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Biomedical subjects

H B Park

Publications and source records attributed to H B Park.

At least 19 recordsLinked to original sources
PubMed2006

Development of athermal epsilon-martensite in atomized Co-Cr-Mo-C implant alloy powders.

Co-Cr-Mo atomized powders containing 0.05 wt.% C were sintered at temperatures above 900 degrees C for 1h and then rapidly cooled to room temperature. As a result, various amounts of athermal epsilon-martensite were produced which increased with increasing sintering temperatures (from 30 vol.% at 950 degrees C to 70 vol.% at 1250 degrees C). Apparently, the development of epsilon-embryos was strongly promoted by increasing sintering temperatures due to the development of a high density of epsilon-nucleation site defects. In addition, athermal martensite readily formed in these powders, suggesting that its development was strongly favored by a significant reduction in the carbon supersaturation levels from 0.25 wt.% for most commercial alloys to 0.05 wt.% C. The amounts of epsilon-martensite were 3-4-fold those found in conventional alloys, suggesting that the powder structure provides increasing nucleation sites for athermal epsilon-martensite. Apparently free surfaces and grain development at powder contact surfaces combined with recrystallization and grain growth within powder particles lead to favorable dislocation configuration arrays for the development of epsilon-embryos.

Biocompatible Materials↗
PubMed2004

Assignment of fourteen microsatellite markers to the chicken linkage map.

A large mapping population, with 874 F2 individuals, was generated by reciprocally intercrossing 2 chicken lines. A genetic map of 2,426.6 cM comprising 25 linkage groups was established based on 145 microsatellite markers. Chromosome locations were assigned for 14 previously unmapped markers. The marker ADL0132 was previously mapped to chromosome 9; however, here close linkage to the MCW0091 marker on chromosome 4 was found. With this exception, the derived linkage map was in excellent agreement with the chicken consensus map. A comparison with the chicken genome assembly (http://genome.ucsc.edu; February 2004) suggested a few minor errors in the assembly. A PCR-RFLP test was used to genotype a single nucleotide polymorphism in the melanocortin receptor 3 (MC3R) gene in the intercross, and pyrosequencing was used to map the genes for Hemopoetic Cell Kinase (HCK) and Bone Morphogenic Protein 7 (BMP7). The HCK and BMP7 genes on linkage group E32 showed significant linkage to MC3R on the distal end of linkage group E47W24, consequently joining the 2 linkage groups. A comparison between the linkage data in the current study and the physical location of markers as revealed in the chicken genome sequence assembly (February 2004) showed a 3-fold higher recombination rate on microchromosomes than on macrochromosomes.

Animals↗
PubMed2003

Molecular characterization and mutational screening of the PRKAG3 gene in the horse.

The PRKAG3 gene encodes a muscle-specific isoform of the regulatory gamma subunit of AMP-activated protein kinase (AMPK). A major part of the coding PRKAG3 sequence was isolated from horse muscle cDNA using reverse-transcriptase (RT)-PCR analysis. Horse-specific primers were used to amplify genomic fragments containing 12 exons. Comparative sequence analysis of horse, pig, mouse, human, Fugu, and zebrafish was performed to establish the exon/intron organization of horse PRKAG3 and to study the homology among different isoforms of AMPK gamma genes in vertebrates. The results showed conclusively that the three different isoforms (gamma1, gamma2, and gamma3) were established already in bony fishes. Seven single nucleotide polymorphisms (SNPs), five causing amino acid substitutions, were identified in a screening across horse breeds with widely different phenotypes as regards muscle development and intended performance. The screening of a major part of the PRKAG3 coding sequence in a small case/control material of horses affected with polysaccharide storage myopathy did not reveal any mutation that was exclusively associated with this muscle storage disease. The breed comparison revealed several potentially interesting SNPs. One of these (Pro258Leu) occurs at a residue that is highly conserved among AMPK gamma genes. In an SNP screening, the variant allele was only found in horse breeds that can be classified as heavy (Belgian) or moderately heavy (North Swedish Trotter, Fjord, and Swedish Warmblood) but not in light horse breeds selected for speed or racing performance (Standardbred, Thoroughbred, and Quarter horse) or in ponies (Icelandic horses and Shetland pony). The results will facilitate future studies of the possible functional significance of PRKAG3 polymorphisms in horses.

