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Biomedical subjects

S W Kim

Publications and source records attributed to S W Kim.

At least 19 recordsLinked to original sources
PubMed1992

Neuropsychological performance in obsessive-compulsive disorder.

Neuropsychological functioning was examined in a group of 18 nondepressed patients with obsessive-compulsive disorder (OCD) and 18 age-, education-, and gender-matched normal controls. A recent nonverbal memory deficit was identified in the patients with OCD. From performance on timed and untimed measures of the same constructs, it appears that OCD patients score more poorly than controls when speed is a factor. Although performance on a timed tactual-spatial motor test was also impaired, it is unclear whether this deficit is attributable to the nonverbal memory and/or speed deficits. Deficits in verbal abilities, including recent verbal memory, were not identified. Results were equivocal for executive function and visual-spatial abilities. The previously established association of recent nonverbal memory abilities with functioning of the right mesial temporal area is discussed in the context of current hypotheses about the neuroanatomic substrate of OCD.

Adult↗
PubMed1992

Blood compatibility of SPUU-PEO-heparin graft copolymers.

Biological responses to heparinized segmented polyurethaneurea (SPUU-PEO-Heparin) were evaluated in vitro and ex vivo. In vitro assays involved plasma protein adsorption, platelet adhesion, and release reaction studies. In addition, an ex vivo rabbit arterio-artery (A-A) shunt experiment was also performed to measure occlusion times of the heparinized surfaces. All SPUU-PEO-Heparin surfaces demonstrated less protein adsorption than Biomer and protein adsorption patterns similar to SPUU-PEO surfaces. Platelet adhesion and release studies demonstrated that both SPUU-PEO-Heparin and SPUU-PEO surfaces adsorbed less platelets and inhibited platelet release, as compared to Biomer. These findings correlated with reduction in protein adsorption observed for the modified surfaces. In low flow rate ex-vivo A-A shunt experiments, all heparinized surfaces prolonged occlusion time longer than controls. However, SPUU-PEO surfaces did not prolong occlusion time when compared to Biomer, although these surfaces suppressed protein adsorption and platelet interaction in vitro. The improved blood compatibility of SPUU-PEO-Heparin surfaces attest to the usefulness of this approach in improving the blood compatibility of blood contacting surfaces.

Adsorption↗
PubMed1992

Concanavalin A microspheres for a self-regulating insulin delivery system.

A self-regulating insulin delivery system based on the competitive binding of glucose and p-succinylamidophenyl-alpha-D-glycopyranoside-insulin (SAPG-insulin) to crosslinked concanavalin A (Con A) microspheres (MSs) has been investigated. Con A MSs prepared by a water-in-oil emulsion technique demonstrated properties of binding to glucose and SAPG-insulin (binding constants of 1.25 x 10(3) and 1.28 x 10(4) M-1, respectively) that are similar to the literature values of these properties for unmodified Con A. The retained binding capacity (number of binding sites per molecule) of Con A MSs, produced with 20% of the epsilon-amino groups crosslinked, was approximately 28% that of intact Con A. As a new device, Con A MSs loaded with SAPG-insulin was enclosed in a heat-sealed, surface-modified, porous poly(vinylidene difluoride) membrane pouch. This system showed a pulsatile release pattern for insulin with a short lag time in response to glucose challenges of 50-500 mg/dL. The pattern of release of SAPG-insulin from the devices was studied with varying design parameters, such as surface area, membrane pore size, and loading content of SAPG-insulin.

Binding, Competitive↗
PubMed1992

The Symptom Checklist-90: Obsessive-Compulsive Subscale: A reliability and validity study.

Twenty-three nondepressed patients with DSM-III obsessive-compulsive disorder completed the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), the Symptom Checklist-90 (SCL-90), and the National Institute of Mental Health Global Obsessive-Compulsive Scale (NIMH-GOCS) once a week for a total of three times during a 2-week medication-free period and 10 times during a 10-week double-blind drug treatment period. The pretreatment test-retest reliabilities were determined for the Y-BOCS, NIMH-GOCS, and the SCL-90-Obsessive-Compulsive Subscale (SCL-90-OCS). Comparisons of the three instruments revealed that the Y-BOCS and the NIMH-GOCS were significantly more reliable than the SCL-90-OCS. Posttreatment correlations were obtained between change scores on the Y-BOCS and NIMH-GOCS and the SCL-90-OCS. Correlations were high and statistically significant for both the Y-BOCS and the NIMH-GOCS, but the correlations of the SCL-90-OCS with the Y-BOCS, NIMH-GOCS, Physician's Global Rating, and the Patient's Global Rating were poor. The findings suggest that the SCL-90-OCS may not be a sensitive instrument in assessing change in obsessive-compulsive symptoms.

