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Biomedical subjects

J H Song

Publications and source records attributed to J H Song.

At least 73 records · Page 4Linked to original sources
PubMed1998

Cloning of leukemia inhibitory factor (LIF) and its expression in the uterus during embryonic diapause and implantation in the mink (Mustela vison).

Leukemia inhibitory factor (LIF) is essential for embryo implantation in mice. Whether LIF plays a role in termination of embryonic diapause and initiation of implantation in carnivores, especially in species with obligate delayed implantation such as the mink, is not known. The objectives of this study were to clone the LIF coding sequence in the mink and determine its mRNA abundance in the uterus through embryonic diapause, implantation, and early postimplantation. We show that the mink LIF cDNA contains 609 nt encoding a deduced protein of 203 amino acids. The homologies are 80.6, 90, 88.2, 87.6, and 86.8% in coding sequence and 79.2, 90.1, 91, 90.1 and 85.4% in amino acid sequence with mouse, human, pig, cow, and sheep respectively. Glycosylation sites and disulfide bonds present in other species are generally conserved in the mink LIF sequence. Quantitation by polymerase chain reaction amplification indicates that LIF mRNA is expressed in mink uterus just prior to implantation and during the first two days after implantation, but not during diapause or later after implantation pregnancy. The abundance of LIF mRNA was significantly higher in the uterus at the embryo expansion stage (P < 0.05) than at days 1-2 of postimplantation. By immunohistochemical localization it was shown that LIF is expressed in the uterine epithelial glands at time of embryonic expansion and in early postimplantation. The coincidence of LIF expression with implantation in this species suggests that LIF is involved in the implantation process, and may be a maternal signal which terminates obligate embryonic diapause.

Amino Acid Sequence↗
PubMed1998

Cine MR CSF flow study in hydrocephalus: what are the valuable parameters?

To evaluate the changes of intracranial cerebrospinal fluid (CSF) dynamics in hydrocephalus, we studied the various parameters of cine phase contrast (PC) magnetic resonance (MR) CSF flow images in cases of acutely progressive hydrocephalus, comparing them with those in normal CSF circulation. The MR images were obtained with 1.5 T unit using the 2 dimensional cine PC sequence with cardiac gating in 10 non-obstructive hydrocephalus (NOH), 3 obstructive hydrocephalus (OH), and 10 controls. The temporal velocity information from the anterior and posterior cervical pericord spaces, third and fourth ventricles, and aqueduct were plotted as wave form. The wave forms were analyzed for configurations, amplitude parameters (Smax, Smin, Sdif), and temporal parameters (R-S, R-SMV, R-D, R-DMV). The statistical significance of each parameter was examined with paired t-test. All patients with OH underwent endoscopic thrid ventriculostomy, whereas all NOH underwent shunting procedures. In 5 ROIs, distinct reproducible configuration features were obtained at aqueductal and cervical pericord spaces. Statistically significant differences between control and hydrocephalus only in temporal parameters were determined. In NOH, the graph showed R-DMV shortening (p < 0.01) at anterior cervical pericord space. In OH, there were R-DMV shortening (p < 0.05) at anterior cervical pericord space, R-SMV shortening (p < 0.02) at posterior cervical pericord space. Also the level of obstructions could be determined in all OHs. The analysis of MR CSF flow images may give us valuable information on the site of obstruction, explaining the cause of hydrocephalus, thus deciding the necessity of shunting procedures using in vivo images.

Adolescent↗
PubMed1998

Decreased mitochondrial DNA content in peripheral blood precedes the development of non-insulin-dependent diabetes mellitus.

Qualitative changes in mitochondrial DNA (mtDNA), such as mutations and deletions, have been implicated in the pathogenesis of diabetes mellitus. In addition to the qualitative changes, mtDNA is subject to quantitative changes, and is vulnerable to oxidative stress, resulting in both qualitative and quantitative changes. This study was performed to investigate whether quantitative changes in mtDNA occur in non-insulin-dependent diabetes mellitus (NIDDM) patients and also in pre-diabetic subjects. MtDNA content from peripheral blood was measured by slot-blot analysis in 55 NIDDM patients and 29 age- and sex-matched control subjects. We have also analysed the mtDNA copies by quantitative polymerase chain reaction (PCR) method in 23 pre-diabetic subjects who converted to diabetic in 2 years and 22 age- and sex-matched control subjects who remained non-diabetic. Mean mtDNA quantity measured by slot blot method was 35% lower in patients with NIDDM than in control subjects (12.3+/-8.1 vs. 19.1+/-8.2 AU/microg DNA; P < 0.05). MtDNA quantities did not correlate with age, body mass index, duration of diabetes or HbA1c levels. We have also found that the mtDNA copies in subjects who converted to diabetes in 2 years were lower than in controls even before the development of diabetes (102.8+/-41.5 vs. 137.8+/-67.7 copies/pg template DNA P < 0.05). Inverse correlations were noted between mtDNA content and baseline waist hip circumference ratio (WHR) (r = -0.31, P < 0.05), and fasting glucose level (r = - 0.35, P < 0.05), diastolic blood pressure (r = -0.36, P < 0.05), and WHR (r = -0.40, P < 0.01) after development of diabetes. In conclusion, we demonstrate that the content of mtDNA decreases in peripheral blood of patients with NIDDM and the lower mtDNA levels precede the development of diabetes.

