Biomedical subjects

Yu Zheng

Publications and source records attributed to Yu Zheng.

At least 19 recordsLinked to original sources

PubMed2026

Reprogrammed Komagataella phaffii for enhanced secretory expression of human lactoferrin.

Human lactoferrin (hLF) is a multifunctional glycoprotein of the transferrin family derived from milk and mucosal secretions, which exhibits antibacterial, anti-tumor, and immunomodulatory functions, and is an important component of infant formula. Conventional methods for lactoferrin expression are often inefficient, primarily due to inadequate protein synthesis capabilities and poor stability within microbial hosts. Herein, a Komagataella phaffii yeast strain capable of high-level secretory expression of hLF was constructed by reprogramming the endoplasmic reticulum (ER) and vacuole using CRISPR/Cas9 technology. A dual-expression cassette containing the AOX1 promoter, an α-secretion signal peptide, the hLF gene, and a terminator was integrated into three different sites of the K. phaffii genome. The stepwise strategy combining expansion of the ER membrane involved in protein synthesis with knockout of vacuolar proteases further enhanced hLF production. Subsequently, 0.1 g/L FeCl₃ was added to the medium to reduce the toxicity of hLF and improve its stability. After high-density cultivation of K. phaffii through optimization of cultivation conditions in shake flasks and a 5 L bioreactor, the secretory intact hLF titer reached 2214 mg/L, representing a 76.3-fold increase achieved through these engineering strategies. In addition, antibacterial experiments demonstrated that this secretory hLF had a significant inhibitory effect on Escherichia coli, Staphylococcus aureus, and yeast. Overall, the developed K. phaffii protein expression platform enabled efficient production of lactoferrin, demonstrating its potential for expressing other lactoproteins.

Lactoferrin↗

PubMed2025

Synostosis of joints caused by mutant FBN2 is linked to the abnormalities and misdifferentiation of articular surface cells.

PURPOSE: FBN2, a high-confidence effector gene for osteoarthritis (OA), was investigated for its potential role in synostosis of joints (SJ) because several OA-related genes are known to cause SJ. METHODS: We analyzed variants in OA-related genes using exome sequencing data from Chinese-Han participants with radioulnar synostosis (RUS). Variants were classified following American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines. Fbn2 knockout mice were generated via CRISPR/Cas9 and evaluated through radiological and histopathological analyses at multiple developmental stages, with complementary cellular and molecular studies. RESULTS: We identified 15 rare, damaging FBN2 variants in unrelated RUS families, including 7 likely pathogenic variants (4 null variants). Fbn2 knockout mice (both homozygous and heterozygous) exhibited SJ phenotypes. Unlike previously reported SJ mechanisms involving failed interzone formation, Fbn2-related SJ occurred after normal interzone formation. Mutant mice showed significant alterations in extracellular matrix composition and volume within articular surface cells. We proposed that these extracellular matrix changes mediated the transdifferentiation of articular surface cells into osteoblasts, which ultimately developed into bones over time. CONCLUSION: We identified FBN2 pathogenic variants that caused SJ in humans and mice. SJ caused by mutant FBN2 is linked to the abnormalities and misdifferentiation of articular surface cells.

Fibrillin-2↗

PubMed2024

Application of third-generation sequencing technology for identifying rare α- and β-globin gene variants in a Southeast Chinese region.

