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.

Genetic polymorphism of human O6-alkylguanine-DNA alkyltransferase: identification of a missense variation in the active site region

O6-Alkylguanine-DNA alkyltransferase (AGT, EC 2.1.1.63) is a principle DNA repair protein in repairing O6-alkylguanine in DNA, a major premutagenic lesion produced by environmental and therapeutic alkylating agents. AGT plays a critical role in protecting cells against mutation and cytotoxicity induced by these alkylating agents. The existence of a large interindividual variation in human AGT activity level has been observed and we hypothesize that genetic polymorphism of AGT could be an important determinant for this variation. The present study reports the identification of a novel missense polymorphism in the human AGT gene. The polymorphic alteration occurs at codon 143 in exon 5, converting isoleucine (ATC) to valine (GTC). Because Ile143 is adjacent to the alkyl acceptor Cys145 of the AGT active site and is conserved among mammalian AGTs, amino acid substitution at this position may affect the function of AGT. The codon 143 polymorphism appears to be linked to another new polymorphic alteration at codon 178, which converts lysine (AAG) to arginine (AGG). Because it has been reported that human AGT can be truncated at position 176 without loss of activity, the codon 178 polymorphism may not affect AGT activity. The codon 143/178 polymorphism was found in two of 90 (2%) esophageal cancer patients residing in a high incidence area of China, but was not detected in 60 normal individuals residing in the same area. Six of 28 (210%) non-cancer Caucasian individuals, however, were found to carry this polymorphic allele, suggesting a significant ethnic difference in distribution of this codon 143/178 polymorphism between Chinese and Caucasian individuals. In addition, we confirmed the existence of a codon 84 genetic polymorphism previously identified in a Japanese population, which converts leucine (CTT) to phenylalanine (TTT). The distribution of codon 84 polymorphism was 16%, 20% and 36%, respectively, in the Chinese esophageal cancer patients, Chinese and Caucasian non-cancer individuals. Coexistence of codons 84 and 143/178 polymorphic alterations was found in one Caucasian individual. In all the Chinese (n = 150) and Caucasian (n = 28) samples examined, we were unable to detect a previously reported codon 160 polymorphism (Gly to Arg) which occurred in 10-25% of the Japanese individuals and was shown to affect the reaction of AGT with the drug O6-benzylguanine. The functional significance of the codon 143/178 genetic polymorphism of human AGT and its role in determining an individual's susceptibility to environmental alkylating carcinogens and response to alkylating chemotherapeutic drugs both remain to be studied.

A genetic model of substrate deprivation therapy for a glycosphingolipid storage disorder

Inherited defects in the degradation of glycosphingolipids (GSLs) cause a group of severe diseases known as GSL storage disorders. There are currently no effective treatments for the majority of these disorders. We have explored a new treatment paradigm, substrate deprivation therapy, by constructing a genetic model in mice. Sandhoff's disease mice, which abnormally accumulate GSLs, were bred with mice that were blocked in their synthesis of GSLs. The mice with simultaneous defects in GSL synthesis and degradation no longer accumulated GSLs, had improved neurologic function, and had a much longer life span. However, these mice eventually developed a late-onset neurologic disease because of accumulation of another class of substrate, oligosaccharides. The results support the validity of the substrate deprivation therapy and also highlight some limitations.

Light experience and lateralization of the two visual pathways in the chick

Using retrograde labelling with the fluorescent tracer rhodamine B isocyanate (RITC), we have examined the organisation of the thalamofugal and tectofugal visual projections to the forebrain of the young chick. In addition, we have investigated the influence of light exposure prior to hatching on the development of the tectofugal visual projections. Our results for the thalamofugal projections confirm those found previously; viz., that there are more projections from the left side of the thalamus to the right hyperstriatum of the forebrain than from the right side of the thalamus to the left hyperstriatum in males and females. The organisation of the tectofugal visual projections to the rotundal nuclei was more symmetrical (males only examined) although there was a trend towards a greater number of projections from the left optic tectum to its ipsilateral nucleus rotundus than from the right optic tectum to its ipsilateral nucleus rotundus. There are numerous projections from the optic tecta to their contralateral rotundal nuclei but, in contrast to reports for the pigeon, no marked asymmetry was present in these. The ratio of contralateral to ipsilateral projections revealed significant asymmetry for projections from the ventral regions of the optic tecta and symmetry from the dorsal regions. Thus both visual pathways of the chick have asymmetrical organisation but the asymmetry is much greater in the thalamofugal pathway. The slight asymmetry in the tectofugal projections may be determined by exposing the embryo to light just before hatching, as known to be the case for thalamofugal projections.

Role of decay-accelerating factor in regulating complement activation on the erythrocyte surface as revealed by gene targeting

Decay-accelerating factor (DAF) is a glycosylphosphatidylinositol (GPI)-anchored membrane protein that inhibits both the classical and the alternative pathways of complement activation. DAF has been studied extensively in humans under two clinical settings: when absent from the erythrocytes of paroxysmal nocturnal hemoglobinuria (PNH) patients, who suffer from complement-mediated hemolytic anemia, and in transgenic pigs expressing human DAF, which have been developed to help overcome complement-mediated hyperacute rejection in xenotransplantation. Nevertheless, the exact role of DAF in regulating complement activation in vivo on the cell surface and the species specificity of this molecule remain to be fully characterized. To address these issues, we have used gene targeting to produce mice lacking GPI-anchored DAF. We found that erythrocytes from mice deficient in GPI-anchored DAF showed no increase in spontaneous complement activation in vivo but exhibited impaired regulation of zymosan-initiated bystander and antibody-triggered classical pathway complement activation in vitro, resulting in enhanced complement deposition. Despite a high level of C3 fixation, no homologous hemolysis occurred. It is noteworthy that GPI-linked DAF knockout erythrocytes, when tested with human and guinea pig sera, were more susceptible to heterologous complement lysis than were normal erythrocytes. These results suggest that DAF is capable of regulating homologous as well as heterologous complement activation via the alternative or the classical pathway. They also indicate that DAF deficiency alone is not sufficient to cause homologous hemolysis. In contrast, when the assembly of the membrane-attack complex is not properly regulated, as in the case of heterologous complement activation or in PNH patients, impaired erythrocyte DAF activity and enhanced C3 deposition could lead to increased hemolytic reaction.

