呼吸功能不全综合实验改革的探索

目的:为了探索如何在一次教学实验中将生理学、病理生理学和药理学三个机能学科的实验有机地结合起来, 形成综合性实验以培养学生的综合思维和实验研究能力。方法:在病理生理学的呼吸功能不全实验的基础上, 增加了呼吸的生理调节和不同类型的呼吸衰竭采用不同的针对性药物治疗, 并且采用启发式教学方法。结果:学生学习兴趣明显提高, 学生不仅学到了更多的研究方法, 而且综合分析和科研创新能力都有明显提高。结论:这种改进明显提高了实验课的教学水平和教学质量。     

Neuromagnetic investigation of somatotopy of human hand somatosensory cortex

Summary In order to investigate functional topography of human hand somatosensory cortex we recorded somatosensory evoked fields (SEFs) on MEG during the first 40 ms after stimulation of median nerve, ulnar nerve, and the 5 digits. We applied dipole modeling to determine the three-dimensional cortial representations of different peripheral receptive fields. Median nerve and ulnar nerve SEFs exhibited the previously described N20 and P30 components with a magnetic field pattern emerging from the head superior and re-entering the head inferior for the N20 component; the magnetic field pattern of the P30 component was of reversed orientation. Reversals of field direction were oriented along the anterior-posterior axis. SEFs during digit stimulation showed analogous N22 and P32 components and similar magnetic field patterns. Reversals of field direction showed a shift from lateral inferior to medial superior for thumb to little finger. Dipole modeling yielded good fits at these peak latencies accounting for an average of 83% of the data variance. The cortical digit representations were arranged in an orderly somatotopic way from lateral inferior to medial superior in the sequence thumb, index finger, middle finger, ring finger, and little finger. Median nerve cortical representation was lateral inferior to that of ulnar nerve. Isofield maps and dipole locations for these components are consistent with neuronal activity in the posterior bank of central fissure corresponding to area 3b. We conclude that SEFs recorded on MEG in conjunction with source localization techniques are useful to investigate functional topography of human hand somatosensory cortex non-invasively.     

Gradual potentiation of isometric muscle force during constant electrical stimulation

An investigation was carried out into how stimulation frequency and stimulation history affect the potentiation of muscle force during 20s of constant stimulation of the two knee extensors in isometric conditions. Stimulation frequency significantly affected the potentiation pattern: low-frequency (2.5–10 Hz) stimulation showed a reduction and subsequent enhancement of force, and high-frequency (14.3–25 Hz) stimulation showed only enhancement of force. The degree of enhancement in force and time-to-peak decreased with the stimulation frequency. Whereas conditioning stimulation (both 40 Hz and 14.3 Hz) significantly enhanced the muscle force above 85%, following main stimulation (14.3 Hz) after short rest (10 s and 50 s, respectively) induced little force enhancement (below 8%). In particular, when the frequency of the conditioning stimulation was 14.3 Hz, the initial force at the main stimulation showed a very similar value to the final force value of the conditioning stimulation (above 90% similarity). The potentiated twitch force slowly decayed during rest, with an average time constant of 2.4 min. These observations indicate that muscle potentiation depends on the stimulation frequency and stimulation history, and therefore a computer model of potentiation can play an important role in predicting muscle force and body movement induced by electrical stimulation.     

Analysis of fMRI data by blind separation of data in a tiny spatial domain into independent temporal component

Independent Component Analysis (ICA) is a promising tool for the analysis of functional magnetic resonance imaging (fMRI) time series. In these studies, mostly assumed is a spatially independent component map of fMRI data (spatial ICA). In this paper, we assume that the temporal courses of the signal and noises are independent within a Tiny spatial domain (temporal ICA). Then with fast-ICA algorithm, spatially neighboring fMRI data were blindly separated into several temporal courses and were preassumed to be formed by a signal time course and several noise time courses where the signal has the largest correlation coefficient with the reference signal. The final functional imaging was completed for the signals obtained from each voxel. Simulations showed that compared with the spatial ICA method, the new temporal ICA method is more effective than the spatial ICA in detecting weak signal in a fMRI dataset. As background noise, the simulations include simulated Gaussian noise and fMRI data without stimulation. Finally, vivo fMRI tests showed that the excited areas evoked by a visual stimuli are mainly in the region of the primary visual cortex and that evoked by auditory stimuli are mainly in the region of the primary temporal cortex.     