AMP-Activated Protein Kinases↗
PubMed2002

Melanocortin-4 receptor (MC4R) genotypes have no major effect on fatness in a Large White x Wild Boar intercross.

The melanocortin-4 receptor (MC4R), a G-protein coupled receptor, is implicated in mediating the effect of leptin on food intake and energy balance. A previous candidate gene study reported an association between an MC4R missense mutation (Asp298Asn) and fatness, growth and feed intake in pigs. To assess this association further, we analysed the segregation of this missense mutation in relation to variation in fatness traits using a Wild Boar x Large White intercross. The Wild Boar and Large White founders were homozygous for different MC4R alleles. The MC4R was assigned to the expected region on pig chromosome 1. The statistical evaluation did not reveal any indication of a significant effect on fatness related traits in this pedigree.

Animals↗
PubMed2001

Er:YAG laser skin resurfacing using repetitive long-pulse exposure and cryogen spray cooling: I. Histological study.

BACKGROUND AND OBJECTIVE: To evaluate histologically the characteristics of repetitive Er:YAG laser exposure of skin in combination with cryogen spray cooling (CSC), and its potential as a method of laser skin resurfacing. STUDY DESIGN/MATERIALS AND METHODS: Rat skin was irradiated in vivo with sequences of 10 Er:YAG laser pulses (repetition rate 20 Hz, pulse duration 150 or 550 micros, single-pulse fluence 1.3-5.2 J/cm(2)). In some examples, CSC was applied to reduce epidermal injury. Histologic evaluation was performed 1 hour, 1 day, 5 days, and 4 weeks post-irradiation. RESULTS: A sequence of ten 550-micros pulses with fluences around 2 J/cm(2) resulted in acute dermal collagen coagulation to a depth of approximately 250 microm, without complete epidermal ablation. CSC improved epidermal preservation, but also diminished the coagulation depth. Four weeks after irradiation, neo-collagen formation was observed to depths in excess of 100 microm. CONCLUSIONS: Dermal collagen coagulation and neo-collagen formation to depths similar to those observed after CO(2) laser resurfacing can be achieved without complete ablation of the epidermis by rapidly stacking long Er:YAG laser pulses. Application of CSC does not offer significant epidermal protection for a given dermal coagulation depth.

Animals↗
PubMed2001

A large-scale purification of recombinant histone H1.5 from Escherichia coli.

An Escherichia coli expression system has been constructed for production of biologically active recombinant histone H1.5. A process of fermentation and purification method at a large scale has been developed. Recombinant histone H1.5 was released from the high density cultured cells by high-pressure homogenization. For an efficient removal of cell debris and partial purification of basic histone H1.5 in a single step, the whole cell lysates were directly loaded onto an expanded bed column packed with the strong cation exchanger (Streamline SP). Complete removal of various impurities was achieved by a combination of hydroxyapatite chromatography and the following cation exchange chromatography with high grade strong cation exchanger (POROS 20 HS), and finally endotoxins were removed by ultrafiltration using a 100-kDa cut-off membrane, which gave the level of endotoxin below 0.5 EU/mg. The molecular mass of the recombinant histone H1.5 analyzed by MALDI-TOF-MS, and the N-terminal amino acid sequences were in good agreement with the authentic histone H1.5. The whole process gave highly purified recombinant histone H1.5 at a high yield, compared to the conventional process.

Chromatography, High Pressure Liquid↗
PubMed2001

Impregnation of vancomycin, gentamicin, and cefotaxime in a cement spacer for two-stage cementless reconstruction in infected total hip arthroplasty.

Twenty-two patients with infected total hip arthroplasty were treated with 2-stage arthroplasty, using a cement spacer impregnated with a combination of 3 thermostable antibiotics (vancomycin, gentamicin, and cefotaxime). Initially, implants were removed, and a spacer was inserted. Six to 12 weeks later, the spacer was removed, and the patients underwent reconstruction using cementless components. The patients were followed for an average of 41 months. One patient had a recurrence of infection and was treated with resection arthroplasty. The remaining 21 patients (95%) had no evidence of infection at the final follow-up. We recommend using the combination of these 3 antibiotics in the cement spacer for 2-stage reconstruction in infected hip arthroplasty when the causative organism is not identified in the culture of preoperative aspiration.

