Comparison of the metabolic and endocrine effects of 3,5,3'-triiodothyroacetic acid and thyroxine.

To test the hypothesis that 3,5,3'-triiodothyroacetic acid (Triac) is more active as a TSH suppressor than on peripheral parameters of thyroid hormone action, the following parameters were studied: basal metabolic rate, sleeping energy expenditure (SEE), sex hormone-binding globulin, and cholesterol. In a double blind trial, 14 subjects received during 3 weeks (phase 1) 180 micrograms T4 or 1700 micrograms Triac daily, divided into 3 doses, to suppress thyroidal secretion. The dosage was doubled for the next 3 weeks (phase 2). Under T4 treatment, TSH reached 0.11 mU/L during phase 1 and less than 0.03 mU/L during phase 2. With Triac, a marked TSH inhibition occurred after 1 week (0.17 mU/L), followed by an escape during the following 2 weeks (0.63 mU/L). During phase 2, an almost complete TSH suppression was obtained (0.03 mU/L). Both Triac doses suppressed endogenous thyroid hormone secretion, as evidenced by T4 and rT3 levels. Both substances induced a 2-fold stimulation of sex hormone-binding globulin during phase 2. Serum cholesterol decreased similarly, without affecting the high/low density lipoprotein ratio. T4 increased SEE by 4.1% and 8.5% during phases 1 and 2. Triac failed to induce the expected peripheral metabolic responses of the thyroid hormones, as demonstrated by an unchanged SEE and basal metabolic rate. These results clearly show a preferential action of Triac on TSH suppression.

Influence of sex and age on T3 receptors and T3 concentration in the pituitary gland of the rat: consequences on TSH secretion.

A reduced secretion of thyroid hormones with age has been documented in humans and animals with no substantial increase in TSH secretion, which may be indicative of an age-related impairment of the pituitary sensitivity to the negative control exerted by thyroid hormones. We have evaluated in rats the influence of sex and age on pituitary T3 nuclear receptors--known to be determinant in the regulation of TSH secretion--as well as on T3 concentration in the pituitary gland. As regards sex, the density of T3 receptors and the concentration of T3 in pituitary gland and plasma were greater in females than in males whereas pituitary and plasma TSH concentrations were less. As for age, the density of T3 receptors was greater in old male rats than in young ones with no changes in pituitary T3 and plasma TSH concentrations. In old female rats in contrast, there was no significant increase in T3 receptors but pituitary T3 was less and plasma TSH greater than in young female rats. In both sexes plasma thyroid hormones and pituitary TSH were reduced with age whereas TSH response to TRH was not altered. These results illustrate sex and age differences in pituitary T3 receptors and pituitary T3 concentration as well as in TSH secretion. In young animals of both sexes an inverse correlation is observed between the density of pituitary T3 receptors and plasma TSH. In contrast, in old animals the absence of this correlation is suggestive of an age-related impairment of T3 action on the thyrotrophs or of changes pertaining to other factors modulating TSH secretion.

Biokinetics and dosimetry of 111 In-DOTA-NOC-ATE compared with 111In-DTPA-Octreotide

