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Biomedical subjects

M Ling

Publications and source records attributed to M Ling.

At least 37 records · Page 2Linked to original sources
PubMed2000

Serum IgE response to orally ingested antigen: a novel IgE response model with allergen-specific T-cell receptor transgenic mice.

BACKGROUND: The mechanism by which orally ingested allergens elicit an IgE response remains unclear because there are few animal models available for investigation of this response. OBJECTIVE: We tried to develop a murine model suitable for investigation of the IgE response to orally ingested allergens, which would allow us to identify T cells that could promote IgE production. METHODS: Ovalbumin (OVA)-specific T-cell receptor transgenic mice were fed a diet containing OVA, and both the serum antibody response and cytokine production by splenocytes were examined. RESULTS: Oral administration of OVA to transgenic mice led to an increase in the levels of both antigen-specific IgE and total IgE in the sera. Subsequent intravenous challenge of OVA-fed transgenic mice with OVA resulted in anaphylactic shock. Analysis of cytokine production by splenocytes revealed that high IL-4-producing T cells appeared in the spleen 1 week after the start of feeding the OVA diet. T cells from these mice were found to promote IgE secretion by BALB/c B cells in vitro. This helper activity and the levels of IL-4 secretion were diminished after long-term feeding. These findings suggest the possibility that the orally ingested antigen elicited a response by a subpopulation of T cells that produce high levels of T(H2)-type cytokines and that promote IgE secretion, and these same T cells were tolerized by the orally ingested antigen. CONCLUSION: This experimental model with transgenic mice may be a useful tool for further studies of the cellular and molecular mechanisms of the T-cell and IgE responses to orally ingested antigens.

Administration, Oral↗
PubMed2000

Effects of lead exposure before pregnancy and dietary calcium during pregnancy on fetal development and lead accumulation.

Millions of women of child-bearing age have substantial bone lead stores due to lead exposure as children. Dietary calcium ingested simultaneously with lead exposure can reduce lead absorption and accumulation. However, the effects of dietary calcium on previously accumulated maternal lead stores and transfer to the fetus have not been investigated. We studied the effects of lead exposure of female rats at an early age on fetal development during a subsequent pregnancy. We gave 5-week-old female Sprague-Dawley rats lead as the acetate in their drinking water for 5 weeks; controls received equimolar sodium acetate. This was followed by a 1-month period without lead exposure before mating. We randomly assigned pregnant rats (n = 39) to diets with a deficient (0.1%) or normal (0.5%) calcium content during pregnancy. A total of 345 pups were delivered alive. Lead-exposed dams and their pups had significantly higher blood lead concentrations than controls, but the concentrations were in the range of those found in many pregnant women. Pups born to dams fed the calcium-deficient diet during pregnancy had higher blood and organ lead concentrations than pups born to dams fed the 0. 5% calcium diet. Pups born to lead-exposed dams had significantly (p<0.0001) lower mean birth weights and birth lengths than controls. There were significant inverse univariate associations between dam or pup organ lead concentrations and birth weight or length. The 0.5% calcium diet did not increase in utero growth. Stepwise regression analysis demonstrated that greater litter size and female sex were significantly associated with reduced pup birth weight and length. However, lead exposure that ended well before pregnancy was significantly (p<0.0001) associated with reduced birth weight and length, even after litter size, pup sex, and dam weight gain during pregnancy were included in the regression analysis. The data demonstrate that an increase in dietary calcium during pregnancy can reduce fetal lead accumulation but cannot prevent lead-induced decreases in birth weight and length. The results provide evidence that dietary nutrients can influence the transfer of toxins to the fetus during pregnancy. If these results are applicable to women, an increase in diet calcium during pregnancy could reduce the transfer of lead from prepregnancy maternal exposures to the fetus.

Animals↗
PubMed2000

[Zymographic analysis of matrix metalloproteinases in mouse carcinoma cell lines with different lymphatic metastasis potential].

