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Biomedical subjects

S M Han

Publications and source records attributed to S M Han.

At least 19 recordsLinked to original sources
PubMed2006

Changes in magnesium concentration in the serum and cerebrospinal fluid of neuropathic rats.

BACKGROUND: Central sensitization of neuropathic pain is associated with an influx of extracellular calcium via the opening of N-methyl-D-aspartate (NMDA) receptor-gated ion channels, which are usually blocked by magnesium plugs. As magnesium-deficient rats develop a mechanical hyperalgesia and intrathecal or intraperitoneal magnesium suppresses neuropathic pain, the magnesium concentrations in serum and cerebrospinal fluid may be altered in neuropathic pain. We therefore compared the magnesium concentrations in serum and cerebrospinal fluid of neuropathic rats with those in injured rats without symptoms of neuropathic pain and normal rats. METHODS: Mechanical allodynia was induced in male Sprague-Dawley rats by tight ligature of the left lumbar fifth and sixth spinal nerves. The threshold of paw withdrawal was evaluated by the up-down method using withdrawal response to stimulus with a von Frey filament on the third, seventh and 14th days. Rats with a threshold of less than 4 g were selected as the symptomatic group and compared with an asymptomatic group, an unoperated control group and a sham-operated group. On the 16th day, the Mg2+ concentrations in serum and cerebrospinal fluid were measured. RESULTS: The magnesium concentrations in the serum and cerebrospinal fluid of symptomatic neuropathic rats did not differ from those in the injured rats without symptoms of neuropathic pain, sham-operated rats and normal rats. CONCLUSION: Our results suggest that physiologic homeostasis is maintained by active transport through the blood-brain barrier despite the activation of NMDA receptor-gated ion channels. However, rats with neuropathic pain may be in a magnesium-deficient condition at the effector site, such that magnesium treatment can decrease neuropathic pain.

Animals↗
PubMed2005

A comparison of ultrasonic and X-ray methods for imaging the growth plate.

The purpose of this study was to assess a systematic and scientific method for measuring children's growth development, in which the accuracy of the existing diagnostic method has not yet been concretely examined. The most popular method for diagnosis of children's growth is to analyse the opening degree of the growth plate in each joint by an X-ray image. However, the X-ray method has some disadvantages; it is impossible to measure the diagnosis of growth periodically and repeatedly due to the radiation problem. Hence, this study introduced a profile analysis and the algorithm of analysing the image of the growth plate using the broadband ultrasound attenuation (BUA) of calcaneus, to verify the possibility of using an alternative ultrasonic method harmless to the human body. The images of the growth plate in the proximal tibiae, phalanges, and calcanei of 269 children (7-16 years old) were obtained using X-ray. The image of the growth plate in the calcanei was also obtained from these children using ultrasound. The results showed that the time of the opening degree of the growth plate in each joint was almost consistent between X-ray and ultrasonic images. Also, the images of the growth plate measured using X-ray and ultrasound showed a high correlation. Therefore, it is expected that the algorithm of ultrasonic profile analysis introduced in this study can replace the existing X-ray method to measure the growth plate correctly.

Adolescent↗
PubMed2001

Formation of alkanethiol monolayer on Ge(111).

Alkanethiols, CH3(CH2)(n-1)SH, are shown to react readily with HF-treated Ge(111) surface at room temperature to form a high-quality monolayer. The resulting films are characterized by using contact angle analysis (CAA), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), and high-resolution electron energy loss spectroscopy (HREELS). The octanethiol and octadecanethiol films on Ge(111) both exhibit 101 degrees and 40 degrees water and hexadecane contact angles, respectively. These values indicate that the thiol surface coverage is relatively high, and that the films possess a high degree of orientational ordering. The angle-resolved XPS analysis supports that thiols are bound to the Ge surface by Ge-S bonds at the monolayer/Ge interface. The film thickness values obtained by XPS and SE agree well with the earlier reported values on alkyl monolayers on Ge(111) prepared by Grignard reaction. On the basis of HREEL spectra taken after thermal annealing steps, the monolayers are found to be thermally stable up to 450 K. The thermal stability provides further evidence that thiols are covalently bonded to Ge(111).

