Biomedical subjects

E Ko

Publications and source records attributed to E Ko.

At least 37 records · Page 2Linked to original sources

PubMed2000

Direct competitive enzyme-linked immunosorbent assay for sulfamethazine.

A direct competitive enzyme-linked immunosorbent assay (ELISA) for screening sulfamethazine (SMZ) in pork tissues was developed. The assay was made with the affinity-purified polyclonal antibody-coated microtiter plate. A cross reactivity of IgG was observed at 3.5 microg/g of sulfamerazine among nine kinds of sulfonamide tested. Pork tissues fortified with SMZ was mixed with octadecyl silica (C18), and extracted with dichloromethane. The extracted SMZ was measured by homemade ELISA, commercial ELISA, and HPLC. The results were correlated (r=0.993, p<0.01). The homemade ELISA was sensitive to determine SMZ at the maximum residue level (MRL) as commercial one. During stability test of the IgG coated microtiter plate performed at 40 degrees C for 14 days, no difference in sensitivity was observed. We developed homemade ELISA with a detection limit of 10 ng of SMZ per g of pork tissues, and it could be used to screen SMZ in pork tissues.

Animals↗

PubMed1999

Analysis of sperm chromosome complements before, during, and after chemotherapy.

Sperm chromosomal abnormalities were assessed in testicular cancer patients before, during, and after BEP (bleomycin, etoposide, cisplatin) chemotherapy (CT). Multicolor fluorescence in situ hybridization (FISH) analysis was employed to detect aneuploidy for chromosomes 1, 12, X, and Y, and diploidy. Sperm samples were cryopreserved and coded before analysis to facilitate "blind" analysis. Complete results at all time points was available for only one patient. A total of 60,400 sperm were analyzed: 20,004 before CT, 20,005 during CT, and 20,391 after CT. There was a significant increase in the frequency of 24,XY sperm during (0.33%) and post-CT (0.34%) compared to pre-CT (0.14%). This study suggests that there may be a significantly increased risk of chromosomal abnormalities in sperm of CT patients during and immediately post-CT, similar to that shown in animal models.

Adult↗

PubMed1999

Coronary vasodilator effects of BNP: mechanisms of action in coronary conductance and resistance arteries.

Brain natriuretic peptide (BNP), a hormone secreted predominantly in ventricular myocytes, may influence coronary vascular tone. We studied the coronary vasodilatory response to BNP under physiological conditions and after preconstriction with endothelin-1 (ET-1) in anesthetized pigs. Average peak-flow velocity (APV) was measured using intracoronary Doppler, and cross-sectional area (CSA) was measured using intravascular ultrasound. Coronary blood flow (CBF) was calculated. Intracoronary BNP induced dose-dependent increases in CSA, APV, and CBF similar in magnitude to those induced by nitroglycerin (NTG). The magnitude of BNP-induced vasodilation was accentuated after preconstriction with ET-1. Pretreatment with either the nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester or the cyclooxygenase inhibitor indomethacin attenuated the coronary vasodilator effect of BNP in resistance arteries without influencing epicardial vasodilation. Pretreatment with the ATP-sensitive potassium-channel blocker glibenclamide enhanced epicardial vasodilation in response to BNP. We conclude that BNP exerts coronary vasodilator effects, predominantly in epicardial conductance vessels. An accentuated vasodilatory response to BNP occurs in ET-1-preconstricted arteries. BNP-induced vasodilation in coronary resistance arteries may be partially mediated via nitric oxide and/or prostaglandin release.

Animals↗

PubMed1998

Abnormalities for chromosomes 13 and 21 detected in spermatozoa from infertile men.

