高频电刀负反馈装置的临床应用研究

本文介绍了一种高频电刀负反馈装置，以解决经尿道前列腺汽化手术中存在的缺陷，保证手术的彻底性和病人的安全。     

Interviewing skills: self-evaluation by medical students

In an independent learning project, 52 third-year medical students carried out a structured self-assessment of two videotaped psycho-social interviews they had conducted with volunteer clients 1 year earlier, as part of a previous course. The interviews had been conducted in small tutorials with feedback from their clients, fellow students and tutors, facilitated by videotape playback. During the sequence of 16 tutorials each student had carried out an early and a late interview and had observed and participated in the discussion of the interviews of 14 peers. Students were asked to tally the frequencies of various interview behaviours, to evaluate the quality of their behaviours, and to establish priorities for future learning. The videotapes were also reliably rated by an independent observer. Students' overall self-assessments correlated 0.46 with those of the independent observer. This correlation was higher than is typically reported in studies of the validity of self-assessment. In absolute terms, the students' mean rating of interviewing performance was 3.2 (adequate plus) which was significantly lower than the observer's mean of 3.6 (adequate to good). Results are discussed in terms of Gordon's (1992) two recommendations for improving the validity of self-assessments and two further suggestions, for paired comparisons and low-threat learning environments, are added.     

What methods do stakeholders prefer for feeding back performance data: a qualitative study in palliative care.

OBJECTIVE: To investigate the opinions of stakeholders (service commissioners and providers) on how performance data should be presented, in order to develop effective feedback methods to facilitate the use of these data in decision making. DESIGN: A qualitative analysis of semi-structured face-to-face and telephone interviews. League tables and fictional box plots were presented as an illustrative guide. The themes covered in the interviews were the effectiveness of these two feedback formats, their positive and negative characteristics, and ideas for new and improved feedback mechanisms. PARTICIPANTS: Thirty-six stakeholders representing a range of clinical and non-clinical roles within palliative care and the wider health care system across a variety of statutory and non-statutory organizations from London and the West Midlands. RESULTS: Box plots were received more positively than league tables, and qualitative information was considered more appropriate than pictorial feedback. Conventional methods such as league tables and box plots were judged to lack essential information on which important decisions could be based, such as additional contextual information and the methodological assumptions of the instrument. Both feedback methods were considered useful as an impetus to further discussion. There was a consensus that feedback should be constructive and able to be adapted to the organizational realities in which UK health services function. CONCLUSION: Qualitative research was viewed as the right evidence for gaining an understanding of the quality of end of life care. Stakeholders highlighted the importance of the lay perspective, which requires approaches that illuminate the subjective meanings of patient experience.     

Role of Estrogens on Human Male Reproductive System

This review focuses on estrogen role on human male physiology. Biological estrogen actions on male reproductive system are summarized with particular regard to the effects of congenital estrogen deprivation in men. The effects of estrogen on spermatogenesis, hormonal secretion and gonadotropin feedback and on sexual behavior are discussed. It is remarked that the role of estrogens in male reproduction is a very recent acquisition in reproductive endocrinology, but it promises new future fields of research to be investigated as well as the possible disclosure of new strategies in clinical practice.     

An optimal dynamic output feedback controller for a flexible spacecraft

The design of a low-order dynamic output feedback controller for a flexible spacecraft is carried out using modified linear quadratic Gaussian (LQG) theory. The necessary conditions for optimization are given. The linear equations governing a flexible spacecraft with a central rigid body and two sun-tracking solar panels are presented. The parameters of the Solar Electric Propulsion Spacecraft (SEPS) are selected for analysis and simulation. The optimal gains for the dynamic controller are estimated using an iterative algorithm. The sequential procedure which assures convergence is selected. The initial gains which stabilize the system are chosen on the basis of the principle of a PD controller. A third-order controller for pitch, roll and yaw axes of the 18th-order system, which includes sensor and actuator dynamics, is designed. Numerical simulations carried out to ascertain the performance of the controller show the performance to be satisfactory.     

