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Biomedical subjects

J Z Huang

Publications and source records attributed to J Z Huang.

18 recordsLinked to original sources
PubMed2001

Identification of a novel phosphorylation motif for CDPKs: phosphorylation of synthetic peptides lacking basic residues at P-3/P-4.

The Ca(2+)-dependent protein kinases (CDPKs) are members of a large subfamily of protein kinases in plants that have been implicated in the control of numerous aspects of plant growth and development. One known substrate of the CDPKs is the ER-located ACA2 calcium pump, which is regulated by phosphorylation of Ser(45). In the present study, a synthetic peptide based on the known regulatory phosphorylation site (RRFRFTANLS(45)KRYEA) was efficiently phosphorylated in vitro by CDPKs but not a plant SNF1-related protein kinase. Phosphorylation of the Ser(45)-ACA2 peptide was surprising because the sequence lacks basic residues at P-3/P-4 (relative to the phosphorylated Ser at position P) that are considered to be essential recognition elements for CDPKs. We demonstrate that phosphorylation of the Ser(45)-ACA2 peptide is dependent on the cluster of basic residues found N-terminal (P-6 to P-9) as well as C-terminal (P + 1/P + 2) to the phosphorylated Ser. The results establish a new general phosphorylation motif for CDPKs: [Basic-Basic-X-Basic]-phi-X(4)-S/T-X-Basic (where phi is a hydrophobic residue). The motif predicts a number of new phosphorylation sites in plant proteins. Evidence is presented that the novel motif may explain the phosphorylation by CDPKs of Ser271 in the aquaporin PM28A.

Amino Acid Motifs↗
PubMed2001

Gene expression analysis in aggressive NHL.

The mRNA expression profile of a tumor reflects the unique genetic alterations present and is predictive of the clinical and biological characteristics of the tumor. Novel techniques have been developed to determine the global gene expression pattern of normal and neoplastic tissues. A cDNA microarray uniquely suitable for the analysis of B-cell non-Hodgkin's lymphomas (B-NHL) has been developed and preliminary analysis on diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL) and B-chronic lymphocytic leukemia (CLL) has been performed. These studies indicate that: 1) it is feasible to determine the gene expression profiles of archival lymphoma samples frozen and stored in a clinical setting, 2) the expression profile of these 3 types of lymphoproliferative disorders are distinctive, 3) DLBCL can be divided into at least 2 major subgroups according to their pattern of expression of B-cell associated genes and 4) the gene expression patterns in DLBCL appear to have prognostic significance. A larger study of DLBCL is currently underway to confirm and extend our findings. Gene expression profiles will be correlated with cytogenetic and clinical data to identify distinctive profiles that are of clinical and biological significance and to delineate key genetic lesions that determine these profiles. The new information will allow the design of a simpler and less expensive array for clinical use. The diagnostic array could provide rapid molecular characterization of every B-NHL at presentation for optimal treatment decisions and prognostication. It is anticipated that this project will advance our understanding of the molecular mechanisms in the neoplastic transformation of B-lymphoid cells and the new insights will help to identify promising molecular targets for therapeutic intervention.

Biomarkers, Tumor↗
PubMed2001

Phosphorylation of synthetic peptides by a CDPK and plant SNF1-related protein kinase. Influence of proline and basic amino acid residues at selected positions.

Spinach (Spinacia oleracea L.) leaf sucrose-phosphate synthase (SPS) can be inactivated by phosphorylation of Ser-158 by calmodulin-like domain protein kinases (CDPKs) or SNF1-related protein kinases (SnRK1) in vitro. While the phosphorylation site sequence is relatively conserved, most of the deduced sequences of SPS from dicot species surrounding the Ser-158 regulatory phosphorylation site contain a Pro residue at P-4 (where P is the phosphorylated Ser); spinach is the exception and contains an Arg at P-4. We show that a Pro at P-4 selectively inhibits phosphorylation of the peptide by a CDPK relative to a SnRK1. The presence of a Pro at P-4, by allowing a tight turn in the peptide substrate, may interfere with proper binding of residues at P-5 and beyond. Both kinases had greater activity with peptides having basic residues at P-6 and P+5 (in addition to the known requirement for an Arg at P-3/P-4), and when the residue at P-6 was a His, the pH optimum for phosphorylation of the peptide was acid shifted. The results are used to predict proteins that may be selectively phosphorylated by SnRK1s (as opposed to CDPKs), such as SPS in dicot species, or may be phosphorylated in a pH-dependent manner.

