Search PubMed⌕ Search

Biomedical subjects

N H Kim

Publications and source records attributed to N H Kim.

At least 109 records · Page 6Linked to original sources
PubMed1997

Chlortetracycline fluorescence patterns and in vitro fertilisation of frozen-thawed boar spermatozoa incubated under various bicarbonate concentrations.

Porcine oocyte-cumulus complexes were cultured in bovine serum albumin (BSA)-free North Carolina State University (NCSU) 23 medium containing porcine follicular fluid (10%), cysteine (0.1 mg/ml) and hormonal supplements (eCG and hCG: 10 IU/ml each) for 22h. They were then cultured in the same medium but without hormonal supplements for an additional 22 h. After culture, cumulus cells were removed and oocytes were co-incubated with frozen-thawed ejaculated boar spermatozoa in tissue culture medium (TCM) 199 containing caffeine (5 mM), fetal calf serum (FCS; 10%) and varying concentrations (26-56 mM) of NaHCO3 for 9 h (experiment 1). In experiment 2, chlortetracycline (CTC) was used to assess the functional state of spermatozoa incubated under different NaHCO3 concentrations. Experiment 3 examined the effect of FCS (1% and 10%) and NaHCO3 (26 and 46 mM) on fertilisation parameters. Compared with 26 mM, penetration rate was significantly higher (p < 0.05) at 36-56 mM NaHCO3. Polyspermy showed a similar pattern although no difference was observed between 26 and 36 mM. At 46 mM NaHCO3, the mean number of spermatozoa (MNS) penetrated per oocyte increased significantly (p < 0.05). A significantly higher proportion of spermatozoa were capacitated and acrosome reacted at 46 and 56 mM NaHCO3, respectively. The fertilisation medium containing 46 mM NaHCO3 and 1% FCS showed a higher penetration rate (84%) with a relatively low incidence of polyspermy (39%). The results indicate that NaHCO3 stimulates capacitation and/or the acrosome reaction of boar spermatozoa in a dose-dependent manner and thus affects fertilisation parameters.

Animals↗
PubMed1997

Blastocoele formation and cell allocation to the inner cell mass and trophectoderm in haploid and diploid pig parthenotes developing in vitro.

The objective of this study was to determine developmental pattern and cell allocation to the inner cell mass and trophectoderm in haploid and diploid embryos following parthenogenetic activation. In vitro matured porcine oocytes were activated by ethanol treatment and cultured in the presence or absence of cytochalasin B for 5 h. The oocytes were then cultured in the NCSU23 for 9 days. The combined treatment with cytochalasin B following ethanol treatment did not increase (p > 0.1) the incidence of activation. The incidence of development to the blastocyst stage was higher (p < 0.05) in the combined treatments of ethanol and cytochalasin B as compared with ethanol treatment alone. The percentage of oocytes with two female pronuclei was higher (p < 0.01) in oocytes treated with cytochalasin B than that in ethanol treatment alone. Treatment with both ethanol and cytochalasin B increased (p < 0.01) the incidence of diploid chromosome spread over just the ethanol treatment alone. The average numbers of total cells and inner cell mass were significantly reduced (p < 0.05) in the ethanol treatment alone as compared with the combined cytochalasin B and ethanol treatment. These results suggested that the ploidy may affect blastocoele formation and cell allocation to inner cell mass and trophectoderm in the pig.

Animals↗
PubMed1997

Effect of cytochalasin B and cycloheximide on the activation rate, chromosome constituent and in vitro development of porcine oocytes following parthenogenetic stimulation.

Activation rate, chromosome constituent and developmental pattern of porcine oocytes was examined in the presence and absence of cytochalasin B and cycloheximide following parthenogenetic stimulation. Treatment with cycloheximide after ethanol or Ca2+ ionophore treatment increased the incidence of activation. The percentage of oocytes with two or more female pronuclei was higher (P < 0.05) in oocytes treated with cytochalasin B than in control or cycloheximide-treated oocytes. Treatment with both electrical stimulation and cytochalasin B increased the incidence of diploid chromosome spreads, and accelerated development to the morula and blastocyst stage compared with the control and cycloheximide-treated groups, suggesting a role of ploidy in the development of parthenote.

