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Biomedical subjects

D Hu

Publications and source records attributed to D Hu.

At least 145 records · Page 8Linked to original sources
PubMed1996

A comparative study of intravenous accelerated streptokinase dose regimen with conventional dose regimen for coronary thrombolysis.

The aim of this study is to test the patency rate and safety of the accelerated streptokinase dose regimen for coronary thrombolysis compared with the conventional one. One hundred and four patients entering three hospitals up to 12 hours after the onset of definite acute myocardial infarction were randomizely treated with intravenous accelerated streptokinase dose regimen (1.5 million units/30 min) (group A, 47 cases) and conventional dose regimen (1.5 million units/60 min) (group B, 57 casese). The reperfusion rate of infarct-related arteries determined by clinical evidence of reperfusion was 76.6% (36/47) in group A VS 61.4% (35/57) in group B. There was significant difference in reperfusion rates among patients within 6 hours after the onset of chest pain: 87.9% (29/33) in group A VS 67.4 (29/43) in group B (P < 0.05). The incidence of mild bleeding, allergic reaction, hypotension was 12.8% (6/47), 4.3% (2/47), 12.8 (6/47) respectively in group A vs 21.1 (12/57), 3.5 (2/57), 17.5% (10/57) respectively in group B. Compared to conventional dose regimen, intravenous accelerated streptokinase dose regimen for coronary thrombolysis seems to improve reperfusion rate markedly without increasing adverse events such as bleeding, allergic reaction and hypotension. It suggests that accelerated streptokinase therapy deserves more extensive investigation.

Aged↗
PubMed1996

[Response and mechanism of vasovagal syncope induced by tilt table test].

Tilt table test (TTT) is done in 110 cases of unexplained syncope and 37 healthy controls. As a result, there is no significant difference in basal diastolic blood pressure (DBP), basal heart rate (HR) x DBP among TTT positive, TTT negative and healthy controls; but DBP and HR x DBP of TTT positive patients at the instant of syncope is not significantly different from their basal values, the HR at the instant of syncopy statistically in not different from the basal HR. These data suggest that not the same mechanism is responsible for the changes of BP and HR. In seventy percent of the TTT positive patients vasovagal syncope (VS) may be provoked by isoproterenol. So the occurrence of VS may be related to hypersensitivity of beta-receptor. TTT may be an approach to unravel the pathogenesis of VS.

Adrenergic beta-Agonists↗
PubMed1996

[A review of 10 patients of nephrectomy through laparoscope video].

Ten patients were subjected to nephrectomy through laparoscope video. Compared with routine nephrectomy, it has such merits as slight trauma, less bleeding and pain during the operation as well as quick recovery and short hospitalization. In 6 male patients and 4 female patients the oldest one was 75 years old, and the youngest one was 15 years old. Seven patients suffered from nephrohydrosis and 3 from polycystic kidney. Before the operation, the patients were found the loss of function of the diseased kidney. The video scope was inserted into the abdominal cavity through an operating hole under the navel making the exploration in the cavity; the other operations are as basical as routine operations. The ill kidney was cut off and put into a special pocket, then it was cut into pieces, and taken out. The abdominal membrane was enclosed by the emanometer, the drainage tube kept. In the 10 patients the operations were successful and satisfactory.

Adolescent↗
PubMed1995

A simple test of the vicarious trial-and-error hypothesis of hippocampal function.

Vicarious trial-and-error (VTE) is a term that Muenzinger and Tolman used to describe the rat's conflict-like behavior before responding to choice. Recently, VTE was proposed as a mechanism alternative to the concept of "cognitive map" in accounts of hippocampal function. That is, many phenomena of impaired learning and memory related to hippocampal interventions may be explained by behavioral first principles: reduced conflicting, incipient, pre-choice tendencies to approach and avoid. The nonspatial black-white discrimination learning and VTE behavior of the rat were investigated. Hippocampal-lesioned and sham-lesioned animals were trained for 25 days (20 trials per day) starting at 60 days of age. Each movement of the head from one discriminative stimulus to the other was counted as a VTE instance. Lesioned rats had fewer VTEs than sham controls, and the former learned much more slowly or never learned. After learning, VTE frequency declined. Male and female rats showed no significant differences in VTE behavior or discrimination learning.