Biomarkers↗
PubMed1998

Differentiation of the corpus luteum of the mink (Mustela vison): mitogenic and steroidogenic potential of luteal cells from embryonic diapause and postimplantation gestation.

The mink corpus luteum (CL) involutes after ovulation and remains dormant, synthesizing low amounts of progesterone until reactivated to terminate embryonic diapause. We examined the mitotic and steroid synthetic capacity of luteal cells from the diapause and postimplantation phases of mink gestation. Cells from diapause divided in vitro, reaching confluence in 7-8 days. Three phenotypes were distinguishable: a fusiform cell in whorls, a hypertrophied epithelioid cell, and a small epithelioid cell. The first and second cell types divided in vitro after confluence, evidenced by localization of proliferating cell nuclear antigen (PCNA) in their nuclei. The small epithelioid cells were present in cell nests and showed no PCNA activity. Cells derived from reactivated CL did not reach confluence and had no PCNA activity. Progesterone accumulation was enhanced in luteal cells from diapause by LH, FSH, and dibutyryl (Bu2)cAMP, and by LH and (Bu2)cAMP in cells from reactivated CL. In luteal cells from the diapause phase of gestation, LH and (Bu2)cAMP induced increases in mRNA coding for steroidogenic acute regulatory protein, while cytochrome P450 side-chain cleavage enzyme mRNA was increased by prolactin, LH and (Bu2)cAMP. Cellular concentrations of 3beta-hydroxysteroid dehydrogenase-delta5-4-isomerase mRNA were increased by prolactin and (Bu2)cAMP. Thus, luteinization in the mink CL does not engender exit from the cell cycle, as both fusiform and hypertrophied cells from diapause divide in vitro. Reactivation appears to represent terminal differentiation. LH is capable of stimulating steroidogenesis in vitro in luteal cells from diapause, and prolactin and LH appear to have both specific and overlapping stimulatory effects on the CL of this species.

Animals↗
PubMed1998

Luteotropic hormone receptors in the ovary of the mink (Mustela vison) during delayed implantation and early-postimplantation gestation.

The reproductive cycle of the mink displays rigid seasonality and obligate embryonic diapause. After ovulation, the corpus luteum (CL) involutes, and it secretes basal progesterone until activated prior to implantation. To study changes in the relative abundance of luteal prolactin and LH receptor mRNA through gestation, ovaries and serum were collected from pregnant female mink at 2-day intervals (n = 3 per date) through embryonic diapause and CL activation (March 19-31) and at 5-day intervals through implantation and early-postimplantation gestation (March 31-April 15). To determine the effect of endogenous prolactin, mink received Alzet osmotic minipumps releasing 2 mg/day 2-bromo-alpha-ergocryptine (bromocriptine) or saline on March 19. Ovaries and serum were taken from 3 animals every 2 days until March 31. Prolactin receptor mRNA in ovaries was low during CL activation but increased 3-fold through embryo implantation. Its abundance correlated with prolactin binding to ovarian membranes and with circulating prolactin. Bromocriptine suppressed endogenous prolactin levels and prevented the increase in prolactin receptor mRNA. There was a transient peak in LH receptor mRNA in the ovaries at March 19-23, which declined to basal levels by March 25 and remained constant through midgestation. Bromocriptine prevented the preimplantation peak in LH receptor mRNA and reduced its abundance below pretreatment levels. The results suggest that prolactin up-regulates its receptor and maintains the LH receptor in the mink CL. The pattern of LH receptor mRNA argues for a role for LH in CL reactivation and termination of embryonic diapause in mink.

Animals↗
PubMed1998

Cloning, developmental expression, and immunohistochemistry of cyclooxygenase 2 in the endometrium during embryo implantation and gestation in the mink (Mustela vison).

