PubMed Health⌕ Search

Biomedical subjects

T S Park

Publications and source records attributed to T S Park.

At least 19 recordsLinked to original sources
PubMed2001

Cerebral protection by hypoxic preconditioning in a murine model of focal ischemia-reperfusion.

Sublethal periods of hypoxia or ischemia can induce adaptive mechanisms to protect against subsequent lethal ischemic insults in a process known as ischemic preconditioning. In the present study, we developed a murine model of cerebral preconditioning using several common strains of adult mice. Animals were exposed to sublethal hypoxia (11% oxygen for 2 h) 48 h prior to a 90 min period of transient focal middle cerebral artery occlusion, induced by an intraluminal filament; injury was assessed 24 h later by TTC staining. Infarct volume in hypoxia-preconditioned animals was reduced 46%, 58%, and 64% in C57Bl/6, 129SvEv, and Swiss-Webster ND4 mice relative to their respective untreated controls. This non-invasive murine model of ischemic tolerance should be useful for elucidating the molecular basis of this protection using transgenic and knockout mice.

Animals↗
PubMed2001

Case report: diabetic muscle infarction presenting as knee arthralgia.

Diabetic muscle infarction is a rare complication of diabetes and has characteristic clinical features including acute onset of pain with painful swelling, most commonly in the thigh or calf muscle, which gradually improves to complete resolution. Recently we experienced a case of diabetic muscular infarction presenting as knee joint pain due to involvement of the proximal portion of the leg muscle, which site has not been reported previously. This case shows that diabetic muscle infarction may involve sites other than the thigh and calf areas and should be considered in the differential diagnosis of knee arthralgia.

Aged↗
PubMed2001

Inhibition of return in children with perinatal brain injury.

Inhibition of return is a bias in attention that reduces the likelihood of returning attention to previously viewed locations. This attention bias develops during the first 6 months of life and is putatively mediated by midbrain structures. The present study evaluated the effects of perinatal lesions on the development of inhibition of return. Thirty-three children with perinatal injury resulting in spastic diplegic cerebral palsy were grouped based on magnetic resonance exams. Children with anterior (n = 5), posterior (n = 12), diffuse (n = 8), or no apparent (n = 8) lesions were compared with a group of age-matched children without neurologic injury (n = 39) on an orienting task designed to elicit inhibition of return. Short-delay trials demonstrated grossly intact facilitation of attention for all groups. Long-delay trials that produced inhibition of return in the control and posterior injury groups indicated a disruption of inhibition of return in the groups with anterior and diffuse lesions. The findings are consistent with previous reports that anterior regions are important for the developing attention system, and that bilateral injury can result in unilateral disruption of visual attention.

Attention↗
PubMed2001

Roentgenographic assessment of acromial morphology using supraspinatus outlet radiographs.

PURPOSE: The purpose of this study was to offer objective and standardized criteria for classifying acromial morphology. TYPE OF STUDY: Blinded study. METHODS: Two of the authors independently classified 106 supraspinatus outlet radiographs (SOR), obtained from 100 skeletally mature patients with impingement syndrome of the shoulder, using both Bigliani's and Park's standardized criteria. The same authors classified the 106 SOR again using the same criteria 2 weeks later. In addition, 2 orthopaedic residents independently classified the same SOR on the basis of the Bigliani and Park criteria in the same manner. RESULTS: The rate of agreement was 66.0% (70 of 106) on the basis of Bigliani's criteria and 95.3% (101 of 106) on the basis of Park's criteria. The interobserver reliability coefficient of the 2 authors the first time was 0.448 (poor) and 0.914 (good to excellent). Their mean intraobserver reliability coefficient was 0.834 (good to excellent) and 0.87 (good to excellent) each. For the 2 orthopaedic residents, the rate of agreement was 58.5% (62 of 106) on the basis of Bigliani's criteria and 86.8% (92 of 106) on the basis of Park's criteria, and the interobserver reliability coefficient the first time was 0.28 (poor) and 0.77 (good to excellent) each. The mean intraobserver reliability coefficient was 0.738 (fair) and 0.844 (good to excellent) each. CONCLUSIONS: In conclusion, regarding the classification for acromial morphology, Park's standardized criteria were far more objective, reliable, and reproducible rather than Bigliani's criteria through naked eye observations, especially for distinguishing the type II and type III acromion.

