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Biomedical subjects

S H Koh

Publications and source records attributed to S H Koh.

At least 19 recordsLinked to original sources
PubMed2006

Haemodynamic effects of oxytocin given as i.v. bolus or infusion on women undergoing Caesarean section.

BACKGROUND: The cardiovascular effects of oxytocin in animal models and women undergoing Caesarean section include tachycardia, hypotension and decrease in cardiac output. These can be sufficient to cause significant compromise in high-risk patients. We aimed to find a simple way to decrease these risks whilst retaining the benefits of oxytocin in decreasing bleeding after delivery. Method. We recruited 30 women undergoing elective Caesarean section. They were randomly allocated to receive 5 u of oxytocin either as a bolus injection (bolus group) or an infusion over 5 min (infusion group). These women had their heart rate and intra-arterial blood pressure recorded every 5 s throughout the procedure. The haemodynamic data, along with the estimated blood loss, were compared between the groups. RESULTS: Marked cardiovascular changes occurred in the bolus group; the heart rate increased by 17 (10.7) beats min(-1) [mean (sd)] compared with 10 (9.7) beats min(-1) in the infusion group. The mean arterial pressure decreased by 27 (7.6) mm Hg in the bolus group compared with 8 (8.7) mm Hg in the infusion group. There were no differences in the estimated blood loss between the two groups. CONCLUSION: We recommend that bolus doses should be used with caution, and further studies should ascertain if oxytocin is equally effective in reducing blood loss when given at a slower rate.

Adult↗
PubMed2006

Ocular flutter induced only by optokinetic stimulation.

Ocular flutter (OF) refers to occasional bursts of involuntary horizontal oscillation around the point of fixation, characterised by rapid horizontal repetitive oscillation without intersaccadic interval in electro-ocular recording. In spite of numerous reports of OF, there has been no previous report describing OF developed by simply looking at moving objects. We report a patient with olivopontocerebellar atrophy (OPCA), with OF induced only by optokinetic stimulation (OKS). A 65-year-old man, with OPCA complained of dizziness and oscillopsia occurring only with a specific type of eye movement. The electro-oculographic recording showed a decreased gain of pursuit, catch-up saccade, and decreased velocity of saccade, and OF was induced only by OKS of more than 40 degrees /second. In OPCA, partial loss of omnipause neurons and/or abnormal firing of burst neurons, especially those involved in optokinetic movement, could be the cause of OF occurring only with OKS.

Aged↗
PubMed2001

Tensile bond strengths of fourth- and fifth-generation dentin adhesives with packable resin composites.

PURPOSE: Placement of packable composites would be simplified if a single-bottle dentin bonding agent, rather than the more complex, multiple-bottle dentin bonding agents, involving multiple steps, could be used successfully with adequate bond strength. This study was designed to compare the tensile bond strengths to extracted human dentin of four single-bottle (fifth-generation) and four multiple-bottle (fourth-generation) dentin bonding agents with four packable composites. MATERIALS AND METHODS: Packable composites (P60, 3M Dental Products Division; ALERT, Jeneric-Pentron; Pyramid Dentin, Bisco; and Clearfil AP-X, Kuraray America) were tested for in vitro tensile bond strength to human dentin with their single-bottle and their multiple-bottle dentin bonding agents. Bond strengths were measured using a truncated cone tensile test, with a bonding diameter of 3 mm, after storage of specimens in water at 37 degrees C and 100% relative humidity for 24 hours, and using a testing machine at a crosshead speed of 0.5 mm per minute. RESULTS: Means and standard deviations (n = 10) of tensile bond strengths (MPa) for the single-bottle system were P60, 21.3 MPa (6.7); ALERT, 26.6 MPa (4.2); Pyramid Dentin, 14.8 MPa (4.4); and Clearfil AP-X, 18.6 MPa (3.7). For the multiple-bottle system they were P60, 20.0 MPa (8.6); ALERT, 20.6 MPa (6.2); Pyramid Dentin, 16.0 MPa (3.4); and Clearfil AP-X, 17.8 MPa (6.0). Two-way analysis of variance showed significant differences among composites but no significant differences between single-bottle and multiple-bottle bonding agents. The Tukey-Kramer interval (p < .05) for comparisons of bond strengths among composites was 4.8 MPa. CONCLUSIONS: For single-bottle agents, bond strengths were ranked as ALERT > P60, P60 = Clearfil, P60 > Pyramid, and Clearfil = Pyramid. For multiple-bottle agents, there were no significant differences in bond strengths among the composites. CLINICAL SIGNIFICANCE: Single-bottle bonding agents provide similar in vitro bond strengths for use with packable composites as do the same manufacturers' multiple-bottle bonding agents.

