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Biomedical subjects

D H Shin

Publications and source records attributed to D H Shin.

At least 145 records · Page 8Linked to original sources
PubMed1997

Chronic use of apraclonidine decreases its moderation of post-laser intraocular pressure spikes.

OBJECTIVE: The purpose of the study is to investigate the efficacy of 1.0% apraclonidine in preventing intraocular pressure (IOP) spike after argon laser trabeculoplasty (ALT) in patients on chronic apraclonidine therapy compared with patients not on chronic apraclonidine use. DESIGN: The study design was a prospective study. PARTICIPANTS: This study consisted of 231 consecutive eyes of patients with primary open-angle glaucoma undergoing ALT: 70 eyes (30%) were started on a regimen including chronic apraclonidine 0.5% use (group A) and 161 eyes (70%) were started on a regimen without chronic apraclonidine 0.5% use (group B). INTERVENTION: Both groups received one drop of apraclonidine 1.0% 15 minutes before ALT to 180 degrees of previously untreated trabecular meshwork. Intraocular pressure was measured before the procedure and at 5 minutes, 1 hour, and 24 hours after the laser treatment. MAIN OUTCOME MEASURES: Incidences of an IOP spike and mean IOPs at 5 minutes, 1 hour, and 24 hours after the laser treatment were compared between the two groups. Multivariate logistic regression analysis also was carried out to identify the significant risk factors for post-ALT IOP spikes despite prophylactic apraclonidine 1.0% treatment. RESULTS: The incidences of IOP spikes greater than 0 mmHg, greater than 2 mmHg, and greater than 5 mmHg at 1 hour after ALT were 32.9%, 22.9%, and 12.9%, respectively, in group A versus 13.7%, 11%, and 3.1%, respectively, in group B (P = 0.0007, P = 0.009, and P = 0.004). Chronic apraclonidine 0.5% use was found to be the only significant risk factor for IOP spikes at 1 hour after ALT by multivariate logistic regression analysis. CONCLUSIONS: The incidences of IOP spikes in group A were significantly greater than in group B and approached the reported incidences of IOP spikes without perilaser apraclonidine prophylaxis. This indicates that peri-ALT apraclonidine is relatively ineffective in patients with chronic apraclonidine 0.5% use (group A) compared with patients without chronic apraclonidine use (group B), presumably because of saturation of the ocular alpha-2 receptors with apraclonidine in patients with chronic apraclonidine use. Therefore, in patients receiving chronic apraclonidine therapy, it is especially important to monitor their post-ALT IOPs and to be prepared to treat postlaser IOP spikes using agents other than apraclonidine.

Adrenergic alpha-Agonists↗
PubMed1997

The effect of adjunctive mitomycin C in Molteno implant surgery.

PURPOSE: The purpose of the study is to assess the effect of adjunctive intraoperative mitomycin C (MMC) in Molteno drainage device implantation for patients with recalcitrant glaucomas. METHOD: Forty-nine eyes of 49 patients who underwent one-stage, single-plate Molteno device implantation with adjunctive intraoperative MMC (0.5 mg/ml) for 3 to 5 minutes (MMC group) were compared to a historic control group of 51 eyes of 51 patients (control group) who received one-stage, single-plate Molteno device implantation without MMC. Success (survival) was defined as an intraocular pressure (IOP) between 6 and 21 mmHg, inclusive, with (qualified success) or without (complete success) glaucoma medications and with no additional glaucoma surgery, phthisis, implant removal, or loss of light perception. RESULTS: Preoperative conditions were similar between the two groups. There was no significant difference in surgical survival rate between the two groups (P = 0.13, log-rank test). There also were no significant differences in the postoperative IOP levels and numbers of antiglaucoma medications between the two groups at all times (P > 0.05). Visual acuity was improved or remained within one line of preoperative visual acuity in 76.1% of the MMC group and 78.7% of the control group at 1 year after surgery (P = 0.76, chi-square test). Complications and reoperation for complications were similar in both groups (P > 0.05, chi-square test) except for the incidence of early postoperative hypotony and the total number of eyes with complications not requiring reoperation, which were more common in the MMC group (P = 0.027, 0.005, respectively, chi-square test). The most common complications included hypotony with or without a flat anterior chamber or choroidal detachment, followed by hyphema and tube plugging. CONCLUSION: Molteno device implantation with adjunctive intraoperative MMC in patients with complicated glaucoma may not offer a better chance of surgical success compared with Molteno implantation without MMC.

