Biomedical subjects

Lei Zhang

Publications and source records attributed to Lei Zhang.

At least 73 records · Page 4Linked to original sources

PubMed2006

Expression of gastric ghrelin and H(+)-K(+)-ATPase mRNA in weanling piglets and effect of ghrelin on H(+)-K(+)-ATPase expression and activity in gastric mucosal cells in vitro.

This study was designed to investigate the effect of ghrelin on gastric acid secretion in weaning piglets both in vivo and in vitro. Thirty newborn piglets were selected from six litters and on 28, 35 (weaning), 38, 42 and 45d of age, respectively, one piglet from each litter was killed and the mucosal tissue from gastric fundus was collected for detecting ghrelin mRNA as well as H(+)-K(+)-ATPase mRNA expression and activity. Primary cultures of gastric mucosal cells from 5-week-old weaning piglets were challenged with 3x10(-5), 3x10(-4), 3x10(-3), 3x10(-2) and 3x10(-1)nmol/ml h-ghrelin, respectively, for 4h in order to further clarify the effect of ghrelin on gastric H(+)-K(+)-ATPase mRNA expression and activity. Ghrelin mRNA expression in gastric fundus kept stable from 28d to 42d, followed by a sudden increase on 45d, exhibiting a peak that was significantly higher than any other age groups investigated. H(+)-K(+)-ATPase activity and mRNA expression showed similar trends of increase with slightly different timing. H(+)-K(+)-ATPase mRNA expression tended to increase on 42d, while H(+)-K(+)-ATPase activity started to rise from 35d, but neither of them reached significantly higher levels until 45d. In vitro, ghrelin significantly increased H(+)-K(+)-ATPase activity of gastric mucosal cells at 3x10(-4), 3x10(-3), and 3x10(-2)nmol/ml, but augmented H(+)-K(+)-ATPase mRNA expression only at 3x10(-4)nmol/ml. The results indicate that ghrelin mRNA expression is up-regulated 10 days after weaning in the gastric fundus of piglets, coinciding with the increase of H(+)-K(+)-ATPase mRNA expression and activity. Ghrelin acts on gastric mucosal cells to stimulate both mRNA expression and activity of H(+)-K(+)-ATPase in vitro.

Animals↗

PubMed2006

[Current diagnostic status, clinical and pathologic manifestation for a Crohn's disease].

OBJECTIVE: To evaluate the contemporary diagnostic and therapeutic status for Crohn's disease (CD), and analyze its clinical and pathologic manifestation. METHODS: Retrospectively we reviewed 220 hospitalized inflammatory bowel disease (IBD) cases in which 48 were diagnosed as CD. Data of diagnostic and therapeutic details were recorded. RESULTS: In the past 10 years 44 of the 48 CD cases were diagnosed in recent and 75.0% of the cases were in the onset age range from 17 to 40 years. The most common symptoms were abdominal pain, diarrhea and bloody stool. 16 (33.3%) of the cases were accompanied with extra-intestinal manifestations, 3 (6.3%) with perianal abscess, and 2 (4.2%) with intestinal fistulation. The main findings through colonoscopy were ulceration, obstruction and cobble stone sign, with a diagnostic correspondence of 85.7% (36/42). Non-caseous granulomas were totally identified in 43.2% (19/44) of the histology. Thirty cases were administrated with Sulfasalazine/Mesalazine (SASP/5-ASA) or corticosteroids/immuno-suppressor in which 27 got clinically improved. Thirteen patients underwent surgery. CONCLUSION: The diagnostic incidence of Crohn's disease has been increased in recent years. The combination of endoscopy, radiography and histology is the best way for the diagnosis of CD. Small intestinal endoscopy and capsule endoscopy with repeated histopathology and follow-up are helpful for the diagnosis.

Adult↗

PubMed2006

Tumor infiltration of bone marrow in patients with hemato-logical malignancies: dynamic contrast-enhanced magnetic resonance imaging.

