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1.
Cancer Chemother Pharmacol ; 80(1): 45-53, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28508095

RESUMO

PURPOSE: Carboplatin clearance is correlated with glomerular filtration rate (GFR) and usually estimated with creatinine clearance using Cockcroft-Gault (CG) formula. Because plasma creatinine level is highly correlated with muscle mass, we hypothesized that an abnormal body composition with a low lean body mass (LBM) percentage [(LBM/weight) × 100] may result in inadequate carboplatin dosing. Serum cystatin C is an alternative marker of GFR, not affected by muscle mass. We aimed to investigate the influence of total LBM and LBM percentage on GFR calculation, using creatinine (CrCl) or cystatin C (GFRcysC-creat) in cancer patients. METHODS: Pretreatment serum creatinine and cystatin C were prospectively measured in consecutive patients. CrCl (CG formula), GFRcysC-creat (CKD-EPI creatinine-cystatin equation), and LBM (CT scan) were calculated. Severe thrombocytopenia post-carboplatin were analyzed. RESULTS: In 131 patients without renal insufficiency, LBM was correlated with creatinine (r = 0.30, p < 0.005) but not with cystatin C (r = -0.07, p = 0.43). In patients with the lowest LBM percentage, the CrCl was significantly higher than GFRcysC-creat indicating an overestimation of GFR with creatinine (p = 0.0004). In 24 patients treated with carboplatin AUC 5 (mg/ml min) ± paclitaxel, the risk of severe thrombocytopenia was associated with lower LBM percentage (p = 0.0002) and higher CrCl/GFRcysC-creat ratio (p = 0.006). By ROC analysis, the CrCl/GFRcysC-creat ratio threshold predicting severe thrombocytopenia was 1.23. CONCLUSIONS: A low LBM percentage increases the risk of inadequate GFR calculation by CG formula, and carboplatin overdosage with severe thrombocytopenia. High CrCl/GFRcysC-creat ratio allows the identification of these patients.


Assuntos
Antineoplásicos/administração & dosagem , Composição Corporal/fisiologia , Carboplatina/administração & dosagem , Taxa de Filtração Glomerular , Neoplasias/tratamento farmacológico , Idoso , Antineoplásicos/efeitos adversos , Antineoplásicos/farmacocinética , Área Sob a Curva , Carboplatina/efeitos adversos , Carboplatina/farmacocinética , Creatinina/sangue , Cistatina C/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/patologia , Paclitaxel/administração & dosagem , Estudos Prospectivos , Trombocitopenia/induzido quimicamente , Trombocitopenia/epidemiologia
2.
Invest New Drugs ; 33(1): 257-68, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25344452

RESUMO

INTRODUCTION: Sunitinib is a multikinase inhibitor active in various cancers types including renal cancers and endocrine tumors. The study analyzed the influence of the lean body mass (LBM) and of pharmacogenetic variants on the exposure to sunitinib and its active metabolite, SU12662, and on sunitinib toxicity and clinical activity. MATERIALS AND METHODS: Exposure to sunitinib and SU12662 was assessed on days 10 and 21 during the first treatment cycle. Acute toxicity was graded using the NCI 4.0 CTCAE ver. 4.0. The LBM and 14 common single nucleotide polymorphisms in the CYP3A4/3A5, NR1I2, NR1I3, ABCB1, and ABCG2 genes were analyzed according to the drug exposure at day 10. Determinants (including sunitinib exposure and pharmacogenetic variants) for toxicities were assessed, as well as the relationship between drug exposure and survival in renal cancer patients. RESULTS: Ninety-two patients (60 % with renal cancer) were assessable for pharmacokinetics, toxicity and survival, and 66 for genetic analysis. The LBM (p < 0.0001) and a polymorphism in the ABCG2 transporter (421C>A) (p = 0.014) were two independent parameters accounting for the variability of composite (sunitinib + SU12662) exposure. Advanced age (OR = 1.47 [1.01-2.15], p = 0.048) and high sunitinib exposure (OR = 1.16 [1.05-1.28], p = 0.005) were independently associated with any grade ≥ 3 acute toxicity, and high SU12662 exposure was associated with grade ≥ 2 thrombocytopenia (OR = 1.27 [1.03-1.57], p = 0.028). A high composite area under the curve (AUC) >1,973 ng/mL∙h at day 21 was associated with a doubled survival (35.2 vs 16.7 months; log-rank p = 0.0051) in renal cancer patients. CONCLUSIONS: This study indicates that LBM and drug monitoring may be helpful in the management of sunitinib-treated patients.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Inibidores da Angiogênese , Peso Corporal , Indóis , Proteínas de Neoplasias/genética , Neoplasias/tratamento farmacológico , Inibidores de Proteínas Quinases , Pirróis , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Idoso , Inibidores da Angiogênese/efeitos adversos , Inibidores da Angiogênese/farmacocinética , Inibidores da Angiogênese/uso terapêutico , Receptor Constitutivo de Androstano , Citocromo P-450 CYP3A/genética , Feminino , Humanos , Indóis/efeitos adversos , Indóis/sangue , Indóis/farmacocinética , Indóis/uso terapêutico , Masculino , Pessoa de Meia-Idade , Neoplasias/genética , Neoplasias/metabolismo , Farmacogenética , Polimorfismo Genético , Inibidores de Proteínas Quinases/efeitos adversos , Inibidores de Proteínas Quinases/farmacocinética , Inibidores de Proteínas Quinases/uso terapêutico , Pirróis/efeitos adversos , Pirróis/sangue , Pirróis/farmacocinética , Pirróis/uso terapêutico , Receptores de Esteroides/genética , Sunitinibe , Resultado do Tratamento
5.
Ann Oncol ; 23(1): 200-205, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21427067