Journal Article↗
PubMed2001

The interaction between intrathecal neostigmine and GABA receptor agonists in rats with nerve ligation Injury.

UNLABELLED: Nerve ligation injury may produce a pain syndrome that includes tactile allodynia. Reversal effects on tactile allodynia have been demonstrated after the intrathecal administration of gamma-aminobutyric acid (GABA) receptor agonists or cholinesterase inhibitors in rats. We examined the drug interactions between neostigmine and muscimol or baclofen in a rat model of nerve ligation injury. Rats were prepared with tight ligation of the left L5-6 spinal nerves and chronic intrathecal catheter implantation. Tactile allodynia was measured by applying von Frey filaments ipsilateral to the lesioned hindpaw. Thresholds for paw withdrawal were assessed. Neostigmine (0.3-10 microg), muscimol (0.1-10 microg), and baclofen (0.1-3.0 microg) were administered to obtain the dose-response curve and the 50% effective dose (ED(50)). Fractions of ED(50) values were administered intrathecally to establish the ED(50)s of drug combinations (neostigmine-muscimol and neostigmine-baclofen). The drug interactions were performed. Intrathecal neostigmine, muscimol, baclofen, and their combinations produced a dose-dependent increase in withdrawal threshold of the lesioned hindpaw. Both analyses revealed a synergistic interaction for the neostigmine-muscimol combination, whereas the effect of the neostigmine-baclofen combination was additive. These results suggest that the activation of both muscarinic and GABA(A) receptors is required for synergistic interaction. IMPLICATIONS: This study indicates that drug interaction is synergistic for the neostigmine-muscimol combination, whereas the effect of the neostigmine-baclofen combination is additive. In a rat model of nerve ligation injury, neostigmine, muscimol, baclofen, and their combinations provide an antagonism on touch-evoked allodynia at the spinal level.

Animals↗
PubMed2001

Disc hydration measured by magnetic resonance imaging in relation to its compressive stiffness in rat models.

The in vivo effects of body dehydration on the water content and compressive stiffness of rat intervertebral disc (IVD) and vertebral body were investigated. Thirty-one rats were divided into three dietary groups: water restricted ( WR), pair fed (PF) and ad libitum (AL). The in vivo water content of L4-5 IVD was measured using magnetic resonance imaging (MRI). Water contents of L4-5 IVD were also determined using the wet/dry weight method after killing. Compressive stiffness of the L5 vertebral body and the L3-4 motion segment were determined. Results showed that the water content of L4-5 IVD was significantly less in the WR group than in the PF and AL groups as measured by the wet/dry weight method; likewise, MRI water content was also less in the WR group. The material stiffness of the IVD was significantly greater in the WR than in the PF and AL groups. However, there was no significant difference in material stiffness of the L5 vertebral body for the WR group in comparison with the PF and AL groups. It was also found that the stiffness of the IVD was significantly lower than that of the vertebral body. This study suggests that the dehydrated matrix of the IVD may be responsible for a stiffer disc that may lead to a less flexible spine.

Animals↗
PubMed2000

Truncated form of importin alpha identified in breast cancer cell inhibits nuclear import of p53.