BACKGROUND: Third-generation sequencing (TGS) based on long-read technology has been gradually used in identifying thalassemia and hemoglobin (Hb) variants. The aim of the present study was to explore genotype varieties of thalassemia and Hb variants in Quanzhou region of Southeast China by TGS. METHODS: Included in this study were 6,174 subjects with thalassemia traits from Quanzhou region of Southeast China. All of them underwent common thalassemia gene testing using the DNA reverse dot-blot hybridization technology. Subjects who were suspected as rare thalassemia carriers were further subjected to TGS to identify rare or novel α- and β-globin gene variants, and the results were verified by Sanger sequencing and/or gap PCR. RESULTS: Of the 6,174 included subjects, 2,390 (38.71%) were identified as α- and β-globin gene mutation carriers, including 40 carrying rare or novel α- and β-thalassemia mutations. The αCD30(-GAG)α and Hb Lepore-Boston-Washington were first reported in Fujian province Southeast China. Moreover, the βCD15(TGG> TAG), βIVS-II-761, β0-Filipino(~ 45 kb deletion), and Hb Lepore-Quanzhou were first identified in the Chinese population. In addition, 35 cases of Hb variants were detected, the rare Hb variants of Hb Jilin and Hb Beijing were first reported in Fujian province of China. Among them, one case with compound αααanti3.7 and Hb G-Honolulu variants was identified in this study. CONCLUSION: Our findings may provide valuable data for enriching the spectrum of thalassemia and highlight the clinical application value of TGS-based α- and β-globin genetic testing.

Humans↗

PubMed2006

Multiple system utilization and mortality for veterans with stroke.

BACKGROUND AND PURPOSE: Many Veteran Health Administration (VHA) enrollees receive health services outside the VHA system. However, limited information is available about poststroke utilization and mortality by veterans who used multiple sources of health care. This study assessed the likelihood of 12-month poststroke rehospitalization and mortality of veterans who used VHA only versus those who used multiple sources of care. METHODS: Our retrospective observational study examined veterans living in Florida and diagnosed with acute stroke. We categorized users into 4 groups: VHA-only, VHA-Medicare, VHA-Medicaid, and VHA-Medicare-Medicaid based on their use of each health care program. Logistic regression models were fitted for 12-month poststroke general rehospitalization, recurrent stroke readmission, and mortality, adjusting for sociodemographic and clinical factors. RESULTS: The sample consisted of 29% VHA-only users, 61% VHA-Medicare users, 3% VHA-Medicaid users, and 7% VHA-Medicare-Medicaid triple users. Compared with the VHA-only users, multiple system users were significantly more likely to be rehospitalized for any cause and for recurrent stroke 12-months postindex. Mortality outcomes depended on when the outcome was measured; at the index admission date, we found no significant difference in mortality across the user groups; at the index discharge date, the VHA-only users was less likely to die within the first 12 months than the users of the 2 dual groups (VHA-Medicare and VHA-Medicaid). CONCLUSIONS: Multiple health care source use was common among VHA enrollees with acute stroke in Florida. Multiple system users were more likely to be rehospitalized and the mortality outcomes were dependent on when the outcome was measured.

Aged↗

PubMed2006

Inhibition of bone resorption, rather than direct cytotoxicity, mediates the anti-tumour actions of ibandronate and osteoprotegerin in a murine model of breast cancer bone metastasis.

Inhibition of bone resorption either by bisphosphonate (BP) treatment or by blocking RANKL signalling with osteoprotegerin (OPG) has been shown to reduce tumour burden in bone and inhibit bone destruction in murine xenograft models of breast cancer. However, whether the anti-tumour effect of OPG or BP in bone is mediated by inhibition of bone resorption or by direct effects on tumour cells is uncertain. The current study is designed to investigate anti-tumour effects of OPG and ibandronate (IBN), dosed alone or in combination, on tumour growth to determine if there is experimental support for combination treatments and to provide evidence for the presence of direct anti-tumour effects. To this aim, 10 microl (5 x 10(6) cells/ml) of the bone-seeking MDA-MB-231 (Tx-SA) cell line was injected intra-tibially into nude mice. After 10 days, when the tumours were evident radiologically, mice were treated with vehicle, OPG (1 mg/kg/day), ibandronate (IBN) (160 microg/kg/day) or IBN and OPG at the same doses (IBN+OPG) for a week, and the effects of each treatment on lytic lesions, tumour cell growth, cell apoptosis and proliferation were measured by radiography, immunohistochemistry and histomorphometry. Compared to vehicle controls, in vivo treatment with OPG, IBN, or IBN+OPG, each prevented the expansion of osteolytic bone lesions (increase in lytic lesion area day 10 to day 17: OPG -3.2%, IBN 6.6%, IBN+OPG 3.6%, Vehicle 232.5%; p<0.01). Treatment with OPG, IBN or IBN+OPG each produced similar reductions in tumour area relative to vehicle-treated mice (OPG 52%, IBN 54%, IBNp and OPG 48%, p<0.01 vs. vehicle) OPG and IBN alone and in combination each produced a similar increase in cancer cell apoptosis (OPG 330%, IBN 342%, IBN and OPG 347%, p<0.01 vs. vehicle) and a decrease in cancer cell proliferation (OPG 59%, IBN 62%, IBN and OPG 58%, p<0.05 vs. vehicle). Our findings indicate that (i) combined treatment with OPG and a bisphosphonate is not significantly more effective than either agent alone; and that (ii) inhibition of bone resorption, rather than direct anti-tumour action, mediates the effects of these agents on tumour growth in this in vivo model.