Ventromedial hypothalamus vs. lateral hypothalamic D2 satiety receptors in the body weight increase induced by systemic sulpiride

Two experiments were conducted in order to see if dopamine satiety receptors in the lateral hypothalamus or satiety mechanisms in the ventromedial hypothalamus were involved in the hyperphagia and body weight increase induced by systemic sulpiride. In the first experiment, it was shown that systemic sulpiride (20 mg/kg) does not block the anorexia caused by intraperifornical injections of amphetamine. In the second experiment, sulpiride (20 mg/kg during 18 days) did not produce an additional increase in body weight in previously VMH-lesioned female rats. This last fact cannot be explained by a ceiling effect since insulin (5 U/day during 7 days) increased body weight in the same VMH rats in which sulpiride was not effective. These results do not support the hypothesis that systemic sulpiride reaches the perifornical dopamine D2 receptors to disinhibit feeding, but suggest instead an involvement of the ventromedial hypothalamus. This last suggestion is more in agreement with the hypothesis that sulpiride alters feeding and body weight gain through the induction of a functional gonadectomy.     

Separating the direct effect of hypoxia from the indirect effect of changes in cardiac output on the maximum pressure difference across the tricuspid valve in healthy humans

In healthy humans, changes in cardiac output are commonly accommodated with minimal change in pulmonary artery pressure. Conversely, exposure to hypoxia is associated with substantial increases in pulmonary artery pressure. In this study we used non-invasive measurement of an index of pulmonary artery pressure, the maximum systolic pressure difference across the tricuspid valve (P_max), to examine the pulmonary vascular response to changes in blood flow during both air breathing and hypoxia. We used Doppler echocardiography in 33 resting healthy humans breathing air over 6–24 h to measure spontaneous diurnal variations in P_max and cardiac output. Cardiac output varied by up to ~2.5 l/min; P_max varied little with cardiac output [0.61±0.74 (SD) mmHg min l^–1]. Eight of the volunteers were also exposed to eucapnic hypoxia (end-tidal ) for 8 h. In this group P_max rose progressively from 21 mmHg to 37 mmHg over 8 h. By comparing diurnal variations in P_max during air breathing with changes in P_max during hypoxia in the same eight individuals, we concluded that only approximately 5% of the changes in P_max during hypoxia could be attributed to concurrent changes in cardiac output. The low sensitivity of P_max to changes in cardiac output makes it a useful index of hypoxic pulmonary vasoconstriction in healthy humans.     

Relationship between saccadic eye movements and cortical activity as measured by fMRI: quantitative and qualitative aspects

We investigated the quantitative relationship between saccadic activity (as reflected in frequency of occurrence and amplitude of saccades) and blood oxygenation level dependent (BOLD) changes in the cerebral cortex using functional magnetic resonance imaging (fMRI). Furthermore, we investigated quantitative changes in cortical activity associated with qualitative changes in the saccade task for comparable levels of saccadic activity. All experiments required the simultaneous acquisition of eye movement and fMRI data. For this purpose we used a new high-resolution limbus-tracking technique for recording eye movements in the magnetic resonance tomograph. In the first two experimental series we varied both frequency and amplitude of saccade stimuli (target jumps). In the third series we varied task difficulty; subjects performed either pro-saccades or anti-saccades. The brain volume investigated comprised the frontal and supplementary eye fields, parietal as well as striate cortex, and the motion sensitive area of the parieto-occipital cortex. All these regions showed saccade-related BOLD responses. The responses in these regions were highly correlated with saccade frequency, indicating that repeated processing of saccades is integrated over time in the BOLD response. In contrast, there was no comparable BOLD change with variation of saccade amplitude. This finding speaks for a topological rather than activity-dependent coding of saccade amplitudes in most cortical regions. In the experiments comparing pro- vs anti-saccades we found higher BOLD activation in the "anti" task than in the "pro" task. A comparison of saccade parameters revealed that saccade frequency and cumulative amplitude were comparable between the two tasks, whereas reaction times were longer in the "anti" task than the pro task. The latter finding is taken to indicate a more demanding cortical processing in the "anti" task than the "pro" task, which could explain the observed difference in BOLD activation. We hold that a quantitative analysis of saccade parameters (especially saccade frequency and latency) is important for the interpretation of the BOLD changes observed with visual stimuli in fMRI.     

