Laser Doppler flowmetry of blood perfusion in mucoperiosteal flaps covering membranes in bone augmentation and implant procedures. A pilot study in dogs.

In guided tissue regeneration (GTR) procedures, flap recession or sloughing may occur as an unwanted sequel to the placement of a membrane. This study was designed to assess the applicability of laser Doppler flowmetry (LDF) in the evaluation of blood perfusion in the mucoperiosteal flap covering the membrane. Five Labrador dogs were initially used inthe study, but one animal was later excluded due to post‐operative problems. Maxillary premolar teeth were extracted and full thickness mucoperiosteal flaps were raised. Following removal of the buccal bone plate, 4 titanium implants were placed on each side. An experimental biodegradable polylactic‐acid membrane was placed over the fixtures on one side to allow for GTR. The mucoperiosteal flap was repositioned and secured with sutures. The contralateral side served as control with no membrane. Blood perfusion was measured in the flaps before surgery, immediately after suturing and at 24, 48 and 72 h postoperatively. A laser Doppler flowmeter was used to assess the blood perfusion. In 3 animals the membrane was exposed within 2 weeks post‐operatively, and in these 3 animals the LDF values were lower on the membrane side than on the control side. The mean LDF value was lower on the membrane side for each of the 4 periods studied. The tindings suggest that LDF can be a valuable method to study blood perfusion of oral mucosal flaps and that there may be a relationship between a reduced relative LDF value and subsequent exposure of the membrane to the oral environment.     

Visuomotor control within a distributed parieto-frontal network

The aim of this functional magnetic resonance imaging study was to investigate differences in visuomotor control with increasing task complexity. Twelve right-handed volunteers were asked to perform their signature under different degrees of visual control: internally generated movement with closed eyes, signing with open eyes, tracking the line of the projected signature forwards, and tracking the line of the projected signature backwards. There was a gradual onset and disappearance of activation within a distributed network. Parietal, lateral and medial frontal brain areas were activated during all conditions, confirming the involvement of a parieto-frontal system. The weight of activation shifted with increasing task complexity. Internally generated movements activated predominantly the inferior parietal lobule and the ventral premotor cortex, as well as the rostral cingulate area, pre-supplementary motor area (pre-SMA) and SMA proper. Opening the eyes reduced SMA and cingulate activation and activated increasingly the occipito-parietal areas with higher task complexity. Visually guided movements produced an activation predominantly in the superior parietal lobule and dorsal premotor cortex. This study bridges human activation studies with the results of neurophysiological studies with monkeys. It confirms a gradual transition of visuomotor control with increasing task complexity within a distributed parieto-frontal network.     

Spatial object representation and its use in planning eye movements

The eye movements we make to look at objects require that the spatial information contained in the objects image on the retina be used to generate a motor command. This process is known as sensorimotor transformation and has been generally addressed using simple point targets. Here, we investigate the sensorimotor transformation involved in planning double saccade sequences directed at one or two objects. Using both visually guided saccades toward stationary objects and objects subjected to intrasaccadic displacements, and memory-guided saccades, we found that the coordinate transformations required to program the second saccade were different for saccades aimed at a new target object and saccades that scanned the same object. While saccades aimed at a new object were updated on the basis of the actual eye position, those that scanned the same object were performed with a fixed amplitude, irrespective of the actual eye position. Our findings demonstrate that different abstract representations of space are used in sensory-to-motor transformations, depending on what action is planned on the objects.     

Control strategies in directing the hand to moving targets

Summary We have evaluated the use of visual information about the movement of a target in two tasks tracking and interceptions — involving multi-joint reaching movements with the arm. Target velocity was either varied in a pseudorandom order (random condition) or was kept constant (predictable condition) across trials. Response latency decreased as target velocity increased in each condition. A simple model that assumes that latency is the sum of two components — the time taken for target motion to be detected, and a fixed processing time — provides a good fit to the data. Results from a step-ramp experiment, in which the target stepped a small distance immediately preceding the onset of the ramp motion, were consistent with this model. The characteristics of the first 100 ms of the response depended on the amount of information about target motion available to the subject. In the tracking task with randomly varied target velocities, the initial changes in hand velocity were largely independent of target velocity. In contrast, when the velocity was predictable the initial hand velocity depended on target velocity. Analogously, the initial changes in the direction of hand motion in the interception task were independent of target velocity in the random condition, but depended on target velocity in the predictable condition. The time course for development of response dependence was estimated by controlling the amount of visual information about target velocity available to the subject before the onset of limb movement. The results suggest that when target velocity was random, hand movement started before visual motion processing was complete. The response was subsequently adjusted after target velocity was computed. Subjects displayed idiosyncratic strategies during the catch-up phase in the tracking task. The peak hand velocity depended on target velocity and was similar for all subjects. The time at which the peak occurred, in contrast, varied substantially among subjects. In the interception task the hand paths were straighter in the predictable than in the random condition. This appeared to be the result of making adjustments in movement direction in the former condition to correct for initially inappropriate responses.     

Five- to six-year results of a prospective clinical trial using the ENDOPORE dental implant and a mandibular overdenture

This report is an update on a group of 46 clinical trial patients who each received 3 free‐standing Endopore® dental implants placed using a 2‐stage surgical approach in the anterior mandible. After an initial healing interval of 10 weeks, the implants were used in each case to retain an overdenture, and at the time of the report. all patients had passed 5 years of continuous function. The 5‐year cumulative "survival" rate based on a life table analysis was 93.4% and this remained unchanged after 6 years. The 5‐year "success rate" was 83.3% when assessed qualitatively with the published criteria of others using a four‐field table analysis categorizing every implant in the study as one of "Grade 1 Success", "survival", "unaccounted for" or "failure". Modified periodontal parameters verified continued peri‐implant soft tissue health. No implant still in function had more than 1.8 mm cumulative bone loss during the first 5 years of function. These results provide clear evidence that Endopore® implants despite their short lengths function at least as well as other dental implant 1 designs used in much longer lengths.     