OBJECTIVE: To investigate the correlation between lymphatic metastasis and matrix metalloproteinases (MMPs) activity. METHODS: Zymographic analysis was used to detect the difference of MMPs product and activities between high lymphatic metastatic cell line (HCa-F) and low lymphatic metastatic cell line (HCa-P), that were cultured in the medium including homogenate of lymph node or liver or spleen tissue. RESULTS: HCa-F and HCa-P cells produced small quantities of MMP-9 in 1640 medium. After adding lymph node homogenate to the culture medium, F cells produced a large quantity of MMP-9 as well as active MMP-9 and MMP-2. P cells also produced MMP-9, active MMP-9 and MMP-2, but were much lower than that of F cells. Neither F cells nor P cells produced MMPs in the media with homogenate of liver or spleen added. CONCLUSION: The metastatic potential of F cells is stronger than that of P cells may be due to F cell's ability to secrete MMPs is stronger than P cell's, therefore the production of MMPs of hepatocarcinoma cells is closely correlated to their metastatic potential.

Animals↗
PubMed1999

Degradation of cardiac troponin I in serum complicates comparisons of cardiac troponin I assays.

BACKGROUND: Up to a 20-fold variation in serum cardiac troponin I (cTnI) concentration may be observed for a given patient sample with different analytical methods. Because more limited variation is seen for control materials and for purified cTnI, we explored the possibility that cTnI was present in altered forms in serum. METHODS: We used four recombinantly engineered cTnI fragments to study the regions of cTnI recognized by the Stratus(R), Opus(R), and ACCESS(R) immunoassays. The stability of these regions in serum was analyzed with Western blot. RESULTS: The measurement of several control materials and different forms of purified cTnI using selected commercial assays demonstrated five- to ninefold variation. Both the Stratus and Opus assays recognized the N-terminal portion (NTP) of cTnI, whereas the ACCESS assay recognized the C-terminal portion (CTP) of cTnI. Incubation of recombinant cTnI in normal human serum produced a marked decrease in cTnI concentration as determined with the ACCESS, but not the Stratus, immunoassay. Western blot analysis of the same samples using cTnI NTP- and CTP-specific antibodies demonstrated preferential degradation of the CTP of cTnI. CONCLUSIONS: The availability of serum cTnI epitopes is markedly affected by the extent of ligand degradation. The N-terminal half of the cTnI molecule was found to be the most stable region in human serum. Differential degradation of cTnI is a key factor in assay-to-assay variation.

Blotting, Western↗
PubMed1998

Prevalence of antibodies against proteins derived from leukemia cells in patients with chronic myeloid leukemia.

Although various studies supported the notion that leukemia cells in chronic myeloid leukemia (CML) may be recognized by the immune system, direct evidence showing the immunogenicity in vivo of proteins derived from the leukemia cells is lacking. In this study, we have constructed an expression cDNA library from the leukemia cells of a patient with CML and used the autologous serum to screen for high-titer IgG antibodies directed at the leukemia-derived proteins. We isolated eight distinct clones from the library, suggesting that multiple immune responses were elicited in the autologous host. Sequence analysis showed high degrees of homology to known gene sequences in six of the eight clones. Neither bcr-abl nor proteinase 3 sequences were isolated. Using Northern blot analysis, seven of the eight clones showed ubiquitous expression in normal bone marrow, leukemia cell lines, fresh leukemia cells, and normal tissues. However, clone no. 4 showed restricted mRNA expression, being only detected in some fresh leukemia cells, K562 cells, and normal testicular RNA. Using bacterial lysates in dot blot analysis, a panel of sera from normal individuals and patients with CML and other hematological malignancies were screened for high-titer antibodies against these eight clones. There were, among the CML patients, signficantly higher prevalence of antibodies against seven of the eight clones. They were observed even after omitting from the analysis patients with multiple myeloma whose associated immune paresis may impair immune responses to these proteins. Interestingly, antibodies against these proteins were also detected in a small number of normal individuals. Although the precise clinical significance of our findings remains to be determined, this study provides evidence in support of the potential immunogenicity of leukemia-derived proteins in the autologous host. It also provides basis for further investigations to characterize these proteins, especially clone no. 4, and determine their potential for immune targeting in CML.

Adolescent↗
PubMed1998

Immunogenicity and cross-reactivity with idiotypic IgA of VH CDR3 peptide in multiple myeloma.

