Biomedical subjects

Zhigang Zhang

Publications and source records attributed to Zhigang Zhang.

At least 19 recordsLinked to original sources

PubMed2026

Safety and efficacy of distal versus conventional radial artery cannulation for invasive blood pressure monitoring: a systematic review and meta-analysis.

To compare the safety and effectiveness of distal radial artery (DRA) versus conventional radial artery (CRA) catheterization for invasive arterial blood pressure monitoring. This meta-analysis followed PRISMA guidelines. Randomized controlled trials published up to December 30, 2025 were systematically searched in PubMed, Embase, Web of Science, the Cochrane Library, CINAHL, CNKI, Wanfang, VIP, and SinoMed. Two reviewers independently screened studies, extracted data, and assessed risk of bias. Meta-analyses were conducted using Review Manager 5.4 and Stata 18.0, and evidence quality was evaluated with the GRADE system. 12 randomized controlled trials (RCTs) involving 1,790 participants were included. For the primary outcomes, compared with CRA, DRA was associated with lower incidences of haematoma (RR = 0.42, 95% CI: 0.24-0.73), catheter blockage (RR = 0.33, 95% CI: 0.14-0.81), and bleeding (RR = 0.25, 95% CI: 0.11-0.59), but a longer catheter insertion time (MD = 26.89, 95% CI: 5.28-48.50). For the secondary outcomes, DRA was associated with a shorter haemostasis time and reduced waveform instability, with no significant differences in first-attempt success rate or pain scores. Subgroup analysis showed a higher first-attempt success rate in patients aged ≤ 65 years (RR = 1.14, 95% CI: 1.02-1.28). DRA catheterization for invasive arterial blood pressure monitoring appears to be associated with fewer complications and more stable arterial waveform acquisition than CRA catheterization, despite a longer insertion time. DRA may represent a feasible alternative in surgical and intensive care settings; however, further high-quality studies are needed to confirm its long-term safety and generalizability.

Humans↗

PubMed2007

Regression analysis of failure time data with informative interval censoring.

Interval censoring arises when a subject misses prescheduled visits at which the failure is to be assessed. Most existing approaches for analysing interval-censored failure time data assume that the censoring mechanism is independent of the true failure time. However, there are situations where this assumption may not hold. In this paper, we consider such a situation in which the dependence structure between the censoring variables and the failure time can be modelled through some latent variables and a method for regression analysis of failure time data is proposed. The method makes use of the proportional hazards frailty model and an EM algorithm is presented for estimation. Finite sample properties of the proposed estimators of regression parameters are examined through simulation studies and we illustrate the method with data from an AIDS study.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Persisters: a distinct physiological state of E. coli.

BACKGROUND: Bacterial populations contain persisters, phenotypic variants that constitute approximately 1% of cells in stationary phase and biofilm cultures. Multidrug tolerance of persisters is largely responsible for the inability of antibiotics to completely eradicate infections. Recent progress in understanding persisters is encouraging, but the main obstacle in understanding their nature was our inability to isolate these elusive cells from a wild-type population since their discovery in 1944. RESULTS: We hypothesized that persisters are dormant cells with a low level of translation, and used this to physically sort dim E. coli cells which do not contain sufficient amounts of unstable GFP expressed from a promoter whose activity depends on the growth rate. The dim cells were tolerant to antibiotics and exhibited a gene expression profile distinctly different from those observed for cells in exponential or stationary phases. Genes coding for toxin-antitoxin module proteins were expressed in persisters and are likely contributors to this condition. CONCLUSION: We report a method for persister isolation and conclude that these cells represent a distinct state of bacterial physiology.

Anti-Bacterial Agents↗

PubMed2006

Evidence that the human cytomegalovirus IE2-86 protein binds mdm2 and facilitates mdm2 degradation.

