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1.
Clin Endocrinol (Oxf) ; 100(6): 595-601, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38226504

RESUMO

INTRODUCTION: Hyponatraemia is the most common electrolyte disorder in inpatients resulting mainly from an imbalance in water homeostasis. Intravascular fluid status assessment is pivotal but is often challenging given multimorbidity, polypharmacy and diuretics use. We evaluated the utility of point-of-care ultrasound (POCUS) as an adjunct tool to standard practice for fluid assessment in severe hyponatraemia patients. METHODS: Patients presenting with severe hyponatremia (Serum Sodium [Na] < 120 mmol/L; Normal range: 135-145 mol/L), managed by standard care were included. Hyponatraemia biochemistry work-up and POCUS examination were undertaken. Both clinician and POCUS independently assigned one of the three fluid status groups of hypovolaemia, hypervolaemia or euvolaemia. The final diagnosis of three fluid status groups at admission was made at the time of discharge by retrospective case review. Clinician's (standard of care) and POCUS fluid assessments were compared to that of the final diagnosis at the time of discharge. RESULTS: n = 19 patients were included. Median Na on admission was 113 mmol/L (109-116), improved to 129 ± 3 mmol/L on discharge. POCUS showed the higher degree of agreement with the final diagnosis (84%; n = 16/19), followed by the clinician (63%; n = 12/19). A trend towards higher accuracy of POCUS compared to clinician assessment of fluid status was noted (84% vs. 63%, p = 0.1611). Biochemistry was unreliable in 58% (n = 11/19) likely due to renal failure, polypharmacy or diuretic use. Inappropriate emergency fluid management was undertaken in 37% (n = 7/19) of cases based on initial clinician assessment. Thirst symptom correlated to hypovolaemia in 80% (4/5) cases. CONCLUSION: As subjective clinical and biochemistry assessments of fluid status are often unreliable due to co-morbidities and concurrent use of medications, POCUS can be a rapid objective diagnostic tool to assess fluid status in patients with severe hyponatraemia, to guide accurate emergency fluid management.


Assuntos
Hiponatremia , Sistemas Automatizados de Assistência Junto ao Leito , Ultrassonografia , Humanos , Hiponatremia/diagnóstico por imagem , Feminino , Masculino , Ultrassonografia/métodos , Idoso , Idoso de 80 Anos ou mais , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto
2.
Vavilovskii Zhurnal Genet Selektsii ; 27(2): 146-152, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37063518

RESUMO

Earthworms are an important ecological group that has a significant impact on soil fauna as well as plant communities. Despite their importance, genetic diversity and phylogeny of earthworms are still insufficiently studied. Most studies on earthworm genetic diversity are currently based on a few mitochondrial and nuclear genes. Mitochondrial genomes are becoming a promising target for phylogeny reconstruction in earthworms. However, most studies on earthworm mitochondrial genomes were made on West European and East Asian species, with much less sampling from other regions. In this study, we performed sequencing, assembly, and analysis of the mitochondrial genome of Dendrobaena tellermanica Perel, 1966 from the Northern Caucasus. This species was earlier included into D. schmidti (Michaelsen, 1907), a polytypic species with many subspecies. The genome was assembled as a single contig 15,298 bp long which contained a typical gene set: 13 protein-coding genes (three subunits of cytochrome c oxidase, seven subunits of NADH dehydrogenase, two subunits of ATP synthetase, and cytochrome b), 12S and 16S ribosomal RNA genes, and 22 tRNA genes. All genes were located on one DNA strand. The assembled part of the control region, located between the tRNA-Arg and tRNA-His genes, was 727 bp long. The control region contained multiple hairpins, as well as tandem repeats of the AACGCTT monomer. Phylogenetic analysis based on the complete mitochondrial genomes indicated that the genus Dendrobaena occupied the basal position within Lumbricidae. D. tellermanica was a rather distant relative of the cosmopolitan D. octaedra, suggesting high genetic diversity in this genus. D. schmidti turned out to be paraphyletic with respect to D. tellermanica. Since D. schmidti is known to contain very high genetic diversity, these results may indicate that it may be split into several species.