BACKGROUND: Conventional magnetic resonance (MR) scanning techniques can identify bone marrow (BM) containing mostly fat cells. But they are not able to differentiate BM tumor infiltration, BM fibrosis and normal red BM. This is particularly problematic in assessment of recurrent or refractory hematological malignancy. This pilot study used dynamic contrast-enhanced MR imaging (DCE-MRI) to evaluate the bone marrow status and to determine whether several calculated parameters derived from the DCE-MRI correlate with histological characteristics of marrow, especially with the tumor fraction (TF). METHODS: DCE-MRI scans were performed in 25 patients with proven or known hematological malignancy who were about to undergo bone marrow biopsy of the posterior iliac crest. The location chosen for biopsy was examined with MRI approximately one hour prior to the biopsy. Time-signal intensity curves (TIC) were generated from the region of the iliac crest corresponding to the planned biopsy site. Enhancement parameters were calculated, including peak enhancement ratio (PER), maximum enhancement slope (Slope(max)), time to peak (TTP) and mean time (MT). The biopsy specimen was reported synoptically, with relevant reported parameters including cellularity and tumor fraction (TF). RESULTS: PER values were significantly higher for the bone marrow tumor infiltration group than for the normal bone marrow group (P < 0.05). A significant positive correlation was found between PER and TF as well as Slope(max) and TF. A negative correlation was found between TTP and TF. There was no significant difference in the mean TTP and MT values between the BM tumor infiltration group and the normal bone marrow group. CONCLUSIONS: The presence of diffuse bone marrow infiltration in patients with haematological malignancies could be verified using DCE-MRI.

Adult↗

PubMed2006

Propagation of a decentered elliptical Gaussian beam through apertured aligned and misaligned paraxial optical systems.

By expanding the hard aperture function into a finite sum of complex Gaussian functions, approximate analytical formulas for a decentered Gaussian beam (DEGB) passing through apertured aligned and misaligned paraxial apertured paraxial optical systems are derived in terms of a tensor method. The results obtained by using the approximate analytical expression are in good agreement with those obtained by using the numerical integral calculation. Furthermore, approximate analytical formulas for a decentered elliptical Hermite-Gaussian beam (DEHGB) through apertured paraxial optical systems are derived. As an application example, approximate analytical formulas for a decentered elliptical flattened Gaussian beam through apertured paraxial optical systems are derived. Our results provide a convenient way for studying the propagation and transformation of a DEGB and a DEHGB through apertured paraxial optical systems.

Journal Article↗

PubMed2006

Regulation of wingless signaling by the CKI family in Drosophila limb development.

The Wingless (Wg)/Wnt signaling pathway regulates a myriad of developmental processes and its malfunction leads to human disorders including cancer. Recent studies suggest that casein kinase I (CKI) family members play pivotal roles in the Wg/Wnt pathway. However, genetic evidence for the involvement of CKI family members in physiological Wg/Wnt signaling events is lacking. In addition, there are conflicting reports regarding whether a given CKI family member functions as a positive or negative regulator of the pathway. Here we examine the roles of seven CKI family members in Wg signaling during Drosophila limb development. We find that increased CKIepsilon stimulates whereas dominant-negative or a null CKIepsilon mutation inhibits Wg signaling. In contrast, inactivation of CKIalpha by RNA interference (RNAi) leads to ectopic Wg signaling. Interestingly, hypomorphic CKIepsilon mutations synergize with CKIalpha RNAi to induce ectopic Wg signaling, revealing a negative role for CKIepsilon. Conversely, CKIalpha RNAi enhances the loss-of-Wg phenotypes caused by CKIepsilon null mutation, suggesting a positive role for CKIalpha. While none of the other five CKI isoforms can substitute for CKIalpha in its inhibitory role in the Wg pathway, several CKI isoforms including CG12147 exhibit a positive role based on overexpression. Moreover, loss of Gilgamesh (Gish)/CKIgamma attenuates Wg signaling activity. Finally, we provide evidence that several CKI isoforms including CKIalpha and Gish/CKIgamma can phosphorylate the Wg coreceptor Arrow (Arr), which may account, at least in part, for their positive roles in the Wg pathway.

