A neuronal mechanism of propofol-induced central respiratory depression in newborn rats

The neural mechanisms of propofol-induced central respiratory depression remain poorly understood. In the present study, we studied these mechanisms and the involvement of gamma-aminobutyric acid (GABA)A receptors in propofol-induced central respiratory depression. The brainstem and the cervical spinal cord of 1- to 4-day-old rats were isolated, and preparations were maintained in vitro with oxygenated artificial cerebrospinal fluid. Rhythmic inspiratory burst activity was recorded from the C4 spinal ventral root. The activity of respiratory neurons in the ventrolateral medulla was recorded using a perforated patch-clamp technique. We found that bath-applied propofol decreased C4 inspiratory burst rate, which could be reversed by the administration of a GABAA antagonist, bicuculline. Propofol caused resting membrane potentials to hyperpolarize and suppressed the firing of action potentials in preinspiratory and expiratory neurons. In contrast, propofol had little effect on resting membrane potentials and action potential firing in inspiratory neurons. Our findings suggest that the depressive effects of propofol are, at least in part, mediated by the agonistic action of propofol on GABAA receptors. It is likely that the GABAA receptor-mediated hyperpolarization of preinspiratory neurons serves as the neuronal basis of propofol-induced respiratory depression in the newborn rat.     

Halothane and propofol modulation of gamma-aminobutyric acidA receptor single-channel currents

Halothane and propofol enhance the activity of the gamma-aminobutyric acid (GABA) system, which is one of the most important systems in the mechanism of anesthesia. To determine whether halothane and propofol enhance GABAergic responses by the same mechanism, we performed single-channel patch-clamp experiments with rat cortical neurons in primary culture. Each of the open-time and closed-time distributions of GABA(A) receptor single channels was expressed by a sum of fast and slow time constants. Neither halothane nor propofol changed the single-channel conductance. Halothane increased the probability of the channel being open via a prolongation of the slow phase of open time, whereas propofol increased the channel open probability via a shortening of the slow phase of closed time. Thus, although both halothane and propofol augmented the channel open probability, thereby causing an increase in charge transfer during inhibitory transmitter action, they acted by different mechanisms.     

Systematic traction techniques in minimal-access pediatric cardiac surgery

Minimal-access pediatric cardiac surgery is now common in the treatment of simple congenital heart defects. However, methods of securing a good, unobstructed view for surgery and the difficulties of working in a deep, narrow field jeopardize safety in surgical procedures, especially for less experienced surgeons have been described. Our systematic, step-by-step traction techniques on the skin, the pericardium, the right atrial appendage, the aortic root, both venae cavae, and the free wall of the right ventricular outflow, using a mechanical retractor and traction sutures, facilitate surgical field exposure and the achievement of safety. As described below, our procedures are simple, allow direct inspection, and assist those working toward technical mastery.     

Prosthetic alignment and sizing in computer-assisted total knee arthroplasty

We implanted 60 posterior stabilized total knee prostheses (P.F.C. Sigma, DePuy, Warsaw, USA). In 30 cases, we used a CT-free navigation system (Vector Vision, Brain LAB, Heimstetten, Germany), and in 30 matched-paired controls, we used a conventional manual implantation. We compared postoperative long-leg radiographs in the two groups. The results revealed a significant difference in favor of navigation. In addition, we compared the preoperative anteroposterior dimension of the femoral condyle with the postoperative value. While there were no significant differences in the preoperative anteroposterior dimension of the femoral condyle between the two groups, the postoperative value in the navigation group was significantly larger than that of the preoperative value. Therefore, surgeons using navigation systems should guard against the possibility of oversizing when determining the size of the femoral component.

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Résumé Nous avons implanté 60 prothèses totales postéro-stabilisées du genou (P.F.C. Sigma, DePuy). Dans 30 cas nous avons utilisé un système de navigation sans scanner (Vector vision R, Laboratoire du Cerveau, Heimstetten, Allemagne) et dans 30 contrôles appairés nous avons utilisé une implantation manuelle habituelle. Nous avons comparé les grandes radiographies postopératoires des membres inférieurs dans les deux groupes. Les résultats ont révélé une différence notable en faveur de la navigation. De plus nous avons comparé la dimension antéro-postérieure du condyle fémoral avant lintervention avec la valeur postopératoire. Tandis quil ny avait pas de différence notable dans la dimension antéro-postérieure préopératoire du condyle fémoral entre les deux groupes, la valeur postopératoire dans le groupe de la navigation était nettement plus grande que la valeur préopératoire. Par conséquent les chirurgiens qui utilisent des systèmes de navigation doivent prendre garde à ne pas implanter un composant fémoral sur-dimensionné.

     

Treatment of spontaneous intracranial hypotension secondary to C-2 meningeal cyst by surgical packing--case report

A 41-year-old man presented with progressive worsening of postural headache. Computed tomography (CT) showed bilateral subdural hematomas without prior history of trauma. The diagnosis was spontaneous intracranial hypotension (SIH). Conservative treatment with oral steroids failed to prevent gradual deterioration of the patient's consciousness. CT myelography revealed massive cerebrospinal fluid (CSF) leakage between the C-1 and C-2 levels. The leak was repaired surgically via a laminectomy. A cyst, thought to be a meningeal cyst, was discovered adjacent to the right C-2 nerve root, and CSF was seen seeping out from around the cyst after a Valsalva maneuver. The presumed dural defect of the cyst was sealed by packing with muscle fragments and fibrin glue. The symptoms disappeared soon after surgery. He was discharged 1 month after surgery without deficits. Most SIH cases are benign and can be managed conservatively, or by the epidural blood patch method. Surgery is more invasive than the epidural blood patch method, but should be performed in patients with a high cervical lesion and massive CSF leakage.     

