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Biomedical subjects

J Huang

Publications and source records attributed to J Huang.

At least 541 records · Page 30Linked to original sources
PubMed1997

Matrix metalloproteinase-9 in cerebral aneurysms.

OBJECTIVE: Generalized disruption of arterial wall morphological changes in patients harboring cerebral aneurysms has been documented; however, little is known regarding the pathogenesis of these changes. To explore the role of the elastolytic gelatinase, matrix metalloproteinase-9 (MMP-9), levels of this enzyme in the wall of intracranial aneurysms were compared with those in both intracranial and extracranial arteries. The tissue levels of its major inhibitor, tissue inhibitor of metalloproteinase (TIMP), were measured in these tissues as well. The activity of MMP-9 in plasma was also evaluated. METHODS: The aneurysm wall was excised from three of six patients undergoing craniotomies for aneurysm clipping. A 1-cm segment of superficial temporal artery (STA) was obtained from each of six patients. Additional STAs were obtained from six patients in the control group who were undergoing craniotomies for nonvascular disease. An intracranial artery was also obtained from the anterior temporal neocortical resection of a patient undergoing a craniotomy for mesial temporal sclerosis. MMP-9 and TIMP levels were determined via Western blot analysis. Using substrate gel Zymography, MMP-9 plasma activity was determined for a separate cohort of patients with aneurysms (n = 6) and patients in the control group (n = 6). RESULTS: MMP-9 and TIMP levels in the aneurysm wall were markedly increased beyond levels in both extracranial arteries (STAs from patients with aneurysms and patients in the control group) and the intracranial artery. There were no differences in the levels of MMP-9 in the STAs of patients harboring aneurysms when compared with patients in the control group. Also, no differences were noted in plasma MMP-9 activity. CONCLUSION: Local rather than systemic perturbations in MMP-9 levels may contribute to the matrix disruption associated with cerebral aneurysms. This local up-regulation is not the result of TIMP down-regulation. The lack of increased systemic metalloproteinase activity precludes the use of plasma MMP-9 activity as a screening tool for presymptomatic aneurysms. However, local therapeutic modulation of MMP-9 activity may help arrest aneurysm progression.

Aneurysm, Ruptured↗
PubMed1997

Identification of new autolytic sites of recombinant truncated mature human fibroblast stromelysin by mass spectrometry.

Stromelysin has been proposed to play a major role in the pathologic degradation of diseased cartilage of osteoarthritis and rheumatoid arthritis patients. A truncated, recombinant form of this enzyme, with the sequence Phe83 to Thr260 (mSL-t), has been expressed and purified from E. coli to investigate its biochemical and biophysical properties, and to develop inhibitors for arthritis treatment. LC/ESI-MS technique was utilized for the characterization of mSL-t. The mass spectra of mSL-t showed the presence of a number of different protein components in addition to the full-length mSL-t form. We have demonstrated that protein degradation arose from autolysis. Molecular weights determined by LC/ESI-MS of these autolysis products allowed for the identification of new autolytic sites in mSL-t. Furthermore, two strategies were undertaken to prepare mSL-t free of degradation products. These include preparation of a mutant form of the enzyme in which Arg163 was substituted for Leu163 and purification of mSL-t using affinity chromatography. The LC/ESI-MS data of the mutant protein confirmed the Leu to Arg mutation. The affinity-purified material showed only one LC peak in the LC/MS chromatograms, and the mass spectrum of the peak identified only the intact protein, demonstrating that the full-length protein has been successfully separated from the autodegradation products and further autolysis of the enzyme has been prevented.

Amino Acid Sequence↗
PubMed1997

Effect of electrode polarity on internal defibrillation with monophasic and biphasic waveforms using an endocardial lead system.