Multiple myeloma idiotypic protein is clone-specific and therefore represents an ideal tumour antigen for immune targeting. In this study we determined whether a synthetic peptide corresponding to the autologous idiotypic VH CDR3 sequence could elicit peptide-specific immune responses in a patient with IgA myeloma. Not unlike B-cell lymphoma, the immune repertoire of the patient contained T cells capable of mounting proliferative and cytotoxic responses to antigen-presenting cells loaded with the CDR3 peptide. Furthermore, the T cells were also able to secrete interferon-gamma upon peptide rechallenge. Antigen recognition by peptide-primed T cells was MHC dependent and could be blocked by antibodies to both monomorphic MHC class I and class II molecules. These results therefore indicate the presence of T-cell epitopes on the VH CDR3 sequence. In addition, CDR3 peptide-primed T cells were also able to mount similar immune responses when rechallenged with the intact IgA idiotypic protein, suggesting that functional T-cell epitopes had been derived from the CDR3 sequence of the idiotypic protein. Our results therefore provide a new perspective to the immunogenicity of the idiotypic protein in myeloma.

Cell Division↗
PubMed1998

Amerindian pyruvate carboxylase deficiency is associated with two distinct missense mutations.

We characterized the pyruvate carboxylase (PC) gene by PCR amplification, subcloning, and sequencing. The coding region has 19 exons and 18 introns spanning approximately 16 kb of genomic DNA. Screening both the cDNA and the gene of individuals with the simple A form of PC deficiency revealed an 1828G-->A missense mutation in 11 Ojibwa and 2 Cree patients and a 2229G-->T transversion mutation in 2 brothers of Micmac origin. Carrier frequency may be as high as 1/10 in some groupings. The two point mutations are located in a region of homology conserved among yeast, rat, and human PC, in the vicinity of the carboxylation domain of the enzyme. These data provide the first characterization of the human PC gene structure, the identification of common pathogenic mutations, and the demonstration of a founder effect in the Ojibwa and Cree patients.

Amino Acid Sequence↗
PubMed1998

Detection of a homozygous four base pair deletion in the protein X gene in a case of pyruvate dehydrogenase complex deficiency.

While the presence of a lipoyl-containing protein (protein X) separate from lipoyl transacetylase in the pyruvate dehydrogenase complex (PDC) has been known for some time, until recently only the cDNA for the yeast enzyme has been cloned. We have cloned, sequenced and characterized the cDNA encoding the human protein X and localized the protein X gene to chromosome 11p13. We also report here a new case of protein X deficiency identified immunologically, with decreased activity of PDC and without mutations in the E1alpha subunit or E1beta subunit. We report that the cDNA and gene of this patient for protein X has a homozygous 4 bp deletion, specifically in the putative mitochondrial targeting signal sequence which results in a premature stop codon. This is the first documented case of a molecular defect in pyruvate dehydrogenase protein X.

Amino Acid Sequence↗
PubMed1998

Chronic ethanol administration alters hepatic rates of glycerol phosphorylation and glycerol 3-phosphate oxidation: a dynamic in vivo 31P magnetic resonance spectroscopy study.

We used dynamic in vivo 31P magnetic resonance spectroscopy to noninvasively study the metabolism of glycerol by the liver in living rats, as a means of detecting subtle metabolic changes induced by chronic ethanol consumption. Rats subjected to chronic ethanol consumption and their pair-fed controls were given a metabolic load of glycerol (0.75 or 1.3 mL glycerol x kg body mass(-1), i.p. or i.v) under normoxic or hyperoxic (98% O2) conditions. Changes in the level of glycerol 3-phosphate were followed in situ by monitoring the hepatic 31P phosphomonoester resonance every 7 or 13 min for up to 330 min. When challenged with a large dose of glycerol, chronic ethanol-treated rats exhibited less accumulation of glycerol 3-phosphate than controls, independent of the route of administration of the glycerol or whether the two groups were fasted or fed. For example, 1.3 mL glycerol x kg(-1) i.v. under normoxic conditions resulted in a two-fold increase in phosphomonoester in ethanol-treated rats compared with a five-fold increase in controls. The ethanol-treated rats also showed a slower rate of phosphorylation of glycerol and slower oxidation of glycerol 3-phosphate than controls, indicating decreased activities of the glycerol kinase and glycerol 3-phosphate dehydrogenase steps, and hence slower glycerol utilization. The rate of glycerol utilization was dose and oxygen concentration dependent. Kinetic analysis indicated that the chronic ethanol-induced decrease in the glycerol 3-phosphate dehydrogenase reaction was due to a decreased rate of NADH reoxidation in the liver, likely owing to a decrease in oxygen supply or utilization in the ethanol-treated rats. These observations support the hypothesis of pre-existing hypoxia in rat liver after chronic ethanol administration. This study demonstrates the utility of dynamic in vivo 31P magnetic resonance spectroscopy in following the metabolism of a glycerol load as a sensitive, nonperturbing, and potentially clinically applicable test of liver function.

