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Biomedical subjects

D Han

Publications and source records attributed to D Han.

At least 109 records · Page 6Linked to original sources
PubMed1998

[Adenovirus-mediated p53 gene therapy of human laryngeal cancer].

OBJECTIVE: To explore the potential use of p53 in gene therapy for laryngeal cancer. METHODS: A human laryngeal cancer cell line Hep-2 was used. Recombinant cytomegalovirus-promoted adeno-viruses containing human wild-type p53 cDNA was transiently introduced into Hep-2 cells in vitro and injected into tumor nodules in vivo. The growth of Hep-2 cells in vitro and established s.c. squamous carcinoma nodules in nude mice was examined. RESULTS: The transduction efficiency of Hep-2 cell line was 100% at > or = 100 MOI. The p53 protein expression peaked on day 2 after infection and lasted far 5 days. Cell growth was greatly suppressed. In vivo studies, Ad5CMV-p53 transfestion in vitro inhibited tumorigenicity of Hep-2 cells in nude mice. Intra-tumoral injection of Ad5CMV-p53 significantly inhibited established s.c. implanted xenograft. CONCLUSION: Transfection of wild-type p53 gene via Ad5CMV-p53 is a potential approach to the therapy of laryngeal cancer.

Adenoviridae↗
PubMed1998

[CT diagnosis of the nose-eye-related disease].

The findings of paranasal and (or) orbital CT scannings of 283 cases who suffered from the nose-eye-related diseases were studied retrospectively in this paper. Of 283 cases, which were proved either by the operation or histopathology, 128 were neoplastic diseases, 120 were traumatic fractures, 23 inflammatory lesions and 12 fibrous dysplasia. The combined use of bony windows and soft tissue windows were the most effective methods of accurately detecting nose-eye-related disease. Meanwhile, vascular contrast were used for neoplastic lesions and some other diseases suspected of fungul nasal-sinusitis, mucocele or traumatic fracture so as to determine the degree and extent of the lesions. The results indicated that the bony destroy was the main diffusion way of the nasal, eye and cranial disease. The natural anatomic duct or openings often became the passage of inflammatory or neoplastic lesions from one organ to another. This study showed that CT scan can clearly demonstrate the degree and extent of the lesion of the nose-eye-related disease and the way of diffusion. The diagnosis of nose-eye-related disease should be established in the imaging analysis.

Adult↗
PubMed1998

[Effects of gentamicin on survival and neuritogenesis of cultured mouse spiral ganglion cells].

The effect of gentamicin on survival and neuritogenesis of cultured spiral ganglion cell(SGC) from NIH mouse 1-5 days after birth was observed. Different doses (25, 50 and 100 mg/L) of gentamicin were add to the medium of SGC, and cultured for 14 days. After that, the specimen was fixed with 4% paraformaldehyde and stained with toluidine blue. The amount of survival SGC was counted, and the length of neurite was measured with micrometer under microscope. It was shown that the survival and length of neurite of SGC had no difference between Gentamicin treated groups and control groups, and there were also no difference among 3 gentamicin treated groups. It was suggested that gentamicin had no effect on survival and neuritogenesis of SGC. The effects of aminoglycoside antibiotics on SGC were probably secondary to the injury of Corti's Organ.

Animals↗
PubMed1998

[A study on EEG-Encephalofluctuographic characteristics in alpha frequency band in pilots].

The frequency-fluctuation characteristics in alpha frequency band were studied by EEG-Encephalofluctuographic Technology (EEG-ET) in 261 pilots. The electrical activity was recorded from 12 scalp monopolar leads of the international 10-20 system using linked ear lobes as reference. The components of the competitive frequency-fluctuation structure in alpha frequency band was analysed. The results showed that the predominant frequency component of the competitive structure was 9 Hz in the 261 normal healthy pilots. The second was 10 Hz. And the third was 7 Hz. The other competitive frequency components were inhibited. The relative entropy value (percentage) of the competivity structure was calculated for each EEG derivation of each pilot. We also analysed the spectra of the EEG-Encephalofluctuograph. We found that there was a dominant power peak at 21.39mHz in 57 pilots who complained in-flight blackout sometimes during acceleration.

Acceleration↗
PubMed1998

[Ergonomical study on Chinese speech warning].