Cyclooxygenase (COX) is the first rate-limiting enzyme in the biosynthesis of PGs. There are two isoforms, COX-1, a constitutive enzyme and COX-2, the induced form, products of two different genes. In this study, we report COX-2 complementary DNA cloning, uterine expression, and immunohistochemical localization in the mink uterus during postimplantation gestation. The open reading frame of mink COX-2 contains 1812 nucleotides encoding 604 amino acids. The homologies are 86%, 83%, 83%, 83%, 85%, and 84% in nucleotides and 86%, 87%, 87%, 85%, 86%, and 88% in amino acids with human, mouse, rat, guinea pig, sheep, and rabbit, respectively. All domains associated with biological activity are conserved in the mink. Northern analysis revealed a transcript of 4.2 kb for COX-2 in mink uterus and adrenal. Semiquantitative RT-PCR showed that COX-2 messenger RNA is not present during diapause. The abundance of COX-2 messenger RNA reached its maxima (P < 0.05) on days 3-5 of postimplantation, gradually decreased through day 9, and was not present thereafter. By immunohistochemistry, COX-2 was present in uterine epithelium, stroma, and necks of endometrial glands at sites of implantation. COX-2 expression appears to be induced in the endometrium by the embryo and may play a role in implantation and placentation in the mink.

Amino Acid Sequence↗
PubMed1998

Surgical options of hypertensive intracerebral hematoma: stereotactic endoscopic removal versus stereotactic catheter drainage.

The authors analyzed the difference between two surgical procedures, stereotactic endoscopic removal (SER) and stereotactic catheter drainage (SCD), in 18 patients of ganglionic intracerebral hematoma (ICH). Ten patients underwent SCD and eight SER within 24 hours of insult. The mean age was 53.3 (33-81) years and male to female ratio was 11:7. The mean volume of hematoma was 34.4 (23-105) ml. All patients had major neurological deficits without signs of transtentorial herniation. Mean follow-up was 8 (6-10) months. Under local anesthesia, Otzuki's cannula was placed through a burr hole. ICH was removed with suction and forceps under endoscopic guidance. Hemostasis was performed with Nd-YAG laser. For SCD, we used silicone catheter and urokinase. The hematoma was drained in 3-5 days in SER, whereas 7-10 days in SCD. Postoperative rebleeding occurred in one case of SER. Mortality rate was 13% in SER, 10% in SCD. The patients who gained most from these treatments were those who had been admitted with an impaired level of consciousness. The whole procedure can be done under direct vision in SER, so SER might replace SCD with similar mortality.

Adult↗
PubMed1998

Emergence and spread of antimicrobial resistance of Streptococcus pneumoniae in Korea.

Pneumococcal resistance has become a global issue during the past three decades. One of the major foci of pneumococcal resistance worldwide is the Asian region including Korea, Japan, and Hong Kong. Korea had not been recognized as a focus of pneumococcal resistance until 1995, when serial reports documented the alarmingly high prevalence of penicillin resistance among clinical isolates. Serial reports on penicillin resistance among pneumococcal isolates in Korea ranged from 68% to 77% as of 1995. Multidrug resistance was also noted in 34% of Korean isolates. Penicillin-binding protein profile analysis, pulsed-field gel electrophoresis, ribotyping, and fingerprinting analysis of pbp genes showed that antibiotic-resistant pneumococci isolated in Korea were genetically related. Data documented the extensive spread of a resistant clone within Korea and between different countries. Besides the injudicious use of antimicrobial agents or the high prevalence of serotypes 23 and 19, the spread of a resistant clone may play an important role in the rapid increase of penicillin resistance in Korea.

Asia↗
PubMed1998

Modulation of the neuronal nicotinic acetylcholine receptor-channel by the nitromethylene heterocycle imidacloprid.

Nitromethylene heterocycle insecticides are known to act on the nicotinic acetylcholine receptor-channel. The effects of the nitromethylene heterocycle, imidacloprid, on the nicotinic acetylcholine receptor-channel of clonal rat phaeochromocytoma (PC12) cells were studied using whole-cell and single-channel patch clamp methods. Imidacloprid suppressed carbachol-induced whole-cell currents in a dose-dependent manner, and this compound itself generated small currents. Multiple conductance states of single-channel currents were also evoked by imidacloprid at the nicotinic acetylcholine receptor-channels. The most frequently generated single-channel currents showed two conductance states, 25.4 and 9.8 pS, which were identical to the conductance states of acetylcholine-generated currents. The mean open time and burst duration of the main conductance currents induced by imidacloprid were shorter than those induced by acetylcholine. Co-application of imidacloprid and acetylcholine caused some interactions at the two conductance states. Mean open time and mean burst duration of the main conductance state currents evoked by acetylcholine were decreased by the co-application of imidacloprid as compared with those induced by acetylcholine alone. In conclusion, imidacloprid has both multiple agonist and antagonist effects on the neuronal nicotinic acetylcholine receptor-channels.

