Cell Death in Retinoblastoma: Electron Microscopic,Immunohistochemical, and DNA Fragmentation Studies

Apparent cell loss by apoptosis occurs in carcinomatous tissue. To investigate cell death in retinoblastoma (Rb), ultrastructural examination, ApopTag staining, electrophoresis to detect apoptotic DNA fragmentation, and flow cytometric studies were performed. Immunostaining for the oncogenic products bcl-2 and p53 was also carried out. Relationships between the proliferation fraction (PF), apoptotic index (AI), and the distribution of bcl-2 and p53 were investigated according to the degree of histologic differentiation of Rb. Ultrastructurally,two patterns of cell death were seen. Necrotic cells exhibited vacuolation of cytoplasmic organelles with a marked lytic change in the karyoplasm and cytoplasm. In contrast, apoptotic cells were characterized by crescentic margination of chromatin, condensation of karyoplasm and cytoplasm, and fragmentation of the nucleus. Differentiated Rb had a low AI value (< 1%),whereas undifferentiated Rb had a high AI value (> 8%). The PF of undifferentiated RB (31%) was significantly higher than that of differentiated RB (14%). Analysis of DNA fragmentation using 3'-end labeling with terminal transferase indicated that undifferentiated Rb has increased DNA cleavage. The distribution of apoptotic bodies within Rb was inversely correlated with the expression of bcl-2. A majority of tumor cells of differentiated Rb were negative for p53, whereas 20-40% of tumor cells of undifferentiated Rb showed a positive reaction for p53. These findings suggest that the degree of susceptibility to apoptosis is closely related to PF, is inversely related to the degree of differentiation of Rb, and is protected by oncogene bcl-2.     

Dexamethasone promotes tolerance in vivo by enriching CD11cloCD40lo tolerogenic macrophages

We previously showed that antigen immunization in the presence of the immunosuppressant dexamethasone (a strategy we termed “suppressed immunization”) could tolerize established recall responses of T cells. However, the mechanism by which dexamethasone acts as a tolerogenic adjuvant has remained unclear. In the present study, we show that dexamethasone enriches CD11c^loCD40^lo macrophages in a dose‐dependent manner in the spleen and peripheral lymph nodes of mice by depleting all other CD11c⁺CD40⁺ cells including dendritic cells. The enriched macrophages display a distinct MHC class II (MHC II)^loCD86^hi phenotype. Upon activation by antigen in vivo, CD11c^loCD40^lo macrophages upregulate IL‐10, a classic marker for tolerogenic antigen‐presenting cells, and elicit a serum IL‐10 response. When presenting antigen in vivo, these cells do not elicit recall responses from memory T cells, but rather stimulate the expansion of antigen‐specific regulatory T cells. Moreover, the depletion of CD11c^loCD40^lo macrophages during suppressed immunization diminishes the tolerogenic efficacy of the treatment. These results indicate that dexamethasone acts as a tolerogenic adjuvant partly by enriching the CD11c^loCD40^lo tolerogenic macrophages.     

Inhibitory role of Smad7 in hepatocarcinogenesis in mice and in vitro

Smad7 is a principal inhibitor of the TGFβ–Smad signalling pathway. We have investigated the functional significance of Smad7 in hepatocellular carcinoma (HCC). Smad7 knockout (KO) and wild‐type (WT) mice were injected with diethylnitrosamine (DEN) to induce HCC. The effects of Smad7 on cellular features were examined in HCC cells, using a Smad7 over‐expression or deletion approach. Signalling pathway components modulated by Smad7 in HCC were evaluated using luciferase reporter assay and co‐immunoprecipitation. Smad7 was down‐regulated in human HCCs compared with the adjacent normal tissues (p < 0.001). Smad7 KO mice were more susceptible to DEN‐induced HCC than WT mice (78% versus 22%, p < 0.05). HCCs from KO mice displayed a greater proliferation activity (p < 0.05) and a reduced apoptotic index compared with WT littermates (p < 0.05). Deletion of Smad7 promoted cell proliferation in primary cultured HCC cells. In addition, over‐expression of Smad7 in HCC cell lines markedly suppressed cell growth (p < 0.0001) and colony formation (p < 0.01). Cell cycle analysis revealed an increase in the G₁ phase and a reduction in the S‐phase populations, accompanied by up‐regulation of p27^Kip1 and down‐regulation of cyclin D1. Smad7 increased cell apoptosis (p < 0.01) by mediating an intrinsic [caspase‐9, caspase‐3 and poly(ADP‐ribose) polymerase] apoptotic pathway. Moreover, Smad7 inhibited NF‐κB signalling by interacting with TAB2, an upstream activator of NF‐κB, and inhibited TGFβ signalling by suppressing phosphorylation of Smad3. In conclusion, loss of Smad7 enhances susceptibility to HCC. Smad7 suppresses HCC cell growth by inhibiting proliferation and G₁–S phase transition and inducing apoptosis through attenuation of NF‐κB and TGFβ signalling. Smad7 acts as a potential tumour suppressor in liver. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

