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Biomedical subjects

Y C Guo

Publications and source records attributed to Y C Guo.

18 recordsLinked to original sources
PubMed2001

Antiepileptic drug withdrawal in patients with temporal lobe epilepsy undergoing presurgical video-EEG monitoring.

PURPOSE: To investigate antiepileptic drug (AED) withdrawal during video-EEG monitoring in adult patients with temporal lobe epilepsy (TLE). METHODS: Between 1995 and 1997, 102 consecutive patients with refractory TLE were admitted to the epilepsy monitoring unit for presurgical evaluation. Patients were monitored with ongoing AEDs being rapidly decreased and discontinued in 4-6 days. The monitoring was continued until sufficient numbers of seizures were recorded. Serum AED levels were checked at admission and after the first complex partial seizure (CPS). RESULTS: In all, 89 patients had 429 CPSs (mean, 4.8 per patient), including 156 (36.4%) secondarily generalized. A mean of 153.8 h (16-451 h) was required for completing the monitoring in each patient. Forty-three (48.3%) patients experienced seizure clusters, and eight (9.0%) had generalized seizures that had never occurred or had been absent for years. However, none evolved to status epilepticus. Carbamazepine was the most commonly used AED in 71.9% of patients, followed by valproate and phenytoin. When the first CPS occurred, mean 77.2 h since the beginning of the monitoring, serum levels of these three AEDs were mostly subtherapeutic rather than minimal. CONCLUSIONS: Acute AED withdrawal effectively provoked seizures in TLE patients undergoing presurgical video-EEG monitoring. However, nearly 50% of patients had seizure clusters or secondarily generalized seizures. Serum AED levels were mostly subtherapeutic when the first CPS occurred.

Adolescent↗
PubMed2001

Lateralizing value of early head turning and ictal dystonia in temporal lobe seizures: a video-EEG study.

To investigate early head turning, we retrospectively studied videotapes of 262 seizures from 82 patients who were seizure free after temporal lobectomy. Early head movements were arbitrarily classified into non-tonic turning, tonic turning, and absence of turning. Among the 222 seizures which showed early head turning, 168 (75.7%) had non-tonic turning and 54 (24.3%) had tonic turning. The direction of the first head turning was ipsilateral to the epileptogenic foci in 132 (78.6%) seizures with non-tonic turning and in 35 (64.8%) seizures showing tonic head turning. The proportion of seizures with turning towards the ipsilateral side in the presence of tonic and non-tonic head turning were significantly different (P= 0.04). Seventy-four seizures (28.2%) evolved to secondary generalization, more frequently found in seizures with early head turning (P= 0.0015) and especially those showing tonic turning (P< 0.0001). The direction of head turning immediately preceding secondary generalization was contralateral to the lesion side in 53 seizures (82.8%). Dystonic upper limb posturing occurred in 86 seizures (32.8%), exclusively contralateral to the seizure focus, whereas 65 (75.6%) were associated with initial head turning ipsilateral to the focus. In summary, temporal lobe seizures with tonic head turning tends to secondarily generalize and the direction of head turning before secondarily generalized was contralateral to the seizure foci. Earlier in the seizures the direction of non-tonic head turning tends to be towards the epileptogenic hemisphere. In addition, dystonic posturing of the extremities is a significant lateralizing sign to the contralateral hemisphere in temporal lobe seizures.

Adult↗
PubMed2001

Single-pulse transcranial magnetic stimulation reset the rhythm of essential tremor but not heart beat.

BACKGROUND: Human oscillator is observed in and outside the nervous system. Cardiac rhythm is generated by heart itself but can be modulated by brain. Using the technique of transcranial magnetic stimulation (TMS) and resetting index, we studied if single-pulse TMS could reset the cardiac rhythm and help differentiate oscillator of neurogenic or non-neurogenic origin. METHODS: In addition to the study of 4 patients with essential tremor, cardiac rhythm was studied in 6 normal subjects. The magnetic intensity was initiated from motor threshold of hand muscle, and then with an increment of 10% up to the maximal output of magnetic stimulator. We used the resetting index (RI) to quantify the influence of the TMS. RESULTS: The resetting phenomenon was observed in essential tremor (RI = 0.92) but not in cardiac rhythm (RI = 0.02). CONCLUSIONS: Single-pulse TMS is able to reset the rhythm of essential tremor but not heart beat. The pacing mechanism is different between essential tremor and heart beat. The cardiac rhythm is regulated and modulated chiefly by heart itself. Essential tremor should not share the same mechanism with heart beat.