3.
Physiol Res ; 68(6): 939-945, 2019 12 30.
Artigo em Inglês | MEDLINE | ID: mdl-31647300

RESUMO

To compare serum adiponectin changes across the menstrual cycle between normal weight and overweight/obese young women and its correlation with serum estradiol. Young women (n=56) with regular menstrual cycle had been grouped according to their BMI into normal weight group (n=26) and overweight /obese group (n=30). Blood samples were drawn during early follicular (FP), pre-ovulatory (OP) and luteal phases (LP) of menstrual cycle for serum adiponectin and estradiol levels determination using enzyme-linked immunosorbent assay. Adiponectin serum level showed a significant decreasing pattern across the phases of menstrual cycle in normal weight group. This pattern was absent in the overweight/obese group. In addition, serum adiponectin was lower in overweight/obese group compared to normal weight subjects through all phases of menstrual cycle. No correlation was found between adiponectin and estradiol levels in both groups. A significant variation of serum adiponectin level was detected across the menstrual cycle in females with normal weight. In comparison, overweight/obese group showed a relatively stable adiponectin level throughout the cycle. This lack of adiponectin variation might be added to the complex mechanisms lies behind obesity-related female infertility.


Assuntos
Adiponectina/sangue , Peso Corporal Ideal/fisiologia , Ciclo Menstrual/sangue , Sobrepeso/sangue , Adolescente , Adulto , Biomarcadores/sangue , Estudos de Coortes , Feminino , Humanos , Obesidade/sangue , Obesidade/diagnóstico , Sobrepeso/diagnóstico , Estudos Prospectivos , Adulto Jovem
4.
Physiol Res ; 67(5): 787-793, 2018 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-30044107

RESUMO

Present study aimed to explore the levels and correlation of oxidative stress biomarkers with anthropometry in a population of young Saudi females. One hundred six normotensives, non-diabetic Saudi females, with minimally active lifestyle, based on their body mass index (BMI) were divided as; normal-weight (NW; n=52), overweight (OW; n=24) and obese (OB; n=30). Anthropometric measurements [BMI, Waist Circumference (WC), Waist-Hip Ratio (WHR), Body Density (BD), Body Adiposity Index (BAI), % Body fat] and oxidative stress biomarkers; Thiobarbituric acid reactive substances (TBARS), 8-hydroxy-2-deoxyguanosine (8-OH-2dG: indicative of DNA/RNA damage), Superoxide dismutase, Serum total antioxidant capacity) were recorded. There was statistically significant higher 8-OH-2dG (pg/ml) in OB compared to NW (800.63+/-6.19 vs. 780.22+/-3.34; p=0.007), as determined by one-way ANOVA and Tukey post hoc test. 8-OH-2dG was significantly and positively associated with BMI (r=0.286, p=0.004), WC (r=0.280, p=0.005), BAI (r=0.26, p=0.008), and % body fat (r=0.27, p=0.006). There may be significantly increased DNA damage in normoglycemic, normotensive obese adolescent females. This can be linked to the amount of adipose tissue in the body as depicted by strong positive association between DNA damage and BMI, WC, BAI, and % body fat.


Assuntos
Antropometria , Antioxidantes/metabolismo , Obesidade/sangue , Oxidantes/sangue , Estresse Oxidativo/fisiologia , Circunferência da Cintura/fisiologia , Adiposidade/fisiologia , Antropometria/métodos , Estudos Transversais , Dano ao DNA/fisiologia , Feminino , Humanos , Obesidade/diagnóstico , Obesidade/epidemiologia , Arábia Saudita/epidemiologia , Relação Cintura-Quadril/métodos , Adulto Jovem
5.
Endocrinology ; 157(9): 3658-67, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27300765

RESUMO

TSH and thyroid hormones (T3 and T4) are intimately involved in bone biology. We have previously reported the presence of a murine TSH-ß splice variant (TSH-ßv) expressed specifically in bone marrow-derived macrophages and that exerted an osteoprotective effect by inducing osteoblastogenesis. To extend this observation and its relevance to human bone biology, we set out to identify and characterize a TSH-ß variant in human macrophages. Real-time PCR analyses using human TSH-ß-specific primers identified a 364-bp product in macrophages, bone marrow, and peripheral blood mononuclear cells that was sequence verified and was homologous to a human TSH-ßv previously reported. We then examined TSH-ßv regulation using the THP-1 human monocyte cell line matured into macrophages. After 4 days, 46.1% of the THP-1 cells expressed the macrophage markers CD-14 and macrophage colony-stimulating factor and exhibited typical morphological characteristics of macrophages. Real-time PCR analyses of these cells treated in a dose-dependent manner with T3 showed a 14-fold induction of human TSH-ßv mRNA and variant protein. Furthermore, these human TSH-ßv-positive cells, induced by T3 exposure, had categorized into both M1 and M2 macrophage phenotypes as evidenced by the expression of macrophage colony-stimulating factor for M1 and CCL-22 for M2. These data indicate that in hyperthyroidism, bone marrow resident macrophages have the potential to exert enhanced osteoprotective effects by oversecreting human TSH-ßv, which may exert its local osteoprotective role via osteoblast and osteoclast TSH receptors.