Animals↗
PubMed1997

The distribution and requirements of microtubules and microfilaments during fertilization and parthenogenesis in pig oocytes.

Microtubules and microfilaments are major cytoskeletal elements in mammalian ova and are important modulators of many fertilization and post-fertilization events. In this study, the integrated distribution of microtubules and microfilaments in pig oocytes were examined under a laser scanning confocal microscope, and the requirements of their assembly during in vitro fertilization and parthenogenesis in in vitro matured pig oocytes were determined. After sperm penetration, an aster of microtubules was produced in the spermatozoon, and this microtubule aster filled the whole cytoplasm during pronuclear movement. During pronuclear formation after activation by insemination, microfilaments became concentrated at the male and female pronuclei and, after electrical stimulation, at the female pronucleus. At metaphase of cleavage, microtubules were detected in the spindle and microfilaments were found mainly in the cortex. At anaphase, microtubule asters assembled at each spindle pole. During cleavage, large asters filled each daughter blastomere and a microfilament-rich cleavage furrow was observed. Cytochalasin B, a microfilament inhibitor, inhibited microfilament polymerization but affected neither pronuclear formation nor movement. However, syngamy and cell division were inhibited in eggs treated with cytochalasin B. Treatment with nocodazole after sperm penetration inhibited microtubule assembly and prevented migration leading to pronuclear union and cell division. These results indicate that microtubule and microfilament assembly in pig oocytes are integrated during fertilization and are required for the union of sperm and egg nuclei and for subsequent cell division.

Actin Cytoskeleton↗
PubMed1997

Effect of different concentrations of potassium on pig embryos developing in vitro.

The effects of varying the potassium concentration in Whitten's medium on the development of pig embryos in vitro was investigated. Osmolality was maintained by adjusting the NaCl concentration. In Expt I, 209 one-cell to early blastocyst stage embryos were individually cultured in 50 microliters microdrops of glucose-free Whitten's medium containing 0.4% (w/v) BSA and 1.5, 3.0, 6.0 or 12.0 mmol potassium l-1. The percentages of embryos undergoing blastocoel formation and expansion for each cell stage evaluated did not differ (P > 0.10) among the various concentrations of potassium. However, more four-cell embryos commenced hatching in 3.0 mmol potassium l-1 (53%) than in 1.5 mmol potassium l-1 (16%) (P < 0.05) and 12.0 mmol potassium l-1 (24%) (P < 0.10). The time required for embryos to develop blastocoels, expand and initiate hatching was not affected (P > 0.10) by the concentration of potassium in the medium. However, blastocoel formation by one- to two-cell embryos was delayed (P < 0.05) in medium with 1.5 mmol potassium l-1. In Expt 2, 89 four-cell embryos were cultured in medium containing 6.0 or 24.0 mmol potassium l-1. No differences (P > 0.10) were observed in the percentages of embryos undergoing blastocoel formation, expansion and hatching or in the time required to develop to these stages. The number of cells in embryos recovered at 96 h was greater (P < 0.05) in medium containing 6.0 compared with 24.0 mmol potassium l-1 (32.9 +/- 1.7 versus 26.9 +/- 2.1, respectively). These results demonstrate that pig embryos are tolerant to a wide range of potassium concentrations when the osmolality of the medium is maintained by adjusting the NaCl concentration. These results also suggest that limitations in development due to culture conditions are not due to inappropriate concentrations of this ion.

Animals↗
PubMed1997

Effects of altered body fluid balance and high blood pressure on the plasma brain natriuretic peptide in rats.