Adult↗
PubMed1997

Comparative study of silicone versus acrylic foldable lens implantation in primary glaucoma triple procedure.

OBJECTIVE: To compare silicone versus acrylic foldable intraocular lens (IOL) implantation in primary glaucoma triple procedure (PGTP). DESIGN: Prospective, randomized. PARTICIPANTS: A total of 79 eyes of 79 primary open-angle glaucoma (POAG) patients in need of combined surgery were randomized to a silicone IOL group (36 eyes) and acrylic IOL group (43 eyes). INTERVENTION: The study eyes underwent PGTP, which consisted of primary trabeculectomy, phacoemulsification, and posterior chamber IOL implantation. Adjunctive mitomycin C (MMC) (0.5 mg/ml for 1 minute) was used selectively only in patients with one or more risk factors for filtration failure of PGTP. MAIN OUTCOME MEASURES: Snellen visual acuity, intraocular pressure (IOP), slit-lamp biomicroscopy, and number of glaucoma medications were measured, performed, or determined preoperatively and at regular intervals postoperatively. RESULTS: There were no significant differences in the mean number of postoperative glaucoma medications at 1, 2, 3, 4-6, and 9-12 months and at last follow-up (P > 0.05); mean change in corrected visual acuity best attained (P = 0.315) or at last follow-up (P = 0.223) between the silicone and acrylic groups. Both groups had significant decreases in mean IOP and mean number of medications postoperatively at all times (P < 0.05). However, the postoperative IOP > 25 mmHg and IOP spike > 5 mmHg above preoperative IOP during the first month were significantly higher in the acrylic group (P = 0.026). The mean postoperative IOP at 1 month in the acrylic group was also significantly higher than the silicone group (14.1 +/- 5.0, 11.2 +/- 3.9, P = 0.005). Conversely, there were no significant differences in mean postoperative IOP at 2, 3, 4-6, and 9-12 months and at last follow-up between the silicone and acrylic groups (P > 0.05). Suture removal or release occurred significantly more frequently in the acrylic IOL group during the first month and the first 2 months (48.8% and 60.5%) than the silicone group (25.0% and 36.1%, P = 0.030 and 0.031, respectively). There were no significant differences in postoperative complications or surgical interventions between the two groups (P > 0.05). CONCLUSIONS: During the first year following the PGTP with selective use of MMC, there were no significant differences in the medical dependency or visual outcomes or complications between the silicone and acrylic groups. Both groups attained significant decreases in IOP postoperatively. However, the mean IOP was significantly higher in the acrylic than the silicone group at 1 month postoperatively, and postoperative IOP > 25 mmHg and IOP spike > 5 mmHg above preoperative IOP were significantly greater in the acrylic group. There were significantly more suture releases in the acrylic IOL group than the silicone IOL group in the first 2 months postoperatively.

Acrylic Resins↗
PubMed1997

Analysis of reliability indices from Humphrey visual field tests in an urban glaucoma population.

PURPOSE: Visual field assessment is extremely important in glaucoma management, but interpretation is affected by the quality of the patient's performance. The authors have investigated the reliability of visual field performance by a randomly selected sample of the chronic glaucoma population at an urban tertiary care practice. METHODS: Patient reliability in Humphrey automated visual field testing was studied in 106 randomly selected chronic open-angle glaucoma patient charts, which provided 768 tests (mean, 7.2 +/- 4.8 fields; range, 2-18 fields). Reliability criteria were established as less than 20% fixation losses, less than 33% false-negative error, and less than 33% false-positive error, as recommended by Humphrey Instruments, Inc (San Leandro, CA). RESULTS: Patients performed reliably in 61% of right eye fields, 58% of left eye fields, and 59.5% overall. Of the 106 patients, only 35 (33%) were always reliable in both eyes, whereas 8 (7.5%) were always unreliable in both eyes. The most common cause of unreliability was fixation loss (39%), whereas false-positive error (5%) and false-negative error (9%) were less frequent. A more severely depressed mean deviation correlated significantly with poorer performance on the three reliability indices, with false-negative error having the greatest correlation, followed by fixation loss and false-positive error. Corrected pattern standard deviation correlated closely only with false-negative error. Prolonged test time also correlated with all three reliability indices. Age was a significant factor for fixation loss but not for false-negative or false-positive error. CONCLUSIONS: The authors conclude that fewer than two thirds of the Humphrey visual fields were reliable with the authors' urban tertiary care population of patients with glaucoma. Relaxing the fixation loss criterion to less than 33% improved the rate of reliability to approximately 75%. The severity of glaucomatous visual field defects, test time, and age were identified as factors influencing the reliability of the Humphrey visual fields.