Differential regulation of p21 by p53 and Rb in cellular response to oxidative stress

Oxidative stress to mammalian cells causes cellular damage and triggers inducible cellular responses leading to cell death by apoptosis. In this paper, we report that p53 was required for programmed cell death induced by oxidative stress in both mouse and human cells and that p53 transactivation was involved in induction of oxidative cell death. Furthermore, we show that p21 was highly responsive to oxidative stress in a p53-dependent manner and that ectopic expression of p21 could increase cellular susceptibility to oxidative stress in the absence of p53. However, p21 was not required for p53-directed oxidative cell death because mouse embryo fibroblasts MEFs lacking p21(p21-/- MEFs) were still susceptible to oxidative cell death. Interestingly, bax, a cell-death mediator regulated by p53, was overexpressed in p21-/- MEFs that underwent cell death by oxidative stress, suggesting a compensation for loss of p21 that may be responsible for the existence of cell-death responses in p21-knockout mouse fibroblasts. Finally, we provide evidence that the retinoblastoma gene product (Rb) is a negative regulator of p21 and a repressor of the cellular apoptotic process. Because p21 is regulated by p53 positively and by Rb negatively, p21 may be a link between p53 and Rb in determining cell fate after oxidative damage.

[MMC conditioning regimen (Melphalan, MeCCNU and cyclophosphamide) followed by allogeneic peripheral blood stem cells transplantation for chronic myeloid leukemia]

This paper reports 3 cases of allogeneic peripheral blood stem cell transplantation (Allo-PBSCT) for the patients with chronic myeloid leukemia (CML). The patients received MMC preparative regimen with high dose chemotherapy (Melphalan 170 mg/m2, p.o. on Day-5, MeCCNU 400 mg/m2, p.o. on Day-4, and Cyclophosphomide 60 mg/kg/day, i.v. on Days-3 and -2). The HLA-identical sibling donors received filgrastim (rhG-CSF) for mobilization at a dose of 300 micrograms/day for 6 days. Leukaphereses were done at the 6th day of mobilization. A median of 8000 ml (2 times total blood volume) of blood was processed the collecting: 2.5-4.5 x 10(8)/kg MNC, 12.8-20.0 x 10(6)/kg CD34+ cells (including 4.8-7.5 x 10(6)/kg CD34+CD33-, 8.0-13.0 x 10(6)/kg CD34+CD33+), and 3.5-4.3 x 10(5)/kg CFU-GM. Cyclosporin A and methotrexate were used for GVHD prophylaxis. Hematopoitic function recovered as for 14-20 days to > 0.5 x 10(9)/L of neutrophil count, and for 16-34 days to > 20 x 10(9)/L of platelet count. At day + 100, chromosome analysis of bone marrow cells showed that complete chimera without ph1 positive chromosome in Cases 1 and 3, and a partial chimera with 73% donor karyotype in Case 2. All patients now are in disease free survival. No episode of acute graft versus host disease (GVHD) developed. It was concluded that HLA matched sibling allogeneic PBSCT result in rapid hematopoitic reconstitution and the MMC conditioning regimen is effective both in leukemic cells eradication and in immunosuppression for stem cells engraftment, and the drug related toxicity could be tolerated by patients.

The Th2 cytokine IL-4 is not required for the progression of antibody-dependent autoimmune myasthenia gravis

Experimental autoimmune myasthenia gravis (EAMG), a disorder of the neuromuscular junction, is mediated by autoantibodies against muscle nicotinic acetylcholine receptor (AChR). The roles of IFN-gamma (Th1) and IL-4 (Th2) cytokines in the initiation and progression of this disease are not fully understood. Recently, we have demonstrated that IFN-gamma is necessary for the initiation of tAChR-induced EAMG in mice. However, the role of IL-4 in the progression of clinical EAMG remained undetermined. In this study we have addressed the contribution of IL-4 in the disease progression in IL-4(-/-) C57BL/6j mice whose IL-4 gene has been disrupted. Following immunization with Torpedo (t) AChR, the IL-4(-/-) mice readily developed signs of muscle weakness and succumbed to clinical EAMG with kinetics similar to the susceptibility of IL-4(+/+) mice. The tAChR-primed lymph node cells from IL-4(-/-) mice vigorously proliferated to tAChR and to its dominant alpha146-162 sequence associated with disease pathogenesis. However, these T cells secreted higher levels of IFN-gamma and IL-2, suggesting the development of a Th1 default pathway in these mice. Nevertheless, the IL-4 mutation had no effect on the recruitment of CD4+ Vbeta6+ T cells specific to the dominant tAChR alpha146-162 sequence in vivo. Immune sera from IL-4(-/-) mice showed a dramatic increase in mouse AChR-specific IgG2a levels followed by a concomitant decrease in IgG1 levels, but these mice did not exhibit an accelerated disease. In conclusion, we have demonstrated for the first time that IL-4 is not required either for the generation of a pathogenic anti-AChR humoral immune response or for progression of clinical EAMG in mice.

