Rabbit corneal endothelial cell surface glycoproteins

Sialic acid residues of plasma membrane glycoproteins of rabbit corneal endothelial cells were radiolabeled by oxidation with sodium periodate and reduction with sodium borotritide. Surface-labeled glycoproteins were resolved by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The major surface labeled glycoproteins were designated GP 1-8 in order of their increasing mobility on the gel (M.W. = 220K (GP-1), 200K (GP-2), 170K (GP-3), 135K (GP-4), 110K (GP-5), 95K (GP-6), 80K (GP-7), and 44K (GP-8). On the basis of the behavior of these glycoproteins on various carrier-bound lectins, preliminary information concerning their saccharide moieties was obtained. All 8 components bound to agarose-linked wheat germ agglutinin; GP 4-6 bound to concanavalin A and GP 6-7 bound to Ricinus communis agglutinin. No component bound to Bandeiraea simplicifolia I, Bandeiraea simplicifolia II, Ulex europeus or soybean agglutinin. These data suggest that in addition to the presence of sialic acid/N-acetylglucosamine residues in all the eight glycoproteins, oligosaccharides with terminal beta-galactose residues occur in GP-6 and GP-7 while mannose (glucose) residues occur in GP 4-6.     

Blood cell structure-function studies: light transmission and attenuation coefficients of suspensions of blood cells and model particles at rest and with stirring.

The Beer-Lambert law of light transmission was found valid for suspensions of blood platelets, erythrocytes, and leukocytes, as well as similarly sized model particles (latex spheres and flat guanine crystals), for a DB-G double-bean photometer at 605 and 710 mg, and a Payton aggregometer with red filter (660 to 750 mu). Attenuation coefficients (K) showed a similar dependence on a particle "equivalent sphere" radius as data reported for a "zero-degree photometer," for particles at rest. Size distribution, degree of aggregation, state of contamination, and effects of aldehyde fixation of the cell suspensions, well as optical geometry, were related to the measured K values. Particle optical efficiencies (K) for asymmetric particles were similar whether calculated from cross-sectional areas derived from "equivalent spheres" or from geometric cross-sections accounting for orientation distributions at rest. Appropriate cell and latex models were identified for the erythrocytes (E) and platelets (P) at rest on the basis of similar K,k values. The biphasic change in K occurring with stirring of these asymmetric blood cells (E, HP) was partly explainable by the known variations of K with shear-induced particle alignment to the optic axis. No such effects were observed with spherical particles or "sphered" cells, even when polydisperse as to size an aggregates. This investigation begins to quantitate ongoing light transmission studies of blood cell shape/aggregation changes.     

Cadaveric study of anterior and posterior elbow endoscopy portals for endoscopic distal biceps repair: comparative anatomy-at-risk

Purpose

The purpose of this study was to describe neurovascular structures-at-risk during establishment of five portals for access to distal biceps tendon (DBT) in cubital fossa, and to establish relative safety of these portal sites for such access. We hypothesized that all five portals are safe for endoscopic DBT exploration.

Methods

Ten fresh frozen cadaveric elbows were dissected after placement of portals at five potential sites (four anterior, one posterior). Nine neurovascular structures (CV, cephalic vein; LCN, lateral cutaneous nerve; LV, leash of vessels; RN, radial nerve; SRN, superficial radial nerve; PIN, posterior interosseous nerve; RA, radial artery; BA, brachial artery; MN, median nerve) were dissected, and their distances from portal sites were measured. Statistical analysis was performed to determine relative portal safety, and risk of injury to neurovascular structures in relation to each portal was analyzed.

Results

Structures that were significantly “at risk” were RA (p = 0.006), SRN (p = 0.002), and PIN (p = 0.004). RA was significantly “at risk” of injury from portal 4 (p = 0.009). Similarly, SRN was “at risk” from portal 3 (p = 0.036), and the PIN was “at risk” from portal 2 (p = 0.003).

Conclusions

Portal 1 (parabiceps portal) was safe for all neurovascular structures, however, portals 2–4 were significantly closer to neurovascular structures. RA, SRN, and PIN were significantly “at risk” as compared to other structures amongst the portals studied. Portal 5 was relatively safe for SRN and PIN.

Clinical relevance

Portals 1 (parabiceps portal) and 5 (distal posterior) can be safely placed for endoscopic access to the DBT. Portal 4 (open distal anterior) may be used after careful open dissection and under direct vision. Portals 2 and 3 are not recommended for elbow endoscopy.

     

Soft tissue tuberculosis – An unusual presentation of a common disease

Tuberculosis (TB) has reached epidemic proportions in India with a myriad of clinical presentations. Extra pulmonary TB can present in a wide variety of clinical forms and its identification requires a high degree of clinical suspicion. Soft tissue infection by Mycobacteria is rare. The diagnosis is often not thought of owing to the rarity of this entity.     