Animals↗

PubMed2006

Cisplatin-induced toxicity is associated with platinum deposition in mouse kidney mitochondria in vivo and with selective inactivation of the alpha-ketoglutarate dehydrogenase complex in LLC-PK1 cells.

The anticancer drug cisplatin is nephrotoxic and neurotoxic. Previous data support the hypothesis that cisplatin is bioactivated to a nephrotoxicant. The final step in the proposed bioactivation is the formation of a platinum-cysteine S-conjugate followed by a pyridoxal 5'-phosphate (PLP)-dependent cysteine S-conjugate beta-lyase reaction. This reaction would generate pyruvate, ammonium, and a highly reactive platinum (Pt)-thiol compound in vivo that would bind to proteins. In this work, the cellular location and identity of the PLP-dependent cysteine S-conjugate beta-lyase were investigated. Pt was shown to bind to proteins in kidneys of cisplatin-treated mice. The concentration of Pt-bound proteins was higher in the mitochondrial fraction than in the cytosolic fraction. Treatment of the mice with aminooxyacetic acid (AOAA, a PLP enzyme inhibitor), which had previously been shown to block the nephrotoxicity of cisplatin, decreased the binding of Pt to mitochondrial proteins but had no effect on the amount of Pt bound to proteins in the cytosolic fraction. These data indicate that a mitochondrial enzyme catalyzes the PLP-dependent cysteine S-conjugate beta-lyase reaction. PLP-dependent mitochondrial aspartate aminotransferase (mitAspAT) is a mitochondrial enzyme that catalyzes beta-elimination reactions with cysteine S-conjugates of halogenated alkenes. We reasoned that the enzyme might also catalyze a beta-lyase reaction with the cisplatin-cysteine S-conjugate. In this study, mitAspAT was stably overexpressed in LLC-PK(1) cells. Cisplatin was significantly more toxic in confluent monolayers of LLC-PK(1) cells that overexpressed mitAspAT than in control cells containing vector alone. AOAA completely blocked the cisplatin toxicity in confluent mitAspAT-transfected cells. The Pt-thiol compound could rapidly bind proteins and inactivate enzymes in close proximity of the PLP-dependent cysteine S-conjugate beta-lyase. Treatment with 50 or 100 microM cisplatin for 3 h, followed by removal of cisplatin from the medium for 24 h, resulted in a pronounced loss of alpha-ketoglutarate dehydrogenase complex (KGDHC) activity in both mitAspAT-transfected cells and control cells. Exposure to 100 microM cisplatin resulted in a significantly greater loss of KGDHC activity in the cells overexpressing mitAspAT than in control cells. Aconitase activity was diminished in both cell types, but only at the higher level of exposure to cisplatin. AspAT activity was also significantly decreased by cisplatin treatment. By contrast, several other enzymes (both cytosolic and mitochondrial) involved in energy/amino acid metabolism were not significantly affected by cisplatin treatment in the LLC-PK(1) cells, whether or not mitAspAT was overexpressed. The susceptibility of KGDHC and aconitase to inactivation in kidney cells exposed to cisplatin metabolites may be due to the proximity of mitAspAT to KGDHC and aconitase in mitochondria. These findings support the hypothesis that a mitochondrial cysteine S-conjugate beta-lyase converts the cisplatin-cysteine S-conjugate to a toxicant, and the data are consistent with the hypothesis that mitAspAT plays a role in the bioactivation of cisplatin.

Animals↗

PubMed2006

Generation and growth mechanism of metal (Fe, Co, Ni) nanotube arrays.