Role of the ras-MAPK signaling pathway in the DNA methyltransferase response to DNA hypomethylation

Our group reported that inhibiting DNA methylation in human T cells increases DNA methyltransferase expression and activity, and suggested that this may represent a response to DNA hypomethylation. The increase correlates with increases in Ha-ras and c-jun, suggesting that increased signaling through the ras-MAPK pathway, due to overexpression of some elements, may be responsible. However, whether human DNA MTase is regulated by the ras-MAPK pathway, and whether overexpression of elements in this pathway will increase DNA MTase, is unknown. We report that treating cells with a DNA methylation inhibitor increases transcription regulated by a putative DNA MTase promoter, and that this increase requires AP-1 sites. Additional studies demonstrate that overexpression of an unmutated Ha-ras causes an increase in DNA MTase, and that human T cell DNA MTase can be decreased by inhibiting signaling through the ras-MAPK pathway. Together, these studies suggest that human T cell DNA MTase is regulated through the ras-MAPK pathway, and that overexpression of Ha-ras is sufficient to increase DNA MTase expression. These results thus provide a mechanism for the increase in DNA MTase observed after inducing DNA hypomethylation, a response which may have relevance to some disease states.

Expression of estrogen sulfotransferase in MCF-7 cells by cDNA transfection suppresses the estrogen response: potential role of the enzyme in regulating estrogen-dependent growth of breast epithelial cells

Estrogen sulfotransferase (EST) is a cytosolic enzyme that catalyzes the sulfonation of estrogens at the 3-hydroxyl position by use of 3'-phosphoadenosine-5'-phosphosulfate as an activated sulfate donor. Although largely known and studied as a phase II metabolic enzyme with prominent expression in the liver, the high substrate specificity of EST (with a high Vmax/Km value for estrogen) suggests that expression of the enzyme in extrahepatic, estrogen target tissues, such as the breast epithelium, may constitute an effective mechanism for local estrogen regulation as well. In this study, we have evaluated the physiological significance of EST expression by cDNA transfection studies with use of the estrogen-dependent MCF-7 breast cancer cell line as a model system. We show that expression of EST in MCF-7 cells effectively reduces the cells' response to physiological concentrations of estradiol (10 nM) by up to 70% as determined in an estrogen-responsive reporter gene assay. In addition, we demonstrate that expression of EST similarly inhibits estrogen-stimulated DNA synthesis and cell proliferation by 21% and 46%, respectively. (The thymidine incorporation rate was measured 3 days after and the cell numbers were counted 8 days after transfection.) These results provide direct evidence for the functional significance of in situ EST expression in the breast epithelium and suggest that abnormal regulation of the enzyme may have pathological implications in the development and maintenance of hormone-dependent breast carcinomas.

Fibroblast growth factor receptor 4, implicated in progression of islet cell carcinogenesis by its expression profile, does not contribute functionally

Fibroblast growth factor receptor 4 (FGFR4) gene expression is activated in late-stage beta-cell tumors that develop in transgenic mice harboring SV40 large T antigen (Tag) gene that is under the transcriptional control of the insulin promoter (RIP-Tag). The FGFR4 gene was active in cell lines derived from tumors but not in cells derived from hyperplastic islets. We used both gain-of-function and loss-of-function FGFR4 transgenic mice to determine whether FGFR4 modulates islet cell tumorigenesis and, if so, to identify the nature of the effect. Both types of FGFR4 transgenic mice were viable and fertile and developed islet tumors when crossed with RIP-Tag mice. Remarkably, there was no significant perturbation in the tumorigenesis pathway resulting from either chronic up-regulation or absence of FGFR4 gene expression. Analyses included the incidence and size of tumors, rate of cell proliferation, cell density, and life span. We conclude that FGFR4 gene activation is a marker of but is not causal for beta-cell transformation.

The effect of B cell deficiency on the immune response to acetylcholine receptor and the development of experimental autoimmune myasthenia gravis

To study the involvement of B cells in the immune response to acetylcholine receptor (AChR), B-cell-deficient (mu mutant) and control wild-type C57BL/6 mice were immunized with AChR and assessed for clinical and immunopathological manifestations of experimental autoimmune myasthenia gravis (EAMG). The mu mutant mice failed to generate anti-AChR antibodies and were completely resistant to the induction of EAMG. However, mu mutant mice developed clinical EAMG when antibodies to the AChR main immunogenic region were passively transferred. Further, the in vivo expansion of lymph node cells after AChR immunization was greatly impaired in mu mutant mice. The mu mutant mice gave an effective in vitro T cell immune response to the immunodominant pathogenic AChR alpha chain peptide 146-162 (alpha 146-162) and to the whole AChR protein when tested on day 90 after immunization with AChR, whereas the response to both AChR and its alpha 146-162 peptide was reduced when tested on day 7 after immunization. The in vitro production of IFN-gamma and IL-2 by AChR-specific and alpha 146-162 peptide-specific lymphocytes was lower in mu mutant mice. The AChR immune mu mutant T cells proliferated and produced IFN-gamma when AChR or alpha 146-162 peptide was presented by wild-type irradiated AChR-primed antigen-presenting cells (APCs). This indicates that B cells are important in the processing and presentation of AChR dominant peptide in vitro during the initial immune response to AChR. However, APCs of non-B-cell lineage are sufficient to process AChR and prime the T cells to AChR dominant T cell epitope peptides.

