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Biomedical subjects

Yuka Kobayashi

Publications and source records attributed to Yuka Kobayashi.

32 records · Page 2Linked to original sources

Supramolecular architecture consisting of an enantiopure amine and an achiral carboxylic acid: application to the enantioseparation of racemic alcohols.

Three-dimensionally dissymmetric cavities are created from an enantiopure amine and an achiral carboxylic acid, which can incorporate the third components to realize the formation of closely packed crystals. The combination demonstrates enantioselective inclusion for 20 kinds of racemic alcohols. The inclusion phenomenon occurs not only during crystallization but also in the solid state.

Journal Article↗

Reaction of [2-(SiH3)C6H4]2SiH2 with Ni(Et2PCH2CH2PEt2)(PEt3)2: characterization of eta2-(Si-H)Ni and NiIV-H complexes.

The reaction of (2-SiH3C6H4)2SiH2 with Ni(Et2PCH2CH2PEt2)(PEt3)2 afforded a new silylnickel complex, which, in the solid state, was determined to be a bis(silyl)eta2-(Si-H)nickel complex, the first example of eta2-(Si-H)nickel complex by single-crystal X-ray analysis. Variable-temperature NMR spectroscopy revealed fluxional behavior of the complex in solution; at room temperature, exchange of five hydrogens (two SiH2 and one hydrogen bound to nickel) was observed, while at -80 degrees C the exchange of hydrogens appeared frozen to adopt a tris(silyl)(hydrido)nickel(IV) structure, which was confirmed by theoretical calculation. The latter complex is the first example of hydridonickel(IV) complex.

Journal Article↗

Effects of oral glucose intake on gastric myoelectrical activity and gastric emptying.

To investigate the effect of oral glucose intake on gastric motility, we measured gastric myoelectrical activity and gastric emptying on two test conditions: 1) glucose intake and 2) water intake in the same 10 healthy male volunteers (20 to 29 years old). Gastric motility was evaluated with cutaneous-recorded electrogastrography (EGG) for 30 min both on fasting and after glucose or water intake, while gastric emptying was measured using acetaminophen-absorption method. There were no significant changes in EGG dominant frequency after water intake, but the frequency increased significantly after glucose intake. A postprandial dip (i.e., a transient decrease in frequency immediately after the food intake) was observed in 3 subjects after water intake and in 8 subjects following glucose intake. The EGG power ratio was significantly larger after glucose than water intake, with delayed gastric emptying in the former case. These results suggest that glucose is one of the components responsible for postprandial gastric motility.

Administration, Oral↗

Synthesis and structure of macrocyclic bis(hydroxynaphthoic amide)s connected by an achiral or chiral diamine.

Macrocyclic bis(hydroxynaphthoic amide)s 6, connected by an achiral or chiral diamine, were synthesized by the tandem Claisen rearrangement. CD spectra, X-ray crystallographic analyses, and variable-temperature NMR measurements of the chiral bis(hydroxynaphthoic amide)s revealed that the two hydroxynaphthalene rings in these macrocycles adopt a twisted conformation both in solution and in the crystalline state because of the steric hindrance between the two hydroxynaphthalene rings and that the chirality of the twisted conformation is generated by that of the chiral linker. Theoretical calculations revealed that the chiral linker works effectively to favor energetically one conformer of the diastereomers, although a flipping process was possible and can be observed to occur on the NMR time scale in variable-temperature experiments.

Journal Article↗

Light-driven open-close motion of chiral molecular scissors.

The first example of "light-driven chiral molecular scissors" (1), which consists of 1,1',3,3'-tetraarylferrocene as a pivot part and azobenzene as a driving part, was synthesized. Absorption, circular dichroism (CD), and 1H NMR spectral studies on the photoinduced isomerization process of an enantiomer of 1 agreed well with a prediction by a DFT calculation, where a motion of the handles via light-driven contraction/expansion of the connecting azobenzene strap was transformed, through a pivotal motion of the ferrocene unit, into an open-close motion of the blade parts.

Journal Article↗

Gastric myoelectrical activity in patients with recurrent gastric or duodenal ulcers.

