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Biomedical subjects

S-H Oh

Publications and source records attributed to S-H Oh.

12 recordsLinked to original sources
PubMed2006

Relationship between occlusal tooth contact patterns and tightness of proximal tooth contact.

The aim of this study was to investigate the relationship between occlusal tooth contact patterns and the tightness of proximal tooth contact (TPTC) during clenching. Twenty young adult volunteers with healthy dentition participated in the study. TPTC between the left second premolar (P2) and the first molar (M1) was measured during clenching at the 50% maximum voluntary contraction level in the intercuspal position (ICP). A silicone impression material was used to make an interocclusal record at the ICP in each subject, and interocclusal records were analysed using an image-processing system. Subjects were classified according to the presence or absence of each type (A, B or C) of occlusal contact. Statistical analysis was performed using the Mann-Whitney U-test. The results of this study exhibited a relationship between B-type contact and the TPTC of maxillary teeth. The experimental group with a lack of B-type contact on maxillary P2 and/or M1 showed a statistically greater TPTC than the group with B-type contact on both of these teeth (P < 0.01). These results suggest that occlusal tooth contact patterns have an influence on TPTC during clenching.

Adult↗
PubMed2005

Interactions between attention and working memory.

Studies of attention and working memory address the fundamental limits in our ability to encode and maintain behaviorally relevant information, processes that are critical for goal-driven processing. Here we review our current understanding of the interactions between these processes, with a focus on how each construct encompasses a variety of dissociable phenomena. Attention facilitates target processing during both perceptual and postperceptual stages of processing, and functionally dissociated processes have been implicated in the maintenance of different kinds of information in working memory. Thus, although it is clear that these processes are closely intertwined, the nature of these interactions depends upon the specific variety of attention or working memory that is considered.

Attention↗
PubMed2005

Analysis of the Candida albicans Als2p and Als4p adhesins suggests the potential for compensatory function within the Als family.

The ALS (agglutinin-like sequence) gene family encodes eight large cell-surface glycoproteins. The work presented here focuses on Als2p and Als4p, and is part of a larger effort to deduce the function of each Als protein. Both ALS4 alleles were deleted from the Candida albicans genome and the phenotype of the mutant strain (als4Delta/als4Delta; named 2034) studied. Loss of Als4p slowed germ tube formation of cells grown in RPMI 1640 medium and resulted in decreased adhesion of C. albicans to vascular endothelial cells. Loss of Als4p did not affect adhesion to buccal epithelial cells, biofilm formation in a catheter model, or adhesion to or destruction of oral reconstituted human epithelium (RHE). Although deletion of one ALS2 allele was achieved readily, a strain lacking the second allele was not identified despite screening thousands of transformants. The remaining ALS2 allele was placed under control of the C. albicans MAL2 promoter to create an als2Delta/PMAL2-ALS2 strain (named 2342). Real-time RT-PCR analysis of strain 2342 grown in glucose-containing medium (non-inducing conditions) showed that although ALS2 transcript levels were greatly reduced compared to wild-type cells, some ALS2 transcript remained. The decreased ALS2 expression levels were sufficient to slow germ tube formation in RPMI 1640 and Lee medium, reduce adhesion to vascular endothelial cells and to RHE, decrease RHE destruction, and impair biofilm formation. Growth of strain 2342 in maltose-containing medium (inducing conditions) restored the wild-type phenotype in all assays. Real-time RT-PCR analysis demonstrated that in maltose-containing medium, strain 2342 overexpressed ALS2 compared to wild-type cells; however no overexpression phenotype was apparent. Microarray analysis revealed little transcriptional response to ALS4 deletion, but showed twofold up-regulation of orf19.4765 in the glucose-medium-grown als2Delta/PMAL2-ALS2 strain. orf19.4765 encodes a protein with features of a glycosylated cell wall protein with similarity to Saccharomyces cerevisiae Ccw12p, although initial analysis suggested functional differences between the two proteins. Real-time RT-PCR measurement of ALS2 and ALS4 transcript copy number showed a 2.8-fold increase in ALS2 expression in the als4Delta/als4Delta strain and a 3.2-fold increase in ALS4 expression in the als2Delta/PMAL2-ALS2 strain, suggesting the potential for compensatory function between these related proteins.

