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Heterozygous mutation of ataxia-telangiectasia mutated gene aggravates hypercholesterolemia in apoE-deficient mice.

Individuals with a heterozygous mutation at the ataxia-telangiectasia mutated gene (ATM) have been reported to be predisposed to ischemic heart disease. This report examined for the first time the effect of a heterozygous ATM mutation (ATM(+)(/-)) on plasma lipid levels and atherosclerosis intensity using ATM(+/-), ATM(+)(/+) (wild type), ATM(+)(/+)/LDLR(-)(/-) (low density lipoprotein receptor knockout), ATM(+)(/-)/LDLR(-)(/-), ATM(+)(/+)/ApoE(-)(/-) (apolipoprotein E knockout), and ATM(+)(/-)/ApoE(-)(/-) mice. Our data demonstrated that the plasma cholesterol and triglyceride levels in ATM(+)(/-) and ATM(+)(/-)/LDLR(-)(/-) mice were approximately the same as those in ATM(+)(/+) and ATM(+)(/+)/LDLR(-)(/-) control mice, respectively. In contrast, the plasma cholesterol level was significantly higher in ATM(+)(/-)/ApoE(-)(/-) mice than in ATM(+)(/+)/ApoE(-)(/-) control mice. In addition, the ATM(+)(/-)/ApoE(-)(/-) mice showed higher plasma apoB-48 levels, slower clearance for plasma apoB-48-carrying lipoproteins, and more advanced atherosclerotic lesions in the aorta compared with the ATM(+)(/+)/ApoE(-)(/-) mice. These novel results suggest that the product of ATM is involved in an apoE-independent pathway for catabolism of apoB-48-carrying remnants; therefore, superimposition of a heterozygous ATM mutation onto an ApoE deficiency background reduces the clearance of apoB-48-carrying lipoproteins from the blood circulation and promotes the formation of atherosclerosis.

Animals↗

Transplantation of vascular endothelial growth factor-transfected neural stem cells into the rat brain provides neuroprotection after transient focal cerebral ischemia.

OBJECTIVE: Vascular endothelial growth factor (VEGF) stimulation and neural stem cell (NSC) transplantation have been implicated in the treatment of cerebral ischemia because of their crucial roles in neuroprotection, neurogenesis, and angiogenesis. However, effective delivery of VEGF or NSCs remains difficult. This study attempted to explore whether VEGF121 complementary deoxyribonucleic acid could be transferred into the NSCs and, furthermore, whether transplanting these VEGF121-transfected NSCs into the rat brain provides sufficient neuroprotection after transient focal cerebral ischemia. METHODS: The VEGF121 gene was transfected to the NSCs isolated from E14 fetal rat hippocampus. In vitro studies revealed that VEGF messenger ribonucleic acid could be consistently expressed in NSCs from 1 day to up to 2 weeks. RESULTS: After transplantation of VEGF121-transfected NSCs into the perifocal area of the ischemic rat brain, we found that these cells could survive and migrate in the ischemic region for 12 weeks. Furthermore, we observed a significant improvement of the Neurological Severity Scale score in the rats transplanted with VEGF121-transfected NSCs in comparison to the phosphate-buffered saline-injected or the sham-operated rats (P < 0.05). Transplantation of nontransfected NSCs into ischemic rat brain improved the Neurological Severity Scale score as well. Of note, the improvement in the Neurological Severity Scale score occurred earlier in the VEGF121-transfected NSC rats than in the nontransfected NSC rats (range, 2-12 wk versus 8-12 wk), suggesting a potent neuroprotection mediated by additional VEGF121 transfection. CONCLUSION: We conclude that transplantation of VEGF121-transfected NSCs improved ischemic neurological deficiency. This finding provides a novel approach for the treatment of cerebral ischemia.

Animals↗

Adenosine-dependent pulmonary fibrosis in adenosine deaminase-deficient mice.

