Biomedical subjects

S J Oh

Publications and source records attributed to S J Oh.

At least 73 records · Page 4Linked to original sources

PubMed2000

Neuronal nitric oxide synthase immunoreactive neurons in the mammalian retina.

The development of immunocytochemistry has led to a better understanding of synaptic transmission carried out by neuroactive substances in the mammalian brain, including the retina. In the mammalian retina, nitric oxide (NO) is widely accepted as a neuromodulator. Histochemistry based on NADPH-d and immunocytochemistry based on nitric oxide synthase (NOS) have been used to identify the presence of nitric oxide in the mammalian retina. Certain types of amacrine cells and a class of displaced amacrine cells have been labeled consistently in all mammalian retinae studied to date. Other cell types showing NADPH-d reactivity or NOS immunoreactivity varied between species. NADPH-d reactive or NOS immunoreactive amacrine cells may serve as a source of NO for amacrine, bipolar, and ganglion cells in the inner retina, whereas interplexiform cells, bipolar cells, and horizontal cells may serve as a source of NO for the outer retina of mammals.

Animals↗

PubMed2000

Identification of p53 gene mutations in breast cancers and their effects on transcriptional activation function.

Somatic mutations in the p53 tumor suppressor gene are the most common genetic alterations found in human malignancies. In the present study, we studied 36 primary human breast carcinomas, using a polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and sequencing analysis of exons 2 through 9 for the presence of p53 gene mutations. Six of 36 (17%) breast cancers contained mutations within the core domain of the p53 protein responsible for sequence-specific DNA binding (codons 102-292); all 5 missense mutations clustered between codons 240 and 291 (codons 240, 243, 250, 285, and 291), whereas one nonsense mutation occurred at codon 199. By using recombinant PCR in vitro mutagenesis, we introduced point mutations at codons 199 from Gly to stop (gly199stop), 240 from Ser to Ile (ser240Ile), 250 from Pro to Ala (pro250ala), 285 from Glu to Lys (glu285lys), and 291 from Lys to Asn (lys291asn), and all the p53 sequences were subcloned into the CMVneoBam vector under the control of the cytomegalovirus (CMV) promoter. To test whether the mutants p53 were functionally wild-type (wt) or mutant, we transfected them to p53-null Saos-2 cells with a reporter plasmid containing a p53-responsive element, and performed chloramphenicol acetyltransferase (CAT) assay. Transient CAT assay for transcriptional activation revealed that one group, including gly199stop, ser240ile, glu285lys, and lys291asn, abolished the transcriptional activity, whereas the other group, including pro250ala, retained stronger transcriptional transactivation activity than that of wt p53.

Adult↗

PubMed2000

Upregulation of ciliary neurotrophic factor in reactive Müller cells in the rat retina following optic nerve transection.

We have investigated the expression and cellular localization of ciliary neurotrophic factor (CNTF) in the rat retina following optic nerve transection. In the normal retina, CNTF immunoreactivity was restricted to profiles in the ganglion cell layer. Following optic nerve transection, immunoreactivity appeared in Müller cell somata and processes and its intensity increased between three and seven days post-lesion. Quantitative evaluation by immunoblotting confirmed that CNTF expression increased continuously up to 7 days after optic nerve transection (to 430% of control levels), but decreased again to 250% of controls at 4 weeks post-lesion. Our findings suggest that CNTF supplied by Müller cells may play a protective role for axotomized ganglion cells in the rat retina.

Animals↗

PubMed2000

Increased expression of ciliary neurotrophic factor receptor alpha mRNA in the ischemic rat retina.

Using in situ hybridization, we investigated the expression of ciliary neurotrophic factor receptor ((CNTFRalpha) mRNA in the rat retina rendered ischemic by elevation of the intraocular pressure (IOP). The IOP was increased to 120 mmHg and maintained for 60 min. The rats were sacrificed on the day of reperfusion (DRP) 1, 3, 7, 14, and 28. In the normal retina, the signal for CNTFRalpha mRNA was present in retinal cells in the inner nuclear layer (INL) and in the ganglion cell layer (GCL). On DRP 1, numerous cells in the INL and GCL showed a CNTFRalpha mRNA signal. From DRP 3 onwards, CNTFRalpha mRNA appeared in photoreceptor cells located in the outer part of the outer nuclear layer. The signal in these cells increased up to DRP 14 and then decreased at DRP 28. Our findings suggest that cells expressing CNTFRalpha mRNA may resist the degenerative processes induced by ischemic insult in the rat retina.

