Biomedical subjects

Y Y Lin

Publications and source records attributed to Y Y Lin.

At least 19 recordsLinked to original sources

PubMed1999

Serum anti-p53 antibodies in gastric adenocarcinoma patients are associated with poor prognosis, lymph node metastasis and poorly differentiated nuclear grade.

Mutation of the p53 tumour suppressor gene often leads to the accumulation of mutant p53 protein in tumour cells. Many cancer patients develop antibodies that recognize the overexpressed p53 protein. The presence of these antibodies is, in some tumour types, associated with poor prognosis. Gastric cancer is a highly prevalent disease associated with a high rate of mortality, there is a need for improved clinical and biological markers for disease behaviour. To investigate the clinical relevance of serum anti-p53 antibodies in patients with gastric adenocarcinoma, we have examined the sera of 501 gastric cancer patients for the presence of serum antibodies against the p53 protein. By immunoblotting analysis using a cell lysate containing overexpressed p53 protein as well as affinity-purified recombinant p53 protein as antigens, we have detected anti-p53 antibodies in 11.2% (61 of 501) of gastric cancer patients, but in none of 46 cancer-free individuals. The presence of anti-p53 antibodies was tightly associated with tumours of higher nuclear grade and lymph node metastasis, and a negative association was found between the presence of anti-p53 antibodies and survival. These results suggest that a preoperative test of serum anti-p53 antibodies in gastric cancer patients can be useful to identify subset of patients who may need gastrectomy with lymph node dissection and post-operative adjuvant therapy.

Adenocarcinoma↗

PubMed1998

pH of preparations affecting the on-off drug penetration behavior through the thermo-responsive liquid crystal-embedded membrane.

A liquid crystal (cholesteryl oleyl carbonate, COC)-embedded membrane with a controlled rate and higher reversibly thermo-responsive function was successfully fabricated by the vacuum filtration method. The aim of this study was to investigate the effect of the pH of aqueous solutions and gel preparations on the penetration of salbutamol sulfate through this thermo-responsive COC-embedded membrane. The results indicate that the on-off switching penetration behavior of salbutamol sulfate through the COC-embedded membrane in response to a repeatedly exchanging temperature cycle (10 <=> 25 degreesC) is not influenced by the pH of the medium. However, the pH-dependent ionization of salbutamol and the viscosity of the gel base, as well as the interaction between salbutamol and carbopol, might change the amount and the rate of salbutamol sulfate that penetrates across this COC-embedded membrane.

Acrylic Resins↗

PubMed1998

Detection of P450c17-independent pathways for dehydroepiandrosterone (DHEA) biosynthesis in brain glial tumor cells.

Dehydroepiandrosterone (D) is biosynthesized in the brain by a pathway different from that existing in the adrenal cortex. C6 rat glioma tumor cells in culture biosynthesize both pregnenolone (P) and D. They possess the mRNA, protein, and side-chain cleavage activity of P450scc. On the other hand, P450c17 was not detected. Adding FeSO4 to C6 cells increased the synthesis of both P and D. Even in the presence of aminoglutethimide, an inhibitor of P450scc, FeSO4 increased the synthesis of both steroids, indicating that the Fe2+-sensitive process does not involve P450scc. Likewise, the FeSO4-induced formation of D was not blocked by the P450c17 inhibitor, SU-10603. These results suggest that the FeSO4-induced synthesis of D as well as of P in C6 cells may be due to the fragmentation of in situ-formed tertiary hydroperoxides. It is likely, however, that the effect of the Fe2+ is not limited to this one reaction. When exogenous P was added to C6 microsomes, along with FeSO4, the amount of D formed was greater than control values, indicating that Fe2+ facilitated the conversion of P to D. Unlike the constituents that are converted by Fe2+ to P, the precursor of D in C6 cells is not soluble in a 1:1 mixture of ether and ethylacetate. Treatment of C6 cells with KI, NaBH4, or HIO4 resulted in an increase in D synthesis. From this it seems clear that a precursor of the D produced in C6 cells is a steroid where both C-17 and C-20 are oxygenated.

Aminoglutethimide↗

PubMed1997

Diminished vasomotor component of systemic arterial pressure signals and baroreflex in brain death.