Assuntos
Osso e Ossos/metabolismo , Macrófagos/metabolismo , Tireotropina Subunidade beta/metabolismo , Tri-Iodotironina/metabolismo , Animais , Células CHO , Linhagem Celular , Cricetulus , Humanos , Masculino , Camundongos Endogâmicos C57BL , Isoformas de Proteínas
6.
Neth J Med ; 73(4): 175-8, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25968289

RESUMO

OBJECTIVE: A rise in oestrogen in the preovulatory phase produces a GnRH-induced luteinising hormone surge. Oestrogen receptors are not found on GnRH neurons but these are present on kisspeptin neurons. That led us to hypothesise that serum kisspeptin levels may vary during various phases of the menstrual cycle in relation to serum oestradiol. METHODS: Thirty female students, 18-25 years old, Saudi nationality, with a regular menstrual cycle, were recruited from various health colleges of the University of Dammam, Saudi Arabia. Three blood samples per volunteer were collected at three different times: the early follicular, preovulatory and luteal phase. Serum kisspeptin and oestradiol were measured using ELISA kits. Comparison between individual subjects during the various phases was done by one-way, repeated-measures ANOVA. To discover which specific means differed, Bonferroni post hoc test was applied. Pearsons correlation was used to find out the relationship. RESULTS: There was a statistically significant increase (p < 0.001) in serum kisspeptin levels from the early follicular to the preovulatory phase (264.11±28.42 vs. 472.46±17.82 nmol/l respectively), and from the preovulatory to the luteal phase (472.46±17.82 vs. 724.79±36.85 nmol/l respectively). Oestradiol levels also increased significantly (p = 0.006) from the early follicular to the preovulatory phase (45.85±5.34 vs. 79.07±7.45 pg/ml respectively), Pearsons correlation revealed a statistically insignificant correlation between kisspeptin and oestradiol in all three phases. CONCLUSION: Endogenous kisspeptin secretion seems to vary across the different phases of the menstrual cycle and is not related to serum oestradiol.


Assuntos
Estradiol/sangue , Fase Folicular/sangue , Kisspeptinas/sangue , Fase Luteal/sangue , Adolescente , Adulto , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Ciclo Menstrual/sangue , Adulto Jovem
7.
Bratisl Lek Listy ; 115(10): 632-4, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25573730

RESUMO

OBJECTIVE: The study was aimed to observe the effect of amlodipine on rat pituitary gonadotropins after amlodipine administration and withdrawal. METHODS: It was an experimental study done at Army Medical College, National University of Sciences and Technology, Islamabad, Pakistan from 2009-2010. Sixty adult male rats were divided into groups A and B. Each group was further subdivided into two subgroups of 15 rats each; A1 (control), A2 (control recovery), B1 (amlodipine-treated) and B2 (amlodipine recovery). Amlodipine, 0.04 mg/kg body weight daily for fifty days was given by means of gavage to groups B1 and B2. Groups A1 and A2 were given vehicle (0.5 ml distilled water). After 50 days, rats in groups A1 and B1 were sacrificed and their serum LH and FSH levels were measured by Enzyme Immunoassay method. Vehicle and amlodipine were withdrawn in groups A2 and B2, respectively, and the rats were left for recovery to take place for another fifty days. The above procedure was adopted for the measurement of LH and FSH levels in the recovered rats. RESULTS: Amlodipine administration for 50 days resulted in a significant rise in serum LH (p < 0.01) whereas serum FSH remained unchanged (p ≥ 0.05). Serum LH in amlodipine-treated rats returned to normal after amlodipine withdrawal (p ≥ 0.05). CONCLUSION: Amlodipine causes a reversible increase in serum LH but it has no effect on serum FSH (Fig. 2, Ref. 17).