Pulmonary fibrosis is a common feature of numerous lung disorders, including interstitial lung diseases, asthma, and chronic obstructive pulmonary disease. Despite the prevalence of pulmonary fibrosis, the molecular mechanisms governing inflammatory and fibroproliferative aspects of the disorder are not clear. Adenosine is a purine-signaling nucleoside that is generated in excess during cellular stress and damage. This signaling molecule has been implicated in the regulation of features of chronic lung disease; however, the impact of adenosine on pulmonary fibrosis is not well understood. The goal of this study was to explore the impact of endogenous adenosine elevations on pulmonary fibrosis. To accomplish this, adenosine deaminase (ADA)-deficient mice were treated with various levels of ADA enzyme replacement therapy to regulate endogenous adenosine levels in the lung. Maintaining ADA-deficient mice on low dosages of ADA enzyme therapy led to chronic elevations in lung adenosine levels that were associated with pulmonary inflammation, expression of profibrotic molecules, collagen deposition, and extreme alteration in airway structure. These features could be blocked by preventing elevations in lung adenosine. Furthermore, lowering lung adenosine levels after the establishment of pulmonary fibrosis resulted in a resolution of fibrosis. These findings demonstrate that chronic adenosine elevations are associated with pulmonary fibrosis in ADA-deficient mice and suggest that the adenosine functions as a profibrotic signal in the lung.

Adenosine↗

[Antisense inhibition of gene expression in human dendritic cells by peptide nucleic acid against CD86].

OBJECTIVE: Dendritic cells (DCs) are the most potent antigen presenting cells (APCs) of the immune system. We intent to block the expression of CD86 in DCs using antisense peptide nucleic acids (PNA), a novel synthetic structural DNA mimic, and interrupt the second signal transmission so that a suppression of corresponding T cell function can be achieved. METHODS: Human DCs grown up from peripheral blood monocytes in GM-CSF and IL-4 were collected. We investigated antisense PNA internalization with laser scan confocal microscope (LSCM). Fluorescence immunocytochemistry, flow cytometry and RT-PCR were used to determine the expression of CD86 protein and mRNA in DCs. RESULTS: LSCM proved that cultured immature DCs could internalized PNA efficiently, according to the specific internalization property of the immature DCs. Antisense PNA DC exhibited striking reductions in cell surface staining for CD86, but not MHC class II, and were poor stimulators of T cell proliferation. RT-PCR found that PNA depressed the amounts of CD86 mRNA in DCs. CONCLUSION: Antisense PNA against CD86 could inhibit the expression of CD86 mRNA and protein in DCs. The blockade of B7/CD28 pathway may increase the potential of costimulatory molecule-deficient antisense PNA DCs of donor origin to induce long-lasting allograft survival.

Antigens, CD↗

[An epidemiological study on factors affecting serum thyroglobulin levels].

OBJECTIVE: To investigate the effects of several factors affecting serum thyroglobulin (TG) levels among people aged 14 or more. METHODS: We selected Panshan with median urinary iodine (MUI) 83.45 micro g/L as a deficient iodine intake community, Zhangwu with MUI 242.85 micro g/L as a sufficient iodine intake community and Huanghua with MUI 650.87 micro g/L as an excessive iodine intake community. Serum TG and thyroid stimulating hormone (TSH) were measured in 3,335 subjects whose thyroglobulin antibody (TGAb) were negative and thyroid volume were examined using B-ultrasound. RESULTS: In the population with MUI of 80 - 650 micro g/L, serum TG levels presented a "V" curve. An elevated serum TG was found in both the communities with deficient iodine intake and excessive iodine intake. The same trend was shown in the groups with different levels of serum TSH. An elevated serum TG was found in both the groups of TSH < 0.3 mU/L and TSH > 4.8 mU/L. The serum TG levels was positively correlated with thyroid volume and was higher in female subjects than in male. An increased serum TG was found in subjects of aged 50 in the community with deficient iodine intake. CONCLUSION: Serum TG level is affected by gender, amount of iodine intake, serum TSH level and thyroid volume.

Adolescent↗

[Mutation-function analysis in the lipoprotein lipase gene of Chinese patients with hypertriglyceridemic type 2 diabetes].

OBJECTIVE: To investigate the role of lipoprotein lipase (LPL) gene on Chinese patients with hypertriglyceridemic type 2 diabetes. METHODS: Three subject groups, including hypertriglyceridemic group, normalipidemic type 2 diabetes group and healthy controls, were recruited and screened for sequence changes in LPL gene with PCR, SSCP, restriction analysis and direct DNA sequencing. LPL mass and activity in post-heparin plasma and in in vitro expression were investigated. Comparative modeling was performed via Swiss-PDB Viewer to provide the potential 2-D structures of wildtype and mutant proteins. RESULTS: Four missense mutations, Ala71Thr, Val18Ile, Gly188Glu and Glu242Lys, were identified in patients with hypertriglyceridemic type 2 diabetes, and not in both normalipidemic diabetes and the control subjects. The four missense mutations were located in the highly conserved amino acid sites, which are involved in highly conserved exon 3, 5, or 6 regions. They led to reduced LPL mass and enzyme activities in both post-heparin plasma and in vitro expression. The modeled structures displayed the differences to a great extent between the mutant and wide-type molecules. CONCLUSION: These results indicated that the 4 missense mutations lead to LPL deficiency and subsequent hypertriglyceridemia. The LPL deficiency predispose a progressive diabetic pathway to those affected individuals. LPL gene is one of susceptibility gene for hypertriglyceridemic type 2 diabetes.