CHARACTERISTICS OF MEMBRANE TRANSPORT PROCESSES OF MACULA DENSA CELLS

1. Macula densa (MD) cells are located within the thick ascending limb (TAL) and have their apical surface in contact with tubular fluid and their basilar region in contact with the glomerulus. These cells sense changes in luminal fluid sodium chloride concentration ([NaCl]) and transmit signals resulting in changes in vascular resistance (tubuloglomerular feedback) and renin release. 2. Current efforts have focused on understanding the cellular transport mechanisms of MD cells. Progress in this area has benefited from the use of the isolated perfused TAL-glomerular preparation, which permits direct access to MD cells. 3. Using microelectrodes to measure basolateral membrane potential (V_BL) of MD cells, it was found that VBL was very sensitive to changes in luminal fluid [NaCl]. As [NaCl] was elevated from 20 to 150mmol/L, V_BL was found to depolarize by over 30 mV. 4. Basolateral membrane potential measurements were also used to identify an apical Na⁺: 2CI^?: K⁺ cotransport pathway in MD cells that is the major pathway for NaCl entry into these cells. 5. Other work identified a basolateral chloride channel that is presumed to be responsible for changes in V_BL during alterations in luminal [NaCl]. This channel, which is the predominant conductance across the basolateral membrane, may be regulated by intracellular Ca²⁺ and cAMP. 6. An apical Na⁺: H⁺ exchanger in MD cells was detected by measuring changes in intracellular pH using the fluorescent probe 2′,7′-bis-(2-carboxyethyl)-5(and-6) carboxyfluorescein. 7. Using patch-clamp techniques, a high density of pH- and Ca²⁺-sensitive K⁺ channels was observed at the apical membrane of MD cells. 8. Other studies found that, at the normal physiological conditions prevailing at the end of the TAL (luminal [NaCl] of 20–60 mmol/L), reabsorption mediated by MD cells is very sensitive to changes in luminal [NaCl].     

Renal interstitial pressure and tubuloglomerular feedback control in rats during infusion of atrial natriuretic peptide (ANP)

Atrial natriuretic peptide (ANP), injected at physiological concentrations, is known to induce both natriuresis and diuresis. It has been suggested by some investigators that these changes result from an increasing glomerular filtration rate (GFR), but others have been unable to demonstrate an increased GFR. The tubuloglomerular feedback (TGF) mechanism is an important regulator of GFR, and the sensitivity of TGF is decreased during ANP administration. Furthermore, resetting of TGF is, in most instances, related to changes in renal interstitial hydrostatic and oncotic pressures. It is also known that ANP may increase capillary permeability which may change renal interstitial pressure. The present study was performed to examine renal interstitial pressures and the TGF mechanism during ANP infusion. In accordance with previous studies, TGF sensitivity was found to be decreased. The tubular flow rate which elicited half the maximal drop in stop-flow pressure (P_sf) was increased from 18.5 to 25.7 nl min^-1. In contrast, ANP infusion resulted in a decreased interstitial hydrostatic pressure and an increased interstitial oncotic pressure. From previous experiments, such changes in interstitial pressures would be expected to increase TGF sensitivity. The changes in interstitial pressure cannot, therefore, directly explain the resetting of the feedback mechanism. In conclusion, the present paper shows a decreased renal net interstial pressure after intravenous administration of ANP.     

Confidants' feedback and traumatic life events

One hundred six undergraduate (83 women and 23 men) completed surveys concerning their most traumatic life event, the feedback they received following their disclosure of the event to others, and how they felt after the disclosure. Results indicated that the better they felt after disclosure, the less disturbed they were by thoughts of the event at the time of the study. In addition, the more personal the trauma was, the worse they felt after their disclosure, and the more disturbed they were about the trauma. However, no significant relation existed between the positivity (e.g., supportiveness) of their confidant's feedback and their present degree of disturbance. Implications for understanding the complex relation between confiding traumatic events and resolving feelings surrounding those events were discussed.     

Inhibition of ligand binding to g protein-coupled receptors by arachidonic acid

Arachidonic acid (AA), released in response to muscarinic acetylcholine receptor (mAChR) stimulation, previously has been reported to function as a reversible feedback inhibitor of the mAChR. To determine if the effects of AA on binding to the mAChR are subtype specific and whether AA inhibits ligand binding to other G protein-coupled receptors (GPCRs), the effects of AA on ligand binding to the mAChR subtypes (M₁, M₂, M₃, M₄, and M₅) and to the μ-opioid receptor, β₂-adrenergic receptor (β₂-AR), 5-hydroxytryptamine receptor (5-HTR), and nicotinic receptors were examined. AA was found to inhibit ligand binding to all mAChR subtypes, to the β₂-AR, the 5-HTR, and to the μ-opioid receptor. However, AA does not inhibit ligand binding to the nicotinic receptor, even at high concentrations of AA. Thus, AA inhibits several types of GPCRs, with 50% inhibition occurring at 3–25 μM, whereas the nicotinic receptor, a non-GPCR, remains unaffected. Further research is needed to determine the mechanism by which AA inhibits GPCR function.     

一类“近乎双线性”系统及其稳定化反馈控制

本文定义了一类“近乎双线性”系统。可用以近似一类奇异摄动双线性系统,而且可以描述某些实际工业对象。并发现其控制器的设计较方便。文中还给出了一种简单的反馈控制器的设计方法。又对一类多输入双线性系统,提出一种设计反馈控制器的改进方案,根据Lyapunov定理得到一非线性反馈控制律。以上设计方法分别对某合成氨反应器作了应用研究,仿真结果表明了方法的有效性。