We compared the cardiovascular autonomic regulatory mechanisms between patients with brain death or under a persistent vegetative state and healthy volunteers, based on auto- and cross-spectral analysis of systolic blood pressure (SBP) and interpulse interval (PPI) signals. Brain-dead patients exhibited a significant reduction in the absolute and relative power of the low-frequency (LF; 0.04-0.15 Hz) component in both SBP and PPI spectra, along with appreciable decrease in the very low frequency (VLF; 0.004-0.04 Hz), LF, and high-frequency (HF; 0.15-0.4 Hz) power of the PPI signals. Patients in a persistent vegetative state exhibited a power of the VLF and LF component in the SBP spectrum that was comparable to that in healthy subjects, although a discernible reduction in the VLF, LF, and HF power of the PPI spectrum was manifested by the former group. Assessments with the magnitude of SBP-PPI transfer function and linear regression analysis of beat-to-beat fluctuations in SBP and PPI revealed a progressive decline in spontaneous baroreflex sensitivity from healthy subjects to patients in a persistent vegetative state or with brain death. We conclude that the vasomotor component of systemic arterial pressure signals and spontaneous baroreflex are highly correlated with the functional integrity of the brain stem.

Adult↗

PubMed1997

Relationship between mesial temporal seizure focus and elevated serum prolactin in temporal lobe epilepsy.

We evaluated the relationship between mesial temporal seizure focus and serum prolactin (PRL) in patients before and after they underwent anterior temporal lobectomy (ATL) for medically intractable temporal lobe epilepsy (TLE). These patients had a confirmed unilateral epileptogenic focus in mesial temporal structures, a postictal rise in serum PRL 15 to 20 minutes after onset of complex partial seizures, and were refractory for more than 2 years to antiepileptic drugs. Presurgical interictal serum PRL levels were significantly elevated (16.47 +/- 0.85 ng/mL, n = 62) and declined after ATL to normal values (patients, 9.63 +/- 0.55 ng/mL, n = 54; normal subjects, 8.99 +/- 0.57 ng/mL, n = 52). Serial evaluations indicated that normalization was seen 3 months after surgery (9.42 +/- 1.22 ng/mL, n = 9). The postsurgical reduction in serum PRL was similar in men and women, in patients with epileptogenic focus on either side of mesial temporal structures, and was unaffected by antiepileptic medication. We conclude that PRL is elevated following seizures and that a seizure focus in mesial temporal structures may exert a sustained excitatory influence on PRL release in patients with medically intractable TLE.

Adolescent↗

PubMed1997

Lamotrigine as add-on therapy in adult patients with refractory epilepsy.

BACKGROUND: Lamotrigine (LTG), one of the newly developed antiepileptic drugs, is efficacious in treating both partial and generalized seizure disorders including Lennox-Gastaut syndrome. Its effect as an add-on therapy was evaluated in 41 adult Chinese patients with refractory epilepsy. Five of the patients were Lennox-Gastaut syndrome and 36 patients had partial epilepsy. METHODS: We started LTG at 25 mg or 50 mg per day, respectively, depending on whether the patients were simultaneously taking valproate (VPA) or not. Then, LTG was increased in steps to maximal dosage (200 mg or 400 mg per day) within seven weeks and maintained for three months while pre-existing antiepileptic drugs remained unchanged. The efficacy of LTG therapy was assessed by the reduction in the overall seizure frequency. Hematological and biochemical parameters were checked before and after the trial in all patients. RESULTS: In all, 38 patients completed the trial. Twenty-two patients (57.9%) had > or = 50% reduction in seizure frequency, including four patients with Lennox-Gastaut syndrome and 18 patients with partial seizures. Among the patients with partial epilepsy, there was no significant difference in the efficacy of LTG whether the seizures were of temporal or extra-temporal origin (p = 0.577). In addition, the efficacy was not determined by the concomitant use of VPA (p = 0.189). Thirteen patients (31.7%) complained of adverse experiences, usually mild and dose-dependent. LTG had to be discontinued in only two patients (4.9%) due to severe side effects. The change in blood cell counts and biochemistry profiles was not significant in any of the patients. CONCLUSIONS: We conclude that LTG is an efficacious and safe antiepileptic drug for add-on therapy in adult patients with refractory epilepsy.