Amino Acid Sequence↗
PubMed2001

The tumor cells in nodular lymphocyte-predominant Hodgkin disease are clonally related to the large cell lymphoma occurring in the same individual. Direct demonstration by single cell analysis.

Large cell lymphoma (LCL) sometimes occurs concurrently or subsequently in patients with nodular lymphocyte-predominant Hodgkin disease (NLPHD). Although there is evidence of a clonal relationship between LCL and NLPHD, there has been no direct demonstration that the lymphocytic and histiocytic (L&H) cells in NLPHD are related to the tumor cells in LCL. We identified 2 cases of NLPHD with an associated LCL. Single L&H cells, the Reed-Sternberg cell variants in NLPHD, were isolated from immunostained tissue sections by micromanipulation, and the immunoglobulin heavy chain gene (IgH) complementarity determining region (CDR) III of the cells was amplified by the polymerase chain reaction (PCR). The products were compared with those obtained from microdissected LCL cells using polyacrylamide gel electrophoresis and nucleotide sequencing. The IgH CDRIII sequences from the L&H cells were related to each other, but also showed nucleotide substitutions, consistent with a germinal center origin. The sequences from the L&H cells also were related to those from the corresponding LCL cells. We have provided direct evidence through sequence analysis of the IgH CDRIII that the L&H cells are clonally related to the corresponding LCL arising in 2 cases of NLPHD.

Adult↗
PubMed2000

[A study on biological characteristics of normal adult human nasal septal chondrocytes cultured in vitro].

OBJECTIVE: To study the characteristics of normal adult human nasal chondrocytes cultured in vitro. METHOD: The adult human nasal septal chondrocytes were cultured in vitro. The changes of cellular morphology from primary to subculture were investigated; to observe the proliferation of chondrocytes by the growth curve and the survive rate of chondrocytes; and to determine the biologic synthesis of the chondrocytes by toluidine blue, alkaline phosphatase staining and type II collagen immunohistochemistry reaction. The survive rate of the nasal septal chondrocytes was observed after being frozen (-196 degrees C). RESULT: The morphology of the primary chondrocytes maintained the spherical shape, and some became polygonal shape after 4 days. Most of the chondrocytes transformed into the shape of the fibroblast cell since the fifth generation. The number of the chondrocytes (2th generation) after being cultured in vitro for 5 days was approximately 4 fold of that of the plating. The phenotype of the chondrocytes was maintained in the first 4 generation, the survive rate of the chondrocytes suscitating from being frozen (-196 degrees C) was 93%. CONCLUSION: The normal adult nasal septal chondrocytes cultured in monolayer in vitro maintained the specific chondrocytes phenotype in the first 4 generation, the growth was normal, and could survive in the condition of deep-frozen.

Adult↗
PubMed1998

Mutations in the gene encoding gap junction protein beta-3 associated with autosomal dominant hearing impairment.

Hearing impairment is the most commonly occurring condition that affects the ability of humans to communicate. More than 50% of the cases of profound early-onset deafness are caused by genetic factors. Over 40 loci for non-syndromic deafness have been genetically mapped, and mutations in several genes have been shown to cause hearing loss. Mutations in the gene encoding connexin 26 (GJB2) cause both autosomal recessive and dominant forms of hearing impairment. To study the possible involvement of other members of the connexin family in hereditary hearing impairment, we cloned the gene (GJB3) encoding human gap junction protein beta-3 using homologous EST searching and nested PCR. GJB3 was mapped to human chromosome 1p33-p35. Mutation analysis revealed that a missense mutation and a nonsense mutation of GJB3 were associated with high-frequency hearing loss in two families. Moreover, expression of Gjb3 was identified in rat inner ear tissue by RT-PCR. These findings suggest that mutations in GJB3 may be responsible for bilateral high-frequency hearing impairment.

