Antagonistic effects of Smad2 versus Smad7 are sensitive to their expression level during tooth development

Members of the transforming growth factor-beta (TGF-beta) superfamily regulate cell proliferation, differentiation, and apoptosis, controlling the development and maintenance of most tissues. TGF-beta signal is transmitted through the phosphorylation of Smad proteins by TGF-beta receptor serine/threonine kinase. During early tooth development, TGF-beta inhibits proliferation of enamel organ epithelial cells but the underlying molecular mechanisms are largely unknown. Here we tested the hypothesis that antagonistic effects between Smad2 and Smad7 regulate TGF-beta signaling during tooth development. Attenuation of Smad2 gene expression resulted in significant advancement of embryonic tooth development with increased proliferation of enamel organ epithelial cells, while attenuation of Smad7 resulted in significant inhibition of embryonic tooth development with increased apoptotic activity within enamel organ epithelium. These findings suggest that different Smads may have differential activities in regulating TGF-beta-mediated cell proliferation and death. Furthermore, functional haploinsufficiency of Smad2, but not Smad3, altered TGF-beta-mediated tooth development. The results indicate that Smads are critical factors in orchestrating TGF-beta-mediated gene regulation during embryonic tooth development. The effectiveness of TGF-beta signaling is highly sensitive to the level of Smad gene expression.

RIM4 encodes a meiotic activator required for early events of meiosis in Saccharomyces cerevisiae

RIM4 was previously found to be required for both the IME1- and IME2-dependent pathways of meiotic gene expression in Saccharomyces cerevisiae. We now demonstrate that RIM4 is also required for meiotic division and recombination. Furthermore, rim4Delta mutants show defects in premeiotic DNA synthesis, which can be suppressed by deletion of the SIC1 gene, which encodes a Cdk inhibitor. Expression of RIM4 is induced early in meiosis, and is dependent on IME1 but not IME2. Indeed, RIM4 itself is essential for the meiotic expression of IME2. These results suggest that RIM4 is epistatic to IME2, and is required for multiple steps during sporulation. In agreement with this interpretation, overexpression of RIM4 induces low levels of sporulation in rich medium.

Motor deficits in fibroblast growth factor receptor-3 null mutant mice

Fibroblast growth factor receptor-3 (FGFR-3) regulates aspects of bone development. Mutations in the FGFR-3 gene (Fgfr3) in humans and mice produce vertebral abnormalities and bone deformities. The present study evaluated the behavioural concomitants of the Fgfr3-/- mutation. Fgfr3-/- null mutant mice displayed severe impairments of motor abilities as detected on the rotarod, wire hang and open field tests. Absence of prepulse inhibition of acoustic startle was seen at prepulse levels from 74 to 86 dB. The motor deficits appear to be a direct and predicted consequence of the skeletal kyphosis, scoliosis and long bone overgrowth previously reported in Fgfr3 null mutant mice. The behavioural phenotype displayed by these mutant mice complements their anatomical, physiological and biochemical phenotypes, to complete the characterization of the functional outcome of a single gene mutation. Simple, robust behavioural symptoms, such as poor rotorod performance in Fgfr3 knockout mice, can provide useful surrogate markers to evaluate pharmacological treatments and gene therapies for human genetic diseases.

[Association of tumor necrosis factor microsatellite polymorphism with chronic atrophic gastritis and gastric adenocarcinoma]

OBJECTIVE

To investigate whether TNFd and TNFe microsatellite polymorphisms correlate with chronic atrophic gastritis and gastric adenocarcinoma in Chinese Han population.

METHODS

In 164 healthy controls, 53 patients with chronic atrophic gastritis, and 56 patients with gastric adenocarcinoma, TNFd and TNFe microsatellite alleles were typed using PCR technique, followed by high-voltage denaturing PAGE, with silver staining. At the same time, the PCR products were cloned and sequenced.

RESULTS

Fight alleles at the TNFd locus and four alleles at the TNFe locus were detected. A new allele was found and identified, its accession number of Genebank is AF315593. Statistical analysis showed that there existed a very strong linkage equilibrium between TNFd8 and TNFe4 allele. No difference was observed between patients and healthy controls in the distribution of alleles at the TNFd and TNFe loci (P > 0.05). The frequence of d2/d6 genotype was significantly higher in patients with gastric adenocarcinoma than in healthy individuals (P = 0.028). d2/d6 genotype wasn't related to age or gender or grade of differentiation or clinicopathologic stage in gastric adenocarcinoma.

CONCLUSION

d8e4 haplotype appears to be specific of Chinese population. d2/d6 genotype is associated with the susceptibility to gastric adenocarcinoma.

[Vacuolation effect of Helicobacter pylori on gastric epithelial cells]

This study was designed to observe vacuolation effect of Helicobacter pylori on gastric epithelial cells. The H. pylori isolates derived from patients with peptic ulcer, chronic gastritis and gastric cancer were plated on common selective medium and their vacuolation effects on SGC-7901 cells were compared. The percentage of H. pylori(Tox+) strain in clinical isolates from different gastroduodenal diseases had no significant difference. The toxicity of the H. pylori (Tox+) strain from peptic ulcer was significantly higher than that from chronic gasritis.

[The relativity study of thrombopoietin and chronic idiopathic thrombocytopenic purpura]

OBJECTIVE

To explore the relationship between thrombopoietin (Tpo) levels and reticulated platelet (RP), blood platelet count (BPC), maturity of megakaryocytes in patients with chronic idiopathic thrombocytopenic purpura (CITP), and the prediction evaluation according to Tpo levels.

METHODS

Serum level of Tpo was measured by a sandwich-ELISA procedure, RP by flow cytometry after stained with thizole orange (TO), and maturity of megakaryocytes by laser scanning confocal microscopy (LSCM).

RESULTS

The serum level of Tpo was (204.05 +/- 65.70) ng/L in 23 normal controls and (345.46 +/- 222.23) ng/L in 33 patients with CITP, being no significant difference between the two groups (P > 0.05). Compared with controls, serum Tpo levels in 22 aplastic anemia(AA) patients [(1427.62 +/- 468.84) ng/L] and 10 acute myelogenous leukemia (AML) patients [(596.09 +/- 462.95) ng/L] were increased significantly (P < 0.05). The RPC was significantly lower in AA and AML patients (P < 0.05). The RP% was increased significantly in CITP and AML patients (P < 0.05). The Tpo level was higher in CITP patients with no response to glucocorticoid therapy than in those with response (P < 0.05).

CONCLUSION

Serum level of Tpo was not increased in patients with CITP. The RP%, RPC and Tpo levels could reflect thrombocytopoiesis and differentiate the causes of thrombocytopenia. The serum level of Tpo could be useful in prediction of the response to therapy in CITP patients.

ADY1, a novel gene required for prospore membrane formation at selected spindle poles in Saccharomyces cerevisiae

ADY1 is identified in a genetic screen for genes on chromosome VIII of Saccharomyces cerevisiae that are required for sporulation. ADY1 is not required for meiotic recombination or meiotic chromosome segregation, but it is required for the formation of four spores inside an ascus. In the absence of ADY1, prospore formation is restricted to mainly one or two spindle poles per cell. Moreover, the two spores in the dyads of the ady1 mutant are predominantly nonsisters, suggesting that the proficiency to form prospores is not randomly distributed to the four spindle poles in the ady1 mutant. Interestingly, the meiosis-specific spindle pole body component Mpc54p, which is known to be required for prospore membrane formation, is localized predominantly to only one or two spindle poles per cell in the ady1 mutant. A partially functional Myc-Pfs1p is localized to the nucleus of mononucleate meiotic cells but not to the spindle pole body or prospore membrane. These results suggest that Pfs1p is specifically required for prospore formation at selected spindle poles, most likely by ensuring the functionality of all four spindle pole bodies of a cell during meiosis II.