Adenosine Triphosphate↗
PubMed1998

[Preoperative staging of esophageal carcinoma: comparison of endoesophageal ultrasonography, computerized tomography and conventional clinical staging].

OBJECTIVE: To evaluate the value of different methods in preoperative staging of esophageal carcinoma. METHOD: Thirty-six patients undergoing resection of esophageal carcinoma were examined with endoesophageal ultrasonography (EU) before operation. Eight of 36 patients could not be evaluated because of severe esophageal stenosis. Computerized tomography (CT) was performed in 21 patients. Comparison was made between stagings based on EU, CT as well as the conventional clinical staging system, respectively with surgical-pathological staging after resection. RESULT: The accuracy of conventional clinical staging for esophageal cancer was only 36%. The accuracy of CT in T, N and pTNM staging was 38.1%, 57.1% and 47.6% respectively. For EU, the figures were 77.8%, 72.2% and 72.2%, and were improved to be 85.7%, 78.6% and 83.1% when untraversable patients were excluded. CONCLUSION: While conventional clinical staging system lacks accuracy in evaluating esophageal carcinoma, CT makes only moderate improvement. Based on direct morphological examination of lesions, EU is highly accurate in preoperative staging of esophageal carcinoma, especially in evaluating the extent of luminal wall invasion and regional lymph node involvement. Therefore, EU is of critical value in the therapeutic selection for esophageal carcinoma.

Endosonography↗
PubMed1998

Idiotypic protein-pulsed adherent peripheral blood mononuclear cell-derived dendritic cells prime immune system in multiple myeloma.

Adherent peripheral blood mononuclear cell-derived dendritic cells pulsed with autologous idiotypic protein (Id) were given to a patient with advanced-stage refractory myeloma. Potentially beneficial antimyeloma Id-specific immune responses were produced, characterized by MHC-dependent T-cell-proliferative responses with cytokine release and the production of anti-Id antibodies. A T-cell line generated after vaccination was also able to lyse autologous Id-pulsed targets and recognize fresh autologous myeloma cells. The immune responses were associated with a transient minor fall in the serum Id level and were not ablated by high-dose myeloablative chemotherapy. This report therefore demonstrates the clinical use of adherent peripheral blood mononuclear cell-derived dendritic cells for vaccination in cancer and the persistence of immune responses after high-dose chemotherapy. Such a therapeutic approach may be useful in reducing the relapse rate in patients who have minimal residual disease after chemotherapy.

Adult↗
PubMed1997

Protective effect of chronic garlic intake on elastic properties of aorta in the elderly.

BACKGROUND: Epidemiological studies have suggested that garlic may have protective effects against cardiovascular diseases. We undertook this cross-sectional observational study to test the hypothesis that regular garlic intake would delay the stiffening of the aorta relating to aging. METHODS AND RESULTS: We studied healthy adults (n=101; age, 50 to 80 years) who were taking > or = 300 mg/d of standardized garlic powder for > or = 2 years and 101 age- and sex-matched control subjects. Pulse wave velocity (PWV) and pressure-standardized elastic vascular resistance (EVR) were used to measure the elastic properties of the aorta. Blood pressures, heart rate, and plasma lipid levels were similar in the two groups. PWV (8.3+/-1.46 versus 9.8+/-2.45 m/s; P<.0001) and EVR (0.63+/-0.21 versus 0.9+/-0.44 m2 x s(-2) x mm Hg(-1); P<.0001) were lower in the garlic group than in the control group. PWV showed significant positive correlation with age (garlic group, r=.44; control group, r=.52) and systolic blood pressure (SBP) (garlic group, r=.48; control group, r=.54). With any degree of increase in age or SBP, PWV increased less in the garlic group than in the control group (P<.0001). ANCOVA and multiple regression analyses demonstrated that age and SBP were the most important determinants of PWV and that the effect of garlic on PWV was independent of confounding factors. CONCLUSIONS: Chronic garlic powder intake attenuated age-related increases in aortic stiffness. These data strongly support the hypothesis that garlic intake had a protective effect on the elastic properties of the aorta related to aging in humans.