The present study was aimed to investigate the regulatory mechanisms of BNP release. Effects of acute and chronic perturbations in body fluid balance, changes in BP, and regulatory roles of NO and endothelin systems on BNP release were examined in rats. Although acute extracellular volume expansion did not have significant effects on plasma BNP, prolonged high-salt intake increased plasma BNP levels. Plasma BNP levels were also higher in 2K1C rats compared with the control. Although infusion of L-NAME increased the plasma BNP in control, it did not further affect the plasma BNP in rats with high-salt intake. Although L-arginine (20 mg.kg-1 per min) per se did not have significant effects on plasma BNP, it blocked the stimulatory effect of L-NAME (200 micrograms.kg-1 per min). Plasma BNP was severalfold increased following a single injection of endothelin (0.3 micrograms/kg) in normal and high-salt intake groups, the magnitude of which was not significantly affected by the high-salt intake. Although indomethacin did not have significant effects on plasma BNP in normal rats, it blocked the stimulatory effect of 2K1C hypertension. It is concluded that BNP is regulated by chronic changes in body fluid balance and blood pressure. It is also suggested that endothelin and NO systems may directly regulate the secretion of BNP in vivo. An endogenous prostaglandin synthesis may be involved in the stimulated release of BNP in hypertension.

Animals↗
PubMed1997

Design of a medical image processing software for clinical-PACS.

Software modules for interactive display, manipulation and retrieval of medical images have been designed for a Picture Archiving and Communications System (PACS). The target of these modules is not for a high-end diagnostic workstation for radiologists, but for a PC-based low cost clinical workstation for a referring physician. This software is constructed based on a concept of an object-oriented language which is designed to be modular and expandable. It consists of several functional modules: (a) a communication module for image retrieval, (b) a standard module for the interpretation of the DICOM images, (c) a user interface module for the non-computer oriented clinicians and (d) a tool module for viewing and manipulating images as well as editing the annotation.

Image Processing, Computer-Assisted↗
PubMed1997

Attenuated central pressor response to nitric oxide synthesis inhibition in chronic renal failure rats.

OBJECTIVES: Central and peripheral roles of nitric oxide (NO) in blood pressure regulation have been suggested. The present study was aimed at examining if the role of NO in blood pressure regulation is altered in chronic renal failure. METHODS: Blood pressure responses to acute inhibition of NO were examined in 5/6 nephrectomized rats. Three weeks after the renal ablation, under thiopental (50 mg/kg, i.p.) anesthesia, an intracerebroventricular cannula was placed in the left lateral ventricle and the femoral vein was cannulated to serve as an infusion route. The arterial blood pressure was measured in the right femoral artery. NG-nito-L-arginine methyl ester (L-NAME) was infused (100 microgram/kg per min for 60 min either intracerebroventricularly or intravenously. RESULTS: Chronic renal failure rats showed a significantly higher arterial pressure than the control rats (147 +/- 14 mmHg vs. 122 +/- 13 mmHg). Intracerebroventricular L-NAME did not affect the arterial pressure in chronic renal failure rats (0.5 +/- 4 mmHg increase from the basal), while it significantly increased the arterial pressure in normal rats (22 +/- 3 mmHg increases from the basal). Intravenous L-NAME increased the arterial pressure, the magnitude of which did not differ between the normal and chronic renal failure rats (24 +/- 3 vs. 16 +/- 3 mmHg increases from the basal). CONCLUSION: These results indicate that the central role of NO in the regulation of blood pressure is altered in chronic renal failure.

Analysis of Variance↗
PubMed1997

A case of carpal tunnel syndrome due to dialysis-related amyloidosis in a patient undergoing long-term hemodialysis.