Ergonomical experiments on speech warning under noise background were carried out in 40 healthy males, aged 20-33. Through the determination of auditory reaction time to the Chinese speech warning under dual-tasks and the subjective evalution of the suitable time length of main warning voice by the subject, the optimum parameters of Chinese speech warning in accordance with space ergonomics were determined. It was found that: suitable time length of main warning voice is 0.35-0.55s, main interval is 0.15-0.35s, speech speed is 4-6 word/s, and sentence interval is 0.2-0.4s. Meanwhile, the analysis of heart rate (HR) and heart rate variability (HRV) demonstrated that the speech warning using aforementioned parameters didn't increase the operator's work load. The results can serve as the objective ergonomical basis and the evaluation criterion for design of speech warning in manned space vehicle.

Adult↗
PubMed1998

[Psychological study of parameter selection for Chinese speech warning].

To study the effects of the parameters of Chinese speech warning on cognitive property, and to obtain the optimal parameters in accordance with cognitive property, experiments of cognitive property for Chinese speech warning was carried out in 20 healthy males. Combining our study on the sensation-reaction time, the optimal parameters in accordance with space ergonomics [correction of ergonormics] and cognitive property were determined: suitable time length of prewarning sound is 0.35 approximately 0.55 s; prewarning interval is 0.3-0.4 s; interval between sentences is 0.3-0.4 s; word number of warning sentence < or = 7. The result can serve as the objective ergonomical basis for the design of Chinese speech warning system in manned space vehicle, and as the evaluation criterion.

Adult↗
PubMed1998

[Lysozyme and lactoferrin in human uncinate process mucosa during chronic sinusitis].

OBJECTIVE: To study the local protective role of lysozyme(LZ) and lactoferrin(LF) in the uncinate process mucosa during chronic sinusitis. METHODS: Expression of LZ and LF was determined in 17 samples from normal subjects and 70 samples from chronic sinusitis patients with ABC immunohistochemical method. According to the presence or absence of nasal polyps, patients were divided into two groups. RESULTS: Serous cells of submucosal glands displayed a strongly positive staining reaction to both LZ and LF in the normal uncinate process mucosa and mucosa from patients with chronic sinusitis. A positive though weak staining for LZ could also be found frequently within mucous cells of submucosal mixed glands and occasionally within goblet cells. In the mucosa from patients without nasal polyps, the staining reaction to LZ appeared to be intensified in goblet cells when compared with normal controls (P < 0.05). In patients with nasal polyps, the staining reaction to LZ appeared to be intensified in submucosal glands when compared with normal controls (P < 0.01) and patients without nasal polyps (P < 0.05). For LF, the staining reaction from patients with nasal polyps was stronger than that in normal controls (P < 0.01). The epithial cells stained negatively for LZ and LF. CONCLUSIONS: It suggests that the observed increase in LZ and LF secreting activity of goblet cells and submucosal mixed glands may play a part role in the defense mechanism of uncinate process mucosa during the course of chronic sinusitis.

Adolescent↗
PubMed1998

[Relationship between anatomic variations of nasal sinus and chronic sinusitis].

OBJECTIVE: To understand the etiology of chronic sinusitis. METHODS: Ninety-one coronal CT scans of chronic sinusitis were analysed with mutimedia software developed by the authors. Sinus CT images were scanned into multimedia computer and the subtle anatomic structures such as pneumatization of the middle turbinate, agger nasi cell, Haller's cell, septal deformity, maxillary sinus hypoplasia, abnormality of uncinate process and ethmoid bulla and so on were measured. The results were analysed by the statistical software SPSS. RESULTS: The penumatization rate of total or inferior part of middle turbinate correlated positively to the inflammation of anterior ethmoid and maxillary sinuses. Compared with patients with normal frontal sinuses, the vertical diameters of agger nasi cells of patients with frontal sinusitis were larger(11.70 +/- 5.50 mm and 8.54 +/- 3.67 mm respectively, P < 0.01). Compared with patients with normal maxillary sinuses, the Haller's cells of patients with maxillary sinusitis were larger (77.8% and 33.3%, P < 0.05) and the amount of inflammatory Haller's cells of the latter was more abundant than that of the former(91.6 +/- 17.8 mm2 and 41.6 +/- 12.6 mm2, respectively, P < 0.05). The deviation of uncinate process was one of the factors of maxillary sinusitis. The sizes of ethmoid bullae increased with the soft tissue thickening in anterior ethmoid sinus, the large ethmoid bulla may cause anterior ethmoid sinusitis. CONCLUSION: Some anatomic variations may play a role in chronic sinusitis.