Assuntos
Anlodipino/farmacologia , Bloqueadores dos Canais de Cálcio/farmacologia , Hormônio Foliculoestimulante/sangue , Hormônio Liberador de Gonadotropina/efeitos dos fármacos , Gonadotropinas Hipofisárias/metabolismo , Hormônio Luteinizante/sangue , Animais , Masculino , Ratos , Testículo/efeitos dos fármacos
8.
Endocrinology ; 154(12): 4919-26, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24140716

RESUMO

It is now firmly established that TSH may influence the physiology and patho-physiology of bone by activating osteoblasts and inhibiting osteoclast activity resulting in relative osteoprotection. Whether this influence is directly exerted by pituitary-derived TSH in vivo is less certain, because we have previously reported that the suppression of pituitary TSH does not remove such protection. Here, we have characterized the functional relevance of a novel form of the TSH-ß subunit, designated TSH-ßv, known to be produced by murine bone marrow cells. We found that fresh bone marrow-derived macrophages (MØs) preferentially produced TSH-ßv and, when cocultured with CHO cells engineered to overexpress the full-length TSH receptor, were able to generate the production of intracellular cAMP; a phenomenon not seen in control CHO cells, such results confirmed the bioactivity of the TSH variant. Furthermore, cocultures of MØs and osteoblasts were shown to enhance osteoblastogenesis, and this phenomenon was markedly reduced by antibody to TSH-ß, suggesting direct interaction between MØs and osteoblasts as observed under the electron microscope. These data suggest a new paradigm of local modulation of bone biology by a MØ-derived TSH-like molecule and raise the question of the relative contribution of local vs pituitary-derived TSH in osteoprotection.


Assuntos
Macrófagos/efeitos dos fármacos , Osteoblastos/metabolismo , Isoformas de Proteínas/farmacologia , Tireotropina Subunidade beta/metabolismo , Sequência de Aminoácidos , Animais , Células CHO , Técnicas de Cocultura , Cricetinae , Cricetulus , Macrófagos/fisiologia , Camundongos , Dados de Sequência Molecular , Conformação Proteica , Tireotropina Subunidade beta/genética
9.
Neth J Med ; 71(2): 63-8, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23462053

RESUMO

Chocolate/cocoa has been known for its good taste and proposed health effects for centuries. Earlier, chocolate used to be criticised for its fat content and its consumption was a sin rather than a remedy, associated with acne, caries, obesity, high blood pressure, coronary artery disease and diabetes. Therefore, many physicians tended to warn patients about the potential health hazards of consuming large amounts of chocolate. However, the recent discovery of biologically active phenolic compounds in cocoa has changed this perception and stimulated research on its effects in ageing, oxidative stress, blood pressure regulation, and atherosclerosis. Today, chocolate is lauded for its tremendous antioxidant potential. However, in many studies, contradictory results and concerns about methodological issues have made it hard for health professionals and the public to understand the available evidence on chocolate's effects on health. The purpose of this review is to interpret research done in the last decade on the benefits and risks of chocolate consumption.


Assuntos
Cacau , Nível de Saúde , Antioxidantes/farmacologia , Gorduras na Dieta/farmacologia , Flavonoides/farmacologia , Humanos , Polifenóis/farmacologia , Xantinas/farmacologia
11.
Endocrinology ; 148(7): 3164-75, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17412816

RESUMO

The TSH receptor (TSHR), a heptahelical G protein-coupled receptor on the surface of thyrocytes, is a major autoantigen and physiological regulator of the thyroid gland. Unlike other G protein-coupled receptors, the TSHR undergoes posttranslational cleavage of its ectodomain, leading to the existence of several forms of the receptor on the plasma membrane. We previously hypothesized that to achieve high fidelity and specificity of TSH ligand or TSHR autoantibody signaling, the TSHR may compartmentalize into microdomains within the plasma membrane. In support of this hypothesis we have shown previously that TSHRs reside in GM1 ganglioside-enriched lipid rafts in the plasma membrane of TSHR-expressing cells. In this study, we further explored the different forms of TSHRs that reside in lipid rafts. We studied both TSHR-transfected cells and rat thyrocytes, using both nondetergent biochemical analyses and receptor-lipid raft colocalization. Using the biochemical approach, we observed that monomeric receptors existed in both raft and nonraft fractions of the cell surface in the steady state. We also demonstrated that the multimeric forms of the receptor were preferentially partitioned into the lipid microdomains. Different TSHR forms, including multimers, were dynamically regulated both by receptor-specific and postreceptor-specific modulators. TSH ligand and TSHR antibody of the stimulating variety induced a decrease of multimeric forms in the raft fractions. In addition, multimeric and monomeric forms of the receptor were both associated with Gsalpha within and without the rafts. Although failure to achieve total lipid raft disruption prevented a conclusion regarding the relative power of TSHR signaling within and without the raft domains, these data showed clearly that not only were a significant proportion of TSHRs residing within lipid microdomains but that constitutive multimerization of TSHRs was actually regulated within the lipid rafts.