Overexpression of Smad2 reveals its concerted action with Smad4 in regulating TGF-beta-mediated epidermal homeostasis

Members of the transforming growth factor-beta (TGF-beta) superfamily are critical regulators for epithelial growth and can alter the differentiation of keratinocytes. Transduction of TGF-beta signaling depends on the phosphorylation and activation of Smad proteins by heteromeric complexes of ligand-specific type I and II receptors. To understand the function of TGF-beta and activin-specific Smad, we generated transgenic mice that overexpress Smad2 in epidermis under the control of keratin 14 promoter. Overexpression of Smad2 increases endogenous Smad4 and TGF-beta 1 expression while heterozygous loss of Smad2 reduces their expression levels, suggesting a concerted action of Smad2 and -4 in regulating TGF-beta signaling during skin development. These transgenic mice have delayed hair growth, underdeveloped ears, and shorter tails. In their skin, there is severe thickening of the epidermis with disorganized epidermal architecture, indistinguishable basement membrane, and dermal fibrosis. These abnormal phenotypes are due to increased proliferation of the basal epidermal cells and abnormalities in the program of keratinocyte differentiation. The ectodermally derived enamel structure is also abnormal. Collectively, our study presents the first in vivo evidence that, by providing an auto-feedback in TGF-beta signaling, Smad2 plays a pivotal role in regulating TGF-beta-mediated epidermal homeostasis.

Post-transplant lymphoproliferative disease in children

Epstein-Barr virus (EBV)-driven post-transplant lymphoproliferative disease (PTLD) is an important cause of morbidity and mortality following transplantation, and it occurs more frequently in children than in adults. Of 22 (5%) children at our institution who developed tissue-proven PTLD 1-60 months (mean 16.5 months) following organ transplant, 11 died: nine of these 22 patients developed PTLD between 1989 and 1993, and seven (78%) died; the remaining 13 developed PTLD between 1994 and 1998, and four (31%) died (p = 0.08). All nine patients who developed PTLD < 6 months after transplant died, but 11 of 13 patients who manifested disease > or = 6 months after transplant survived (p = 0.0002). Ten of 11 (91%) survivors, but only two of eight (25%) children who died, had serologic evidence of EBV infection at the time of PTLD diagnosis (p = 0.04). EBV seroconversion identified patients at risk for developing PTLD, but also characterized patients with sufficient immune function to survive EBV-related lymphoid proliferation. In situ hybridization for EBER1 mRNA was diagnostically helpful because it detected EBV in tissue sections of all 20 patients with B-cell PTLD, including those with negative serology.

Similarity of the song nuclei of male and female Australian magpies (Gymnorhina tibicen)

The organisation of the song control nuclei of the Australian magpie (Gymnorhina tibicen), a species with highly complex song, was investigated. In contrast to most of the songbirds studied so far, the Australian magpie sings throughout the year and both males and females sing. All of the forebrain song nuclei, including the high vocal centre (HVC), the robust nucleus of the archistriatum (RA), Area X and the lateral and medial magnocellular nuclei of the anterior neostriatum (lMAN and mMAN) were found to be well developed in both male and female magpies. Consistent with the known vocal competence of juvenile magpies, all of the song nuclei were also well-developed in juvenile magpies (2--3 months old). HVC in both male and female magpies consists of a rostrolateral and a caudomedial region. The ventromedial part of RA differs from the dorsolateral part by having medium-sized neurons packed in higher density. The HVC to RA projections were labelled anterogradely by DiI and DiA. However, no HVC to Area X projections were labeled by DiI or DiA, suggesting a possible difference from songbirds studied previously.

Functional characterization of transforming growth factor beta signaling in Smad2- and Smad3-deficient fibroblasts

A prominent pathway of transforming growth factor (TGF)-beta signaling involves receptor-dependent phosphorylation of Smad2 and Smad3, which then translocate to the nucleus to activate transcription of target genes. To investigate the relative importance of these two Smad proteins in TGF-beta1 signal transduction, we have utilized a loss of function approach, based on analysis of the effects of TGF-beta1 on fibroblasts derived from mouse embryos deficient in Smad2 (S2KO) or Smad3 (S3KO). TGF-beta1 caused 50% inhibition of cellular proliferation in wild-type fibroblasts as assessed by [(3)H]thymidine incorporation, whereas the growth of S2KO or S3KO cells was only weakly inhibited by TGF-beta1. Lack of Smad2 or Smad3 expression did not affect TGF-beta1-induced fibronectin synthesis but resulted in markedly suppressed induction of plasminogen activator inhibitor-1 by TGF-beta1. Moreover, TGF-beta1-mediated induction of matrix metalloproteinase-2 was selectively dependent on Smad2, whereas induction of c-fos, Smad7, and TGF-beta1 autoinduction relied on expression of Smad3. Investigation of transcriptional activation of TGF-beta-sensitive reporter genes in the different fibroblasts showed that activation of the (Smad binding element)(4)-Lux reporter by TGF-beta1 was dependent on expression of Smad3, but not Smad2, whereas activation of the activin response element-Lux reporter was strongly suppressed in S2KO fibroblasts but, on the contrary, enhanced in S3KO cells. Our findings indicate specific roles for Smad2 and Smad3 in TGF-beta1 signaling.

Unexpected effects of a heterozygous dnmt1 null mutation on age-dependent DNA hypomethylation and autoimmunity

DNA methylation modifies gene expression. Methylation patterns are established during ontogeny, but they change with aging, usually with a net decrease in methylation. The significance of this change in T cells is unknown, but it could contribute to autoimmunity, senescence, or both. We examined the effects of a null mutation in DNA methyltransferase 1 (Dnmt1), a gene maintaining DNA methylation patterns, on immune aging. Whereas aged control mice developed hypomethylated DNA, autoimmunity, and signs of immune senescence as predicted, the knockout mice surprisingly increased DNA methylation and developed signs of autoimmunity and senescence more slowly. To identify potential mechanisms, we compared transcripts of DNA methyltransferase and methylcytosine binding protein family members in control and knockout mice. MeCP2, a methylcytosine binding protein involved in gene suppression and chromatin inactivation, was the only transcript differentially expressed between old knockout mice and controls, and thus it is a candidate for a gene product mediating these effects.

[Investigation on an outbreak of Legionnaires' disease caused by Lboz in a suburb of Beijing]

OBJECTIVE

To demonstrate the infectious rates and incidence rates through epidemiological investigation.

METHODS

Serum samples from 203 new soldiers were detected from Lboz by TAT.

RESULTS

Infectious rates was 33.00% (67/203), and the incidence rates was 8.87% (18/203) with 2 cases of pneumonic type and 16 cases of pontiac fever type.

CONCLUSION

The results suggested that an outbreak of Legionnaires' desease caused by Legionella bozemanii (Lboz) took place in a suburb of Beijing. However the report of the outbreak caused by Lboz had not been found in related references.

