Resorption rate and biocompatibility characteristics of two polyester ventilation tubes in a guinea pig model

OBJECTIVES: Determine the resorption rate and biocompatibility characteristics of 2 polyester ventilation tubes, and to determine whether soap and water exposure accelerates polyester tube degradation. STUDY DESIGN AND SETTING: 50/50 poly (D, L-lactide-co-glycolide; PLGA-50) and poly (L-lactide; PLA) polymers were placed into the tympanic membranes of Hartley pigmented guinea pigs. Integrity of the tubes was determined by weekly otoscopic examination. Biocompatibility was assessed by comparing auditory brainstem response (ABR) thresholds and by examining tympanic membrane changes following tube resorption. Shah minigrommet ventilation tubes were used as controls. In the second portion of this study, implanted PLGA-50 and PLA tubes were exposed weekly to a mixture of soap and water (1:5) until complete resorption was observed. Biocompatibility was assessed by periodic ABR testing and tympanic membrane examination. RESULTS: The PLA tubes remained in the tympanic membrane for a longer period (63.2 +/- 19.3 days) than the PLGA-50 (18.8 +/- 8.1 days). The tympanic membrane and resorbable tube interface demonstrated equivalent findings for auditory thresholds and tissue histopathology at the implant site compared to nonresorbable controls. The resorption behavior was not altered by exposure to soap and water. Tympanic membranes of all animals following tube degradation and soap water exposure were intact with minimal scarring and no signs of persistent foreign body response. The histological analysis showed that implantation of resorbable tubes was not accompanied by secondary infection with otorrhea through the tube, did not result in a permanent perforation or dislocation of the tube into the middle ear cavity, and was not followed by excess tympanosclerosis or localized or diffuse membrane atrophy. CONCLUSIONS AND SIGNIFICANCE: Resorbable polyester pressure equalization tubes demonstrate predictable resorption behavior and similar biocompatibility characteristics when compared with nonresorbable Shah minigrommet ventilation tubes. Exposure to soap water does not accelerate polyester tube degradation nor change the host tissue response during the indwelling period or after complete resorption. The data suggests that resorbable ventilation tubes are substantially equivalent to other FDA-approved tympanostomy devices with regard to safety and biocompatibility in the guinea pig model examined and may provide improved clinical performance by combining this approach with sustained release technology. EBM RATING: B-2.     

Anatomic and spiral computed tomographic study of the genial tubercles for genioglossus advancement.

OBJECTIVE: To measure and compare Chinese mandibular genial tubercles measured anatomically and with computed tomography (CT). STUDY DESIGN AND SETTING: Spiral CT scans were taken of 40 adult human skulls; the superior genial spines were measured using anatomic and CT methods. RESULTS: The height and width of the superior genial spines, mandible thickness, and distance from the menton to the inferior and superior margins of the superior genial spines were 5.82 +/- 0.71, 6.98 +/- 1.35, 11.95 +/- 1.59, 11.08 +/- 2.05, and 16.91 +/- 2.30 mm from anatomic measurements and 6.17 +/- 0.71, 7.01 +/- 1.13, 12.19 +/- 1.64, 10.41 +/- 1.55, and 15.73 +/- 2.12 mm using spiral CT, respectively. The anatomic and CT measurements were correlated. CONCLUSION: Spiral CT of the genial tubercles can help locate the osteotomy in genioglossus advancement. SIGNIFICANCE: This study acquired reference data on Chinese genial tubercles demonstrating that CT measurements of the genial tubercles reflect their anatomy, which should allow accurately locate the osteotomy.     

后装机出源阻力大故障分析及维修

从机械和电路两方面分析了 KLHZ-001型后装机出源阻力大的原因 ,并分别阐述了维修办法.     

眼内异物合并外伤性白内障的联合手术治疗：附88例分析

眼内异物合并外伤性白内障是眼外伤常见的致盲原因之一,各地报告的致盲率为20%～48.9%。本文对88例眼内异物合并外伤性白内障患者采用联合手术治疗,收到较好疗效,术前视力0.05以下占85.2%,术后矫正视力0.05以下占27.3%,矫正视力0.06～1.5占73.7%,其中矫正视力0.6～1.5者占22.8%。根据异物的性质、在眼内部位和晶体损伤情况选择不同的手术方式一次联合手术摘出异物和白内障,术后采用中西药配合治疗。联合手术可提高疗效,减少术后并发症.减少手术次数,减轻病人的痛苦,缩短病程,减少医疗费用.眼科学报1993;9:216—218.     