Aim: Biokinetics and dosimetry of 111In-DOTA-NOC-ATE (NOCATE) and 111In-DTPA-octreotide (Octreoscan?, OCTREO) were comparatively studied in the same patients. Patients and Methods: Seventeen patients (10 males, 7 females), mean age 60 years referred for an Octreoscan? because of carcinoid (N=9), unspecified neurodendocrine tumors (N=6), thymoma (N=1) or medullary thyroid carcinoma (N=1) accepted a second study with NOCATE. Four patients had no detectable tumor at the time of scanning. Whole-body (WB) anterior-posterior scans were recorded 0.5 (100% reference scan), 4, 24 and 48 hrs (N=17) and 120 hrs (N=6) after injection. OCTREO (178±15 MBq) preceded NOCATE (108±14 MBq) imaging with 16±5 days in 16 patients while 1 patient had first NOCATE followed 14 days later by OCTREO. Blood samples were taken 5, 15, 30, 60, 240 and 1440 min after injection. Background corrected geometric mean counts of WB, lung, kidney, liver, spleen and blood counts expressed in % of the initial composite WB and blood counts, respectively were fitted to bi- or single exponential curves and dosimetry was performed for male and female patients using MIRDOSE3.1 and OLINDA/EXM. Results: Initially, WB, lung and kidney activity was similar but retention was significantly higher for NOCATE compared with OCTREO. Liver and spleen uptake of NOCATE was higher from beginning (p<0.001) and remained so over time. Activity in rest of body showed similar α and β half-lives, but the β half-life fraction of NOCATE was much higher than OCTREO (49% vs. 19%, respectively). Blood T1/2β was longer for NOCATE compared with OCTREO (19 vs. 6h). Residence times were similar in male and female patients while they were in both genders higher for NOCATE than OCTREO. Consequently, effective dose (ED) for NOCATE (ED 114 and 134 μSv/MBq for man and women, respectively) exceeded that of OCTREO (ED = 61 and 71 μSv/MBq), the latter results being close to the ICRP-published radiation dose of OCTREO (ED = 54 and 71 µSv/MBq, respectively). Differential activity measurement in blood cells and plasma showed that only a minor fraction of NOCATE and OCTREO (<5 % in the mean) was bound to globular blood components. Conclusions: NOCATE showed higher retention in normal organs and delivered roughly twice the radiation dose of OCTREO. The ED of OCTREO in these patients was similar to ICRP80 report when adopting a bladder voiding interval of 2 hours.

NF-kappaB transmits Eda A1/EdaR signalling to activate Shh and cyclin D1 expression, and controls post-initiation hair placode down growth.

A novel function of NF-kappaB in the development of most ectodermal appendages, including two types of murine pelage hair follicles, was detected in a mouse model with suppressed NF-kappaB activity (c(IkappaBalphaDeltaN)). However, the developmental processes regulated by NF-kappaB in hair follicles has remained unknown. Furthermore, the similarity between the phenotypes of c(IkappaBADeltaN) mice and mice deficient in Eda A1 (tabby) or its receptor EdaR (downless) raised the issue of whether in vivo NF-kappaB regulates or is regulated by these novel TNF family members. We now demonstrate that epidermal NF-kappaB activity is first observed in placodes of primary guard hair follicles at day E14.5, and that in vivo NF-kappaB signalling is activated downstream of Eda A1 and EdaR. Importantly, ectopic signals which activate NF-kappaB can also stimulate guard hair placode formation, suggesting a crucial role for NF-kappaB in placode development. In downless and c(IkappaBalphaDeltaN) mice, placodes start to develop, but rapidly abort in the absence of EdaR/NF-kappaB signalling. We show that NF-kappaB activation is essential for induction of Shh and cyclin D1 expression and subsequent placode down growth. However, cyclin D1 induction appears to be indirectly regulated by NF-kappaB, probably via Shh and Wnt. The strongly decreased number of hair follicles observed in c(IkappaBalphaDeltaN) mice compared with tabby mice, indicates that additional signals, such as TROY, must regulate NF-kappaB activity in specific hair follicle subtypes.

Peroxisome proliferator-activated receptors A link between endocrinology and nutrition?

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily like the steroid, thyroid, or retinoid hormone receptors, which are ligand-activated transcription factors regulating gene expression. PPARs mediate the induction of the enzymes of the peroxisomal and microsomal fatty-acid oxidation pathways by hypolipidemic drugs such as clofibrate and are probably also involved in the gene expression of other lipid-metabolism-associated proteins that are controlled by fibrate hypolipidemic drugs. That PPARs play an important role in the regulation of lipid metabolism is reinforced by the discovery of their activation by physiologic concentrations of fatty acids. This observation raises the question of whether fatty acids are ligands of PPARs, which would imply that nutritional fatty acids can act like hormones.