Human cytochrome P450 isozymes in metabolism and health effects of gasoline ethers

To reduce the production of carbon monoxide and other pollutants in motor vehicle exhaust, methyl tert-butyl ether (MTBE*), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME) are added to gasoline as oxygenates for more complete combustion. Among them, MTBE is the most widely used. The possible adverse effect of MTBE in humans is a public concern, but the human enzymes responsible for metabolism of these gasoline ethers and the causes or factors for increased sensitivity to MTBE in certain individuals are totally unknown. This information is important to understanding the health effects of MTBE in humans and to assessing the human relevance of pharmacokinetics and toxicity data obtained from animals. In the present study, we demonstrated that human liver is active in metabolizing MTBE to tert-butyl alcohol (TBA), a major circulating metabolite and an exposure marker of MTBE. The activity is localized in the microsomal fraction but not in the cytosol. Formation of TBA in human liver microsomes is NADPH-dependent and is significantly inhibited by carbon monoxide, which inhibits cytochrome P450 (CYP) enzymes. These results provide strong evidence that CYP enzymes play a critical role in the metabolism of MTBE in human livers. Human liver is also active in the oxidative metabolism of 2 other gasoline ethers, ETBE and TAME. We observed a large interindividual variation in metabolizing these gasoline ethers in 15 microsomal samples prepared from normal human livers. The activity level (pmol metabolite/min/mg) ranged from 204 to 2,890 for MTBE; 179 to 3,134 for ETBE; and 271 to 8,532 for TAME. The microsomal activities in metabolizing MTBE, ETBE, and TAME correlated highly with each other (r = 0.91 to 0.96), suggesting that these ethers are metabolized by the same enzyme(s). Correlation analysis of the ether-metabolizing activities with individual CYP enzyme activities in the human liver microsomes showed that the highest degree of correlation was with CYP isoform 2A6 (CYP2A6)+ (r = 0.94 for MTBE, 0.95 for ETBE, and 0.90 for TAME), which is constitutively expressed in human livers and known to be polymorphic. CYP2A6 displayed the highest turnover number in metabolizing gasoline ethers among a battery of human CYP enzymes expressed in human B-lymphoblastoid cells. CYP2A6 coexpressed with human CYP reductase by a baculovirus expression system was also more active than CYP isoform 2E1 (CYP2E1) in the metabolism of MTBE, ETBE, and TAME. Kinetic studies on MTBE metabolism with human liver microsomes (n = 3) exhibited an apparent Michaelis constant (Km) of 28 to 89 microM and a maximum rate of metabolism (Vmax) of 215 to 783 pmol/min/mg. Metabolism of MTBE, ETBE, and TAME by human liver microsomes was inhibited by coumarin, a known substrate of human CYP2A6, in a concentration-dependent manner. Monoclonal antibody against human CYP2A6 caused a significant inhibition (75% to 95%) of the metabolism of MTBE, ETBE, and TAME in human liver microsomes. Taken together, these results clearly indicate that, in human liver, CYP2A6 is a major enzyme responsible for metabolism of MTBE, ETBE, and TAME. Although CYP2E1 metabolizes diethyl ether and was previously suggested to be involved

[Hypermethylation of the calcitonin gene as molecular genetic marker in detecting minimal residual disease of leukemia]

OBJECTIVE

To explore whether detecting minimal residual disease (MRD) of leukemia with hypermethylation of the calcitonin gene as molecular genetic marker of leukemic clone may predict the prognosis.

METHODS

Polymerase chain reaction (PCR) in combination with digestion of DNA with HpaII was used to examine the methylation patterns of the calcitonin gene in 29 cases with acute leukemia and 8 cases with transformation of chronic myeloid leukemia. By using PCR, MRD was longitudinally detected in patients who were positive for hypermethylation of the calcitonin gene as molecular genetic marker.

RESULTS

Twenty patients with acute leukemia and transformation of chronic myeloid leukemia had MRD after complete remission. Bone marrow relapse occurred soon when MRD persisted or reappeared. It may predict bone marrow relapse two to eleven months earlier. The patients who were negative for MRD early and remained persistently negative may acquire prolonged survival.

CONCLUSION

MRD of leukemia may be monitored by using PCR with hypermethylation of the calcitonin gene as molecular genetic marker for leukemic clone. It may prove useful in predicting the prognosis of leukemia.

Mice expressing only monosialoganglioside GM3 exhibit lethal audiogenic seizures

Gangliosides are a family of glycosphingolipids that contain sialic acid. Although they are abundant on neuronal cell membranes, their precise functions and importance in the central nervous system (CNS) remain largely undefined. We have disrupted the gene encoding GD3 synthase (GD3S), a sialyltransferase expressed in the CNS that is responsible for the synthesis of b-series gangliosides. GD3S-/- mice, even with an absence of b-series gangliosides, appear to undergo normal development and have a normal life span. To further restrict the expression of gangliosides, the GD3S mutant mice were crossbred with mice carrying a disrupted GalNAcT gene encoding beta1,4-N-acetylgalactosaminyltransferase. These double mutant mice expressed GM3 as their major ganglioside. In contrast to the single mutant mice, the double mutants displayed a sudden death phenotype and were extremely susceptible to induction of lethal seizures by sound stimulus. These results demonstrate unequivocally that gangliosides play an essential role in the proper functioning of the CNS.

[Study on hypermethylation of the calcitonin gene in malignant hematological disorders]

OBJECTIVE

To investigate the clinical significance of hypermethylation of the calcitonin (CT) gene in malignant hematological disorders (MHD).

METHODS

Polymerase chain reaction (PCR) in combination with digestion of DNA with Hpa II was used to examine the methylation patterns of the CT gene in 73 patients with MHD, 6 healthy people and 24 patients with nonmalignant hematological disorders (NON-MHD).

RESULTS

Hypermethylation of the CT gene occurred in 12 of 14 (85.7%) patients with acute lymphoblastic leukemia (ALL), 9 of 15 (60%) acute nonlymphocytic leukemia (ANLL), 8 of 10 (80%) chronic myelogenous leukemia (CML), 5 of 15 (33.3%) malignant lymphoma (ML), 2 of 5 patients with myelodysplastic syndrome (MDS), 1 of 2 malignant histiocytosis (MH), 1 of 3 chronic lymphocytic leukemia (CLL) and 1 of 9 multiple myeloma (MM). However, it did not occur in normal controls and NON-MHD.

CONCLUSION

Hypermethylation of CT gene may serve as an important molecular maker for tumorous cell clone and may be useful in diagnosing MHD, monitoring minimal residual disease and predicting prognosis.

A Ser(365)-->Cys mutation of fibroblast growth factor receptor 3 in mouse downregulates Ihh/PTHrP signals and causes severe achondroplasia

Missense mutations in fibroblast growth factor receptor 3 (FGFR3) result in several types of human skeletal dysplasia, including the neonatally lethal dwarfism known as thanatophoric dysplasia. An engineered Ser(365)-->Cys substitution in mouse FGFR3, which is equivalent to a mutation associated with thanatophoric dysplasia-I in humans, has now been shown to cause severe dwarfism but not neonatal death. The mutant mice exhibit shortened limbs as a result of markedly reduced proliferation and impaired differentiation of growth plate chondrocytes. The receptor-activating mutation also resulted in downregulation of expression of the Indian hedgehog (IHH) and parathyroid hormone-related protein (PTHrP) receptor genes, both of which are important for bone growth. Interactions between FGFR3- and PTHrP-receptor-mediated signals during endochondral ossification were examined with embryonic metatarsal bones maintained in culture under defined conditions. Consistent with the in vivo observations, FGF2 inhibited bone growth in culture and induced downregulation of IHH and PTHrP receptor gene expression. Furthermore, PTHrP partially reversed the inhibition of long bone growth caused by activation of FGFR3; however, it impaired the differentiation of chondrocytes in an FGFR3-independent manner. These observations suggest that FGFR3 and IHH-PTHrP signals are transmitted by two interacting parallel pathways that mediate both overlapping and distinct functions during endochondral ossification.