Adult↗
PubMed1996

Study on characteristics of blast-fragment combined injury in dogs.

It is known that blast wave and fragments are the primary causes of casualties from explosive weapons. To study the characteristics of blast-fragment combined injuries, functional and morphological changes were investigated in three groups of anesthetized dogs with blast injury, high velocity fragment extremity injury, and combined injuries of both types. The same parameters were also examined in a control group. Several of the functions investigated were systemic pressure, mean pulmonary arterial pressure (PAP), oxygenic partial pressure of arterial blood (Po2), thromboxane B2(TXB2), and 6-keto-prostaglandin F1 alpha (6-keto-PGF alpha). The morphologic study included gross, light microscopic, and transmission electronic microscopic observations. In the blast injury group, Po2 decreased and PAP, levels of blood plasma 6-keto-PGF alpha and level of TXB2 increased after injury, whereas PAP and level of 6-keto-PGF alpha decreased 24 hours after injury. The levels of 6-keto-PGF alpha and TXB2, in lung tissues, lung/body weight index were higher than those of the control group 24 hours after injury. The TXB2/6-keto-PGF alpha level in blood plasma increased slightly after injury, but showed no difference in lung tissue 24 hours after injury compared with the control group. The morphological changes showed that most of the animals sustained moderate lung injury. In the fragment injury group, Po2 decreased slightly and PAP increased slightly after injury; the levels of 6-keto-PGF alpha, TXB2 and TXB2/6-keto-PGF alpha in blood plasma increased after injury and were higher in lung tissue than in the control group 24 hours after injury. The lung/body weight index was nearly equal to that of control group. The morphological changes showed that only a few animals suffered from mild lung injury. In the combined injury group, Po2 and PAP changed in a manner similar to those of the other two injury groups but were more significantly. The level of blood plasma 6-keto-PGF alpha decreased gradually, whereas that of TXB2 increased permanently; thus, the levels of TXB2/6-keto-PGF alpha obviously increased after injury and were much higher than those in the other injury groups. The level of TXB2 in lung tissue was higher than that of the control group 24 hours after injury, but that of 6-keto-PGF alpha showed no change compared with that of the control group, and the level of TXB2/6-keto-PGF alpha was higher than in the other three groups. The morphological changes showed that most of animals sustained severe lung injury. It is concluded that extremity injury from high velocity fragment will aggravate lung blast injury. Changes in the levels of PGI2 and TXA2, can be used to determine the extent of injury in the three kinds of wounds. This may be useful for early diagnoses and rational treatment of the victims of explosion.

Animals↗
PubMed1996

[Comparison between kinetics of positive inotropism of ibopamine and ouabain].

AIM: To compare the kinetics of positive inotropism between ibopamine (Ibo) and ouabain (Oua). METHODS: The isolated right papillary muscle of cat was used to assess the positive inotropic effects by cummulative concentrations of Ibo and Oua. The maximal effects was recognized as the contraction just before the appearance of spontaneous contraction. A Hill equation was developed by using lg [E/(Emax-E)] vs lg C. RESULTS: The S value of Ibo was smaller than that of Oua, causing C95/C5 (ratio of concentrations producing 95%/5% of Emax) of Ibo (264) elevenfold as large as Oua (22.9). Comparing with Oua, concentrations of Ibo initiating effects were lower, the slope was smaller, and higher concentrations were required for producing maximal effect. During drug concentration declining, the effect-concentration curve of Ibo showed a counter-hysteresis loop, more remarkable than Oua. CONCLUSION: The changes in positive inotropism of Ibo against drug concentrations were less than those of Oua.