Bilaterally projecting neurons in the two visual pathways of chicks

By means of a double-labeling technique, we have investigated the organization of the bilateral thalamo-Wulst and tecto-rotundal projections in 2-day old chicks. After injecting fluorogold (FG) into one side of the visual Wulst and rhodamine B isothiocyanate (RITC) into the other side of the visual Wulst, the labeled neurons in the nucleus geniculatus lateralis pars dorsalis (GLd) were examined. Although the distribution areas of ipsilaterally and contralaterally labeled neurons overlap partly, very few double-labeled neurons were found (only 0.01% double-labeled neurons). This suggests that the ipsilateral and contralateral projections to the Wulst come from different neuronal populations of the thalamus. The FG and RITC were also injected into the rotundal nuclei (Rt) on each side of the thalamus and the labeled neurons in the optic tectum (TeO) were examined. In the TeO, the distribution areas of the neurons labeled ipsilaterally and contralaterally to Rt overlap completely and we found that up to 45% of the tectal cells were double-labeled by both FG and RITC. Therefore, many tectal neurons have axon collaterals so that they project to the Rt on both sides of the thalamus and must send information simultaneously to both sides of the brain. The differences in the structural organization of the two visual pathways are discussed with reference to the transmission of information to higher centers on both sides of the brain.

Organisation of the tectorotundal and SP/IPS-rotundal projections in the chick

The organisation of the neural projections from the optic tectum and pretectal nuclei complex, n. subpretectalis / n. interstitio-pretecto-subpretectalis (SP/IPS), to the nucleus rotundus (Rt) in chicks was studied by using retrograde tracing techniques. After the injection of fluorescent retrograde tracers, rhodamine-conjugated latex microspheres, fluorescein-conjugated latex microspheres, True Blue, Fluoro-Gold, or rhodamine B isothiocyanate, into different regions of Rt and its middorsal extension, the nucleus triangularis (T), the distribution of retrogradely labelled neuronal cell bodies in the tectum and pretectal nuclei was assessed. Both the ipsilateral and contralateral tectorotundal projections were found to be organised topographically in as much as different sublaminas of the stratum griseum centrale (SGC) project in an orderly manner to Rt and T. The deepest stratum of SGC overlapping into the stratum album centrale projects to T. Deep SGC projects to the dorsal Rt and superficial SGC to the ventral Rt. A band running through the centre of Rt receives input from the central sublamina of SGC, and the caudal central Rt receives input from a deeper sublamina than does the rostral central Rt. The SP/IPS projects to the ipsilateral Rt only and the projection order is dorsal SP to dorsal Rt, ventral SP to ventral Rt and middle SP to the central band of Rt. The neurones in IPS and the nucleus of the tractus tectothalamicus project to T. Thus, Rt and T receive topographically both tecto- (excitatory) and SP/IPS- (inhibitory) projections. The possible functional implications for parallel information processing in these projections are discussed.

Involvement of p21 and p27 in the regulation of CDK activity and cell cycle progression in the regenerating liver

In tissue culture systems, p21 and p27 inhibit cyclin-dependent kinase (CDK) activity and cell cycle progression in response to numerous stimuli, but little is known about their involvement in cell growth in vivo. We examined the modulation of CDK activity by these proteins after 70% partial hepatectomy (PH), an in vivo model of synchronous hepatocyte cell cycle progression. After PH in BALB/c mice, p21 was induced during the prereplicative (G1) phase and was maximally expressed after peak hepatocyte DNA synthesis. p27 was present in quiescent liver and was minimally induced after PH. p21 and p27 immunoprecipitated with CDK2, CDK4, and cyclin D1 in the regenerating liver. The activity of CDK2-, CDK4- and cyclin D1-associated kinases was upregulated after PH, and maximal activity of these enzyme complexes corresponded to peak DNA synthesis. Immunodepletion experiments suggested that p27 plays a role in downregulating CDK2 activity before and after peak DNA synthesis. Compared to cogenic wild-type mice, p21-/- mice demonstrated evidence of markedly accelerated hepatocyte progression through G1 phase after PH: DNA synthesis, upregulation of cyclin A and PCNA, induction of cyclin D1- and CDK2-associated kinase activity, and appearance of a phosphorylated retinoblastoma protein (Rb) species occurred earlier in the p21-/- mice. These results suggest that p21 and p27 modulate CDK activity in the regenerating liver, and that p21 regulates the rate of progression through G1 phase of the cell cycle in vivo.

The tumor suppressor SMAD4/DPC4 is essential for epiblast proliferation and mesoderm induction in mice

Members of the transforming growth factor (TGF)-beta superfamily have been shown to play a variety of important roles in embryogenesis, including dorsal and ventral mesoderm induction. The tumor suppressor SMAD4, also known as DPC4, is believed to be an essential factor that mediates TGF-beta signals. To explore functions of SMAD4 in development, we have mutated it by truncating its functional C-domain. We show that Smad4 is expressed ubiquitously during murine embryogenesis. Mice heterozygous for the Smad4(ex8/+) mutation are developmentally normal, whereas homozygotes die between embryonic day 6.5 (E6.5) and 8.5. All Smad4(ex8/ex8) mutants are developmentally delayed at E6 and show little or no elongation in the extraembryonic portion of late egg cylinder stage embryos. Consistent with this, cultured Smad4(ex8/ex8) blastocyst outgrowths suffer cellular proliferation defects and fail to undergo endoderm differentiation. Although a portion of mutant embryos at E8.5 show an increase in the embryonic ectoderm and endoderm, morphological and molecular analyses indicate that they do not form mesoderm. Altogether, these data demonstrate that SMAD4-mediated signals are required for epiblast proliferation, egg cylinder formation, and mesoderm induction.