Acromion↗
PubMed2001

Methods for evaluation of peripheral neurovascular dysfunction.

Measurement of skin blood flow is a sensitive marker of C-fiber neurovascular dysfunction. It precedes development of abnormalities in diabetes mellitus, correlates with in vivo indices of the metabolic syndrome, and may be a "benchmark" for future studies on agents to improve microvascular dysfunction in diabetes mellitus. Skin blood flow can be measured under basal and stimulated conditions. There are different methods of evaluation. Iontophoresis and microdialysis are novel methods of drug delivery and the latter may be used as a means of extracting analytes in the skin. Theses methods are not invasive (iontophoresis) or minimally invasive (microdialysis). They can be performed repeatedly and safely in most patients. The use of microdialysis may be limited by sampling only water-soluble molecules. An alternative to microdialysis is iontophoresis, which works better with polar molecules. A combination of microdialysis and iontophoresis techniques can be useful in assessment of the pharmacokinetics of polar and nonpolar agents and the physiology and pathophysiology of the skin neurovascular system.

Diabetic Angiopathies↗
PubMed2001

Cell cycle progression and cell polarity require sphingolipid biosynthesis in Aspergillus nidulans.

Sphingolipids are major components of the plasma membrane of eukaryotic cells and were once thought of merely as structural components of the membrane. We have investigated effects of inhibiting sphingolipid biosynthesis, both in germinating spores and growing hyphae of Aspergillus nidulans. In germinating spores, genetic or pharmacological inactivation of inositol phosphorylceramide (IPC) synthase arrests the cell cycle in G(1) and also prevents polarized growth during spore germination. However, inactivation of IPC synthase not only eliminates sphingolipid biosynthesis but also leads to a marked accumulation of ceramide, its upstream intermediate. We therefore inactivated serine palmitoyltransferase, the first enzyme in the sphingolipid biosynthesis pathway, to determine effects of inhibiting sphingolipid biosynthesis without an accumulation of ceramide. This inactivation also prevented polarized growth but did not affect nuclear division of germinating spores. To see if sphingolipid biosynthesis is required to maintain polarized growth, and not just to establish polarity, we inhibited sphingolipid biosynthesis in cells in which polarity was already established. This inhibition rapidly abolished normal cell polarity and promoted cell tip branching, which normally never occurs. Cell tip branching was closely associated with dramatic changes in the normally highly polarized actin cytoskeleton and found to be dependent on actin function. The results indicate that sphingolipids are essential for the establishment and maintenance of cell polarity via control of the actin cytoskeleton and that accumulation of ceramide is likely responsible for arresting the cell cycle in G(1).

Actins↗
PubMed2001

Selective posterior rhizotomy and intrathecal baclofen for the treatment of spasticity.

Spasticity occurs in children and adults due to a wide range of conditions, including cerebral palsy, head and spinal cord trauma, cerebrovascular accidents and multiple sclerosis. Multiple treatment options have been described, including medical and surgical treatments. Medical treatments include intramuscular botulinum A toxin, oral baclofen and supportive bracing. Surgical approaches include selective posterior rhizotomy, intrathecal baclofen and orthopedic procedures to address deformities. Many reports have been published on these different treatment options, but rarely has a comparison been made between them. Therefore, this review is aimed at comparing selective posterior rhizotomy and intrathecal baclofen injection for spasticity due to cerebral palsy, especially in children.

