Effects of differences in charge and hydrophobicity of surface amino acids of hemoglobins on high-performance gel-permeation chromatography

We studied the elution properties of the carboxy and deoxy forms of hemoglobins A, S, and C in gel-permeation high-performance liquid chromatography using TSK-GEL-SW-type columns. Since these hemoglobins have the same molecular mass but different amino acids at the beta 6 position, they are ideal for studies of the effect of charge and hydrophobicity on elution patterns in high-performance gel-permeation chromatography. Although there was a linear relationship between elution volume and logarithm of molecular mass of various proteins, the elution volumes of carboxyhemoglobins were found to be slightly greater than the expected volumes calculated from the molecular mass. The elution volumes of hemoglobins increased in the order of hemoglobins F, A, C, and S in 0.1 M phosphate buffer, pH 7.4, at room temperature. The elution volume of these hemoglobins was also dependent on pH and salt concentration. These results indicate that elution of these hemoglobins was affected by the electrostatic and hydrophobic interactions between hemoglobin molecules and polar sites of silica gel (with silanol groups) of the resin matrix of TSK-G2000-SW. This study may serve as a useful reference for separation and determination of molecular masses of proteins in the native state using gel-permeation liquid chromatography.

Clinical study on the efficacy of tonsilloadenoidectomy

Controversies regarding the efficacy and indications for tonsilloadenoidectomy have existed for some time. The authors attempt to present an outline in the management of patients with tonsillar and adenoid diseases by carrying out a clinical survey on 1,566 patients who had tonsilloadenoidectomy at the Department of Otolaryngology, Seoul National University Hospital, from January of 1981 to December of 1985. There were 217 cases that could be followed up and the survey consists of the indication for surgery, initial presenting symptoms and their changes over time after surgery, and complications of the surgery.

Role of disulfide bonds in the oligomeric structure and protease resistance of recombinant and native Treponema pallidum surface antigen 4D

Recombinant Treponema pallidum surface antigen 4D isolated from Escherichia coli formed a protease-resistant ordered ring structure composed of 19,000-dalton subunits. On gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the higher oligomers of recombinant 4D migrated with molecular masses that were nearly multiples of the 190,000-dalton basic ordered ring. Reduction at room temperature with 2-mercaptoethanol converted the 190,000-dalton ordered ring and the higher oligomers to a 160,000-dalton form and the dissociated monomer. A 190,000-dalton form of 4D was identified in sodium dodecyl sulfate-solubilized T. pallidum after reduction at room temperature. Disulfide bonds stabilized both native and recombinant 4D oligomers against dissociation by heating in detergent without a reducing agent. Electron microscopy of recombinant 4D revealed that the characteristic ordered ring structure was maintained after reduction. Reduction of 4D under conditions that preserved the ordered ring structure did not affect the resistance of the molecule to digestion with proteinase K. The properties of 4D suggest that it may fulfill an important structural role in the T. pallidum outer membrane.

Regulation of protein kinase C activity by gangliosides

The activity of protein kinase C (Ca2+/phospholipid-dependent enzyme) in the presence of phosphatidylserine and its physiological regulator, diacylglycerol, could be suppressed by a mixture of brain gangliosides. Half-maximal inhibition was observed at 30 microM and was nearly complete at 100 microM. Inhibition was observed at all concentrations of Ca2+ between 10(-8) and 10(-4) M. Inhibition of protein kinase C activity could not be reversed by increasing the concentration of diacylglycerol or the substrate, histone. Inhibition was also observed when myelin basic protein or a synthetic myelin basic protein peptide was used as substrate. Among the individual gangliosides, the rank order of potency was GT1b greater than GD1a = GD1b greater than GM3 = GM1. Our results suggest that gangliosides may regulate the responsiveness of protein kinase C to diacylglycerol.

Gangliosides inhibit phospholipid-sensitive Ca2+-dependent kinase phosphorylation of rat myelin basic proteins

Gangliosides inhibit the phosphorylation of both small and large rat myelin basic proteins (SMBP, LMBP) by an endogenous phospholipid-sensitive Ca2+-dependent protein kinase (C-kinase). Using a rat brain myelin preparation in an in vitro phosphorylation assay system, we determined the inhibition constants (IC50's) of the gangliosides GM1, GD1a, GD1b, and GT1b to be approximately 160 microM, 65 microM, 65 microM, and 40 microM, respectively. Asialoganglioside GA1, ceramide, and N-acetylneuraminic acid (NANA, sialic acid) failed to produce similar inhibition, suggesting that both the lipid and the sialic acid moieties are necessary, but neither alone is sufficient to produce inhibition. The results indicate that gangliosides may regulate protein kinase C activities in the nervous system.

Radiation optic neuropathy

Following surgery for pituitary adenoma, radiation therapy is an accepted treatment in reducing tumor recurrence. However, a potential therapeutic complication is delayed radionecrosis of perisellar neural structures, including the optic nerves and chiasm. This particular cause of visual loss, radiation optic neuropathy (RON), has not been emphasized in the ophthalmologic literature. Four cases of RON seen in the past five years are reported. Diagnostic criteria include: (1) acute visual loss (monocular or binocular), (2) visual field defects indicating optic nerve or chiasmal dysfunction, (3) absence of optic disc edema, (4) onset usually within three years of therapy (peak: 1-1 1/2 years), and (5) no computed tomographic evidence of visual pathway compression. Pathologic findings, differential diagnosis and therapy will be discussed in outlining the clinical profile of RON.

The effect of synovectomy on the articular cartilage of the knee joint in rabbits

Subtotal synovectomy was performed on the right knee joints of 20 immature and 20 mature rabbits, and articular cartilage from the femoral and tibial condyles and the patellae was examined at 1, 3, 5 and 12 weeks after operation. Specimens from the unoperated left knees provided the controls. Each specimen was examined macroscopically and with histological (H-E stain) and histochemical (safranin-O stain) techniques for abnormalities in structure, cell population, stain intensity and distribution. The femoral articular cartilage was most affected by synovectomy. The tibial articular cartilage was only moderately affected and the patellar articular cartilage was even less affected. The histochemical changes were transient and reversible, being more severe and prolonged in the mature animals. No changes in either group were noted on gross inspection or in the H-E stained sections.

[The effect of viruses on megakaryocytes in vitro (author's transl)]

Bone marrow suspensions from adolescent rats contain 0.3% megakaryocytes; this rate decreases to almost zero within 72--96 h cultivation in vitro in Leighton tubes because of thrombocytopoesis. Such cultures were inoculated immediately after seeding with different viruses in high multiplicity. After infection with herpes simplex virus type 1 or adenovirus type 2, no deviation of the number and morphology of the megakaryocytes was seen when compared with control cultures. However, after infection with vaccinia virus and, still more marked, with Newcastle disease virus, morphological alterations and interference with thrombocytopoesis were seen. Furthermore, a considerable portion of the altered megakaryocytes persisted for 72--96 h. Finally, the cytoplasm of the megakaryocytes after infection with vaccinia virus or NDV, but not with HSV 1 or adenovirus 2, showed a specific immunofluorescence with antiviral antisera, which indicates a direct cellular involvement and multiplication of vaccinia virus and NDV in megakaryocytes.

Chemical methylation of inorganic mercury with methylcobalamin, a vitamin B12 analog

Chemical methylation of mercuric chloride with methylcobalamin has been studied. Methylated mercury was detected by gas chromatography; and analysis of the products of the reaction by thin-layer chromatography revealed that the methylation proceeded at a remarkably high rate when methylcobalamin and inorganic mercury were mixed. Dimethylmercury was an initial product of the reaction.