Adult↗
PubMed2001

Iliacus hematoma and femoral nerve palsy after revision hip arthroplasty: a case report.

Femoral nerve palsy occurred in a 65-year-old man after he had undergone a revision total hip arthroplasty using cementless components. The magnetic resonance imaging scan showed a mass in the iliacus muscle. The mass showed increased signal intensity on T1-weighted and T2-weighted spin-echo images and contained linear septa and a nodule. The gadolinium-enhanced T1-weighted image showed a rim of significant enhancement in the nodule. The findings of magnetic resonance images were suggestive of iliacus hematoma and of liposarcoma. The patient underwent surgery, and the mass was identified as an iliacus hematoma. The femoral nerve was stretched by the hematoma. After removal of the hematoma, the nerve palsy was improved completely. Iliacus hematoma may occur after total hip arthroplasty, even without anticoagulant therapy. The hematoma might appear to be a liposarcoma on magnetic resonance imaging scans.

Aged↗
PubMed2001

Concomitant fractures of the femoral head and neck without hip dislocation.

This case report describes two patients who sustained ipsilateral fractures of the femoral head and femoral neck without dislocation of the hip. The fractures in the two patients resulted from vehicle accidents. The femoral head was fractured in the sagittal plane, and the femoral neck was fractured at the subcapital portion. However, the hip was not dislocated in either patient. Both patients were treated using cementless total hip arthroplasty. These unusual hip injuries have not been reported previously and are not categorized according to any known classification system of hip injuries.

Femoral Neck Fractures↗
PubMed2001

A simple method for the purification of an antimicrobial peptide in recombinant Escherichia coli.

A magainin derivative, designated MSI-344, was produced in Escherichia coli as fusion protein, by utilizing a truncated amidophsphoribosyltransferase of E. coli as a fusion partner. Bacterial cells transformed with the gene encoding the fusion protein were grown to a high cell density and induced with isopropyl-1-thio-b-D-galatoside (IPTG) to initiate product expression. The fusion protein was accumulated into cytoplasmic inclusion body and recombinant MSI-344 was released from the fusion partner by hydroxylamine treatment. Following cleavage of the fusion protein with hydroxylamine, the released MSI-344 was purified to homogeneity by cationic exchange chromatography. The final purity was at least 95% by reversed-phase high performance liquid chromatography (RP-HPLC). Purified recombinant MSI-344 was found to be indistinguishable from the synthetic peptide determined by amino acid sequences and antimicrobial activity assay.

Amino Acid Sequence↗
PubMed2000

Subcutaneous and musculoskeletal sparganosis: imaging characteristics and pathologic correlation.

OBJECTIVE: To document the imaging characteristics of subcutaneous and musculoskeletal sparganosis. DESIGN AND PATIENTS: Ten patients with musculoskeletal sparganosis were examined, with a variety of imaging modalities including MRI (n=6), ultrasonography (n=8), plain radiography (n=7) and CT (n=1). Pathologic correlation was carried out in all cases. RESULTS: Nine lesions involved soft tissues, of which seven were in the thigh, two in the trunk and one involved a vertebral body. The majority of the lesions in soft tissue were confined to the subcutaneous layer but two extended deep into underlying muscles. Sonography revealed low-echoic serpiginous tubular tracts (8/8), and an intraluminal echogenic structure (4/8). MRI revealed multiple serpiginous tubular tracts and peripheral rim enhancement. Two patients showed perilesional soft tissue edema. Pathologically, the lesion consisted of a larva surrounded by three layers of inflammation: an inner epithelioid granulomatous cell layer, middle chronic inflammatory cell layers, and an outer fibrous layer. CONCLUSION: The study suggests that if serpiginous tubular tracts are seen at imaging studies, musculoskeletal sparganosis should be included in the differential diagnosis.