Aged↗
PubMed1997

The human mitochondrial elongation factor tu (EF-Tu) gene: cDNA sequence, genomic localization, genomic structure, and identification of a pseudogene.

The human mitochondrial elongation factor Tu (EF-Tu) is nuclear-encoded and functions in the translational apparatus of mitochondria. The complete human EF-Tu cDNA sequence of 1677 base pairs (bp) with a 101 bp 5'-untranslated region, a 1368 bp coding region, and a 207 bp 3'-untranslated region, has been determined and updated. The predicted protein from this cDNA sequence is approximately 49.8 kDa in size and is composed of 455 amino acids (aa) with a putative N-terminal mitochondrial leader sequence of approximately 50 aa residues. The predicted amino acid sequence shows high similarity to other EF-Tu protein sequences from ox, yeast, and bacteria, and also shows limited similarity to human cystolic elongation factor 1 alpha. The complete size of this cDNA (1677 bp) obtained by cloning and sequencing was confirmed by Northern blot analysis, which showed a single transcript (mRNA) of approximately 1.7 kb in human liver. The genomic structure of this EF-Tu gene has been determined for the first time. This gene contains nine introns with a predicted size of approximately 3.6 kilobases (kb) and has been mapped to chromosome 16p11.2. In addition, an intronless pseudogene of approximately 1.7 kb with 92.6% nucleotide sequence similarity to the EF-Tu gene has also been identified and mapped to chromosome 17q11.2.

Amino Acid Sequence↗
PubMed1997

Cloning, characterization, and chromosomal localization of human liver form cytochrome c oxidase subunit VIa related genes.

The chromosomal location of human cytochrome c oxidase (COX) subunit VIa Liver (VIa-L) isoform related sequences has been determined by a combination of in situ hybridization and analysis of human-hamster somatic cell hybrid panels. COX VIa-L related sequences were present on chromosomes 6 and 12. It has been verified that at least two COX VIa-L genes are on chromosome 6, one of which is a pseudogene. In total, four COX VIa-L related sequences have been cloned and their nucleotide sequences analyzed. At least three of the sequences represent pseudogenes; their relatedness to the COX VIa-L cDNA is discussed.

Animals↗
PubMed1997

The effects of hypoxia on the bioenergetics of liver in situ in chronic ethanol-treated rats: a noninvasive in vivo 31P magnetic resonance spectroscopy study.

OBJECTIVE: The effects of hypoxia on bioenergetic parameters of the livers of rats with and without chronic ethanol (CE) treatment has been studied in a totally noninvasive manner, using in vivo 31P magnetic resonance spectroscopy (MRS). METHOD: The effects of hypoxia (10% oxygen for 55 minutes) on the levels of ATP, inorganic phosphate (Pi), phosphomonoesters (PME) and phosphodiesters (PDE) were followed with time. The CE and control rats (four pairs) were starved for 16-20 hours to eliminate the effects of any ethanol still present within the liver. To complement the in vivo studies, perchloric acid extracts from rats (four pairs for each stage) at the three stages, initial (normoxic), hypoxic and recovery, were analyzed using in vitro high resolution 31P MRS. RESULTS: After hypoxic challenge, the hepatic Pi and PME levels increased much more significantly and more quickly for the CE rats compared to those of controls, and ATP levels decreased more dramatically for CE rats. The recoveries of Pi and PME levels after return to normoxic conditions were incomplete for the CE rats in contrast to the controls. The hepatic extract analyses showed that several different PMEs increased during hypoxia, including alpha-glycerophosphate, phosphocholine, AMP, IMP and glycolytic metabolites, and that total hepatic Pi increased during hypoxia in addition to cytoplasmic Pi. CONCLUSIONS: CE-treated rat livers in situ are bioenergetically more sensitive to a hypoxic challenge than are control rat livers, even in the absence of endogenous ethanol. This is consistent with a model of CE-induced liver damage in which CE-treated livers already have centrolobular hypoxia under normoxic conditions and cannot adequately compensate for additional hypoxic stress.

Adenosine Triphosphate↗