Effects of thyromimetic drugs on aldosterone-dependent sodium transport in the toad bladder.

Aldosterone increases transepithelial Na+ transport in the urinary bladder of Bufo marinus. The response is characterized by 3 distinct phases: 1) a lag period of about 60 min, ii) an initial phase (early response) of about 2 hr during which Na+ transport increases rapidly and transepithelial electrical resistance falls, and iii) a late phase (late response) of about 4 to 6 hr during which Na+ transport still increases significantly but with very little change in resistance. Triiodothyronine (T3, 6 nM) added either 2 or 18 hr before aldosterone selectively antagonizes the late response. T3 per se (up to 6 nM) has no effect on base-line Na+ transport. The antagonist activity of T3 is only apparent after a latent period of about 6 to 8 hr. It is not rapidly reversible after a 4-hr washout of the hormone. The effects appear to be selective for thyromimetic drugs since reverse T3 (rT3) is inactive and isopropyldiiodothyronine (isoT2) is more active than T3. The relative activity of these analogs corresponds to their relative affinity for T3 nuclear binding sites which we have previously described. Our data suggest that T3 might control the expression of aldosterone by regulating gene expression, e.g. by the induction of specific proteins, which in turn will inhibit the late mineralocorticoid response, without interaction with the early response.

Post-traumatic stimulus suppressible myoclonus of peripheral origin.

A patient is described who presented with myoclonus of the first dorsal interosseus muscle of the right foot. This myoclonus occurred 18 months after trauma of the cutaneous branch of the deep peroneal nerve on the dorsal aspect of the foot. Tactile stimulation in the dermatome of this nerve, or an anaesthetic block of the deep peroneal nerve stopped the myoclonus. The different innervation between the efferent motor activity responsible for the movements and the sensory afference suppressing it points firmly towards involvement of central connections. However, abolition of the movement by anaesthesia suggests the presence of a peripheral ectopic generator. This finding confirms that focal myoclonus can have its origin in the peripheral nervous system and may be modulated by sensory inputs.

The Tea4-PP1 landmark promotes local growth by dual Cdc42 GEF recruitment and GAP exclusion.

Cell polarization relies on small GTPases, such as Cdc42, which can break symmetry through self-organizing principles, and landmarks that define the axis of polarity. In fission yeast, microtubules deliver the Tea1-Tea4 complex to mark cell poles for growth, but how this complex activates Cdc42 is unknown. Here, we show that ectopic targeting of Tea4 to cell sides promotes the local activation of Cdc42 and cell growth. This activity requires that Tea4 binds the type I phosphatase (PP1) catalytic subunit Dis2 or Sds21, and ectopic targeting of either catalytic subunit is similarly instructive for growth. The Cdc42 guanine-nucleotide-exchange factor Gef1 and the GTPase-activating protein Rga4 are required for Tea4-PP1-dependent ectopic growth. Gef1 is recruited to ectopic Tea4 and Dis2 locations to promote Cdc42 activation. By contrast, Rga4 is locally excluded by Tea4, and its forced colocalization with Tea4 blocks ectopic growth, indicating that Rga4 must be present, but at sites distinct from Tea4. Thus, a Tea4-PP1 landmark promotes local Cdc42 activation and growth both through Cdc42 GEF recruitment and by creating a local trough in a Cdc42 GAP.

Utilisation en tomoscintigraphie d'anticorps monoclonaux radio-marqués pour la détection chez l'homme des cancers digestifs et des cancers médullaires de la thyroïde

Two 131-Iodine radiolabelled monoclonal antibodies were used to perform tomoscintigraphy in 42 patients: 11 patients bearing medullary thyroid cancers and 19 patients bearing gastrointestinal cancers received an antibody directed against carcino-embryonic antigen; 12 patients bearing gastro-intestinal cancers received an antibody directed against a non circulating antigen expressed by human colorectal cancers cell lines. Tomoscintigraphy is particularly useful for analysing the complex biodistribution of radiolabelled antibodies and the low contrast images encountered in immunoscintigraphy; the problems related to the true positive rate and to the clinical specificity of the method are discussed.