Aged↗
PubMed1997

Induction of brain derived neurotrophic factor mRNA by seizures in neonatal and juvenile rat brain.

Seizures have been shown to regulate neurotrophin expression in adult mammalian brain. However, there has been some controversy as to whether seizures affect neurotrophin expression in very immature brain. In the present study, we have examined the effects of seizures induced by pilocarpine following lithium pretreatment or by kainic acid on the expression of brain derived neurotrophic factor (BDNF) mRNA in developing rat brain by in situ hybridization. In adult brain, lithium/pilocarpine treatment resulted in dramatic elevations of hybridization to BDNF cRNA in neocortical and limbic brain structures. In developing brain, lithium/pilocarpine induced elevations of BDNF mRNA in the hippocampus, piriform and entorhinal cortex as early as postnatal day 7 (P7). By P12, the pattern of enhanced expression was similar to that of the adult. Maximal elevations of hybridization were present 2 to 4 h following pilocarpine injection. Electrophysiological recording demonstrated that lithium/pilocarpine treatment resulted in electrographic seizures. Pretreatment with diazepam blocked the seizures as well as the elevation of BDNF mRNA. Kainic acid induced elevations of BDNF mRNA in the CA3 subfield of the hippocampal pyramidal cell layer, but not in other brain areas in pups as young as P7. These data indicate that seizures during the neonatal and early juvenile period of brain development induce elevated BDNF mRNA expression, and that different methods of seizure induction yield different patterns of elevations in hybridization. Furthermore, BDNF may be capable of playing a role in the development of seizure susceptibility in the immature brain.

Animals↗
PubMed1997

Serum neuron-specific enolase is a marker for neuronal damage following status epilepticus in the rat.

We determined the serum concentrations of neuron-specific enolase (s-NSE) in rat pups of 1, 2, 3, and 4 weeks of age and in adult rats that were subjected to lithium-pilocarpine status epilepticus (SE). Damage to brain regions was rated on a scale of 0 (no damage) to 5 (> 50% cell loss). Rat pups of 1-2 weeks of age had a higher baseline s-NSE than the adults. Following SE, 1 week old rat pups had no elevation of s-NSE and no histologic evidence of damage. At older ages the increases in NSE ranged from 18.9 +/- 0.8 ng/ml in the 2 week old (vs. 11.5 +/- 0.5 control) to 35.8 +/- 2.1 ng/ml in the 3 week old (vs. 12.1 +/- 0.8 control). In the adult rats s-NSE increased from 5.4 +/- 0.4 in the control animals to 30.4 +/- 1.3 after SE. The different brain regions examined had distinctive ontogenic profiles for SE-induced damage. Elevation of s-NSE after SE correlated with overall histologic evidence for damage.

Animals↗
PubMed1997

Intravascular lymphomatosis: a clinicopathological study of two cases presenting as an interstitial lung disease.

AIMS: Intravascular lymphomatosis is an uncommon type of non-Hodgkin's lymphoma characterized by intravascular proliferation of neoplastic lymphoid cells. Although the tumour is basically a systemic disease, eventually involving multiple organs, primary presentation in the lung is rare. METHODS AND RESULTS: We describe the clinicopathological features of two patients with intravascular lymphomatosis presenting in the lung. One patient complained of fever, headache and chest pain; the other, of dyspnoea on exertion and headache. Both patients showed reticulonodular density on chest radiography and decreased diffusion capacity. Lung biopsy showed features characteristic of intravascular lymphomatosis. Malignant lymphoid cells were CD30 positive T-cells of anaplastic large cell type in one patient and B-cells of large cell type in the other. There was a poor response to chemotherapy and both patients died of the disease within 3 months of diagnosis. CONCLUSIONS: These cases and 10 previous reports illustrate the need to include intravascular lymphomatosis in the differential diagnosis of interstitial lung disease.

Aged↗
PubMed1997

Microplate assay of ascorbic acid in aqueous humor with bicinchoninic acid.

An inexpensive microplate assay method was developed to determine ascorbic acid in human aqueous humor samples. The method is based on the selective oxidation of ascorbic acid at alkaline pH and determination of ascorbic acid and other reducing substances in samples with bicinchoninic acid/CuSO4 before and after the alkaline treatment. The two-point measurement eliminates the effect of interfering substances, such as glucose, uric acid and glutathione, which are stable at alkaline pH. The advantages of the method are that it requires small sample volumes and allows handling of a large number of samples simultaneously.