Adolescent↗
PubMed1998

[Effect of basic fibroblast growth factor on cultured spiral ganglion cells following glutamate treatment].

OBJECTIVE: To understand the effects of basic fibroblast growth factor (bFGF) on survival and neurogenesis of the cultured spiral ganglion cell (SGC) of mouse after exposed to glutamate, and the effects of hFGF and glutamate on free intracellular calcium ion concentration. METHODS: After exposed to 2 x 10(-2) mol/L glutamate for 2 hours, the medium of SGC was replaced with the media containing 25, 50, 100 micrograms/L bFGF. Medium without bFGF was used as control. RESULTS: Twenty-four hours later, more cells in the control group showed signs of cell death than in bFGF groups. After 14 days, specimens were fixed in 4% paraformaldehyde and stained with toluidine blue. It was shown that the SGC in medium with bFGF exhibited more survival and longer neurites, and the effect was dose dependent (P < 0.01). Application of glutamate to the medium induced an increase to the the free intracellular calcium ion concentration in SGC, but bFGF had no such effect. CONCLUSION: Glutamate excitotoxicity was associated with free intracellular calcium ion concentration elevation in SGC, and bFGF could protect SGC against glutamate neurotoxicity.

Animals↗
PubMed1998

[Endoscopic nasal surgery in treatment of nasopharyngeal angiofibroma].

OBJECTIVE: To avoid complications of the routine surgeries for nasopharyngeal angiofibroma. METHODS: Endoscopic nasal surgery and other new techniques including controlled-hypotension anesthesia and preoperative feeding artery embolism had been used. From April 1996 to September 1997 eight young male patients with diagnosis of nasopharyngeal angiofibroma were treated by endoscopic sinus surgery. The average age was 16.6 years old. Six accepted preoperative embolism, seven accepted hypotension anesthesia. RESULTS: No complications had occurred. Average intraoperative blood loss was 900 ml. All cases were followed for 1 to 20 months(mean 8 months). Recurrence was found in only one patient three months after operation. The recurrent rate was 12.5%. CONCLUSION: The lesions limited to nasal and nasopharyngeal cavities and with sphnoid and ethmoid invasions can be removed by endoscopic nasal surgery. Endoscopic surgery has advantages in reducing complications and obtaining better post operative functions. Transnasal endoscopic examination is also necessary in the follow-up period. Other techniques such as CT, digital subtract angiography, preoperative feeding artery embolism and controlled-hypotension technique during anesthesia are beneficial.

Adolescent↗
PubMed1998

The CVC removal distress syndrome: an unappreciated complication of central venous catheter removal.

The removal of a central venous catheter (CVC) can be complicated by rare but potentially life-threatening neurocardiopulmonary distress. The clinical courses of eight patients who had CVC removal complications are reviewed. Seven patients had catheter removal from the right internal jugular vein, and one from the right subclavian vein. The complications occurred after complete removal of the catheter (four patients), after guidewire replacement for catheter change (three patients), and after detachment of the hemostasis side port of the Swan introducer during sheath removal (one patient). Each of them had more than one complication. The major complications were: neurologic paresis or coma (four patients), respiratory failure (four patients), and shock (two patients). One patient died of pulmonary sepsis. The overall mortality rate was 12.5 per cent. Guidelines for safe removal of central venous catheters are proposed. Possible mechanisms of the complications are discussed. We refer to the observed complications as the CVC removal distress syndrome.

Adult↗
PubMed1997

Lipoic acid increases de novo synthesis of cellular glutathione by improving cystine utilization.