Analysis of Variance↗
PubMed2001

Spinocerebellar ataxia type 6 and episodic ataxia type 2 in a Korean family.

Spinocerebellar ataxia type 6 (SCA6), episodic ataxia type 2 (EA2) and familial hemiplegic migraine (FHM) have been known as allelic disorders, which are caused by the alteration of the alpha1A voltage-dependent calcium channel subunit. Expansions of the CAG repeat in the CACNA1A gene on the short arm of the chromosome 19 induce SCA6, and point mutations in the same gene are responsible for EA2 and FHM. In recent studies, both SCA6 and EA2 have been concurrently found in families with 26 CAG repeats without previously reported point mutations either in coding sequences or in intron-exon junctions. We describe a Korean family with CAG26 repeats in the CACNA1A gene. Some of the affected family members had progressive ataxia typical of SCA6 whereas others had episodic vertigo responsive to acetazolamide typical of EA2. Our family support that SCA6 and EA2 are allelic disorders with a high phenotypic variability.

Adolescent↗
PubMed2000

Changes in expression of sodium cotransporters and aquaporin-2 during ischemia-reperfusion injury in rabbit kidney.

Ischemic renal injury is associated with defects in transport functions of the proximal tubules and urinary concentration ability. To determine whether alterations in expression of various transporter genes contribute to an impairment in renal functions, the expression of various solute transport genes was analyzed in renal cortex and medulla of rabbits with ischemic acute renal failure. Rabbits were subjected to 60 min of renal pedicle clamping followed by 24, 48, or 72 h of reperfusion. Urine volume and glomerular filtration rate were markedly decreased, which were accompanied by an increase in serum creatinine level and fraction Na+ excretion. Glucosuria and phosphaturia were evident during reperfusion periods. These alterations in renal functions were persisted to 72 h after reperfusion. The Na+-dependent uptakes of glucose and phosphate by brush border membrane vesicles were inhibited by 24 h of reperfusion. mRNA levels for Na+-glucose, Na+-phosphate, and Na+-succinate cotransporter analyzed by RT-PCR were not changed by 60 min of ischemia alone, but were significantly reduced by 24 h of reperfusion. mRNA levels for apical Na+-K+-2Cl- cotransporter, NaCl cotransporter, and turea transporter in the medulla were not changed during reperfusion. Protein levels for AQP2 in the medulla, but not AQP1 in the cortex, analyzed by Western blot were significantly reduced at 24 h after reperfusion. These results suggest that reductions in expression of Na+-cotransporter genes in the proximal tubules may be important factors in the impairment in Na+-dependent reabsorption of solutes and that decrease in AQP2 protein may be involved in defect in urinary concentration ability in rabbits with ischemic acute renal failure.

Analysis of Variance↗
PubMed1996

Fluoride content in caffeinated, decaffeinated and herbal teas.

The fluoride contents of infusions prepared from 44 different brands and types of teas were measured. Fluoride concentrations ranged from 0.34 to 3.71 ppm (mean = 1.50 ppm) in caffeinated tea infusions, 0.02-0.14 ppm (mean = 0.05 ppm) in herbal tea infusions, and 1.01-5.20 ppm (mean = 3.19) in decaffeinated tea infusions. This is the first report of the fluoride content of decaffeinated teas. The mean fluoride content of decaffeinated tea infusions is significantly (p < 0.01) higher than the corresponding caffeinated tea. The use of mineral water containing a naturally high fluoride level during the process of decaffeination is the most likely explanation of the above observation.

Beverages↗
PubMed1988

Histocompatibility antigens and habitual abortion.