可生物降解共聚膜修复兔桡骨节段性缺损

目的：探讨在引导性骨再生中生物降解材料聚已内酯（ｐｏｌｙ ε ｃａｐｒｏｌａｃｔｏｎｅ, Ｐ Ｃ Ｌ）和聚乳酸（ｐｏｌｙ ｌａｃｔｉｃ ａｃｉｄ, Ｐ Ｌ Ａ）共聚物的作用及其生物相容性和生物降解性。方法：采用兔桡骨中段１２ ｃｍ节段性骨缺损（保留骨膜）动物模型,共２４只分两组进行对照研究,每组１２只,双侧处理方法相同, Ａ组骨缺损区用膜包绕骨缺损区, Ｂ 组为空白对照。分别于３、６、１２周后处死,进行 Ｘ 线、大体、组织学及电镜观察,检测生化及免疫指标。结果：实验组（ Ａ）骨生长明显优于对照组（ Ｂ）;材料呈明显的降解趋势;血清中 Ｃａ、 Ｐ、 Ｉｇ Ｇ、 Ｉｇ Ｍ 、 Ｃ４值与正常及空白对照均无明显差异。结论：生物降解材料（ Ｐ Ｃ Ｌ／ Ｐ Ｌ Ａ）在引导骨性组织再生中有良好的屏障作用,促进骨缺损的愈合。证明新型骨生物降解材料有良好的生物降解性和生物相容性。     

Internally and externally guided voluntary saccades in unmedicated and medicated schizophrenic patients. Part I. Saccadic velocity

Saccadic eye movements were elicited in 30 schizophrenic patients before and in 17 of these 30 during antipsychotic treatment with neuroleptics, and compared with those of 12 age-matched controls under three different conditions: (a) the gap paradigm, which tests the visually triggered and visually guided saccades; (b) the anti-task paradigm, which tests the internally guided, visually triggered saccades; and (c) the memory paradigm, which tests the internally triggered and guided saccades. Eye movements were recorded by DC electro-oculography, and the peak eye velocities for the different saccades were calculated. We found that antipsychotic treatment with neuroleptics reduces the peak saccadic eye velocity. This effect is larger for internally guided saccades than for externally triggered and guided eye movements. The saccadic velocity of the unmedicated schizophrenic patients did not differ from that of the controls. Since patients with diseases of the basal ganglia primarily show abnormalities of the internally guided and triggered saccades, our findings indicate that neuroleptics influence the oculomotor loop through the basal ganglia and that this loop, by means of neuroleptic influence on the brainstem saccadic burst generator, also influences the peak velocity of the internally guided saccades. This contradicts the current idea of the role of the cortical input to the brainstem saccadic burst generator, which is thought to not be involved in the determination of saccadic velocity. Received: 20 December 1997 / Accepted: 15 September 1998     

Immunocontraceptive activity guided fractionation and characterization of active constituents of neem (Azadirachta indica) seed extracts

A novel approach for immunocontraception by intervention of local cell mediated immunity in the reproductive system by using single intrauterine application of neem oil has been described earlier. The reversible block in fertility was reported to last for 107–180 days in female Wistar rats (Upadhyay et al., 1990. Antifertility effects of neem oil by single intrauterine administration: A novel method of contraception. Proceedings Of The Royal Society Of London B 242, 175–180) and 7–11 months in monkeys (Upadhyay et al., 1994. Long term contraceptive effects of intrauterine neem treatment (IUNT) in bonnet monkeys: An alternative to intrauterine contraceptive devices. Contraception 49, 161–167). The present study, describes the identification and characterization of the biologically active fraction from neem seeds (Azadirachta indica A. Juss. Family Meliaceae), responsible for the above activity in adult female Wistar rats. Initial studies with the mechanically extracted oil and solvent extracts of neem seeds have revealed that the antifertility activity was present in constituents of low to intermediate polarity. A hexane extract of neem seeds was reported to be biologically active (Garg et al., 1994. Comparison of extraction procedures on the immunocontraceptive activity of neem seed extracts. Journal of Ethnopharmacology 22, 87–92). Subsequently, hexane extract was sequentially fractionated through the last active fraction using various separation techniques and tested for antifertility activity at each step. Preparative HPLC was used for isolating individual components of the active fraction in quantities, sufficient for characterization. An analytical HPLC method was developed for standardization of the fraction. The active fraction was identified to be a mixture of six components, which comprises of saturated, mono and di-unsaturated free fatty acids and their methyl esters. Dose response study was performed with the last active fractions. The antifertility activity with the active fraction was reversible in nature and it was completely active until 5% concentration. There was no systemic toxic effect following the administration of the active fraction. This study, for the first time, proposes an active fraction from neem seeds, responsible for long term and reversible blocking of fertility after a single intrauterine administration with high efficacy.     

CT导引注射胶原酶治疗腰椎间盘突出症的临床研究

目的：探讨ＣＴ引导下椎间盘突出的髓核内和突出物表面注射胶原酶治疗椎间盘突出 的效果。方法：对９０例椎间盘突出的患者在ＣＴ导引下分别于椎间盘突出的髓核内和突出物的表达注射胶原酶,所有患者随访３个月￣２年,其中３０例行ＣＴ复查。结果：穿刺成功率１００％,术后随访３个月￣２年,优良率为９５．６％,２９例ＣＴ随访突出物 部分缩小或消失（９６．７％）,本组无并发症。结论”腰椎间盘突出的髓核内和突出物的表面共