Adult↗
PubMed1992

Hydrogels: swelling, drug loading, and release.

Hydrogels have been used by many investigators in controlled-release drug delivery systems because of their good tissue compatibility and easy manipulation of swelling level and, thereby, solute permeability. The desired kinetics, duration, and rate of solute release from hydrogels are limited to specific conditions, such as hydrogel properties, amount of incorporated drug, drug solubility, and drug-polymer interactions. This review summarizes the compositional and structural effects of polymers on swelling, loading, and release and approaches to characterize solute release behavior in a dynamic state. A new approach is introduced to compensate drug effects (solubility and loading) with the release kinetics by varying the structure of heterogeneous polymers. Modulated or pulsatile drug delivery using functional hydrogels is a recent trend in hydrogel drug delivery.

Drug Carriers↗
PubMed1992

Computerized quantitative radionuclide assessment of heterotopic ossification in spinal cord injury patients.

We evaluated the progression of heterotopic ossification (HO) in 17 spinal cord injury patients by comparing radiographs, quantitative radionuclide bone scans, and serum alkaline phosphatase levels. Evidence of maturation of HO appeared earlier (3 months to 6 years post injury) in radiographs, whereas, during the same time frame, radioactive nuclide assessment showed continued progression of HO in 10 out of the 17 patients. The evolution of HO appeared to take place over a period ranging between 3 and 80 months. We believe that stabilization of HO may be reasonably defined in terms of uptake ratios of 2.0 or less in patients with initial uptake ratios over 3.0 but below 5.0, and of ratios of 3.0 or less when the initial values are over 5.0.

Adult↗
PubMed1992

Functional analysis of the rat insulin-like growth factor I gene and identification of an IGF-I gene promoter.

Insulin-like growth factor I (IGF-I) mediates many of the systemic growth-promoting effects of growth hormone and also functions as a locally acting growth stimulator. In mammals, IGF-I gene expression is complicated, as the gene is transcribed and processed into multiple mRNAs (ranging in length from less than 1 to nearly 7.5 kb) that encode at least two protein precursors. As a step toward understanding the regulation of IGF-I, we report the complete organization of the rat IGF-I gene, including identification of the structural determinants for all IGF-I mRNA species, and an initial functional analysis of its promoters. The gene is composed of 6 exons distributed over nearly 80 kb of chromosomal DNA and is structurally heterogeneous. Several transcription start sites were identified within IGF-I exons 1 and 2, adjacent to presumptive promoters 1 and 2, respectively, and at least three polyadenylation sites were mapped to exon 6. To test promoter function, fusion genes were constructed linking fragments of IGF-I DNA to a reporter plasmid. Chimeric genes containing at least 395 bp of DNA from the 5'-flanking region of exon 1 enhanced luciferase activity after transfection into the IGF-I-producing SK-N-MC cell line, while fusion plasmids containing up to 1,300 bp of DNA from the 5'-flanking region of exon 2 were inactive. Relative levels of IGF-I mRNAs containing exons 1 or 2 varied among different rat tissues, although in response to acute or chronic growth hormone treatment both classes of transcripts were induced coordinately in rat liver. These observations represent the first thorough characterization of a mammalian IGF-I gene, and provide a starting point for defining the mechanisms by which growth hormone and other trophic factors regulate IGF-I gene expression.

Amino Acid Sequence↗
PubMed1992

Prominent eye movements during NREM sleep and REM sleep behavior disorder associated with fluoxetine treatment of depression and obsessive-compulsive disorder.