Eighty-five couples with habitual abortion were studied: 43 were primary aborters (i.e., had no advanced pregnancy beyond 20 weeks gestation), and 42 were secondary aborters. The only significant finding in primary female aborters was a reduction in the incidence of B35. In contrast, in secondary female aborters there was a reduction in the incidence of DR3 and A1/B8/DR3 and an increase in the degree of homozygosity of HLA B. In the male partners of primary aborters, there was a reduced incidence of DR3 and A1/B8/DR3. In addition, in male partners of both primary and secondary aborters, there was increased HLA-B homozygosity and increased frequency of DR4-5 phenotype. Increased sharing of HLA antigens between partners was not found to be significantly different from the control population. These findings emphasize that primary and secondary female aborters form distinct populations, which could explain differences in immunological responses to various antigens, including fetal-related antigens. The closely related findings in female secondary aborters and male partners of primary aborters are intriguing but cannot be explained. Whether or not these genetic markers bear any relationship to reproductive success remains to be determined.

Abortion, Habitual↗
PubMed1987

Immunogenetic studies in habitual abortion.

Recent evidence suggests that immunological factors could play a role in the aetiology of habitual abortion. In this study, 71 couples with habitual abortion (i.e. more than 3 successive abortions) were investigated. Sharing of HLA-A, B, DR between partners was not found to be significantly increased. Anti-HLA antibodies in women against their partners' lymphocytes were found in 18.3%. After immunization with 10(7)-10(8) lymphocytes obtained from husband or unrelated donor, there was a seroconversion rate of 61% in those without antibodies initially. This was not dependent on the number of cells injected, source of cells, degree of sharing of HLA antigens or whether the couple were primary aborters (i.e. having had no advanced pregnancy), or secondary aborters. Seven pregnancies have resulted following the immunization procedure so far, 5 occurring in cross-match positive patients and 2 in cross-match negative. Growth retarded infants resulted from the pregnancy of 1 primary aborter and 2 secondary aborters.

Abortion, Habitual↗
PubMed1985

Increased frequency of autoantibodies in men with sperm antibodies.

Autoantibodies to thyroid microsomes were more frequent in 102 infertile men with complement-dependent sperm-immobilizing activity (sperm immobilization test [SIT] ) in serum (11.8%) than in a control group of 277 men of comparable ages and semen quality without sperm antibodies (4.3%, P less than 0.05). Frequencies of organ-specific antibodies (antigastric parietal cell, antithyroglobulin, and antithyroid microsome) in 57 men with genital tract obstructions and positive SIT were similar to those for control subjects, and there were no significant differences in the frequencies of non-organ-specific autoantibodies (antinuclear antibody, rheumatoid factor, antimitochondrial, and anti-smooth muscle) in the three groups. Because in men without genital tract obstruction antithyroid microsomal autoantibodies were more common with sperm antibodies than without, the possibility of a genetic factor in the causation of sperm autoimmunity should be considered.

Adult↗
PubMed1985

Correlation between cytoplasmic steroid receptors and tumour differentiation and invasion in endometrial carcinoma.

The incidence and levels of cytoplasmic steroid receptors were studied in 155 endometrial carcinomas: oestrogen receptors (ER) were measured in all samples, progesterone receptors (PR) in 148 and androgen receptors (AR) in 118. Well-differentiated adenocarcinomas were significantly more likely to contain ER, PR and AR than were poorly-differentiated tumours, and mean values of ER and PR content were significantly higher in well-differentiated adenocarcinomas than in less-differentiated tumours. Receptor profiles in adenosquamous carcinomas and clear-cell carcinomas were similar to those in adenocarcinomas. Deeply invasive tumours were significantly less likely to be ER, PR or AR positive and, even when positive, such tumours had significantly lower mean levels of ER and PR. Poorly-differentiated tumours were significantly more likely to be ER-negative PR-positive than well-differentiated adenocarcinomas and adenosquamous carcinomas.

Adenocarcinoma↗
PubMed1984

Sperm antibodies, immunoglobulins, and complement in human follicular fluid.

The levels of immunoglobulins (IgG, IgA, IgM), complement (C3, C4, C1EI) and sperm antibodies were determined in plasma and follicular fluid samples from 26 patients undergoing in vitro fertilization (IVF) treatment. The results show that IgG, IgA, C3, C4, and C1EI concentrations in follicular fluid are similar to plasma concentrations (63.1-96.1% of plasma levels). The follicular fluid concentration of IgM was severely reduced, however, being only approximately 10% of plasma concentrations. Sperm antibody titres were compared in three patients using sperm agglutination, immobilization, and immunobead binding. The titres in plasma and follicular fluid were similar, apart from antibodies of IgM class, which were undetectable in follicular fluid.