Levels of the p53 tumor suppressor protein are increased in human cytomegalovirus (HCMV)-infected cells and may be important for HCMV pathogenesis. In normal cells p53 levels are kept low due to an autoregulatory feedback loop where p53 activates the transcription of mdm2 and mdm2 binds and ubiquitinates p53, targeting p53 for proteasomal degradation. Here we report that, in contrast to uninfected cells, mdm2 was undetectable upon treatment of infected fibroblasts with the proteasome inhibitor MG132. Cellular depletion of mdm2 was reproducible in p53-null cells transfected with the HCMV IE2-86 protein, but not with IE172, independently of the endogenous mdm2 promoter. IE2-86 also prevented the emergence of presumably ubiquitinated species of p53. The regions of IE2-86 important for mdm2 depletion were those containing the sequences corresponding to the putative zinc finger and C-terminal acidic motifs. mdm2 and IE2-86 coimmunoprecipitated in transfected and infected cell lysates and in a cell-free system. IE2-86 blocked mdm2's p53-independent transactivation of the cyclin A promoter in transient-transfection experiments. Pulse-chase experiments revealed that IE2-86 but not IE1-72 or several loss-of-function IE2-86 mutants increased the half-life of p53 and reduced the half-life of mdm2. Short interfering RNA-mediated depletion of IE2-86 restored the ability of HCMV-infected cells to accumulate mdm2 in response to proteasome inhibition. Taken together, the data suggest that specific interactions between IE2-86 and mdm2 cause proteasome-independent degradation of mdm2 and that this may be important for the accumulation of p53 in HCMV-infected cells.

Amino Acid Sequence↗

PubMed2006

[The effect of the size of tonsil on uvulopalatopharyngoplasty].

OBJECTIVE: To investigate how the size of tonsil affects the curative effect of patients with obstructive sleep apnea hypopnea syndrome (OSAHS) treated with Uvulopalatopharyngoplasty (UPPP). METHOD: Fifty-four cases with OSAHS treated with UPPP in our department were analyzed retrospectively. The polysomnography (PSG) was examined again one years or longer after operation. RESULT: There was no statistical difference between different tonsil size groups in age, apnea-hypopnea index (AHI), body mass index (BMI) and the lowest Pulse Oxygen Saturation (lowest SpO2) before operation. But there was a statistical difference in curative effect after operation between groups. The lowest SpO2 raised obviously in groups with bigger tonsils. In serious OSAHS group, there was a statistical difference in the composing of tonsil size grade in different curative effect groups. CONCLUSION: Patients with bigger size of tonsil will receive a better result after UPPP while the lowest SpO2 will be improved more prominent. To serious OSAHS, we should treat them individually.

Adult↗

PubMed2006

[Salt resistance and its mechanism of cucumber under effects of exogenous chemical activators].

With root injection and foliar spray, this paper studied the effects of different concentrations salicylic acid, brassinolide, chitosan and spermidine on the growth, morphogenesis, and physiological and biochemical characters of cucumber ( Cucumis sativus L. ) seedlings under 200 mmol x L(-1) NaCl stress. The results showed that at proper concentrations, these four exogenous chemical activators could markedly decrease the salt stress index and mortality of cucumber seedlings, and the decrement induced by 0. 01 mg x L (-1) brassinolide was the largest, being 63. 0% and 75. 0% , respectively. The activities of superoxide dismutase (SOD) , peroxidase (POD) and catalase (CAT) increased significantly, resulting in a marked decrease of malondialdehyde (MDA) content and electrolyte leakage. The dry weight water content and morphogenesis of cucumber seedlings improved, and the stem diameter, leaf number, and healthy index increased significantly. All of these suggested that exogenous chemical activators at proper concentrations could induce the salt resistance of cucumber, and mitigate the damage degree of salt stress. The salt resistance effect of test exogenous chemical activators decreased in the sequence of 0.005 -0.05 mg (L-1) brassinolide, 150 -250 mg x L (-1) spermidine, 100 -200 mg x L(-1) chitosan, and 50 -150 mg x L(-1) salicylic acid.

Brassinosteroids↗

PubMed2005

Human cytomegalovirus-inhibitory flavonoids: studies on antiviral activity and mechanism of action.

We report antiviral activity against human cytomegalovirus for certain dietary flavonoids and their likely biochemical mechanisms of action. Nine out of ten evaluated flavonoids blocked HCMV replication at concentrations that were significantly lower than those producing cytotoxicity against growing or stationary phase host cells. Baicalein was the most potent inhibitor in this series (IC(50)=0.4-1.2 microM), including positive control ganciclovir. Baicalein and genistein were chosen as model compounds to study the antiviral mechanism(s) of action for this series. Both flavonoids significantly reduced the levels of HCMV early and late proteins, as well as viral DNA synthesis. Baicalein reduced the levels of HCMV immediate-early proteins to nearly background levels while genistein did not. The antiviral effects of genistein, but not baicalein, were fully reversible in cell culture. Pre-incubation of concentrated virus stocks with either flavonoid did not inhibit HCMV replication, suggesting that baicalein did not directly inactivate virus particles. Baicalein functionally blocked epidermal growth factor receptor tyrosine kinase activity and HCMV nuclear translocation, while genistein did not. At 24h post infection HCMV-infected cells treated with genistein continued to express immediate-early proteins and efficiently phosphorylate IE1-72. However, HCMV induction of NF-kappaB and increases in the levels of cell cycle regulatory proteins--events that are associated with immediate-early protein functioning--were absent. The data suggested that the primary mechanism of action for baicalein may be to block HCMV infection at entry while the primary mechanism of action for genistein may be to block HCMV immediate-early protein functioning.