Sperm samples from infertile men with oligozoospermia or teratozoospermia were studied by multicolour fluorescence in-situ hybridization (FISH) using DNA probes for chromosomes 13 and 21. A total of 90 809 sperm nuclei from nine infertile men and 182 799 sperm nuclei from 18 control donors were analysed. There was a highly significant increase in the frequency of spermatozoa disomic for chromosome 13 in infertile patients (0.28%) compared to control donors (0.13%) (two-tailed Z statistic P < 0.0001) and for chromosome 21 (0.48% in infertile men versus 0.37% in controls, P < 0.0001). Also there was a significantly increased frequency of diploid spermatozoa in infertile men (0.85%) compared to control donors (0.66%) (P < 0.0001). Our previous studies on these same infertile patients demonstrated increased frequencies of sperm disomy for chromosomes 1 and XY. This suggests that infertile men, who are prime candidates for intracytoplasmic sperm injection, may be at a very small increased risk of aneuploid offspring.

Adult↗

PubMed1997

Physiological concentrations of estradiol attenuate endothelin 1-induced coronary vasoconstriction in vivo.

BACKGROUND: Estrogens are cardioprotective hormones and are reported to have antianginal properties. We examined the effect of physiological concentrations of 17beta-estradiol on coronary reactivity in anesthetized female farm pigs. METHODS AND RESULTS: Epicardial coronary cross-sectional area (CSA) was assessed by two-dimensional intravascular ultrasound, average coronary peak flow velocity (APV) by intravascular Doppler velocimetry, and coronary blood flow (CBF) was calculated. Dose-response curves to intracoronary endothelin-1 (ET-1, 1 pmol/L to 10 nmol/L), the selective ET(B) receptor agonist sarafotoxin (1 pmol/L to 10 nmol/L), and serotonin (0.1 nmol/L to 1 micromol/L) were assessed before and after a 10-minute infusion of intracoronary estradiol (1 nmol/L). Before estradiol administration, ET-1 induced significant dose-dependent decreases in CSA, APV, and CBF. Estradiol attenuated ET-1-induced epicardial vasoconstriction (P<.001) as well as ET-1-induced decreases in APV (P=.05) and CBF (P=.012). In an additional five pigs, vehicle (DMSO) had no effect on ET-1-induced coronary vasoconstriction. Before estradiol administration, sarafotoxin induced no net change in CSA but induced increases in APV and CBF, the extent of which did not change significantly after estradiol. Serotonin induced small decreases in CSA but increased APV and CBF. Estradiol did not influence serotonin-induced changes in CSA, APV, or CBF. CONCLUSIONS: We conclude that estradiol attenuates ET-1-induced vasoconstriction, possibly through effects on the ET(A) receptor, because selective ET(B) receptor-induced stimulation with sarafotoxin remained unchanged. Such an effect on the ET(A) receptor may relate to the antianginal properties of estrogens.

Animals↗

PubMed1997

Neuronal alpha-bungarotoxin receptors differ structurally from other nicotinic acetylcholine receptors.

We have characterized the alpha-bungarotoxin receptors (BgtRs) found on the cell surface of undifferentiated pheochromocytoma (PC12) cells. The PC12 cells express a homogeneous population of alpha7-containing receptors that bind alpha-Bgt with high affinity (Kd = 94 pM). The BgtRs mediate most of the response elicited by nicotine, because the BgtR-specific antagonists methyllycaconitine and alpha-Bgt block approximately 90% of the whole-cell current. The binding of nicotinic agonists to cell-surface BgtRs was highly cooperative with four different agonists showing Hill coefficients in the range of 2.3-2.4. A similar agonist binding cooperativity was observed for BgtR homomers formed from chimeric alpha7/5HT3 subunits expressed in tsA 201 cells. Two classes of agonist binding sites, in the ratio of 4:1 for PC12 cell BgtRs and 3:1 for alpha7/5HT3 BgtRs, were revealed by bromoacetylcholine alkylation of the reduced sites on both PC12 BgtRs and alpha7/5HT3 BgtRs. We conclude from this data that PC12 BgtRs and alpha7/5HT3 homomers contain at least three distinguishable agonist binding sites and thus are different from other nicotinic receptors.

Acetylcholine↗

PubMed1997

Fetoscopic and open transumbilical fetal cardiac catheterization in sheep. Potential approaches for human fetal cardiac intervention.

