Diverse foxp3 expression in children with type 1 diabetes and celiac disease

Imbalance between different types of T lymphocytes, such as T helper (Th) and regulatory T cells (Tregs), has been reported to play a part in the pathogenesis behind such autoimmune diseases as type 1 diabetes (T1D) and celiac disease (CD). Defects in Tregs are proposed to at least partly explain the imbalance of Th cells found in children with immunologic diseases. Peripheral blood mononuclear cells from 24 children with T1D and/or CD, and reference children (that is, those without any of these diseases) were stimulated with disease-associated antigens (insulin, gluten, transglutaminase [tTG]), and phytohemagglutinin (PHA). The mRNA expression of the Treg-associated marker FOXP3 was analyzed with multiplex real-time RT-PCR. Children with T1D showed both a low spontaneous (P < 0.05) and PHA-induced (P < 0.01) expression of FOXP3 mRNA compared to children with CD. Children with T1D also had a low PHA-induced FOXP3 mRNA expression compared to the group of children diagnosed with both T1D and CD (P < 0.05). Spontaneous (P < 0.05) and PHA-induced (P < 0.05) FOXP3 mRNA expression was high in children with CD compared to reference children. In contrast, stimulation with insulin tended to induce high FOXP3 mRNA expression in T1D children compared to reference children (P= 0.057). In conclusion, children with only T1D generally showed a lower FOXP3 mRNA expression than did children with CD, or with T1D in combination with CD, which suggests impaired regulation of the immune system in children with T1D.

Amiodarone inhibits thyroidal iodide transport in vitro by a cyclic adenosine 5'-monophosphate- and iodine-independent mechanism

Thyroid side effects are common in patients treated for cardiac arrhythmias with amiodarone (AM). A major disturbance is inhibited thyroidal radioiodine uptake in AM-induced thyrotoxicosis, which makes 131I therapy ineffective. On the other hand, failure to escape from the Wolff-Chaikoff effect by down-regulation of the sodium/iodide symporter (NIS) is proposed to explain AM-induced hypothyroidism. However, previously no experimental studies on the possible mechanisms have been conducted. We therefore investigated the early effects of AM on thyroidal iodide transport using bicameral chamber cultures of primary pig thyrocytes that reproduce the three tissue compartments (epithelium, lumen, and extrafollicular space) of the gland. AM dose-dependently (1-50 microm) inhibited the TSH-stimulated transepithelial (basal to apical) transport of 125I- by up to 90%. The inhibitory effect was noticed already after 8 h and was further pronounced after 1-4 d, depending on the AM concentration. The intracellularly accumulated 125I- was reduced by perchlorate but not AM, and quantitative real-time RT-PCR revealed no change in the NIS expression in AM-treated cells. Blocking of cAMP degradation with 3-isobutyl-1-methylxanthine or withdrawal of AM reversed AM-induced changes in electrolyte transport but were unable to recover the suppressed 125I- transport. The iodine-free AM analog dronedarone also inhibited 125I- transport to the same extent as AM. The findings indicate that AM blocks thyroidal iodide uptake by reducing the iodide permeability of the apical plasma membrane of the thyroid epithelial cells. The effect is iodine independent and long-lasting and does not involve impaired function of NIS or the TSH receptor/cAMP signaling pathway.

Choroid plexus electrolytes and ultrastructure following transient forebrain ischemia

A temporal profile of lateral and fourth ventricle rat choroid plexus (LVCP and 4VCP, respectively) tissue injury and recovery was determined using alterations in K, Na, and H2O content and ultrastructure after 10 min of transient forebrain ischemia (TFI). At 0.5 h postischemia the LVCP displayed a maximum reduction in K content by 32% and a significant increase in Na content by 85% and H2O content by 22%. LVCP tissue K, Na, and H2O content returned to sham values by 24 h postischemia. Ultrastructural changes appeared more severe between 0.5 and 12 h postischemia, whereas by 24 h, normal ultrastructure was restored. Elevations in 4VCP tissue Na (P < 0.05) and H2O content, which were less than those in LVCP, gradually reached a maximum by 24 h compared with sham. No change in 4VCP tissue ultrastructure was observed. These results indicate that the LVCP tissue is more vulnerable than 4VCP in the bilateral carotid artery occlusion model but that it recovers in a timely manner after TFI. Furthermore, the ability of the LVCP tissue to rapidly recover suggests its functional importance in helping to restore brain homeostasis.

Hydrocephalus decreases chloride efflux from the choroid plexus epithelium

To explore the novel concept of intrinsic brain regulation of the choroid plexus (CP), we studied the function of the CP exposed to increased intracranial pressure (ICP). The function of the CP was evaluated by in vitro chloride (Cl-) efflux from isolated CP 21 days after kaolin induced hydrocephalus. The Cl- efflux was significantly decreased in animals with elevated intracranial pressure (rate constant, K = 0.024 +/- 0.001 s-1) and enlarged ventricles (K = 0.023 +/- 0.001 s-1) compared to sham animals (K = 0.031 +/- 0.001 s-1). In contrast, the Cl- efflux of CP from animals with normal ICP and ventricular size did not differ from sham animals. These results illustrate the first demonstration of regulation of the CP epithelial function with elevated ICP; they also suggest a brain-CP regulatory mechanism that alters CP function.