Variant ionotropic glutamate receptors as chemosensory receptors in Drosophila.

Ionotropic glutamate receptors (iGluRs) mediate neuronal communication at synapses throughout vertebrate and invertebrate nervous systems. We have characterized a family of iGluR-related genes in Drosophila, which we name ionotropic receptors (IRs). These receptors do not belong to the well-described kainate, AMPA, or NMDA classes of iGluRs, and they have divergent ligand-binding domains that lack their characteristic glutamate-interacting residues. IRs are expressed in a combinatorial fashion in sensory neurons that respond to many distinct odors but do not express either insect odorant receptors (ORs) or gustatory receptors (GRs). IR proteins accumulate in sensory dendrites and not at synapses. Misexpression of IRs in different olfactory neurons is sufficient to confer ectopic odor responsiveness. Together, these results lead us to propose that the IRs comprise a novel family of chemosensory receptors. Conservation of IR/iGluR-related proteins in bacteria, plants, and animals suggests that this receptor family represents an evolutionarily ancient mechanism for sensing both internal and external chemical cues.

Peroxisome proliferator-activated receptors and lipid metabolism.

PPARs are nuclear hormone receptors which, like the retinoid, thyroid hormone, vitamin D, and steroid hormone receptors, are ligand-activated transcription factors mediating the hormonal control of gene expression. Two lines of evidence indicate that PPARs have an important function in fatty acid metabolism. First, PPARs are activated by hypolipidemic drugs and physiological concentrations of fatty acids, and second, PPARs control the peroxisomal beta-oxidation pathway of fatty acids through transcriptional induction of the gene encoding the acyl-CoA oxidase (ACO), which is the rate-limiting enzyme of the pathway. Furthermore, the PPAR signaling pathway appears to converge with the 9-cis retinoic acid receptor (RXR) signaling pathway in the regulation of the ACO gene because heterodimerization between PPAR and RXR is essential for in vitro binding to the PPRE and because the strongest stimulation of this gene is observed when both receptors are exposed simultaneously to their activators. Thus, it appears that PPARs are involved in the 9-cis retinoic acid signaling pathway and that they play a pivotal role in the hormonal control of lipid metabolism.

Intérêt du bleu de méthylène dans la chirurgie de l'hyperparathyroïdism primaire [Methylene blue in surgery of primary hyperparathyroidism]

Is surgery for primary hyperparathyroidism easier when methylene blue (MB) is given preoperatively? This retrospective study compares the durations of interventions for primary hyperparathyroidism carried out after i.v. MB administration to those when no MB was given. Over a period of 20 years (June 1976 to December 1996), 175 consecutive patients (56 men and 119 women, with ages ranging from 16 to 92, mean 59.6) were operated upon for primary hyperparathyrodism; 55 were operated before February 1986--the period when BM was introduced routinely, and 120 after. Thirty-two other patients were excluded from the study: 14 had had a previous cervicotomy and 18 another procedure in addition to the parathyroidectomy (usually on the thyroid gland), two conditions which prolonged the time devoted to parathyroid identification and excision. Preoperative calcemia averaged 2.97 mmol/L (2.34 to 4.59) and mean preoperative PTH was equal to 2.6 times the upper normal limit (0.5 to 24.1). Both groups were similar for as age, sex, preoperative calcium and PTH, and histologies. Methylene blue was administered intravenously (5 mg/kg diluted in 500 cc of 5% glucose) over a period of time of one hour starting two hours prior to surgery. All 175 procedures were performed by two surgeons and duration of surgery was recorded from the anesthesiologist's notes. There were 149 adenomas (85%), 24 hyperplasias (14%), a combination of both in two, and unspecified in two others. Except for a case of acute lower back pain synchronous to the injection of the dye (which was immediately stopped), MB was well tolerated. Mean duration for the 55 interventions performed without MB was 68 minutes (35 to 140, median 60), compared to 49 minutes for the 120 procedures carried out after MB had been given (20 to 155, median 45). Differences in operative, times were highly significant (p < 10(-6) and represented a gain of time of 27%. Surgery for primary hyperparathyroidism was significantly shorter when it was preceded by the administration of MB, a dye which facilitates the identification of pathologic parathyroid gland(s).