Aqueous Humor↗
PubMed1997

Intravascular lymphomatosis of the T cell type presenting as interstitial lung disease--a case report.

Intravascular lymphomatosis (IL) is a rare and generally fatal disease characterized by proliferation of large lymphoma cells almost exclusively within the lumen of small blood vessels. The skin and central nervous systems are typically affected, but involvement of other organs, such as lung, has been described. Predominant lung involvement without cutaneous and neurologic manifestation is very rare and difficult to diagnose. Originally considered as an endothelial disorder, IL has recently been reclassified as lymphoma. Most of the cases reported are of B cell lineage with a few cases of T cell type. We describe a case of the T-cell type IL manifested clinically as an interstitial lung disease without involvement of skin and central nervous systems. Immunohistochemical studies showed the T-cell nature of the neoplastic cells in open lung biopsy sample.

Blood Vessels↗
PubMed1997

Pleomorphic adenoma of the trachea.

A case of salivary gland type pleomorphic adenoma of the trachea in a 48-year-old woman is presented. Pleomorphic adenoma is extremely rare in the trachea. The behavior of this tumor in the trachea appears to be similar to its counterpart in other sites and distinctly different from the more frequently encountered epithelial tumors.

Adenoma, Pleomorphic↗
PubMed1997

Pulmonary asbestosis: radiologic-pathologic brief report.

Pulmonary asbestosis is defined as bilateral diffuse interstitial fibrosis of the lungs caused by exposure to asbestos. Many occupations are at risk for asbestos exposure, particularly in the mining, milling, manufacturing, construction, shipbuilding, and automotive industries. Therefore, the prevalence of asbestosis should be fairly widespread. The diagnosis of asbestosis can be made on either clinical or pathological grounds. We recently encountered one case of asbestosis which was confirmed histologically. On HRCT, there was ground-glass opacity with irregular linear shadows, subpleural curvilinear lines and parenchymal bands. Neither plaque nor calcification were noted. The histologic findings observed on open-lung biopsy specimen were well in accord with those in HRCT. Many asbestos-coated bodies were present along with black dust.

Asbestosis↗
PubMed1997

Laser trabeculoplasty: how little is enough?

BACKGROUND AND OBJECTIVE: The optimal number of laser applications for argon laser trabeculoplasty in patients with primary open-angle glaucoma has not been established. The purpose of this study was to determine the fewest number of burns necessary for clinically effective intraocular pressure reduction for these patients. PATIENTS AND METHODS: Using a prospective, randomized, collaborative study, the authors examined the relationship between the number of laser trabeculoplasty burns and intraocular pressure for patients with primary open-angle glaucoma. A total of 122 patients received either 50 burns to half of the trabecular meshwork (group 1) or 35 burns to one third of the trabecular meshwork (group 2). RESULTS: The mean baseline intraocular pressures were similar between group 1 (22.3 +/- 4.1 mm Hg [mean +/- SD]) and group 2 (22.8 +/- 5.0 mm Hg) (P = .58). Intraocular pressure reduction at 9 to 12 months, although significant in both groups (group 1: 4.4 +/- 3.0 mm Hg, P < .0001; group 2: 3.9 +/- 5.1 mm Hg, P < .0001), did not differ significantly between the two groups (P = .63). CONCLUSION: This study demonstrated that 35 burns may be as clinically effective as 50 burns in reducing the intraocular pressure in primary open-angle glaucoma patients.

Aged↗
PubMed1996

Mutational analysis of the ATP-binding site in HslU, the ATPase component of HslVU protease in Escherichia coli.

HslU is the ATPase component of the ATP-dependent HslVU protease in Escherichia coli. To gain an insight into the structure and function of HslU, site-directed mutagenesis was performed to generate a mutation in the ATP-binding site of the ATPase (i.e., to replace the Lys63 with Thr). Unlike the wild-type HslU, the mutant form (referred to as HslU/K63T) could not hydrolyze ATP or support the ATP-dependent hydrolysis of N-carbobenzoxy-Gly-Gly-Leu-7-amido-4-methyl coumarin by HslV. The wild-type HslU (a mixture of monomer and dimer) formed a multimer containing 6-8 subunits in the presence of either ATP or ADP, indicating that ATP-binding, but not its hydrolysis, is required for oligomerization of HslU. However, HslU/K63T remained as a monomer whether or not the adenine nucleotides were present. Furthermore, ATP or ADP could protect HslU, but not HslU/K63T, from degradation by trypsin. These results suggest that the mutation in the ATP-binding site results in prevention of the binding of the adenine nucleotides to HslU and hence in impairment of both oligomerization and ATPase function of HslU.

