Biomedical subjects
M Rosen
Publications and source records attributed to M Rosen.
Peripheral mechanical loading and the mechanism of the tremor of chronic alcoholism.
The tremor of chronic alcoholism, although clinically similar to essential tremor, has been considered a distinct syndrome. Its underlying mechanism was analyzed in five patients (none in the acute stages of alcohol withdrawal) hospitalized in an alcohol detoxification program. All five patients performed tracking tasks in which they pursued a linearly moving "target" light with a response light that they controlled by flexion-extension activity of the wrist. Stationary and dynamic targets were used with both isometric and unconstrained wrist mechanical interfaces. Frequency, torque, and displacement tremor characteristics were examined under varying inertial loading or isometric voluntary torque conditions. Two simultaneous tremor components were present in all patients: a prominent 4- to 7-Hz low-frequency peak and a smaller-amplitude 9.4- to 9.6-Hz high-frequency peak. As the inertia of the hand was augmented during unconstrained tasks, the low-frequency peak decreased, while the high-frequency peak was unaffected. As required voluntary effort was increased during isometric testing, the amplitude of the low-frequency peak increased. These findings suggest that the low-frequency peak represents the significant pathologic component of the tremor of chronic alcoholism and that it has a biomechanical reflex mechanism similar to that of the lower-amplitude normal physiologic tremor.
[Backache and the anesthetist].
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The interaction of platinum antitumour drugs with mouse liver mitochondria.
A study was undertaken to determine if cis-DDP and its second generation derivatives produced effects on mouse liver mitochondria, and if any of the observed effects could be correlated with the nephrotoxicity of the drugs. Although changes were observed in mitochondrial morphology, enzyme activity, Ca2+ influx, terbium binding and surface potential, no specific effect was correlated with nephrotoxicity. cis-DDP produced marked changes in mitochondrial morphology; electron probe analysis showed binding of the drug to the mitochondria. Inhibition of complex I and II activity of the respiratory chain and an ionic-strength-dependent effect on Tb3+ (a Ca2+ analogue) fluorescence were observed. The non-nephrotoxic derivatives, CHIP and tetraplatin, also produced significant changes in morphology. Treatment with these derivatives also produced decreases in mitochondrial enzyme activity, but the effect on terbium binding had an ionic-strength dependence which was inverse to that observed with cis-DDP. The tetravalent compounds also had a notable effect on mitochondrial surface potential. Carboplatin had an effect on morphology and Ca2+ influx and it inhibited the respiratory enzymes, although in a manner different from that observed with cis-DDP. Carboplatin had a minimal effect on terbium binding. It is evident that if the platinum drugs enter a cell to exert their action at the nuclear level, they will also depress mitochondrial function. The observed effects did not correlate with nephrotoxicity but, since all four compounds significantly altered mitochondrial structure and function, they may be related to the cytotoxicity of the drug.
The effect of impression technique and multiple pours on accuracy of stone models.
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Effects of intrathecal and intraperitoneal morphine on gastrointestinal motility in the rat.
A method has been developed to compare gastrointestinal (GI) transit time after intrathecal (i.t.) drug injection in the rat. Each animal had a catheter implanted in the i.t. space. Eight rats, on three separate occasions, had either i.t. morphine 16 micrograms kg-1 (in 50 microliters) or intraperitoneal (i.p.) morphine (0.1%) 7.5 mg kg-1 or i.t. saline (50 microliters). The dose of morphine was the ED50 for analgesia by each route. After halothane and oxygen anaesthesia, 10 steel balls and 1 ml of contrast medium were placed into the stomach, the whole procedure being completed within 5 min. Radiographs were taken at 5 min, 3, 6 and 24 h, and the number of balls in the stomach, small and large intestine were counted. The inhibitory effect of i.t. or i.p. morphine on gut motility caused an equally significant delay at 6 h. In a separate series of eight rats the delay by i.t. morphine could be completely antagonized by i.p. naloxone 1 mg kg-1. Thus, i.t. morphine in an analgesic dose even though smaller than the i.p. dose has a similar inhibitory effect on GI tract motility in the rat. This method would enable comparisons on GI transit to be made between a variety of intrathecally administered drugs.
Results of radiotherapy for localised prostatic carcinoma treated at the Prince of Wales Hospital, Sydney.