Bonds between fibronectin and fibronectin-binding proteins on Staphylococcus aureus and Lactococcus lactis.

Bacterial cell-wall-associated fibronectin binding proteins A and B (FnBPA and FnBPB) form bonds with host fibronectin. This binding reaction is often the initial step in prosthetic device infections. Atomic force microscopy was used to evaluate binding interactions between a fibronectin-coated probe and laboratory-derived Staphylococcus aureus that are (i) defective in both FnBPA and FnBPB (fnbA fnbB double mutant, DU5883), (ii) capable of expressing only FnBPA (fnbA fnbB double mutant complemented with pFNBA4), or (iii) capable of expressing only FnBPB (fnbA fnbB double mutant complemented with pFNBB4). These experiments were repeated using Lactococcus lactis constructs expressing fnbA and fnbB genes from S. aureus. A distinct force signature was observed for those bacteria that expressed FnBPA or FnBPB. Analysis of this force signature with the biomechanical wormlike chain model suggests that parallel bonds form between fibronectin and FnBPs on a bacterium. The strength and covalence of bonds were evaluated via nonlinear regression of force profiles. Binding events were more frequent (p < 0.01) for S. aureus expressing FnBPA or FnBPB than for the S. aureus double mutant. The binding force, frequency, and profile were similar between the FnBPA and FnBPB expressing strains of S. aureus. The absence of both FnBPs from the surface of S. aureus removed its ability to form a detectable bond with fibronectin. By contrast, ectopic expression of FnBPA or FnBPB on the surface of L. lactis conferred fibronectin binding characteristics similar to those of S. aureus. These measurements demonstrate that fibronectin-binding adhesins FnBPA and FnBPB are necessary and sufficient for the binding of S. aureus to prosthetic devices that are coated with host fibronectin.

Study of the mechanisms regulating the proliferative potential of human CD8+T lymphocytes over-expressing telomerase reverse transcriptase (hTERT)