The trend and susceptibility to antibacterial agents of enterococcus species from urinary tract infections

OBJECTIVE: To determine the extent of drug-resistance among Enterococcus species we investigated in vitro experiments. METHODS: Studies were carried out on pure cultured of enterococci isolated from 8,575 urine specimens between 1990 and 2002. We had determined test strains to three kinds of species, which posses the urinary pathogenesis. Both an EF-agars and an ADH decarboxylase test performed the identification and speciation of the strains of enterococci. In vitro drug-susceptibility tests of enterococci were performed against the following antibiotics: ampicillin (ABPC), cefpirome (CPR), cefozopran (CZOP), imipenem/cilastatin (IPM/CS), minocycline (MINO), levofloxacin (LVFX), vancomycin (VCM), sulfamethoxazone/trimethoprim (ST), by employing the method for dilution antimicrobial susceptibility tests for bacteria that grow aerobically recommended by Japan Society of Chemotherapy. These drug-susceptibilities were shown susceptible, intermittent and resistant in according to National Committee for Clinical Laboratory Standards (M100-S12). RESULTS: The most common species isolated was E. faecalis (84.4%), followed by E. faecium (9.9%) and E. avium (5.6%). In E. faecium and E. avium, the sensitivity to ABPC has tended to improve from 1999. This tendency inverse correlated to decreasing dosage of PCs. There was much difference of resistant rate to IPM/CS between each species, and no correlation to used dosage of CBPs. The rate of resistance to MINO did not change during this period. 60% of E. faecalis had sensitivity to LVFX and the rate did not change during this period. In E. faecium, whose resistant rate to LVFX was 90%, the sensitivity has been improved to over 25% from 2001. The improved tendency of E. faecium to LVFX has inverse proportion to decreasing dosage of NQs. With the exception of a little bit VRE (VCM resistant Enterococci), almost of them had sensitivity to VCM. CONCLUSION: The emergence of enterococci with alarming rates of resistance concomitantly to multi-drugs highlights the need for a more rational and restricted use of antimicrobials, in order to minimize the selection and spread of such strains. An early detection of these problem pathogens is also important for preventing any treatment failures.     

Effect of follow-up intervention of toothbrushing on periodontal health in workplace dental examination

This study examined the effect of follow-up intervention on periodontal health of workers on the basis of clinical assessment and a laboratory test. Toothbrushing instruction was given to 26 workers (41.4 +/- 7.8 yr of age). In the experimental group (EG), 13 workers received re-instruction and reminder messages after the initial intervention. The remaining 13 workers, who served as a control group (CG), underwent no follow-up. Brushing skill was assessed on the basis of plaque scores for the whole mouth (Plaque Control Record, PCR) and for eight representative teeth (Plaque Index, PLI). Periodontal health was evaluated with the Community Periodontal Index (CPI). Assessment of gingival inflammation (Modified Gingival Index, MGI), measurements of pocket depth (PD) and attachment level (AL), and collection of gingival crevicular fluid (GCF) were performed at the representative sites. Aspartate aminotransferase (AST) in GCF was determined. Periodontal assessments were conducted prior to and three months after the first examination. Data were analyzed on site- and subject-bases. Both groups exhibited a significant reduction in PLI and MGI. PCR and PD significantly decreased exclusively in the EG. No significant change was observed in the CPI or AL. A significant reduction in PD in shallow pockets (PD<=3 mm) and declines in AL and AST in deeper pockets (PD>=4 mm) were detected in EG. A reduction in PD in deeper pockets was significant in the CG. These results indicate that intervention with follow-up is more effective with respect to periodontal health of workers than is a single intervention; moreover, the laboratory GCF test could be employed to ascertain the outcome of behavioral change.     

Impact of health education and screening over all-cause mortality in Japan: evidence from a cohort study during 1984-2002

BACKGROUND: Health education and screening are two components of preventive health services in Japan since 1983. This study investigated their relationships with all-cause mortality as they are studied insufficiently in Hokkaido, Japan. METHODS: This study enrolled 1,532 men and 1,653 women aged 40-97 years from 1,702 randomly selected households of 60 areas during 1984-1985 and followed them until 2002. At baseline survey, staffs of 45 health centers collected sociodemographic, medical, behavioral, and dietary information including health education and screening from study subjects with informed consent. RESULTS: For men, age-adjusted Cox proportional hazard model indicated lower mortality for those who received health education (RR = 0.76, P < 0.01) and screening (RR = 0.83, P < 0.05) than those who did not. Health education showed lower mortality even after adjusting for many variables. Similarly for women, health education (RR = 0.66, P < 0.01) and screening (RR = 0.64, P < 0.001) revealed lower age-adjusted mortality. Almost similar results were found for both services when models were adjusted for many variables and when the deaths including lost to follow-up cases of the first 4 years of baseline survey are excluded. CONCLUSIONS: This study shows protective effects of health education and screening over all-cause mortality for both sexes. However, further studies are needed to confirm the results.