Antiviral Agents↗

PubMed2005

An optimized molecular potential for carbon dioxide.

An optimized molecular potential model for carbon dioxide is presented in this paper. Utilizing the established techniques of molecular-dynamics and histogram reweighting grand canonical Monte Carlo simulations, this model is demonstrated to show excellent predictability for thermodynamic, transport, and liquid structural properties in a wide temperature-pressure range with remarkable accuracies. The average deviations of this new model from experimental data for the saturated liquid densities, vapor densities, vapor pressures, and heats of vaporization are around 0.1%, 2.3%, 0.7%, and 1.9%, respectively. The calculated critical point is almost pinpointed by the new model. The experimental radial distribution functions ranging from 240.0 to 473.0 K are well reproduced as compared to neutron-diffraction measurements. The predicted self-diffusion coefficients are in good agreement with the nuclear-magnetic-resonance measurements. The previously published potential models for CO2 are also systematically evaluated, and our proposed new model is found to be superior to the previous models in general.

Journal Article↗

PubMed2005

Statistical analysis of current status data with informative observation times.

Current status data arise when each study subject is observed only once and the survival time of interest is known only to be either less or greater than the observation time. Such data often occur in, for example, cross-sectional studies, demographical investigations and tumorigenicity experiments and several semi-parametric and non-parametric methods for their analysis have been proposed. However, most of these methods deal only with the situation where observation time is independent of the underlying survival time completely or given covariates. This paper discusses regression analysis of current status data when the observation time may be related to the underlying survival time and inference procedures are presented for estimation of regression parameters under the additive hazards regression model. The procedures can be easily implemented and are applied to two motivating examples.

2-Acetylaminofluorene↗

PubMed2005

[Clinical review of thirty-nine cases of ulnar tunnel syndrome].

OBJECTIVE: To discuss the concept of ulnar tunnel at the wrist, the types, causes, traits of compression, diagnosis, and clinical significance of ulnar tunnel syndrome (UTS). METHODS: Thirty-nine cases diagnosed as having UTS from 1986 were retrospectively reviewed combined with previous relevant literature. RESULTS: Ulnar tunnel included Guyon's canal, piso-hamate tunnel and hypothenar segment. There were 8 types and many causes of UTS. Some patients had compression in more than one zones and might be associated with carpal tunnel syndrome or cubital tunnel syndrome. UTS could be diagnosed through clinical manifestations and electrophysiological examination. CONCLUSION: Defining the concept of ulnar tunnel and the knowledge of the complexity and rarity of UTS can effectively guide diagnosis and treatment.

Adolescent↗

PubMed2005

[Clinical classification and treatment of localized attic cholesteatoma].

OBJECTIVE: To investigate the clinical classification and treatment of localized attic cholesteatoma through surgical management. METHOD: Twenty-one patients (21 ears) of localized attic cholesteatoma accepted atticotomy. Then different surgical managements were carried out according to the extent of cholesteatoma and whether the malleo-incudal joint was destroyed or not. If the cholesteatoma has only reached the surface of the malleo-incudal joint, it was regarded as type I (5 patients). To this type, the cholesteatoma was removed and the ossicular chain was preserved. If the cholesteatoma has entered the anterior attic space and destroyed the malleo-incudal joint, it was regarded as type II (16 patients). Besides the removing of cholesteatoma, the head of malleus and incus should be removed also in this condition. Then reconstruction of the ossicular chain was performed by putting PORP artificial auditory ossicles between the manubrium mallei and staple. In all these 21 patients, the lateral wall of attic was reconstructed with the cartilage of tragus. The perichondrium of the cartilage was used to repair the perforation in the non-vibrant membrane. Healing of the lateral wall of attic and the tympanic membrane and recovery of hearing level were investigated after the operation. RESULT: The follow-up period lasted 1 year to 5 years. Healing of the lateral wall of attic and the tympanic membrane were satisfying in all 21 patients. According to the pure tone audiometry after the operation, A-B gap was less than 10 decibel in 10 patients,less than 20 decibel in 7 patients, less than 30 decibel in 3 patients, and over 30 decibel in only 1 patient. Acoustic transmission function was preserved or reconstructed. No vertigo or tinnitus happened after operation. CONCLUSION: Diagnosis of localized attic cholesteatoma should be made early. If it can be treated by clinical classification properly, not only the removing of cholesteatoma, but also the reservation and recovery of acoustic transmission function can be obtained. It is worthy of further discussion.