Baclofen↗
PubMed2001

Prospective study of recovery following neonatal brachial plexus injury.

The prognosis for recovery from brachial plexus injury sustained at or before birth is generally favorable. However, roughly 10% of these infants remain profoundly weak and later exhibit functional disability in the affected arm. Early identification of these at-risk infants would be helpful in selecting patients for surgical management. In our prospective study, 80 infants with brachial plexus injury were examined on a monthly basis. Complete recovery occurred in 53 (66%); in 9 (11%), mild weakness persisted. In each child, recovery to antigravity strength in the biceps, triceps, and deltoid was noted by 6 months of age. Moderate arm weakness persisted in 7 children (9%); none had antigravity strength in the deltoid at age 6 months. Eleven children (14%) had severe permanent weakness (mean follow-up: 4.4 years). At age 6 months, these individuals exhibited at best 2/5 strength proximally and typically 0-1/5 strength in the wrist and finger extensors. Our results demonstrate that detailed strength testing up to 6 months of age predicts not only complete recovery of neonatal brachial plexus injury but also those children destined for long-term severe disability.

Birth Injuries↗
PubMed2001

Dermal neurovascular dysfunction in type 2 diabetes.

OBJECTIVE: To review evidence for a relationship between dermal neurovascular dysfunction and other components of the metabolic syndrome of type 2 diabetes. RESEARCH DESIGN AND METHODS: We review and present data supporting concepts relating dermal neurovascular function to prediabetes and the metabolic syndrome. Skin blood flow can be easily measured by laser Doppler techniques. RESULTS: Heat and gravity have been shown to have specific neural, nitrergic, and independent mediators to regulate skin blood flow. We describe data showing that this new tool identifies dermal neurovascular dysfunction in the majority of type 2 diabetic patients. The defect in skin vasodilation is detectable before the development of diabetes and is partially correctable with insulin sensitizers. This defect is associated with C-fiber dysfunction (i.e., the dermal neurovascular unit) and coexists with variables of the insulin resistance syndrome. The defect most likely results from an imbalance among the endogenous vasodilator compound nitric oxide, the vasodilator neuropeptides substance P and calcitonin gene-related peptide, and the vasoconstrictors angiotensin II and endothelin. Hypertension per se increases skin vasodilation and does not impair the responses to gravity, which is opposite to that of diabetes, suggesting that the effects of diabetes override and counteract those of hypertension. CONCLUSIONS: These observations suggest that dermal neurovascular function is largely regulated by peripheral C-fiber neurons and that dysregulation may be a component of the metabolic syndrome associated with type 2 diabetes.

Diabetes Mellitus, Type 2↗
PubMed2001

Platelet dysfunction in type 2 diabetes.

Insulin resistance is a uniform finding in type 2 diabetes, as are abnormalities in the microvascular and macrovascular circulations. These complications are associated with dysfunction of platelets and the neurovascular unit. Platelets are essential for hemostasis, and knowledge of their function is basic to understanding the pathophysiology of vascular disease in diabetes. Intact healthy vascular endothelium is central to the normal functioning of smooth muscle contractility as well as its normal interaction with platelets. What is not clear is the role of hyperglycemia in the functional and organic microvascular deficiencies and platelet hyperactivity in individuals with diabetes. The entire coagulation cascade is dysfunctional in diabetes. Increased levels of fibrinogen and plasminogen activator inhibitor 1 favor both thrombosis and defective dissolution of clots once formed. Platelets in type 2 diabetic individuals adhere to vascular endothelium and aggregate more readily than those in healthy people. Loss of sensitivity to the normal restraints exercised by prostacyclin (PGI(2)) and nitric oxide (NO) generated by the vascular endothelium presents as the major defect in platelet function. Insulin is a natural antagonist of platelet hyperactivity. It sensitizes the platelet to PGI(2) and enhances endothelial generation of PGI(2) and NO. Thus, the defects in insulin action in diabetes create a milieu of disordered platelet activity conducive to macrovascular and microvascular events.