Assuntos
Microdomínios da Membrana/metabolismo , Receptores da Tireotropina/metabolismo , Animais , Células CHO , Centrifugação com Gradiente de Concentração , Colesterol/metabolismo , Colforsina/farmacologia , Cricetinae , Cricetulus , Dimerização , Proteínas de Ligação ao GTP/metabolismo , Imunoglobulinas Estimuladoras da Glândula Tireoide/farmacologia , Imunoprecipitação , Modelos Biológicos , Ligação Proteica/efeitos dos fármacos , Ratos , Receptores da Tireotropina/química , Receptores da Tireotropina/imunologia
12.
Pain ; 118(1-2): 194-200, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16202529

RESUMO

The expression and report of pain is influenced by social environment and culture. Previous studies have suggested ethnically determined differences in report of pain threshold, intensity and affect. The influence of ethnic differences between White British and South Asians has remained unexplored. Twenty age-matched, male volunteers in each group underwent evaluation. Cold and warm perception and cold and heat threshold were assessed using an ascending method of limits. Magnitude estimation of pain unpleasantness and pain intensity were investigated with thermal stimuli of 46, 47, 48 and 49 degrees C. Subjects also completed a pain anxiety questionnaire. Data was analysed using t-test, Mann-Whitney and repeated measures analysis of variance as appropriate. There were no differences in cold and warm perception between the two groups. There was a statistically significant difference between the two groups for heat pain threshold (P=0.006) and heat pain intensity demonstrated a significant effect for ethnicity (F=13.84, P=0.001). Although no group differences emerged for cold pain threshold and heat unpleasantness, South Asians demonstrated lower cold pain threshold and reported more unpleasantness at all temperatures but this was not statistically significant. Our study shows that ethnicity plays an important role in heat pain threshold and pain report, South Asian males demonstrated lower pain thresholds and higher pain report when compared with matched White British males. There were no differences in pain anxiety between the two groups and no correlations were identified between pain and pain anxiety Haemodynamic measures and anthropometry did not explain group differences.


Assuntos
Povo Asiático/estatística & dados numéricos , Temperatura Alta , Limiar da Dor/fisiologia , Sensação Térmica/fisiologia , População Branca/estatística & dados numéricos , Adulto , Antropometria , Ansiedade/diagnóstico , Ansiedade/psicologia , Temperatura Baixa , Comparação Transcultural , Hemodinâmica/fisiologia , Humanos , Masculino , Medição da Dor/estatística & dados numéricos , Limiar da Dor/etnologia , Fatores Sexuais , Inquéritos e Questionários
13.
Endocrinology ; 145(12): 5580-8, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15319351

RESUMO

The TSH receptor (TSHR) undergoes intramolecular cleavage of the ectodomain yielding a two-subunit structure on the cell surface. Subsequently, the TSHR ectodomains (the alpha- or A-subunits) are shed from the cell surface. In this study we first confirmed TSHR alpha-subunit shedding from tagged-TSHR transfected Chinese hamster ovary cells. We found that TSH exacerbated this phenomenon of TSHR subunit shedding. The 125I-TSH cross-linking technique has been suggested as useful in the assessment of dynamic changes in TSHR processing. In our hands this technique did not detect any enhancement of cleavage by TSH. However, we found that the cross-linking method had an inherent insensitivity for studying receptor dynamics as exhibited by its inability to detect even major degrees of TSHR down-regulation. We, therefore, used a cell-based, double-antibody, flow cytometric immunoassay to quantitate TSHR cleavage in real time. We then found that different lines of Chinese hamster ovary TSHR cells, when treated with TSH, showed a time- and dose-dependent increase in TSHR cleavage in addition to ectodomain shedding. We previously reported that monoclonal TSHR stimulating antibody (MS-1) did not always act like TSH. In particular, MS-1 did not enhance TSHR cleavage. However, when we used the Fab fragment of MS-1, we were able to induce cleavage in a similar time frame to TSH. These results suggested that the intact bivalent antibody immobilized the TSHRs in their multimeric state and inhibited intramolecular cleavage. In support of these observations, fluorescence recovery after photo bleaching measurements demonstrated a greater increase in TSHR mobility with MS-1 Fab fragments than with the intact MS-1 IgG. In conclusion, these data indicated that monomer formation from multimeric TSHRs might be an important requirement for TSHR cleavage and TSHR ectodomain shedding.