Fas/Fas ligand pathway, apoptosis, and clonal anergy involved in systemic acetylcholine receptor T cell epitope tolerance

The cellular mechanisms of high dose systemic acetylcholine receptor (AChR) T cell epitope, alpha 146--162 peptide-induced tolerance in experimental myasthenia gravis were examined. CD4 cells are the prime target for alpha 146--162 peptide-induced tolerance. The expression of CD69, Fas, and B7.2 molecules on AChR-immune lymphocytes was enhanced within 4--12 h after tolerance induction. A high dose of alpha 146--162 peptide in IFA failed to suppress T cell proliferation and/or clinical myasthenia gravis in lpr and gld mice deficient in Fas and Fas ligand, respectively. A high dose of alpha 146--162 peptide in IFA in AChR-immunized mice induced apoptosis of BV6 cells. Further, reconstitution of IL-2 in vitro-recovered alpha 146--162 peptide tolerized T cell proliferation, IFN-gamma, and IL-10 production. The findings implicate the possible role of Fas-/Fas ligand-mediated apoptosis and the resulting clonal anergy as the mechanisms of high dose AChR alpha 146--162 peptide-induced tolerance on CD4 cells.

Role of nerve growth factor in experimental autoimmune encephalomyelitis

The expression of neural regulatory molecules by immune cells that infiltrate the nervous system upon injury may be a mechanism for cross-regulation between the nervous system and the immune system. Several lines of evidence implicate nerve growth factor (NGF) signaling through its receptors (TrkA and p75(NGFR)) as a potential source of communication between the two systems. We observed changes in NGF mRNA expression and protein secretion by T lymphocytes polarized toward the Th2 phenotype. The presence of NGF did not affect T cell proliferation or cytokine production in vitro. Mice treated with NGF by i. p. injection following induction of experimental autoimmune encephalomyelitis, an inflammatory, demyelinating disease of the central nervous system, showed a delayed onset of disease and lower clinical scores during the course of disease. These data suggest a role for NGF signaling in the regulation of the immune response, possibly by enhancing sympathetic innervation of lymphoid tissues.

Decreased Ras-mitogen-activated protein kinase signaling may cause DNA hypomethylation in T lymphocytes from lupus patients

OBJECTIVE

Previous studies have shown that inhibiting T cell DNA methylation causes a lupus-like disease by modifying gene expression. T cells from patients with lupus exhibit diminished levels of DNA methyltransferase (MTase) enzyme activity, hypomethylated DNA, and changes in gene expression similar to those exhibited by T cells treated with methylation inhibitors, suggesting that DNA hypomethylation may contribute to human lupus. Since it is known that DNA MTase levels are regulated by the ras-mitogen-activated protein kinase (MAPK) pathway, this study sought to determine whether decreased ras-MAPK signaling could account for the DNA hypomethylation in lupus T cells.

METHODS

DNA MTase messenger RNA (mRNA) from lupus patients and from healthy controls was quantitated by Northern analysis, and ras-MAPK signaling was determined by immunoblotting with antibodies to the activated forms of extracellular receptor-associated kinase (ERK). Results were compared with those in T cells in which ras-MAPK signaling was inhibited with a soluble inhibitor of MAPK ERK I (MEK1).

RESULTS

T cells from patients with active lupus had diminished DNA MTase mRNA levels and decreased signaling through the ras-MAPK pathway. Inhibiting signaling through the ras-MAPK pathway with the MEK1 inhibitor decreased DNA MTase mRNA and enzyme activity to the levels seen in lupus T cells, and resulted in DNA hypomethylation resembling that seen in lupus T cells.

CONCLUSION

These results suggest that a decrease in signaling through the ras-MAPK pathway may be responsible for the decreased MTase activity and DNA hypomethylation in patients with lupus.

Lymphotoxin-alpha deficiency completely protects C57BL/6 mice from developing clinical experimental autoimmune myasthenia gravis

A complete prevention of clinical experimental autoimmune myasthenia gravis (EAMG) was observed in lymphotoxin (LT)-alpha deficient (LT-alpha(-/-)) mice compared to LT-alpha(+/+) mice when immunized with acetylcholine receptor. However, only a partial prevention of clinical EAMG incidence was observed in LT-beta(-/-) mice compared to LT-beta(+/+) mice. LT-alpha(-/-)and LT-beta(-/-) mice had lower mean titers of total IgG, IgG(1), IgG(2a) and IgG(2b) and higher or equal mean titers of IgM anti-AChR antibodies compared to controls. Therefore, LT-alpha(-/-)and LT-beta(-/-) AChR immunized mice are capable of mounting a primary (IgM) humoral immune response to AChR, but are less capable of switching to the pathogenic anti-AChR IgG isotypes. LT could play a significant role in the pathogenesis of myasthenia gravis.

Detecting hormesis using a non-parametric rank test

When a dose-response experiment is conducted, the enhanced responses can be observed at low doses. This phenomenon is often called hormesis. The enhanced responses at low doses does not necessarily mean the existence of hormesis. It is important to conduct statistical analyses to determine whether a departure from monotonic relationships is significantly different from the chance occurrence. This paper introduces a non-parametric rank test to detect hormesis. To illustrate the use of this method, we apply it to the data from a Whole Effluent Toxicity test. We demonstrate that the occurrence of hormesis can be statistically evaluated by using this non-parametric rank test.

Generation and phenotype of mice harboring a nonsense mutation in the V2 vasopressin receptor gene

The V2 vasopressin receptor (V2R) plays a key role in the maintenance of a normal body water balance. To generate an in vivo model that allows the physiological and molecular analysis of the role of V2Rs in kidney function, we have created mouse lines that lack functional V2Rs by using targeted mutagenesis in mouse embryonic stem cells. Specifically, we introduced a nonsense mutation known to cause X-linked nephrogenic diabetes insipidus (XNDI) in humans (Glu242stop) into the mouse genome. V2R-deficient hemizygous male pups showed a decrease in basal urine osmolalities and were unable to concentrate their urine. These pups also exhibited an enlargement of renal pelvic space, failed to thrive, and died within the first week after birth due to hypernatremic dehydration. Interestingly, female mice heterozygous for the V2R mutation showed normal growth but displayed an XNDI-like phenotype, characterized by reduced urine concentrating ability of the kidney, polyuria, and polydipsia. Western blot analysis and immunoelectron microscopic studies showed that the loss of functional V2Rs had no significant effect on the basal expression levels of aquaporin-2 and the bumetanide-sensitive Na-K-2Cl cotransporter (BSC-1). The V2R mutant mice described here should serve as highly useful tools for the development of novel therapeutic strategies for the treatment of XNDI.