Asian People↗

[Effects of treatment with redox agent, blood transfusion and scopolamine on 200 patients with severe chlorphenamidine poisoning].

OBJECTIVE: To verify the effects of treatment with blood transfusion and scopolamine on severe chlorphenamidine poisoning (SCP). METHODS: 400 patients with severe oral chlorphenamidine poisoning were randomly divided into two groups. 200 patients (Group I) were treated with the traditional combined therapy including gastrolavage, purgation and taking redox agent (methylene blue and vitamin C) while the other 200 patients (Group II) in addition to the above mentioned therapy, received blood transfusion and scopolamine injection. RESULTS: The cure rate of Group II was 99.5% and significantly higher than that of Group I (91.0%, P < 0.01). The average time of improving in health in Group II [(8.71 +/- 1.49) h] was obviously shorter than those in Group I [(10.65 +/- 1.72) h, P < 0.01]. Blood methemoglobin concentrations in Group II at 3, 7, 12, 24 h after admission [(43.58 +/- 2.69), (34.21 +/- 2.30), (20.60 +/- 4.03), (13.50 +/- 1.65) g/L respectively] were obviously lower than those in Group I [(54.42 +/- 12.79), (42.17 +/- 22.34), (30.66 +/- 17.67), (19.01 +/- 0.61) g/L respectively, P < 0.01]. CONCLUSION: Blood transfusion and scopolamine had distinctive therapeutic effect on SCP to makeup the deficiency of redox agent. Combination of three therapies may potentiate the detoxication for chlorphenamidine.

Adult↗

Purification and quantitation of a rat plasma selenoprotein distinct from glutathione peroxidase using monoclonal antibodies.

Studies with 75Se have shown the existence of a rat plasma selenoprotein in addition to glutathione peroxidase. Because the function of the protein is not known, it has been referred to as selenoprotein P. A partially purified preparation was used to produce a monoclonal antibody to selenoprotein P. The antibody did not bind glutathione peroxidase as evidenced by its failure to remove glutathione peroxidase activity from rat plasma by immunoprecipitation. An immunoaffinity column was prepared with the monoclonal antibody, and selenoprotein P was purified 1270-fold from rat plasma in a two-step procedure. The purified selenoprotein P migrated in a single band with an Mr of 57,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Autoradiography demonstrated that this band contained 75Se when the protein was purified from rats which had received 75SeO2-(3). A competitive radioimmunoassay for selenoprotein P was developed. The selenoprotein P concentration in plasma of selenium-replete rats was determined with this assay to be 51 +/- 3.7 micrograms/ml. It was less than 5 micrograms/ml in plasma from selenium-deficient rats. Injection of 50 micrograms of selenium into selenium-deficient rats caused an increase in selenoprotein P from less than 10% of control to 52% of control in 6 h. Plasma glutathione peroxidase activity increased only from 2.2 to 3.1% of control. These experiments demonstrate that rat plasma contains a selenoprotein distinct from glutathione peroxidase. The concentration of this selenoprotein is depressed in selenium deficiency, as is glutathione peroxidase activity, but selenoprotein P increases more rapidly when selenium is supplied than does glutathione peroxidase activity.

Animals↗

Regulated expression and function of CD122 (interleukin-2/interleukin-15R-beta) during lymphoid development.

To determine whether signaling via CD122 (interleukin-2 [IL-2]/IL-15 receptor beta-chain) plays a role in regulating the expansion and differentiation of lymphocyte precursors, we have characterized its expression and evaluated its ability to influence the activity of developing lymphoid cells. A significant fraction of Sca1+Lin- hematopoietic stem cells in day 12 fetal liver were found to be CD122+. CD122-mRNA+ and IL-2-mRNA+ cells were also localized in embryo sections within pharyngeal blood vessels adjacent to and surrounding the thymic analgen. This distribution is consistent with the migration of CD122+ progenitor cells from the liver to the developing thymus where a majority of Sca1+ intrathymic T-cell progenitors were CD122+. Analysis of CD122 expression in the day 12 fetal liver revealed that the majority of B220+ cells were CD122+. Furthermore, CD122 expression was restricted to the earliest B220+ cells (CD43+CD24-; prepro B cells; fraction A) that proliferate vigorously to IL-2 in the absence of any stromal cells, but not to IL-15. Consistent with a role for the IL-2/IL-2R pathway in lymphocyte development is the progressive loss of B cells seen in IL-2-deficient mice. Together, these observations suggest that CD122 plays a role in regulating normal lymphocyte development in vivo.