Adenosine as substrate and receptor agonist in the ovary

In the present study the possible dual effects of adenosine as substrate and adenosine receptor agonist in rat granulosa cells, cumulus-oocyte complexes, luteal cells and ovarian membranes are discussed. Adenosine is an indispensable compound in cell energy metabolism, as precursor to cofactors, second messenger and nucleic acids. Adenosine is also an agonist to adenosine receptors. The adenosine receptor can either inhibit (A1) or stimulate (A2) adenylate cyclase. Alternatively, in some cells adenosine receptor activation is linked to other cellular events like inhibition of Ca2+ fluxes. Adenosine is taken up by isolated preovulatory granulosa and luteal cells from pregnant mare serum gonadotropin-treated immature rats, but follicle stimulating hormone (FSH) decreases the uptake by granulosa cells. Adenosine, but not the non-metabolizable adenosine analogs 5'-(N-ethyl)carboxamide-adenosine (NECA), 2-chloro-adenosine (2-Clado), N6-(R-phenyl-isopropyl)-adenosine (R-PLA) and N6-(S-phenyl-isopropyl)-adenosine (S-PLA), increase granulosa cell ATP levels. FSH and luteinizing hormone (LH) decrease granulosa cell ATP levels in the presence or absence of adenosine. It has previously been shown that FSH and LH decrease oxygen consumption by cumulus-oocyte complexes and increase their lactate production. These effects have been suggested to be due to a competition of cofactors (e.g. ADP) common to glycolysis and the respiratory chain. The fact that adenosine reverse the gonadotropin-induced effects on oxygen consumption and lactate production support this theory. Adenosine and its analogs increase cAMP accumulation in luteal and granulosa cells only in the presence of gonadotropins, and this effect is antagonized by the adenosine receptor antagonist 8-phenyl-theophylline (8-PHT). Furthermore, adenylate cyclase is stimulated by adenosine analogs in membranes from non-luteinized and luteinized ovarian membranes and in luteal cell homogenates. The effect of NECA is antagonized by 8-PHT. In the membranes, the rank order of potency was NECA greater than 2-Clado greater than R-PLA greater than S-PLA, suggesting adenosine A2 receptors. In summary, it is suggested that adenosine can act both as a substrate to intracellular metabolism and as an adenosine A2 receptor agonist in granulosa and luteal cells. A paracrine short loop positive feedback model is proposed where extracellular adenosine, derived from a gonadotropin-induced extracellular increase in cAMP and a decrease in cellular ATP, enhances gonadotropin stimulation in granulosa and luteal cells.

Refractoriness to follicle-stimulating hormone in rat ovarian granulosa cells--a concentration- and time-dependent phenomenon

Granulosa cells from pre-ovulatory ovarian follicles of rats were exposed, in vitro, to one or two pulses of follicle-stimulating hormone (FSH) in a superfusion apparatus. The superfusate was analysed for cyclic adenosine-3',5' monophosphate (cAMP) and steroids. In experiments with two consecutive FSH pulses, the response to the second pulse (100 ng/ml) was inversely related to the concentration of the first FSH pulse (2.5-100 ng/ml). Within certain limits, a lower total amount of cAMP and progesterone was accordingly released in response to the two FSH pulses when the concentration of the first pulse was increased. This refractoriness declined within a few hours as shown in experiments with extended pulse intervals. Two short and separate FSH pulses also evoked a higher combined response than did a single long FSH pulse lasting the whole time period. In these cases the cells thus responded with a lower total cAMP and progesterone release when exposed to a higher amount of FSH. Clinical trials on i.m. versus pulsatile i.v. FSH administration to anovulatory women have shown a similar relationship between FSH dose and effect, though other parameters were measured than those in the present study.

Methotrexate/fluorouracil scheduling influences normal tissue toxicity but not antitumor effects in patients with squamous cell head and neck cancer: results from a randomized trial