The clinical polysomnographic (PSG) reports of 2,650 consecutive adults studied during 41 months were reviewed retrospectively to identify all patients treated with fluoxetine or tricyclic antidepressants. The PSG reports of four other adult groups were also reviewed: periodic limb movement (PLM) disorder (n = 28); sleep terror/sleepwalking (ST/SW) (n = 54); rapid eye movement (REM) sleep behavior disorder (RBD) (n = 70); patients with clinically unremarkable sleep during two consecutive PSG studies (n = 30). Standard PSG recording and scoring methods were employed. A total of 1.5% (n = 41) and 2.0% (n = 52) of patients were receiving fluoxetine or tricyclics (amitriptyline or nortriptyline, n = 31; imipramine or desipramine, n = 16; protriptyline or trimipramine, n = 5). A selective association between fluoxetine and extensive, prominent eye movements in nonrapid eye movement (NREM) sleep was detected, utilizing Fisher's exact one-tailed statistic (p less than 0.00001 for each comparison). The detection rates were fluoxetine, 48.8% (20/41); tricyclics, 5.8% (3/52); RBD, 4.3% (3/70); objectively normal sleepers, 3.3% (1/30); PLM, ST/SW, 0% (0/82). These groups had similar mean ages (31.5-45.4 years) and gender distributions (50.0-60.7% male), apart from RBD. The effect of fluoxetine, a potent and specific serotonin reuptake inhibitor, on NREM eye movements is postulated to derive from potentiation of serotonergic neurons that inhibit brainstem "omnipause neurons", which, in turn, inhibit saccadic eye movements, thus resulting in disinhibited release of saccades. In addition, a 31-year-old man with obsessive-compulsive disorder developed RBD soon after starting fluoxetine therapy, which persisted at PSG study 19 months after fluoxetine discontinuation.

Adult↗
PubMed1992

Surface characterization of 2-hydroxyethyl methacrylate/styrene copolymers by angle-dependent X-ray photoelectron spectroscopy and static secondary ion mass spectrometry.

The surface composition and structure of three structurally distinct amphiphilic copolymers of 2-hydroxyethyl methacrylate (HEMA) and styrene have been examined with angle-dependent X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS). The phase-separated block copolymer made by anionic living polymerization, HSH-A50, showed significant surface enrichment of styrene. The outermost 2-3 A appeared to be approximately 100% styrene, with the styrene concentration decreasing to its bulk value at a depth of approximately 50 A from the surface. However, HEMA was detected in the outer 20 A of this copolymer. The presence of HEMA in the surface region implies this copolymer may undergo significant restructuring when hydrated in a hydrophilic environment (as opposed to the hydrophobic environment in which the sample was prepared and analyzed). The phase-separated block copolymer made by telechelic coupling of free radical polymerized functionalized oligomers, HSH-B60, showed only slight styrene enrichment at the surface. Both HEMA and styrene were detected at all sampling depths, including the outermost surface layer, consistent with the presence of discrete HEMA and styrene domains at the copolymer surface. Since both components are already present at the surface under hydrophobic conditions, the degree of restructuring this copolymer may undergo upon hydration should be minor. The random HEMA--styrene copolymer made by conventional free radical initiation techniques, HS-RAN50, had a surface composition that was similar to the bulk composition and independent of depth, as expected for a homogeneously mixed copolymer film.

Biocompatible Materials↗
PubMed1992

pH-inducible beta-glucosidase and beta-glucuronidase of intestinal bacteria.

beta-Glucosidase and beta-glucuronidase of human and rat fecal bacteria were induced by cultivation in alkaline media although their growths were not affected. When a bacterium isolated from human feces producing each enzyme was cultured in a medium at pH 5 for 12-15 h and then adjusted to pH 8, beta-glucosidase and beta-glucuronidase were induced 9.2-fold and 11.5-fold, respectively.

Animals↗
PubMed1992

The efficacy of Doppler umbilical artery velocimetry in identifying fetal acidosis. A comparison with fetal biophysical profile.

In 105 singleton pregnancies in which cesarean section was performed before the onset of labor, the efficacy of Doppler umbilical velocimetry in identifying fetal acidosis was determined and compared with fetal biophysical profile. Doppler velocimetry showed a significant correlation with the umbilical artery pH and was also a sensitive indicator of fetal acidosis, comparable to the biophysical profile score. Patients were classified into four groups. Groups with abnormal Doppler results showed a significantly higher prevalence of fetal acidosis, and all the fetuses with abnormal Doppler results were either in acidosis or in a growth-retarded state. Our data lend further support to the clinical validity of Doppler umbilical velocimetry in identifying fetal acidosis or compromise.

