全身性遗传疾病对角膜移植排斥的影响

角膜移植为治疗角膜盲的主要手段，而角膜移植排斥则是决定角膜植片存活时间和病人术后视力的关键。角膜得益于其特殊的眼前节“免疫赦免”状态，使得角膜移植能够在众多器官移植中享有极低的排斥率，然而排斥反应发生的风险依然存在。当机体处于遗传物质异常的特殊状态时，宿主将通过宏观调控“免疫赦免”状态对植片的保护作用或受体对移植物排异产生的有害作用，延迟或促进角膜移植排斥反应的发生，进而影响移植物的存活时间和透明度。该文综述与角膜移植排斥相关的多种全身性遗传疾病，总结全身性遗传疾病对角膜移植排斥的影响，浅析其发生的病理生理学机制以及诊疗的特殊性。     

中毒性表皮坏死松解症导致眼部远期并发症1例

中毒性表皮坏死松解症与Stevens-Johnson综合征是一种由药物反应引起的严重的表皮及黏膜的不良反应。最常发生于成人,与服用磺胺类、巴比妥类、非类固醇抗炎药、苯妥英纳、醋甲唑胺、别嘌呤醇和青霉素等药物有关。约有1/5的患者否认有服药史,约在1/3病例中由于同时患有严重疾病及用药物治疗而病因不明。中毒性表皮坏死松解症为皮肤科少数病情危重的疾病之一,其死亡率达30%~35%。20%~40%的存活者有眼睛受累。少数患者由于泪管阻塞可出现泪眼,多数患者表现为睫毛、眼睑上皮增生,伴鳞状化生、结膜和角膜新生血管形成,引起一种中毒性表皮坏死松解症眼综合征。经及时治疗中毒性表皮坏死松解症可好转。但是部分患者眼部情况可继续发展,可引起畏光、灼痛、视力下降甚至失明。现汇报1例中毒性表皮坏死松解症眼综合征患者眼部远期并发症。     

Racial and geographic disparities with gastrostomy tube placement in dementia and parkinsonian disorders

IntroductionMany patients with advanced dementia and Parkinson's disease and related disorders (PDRD) are receiving gastrostomy tube (GT) placement annually, despite its lack of proven benefit for preventing aspiration, enhancing nutrition, or prolonging survival. Given clinical practice variability in the care of people with neurodegenerative disorders, we sought to examine racial and geographic disparities in GT placement for these populations in the United States.MethodData were extracted from a publicly-available national database using diagnostic and procedural codes from 2006 to 2010. GT placement rates and odds ratios were calculated for two groups: PDRD and non-parkinsonian dementia (NPD).ResultsIn the PDRD group, odds of GT placement were higher among patients coded as Black (OR 1.69, CI 0.80–3.56, p = 0.17) and Asian (OR 2.17, CI 0.70–6.78, p = 0.18) than Whites; although these tendencies did not reach statistical significance. In the NPD group, GT placement among Black patients was significantly more likely (OR 2.88, CI 1.90–4.36, p < 0.001) than their white counterparts, while Asian patients were significantly less likely (OR 0.12, CI 0.02–0.91, p = 0.04). Compared to the Northeast region, there were significantly lower odds of GT placement in the Midwest region (OR 0.37, CI 0.24–0.58, p < 0.001) in the NPD group only. No difference in odds was observed between the sexes in both groups.ConclusionThis study showed geographic and racial disparities in GT placement among PDRD and NPD patients. Further studies should aim to clarify best practices for GT placement in PDRD and causes of practice differences within and between PDRD and NPD groups.     

Synthetic MRI is not yet ready for morphologic and functional assessment of patellar cartilage at 1.5 Tesla

PurposeThe purpose of this study was to compare morphologic assessment and relaxometry of patellar hyaline cartilage between conventional sequences (fast spin-echo [FSE] T2-weighted fat-saturated and T2-mapping) and synthetic T2 short-TI inversion recovery (STIR) and T2 maps at 1.5 T magnetic resonance imaging (MRI).MethodThe MRI examinations of the knee obtained at 1.5 T in 49 consecutive patients were retrospectively studied. There were 21 men and 28 women with a mean age of 45 ± 17.7 (SD) years (range: 18–88 years). Conventional and synthetic acquisitions were performed, including T2-weighted fat-saturated and T2-mapping sequences. Two radiologists independently compared patellar cartilage T2-relaxation time on conventional T2-mapping and synthetic T2-mapping images. A third radiologist evaluated the patellar cartilage morphology on conventional and synthetic T2-weighted images. The presence of artifacts was also assessed. Interobserver agreement for quantitative variables was assessed using intraclass correlation coefficient (ICC).ResultsIn vitro, conventional and synthetic T2 maps yielded similar mean T2 values 58.5 ± 2.3 (SD) ms and 58.8 ± 2.6 (SD) ms, respectively (P = 0.414) and 6% lower than the expected experimental values (P = 0.038). Synthetic images allowed for a 15% reduction in examination time compared to conventional images. On conventional sequences, patellar chondropathy was identified in 35 patients (35/49; 71%) with a mean chondropathy grade of 4.8 ± 4.8 (SD). On synthetic images, 28 patients (28/49; 57%) were diagnosed with patellar chondropathy, with a significant 14% difference (P = 0.009) and lower chondropathy scores (3.7 ± 4.9 [SD]) compared to conventional images. Motion artifacts were more frequently observed on synthetic images (18%) than on conventional ones (6%). The interobserver agreement was excellent for both conventional and synthetic T2 maps (ICC > 0.83). Mean cartilage T2 values were significantly greater on synthetic images (36.2 ± 3.8 [SD] ms; range: 29-46 ms) relative to conventional T2 maps (31.8 ± 4.1 [SD] ms; range: 26-49 ms) (P < 0.0001).ConclusionDespite a decrease in examination duration, synthetic images convey lower diagnostic performance for chondropathy, greater prevalence of motion artifacts, and an overestimation of T2 values compared to conventional MRI sequences.     

Neurovascular-modulation: A review of primary vascular responses to transcranial electrical stimulation as a mechanism of action

BackgroundThe ubiquitous vascular response to transcranial electrical stimulation (tES) has been attributed to the secondary effect of neuronal activity forming the classic neurovascular coupling. However, the current density delivered transcranially concentrates in: A) the cerebrospinal fluid of subarachnoid space where cerebral vasculature resides after reaching the dural and pial surfaces and B) across the blood-brain-barrier after reaching the brain parenchyma. Therefore, it is anticipated that tES has a primary vascular influence.ObjectivesFocused review of studies that demonstrated the direct vascular response to electrical stimulation and studies demonstrating evidence for tES-induced vascular effect in coupled neurovascular systems.ResultstES induces both primary and secondary vascular phenomena originating from four cellular elements; the first two mediating a primary vascular phenomenon mainly in the form of an immediate vasodilatory response and the latter two leading to secondary vascular effects and as parts of classic neurovascular coupling: 1) The perivascular nerves of more superficially located dural and pial arteries and medium-sized arterioles with multilayered smooth muscle cells; and 2) The endothelial lining of all vessels including microvasculature of blood-brain barrier; 3) Astrocytes; and 4) Neurons of neurovascular units.ConclusionA primary vascular effect of tES is highly suggested based on various preclinical and clinical studies. We explain how the nature of vascular response can depend on vessel anatomy (size) and physiology and be controlled by stimulation waveform. Further studies are warranted to investigate the mechanisms underlying the vascular response and its contribution to neural activity in both healthy brain and pathological conditions – recognizing many brain diseases are associated with alteration of cerebral hemodynamics and decoupling of neurovascular units.