Comparative virulence of periodontopathogens in a mouse abscess model

OBJECTIVE(S): This report compares the virulence of selected strains of P. gingivalis, A. actinomycetemcomitans, C. rectus, F. nucleatum and T. denticola in a murine model as a measure of pathogenic potential of these oral microorganisms. The characteristics of the tissue destruction associated with these monoinfections were then related to a potential model for bacterial synergism in progressing periodontitis. DESIGN AND METHODS: All bacterial strains were grown to mid-logarithmic to early stationary growth phase, harvested and used at various doses to challenge BALBlc normal and BALB/c dexamethasone (DEX) treated mice to mimic a neutrophil dysfunction. The characteristics of tissue destruction, and overt tissue destructive capacity of these species were examined as a function of challenge dose and time. OUTCOME MEASURES The mice were examined for an interval of approximately 15 days post-challenge and the presencelabsence of lesions, localized or generalized nature of the lesion (including size in mm), and lethality of the infection were assessed. RESULTS: Comparison of the virulence of the various P. gingivalis strains related to lethality and lesion size associated with destruction of the connective tissue, indicated a virulence capacity of P. gingivalis strains 53977>W50 = T22>3079>33277>381. C. rectus elicited localized necrotic lesions which were limited to the epithelial layers of the skin. The size of the lesions also indicated a graded difference in virulence, such that C. rectus strains 234>576>>33238. A. actinomycetemcornitans caused the formation of classic localized abscesses with a PMN infiltrate and inflammatory exudates. Although, each of the A. actinornyceterncomitans strains exhibited a similar virulence pattern in this murine model, A. actinomycetemcomitans serotype b representative strains were potentially more pathogenic with a virulence capacity of 3113D-N = 3975A>jP2>Y4>29523>33384. Both C. rectus and A. actinomycetemcomitans strains showed clear evidence that recent clinical isolates were more virulent than laboratory strains. Challenge with F. nucleatum resulted in tissue destructive responses which were different from those observed with the other strains used in this study. A rapid onset of dose-dependent lesion development, related to the formation of either closed abscesses or open lesions, was observed with F. nucleaturn. Tissue involvement was also greater at lower F. nucleaturn doses when compared to the other bacteria. F. nucleaturn challenge of DEX-treated mice resulted in a shift to open lesions. T. denticola appeared to be more tissue invasive than the other species examined in this study. Challenge of mice with T. denticola resulted in involvement of multiple tissues, including epithelial and connective tissues, as well as appearing to invade muscle layers and deeper tissues. In addition to invading deeper tissues, the resulting lesions took considerably longer to resolve. In the DEX-treated mice (neutrophil depleted), P. gingivalis, C. rectus, and A. actinomycetemcomitans were significantly more virulent. In contrast, while DEX treatment altered the characteristics of lesions caused by F. nucleatum, the extent of lesions produced by F. nucleatum and T. denticola was not substantially enhanced. CONCLUSIONS: The results obtained from this study suggest that different microorganisms have the ability to provide individual pathologies which may act in an additivelsynergistic fashion contributing to the tissue destruction noted in periodontitis.     

Trimethylaminuria (fish-odour syndrome) and oral malodour

A small but important percentage of oral malodour cases have an extra-oral aetiology and certain of these fall into the category of 'blood-borne halitosis'. Odoriferous substances generated within the body and transported to the lungs via the circulatory system may, if sufficiently volatile, leave with the exhaled air and impart a foetid odour to the breath. The aliphatic tertiary amine, trimethylamine, is such a volatile compound that is generated to excess in patients with a metabolic disorder known as trimethylaminuria (fish-odour syndrome). This article highlights this condition and draws attention to its potential role in the causation of recalcitrant oral malodour.     

A broken heart: a stretch too far: an overview of mouse models with mutations in stretch-sensor components

With every heartbeat the heart must contract and relax. This seemingly trivial process critically needs tight control of contraction and relaxation phases, and extremely efficient coordination between these two phases to control blood flow and maintain cardiac homeostasis. To achieve this, specialized sensors are required to detect the inherent repeatedly changing environment and needs. One sensor is a stretch-sensor that monitors the filling of the ventricles. Its molecular identity and localization are only partly understood. Here we give a synopsis of the genetic models that leap into our understanding of stretch-sensors. We focus on the widely acknowledged sarcomeric sensor at the Z-disc and the costamere sensor at the sarcolemma. Recently, several novel components of both sensors were discovered. Given that these two sensors seem physically connected, it is likely that these two models are not mutually exclusive and might even communicate. We describe briefly how candidate and known proteins within these sensors receive and transduce mechanical signals in the cardiomyocyte that lead to changes in gene expression underlying homeostasis and its restoration in the heart. Emphasis is placed on the putative link between altered stretch-sensor function and heart failure observed in different genetic mouse models of stretch-sensor components.     