Animals↗

PubMed2006

A new rat model of acute seizures induced by tutin.

Coriaria Lactone (CL) is a mixture that has been used to establish animal models of epilepsy. In this study, we focused on the epileptogenic action of tutin, a pure chemical component derived from CL. Rats were implanted with a guide cannula for microinjection of tutin into either of the lateral cerebral ventricles. Behavioral and electroencephalographic (EEG) changes were investigated for at least 2 h after tutin administration. Injected animals presented behavioral seizures: initially, facial and limbic clonus, and subsequently, tonic-clonic seizures that eventually progressed to status epilepticus. Accompanying the behavioral activities, a variety of EEG patterns were recorded. Spike-and-wave complexes occurred continuously at 3 Hz, with a mean amplitude of approximately 295 microV. Multiple spikes and slow waves occurred repetitively and became more frequent and intense. The amplitude of this EEG pattern was low (approximately 85 microV) at onset and gradually increased to approximately 200 microV. Spikes (8 Hz, approximately 555 microV) and slow waves (3 Hz, approximately 670 microV) occurred periodically at the onset of grand mal seizures. Behavioral and EEG changes induced in rats by tutin demonstrated that this is a potent convulsant, by which a new animal model of status epilepticus was established. This acute seizure model is productive and would be optional for investigation of seizures or status epilepticus.

Action Potentials↗

PubMed2006

A new strategy for structure determination of large proteins in solution without deuteration.

So far high-resolution structure determination by nuclear magnetic resonance (NMR) spectroscopy has been limited to proteins <30 kDa, although global fold determination is possible for substantially larger proteins. Here we present a strategy for assigning backbone and side-chain resonances of large proteins without deuteration, with which one can obtain high-resolution structures from (1)H-(1)H distance restraints. The strategy uses information from through-bond correlation experiments to filter intraresidue and sequential correlations from through-space correlation experiments, and then matches the filtered correlations to obtain sequential assignment. We demonstrate this strategy on three proteins ranging from 24 to 65 kDa for resonance assignment and on maltose binding protein (42 kDa) and hemoglobin (65 kDa) for high-resolution structure determination. The strategy extends the size limit for structure determination by NMR spectroscopy to 42 kDa for monomeric proteins and to 65 kDa for differentially labeled multimeric proteins without the need for deuteration or selective labeling.

Carrier Proteins↗

PubMed2006

Augmented locomotor recovery after spinal cord injury in the athymic nude rat.