Carpal tunnel syndrome (CTS) is characterized by burning pain, numbness and tingling sensation in the thumb, index and middle fingers and the lateral half of the palm and progressive atrophy of the thenar muscles by compression of the median nerve within the carpal tunnel due to a variety of etiologic factors. Surgical intervention usually successfully relieves symptoms of CTS. Recently CTS has been regarded as one of the major clinical manifestations of dialysis-related amyloidosis due to beta 2-microglobulin deposition and recognized with increasing frequency in patients undergoing long-term hemodialysis. We report a case of carpal tunnel syndrome due to dialysis-related amyloidosis in patients undergoing long-term hemodialysis, confirmed by electromyography and biopsy in transverse carpal ligament and median nerve.

Amyloid Neuropathies↗
PubMed1997

The role of transitional vertebrae in spondylolysis and spondylolytic spondylolisthesis.

Transitional lumbar vertebrae include lumbarization and sacralization of the lumbosacral region. This study was performed to evaluate the relationship of transitional vertebra to spondylolytic spondylolisthesis such as the incidence and degree of slippage and to ascertain the clinical relevance for treatment. The study included 182 cases with 33 cases (18.1%) of transitional vertebra, 12 cases of lumbarization, and 21 cases of sacralization. The remaining 149 cases constituted the control group. The degree of the anterior slippage of the vertebral body was measured by Meyerding's grading and the percentage of the anterior slippage was measured by Taillard's method. In the patients with lumbarization and the isthmic defects in the fourth lumbar spine, the average slip of L4 was 14.5%. While patients with sacralization and the isthmic defects in L4, the average slip of L4 was 19.3%. The average slip of L4 was 11.4% in the control group. In patients with lumbarization and the isthmic defects in the fifth lumbar vertebra, the average slip of L5 was 12.5%. While in patients with sacralization and the isthmic defects in L5, the average slip of the L5 vertebra was 9.5%. The average slip of L5 was 16.2% in the control group. The patients with sacralization and the isthmic defects in L4 showed more anterior slippage than the patients with the isthmic defect in L4 without transitional vertebrae. The patients with sacralization and the isthmic defects in L5 showed less anterior slippage than the patients with isthmic defects in L5 without transitional vertebrae. From this it can be concluded that more aggressive treatment is recommended in the patients with sacralization and isthmic defects in L4, whereas more conservative treatment is recommended in the patients with sacralization and the isthmic defects in L5.

Adult↗
PubMed1996

Microtubule and microfilament dynamics in porcine oocytes during meiotic maturation.

Microtubule and microfilament organization in porcine oocytes during maturation in vivo and in vitro was imaged by immunocytochemistry and laser scanning confocal microscopy. At the germinal vesicle stage, microtubules were not detected in the oocyte. After germinal vesicle breakdown, a small microtubule aster was observed near the condensed chromatin. During the prometaphase stage, microtubule asters were found in association with each chromatin mass. The asters then elongated and encompassed the chromatin at the metaphase-I stage. At anaphase-I and telophase-I microtubules were detected in the meiotic spindle. Microtubules were observed only in the second meiotic spindle at the metaphase-II stage. The meiotic spindle was a symmetric, barrel-shaped structure containing anastral broad poles, located peripherally and radially oriented. Taxol, a microtubule-stabilizing agent, did not induce microtubules in oocytes at the germinal vesicle stage. After germinal vesicle breakdown, numerous cytoplasmic foci of microtubules were formed in the entire oocyte when oocytes were incubated in the presence of taxol. Microfilaments were observed as a relatively thick uniform area around the cell cortex and were also found throughout the cytoplasm of oocytes at the germinal vesicle stage. After germinal vesicle breakdown, the microfilaments were concentrated close to the female chromatin. During prometaphase, microfilaments were chromatin moved to the peripheral position. At metaphase-I, two domains, a thick and a thin microfilament area, existed in the egg cortex. Chromosomes were located in the thick microfilament domain of the cortex. In summary, these results suggest that both microtubules and microfilaments are closely involved with chromosomal dynamics after germinal vesicle breakdown and during meiotic maturation in porcine oocytes.