Animals↗

PubMed2000

The expression and cellular localization of brain/kidney protein in the rat retina.

Brain/kidney (B/K) protein is a new protein of 474 amino acids, which contains two C2 domains structurally homologous to those present in synaptotagmins. The expression of B/K protein was identified in the rat retina and B/K protein immunoreactivity was localized to a number of ganglion cells, a few amacrine cells and the radial processes of Müller cells. Thus, B/K protein appears to be important in the homeostasis in these cells of the rat retina.

Animals↗

PubMed2000

Ganglion cells of the rat retina show osteopontin-like immunoreactivity.

Osteopontin (OPN) is a negatively charged, highly acidic glycosylated phosphoprotein that contains an GRGDS amino acid sequence, characteristic of proteins that bind to integrin receptors, thereby playing crucial roles in a number of physiological processes. This study was conducted to examine the expression of OPN in the rat retina by Northern blot analysis, Western blot analysis and immunocytochemistry. The expression of OPN was identified in the retina and OPN-like immunoreactivity was present in a number of ganglion cells. Thus, OPN appears to be important in the retinal homeostasis.

Animals↗

PubMed2000

The immunocytochemical localization of neuronal nitric oxide synthase in the developing rat retina.

The localization of nitric oxide synthase (NOS) was investigated in the developing rat retina by immunocytochemistry and western blot analysis, using an antiserum directed against neuronal NOS. NOS-labeled cells were first detected at postnatal day 5 (P5) in the inner row of the neuroblastic layer. These cells were considered to correspond to the type 1 cell of the adult rat retina. Type 2 cells, characterized by a small soma and weak immunoreactivity, and a class of displaced amacrine cells were detected at P9 and P7, respectively. By P14 or P15, the time of eye opening, NOS immunoreactivity appeared in some bipolar cells. NOS was first expressed at the protein level at P9. Thereafter, quantitative evaluation by immunoblotting confirmed that the intensity of the immunoreactive bands increased abruptly, reaching the same value as is found in the adult retina at P21. Our results demonstrate that differentiation of NOS-labeled cells follows a discrete developmental pattern and is most active during the 2nd postnatal period in the rat retina.

Animals↗

PubMed2000

Expression of tenascin-C in astrocytic tumors: its relevance to proliferation and angiogenesis.

BACKGROUND: The expression and distribution of the extracellular matrix protein tenascin-C (TN-C) may be enhanced in human astrocytomas. The purpose of this study is to evaluate the expression of TN-C according to histological malignancy of tumor cells and its relevance to neoplastic angiogenesis in human astrocytic tumors. METHODS: Between 1994 and 1998, 52 astrocytic tumor specimens including 4 pilocytic astrocytomas, 13 astrocytomas, 3 anaplastic astrocytomas, and 32 glioblastomas were used in this study. A retrospective analysis was performed to evaluate a statistical correlation between TN-C expression and proliferative indices. We characterized the expression of TN-C in neoplastic vessels, around individual tumor cells as a tumor network, and in tumor cells by immunohistochemistry using antibodies against human TN-C. The proliferative indices were also investigated by immunostaining with the MIB-1 antibody against the Ki-67 proliferation antigen. RESULTS: TN-C immunoreactivity was found to be enhanced in tumor vessels and tumor networks of high-grade astrocytic tumors. The vascular TN-C deposition was greater in high-grade than in low-grade astrocytic tumors (p < 0.05). Its expression was the most intense in glioblastomas. Proliferation indices increased with tumor grade and MIB-1 labeling index (LI) was highest in glioblastomas. Moreover, expression of TN-C in tumor vessels was correlated with proliferative indices. CONCLUSIONS: Our data show that TN-C in human astrocytic tumors may be identified as a factor contributing to malignant progression. And also, enhanced expression of TN-C in tumor vessels having a high proliferative index indicates that TN-C could be involved in neoplastic angiogenesis.