Resistance to apoptosis in HIV-infected CD4+ T lymphocytes is mediated by macrophages: role for Nef and immune activation in viral persistence

Apoptosis or programmed cell death may play a critical role in AIDS pathogenesis through depletion of both CD4(+) and CD8(+) T lymphocytes. Using a reporter virus, a recombinant HIV infectious clone expressing the green fluorescent protein (GFP), apoptosis was measured in productively infected CD4(+) T lymphocytes, in the presence and absence of autologous macrophages. The presence of macrophages in the culture increased the frequency of nonapoptotic GFP-positive productively infected CD4(+) T lymphocytes. The appearance of nonapoptotic productively infected CD4(+) T lymphocytes in the culture required intercellular contacts between macrophages and PBLs and the expression of the HIV Nef protein. The presence of macrophages did not reduce apoptosis when CD4(+) T lymphocytes were infected with a GFP-tagged virus deleted for the nef gene. TNF-alpha (TNF) expressed on the surface of macrophages prevented apoptosis in nef-expressing, productively infected CD4(+) T lymphocytes. Similarly, following TNF stimulation, apoptosis was diminished in Jurkat T cells transfected with a nef-expressing plasmid. TNF stimulation of nef-expressing Jurkat T cells resulted in NF-kappaB hyperactivation, which has been shown to deliver anti-apoptotic signals. Our results indicate that intercellular contacts with macrophages increase the rate of productively infected nonapoptotic CD4(+) T lymphocytes. The survival of productively infected CD4(+) T lymphocytes requires Nef expression as well as activation by TNF expressed on the surface of macrophages and might participate in the formation and maintenance of viral reservoirs in HIV-infected persons.

DNA methylation in the regulation of T cell LFA-1 expression

Inducing T cell LFA-1 overexpression by transfection, or by treatment with DNA methylation inhibitors including 5-azacytidine, procainamide and hydralazine, causes MHC-specific T cell autoreactivity in vitro and autoimmunity in vivo. How DNA methylation inhibitors increase LFA-1 expression is unknown. In this report we identify a mechanism by which DNA methylation affects LFA-1 expression. Nuclear run-on assays demonstrated that inhibiting DNA methylation increased transcription of CD11a but not CD18 or beta-actin mRNA. CD11a mRNA stability was not affected. Transfection of hypomethylated cells with reporter constructs containing the CD11a promoter showed no role for overexpression of transcription factors. However, the CD11a promoter demethylated following treatment with DNA methyltransferase inhibitors, and in vitro methylation of the construct suppressed its expression. Together, these results indicate that DNA methylation inhibitors can cause LFA-1 overexpression directly by demethylating the CD11a promoter. This mechanism could contribute to T cell autoreactivity, and potentially to autoimmunity.

[Clinical study on interferon treatment of chronic idiopathic thrombocytopenic purpura]

The efficacy and mechanism of interferon alpha-2a (IFN alpha-2a) were assessed in the treatment of chronic idiopathic thrombocytopenic purpura (cITP). 20 patients with cITP (treatment group) were treated with IFN alpha-2a 3MIU i.m. once a week for 8 weeks; 28 patients with cITP (control group) were treated with prednisone 1 mg/(kg.d) for 4 weeks. Blood platelet counts (BPC), megakaryocyte number, immunnological parameters, percent and absolute counts of reticulated platelets (RPs) and megakaryocyte colony formation units were observed before and after therapy. The results showed that the efficacy of IFN alpha-2a was better than that of corticosteroid, P < 0.05. The RPs% decreased and the platelet-producing megakaryocyte percentage increased from 11.43% to 33.19% significantly after IFN alpha-2a therapy, but there were no significant changes in immunnological parameters. These indicate that IFN alpha-2a is effective in treating cITP, the mechanism may be based on promoting the megakaryocyte development and activating the production of platelets.

Functional collaboration between different cyclin-dependent kinase inhibitors suppresses tumor growth with distinct tissue specificity

The presence of two families of seven distinct mammalian cyclin-dependent kinase (CDK) inhibitor genes is thought to mediate the complexity of connecting a variety of cellular processes to the cell cycle control pathway. The distinct pattern of tissue expression of CDK inhibitor genes suggests that they may function as tumor suppressors with different tissue specificities. To test this hypothesis, we have characterized two strains of double mutant mice lacking either p18(INK4c) and p27(KIP1) or p18(INK4c) and p21(CIP1/WAF1). Loss of both p18 and p27 function resulted in the spontaneous development by 3 months of age of at least eight different types of hyperplastic tissues and/or tumors in the pituitary, adrenals, thyroid, parathyroid, testes, pancreas, duodenum, and stomach. Six of these hyperplastic tissues and tumors were in endocrine organs, and several types of tumors routinely developed within the same animal, a phenotype reminiscent of that seen in combined human multiple endocrine neoplasia syndromes. The p18-p21 double null mice, on the other hand, developed pituitary adenomas, multifocal gastric neuroendocrine hyperplasia, and lung bronchioalveolar tumors later in life. G(1) CDK2 and CDK4 kinase activities were increased in both normal and neoplastic tissues derived from mice lacking individual CDK inhibitors and were synergistically stimulated by the simultaneous loss of two CDK inhibitors. This indicates that an increase in G(1) CDK kinase activity is a critical step during but is not sufficient for tumor growth. Our results suggest that functional collaborations between distinct CDK inhibitor genes are tissue specific and confer yet another level of regulation in cell growth control and tumor suppression.

The steroid receptor coactivator SRC-3 (p/CIP/RAC3/AIB1/ACTR/TRAM-1) is required for normal growth, puberty, female reproductive function, and mammary gland development

Steroid receptor coactivator-3 (SRC-3) is a coactivator of nuclear receptors in the SRC family as assayed in vitro. Here, we show that mouse SRC-3 is expressed in a tissue-specific fashion and distributed mainly in the oocytes, mammary glands, hippocampus, olfactory bulb, smooth muscle, hepatocytes, and vaginal epithelium. Genetic disruption of SRC-3 in mice results in a pleiotropic phenotype showing dwarfism, delayed puberty, reduced female reproductive function, and blunted mammary gland development. Hormonal analysis indicates that SRC-3 plays a role in both the growth hormone regulatory pathway and the production of estrogen, which may explain the observed phenotypes. These results suggest that the physiological role of SRC-3 is different from that of SRC-1 and prove the diversity among coactivator family members.

Disability case management: an impact assessment in an automotive manufacturing organization

A multifaceted disability management program was instituted at an automotive manufacturing organization to control rising workers' compensation costs. A pilot program showed major cost savings over a 9-month period. When total and component disability leave rates were calculated as a percentage of the available workforce and tracked on a weekly basis over the subsequent 3 years, total disability leave rates fell by nearly 50%. This was largely attributable to an approximately 50% decrease in the extended (> 1-year) disability leave rate and a 75% decrease in the workers' compensation leave rate. A novel approach to biostatistical analysis showed a good fit of weekly disability leave rates to a Poisson random variable distribution with an identifiable break point at about 1 1/2 years after observation for extended disability leaves and at 2 years for workers' compensation leaves. This biostatistical approach may prove generalizable to tracking leave rates in other organizations.

