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Biomedical subjects

H Dai

Publications and source records attributed to H Dai.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Influence of pavulon on facial nerve monitoring during middle ear-mastoid operation].

OBJECTIVE: To evaluate the influence of pavulon (muscle relaxant) on facial nerve monitoring for patient with middle ear-mastoid operation during general anesthesia. METHOD: Intraoperative monitoring of the facial nerve (FNM) was done in 45 ears (44 case). For patient with middle ear-mastoid disease, 38 ears underwent inhaled-intravenous anesthesia with muscle relaxant pavulon (group of general anesthesia), 7 ears underwent local anesthesia (group of local anesthesia). Accelography (ACCG) was used in 10 case for testing the correlation between of FNM and the various degree of recovery from ulnar nerve-musculor blockade. RESULT: FNM could be elicited during different periods of recovery with values of T4/T1 varying from 10%-98%. Pavulon could be used to eliminate muscular vibration from disturbing FNM. Electromyography (EMG) potentials were successfully recorded in 34 ears (89.4%). Anesthesia was uneventful and it may be controled satisfactority. CONCLUSION: Considering the advantage of pavulon. It can be used for general anesthesia during intraoperative monitoring of the facial nerve for children or adults suffering from local complicated diseases.

Adolescent↗
PubMed1998

Fullerene pipes

Single-wall fullerene nanotubes were converted from nearly endless, highly tangled ropes into short, open-ended pipes that behave as individual macromolecules. Raw nanotube material was purified in large batches, and the ropes were cut into 100- to 300-nanometer lengths. The resulting pieces formed a stable colloidal suspension in water with the help of surfactants. These suspensions permit a variety of manipulations, such as sorting by length, derivatization, and tethering to gold surfaces.

Journal Article↗
PubMed1998

Effects of dizocilpine (MK-801) on motor activity and memory.

The effects of MK-801 upon motor activity and memory were assessed in a novel use of open-field behavior testing. In this study, rats were treated with different doses of MK-801 (0.025, 0.05, 0.1 and 0.2 mg/kg) and given a brief 10-min exposure to an open-field in which locomotor activity and within-session habituation were measured. Doses of MK-801 < or =0.1 mg/kg had no effect upon locomotor activity or within-session habituation. MK-801 0.2 mg/kg produced a marked hyperlocomotion and completely prevented within-session habituation. One day later, the animals were tested for their retention of habituation to evaluate the effects of MK-801 on memory processes. In that animals treated with 0.2 mg/kg MK-801 failed to habituate to the novel environment under the influence of 0.2 mg/kg MK-801, it was not surprising that these animals were impaired on the retention test for the novel environment. Importantly, however, the 0.1 mg/kg MK-801 treatment, which did not affect locomotor activity or within-session habitation to the novel environment, severely interfered with retention of the novel environment. Additional experiments indicated that this result could not be accounted for by drug conditioning or drug state-dependent effects. Thus, the results indicated that MK-801 can produce profound effects upon motor activity and memory and that these two effects can be disassociated.

Animals↗
PubMed1998

A telemedicine consultative service for the evaluation of patients with urolithiasis.

OBJECTIVES: A 6-month pilot teleconsultative project linking Georgetown University Medical Center (GUMC) in Washington, DC, and City Hospital in Martinsburg, West Virginia, 90 miles away, was designed to assess the effectiveness of telemedicine on the clinical decision-making process for patients with urolithiasis. METHODS: The telemedicine system designed and tested for this project was based on a PC-based platform. Videoconferencing and review of the patient's imaging studies were performed over an Integrated Service Digital Network (ISDN) with 3 Basic Rate (BRI) ISDN lines providing a 336-kilobytes/s bandwidth through an Inverse Multiplexor (IMUX). Treatment options were recorded for the clinical trial group and a simulated study group by the consulting urologist after the initial telephone consultation, after the telemedicine consultation, and after examination of those patients transferred to GUMC. RESULTS: A total of 32 telemedicine consultations were performed: 14 in the clinical trial group and 18 in the simulated study group. The recommendation of the consulting urologist at the tertiary center was altered in 12 patients (37.5%) after the telemedicine consultation compared with the recommended treatment after the initial telephone consultation. CONCLUSIONS: In the evaluation of patients with urolithiasis, this telemedicine application enhanced the clinical decision-making process by allowing for improved quality of care through immediate access and effective transfer of information between the referring urologist, the patient, and the stone center specialist.

Adult↗
PubMed1998

Population heterogeneity of higher-plant mitochondria in structure and function.