RESUMO

BACKGROUND: Oxaliplatin neurosensory toxicity is dose limiting and may present as acute symptoms and/or cumulative peripheral neuropathy. PATIENTS AND METHODS: From October 2005 to May 2008, patients with oxaliplatin-induced acute neurotoxicity were randomized into a double-blind study, to receive either venlafaxine 50 mg 1 h prior oxaliplatin infusion and venlafaxine extended release 37.5 mg b.i.d. from day 2 to day 11 or placebo. Neurotoxicity was evaluated using numeric rating scale (NRS) for pain intensity and experienced relief under treatment, the Neuropathic Pain Symptom Inventory and the oxaliplatin-specific neurotoxicity scale. The primary end point was the percentage of patients with a 100% relief under treatment. RESULTS: Forty-eight patients were included (27 males, median age: 67.6 years). Most patients had colorectal cancer (72.9%). Median number of cycles administered at inclusion was 4.5 (mean cumulative oxaliplatin dose: 684.6 mg). Twenty out of 24 patients in arm A (venlafaxine) and 22 out of 24 patients in arm B (placebo) were assessable for neurotoxicity. Based on the NRS, full relief was more frequent in the venlafaxine arm: 31.3% versus 5.3% (P=0.03). Venlafaxine side-effects included grade 1-2 nausea (43.1%) and asthenia (39.2%) without grade 3-4 events. CONCLUSION: Venlafaxine has clinical activity against oxaliplatin-induced acute neurosensory toxicity.


Assuntos
Antineoplásicos/efeitos adversos , Cicloexanóis/uso terapêutico , Síndromes Neurotóxicas/prevenção & controle , Compostos Organoplatínicos/efeitos adversos , Inibidores Seletivos de Recaptação de Serotonina/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Colorretais/tratamento farmacológico , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oxaliplatina , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/prevenção & controle , Cloridrato de Venlafaxina
6.
Bull Cancer ; 96(10): 951-60, 2009 Oct.
Artigo em Francês | MEDLINE | ID: mdl-19734117

RESUMO

For the past two decades, significant developments have been made in supportive care for the management of chemotherapy-induced nausea and vomiting (CINV). A better understanding of the pathophysiology of vomiting and the introduction of two new classes of antiemetic agents with a high therapeutic index (serotonin type 3 receptor antagonists [anti-5HT3 or setrons] in the 1990s and neurokinin type 1 receptor antagonists [anti-NK1] in 2000), possibly combined with corticosteroids, have helped to improve the management of this distressing side effect, constantly feared by patients. It is essential to distinguish between the anticipatory, acute (first 24 hours) and delayed phases of CINV, to take into account the emetogenic potential of the different chemotherapy protocols (very low, low, moderate and high) together with individual risk factors. The authors would like to propose methodological and therapeutic recommendations for the primary and secondary prophylaxis of the acute and delayed phases of CINV, based on recent publications by international learned societies.