Biofilms↗
PubMed2005

A case of chromoblastomycosis with an unusual clinical manifestation caused by Phialophora verrucosa on an unexposed area: treatment with a combination of amphotericin B and 5-flucytosine.

Chromoblastomycosis is a cutaneous and subcutaneous mycotic disease caused by the dematiaceous (black) fungi. Five species of fungi are known generally to be the cause: Fonsecaea pedrosoi, Phialophora verrucosa, Cladosporium carrionii, F. compacta and Rhinocladiella cerphilum. In infected tissue they can appear as pigmented sclerotic bodies, commonly called 'copper pennies', which are pathognomonic of chromoblastomycosis. The infection usually occurs through traumatic skin inoculation, with the majority of lesions occurring on the feet and legs of outdoor workers. We report a patient in whom the lesions had begun on the right breast, which is an unexposed area, without a history of trauma. A uniform, reliable treatment does not exist but our patient was mycologically cured with the use of amphotericin B and the subsequent combination of 5-flucytosine and itraconazole.

Adult↗
PubMed2004

Infarct patterns in atherosclerotic middle cerebral artery versus internal carotid artery disease.

OBJECTIVE: To compare clinical and radiologic characteristics of atherosclerotic middle cerebral artery (MCA) vs internal carotid artery (ICA) disease. METHODS: The authors defined atherosclerotic MCA and ICA disease as >50% symptomatic stenosis or occlusion without significant ICA and MCA stenosis on MR angiography. Patients with potential cardiac sources of embolism were excluded. The authors analyzed clinical, laboratory, and neuroradiologic data of the two groups. RESULTS: Among the 920 consecutive patients with acute ischemic strokes, 112 met the criteria for atherosclerotic MCA and 71 met the criteria for ICA disease. Clinically, the MCA group more frequently presented with lacunar syndrome (p = 0.001), whereas the ICA group more often presented with total anterior circulation infarct and had higher initial NIH Stroke Scale scores than the MCA group (all p < 0.001). Whereas deep perforator and internal border-zone infarcts were associated with MCA disease (p < 0.001 and 0.012), territorial infarcts and superficial perforator infarcts were associated with ICA disease (p < 0.001 and p = 0.009). The topographic patterns with respect to the degree of stenosis were also significantly different between the two groups. CONCLUSIONS: The clinical and radiologic stroke patterns were distinctively different between atherosclerotic MCA and ICA disease, suggesting different underlying pathogeneses.

Acute Disease↗
PubMed2003

Total hip arthroplasty for the treatment of osseous ankylosed hips.

The long-term results of total hip prostheses in 86 patients (87 hips) who had either primary cemented or cementless total hip arthroplasty after fusion take-down were analyzed. Thirty-eight patients (38 hips) had a surgical fusion and 48 patients (49 hips) had a spontaneous fusion. The mean age of patients was slightly older in the cemented group (49.8 years) than in the cementless group (43.8 years). Twenty-six of 42 patients (62%) in the cemented group and 32 of 44 patients (73%) in the cementless group were younger than 50 years. Clinical (Harris hip rating system) and radiographic evaluations were done preoperatively and at 6 weeks, at 3, 6, and 12 months, and yearly thereafter. The average followup was 10.2 years (range, 8-18 years) in the cemented group and 9.8 years (range, 8-17 years) in the cementless group. The revision rates were 16% in the patients who had surgical fusion and 18% in the patients who had spontaneous fusion. The revision rates were 17% in the cemented group and 18% in the cementless group. The average linear wear rate of polyethylene per year was 0.24 mm in the cemented group and 0.32 mm in the cementless group. The incidence of osteolysis was 52% in the cemented group and was 58% in the cementless group.

Adult↗
PubMed2003

Primary total hip arthroplasty with a second-generation cementless total hip prosthesis in patients younger than fifty years of age.