The Essential Oil Isolated from Artemisia capillaris Prevents LPS-Induced Production of NO and PGE2 by Inhibiting MAPK-Mediated Pathways in RAW 264.7 Macrophages

Artemisia capillaris (A. capillaris) is used in traditional Korean herbal medicine for its believedanti-inflammatory activities. Previous studies have suggested that the essential oil of A. capillaris contains the active components responsible for its pharmacological effect, even though the mechanism for its action is unclear. This study examined the inhibitory effects of the essential oil of A. capillaris on the lipopolysaccharide (LPS)-induced production of nitric oxide (NO) and prostaglandin E₂ (PGE₂). The essential oil significantly inhibited the production of NO in the LPS-stimulated RAW 264.7 macrophages, which was mediated by the down-regulation of inducible NO synthase (iNOS) expression but not by its direct cytotoxic activity. The essential oil also blocked the secretion of PGE₂ and the expression of cyclooxygenase-2 (COX-2) in the LPS-stimulated cells. Western blot analysis showed that the essential oil inhibited the phosphorylation of IκB-α, nuclear translocation of p65, and subsequent activation of NF-κB. In addition, the essential oil suppressed the LPS-stimulated activation of mitogen-activated protein kinases (MAPKs) as well as the AP-1 DNA-binding activity. Moreover, MAPK inhibitors significantly reduced the LPS-induced production of NO and PGE₂. Collectively, we suggest that the oil inhibits the expression and production of inflammatory mediators by blocking the MAPK-mediated pathways and inhibiting the activation of NF-κB and AP-1.     

Mutations in the rpoB gene of Mycobacterium tuberculosis that interfere with PCR-single-strand conformation polymorphism analysis for rifampin susceptibility testing.

Rifampin susceptibility of 32 rifampin-resistant and 26 rifampin-susceptible Mycobacterium tuberculosis strains was analyzed by PCR-single-strand conformation polymorphism (SSCP) and DNA sequencing within the 157-bp region of the rpoB gene (Ala500 to Val550). Two false-positive PCR-SSCP results were observed among the susceptible strains due to the silent mutation Gln513 (CAA-->CAG) and the deletion mutation Thr508 and Ser509. Another silent mutation [Leu511 (CTG-->CTA)], combined with the mutation Ser531-->Leu, was observed in a resistant strain. These results suggest that to rule out false-positive PCR-SSCP results, sequencing of the target DNA is required.     

A novel splice site mutation of the arginine vasopressin-neurophysin II gene identified in a kindred with autosomal dominant familial neurohypophyseal diabetes insipidus

Autosomal dominant familial neurohypophyseal diabetes insipidus is an inherited deficiency of arginine vasopressin (AVP), and this is caused by mutations in the AVP-neurophysin II (AVP-NP II) gene. Most of these mutations have been located in the signal peptide or in the NP II moiety. In the present study, we have analyzed the AVP-NP II gene in a Korean family. Clinical and genetic studies were performed on three members of the family, and on a normal healthy unrelated individual. The diagnosis of neurohypophyseal diabetes insipidus was done by performing a fluid deprivation test and a vasopressin challenge. For genetic analysis, the genomic DNA was extracted and the AVP-NP II gene was amplified by polymerase chain reaction (PCR). Clinical assessment of the affected individuals confirmed the diagnosis of neurohypophyseal diabetes insipidus. Genetic analysis of the AVP-NP II gene revealed a novel deletion mutation of a single nucleotide (guanine) within the splice acceptor site of intron 2 (IVS2 +1 delG). The affected individuals were heterozygous for this mutation. We also demonstrated through RT-PCR analysis of the mutant gene that this mutation resulted in the retention of intron 2 during pre-mRNA splicing. We concluded that a novel splicing mutation in the AVP-NP II gene causes neurohypophyseal diabetes insipidus in this family.     