Fibroblast growth factor receptor 2 (FGFR2)-mediated reciprocal regulation loop between FGF8 and FGF10 is essential for limb induction

FGFR2 is a membrane-spanning tyrosine kinase that serves as a high affinity receptor for several members of the fibroblast growth factor (FGF) family. To explore functions of FGF/FGFR2 signals in development, we have mutated FGFR2 by deleting the entire immunoglobin-like domain III of the receptor. We showed that murine FGFR2 is essential for chorioallantoic fusion and placenta trophoblast cell proliferation. Fgfr2(DeltaIgIII/DeltaIgIII) embryos displayed two distinct defects that resulted in failures in formation of a functional placenta. About one third of the mutants failed to form the chorioallantoic fusion junction and the remaining mutants did not have the labyrinthine portion of the placenta. Consequently, all mutants died at 10–11 days of gestation. Interestingly, Fgfr2(DeltaIgIII/DeltaIgIII) embryos do not form limb buds. Consistent with this defect, the expression of Fgf8, an apical ectodermal factor, is absent in the mutant presumptive limb ectoderm, and the expression of Fgf10, a mesenchymally expressed limb bud initiator, is down regulated in the underlying mesoderm. These findings provide direct genetic evidence that FGF/FGFR2 signals are absolutely required for vertebrate limb induction and that an FGFR2 signal is essential for the reciprocal regulation loop between FGF8 and FGF10 during limb induction.

[Characterization of slowly-growing mycobacteria species by capillary gas chromatography]

A method for the characterization of mycobacteria species by capillary gas chromatography is described. After strains of mycobacteria being hydrolyzed, saponified in an acidic solution, various methyl esters resulted from mycobacteria were studied on an OV-101 column at optimum chromatographic conditions. The constituents of 9 slowly-growing mycobacteria species were analyzed and the results showed that there were obvious differences between different mycobacteria species, but same characteristics were observed between strains of the same species. The 9 species can be identified by the ratio of peak height of C18:1, C18:0 and TBSA. They are C18:1>TBSA>C18:0 for M. tuberculosis, C18:0>C18:1>TBSA for M. triviale, TBSA>C18:1>C18:0 for M. intracellulare, TBSA>C18:0>C18:1 for M. avium and C18:1>C18:0>TBSA for M. bovis, M. kansasii, M. gordonae, M. nonchromogenicum and M. terrae respectively. The 5 latter species can be distinguished by the presence of characteristic peaks of iC16:1 and C19:0. 75 strains of clinical isolated mycobacteria were analysed at the same chromatographic conditions. The results showed that they belonged to 9 different species. The accuracy of the proposed method was examined according to biological analysis.

[Determination of total organic acids in wine by interfacial derivatization gas chromatographic method]

This paper presents a new method for analysis of total organic acids in wine as follows: organic acids in wine were separated and enriched with strong anion-exchange resin and were esterified directly on the resin with BF3-diethylether and alcohol for 60 min under the temperature of 90 degrees C. The ethyl esters of organic acids were extracted with dichloromethane and determined by HP 5890A GC-5970B MSD equipped with fused-silica capillary column, 12.5 m x 0. 2mm i.d.. The column temperature was programmed from 30 degrees C to 60 degrees C at 2 degrees C/min, 60 degrees C to 180 degrees C at 5 degrees C/min, 180 degrees C to 230 degrees C at 10 degrees C/min. Twenty one peaks of ethyl esters of organic acids in wine were identified with gas chromatography/mass spectrometry and quantitated with internal standard and working curve. The results of analysis are satisfactory. This paper has provided a useful method of determination of low content of organic acids in complex aqueous samples.

Tolerance to a dominant T cell epitope in the acetylcholine receptor molecule induces epitope spread and suppresses murine myasthenia gravis

Myasthenia gravis (MG) is a T cell-dependent, Ab-mediated autoimmune disease. T cells reactive to a dominant peptide alpha 146-162 of acetylcholine receptor (AChR) alpha subunit participate in murine MG pathogenesis. To suppress the autoimmune response to AChR, a high dose of alpha146-162 peptide in IFA was administered parenterally as a tolerogen, after the development of a primary T cell immune response to AChR. This form of AChR T cell peptide tolerance suppressed the in vitro T cell proliferative response to AChR and its dominant alpha146-162 and subdominant alpha182-198 peptides through epitope spread. Administration of alpha146-162 peptide in IFA after the primary immune response to AChR also significantly suppressed the serum anti-AChR Ab of the IgG2b isotype and clinical incidence of MG in C57BL/6 mice. Furthermore, the production of IFN-gamma, IL-2, and IL-10 cytokines by AChR, alpha146-162, and alpha182-198 peptide-reactive cells was suppressed by alpha146-162 peptide tolerance, and the epitope spread observed could be attributed to the reduction in the above cytokine production. Therefore, AChR T cell-dominant peptide tolerance could be adapted in the Ag-specific therapy of MG.