Mitochondria of rapidly developing mungbean seedlings were fractionated into four populations: two density classes, each from a 1500S and a 150S pellet. Each of the four populations exhibited cytochrome c oxidase (COX) activity and contained mitochondrial DNA and cardiolipin; plastid and glyoxysome content were found to be relatively low. Five mitochondrial membrane proteins, COXII/III, ATPase alpha/beta and porin, and a matrix enzyme, manganese superoxide dismutase (MnSOD), were detected by immunoblots in all four populations. Another matrix enzyme, pyruvate dehydrogenase was detected only in the two respiratory-competent 1500S populations. The two 150S populations contained a previously unidentified organelle that lacked demonstrable respiratory capability. This organelle, which we have tentatively referred to as "slow-sedimenting (ss-) mitochondrion", was small in size (below light-optics resolution, 70-300nm, majority < or =200nm) and possessed a peculiar looking boundary membrane, ribosomes, and an occasional prominent electron-dense spot. Characteristically, ss-mitochondria were almost always in contact with a filament-aligned membrane-like structure of varying length. Cristae structure, while undetected in small ss-mitochondria, appeared in larger individuals. Typical mitochondria were found in the denser 1500S population, while the lighter 1500S population consisted of 300-800 nm mitochondria exhibiting a varying degree of size-dependent inner membrane folding. Using electron microscopy (EM) immunolocalization and serial sectioning, we have identified in situ organelles resembling in size and in fine structure the ss-mitochondria, which also exhibit a size-dependent folding of the inner membrane. These results suggest that small ss-mitochondria may undergo a progressive development in situ. Taken together, our findings demonstrate the existence of a pattern of structure-function-coordinated gross heterogeneity among mitochondria. This pattern of mitochondrial heterogeneity, characterized both in isolated mitochondria and in situ, implies that small ss-mitochondria may represent a type of "nascent mitochondria" derived from a yet unidentified mitochondria-propagation mode operating during rapid seedling growth. Mitochondrial division by binary fission, characterized by the appearance of dumbbell-shaped intermediates, was also detected.

Cardiolipins↗
PubMed1998

Design and baseline characteristics of the Veterans Affairs Non-Q-Wave Infarction Strategies In-Hospital (VANQWISH) trial. VANQWISH Trial Research Investigators.

OBJECTIVES: The Veterans Affairs Non-Q-Wave Infarction Strategies In-Hospital (VANQWISH) trial was designed to compare outcomes of patients with a non-Q wave myocardial infarction (NQMI) who were randomized prospectively to an early "invasive" strategy versus an early "conservative" strategy. The primary objective was to compare early and late outcomes between the two strategies using a combined trial end point (all-cause mortality or nonfatal infarction) during at least 1 year of follow-up. BACKGROUND: Because of the widely held view that survivors of NQMI are at high risk for subsequent cardiac events, management of these patients has become more aggressive during the last decade. There is a paucity of data from controlled trials to support such an approach, however. METHODS: Appropriate patients with a new NQMI were randomized to an early "invasive" strategy (routine coronary angiography followed by myocardial revascularization, if feasible) versus an early "conservative" strategy (noninvasive, predischarge stress testing with planar thallium scintigraphy and radionuclide ventriculography), where the use of coronary angiography and myocardial revascularization was guided by the development of ischemia (clinical course or results of noninvasive tests, or both). RESULTS: A total of 920 patients were randomized (mean follow-up 23 months, range 12 to 44). The mean patient age was 61 +/- 10 years; 97% were male; 38% had ST segment depression at study entry; 30% had an anterior NQMI; 54% were hypertensive; 26% had diabetes requiring insulin; 43% were current smokers; 43% had a previous acute myocardial infarction; and 45% had antecedent angina within 3 weeks of the index NQMI. CONCLUSIONS: Baseline characteristics were compatible with a moderate to high risk group of patients with an NQMI.

Angina Pectoris↗
PubMed1998

Tensile strength of lens capsules in eye-bank eyes.

PURPOSE: To measure the tensile strength of the anterior and posterior lens capsules in eye-bank eyes and study the tensile strength of capsules dehydrated with hypertonic glucose solution. SETTING: Tongren Hospital, Beijing, China. METHODS: The in situ anterior and posterior capsules of 35 eye-bank eyes (Group 1) donated by healthy men aged 20 to 40 years (mean 27.1 years) were measured with a biomembrane strength device. Sixteen eyes (Group 2), from donors aged 20 to 37 years (mean 27.0 years) and similar to those in Group 1, were measured in the same way after the anterior and posterior capsules were exposed to glucose 50% solution for 15 minutes. RESULTS: In Group 1, anterior and posterior capsule strength was 6.269 +/- 1.118 and 3.755 +/- 0.835 g, respectively (P < .01), and the correlation between the tensile strength of the anterior and posterior capsules was statistically significant (r = .94; P < .001). In Group 2, the strength of the capsules increased to 9.024 +/- 0.586 and 4.424 +/- 0.761 g, respectively, a finding that was statistically significantly different from that in Group 1 (P < .01 and .05, respectively. CONCLUSION: The tensile strength of the anterior capsule was stronger than that of the posterior capsule under the experimental conditions. Glucose 50% solution has the potential to increase the tensile strength of anterior and posterior capsules.

