Phase Transition In Metal Hexammine Complexes. Ii. The Epr Spectra Of Ni(no3)26nh3 And Ni++ Doped Zn(no3)26nh3 And Cd(no3) 26nh3

The cooperative effect of the ammonias in X(NO3) 26NH3 (X=Ni,Zn,Cd) was investigated by EPR. In Ni(NO 3)26NH3, the linewidth of the single EPR absorption line undergoes a sudden broadening at Tc=243 K. This effect is probably a result of a cooperative freezing of the degrees of freedom of rotation of the ammonias, giving the appearance of a crystal field on the Ni++ ions. The crystal field does not split the single line, probably because strong exchange effects assemble the lines. The crystal field parameter D=0.425 cm-1 was evaluated by applying the Anderson and Weiss theory for the exchange narrowing of the linewidth. Small quantities of the Ni ++ ions in Zn and Cd salts do not exhibit strong exchange effects. So the single EPR absorption line above Tc goes to a split line below Tc. For Ni:Zn(NO3)26NH3, T c=231 K and D=0.606 cm-1. For Ni:Cd(NO3) 26NH3, Tc=198 K and D≃0.3 cm-1. Hysteresis in Tc was also observed for all salts. Copyright © 1975 American Institute of Physics.2115211

Hyperthyroidism related to McCune-Albright syndrome: report of two cases and review of the literature

INTRODUCTION: McCune-Albright syndrome is a sporadic disease clinicaly characterized by polyostotic fibrous dysplasia, café-au-lait cutaneous spots and hyperfunctional endocrinopathies, such as precocious puberty, hyperthyroidism, acromegaly and others. The biologic physiopathology of the disease is based on an activating mutation of the gene for the Gs protein which mediates the activation of adenyl cyclase and subsequent gland autonomous secretion. The thyroid gland is usually involved in this disease, being hyperthyroidism the second most common endocrinopathy seen after precocious puberty. OBJECTIVE: Revision of the literature since 1937 to 1997, adding our casuistic and discussing the adequate treatment for the hyperthyroidism in the syndrome. RESULTS: Among 85 cases identified with the syndrome, hyperthyroidism treatment was described in 26 of them. Fifteen were submitted to surgery (total thyroidectomy), 6 were submitted to iodotherapy and 5 were treated with antithyroid drugs (ATD - propylthiouracil, carbimazole or methimazole). In some cases, treatment association was done. CONCLUSION: McCune-Albright syndrome is a rare disease, combining polyostotic fibrous dysplasia, café-au-lait cutaneous spots and hyperfunctional endocrinopathies. Cases with hyperthyroidism are treated iniatially clinically, but definitive ablation with surgery or radioiodine treatment is the most indicated option.INTRODUÇÃO: A síndrome de McCune Albright é uma doença rara, clinicamente definida pela combinação de displasia fibrosa poliostótica, manchas café-com-leite e endocrinopatias com hiperfunção, como puberdade precoce, hipertireoidismo, acromegalia e outras. A fisiopatologia biomolecular baseia-se em uma mutação ativadora do gene para a subunidade alfa da proteína de membrana Gs, que estimula a produção intracelular de AMPc, conferindo secreção autônoma à glândula em particular. A glândula tireóide é freqüentemente envolvida nesta doença, sendo o hipertireoidismo a segunda endocrinopatia mais comum após a puberdade precoce. OBJETIVO: Realizar uma revisão da literatura no período de 1937 a 1997, incluindo nossa casuística, e discutir o tratamento utilizado para o hipertireoidismo nesta síndrome. RESULTADOS: Do total de 85 casos, em 26 com hipertireoidismo se descreve o tipo de tratamento utilizado. Entre esses, 15 foram submetidos à cirurgia (tireoidectomia total), seis foram submetidos à iodoterapia e cinco foram submetidos a tratamento com drogas antitireoidianas (DAT - propiltiuracil, carbimazol ou metimazol), pois em alguns houve associação dos tratamentos citados anteriormente. CONCLUSÃO: A síndrome de McCune-Albright é uma doença rara, que inclui displasia fibrosa poliostótica, manchas café-com-leite e endocrinopatias com hiperfunção. Os casos acompanhados com hipertireoidismo são inicialmente tratados clinicamente com DAT, porém a ablação cirúrgica ou com radioiodoterapia é a opção definitiva mais indicada.Universidade Federal de São Paulo (UNIFESP) Departamento de Otorrinolaringologia e Cirurgia de Cabeça e PescoçoUNIFESP, Depto. de Otorrinolaringologia e Cirurgia de Cabeça e PescoçoSciEL

Coupled down-regulation of mTOR and telomerase activity during fluorouracil-induced apoptosis of hepatocarcinoma Cells

