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Biomedical subjects

D M Kim

Publications and source records attributed to D M Kim.

At least 55 records · Page 3Linked to original sources
PubMed1993

Mitomycin C in anterior chamber tube shunt to a surgical membrane.

To increase the success rate of intraocular pressure control in recalcitrant glaucoma, anterior chamber tube shunt to a surgical membrane (ACTSSM) surgery using silicone tube and expanded polytetrafluoroethylene (e-PTFE) can be performed. Applying mitomycin C (MMC) during ACTSSM surgery may increase the success rate by decreasing the fibroblast proliferation and collagen in the fibrous capsule. To evaluate the effects of MMC on the fibrous capsule formed after ACTSSM surgery, operations were performed on 18 white rabbits. Nine rabbits were treated with 0.04% MMC solution on the episclera for 5 minutes before ACTSSM (group A) and the others were not treated (group B). At postoperative 2, 4 and 8 weeks successively, 6 eyes of the 3 rabbits were enucleated from each group. Light microscopic examinations were performed after hematoxylin & eosin staining and Masson's trichrome staining. In group A (MMC application group), fibrous capsules were not so dense, moderately thick, and showed many microcystic spaces. Proliferating fibrous connective tissues ingrowing between twofold surgical membranes were scanty. In group B (MMC non-application group), fibrous capsules showed high cellular density and less microcystic spaces, comparing those of MMC application group, suggesting low permeability of fibrous capsule to aqueous humor. MMC may be useful in increasing the success rate of ACTSSM surgery.

Animals↗
PubMed1992

Prestorage removal of Yersinia enterocolitica from red cells with white cell-reduction filters.

Prestorage removal of phagocytic white cells (WBCs) may increase the survivability of contaminating bacteria in units of stored red cells. Fourteen units of whole blood were inoculated with 65 colony-forming units per mL of Yersinia enterocolitica (serotype O:3) and processed into AS-3-preserved red cells. Five red cell units were filtered with a prototype third-generation filter and five red cell units with a second generation filter. WBC reduction was performed on the day of collection. Four red cell units were not filtered. Three noninoculated whole blood units served as negative controls; two were filtered (one with each type of WBC-reduction filter) and one remained unfiltered. All red cell units were then stored at 4 degrees C for 42 days. One of the five filtered red cell units (20%) in each filter group supported growth of Y. enterocolitica. In contrast, 4 (100%) of 4 unfiltered inoculated red cell units had growth (p = 0.04). Overall, 2 (20%) of 10 units of WBC-reduced red cells supported the growth of Y. enterocolitica, as compared to 100 percent of unfiltered red cell units after inoculation (p = 0.015). Bacterial contamination was not detected in any of the three noninoculated units. It can be concluded that prestorage WBC filtration significantly reduces the potential for growth of Y. enterocolitica in red cells stored at 4 degrees C for 42 days.

Endotoxins↗
PubMed1992

Optic disc of the myopic eye: relationship between refractive errors and morphometric characteristics.

Because the optic disc in myopic eyes is different from a normal optic disc, there are many difficulties in examining the optic discs of myopic eyes. To study optic disc change due to myopia, we performed a morphometrical study of stereophotographs of 61 men, 109 eyes, who had no glaucoma history. The range of refractive error was from +0.75 diopter to -12.75 diopter, and all subjects had intraocular pressure below or equal to 21 mmHg. According to the increase in the myopic degree, the temporal slope of the disc cup was significantly decreased, but the ratio of the vertical disc diameter (VDD) to the horizontal disc diameter and the ratio of the width of peripapillary atrophy (PPA) to the VDD were significantly increased. The above results suggests that in high myopia the optic disc was tilted and the rim-cup border was indistinct and there are some problems in the estimation of the morphometric parameters. Also in evaluation of the PPA of myopic glaucoma patients, there may be some difficulty in deciding whether it is due to myopic change or glaucomatous damage.

Adolescent↗
PubMed1992

Effects of aqueous humor on filtering bleb in rabbits.

Preoperative aqueous humor, known to inhibit the growth of fibroblasts in tissue culture assay, was used as an adjunct to filtering surgery in rabbits to determine its effect in vivo on the outcome of filtering surgery. Fifteen rabbits underwent a posterior-lip sclerectomy in both eyes. In experimental eyes 1.4 ml preoperative aqueous humor and in fellow eyes 1.4 ml balanced salt solution were injected intracamerally. Gross and histopathological differences of bleb were observed. In this animal experiment, although there was no statistical significance or late postoperative effect, the rabbit eyes refilled with preoperative aqueous humor intracamerally just after filtering surgery, had a larger bleb and less fibroconnective tissue on the bleb than the control eyes in the early postoperative period.