Nanotubes composed of layered or nonlayered materials have been synthesized through various methods, among which template-based electrodeposition technology provides a versatile technique for synthesizing one-dimensional nanostructured materials. However, the growth mechanism of nanotubes using the template method is seldom clarified. Herein, we present the systematic preparation of metal nanotube arrays and put forward the growth mechanism, termed current-directed tubular growth (CDTG), for template-based electrodeposition. There are competitive growth rates for metal atoms entering the crystal lattice, that is, v( parallel) (growth rate parallel to current direction) and v( perpendicular) (growth rate perpendicular to current direction). Metal nanotubes can be obtained at v( parallel)>>v( perpendicular), while nanowires can be obtained at v( parallel) approximately v( perpendicular). The as-synthesized metal (Fe, Co, Ni) nanotubes are constructed from nonlayered materials, which are of body-centered cubic iron structure, hexagonal close packed cobalt structure, and face-centered cubic nickel structure, respectively. The CDTG mechanism is expected to have applications in designing and synthesizing other metal nanotubes and even compound nanotubes via template-based electrodeposition technology.

Journal Article↗

PubMed2006

Novel dimetal bridging carbene complexes derived from a terminal carbonyl dimetal compound. Syntheses, structures and reactivities of 7H-indene-coordinated diiron bridging carbene complexes.

Pentacarbonyl-7H-indenediiron, [Fe2(CO)5(eta3,eta5-C9H8)] (1), reacts with aryllithium, ArLi (Ar = C6H5, p-C6H5C6H4), followed by alkylation with Et3OBF4 to give novel 7H-indene-coordinated diiron bridging alkoxycarbene complexes [Fe2{mu-C(OC2H5)Ar}(CO)4(eta4,eta4-C9H8)] (2, Ar = C6H5; 3, Ar = p-C6H5C6H4). Complexes 2 and 3 react with HBF4.Et2O at low temperature to yield cationic bridging carbyne complexes [Fe2(mu-CAr)(CO)4(eta4,eta4-C9H8)]BF4 (4, Ar = C6H5; 5, Ar = p-C6H5C6H4). Cationic 4 and 5 react with NaBH4 in THF at low temperature to afford diiron bridging arylcarbene complexes [Fe2{mu-C(H)Ar}(CO)4(eta4,eta4-C9H8)] (6, Ar = C6H5; 7, Ar = p-C6H5C6H4). The similar reactions of 4 and 5 with NaSC6H4CH3-p produce the bridging arylthiocarbene complexes [Fe2{mu-C(Ar)SC6H4CH3-p}(CO)4(eta4,eta4-C9H8)] (8, Ar = C6H5; 9, Ar = p-C6H5C6H4). Cationic 4 and 5 can also react with anionic carbonylmetal compounds Na[M(CO)5(CN)] (M = Cr, Mo, W) to give the diiron bridging aryl(pentacarbonylcyanometal)carbene complexes [Fe2{mu-C(Ar)NCM(CO)5}(CO)4(eta4,eta4-C9H8)] (10, Ar = C6H5, M = Cr; 11, Ar = p-C6H5C6H4, M = Cr; 12, Ar = C6H5, M = Mo; 13, Ar = p-C6H5C6H4, M = Mo; 14, Ar = C6H5, M = W; 15, Ar = p-C6H5C6H4, M = W). Interestingly, in CH2Cl2 solution at room temperature complexes 10-15 were transformed into the isomerized 7H-indene-coordinated monoiron complexes [Fe(CO)2(eta5-C9H8)C(Ar)NCM(CO)5] (16, Ar = C6H5, M = Cr; 17, Ar = p-C6H5C6H4, M = Cr; 18, Ar = C6H5, M = Mo; 19, Ar = p-C6H5C6H4, M = Mo; 20, Ar = C6H5, M = W; 21, Ar = p-C6H5C6H4, M = W), while complex 3 was converted into a novel ring addition product [Fe2{C(OC2H5)C6H4C6H5-p-(eta2,eta5-C9H8)}(CO)5] (22) under the same conditions. The structures of complexes 2, 6, 8, 14, 18 and 22 have been established by X-ray diffraction studies.

Journal Article↗

PubMed2006

Adsorption of mixtures of nonionic sugar-based surfactants with other surfactants at solid/liquid interfaces II. Adsorption of n-dodecyl-beta-D-maltoside with a cationic surfactant and a nonionic ethoxylated surfactant on solids.