Résumé La plupart des cellules issues du sang ont une durée de vie limitée. Dans les cellules somatiques humaines, y incluant les lymphocytes T, la taille des télomères diminue progressivement à chaque division cellulaire, pouvant aboutir à des instabilités chromosomiques. L'expression ectopique du gène de la transcriptase réverse de la télomérase (hTERT) dans les cellules restaure l'activité de la télomérase, et permet un rallongement de leur vie réplicative. Malgré l'absence de signes caractéristiques de transformation, nous ne savons pas encore si les cellules somatiques qui surexpriment hTERT sont physiologiquement indiscernables des cellules normales. Certaines études récentes proposent que la télomérase joue plusieurs rôles additionnels dans d'autres phénomènes biologiques tels que la réparation de l'ADN, la survie et la croissance des cellules. Dans notre étude, nous avons utilisé des clones issus de lymphocytes T cytotoxiques surexprimant la télomérase afin d'étudier les mécanismes moléculaires qui règlent leur prolifération et leur sénescence. Nous avons montré que les «jeunes » cellules T exprimant ou non hTERT révèlent des taux de croissance identiques suite à des réponses de stimulation induites par des mitogènes. De plus, aucun changement global dans leur expression des gènes n'a pu être mis en évidence. Curieusement, nous avons observé des réponses réduites dans la prolifération des cellules transduites avec la télomérase qui présentaient une élongation des télomères et une durée de vie prolongée. Ces cellules, malgré le maintien d'un niveau élevé de l'expression de gènes impliqués dans la progression du cycle cellulaire, ont également montré une expression accrue de plusieurs gènes trouvés en commun avec nos lymphocytes T vieillissants n'exprimant pas de télomérase. En particulier, les cellules ayant une durée de vie prolongée grâce à l'expression de la télomérase accumulaient également certains inhibiteurs du cycle cellulaire tels que p16Ink4a et p21Cip1, associés à l'arrêt de la croissance cellulaire. En résumé, nos résultats indiquent la présence fonctionnelle de mécanismes alternatifs pouvant contrôler la croissance réplicative de ces cellules; ils sont donc encourageants dans l'optique d'une utilisation à moindre risque de lymphocytes T «immortalisés » à des fins thérapeutiques pour traiter les tumeurs malignes ou les infections. Summary Most mature blood cells have a finite life span. In human somatic cells, including T lymphocytes, telomeres progressively shorten with each cell division eventually leading to chromosomal instability. Ectopic expression of the human telomerase reverse transcriptase (hTERT) gene in cells restores telomerase activity and results in the extension of their replicative life span. Despite lack of transformation characteristics, it is yet unknown whether somatic cells that over-express telomerase are biologically and physiologically indistinguishable from normal cells. Recent data suggest that telomerase might mediate additional functions in DNA repair, cell survival and cell growth. Using CD8+ T lymphocyte clones over-expressing telomerase we investigated the molecular mechanisms that regulate T cell proliferation and senescence. Here we show that early-passage T cell clones transduced or not with hTERT displayed identical growth rates upon mitogenic stimulation and no marked global changes in gene expression. Surprisingly, reduced proliferative responses were observed in hTERT-transduced cells with elongated telomeres and extended life span. These cells, despite maintaining high expression level of genes involved in cell cycle division and progression, also showed increased expression of several genes associated with normal aging T lymphocytes. In particular, late passage T cells over-expressing telomerase accumulated the cyclin-dependent inhibitors p16INK4a and p21CIP1 that have largely been associated with in vitro growth arrest. Whether tumor-reactive CD8+ T cells that ectopically express telomerase could now be used for adoptive transfer therapy in cancer patients remains unclear at this point. Nevertheless, our results regarding the safe and effective use of hTERT-transduced lymphocytes are encouraging, since they indicate that alternative growth arrest mechanisms such as p 16 and p21 are still functional in these cells and regulate to some extend their growth potential.

Interstitial pregnancies' diagnosis and management: an eleven cases series.

PRINCIPLES: Interstitial pregnancy represents 2% of ectopic pregnancies, but it is a highly morbid condition with a 2.5% of maternal mortality. Its diagnostic and therapeutic management remains controversial. The aim of this review is to describe the management of interstitial pregnancy in our institution between 2001 and 2011 and to define some general rules for the clinical practice. METHODS: Single institution retrospective study. RESULTS: Eleven women were treated for interstitial pregnancy. The median age was 33 years and the median gestity was 4. Seven patients had a history of gynaecological surgery and four interstitial pregnancies followed in vitro fertilisation. The diagnosis was made at a median gestational age of seven weeks with a median beta-HCG level of 5,838 U/l. Six of the eleven patients received an initial treatment with intracornual methotrexate, three with intramuscular methotrexate and two with surgery. The median time to beta-HCG resolution was 58 days. Three of the eleven patients needed a second line treatment: two after intramuscular methotrexate and one after intracornual methotrexate. Six patients had further pregnancies and delivered by caesarean section. CONCLUSIONS: A high prevalence of previous ectopic pregnancies, gynaecological surgery and of pregnancies resulting from in vitro fertilisation was observed. The earliness of the diagnosis was the factor that allowed a conservative treatment in most cases. Beta-HCG level follow up was fundamental in allowing a second line therapy but beta-HCG can persist over a long period of time and this must be taken into account due to its possible psychological impact. Intracornual methotrexate seems to be more efficacious than intramuscular methotrexate in our series.