Assuntos
Antieméticos/uso terapêutico , Antineoplásicos/efeitos adversos , Náusea/prevenção & controle , Guias de Prática Clínica como Assunto , Vômito/prevenção & controle , Corticosteroides/uso terapêutico , Antieméticos/efeitos adversos , Antieméticos/classificação , Antineoplásicos/classificação , Humanos , Náusea/induzido quimicamente , Náusea/tratamento farmacológico , Antagonistas dos Receptores de Neurocinina-1 , Qualidade de Vida , Fatores de Risco , Antagonistas do Receptor 5-HT3 de Serotonina , Sociedades Médicas/normas , Vômito/induzido quimicamente , Vômito/tratamento farmacológico
7.
Ann Oncol ; 20(4): 736-40, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19223573

RESUMO

BACKGROUND: Glutathione-S-transferases (GST) regulate the cellular response to oxidative stress. We previously highlighted the importance of oxidative stress in taxane toxicity and therefore investigated the relationship between the GST isoforms M1, T1 and P1 gene polymorphisms and docetaxel (Taxotere)-induced peripheral neuropathy (DIPN). PATIENTS AND METHODS: The GSTM1 (null), GSTT1 (null) and GSTP1 (Ile(105)Val and Ala(114)Val) polymorphisms were determined in a cohort of cancer patients treated with docetaxel and entered in a clinical trial database. The relationship between GST polymorphisms and grade > or = 2 DIPN as primary end point was studied. RESULTS: Fifty-eight patients (median age 61 years) received a total of 261 cycles of docetaxel given as single agent. Patients with GSTP1 (105)Ile/(105)Ile genotype had a higher risk of developing a grade > or = 2 DIPN than did those with other GSTP1 genotypes (8 of 27 versus 2 of 31, respectively, odds ratio 6.11; 95% confidence interval 1.17-31.94; P = 0.03). In multivariate analysis, grade > or = 2 DIPN was strongly correlated with GSTP1 (105)Ile/(105)Ile genotype (P = 0.01) and the number of cycles (P = 0.03). CONCLUSION: We found a significant correlation between GSTP1 (105)Ile/(105)Ile genotype and the development of grade > or = 2 DIPN. This finding strongly suggests a role of oxidative stress in the pathophysiology of DIPN.


Assuntos
Antineoplásicos Fitogênicos/efeitos adversos , Glutationa Transferase/genética , Isoleucina/genética , Estresse Oxidativo , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Polimorfismo Genético , Taxoides/efeitos adversos , Valina/genética , Idoso , Docetaxel , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
9.
Med Trop (Mars) ; 60(3): 278-80, 2000.
Artigo em Francês | MEDLINE | ID: mdl-11258064

RESUMO

Dengue is prevalent in all subtropical areas. Hemorrhagic forms of the disease were first described in southeast Asia but have now been observed on several continents. Travelers are at risk for infection and the likelihood of imported dengue has grown in relation to volume of air traffic. In developed countries, dengue usually presents in the benign form, but sudden aggravation is always possible. The purpose of this report is to describe a case of imported dengue hemorrhagic fever associated with abdominal pain in a traveler returning from Asia. Radiological findings were suggestive of nonlithiasic cholecystitis. Similar ultrasound feature have been reported by pediatric groups during dengue outbreaks in Asia. Previous findings have shown that bladder involvement is a predictive sign of severe disease and impending shock. Surgery is contraindicated in these patients. Close clinical and laboratory surveillance is necessary due to the high risk of aggravation. The pathogenesis of this severe life-threatening form of the disease is unclear. A possible explanation is involvement of a more virulent strain of virus. Dengue should always be considered after malaria in the differential diagnosis of returning travelers patients presenting fever.


Assuntos
Colecistite , Dengue Grave/diagnóstico , Dor Abdominal , Doença Aguda , Adulto , Ásia , Diagnóstico Diferencial , França , Humanos , Masculino , Viagem
10.
J Virol ; 71(1): 307-13, 1997 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8985351

RESUMO

High simian immunodeficiency virus (SIV) seroprevalence rates have been reported in the different African green monkey (AGM) subspecies. Genetic diversity of these viruses far exceeds the diversity observed in the other lentivirus-infected human and nonhuman primates and is thought to reflect ancient introduction of SIV in the AGM population. We investigate here genetic diversity of SIVagm in wild-living AGM populations from the same geographical locale (i.e., sympatric population) in Senegal. For 11 new strains, we PCR amplified and sequenced two regions of the genome spanning the first tat exon and part of the transmembrane glycoprotein. Phylogenetic analysis of these sequences shows that viruses found in sympatric populations cluster into distinct lineages, with at least two distinct genotypes in each troop. These data strongly suggest an ancient introduction of these divergent viruses in the AGM population.


