayer, and thus in a functional state. The low signal-to-noise ratio of cryoelectron microscopy is overcome by crystallizing membrane proteins in a two-dimensional protein-lipid membrane, allowing its atomic structure to be determined. In contrast, the high signal-to-noise ratio of atomic force microscopy allows individual protein surfaces to be imaged at subnanometer resolution, and their conformational states to be sampled. This review discusses examples of microscopic membrane protein structure determination and illuminates recent progress.     

The baseline and longitudinal changes of PCC connectivity in mild cognitive impairment: a combined structure and resting-state fMRI study

The baseline and longitudinal changes of the posterior cingulate cortex (PCC) connectivity were assessed in order to clarify the neural mechanism of mild cognitive impairment (MCI). Twenty-eight right-handed subjects (14 MCI patients and 14 healthy elders) participated in this study. Clinical and neuropsychological examinations were performed on all the subjects. PCC functional connectivity was studied by examining the correlation between low frequency fMRI signal fluctuations in the PCC and those in all the other brain regions. Additionally, we traced all the MCI patients and compared their PCC connectivity in the initial stage and that in 3 years later. We also explored the relationship between the PCC functional connectivity strength and cognitive performances. Our results are as follows: Functional connectivity between the PCC and a set of regions is decreased in MCI patients. Most of these regions are within the default mode network (DMN). Three years later, the regions of superior frontal gyrus (SFG) and middle frontal gyrus (MFG) presented further decreased connectivity to the PCC in MCI. In addition, we also find enhanced functional connectivity between PCC and medial prefrontal cortex (MPFC), PCC and anterior cingulate cortex (ACC) in MCI patients. At last, our research also shows that the PCC connectivity with some regions significantly correlates with the cognitive performances of patients as measured by mini-mental state examination (MMSE), and California verbal learning test (CVLT) scores. The baseline and longitudinal changes of the PCC connectivity in our study suggest that impairment and compensation coexist in the disease progress of MCI patients.