Adolescent↗

PubMed1996

Six lignans from Phyllanthus myrtifolius.

Six lignans comprising phyllamyricins D (1), E (2), and F (3) and phyllamyricosides A (4), B (5), and C (6) were isolated in a continuing study of Phyllanthus myrtifolius. Compounds 1 and 2 are 2a-methoxy-4-aryl-2,3-naphthalides. Compounds 3-6 belong to the 4-arylnaphthalene class, with compounds 4-6 being O-beta-glucosides. Their structures were elucidated on the basis of spectral analysis. Compound 4 increased the activity of HIV-1 reverse transcriptase by 65% at a concentration of 1.89 microM.

HIV Reverse Transcriptase↗

PubMed1996

Permeation behavior of salbutamol sulfate through hydrophilic and hydrophobic membranes embedded by thermo-responsive cholesteryl oleyl carbonate.

PURPOSE: To investigate the suitability of hydrophilic or hydrophobic membranes for use as potential thermo-responsive drug delivery system. METHODS: Liquid crystal was embedded in membranes using vacuum filtration method to control the penetration rate of salbutamol sulfate. Cholesteryl oleyl carbonate (COC) with smectic-cholesteric phase transition temperature near 18 degrees C was used as a model liquid crystal. RESULTS: It indicates only hydrophilic salbutamol sulfate can penetrate through the hydrophilic membranes embedded with or without COC, in which the permeation is mainly governed by the adsorption of COC. However, the hydrophilic drug do not pass through the hydrophobic membranes even if not embedded with COC. The void volume of the membrane also influences the penetration of salbutamol sulfate. The higher thermo-response efficacy of the COC-embedded membranes can be explained not only by less permeability through matrix part of the membrane but also by higher thermal motion of the COC molecules due to above the phase transition temperature. CONCLUSIONS: A COC-embedded membrane with rate-controlled and thermo-responsive function is easily prepared by vacuum filtration method. High reversibly thermo-responsive function can be achieved by choosing membrane and COC concentration properly.

Albuterol↗

PubMed1996

Cytotoxicity and NMR spectral assignments of ergolide and bigelovin.

Two potent cytotoxic sesquiterpene lactones, ergolide (1) and bigelovin (2) were isolated from Inula hupehensis I. helianthus-aquatica and their structures and NMR data were assignment unambiguously by using a combination of one-and two-dimensional NMR techniques and computer modeling calculations.

Antineoplastic Agents, Phytogenic↗

PubMed1996

Ictal speech manifestations in temporal lobe epilepsy: a video-EEG study.

To evaluate ictal speech manifestations in complex partial seizures (C PS), we reviewed videotapes of 68 consecutive patients who underwent anterior temporal lobectomy (ATL) for treatment of intractable epilepsy in Taiwan. In all, 261 CPS were collected from their video-EEG (VEEG) recordings. Cerebral speech dominance was determined by intracarotid injection of sodium amobarbital (Wada test) in all cases. Ictal speech manifestations, classified as verbalization or vocalization, occurred in 32 patients (47.1%) with 96 seizures (36.8%). Ictal verbalization occurred in 10 patients (14.7%). Ictal vocalization was observed in 28 patients (41.2%); including 6 patients who also had ictal verbalization. Thirty-six patients (52.9%) had no seizure with ictal speech manifestations. Ictal verbalization had significant lateralization value: 90% of patients with this manifestation had seizure focus in the nondominant temporal lobe (p = 0.049). Seizures of patients with ictal vocalization were not more likely to arise from either temporal lobe. We also observed bilingual patients who exclusively spoke in their mother tongue (Taiwanese) rather than the acquired language (Mandarin) in 72.2% of seizures with verbalization. This finding is significant and contrary to a commonly held notion that the acquired language is used in seizures associated with speech behaviors.

Adolescent↗

PubMed1995

Intravenous immunoglobulin infusion in multifocal demyelinating motor neuropathy: a case report.