Lipoic acid (thiotic acid) is being used as a dietary supplement, and as a therapeutic agent, and is reported to have beneficial effects in disorders associated with oxidative stress, but its mechanism of action remains unclear. We present evidence that lipoic acid induces a substantial increase in cellular reduced glutathione in cultured human Jurkat T cells human erythrocytes, C6 glial cells, NB41A3 neuroblastoma cells, and peripheral blood lymphocytes. The effect depends on metabolic reduction of lipoic acid to dihydrolipoic acid. Dihydrolipoic acid is released into the culture medium where it reduces cystine. Cysteine thus formed is readily taken up by the neutral amino acid transport system and utilized for glutathione synthesis. By this mechanism lipoic acid enables cystine to bypass the xc- transport system, which is weakly expressed in lymphocytes and inhibited by glutamate. Thereby lipoic acid enables the key enzyme of glutathione synthesis, gamma-glutamylcysteine synthetase, which is regulated by uptake-limited cysteine supply, to work at optimum conditions. Flow cytometric analysis of freshly prepared human peripheral blood lymphocytes, using monobromobimane labeling of cellular thiols, reveals that lipoic acid acts mainly to normalize a subpopulation of cells severely compromised in thiol status rather than to increase thiol content beyond physiological levels. Hence lipoic acid may have clinical relevance in restoration of severely glutathione deficient cells.

Animals↗
PubMed1997

Ventilation inhomogeneities and mixed venous blood N2 in multibreath N2 washout.

The single path model of airway gas transport, with and without a distributed blood source term, was used to simulate multiple-breath N2 washout by breathing pure O2 in two lung models: a single-region lung model (SRLM) which produces series inhomogeneity, and a seven-region lung model (7RLM) incorporating both series and parallel inhomogeneities. Normalized phase III slopes (Sn) from N2 expirograms were computed for each breath and compared with published human experimental data obtained under similar conditions. The 7RLM predicts well the trend of experimental Sn N2 changes and is superior to the SRLM in the first part (the unsteady state), implying that this part of the curve is mostly due to convective mixing of the seven parallel flow streams. In the quasi-steady state, the 7RLM is not obviously superior to the SRLM. Functional residual capacity and pulmonary perfusion are shown to strongly affect the number of breaths required to reach the quasi-steady state. The anatomical dimensions that appear to be critical in SRLM are not as important in the 7RLM.

Computer Simulation↗
PubMed1997

Cytosolic and mitochondrial systems for NADH- and NADPH-dependent reduction of alpha-lipoic acid.

In cellular, tissue, and organismal systems, exogenously supplied alpha-lipoic acid (thioctic acid) has a variety of significant effects, including direct radical scavenging, redox modulation of cell metabolism, and potential to inhibit oxidatively-induced injury. Because reduction of lipoate to dihydrolipoate is a crucial step in many of these processes, we investigated mechanisms of its reduction. The mitochondrial NADH-dependent dihydrolipoamide dehydrogenase exhibits a marked preference for R(+)-lipoate, whereas NADPH-dependent glutathione reductase shows slightly greater activity toward the S(-)-lipoate stereoisomer. Rat liver mitochondria also reduced exogenous lipoic acid. The rate of reduction was stimulated by substrates which increased the NADH content of the mitochondria, and was inhibited by methoxyindole-2-carboxylic acid, a dihydrolipoamide dehydrogenase inhibitor. In rat liver cytosol, NADPH-dependent reduction was greater than NADH, and lipoate reduction was inhibited by glutathione disulfide. In rat heart, kidney, and brain whole cell-soluble fractions, NADH contributed more to reduction (70-90%) than NADPH, whereas with liver, NADH and NADPH were about equally active. An intact organ, the isolated perfused rat heart, reduced R-lipoate six to eight times more rapidly than S-lipoate, consistent with high mitochondrial dihydrolipoamide dehydrogenase activity and results with isolated cardiac mitochondria. On the other hand, erythrocytes, which lack mitochondria, somewhat more actively reduced S- than R-lipoate. These results demonstrate differing stereospecific reduction by intact cells and tissues. Thus, mechanisms of reduction of alpha-lipoate are highly tissue-specific and effects of exogenously supplied alpha-lipoate are determined by tissue glutathione reductase and dihydrolipoamide dehydrogenase activity.

Animals↗
PubMed1997

Regulation of cellular thiols in human lymphocytes by alpha-lipoic acid: a flow cytometric analysis.