<p>Abstract</p> <p>Background</p> <p>Hepatocellular carcinoma (HCC) is the most invasive and frequently diagnosed malignancy and the second leading cause of cancer death in many regions of Asia. The PI3K/Akt/mTOR signal pathway is involved in multiple cellular functions including proliferation, differentiation, tumorigenesis, and apoptosis. Up-regulation of telomerase activity is thought to be a critical step leading to cell transformation.</p> <p>Methods</p> <p>This study investigated changes in mTOR pathway and telomerase activity in hepatocarcinoma cell line SMMC-7721 treated with chemotherapeutic agent 5-fluorouracil (5-Fu). We detected apoptosis of hepatocarcinoma cells by TUNEL assay. Telomerase activity, hTERT transcription level and p- p70 S6k was demonstrated by the telomeric repeat amplification protocol and silver staining assay, Dual-Luciferase Reporter Assay and Western blot analysis respectively.</p> <p>Results</p> <p>Treating SMMC-7721 cells with 5-Fu leads to apoptosis of the cells, and reduction in telomerase activity, as well as a dramatic reduction in the activated form of p70 S6 kinase, a mTOR substrate. The 5-Fu treatment nearly abolishes transcription of hTERT (the major component of telomerase) mRNA. Treating SMMC-7721 cells with Rapamycin, a specific mTOR inhibitor, significantly reduce hTERT protein level but did not affect hTERT transcription. 5-Fu and rapamycin were synergistic in regards to down-regulation of telomerase activity in hepatocarcinoma cells.</p> <p>Conclusion</p> <p>These results suggest that chemotherapeutic agent 5-Fu may down-regulate telomerase activity at both transcriptional level and PI3K/Akt/mTOR pathway-dependent post-transcriptional level to facilitate hepatocellular carcinoma cell apoptosis.</p

Canine and human gastrointestinal stromal tumors display similar mutations in c-KIT exon 11

<p>Abstract</p> <p>Background</p> <p>Gastrointestinal stromal tumors (GISTs) are common mesenchymal neoplasms in the gastrointestinal tract of humans and dogs. Little is known about the pathogenesis of these tumors. This study evaluated the role of <it>c-KIT </it>in canine GISTs; specifically, we investigated activating mutations in exons 8, 9, 11, 13, and 17 of <it>c-KIT </it>and exons 12, 14, and 18 of platelet-derived growth factor receptor, alpha polypeptide (<it>PDGFRA</it>), all of which have been implicated in human GISTs.</p> <p>Methods</p> <p>Seventeen canine GISTs all confirmed to be positive for KIT immunostaining were studied. Exons 8, 9, 11, 13 and 17 of <it>c-KIT </it>and exons 12, 14, and 18 of <it>PDGFRA</it>, were amplified from DNA isolated from formalin-fixed paraffin-embedded samples.</p> <p>Results</p> <p>Of these seventeen cases, six amplicons of exon 11 of <it>c-KIT </it>showed aberrant bands on gel electrophoresis. Sequencing of these amplicons revealed heterozygous in-frame deletions in six cases. The mutations include two different but overlapping six base pair deletions. Exons 8, 9, 13, and 17 of <it>c-KIT </it>and exons 12, 14, and 18 of <it>PDGFRA </it>had no abnormalities detected by electrophoresis and sequencing did not reveal any mutations, other than synonymous single nucleotide polymorphisms (SNPs) found in exon 11 of <it>c-KIT </it>and exons 12 and 14 of <it>PDGFRA</it>.</p> <p>Conclusions</p> <p>The deletion mutations detected in canine GISTs are similar to those previously found in the juxtamembrane domain of <it>c-KIT </it>in canine cutaneous mast cell tumors in our laboratory as well as to those reported in human GISTs. Interestingly, none of the other <it>c-KIT </it>or <it>PDGFRA </it>exons showed any abnormalities in our cases. This finding underlines the critical importance of <it>c-KIT </it>in the pathophysiology of canine GISTs. The expression of KIT and the identification of these activating mutations in <it>c-KIT </it>implicate KIT in the pathogenesis of these tumors. Our results indicate that mutations in <it>c-KIT </it>may be of prognostic significance and that targeting KIT may be a rational approach to treatment of these malignant tumors. This study further demonstrates that spontaneously occurring canine GISTs share molecular features with human GISTs and are an appropriate model for human GISTs.</p

OAZ-t/OAZ3 Is Essential for Rigid Connection of Sperm Tails to Heads in Mouse

Polyamines are known to play important roles in the proliferation and differentiation of many types of cells. Although considerable amounts of polyamines are synthesized and stored in the testes, their roles remain unknown. Ornithine decarboxylase antizymes (OAZs) control the intracellular concentration of polyamines in a feedback manner. OAZ1 and OAZ2 are expressed ubiquitously, whereas OAZ-t/OAZ3 is expressed specifically in germline cells during spermiogenesis. OAZ-t reportedly binds to ornithine decarboxylase (ODC) and inactivates ODC activity. In a prior study, polyamines were capable of inducing a frameshift at the frameshift sequence of OAZ-t mRNA, resulting in the translation of OAZ-t. To investigate the physiological role of OAZ-t, we generated OAZ-t–disrupted mutant mice. Homozygous OAZ-t mutant males were infertile, although the polyamine concentrations of epididymides and testes were normal in these mice, and females were fertile. Sperm were successfully recovered from the epididymides of the mutant mice, but the heads and tails of the sperm cells were easily separated in culture medium during incubation. Results indicated that OAZ-t is essential for the formation of a rigid junction between the head and tail during spermatogenesis. The detached tails and heads were alive, and most of the headless tails showed straight forward movement. Although the tailless sperm failed to acrosome-react, the heads were capable of fertilizing eggs via intracytoplasmic sperm injection. OAZ-t likely plays a key role in haploid germ cell differentiation via the local concentration of polyamines

A Phosphatidylinositol 3-Kinase/Protein Kinase B-independent Activation of Mammalian Target of Rapamycin Signaling Is Sufficient to Induce Skeletal Muscle Hypertrophy

Overexpression of Rheb activates mTOR signaling via a PI3K/PKB-independent mechanism and is sufficient to induce skeletal muscle hypertrophy. The hypertrophic effects of Rheb are driven through a rapamycin-sensitive (RS) mechanism, mTOR is the RS element that confers the hypertrophy and the kinase activity of mTOR is necessary for this event