Animals↗

Clinical features and ALDH5A1 gene findings in 13 Chinese cases with succinic semialdehyde dehydrogenase deficiency.

BACKGROUND AND AIMS: To investigate the clinical features, ALDH5A1 gene variations, treatment, and prognosis of patients with succinic semialdehyde dehydrogenase (SSADH) deficiency. MATERIALS AND METHODS: This retrospective study evaluated the findings in 13 Chinese patients with SSADH deficiency admitted to the Pediatric Department of Peking University First Hospital from September 2013 to September 2023. RESULTS: Thirteen patients (seven male and six female patients; two sibling sisters) had the symptoms aged from 1 month to 1 year. Their urine 4-hydroxybutyrate acid levels were elevated and were accompanied by mildly increased serum lactate levels. Brain magnetic resonance imaging (MRI) showed symmetric abnormal signals in both sides of the globus pallidus and other areas. All 13 patients had psychomotor retardation, with seven showing epileptic seizures. Among the 18 variants of the ALDH5A1 gene identified in these 13 patients, six were previously reported, while 12 were novel variants. Among the 12 novel variants, three (c.85_116del, c.206_222dup, c.762C&#x2009;>&#x2009;G) were pathogenic variants; five (c.427delA, c.515G&#x2009;>&#x2009;A, c.637C&#x2009;>&#x2009;T, c.755G&#x2009;>&#x2009;T, c.1274T&#x2009;>&#x2009;C) were likely pathogenic; and the remaining four (c.454G&#x2009;>&#x2009;C, c.479C&#x2009;>&#x2009;T, c.1480G&#x2009;>&#x2009;A, c.1501G&#x2009;>&#x2009;C) were variants of uncertain significance. The patients received drugs such as L-carnitine, vigabatrin, and taurine, along with symptomatic treatment. Their urine 4-hydroxybutyric acid levels showed variable degrees of reduction. CONCLUSIONS: A cohort of 13 cases with early-onset SSADH deficiency was analyzed. Onset of symptoms occurred from 1 month to 1 year of age. Twelve novel variants of the ALDH5A1 gene were identified.

Child, Preschool↗

Factor VII deficiency caused by a structural variant N57D of the first epidermal growth factor domain.

We have previously described a kindred with factor VII (FVII) deficiency whose members exhibited reduced procoagulant activity relative to FVII antigen concentration. In this report, the molecular genetic basis of the FVII defect has been determined to be a heterozygous substitution of Asp for Asn at position 57 in the first epidermal growth factor (EGF) domain. Recombinant FVII (N57D) cDNA was created by site-directed mutagenesis and transiently expressed in human 293 cells. The transfected cells synthesized an immunoprecipitable protein with an apparent molecular weight of 50 kD. Quantitation of expression by FVII enzyme-linked immunosorbent assay indicated that mutant protein yields were consistently low, typically 10% to 30% of wild-type FVII. FVII (N57D) protein did not accumulate intracellularly, and Northern blot analysis indicated equivalent FVII mRNA levels in 293 cells expressing either wild-type FVII or FVII (N57D). Secreted FVII (N57D) protein did not bind tissue factor, exhibited no procoagulant activity, and failed to bind a conformation-dependent monoclonal antibody specific for the first EGF domain of FVII. Molecular modeling of the first EGF domain of FVII predicted that the N57D amino acid substitution would disrupt tertiary bonding structure. We conclude that the N57D mutation affects folding of the first EGF domain of FVII resulting in decreased cellular secretion of a mutant FVII molecule, which is unable to bind tissue factor and is therefore biologically inactive.

Animals↗

A truncated COL10A1 protein causes Schmid metaphyseal chondrodysplasia via protein downregulation and impairing &#x3b1;1 trimer formation and secretion.