To test the hypothesis that sequential scheduling of methotrexate (MTX) and fluorouracil (FU) produces a synergistic antitumor effect, we randomized 113 patients with recurrent or locally advanced squamous cell carcinoma of the head and neck to receive MTX-FU either 18 hours apart or simultaneously, with leucovorin rescue. There were 100 patients with locally advanced newly presenting disease and 13 patients with recurrence. Excessive toxicity was observed in the first 11 patients who received MTX 250 mg/m2 administered intravenously (IV) and leucovorin at 36 hours, therefore all subsequent patients received MTX 200 mg/m2 administered IV and leucovorin at 24 hours. FU 600 mg/m2 IV was administered to all patients, and treatment was given on days 1 and 8 of 21-day cycles. The treatment groups were well balanced for known prognostic variables. The response rate was 47.3% (26 of 55) for simultaneous v 44.8% (26 of 58) for sequential therapy. These results exclude a 20% difference in response rate favoring sequential therapy at P = .04. There was no observed difference in survival between the two treatment arms (P = .55) with a minimum follow-up of 8 months. Toxicity was greater in patients who received sequential therapy, and the difference was confined to the gastrointestinal (GI) tract. A comparison of the distribution in maximum Eastern Cooperative Oncology Group (ECOG) toxicity scores during chemotherapy for the two treatment groups showed greater stomatitis (P = .001), diarrhea (P = .04), and overall toxicity (P = .02) for sequential treatment without an observed difference in bone marrow toxicity. The results of this trial indicate that sequential MTX-FU is not superior to simultaneous therapy for the treatment of patients with head and neck cancer. Biochemical modulation of MTX-FU by drug scheduling may occur in vivo and may be organ specific.

Luteotropic effects of prostaglandin E2 on the human corpus luteum of the menstrual cycle and early pregnancy

Human corpora lutea (CL) of the menstrual cycle and early pregnancy were excised at operation, cut into pieces, and incubated or superfused in the presence of hCG or prostaglandin (PG) E2. After incubation, the tissue levels of cAMP and the medium concentrations of progesterone (P) were determined, while the concentration of P was analyzed after superfusion. PGE2 stimulated cAMP formation in CL from all phases of the menstrual cycle as well as from early pregnancy and caused an increase in P formation in CL from the early and midluteal phases of the menstrual cycle as well as from early pregnancy. A difference was found in the latency, the lag phase until maximal response, and the duration of response between the effects of PGE2 and hCG on both cAMP and P formation. Thus, the effect of PGE2 started more rapidly and was of shorter duration than that of hCG. The stimulatory effect of PGE2 on CL from early pregnancy was of the same magnitude as that of CL from the menstrual cycle. On the other hand, hCG had less stimulatory effect on cAMP and P formation in CL from early pregnancy compared to CL from the menstrual cycle. We conclude that PGE2 stimulates P and cAMP formation in isolated human CL from all phases of the menstrual cycle as well as in early pregnancy, indicating a luteotropic effect of this PG.

A technique for superfusion of isolated granulosa cells. Dynamics of cAMP production and steroidogenesis in response to gonadotropins

A superfusion model for isolated ovarian cells was developed and characterized in detail. Granulosa cells isolated from pre-ovulatory rat ovarian follicles were placed in superfusion (perifusion) chambers with a volume of 125 microliters. Culture medium was pumped through the chambers, collected in 20-min fractions of 600 microliters and analysed for cAMP and steroids. Viability was confirmed by morphological examination. The use of polycarbonate membranes to retain the cells in the chambers was abandoned since the membranes caused severe cell damage. The temporal relationships between gonadotropic stimuli and the release of cyclic 3':5'-adenosine monophosphate (cAMP) and steroids was investigated. Within 10 min FSH elicited transient increase in the release of cAMP and progesterone but had no effect on testosterone or estradiol-17 beta release. Amplitude and duration of the response in cAMP and progesterone release were correlated to concentration and length of the FSH pulse when these parameters were varied within the ranges 1-100 micrograms/l and 30-270 min, respectively. Compared with the cAMP response, the progesterone response peaked up to 30 min later and lasted 1 to 2 h longer but could not be extended to more than approximately 6 h, not even with longer FSH pulses. These results could indicate a development of desensitization.

Steroidogenesis in isolated rat granulosa cells--changes during follicular maturation

Steroid release was investigated in granulosa cells isolated from rat ovarian follicles at different maturation stages. Immature rats were treated with 10 IU of pregnant mare's serum gonadotrophin (PMSG) to induce follicular growth and maturation. Granulosa cells were isolated and subsequently incubated for 4 h in the absence or presence of follicle stimulating hormone (FSH), luteinizing hormone (LH) or forskolin. The concentrations of progesterone (P), 20 alpha-dihydroprogesterone (20 alpha DHP), testosterone (T) and oestradiol (E2) in the media were determined by radioimmunoassay. During maturation, basal release of T increased markedly at late dioestrus. At pro-oestrus, concomitant with a sharp rise in E2 and P release, T release returned to previously low levels. Addition of FSH or LH stimulated P release at late dioestrus and pro-oestrus but had no effect on E2 or T levels. Basal 20 alpha DHP levels remained low until a sharp rise at mid pro-oestrus. A stimulatory effect of gonadotrophins on 20 alpha DHP was first seen at this stage. The adenylate cyclase stimulator forskolin resembled FSH in all its effects. In summary, the present study demonstrates that maturing, but not preovulatory, granulosa cells have an increased capacity to release T during a relatively short period. It is suggested that this T peak could be of great importance for the further progress of follicular maturation.