INTRODUCTION: To test the hypothesis that the effect of shock polarity on defibrillation depends on waveform duration, this study determined strength-duration defibrillation curves of monophasic and biphasic truncated exponential waveforms for both polarities. METHODS AND RESULTS: Defibrillation thresholds (DFTs) were obtained in 32 pigs for catheter electrodes in the right ventricle (RV) and superior vena cava (SVC) using a modified Purdue technique. Both electrode polarities were tested in five different protocols. In part 1, DFTs were determined with 1- to 14-msec monophasic waveforms. In parts 2, 3, and 4, DFTs were determined with two different sizes of SVC electrodes for biphasic waveforms with a phase 1 of 4 or 6 msec and a phase 2 ranging from 1 to 10 msec. In part 5, DFTs were tested for monophasic waveforms ranging from 2 to 11 msec and for biphasic waveforms with a phase 1 duration corresponding to each monophasic waveform and a phase 2 held constant at 1 msec. Mean DFTs for monophasic waveforms were significantly lower when the RV electrode was an anode than when it was a cathode for waveform durations > or = 3 msec. For biphasic waveforms in which phase 2 was < or = phase 1 in duration, no significant difference in mean DFT was observed when polarity was reversed. Even a phase 2 as short as 1 msec could eliminate the DFT difference between polarities observed with monophasic shocks. When phase 2 was > or = 2 msec longer than phase 1, polarity did affect the DFT of biphasic waveforms; it affected the DFT similarly to a monophasic waveform of the same polarity as phase 2. Phase 1 duration and electrode size also affected the difference in DFT produced by changing the electrode polarity. CONCLUSIONS: For phase durations most commonly used clinically because of their low DFTs, reversing polarity changed defibrillation efficacy for monophasic but not biphasic shocks. For inefficient biphasic waveforms with phase 2 > or = 2 msec longer than phase 1, the DFT was lower when the RV electrode was an anode during phase 2, similar to the polarity difference for monophasic waveforms, suggesting that a long second phase of biphasic waveforms defibrillates in a similar fashion to monophasic waveforms.

Animals↗
PubMed1997

Analysis of the interaction of FtsZ with itself, GTP, and FtsA.

The interaction of FtsZ with itself, GTP, and FtsA was examined by analyzing the sensitivity of FtsZ to proteolysis and by using the yeast two-hybrid system. The N-terminal conserved domain consisting of 320 amino acids bound GTP, and a central region of FtsZ, encompassing slightly more than half of the protein, was cross-linked to GTP. Site-directed mutagenesis revealed that none of six highly conserved aspartic acid and asparagine residues were required for GTP binding. These results indicate that the specificity determinants for GTP binding are different than those for the GTPase superfamily. The N-terminal conserved domain of FtsZ contained a site for self-interaction that is conserved between FtsZ proteins from distantly related bacterial species. FtsZ320, which was truncated at the end of the conserved domain, was a potent inhibitor of division although it expressed normal GTPase activity and could polymerize. FtsZ was also found to interact directly with FtsA, and this interaction could also be observed between these proteins from distantly related bacterial species.

Asparagine↗
PubMed1997

Molecular mechanisms of myogenic coactivation by p300: direct interaction with the activation domain of MyoD and with the MADS box of MEF2C.

By searching for molecules that assist MyoD in converting fibroblasts to muscle cells, we have found that p300 and CBP, two related molecules that act as transcriptional adapters, coactivate the myogenic basic-helix-loop-helix (bHLH) proteins. Coactivation by p300 involves novel physical interactions between p300 and the amino-terminal activation domain of MyoD. In particular, disruption of the FYD domain, a group of three amino acids conserved in the activation domains of other myogenic bHLH proteins, drastically diminishes the transactivation potential of MyoD and abolishes both p300-mediated coactivation and the physical interaction between MyoD and p300. Two domains of p300, at its amino and carboxy terminals, independently function to both mediate coactivation and physically interact with MyoD. A truncated segment of p300, unable to bind MyoD, acts as a dominant negative mutation and abrogates both myogenic conversion and transactivation by MyoD, suggesting that endogenous p300 is a required coactivator for MyoD function. The p300 dominant negative peptide forms multimers with intact p300. p300 and CBP serve as coactivators of another class of transcriptional activators critical for myogenesis, myocyte enhancer factor 2 (MEF2). In fact, transactivation mediated by the MEF2C protein is potentiated by the two coactivators, and this phenomenon is associated with the ability of p300 to interact with the MADS domain of MEF2C. Our results suggest that p300 and CBP may positively influence myogenesis by reinforcing the transcriptional autoregulatory loop established between the myogenic bHLH and the MEF2 factors.