Adult↗
PubMed1998

Drug target validation and identification of secondary drug target effects using DNA microarrays.

We describe here a method for drug target validation and identification of secondary drug target effects based on genome-wide gene expression patterns. The method is demonstrated by several experiments, including treatment of yeast mutant strains defective in calcineurin, immunophilins or other genes with the immunosuppressants cyclosporin A or FK506. Presence or absence of the characteristic drug 'signature' pattern of altered gene expression in drug-treated cells with a mutation in the gene encoding a putative target established whether that target was required to generate the drug signature. Drug dependent effects were seen in 'targetless' cells, showing that FK506 affects additional pathways independent of calcineurin and the immunophilins. The described method permits the direct confirmation of drug targets and recognition of drug-dependent changes in gene expression that are modulated through pathways distinct from the drug's intended target. Such a method may prove useful in improving the efficiency of drug development programs.

Calcineurin↗
PubMed1998

Detection of sinusoidal amplitude modulation at unexpected rates.

The detectability of sinusoidal amplitude modulation at unexpected modulation rates was assessed using a probe-signal method. With this method, three listeners were led to expect a target modulation rate (4, 32, or 256 Hz) by presenting the signal most often at that rate, and sensitivity to modulation at six other unexpected rates between 4 and 256 Hz was measured via occasionally presented probe modulation rates. The modulation phase was random on each two-interval forced-choice trial and the overall level of the 500-ms broadband carrier was randomly varied between 55 and 75 dB SPL across intervals. The modulation depth at each rate was set so that the modulation was detected on about 90% of the trials when only that rate was presented. Performance at the unexpected rates depended upon the target rate. For the 4-Hz target, modulation at all rates was detected on about 80% of the trials. For the 32- and 256-Hz targets, unexpected modulation rates of 16 Hz and above were detected on 80%-90% of the trials, but modulation rates below 16 Hz were detected nearly at chance. The influence of expectation of modulation rate on the detection of sinusoidal amplitude modulation is not readily predicted by current models of modulation detection.

Adult↗
PubMed1998

AIDS risk perception among women drug users in Hartford, CT.

This paper reports the findings of a study of congruence between AIDS risk perception and risk behavior in a sample of outreach-recruited out-of-treatment injection and non-injection crack cocaine using women in Hartford, CT. While rates of drug- and sex-related AIDS risk were high in this sample, perception of risk was low among many of the respondents. Variation in risk perception reflects sociodemographic differences in the sample, with those women who were most socially isolated exhibiting the greatest incongruence between personal risk and risk perception. Women who have had contact with health or social service programs were the most likely to report reductions in risk behavior.

Adult↗
PubMed1998

[Research in the relationship between Chlamydia and ureaplasma and infertility].

Samples taken from cervix and male urethra of 768 infertilitas patients were studied, and samples taken from 226 normal fertile males and females served as control. The fluorescent monoclonal antibody technique and cell culture method were used for Chlamydia trachomatis (Ct) and microbiological culture method was used for Ureaplasma urealyticum (Uu) detection. The positive rates of Ct and Uu infections were 28.64% (220/768) and 36.59% (281/768) in infertilitas group, 5.2% (14/266) and 14.28% (38/266) in control group respectively. There was significant difference between the 2 groups (P < 0.01). The results suggest that infection with Ct or Uu is one of the factors causing infertility.

Adult↗
PubMed1998

[The effects of diltiazem on pulmonary hemodynamics and oxygenation in copd induced pulmonary hypertension].

OBJECTIVE: To study hemodynamic the effects of intravenous diltiazem on COPD induced pulmonary hypertention. METHODS: 11 cases in exacerbation stage were chosen to study. Swan-Ganz catheterization were taken for hemodynamic monitoring. RESULTS: After the administration of diltiazem, pulmonary vascular resistance, pulmonary pressure, right artrial pressure and heart rate decreased significantly (the extents decreased were 14.0 kPa.s-1.L-1, 0.62-1.27 kPa, 0.27-0.40 kPa and 25-30 beats/min respectively, P < 0.05); Cardiac output and stroke volume increased identically (the extents increased were 0.3-0.6 L.min-1.m-2 and 5-9 ml.beat-1.m-2 respectively, P < 0.05); No significant changes found in Qs/Qt, PaO2 and systemic blood pressure. CONCLUSION: Our study showed that diltiazem produces beneficial pulmonary hemodynamic effects without oxygenation compromise in COPD cases and has a strong indication in those who complicated with superventricular tachycardia.