Actin Cytoskeleton↗
PubMed1996

Cytoskeletal alteration in aged porcine oocytes and parthenogenesis.

The objective of this study was to examine the changes in microtubule and microfilament assembly in aged porcine oocytes and to determine their developmental pattern after parthenogenetic activation. Porcine oocytes were cultured in Whitten's medium containing 10% follicular fluid with hormonal supplements (eCG and hCG) for 22 hr and 40 hr additional culture without hormonal supplements. At 40, 50, and 60 hr of culture, the oocytes were fixed for immunocytochemistry or activated by electrical pulse. In metaphase II stage oocytes, microtubules were detected only in the meiotic spindle. Two microfilament domains existed in the egg cortex, a thick and a thin microfilament domain. In aged oocytes (50 and 60 hr of culture), the incidence of metaphase II plates observed outside of the thick microfilament domain was higher (P < 0.05) than in young oocytes (40 hr of culture). After activation, a polar body was usually emitted from the chromatin at the microfilament rich domain or two pronuclei were formed outside of the microfilament rich domain. The percentage of activated oocytes with one female pronucleus was higher (P < 0.05) in oocytes at 40 hr of maturation than at 50 and 60 hr of culture. At 24 and 30 hr after stimulation the incidence of cleavage to the 3- to 4-cell stage was higher (P < 0.05) in aged oocytes (50 and 60 hr of maturation) than that in oocytes at 40 hr of culture. These results suggested that a role of microfilaments is to retain the chromatin at the proper position in the oocyte cortex, and that aging results in a disruption of the microfilaments such that atypical development results after parthenogenetic activation.

Actin Cytoskeleton↗
PubMed1996

A study of motor and sensory evoked potentials in chronic cauda equina compression of the dog.

Previous experimental studies have shown the effects of acute compression of the spinal cord and peripheral nerve roots. Recently, however, a few studies of chronic compression of the cauda equina in animal models have been reported. The purpose of this study was to determine the long-term electrophysiologic changes resulting from chronic compression of the cauda equina in dogs. An animal model of lumbar spinal stenosis was prepared according to Delamarter's method. Four experimental groups, each containing six dogs, were studied. One group underwent only laminectomy of the sixth and seventh lumbar vertebrae; these animals served as controls. In the three other groups, a laminectomy was performed and the cauda equina was constricted by 25%, 50%, and 75%, respectively, to produce chronic compression. Weekly neurologic examinations were carried out, and the neurologic deficits were graded using a modified Tarlov system. Sensory, and motor evoked potentials were recorded preoperatively, immediately after constriction, and at 2 weeks and 1, 2, and 3 months postoperatively. The animals in the control group showed no changes in sensory or motor evoked potentials. The dogs in which the cauda equina had been constricted by 25% showed no neurologic deficits and only mild changes in sensory and motor evoked potentials. The dogs in which the cauda equina had been constricted by 50% showed mild initial motor weakness, and major changes in the evoked potentials. The dogs in which the cauda equina had been constricted by 75% showed significant weakness, paralysis of the tail, and urinary incontinence; all dogs were partially recovered by the 3rd month, but all still showed neurogenic changes in the evoked potentials. Sensory and motor evoked potentials revealed neurologic abnormalities before the appearance of neurologic signs and symptoms. Constriction of more than 50% was the critical point that resulted in complete loss or reduction of the evoked potentials and in neurologic deficits. Dogs in which motor and sensory evoked potentials recovered also showed gradual disappearance of neurologic symptoms and signs. Recovery of motor evoked potentials in particular was associated with complete disappearance of neurologic symptoms and signs. For accurate prognosis in cases of chronic cauda equina compression, a combined diagnostic study of sensory and motor evoked potentials is recommended.

Analysis of Variance↗
PubMed1996

Microfilament assembly and cortical granule distribution during maturation, parthenogenetic activation and fertilisation in the porcine oocyte.