腹部推拿联合艾灸治疗脾虚型功能性便秘的临床疗效

目的：分析腹部推拿联合艾灸治疗脾虚型功能性便秘的临床疗效。方法：选取郑州人民医院2021年11月至2023年1月期间收治的78例脾虚型功能性便秘患者,其中艾灸治疗的39例患者纳入对照组,在艾灸治疗基础上联合腹部推拿治疗的39例患者纳入观察组。治疗后,比较两组患者临床疗效与相关临床指标。结果：观察组患者总有效率高于对照组,差异具有统计学意义（P <0.05）;治疗后,观察组患者排便次数、大便性状、盆底松弛程度、阻塞感、排便不尽感积分均低于对照组,差异具有统计学意义（P <0.05）;治疗后,观察组患者直肠肛管压差、力排时肛管残余压均低于对照组,差异具有统计学意义（P <0.05）;治疗后,观察组患者血清胃动素（MTL）、P物质（SP）水平均高于对照组,生长抑素（SS）水平低于对照组,差异具有统计学意义（P <0.05）。结论：腹部推拿联合艾灸治疗脾虚型功能性便秘可进一步改善患者相关临床指标。     

Machine Learning Algorithms to Predict Mortality and Allocate Palliative Care for Older Patients With Hip Fracture

ObjectivesTo evaluate a machine learning model designed to predict mortality for Medicare beneficiaries aged >65 years treated for hip fracture in Inpatient Rehabilitation Facilities (IRFs).DesignRetrospective design/cohort analysis of Centers for Medicare & Medicaid Services Inpatient Rehabilitation Facility–Patient Assessment Instrument data.Setting and ParticipantsA total of 17,140 persons admitted to Medicare-certified IRFs in 2015 following hospitalization for hip fracture.MeasuresPatient characteristics include sociodemographic (age, gender, race, and social support) and clinical factors (functional status at admission, chronic conditions) and IRF length of stay. Outcomes were 30-day and 1-year all-cause mortality. We trained and evaluated 2 classification models, logistic regression and a multilayer perceptron (MLP), to predict the probability of 30-day and 1-year mortality and evaluated the calibration, discrimination, and precision of the models.ResultsFor 30-day mortality, MLP performed well [acc = 0.74, area under the receiver operating characteristic curve (AUROC) = 0.76, avg prec = 0.10, slope = 1.14] as did logistic regression (acc = 0.78, AUROC = 0.76, avg prec = 0.09, slope = 1.20). For 1-year mortality, the performances were similar for both MLP (acc = 0.68, AUROC = 0.75, avg prec = 0.32, slope = 0.96) and logistic regression (acc = 0.68, AUROC = 0.75, avg prec = 0.32, slope = 0.95).Conclusion and ImplicationsA scoring system based on logistic regression may be more feasible to run in current electronic medical records. But MLP models may reduce cognitive burden and increase ability to calibrate to local data, yielding clinical specificity in mortality prediction so that palliative care resources may be allocated more effectively.     

The secret life of the mitral valve

In secondary mitral regurgitation, the concept that the mitral valve (MV) is an innocent bystander, has been challenged by many studies in the last decades. The MV is a living structure with intrinsic plasticity that reacts to changes in stretch or in mechanical stress activating biohumoral mechanisms that have, as purpose, the adaptation of the valve to the new environment. If the adaptation is balanced, the leaflets increase both surface and length and the chordae tendineae lengthen: the result is a valve with different characteristics, but able to avoid or to limit the regurgitation. However, if the adaptation is unbalanced, the leaflets and the chords do not change their size, but become stiffer and rigid, with moderate or severe regurgitation. These changes are mediated mainly by a cytokine, the transforming growth factor‐β (TGF‐β), which is able to promote the changes that the MV needs to adapt to a new hemodynamic environment. In general, mild TGF‐β activation facilitates leaflet growth, excessive TGF‐β activation, as after myocardial infarction, results in profibrotic changes in the leaflets, with increased thickness and stiffness. The MV is then a plastic organism, that reacts to the external stimuli, trying to maintain its physiologic integrity. This review has the goal to unveil the secret life of the MV, to understand which stimuli can trigger its plasticity, and to explain why the equation “large heart = moderate/severe mitral regurgitation” and “small heart = no/mild mitral regurgitation” does not work into the clinical practice.