Synergy and antagonism between sugar-based surfactants, a group of environmentally benign surfactants, and cationic surfactants and nonionic ethoxylated surfactants have been investigated in this study with solids which adsorbs only one or other when presented alone. Sugar-based n-dodecyl-beta-D-maltoside (DM) does not adsorb on silica by itself. However, in mixtures with cationic dodecyltrimethylammonium bromide (DTAB) and nonionic nonylphenol ethoxylated decyl ether (NP-10), DM adsorbs on silica through hydrophobic interactions. In contrast, although DM does adsorb on alumina, the presence of NP-10 reduces the adsorption of DM as well as that of the total surfactant adsorption. Such synergistic/antagonistic effects of sugar-based n-dodecyl-beta-D-maltoside (DM) in mixtures with other surfactants at solid/liquid interfaces were systematically investigated and some general rules on synergy/antagonism in mixed surfactant systems are identified. These results have implications for designing surfactant combinations for controlled adsorption or prevention of adsorption.

Adsorption↗

PubMed2006

Adsorption of mixtures of nonionic sugar-based surfactants with other surfactants at solid/liquid interfaces I. Adsorption of n-dodecyl-beta-D-maltoside with anionic sodium dodecyl sulfate on alumina.

Sugar-based surfactants can be synthesized from renewable materials and are environmentally benign. They have some unique solution and interfacial properties and have potential applications in a wide variety of processes, and there is a need for corresponding information on their behavior at various interfaces. In this study, co-adsorption of nonionic sugar-based n-dodecyl-beta-D-maltoside (DM) and anionic sodium dodecyl sulfate (SDS) on alumina was studied as a function of mixing ratios and solution pHs. It is found that at solid-liquid interface, depending on the solid type and the solution conditions, there are various interactions that dictate synergy or antagonism. At pH 6 where alumina is positively charged, marked synergistic effects between DM and SDS were observed, while at pH 11 where alumina is negatively charged, SDS shows antagonistic adsorption effects with DM. The ratios of surfactant components on solids change as a function of surfactant structure and concentrations as well, indicating various interactions at solid/liquid interface under different conditions that can be utilized for many industrial processes.

Adsorption↗

PubMed2006

Calmodulin isoform-specific activation of a rice calmodulin-binding kinase conferred by only three amino-acids of OsCaM61.

The kinase activity of a Ca(2+)/calmodulin (CaM)-binding serine/threonine protein kinase from rice (Oryza sativa) (OsCBK) has been reported to be unaffected by OsCaM1 binding. In this study, we examined whether other rice CaMs can stimulate OsCBK. It was observed that OsCaM61 stimulated OsCBK in a Ca(2+)-dependent manner. In addition, Ala(111), Gly(123) and Ser(127) were identified as critical residues for OsCBK activation. Mutational study and fluorescent spectroscopy analysis indicated that CaM-binding affinity does not correlate with the kinase activity and that these key amino-acids in OsCaM61 play a vital role in suitable changes of OsCBK conformation for kinase activation.

Alanine↗

PubMed2006

Functional redundancy of transcription factor-binding sites in the killer cell Ig-like receptor (KIR) gene promoter.

Variegated expression of inhibitory killer cell Ig-like receptors (KIRs) for MHC class I molecules helps NK cells distinguish normal from aberrant self and avoid autoreactivity. Prior studies of KIR promoters have produced conflicting results and no cis-acting sites have been independently confirmed. We took a comprehensive linker-scanning mutagenesis approach and substituted 24 consecutive 10-bp segments in the human KIR3DL1 promoter. Our analysis revealed eight segments that activated and three segments that repressed KIR transcription. Site-directed mutagenesis and electrophoretic mobility shift assays indicated that optimal KIR transcription requires a proximal Ets site that binds several Ets family members, a cAMP response element (CRE), a Runx site and a site that mediates complex interactions between Ets family members, signal transducer and activator of transcription 5 (STAT5) and YY1; Sp1 also contributes to KIR transcription. KIR transcription was greatly reduced by several compound mutations and was abrogated by a combination of mutations that affected the proximal Ets site, and the CRE, Runx, Sp1 and Ets/STAT sites. The many transcription factors that contribute to KIR transcription are partially redundant in the setting of transient transfection assays, helping to explain why only 0-2 activating sites had been reported in each of three prior studies. We propose that the multiplicity of transcription factors enables NK cells to sustain continuous KIR expression in diverse cellular and cytokine milieus, thus preventing NK autoreactivity.