Animals↗
PubMed1992

Photoelastic analysis of stress distribution on the tibiofemoral joint after meniscectomy.

Three-dimensional photoelasticity models of the knee joints were made of epoxy to observe the change in the status of stresses according to the size of defect in the meniscus. Three kinds of meniscus models were made of rubber. Through axial application of a vertical compressive load of 8 kg, equivalent to the joint reaction of 3000 N in the human knee joint, the patterns of the isochromatic fringes were observed and stresses around the knee joint were analyzed according to the size of the defect in the medial meniscus. Stress was increased in magnitude according to the size of the defect of the meniscus, and was focalized after meniscectomy. In the partial meniscectomy model, the maximum stress concentration point of the removed side migrated to the margin of the same side of the joint. But, in the total meniscectomy model, stresses were markedly increased in magnitude on both sides of joints, and maximum stress concentration points were more centralized. This centralization effect would contribute to the degenerative process of the knee joint after meniscectomy.

Humans↗
PubMed1992

Propagation of ciliary smooth muscle cells in vitro and effects of prostaglandin F2 alpha on calcium efflux.

The effect of prostaglandin F2 alpha (PGF2 alpha) on calcium efflux from ciliary smooth muscle cells was studied. Ciliary smooth muscle cells, cultured from human ciliary muscle explants, retained the morphologic and immunologic characteristics of smooth muscle cells. High concentrations (to 10(-6) mol/l) of PGF2 alpha were associated with a dose-dependent increase of calcium (45Ca) efflux, whereas at concentrations lower than 10(-8) mol/l there was little or no 45Ca efflux. Our in vitro data are inconsistent with the experimental hypothesis that PGF2 alpha at pharmacologic concentrations relaxes ciliary muscle with a consequent increase in uveoscleral outflow.

Actins↗
PubMed1991

Fibrous capsule surrounding silicone encircling band and Gore-Tex surgical membrane.

Since the anterior chamber tube shunt to an encircling band(ACTSEB) is not a simple procedure, an extended polytetrafluoroethylene (e-PTFE)-silicone tube (anterior chamber tube shunt to a surgical membrane; ACTSSM) was attempted as a new glaucoma drainage implant. To see whether the newly-modified, two-fold e-PTFE-silicone tube implant could prevent early hypotony and to compare the tissue response to each implant, ACTSEB and ACTSSM procedures were done in normal colored rabbit eyes. It was found the ACTSSM kept the depth of the postoperative anterior chamber normal. And in general, foreign body responses were light microscopically similar. The fibrous capsule lining the e-PTFE was composed of thicker, less dense fibroblasts, as well as less collagen than that lining the silicone encircling band. These findings seemed to be related to the difference in the pressure-lowering capacity between ACTSEB and ACTSSM.

Animals↗
PubMed1990

Detection of specific proteins in the aqueous humor in primary open-angle glaucoma.

To elucidate the mechanism of increased intraocular pressure in primary open-angle glaucoma (POAG), the protein profiles of aqueous humor obtained from POAG patients were compared with those of cataract patients as a control group. Aqueous humor proteins were analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and detected by the ultrasensitive silver staining technique. In 79% of the samples taken from POAG patients, protein bands of 140,000 or 160,000 daltons were stained, but none were stained from cataract patients. The presence of these protein bands revealed statistically significant differences between the two groups. Protein bands of 140,000 or 160,000 daltons were evenly visible at all ages in POAG patients, and the positivity of bands had no correlation with sex or initial intraocular pressure level. It is possible that the ultrastructural changes of the aqueous outflow pathway in POAG may be related to the changes in the aqueous protein, presence of 140,000 or 160,000 daltons protein bands.

Adult↗
PubMed1990

Detection of early visual field change in ocular hypertension using STATPAC.

Perimetric tests were performed on 32 ocular hypertensive eyes (17 patients) with the C-30-2 threshold program of the Humphrey Visual Field Analyzer. The global indices of 32 ocular hypertensive eyes were compared with those of 34 normal eyes (17 controls). None of the 34 normal eyes had visual field sensitivity loss. However, three out of 32 ocular hypertensive eyes, which is 0.4%, had visual field sensitivity loss. Of these three eyes, two eyes showed generalized depression (MD, P less than 5%) and one eye showed paracentral scotoma.

Adolescent↗
PubMed1990

Optic disc and early glaucomatous visual field loss.