Prevalence of the ST239 clone of methicillin-resistant Staphylococcus aureus and differences in antimicrobial susceptibilities of ST239 and ST5 clones identified in a Korean hospital

A total of 188 nonduplicate methicillin-resistant Staphylococcus aureus (MRSA) isolates obtained between 2001 and 2004 in a university hospital in Daegu, Korea, were analyzed for their clonal types by molecular typing techniques, including multilocus sequence typing, spaA typing, staphylococcal chromosomal cassette mec (SCCmec) typing, and pulsed-field gel electrophoresis (PFGE). They were examined for their antimicrobial susceptibilities. The majority (87%) of MRSA isolates belonged to sequence type 239 (ST239; n = 100; 53%) and ST5 (n = 63, 34%) on the basis of sequence typing. MRSA isolates belonging to ST239 were genotypically homogeneous, while those belonging to ST5 showed variations in spaA type, SCCmec type, and PFGE patterns. The rates of resistance of the MRSA isolates belonging to ST239 to trimethoprim, sulfamethoxazole, tobramycin, gentamicin, erythromycin, and tetracycline were significantly higher than those of the isolates belonging to ST5 (P < 0.05). This study demonstrated that the ST239 clone, while rarely detected in Korea, was prevalent and that the antimicrobial susceptibility of the ST239 clone was significantly different from that of the ST5 clone.     

The effect of iodine restriction on thyroid function in patients with hypothyroidism due to Hashimoto's thyroiditis

Lifelong thyroid hormone replacement is indicated in patients with hypothyroidism as a result of Hashimoto's thyroiditis. However, previous reports have shown that excess iodine induces hypothyroidism in Hashimoto's thyroiditis. This study investigated the effects of iodine restriction on the thyroid function and the predictable factors for recovery in patients with hypothyroidism due to Hashimoto's thyroiditis. The subject group consisted of 45 patients who had initially been diagnosed with hypothyroidism due to Hashimoto's thyroiditis. The subjects were divided randomly into two groups. One group was an iodine intake restriction group (group 1) (iodine intake: less than 100 micro g/day) and the other group was an iodine intake non-restriction group (group 2). The thyroid-related hormones and the urinary excretion of iodine were measured at the baseline state and after 3 months. After 3 months, a recovery to the euthyroid state was found in 78.3 % of group 1 (18 out of 23 patients), which is higher than the 45.5% from group 2 (10 out of 22 patients). In group 1, mean serum fT4 level (0.80 +/- 0.27 ng/dL at the baseline, 0.98 +/- 0.21 ng/dL after 3 months) and the TSH level (37.95 +/- 81.76 micro IU/mL at the baseline, 25.66 +/- 70.79 micro IU/mL after 3 months) changed significantly during this period (p < 0.05). In group 2, the mean serum fT4 level decreased (0.98 +/- 0.17 ng/dL at baseline, 0.92 +/- 0.28 ng/dL after 3 months, p < 0.05). In the iodine restriction group, the urinary iodine excretion values were higher in the recovered patients than in non-recovered patients (3.51 +/- 1.62 mg/L vs. 1.21 +/- 0.39 mg/ L, p=0.006) and the initial serum TSH values were lower in the recovered patients than in the non-recovered patients (14.28 +/- 12.63 micro IU/mL vs. 123.14 +/- 156.51 micro IU/mL, p=0.005). In conclusion, 78.3% of patients with hypothyroidism due to Hashimoto's thyroiditis regained an euthyroid state iodine restriction alone. Both a low initial serum TSH and a high initial urinary iodine concentration can be predictable factors for a recovery from hypothyroidism due to Hashimoto's thyroiditis after restricting their iodine intake.