3T3 Cells↗
PubMed1997

Amidative peptide processing and vascular function.

Substance P (SP), an amidated peptide present in many sensory nerves, is known to affect cardiovascular function, and exogenously supplied SP has been shown to activate nitric oxide synthase (NOS) in endothelial cells. We now report that SP-Gly, the glycine-extended biosynthetic precursor of SP (which is enzymatically processed to the mature amidated SP), causes relaxation of rat aortic strips with an efficacy and potency comparable to that of SP itself. Pretreatment of the aortic strips with 4-phenyl-3-butenoic acid (PBA), an irreversible amidating enzyme inactivator, results in marked inhibition of the vasodilation activity induced by SP-Gly but not of that induced by SP itself. Isolated endothelial cell basal NOS activity is also decreased by pretreatment with PBA, with no evidence of cell death or direct action of PBA on NOS activity. Both bifunctional and monofunctional forms of amidating enzymes are present in endothelial cells, as evidenced by affinity chromatography and Western blot analysis. These results provide evidence for a link between amidative peptide processing, NOS activation in endothelial cells, and vasodilation and suggest that a product of amidative processing provides intrinsic basal activation of NOS in endothelial cells.

Amino Acid Sequence↗
PubMed1997

AIDS-related Kaposi's sarcoma: prospective validation of the AIDS Clinical Trials Group staging classification. AIDS Clinical Trials Group Oncology Committee.

PURPOSE: To prospectively validate the AIDS Clinical Trials Group (ACTG) staging classification for AIDS-associated Kaposi's sarcoma (KS). PATIENTS AND METHODS: Two hundred ninety-four consecutive patients enrolled in eight ACTG therapeutic trials for AIDS-associated KS were staged prospectively according to tumor extent (T), severity of immunosuppression (I), and other systemic human immunodeficiency virus type 1 (HIV-1)-associated illness (S) and were observed for survival. Patients were classified as good risk (subscript 0) or poor risk (subscript 1) for each variable according to published ACTG criteria. Univariate and multivariate analyses were used to evaluate the associations between TIS variables and survival; additional analyses were conducted to improve the predictive value of the staging system. RESULTS: Survival was significantly shorter for patients in the poor-risk category for each of the TIS variables. Respective median survivals for patients in the good- and poor-risk categories were 27 and 15 months for T (P < .001); 40 and 13 months for I (P < .001) when I0 included CD4 counts > or = 200/microL and 22 and 16 months for S (P = .04). Multivariate analysis indicated that severity of immunosuppression gave the most predictive information but also showed that T provided significant additional predictive information in patients whose immune function was least impaired. Refined Cox models using a CD4 count of 150/microL rather than 200/microL to distinguish I0 and I1 yielded a simplified model with better fit to the observed data. CONCLUSION: The ACTG TIS classification predicts survival in patients with AIDS-associated KS; CD4 count and tumor stage provide the most predictive information. However, a lower CD4 count than the one originally proposed provides better discrimination between prognostic groups.

Acquired Immunodeficiency Syndrome↗
PubMed1997

[Effects of permissive hypercapnia on cardiopulmonary function in acute lung injury model].

OBJECTIVE: To observe the effects of permissive hypercapnia on cardiopulmonary function in oleic acid induced acute lung injury (ALI) models. METHOD: ALI models of pigs were induced successfully by infusing oleic acid, Swan-Ganz cathether was used for monitoring hemodynamics and different low tidal volumes were set for variable hypercapnia. RESULTS: ALI was characterized by an increase in airway pressure and a decrease in static compliance (Cst), artery oxygen tension (PaO2), oxygenation index and cardiac output. There was also an increase in mean pulmonary artery pressure (mPAP), pulmonary vascular resistance (PVR), systemic vascular resistance (SVR) and shunt fraction. After using 0.98 kPa (1 kPa = 10.2 cmH2O) PEEP, some of cardiopulmonary functions were improved. While reduced tidal volume to 7.7 +/- 0.3 ml/kg and PaCO2 increased to 9.44 +/- 1.27 kPa (1 kPa = 7.5 mmHg), which caused neither a change in PaO2/FiO2, PaO2, Cst nor in SVR, PVR but an increase in cardiac output. Though ventilation setting did not change except for the reducing tidal volume to 6.1 +/- 0.6 ml/kg and PaCO2 reached 12.1 +/- 1.05 kPa, then various adverse effects on cardiopulmonary system were observed. CONCLUSION: It seems that mechanical ventilation with permissive hypercapnia was safe at certain level.