BACKGROUND: The early experience with cementless total hip replacement led to design modifications to increase the initial press-fit and stability of the femoral component, to reduce the diameter of the femoral head, and to improve the acetabular component, including the locking mechanism of the shell and the quality of the polyethylene liner. We performed a prospective study to assess the results in young patients who had been followed for a minimum of eight years after treatment with a primary total hip arthroplasty with a second-generation cementless prosthesis. METHODS: Eighty patients (118 hips) were included in the study. There were fifty-eight men and twenty-two women; the mean age at the time of the operation was 46.8 years (range, twenty-one to forty-nine years). We used a cementless Duraloc series-100 or 1200 acetabular component with or without screw fixation, a polyethylene liner with a 22-mm inner diameter, and a cementless Profile femoral component in all hips. The average duration of follow-up was 9.8 years (range, eight to eleven years). Clinical follow-up (with use of the Harris hip score) and radiographic follow-up were performed at six weeks; at three, six, and twelve months; and yearly thereafter. Linear and volumetric wear were measured, and bone-remodeling and osteolysis were assessed. RESULTS: The average Harris hip score improved from 48.8 points preoperatively to 92 points at the final follow-up examination. The prevalence of transitory thigh pain was 10% (twelve of 118 hips). There was no aseptic loosening. One hip was revised because of recurrent dislocation. The average amount of linear wear was 1.18 mm, and the average wear rate was 0.12 mm/yr. Fourteen hips (12%) had osteolysis in the calcar femorale and eleven hips (9%) had acetabular osteolysis, but all of the osteolytic lesions were <1 cm (2). CONCLUSIONS: The mechanical fixation of the anatomic fit cementless Profile stem was excellent in this study of young patients who were particularly difficult to treat because of a high prevalence of osteonecrosis and developmental dysplasia. Although there was no aseptic loosening of the components and a relatively low prevalence of osteolysis, there was a high rate of linear wear of the polyethylene liner. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series [no, or historical, control group]). See p. 2 for complete description of levels of evidence.

Adult↗
PubMed2003

Total hip arthroplasty in adult patients who had childhood infection of the hip.

BACKGROUND: Adult patients with a history of infection of the hip in childhood present a challenge as candidates for total hip arthroplasty because of abnormal bone development, soft-tissue contractures, the possibility of reinfection, and their relative youth. The purpose of this study was to analyze the mid-term results of primary total hip arthroplasty in adult patients who had had infection of the hip in childhood. METHODS: We retrospectively analyzed 170 total hip arthroplasties that had been performed between 1983 and 1996 in patients who had had infection of the hip during childhood. Forty-seven hips had cemented or hybrid total hip replacements, and 123 hips had cementless total hip replacements. The age of the patients at the time that the infection was contracted was an average of 7.3 years (range, one to eleven years). The average age of the patients at the time of the index total hip arthroplasty was 41.9 years in the cemented or hybrid group and 42.7 years in the cementless group. The interval between active infection and arthroplasty was 34.9 years in the cemented or hybrid group and 31.9 years in the cementless group. All but two hips (one patient) had a quiescent period of infection of more than ten years. The average duration of follow-up was 9.8 years (range, seven to seventeen years) in the cemented or hybrid group and 10.8 years (range, seven to seventeen years) in the cementless group. RESULTS: All hips with a quiescent period of more than ten years had no recurrence of infection. The remaining two hips in one patient with a quiescent period of seven years had recurrence of the infection. The mean Harris hip scores improved from 50 points preoperatively to 85 points at the latest follow-up examination in the cemented or hybrid group and from 50 points preoperatively to 89 points at the latest follow-up examination in the cementless group. Eight (17%) of forty-seven hips with cemented or hybrid fixation and eighteen (15%) of 123 hips with cementless fixation had revision of both components because of aseptic loosening and/or osteolysis. The mean rate of linear wear of the polyethylene was 0.25 mm per year in the cemented or hybrid group and 0.29 mm per year in the cementless group. The prevalence of osteolysis was 53% (twenty-five of forty-seven hips) in the cemented or hybrid group and 59% (seventy-two of 123 hips) in the cementless group. CONCLUSIONS: There was no recurrence of infection after total hip arthroplasty in the patients with a quiescent period of infection of more than ten years. These young, active patients with technically difficult arthroplasties were at considerable risk for aseptic loosening. The prevalence of polyethylene wear and osteolysis was attributable to the less than optimal prosthetic designs and materials used during the time-period of this study.