Animals↗
PubMed1995

Outline of control practice of endemic fluorosis in China.

Endemic fluorosis is prevalent in China covering 29 provinces, municipalities and autonomous regions. The endemically affected areas can be divided, according to the sources of fluoride, into three types: high fluoride water, pollution from coal burning, and drinking brick tea in excess. Since the 1960's, several pilot surveys of the disease have been made and control programmes carried out in some of the areas. An Expert Consultation Committee on Endemic Fluorosis Control of the Ministry of Public Health was formally established in 1979. A national survey programme and series of working criteria for the disease were drawn up at the First National Congress of Endemic Fluorosis Control in 1981. Under the Central Government of China, administrative organizations and institutions concerned at all levels have been set up, forming a nation-wide network of control. Cooperation and coordination among such departments as health, water conservancy, geology and finance have been achieved in the planning and implementation of control programmes. Since 1980, many projects for improving drinking water quality through de-fluoridation have been completed. At the same time, new methods and technologies for improving stove and grain baking have become widely used in some of the areas where environmental fluoride pollution exists from burning coal. After all the control programmes had been introduced, the incidence of the illness was reduced with some patients making a complete recovery.

China↗
PubMed1992

Role of the two-component leader sequence and mature amino acid sequences in extracellular export of endoglucanase EGL from Pseudomonas solanacearum.

The egl gene of Pseudomonas solanacearum encodes a 43-kDa extracellular endoglucanase (mEGL) involved in wilt disease caused by this phytopathogen. Egl is initially translated with a 45-residue, two-part leader sequence. The first 19 residues are apparently removed by signal peptidase II during export of Egl across the inner membrane (IM); the remaining residues of the leader sequence (modified with palmitate) are removed during export across the outer membrane (OM). Localization of Egl-PhoA fusion proteins showed that the first 26 residues of the Egl leader sequence are required and sufficient to direct lipid modification, processing, and export of Egl or PhoA across the IM but not the OM. Fusions of the complete 45-residue leader sequence or of the leader and increasing portions of mEgl sequences to PhoA did not cause its export across the OM. In-frame deletion of portions of mEGL-coding sequences blocked export of the truncated polypeptides across the OM without affecting export across the IM. These results indicate that the first part of the leader sequence functions independently to direct export of Egl across the IM while the second part and sequences and structures in mEGL are involved in export across the OM. Computer analysis of the mEgl amino acid sequence obtained from its nucleotide sequence identified a region of mEGL similar in amino acid sequence to regions in other prokaryotic endoglucanases.

Alkaline Phosphatase↗
PubMed1991

In vivo interactions of the NahR transcriptional activator with its target sequences. Inducer-mediated changes resulting in transcription activation.

The nahR gene from the NAH7 naphthalene degradation plasmid encodes a LysR-type transcriptional activator of the nah and sal promoters (Pnah and Psal, respectively) that responds to the inducer salicylate. In vivo methylation protection experiments with dimethyl sulfate showed that in the absence of inducer, NahR interacts in a similar manner with its target sites at Psal and Pnah. Both target sites also have very similar sequences comprised of a 4-base pair interrupted dyad containing two symmetrical guanines (-73 and -64 of Pnah; -71 and -62 of Psal), each located in adjacent major grooves on the same helical face, and both strongly protected by NahR. When inducer was present, several additional guanines of Pnah (-35, -45, and -58) and Psal (-42 and -40) became protected from methylation, while a guanine at -52 of Pnah became markedly enhanced for methylation, indicating that inducer and NahR-dependent interactions with these downstream sites of each promoter are quite different. Deletion of Psal sequences downstream of -30 did not affect its methylation patterns suggesting that NahR alone is responsible for the altered reactivities of these nucleotides. Similar in vivo methylation analyses with inducer-insensitive or inducer-independent NahR mutants also suggested that all alterations in methylation sensitivity are directly caused by NahR. It is more probable that the salicylate-induced reactivity changes result from direct NahR-guanine contacts which are required for, but not sufficient for transcription activation; however, they could also result from NahR-induced DNA contortions caused by upstream protein-DNA contacts.