Tolerance to a dominant T cell epitope in the acetylcholine receptor molecule induces epitope spread and suppresses murine myasthenia gravis

Myasthenia gravis (MG) is a T cell-dependent, Ab-mediated autoimmune disease. T cells reactive to a dominant peptide alpha 146-162 of acetylcholine receptor (AChR) alpha subunit participate in murine MG pathogenesis. To suppress the autoimmune response to AChR, a high dose of alpha146-162 peptide in IFA was administered parenterally as a tolerogen, after the development of a primary T cell immune response to AChR. This form of AChR T cell peptide tolerance suppressed the in vitro T cell proliferative response to AChR and its dominant alpha146-162 and subdominant alpha182-198 peptides through epitope spread. Administration of alpha146-162 peptide in IFA after the primary immune response to AChR also significantly suppressed the serum anti-AChR Ab of the IgG2b isotype and clinical incidence of MG in C57BL/6 mice. Furthermore, the production of IFN-gamma, IL-2, and IL-10 cytokines by AChR, alpha146-162, and alpha182-198 peptide-reactive cells was suppressed by alpha146-162 peptide tolerance, and the epitope spread observed could be attributed to the reduction in the above cytokine production. Therefore, AChR T cell-dominant peptide tolerance could be adapted in the Ag-specific therapy of MG.

Differential contributions of the two visual pathways to functional lateralization in chicks

The contribution of the two visual pathways to lateralization of visual behaviour in chicks was assessed using unilateral injections of 0.5 microliters of 100 mM monosodium glutamate into localized regions of the forebrain. Chicks treated with glutamate in the left visual hyperstriatum made more errors in a visual discrimination task (pebble-floor test) than did chicks treated in the right visual hyperstriatum. Glutamate injection into the left visual hyperstriatum also elevated attack and copulation scores, but this did not occur following injection of the right visual hyperstriatum. The performance of chicks treated in the right visual hyperstriatum did not differ from that of sham-operated controls. Thus, only the left visual hyperstriatum is involved in the control of these three visually guided behaviours. By contrast, glutamate injections of the left ectostriatum affected only the attack behavior and not performance in the pebble-floor test or copulation responses. Glutamate treatment of the right ectostriatum had no affect on any of the behaviours tested and this was also the case for glutamate treatment of both the left and right neostriata. Although injecting glutamate in a larger volume that allows glutamate to spread over a wide area of the left hemisphere is known to retard auditory habituation, localized injection of glutamate in the areas chosen for this study had no effect on auditory habituation. The results suggest that the tectofugal and thalamofugal pathways have different roles in the lateralization of visual functions. The forebrain region which receives input from the thalamofugal visual system has a lateralized role in categorising pebbles as different from food grains, and also a role in controlling attack and copulation responses. The forebrain region which receives input from the tectofugal visual system is involved in the control of attack responses only.

[Maturation of bone marrow megakaryocyte in patients with chronic idiopathic thrombocytopenic purpura]

Colony formation units of megakaryocyte of twenty four patients with idopathic thromboeytopentic purpura (CITP) were observed by plasma clot cultures in vitro. We observed the maturation degree of megakarycyte and the effect of recombinant interferon alpha-2a (rIFN-alpha-2a) on megakaryocyte colony growth and maturation. The results showed that the number of CFU-MK of the patients with CITP was greater than that of the control group, while the patients with normal number of megakaryocytes on bone marrow smears had less BFU-MK and total clonies than the controls had. Through image analysis, we found that the black level of the positive cells of GP II a and GMP-140, the diameter and the area of megakaryocyte of patients with CITP were lower or smaller than those of the control group. These evidenced the block of megakaryocytopoiesis and megakarycyte maturation. The growth of MK colonies of marrow of patients with CITP was inhibited by r-IFN-alpha-2a.

Loss of p21CIP1/WAF1 does not recapitulate accelerated malignant conversion caused by p53 loss in experimental skin carcinogenesis

The p21(CIP1/WAF1) protein is considered a downstream effector of tumor suppression by p53. We have previously demonstrated that p53 null keratinocytes have lower basal p21(CIP1/WAF1) mRNA levels and that tumors derived from these cells following transduction with the v-ras(Ha) oncogene grow faster than wildtype keratinocytes and rapidly progress to undifferentiated carcinomas (Cancer Res 54: 5584-5592, 1994). In this study, primary keratinocytes differing in p21(CIP1/WAF1) gene dose were transduced with v-ras(Ha) encoding retrovirus and grafted to nude mouse hosts to test whether the p53 null phenotype is mediated through p21(CIP1/WAF1). Resulting tumors from all genotypes were well differentiated papillomas; focal carcinomas were observed in 43, 30 and 44% of papillomas derived from +/+, +/- and -/- keratinocytes, respectively. p21(CIP1/WAF1) deficient keratinocytes expressing v-ras(Ha) do not display the degree of increased growth observed in p53 deficient tumors in vivo or the decreased responsiveness to negative growth regulation by Ca2+ in vitro. These results suggest that p21(CIP1/WAF1) does not regulate the differentiated phenotype or malignant progression of v-ras(Ha) initiated keratinocytes and that additional functions of the p53 protein other than transcriptional regulation of the p21(CIP1/WAF1) gene are required for p53 mediated tumor suppression.