Adolescent↗
PubMed2003

Contemporary total hip arthroplasty with and without cement in patients with osteonecrosis of the femoral head.

BACKGROUND: The rate of failure of primary total hip arthroplasty in patients with osteonecrosis of the femoral head is higher than that in patients with osteoarthritis. The purpose of this prospective study was to document the clinical and radiographic results of arthroplasty with so-called third-generation cementing and the results of second-generation cementless total hip arthroplasty in ninety-eight consecutive patients with osteonecrosis of the femoral head. METHODS: Fifty patients who had had simultaneous bilateral total hip arthroplasty with a cemented stem in one hip and a cementless stem in the other and forty-eight patients who had had a unilateral total hip arthroplasty with a cementless stem were included in the study. A cementless acetabular component was used in all hips. The presumed cause of the osteonecrosis was ethanol abuse in fifty-seven patients, unknown in twenty-seven, fracture of the femoral neck in nine, and steroid use in five. There were eighty men and eighteen women. The mean age at the time of the arthroplasty was 47.3 years (range, twenty-six to fifty-eight years). Clinical and radiographic evaluations were performed preoperatively; at six weeks; at three, six, and twelve months; and yearly thereafter. The average duration of follow-up was 9.3 years. RESULTS: The average Harris hip scores in the group treated with unilateral arthroplasty (97 points) and the group treated with bilateral arthroplasty (94 points) were similar at the time of final follow-up. They were also similar between the group treated with cement (mean, 96 points) and that treated without cement (95 points). No component had aseptic loosening in either group. In one hip, a cemented femoral stem (2%) and a cementless cup were revised because of infection. Two cementless stems (2%) were revised because of fracture of the proximal part of the femur with loosening of the stem. Annual wear of the polyethylene liner averaged 0.22 mm in the group treated with cement (a zirconia head) and 0.14 mm in the group treated without cement (a cobalt-chromium head). The prevalence of osteolysis in zones 1 and 7 of the femur was 16% in the group treated with cement and 24% in the group treated without cement. CONCLUSIONS: Advancements in surgical technique and better designs have greatly improved the long-term survival of cemented and cementless implants in young patients with osteonecrosis of the femoral head. Although there was no aseptic loosening of the components, a high rate of linear wear of the polyethylene liner and a high rate of osteolysis in these high-risk young patients remain challenging problems.

Adult↗
PubMed2003

Conversion of a fused knee with use of a posterior stabilized total knee prosthesis.

BACKGROUND: Typically a hinged or condylar constrained prosthesis is recommended for total knee arthroplasty in a fused knee, to substitute for the absent or deficient collateral ligaments. The purpose of this study was to evaluate the stability and clinical results after the use of a posterior stabilized prosthesis in the conversion of a fused knee to a total knee arthroplasty. METHODS: Thirty-six patients (thirty-six knees) with a mean age of 39.2 years underwent conversion of a fused knee to a total knee arthroplasty with a posterior stabilized prosthesis. The mean duration of ankylosis had been 24.5 years. Clinical and radiographic evaluation was carried out preoperatively; at six weeks and three, six, and twelve months postoperatively; and annually thereafter. The mean duration of follow-up was 7.7 years. RESULTS: The mean preoperative Hospital for Special Surgery knee score of 60 points improved to 83.2 points at the final follow-up examination. Twenty-two knees were pain-free, and the remaining fourteen were mildly painful after prolonged walking. The mean amount of active flexion in the entire group was 77.7 degrees. The extension lag in the entire group averaged 12.5 degrees. Complications included necrosis of the skin edges in eighteen knees (50%), a rupture of the quadriceps tendon in two patients, and a pyogenic infection in two. No prosthesis required revision because of clinical or radiographic loosening. CONCLUSIONS: We believe that when the soft-tissue sleeves in a previously fused knee are carefully preserved intraoperatively, they can provide adequate stability after total knee arthroplasty with a posterior stabilized prosthesis. Therefore, we believe that use of that type of prosthesis is a reasonable alternative to the use of a more constrained implant in the treatment of this condition.

Adult↗