Base Sequence↗

PubMed2006

Bestatin, an inhibitor of aminopeptidases, provides a chemical genetics approach to dissect jasmonate signaling in Arabidopsis.

Bestatin, a potent inhibitor of some aminopeptidases, was shown previously to be a powerful inducer of wound-response genes in tomato (Lycopersicon esculentum). Here, we present several lines of evidence showing that bestatin specifically activates jasmonic acid (JA) signaling in plants. First, bestatin specifically activates the expression of JA-inducible genes in tomato and Arabidopsis (Arabidopsis thaliana). Second, the induction of JA-responsive genes by bestatin requires the COI1-dependent JA-signaling pathway, but does not depend strictly on JA biosynthesis. Third, microarray analysis using Arabidopsis whole-genome chip demonstrates that the gene expression profile of bestatin-treated plants is similar to that of JA-treated plants. Fourth, bestatin promotes a series of JA-related developmental phenotypes. Taken together, the unique action mode of bestatin in regulating JA-signaled processes leads us to the hypothesis that bestatin exerts its effects through the modulation of some key regulators in JA signaling. We have employed bestatin as an experimental tool to dissect JA signaling through a chemical genetic screening, which yielded a collection of Arabidopsis bestatin-resistant (ber) mutants that are insensitive to the inhibitory effects of bestatin on root elongation. Further characterization efforts demonstrate that some ber mutants are defective in various JA-induced responses, which allowed us to classify the ber mutants into three phenotypic groups: JA-insensitive ber mutants, JA-hypersensitive ber mutants, and mutants insensitive to bestatin but showing normal response to JA. Genetic and phenotypic analyses of the ber mutants with altered JA responses indicate that we have identified several novel loci involved in JA signaling.

Aminopeptidases↗

PubMed2006

Microenvironment control of methyl rotation induced by proton transfer.

Methyl rotation induced by proton transfer was found for cis-N-methylacetamide (NMA). More interestingly, it was found that the microenvironment could control the methyl rotation. The atom-centered density matrix propagation (ADMP) method, a recently developed ab initio molecular dynamics, was further carried out to depict the trajectories for methyl rotation of NMA. Moreover, trajectories for methyl rotation of NMA complexed with water molecules were also calculated, and water molecules at the two different sites of NMA were found to reverse or cease the rotational direction of the methyl groups of NMA. This finding that microenvironment can not only control rotational direction of methyl groups but can also cease the rotation may be of significant importance for the control of molecular machines.

Journal Article↗

PubMed2006

Neural substrates for forward and backward recitation of numbers and the alphabet: a close examination of the role of intraparietal sulcus and perisylvian areas.

Despite numerous studies on the neural basis of numerical processing, few studies have examined the neural substrates of one of the most basic numerical processing-number sequence recitation. The present study used fMRI to investigate neural substrates of number sequence recitation, focusing on the intraparietal sulcus (IPS) and perisylvian areas. This study used a 2 (number versus alphabet) x 2 (forward versus backward recitation) design. 12 Chinese undergraduates were asked to recite overtly but gently numerical and alphabetical sequences forward and backward. Results showed that, for both numerical and alphabetic sequences, the left IPS was activated when performing backward recitation, but not when performing forward recitation. In terms of perisylvian areas, all four tasks elicited activation in bilateral superior temporal gyrus and inferior frontal gyrus, but forward recitation elicited greater activation in the left posterior superior temporal gyrus than did backward recitation, whereas backward recitation elicited greater activation in the left inferior frontal gyrus than did forward recitation. These results suggest that forward recitation of numbers and the alphabet is typically based on verbal processing of numbers implemented in the perisylvian area, whereas backward recitation would likely require additional neural resources in the IPS.