ATP-Dependent Proteases↗
PubMed1996

Molecular symmetry of the ClpP component of the ATP-dependent Clp protease, an Escherichia coli homolog of 20 S proteasome.

The ClpP component Clp protease from Escherichia coli has been crystallized and examined by X-ray crystallography and self-rotation function calculations. The crystal belongs to the monoclinic space group P2(1) with unit cell dimensions of a = 196.9 A, b = 104.3 A, c = 162.4 A and beta = 98.3 degrees. The X-ray diffraction pattern extends at least to 2.5 A Bragg spacing when exposed to CuK alpha X-rays. Self-rotation function analyses indicate that the ClpP oligomer has 72-point group symmetry. This symmetry suggests that the ClpP oligomer is a tetradecamer, (ClpP)14, consisting of two heptamers, (ClpP)7 stacked on top of each other in a head-to-head fashion. The measurement of crystal density indicates that two independent copies of the ClpP oligomers are present in the asymmetric unit, giving a crystal volume per protein mass (VM) of 2.73 A3/Da and a solvent content of 54.9% (v/v). Self-rotation function calculations are consistent with the presence of two ClpP tetradecamers in the asymmetric unit. The Patterson function suggests that a translation of x = 0.5 and y = 0.5 relates a pair of ClpP oligomers in one asymmetric unit to another pair in the other asymmetric unit. And the two independent tetradecamers in one asymmetric unit are related by a relative rotation of about 18 degrees around the 7-fold axis.

Adenosine Triphosphatases↗
PubMed1996

Purification and characterization of the heat shock proteins HslV and HslU that form a new ATP-dependent protease in Escherichia coli.

The hslVU operon in Escherichia coli encodes two heat shock proteins, HslV, a 19-kDa protein homologous to beta-type subunits of the 20 S proteasomes, and HslU, a 50-kDa protein related to the ATPase ClpX. We have recently shown that HslV and HslU can function together as a novel ATP-dependent protease, the HslVU protease. We have now purified both proteins to apparent homogeneity from extracts of E. coli carrying the hslVU operon on a multicopy plasmid. HslU by itself cleaved ATP, and pure HslV is a weak peptidase degrading certain hydrophobic peptides. HslU dramatically stimulated peptide hydrolysis by HslV when ATP is present. With a 1:4 molar ratio of HslV to HslU, approximately a 200-fold increase in peptide hydrolysis was observed. HslV stimulated the ATPase activity of HslU 2-4-fold, but had little influence on the affinity of HslU to ATP. The nonhydrolyzable ATP analog, beta,gamma-methylene-ATP, did not support peptide hydrolysis. Other nucleotides (CTP, dATP) that were slowly hydrolyzed by HslU allowed some peptide hydrolysis. Therefore, ATP cleavage appears essential for the HslV activity. Upon gel filtration on a Sephacryl S-300 column, HslV behaved as a 250-kDa oligomer (i.e. 12-14 subunits), and HslU behaved as a 100-kDa protein (i.e. a dimer) in the absence of ATP, but as a 450-kDa multimer (8-10 subunits) in its presence. Therefore ATP appears necessary for oligomerization of HslU. Thus the HslVU protease appears to be a two-component protease in which HslV harbors the peptidase activity, while HslU provides an essential ATPase activity.

ATP-Dependent Proteases↗
PubMed1996

Crystal structure analyses of uncomplexed ecotin in two crystal forms: implications for its function and stability.

Ecotin, a homodimeric protein composed of 142 residue subunits, is a novel serine protease inhibitor present in Escherichia coli. Its thermostability and acid stability, as well as broad specificity toward proteases, make it an interesting protein for structural characterization. Its structure in the uncomplexed state, determined for two different crystalline environments, allows a structural comparison of the free inhibitor with that in complex with trypsin. Although there is no gross structural rearrangement of ecotin when binding trypsin, the loops involved in binding trypsin show relatively large shifts in atomic positions. The inherent flexibility of the loops and the highly nonglobular shape are the two features essential for its inhibitory function. An insight into the understanding of the structural basis of thermostability and acid stability of ecotin is also provided by the present structure.

Amino Acid Sequence↗