Assuntos
DNA Viral/análise , Variação Genética , Vírus da Imunodeficiência Símia/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Chlorocebus aethiops , Evolução Molecular , Produtos do Gene env/genética , Genes rev , Genes tat , Genótipo , Humanos , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Proteínas Oncogênicas de Retroviridae/genética , Homologia de Sequência de Aminoácidos , Vírus da Imunodeficiência Símia/classificação , Proteínas Virais de Fusão/genética
11.
J Virol ; 69(11): 7349-53, 1995 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-7474168

RESUMO

The high seroprevalence of simian immunodeficiency viruses (SIVs) in African green monkeys (AGMs) without immunological defects in their natural hosts has prompted consideration of SIV-infected AGMs as a model of apathogenic SIV infection. Study of the molecular mechanisms of SIVagm asymptomatic infection could thus provide clues for understanding the pathogenesis of human immunodeficiency viruses. Regulatory genes could be candidates for genetic control of SIVagm apathogenicity. We have characterized Vpr, Tat, Rev, and Nef genes of two SIVagm strains isolated from naturally infected sabaeus monkeys captured in Senegal. The results provide further evidence that SIVagm from West African green monkeys is the most divergent class of AGM viruses, with structural features in long terminal repeat sequences and Vpr and Tat genes that distinguish them from viruses isolated from other AGM species (vervet, grivet, and tantalus monkeys).


Assuntos
Chlorocebus aethiops/virologia , Genes Reguladores , Genes Virais , Filogenia , Vírus da Imunodeficiência Símia/genética , África Ocidental , Sequência de Aminoácidos , Animais , Éxons , Produtos do Gene nef/química , Produtos do Gene nef/genética , Produtos do Gene tat/química , Produtos do Gene tat/genética , Produtos do Gene vpr/química , Produtos do Gene vpr/genética , HIV/patogenicidade , Humanos , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Vírus da Imunodeficiência Símia/isolamento & purificação , Vírus da Imunodeficiência Símia/patogenicidade , Produtos do Gene nef do Vírus da Imunodeficiência Humana , Produtos do Gene tat do Vírus da Imunodeficiência Humana , Produtos do Gene vpr do Vírus da Imunodeficiência Humana
14.
Virology ; 198(1): 297-310, 1994 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8259665

RESUMO

A study of simian T-cell lymphoma/leukemia virus infection, conducted on 747 nonhuman primates belonging to 14 different species in Central and Western Africa, indicated that 4 species (Cercopithecus aethiops, Erythrocebus patas, Papio doguera, and Cercopithecus mona pogonias) had a high prevalence of seropositivity to simian T-cell lymphoma/leukemia virus type I (STLV-I). The other nonhuman primate species, however, had negative or low levels of anti-HTLV-I antibodies. STLV-I pol and env DNA was detected in 12 of 12 different animals among the seropositive species. However, STLV-I pX DNA could be detected in only 10 of 12 animals. Comparative phylogenetic analyses based on 140 bp sequence of the pol gene indicate that these STLV-I isolates were 0-9% divergent from each other and were 3.5-7% divergent from the prototype related human retrovirus HTLV-I (ATK). The West African STLV-I isolates formed a unique phylogenetic cluster as did most of the Central African STLV-I isolates, save for STLV-I (Tan 90). The phylogenetic data indicate that cross species transmission of HTLV-I and STLV-I continued to occur long after their ancestral strain separated from the progenitor to HTLV-II. Comparative amino acid analyses indicated that there was marked conservation of the TAX protein regardless of host species, while the pol and REX proteins exhibited increasing levels of diversity.