Adolescent↗

PubMed2006

Potent inhibition of the CD4-dependent T cell response by J2, a novel nonpeptide organic ligand of CD4 D1.

The interaction between CD4 and major histocompatibility complex (MHC) class II proteins is critical for the activation of CD4+ T cells, which are involved in transplantation reactions and a number of autoimmune diseases. It is known that the CD4 N-terminal immunoglobulin variable region-like domain (D1) is directed toward and reaching into the two membrane-proximal domains of the MHC class II molecule. Thus, compounds targeted to D1 would be expected to function as the inhibitors of the interaction of CD4 and class II MHC molecules. In this study, we used a computer-based design method to screen thousands of non-peptidic compounds in a molecular database and identified a group of compounds as potential ligands of CD4 D1. These small organic compounds were then synthesized and tested by actual biological assays. One of them, named J2, which possessed favorable activity, was obtained. Experimental data showed that J2 could specifically block stable CD4-MHC class II binding and elicit significant inhibition of immune responses in vitro and in vivo. All the results demonstrated the therapeutic potential of this compound as a novel immunosuppressive agent.

Acrylamides↗

PubMed2006

Prevalence of overweight among elementary and middle school students in Mississippi compared with prevalence data from the Youth Risk Behavior Surveillance System.

INTRODUCTION: The purpose of the Child and Youth Prevalence of Overweight Survey was to estimate the prevalence of overweight and at risk for becoming overweight among children in Mississippi (grades 1-8) using height and weight measures instead of self-report and to compare the findings for grades 6 through 8 with data from the Youth Risk Behavior Surveillance System for middle school students (grades 6-8). METHODS: Students in randomly selected classes from 37 sampled elementary and middle schools throughout Mississippi participated in the study. School staff were trained to collect height and weight data using a standardized procedure. RESULTS: Overall, 24.0% of students in grades 1 through 8 were found to be overweight, and another 14.7% were at risk for becoming overweight. With the exception of sixth grade, there was a trend of increasing prevalence of overweight by grade (17.5% in grade 1 compared with 31.3% in grade 8). In the Child and Youth Prevalence of Overweight Survey, 25.2% of students in grades 6 through 8 were found to be overweight, compared with 18.5% in the Youth Risk Behavior Surveillance System. CONCLUSION: A high percentage of students in Mississippi are already overweight in first grade, and the prevalence tends to increase by grade. Data collected from middle school students through measured heights and weights in the Child and Youth Prevalence of Overweight Survey were higher than self-reported data from the Youth Risk Behavior Surveillance System. Our data suggest that self-reported data underestimate the prevalence of overweight among middle school students. Efforts to monitor students' body mass index and assess effectiveness of interventions should include all grades and use measured heights and weights rather than self-reports.

Child↗

PubMed2006

Leptin enhances in vitro secretion of IgG antiplatelet antibodies by splenocytes and peripheral blood mononuclear cells from patients with chronic idiopathic thrombocytopenic purpura.

Chronic idiopathic thrombocytopenic purpura (ITP) is an organ-specific autoimmune disease characterized by the production of antibodies against antigens on the membranes of platelets, resulting in enhanced destruction of the platelets by macrophages. Leptin, a cytokine-like hormone, plays a role in the pathogenesis of several autoimmune diseases. In this study, we observed significantly increased plasma leptin levels combined with decreased soluble leptin receptor (sOB-R) levels in 18 chronic ITP patients compared with 14 controls. We also demonstrated significantly elevated mRNA expression of long form leptin receptor (Ob-Rb) on peripheral blood mononuclear cells (PBMCs) from chronic ITP patients. Treatment with recombinant leptin or serum with high leptin levels enhanced in vitro secretion of IgG antiplatelet antibodies by splenocytes and PBMCs from patients with chronic ITP. After depletion of CD4(+) T cells from splenocytes, leptin lost this function. Further studies showed that leptin could increase platelet reactive T cells. These findings suggest that leptin may be involved in the pathogenesis of chronic ITP and might offer a potential target for the treatment of this disease.

Adult↗