激光生物效应及医学应用研究

激光作用于生物体会产生物理、化学或生物学的效应,激光正是通过这些效应达到医学基础研究、诊断和治疗疾病的目的.本文简介了激光与生物组织相互作用所产生的生物效应,概述了激光生物效应在生物学和医学研究中的应用.     

Anti-HBs characteristics after hepatitis B immunisation with plasma-derived and recombinant DNA-derived vaccines

Hepatitis B surface antigen derived from chronic hepatitis B carriers has been replaced almost completely by recombinant DNA-derived HBsAg for use as hepatitis B vaccine. Similarly, recombinant DNA-derived HBsAg is replacing plasma-derived HBsAg in standard anti-HBs assays. We analysed the influence of a change from plasma-derived HBsAg to recombinant DNA-derived HBsAg on antigen presentation in immunoassays and the characteristics of the anti-HBs antibodies after immunisation. Antigens and/or antibodies were subjected to three types of experiments: (a) binding of 'a'-loop specific monoclonal (anti-S) antibody conjugates to immobilised vaccine-HBsAg; (b) binding of post-vaccination anti-HBs to immobilised (vaccine-)HBsAg and (c) inhibition of HBsAg binding to immobilised monoclonal anti-HBs after pre-incubation with post-vaccination antibodies. Our results show that, in both antigen presentation and anti-HBs binding properties, yeast recombinant HBsAg and related antibodies could be clearly distinguished from plasma-derived HBsAg and related antibodies. Divergent results were also obtained in the inhibition assay with recombinant DNA-derived HBsAg but not with serum HBsAg from the vaccine HBsAg subtype. It is concluded that both antigen presentation in vaccines and in anti-HBs assays can markedly influence the quantitation anti-HBs response. It is suggested that a challenge with an heterologous hepatitis B virus may encounter reduced efficacy of vaccine antibodies.     

Comparison of ticarcillin plus clavulanic acid with clindamycin and gentamicin in the treatment of postcesarean endomyometritis

The efficacy of a single antibiotic--Timentin (ticarcillin with clavulanic acid)--was compared with a standard two antibiotic regimen (clindamycin and gentamicin) for the treatment of endomyometritis after cesarean delivery. The regimens were 3 grams of ticarcillin plus 100 milligrams of clavulanic acid given intravenously every four hours, or 600 milligrams of clindamycin given intravenously every six hours plus 3 to 5 milligrams per kilogram per day of gentamicin given intramuscularly. The diagnosis of endomyometritis was based upon an oral temperature of 100.4 degrees F. or higher on any two occasions, excluding the first 24 hours post partum, uterine tenderness and the absence of another focus of infection. Ninety-one patients were treated. Treatment failure rates were three of 49 in the clindamycin and gentamicin group and four of 42 of the ticarcillin plus clavulanic acid group. Treatment failures did not appear to be different from successes demographically or in risk factors for endomyometritis. The results of this study suggest that ticarcillin with clavulanic acid is as effective in the treatment of postcesarean endomyometritis as the standard regimen of clindamycin and gentamicin.     

Comparison of video trainer and virtual reality training systems on acquisition of laparoscopic skills

Training on a video trainer or computer-based minimally invasive surgery trainer leads to improved benchtop laparoscopic skill. Recently, improved operative performance from practice on a video trainer was reported. The purpose of this study was three fold: (a) to compare psychomotor skill improvement after training on a virtual reality (VR) system with that after training on a video-trainer, (VT) (b) to evaluate whether skills learned on the one training system are transferable to the other, and (c) to evaluate whether VR or VT training improves operative performance. For the study, 50 junior surgery residents completed baseline skill testing on both the VR and VT systems. These subjects then were randomized to either a VR or VT structured training group. After practice, the subjects were tested again on their VR and VT skills. To assess the effect of practice on operative performance, all second-year residents (n = 19) were evaluated on their operative performance during a laparoscopic cholecystectomy before and after skill training. Data are expressed as percentage of improvement in mean score/time. Analysis was performed by Student's paired t-test. The VR training group showed improvement of 54% on the VR posttest, as compared with 55% improvement by the VT group. The VR training group improved more on the VT posttest tasks (36%) than the VT training group improved on the VR posttest tasks (17%) (p <0.05). Operative performance improved only in the VR training group (p <0.05). Psychomotor skills improve after training on both VR and VT, and skills may be transferable. Furthermore, training on a minimally invasive surgery trainer, virtual reality system may improve operative performance during laparoscopic cholecystectomy.     

Candidate gene studies in eating disorders

It has become increasingly clear that biological factors contribute to the etiology of eating disorders. Vulnerability to anorexia and bulimia nervosa is due, at least in part, to the effect of genes. The purpose of this paper is to review the extant literature on association studies of putative candidate genes for eating disorders.     

Diagnosis and management of cystic duct leakage after laparoscopic cholecystectomy, report of 3 cases

BACKGROUND： Operative complications after laparoscopic cholecystectomy （LC） vary. Abdominal pain and other symptoms caused by fluid accumulation in the operative area are not uncommon. Cystic duct （CD） leakage is one of the main sources of the fluid. This study was to evaluate the procedures used in the diagnosis and management of CD leakage after LC. METHOD： The clinical materials of 3 patients with CD leakage after LC were studied retrospectively.     

Directionally selective complex cells and the computation of motion energy in cat visual cortex.

We applied a set of 1- and 2-bar tests to directionally selective (DS) complex cells in the cat's striate cortex, and compared the responses with those predicted by two computational models. Single-bar responses and 2-bar interactions produce distinctive patterns that are highly diagnostic. The observed responses are quite similar to those predicted by a basic (non-opponent) motion-energy model [Adelson & Bergen (1985) Journal of the Optical Society of America A, 2, 284-299]. However, they are not consistent with an opponent combination of energy models, nor are they consistent with any stage of the classic Reichardt model. In particular, the Reichardt model (as well as opponent combinations of energy models) predicts a separable space-time symmetry in the 2-bar interaction that is not observed in our measurements, while the non-opponent energy model predicts an inseparable, oriented interaction very similar to the measured cortical responses. Comparisons between model and measurements suggest possible mechanisms of spatial receptive-field organization and of nonlinear transformations.