Adolescent↗

PubMed2004

Characterization of an NBS-LRR resistance gene homologue from soybean.

Conserved motifs such as the nucleotide-binding site (NBS) were found in many characterized plant disease resistance genes. Based on the NBS domain, resistance gene analogs have been isolated in our previous study and were used as probes to screen a soybean (Glycine max) cDNA library. A full-length cDNA, KR4, was isolated by screening the library and rapid amplification of cDNA ends method. Sequence analysis revealed that the cDNA was 3818 bp in length and the open reading frame coded for a polypeptide of 1211 amino acids with an NBS and five leucine-rich repeats domains, which were identified by Pfam protein analysis. Sequence alignment showed that KR4 was similar to 12 protein of tomato. Southern analysis indicated that the KR4 gene had low copies in soybean genome and it was mapped on the molecular linkage group E. Its expression was also investigated and it was found that KR4 was induced by exogenous salicylic acid and responded upon infection of soybean mosaic virus strain N3.

Amino Acid Sequence↗

PubMed2004

Regulation of the stability of P-glycoprotein by ubiquitination.

Ubiquitination plays a crucial role in regulating protein turnover. Here we show that ubiquitination regulates the stability of the MDR1 gene product, P-glycoprotein, thereby affecting the functions of this membrane transporter that mediates multidrug resistance. We found that P-glycoprotein was constitutively ubiquitinated in drug-resistant cancer cells. Transfection of multidrug-resistant cells with wild-type ubiquitin or treatment with an N-glycosylation inhibitor increased the ubiquitination of P-glycoprotein and increased P-glycoprotein degradation. Carbobenzoxy-L-leucyl-L-leucyl-L-leucinal (MG-132), a proteasome inhibitor, induced accumulation of ubiquitinated P-glycoprotein, suggesting the involvement of the proteasome in the turnover of the transporter. Treatment of multidrug-resistant cells with 12-O-tetradecanoylphorbol-13-acetate, a phorbol ester that increases the phosphorylation of P-glycoprotein through activation of protein kinase C, or substituting phosphorylation sites of P-glycoprotein by nonphosphorylatable residues did not affect the ubiquitination of the transporter. Enhanced ubiquitination of P-glycoprotein resulted in a decrease of the function of the transporter, as demonstrated by increased intracellular drug accumulation and increased cellular sensitivity to drugs transported by P-glycoprotein. Our results indicate that the stability and function of P-glycoprotein can be regulated by the ubiquitin-proteasome pathway and suggest that modulating the ubiquitination of P-glycoprotein might be a novel approach to the reversal of drug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

[Relationship between tibia callus diameter ratio and prognosis during tibia lengthening].

OBJECTIVE: To investigate the relationship between the tibia callus diameter ratio (CDR) and prognosis during tibial distraction and the occurrence of late deformity or fracture. METHODS: We measured tibial lengthening callus diameter and added up the cases of angular deformity and fracture in 68 cases from January 1996 to December 2001, to calculated callus diameter ratios and compare the relationship between the tibia callus diameter during tibial distraction and the occurrence of late callus angular deformity or fracture. RESULTS: In 23 cases of CDR < 80%, 13 cases had new bone fracture, 21 cases had angular deformity > 5 degree. In 6 cases of 81% < CDR < 85%, there were 4 cases of angular deformity > 5 degree. In the other 39 cases of CDR > 85%, there were no fracture and angular deformity. CONCLUSION: When the CDR was > 85%, there were no angular deformity and fracture, but when the CDR was < 80%, the complications of fracture and angular deformity occur. CDR is a better alarming index for preventing the complications occurring in tibial lengthening.

Adolescent↗

PubMed2003

Optical pulse compression to 3.4 fs in the monocycle region by feedback phase compensation.