Assuntos
Infecções por HTLV-I/epidemiologia , Haplorrinos/microbiologia , Doenças dos Macacos/epidemiologia , Vírus Linfotrópico T Tipo 1 de Símios/classificação , África Central/epidemiologia , África Ocidental/epidemiologia , Sequência de Aminoácidos , Animais , Animais Selvagens/microbiologia , Sequência de Bases , Cercopithecus/microbiologia , Clonagem Molecular , Erythrocebus patas/microbiologia , Infecções por HTLV-I/sangue , Infecções por HTLV-I/veterinária , Dados de Sequência Molecular , Doenças dos Macacos/sangue , Papio/microbiologia , Filogenia , Análise de Sequência de DNA , Homologia de Sequência , Vírus Linfotrópico T Tipo 1 de Símios/genética , Vírus Linfotrópico T Tipo 1 de Símios/imunologia
15.
Virology ; 192(1): 312-20, 1993 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8390757

RESUMO

Simian T-cell leukemia virus (STLV-I) is an oncovirus highly related to human T-cell leukemia virus type I (HTLV-I). To further examine the extent of variability, dissemination patterns, phylogeny, and evolution of these viruses, we analyzed a new STLV-I variant from a naturally infected Cercopithecus aethiops var. tantalus from the Central African Republic. Sequence analyses of its LTR, gag, pol, env, and pX (OrfII) genes indicated that this isolate, STLV-I (Tan 90), is 6% divergent from the prototype HTLV-I (ATK) and is the most divergent African STLV-I characterized to date. Our phylogenetic data indicate that southeast Asian and African STLV-I and HTLV-I strains segregated from each other thousands of years ago and that Japanese HTLV-I strains represent a relatively recent introduction of African or New World isolates. The data also indicate that interspecies transmission occurred several times on different continents over prolonged periods of time.


Assuntos
Cercopithecus/microbiologia , Vírus Linfotrópico T Tipo 1 de Símios/genética , África Central , Animais , Sequência de Bases , DNA Viral/genética , Vírus Linfotrópico T Tipo 1 Humano/genética , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Alinhamento de Sequência
16.
Ann Otolaryngol Chir Cervicofac ; 107(1): 21-5, 1990.
Artigo em Francês | MEDLINE | ID: mdl-2310123

RESUMO

Therapeutical fiberscopy permits ambulatory treatment of benign lesions of the nose and cavum with the use of a flexible endoscope on a patient in the sitting position. YAG gives access to the nasal fossa and, more particularly, to the cavum conchae where it is of the utmost value, since this area is normally inaccessible under local anesthesia. In the cavum, we have been able to treat primarily inflammatory lesions of the adenoids, bridles, cysts, and cases of epipharyngitis and tubal catarrh. In the nasal fossa, although the YAG method provides a means for resorbing hypertrophic conchae, it is of special values for the management of polyposis. The removal of polyps allows to withhold the utilization of adrenal corticosteroids; to delay surgery; or even to reoperate patients with early recurrences. Two ventilation middle meatotomy operations have also been performed. Results from this destructive but precise method are promising.


Assuntos
Terapia a Laser , Doenças Nasofaríngeas/cirurgia , Doenças Faríngeas/cirurgia , Adulto , Procedimentos Cirúrgicos Ambulatórios , Endoscopia , Tecnologia de Fibra Óptica , Humanos , Hipofaringe
17.
Cell Differ Dev ; 28(2): 135-44, 1989 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-2532948

RESUMO

In the perennibranchiate Proteus anguinus, larval myosin isoforms were shown to coexist for life with the adult isomyosins that appeared at the end of the larval stage. Analysis of the myofibrillar ATPase profile also revealed that a high percentage of immature fibers persisted in adults. A long-term treatment with large amounts of T3 had no effect on juvenile individuals. Applied to subadult animals it promoted a regression of larval myosin isoforms and a reduction in the percentage of immature fiber types. The regulative effect of T3 in the myosin isoenzymic transition may be delayed and depends on metabolic conditions, which suggests it is indirect.


Assuntos
Músculos/enzimologia , Miosinas/metabolismo , Proteínas/metabolismo , Glândula Tireoide/metabolismo , Urodelos/metabolismo , Animais , Diferenciação Celular , Hipotireoidismo/metabolismo , Músculos/citologia , Miosinas/análise , Hormônios Tireóideos/farmacologia
18.
Artigo em Inglês | MEDLINE | ID: mdl-2754613

RESUMO

Between 1987 and 1988, a survey to determine the distribution of HTLV-I infection was conducted in a representative population of adults, living in southern Chad, Cameroon, and Equatorial Guinea. Populations studied were selected by the cluster sampling technique. Sera were tested for IgG antibodies to HTLV-I by ELISA. ELISA-positive sera were retested by Western blot. The study comprised 2,301 adults, all apparently healthy. Crude prevalence rates range from 0.5 to 11.8%. We found three clearly different areas of HTLV-I seroprevalence rates. An area of low seropositivity in southern Chad and northern Cameroon (0.5-2.0%), an area of moderate seropositivity in the savannah region of Ngaoundere, Cameroon (4.2%) and in Bata, Equatorial Guinea (6.5%), and lastly an area of high seropositivity (8.6-11.8%) in the equatorial forest area of Equatorial Guinea and southern Cameroon. HTLV-I seroprevalence rates increased with age up to 12.6% after 40 years old in the areas of high seropositivity. There was no difference between male and female age-adjusted prevalence rates in all of the areas studied.