Animals↗
PubMed1995

Interactions of human nuclear proteins P1Mcm3 and P1Cdc46.

Human nuclear proteins P1Mcm3 and P1Cdc46 have high sequence similarities with the corresponding yeast proteins known to be required for the initiation of genome replication. Nuclei of proliferating HeLa cells contain relatively high amounts of P1Mcm3 (about 10(6) molecules/nucleus) of which only a small fraction is bound to a nuclear structure, most probably chromatin. At 0.5 M NaCl, the structure-bound nuclear protein can be partially solubilized as a dimer composed of P1Mcm3 and the related protein P1Cdc46. However, most protein P1Mcm3 is not bound to a nuclear structure and appears in the nucleoplasm. About 10% of protein P1Mcm3 in the soluble fraction is free and uncomplexed, and the remaining P1Mcm3 forms stable complexes with protein P1Cdc46. These P1Mcm3/Cdc46 complexes occur as dimers and in high-molecular-mass complexes (approximately 500 kDa). The high-molecular-mass complexes dissociate in 0.5 M NaCl and release P1Mcm3/Cdc46 dimers. It has frequently been proposed that the Mcm proteins may function as licensing factors for genome replication. Our data imply that the active form of an Mcm protein is not a monomer, but a protein complex that includes an Mcm3/Cdc46 dimer. DNA polymerase alpha is not a component of this complex.

Amino Acid Sequence↗
PubMed1995

Flow cytometric assay for cytotoxic activity of crude Clostridium perfringens enterotoxin using non-adherent cell FM3A.

The flow cytometric assay method was tested for the cytotoxic activity of Clostridium perfringens enterotoxin (CPE) in culture using mouse mammary carcinoma cell line FM3A stained with propidium iodide (PI). From the results obtained, FM3A cells proved to be susceptible to CPE. A reproducible dose-response curve with FM3A was obtained between crude CPE at 13.9-109 ng/ml and between purified CPE at 40-400 ng/ml, respectively. These findings indicate that non-adherent FM3A is preferable to determine the cytotoxic activity of CPE because it can be used without detachment procedures with trypsinin compared with adherent African monkey kidney cell line (Vero cells). Furthermore, the flow cytometry with non-adherent cell FM3A stained with PI only proved to be a useful method to determine the biological activity of CPE in culture isolates.

Animals↗
PubMed1995

[Predictive values for slow pathway modification of atrioventricular nodal reentrant tachycardia].

The predictive values of various ECG parameters for slow pathway modification were studied in 42 slow-fast AVNRT patients. The negative predictive values of a stable ECG, junctional rhythm, and slow pathway potential were as high as 94.8%, 94.9% and 84.9% respectively. But, their positive values were 29.4%, 15.1% and 23.9%. The possibility of success (PS) raised with increasing of width and peak number of A wave. When the width of A wave was > or = 80ms, PS was 50%. When the peak number of A wave was > 7, PS was 80%. A/V ratio varied from 0.14 to 1 in 93.2% of successful sites. When A/V ratio was 0.25, PS reached its peak value of 33.3%.

Adolescent↗
PubMed1995

[Effects of interferon treatment on mutation of hepatitis B virus precore genome].

Effects of interferon (IFN) treatment on mutation of hepatitis B virus (HBV) precore were studied with a rapid polymerase chain reaction method to investigate the stop codon in the distal precore region during HBV precore mutation. 6 cases of chronic hepatitis B were treated with recombinant IFN alpha 1 3 x 10(6) U/day for 14 weeks. In 4 of them HBV DNA was undetectable after treatment. Precore mutant was detected in the remaining 2 cases whose HBV DNA was still positive. In a group of 11 cases not treated with IFN, mutants were detected in 3. HBV e antigen (HBeAg) became negative after IFN treatment in one case, the original wild strain was replaced by a status of co-existence of mutant and wild strain. These results suggest that HBeAg negative seroconversion after IFN treatment does not necessarily implicate a complete clearance of HBV and the possibility of mutation of precore still exists.

Adult↗
PubMed1995

[Effect of DL-butylphthalide (NBP) on mouse brain energy metabolism in complete brain ischemia induced by decapitation].