BACKGROUND: Shortening the prenatal disease course of severe aortic and pulmonary stenoses by balloon valvuloplasty may diminish their postnatal expression. The purpose of this study in fetal sheep was to assess the feasibility of fetoscopic and open transumbilical fetal cardiac catheterization guided by fetal transesophageal echocardiography to provide alternative approaches for human fetal cardiac intervention. METHODS AND RESULTS: We studied a total of nine fetal sheep (95 to 103 days of gestation; term = 145 to 150 days) and performed transumbilical fetal cardiac catheterization by a minimally invasive fetoscopic (n = 6) or an open fetal surgical approach (n = 3). Monitored by fetal transesophageal echocardiography, with an 8F or 10F, 10-MHz intravascular ultrasound catheter we placed guidewires and interventional catheters via the umbilical arterial route into the fetal heart. In three of the fetuses, we created supravalvar pulmonary artery stenosis by open fetal cardiac surgery After fetal and maternal recovery, we exteriorized these fetuses and performed open transumbilical fetal cardiac catheterization with successful pulmonary arterial angioplasty in two. Three fetuses survived fetoscopic transumbilical catheterization for 1 or 2 days and died most likely of blood loss after sheath dislodgment (n = 1) or removal (n = 2). By securing the sheath insertion site with a suture, we prevented sheath dislodgment and minimized bleeding during sheath removal in three fetuses. These fetuses then survived fetoscopic transumbilical fetal cardiac catheterization for 1 to 2 weeks before being killed. CONCLUSIONS: This study in fetal sheep demonstrates that fetoscopic and open transumbilical fetal cardiac catheterization are feasible and, guided by fetal transesophageal echocardiography, provide potential alternative approaches for human fetal cardiac intervention.

Angioplasty, Balloon↗

PubMed1997

Use of intravascular ultrasound in evaluating repeated balloon rupture during coronary stenting.

Balloon rupture during coronary angioplasty is a well-recognized complication of PTCA. Coronary angiography commonly fails to elicit the cause of balloon perforation. We present a case with multiple balloon rupture during additional high-pressure inflations of a Palmaz-Schatz stent where intravascular ultrasound was useful in revealing a calcified lesion protruding through the struts of the stent.

Aged↗

PubMed1997

Chromosomal abnormalities in sperm from testicular cancer patients before and after chemotherapy.

Sperm chromosome abnormalities were assessed in testicular cancer patients before and after treatment with BEP (bleomycin, etoposide, cisplatin). The frequencies of disomy for chromosomes 1, 12, X, Y and XY were assessed along with diploid frequencies and sex ratios by multicolour fluorescence in situ hybridization (FISH). For each cancer patient, a minimum of 10,000 sperm was assessed for each chromosome probe before and after chemotherapy (CT). Data was analysed "blindly" by coding the slides. A total of 161097 sperm were analyzed, 80,445 before and 80,642 after treatment. The mean disomy frequencies were 0.11% pre-CT vs 0.06% post-CT for chromosome 1, 0.18% vs 0.15% for chromosome 12, 0.10% vs 0.9% for the X chromosome, 0.13% vs 0.10% for the Y chromosome and 0.25% vs 0.20% for XY sperm. There was no significant difference in the frequency of disomy pre-CT vs post-CT for any chromosome except that chromosome 1 demonstrated a significant decrease after CT. The "sex ratios" and frequency of diploid sperm were also not significantly different in pre and post-CT samples with 50.2% X-bearing sperm pre-CT and 50.5% X post-CT and 0.14% diploid sperm pre-CT vs 0.15% diploid sperm post-CT. There was no significant donor heterogeneity among the cancer patients. None of the values in the cancer patients differed significantly from 10 normal control donors. Thus our study suggests that BEP chemotherapy does not increase the risk of numerical chromosomal abnormalities in human sperm.