Assuntos
Infecções por HTLV-I/epidemiologia , Adolescente , Adulto , Western Blotting , Camarões , Chade , Ensaio de Imunoadsorção Enzimática , Feminino , Guiné-Bissau , Anticorpos Anti-HTLV-I/análise , Infecções por HTLV-I/sangue , Humanos , Imunoglobulina G/análise , Masculino , Distribuição Aleatória , População Rural , População Urbana
19.
Bull Soc Pathol Exot Filiales ; 81(1): 15-23, 1988.
Artigo em Francês | MEDLINE | ID: mdl-2841043

RESUMO

An epidemiological study of 66 cases of Burkitt's lymphoma, a census taken between 1980 and 1986 permitted us to ascertain that, in Cameroon, this disease does not only affect children under the age of 15 years, and that the distribution is almost the same in both sexes. Geographically, the littoral and the western region are more affected than the rest of the country. Clinically although the maxillo-facial localisations are not negligible (29.6%), the abdomen involvement is more common (50%; particularly ovary in women). The clinical aspects met are fairly often advanced or generalized cases.


Assuntos
Linfoma de Burkitt/epidemiologia , Adolescente , Adulto , Anticorpos Antivirais/análise , Linfoma de Burkitt/imunologia , Linfoma de Burkitt/patologia , Camarões , Criança , Pré-Escolar , Feminino , Herpesvirus Humano 4/imunologia , Humanos , Masculino
20.
Reprod Nutr Dev (1980) ; 28(3B): 721-31, 1988.
Artigo em Francês | MEDLINE | ID: mdl-2973102

RESUMO

In the urodelan amphibian Pleurodeles waltlii, spontaneous external metamorphosis was correlated with an increase in the serum level of thyroxine (T4). Within the same period, a change occurred in the myofibrillar ATPase profile of the dorsal skeletal muscle; fibres of larval type were gradually replaced by transitional fibres (type IIC), then by adult fibres of the types I, IIA, and IIB. Likewise, a myosin isoenzymic transition was observed. In larval animals, myosin electrophoresis revealed 3 bands corresponding with isoforms having identical heavy chains (MHC), but different light chains (MLC). In the course of metamorphosis, the 3 larval isomyosins were replaced by 3 isoforms having the adult type MHC and different motility. In a related neotenic species, Ambystoma mexicanum, no spontaneous anatomic metamorphosis occurred; at the time it should theoretically take place, the serum T4 level remained low. The ATPase profile was modified, but transitional fibres that replaced the initial larval types appeared to be persistent, and adult fiber types appeared only in a small amount. Myosin isoenzymic transition was also incomplete, larval isoforms were still distinguished in the neotenic adults. Similar persistence of larval characters was observed in adult Proteus anguinus, a perennibranch that never undergoes anatomical metamorphosis. Experimental hypothyroidian Pleurodeles waltlii displayed no external metamorphosis, only the larval fibre types and isomyosins were detected in those animals. External metamorphosis was induced in Ambystoma mexicanum by a triiodothyronine treatment. A complete myosin isoenzymic transition was observed in metamorphosed animals. These results tend to indicate that a moderate increase in the level of thyroid hormones is sufficient to determine the production of the adult type MHC molecules and the differentiation of the corresponding myofibrillar types in the skeletal dorsal muscle of amphibians, while a marked increase would be necessary for repressing the initial larval feature.


Assuntos
Ambystoma mexicanum/crescimento & desenvolvimento , Ambystoma/crescimento & desenvolvimento , Desenvolvimento Muscular , Pleurodeles/crescimento & desenvolvimento , Salamandridae/crescimento & desenvolvimento , Hormônios Tireóideos/fisiologia , Animais , Diferenciação Celular , Isoenzimas/metabolismo , Metamorfose Biológica , Miosinas/metabolismo , Tiroxina/sangue
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