Animals↗
PubMed2001

Large cell/anaplastic medulloblastomas and medullomyoblastomas: clinicopathological and genetic features.

OBJECT: Medulloblastoma is the most common malignant central nervous system neoplasm found in children. A distinct variant designated large cell/anaplastic (LC/A) medulloblastoma is characterized by frequent dissemination of cerebrospinal fluid (CSF) at presentation and a more aggressive clinical course. The authors report on their examination of the clinicopathological and genetic features of seven such cases encountered at their institution. METHODS: Eighty cases of medulloblastomas were reviewed and seven (8.8%) of these were believed to fit the histological and immunohistochemical criteria for LC/A medulloblastoma. In three cases (43%) either desmoplastic or classic medulloblastoma was the underlying subtype, and in two cases (28%) the LC/A tumor was found within the setting of medullomyoblastoma. Fluorescence in situ hybridization was used in six of the seven cases to characterize the presence of isochromosome 17q, deletion of chromosome 22q (a deletion characteristically found in atypical teratoid/rhabdoid tumors), and c-myc amplification. The patients' clinical histories revealed CSF dissemination in all cases and lymph node metastasis in one case. Isochromosome 17q was found in five (83%) of six cases. Evidence of chromosomal gains indicated aneuploidy in three tumors (50%), and amplification of c-myc was found in three tumors (50%). No 22q deletions were encountered. CONCLUSIONS: A high percentage of LC/A medulloblastomas arise within a background of typical medulloblastomas or medullomyoblastomas. As is the case in conventional medulloblastomas, the presence of 17q is a common early tumorigenic event; however, in a significant percentage of specimens there is also evidence of aneuploidy and/or amplification of c-myc. These findings indicate that LC/A morphological characteristics reflect a more advanced tumor stage than that found in pure medulloblastomas or in typical medullomyoblastomas.

Adolescent↗
PubMed2001

Recurrent pseudotumor cerebri in systemic lupus erythematosus: a case report.

Pseudotumor cerebri is an uncommon manifestation of neuropsychiatric systemic lupus erythematosus (SLE), and is characterized by an elevated intracranial pressure, papilledema with occasional abducens nerve paresis, absence of a space-occupying lesion or ventricular enlargement, and normal cerebrospinal fluid chemical and hematological constituents. Pseudotumor cerebri has been reported in a few sporadic cases in patients with systemic lupus erythematosus. However, the recurrent pseudotumor cerebri in patients with systemic lupus erythematosus which has been rarely reported, has not been reported in Korea. We experienced a 30-yr-old female patient with SLE who was presented with second attack of severe intractable headache. She was diagnosed pseudotumor cerebri twice and successfully treated with corticosteroid. Headache is the common symptom in patients with neuropsychiatric SLE and attributable to various causes. We suggest that it is important to define the cause of headache in patients with SLE and pseudotumor cerebri should be included in the spectrum of clinical manifestations during the course of SLE as a cause of headache.

Adult↗
PubMed2000

Electrophysiological evidence for afferent nerve fibers in human ventral roots.

This study was designed to test the hypothesis that ventral roots in humans contain afferent nerve fibers. We made direct electrophysiological recordings of compound nerve action potentials in dorsal and ventral roots in children undergoing selective dorsal rhizotomy for spastic cerebral palsy. We stimulated the saphenous or sural nerves, which are pure sensory nerves, with electrical stimuli while systematically recording from ventral and dorsal roots from L3 to S2. In addition to the dorsal root nerve action potentials which we expected, we found smaller compound nerve action potentials, which were clearly afferent, in the ventral roots. This confirms the limited amount of experimental evidence that ventral roots do contain some afferent nerve fibers. The functional significance of these observations is not yet clear.

Action Potentials↗
PubMed2000

Derivation and characterization of pluripotent embryonic germ cells in chicken.