The following report is a case of multifocal demyelinating motor neuropathy (MMN) presenting as a gradual development of asymmetric motor weakness without sensory involvement. Electrophysiological studies showed mainly a conduction block with normal or slightly slow nerve conduction velocity. Cerebrospinal fluid (CSF) protein and serum protein electrophoresis were normal, but serum IgM anti-GM1 ganglioside antibody was elevated. The patient had a poor response to steroid, plasmapheresis and chemotherapy with cyclophosphamide, but significant improvement was noted after intravenous immunoglobulin (IVIG) infusion. MMN is a potentially treatable condition which clinically mimics a motor neuron disease; if treatment with steroid, plasmapheresis and cyclophosphamide have failed, IVIG may be effective.

Demyelinating Diseases↗

PubMed1995

Hypothalamic hamartoma and gelastic epilepsy: a case report.

We studied a 6-year-old girl who presented with inappropriate and uncontrollable laughing episodes since age 3. Physical examination revealed a precocious puberty. The luteinizing hormone-releasing hormone (LH-RH) stimulation test showed an increased level of follicle-stimulating hormone (FSH). The interictal electroencephalogram (EEG) was normal. Several laughing fits were documented during video/EEG monitoring. During laughing, the ictal EEG showed a diffuse suppression of background rhythm, prominent over the left mesial temporal region. A mass lesion about 2 x 2 cm in size was found over the suprasellar cistern with a broad base attached to the hypothalamus, which was isodense on a computed tomography (CT) scan, isointense to gray matter on T1-weighted magnetic resonance (MR) imaging and hyperintense on T2-weighted MR imaging. The findings were suggestive of a hypothalamic hamartoma. A variety of anticonvulsants had been used with little or no response to the frequency or duration of the laughing seizures.

Child↗

PubMed1995

Midbrain hemorrhage presenting as bilateral ptosis without hemiplegia: a case report.

A 66-year-old man suddenly developed bilateral ptosis after awaking from a nap. He did not experience nausea, vomiting or headache. In the emergency room, high blood pressure was noted. On examination, his consciousness was clear. Ptosis was present bilaterally and worse on the right side. The pupils promptly constricted to light. He could fully adduct his eyes during conjugate gaze movements, but convergence was impaired in the right eye. There was no diplopia or nystagmus. The assessment of the motor and sensory systems revealed no significant findings. Computed tomographic scanning and magnetic resonance imaging of the brain showed a small hematoma in the midbrain. Six months later, ptosis improved; however, the convergence deficit remained.

Blepharoptosis↗

PubMed1995

Startle epilepsy presenting as drop attacks: a case report.

A case of startle epilepsy, induced by an unexpected touch on the left shoulder of a 3.5 year old boy, was investigated. The startle epilepsy manifested as an atonic drop attack. Neurological examination revealed a mild hemiparesis on the left side. Computed tomography (CT) scanning demonstrated an enhancement over the right parieto-frontal region, suggesting a hemangioma. Interictal electroencephalography (EEG) showed diffuse slowing and asymmetry of background activities with lower amplitude over the right centro-parieto-temporal region. The ictal EEG showed a paroxysmal bilaterally synchronized high amplitude single spike followed by a few slow waves lasting about one second over the bilateral centro-parieto-temporal regions. The seizure resisted anticonvulsant therapy and no significant responses were observed despite the use of combined therapy with valproic acid, phenytoin, primidone and clonazepam.

Child, Preschool↗

PubMed1994

Masseter silent period: a study of magnetic stimulation.

We employed magnetic stimulation to study the masseter silent period (SP) in 16 healthy volunteers. Cutaneous perception threshold (CPT or 1 T) was determined. SP threshold was 30% M (maximal output) in each subject, equivalent to 1.5-3 T, and as intensity increased, SP durations prolonged. The correlation was higher with units of % M (r = 0.89) than CPT (r = 0.39). The recommended intensity was 60% M because of least variation of SP durations. Conclusively, magnetic stimulation is a new and painless method to study masseter SP. CPT is less effective in studying masseter SP with magnetic stimulation as the input effectiveness correlates best with % M rather than CPT.

