Mouthguards: difference in longitudinal dimensional stability between single- and double-laminated fabrication techniques

Abstract –  Though the use of mouthguards (MGs) has increased with the increase in sporting activities, little is known about the influence of their fabrication methods on longitudinal dimensional stability. The objective of this study was to compare the difference in the longitudinal dimensional stability between single and laminated MGs. Single-layer MGs were made from a 4.0 mm thick ethylene vinyl acetate (EVA) sheet and laminated MGs were made from two 2.0 mm thick sheets of EVA. MGs were kept in a 37°C water bath for 60 h, equivalent to the time period of 3-months inter-oral use. MG deformation was analyzed by measuring designated points on the MG border using a profile projector (J-12, Nikon Inc., Tokyo, Japan) before and after the water immersion. A finite-element model was also created to examine the time course of stress accumulation during the sheet forming process using Finite Element software. Longitudinal deformation was smaller in the laminated MGs than in the single-layer MGs in the anterior area ( P  < 0.05). Finite element method (FEM) analysis also showed the largest stress accumulation in the anterior incisal area where deformations were mainly observed. Laminated double layer MGs have advantages over single-layer MGs in terms of longitudinal stability due to lower stress accumulation during the fabrication process.     

Normal stomach wall and gastric cancer: evaluation with high-resolution operative US

Operative ultrasound examinations were performed using a 7.5-MHz transducer during nine operations for advanced gastric cancers and during six for early cancers. Normal stomach wall showed five layers that corresponded to histologic structures. Fourteen of 15 tumors, including nonpalpable early cancers, were localized with ultrasonography. In addition, both depth of penetration and lateral wall extension of the gastric cancers were precisely determined with this technique. Our preliminary results indicate that high-resolution operative ultrasonography may become a diagnostic aid during gastric cancer operations.     

Randomized double-blind study comparing the effectiveness of balloon dilation of the prostate and cystoscopy for the treatment of symptomatic benign prostatic hyperplasia.

We attempted to determine the effectiveness of balloon dilation of the prostate for the treatment of symptomatic benign prostatic hyperplasia (BPH). A total of 33 men with symptomatic BPH signed informed consent to participate in a randomized, double-blind study comparing balloon dilation of the prostate and cystoscopy. Balloon dilation of the prostate and cystoscopy were performed with the patient under intravenous sedation after intraurethral instillation of viscous lidocaine and infiltration of the autonomic neural innervation of the prostate with 1% lidocaine. Efficacy was based upon improvement in Boyarsky symptom scores, increases in peak urinary flow rates and patient global assessment of symptomatic improvement. Efficacy was assessed at 1 and 3 months after treatment. A study nurse blinded to the randomization scheme administered the symptom score questionnaires and supervised the uroflowmetry studies. The study was randomized, since the mean baseline prostate sizes, peak urine flow rates, obstructive and irritative symptoms scores, post-void residual volumes and patient ages were similar in the 2 groups. The patient perceptions of treatment rendered were similar for the 2 treatment groups, confirming that the study was double-blind. The patients undergoing cystoscopy and balloon dilation of the prostate experienced a statistically significant improvement in the mean total symptom scores at 1 and 3 months. The mean total symptom scores after balloon dilation of the prostate and cystoscopy at 1 and 3 months were not significantly different. The mean peak urinary flow rates 1 and 3 months after balloon dilation of the prostate and cystoscopy were not significantly different from the baseline mean peak urinary flow rates. We demonstrate that balloon dilation of the prostate and cystoscopy are equally effective for the treatment of BPH. Since cystoscopy is considered a diagnostic modality, our study suggests that the efficacy previously observed after balloon dilation of the prostate is primarily placebo-related. The study does not support the indication of balloon dilation of the prostate for the treatment of symptomatic BPH.     