Lack of obesity and normal response to fasting and thyroid hormone in mice lacking uncoupling protein-3

Uncoupling protein-3 (UCP3) is a mitochondrial protein that can diminish the mitochondrial membrane potential. Levels of muscle Ucp3 mRNA are increased by thyroid hormone and fasting. Ucp3 has been proposed to influence metabolic efficiency and is a candidate obesity gene. We have produced a Ucp3 knockout mouse to test these hypotheses. The Ucp3 (-/-) mice had no detectable immunoreactive UCP3 by Western blotting. In mitochondria from the knockout mice, proton leak was greatly reduced in muscle, minimally reduced in brown fat, and not reduced at all in liver. These data suggest that UCP3 accounts for much of the proton leak in skeletal muscle. Despite the lack of UCP3, no consistent phenotypic abnormality was observed. The knockout mice were not obese and had normal serum insulin, triglyceride, and leptin levels, with a tendency toward reduced free fatty acids and glucose. Knockout mice showed a normal circadian rhythm in body temperature and motor activity and had normal body temperature responses to fasting, stress, thyroid hormone, and cold exposure. The base-line metabolic rate and respiratory exchange ratio were the same in knockout and control mice, as were the effects of fasting, a beta3-adrenergic agonist (CL316243), and thyroid hormone on these parameters. The phenotype of Ucp1/Ucp3 double knockout mice was indistinguishable from Ucp1 single knockout mice. These data suggest that Ucp3 is not a major determinant of metabolic rate but, rather, has other functions.

Functions of mammalian Smad genes as revealed by targeted gene disruption in mice

The Smad genes are the intracellular mediators of TGF-beta signals. Targeted mutagenesis in mice has yielded valuable new insights into the functions of this important gene family. These experiments have shown that Smad2 and Smad4 are needed for gastrulation, Smad5 for angiogenesis, and Smad3 for establishment of the mucosal immune response and proper development of the skeleton. In addition, these experiments have shown us the importance of gene dosage in this family, as several of its members yielded haploinsufficiency phenotypes. These include gastrulation and craniofacial defects for Smad2, accelerated wound healing for Smad3, and the incidence of gastric cancer for Smad4. Combinatorial genetics has also revealed functions of Smads in left/right isomerism and liver development.

Organization of intratelencephalic projections to the visual Wulst of the chick

The avian visual Wulst, said to be the equivalent of the striate cortex in mammals, is the telencephalic visual area of the thalamofugal visual pathway. In this study, by means of retrograde labelling with fluorescent tracers injected into the Wulst regions in the left and right hemispheres, we have investigated the organization of the intratelencephalic projections to the visual Wulst in chicks. After injecting Fluorogold (FG), True blue (TB) or rhodamine into the visual Wulst, fluorescent-labelled neurones were found in the ipsilateral neostriatum frontale, pars lateralis (NFl), the ipsilateral neostriatum intermedium (NI) and the ipsilateral dorso-lateral neostriatum. Labelled neurones were also found in both the ipsilateral and contralateral archistriata. In addition, some neurones in the archistriatum were double-labelled, which indicates that these archistriatal neurones have axon collaterals projecting to the visual Wulst on both sides of the forebrain. Through these intratelencephalic afferents to the visual Wulst, visual information transmitted in the thalamofugal pathway may be modulated by other telencephalic areas. The possible roles of these connections in regulating behaviour are discussed.

Animal models of myasthenia gravis

Myasthenia gravis (MG) is an antibody-mediated, autoimmune neuromuscular disease. Animal models of experimental autoimmune myasthenia gravis (EAMG) can be induced in vertebrates by immunization with Torpedo californica acetylcholine receptors (AChR) in complete Freund's adjuvant. The MHC class II genes influence the cellular and humoral immune response to AChR and are involved in the development of clinical EAMG in mice. A dominant epitope within the AChR alpha146-162 region activates MHC class II-restricted CD4 cells and is involved in the production of pathogenic anti-AChR antibodies by B cells. Neonatal or adult tolerance to this T-cell epitope could prevent EAMG. During an immune response to AChR in vivo, multiple TCR genes are used. The CD28-B7 and CD40L-CD40 interaction is required during the primary immune response to AChR. However, CTLA-4 blockade augmented T- and B-cell immune response to AChR and disease. Cytokines IFN-gamma and IL-12 upregulate, while IFN-alpha downregulates, EAMG pathogenesis. However, the Th2 cytokine IL-4 fails to play a significant role in the development of antibody-mediated EAMG. Systemic or mucosal tolerance to AChR or its dominant peptide(s) has prevented EAMG in an antigen-specific manner. Antigen-specific tolerance and downregulation of pathogenic cytokines could achieve effective therapy of EAMG and probably MG.

[Effects of protocol HX-97 on mobilization, collection and hematopoietic reconstitution of peripheral blood stem cells transplantation]

In order to enhance the effects of peripheral blood stem cell mobilization, collection and hematopoietic reconstitution, we observed and evaluated the effects of Protocol HX-97 on 22 patients who received allogeneic or autologous peripheral blood stem cell transplants from April 1997 to June 1999. rhG-CSF was used for mobilization at a dose of 300 micrograms/day for 6 days; the sixth dose was given an hour and a half before leukapheresis. High dose chemotherapy and rhG-CSF were given for autologous peripheral blood stem cell mobilization; the chemotherapy should be intensive enough to reduce the patients' peripheral WBC to less than 1.0 x 10(9)/L, and the beginning of using rhG-CSF should be just at the time of WBC's rising from the nadir. rhGM-CSF and rhG-CSF were given sequentially for hematopoietic reconstitution after transplantation. The results showed that leukaphereses were successfully performed for peripheral blood stem cell collection. Sixteen cases needed apheresis only once, and 6 cases needed it twice. The harvests were 2.5-10.7 x 10(8)/kg MNC, 2.5-20.0 x 10(6)/kg CD34+ cells (including 1.8-7.5 x 10(6)/kg CD34+CD33-, 0.7-12.5 x 10(6)/kg CD34+CD33+), and 3.5-6.3 x 10(5)/kg CFU-GM. Hematopoietic function recovered to > 0.5 x 10(9)/L of neutrophil count in allo-PBSCT at 14-20 days and in auto-PBSCT at 12-20 days, and to > 20 x 10(9)/L of platelet count in allo-PBSCT and in auto-PBSCT at 16-34 days and 16-28 days, respectively. At day +30 post-transplantation, chromosome analysis and DNA finger print assessment of bone marrow cells indicated that the patients' hematopoietic function had been reconstituted. This study suggests that Protocol HX-97 is an effective approach to mobilization of peripheral blood stem cell transplantation, and it is relatively cost-effective.

Mice lacking Smad3 show accelerated wound healing and an impaired local inflammatory response

The generation of animals lacking SMAD proteins, which transduce signals from transforming growth factor-beta (TGF-beta), has made it possible to explore the contribution of the SMAD proteins to TGF-beta activity in vivo. Here we report that, in contrast to predictions made on the basis of the ability of exogenous TGF-beta to improve wound healing, Smad3-null (Smad3ex8/ex8) mice paradoxically show accelerated cutaneous wound healing compared with wild-type mice, characterized by an increased rate of re-epithelialization and significantly reduced local infiltration of monocytes. Smad3ex8/ex8 keratinocytes show altered patterns of growth and migration, and Smad3ex8/ex8 monocytes exhibit a selectively blunted chemotactic response to TGF-beta. These data are, to our knowledge, the first to implicate Smad3 in specific pathways of tissue repair and in the modulation of keratinocyte and monocyte function in vivo.