Disruption of the function of tumor suppressor proteins occasionally can be dependent on their subcellular localization. In about 40% of the breast cancer tissues, p53 is found in the cytoplasm as opposed to the nucleus, where it resides in normal breast cells. This means that the regulation of subcellular location of p53 is an important mechanism in controlling its function. The transport factors required for the nuclear export of p53 and the mechanisms of their nuclear export have been extensively characterized. However, little is known about the mechanism of nuclear import of p53. p53 contains putative nuclear localization signals (NLSs) which would interact with a nuclear transport factor, importin alpha. In this report we demonstrate that importin alpha binds to NLSI in p53 and mediates the nuclear import of p53. Reverse transcriptase-polymerase chain reaction and sequencing analyses showed that a truncated importin alpha deleted the region encoding the putative NLS-binding domain of p53, suggesting that it could not bind to NLSs of p53 proteins. Binding of importin alpha to p53 was confirmed by using yeast two-hybrid assay. When expressed in CHO-K1 cells, the truncated importin alpha predominantly localized to the cytoplasm. In truncated importin alpha expressing cells, p53 preferentially localized to cytoplasmic sites as well. A significant increase in the p21(waf1/cip1) mRNA level and induction of apoptosis were also observed in importin alpha overexpressing cells. These results strongly suggest that importin alpha functions as a component of the NLS receptor for p53 and mediates nuclear import of p53.

Amino Acid Sequence↗
PubMed2000

An analysis of drug interaction between morphine and neostigmine in rats with nerve-ligation injury.

UNLABELLED: Intrathecal neostigmine reverses mechanical allodynia in humans and animals. The efficacy of morphine in a neuropathic pain state is still controversial. This study examines the antiallodynic interaction between morphine and neostigmine in a rat model of neuropathic pain. Rats were prepared with tight ligation of left L5-6 (fifth and sixth lumbar) spinal nerves and chronic intrathecal catheter implantation. Mechanical allodynia was measured by using application of von Frey hairs to the left hindpaw. Morphine (1, 3, 10, and 30 microg) and neostigmine (0.3, 1, 3, and 10 microg) were administered intrathecally to obtain the dose-response curves and the 50% effective dose (ED(50)) for each drug. ED(50) values and fractions of the ED(50) values (1/2, 1/4, and 1/8) were administered intrathecally in an equal dose ratio to establish the ED(50). Isobolographic and fractional analyses for the drug interaction were performed. Intrathecal morphine produced a moderate antagonism of the tactile allodynia. A morphine-neostigmine combination produced a dose-dependent increase in withdrawal threshold of the lesioned hind paw with reduced side effects. Both analyses revealed a synergistic interaction after the coadministration of morphine and neostigmine. These experiments suggest that the antiallodynic action of a morphine-neostigmine combination is synergistic at the spinal level. IMPLICATIONS: This study indicates that, by using both isobolographic and fractional analyses, the antiallodynic effect of intrathecal morphine and neostigmine is synergistic when coadministered intrathecally. In a rat model of neuropathic pain, the intrathecal morphine produced a moderate antagonism on touch-evoked allodynia at the spinal level.

Analgesics, Opioid↗
PubMed2000

Comparison of wiring techniques for bone fracture fixation in total hip arthroplasty.

The objective of this study was to investigate the effect of cerclage wire position and determine the number of wires necessary to prevent crack opening and stem subsidence following a proximal femoral fracture in cementless total hip arthroplasty. A cementless femoral stem one size larger than the templated size was inserted into each femur to initiate a proximal crack. A cerclage wire was wrapped around the fracture in one of two orientations: 1) parallel to the osteotomy (PO) and 2) normal to the fracture line (NF). The femur was compressed to a load of 890 N, 1780 N and 2670 N while crack opening and stem subsidence were measured. A second cerclage wire was placed parallel to NF wire and inferior to the lesser trochanter and a third wire was placed 1 cm distal and parallel to the second wire. The loading was repeated again. The mechanical evaluation of stem subsidence were verified by various computer simulations even using four wires. We have found that placement of the cerclage wires normal to the fracture line prevents stem subsidence and crack opening better than placement of the wires parallel to the osteotomy. Three cerclage wires, placed normal to the fracture line at three locations: 1) adjacent to the superior of the lesser trochanter, 2) adjacent to the inferior of the lesser trochanter and 3) 10 mm distal to the bottom of the lesser trochanter were necessary to achieve stability under higher loads.