Schmid-type metaphyseal chondrodysplasia (SMCD) is primarily caused by mutations in the COL10A1 gene. This study reports a novel frameshift mutation, c.1940dup (p.Asn647Lysfs*2), identified in a Chinese SMCD pedigree. The mutation did not alter messenger RNA levels but significantly reduced COL10A1 protein expression. The mutant protein lacks the C-terminal 33 amino acids, resulting in a truncated polypeptide of 648 residues with a lower molecular weight than the wild-type protein. Degradation kinetics analysis showed no evidence of accelerated turnover. Notably, even under complete inhibition of degradation pathways, mutant protein expression remained substantially lower than that of wild-type, suggesting a potential defect in translational efficiency. Furthermore, the mutation severely disrupted the assembly of the characteristic collagen X trimer and led to markedly reduced extracellular secretion, as measured by accumulated protein levels in conditioned medium. These findings demonstrate that the c.1940dup mutation contributes to SMCD pathogenesis through coordinated mechanisms involving protein truncation, reduced expression, probable translational deficiency, and defective trimer formation and secretion, thereby revealing new potential therapeutic targets.

Osteochondrodysplasias↗

X-linked recessive progressive combined variable immunodeficiency (Duncan's disease).

Of 18 boys in Duncan kindred, 6 died of a lymphoproliferative disease. They exhibited a subtle, progressive combined variable immunodeficiency disease characterised by benign or malignant proliferation of lymphocytes, histiocytosis, and alterations in concentrations of serum-immunoglobulins. Infectious mononucleosis occurred during or preceding terminal events in at least 3 of the cousins. Fever, pharyngitis, lymphadenomegaly, hepatosplenomegaly, atypical lymphocytosis, and a spectrum ranging from agammaglobulinaemia to polyclonal hyper-gammaglobulinaemia occurred. At necropsy, the thymus gland and thymic-dependent areas in the lymph-nodes and spleen were depleted of lymphocytes. Diffuse infiltrates composed of lymphocytes, plasma cells, and histiocytes, some containing erythrocytes, invaded the haematopoietic organs, viscera, and central nervous system. In addition, 2 half-brothers had lymphomas of the ileum and central nervous system. Approximately half the boys, including the half-brothers, were affected, and girls were spared, implying sex-linked recessive inheritance. Various lymphohistiocytoses resemble Duncan's disease, but it is distinctive from them in the mode of inheritance or by histiological characteristics. This study suggests that the Epstein-Barr virus or other viruses triggered the fatal proliferation of lymphocytes and that progressive attrition of T-cell functions allowed uncontrolled lymphoproliferation.

Adult↗

Differentiation of CD4+ T cells to Th1 cells requires MAP kinase JNK2.

Precursor CD4+ T cells develop into effector Th1 and Th2 cells that play a central role in the immune response. We show that the JNK MAP kinase pathway is induced in Th1 but not in Th2 effector cells upon antigen stimulation. Further, the differentiation of precursor CD4+ T cells into effector Th1 but not Th2 cells is impaired in JNK2-deficient mice. The inability of IL-12 to differentiate JNK2-deficient CD4+ T cells fully into effector Th1 cells is caused by a defect in IFNgamma production during the early stages of differentiation. The addition of exogenous IFNgamma during differentiation restores IL-12-mediated Th1 polarization in the JNK2-deficient mice. The JNK MAP kinase signaling pathway, therefore, plays an important role in the balance of Th1 and Th2 immune responses.

Amino Acid Sequence↗

The glycine N-methyltransferase (GNMT) 1289 C->T variant influences plasma total homocysteine concentrations in young women after restricting folate intake.

Glycine N-methyltransferase (GNMT) is a key regulatory protein in folate metabolism, methionine availability, and transmethylation reactions. Perturbations in GNMT may lead to aberrations in homocysteine metabolism, a marker of numerous pathologies. The primary objective of this study was to examine the influence of the GNMT 1289 C-->T alone, and in combination with the methylenetetrahydrofolate reductase (MTHFR) 677 C-->T variant, on plasma total homocysteine concentrations in healthy young women (n = 114). Plasma total homocysteine was measured at baseline (wk 0) and after 2 wk of controlled folate restriction (135 microg/d as dietary folate equivalents). Plasma homocysteine concentrations did not differ among the GNMT C1289T genotypes at baseline. However, after folate restriction, women with the GNMT 1289 TT genotype (n = 16) had higher (P = 0.019) homocysteine concentrations than women with the CT (n = 51) or CC (n = 47) genotype. The influence of the GNMT 1289 C-->T variant on homocysteine was dependent on the MTHFR C677T genotype. In subjects with the MTHFR 677 CC genotype, homocysteine was greater (P < or = 0.05) for GNMT 1289 TT subjects relative to 1289 CT or CC subjects. However, in subjects with the MTHFR 677 TT genotype, plasma homocysteine concentrations did not differ among the GNMT C1289T genotypes. Overall, these data suggest that the GNMT 1289 C-->T polymorphism influences plasma homocysteine and is responsive to folate intake.