The effects of NBP on gasping and brain energy metabolism after complete brain ischemia in mice subjected to decapitation were investigated. The levels of ATP, phosphocreatine (PCr) and lactate were determined by the method of Lowry. The data indicated that NBP at 112.5 or 250 mg.kg-1 sc can significantly prolong the duration of gasping and at the dose of 150 or 200 mg.kg-1 sc reduce the level of lactate and increase the levels of ATP and PCr after complete brain ischemia. The results suggest that NBP may have brain protective action and improve ischemic brain energy metabolism.

Adenosine Triphosphate↗
PubMed1995

[Scavenging effects of daphnetin and its Cu, Zn complexes on superoxide radical].

The scavenging effects of daphnetin (D) and its Cu, Zn complexes on superoxide radical (O2-.) generated through the photooxidation of riboflavin were studied with human red blood cells (RBC) and RBC membrane as experimental material. The Cu ( II ) complex showed the highest activity. SOD, D and its Cu ( II ), Zn ( II ) complexes were found to have inhibitory effect on the production of lipid peroxide in the membrane, SOD being the best among them.

Erythrocyte Membrane↗
PubMed1995

Transseptal methods for percutaneous balloon valvoplasty simultaneously with radiofrequency catheter ablation.

Percutaneous balloon mitral valvoplasty (PBMV) and radiofrequency catheter ablation (RFCA) have been used in the treatment of mitral stenosis (MS) and supraventricular tachycardia. The techniques of PBMV and RFCA yield better results with the development of interventional cardiology, but there is no report about PBMV performed simultaneously with RFCA in the same patient. Seven patients with mitral stenosis and Wollf-Parkinson-White (W-P-W) Syndrome were successfully treated with PBMV and RFCA by transseptal methods. LA, LAP, mPG and mPA were decreased from 43.4 +/- 4.6mm, 21.8 +/- 6.8mmHg, 21 +/- 7.7mmHg and 45.7 +/- 16.5mmHg to 39.2 +/- 3.7mm (P < 0.05), 12.7 +/- 4.5mmHg, 12 +/- 3.7mmHg and 32.3 +/- 9mmHg (P < 0.01). MVA was increased from 0.96 +/- 0.33cm2 to 1.7 +/- 0.80cm2 (P < 0.01). delta wave disappeared in 12-lead surface EKG and SVT could not be induced in electrophysiological study after the treatment. The overall time of the procedure for this series was 93 +/- 34 minutes and fluoroscopy time was 23 +/- 7 minutes on the average. Radiofrequency energy applications were 3 +/- 2 times each procedure. PBMV and RFCA are safe and highly effective in the treatment of MS and W-P-W syndrome. The results in the present study proved the feasibility of the combined use of PBMV and RFCA. We prefer a first choice of PBMV and then RFCA in order to avoid aggravation of the hemodynamics due to mitral stenosis. The results also showed that of overall procedure and fluoroscopy only took a short time for this series. We suggest that it could be used as a routine method for the treatment of mitral stenosis complicated by W-P-W syndrome.

Adult↗
PubMed1994

Building synthetic antibodies as adhesive ligands for integrins.

An antibody engineering strategy was employed to build high affinity ligands and antagonists of integrins alpha v beta 3 and alpha IIb beta 3. Previously, we inserted the integrin recognition motif, RGD, into the antigen binding site of a human antibody and selected the optimal flanking sequences from a phage-display library (Barbas, C. F., Languino, L. R., and Smith, J. W. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 10003-10007). The resulting antibody, Fab-9, blocked the function of integrin alpha v beta 3 but also bound to the ligand binding site of platelet integrin alpha IIb beta 3. In this report, the antibody engineering effort has been extended by 1) redesigning Fab-9 to achieve specificity for platelet integrin alpha IIb beta 3, 2) building non-RGD-containing antibodies that bind the ligand binding site of both beta 3-integrins, and 3) testing the hypothesis that peptides derived from complementarity determining regions (CDR) can be used to emulate the activity of the parent synthetic antibody. These goals were accomplished by subjecting the original antibody, Fab-9, to a "motif optimization" (MTF). A phage library was constructed in which the residues flanking the RGD motif in Fab-9 were maintained, but the RGDX sequence was randomized. This library was panned on purified alpha IIb beta 3 to identify high affinity binders. Four function-blocking antibodies lacking RGD, but with specificity for alpha IIb beta 3, were characterized. The antibody with the highest preference for alpha IIb beta 3, MTF-10, had an adhesion sequence of KGDN. This sequence is similar in primary structure to the active sequence within the disintegrin barbourin, which also antagonizes alpha IIb beta 3 (Scarborough, R. M., Rose, J. W., Hsu, M. A., Phillips, D. R., Fried, V. A., Campbell, A. M., Nannizzi, L., and Charo, I. F. (1991) J. Biol. Chem. 266, 9359-9362). MTF-10 had a 70-fold higher affinity for alpha IIb beta 3 than alpha v beta 3. Through our selection strategy, we also identified several antibodies that lack RGD but still blocked ligand binding to both integrins with high affinity. Therefore, the RGD sequence is not necessary for a high affinity interaction with the ligand binding site of beta 3-integrins. Further investigation showed that the activity of inhibitory antibodies could be emulated by synthetic peptides derived from the protein sequences of the antibody's HCDR3. CDR-derived peptides blocked ligand binding to integrins and maintained essentially the same specificity as the parent antibody.

