Biomedical subjects

V N Chen

Publications and source records attributed to V N Chen.

3 recordsLinked to original sources

PubMed1996

Cluster headache presenting with orbital inflammation.

Acute, noninfectious orbital inflammations often defy a specific diagnosis despite a thorough medical evaluation and are grouped in the nonspecific diagnostic category of idiopathic inflammation of the orbit (pseudotumor). An atypical case of cluster headache presenting with intermittent migratory facial swelling and orbital inflammation, and 3 mm of exophthalmos simulating idiopathic orbital inflammation is presented. Although periobital pain is a frequent finding in patients suffering from cluster headaches, to the authors' knowledge this is the first reported case of orbital inflammation with cluster headache. After unsuccessful treatment directed at potential infectious and inflammatory causes, the patient responded well to methysergide, an established treatment for cluster headaches. A review of the known mechanism for this disorder, peripheral and central nervous system mechanisms of pain, and migratory angioedema reveals overlapping pathophysiology, clinical findings, and associated symptoms.

Adult↗

PubMed1996

Effect of chondroitin sulfate on the endothelium in corneal storage.

The scope of this study includes investigations on uptake of dextran and chondroitin sulfate in human donor corneas, and effects of chondroitin sulfate on adhesion and growth of rabbit and cat corneal endothelial cells. Fibronectin and dextran sulfate served as controls. Nuclear magnetic resonance spectroscopy revealed no detectable osmotic agents in the corneas stored in either Dexsol or Optisol at 4 degrees C for 6 days. The study showed that chondroitin sulfate enhanced cell adhesion marginally at 2.5%, but >40% at 0.5%, comparable to that of 10 mu g/ml fibronectin, whereas 2% dextran sulfate abolished approximately 70% of cell adhesion capability. In cultures with fibronectin present, the duration for cells to reach confluence was extended from 1.75 to 3 days. Chondroitin sulfate (2%) elicited no apparent cytotoxic effect, with cells becoming polygonal and reaching confluence in approximately 9 days. Cell growth was retarded by 2% dextran sulfate, with signs of senescence on day 3 and clear evidence of cell degeneration on day 9. The cells did not survive without serum in cultures, especially at 36 degrees C. These findings suggest that corneal deterioration probably is linked primarily to serum-free storage conditions, not uptake of osmotic agents in the cornea. The highly negatively charged sulfate group, however, may have rendered chondroitin sulfate less effective as an additive.

Animals↗

PubMed1987

Phosphoenolpyruvate:glycose phosphotransferase system in species of Vibrio, a widely distributed marine bacterial genus.

The genus Vibrio is one of the most common and widely distributed groups of marine bacteria. Studies on the physiology of marine Vibrio species were initiated by examining 15 species for the bacterial phosphoenolpyruvate:glycose phosphotransferase system (PTS). All species tested contained a PTS analogous to the glucose-specific (IIGlc) system in enteric bacteria. Crude extracts of the cells showed immunological cross-reactivity with antibodies to enzyme I, HPr, and IIIGlc from Salmonella typhimurium when assayed by the rocket-line method. Toluene-permeabilized cells of 11 species were tested and were active in phosphorylating methyl alpha-D-glucoside with phosphoenolpyruvate but not ATP as the phosphoryl donor. Membranes from 10 species were assayed, and they phosphorylated methyl alpha-D-glucoside when supplemented with a phospho-IIIGlc-generating system composed of homogeneous proteins from enteric bacteria. Toluene-permeabilized cells and membranes of seven species were assayed, as were phosphorylated fructose and 2-deoxyglucose. IIIGlc was isolated from Vibrio fluvialis and was active in phosphorylating methyl alpha-D-glucoside when supplemented with a phospho-HPr-generating system composed of homogeneous proteins from Escherichia coli and membranes from either E. coli or V. fluvialis. These results show that the bacterial PTS is widely distributed in the marine environment and that it is likely to have a significant role in marine bacterial physiology and in the marine ecosystem.

Cell Membrane↗