Adult↗

PubMed1997

Reliability of estimates of diploid human spermatozoa using multicolour fluorescence in-situ hybridization.

Multicolour fluorescence in-situ hybridization (FISH) analysis permits distinction between disomic and diploid spermatozoa. Thus estimates of the frequency of diploid spermatozoa can be obtained for human semen samples. The issue of the accuracy and reliability of these diploidy estimates has been addressed by analysing diploidy frequencies in 10 men using the same sperm sample to estimate diploidy twice-once during two-colour FISH analysis of disomy for chromosomes 1 and 12 and a second independent analysis of three-colour FISH for disomy estimates for chromosomes X and Y (with chromosome 1 used as the autosomal control). A minimum of 10,000 spermatozoa per hybridization per male was counted for a total of over 200,000 spermatozoa analysed. The mean frequency of diploid spermatozoa was 0.13% for the autosomal study and 0.14% for the sex chromosomal study, which were not significantly different. One donor had extremely divergent values of diploidy in the two studies. Analysis of values in the other nine donors demonstrated no significant difference in the two diploidy estimates. These results indicate that the FISH technique is an accurate and reliable method for determining diploid frequencies in human spermatozoa.

Cell Nucleus↗

PubMed1997

Transesophageal echocardiography in rats using an intravascular ultrasound catheter.

In vivo assessment of cardiac structure and function in small animals is an important experimental goal, but currently available techniques have significant limitations. A commercially available intravascular ultrasound (IVUS) system was adapted to perform transesophageal echocardiography (TEE) in rats. Twelve Sprague-Dawley rats (270-370 g) were anesthetized with intraperitoneal pentobarbital sodium. A 4.3-Fr, 30-MHz or an 8-Fr, 20-MHz IVUS catheter was inserted into the esophagus to obtain long-axis views of the aortic arch, short-axis views of the ascending aorta, and long-axis views of the pulmonary artery. A preshaped, 8-Fr, 20-MHz catheter was used to obtain short-axis images of the left ventricle (LV) at the midpapillary muscle level, which were used to measure LV diastolic and systolic dimensions (diameters) and to calculate LV mass and fractional shortening. Measurements by TEE were compared with those obtained by transthoracic echocardiography in 6 of 12 rats. Postmortem, the LV was weighed to determine actual LV mass. The correlation coefficients between TEE- and transthoracic echocardiography-calculated LV mass and actual LV mass were 0.94 and 0.88, respectively, and had a good agreement with actual LV mass. Inter- and intraobserver variability of TEE measurements was <10%. IVUS instrumentation may offer an alternative technique for the accurate, serial assessment of LV dimensions, mass, and systolic function and a means of imaging the great vessels in small laboratory animals.

Animals↗

PubMed1997

Analysis of human sperm karyotypes in testicular cancer patients before and after chemotherapy.

Sperm karyotype analysis was performed on testicular cancer patients before and after treatment with BEP (bleomycin, etoposide, and cisplatin). A total of 788 sperm chromosome complements was studied, 236 before chemotherapy (CT) and 552 post-CT. There was no significant difference in the total frequency of sperm chromosomal abnormalities pre-CT (10.2%) compared to post-CT (10.7%). Similarly, there were no significant differences in the frequencies of numerical abnormalities (2.5% pre-CT vs. 2.4% post-CT) or structural abnormalities (6.4% pre-CT vs. 7.4% post-CT). The percentage of X-bearing sperm was also not significantly different before (46.3%) and after CT (50.1%). The results in cancer patients were not significantly different from those in control donors. This study corroborates results from our previous analysis of these same men using multicolor fluorescence in situ hybridization for assessment of aneuploidy for chromosomes 1, 12, X, Y, and XY. Together, these two studies suggest that the sperm of men receiving BEP chemotherapy are not at increased risk of chromosomal abnormalities two or more years after treatment.

Adult↗

PubMed1996

Testosterone induces dilation of canine coronary conductance and resistance arteries in vivo.