Between 1980 and 1986 a total of 218 patients with localised prostatic carcinoma received radical pelvic radiotherapy at The Prince of Wales Hospital, Sydney. The mean follow-up time was 4.6 years. The five-year actuarial overall survival rate was 63% (death from all causes) and the five-year cancer-specific survival rate was 73% (death from or with prostate cancer). The overall survival was significantly worse with more advanced clinical stage of the disease (P = 0.003) and with poor histological differentiation of the tumour (P = 0.001). The five-year actuarial rate for local control of tumour in the pelvis was 84%. Late treatment-related complications (occurring or persisting beyond six months) were mild or moderate and the majority settled with conservative management. Only five patients experienced severe complications (necessitating surgical treatment). Of 42 patients with normal potency documented before radiotherapy who were not subsequently hormonally manipulated 23 (55%) retained potency at two years. These results for definitive radiotherapy for localised prostatic carcinoma indicate good local control with minimal morbidity and compare favourably with other published results.
Glutethimide treatment of disabling action tremor in patients with multiple sclerosis and traumatic brain injury.
Glutethimide has been used to control essential tremor. Its efficacy in the treatment of disabling cerebellar and rubral tremor was assessed in an open study of six patients with multiple sclerosis and two patients with traumatic brain injury. Functional and quantitative tremor severity was assessed before treatment and 7 to 14 days after a stable dose was achieved. Six of eight patients exhibited visible functional benefit from treatment with glutethimide; abstract testing results correlated well with functional status in most cases. Four patients chose to continue to receive medication. Controlled trials of glutethimide to compare its efficacy with that of other medications used in the treatment of action tremor are indicated.
Duplication of the upstream regulatory sequences increases the transformation potential of human papillomavirus type 11.
Infections with certain types of papillomaviruses, e.g., human papillomavirus type 16 (HPV-16), often progress to cancer. Malignant lesions associated with the closely related HPV-11 are extremely rare. Additionally, HPV-11 DNA, unlike HPV-16, does not normally transform cells in vitro. We determined that HPV-11 DNA was able to transform baby rat kidney cells in a ras-dependent focus assay when the upstream regulatory region (URR) was present in two copies. Addition of a second HPV-11 URR or an HPV-16 URR was equally effective and was position and orientation independent. The transformation was enhanced by dexamethasone. On passage the HPV-11 genome was not retained at a detectable level. This analysis supports isolated observations in vivo that duplications of regulatory sequences in HPV-11 increase the transformation potential of this virus type.
Influence of mixing disinfectant solutions into alginate on working time and accuracy.
Possible transfer of pathogens from dental surgery to dental laboratory is of concern to the profession. This study investigates changes in the working time and accuracy of an alginate impression material when mixed with solutions of selected disinfectants rather than water. The results indicate that certain disinfectant solutions, when used as a water substitute, do not modify the working time of the alginate investigated beyond acceptable limits and have no significant effect on the dimensional accuracy of that material. The use of a 0.2 per cent solution of chlorhexidene gluconate is recommended as a water substitute for the alginate investigated.
Disinfection of alginate impression material using disinfectants as mixing and soak solutions.
Disinfectant solutions were used as water substitutes in the preparation of specimens of alginate impression material. Chlorhexidine gluconate and sodium peroxysulphate solutions were tested. The alginate specimens were infected by sucking, subsequently disinfected in the solution used in the alginate preparation, and then tested for infectivity by 24-h incubation in thioglycollate broth. Bacterial growth was measured by changes in turbidity using a turbidimeter. The results indicate that chlorhexidine gluconate is an effective alginate disinfectant, when it is used as the liquid for alginate preparation and post-setting disinfection solution.
Reversal of benzodiazepine sedation with the antagonist flumazenil.
The effectiveness of the benzodiazepine antagonist, flumazenil, was evaluated in a randomized double-blind clinical study in which diazepam 0.2 mg kg-1 or midazolam 0.1 mg kg-1 was used for i.v. sedation. We studied 120 day-case patients undergoing gastroscopy and treated with either flumazenil 0.1-2 mg or placebo after the procedure. Psychometric assessment of four aspects of recovery over a 3-h period showed that flumazenil attenuated the sedative effects of the benzodiazepines, but did not antagonize the sedation completely. For patients sedated with diazepam, there was a significant effect of flumazenil on speed of motor co-ordination after 90 min (P less than 0.01), and for those given midazolam a similar effect was found at 20 min (P less than 0.01). However, after 3 h all four groups of patients had not returned to baseline performance in accuracy of motor co-ordination (P less than 0.01) and cortical arousal (P less than 0.05), and the two groups sedated with diazepam still displayed memory deficits (P less than 0.05). Flumazenil did not attenuate the subjective experience of sedation as measured by visual analogue scales. These results indicate that sedation is multidimensional, differentially affecting the hierarchy of cognitive functions. In day-cases, antagonism of benzodiazepine sedation with flumazenil would not hasten the safe discharge of patients.