Caesarean section as preferred mode of delivery in term breech presentations is not a realistic option in rural Zimbabwe

We undertook this retrospective cross-sectional study in order to establish the outcome of 510 singleton breech presentations at term in seven district hospitals in rural Matabeleland-North Province, Zimbabwe. We also studied the mortality for 1093 caesarean sections (CS), in order to decide if CS should be the preferred option for breech births. The perinatal mortality rate in singleton breech presentation (BrPNMR) was very high:166/1000. Between the hospitals the BrPNMR ranged from 66 to 225/1000 (P = 0.04). Although the outcome was better for CS than for vaginal delivery (odds ratio = 5.4, P = 0.0005), there was no correlation between the BrPNMR and the CS rate. Results indicate that closer monitoring of these high-risk pregnancies by the most senior staff would be more effective than increasing the number of CS performed. An external cephalic version at term could also reduce breech-related mortality. Symphysiotomy is a life-saving emergency intervention when the head is trapped. Increasing the number of CS should be strongly discouraged since the case fatality rate in this rural setting was found to be very high: 18/1093 women died after CS (for any indication) within 42 days after the operation (1, 6%); 15 within 24 h. Haemorrhage was the major cause of death.     

Intrauterine adhesions as a risk factor for failed first-trimester pregnancy termination

BACKGROUND: Risk factors for failed first-trimester surgical abortion include endometrial distortion caused by leiomyomas, uterine anomalies and malposition and cervical stenosis. This report introduces intrauterine adhesions as an additional risk factor. CASE: A multiparous woman presented for pregnancy termination at 6 weeks' gestation. Three suction-curettage attempts failed to remove what appeared to be an intrauterine pregnancy. Rising beta-hCG levels and concern for an interstitial ectopic pregnancy prompted a diagnostic laparoscopy and exploratory laparotomy without the identification of an ectopic pregnancy. After methotrexate treatment failed, the patient underwent ultrasound-guided hysteroscopy and suction curettage using a cannula with a whistle-cut aperture for the successful removal of a pregnancy implanted behind intrauterine adhesions. CONCLUSION: Intrauterine adhesions are a cause of failed surgical abortion. Ultrasound-guided hysteroscopy may be required for diagnosis.     

基于Linux操作系统嵌入式心电记录仪的设计

介绍了一种基于ARM9和Linux操作系统的心电记录仪。该记录仪以32位低功耗ARM9微处理器S3C2410X为核心,在其上移植了Linux操作系统,利用轻量级的图形用户界面支持系统MiniGUI进行软件界面开发,实现了心电信号的实时采集显示、心率计算、心律失常分析并利用GPRS进行心律失常报警等功能。为了检验系统的性能,使用心电信号模拟发生器(MPS450多参数模拟器)产生各种类型的心电信号,用该记录仪进行采集分析,记录仪分析获得的心率值与模拟发生器产生的心率值基本相同,当模拟发生器产生异常心电时,记录仪通过GPRS发出报警信息,同时在主界面上显示心律失常类型。实验结果表明,该记录仪能实时采集显示心电波形,当发生心动过速、心动过缓、心律不齐、漏搏、停搏时,能通过GPRS进行实时报警,实现了心电信号的无线远程实时监护。     

A randomized double-blinded clinical trial to evaluate the safety and efficacy of a novel superelastic nickel–titanium spinal rod in adolescent idiopathic scoliosis: 5-year follow-up

Purpose

To evaluate the safety and efficacy of a superelastic shape-memory alloy (SNT) rod used in the treatment of adolescent idiopathic scoliosis (AIS).

Methods

AIS Patients with Lenke 1 curves undergoing fusion surgery were randomized (1:1) at the time of surgery to receive either the SNT or a conventional titanium alloy (CTA) rod. Radiographs were obtained preoperatively and postoperatively up to 5 years of follow-up. Parameters assessed included coronal and sagittal Cobb angles, and overall truncal and shoulder balance. Sagittal profiles were subcategorized into Types A (<20°), B (20–40°), and C (>40°).

Results

Twenty-four patients with mean age of 15 years were recruited. A total of 87.0% of subjects were followed up till postoperative 5 years, but all patients had minimum 2 years of follow-up. The fulcrum-bending correction index for the SNT group was 113% at postoperative day 4 and 127% at half-year, while the CTA group was 112% at postoperative day 4 and only 106% at half-year. In terms of sagittal profile, the SNT group moved toward type B profile at half-year follow-up with a mean correction of 7.6°, while no significant change was observed in the CTA group (?0.7°). Nickel levels remained normal, and there were no complications.

Conclusions

This is the first randomized clinical trial of a novel SNT rod for treating patients with AIS, noting it to be safe and has potential to gradually correct scoliosis over time. This study serves as a pilot and platform to properly power future large-scale studies to demonstrate efficacy and superiority.