The immune response contributes to ongoing secondary tissue destruction following spinal cord injury (SCI). Although infiltrating neutrophils and monocytes have been well studied in this process, T-cells have received less attention. The objective of this study was to assess locomotor recovery and tissue morphology after SCI in athymic (nude) rats, in which T-cell numbers are reduced. Results in athymic rats were compared with heterozygote littermates with normal T-cell profiles and with Sprague-Dawley rats from previous studies in our lab. Following transection of rat spinal cords at T10, we assessed the animals' locomotor recovery on a weekly basis for up to 11 weeks, using the Basso-Beattie-Bresnahan locomotor rating scale. Nude rats showed better locomotor recovery than did heterozygote or Sprague-Dawley rats, achieving scores of 5.6 +/- 0.8 versus 1.0 +/- 0.0, respectively (p = 0.002), at 4 weeks postinjury. The improved recovery of nude rats persisted for the 11-week postinjury assessment period, and was consistent with improved spinal reflexes rather than with recovery of descending motor pathways. Anatomical evaluation at 11 weeks indicated no difference in nude versus heterozygote rats in the size or distribution of cavities caudal to the transection site, but secondary damage was more severe rostral to the transection site in heterozygote rats. In neither group did cavities extend beyond 4 mm caudal to the transection site, and were therefore not directly responsible for the functional differences between the two groups. Cellular expression of the microglia/macrophage antigen ectodysplasin A (ED1) was reduced in nude rats as compared to heterozygotes, but no difference was observed in expression levels of 5-hydroxytryptamine, the 200-kDa neurofilament, or glial fibrillary acidic protein. The findings of the study show that a reduction in T-cell numbers significantly improves locomotor recovery after spinal cord transection, indicating a deleterious role for these immune cells in neural repair after trauma.

Animals↗

PubMed2006

A fast procedure for optimizing dynamic force distribution in multifingered grasping.

This correspondence deals with the dynamic force distribution (DFD) problem, i.e., computing the contact forces to equilibrate a dynamic external wrench on the grasped object. The sum of the normal force components is minimized for enhancing safety and saving energy. By this optimality criterion, the DFD problem can be transformed into a linear programming (LP) problem. Its objective function is the inner product of the dynamic external wrench and a vector, and the constraints on the vector, given by a set of linear inequalities, define a polytope. The solution to the LP problem can always be attained at the vertex of the polytope called the solution vertex. We notice that the polytope is determined by the grasp configuration. Along with the direction change of the dynamic external wrench, only the solution vertex moves to an adjacent vertex sequentially, whereas the polytope with all its vertices remains unchanged. Therefore, the polytope and the adjacencies of each vertex can be computed in the offline phase. Then, in the online phase, simply search the adjacencies of the old solution vertex for the new one. Without lost of optimality, such a DFD algorithm runs a thousandfold faster than solving the LP problem by the simplex method in real time.

Fingers↗

PubMed2006

[Effects of acupuncture plus acupoint sticking on bone mass density and pain in the patient of primary osteoporosis].

OBJECTIVE: To observe effects of acupuncture plus acupoint sticking of Migudan on bone mass density (BMD) and pain in the patient of primary osteoporosis. METHODS: By computer random number generating method, the patients were randomly divided into a treatment group treated with acupuncture plus acupoint sticking of Migudan, and a control group treated with Gaitianli, 48 cases in each group. Changes of their BMD and cumulative scores of pain after treatment were investigated. RESULTS: Acupuncture plus acupoint sticking of Migudan could relieve cumulative score of bone pain in the patient of primary osteoporosis as compared with the control group (P 0.01), with 95% CI= 4.05 to approximately 4. 31 points; acupuncture plus acupoint sticking of Migudan could increase significantly BMD in the patients as compared with the control group (P < 0.05), L2 to approximately L4 BMD 95% CI = 0.029 to approximately 0.073 g/cm2, the neck of femur BMD 95% CI = 0.013 to approximately 0.047 g/cm2. CONCLUSION: Acupuncture plus acupoint sticking of Migudan has definite therapeutic effect on primary osteoporosis.

Acupuncture Points↗

PubMed2006

[Effects of acupoint-injection of Kaixilai on TG, TC, MDA, SOD, AST and ALT in the patient of non-alcoholic fatty liver].