Adult↗
PubMed2000

A double-blind, placebo-controlled study of topiramate in adult patients with refractory partial epilepsy.

PURPOSE: The efficacy and safety of topiramate (TPM) as adjunctive therapy in the treatment of adult Chinese patients with refractory partial epilepsy were investigated in a randomized, double-blind, placebo-controlled study. METHODS: A total of 46 patients who had four or more complex partial seizures with or without secondary generalization within an 8-week baseline phase were enrolled. Patients were assigned randomly to receive TPM (n = 23) or placebo (n = 23). TPM or placebo was titrated to target doses of 300 mg/d for 6 weeks and maintained at stabilized levels for another 8 weeks. Concomitant antiepileptic drugs remained at constant previous levels during the trial. RESULTS: In all, 41 patients completed the trial (TPM group, n = 20; placebo group, n = 21). The proportion of patients with a > or =50% reduction from baseline in complex partial seizures was 11 of 23 (47.8%) in the TPM group and 3 of 23 (13.0%) in the placebo group (p = 0.01). In addition, patients treated with TPM had significantly better investigator (p = 0.014) and patient (p = 0.0005) global assessment scores than patients in the placebo group. Adverse events were mostly mild and transient, with no significant differences between treatment groups. Two patients with TPM therapy complained of weight loss. Routine blood cell counts and other laboratory results showed no significant changes from baseline in either treatment group. CONCLUSIONS: TPM 300 mg/d is effective and well tolerated as treatment for refractory partial epilepsy in adults.

Adolescent↗
PubMed1996

Experimental study on microthrombi and myocardial injuries.

The experiment was conducted with SD male rats. After they had been each given an intravenous injection of high molecular weight dextran (0.8 ml/100 g body wt) once a day for 4 days, they were brought under the observation of ECG and mesentery microcirculation. Microthrombi were found in the venules and capillaries of each rat of the experimental group, while in the microcirculation of the control group rats, no microthrombi were found. No changes were found in the ECGs of the rats (n = 6) in the control group after the injections, while the rats in the subject group all suffered a rise in the S-T segment of ECG, an indication of myocardial injuries. The rise was significantly in positive correlation to the increase in microthrombi in number (r = 0.944, P < 0.01). The erythrocytes of the rats in the subject group clustered to become rouleau-like, and platelets aggregated by tens and hundreds to form microthrombi. Their blood also showed a significant decrease in number of platelets. The degree of platelet aggregation and the scores of the rise on ECG were significantly in positive correlation as shown by the results: y = 20 + 94x, r = 0.94, P < 0.01. The plasma TXB2 of the subject group increased obviously but the change of 6-K-PGF1 alpha in the blood was not significant. The content of plasma TXB2 and the scores that indicated the rise in the S-T segment of the ECG showed significantly a positive correlation by the analysis of linear regression equation: y = 109.997 +/- 116.25x, r = 0.889, P < 0.05. The activity of Na(+)-K(+)-ATPase on the myocardial cell membranes of the rats with microthrombi was significantly reduced as compared with that of the rats in the control group (P < 0.01). The activity of the Na(+)-K(+)-ATPase was significantly in negative correlation to the rise in the S-T segment of ECG (P < 0.05). This study demonstrates that the above changes are the causes of myocardial injuries in rats with circulatory thrombi.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Visualization method for fingerprints on skin by impression on a polyethylene terephthalate (PET) semirigid sheet.

Based on the phenomenon that static electricity attracts dust, a polyethylene terephthalate (PET) semirigid sheet coated with printing ink was used to visualize impressions of fingerprints on the skin of living and dead bodies. Compared with visualization methods for perspiration fingerprints, this method recovers better images for a longer time after the fingerprint has been deposited on skin. Fingerprints transferred to the PET sheet are photographed with sidelighting using an ordinary light source. For fingerprints that yield inadequate contrast, an argon-ion laser can be used to improve the contrast.

Dermatoglyphics↗
PubMed1991

Epiglottic laryngoplasty after hemilaryngectomy for glottic cancer.