Acidosis↗
PubMed1992

In vivo protein adsorption on polymers: visualization of adsorbed proteins on vascular implants in dogs.

The absorption of plasma proteins is an important event at the blood-material interface, and strongly affects subsequent cellular interaction and thrombus formation. Although considerable efforts have been expended to elucidate the mechanism of protein adsorption and the role of absorbed protein layer at the blood-material interface, there has been little knowledge of how the initial adsorbed proteins are maintained or changed in a time-variant process in in vivo long-term implantation. In this study, we described detailed analyses concerning the characterization of adsorbed proteins on HEMA--styrene block copolymer surfaces (HEMA-st) and poly(ethylene oxide) (PEO) grafted Biomer (B-PEO4K) for in vivo long-term canine vascular graft implants as well as in vitro short-term experiments. Biomer vascular grafts (6 mm I.D., 7 cm in length) were fabricated by a dip coating and the luminal surface was modified with PEO grafting, HEMA-st coating, or Biomer coating (control). These surface modified grafts were recirculated for different time intervals (5, 15, 30, 60 and 120 min) using citrated canine whole blood. The grafts were then implanted in the abdominal aortas of dogs and evaluated for graft patency and protein adsorption. The adsorbed proteins (albumin, IgG and fibrinogen) were quantified using an in situ radioimmunoassay. Surface protein layer thickness was measured by transmission electron microscopy (TEM). Visualization of absorbed plasma proteins (albumin, IgG and fibrinogen) was performed with TEM using an immunoperoxidase double antibody technique. In in vitro recirculation systems, albumin and IgG showed similar Langmuir type pattern onto all test surfaces. On B-PEO4K surfaces, fibrinogen adsorption kinetics demonstrated 'Vroman effect'. The Biomer and B-PEO4K grafts occluded within 1 month, while HEMA-st grafts were patent for over 3 months. Biomer and B-PEO4K showed thick multilayers of adsorbed proteins, and the thickness increased with implantation periods and the composition altered with time. In contrast, HEMA-st showed a monolayer-like adsorbed protein pattern, and the composition and thickness were consistent regardless of implantation time including in vitro short-time experiments, which may attribute to less conformational change of adsorbed proteins on HEMA-st surfaces. In terms of nonthrombogenicity, the stable monolayer-like adsorbed protein layer on HEMA-st surfaces exhibited improved blood compatibility over thick multilayered adsorbed proteins on Biomer and B-PEO4K surfaces.

Adsorption↗
PubMed1992

Haloperidol decanoate pharmacokinetics in red blood cells and plasma.

Red blood cell (RBC) and plasma concentrations of haloperidol (H) and reduced haloperidol (RH) were determined in nine patients (five men, four women) who had been receiving monthly injections of haloperidol decanoate (HD) for at least 3 months. A very sensitive high performance liquid chromatography method was used to measure H and RH, which could be detected at levels as low as 0.1 ng/ml. Blood samples for H and RH were drawn at the end of weeks 1, 2, 3, and 4 of a 4-week cycle. Monthly HD dosages ranged from 50 mg to 200 mg. At each time point RBC H did not differ significantly from plasma H. RBC RH and plasma RH did not change significantly over time and were consistently lower than RBC H and plasma H. However, RBC RH levels were higher than plasma RH levels. Also, the ratios of RBC RH/H were higher than were the ratios of plasma RH/H, which reflect an accumulation of RH intracellularly. HD dosage was highly correlated with both RBC H and plasma H, but RBC RH and plasma RH were not significantly related to dosage at any time point. Significant correlations were observed between HD dosage and prolactin concentration at week 1 and between prolactin concentration and RBC H and plasma H at weeks 1 and 4. Blood concentrations of H and RH and the corresponding standardized areas under the curve were not significantly related to smoking.

Adult↗
PubMed1991

Electrically erodible polymer gel for controlled release of drugs.