In this study we imaged integral changes in microfilament assembly and cortical granule distribution, and examined effects of microfilament inhibitor on the cortical granule distribution during oocyte maturation, parthenogenetic activation and in vitro fertilisation in the pig. The microfilament assembly and cortical granule distribution were imaged with fluorescent-labelled lectin and rhodamine-labelled phalloidin under laser scanning confocal microscopy. At the germinal vesicle stage, cortical granule organelles were located around the cell cortex and were present as a relatively wide area on the oolemma. Microfilaments were also observed in a wide uniform area around the cell cortex. Following germinal vesicle breakdown, microfilaments concentrated in the condensed chromatin and cortical granules were observed in the cortex. Treatment with cytochalasin B inhibited microfilament polymerisation and prevented movement of cortical granules to the cortex. Cortical granule exudation following sperm penetration was evenly distributed in the entire perivitelline space. These results suggest that the microfilament assembly is involved in the distribution, movement and exocytosis of cortical granules during maturation and fertilisation.

Actin Cytoskeleton↗
PubMed1996

Microtubule organization in porcine oocytes during fertilization and parthenogenesis.

Microtubule configurations in porcine oocytes after sperm penetration or after artificial activation by electrical stimulation were imaged by immunocytochemistry and laser scanning confocal microscopy. Soon after sperm penetration, an aster was seen adjacent to the incorporated sperm head. Polyspermic penetrations led to the presence of multiple sperm asters in association with each sperm. The sperm aster enlarged and, at the time of pronuclear apposition, filled the cytoplasm. After male and female gamete union, the microtubule matrix was reduced. At the mitotic metaphase stage, microtubules were detected in the spindle, which was anastral and fusiform. At anaphase, asters assembled at each spindle pole, and at telophase, large asters filled the cytoplasm. Artificial activation by electrical stimulation induced in the cytoplasm a dense network of microtubules, which seem to be involved in proper positioning of the female pronucleus. At mitotic metaphase, microtubules were concentrated around the chromatin. The results of experiments using taxol, a microtubule stabilizing agent, suggest that maternal centrosomal material is present in the mature porcine oocyte as dispersed undetectable material that can form a microtubule network after parthenogenetic activation. However, at fertilization, the paternal centrosome collects centrosomal material to form a sperm aster. These results suggest that the functional centrosome that forms during fertilization is a result of the blending of paternal and maternal centrosomal components.

Animals↗
PubMed1996

Presence of organic osmolytes in maturation medium enhances cytoplasmic maturation of porcine oocytes.

The effects of organic osmolytes on cytoplasmic maturation of porcine oocytes were examined in maturation medium (modified Whitten's medium) containing various NaCl concentrations. The presence of organic osmolytes, such as taurine and sorbitol, at 6 and 12 mM in maturation medium containing 68.49 or 92.40 mM NaCl increased oocyte glutathione content. Microfilament organization in oocytes was disrupted in maturation medium containing the higher level of NaCl (92.40 mM). However, supplementation with 12 mM sorbitol to the medium reduced the severity of the abnormality. Early embryonic development in vitro to the blastocyst stage was 8.3 +/- 0.9% for oocytes matured in modified Whitten's medium (68.49 mM NaCl) supplemented with 12 mM sorbitol, and 7.9 +/- 0.8% in modified NCSU23 medium (containing 108.73 mM NaCl, 7 mM taurine, 5 mM hypotaurine, and 1 mM glutamine), compared to 4.7 +/- 0.6% in modified Whitten's medium (68.49 mM Na Cl), which did not contain organic osmolytes. These results indicate that the presence of organic osmolytes, such as sorbitol and taurine, reduces the detrimental effects of high NaCl concentration in media used for the maturation of porcine oocytes. This effect is reflected by oocyte glutathione content and microfilament organization at the end of maturation and early development following in vitro maturation and in vitro fertilization.

Animals↗