Epiglottic laryngoplasty is technically feasible as a one-stage procedure with excellent functional results. Although the Kambic-Sedlacek-Tucker (K-S-T) technique of glottic reconstruction offers early extubation with an adequate airway, a subsequent wide neoglottis may increase the chance of aspiration and a poor voice. To better restore the laryngeal functions of closure and phonation, we made some modifications on the original K-S-T technique as follows: (1) One of the lateral margins of the epiglottis with the aryepiglottic fold is sutured to the arytenoid region of the cricoid rather than a thyroid cartilage remnant. A neo-arytenoid is formed. (2) The other lateral margin of the epiglottis with the aryepiglottic fold is sutured to the cut edge of the false and true cord instead of a thyroid ala remnant. Therefore both margins of the epiglottis with the aryepiglottic folds are lowered as much as possible to the level of the glottis. A new pseudocord is formed. (3) A cartilage cut is made at the anterior aspect of the epiglottis, leaving its laryngeal surface of mucoperichondrial intact. A new anterior commissure with a sharp angle is shaped by this maneuver. Nineteen hemilaryngectomies with modified epiglottic laryngoplasty have been performed by members of the Department of Otolaryngology of Guangxi Medical College since 1984. Results in this series are fairly good and indicate that the modified epiglottic laryngoplasty is effective in enhancing functional results in terms of respiration, deglutition, and phonation.

Aged↗
PubMed1991

The effects of Escherichia coli and its endotoxin on amyloidogenesis in ducks.

To compare the effects of two inocula on the induction of amyloidosis in normal and thymectomized ducks, 180 normal and 50 thymectomized ducks were injected intravenously weekly for up to 16 weeks with either crude endotoxin or crude whole cell extract of a virulent strain of Escherichia coli (O78), and another 60 ducks were injected with normal saline as study control. During the first 5 weekly injections, the initial doses of inducing agents were the smallest and then adjusted upward to the maximum study doses (1 or 2 mg/bird of crude endotoxin and 15-18 x 10(8) bacteria/bird of crude whole cell extract), which were then maintained over the course of the study. The incidence of amyloid deposition were: 50.00% (25/50) for thymectomized ducks that received 1 mg/bird/week of crude endotoxin, 61.67% (37/60) for intact ducks that received 15 x 10(8)-18 x 10(8) bacteria (crude whole cell extract)/bird/week, 53.33% (32/60) for intact ducks received 2 mg/bird/week of crude endotoxin, and 63.33% (38/60) for intact ducks received 1 mg/bird/week of crude endotoxin. The results suggest that crude whole cell extract and crude endotoxin induced amyloidosis in ducks at similar rates and that, in ducks, thymectomy has no appreciable effect on the occurrence of amyloidosis.

Amyloidosis↗
PubMed1991

[Syntheses of 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-[(4-P-nitrobenzol)-1- piperazinyl] quinoline-3-carboxylic acid and its analogues].

Syntheses of thirteen new compounds of 1-ethyl-6-flouro-1, 4-dihydro-4-oxo-7-[(4-p-nitrobenzoyl)1-piperazinyl] quinoline-3-carboxylic acid and its analogues are reported. The structures were determined by IR, 1HNMR and elemental analysis. Four compounds have been subjected to antibacterial activity tests in vitro. Compound I1 was shown to have significant activity.

Anti-Infective Agents↗
PubMed1990

[Improved argon laser photodynamic therapy for superficial bladder tumor--experimental research and clinical analysis].

The killing effects of 514.5 nm argon laser and 630 nm dye laser radiation on the murine SP2/0 myeloma cells cultured in thin layer containing HPD were measured by clonogenic assay. It was found that the former was 3.34 fold higher than the latter. Improved argon laser photodynamic therapy was used in the treatment of 104 superficial bladder tumors in 40 patients. Firstly, high output (6-7 W/cm2) argon laser contact and interstitial radiation were used to eradicate visible tumors, and then cylindrical optic fiber was used to deliver argon laser (2.1-3.47 W/cm2) for whole bladder mucosal scattered irradiation to destroy small multi-focal tumors and reduce recurrence. In this series, the follow-up was 7-34 months. All patients achieved complete response and only 7 (17.5%) recurred.

Adult↗
PubMed1990

[Auditory brainstem response in the aged and elderly].