Adult↗

PubMed1994

Purification and properties of beta-fructofuranosidase from Aspergillus oryzae ATCC 76080.

A fructooligosaccharide-producing beta-fructofuranosidase was purified from the crude extract of Aspergillus oryzae ATCC 76080 through successive steps of ultrafiltration, DEAE-Sepharose CL-6B ion-exchange chromatography, preparative isoelectric focusing electrophoresis and Sephacryl S-200 gel filtration. The purified enzyme had an optimal pH of 5-6, an optimal temperature of 50 degrees C, a Km value of 0.53 M for catalyzing selftransfer reaction from sucrose. The molecular weight was 87 kDa by gel filtration. Mercuric ion (0.25 mM), p-hydroxymercuribenzoate (0.25 mM) and N-bromosuccinimide (0.5 mM), significantly inhibited the enzyme activity. The enzyme showed both transfructosylation and hydrolytic action in 0.5 to 50% sucrose. The transfructosylation ratio increased as the sucrose concentration increased and it was 88.5% at 50% sucrose. The main fructooligosaccharides produced from sucrose were 1-kestose and nystose.

Aspergillus oryzae↗

PubMed1993

Peptide compositions of the cerebrovascular and senile plaque core amyloid deposits of Alzheimer's disease.

The pathological findings of Alzheimer's disease include amyloid deposition in cerebral blood vessels and in senile plaques. Both deposits are known to include peptides that contain a common sequence. Both forms of amyloid were isolated and their peptide compositions were determined. The peptides were resolved by size-exclusion chromatography in 70% formic acid, and reverse-phase chromatography in 60% formic acid, 0-40% acetonitrile. Senile plaque amyloid cores contain about 25% protein, about 70% of which is composed of peptides containing the beta-amyloid sequence. Amino-terminal sequencing of the core amyloid peptides (CAPs) revealed extensive amino-terminal heterogeneity, with variable amounts of blocked amino termini. Matrix-assisted, laser-desorption-time-of-flight mass spectrometry of the CAP mixture revealed an array of peptides the molecular weights of which corresponded to peptides beginning with each of the first 11 amino acids of the beta-peptide sequence and ending with Ala-42 of that sequence. The carboxyl-terminal residues were identified by tandem mass spectrometry of chymotrypsin digests. CAP possessed a minor degree of carboxyl-terminal heterogeneity. Cerebrovascular amyloid peptides (CVAPs) possessed minor degrees of both amino- and carboxyl-terminal heterogeneity. The major CVAP commenced at Asp-1 and ended at Val-40. Minor components of CAP possessed masses of 8000-9000 Da and the same amino-terminal residues as the major components of CAP. They may be precursors to the smaller CAPs. The differences in amino termini and carboxyl termini of CAPs and CVAPs suggest that the two types of amyloid form by different pathways, on which they encounter different proteases.

Alzheimer Disease↗

PubMed1993

Glucose metabolism in mammalian cells as determined by mass isotopomer analysis.

A method using 13C isotopes and GCMS/SIM was developed and was used to study glucose metabolism in several mammalian cell lines. Using [U-13C6]glucose, the 13C isotopomer distributions in glucose, lactic acid, glutamic acid, aspartic acid, and gamma-aminobutyric acid produced by the cells were determined, and glycolysis, gluconeogenesis, and the flux into the amino acid pools were calculated. A 1:1 mixture of [U-13C6]glucose and [1-13C]glucose was used to examine the loss of 1-13C carbon from [1-13C]glucose via the pentose monophosphate pathway in the cells; this new method measures the production of [3-13C]lactic acid and [U-13C3]lactic acid, and thus avoids most systematic errors that result from the endogenous production of 12C-lactic acid during metabolic conversion; in addition, glycolysis and the recycling of glucose and lactic acid can be examined at the same time. The mass isotopomer analysis method is reproducible and sensitive, and can be used to analyze metabolites in 10(-7) M concentration with less than 10(5) cultured human cells. This method was used to examine metabolic regulation of glucose in fibroblasts, lymphoblasts, and PC12 cells under various conditions of metabolic disturbance. The method appears to have wide applicability for the study of metabolic regulation of glucose and metabolic defects in cells.

Animals↗