In the early stages of glaucoma, the disc changes prior to visual field loss, so assessment of the optic disc is very important for the evaluation of the glaucoma patient. The aim of this study is to assess the glaucomatous disc and to look for the features of the optic disc that are commonly associated with early visual field loss. Forty-three eyes of 28 patients were included in this investigation. The criteria for inclusion were a cup/disc(C/D) ratio of more than 0.4 by direct ophthalmoscopy, no visual field defect with Goldmann perimetry, and open anterior chamber angle. Each optic disc was photographed with a Canon fundus camera with Polaroid 600 Plus film. Each photographic set was then examined stereoscopically for morphologic parameters: 1) comparison of vertical versus horizontal C/D ratio; 2) presence of nasal cupping; 3) presence of overpassing vessels; 4) presence of baring of circumlinear vessels; 5) presence of peripapillary atrophy; 6) ratio of the thinnest neuroretinal rim(NRR) width in the vertical sectors of the NRR width of the temporal sector. All subject's central visual fields were examined with an automated static perimeter, Humphrey program C30-2 with STATPAC. The C/D ratio estimated by direct ophthalmoscopy consistently showed a smaller C/D ratio than that found by the stereophotographic method. The parameter with the highest probability value to differentiate between the optic disc of the early visual field loss and the optic disc of normal subjects was "Ratio of the thinnest NRR width in the vertical sectors to the NRR width of the temporal sector less than or equal to 85%". Although it has less resolving power than slide film, a stereo disc photograph with Polaroid film is a quick and simple method of recording changes, and the ratio of the thinnest NRR width in the vertical sectors to the temporal sector is a good predictive parameter for detection of early visual field loss.

Adolescent↗
PubMed1977

Transmission microscropy of unmodified biological materials: comparative radiation dosages with electrons and ultrasoft x-ray photons.

The minimum radiation dosage in a specimen consistent with transmission microscopy at resolution d and specimen thickness t is calculated for model specimens resembling biological materials in their natural state. The calculations cover 10(4)-10(7) eV electrons and 1.3-90 A photons in a number of microscopy modes. The results indicate that over a considerable part of the (t,d)-plane transmission microscopy on such specimens can be carried out at lower dosage with photons than with electrons. Estimates of the maximum resolutions obtainable with electrons and photons, consistent with structural survival of the specimen, are obtained, as are data on optimal operating conditions for microscopy with the two particles.

Air↗
PubMedDate not supplied

Prolonging cell-free protein synthesis by selective reagent additions.

Factors causing the early cessation of protein synthesis have been studied in a cell-free system from Escherichia coli. We discovered that phosphoenol pyruvate (PEP), the secondary energy source for ATP regeneration, and several amino acids are rapidly degraded during the cell-free protein synthesis reaction. The degradation of such compounds takes place even in the absence of protein synthesis. This degradation severely reduces the capacity for protein synthesis. The lost potency was completely recovered when the reaction mixture was supplied with additional PEP and amino acids. Of the 20 amino acids, only arginine, cysteine, and tryptophan were required to restore system activity. Through repeated additions of PEP, arginine, cysteine,and tryptophan, the duration of protein synthesis was greatly extended. In this fed-batch reaction, after a 2 h incubation, the level of cell-free synthesized chloramphenicol acetyl transferase (CAT) reached 350 microg/mL, which is 3.5 times the yield of the batch reaction. Addition of fresh magnesium further extended the protein synthesis. As a result, through coordinated additions of PEP, arginine, cysteine, tryptophan, and magnesium, the final concentration of cell-free synthesized CAT increased more than 4-fold compared to a batch reaction. SDS-PAGE analysis of such a fed-batch reaction produced an obvious band of CAT upon Coomassie Blue staining.

Cell-Free System↗
PubMedDate not supplied

A semicontinuous prokaryotic coupled transcription/translation system using a dialysis membrane.

This report describes a novel and simple cell-free protein synthesis system. In this paper, we prove that the short duration of protein synthesis in a conventional cell-free protein synthesis system of batch configuration can be attributed both to depletion of energy sources and deactivation of S30 extract by small-molecule byproducts produced during the protein synthesis. The reaction period of cell-free protein synthesis system could be extended through an operation of a continuous-flow cell-free protein synthesis system, which was originally developed by Spirin. However, inspite of the greatly extended reaction period, the final amount of cell-free produced protein was not significantly larger than that can be obtained from a batch system due to the reduced rate of protein synthesis. It was supposed that the reduced rate of protein synthesis in the continuous-flow system was attributed to leakage of translational components through the ultrafiltration membrane during the operation of the continuous-flow system. To solve such a problem of the continuous-flow system, we have developed and operated a novel reactor for cell-free protein synthesis. By use of this system, protein synthesis occurred for at least 14 h, yielding 1.2 mg/mL CAT protein. The present system is superior to the continuous-flow system as well as the conventional batch system in that it enables extremely high productivity without using any complex and hard-to-handle apparatus. As far as we know, the yield of cell-free protein synthesis given above is the best of the results reported to date.

Cell-Free System↗