Alleles↗
PubMed1990

Evidence that extracellular export of the endoglucanase encoded by egl of Pseudomonas solanacearum occurs by a two-step process involving a lipoprotein intermediate.

Pseudomonas solanacearum is an important phytopathogen that produces a variety of extracellular enzymes. Previous reports suggested that one of these, a 43-kDa beta-1,4-endoglucanase (EGL), is initially synthesized with a 45-residue leader sequence that is removed during export. Experiments with globomycin presented here also suggest that the primary precursor of EGL (ppEGL) has a 45-residue leader sequence but that only the first 19 residues of the leader sequence are removed by signal peptidase II during initial export across the inner membrane. Further analysis suggested that the resultant 46-kDa intermediate precursor (pEGL) is a transient fatty acylated lipoprotein and is located on the periplasmic side of the inner membrane of P. solanacearum. Although Escherichia coli could synthesize ppEGL, modify it with palmitate, and remove the first 19 residues of the leader sequence during export across the inner membrane, only P. solanacearum could export pEGL across the outer membrane and remove the remaining 26 residues of the leader sequence producing the mature, extracellular EGL. The second step of the export process requires export machinery not present in E. coli. To our knowledge this represents the first example of a leader sequence with two distinct parts, one removed during export across the inner membrane and the other removed during export across the outer membrane.

Amino Acid Sequence↗
PubMed1990

[Influence of 6,7-dimethoxycoumarin on toxicity and pharmacodynamics of cyclophosphamide].

When 40 mg/kg of 6,7-dimethoxycoumarin (DMOC) was given (ip) 15 min before sc cyclophosphamide (Cy), the LD50/7 d of Cy would be raised from 166 +/- 9 (100-245) to 294 +/- 4 (250-346) mg/kg (dose reduction factor 1.78) in Wistar rat. The 7 d survival rate of mice intoxicated by Cy was raised to 26.7%. To give 100 mg/(kg.d) of DMOC for 5 or 24 days, it prevented the chronic toxicity of Cy prolonged the life-span, elevated the 30 d survival rate of rats intoxicated by Cy to 45.3 and 42.5%, respectively. DMOC increased the WBC, weight of thymus and body of rats and mice intoxicated by Cy; raised colony-forming unit and reduced high plasma corticosterone of mice intoxicated by Cy. It also increased the RNA and DNA of bone marrow, liver and spleen. DMOC in combination with Cy did not reduce the antitumor effect of Cy.

Animals↗
PubMed1989

Excretion of the egl gene product of Pseudomonas solanacearum.

Pseudomonas solanacearum is an important phytopathogen which excretes a variety of extracellular enzymes. Pulse-chase experiments showed that one of these enzymes, a beta-1,4-endoglucanase (EGL) encoded by the egl gene, is synthesized as a higher-molecular-weight precursor polypeptide (pEGL) which is subsequently excreted into the extracellular medium as a 43-kilodalton mature protein. S1 nuclease transcript mapping and DNA sequence analysis were used to identify the transcription start site and the possible translation start site of egl. Pulse-chase experiments and comparison of the putative NH2-terminal amino acid sequence of pEGL with the actual NH2-terminal amino acid sequence of mature excreted EGL suggested that pEGL has a 45-residue leader sequence preceding the N terminus of EGL which is proteolytically cleaved during export to the extracellular environment. The first 20 residues of the leader sequence resembled a typical lipoprotein signal peptide. The excretion of EGL by P. solanacearum apparently requires a membrane potential since it was blocked by carbonyl cyanide m-chlorophenyl hydrazone.

Amino Acid Sequence↗