Assuntos
Receptores da Tireotropina/química , Receptores da Tireotropina/metabolismo , Animais , Anticorpos Monoclonais/metabolismo , Sítios de Ligação , Cricetinae , Reagentes de Ligações Cruzadas/metabolismo , Reagentes de Ligações Cruzadas/farmacologia , Citometria de Fluxo , Recuperação de Fluorescência Após Fotodegradação , Humanos , Fragmentos Fab das Imunoglobulinas/metabolismo , Radioisótopos do Iodo , Estrutura Terciária de Proteína , Receptores da Tireotropina/imunologia , Tireotropina/metabolismo , Tireotropina/farmacologia
14.
Endocrinology ; 144(11): 4725-8, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12960014

RESUMO

The TSH receptor (TSHR) is a prototypic G protein-coupled receptor with a large extracellular domain. We have previously demonstrated homophilic interactions of TSHRs and their existence as constitutive oligomers. However, we have also shown that TSH itself promotes the formation of receptor monomers. We hypothesized, therefore, that TSHR monomers induced by TSH ligand may move into lipid rafts before effective TSH-induced signaling by bringing the cognate signaling molecules resident in such rafts together with the TSHRs. Thus, we aimed to determine whether the TSHRs would partition into these lipid rafts. The B subunit of cholera toxin (CTxB) binds to lipid raft-enriched GM1 ganglioside and has been widely exploited to visualize lipid rafts. Using such a method, we demonstrated the presence of these GM1-enriched lipid microdomains in Chinese hamster ovary cells by using CTxB labeled with a red dye (Alexa 594). To provide evidence for the presence of TSHRs in lipid rafts, we stained Chinese hamster ovary cells expressing TSHRGFP with labeled CTxB. Our results demonstrated that the TSHRGFP complexes localized to GM1-enriched lipid raft microdomains as evidenced by colocalization of the green fluorescent protein tag with the labeled CTxB. Hence, we concluded that a significant proportion of TSHRs were constitutively associated with lipid rafts. Furthermore, upon activation of these stained raft-receptor complexes with increasing concentrations of TSH, we observed that the raft-receptor complexes decreased significantly. The relevance of such receptor movement out of the rafts suggested that these may be the receptors critical in the initiation of signal transduction


Assuntos
Metabolismo dos Lipídeos , Receptores da Tireotropina/metabolismo , Animais , Células CHO , Membrana Celular/metabolismo , Cricetinae , Proteínas de Fluorescência Verde , Indicadores e Reagentes , Ligantes , Proteínas Luminescentes , Receptores da Tireotropina/efeitos dos fármacos , Tireotropina/farmacologia , Distribuição Tecidual
15.
Endocrinology ; 144(7): 3176-81, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12810574

RESUMO

Posttranslational processing of the TSH receptor (TSHR) involves proteolysis of a single chain holoreceptor into TSHR-alpha (or A) and TSHR-beta (or B) subunits, which remain associated via disulfide bonds and which may then form oligomers. As both uncleaved and cleavage-derived forms of this receptor have been reported to bind TSH and transduce signals, reasons for this cleavage into alpha- and beta-subunits have remained enigmatic. Recently we suggested that TSHR cleavage was related to receptor oligomerization and now we have asked if cleavage influenced the binding of G proteins to this receptor. Furthermore, as TSHR-alpha subunits are subject to shedding from the cell surface membrane, we have examined whether the remaining TSHR-beta subunits could mediate signaling themselves, either constitutively and /or ligand-induced. We found that only the cleaved form of the TSHR in transfected Chinese hamster ovary cells was able to bind Gsalpha protein, suggesting that cleavage of the native TSH receptor was associated with receptor activation. We also found that independently expressed TSHR-beta subunits on stable cell lines were unable to mediate either constitutive or TSH-induced signaling, as monitored by their inability to induce cAMP accumulation. These data suggested that receptor cleavage was intimately associated with receptor activation in the wild-type TSH receptor and that the residual TSHR-beta subunits left on the thyroid cell membrane, after TSHR cleavage and subsequent TSHR-alpha shedding, were essentially silent and did not participate in signal transduction.