Amino Acid Sequence↗
PubMed1994

Sensitivity of United States HIV antibody tests for detection of HIV-1 group O infections.

Infections by highly divergent strains of HIV-1, first detected in central Africa and grouped provisionally as group O, have not been reliably detected by certain European HIV screening tests. Serum specimens from eight probable group O infections from Cameroon were tested by ten HIV assays licensed by the US Food and Drug Administration. All assays based on synthetic peptides or recombinant antigens failed to detect at least one of the infections; assays based on whole-virus lysates performed better. Divergent HIV strains may be undetected by current HIV tests. Thus active surveillance for and characterisation of HIV variants to evaluate and, when necessary, modify current tests is urgently needed.

AIDS Serodiagnosis↗
PubMed1994

In vitro evolution of a neutralizing human antibody to human immunodeficiency virus type 1 to enhance affinity and broaden strain cross-reactivity.

A method is described that allows for the improvement of antibody affinity. This method, termed complementary-determining region (CDR) walking, does not require structural information on either antibody or antigen. Complementary-determining regions are targeted for random mutagenesis followed by selection for fitness, in this case increased binding affinity, by the phage-display approach. The current study targets a human CD4-binding-site anti-gp120 antibody that is potently and broadly neutralizing. Evolution of affinity of this antibody demonstrates in this case that affinity can be increased while reactivity to variants of human immunodeficiency virus type 1 is broadened. The neutralizing ability of this antibody is improved, as assayed with laboratory and primary clinical isolates of human immunodeficiency virus type 1. The ability to produce human antibodies of exceptional affinity and broad neutralizing ability has implications for the therapeutic and prophylactic application of antibodies for human immunodeficiency virus type 1 infection.

Amino Acid Sequence↗
PubMed1994

Metachromatic leukodystrophy in the Navajo Indian population: a splice site mutation in intron 4 of the arylsulfatase A gene.

Metachromatic leukodystrophy (MLD) is an autosomal recessive disorder of myelin metabolism, resulting from the inability to properly degrade 3-sulfogalactosylceramide (sulfatide). This metabolic block is often due to defective functioning of the lysosomal enzyme arylsulfatase A (ARSA). Unmetabolized sulfatide accumulates in the white matter of the CNS and in the peripheral nerves, leading to progressive demyelination and death. Late infantile, juvenile and adult clinical variants of MLD have been described. A Navajo Indian child was diagnosed with late infantile MLD (LIMLD), and his ARSA gene was amplified in three overlapping regions by the PCR and sequenced. A single mutation was found: a G-->A transition in the first nucleotide of intron 4 (IVS4nt1), which abolishes the 5' splice site consensus sequence. Negligible amounts of ARSA mRNA were observed in Northern blots. However, PCR amplification and sequencing of the ARSA cDNA showed that all of the mRNA species from the patient have exon 4 deleted. A new reading frame is thus established which results in a premature stop codon within exon 5. A minority of transcripts had additional splicing errors. Both parents carry this mutation, and the father also carries the pseudodeficiency (PD) allele. Three additional unrelated Navajo LIMLD patients were found to be homozygous for the same MLD-causing mutation by allele-specific oligonucleotide (ASO) hybridization. This method could be used for carrier and patient identification in this population.

Adult↗