New controlled drug-delivery systems are being explored to overcome the disadvantages of conventional dosage forms. For example, stimulated drug-delivery has been used to overcome the tolerance problems that occur with a constant delivery rate, to mimic the physiological pattern of hormonal concentration and to supply drugs on demand. Stimuli-sensitive polymers, which are potentially useful for pulsed drug delivery, experience changes in either their structure or their chemical properties in response to changes in environmental conditions. Environmental stimuli include temperature, pH, light (ultraviolet or visible), electric field or certain chemicals. Volume changes of stimuli-sensitive gel networks are particularly responsive to external stimuli, but swelling is slow to occur. As well as being useful in the controlled release of drugs, such systems also provide insight into intermolecular interactions. Here we report on a novel polymeric system, which rapidly changes from a solid state to solution in response to small electric currents, by disintegration of the solid polymer complex into two water-soluble polymers. We show that the modulated release of insulin, and by extension other macromolecules, can be achieved with this polymeric system.

Acrylic Resins↗
PubMed1991

Platelet 3H-imipramine binding sites in obsessive-compulsive behavior.

Several studies indicate a serotonergic dysfunction in patients with obsessive-compulsive disorder (OCD). We examined serotonergic function in OCD by determining platelet 3H-impiramine binding sites in patients with OCD during a drug-free baseline period as well as normal control volunteers. The maximum number of binding sites (Bmax) and apparent dissociation constant (Kd) was determined using 3H-imipramine (IMI) as the binding ligand. We observed that the mean 3H-IMI binding Bmax (fmol/mg protein) determined in 24 patients with OCD was not significantly different from that in 23 normal control subjects. There were no significant differences in the Kd between patients with OCD and normal control subjects. Our results are thus similar to those reported by Insel et al (1985) and Black et al (1990), who observed no significant differences in platelet 3H-IMI binding between OCD patients and controls; but different from those reported by Weizmann et al (1986), who observed decreased 3H-IMI Bmax in OCD patients. The discrepancy in the results is not clear, but may be related to several factors. Our results thus indicate that any abnormality in serotonergic function present in patients with OCD is not related to imipramine binding sites in the platelets. However, the possibility that there may be an abnormal platelet serotonin uptake or other serotonergic function in OCD cannot be ruled out.

Adult↗
PubMed1991

[MR imaging of osteoradionecrosis of the mandibula following radiotherapy for head and neck cancers].

Magnetic resonance (MR) images of 13 patients with osteoradionecrosis of the mandibula were analyzed. Abnormalities were noted in all patients and could be classified into three groups. In nine patients, MR signals were homogeneously low in intensity on both T1 weighted images (T1WI) and T2 weighted images (T2WI), suggesting fibrosis of bone marrow. These nine patients had suffered radiologically and/or clinically overt osteoradionecrosis more than ten months previously, and inflammatory symptoms had settled down by the time of MR study. Two patients showed low signal intensity on T1WI and an area of inhomogeneous high intensity in a diffuse area of low signal intensity on T2WI, suggesting acute inflammation in the irradiated fibrous bone marrow. Both patients suffered pathologic fracture due to osteoradionecrosis and showed severe inflammatory symptoms at the time MR study. In one of the two patients, these pathologic changes were confirmed in surgically excised mandibulectomy specimens. The other two patients showed homogeneous low signal intensity on T1WI and high signal intensity on T2WI, a finding that may be due to slight inflammation. However, in one of the two patients, this signal feature possibly indicated loose fibrosis with marked cellularity.

Adult↗
PubMed1991

Effect of silicone rubber surface on the calcium balance of human serum.

The nature and mechanism of calcium complexation with human serum components in the presence of silicone rubber were assessed in in vitro model experiments. Silicone rubber samples were incubated for 67 h in serum of both physiologic calcium concentrations and induced hypercalcemic levels. Physiologic calcium incubation decreased the intrinsic and nth binding site association constants by factors of 2 and 4, respectively, from initial serum values. Incubation with silicone rubber did not change the association constants. Hypercalcemia incubation lowered the intrinsic and nth binding site association constants by 39 and 61%, respectively. Polymer incubation increased the intrinsic association constant and decreased the number of binding sites by a factor of 2. With initial binding site association constants unperturbed by incubation and Hill coefficients equivalent to 1, complexation was non-cooperative and binding sites were considered to be identical and independent. Both Scatchard and Hill plots show nonlinearity for the polymer incubation case giving two distinct linear regions. This is indicative of cooperative binding for incubation with polymer; the Hill coefficient for the physiologic calcium concentration range was 0.97, while the coefficient for the hypercalcemic calcium range was 6.

Calcium↗