Adult↗
PubMed1997

Multiple brown tumors in parathyroid carcinoma mimicking metastatic bone disease.

An unusual case of multiple brown tumors due to parathyroid carcinoma is reported. The patient presented with lower leg pain. Plain radiographs demonstrated multiple lytic lesions of the lower legs and a Tc-99m MDP bone scan depicted multiple areas of increased uptake suggesting skeletal metastases. Tc-99m sestamibi tumor scintigraphy showed multiple sites of tumor uptake in bones and a large area of increased uptake with a cystic component in the right lower pole of the thyroid gland. An open biopsy from the right tibial lesion revealed a brown tumor. A large parathyroid carcinoma with a necrotic cyst was removed. After parathyroidectomy and right thyroid lobectomy, the patient became free of bone pain and serum PTH levels normalized. A 9-month follow-up Tc-99m MDP bone scan demonstrated less intense uptake in the pelvis, tibia, and fibulae. Nine-month follow-up tumor imaging with Tc-99m MIBI revealed disappearance of the preoperative uptake of multiple brown tumor.

Adult↗
PubMed1997

Monoclonal antibodies against Helicobacter pylori cross-react with human tissue.

BACKGROUND: H. pylori is a causative agent of chronic gastritis. However, the pathogenic mechanism by which H. pylori induces chronic inflammation and epithelial injuries in the gastric and duodenal mucosa is not well known. Investigators have recently reported that some monoclonal antibodies against H. pylori cross-react with the gastric epithelial cells. So, there exists the possibility that the autoimmune mechanism may be involved in the pathogenesis of chronic gastritis caused by H. pylori. The purpose of his study is to investigate whether the antibodies against H. pylori react with human tissues or not, using a large panel of monoclonal antibodies. MATERIALS AND METHODS: Two hundred and fourteen monoclonal antibodies against H. pylori were produced. An immunohistochemical staining of human tissues, including H. pylori-infected gastric mucosa, was performed using the antibodies. RESULTS: Of 214 monoclonal antibodies, 71 antibodies reacted with H. pylori in the gastric mucosa. Of 71 antibodies, 25 antibodies also reacted with gastric epithelial cells, 11 antibodies reacted with ductal cells of the salivary gland, 11 antibodies reacted with renal tubular cells, and 8 antibodies reacted with duodenal epithelial cells. The antibodies which showed cross-reactivity with gastric epithelial cells included those against urease, flagella, lipopolysaccharide, and heat shock protein of H. pylori. CONCLUSIONS: It is believed that the autoimmune reaction might be involved in the pathogenesis of chronic gastritis due to H. pylori infection, and that the autoimmune reaction induced by H. pylori infection might also be involved in the pathogenesis of various diseases in other organs.

Animals↗
PubMed1997

Gastric metastasis of mammary signet ring cell carcinoma--a differential diagnosis with primary gastric signet ring cell carcinoma.

Metastasis of breast carcinoma to the stomach is relatively uncommon, although metastasis to other organs such as lung, bone, and lymph nodes is not rare. It may cause difficulty in differentiating from primary gastric carcinoma. We report a case of signet ring cell carcinoma of the breast with metastasis to the stomach with illustrations of histologic findings of both lesions. The results of immunohistochemical stainining with GCDFP-15 (gross cystic disease fluid protein-15), that can be used to differentiate primary gastric signet ring cell carcinoma and metastatic mammary signet ring cell carcinoma, are described.

Apolipoproteins↗
PubMed1996

Bilateral signet-ring cell carcinoma of the breast: scintigraphic findings.

Signet-ring cell carcinoma of the breast, first recognized in 1976, behaves aggressively and is associated with a poor prognosis. The tumor is a rare type of breast cancer and often metastasizes to the gastrointestinal tract and female genital tract. The authors report a case of a 48-year-old woman with bilateral signet-ring cell carcinoma of the breasts with multiple skeletal metastases and gastric metastasis. The breast cancer was depicted on a Tc-99m MIBI scintimammogram.

Bone Neoplasms↗
PubMed1996

Two cases of pachydermodactyly.