The aim of this study was to characterize gastric myoelectrical activity in patients with recurrent gastric ulcer (GU) or duodenal ulcer (DU), and to compare gastric motility between these two groups of patients. Studies were performed in 59 patients with recurrent active peptic-ulcer disease as diagnosed by gastrointestinal endoscopy: 31 patients had a GU and 28 patients had a DU. Gastric myoelectrical activity was evaluated by cutaneous electro-gastrography (EGG). The following EGG parameters were assessed: the percentage of normogastria (regular 2.4-3.6 cpm slow waves); the EGG power ratio; and the occurrence of a postprandial dip (PD), which is the transient decrease in EGG frequency after a meal. In the GU group, no significant change occurred in the percentage of normogastria or in the EGG power ratio observed after treatment with a proton-pump inhibitor. During the healed stage, the occurrence of PD remained unchanged. In contrast, in the DU group, the percentage of normogastria and the EGG power ratio were significantly increased after treatment. Moreover, during the healed stage, the occurrence of PD significantly increased compared with that during the active stage. These findings suggest that abnormal gastric myoelectrical activity plays an important role in the pathophysiology of recurrent GU rather than DU.

2-Pyridinylmethylsulfinylbenzimidazoles↗

[Quinacrine administration to a patient with Creutzfeldt-Jakob disease who received a cadaveric dura mater graft--an EEG evaluation].

An old antimalarial drug quinacrine is one of the compounds that can inhibit the accumulation of pathogenic prion protein in cultured neuroblastoma cells. Here we report the result of a clinical trial of quinacrine administration to a patient with Creutzfeldt-Jakob disease (CJD). A 37-year-old woman was admitted to our hospital for ataxic gait, hallucination and dementia in August 2001. As a past history she had received an operation for cerebellar astrocytoma and had a cadaveric dura mater graft at 14 years old. After hospitalization she showed signs of anxiety, stimulus-sensitive myoclonus, decorticate rigidity, then deteriorated pursuit eye movement and voluntary limb movement. The ethics committee of Dokkyo University hospital approved this treatment, and the family of the subject was fully informed as to the nature and purpose of the treatment and gave their consent. One week after the administration of 300 mg/day of quinacrine, voluntary limb movement and pursuit eye movement appeared. There was PSD on EEG, but one week after administration of the quinacrine, PSD disappeared, and a theta wave was recognized as the basic activity on the EEG. But her symptoms deteriorated again after 3 weeks, and PSD appeared. Liver dysfunction developed 2 months after administration, and the administration of quinacrine had to be stopped. Quinacrine was administrated to a CJD patient who received a cadaveric dura mater graft and developed CJD 23 years later. The symptoms of the patient were transiently improved with the disappearance of PSD on EEG. Although the mechanism of quinacrine for the central nervous system is still unclear, this case suggests that quinacrine may be clinically one possible drug for treating CJD.

Adult↗

Pancreatic T-cell lymphoma with high level of soluble interleukin-2 receptor.

An 82-year-old man was admitted to hospital with symptoms of abdominal fullness and loss of appetite. Abdominal computed tomography (CT) scan and ultrasonography showed enlargement of the whole pancreas with para-aortic lymphadenopathy. Endoscopic retrograde pancreatography (ERP) showed diffuse narrowing of the main pancreatic duct (MPD), and brushing cytology from the MPD was non-neoplastic. Differential diagnosis between lymphoma and other exocrine and endocrine pancreatic malignancies was needed, and the level of serum soluble interleukin-2 receptor (17 751 U/ml) was revealed to be significantly high, which was strongly suggestive of pancreatic lymphoma. Chemotherapy was refused by the patient's family and the patient succumbed after 2 months of conservative follow-up. Autopsy revealed diffuse, mixed cell-type, non-Hodgkin's lymphoma of T-cell subtype.

Aged↗

Gastric motility in patients with recurrent gastric ulcers.