[Effect of in vitro interferon on bone marrow megakaryocyte in patients with idiopathic thrombocytopenic purpura]

The effect of rIFN alpha-2a on the megakaryocyte colony growth and maturation was observed in 33 patients with idiopathic thrombocytopenic purpura (CITP) in vitro by plasma clot cultures and by GP III a McAb and ABC kit. Twenty five healthy persons were in the control group. The results showed that the number of colony formation units of megakaryocyte in the patients was similar to that in the controls, but the diameter and area levels of megakaryocyte in the patients were lower. The ratio of inhibition of rIFN alpha-2a on megakaryocyte progenitors colony growth was significantly lower in the patients and was lowest in the group with increasing number of megakaryocytes on bone marrow smear. The rIFN alpha-2a had no effect on promoting the megakaryocyte maturation. Since this study has indicated that the inhibition of rIFN alpha-2a on colony formation unit of megakaryocyte is slight in CITP, interferon therapy should be a suitable prescription for the CITP patients who have an increasing number of megakaryocyte on bone marrow smear.

Enhancement of D1 dopamine receptor-mediated locomotor stimulation in M(4) muscarinic acetylcholine receptor knockout mice

Muscarinic acetylcholine receptors (M(1)-M(5)) regulate many key functions of the central and peripheral nervous system. Primarily because of the lack of receptor subtype-selective ligands, the precise physiological roles of the individual muscarinic receptor subtypes remain to be elucidated. Interestingly, the M(4) receptor subtype is expressed abundantly in the striatum and various other forebrain regions. To study its potential role in the regulation of locomotor activity and other central functions, we used gene-targeting technology to create mice that lack functional M(4) receptors. Pharmacologic analysis of M(4) receptor-deficient mice indicated that M(4) receptors are not required for muscarinic receptor-mediated analgesia, tremor, hypothermia, and salivation. Strikingly, M(4) receptor-deficient mice showed an increase in basal locomotor activity and greatly enhanced locomotor responses (as compared with their wild-type littermates) after activation of D1 dopamine receptors. These results indicate that M(4) receptors exert inhibitory control on D1 receptor-mediated locomotor stimulation, probably at the level of striatal projection neurons where the two receptors are coexpressed at high levels. Our findings offer new perspectives for the treatment of Parkinson's disease and other movement disorders that are characterized by an imbalance between muscarinic cholinergic and dopaminergic neurotransmission.

A vital role for glycosphingolipid synthesis during development and differentiation

Glycosphingolipids (GSLs) are believed to be integral for the dynamics of many cell membrane events, including cellular interactions, signaling, and trafficking. We have investigated their roles in development and differentiation by eliminating the major synthesis pathway of GSLs through targeted disruption of the Ugcg gene encoding glucosylceramide synthase. In the absence of GSL synthesis, embryogenesis proceeded well into gastrulation with differentiation into primitive germ layers and patterning of the embryo but was abruptly halted by a major apoptotic process. In vivo, embryonic stem cells deficient in GSL synthesis were again able to differentiate into endodermal, mesodermal, and ectodermal derivatives but were strikingly deficient in their ability to form well differentiated tissues. In vitro, however, hematopoietic and neuronal differentiation could be induced. The results demonstrate that the synthesis of GSL structures is essential for embryonic development and for the differentiation of some tissues and support the concept that GSLs are involved in crucial cell interactions mediating these processes.

[The effects of Xuezhikang on serum lipid profile, thromboxane A2 and prostacyclin in patients with hyperlipidemia]

OBJECTIVE

To study the effects of Xuezhikang on lipid profile, thromboxane (TX) A(2), prostacyclin (PGI(2)) in patients with hyperlipidemia.

METHODS

91 patients with hyperlipidemia were randomly divided into a treatment group (n = 47, Xuezhikang 1.2 g/d Bid, p.o) and control group (n = 44, gemfibrozil 1.2 g/d Bid, p.o). serum lipids, TXB(2) and 6-Keto-PGF(1alpha) were determined before and 8 weeks after the treatment.

RESULTS

(1) After 8 weeks of treatment, the level of serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) decreased by 21.6% (P < 0.01) and 33.3% (P < 0. 01) in the Xuezikang group and by 20.4% (P < 0.01) and 24.8% (P < 0.01) in the gemfibrozil group respectively. Serum high density lipoprotein cholesterol (HDL-C) level elevated by 33.7% in the Xuezhikang group (P < 0.01) and 26.9% in the gemfibrozil group (P < 0.01). The effect of Xuezhikang was the same as gemfibrozil. There was no statistically significant difference between the effects of these two drugs. Triglyceride (TG) level decreased by 23.3% in the Xuezhikang group (P < 0.01) and 40.3% in the gemfibrozil group (P < 0.01). TG lowering effect of gemfibrozil was superior to that of Xuezhikang (P < 0.05). (2) The level of lipoprotein (a) [LP (a)] in the plasma decreased by 28.2% (P < 0.01) in the Xuezhikang group and by 4.9% (P > 0.05) in the gemfibrozil group. LP (a) lowering effect of Xuezhikang was superior to that of gemfibrozil (P < 0.01). (3)The Level of thromboxane (TX) B(2) in the plasma decreased by 34.2% in the Xuezhikang group (P < 0.01) and by 8.4% in the gemfibrozil group (P < 0.01). TXB(2) lowering effect of Xuezhikang was superior to that of gemfibrozil (P < 0.01). The level of 6-KetO-PGF(1alpha) in the plasma elevated by 65.4% in the Xuezhikang group (P < 0.01) and by 11.7% in the gemfibrozil group (P < 0.01); the effect of Xuezhikang was superior to that of gemfibrozil (P < 0.01).

CONCLUSION

Xuezhikang could markedly decrease the level of TC and LDL-C and elevate that of HDL-C in patients with hyperlipidemia and the effects of Xuezhikang were the same as those of gemfibrozil. TG lowering effect of gemfibrozil was superior to that of Xuezhikang, but Xuezhikang could markedly decrease the level of Lp (a) and regluate the balance between TXA(2) and PGI(2), its effect being superior to that of gemfibrozil.

Analysis of human peripheral blood T cells and single-cell-derived T cell clones uncovers extensive clonal CpG island methylation heterogeneity throughout the genome

Methylation of cytosine residues in CpG dinucleotides is generally associated with silencing of gene expression. DNA methylation, as a somatic event, has the potential of diversifying gene expression in individual cells of the same lineage. There is little quantitative data available concerning the extent of methylation heterogeneity in individual cells across the genome. T cells from the peripheral blood can be grown as single-cell-derived clones and can be analyzed with respect to their DNA methylation patterns by restriction landmark genomic scanning. The use of the methylation-sensitive enzyme NotI to cut and end-label DNA fragments before their separation in two dimensions provides a quantitative assessment of methylation at NotI sites that characteristically occur in CpG islands. We have undertaken quantitative analysis of two-dimensional DNA patterns to determine the extent of methylation heterogeneity at NotI sites between peripheral blood single-cell-derived T cell clones from the same individual. A total of 1,068 NotI-tagged fragments were analyzed. A subset of 156 fragments exhibited marked methylation heterogeneity at NotI sites between clones. Their average intensity among clones correlated with their intensity in uncultured, whole-blood-derived T cells, indicating that the methylation heterogeneity observed in clones was largely attributable to methylation heterogeneity between the individual cells from which the clones were derived. We have cloned one fragment that exhibited variable NotI-site methylation between clones. This fragment contained a novel CpG island for a gene that we mapped to chromosome 4. The methylation status of the NotI site of this fragment correlated with expression of the corresponding gene. Our data suggest extensive diversity in vivo in the methylation and expression profiles of individual T cells at multiple unrelated loci across the genome.