Interferon gamma (IFN-gamma) is necessary for the genesis of acetylcholine receptor-induced clinical experimental autoimmune myasthenia gravis in mice

Experimental autoimmune myasthenia gravis (EAMG) is an animal model of human myasthenia gravis (MG). In mice, EAMG is induced by immunization with Torpedo californica acetylcholine receptor (AChR) in complete Freund's adjuvant (CFA). However, the role of cytokines in the pathogenesis of EAMG is not clear. Because EAMG is an antibody-mediated disease, it is of the prevailing notion that Th2 but not Th1 cytokines play a role in the pathogenesis of this disease. To test the hypothesis that the Th1 cytokine, interferon (IFN)-gamma, plays a role in the development of EAMG, we immunized IFN-gamma knockout (IFN-gko) (-/-) mice and wild-type (WT) (+/+) mice of H-2(b) haplotype with AChR in CFA. We observed that AChR-primed lymph node cells from IFN-gko mice proliferated normally to AChR and to its dominant pathogenic alpha146-162 sequence when compared with these cells from the WT mice. However, the IFN-gko mice had no signs of muscle weakness and remained resistant to clinical EAMG at a time when the WT mice exhibited severe muscle weakness and some died. The resistance of IFN-gko mice was associated with greatly reduced levels of circulating anti-AChR antibody levels compared with those in the WT mice. Comparatively, immune sera from IFN-gko mice showed a dramatic reduction in mouse AChR-specific IgG1 and IgG2a antibodies. However, keyhole limpet hemocyanin (KLH)-priming of IFN-gko mice readily elicited both T cell and antibody responses, suggesting that IFN-gamma regulates the humoral immune response distinctly to self (AChR) versus foreign (KLH) antigens. We conclude that IFN-gamma is required for the generation of a pathogenic anti-AChR humoral immune response and for conferring susceptibility of mice to clinical EAMG.

Effect of mitogenic stimulation and DNA methylation on human T cell DNA methyltransferase expression and activity

DNA methylation, a mechanism modifying gene expression, is mediated in part by the enzyme DNA methyltransferase. Reduced levels of T cell DNA methyltransferase have been observed in lupus-like diseases, and increased levels have been reported in malignancies. Little is known concerning the regulation of human DNA methyltransferase. In this report we demonstrate that mitogenic T cell stimulation causes an increase in DNA methyltransferase mRNA and enzyme activity. We also show that pharmacologic inhibition of T cell DNA methylation causes an increase in the rate of DNA methyltransferase mRNA transcription and a corresponding increase in mRNA levels and enzyme activity. This suggests that DNA methyltransferase is itself regulated in part by DNA methylation status, possibly representing a feedback mechanism. DNA methylation inhibition also resulted in an increase in Ha-ras and c-jun mRNA levels, overexpression of which increases DNA methyltransferase in murine systems. These results thus identify two mechanisms regulating levels of human T cell DNA methyltransferase and raise the possibility that abnormalities in either could contribute to disorders associated with altered DNA methylation.

Effect of mitogenic stimulation and DNA methylation on human T cell DNA methyltransferase expression and activity

DNA methylation, a mechanism modifying gene expression, is mediated in part by the enzyme DNA methyltransferase. Reduced levels of T cell DNA methyltransferase have been observed in lupus-like diseases, and increased levels have been reported in malignancies. Little is known concerning the regulation of human DNA methyltransferase. In this report we demonstrate that mitogenic T cell stimulation causes an increase in DNA methyltransferase mRNA and enzyme activity. We also show that pharmacologic inhibition of T cell DNA methylation causes an increase in the rate of DNA methyltransferase mRNA transcription and a corresponding increase in mRNA levels and enzyme activity. This suggests that DNA methyltransferase is itself regulated in part by DNA methylation status, possibly representing a feedback mechanism. DNA methylation inhibition also resulted in an increase in Ha-ras and c-jun mRNA levels, overexpression of which increases DNA methyltransferase in murine systems. These results thus identify two mechanisms regulating levels of human T cell DNA methyltransferase and raise the possibility that abnormalities in either could contribute to disorders associated with altered DNA methylation.

Experimental autoimmune myasthenia gravis in B10.BV8S2 transgenic mice: preferential usage of TCRAV1 gene by lymphocytes responding to acetylcholine receptor

Multiple TCRBV genes have been implicated in experimental autoimmune myasthenia gravis (EAMG) pathogenesis in susceptible H-2(b) strains of mice. We studied the contribution of specific TCRBV and AV genes in EAMG pathogenesis using B10.BV8S2 transgenic mice (H-2[b]). The TCR transgenic mice predominantly have TCRBV8S2 transgene, but can use any of the endogenous AV gene repertoire. The transgenic mice were immunized with acetylcholine receptor (AChR) in CFA and evaluated for EAMG pathogenesis. Although the lymphocyte responses to AChR in B10.BV8S2 transgenic and nontransgenic TCR wild-type mice were equivalent, a marked reduction in lymphocyte response to the dominant AChR alpha chain peptide 146-162 was observed in the TCR transgenic mice. After boosting with AChR in CFA, anti-AChR Abs were detected in the serum, and 14 of 42 (33%) of the TCR transgenic mice developed clinical EAMG. Furthermore, EAMG in TCR transgenic mice was prevented by treatment with mAb to TCRBV8, which depleted BV8-expressing T cells. Cloning and sequencing of TCRAV genes from AChR-reactive T cells from B10.BV8S2 transgenic mice revealed a pattern of restricted TCRAV gene usage. The majority (60%) of the clones sequenced showed a sequence identical with that of the TCRAV1S8 gene. In the normal spleen cells of TCR transgenic mice, AV gene usage was more random. Thus, despite the presence of a complete endogenous TCRAV repertoire in B10.BV8S2 transgenic mice, T cells responding to AChR preferentially used a single endogenous TCRAV gene, thus implicating the involvement of the TCRAV1S8 gene in EAMG pathogenesis.