Acetylcholine↗
PubMed1997

Direct actions of anticholinesterases on the neuronal nicotinic acetylcholine receptor channels.

Recent studies have suggested that anticholinesterases including organophosphates and carbamates act directly on the nicotinic acetylcholine receptor (AChR) channel. We performed whole-cell and single-channel patch-clamp experiments to elucidate the mechanism of action of anticholinesterases on the nicotinic AChR in rat clonal phaeochromocytoma (PC12) cells. Neostigmine and carbaryl showed a biphasic effect; enhancement and suppression of carbachol-induced whole-cell currents. The currents induced by 100 microM carbachol was enhanced by the first co-application with 10 or 100 microM neostigmine, and the current was eventually suppressed below the control level during repeated co-applications. The decay phase of current was accelerated by neostigmine. Carbaryl at 0.1 microM greatly potentiated the carbachol-induced current, and at higher concentrations (0.3-3 microM), current was suppressed. In single-channel experiments, these compounds increased the short closures or gaps during channel opening without changing the single-channel conductance. Mean open time and burst duration were decreased in the presence of neostigmine and carbaryl. These results indicate that neostigmine and carbaryl directly block the nicotinic AChR channel.

Acetylcholine↗
PubMed1997

Neurons of the rostral para-ambiguual field have activity correlated to the 10-Hz rhythm in sympathetic nerve discharge of urethane-anesthetized cat.

Using the techniques of time domain correlation (mid-signal spike-triggered averaging) and frequency domain correlation (neuron-to-nerve coherence), 24% (54) of a sample of 229 neurons of the rostral para-ambiguual field have shown to have activity correlated to the 8- to 13-Hz rhythm in the inferior cardiac sympathetic nerve discharge (SND) of urethane-anesthetized cat. This correlation existed in both baroreceptor-innervated and -denervated animals. Of the correlated neurons, 37% (20) were non-rhythmically firing and displayed flat autospectra, while 63% (34) fired rhythmically and contained well-defined peaks in their autospectra. The group firing rate of these neurons was 4.3 +/- 0.4 spikes/s, indicating that they are not pacemaker neurons for the 10-Hz SND rhythm. The group time of firing of these neurons to the next peak of the SND slow wave was 52 +/- 4 ms. Correlation of the activity of medullary neurons with the 8-13-Hz rhythm of the SND was previously claimed only for rostral ventrolateral medulla, caudal raphe, and rostral caudal ventrolateral medulla. This present finding suggests that this behavior may be more widely spread throughout the medulla.

Anesthetics, Intravenous↗
PubMed1997

G-proteins are involved in riluzole inhibition of high voltage-activated calcium channels in rat dorsal root ganglion neurons.

Effects of riluzole on high voltage-activated (HVA) calcium channels of rat dorsal root ganglion neurons were studied using the whole-cell patch-clamp technique. Riluzole at 30 microM inhibited the HVA currents. The onset and offset of riluzole inhibitory effect were slow usually taking more than 3 min. Riluzole inhibition of the HVA currents was abolished and partially reduced by addition of 500 microM GDP-beta-S and 1 mM N-ethylmaleimide, respectively, to the pipette solution. Pre-treatment with pertussis toxin or application of depolarizing pre-pulses did not affect riluzole's inhibitory effect on the HVA currents. Riluzole inhibition of the HVA currents was also blocked by internal application of 50 microg/ml protein kinase A inhibitory peptide. It was concluded that pertussis toxin-insensitive G-proteins and protein kinase A may be involved in riluzole inhibition of the HVA currents.

Animals↗
PubMed1997

Lead modulation of the neuronal nicotinic acetylcholine receptor in PC12 cells.

Lead is known to modulate several ligand- and voltage-gated ion channels, including the nicotinic acetylcholine receptor (AChR) channel. We examined the effects of lead on the nicotinic AChR in rat clonal phaeochromocytoma PC12 cells using whole-cell and single-channel patch-clamp techniques to clarify the detailed mechanism of action. Lead suppressed acetylcholine-induced currents in a dose-dependent manner with an EC50 value of 37 microM and a Hill coefficient of 0.82. At the single-channel level, 1-10 microM lead shortened the opening and burst durations, and increased the duration of mean closed time. The open probability was significantly decreased by lead. These changes of single-channel kinetics result in a significant decrease in the total charge carried through the open AChR channels explaining the suppressive effect of lead on acetylcholine-induced whole-cell currents.

Acetylcholine↗