Tribological characterization of a biocompatible thin film of UHMWPE on Ti6Al4V and the effects of PFPE as top lubricating layer

Ultra-high molecular weight polyethylene (UHMWPE) thin film was coated onto Ti6Al4V alloy specimens using dip coating method. Tribological performance of this coating (thickness of 19.6±2.0 μm) was evaluated using 4 mm diameter Si₃N₄ ball counterface in a ball-on-disk tribometer. Tests were carried out for different normal loads (0.5, 1.0, 2.0 and 4.0 N) and rotational speeds of the disk (200 and 400 rpm). UHMWPE coating formed in this study exhibits high hydrophobicity with water contact angle of 135.5±3.3° and meets the requirements of cytotoxicity test using the ISO 10993-5 elution method. This coating shows low coefficient of friction (0.15) and high wear durability (>96,000 cycles) for the tested conditions. PFPE overcoat on UHMWPE has further increased the wear durability of UHMWPE coating as evaluated at even higher rotational speed of 1000 rpm.     

Electrophysiological correlates of cognition improve with nap during sleep deprivation

The efficacy of a 30-min nap as a countermeasure in the reduction of cognitive decline following 24 h of sleep deprivation (SD) on subjective sleepiness scales, event-related potential (ERP) P300, and contingent negative variation (CNV) was evaluated. The experiment was performed in three sessions on different days between 7 and 8 a.m. on nine normal, healthy males, of age 25–30 years: Session 1. Baseline recordings; Session 2, after one night’s total sleep deprivation, and; Session 3, after 1 week of Session 1, following one night’s sleep deprivation along with a 30-min nap opportunity between 1.00 and 3.00 a.m. Subjective sleepiness scores increased after SD as compared to baseline, but reduced significantly after nap (P < 0.05). There was an increase in P3 peak latency of ERP following SD (16%, P < 0.01), which was reduced with nap (10.7%, P < 0.05).There was an increase in CNV M1 peak latency after SD (18%) which decreased with the use of nap (12.5%) (P < 0.01). The CNV reaction time increased following SD (39.3%) and decreased with the use of nap (24%) (P < 0.01). No significant effects on ERP N1, P1, N2 latencies, P2 and P3 amplitudes and CNV N1, P3, M2 peak latencies and M1, and M2 amplitudes were observed. It was concluded that a 30-min nap, between 1.00 and 3.00 a.m. during night SD, reduces the cognitive decline following 24 h of SD in terms of its electro-physiological correlates. The study is of applied value in optimization of cognitive performance in professions demanding night work schedules.     

Evaluation of daily online set-up errors and organ displacement uncertainty during conformal radiation treatment of the prostate

We have studied and analysed the magnitude of interfraction set-up errors and gold seed marker and prostate displacement in 118 patients using three gold seeds implanted within the prostate. Set-up errors and gold seed marker displacements were determined from bony anatomy and gold seed marker mismatch between the electronic portal image and the simulation digitally reconstructed radiograph (DRR), respectively. Prostate displacement relative to bony anatomy was determined from the difference between gold seed marker and bony anatomy displacement. Daily online repositioning of patients was accomplished through image matching using Varian Portal-Vision software. A total of 4878 electronic portal images and 236 DRRs from 118 patients were acquired over the course of the study. The means and standard deviations of the systematic error of gold seed marker displacement of 118 patients were 2.1+/-2.7 mm for anteroposterior (AP), -0.5+/-1.7 mm for left-right (L-R), and 1.0+/-1.9 mm for superoinferior (SI) directions; the random errors were 3.2 mm (0.9-4.9 mm) for AP, 1.9 mm (0.7-5.3 mm) for L-R, and 2.1 mm (0.7-4.5 mm) for SI directions. The mean and standard deviation of the isocentre set-up systematic error of 20 patients was 1.2+/-2.2 mm for AP, -0.1+/-1.4 mm for L-R, and -0.8+/-2.6 mm for SI directions. The isocentre set-up random errors were 1.6 mm (1.2-4.8 mm) for AP, 1.3 mm (0.6-2.5 mm) for L-R and 1.3 mm (1.0-2.6 mm) for SI directions. The mean and standard deviation of the prostate displacement systematic error relative to bony anatomy was 0.0+/-1.4 mm for AP, 0.0+/-1.1 mm for L-R and -0.2+/-2.4 mm for SI directions. Prostate displacement random errors were 1.5 mm (1.2-3.3 mm) for AP, 0.9 mm (0.4-1.5 mm) for L-R and 1.4 mm (1.2-2.4 mm) for SI directions.