Aged↗
PubMed1998

Growth regulation of ovarian cancer cell line HO-8910 by transforming growth factor beta 1 in vitro.

OBJECTIVE: To further understand the role of growth regulation of human ovarian cancer cells by transforming growth factor (TGF) beta 1. METHODS: The cell proliferation, cAMP synthesis, gene expression, and induction of programmed cell death (PCD) in human epithelial ovarian cancer cell line HO-8910 cells exposed to TGF beta 1 in vitro were studied. RESULTS: TGF beta 1 inhibited cell growth and DNA synthesis, and induced G0/G1 arrest in cell cycle. It could also trigger PCD in cells. This induction of PCD may occur within G0/G1 phase. Meanwhile, the assay also showed that TGF beta 1 could inhibit the mRNA expression of c-myc, EGFR and TGF beta 1 genes in cells. CONCLUSIONS: TGF beta 1 can not only act as an autocrine to inhibit cell proliferation, but also trigger PCD in HO-8910 cells. These functions may be fulfilled through some specific signal transduction pathways.

Apoptosis↗
PubMed1998

[Living related liver transplantation: a case report].

OBJECTIVE: To study a case of living related liver transplantation. METHOD: The patient was a 10-year-old girl who suffered from congenital diffuse intrahepatic cholangiectasis, recurrent cholangitis and hepatocirrhosis. The donor was the patient's father aged 40. The left lateral lobe of donor's liver was cut and grafted to the patient. Intensive care and treatment as well as follow-up were given after operation. RESULT: For the donor, the operation lasted 400 min, with 410 ml bleeding and 300 g liver removed. The recovery was satisfactory. For the recipient, the operation lasted 652 min, with 1665 ml bleeding, 80 min non-liver stage, 0 min graft hot ischemic stage, and 137 min cold ischemic stage. Immunosuppressive therapy was given using cyclosporin A, azathioprine and adrenocortical hormones. There was an acute rejection 11 days after operation, which was controlled using hormone impulsive therapy. The patient has been surviving 7 months with normal liver function. CONCLUSION: The living related liver transplantation is feasible under modern surgical conditions. It is demonstrated that perfect postoperative management is the key for the successful liver transplantation.

Adult↗
PubMed1997

UAS(MAG1), a yeast cis-acting element that regulates the expression of MAG1, is located within the protein coding region of DDI1.

MAG1 and DDI1 are two divergently transcribed DNA damage-inducible genes from Saccharomyces cerevisiae. Previous studies have shown that MAG1 induction requires an upstream activating site (UAS) located between nucleotides -376 and -330. Here we show that a 24-bp oligonucleotide from within the UAS(MAG1) region forms a sequence-specific DNA-protein complex with partially purified proteins from S. cerevisiae. Point mutations introduced into the 24-bp oligonucleotide inhibited the formation of the DNA-protein complex and decreased the level of induction of MAG1-lacZ. By determining the transcription and translation start points of both MAG1 and DDI1, an interesting, indeed unprecedented feature of genome organization in eukaryotes was revealed: UAS(MAG1) actually lies within the protein-coding region of DDI1. Although tightly linked to each other, and co-induced upon treatment with DNA-damaging agents, DDI1 does not share the UAS(MAG1) required for DNA damage induction of MAG1. Furthermore, MAG1 and DDI1 respond differently in the presence of the protein synthesis inhibitor cycloheximide, suggesting that these two genes are regulated by different mechanisms in the absence of de novo protein synthesis.

Amino Acid Sequence↗
PubMed1997

Restoration of nitric oxide production by aldose reductase inhibitor in human endothelial cells cultured in high-glucose medium.

The effects of elevated glucose and aldose reductase inhibitor (ARI:ONO-2235) on nitric oxide (NO) production in cultured human umbilical endothelial cells (HUVEC) were evaluated. Aldose reductase and nitric oxide synthase(NOS) share NADPH as an obligate cofactor, therefore it is suggested that the enhanced of glucose flux (27.5 mM) by aldose reductase inhibited NO production by blunting NOS activity. However, the addition of ONO-2235 (100 microM) prevented the inhibition of [NO2-] production. Since ARI decreases glucose-mediated inhibition of NO production in HUVEC. this agent might ameliorate endothelial function associated with diabetes.

Aldehyde Reductase↗