OBJECTIVE: To observe therapeutic effect of acupoint-injection of Kaixilai on non-alcoholic fatty liver. METHODS: One hundred cases of non-alcoholic fatty liver were randomly divided into a test group and a control group, 50 cases in each group. The test group were treated with injection of 2 mL Kaixilai injection into Zusanli (ST 36), thrice each week, for 3 months; and the control group were treated with intravenous drip of 200 mL Kaixilai injection, once each day, for 3 months. Changes of triglyceride (TG), total cholesterol (TC), malondialhyde (MDA), superoxide dismutase (SOD), glutamic-oxaloacetic transaminase (AST), glutamic-pyruvic transaminase (ALT), and clinical symptoms were observed in the two groups. RESULTS: There were significant differences before and after treatment in the symptoms, TG, TC, MDA, SOD, AST and ALT in the two groups (P<0.05), with no significant difference between the two groups (P>0.05). CONCLUSION: Acupoint-injection of Kaixilai is an effective therapy for non-alcoholic fatty liver, with convenience, economic and no adverse effect.

Acupuncture Points↗

PubMed2006

[Preparation and characterization of transfersomes of three drugs in vitro].

OBJECTIVE: To investigate the influence of drug properties on the encapsulation effiency (EE) and drug release of transfersomes for a proper transfersome preparation. METHOD: To prepare the transfersomes of colchicines (CLC), vincristine sulfate (VCR) and mitoxantrone hydrochloride (DHAD) with the same materials and methods, and then measure their EE. To find out the relationship between drug properties like solubility, molecular weight and charges, and EE. To performe the drug release experiments of various types of transfersomes in vitro, and compare their differences. RESULT: VCR and DHAD are lipophilic or hydrophilic, owing positive charges and large molecular weight, as a result, their EE are high, while CLC is amphipathic, neutral, and of small molecular weight, its EE is very low. As DHAD can insert into the membrane of transfersome, the drug release of DHAD-T in vitro is much slower than that of VCR-T. CONCLUSION: To prepare transfersomes with high EE, drugs that are lipophilic or hydrophilic, high molecular weight and opposite charges to the membrane should be chosen. Interaction between drugs and membrane will influnce the rate of drug release.

Antineoplastic Agents↗

PubMed2005

Phylogenetic detection of conserved gene clusters in microbial genomes.

BACKGROUND: Microbial genomes contain an abundance of genes with conserved proximity forming clusters on the chromosome. However, the conservation can be a result of many factors such as vertical inheritance, or functional selection. Thus, identification of conserved gene clusters that are under functional selection provides an effective channel for gene annotation, microarray screening, and pathway reconstruction. The problem of devising a robust method to identify these conserved gene clusters and to evaluate the significance of the conservation in multiple genomes has a number of implications for comparative, evolutionary and functional genomics as well as synthetic biology. RESULTS: In this paper we describe a new method for detecting conserved gene clusters that incorporates the information captured by a genome phylogenetic tree. We show that our method can overcome the common problem of overestimation of significance due to the bias in the genome database and thereby achieve better accuracy when detecting functionally connected gene clusters. Our results can be accessed at database GeneChords http://genomics10.bu.edu/GeneChords. CONCLUSION: The methodology described in this paper gives a scalable framework for discovering conserved gene clusters in microbial genomes. It serves as a platform for many other functional genomic analyses in microorganisms, such as operon prediction, regulatory site prediction, functional annotation of genes, evolutionary origin and development of gene clusters.

Algorithms↗

PubMed2005

[Effect of tetramethylpyrazine on the responses of respiration and expression of nNOS in brainstem to hypoxia in rats].

The aim of the present study was to investigate the effect of tetramethylpyrazine (TMP) on the changes of respiration and expression of neuronal nitric oxide synthase (nNOS) in brainstem induced by hypoxia in the rats. Hypoxia was induced by inhalation of 8% O2-balanced N2.The electromyogram (EMG) of diaphragm was monitored to evaluate the respiratory response of the rats to hypoxia. The immunohistochemical staining technique was used to study the change of the expression of nNOS in the brainstem during hypoxia. In the rats of hypoxia group, a successive process of response, excitatory followed by inhibitory, was produced. Twenty min after hypoxia, a significant inhibition of respiration occurred, which was characterized with a marked decrease in the inspiratory duration, the respiratory frequency, and the amplitude of inspiration and a prolongation of expiratory duration (P<0.05). In the rats of pretreated with TMP, the respiratory activity was not obviously depressed (P>0.05). In the rats of hypoxia group, the level of nNOS immunoreactivity was enhanced remarkably in the lateral reticular nucleus, nucleus of trapezoid, hypoglossal nucleus and the facial nucleus compared with the control group (P<0.05). In the rats of pretreated with TMP, the nNOS level increased further in the nuclei mentioned above (P<0.05). The results obtained indicate that TMP can reverse the inhibitory effect of hypoxia on respiration in the rats and that nNOS may be involved in the respiratory protective action of TMP.