Embryonic germ (EG) cell lines established from primordial germ cells (PGCs) are undifferentiated and pluripotent stem cells. To date, EG cells with proven germ-line transmission have been completely established only in the mouse with embryonic stem (ES) cells. We isolated PGCs from 5.5-day-old (stage 28) chicken embryonic gonads and established a putative chicken EG cell line with EG culture medium supplemented with stem cell factor (SCF), leukemia inhibitory factor (LIF), basic fibroblast growth factor (bFGF), interleukin-11 (IL-11), and insulin-like growth factor-I (IGF-I). These cells grew continuously for ten passages (4 months) on a feeder layer of mitotically active chicken embryonic fibroblasts. After several passages, these cells were characterized by screening with the periodic acid-Schiff reaction, anti-SSEA-1 antibody, and a proliferation assay. The chicken EG cells maintained characteristics of gonadal PGCs and undifferentiated stem cells. When cultured in suspension, the chicken EG cells successfully formed an embryoid body and differentiated into a variety of cell types. The chicken EG cells were injected into stage X blastodermal layer and produced chimeric chickens with various differentiated tissues derived from the EG cells. Chicken EG cells will be useful for the production of transgenic chickens and for studies of germ cell differentiation and genomic imprinting.

Alkaline Phosphatase↗
PubMed2000

Measurement of femoral neck anteversion in 3D. Part 1: 3D imaging method.

Femoral neck anteversion is the torsion of the femoral head with reference to the distal femur. Conventional methods that use cross-sectional computed tomography (CT), magnetic resonance or ultrasound images to estimate femoral anteversion have met with several problems owing to the complex, three-dimensional (3D) structure of the femur. These problems include not only the difficulty of defining the direction of the femoral neck axis and condylar line but also the dependency upon patient positioning. In particular, the femoral neck axis, the direction of the femoral head, known as the major source of error, is difficult to determine from either a single or several two-dimensional (2D) cross-sectional images. A new method has been devised for the measurement of femoral anteversion using the 3D imaging technique. 3D reconstructed CT images from the femoral head and trochanter to the distal femur are used to measure the anteversion. It is necessary to remove the soft tissue from the CT images and extract just the bone part. Then, the femoral anteversion is measured from a computer-rendered femur image. The 3D imaging method is compared with both the conventional 2D method and the physical method using 20 dried femurs. For the physical method, which is used as a reference value, a special apparatus is devised. The average difference between the results of the physical method and those of the 2D CT method is 5.33 degrees. The average difference between the results of the physical method and those of the 3D imaging method is 0.45 degrees. Seventy-four patients, who suffer from toe-in-gait disease, are tested to compare the 3D imaging method with the conventional 2D CT method. The average difference between the 2D and 3D methods is 8.6 degrees, and the standard is 7.43 degrees. This method provides a very accurate and reliable measurement of femoral anteversion, as it is virtually equivalent to the direct measurement of bisected dried femur in vitro.

Adolescent↗
PubMed2000

Measurement of femoral neck anteversion in 3D. Part 2: 3D modelling method.

Femoral neck anteversion is the torsion of the femoral head with reference to the distal femur. Conventional methods that use cross-sectional computed tomography (CT), magnetic resonance or ultrasound images to estimate femoral anteversion have met with several problems owing to the complex three-dimensional (3D) structure of the femur. A 3D imaging method has been developed that virtually measures femoral anteversion on the 3D computer space with continuous CT slices; this 3D method provides more accurate and reliable results than conventional 2D CT measurements. A 3D modelling method is devised for the measurement of femoral neck anteversion. This method has advantages over the 3D imaging method, such as shorter processing time, reduced number of slices and an objective result compared with the 3D imaging method. The results of the 3D modelling method are compared with the conventional CT methods (2D CT method and 3D imaging method) using 20 dried femurs.

Femur Neck↗