The existence of abnormal gastric motility in gastric ulcer disease remains controversial. The aim of this study was to characterize gastric motility in patients with recurrent gastric ulcers. Studies were performed in 10 control subjects and in 24 patients with recurrent active gastric ulcer disease as diagnosed by gastrointestinal endoscopy. Gastric motility was evaluated by cutaneous electrogastrography (EGG) and by gastric semi-liquid meal emptying. The EGG was recorded before and after ingestion of a test meal containing 20 mg/kg of acetaminophen. Patients with a dominant EGG frequency of greater than 0.06 Hz were defined as tachygastria, while those with a frequency of less than 0.04 Hz were defined as bradygastria. A transient frequency decrease, called postprandial dip (PD), was identified visually. The degree of gastric emptying was determined from the serum acetaminophen concentration 45 minutes after the meal. Control subjects showed no irregularity in their dominant EGG frequency in tither fasting or postprandial states. PD was observed in 8 control subjects. In patients presenting with active gastric ulcers, abnormal patterns in the dominant EGG frequency (either as tachygastria or bradygastria) were observed in 14 of the 24 patients when fasting and in 15 of them in the postprandial state. After successful treatment, the number of patients with abnormal patterns in their dominant EGG frequency remained unchanged, while PD was observed in 11 patients. No significant difference was observed in the EGG power ratio as a result of successful treatment. Gastric emptying was significantly delayed compared with controls in both the active and healed stages. These findings suggest that abnormal gastric motility, including gastric electrical abnormalities and delayed gastric emptying, plays an important role in the pathophysiology of recurrent gastric ulcers.

Adult↗

[Nacrolepsy manifesting initially as cataplexy and sleep paralysis: usefulness of CSF hypocretin-1 examination for early diagnosis].

We report a 24-year-old man with narcolepsy initially suffered from cataplexy and sleep paralysis. From May 2000, at age 23 he experienced two kinds of recurrent episodes of weakness without altered consciousness; one was provoked by emotion and excitement, the other occurred spontaneously on onset of sleep without hallucination. He denied having daytime sleepiness and did not experience hypnagogic hallucinations. In July 2000, at our hospital he received the first medical examinations, of which physical and neurological results were unremarkable. A magnetic resonance imaging scan of the brain also gave unremarkable results. The initial diagnosis was epilepsy, and anti-convulsant drugs were begun in August 2000. The weakness episodes were not lessened by the treatment with carbamazepine, sodium valproate or clonazepam, and he was admitted to our clinic in April 2001 for further examinations. Human leukocyte antigen testing was positive for DR15 (DR2) and DQ6 (DQ1). The routine electroencephalographam detected no epileptic discharge or paradoxical alpha blocking. A polysomnogram showed a sleep onset REM sleep period and sleep fragmentation, but there was no apnea or periodic leg movements. A multiple sleep latency test showed a mean sleep latency of 1.8 min and REM sleep in three of five naps. These findings suggested probable narcolepsy, so we examined the hypocretin-1 (orexin A) concentration in his cerebrospinal fluid (CSF). It was below the detection limit of the assay (< 40 pg/mL). The final diagnosis in April 2001 was narcolepsy. Making an initial diagnosis of incomplete or atypical narcolepsy is difficult for clinicians. A delay in diagnosis, however, may produce personal and social problems for narcoleptic patients. We believe that an examination of CSF hypocretin-1 aids in the early diagnosis of narcolepsy.

Adult↗

Advanced gastric glandular-endocrine cell carcinoma with 1-year survival after gastrectomy.

Primary gastric endocrine cell carcinoma (ECC) is extremely rare. In general, when it is advanced, gastric ECC causes extensive ulceration (type 2) and invades or metastasizes to other organs, frequently to the liver and sometimes to the lungs or bones, and carries a poor prognosis. We herein report a 67-year-old man with advanced gastric ECC of extensive-polypoid shape (type 1) but without distant metastasis, who underwent total gastrectomy and treatment with oral tegafur-uracil (UFT), and showed no sign of recurrence 1 year later.

Journal Article↗

Absence of pretreatment markers that predict the emergence of YMDD mutants during lamivudine treatment--the results of a prospective multi-center study.

BACKGROUND/AIMS: The emergence of YMDD mutants in patients who are treated with lamivudine may determine the clinical prognosis. However, currently there are no clinical or virological factors that predict specifically the emergence of the mutants. METHODOLOGY: To define these factors, we analyzed 69 patients with chronic hepatitis B infection who were treated with lamivudine (LAM) and followed prospectively for at least 12 months. RESULTS: Of the 69 patients, 12 (17.4%) developed YMDD mutants up to 12 months after the start of LAM. The incidence of YMDD mutants was slightly higher in those who were younger, had higher HBV DNA titers, lower ALT levels, genotype C, and mutations in the core promoter before treatment. However, we could not find any significant factors that correlated with the appearance of the mutants. CONCLUSIONS: Currently, using conventional virological assays, it is difficult to predict the development of mutants before LAM treatment. Management of flare-ups of hepatitis, due to the appearance of mutants, should always be envisaged when LAM treatment is started.

Adult↗