BACKGROUND: Although estrogens have been shown to be vasoactive hormones, the vascular effects of testosterone are not well defined. Like estrogen, testosterone causes relaxation of isolated rabbit coronary arterial segments. We examined the vasodilator effects of testosterone in vivo in the coronary circulation and the potential mechanisms of its actions. METHODS AND RESULTS: Using simultaneous intravascular two-dimensional and Doppler ultrasound, we examined the effect of intracoronary testosterone in coronary conductance and resistance arteries in 10 anesthetized dogs (5 male, 5 female). We also assessed the contribution of NO, prostaglandins, ATP-sensitive K+ channels, and classic estrogen receptors to testosterone-induced vasodilation. Testosterone induced a significant increase in cross-sectional area, average coronary peak flow velocity, and calculated volumetric coronary blood flow at the 0.1 and 1 mumol/L concentrations. This effect was independent of sex. Pretreatment with N omega-nitro-L-arginine methyl ester to block NO synthesis decreased testosterone-induced increase in cross-sectional area, average coronary peak flow velocity, and coronary blood flow. Pretreatment with glybenclamide to assess the role of ATP-sensitive K+ channels did not influence testosterone-induced dilation in epicardial arteries but did attenuate its effect in the microcirculation. Pretreatment with indomethacin or the classic estrogen-receptor antagonist ICI 182,780 did not alter testosterone-induced changes. CONCLUSIONS: Short-term administration of testosterone induces a sex-independent vasodilation in coronary conductance and resistance arteries in vivo. Acute testosterone-induced coronary vasodilation of epicardial and resistance vessels is mediated in part by endothelium-derived NO. ATP-sensitive K+ channels appear to play a role in the vasodilatory effect of testosterone in resistance arteries.

Animals↗

PubMed1996

Transesophageal echocardiography in fetal sheep. A monitoring tool for open and fetoscopic cardiac procedures.

BACKGROUND: Cardiac procedures in exteriorized fetuses or assisted by fetoscopy require monitoring capabilities not attended by conventional maternal transabdominal echocardiography. METHODS: We, therefore, assessed the potential of fetal transesophageal echocardiography (TEE) utilizing an intravascular ultrasound catheter (IVUC) for fetal cardiac monitoring. We inserted a 10-F-10-MHz IVUC into the esophagus in 12 exteriorized fetal sheep and by a fetoscopic approach in 4 fetal sheep. Cardiac events were observed. Heart rate, cardiac rhythm, patency of the foramen ovale and ductus arteriosus, and the width of the branch pulmonary arteries could be assessed in all fetuses. Ventricular contractility could be assessed only in fetuses weighing less than 2.5 kg. Larger fetuses did not allow adequate imaging of the apical portion of the ventricles because of limited tissue penetration of the IVUC. Fetal TEE permitted placing small guide wires in the cardiac atria and left ventricle. Short-lived premature beats following intracardiac manipulations of these wires could be observed by fetal TEE in all cases. RESULTS: At autopsy, no complications from IVUC insertion were observed in the exteriorized fetuses. Fetoscopic placement of the IVUC resulted in minor perioral skin erosion in two nonexteriorized fetuses. CONCLUSIONS: In conclusion, fetal TEE can be achieved with minor fetal injury and may provide useful information during open and fetoscopic cardiac procedures. Further improvements in IVUC design will permit the application of this technique to monitor human fetal cardiac procedures.

Animals↗

PubMed1995

The relationship between paternal age, sex ratios, and aneuploidy frequencies in human sperm, as assessed by multicolor FISH.

