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Biomedical subjects

K B Yoon

Publications and source records attributed to K B Yoon.

7 recordsLinked to original sources
PubMed2001

Layer-by-layer assembly of zeolite crystals on glass with polyelectrolytes as ionic linkers.

ZSM-5 crystals and glass plates tethered with trimethylpropylammonium iodide and sodium butyrate, respectively, (denoted as Z+, Z-, G+, and G-, respectively) were prepared. Treatment of G- with Z+ suspended in ethanol results in monolayer assembly of Z+ on G- (G-/Z+) with high surface coverage. The zeolite crystals have a strong tendency to closely pack and align with the b-axis normal to the glass plate, despite large positive zeta potentials. Subsequent treatment of G-/Z+ with Z- leads to second-layer assembly of Z- on G-/Z+ (G-/Z+/Z-), but with rather poor coverage. Sequential treatment of G+ with poly(sodium 4-styrenesulfonate)(Na+PSS-), poly(diallyldimethylammonium chloride) (PDDA+Cl-), and Na+PSS- followed by Z+ yields glass plates assembled with monolayers of Z+ with very high surface coverage through the composite polyelectrolyte linkers (G+/PSS-/PDDA+/PSS-/Z+). The zeolite crystals also have a strong tendency to closely pack and align with the b-axis perpendicular to the substrate plane. The binding strength between the zeolite crystals and glass plates is much higher in G+/PSS-/PDDA+/PSS-/Z+ than in G-/Z+. Repetition of the sequential PSS-/PDDA+/PSS-/Z+ layering for five cycles yields glass plates assembled with pentalayers of ZSM-5 crystals [G+/(PSS-/PDDA+/PSS-/Z+)(5)]. The observed degrees of coverage and alignment of zeolite crystals in each layer were very high up to the third layers despite the nonuniformity of the sizes and shapes of the zeolite crystals used in this study. This report thus demonstrates the feasibility of layer-by-layer assembly of micrometer-sized zeolite crystals on glass through electrostatic interaction between surface-bound, full-fledged ionic centers, especially by use of polyelectrolyes as the linkers.

Journal Article↗
PubMed2001

Iodide-to-cation charge-transfer bands as a novel probe for evaluation of actual acceptor strengths of cations in zeolites and cation-dependent pore volume change.

Iodide-to-cation charge-transfer (ITC-CT) bands have been measured for the first time in zeolites X and Y exchanged with a series of alkali metal ions and the results show that the ITC-CT band progressively red shifts with increasing the size and the number of site III cations in the supercage, which indicates that the actual acceptor strength of the cation toward iodide increases with increasing the degree of protrusion of the cation into supercages and the number of cations, and overall, with decrease in supercage volume.

Journal Article↗
PubMed1999

The effects of epidural blockade on the acute pain in herpes zoster.

OBJECTIVE: To evaluate the relief of acute pain and possible preventive effects on postherpetic neuralgia through the use of an epidural blockade in the acute stage of herpes zoster. DESIGN: Prospective, nonrandomized, comparative clinical trial. SETTING: A dermatologic clinic in a university hospital. PATIENTS: Sixty-five consecutive patients with pain due to acute herpes zoster were treated for a 7-day hospitalization period from July 1, 1996, through June 30, 1997. INTERVENTION: The consecutive patients were divided into 2 groups. Group A consisted of 30 patients who were seen from July 1, 1996, through December 31, 1996, and who were treated with intravenous acyclovir (5 mg/kg) for 7 days. Group B consisted of 35 patients who were seen from January 1, 1997, through June 30, 1997, and who were treated with intravenous acyclovir (5 mg/kg) and an epidural blockade for 7 days. The changes in the intensity of pain and the total duration of pain in both groups were assessed for 12 to 18 months. MAIN OUTCOME MEASURES: The number of days required for relief of pain and the total duration of pain. RESULTS: The mean +/- SD number of days required for relief of pain, which was rated on a scale of 100 (worst pain) to 0 (no pain), was significantly fewer in group B than in group A: it took 2.6 +/- 1.1 days to go from 100 to 50 on the relief-of-pain scale in group B, but 3.8 +/- 1.1 days in group A (P = .03), and 12.5 +/- 6.4 days to go from 100 to 10 in group B, but 20.1 +/- 14.6 days in group A (P = .04). The duration of late residual pain was significantly shorter in group B (5.9 +/- 5.8 days) than in group A (11.9 +/- 7.5 days) (P = .03). The total duration of pain was also significantly shorter in group B (18.5 +/- 9.3 days) than in group A (31.6 +/- 17.6 days) (P = .04). CONCLUSIONS: We believe that an epidural blockade combined with an antiviral agent is a very effective treatment modality for the pain of acute herpes zoster, and we recommend its use for the prevention of postherpetic neuralgia, with a view to shortening the total duration of pain, especially late residual pain.

Acute Disease↗
PubMed1999

Long-term outcome of percutaneous thermocoagulation for trigeminal neuralgia.

A retrospective analysis of long-term efficacy of percutaneous radiofrequency thermocoagulation of the trigeminal ganglion or root for the relief of trigeminal neuralgia was carried out in our unit. From the medical records and questionnaires, outcomes of 108 procedures performed in 81 patients from January 1986 to December 1990 were obtained with a follow-up period of 6-11 years. The initial success rate was 87% and the probability of remaining pain-free 1, 2 and 11 years after the procedure was 65, 49 and 26%, respectively. Patients with typical symptoms had a better long-term efficacy than those with atypical presentations, and patients who had not undergone a previous surgical procedure also had a better outcome. There was no mortality in this series. Common adverse effects included dysaesthesia in 20 patients, corneal numbness in 12 patients and masseter weakness in three patients.

Adult↗
PubMed1998

Presence of emerinopathy in cases of rigid spine syndrome.

Rigid spine syndrome (RSS) shows clinical similarities to Emery-Dreifuss muscular dystrophy (EDMD). Differential diagnosis between EDMD and RSS is essential because EDMD is often associated with life-threatening cardiomyopathy that can be cured by an implantation of a cardiac pacemaker. To determine if any of the patients with RSS had mutations of the emerin gene (responsible gene for X-linked EDMD or emerinopathy), we screened the patients for mutations. We found seven patients with a clinical picture consistent with RSS in the 6500 diagnostic muscle biopsies in our National Center over the last 19 years. We identified a novel mutation in the gene (1-bp frame-shift deletion in the exon 1) in one of the seven patients with RSS. This mutation created a premature termination at codon 12 and was expected to produce a severely truncated emerin. Emerin was not detected in the skeletal muscle. The unaffected mother of the patient was a heterozygous carrier for the mutation. The remaining six patients with RSS had no mutation in the gene and showed normal expression of emerin in the skeletal muscle. Our results emphasize the presence of clinical overlap between possible RSS and EDMD, and reinforce the necessity of molecular genetic diagnosis of emerin to exclude emerinopathy in a patient population that has a clinical diagnosis of RSS.

Adolescent↗
PubMed1992

Autoimmune progesterone dermatitis.

A 35-year-old woman had recurrent urticarial erythemas on her trunk and extremities for 3 years. The eruptions appeared regularly 3 to 5 days prior to menstruation and persisted for several days. The patient showed a positive skin test response to progesterone and had circulating antiprogesterone IgG antibodies. A speculative concept of the possible autoimmune damage to the ovary, the major organ producing progesterone, is discussed.

Adult↗