Arthroplasty, Replacement, Hip↗
PubMed1999

Transfer from manual to automated sample preparation: a case study.

A manual sample preparation for a controlled release capsule formulation has been converted to an automated sample preparation. Each step of the manual sample preparation was evaluated as to its feasibility for automation in terms of precision, carryover, filter selection and other critical issues. Although most steps of the manual method were easily translated to the automated procedure, certain 'simple' details such as filter selection, sample storage, and the conversion from volumetric to gravimetric measurements needed closer investigation.

Automation↗
PubMed1999

Cerclage wiring technique after proximal femoral fracture in total hip arthroplasty.

Cerclage wires have been used to stabilize proximal femoral cracks after stem insertion in cementless total hip arthroplasty. The objective of this study was to determine the optimal number and orientation of cerclage wires necessary to prevent stem subsidence and crack propagation. The crack was stabilized by 1, 2, or 3 wires placed either normal to the femoral neck axis or normal to the crack. The femora were compressed to 2,670 N while measuring crack opening and stem subsidence. Wires placed normal to the crack allowed less stem subsidence by 3.17 mm and less crack opening by 1.55 mm compared with wires placed normal to the neck. The addition of multiple wires reduced subsidence by 50% and reduced crack opening to <1 mm. Medial and anterior calcar cracks are best stabilized by at least 2 cerclage wires that are placed normal to the crack.

Arthroplasty, Replacement, Hip↗
PubMed1999

Ultrasound velocity and attenuation in relation to maximum trabecula stress in the patella.

The ultrasound velocity and attenuation were examined in 16 sets of human patellae. The average ultrasound velocity of patella was shown to be greater in the superior/inferior direction than in the anterior/posterior and medial/lateral directions. The distribution of bone mineral density (BMD) was also examined. The BMD of the patella varied with location. BMD values were largest at the superior and lateral regions and decreased inferiorly and medially. A two-dimensional finite element analysis was performed on each patella. The maximum von Mises stress occurred along the cortical shell on the non-articular surface. The trabecular von Mises stress existed in the posterior region of the patella. Correlation study showed that patellar BMD was significantly associated with each of three directional ultrasound velocities. The relationship between BMD and ultrasound attenuation was not significant. It was also found that the ultrasound velocity and attenuation were not significantly correlated with the maximum von Mises stress.

Aged↗
PubMed1999

Management of difficult airways with a laryngeal mask airway under propofol anaesthesia.

We report four cases of difficult airway managed with a laryngeal mask airway (LMA) under propofol anaesthesia; this method was chosen to minimize psychological and physical trauma. Case 1 was a boy with dermatomyositis; Case 2, a girl wearing a base ring of a stereotactic frame; Case 3, a boy with Treacher-Collins syndrome; Case 4, a boy with Goldenhar syndrome. They were anaesthesized with propofol and though spontaneous ventilation became shallower, or apnoea occurred, the stimulus of inserting an LMA awakened the patient and caused more active spontaneous ventilation while a patent airway was established by the LMA. All tracheal intubations were performed smoothly and without delay through the LMA, and we believe that psychological and physical trauma was thus minimized.

Anesthesia↗
PubMed1999

The antiallodynic effects of intrathecal cholinesterase inhibitors in a rat model of neuropathic pain.