Spectrum of morphological appearance of amyloid deposits in Alzheimer's disease

Summary Immunocytochemical staining with monoclonal antibodies to the -protein on tissue sections which have been pretreated with formic acid is not only a very specific but also a highly sensitive method for the detection of amyloid deposits in the brains of Alzheimer's disease victims. We report here a spectrum of morphological appearance of the brain amyloid deposits which are one of the main histopathological correlates of this disorder. Deposits of the -protein are not only found in the well-known lesions [congophilic angiopathy and senile (neuritic) plaques] but are also seen under various morphological forms for which the word plaques does not appear an appropriate term: amyloid fibrils are found as large areas of diffuse infiltration of the neuropil, as ribbon-like infiltration in the subpial layer of the cerebral cortex, as granular deposits in the white matter, as diffuse deposits in the molecular layer of the cerebellum and the basal ganglia and as star-shaped deposits in the cerebellar Purkinje cell layer. The morphology of these deposits seems to depend on the cyto-and fibroarchitectonics of the brain region in which they are found, on the amount of amyloid deposited, and also on the type of staining technique used. It is only under specific circumstances that the deposition of amyloid in the neuropil is accompanied by the formation of paired helical filaments in nerve cell processes and their parent perikarya. In conclusion, our studies suggest that the extent of brain amyloidosis in Alzheimer's disease is much wider than so far appreciated.Supported in part by grants 5-AGO-4220-05 and 5-HD-22634-02 from the National Institutes of Heath     

A unique exonic splice enhancer mutation in a family with X-linked mental retardation and epilepsy points to a novel role of the renin receptor

The renin-angiotensin system (RAS) is essential for blood pressure control and water-electrolyte balance. Until the discovery of the renin receptor, renin was believed to be mainly a circulating enzyme with a unique function, the cleavage of angiotensinogen. We report a unique mutation in the renin receptor gene (ATP6AP2) present in patients with X-linked mental retardation and epilepsy (OMIM no. 300423), but absent in 1200 control X-chromosomes. A silent mutation (c.321C>T, p.D107D) residing in a putative exonic splicing enhancer site resulted in inefficient inclusion of exon 4 in 50% of renin receptor mRNA, as demonstrated by quantitative RT-PCR. Analysis of membrane associated-receptor molecular forms showed the presence of full-length and truncated proteins in the patient. Functional analysis demonstrated that the mutated receptor could bind renin and increase renin catalytic activity, similar to the wild-type receptor, but resulted in a modest and reproducible impairment of ERK1/2 activation. Thus, our findings confirm the importance of the RAS in cognitive processes and indicate a novel specific role for the renin receptor in cognitive functions and brain development.     

抗体包被对红细胞变形性影响的研究

作者对抗体包被的红为性进行研究，发现抗体包被改变了红细胞的变形性，在我们研究的抗体量范围内，抗体量越多，红细胞的变形性越小，作者从血液流变学的角度对上述结果作了讨论，并提出了通过测定其对红细胞变形性的影响来比较准确地标定抗体效价的可能性。     

Essential role for caspase 8 in T-cell homeostasis and T-cell-mediated immunity

Defects in death receptor-mediated apoptosis have been linked to cancer and autoimmune disease in humans. The in vivo role of caspase 8, a component of this pathway, has eluded analysis in postnatal tissues because of the lack of an appropriate animal model. Targeted disruption of caspase 8 is lethal in utero. We generated mice with a targeted caspase 8 mutation that is restricted to the T-cell lineage. Despite normal thymocyte development in the absence of caspase 8, we observed a marked decrease in the number of peripheral T-cells and impaired T-cell response ex vivo to activation stimuli. caspase 8 ablation protected thymocytes and activated T-cells from CD95 ligand but not anti-CD3-induced apoptosis, or apoptosis activated by agents that are known to act through the mitochondria. caspase 8 mutant mice were unable to mount an immune response to viral infection, indicating that caspase 8 deletion in T-cells leads to immunodeficiency. These findings identify an essential, cell-stage-specific role for caspase 8 in T-cell homeostasis and T-cell-mediated immunity. This is consistent with the recent identification of caspase 8 mutations in human immunodeficiency.