Assuntos
Receptores da Tireotropina/genética , Receptores da Tireotropina/metabolismo , Transdução de Sinais/fisiologia , Animais , Células CHO , Cricetinae , Proteínas de Ligação ao GTP/metabolismo , Expressão Gênica/fisiologia , Ligação Proteica/fisiologia , Receptores da Tireotropina/química , Relação Estrutura-Atividade
16.
J Biol Chem ; 276(48): 45217-24, 2001 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-11535591

RESUMO

To examine thyrotropin (TSH) receptor homophilic interactions we fused the human TSH receptor (hTSHR) carboxyl terminus to green fluorescent protein (GFP) and the corresponding chimeric cDNA was expressed in Chinese hamster ovary cells. Fluorescent TSH receptors on the plasma membrane were functional as assessed by TSH-induced cAMP synthesis. The binding of TSH, as well as TSHR autoantibodies, induced time- and dose-dependent receptor capping. Fluorescence resonance energy transfer between receptors differentially tagged with GFP variants (RFP and YFP) provided evidence for the close proximity of individual receptor molecules. This was consistent with previous studies demonstrating the presence of TSHR dimers and oligomers in thyroid tissue. Co-immunoprecipitation of GFP-tagged and Myc-tagged receptor complexes was performed using doubly transfected cells with Myc antibody. Western blotting of the immunoprecipitated complex revealed the absence of noncleaved TSH holoreceptors. This further suggested that cleavage of the holoreceptor into its two-subunit structure, comprising disulfide-linked TSHR-alpha and TSHR-beta subunits, was required for the formation of TSHR dimers and higher order complexes.


Assuntos
Corantes Fluorescentes/química , Receptores da Tireotropina/química , Receptores da Tireotropina/metabolismo , Animais , Western Blotting , Células CHO , Membrana Celular/metabolismo , Separação Celular , Cricetinae , AMP Cíclico/metabolismo , DNA Complementar/metabolismo , Dimerização , Dissulfetos , Relação Dose-Resposta a Droga , Eletroforese em Gel de Poliacrilamida , Epitopos , Citometria de Fluxo , Proteínas de Fluorescência Verde , Humanos , Proteínas Luminescentes/metabolismo , Microscopia de Fluorescência , Testes de Precipitina , Ligação Proteica , Processamento de Proteína Pós-Traducional , Transfecção
17.
Infect Immun ; 69(5): 3073-81, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11292726

RESUMO

Pertussis toxin (PT), a holomer consisting of a catalytic S1 subunit and a B oligomer composed of S2-S4 and S3-S4 dimers, held together by the S5 subunit, exerts profound effects on immune cells, including T-cell mitogenicity. While the mitogenic activity of PT was shown to reside fully within the B oligomer, it could not be assigned to any particular B-oligomer component. In this study, we purified the S3-S4 dimer to homogeneity under conditions propitious to maintenance of the native conformation. In contrast to previous reports which suggested that both S3-S4 and S2-S4 dimers are necessary for mitogenic activity, our preparation of the highly purified S3-S4 dimer was as strongly mitogenic as the B oligomer, suggesting that the S3-S4 dimer accounts for the mitogenic activity of the B oligomer. Moreover, in vitro stimulation of naive lymphocytes by the S3-S4 dimer resulted in reversal of the normal CD4(+)/CD8(+) T-cell ratio from approximately 2:1 to 1:2. The reversal of the CD4(+)/CD8(+) T-cell ratio is unlikely to be due to preferential apoptosis-necrosis of CD4(+) T cells, as indicated by fluorescence-activated cell sorter analysis of annexin-stained T-cell subsets, or to preferential stimulation of CD8(+) T cells. The mechanism underlying the reversal requires further investigation. Nevertheless, the data presented indicate that the S3-S4 dimer may have potential use in the context of diseases amenable to immunological modulation.