Animals↗
PubMed1997

[Report of four cases of 22 channel cochlear implantations].

22 channel cochlear implants were implanted in 3 postlinguistical deafened adults and a prelinguistical deafened adolescent. All 4 patients including one with total cochlear ossification and another with congenital cochlear malformation showed significant auditory performance and demonstrated satisfactorily improved speech perception test scores postoperatively.

Adolescent↗
PubMed1997

[Carotid cavernous fistula (report of 14 cases)].

Fourteen cases of carotid cavernous fistula (CCF), including 9 cases of traumatic CCF and 5 cases of spontaneous CCF, were treated respectively or in combination with the ligation of the carotid, the isolation of the fistula, following clipping of its upper and lower reaches of the carotid, and endovascular treatment of balloons, steel coils, dry frozen dural pieces or Ivalon grains. It is considered that the detachable balloon endovascular embolization is a choice treatment for CCF.

Adult↗
PubMed1997

[Reference values for biological parameters in occupational and environmental medicine].

Biological parameters are extensively used in occupational and environmental medicine. They are traditionally evaluated by comparison with normal range. Since 1970's, with the growing skepticism about normal range and researches' progress, the replacing notion of reference values and related theory had gradually come into being with the one which is the most representative, published by International Federation of Clinical Chemistry and International Committee for Standardization in Haematology. This paper introduces those results with emphatic discussion on data processing and statistical procedures. The process of establishing reference limits is illustrated by an example and issues on reference and decision limits, reference band, multivariate reference values are also briefly addressed.

Environmental Medicine↗
PubMed1997

[Study of PEFV curves in 520 normal middle-aged and old humans].

Partial expiratory flow-volume(PEEV) curves and other pulmonary functions were performed for 520 (20-86 yr) normal midde-aged and old humans. The regression equations of V at FRC (VFRC, volume corrected VFRC (VFRC/FVC), flows at various lung volumes (V75, V50, V25) and specific time constants (S tau 75, S tau 50, S tau 25) were built with multiple stepwise regression analysis. VFRC decreased with increase of age, but after correction with FVC, the correlation of VFRC/FVC with age decreased. The regressions were tested with substitution of parameters with normal persons and proved to be correct. This study suggests that PEFV curve with convenient method has theoretical and practical significance.

Adult↗
PubMed1997

[Analysis of the mechanism on the formation of configuration of F-V curves with tangent time constant in adult humans].

The tangent time constants at high, mid, low lung volumes (tau t75, tau t50, tau t25) were measured from F-V curves of 258 normal adults aged 20-49. The configurations of F-V curves were classified into the plateau, linear, convex and concave types. In terms of distribution ratio, the convex type increased with age, but the concave type decreased with age. The top of F-V curve was chiefly determined by the length of magnitude of tau t75. The magnitude of tau t75 was the longest for the concave type; its top fell down slowly with the formation of a blant round shape. The magnitude of tau t75 of convex type was the shortest; its top fell down rapidly and formed a peak shape. The mid portion of the curve was determined by the length of tau t50 and the height of V50. The tau t50 was longer and V50 was higher in the plateau and concave types, so that the mid portion fell down slowly to form a plateau or to be concave to the volume axis. While tau t50 was shorter and V50 was lower in the convex and linear types, the mid portion became convex to the volume axis or formed a linear shape. The configuration of the tail was determined by tau t25 and V25. The long tau t25 and high V25 in the plateou type implied the extension of plateau to the low lung volumes. While tau t25 in theother 3 types was shorter. However, V25 was higher in the concave type, thus it made the tail fall down fast and become concave to the volume axis. The V25 was lower in the convex type with the tail convex to the volume axis. The height of V25 in the linear type was between the concave and convex ones with the tail falling in a linear fashion.