We report two cases of pachydermodactyly. Case 1 was a 16-year-old girl who complained of asymptomatic, bulbous, firm swellings which developed insidiously on both sides of the proximal interphalangeal (PIP) joint of her right middle finger. Case 2 was a 14-year-old boy with similar lesions on the sides of the PIP joints of the index and middle fingers of both hands. They both had histories of mild, repetitive mechanical trauma of the fingers. Radiologic findings showed soft tissue swellings without any bony or articular abnormalities. Histopathologic findings from the bulbous swellings revealed marked hyperkeratosis, slight epidermal hyperplasia, and a markedly thickened dermis with a deposition of mucinous material among the collagen fibers. Ultrastructural examinations of both cases showed decreased diameters of collagen fibrils. The lesions temporarily improved with intralesional injection of triamcinolone acetonide. Pachydermodactyly is more commonly found in boys and the affected fingers are more numerous in boys. Both of the present cases had the habit of rubbing and gripping their fingers unconsciously. Mechanical trauma of the fingers around puberty may play an important role in pachydermodactyly.

Adolescent↗
PubMed1995

Comparative study of efficacy and safety of low-dose diltiazem or betaxolol in combination with digoxin to control ventricular rate in chronic atrial fibrillation: randomized crossover study.

BACKGROUND: The combination therapy of low-dose diltiazem or bexatolol with digoxin can be a useful adjunct for achieving heart rate control with minimal side effects. But there has not been a study including patients with impaired left ventricular function and evaluating whether the beneficial effects of medication will be maintained during a follow-up period. OBJECTIVES: The purpose of this study was three-fold: (1) to compare the efficacy of digoxin with low-dose diltiazem and digoxin with low-dose betaxolol on randomized crossover study; (2) to evaluate whether the beneficial effects of medication will be maintained after 7 months; (3) to evaluate the safety of the combination therapy in patients with impaired left ventricular function. METHODS: We did a prospective randomized crossover study in 35 patients with chronic atrial fibrillation (AF) including 15 patients with left ventricular dysfunction. After enrollment, each patient was evaluated for heart rate, blood pressure, rate-pressure products, maximal exercise tolerance at rest and during symptom-limited treadmill test before medication, at 4 weeks after medication of digoxin (0.125-0.5 mg daily) with diltiazem (90 mg twice daily), and at 4 weeks after digoxin with betaxolol (20 mg once daily). We performed 24-h ambulatory electrocardiogram (ECG) in 15 patients at the end of each phase of treatment. We repeated symptom-limited treadmill test like above method in 15 patients at 7 months of medication. RESULTS: (1) Ventricular rates were significantly reduced in digoxin with low-dose betaxolol therapy at rest and during exercise (67 +/- 3, 135 +/- 5 (mean +/- S.E.M.) beats/min, respectively) in comparison to digoxin with low-dose diltiazem therapy (80 +/- 7, 154 +/- 5) (P < 0.05). (2) Rate-pressure products were significantly less in digoxin with low-dose betaxolol at rest and during exercise (85 +/- 4, 213 +/- 12 x 10(2) mmHg/min) than in digoxin with low-dose diltiazem therapy (105 +/- 6, 269 +/- 12) (P < 0.05). (3) Exercise capacity was significantly improved in digoxin with low-dose betaxolol (9.3 +/- 0.5 METS) or digoxin with low-dose diltiazem (9.7 +/- 0.5) in comparison to control state (8.3 +/- 0.5) (P < 0.05). (4) At 7 months evaluation, there was no significant difference between at 4 weeks and at 7 months. (5) Results on 24-h ambulatory ECG showed the same findings as on treadmill test. (6) Although side effects occurred more frequently in digoxin with low-dose betaxolol therapy, they were minimal and no patient had to withdraw medication. Worsening of left ventricular dysfunction was not observed. CONCLUSION: Our study suggested that (1) combination therapy of low-dose betaxolol with digoxin was more superior to low-dose diltiazem with digoxin in controlling ventricular rate and reducing rate-pressure products; (2) the effects controlling ventricular rate, reducing rate-pressure products and improving exercise capacity have been well maintained even after 7 months of medication with each combination therapy.

Adrenergic beta-Antagonists↗