Modulation of cellular thiols is an effective therapeutic strategy, particularly in the treatment of AIDS. Lipoic acid, a metabolic antioxidant, functions as a redox modulator and has proven clinically beneficial effects. It is also used as a dietary supplement. We utilized the specific capabilities of N-ethylmaleimide to block total cellular thiols, phenylarsine oxide to block vicinal dithiols, and buthionine sulfoximine to deplete cellular GSH to flow cytometrically investigate how these thiol pools are influenced by exogenous lipoate treatment. Low concentrations of lipoate and its analogue lipoamide increased Jurkat cell GSH in a dose-dependent manner between 10 (25 microM for lipoamide) to 100 microM. This was also observed in mitogenically stimulated peripheral blood lymphocytes (PBL). Studies with Jurkat cells and its Wurzburg subclone showed that lipoate dependent increase in cellular GSH was similar in CD4+ and - cells. Chronic (16 week) exposure of cells to lipoate resulted in further increase of total cellular thiols, vicinal dithiols, and GSH. High concentration (2 and 5 mM) of lipoate exhibited cell shrinkage, thiol depletion, and DNA fragmentation effects. Based on similar effects of octanoic acid, the cytotoxic effects of lipoate at high concentration could be attributed to its fatty acid structure. In certain diseases such as AIDS and cancer, elevated plasma glutamate lowers cellular GSH by inhibiting cystine uptake. Low concentrations of lipoate and lipoamide were able to bypass the adverse effect of elevated extracellular glutamate. A heterogeneity in the thiol status of PBL was observed. Lipoate, lipoamide, or N-acetylcysteine corrected the deficient thiol status of cell subpopulations. Hence, the favorable effects of low concentrations of lipoate treatment appears clinically relevant.

Acetylcysteine↗
PubMed1997

Zatebradine slows ectopic ventricular rhythms in canine heart 24 hours after coronary artery ligation.

Arrhythmias occur 24 h after occlusion of the left anterior descending (LAD) coronary artery in the canine heart and have been attributed to the abnormal spontaneous activity in subendocardial Purkinje fibers, which are markedly depolarized. The major current underlying normal automaticity in these fibers is i(f). Although the i(f) activation range is generally considered to be more negative than the diastolic membrane potential in these depolarized fibers in infarcts, this activation range has been shown to shift in a positive direction in response to hormonal influences. Thus i(f) could still mediate automaticity in these fibers in infarcts. Furthermore, recent reports indicate that a depolarizing diastolic current, probably i(f), also can be measured in ventricular muscle during abnormal experimental conditions, which may occur during ischemia. To test whether there is a role of i(f) currents in sustaining ventricular ectopy, we administered the selective i(f) channel blocker, zatebradine, 24 h after LAD ligation in canine hearts. We report that intravenous injections of zatebradine (0.25 or 1.0 mg/kg) significantly slow ventricular rhythms (with average reductions of 19 or 26%, respectively). Moreover, because zatebradine also slows sinus nodal rate, it can lead to an increased incidence of ectopic beats. However, during right atrial pacing, when sinus slowing has no effect on ventricular rhythms, capture of ventricular rhythms occurs at lower rates in the presence of zatebradine. The reduction of capture threshold is comparable to the reduction in the rate of the ectopic rhythm. Thus zatebradine eliminated the arrhythmia when the right atrium was paced at the original sinus rate.

Animals↗
PubMed1997

Neurotransmitter modulation of gap junctional communication in the rat hippocampus.

Increasing experimental evidence indicates that gap junctions can be modulated by neurotransmitters, in particular dopamine. To examine possible modulation of gap junctional communication in the rat hippocampus by neurotransmitters, we studied dye coupling and electrotonic transmission in the CA1 area in the presence of carbachol, a cholinergic agonist, and dopamine agonists. Carbachol markedly reduced dye coupling and the frequency of electrotonic potentials (spikelets). Spikelet amplitudes were decreased in the presence of carbachol. These effects were reversed by the cholinergic antagonist atropine, suggesting a muscarinic action of carbachol on gap junctional function. The non-specific dopamine agonist apomorphine, and the specific D1 receptor agonist SKF 38393, reduced dye coupling between pyramidal cells. Spikelet frequency was also decreased in the presence of dopamine agonists, but less than with carbachol. The specific D1 receptor antagonist, SCH 23390, reversed the effects of both dopamine agonists. These observations indicate that cholinergic and dopaminergic transmission can affect electrical and chemical (dye coupling) communication through gap junctions, and could therefore alter properties of neuronal assemblies, in addition to their effects on intrinsic membrane properties.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