We compensated for chirp of optical pulses with an over-one-octave bandwidth (495-1090 nm; center wavelength of 655.4 nm) produced by self-phase modulation in a single argon-filled hollow fiber and generated 3.4-fs, 1.56 optical-cycle pulses (500 nJ, 1-kHz repetition rate). This was achieved with a feedback system combined with only one 4-f phase compensator with a spatial light modulator and a significantly improved phase characterizer based on modified spectral phase interferometry for direct electric-field reconstruction. To the best of our knowledge, this is the shortest pulse in the visible-to-infrared region.

Journal Article↗

PubMed2003

Passive mode locking of a diode-end-pumped Nd:GdVO4 laser with a semiconductor saturable absorber mirror.

We report an end-pumped and passive mode-locking all-solid-state laser. The laser consists of a Nd:GdVO4 crystal and a linear resonator with a semiconductor saturable absorber mirror that yield mode locking. We achieved stable continuous-wave mode locking with an 8-ps pulse duration at a 154-MHz repetition rate. The average output power was 600 mW with 4 W of pump power. To our knowledge this is the first report of the use of a Nd:GdVO4 crystal for mode locking with a semiconductor saturable absorber mirror.

Journal Article↗

PubMed2003

Interactions between human cytomegalovirus IE1-72 and cellular p107: functional domains and mechanisms of up-regulation of cyclin E/cdk2 kinase activity.

Previous work has demonstrated that the human cytomegalovirus IE1-72 protein is able to bind to the N terminus of p107, and IE1-72 alone is sufficient for alleviation of p107-mediated cell growth suppression. However, the mechanism of this alleviation is unclear. Here, we show that IE1-72 can alleviate p107 inhibition of cyclin E/cdk2 kinase activity. We cotransfected various IE1-72 and p107 constructs into C33A cells and demonstrated that IE1-72 could activate the kinase activity of cyclin E/cdk2. Conversely, IE2-86 did not activate this activity, suggesting that the interaction between p107 and IE1-72 and the subsequent kinase activation are specific. By the use of a series of deletion and point mutants of IE1-72 and p107, we observed that a mutation of the loop region of helix-loop-helix-turn-helix in exon 3 of IE1-72 as well as a mutation of the leucine zipper-2 region in exon 4 of IE1-72 abolished binding to p107. In addition, these two IE1-72 mutants did not alleviate p107 inhibition of cyclin E/cdk2 kinase activity and also failed to alleviate p107 inhibition of the E2F-responsive promoter. Meanwhile, deletion of the N-terminal aa 1 to 175 of p107 abolished both p107 binding with IE1-72 and p107 inhibition of cyclin E/cdk2 kinase activity. This result confirms that the N-terminus aa 1 to 175 region of p107 is a common region where both IE1-72 protein and cyclin E/cdk2 bind. We propose a mechanism in which binding of IE1-72 to p107 displaces cyclin E/cdk2 from p107. Once released from p107, cyclin E/cdk2 is able to function as an active kinase.

Base Sequence↗

PubMed2002

Urinary type IV collagen: a specific indicator of incipient diabetic nephropathy.

OBJECTIVE: To determine whether urinary type IV collagen can serve as an indicator specific for diabetic nephropathy. METHODS: Using a novel sandwich ABC-ELISA to measure type IV collagen directly, the 24-hour urinary type IV collagen excretion rate was determined in 120 diabetic patients and some groups of controls. Urinary albumin determinations were made with a RIA kit at the same time. A total of 13 diabetic patients with microalbuminuria underwent percutaneous renal biopsy for definitive diagnosis of diabetic nephropathy. Type IV collagen and TGF-beta 1 immunoreactivities were detected with ABC methods in renal biopsies. RESULTS: Urinary type IV collagen excretion was significantly increased in diabetic patients with microalbuminuria, especially those with albumin excretion above 200 mg/24 h. By comparison, collagen excretion was equivalent to that in healthy controls when measured in diabetics with normalbuminuria and in patients with primary glomerular disease, primary hypertension, or coronary heart disease. Urinary type IV collagen excretion in diabetics was negatively correlated with creatinine clearance. In renal biopsies from subjects with elevated collagen excretion, the glomeruli showed pathological changes typical of diabetic nephropathy. Also, excessive type IV collagen and TGF-beta 1 immunoreactivity were detected in the glomeruli, Bowman's capsule and interstitium. CONCLUSIONS: Excretion of type IV collagen, possibly reflecting increased production or decreased degradation of this protein, may be a clinically useful indicator of incipient diabetic nephropathy.

Albuminuria↗