Differential sensitivities of the two visual pathways of the chick to labelling by fluorescent retrograde tracers

This study investigates the neurone structure-specific differences of sensitivities of fluorescent tracers. The tracers were used for retrograde labelling of contralateral projections in the two visual pathways of the chick. Rhodamine B Isothiocyanate (RITC), Fluorogold (FG) and True blue (TB) were injected into either the visual Wulst (thalamofugal pathway) or the nucleus rotundus (Rt; tectofugal pathway) and the retrogradely labelled neurones in the nucleus geniculatus lateralis pars dorsalis (GLd) or the optic tectum, respectively, were counted. Differential retrograde labelling in the two pathways was observed. In the thalamofugal pathway, both the contralateral and ipsilateral GLd cells were labelled by all three tracers (RITC, FG and TB). However, in the tectofugal pathway, whereas RITC labelled both the ipsilateral and contralateral tectal neurones, FG or TB labelled effectively only the ipsilateral tectal neurones. It was clear that FG and TB were taken up by the nerve endings and transported part-way along the axon but failed to be transported to the cell bodies of the contralateral tectal neurones. In addition, red beads and green beads were also injected into Rt and the differential labelling was also observed. Red beads labelled both ipsilateral and contralateral tectal neurones but green beads labelled only the ipsilateral tectal neurones. Since the contralateral tectal projections consist of divergent axon collaterals, the present study suggests that various retrograde tracers are not transported in these axon collaterals to label cell bodies. The contralaterally projecting neurones in the thalamofugal pathway are not axon collaterals and they were labelled by all of the tracers used.

Genetic deletion of p21WAF1 enhances papilloma formation but not malignant conversion in experimental mouse skin carcinogenesis

Tumor suppression by p53 is believed to reside in its ability to regulate gene transcription, including up-regulation of p21WAF1. In p53(-/-) mice, chemical- or oncogene-induced skin tumors undergo accelerated malignant conversion. To determine the contribution of the p21WAF1 gene product to epidermal carcinogenesis, animals +/+, +/-, and -/- for a null mutation in the p21WAF1 gene were treated once with 25 nmol 7,12-dimethylbenz[a]anthracene, followed by 5 microg of TPA two times/week for 20 weeks. Papilloma frequency was higher in the p21WAF1-deficient mice. However, the frequency of malignant conversion was similar among all three genotypes. After TPA treatment, all genotypes developed epidermal hyperplasia, although the labeling index was lower in p21WAF1 (-/-) epidermis compared with p21WAF1 (+/+). Furthermore, the expression of differentiation markers was the same across genotypes in untreated or TPA-treated epidermis. Similar frequencies of malignant conversion were also observed in an in vitro assay. Thus, p21WAF1 suppresses early stages of papilloma formation but not malignant progression in mouse skin carcinogenesis, and decreased levels of p21WAF1 do not account for the enhanced malignant conversion of p53 null epidermal tumors.

[Detection of Epstein-Barr viral genome in tumor cells of Warthin's tumor of parotid gland]

OBJECTIVE

To evaluate the relations between Warthin's tumors of salivary gland and Epstein-Barr virus (EBV).

METHODS

75 cases of salivary gland Warthin's tumor and 20 cases of normal salivary gland tissue were examined for to detect EBV genoma by using the polymerase chain reaction (PCR) of DNA, 62 cases of single Warthin's tumor and 13 cases of multiple/bilateral Warthin's tumor's.

RESULTS

EBV DNA was detected in 13 cases of single Wathin's tumors, 9 cases of multiple/bilateral Warthin's tumor and 3 cases of normal salivary gland.

CONCLUSION

There was a close relationship between EBV and multiple/bilateral Warthin's tumors.

[HLA-DQA1 genes involved in the genetic susceptibility to duodenal ulcer in Wuhan Hans]

OBJECTIVE

To study the genetic susceptibility of HLA-DQA1 alleles to duodenal ulcer in Chinese Hans from Wuhan and its nearby regions.

METHODS

Seventy patients with duodenal ulcer and fifty healthy controls were examined for HLA-DQA1 genotypes. HLA-DQA1 typing was carried out by digesting the locus specific polymerase chain reaction amplified products with alleles specific restriction enzymes (PCR-RFLP), Apal I, Basj I, Hph I, Fok I, Mbo II and Mnl I.

RESULTS

The allele frequency of DQA1 0301 in patients with duodenal ulcer (64.3%) was significantly higher than that in healthy controls (36%). In contrast, the allele frequency of DQA1 0102 in patients with duodenal ulcer (8.6%) was significantly lower than that in healthy controls (26%).

CONCLUSION

These findings suggest that DQA1 0301 is a susceptible gene for duodenal ulcer in Wuhan Hans while DQA1 0102 is its resistant gene, and there are immunogenetic differences in HLA-DQA1 locus between duodenal ulcer patients and healthy controls.

Fibroblast growth factor receptors (FGFRs) and their roles in limb development

Fibroblast growth factor (FGF) receptors constitute a family of four membrane-spanning tyrosine kinases (FGFR1-4) which serve as high-affinity receptors for 17 growth factors (FGF1-17). To study functions of FGF/ FGFR signals in development, mice that carry mutations in each receptor have been created by gene targeting. Analysis of these mutant mice revealed essential functions of FGF receptors in multiple biological processes, including mesoderm induction and patterning, cell growth and migration, organ formation and bone growth. In this review we discuss recent work with FGF receptors to illustrate mechanisms, through which the FGF/FGFR signals specify vertebrate limb initiation, outgrowth and patterning.

Targeted disruption of SMAD3 results in impaired mucosal immunity and diminished T cell responsiveness to TGF-beta

SMAD3 is one of the intracellular mediators that transduces signals from transforming growth factor-beta (TGF-beta) and activin receptors. We show that SMAD3 mutant mice generated by gene targeting die between 1 and 8 months due to a primary defect in immune function. Symptomatic mice exhibit thymic involution, enlarged lymph nodes, and formation of bacterial abscesses adjacent to mucosal surfaces. Mutant T cells exhibit an activated phenotype in vivo, and are not inhibited by TGF-beta1 in vitro. Mutant neutrophils are also impaired in their chemotactic response toward TGF-beta. Chronic intestinal inflammation is infrequently associated with colonic adenocarcinoma in mice older than 6 months of age. These data suggest that SMAD3 has an important role in TGF-beta-mediated regulation of T cell activation and mucosal immunity, and that the loss of these functions is responsible for chronic infection and the lethality of Smad3-null mice.

Targeted disruption of SMAD3 results in impaired mucosal immunity and diminished T cell responsiveness to TGF-beta

SMAD3 is one of the intracellular mediators that transduces signals from transforming growth factor-beta (TGF-beta) and activin receptors. We show that SMAD3 mutant mice generated by gene targeting die between 1 and 8 months due to a primary defect in immune function. Symptomatic mice exhibit thymic involution, enlarged lymph nodes, and formation of bacterial abscesses adjacent to mucosal surfaces. Mutant T cells exhibit an activated phenotype in vivo, and are not inhibited by TGF-beta1 in vitro. Mutant neutrophils are also impaired in their chemotactic response toward TGF-beta. Chronic intestinal inflammation is infrequently associated with colonic adenocarcinoma in mice older than 6 months of age. These data suggest that SMAD3 has an important role in TGF-beta-mediated regulation of T cell activation and mucosal immunity, and that the loss of these functions is responsible for chronic infection and the lethality of Smad3-null mice.