Design Considerations for a Microfluidic Device to Quantify the Platelet Adhesion to Collagen at Physiological Shear Rates

Accurate assessment of blood platelet function is essential in understanding thrombus formation which plays a central role in cardiovascular disease. Parallel plate flow chambers have been widely used as they allow for platelet adhesion on a collagen surface at physiologically relevant fluid mechanical forces. Standard parallel plate flow chambers typically need several milliliters of blood, which is substantially more than can be obtained from small animals. We designed, fabricated, and assessed the functionality of a microfluidic channel with a width of 500 μm and a height of 50 μm in which a wall shear rate of 1000 s⁻¹ can be achieved with a flow rate of 15 μL/min. The velocity distribution in the microchannel predicted from the equations of motion was compared to experimentally measured velocities of fluorescent beads. This analysis showed that the motion of beads was quite similar to the predicted motion. Adhesion of platelets from whole blood at a shear rate of 1000 s⁻¹ onto a collagen surface using the microfluidic flow channel was qualitatively similar to platelet adhesion observed with a standard sized parallel plate flow chamber. After 5 min flow the surface coverage of platelets in the microfluidic device was about 55% while in a traditional size flow chamber the surface coverage was about 75%. This suggests that the microfluidic flow chamber can be used to quantify platelet adhesion for system where only very small amounts of blood are available.     

Myectomy versus anterior transposition for inferior oblique overaction

BACKGROUND: Inferior oblique overaction can be either secondary (as a sequela of ipsilateral superior oblique palsy) or primary (commonly associated with horizontal strabismus). Superior oblique underaction often coexists with both primary and secondary inferior oblique overaction. This retrospective case series compares the efficacy of inferior oblique myectomy versus anterior transposition in improving inferior oblique overaction and superior oblique underaction in eyes with either primary or secondary inferior oblique overaction. METHODS: One hundred twenty eyes of 81 patients were included in this retrospective case series, of which 20 had anterior transposition of the inferior oblique and 100 eyes underwent myectomy. Inferior oblique myectomy was compared with inferior oblique anterior transposition in improving inferior oblique overaction and superior oblique underaction in each diagnostic subgroup. Postoperative outcome was qualitatively and quantitatively assessed. Fisher's exact test was used to compare the outcomes. The quantitative improvement of function in terms of inferior oblique overaction and superior oblique underaction was analyzed by regression analysis. RESULTS: When postoperative inferior oblique overaction was considered, there was no statistically significant difference between myectomy and anterior transposition in both primary and secondary inferior oblique overaction. Myectomy was superior to anterior transposition in improving superior oblique underaction in both primary inferior oblique overaction (OR = 0.14; 95% CI, 0.015-1.45; p = 0.056) and secondary inferior oblique overaction (OR = 0; 95% CI, 0-0.027; p < 0.001). The quantitative improvement of function showed a significant difference between procedures for superior oblique underaction (t-test; p = 0.005; 95% CI, 0.25-1.3) but not inferior oblique overaction (t-test; p = 0.8; 95% CI, -0.67-0.54). CONCLUSIONS: This study demonstrates both inferior oblique myectomy and inferior oblique anterior transposition to be effective in correcting primary and secondary inferior oblique overaction. Myectomy is more effective in improving superior oblique underaction associated with both primary and secondary inferior oblique overaction. On this basis, we feel that inferior oblique myectomy has some advantage over anterior transposition in treating combined inferior oblique overaction and superior oblique underaction and can be considered the procedure of choice.     

Undifferentiated Tumors: An Immunohistochemical Analysis on Biopsies

Immunohistochemical staining was performed on 145 biopsies with a diagnosis of undifferentiated or poorly differentiated tumor in order to classify them into lymphoid, epithelial, or mesenchymal in origin. It was possible to arrive at a histogenetic diagnosis on immunostaining in 85.5% of cases. Immunostaining confirmed the diagnosis in 32.4% and contributed to diagnosis in 53.1%. Malignant lymphoma was the most common diagnosis (35.9%), followed by carcinoma (23.4%). A panel of antibodies consisting of anti-common leucocyte antigen (LCA), anti-epithelial membrane antigen (EMA), anti-cytokeratin (CK), anti-low to intermediate molecular weight cytokeratin (CAM 5.2), anti-S-100 protein (S-100), and anti-vimentin (VM) may resolve, to a large extent, some of the common diagnostic problems. © 1994 Wiley-Liss, Inc.     

Idiopathic isolated optic nerve head swelling a presentation of two cases

Optic nerve head swelling is caused by either ocular or systemic diseases of inflammatory, infective, infiltrative, compressive, or ischemic origin. Uncommonly, an isolated optic nerve head swelling without the above underlying mechanisms might also occur. Two patients presented with unilateral, isolated optic nerve head swelling. A detailed oculoneurological examination and a series of investigations failed to indicate any pathology. No probable cause for optic nerve head swelling in these patients was determined by the authors. the authors have stated that they do not have a significant financial interest or other relationship with any product manufacturer or privider of services discussed in this article. The authors also do not discuss the use of off-label products, which include unlabeled, unapproved, or investigative products or devices.     

Haemodynamic instability during transhiatal resection of oesophagus results in postoperative metabolic acidosis and hypoxia: is there a need for assisted ventilation?

Oesophagectomy for oesophageal carcinoma is a stressful physical and metabolic challenge for an individual. The metabolic acidosis and hypoxia resulting postoperatively in a 34-year-old male, suffering from oesophageal carcinoma, after transhiatal oesophagectomy was managed without assisted ventilation contrary to the usual teaching. Relevant literature has been reviewed.     

Sulfur in human crystallins

Molecular models of human gamma-crystallins and the 'alpha-crystallin domain' of human alphaA-crystallin have been built based on available related X-ray crystal structures. The accessibilities of the component cysteine, methionine and tryptophan side chains in the crystallin models have been calculated. The reactivities of these cysteines, which are oxidised in cataract, are assessed based on their known modifications and within the context of their location within the 3D models.     

Familial keratoconus with cataract: linkage to the long arm of chromosome 15 and exclusion of candidate genes

PURPOSE: Keratoconus and cataract are common causes of visual morbidity. Both conditions show genetic predisposition. The purpose of this study was to map the disease locus in a large three-generation family affected by combined early-onset autosomal dominant anterior polar cataract and clinically severe keratoconus. Uniquely, in this family both disorders were present and fully penetrant in those affected. METHODS: Thirty members of the family were examined clinically on two occasions, at an interval of 5 years, to establish their phenotypes and determine the progression of the disease. Genomic DNA was extracted from blood samples of 16 affected and 14 unaffected individuals, and typed with more than 350 highly polymorphic microsatellite loci in a genome-wide linkage screen. Markers were amplified by PCR with fluorescently labeled primers and sized with an automated DNA analyser before calculation of lod scores. After linkage was established, several positional candidate genes were assessed by PCR-based DNA sequencing. RESULTS: The locus for keratoconus with cataract was mapped to a 6.5-Mb region of the long arm of chromosome 15, at 22.33-24.2 between CYP11A and D15S211. The positional and functional candidate genes CTSH, CRABP1, IREB2, and RASGRF1 were excluded as the cause of keratoconus with cataract in this family. CONCLUSIONS: This is the first report of a family with autosomal dominant inheritance of keratoconus in association with cataract. The causative gene maps to the long arm of chromosome 15 but has not yet been identified.