Assuntos
Relação CD4-CD8 , Mitógenos/farmacologia , Toxina Pertussis , Proteínas Recombinantes de Fusão/farmacologia , Fatores de Virulência de Bordetella/farmacologia , Animais , Western Blotting , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Dimerização , Linfonodos/imunologia , Camundongos , Subunidades Proteicas , Proteínas Recombinantes de Fusão/isolamento & purificação , Fatores de Virulência de Bordetella/química , Fatores de Virulência de Bordetella/isolamento & purificação
18.
Thyroid ; 10(5): 407-12, 2000 May.
Artigo em Inglês | MEDLINE | ID: mdl-10884187

RESUMO

Probe technology has been advancing very rapidly but to study molecular events in real time, there has to be a discrete choice in the use of "probes" and the "labels" that they carry. In this minireview, we shed light on the use of fluorescent probes, especially the use of green fluorescent protein (GFP) and its variants as tools to cell biologists studying protein secretion and trafficking. The use of these GFP variants has further widened the application of Fluorescence Resonance Energy Transfer (FRET) in analyzing protein-protein interaction.


Assuntos
Endocrinologia/métodos , Glândula Tireoide/metabolismo , Transferência de Energia , Fluorescência , Corantes Fluorescentes , Proteínas de Fluorescência Verde , Humanos , Indicadores e Reagentes , Proteínas Luminescentes , Proteínas/metabolismo
19.
J Virol Methods ; 38(1): 145-52, 1992 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1644891

RESUMO

A simple, specific and economical dipstick immunobinding enzyme-linked immunosorbent assay (DIA) for detecting hepatitis B surface antigen (HBsAg) and antibodies to hepatitis delta virus (anti-HDV), utilizing cellulose nitrate membrane is described. Screening of 815 serum specimens for HBsAg by DIA and micro ELISA revealed a positivity of 22.69% and 22.94% respectively. In the detection of antibodies to delta antigen, DIA was compared with an indirect immunofluorescence technique using A3 cell line as antigen substrate and a commercial macro ELISA. Of the 143 HBsAg positive sera tested for anti-HDV, 59 (41.25%) were positive by both immunofluorescence and macro ELISA and 61 (42.65%) by DIA. While the positive and negative predictive values of DIA for HBsAg were 100% and 99.6%, for anti-HDV by DIA these were 96.7% and 100% respectively. Based on the simplicity of performance and the economical nature of the test system, DIA is recommended as a diagnostic tool for field surveys and small laboratories in developing countries.


Assuntos
Ensaio de Imunoadsorção Enzimática/métodos , Anticorpos Anti-Hepatite/sangue , Antígenos de Superfície da Hepatite B/sangue , Hepatite B/diagnóstico , Hepatite D/diagnóstico , Humanos , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Testes Sorológicos
20.
Indian J Med Res ; 89: 221-4, 1989 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-2807426

RESUMO

Eighty eight patients of glomerulonephropathies (HBsAg positive 67; HBsAg negative 21) and 88 matched and healthy controls were screened for non-organ specific autoantibodies-ANA, AMA, ASMA and APCA by indirect immunofluorescent technique. The 2.3 per cent positivity in the test group and the 8 per cent positivity in the control group did not suggest the involvement of hepatitis-B virus (HBV), as an influencing or associated agent. When 48 patients with glomerulonephropathies and 23 controls were screened for liver cell membrane (LMA) and renal cell membrane antibodies (RMA) by indirect immunofluorescent technique using isolated rat hepatocytes and renal cells, 79.2 per cent LMA positivity was seen in the HBsAg positive group and 41.7 per cent in the negative group and RMA positivity was 58 per cent in the positive group and 25 per cent in the negative group. Simultaneous positivity for both LMA and RMA was recorded in 50 per cent of the HBsAg positive patients and 15.7 per cent of the negative ones. The results suggest the possibility of an organ specific autoimmune trigger more frequently in HBV associated glomerulonephropathy.


Assuntos
Autoanticorpos/análise , Antígenos de Superfície da Hepatite B/análise , Hepatite B/complicações , Glomérulos Renais , Especificidade de Anticorpos , Autoanticorpos/imunologia , Hepatite B/imunologia , Antígenos de Superfície da Hepatite B/imunologia , Humanos , Nefropatias/etiologia , Nefropatias/imunologia
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