Proteolytic Processing Mechanisms in the Biosynthesis of Neuroendocrine Peptides: The Subtilisin-like Proprotein Convertases

The recent discovery of a novel family of precursor processing endoproteases has greatly accelerated progress in understanding the complex mechanisms underlying the maturation of prohormones, neuropeptides, and many other precursor-derived proteins. At least six members of this family have been found thus far in mammalian species, several having alternatively spliced isoforms, and related enzymes have been identified in many invertebrates, including molluscs, insects, nematodes, and coelenterates. The proprotein convertases are all dependent on calcium for activity and all possess highly conserved subtilisin-like domains with the characteristic catalytic triad of this serine protease (ordered Asp, His, and Ser along the polypeptide chain). Two members of this family, PC2(SPC2) and PC1/PC3(SPC3), appear to play a preeminent role in neuroendocrine precursor processing. Both convertases are expressed only in the brain and in the extended neuroendocrine system, while another important family member—furin/PACE (SPC1)—is expressed more ubiquitously, in almost all tissues, and at high levels in liver. SPC2 and SPC3 exhibit acidic pH optima and other properties which enhance their activity in the acidic, calcium-enriched environment of the dense-core secretory granules of the regulated pathway in neuroendocrine cells, while furin has a neutral pH optimum and is localized predominantly to the trans Golgi network where it is retained by a C-terminal transmembrane domain. Furin processes a wide variety of precursors in the constitutive pathway, such as those of growth factors, receptors, coagulation factors, and viral glycoproteins. Recent findings on the processing of proopiomelanocortin, proinsulin, proglucagon, and several other neuroendocrine precursors by SPC2 and SPC3 are discussed, along with information on the structure, properties, evolution, developmental expression, and regulation or the convertases. An inherited defect in the fat/fat mouse which affects the processing of proinsulin, and probably also many other prohormones, due to a point mutation in carboxypeptidase E has recently been identified and has begun to provide new insights into the functional integration of the individual processing steps.     

Endothelium-dependent vasodilation in type II diabetes mellitus

Endothelial dysfunction is a major feature of atherosclerosis and it can also serve as an early atherosclerotic marker. Evaluation and assessment of the endothelial function is important to prevent serious atherosclerotic disease especially myocardial infarction, cerebrovascular disease and renal failure. To evaluate endothelial function we measured endothelium-dependent vasodilation (flow-mediated dilatation: %FMD) of the brachial artery with ultrasound. This method is non-invasive and can be repeatable in order to follow patients individually. Progressive atherosclerosis is often observed in diabetic patients who are not hypertensive. To evaluate the impairment of the endothelial function in type 2 diabetic patients, we examined %FMD in them and compared with hypertensive patients without diabetes and control subjects. We found that type 2 diabetic patients had the same endothelial dysfunction as hypertensive patients without diabetes. %FMD in both diabetic patients and hypertensive patients was lower than in control subjects. Moreover, %FMD of type 2 diabetic patients with hypertension was lower than %FMD of type 2 diabetic patients without hypertension. These finding suggests that endothelial dysfunction develops under the conditions of hypertension and hyperglycemia. Evaluating endothelial function with ultrasound is useful for assessment of atherosclerosis in diabetes.     

Safe jugular and subclavian venipuncture under ultrasonographic guidance

Although jugular and subclavian venipuncture is a valuable technique and frequently utilized, blind venipuncture is at times associated with complications such as arterial puncture, pneumothorax, and malpositioning of catheters. We performed venipuncture under the guidance of high-resolution real-time ultrasonography, and these catheter-related complications were prevented. Jugular, subclavian and innominate veins and arteries, the pleura, and the lung are all delineated by supraclavicular and subclavicular scanning, and the needle and catheter can also be visualized. Ultrasonographically-assisted jugular and subclavian venipuncture is a simple and helpful procedure to carry out safe venipuncture. This method is particularly recommended for less experienced physicians and for more accurate puncture in patients with distorted cervical or subclavicular anatomic characteristics.