Adult↗

CD8+ T cells mediate recovery and immunopathology in West Nile virus encephalitis.

C57BL/6J mice infected intravenously with the Sarafend strain of West Nile virus (WNV) develop a characteristic central nervous system (CNS) disease, including an acute inflammatory reaction. Dose response studies indicate two distinct kinetics of mortality. At high doses of infection (10(8) PFU), direct infection of the brain occurred within 24 h, resulting in 100% mortality with a 6-day mean survival time (MST), and there was minimal destruction of neural tissue. A low dose (10(3) PFU) of infection resulted in 27% mortality (MST, 11 days), and virus could be detected in the CNS 7 days postinfection (p.i.). Virus was present in the hypogastric lymph nodes and spleens at days 4 to 7 p.i. Histology of the brains revealed neuronal degeneration and inflammation within leptomeninges and brain parenchyma. Inflammatory cell infiltration was detectable in brains from day 4 p.i. onward in the high-dose group and from day 7 p.i. in the low-dose group, with the severity of infiltration increasing over time. The cellular infiltrates in brain consisted predominantly of CD8(+), but not CD4(+), T cells. CD8(+) T cells in the brain and the spleen expressed the activation markers CD69 early and expressed CD25 at later time points. CD8(+) T-cell-deficient mice infected with 10(3) PFU of WNV showed increased mortalities but prolonged MST and early infection of the CNS compared to wild-type mice. Using high doses of virus in CD8-deficient mice leads to increased survival. These results provide evidence that CD8(+) T cells are involved in both recovery and immunopathology in WNV infection.

Animals↗

Deficiency of iNOS does not attenuate severe congestive heart failure in mice.

Inducible nitric oxide synthase (iNOS) has been implicated in the pathophysiology of congestive heart failure (CHF). Given the extensive evidence supporting this concept, we hypothesized that iNOS deficiency (iNOS(-/-)) would attenuate the severity of CHF in mice. Mice were subjected to permanent occlusion [myocardial infarction (MI)] of the proximal left anterior descending coronary artery to produce CHF. Cardiac function was assessed in vivo using echocardiography and ultraminiature ventricular pressure catheters. Sham wild-type (n = 17), sham iNOS(-/-) (n = 8), MI wild-type (n = 56), and MI iNOS(-/-) (n = 48) mice were subjected to MI (or sham MI) and followed for 1 mo. Deficiency of iNOS did not alter survival during CHF compared with wild type (35% vs. 32%, P = not significant). Furthermore, fractional shortening and cardiac output were not significantly different between wild-type (9.6 +/- 2.0% and 441 +/- 20 microl.min(-1).g(-1)) and iNOS(-/-) (9.8 +/- 1.3% and 471 +/- 26 microl.min(-1).g(-1)) mice. The extent of cardiac hypertrophy and pulmonary edema was also similar between wild-type and iNOS(-/-) mice. None of the indexes demonstrated any significant differences between iNOS(-/-) and wild-type mice subjected to MI. These findings indicate that deficiency of iNOS does not significantly affect severe CHF in mice after MI.

Animals↗

An Msh2 point mutation uncouples DNA mismatch repair and apoptosis.

Mutations in the human DNA mismatch repair gene MSH2 are associated with hereditary nonpolyposis colorectal cancer as well as a significant proportion of sporadic colorectal cancer. The inactivation of MSH2 results in the accumulation of somatic mutations in the genome of tumor cells and resistance to the genotoxic effects of a variety of chemotherapeutic agents. Here we show that the DNA repair and DNA damage-induced apoptosis functions of Msh2 can be uncoupled using mice that carry the G674A missense mutation in the conserved ATPase domain. As a consequence, although Msh2(G674A) homozygous mutant mice are highly tumor prone, the onset of tumorigenesis is delayed as compared with Msh2-null mice. In addition, tumors that carry the mutant allele remain responsive to treatment with a chemotherapeutic agent. Our results indicate that Msh2-mediated apoptosis is an important component of tumor suppression and that certain MSH2 missense mutations can cause mismatch repair deficiency while retaining the signaling functions that confer sensitivity to chemotherapeutic agents.

Alanine↗