Animals↗

PubMed2005

STARS: statistics on inter-atomic distances and torsion angles in protein secondary structures.

UNLABELLED: A graphics package has been developed for performing statistics on interatomic distances and torsion angles in protein secondary structures (STARS) from a protein crystal structure database. It allows one to obtain both the graphical view and the text format of distributions of the distances and angles for atoms located in 10 types of protein secondary structures. STARS will facilitate assignment of ambiguous NOESY peaks, structure determination by nuclear magnetic resonance, structure validation and comparison of protein folds. AVAILABILITY: All data, documents and execute files are freely downloadable at http://stars.zhengyuhome.com. The software works appropriately on Windows system, without any compilation or installation. CONTACT: dbsydw@nus.edu.sg.

Computer Graphics↗

PubMed2005

Effects of removal of necrotic blastomeres from mouse cryopreserved embryos on blastocyst formation and hatching.

To evaluate whether the developmental potential of embryos that were partially damaged after freezing and thawing can be improved by removal of necrotic blastomeres. Eight-cell mouse embryos were cryopreserved using 1,2-propanediol and sucrose as cryoprotectant with slow cooling procedure. After thawing, blastocyst formation and hatching of fully intact embryos were compared between no treatment and with laser-assisted hatching. For partially intact embryos, the effects of removal of necrotic blastomeres with micromanipulation were evaluated. Laser-assisted hatching of mouse cryopreserved fully intact embryos significantly increased blastocyst hatching (63.4% versus 48.3%, P<0.05), but had little effect on blastocyst formation (72.0% versus 70.1%, P>0.05). The removal of necrotic blastomeres from partially damaged mouse cryopreserved embryos with micromanipulation significantly increased blastocyst formation (52.9% versus 32.0%, P<0.05) and blastocyst hatching (41.2% versus 22.0%, P>0.05) compared with the control group. The developmental potential of partially damaged cryopreserved embryos can be improved by removal of necrotic blastomeres with micromanipulation.

Animals↗

PubMed2005

Characterization of two new aminopeptidases in Escherichia coli.

Two genes in the Escherichia coli genome, ypdE and ypdF, have been cloned and expressed, and their products have been purified. YpdF is shown to be a metalloenzyme with Xaa-Pro aminopeptidase activity and limited methionine aminopeptidase activity. Genes homologous to ypdF are widely distributed in bacterial species. The unique feature in the sequences of the products of these genes is a conserved C-terminal domain and a variable N-terminal domain. Full or partial deletion of the N terminus in YpdF leads to the loss of enzymatic activity. The conserved C-terminal domain is homologous to that of the methionyl aminopeptidase (encoded by map) in E. coli. However, YpdF and Map differ in their preference for the amino acid next to the initial methionine in the peptide substrates. The implication of this difference is discussed. ypdE is the immediate downstream gene of ypdF, and its start codon overlaps with the stop codon of ypdF by 1 base. YpdE is shown to be a metalloaminopeptidase and has a broad exoaminopeptidase activity.

Amino Acid Sequence↗

PubMed2005

[Study on an unknown complex by gas chromatography/infrared spectrometry].

If the authors use normal infrared spectrometry, a lot of mixture compounds are difficult to characterize, because most of the peaks are overlapped in the spectra. Gas chromatography/Infrared spectrometry (GC-IR) are widely used in the separation and identification of organic complexes. The GC-IR can characterize the ingredients quickly and correctly that are difficult to do for normal infrared spectrometry. The technique also can be used to quantitatively analyze the ingredients by integral. The authors studied an unknown complex by GC-IR here.

Chromatography, Gas↗