Adolescent↗

PubMed2000

Radiolabeling of paclitaxel with electrophilic 123I.

123I-Labeled paclitaxel, [123I]-1 was prepared by electrophilic aromatic radioiodination of 3'-N-(p-trimethylstannylbenzoyl)-3'-debenzoylpaclitaxel 2 with 123I- in the presence of peracetic acid.

Antineoplastic Agents, Phytogenic↗

PubMed2000

Turns-amplitude analysis and motor unit potential analysis in myasthenia gravis.

OBJECTIVES: The aims of this study were to investigate myopathic changes in myasthenia gravis (MG) by using turns-amplitude analysis (TAA) and quantitative motor unit potential duration analysis (MUPan), to correlate myopathic changes with severity and duration of the disease and the results of diagnostic tests including repetitive nerve stimulation test (RNS), single fiber electromyography (SFEMG), and anti-acetylcholine receptor antibody (AChR-ab), and to compare the sensitivities of these two methods in detecting myopathic changes in MG. MATERIALS AND METHODS: We studied both MUPan and TAA in 32 patients with MG. RESULTS: The MUPan study showed myopathic changes in 12 patients (37.5%); TAA revealed a myopathic pattern in 4 (12.5%) and a neurogenic pattern in 4 cases (12.5%). Two of the 4 patients with a myopathic change by TAA also had short-duration mean MUP on the MUPan. No statistically significant association was found between the myopathic changes either by MUPan or TAA, and the various clinical and laboratory features. CONCLUSION: We conclude that MUPan is a more sensitive method than TAA in showing myopathic changes in MG, and that TAA is of limited help in demonstrating them.

Adolescent↗

PubMed2000

Active properties of the urinary bladder: in vitro comparative studies between adult and neonatal rats.

OBJECTIVE: To determine, using in vitro comparative studies, developmental aspects associated with the active properties of the urinary bladder in neonatal and adult rats. MATERIALS AND METHODS: Urinary bladders were removed from neonatal (1-3 days old) and adult (15 weeks old) male Sprague-Dawley rats. Anterior longitudinal muscle strips were obtained from each group and isometric tensions recorded. Nerve-mediated contractions elicited by electrical field stimulation (0.8 ms pulse) or carbachol-induced contractile responses in neonatal and adult bladder strips were compared. Contractile tensions were normalized using the wet weight of the bladder strip or by using the percentage contraction induced by 60 mmol/L KCl. RESULTS: Nerve-mediated contractile responses showed that the muscarinic component predominated in the neonatal rat bladder, which contrasted with the predominant purinergic components in adult bladder. The pattern of spontaneous activity and carbachol-induced contraction differed in the two groups. Small spontaneous contractions in the basal state occurred in adult bladder strips, while short-lived large spontaneous contractions were present in neonatal strips. The amplitude of carbachol-induced contractions generated in the neonatal bladder was larger than that in the adult bladder. In addition, the time to achieve peak contraction elicited by carbachol (5 micromol/L) was shorter in the neonatal bladder. Repetitive carbachol applications induced an attenuation of the contractile response (desensitization), but the neonatal bladder was more resistant to desensitization than the adult bladder. CONCLUSIONS: These results show that nerve-mediated or agonist-induced contractile patterns, and spontaneous activity, in the neonatal bladder differ from those of the adult bladder in rats. The results suggest that in addition to neural immaturity, there are functional differences between the bladders of adult and neonatal rats.

Adenosine Triphosphate↗

PubMed2000

The management of children with complete ureteric duplication: selective use of uretero-ureterostomy as a primary and salvage procedure.