Gastric emptying and small bowel transit in male volunteers after i.m. ketorolac and morphine.
Ten male volunteers were studied in a randomized, double-blind crossover trial. Each received ketorolac tromethamine 30 mg and morphine sulphate 10 mg i.m. at an interval of 2 weeks. After a standard radiolabelled meal, gastric emptying half-time (GE) and small intestinal transit time (SIT) were measured using a gamma camera. Small intestinal transit time was measured also from end-tidal breath hydrogen (ETH), and overall gastrointestinal motility by time to first flatus (TFF). Mean GE, SIT and TFF were significantly prolonged by morphine compared with ketorolac (P less than 0.03); ETH was prolonged also, but the difference was not significant. There were no significant correlations between SIT, ETH and TFF. Most subjects reported adverse effects after morphine, but only one after ketorolac.
Propofol in short gynaecological procedures. Comparison of recovery over 2 days after anaesthesia with propofol or thiopentone as sole anaesthetic agent.
Recovery was assessed over 48 hours after anaesthesia with propofol or thiopentone as sole anaesthetic agent in 36 unpremedicated gynaecological patients. Immediate recovery, as measured by the Steward scale, was shown to be quicker for the patients given propofol. At one hour postoperatively the thiopentone group showed impaired visual-motor coordination on the aiming test (p less than 0.01) and dexterity task (p less than 0.05), and a slowing of reaction time (p less than 0.01). Patients given propofol showed only an increase in reaction time (p less than 0.05). By 2 hours the thiopentone group showed impairment only in the aiming task (p less than 0.05). No further significant impairment was detected at 4, 24 or 48 hours. However, patients reported symptoms throughout the 48 hours indicative of residual drug effects. There was a substantial practice effect with some tests which may have obscured impairment. It can be argued therefore that the better recovery profile after propofol is still evident at 24 hours.
A survey of concurrent drug therapy among day unit patients.
In order to assess the reliability of drug information supplied by day-stay cases, 85 consecutive patients were interviewed. A comparison of the interview answers with the details previously volunteered during the admission procedure showed an increase of 80% in the information given by the patient. While the detailed interviewing technique is time-consuming and may not be infallible, this substantial increase in information highlights problems in the current routine.
Bond strength of glass ionomer cement to composite resin.
This report assesses the effect of acid etching, acid etching plus bonding adhesive and bonding adhesive only, on the bond strength of one light curing and two chemical curing glass ionomer cements (GICs) to composite resin. Bonded specimens were fractured using a three point flexural jig. The only bond obtained with the chemically curing cements was after acid etching and bonding adhesive application. The light curing cements produced a bond with all treatments but a true cohesive fracture was only obtained after application of the dentine primer and bonding adhesive of the particular bonding system employed. It is recommended that a bonding adhesive be applied after acid etching chemically curing GICs in order to achieve a bond to composite resin. The light curing GIC should not be etched with phosphoric acid and is the material of choice as it is both stronger and less technique sensitive than the chemically curing GICs. Manufacturers' instructions may not always give the best results.
Effect of impression technique and multiple pours on accuracy of stone models.
The number of accurate repour models obtainable from a single impression is of clinical importance. This study was designed to compare the accuracy of initial and repour models obtained from an impression recorded in a hydrophilic addition curing silicone and to determine whether or not this accuracy is affected by the impression technique employed and whether any interaction between impression techniques and levels of pour existed. The laminated and putty wash plus spacer techniques were employed. Six impressions were recorded of a brass master model with each technique. Improved stone models were poured after 2 hours and then repoured in the same impression at 3, 4, 5 and 6 hours. Thus, 30 models were poured with each impression technique. Using a reflex microscope, measurements between two fixed points on the brass model were taken and compared with similar measurements obtained from the stone models. The analysis of variance indicates that no significant difference exists between impression techniques (p greater than 0.05) and between the first pour and first repour model (p greater than 0.05). With the material tested, this study indicates that the laminated and putty wash plus spacer techniques both give accurate impressions and that only two accurate models can be poured.