We studied the frequencies of X- and Y-chromosome-bearing sperm, diploidy and disomy for chromosomes 1, 12, X, and Y in sperm from 10 normal men aged 21-52 years, to determine whether there was any relationship between donor age and any of these variables. Multicolor FISH was used to control for lack of probe hybridization and to distinguish diploid sperm from disomic sperm. A minimum of 10,000 sperm per donor was evaluated for each chromosome, for a total of 225,846 sperm studied. Sperm were considered disomic if two fluorescent signals were separated by a minimal distance of one signal domain. The mean frequencies of X- and Y-bearing sperm were 50.1% and 49.0%, respectively; not significantly different from 50%. There was no correlation between paternal age and "sex ratio" in sperm. Similarly, there was no association between the frequency of diploid sperm (mean, .16%; range, .06-.42%) and donor age. For disomy frequencies, there was no relationship between donor age and disomy 12 (mean, .16%; range, .10%-.25%), XX (mean, .07%; range, .03%-.17%), and XY sperm (mean, .16%; range, .08%-.24%). There was a significant increase in the frequency of YY sperm (P = .04; mean, .18%; range, .10%-.43%) and disomy 1 sperm (P = .01; mean, .11%; range, .05%-.18%) with donor age. In summary, our results do not support a correlation between paternal age and sex ratio or diploidy.

Adult↗

PubMed1994

Analysis of sperm chromosome complements from a man heterozygous for a pericentric inversion of chromosome 1.

Human sperm chromosomes were studied in a man heterozygous for a pericentric inversion of chromosome (1)(p31q12). Q-banded pronuclear chromosomes were analyzed after in vitro penetration of golden hamster oocytes. A total of 159 sperm were examined: 54% bearing the inverted chromosome 1 and 46% the normal chromosome 1. These frequencies are not significantly different from the theoretical 1:1 ratio. There were no recombinant sperm with duplications or deficiencies, suggesting that a pairing loop failed to form or that crossing-over was suppressed. The frequency of abnormalities unrelated to the inversion was 5% for numerical, 8.8% for structural, 2.5% for numerical and structural, values not significantly different from control donors studied in our lab. The frequencies of X- and Y-bearing sperm were 46% and 54%, respectively, not significantly different from the expected value of 50%. This is the fifth pericentric inversion studied by human sperm chromosome analysis; recombinant chromosomes have been observed in two of the five cases. Some of the factors associated with an increased risk of recombinant sperm appear to be inversion size greater than 30% of the chromosome and chromosome breakpoints in G-light bands.

Adult↗

PubMed1994

Detection of aneuploidy in human sperm by fluorescence in situ hybridization (FISH): different frequencies in fresh and stored sperm nuclei.

Fluorescence in situ hybridization (FISH) with chromosome-specific repetitive DNA probes provides a new method for rapid detection of aneuploidy in human sperm. There is widespread interest in this technique for basic research, as well as for screening men exposed to potential aneugens. A number of laboratories have reported a wide range in the frequency of aneuploidy for chromosomes in human sperm, suggesting that FISH may not reflect the true frequency accurately. We have serendipitously discovered that the length of time that fixed frozen sperm nuclei are stored affects both the hybridization efficiency and disomy frequency of individual chromosomes. This may explain some of the variation in the aneuploidy frequencies observed among laboratories.

Aneuploidy↗

PubMed1993

Detection of aneuploidy in human interphase spermatozoa by fluorescence in situ hybridization (FISH).

Fluorescence in situ hybridization (FISH) with repetitive-sequence DNA probes was performed on human interphase sperm to determine the utility of this technique for aneuploidy detection. DNA sequences specific for chromosomes 15 and 16 and the Y were biotinylated and hybridized with human sperm that had been treated with cetyltrimethylammonium bromide and dithiothreitol to render them accessible to the probes. Fluoresceinated avidin and antiavidin were utilized to visualize bound probe. More than 10,000 sperm were analyzed for each chromosome probe. The hybridization efficiency was 98-99% for all three probes. The frequencies for disomy (i.e., for nuclei containing two fluorescent signals) for chromosomes 15 and 16 and the Y were 0.14%, 0.17%, and 0.11%, respectively. These frequencies are all somewhat higher than those obtained by the human sperm karyotyping technique. Nevertheless, these preliminary results suggest that FISH is a simple and rapid technique that may provide an accurate screen for aneuploidy detection in human sperm.

Aneuploidy↗