OBJECTIVE: To determine the optimum management of duplex urinary tracts with refluxing or obstructed units. PATIENTS AND METHODS: Sixty-three children (19 boys and 44 girls) with complete duplex-system anomalies (84 duplex system units) who underwent corrective surgery by one surgeon (H.C.) between March 1983 and June 1997 were reviewed, analysing their diagnosis and treatment. RESULTS: Most children had presented with urinary tract infection; a ureterocele was found in 26 renal units, reflux in 12 and a combined anomaly in 18. Ectopic insertion of the ureter causing incontinence was found in six and ureteric obstruction in nine ureteric units. Patients were managed so that whenever possible, functional renal tissue was preserved; thus surgical strategies were basically staged, conservative, and planned preoperatively on the basis of renal function. Initial surgery was undertaken in 71 units (all patients; ureterocele incision in 12, upper pole nephrectomy in 30, ureteric reimplantation in 14, uretero-ureterostomy in 13 and others in two). The median (range) follow-up was 7.6 (2.1-16) years. Secondary procedures were undertaken in 24 units (34%); ureterocele incision (11 of 12 units) was the most common procedure of additional surgery, followed by ureteric reimplantation (six of 27 units), upper pole nephrectomy (eight of 37 units) and uretero-ureterostomy (two of 18 units). CONCLUSIONS: Uretero-ureterostomy was the most successful nephron-sparing additional operation. When the upper pole is salvageable, uretero-ureterostomy may be the preferred alternative for managing complete duplex system anomalies.

Adolescent↗

PubMed2000

Selective neuronal survival and upregulation of PCNA in the rat inner retina following transient ischemia.

In this study we investigated the extent and time course of neuronal cell death and the regulation of the proliferating cell nuclear antigen (PCNA) in the different retinal cell layers following ischemia-reperfusion injury. Retinal ischemia was induced by controlled elevation of the intraocular pressure for a duration of 60 min. Changes in thickness and cell numbers in the retinal cell layers were analyzed at various time points (1 h to 4 weeks) after reperfusion. In parallel, apoptotic cell death was determined by the TUNEL method and the expression of PCNA analyzed by immunocytochemistry. In addition, we tested whether PCNA is expressed in neurons by double immunocytochemistry. The reduction in thickness was found to be less pronounced in the inner nuclear layer (INL). Correspondingly, cell numbers decreased by only 33% in the inner retina, but by more than 80% in the outer nuclear layer (ONL). Alterations in glial cell numbers did not contribute significantly to postischemic changes in the INL and ONL as assessed by using immunocytochemical markers for microglial and Müller cells. The time course of cell death determined by the TUNEL technique also differed markedly in the retinal layers being rapid and transient in the inner retina but delayed and prolonged in the ONL. PCNA immunoreactivity was undetectable in the normal retina, but was specifically induced in neurons of the inner retina within 1 h after reperfusion and was sustained for at least 4 weeks. We conclude that in contrast to photoreceptors in the ONL, a significant proportion of inner retinal neurons is resistant to ischemic insult induced by transiently increased intraocular pressure and that PCNA may possibly play a role in the selective postischemic survival of these cells.

Animals↗

PubMed2000

Fist position for skin grafting on the dorsal hand: II. Clinical use in deep burns and burn scar contractures.

The fundamental problem in all types of hand burns is a loss of skin and subsequent deformities. The goal of skin grafting on the dorsal hand is to graft a sufficient amount of skin, as much as the original amount, and to restore normal hand function without secondary deformities. The safe, or Michigan, position commonly has been used for immobilizing the hand. However, this position is to protect hand function rather than to provide for adequate skin grafting. This institution has developed a new hand position (the fist position) for grafting the greatest amount of skin on the dorsal side of the hand. In the fist position, the hand is positioned flexing all joints of the wrist and the fingers and maximally stretching the dorsal surface of the hand before skin grafting. Ten hands with deep second- or third-degree burn (n = 6) and burn scar contracture (n = 4) of the dorsal hand in eight patients were treated with split-thickness skin grafting after immobilizing in the fist position. The burns and contractures involved nearly the total area of the dorsal hand. The hand was kept in the fist position for 7 to 9 days after skin grafting. Excellent functional and cosmetic results were observed in all cases during the follow-up period of 6 months to 2 years. Complications resulting from hand immobilization for a short period did not occur. The fist position may be a proper hand position for skin grafting to reconstruct the dorsal hand.