BACKGROUND: This study determined the effect of intrathecally administered cholinesterase inhibitors, edrophonium and neostigmine, on nerve injury-induced, touch-evoked allodynia and identified the pharmacologic characteristics of this action. METHODS: Rats were prepared with tight ligation of the left L5 and L6 spinal nerves and with lumbar intrathecal catheters fitted for long-term monitoring. Edrophonium (3, 10, 30, or 100 microg) or neostigmine (0.3, 1, 3, or 10 microg) was administered intrathecally. Tactile allodynia and motor weakness were assessed. To evaluate the pharmacologic characteristics of the activity, a muscarinic receptor antagonist or a nicotinic receptor antagonist was administered intrathecally before edrophonium or neostigmine was injected. To compare the action of subtype antagonists, the M1 muscarinic receptor antagonist pirenzepine, the M2 antagonist methoctramine, the M3 antagonist 4-DAMP (diphenylacetoxy-N-methypiperidine), and the M4 antagonist tropicamide were administered intrathecally before cholinesterase inhibitors were injected. RESULTS: Intrathecal edrophonium or neostigmine produced a dose-dependent antagonism of the touch-evoked allodynia. Neostigmine resulted in a moderate effect on motor weakness at doses of 3 and 10 microg. Pretreatment with intrathecal atropine but not mecamylamine yielded a complete antagonism of the effects of the cholinesterase inhibitors. In addition, antiallodynia produced by edrophonium (100 microg) was reversed by pretreatment with methoctramine, 4-DAMP, tropicamide, and pirenzepine. In the neostigmine (10 microg) group, only the M1 antagonist pirenzepine had a moderate effect on reversal of increased allodynic threshold. CONCLUSIONS: These experiments suggest that intrathecal edrophonium or neostigmine produces an antagonism on touch-evoked allodynia at the spinal level in a rat model of neuropathic pain and that the antiallodynic action of cholinesterase inhibitors is probably mediated by a spinal muscarinic system, especially at the M1 receptor subtype.

Animals↗
PubMed1998

Increased glyceraldehyde-3-phosphate dehydrogenase gene expression in human cervical cancers.

OBJECTIVE: Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a classical glycolytic protein. A higher level of GAPDH mRNA was found in lung, pancreas, and prostate cancers, but in cervical carcinoma there have not been any reports about the level of GAPDH gene expression. So, we tried to investigate the GAPDH gene expression patterns in cervical carcinomas compared to normal cervical tissues, and the relationships between the expression levels of this gene and conventional clinicopathological parameters were evaluated. MATERIALS AND METHODS: In this study, 25 normal exocervical tissues, 35 primary untreated cervical cancer tissues, 2 cervical cancer cell lines, and 2 post-nude-mouse-derived cervical cancer cell lines were subjected to Northern blot analyses for GAPDH gene expression. RESULTS: Northern blot analyses revealed that the levels of GAPDH gene expression were elevated in 34 of 35 (97%) cervical carcinoma tissues and all of the 4 cervical cancer cell lines compared to normal cervical tissues. The levels of GAPDH gene expression were more prominent in rapidly proliferating cervical carcinoma cells. The levels of the GAPDH gene expressions in cervical cancer tissues were not associated with conventional clinicopathological parameters including clinical stage, histological type, and degree of differentiation. CONCLUSION: These results suggest that increased GAPDH gene expression is characteristic of human cervical carcinomas and that rapidly proliferating carcinoma cells express more enhanced GAPDH gene. Future gene therapy using antisense oligodeoxynucleotide directed against GAPDH mRNA might be another therapeutic tool for human uterine cervical carcinoma.

Female↗
PubMed1998

Dependence of broadband ultrasound attenuation on the elastic anisotropy of trabecular bone.

The effect of trabecular elastic anisotropy on broadband ultrasound attenuation (BUA) and bone mineral density (BMD) was investigated with human and bovine cubic cancellous bones. Ultrasonic parameters describing trabecular anisotropy were found from the three orthogonal ultrasound velocities. BMD was measured using quantitative computed tomography. Three elastic anisotropy ratios were compared to BUA in all three directions and to BMD. The combined effect of anisotropic characteristics and BMD was also correlated with BUA. The results showed that the anisotropy ratios were significantly related to BUA (p < 0.05). There was, however, no correlation between BMD and the elastic anisotropy ratios. The combination of BMD and the anisotropy produced a significantly enhanced relationship with BUA.

Aged↗