Auditory brainstem response(ABR) was studied in 63 old healthy individuals (mean age = 66.42 +/- 9.88 years). They presented some degree of hearing loss (pure tone hearing threshold for 4 frequencies less than or equal to 30dB HL). Meanwhile 24 younger subjects (half for each sex, mean age = 17.61 +/- 2.63 years) with normal hearing were chosen as the control group. It was found that (a) the older group had greater mean values for both absolute peak latencies and inter-peak latencies than the younger group. The results indicate that age-related hearing loss is due to cochlear pathology but do not exclude the possibility of central auditory involvement. (b) the main parameters of ABR in both ears for each individual were quite symmetric. This fact implicates the diagnostic significance in differentiating presbycusis and space occupying lesion in the brainstem. (c) sex also affected the ABR in both age groups. Males were easier to be affected than females.

Aged↗
PubMed1989

The disaccharide composition of heparins and heparan sulfates.

Heparin and heparan sulfate can be cleaved selectively at their N-sulfated glucosamine residues by direct treatment with nitrous acid at pH 1.5. These polymers can also be cleaved selectively at their N-acetylated glucosamine residues by first N-deacetylating with hydrazine and then treating the products with nitrous acid at pH 4. These procedures have been combined and optimized for the conversion of these glycosaminoglycan chains into their disaccharide units. A modified hydrazinolysis procedure in which the glycosaminoglycans were heated with hydrazine:water (70:30) containing 1% hydrazine sulfate gave rapid rates of N-deacetylation and minimal conversion of the uronic acid residues to their hydrazide derivatives. Under these conditions, N-deacetylation was complete in 4 h and the beta-eliminative cleavage of the polymer chains that occurs during hydrazinolysis (P. N. Shaklee and H. E. Conrad (1984) Biochem. J. 217, 187-197) was eliminated. Treatment of the N-deacetylated polymer with nitrous acid at pH 3 for 15 h at 25 degrees C then gave simultaneous cleavage at the N-unsubstituted glucosamine residues and the N-sulfated glucosamine residues. These deamination conditions minimized, but did not eliminate, the side reaction in which nitrous acid-reactive glucosamine residues undergo ring contraction without glucosaminide bond cleavage. Thus, the disaccharides were obtained in a yield of 90% of those originally present in the glycosaminoglycan chains. Since the ring contraction side reaction occurs randomly at the diazotized glucosamine residues, the disaccharides formed in the pH 3 nitrous acid reaction were recovered in proportions equal to those in the original glycosaminoglycan chain.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, Gel↗
PubMed1989

Prognostic implications of nuclear DNA content in head and neck cancer.

The nuclear DNA content was measured in formalin-fixed and deparaffined specimens of 296 oral, pharyngeal, and laryngeal squamous cell carcinomas from patients in whom the clinical outcome was known. One hundred ninety (64%) contained cells with abnormal DNA (DNA aneuploid or tetra/polypoid). Only 32% (60 of 190) of the patients with DNA nondiploid cancers survived 5 years, compared with 49% (52 of 106) of the patients with DNA diploid cancers. When the findings were controlled for clinical stage, patients whose tumors were DNA diploid had a survival advantage at each stage. Histologic grading showed less correlation, because only patients with well-differentiated carcinomas had a survival advantage if their tumors were DNA diploid. These data showed that determination of DNA content in cancers of the head and neck can offer prognostic information not provided by other means and enhance the diagnosis of cancer.

Adult↗
PubMed1988

Analysis of oligosaccharides from heparin by reversed-phase ion-pairing high-performance liquid chromatography.

An ion-pairing high-pressure liquid chromatography procedure was developed for analysis of mixtures of oligosaccharides generated by nitrous acid cleavage of heparin. Oligosaccharides were eluted from a Hi-Chrom 5S ODS (C18) column using mixtures of acetonitrile and buffers containing 40 mM ammonium phosphate and 1 mM tetrabutylammonium phosphate. Isocratic conditions were developed for optimal separation of a number of individual disaccharides and tetrasaccharides that were characterized previously (M.J. Bienkowski and H.E. Conrad (1985) J. Biol. Chem. 260, 356-365). These isocratic conditions were then coupled to obtain gradient elution conditions for the ion-pairing separations of mixtures of disaccharides and mixtures of tetrasaccharides. A comparison of the elution profiles obtained in the ion-pairing chromatography procedure with profiles obtained by anion-exchange high-pressure liquid chromatography profiles showed markedly better overall resolution by the ion-pairing procedure. As a result of this improved resolution, the new procedure showed the presence of previously unidentified products in the heparin oligosaccharide mixtures.

Chromatography, High Pressure Liquid↗