Experimental autoimmune myasthenia gravis in B10.BV8S2 transgenic mice: preferential usage of TCRAV1 gene by lymphocytes responding to acetylcholine receptor

Multiple TCRBV genes have been implicated in experimental autoimmune myasthenia gravis (EAMG) pathogenesis in susceptible H-2(b) strains of mice. We studied the contribution of specific TCRBV and AV genes in EAMG pathogenesis using B10.BV8S2 transgenic mice (H-2[b]). The TCR transgenic mice predominantly have TCRBV8S2 transgene, but can use any of the endogenous AV gene repertoire. The transgenic mice were immunized with acetylcholine receptor (AChR) in CFA and evaluated for EAMG pathogenesis. Although the lymphocyte responses to AChR in B10.BV8S2 transgenic and nontransgenic TCR wild-type mice were equivalent, a marked reduction in lymphocyte response to the dominant AChR alpha chain peptide 146-162 was observed in the TCR transgenic mice. After boosting with AChR in CFA, anti-AChR Abs were detected in the serum, and 14 of 42 (33%) of the TCR transgenic mice developed clinical EAMG. Furthermore, EAMG in TCR transgenic mice was prevented by treatment with mAb to TCRBV8, which depleted BV8-expressing T cells. Cloning and sequencing of TCRAV genes from AChR-reactive T cells from B10.BV8S2 transgenic mice revealed a pattern of restricted TCRAV gene usage. The majority (60%) of the clones sequenced showed a sequence identical with that of the TCRAV1S8 gene. In the normal spleen cells of TCR transgenic mice, AV gene usage was more random. Thus, despite the presence of a complete endogenous TCRAV repertoire in B10.BV8S2 transgenic mice, T cells responding to AChR preferentially used a single endogenous TCRAV gene, thus implicating the involvement of the TCRAV1S8 gene in EAMG pathogenesis.

Fibroblast growth factor receptor-1 (FGFR-1) is essential for normal neural tube and limb development

Fibroblast growth factor receptor-1 (FGFR-1) is a membrane-spanning tyrosine kinase that serves as a high-affinity receptor for fibroblast growth factors. It has recently been shown that FGFR-1 mutant embryos die during gastrulation displaying severe growth retardation and defective mesodermal structures. This early lethality has obscured functions of FGFR-1 that might occur later in development. To circumvent these embryonic defects, we generated chimeras by injecting FGFR-1-deficient (R1-/-) ES cells into wild-type blastocysts. We found that the fgfr-1 gene plays an important role after gastrulation and that it acts in a cell-autonomous fashion. Embryos with a high contribution of R1-/- cells replicate the FGFR-1 null phenotype and die during gastrulation. In contrast, the majority of embryos with a low contribution of R1-/- cells complete gastrulation and display malformations of posterior structures at later stages of embryogenesis. These abnormalities include truncation of embryonic structures, limb bud malformation, partial duplication of the neural tube, tail distortion, and spina bifida caused by the amplification of neural tissue in the posterior portion of the spinal cord. Thus, FGFR-1 plays a role in neurulation, suggesting that there may be a connection between FGFR-1-mediated signal pathways and neural tube defects, the most common malformations in the human central nervous system.

[The impact of different incisions on visual acuity and corneal refractivity in cataract surgery]

OBJECTIVE

To research the impact of different incisions of cataract surgery on post-operative visual acuity and corneal refractivity.

METHODS

The visual acuity and corneal refractivity in 243 eyes having undergone extracapsular cataract extraction and phacoemulsification with 5 mm tunnel incision or 7 mm frown-shaped incision were examined and compared at three post-operative periods.

RESULTS

The mean increase in corneal refractivity in phacoemulsification group was significantly less (P < 0.05) and the corrected visual acuity was much better (P < 0.05) than that in conventional extracapsular cataract extraction (ECCE) group at post-operative 1/2 month, 3 months and 6 months (P < 0.05). In the phacoemuisification group, the increase of the post-operative refractivity in 7 mm frown-shaped incision group was less than that in 5 mm tunnel incision group at 1/2 month and 3 months (P < 0.05).

CONCLUSION

7 mm frown-shaped incision of phacoemulsification is the most effective method to control the post-operative corneal astigmatism in cataract surgery.

The Saccharomyces cerevisiae kinesin-related motor Kar3p acts at preanaphase spindle poles to limit the number and length of cytoplasmic microtubules

The Saccharomyces cerevisiae kinesin-related motor Kar3p, though known to be required for karyogamy, plays a poorly defined, nonessential role during vegetative growth. We have found evidence suggesting that Kar3p functions to limit the number and length of cytoplasmic microtubules in a cell cycle-specific manner. Deletion of KAR3 leads to a dramatic increase in cytoplasmic microtubules, a phenotype which is most pronounced from START through the onset of anaphase but less so during late anaphase in synchronized cultures. We have immunolocalized HA-tagged Kar3p to the spindle pole body region, and fittingly, Kar3p was not detected by late anaphase. A microtubule depolymerizing activity may be the major vegetative role for Kar3p. Addition of the microtubule polymerization inhibitors nocodazol or benomyl to the medium or deletion of the nonessential alpha-tubulin TUB3 gene can mostly correct the abnormal microtubule arrays and other growth defects of kar3 mutants, suggesting that these phenotypes result from excessive microtubule polymerization. Microtubule depolymerization may also be the mechanism by which Kar3p acts in opposition to the anaphase B motors Cin8p and Kip1p. A preanaphase spindle collapse phenotype of cin8 kip1 mutants, previously shown to involve Kar3p, is markedly delayed when microtubule depolymerization is inhibited by the tub2-150 mutation. These results suggest that the Kar3p motor may act to regulate the length and number of microtubules in the preanaphase spindle.