Adolescent↗

PubMed2000

Rice cooker steam hand burn in the pediatric patient.

Burn injuries often lead to significant cosmetic and functional deformity. In the Orient, household electric rice cookers have caused a significant number of steam burns to infant hands. The clinical course and treatment outcome of these burns have been studied retrospectively in a review of the medical records of 79 pediatric patients treated for acute hand steam burns and of 38 other patients who underwent correction for postburn contracture. Electric rice cookers caused all of the acute pediatric steam burns treated at our institute. Of the 81 hands treated between 1995 and 1998, 38.3 percent healed with conservative treatment and 61.7 percent required skin grafting. The volar aspects of the index and middle fingers were those most frequently involved. Eighteen of 36 hands (50 percent) grafted with split-thickness skin developed late contractures requiring additional procedures. Among the 38 patients who underwent correction for postburn deformity, initial treatment was split-thickness grafting for 60.5 percent, full-thickness skin grafting for 7.9 percent, and spontaneous healing for 31.6 percent. Awareness among medical personnel and continued public education should be promoted to help prevent this unique type of pediatric steam burn from occurring.

Burns↗

PubMed2000

A micromachined silicon depth probe for multichannel neural recording.

A process of making a new type of silicon depth-probe microelectrode array is described using a combination of plasma and wet etch. The plasma etch, which is done using a low temperature oxide (LTO) mask, enables probe thickness to be controlled over a range from 5 to 90 mu. Bending tests show that the probe's mechanical strength depends largely on shank thickness. More force can be applied to thicker shanks while thinner shanks are more flexible. One can then choose a thickness and corresponding mechanical strength using the process developed. The entire probe shaping process is performed only at low temperature, and thus is consistent with the standard CMOS fabrication. Using the probe in recording from rat's somatosensory cortex, we obtained four channel simultaneous recordings which showed clear independence among channels with a signal-to-noise ratio performance comparable with that obtained using other devices.

Animals↗

PubMed2000

Metastatic tumors in the sellar and parasellar regions: clinical review of four cases.

Metastatic tumors in the sellar and parasellar regions are uncommon and rarely detected in clinical practice. We present four cases of sellar and parasellar metastatic tumors, which metastasized from distant organ in one case and extended directly from adjacent structures in three. Common presenting symptoms were cranial neuropathies, headache and facial pain. Invasion into the cavernous sinus was noted in all cases. We report rare cases of sellar and parasellar metastases. Also, we should consider the possibility of metastasis in these regions for patients who showed the above clinical presentations in systemic cancer patients. In extensive diseases, transient symptomatic relief could be obtained by direct surgical management, even in restricted degree.

Adenocarcinoma↗

PubMed1999

Survey of the Korean population for 9 short tandem repeat loci.

The short tandem repeats with repeat units ranging from two to several nucleotides became a powerful tool in the field of forensic identification and paternity determination as well as for research in human gene mapping. Allele and genotype frequencies for 9 short tandem repeats including HUMCSF1PO, HUMTH01, HUMPLA2A1, HUMF13A01, HUMCYAR04, HUMLIPOL, HUMHPRTB, HUMCD4, and HUMFABP were determined using PCR and subsequent analysis of the PCR products by denaturing polyacrylamide gel electrophoresis followed by silver-staining. DNA samples were obtained from about 100 Korean people and amplified in a thermocycler adopting glass capillaries rather than traditional tubes. We found that the bovine serum albumin was an essential additive for the capillary PCR, presumably to coat the inner surface of the capillary which may adsorb Taq DNA polymerase. The capillary thermocycler was very effective in reducing the cycling time such that most of the amplification reactions could be finished within 30 min albeit the PCR product was less than that for the tube systems. All loci except HUMHPRTB met the Hardy-Weinberg expectations according to the exact test. The cumulative power of discrimination (PD) was 0.9999998 and the power of exclusion (POE) for the paternity test was a little low, being 0.9873989.

Alleles↗