Adult↗
PubMed1997

[Long-term results of small cell lung cancer treated by surgery combined with postoperative chemotherapy: a report of 65 patients].

OBJECTIVE: To analyse the long term results of small cell lung cancer (SCLC) treated by surgery combined with postoperative chemotherapy. METHODS: From 1983 to 1994, 65 patients with SCLC were treated by surgery combined with postoperative chemotherapy, and 22 of them received prophylactic cranial irradiation. RESULTS: In 64 evaluable patients, the overall 1-, 3- and 5-year survival rates were 87.5%, 53.2% and 36.3%. Patients treated by radical operation plus chemotherapy gave 1-, 3- and 5-year survival rates of 92.5%, 58.5% and 43.8%. The prognostic surviving factors as analysed showed that statistical differences were observed between stage I and II, I and III A (P < 0.03), N0 and N1 (P < 0.021) in 3-year survival rate, between 2-3 and 4-6 cycle chemotherapy in 1-year survival rate (P < 0.007). CONCLUSION: Surgery combined with postoperative chemotherapy and radiotherapy is preferred for stages I and II, N0 and N1 lesions of SCLC.

Adult↗
PubMed1997

[Inhibition of parvovirus H-1 on transplantable human hepatoma and its histological and histobiochemical studies].

A transplantable human hepatoma model, the QGY-9204, was used in this study. The growth kinetics of hepatoma in nude mice were compared after injection of parvovirus H-1 into the tumor growth. Significant difference in growth curves were seen between injected groups with H-1 dosages of 5 x 10(7) PFU and 5 x 10(8) PFU and that of control. It indicated that parvovirus H-1 was capable of suppressing the growth of human hepatoma. Previous studies showed H-1 is oncotropic, oncosuppressive and oncolytic. For histological, ultrastructural and histochemical examinations, transplantable hepatomas were taken at different time interval post H-1 (1 x 10(8) PFU per tumor growth) injection. For H-1 DNA amplification and H-1 nonstructural protein expression, PCR and ABC approach in hepatoma paraffin sections were used. The H-1 treated groups exhibited obvious signs of necrosis. It started on 3rd day post infection (3 d.p.i.) and the area of necrosis enlarged consecutively on 7 d.p.i., 10 d.p.i. and 14 d.p.i., but none was seen in saline-injected group even on 14 d.p.i. H-1 virions were also detected in the damaged tumor cells with numerous vacuoles in cytoplasm. Specific band (908 bp) of H-1 DNA and ABC immunostaining indicated H-1 DNA replication and NS-1 expression in tumors of treated groups, their time course was well in accordance with that process of necrosis. These results suggest that parvovirus H-1 promotes tumor necrosis by its DNA replication and cytotoxic NS-1 protein expression, and thus, it inhibits hepatoma growth and induces oncosuppression and oncolysis.

Animals↗
PubMed1997

[Preliminary evaluation of plastic crown restoration supported by osseointegrated implants].

This study was to evaluate the feasibility of plastic crown restoration supported by osseointegrated implants. The following conclusions were drawn from this study: plastic crown gave better biomechanical consideration than porcelain fused to metal (PFM) crown in osseointegrated prostheses, but plastic crown gave worse wearability, tensile strength, compression strength and flexuaral strength than PFM crown. After restoration the disadvantages of the plastic crown were beyond the clinical acceptable range. It showed plastic crown designed dental prothetic implantation was unfeasible.

Crowns↗
PubMed1997

[The study on analgesic effect of local-release delivery system--Huangjiabang].

Laboratory investigation was made on analgesic effect of local release delivery system, Huangjiabang, which mainly includes Chinese medical herbs. Through the application of twisting-body and thermal-plate experiments on white rats. The result showed that the pain threshold was markedly elevated (P < 0.05, P < 0.001) after the rats were fed with Huangjiabang 125 mg/kg or 250 mg/kg body weight, and the number of twisting body's animals significantly decreased (P < 0.001). The analgestic mechanism of Huangjiabang delivery system relates to its effect of invigorating the circulation of blood and accelerating the stasis assimilation, remitting the inflammation.

Analgesics, Non-Narcotic↗