Antibodies↗
PubMed1984

Oncofetal antigens in ovarian cyst fluids.

The levels of five oncofetal antigens were measured in ovarian cyst fluids. Significantly raised levels of carcinoembryonic antigen (CEA), human chorionic gonadotropin, beta 2-microglobulin, and alpha-fetoprotein were found in ovarian cyst samples. Human placental lactogen was not detectable in any samples. Mucinous cyst fluids demonstrated higher levels of CEA than serous fluids in both malignant and benign conditions. We could not distinguish between malignant and benign conditions with any of the markers. Except for CEA, there is no difference in values between mucinous and serous cystadenocarcinomas.

Antigens, Neoplasm↗
PubMed1983

Prognostic significance of oncofetal antigens in patients with ovarian cancer.

The prognostic significance of elevated oncofetal antigens, namely carcinoembryonic antigen (CEA), alphafetoprotein (AFP), and beta subunit of human chorionic gonadotrophin (beta HCG) were studied in 39 patients with cancer of the ovary. At low cut-off levels, (CEA greater than 2.5 micrograms/l, AFP greater than 5 micrograms/l, and beta HCG greater than 3 IU/l) the median survival was 21 months in patients with one or more positive markers compared to greater than 43 months in patients without markers. At high cut-off points (namely CEA greater than 10 micrograms/l, AFP greater than 10 micrograms/l and beta HCG greater than 10 IU/l), the median survival of patients having one or more positive markers was 10 months compared to greater than 46 months in patients with no markers. Using linear regression and Logrank analysis, the difference between the observed and expected death rate was significant (P less than 0.05 at low cut-off levels, and less than 0.01 at high cut-off levels). These results indicate that patients who have one or more positive oncofetal markers on presentation are likely to have a significantly worse prognosis than patients without markers. Moreover, higher levels of oncofetal markers are associated with correspondingly worse prognosis.

Adolescent↗
PubMed1981

The Production of beta 1-specific pregnancy glycoprotein (SP1) by the amnion.

Using indirect immunofluorescence, beta 1-specific pregnancy glycoprotein (SP1) was localised to the amnion cells, as well as to trophoblastic cells. Cultures of fragments of amnion incubated with 3H-leucine for up to 72 h demonstrated that protein was synthesized by the amnion. Using antisera specific to SP1 it was shown that after 72 h incubation about 50% of the total protein could be precipitated. These studies demonstrate that the amnion cells are actively involved in the synthesis of SP1 and could account for the high level of this glycoprotein in amniotic fluid.

Amnion↗
PubMed1981

Oncofoetal antigens in cancer of the cervix and ovary.

The incidence of oncofoetal antigens has been reported to be increased in patients with gynaecological cancers. In this study the incidence of CEA, AFP, and hCG (beta subunit) were studied in patients with adenocarcinoma of the ovary, adenocarcinoma of the cervix, and squamous-cell carcinoma of the cervix. Using a low cut-off point (CEA 2.5 microgram/l, AFP 5 microgram/l, and hCG 3 i.u./l) there is an unacceptably high proportion of control patients having one or more positive tests (42-54%) compared to cancer-bearing patients (67%). The specificity of the tests can be increased to over 95% by increasing the cut-off point to CEA 10 microgram/l, AFP 10 microgram/l, and hCG 10 i.u./l). Although this reduces the sensitivity considerably, the incidence of false positives in the control population is reduced to nil in non-cancer patients and to 2% in cancer patients tested when free of tumour, compared to 17% of patients with cancer of the ovary, 33% with adenocarcinoma of the cervix, and 6% with squamous-cell carcinoma of the cervix. Patients with adenocarcinoma of the cervix were clearly distinguishable from those with squamous-cell carcinoma of the cervix by these tests. There was also a significant correlation between AFP and hCG levels in adenocarcinoma of the cervix (r = 0.53, P less than 0.05).

Adenocarcinoma↗