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R C Smallridge

Publications and source records attributed to R C Smallridge.

At least 37 records · Page 2Linked to original sources
PubMed1997

Polymerase chain reaction-based microsatellite analysis of fine-needle aspirations from Hürthle cell neoplasms.

Fine-needle aspiration (FNA) of the thyroid is the sine qua non in the preoperative evaluation of thyroid nodules. Despite this, cytological examination of FNA cannot differentiate malignant from benign Hürthle cell neoplasms. We have previously shown that Hürthle cell carcinomas harbor more genetic alterations on chromosomal arms 1q and 2p than Hürthle cell adenomas, and that all Hürthle cell neoplasms have a significantly higher frequency of alterations on chromosomal arm 1p compared with normal thyroid. To determine if these genetic alterations could be detected in FNA samples, we examined DNA from FNAs that were available from eight Hürthle cell neoplasms. Polymerase chain reaction (PCR) amplification of DNA demonstrated either direct correlation with alterations seen in the tumor samples or in some instances, additional chromosomal alterations. We conclude that PCR-based microsatellite DNA analysis of preoperative FNA samples from Hürthle cell neoplasms can potentially distinguish Hürthle cell carcinomas from adenomas and that with further validation and perfection, this technique may allow more optimal surgical management of patients with these lesions.

Adenocarcinoma↗
PubMed1997

Soluble interleukin-2 receptor is a thyroid hormone-dependent early-response marker in the treatment of thyrotoxicosis.

Thyrotoxic patients exhibit increased levels of immune activation molecules (soluble interleukin-2 receptor [sIL-2R], intercellular adhesion molecule-1 [ICAM-1], and endothelial-leukocyte adhesion molecule-1 [ELAM-1]) in serum, although the clinical significance of these measurements remains unclear. In a randomized 4-week study, we have recently shown that in the treatment of hyperthyroidism, the combination of cholestyramine and methimazole (MMI) resulted in faster lowering of serum thyroid-hormone levels than did MMI alone. Stored serial serum samples from patients participating in this randomized treatment trial were analyzed for sIL-2R, soluble ICAM-1 (sICAM-1), and soluble ELAM-1 (sELAM-1). The levels of all three molecules were elevated in patients with hyperthyroidism. Although the levels of sICAM-1 and sELAM-1 remained elevated through the 4-week follow-up period in both groups of patients, the sIL-2R levels (normal levels, 1.0 to 4.2 ng/ml) decreased significantly in the 10 patients who received cholestyramine in addition to MMI (week 0, 14.2 +/- 1.5 ng/ml; week 2, 10.8 +/- 1.2 ng/ml; week 4, 8.9 +/- 1.5 ng/ml). In eight patients who received MMI alone, sIL-2R decreased less rapidly (week 0, 12.3 +/- 1.4 ng/ml; week 2, 12.3 +/- 1.3 ng/ml; week 4, 10.9 +/- 1.3 ng/ml). sICAM-1 and sELAM-1 were elevated at baseline but did not decrease during therapy. In the former group, free thyroxine and free triiodothyronine decreased faster. These data show that levels of sIL-2R in serum, but not those of sICAM-1 and sELAM-1, may be of clinical use in the early follow-up evaluation of medically treated patients.

Antithyroid Agents↗
PubMed1996

Rapid assay of HSF1 and HSF2 gene expression by RT-PCR.

Primers were developed to allow the rapid and reliable assay of heat shock transcriptional factors 1 and 2 in human epidermoid A431 cells by following the protocol described in this study. Using the primers, the heat-induced increase in heat shock transcriptional factor 1 but not 2 was observed. This is the first report to show that heat shock increases the mRNA amount of HSF1 with no changes in HSF2 mRNA.

DNA Primers↗
PubMed1996

Imaging in thyroid cancer.

No ideal imaging method is available for the diagnosis of MTC. Once the diagnosis is suspected, serum calcitonin or CEA may help to confirm it. Often, multiple studies are done, especially a combination of MR imaging or ultrasound and an isotopic method. Tc(V)DMSA is an excellent agent but not readily available in the United States. Indium-labeled pentreotide is probably the imaging agent of choice in the United States.

Diagnostic Imaging↗
PubMed1996

Heat shock inhibits the hypoxia-induced effects on iodide uptake and signal transduction and enhances cell survival in rat thyroid FRTL-5 cells.

Chronic hypoxia inhibits rat thyroid function in vivo. To determine possible mechanisms, we studied the effect of hypoxia on iodide uptake, the involvement of second messengers, and cell membrane permeability in rat thyroid FRTL-5 cells. Since sublethal heat stress protects tissues from ischemia, we also determined effects of heat stress. The initial rate of iodide uptake in untreated cells was between 12.98 and 15.28 pmol/micrograms DNA/min. Hypoxia (5% O2) increased the rate of uptake in a time-dependent manner. Heating cells at 45 degrees C for 15 min (heat shock) prior to exposure to hypoxia for 3 days inhibited the increase in the initial rate of I-uptake. Using fura-2, we found that the resting [Ca2+]i in suspended FRTL-5 cells was 65 +/- 7 nM (n = 16). [Ca2+]i was not increased in cells exposed to hypoxia for 1 day, while a 3-day exposure increased [Ca2+]i by 43 +/- 4% (p < 0.05); no additional increase occurred after 7 days of exposure. When cells were heated prior to hypoxia exposure for 3 days, the hypoxia-induced increase in [Ca2+]i did not occur. Similar observations were found with inositol trisphosphates (InsP3). Exposure of cells to hypoxia for 3 days increased InsP3 from 0.08 +/- 0.02 (n = 5) to 0.32 +/- 0.04% total cpm (n = 5, p < 0.05), but sublethal heating of cells prior to hypoxia exposure prevented the increase. Three-day hypoxia increased PKC activity in the membrane fraction (from 67 +/- 7 to 86 +/- 4% of total activity, p < 0.05), and heat shock inhibited these changes also. Immunoblots showed that hypoxia treatment alone and heat shock plus hypoxia resulted in the translocation of PKC-alpha, -delta, -epsilon, and -zeta isoforms, whereas heat shock alone translocated only PKC-beta I, -beta II, and -zeta. Cell membrane integrity was assayed by trypan blue exclusion. Hypoxia alone for 3 days did not affect membrane permeability, but only 49 +/- 3% of cells excluded trypan blue when a 3-day hypoxia exposure was followed by a 6 h reoxygenation. Heat shock prior to hypoxia and reoxygenation protected cell membrane function. Heat shock also induced heat shock protein 70 kDa (HSP-70) synthesis at the transcriptional level. Results suggest that heat shock protects FRTL-5 cells from hypoxic injury, perhaps by inhibiting the initial rate of iodide uptake and second messengers. It is likely that HSP-70 plays an essential role in the process of protection.

Animals↗
PubMed1996

Screening of candidate oncogenes in human thyrotroph tumors: absence of activating mutations of the G alpha q, G alpha 11, G alpha s, or thyrotropin-releasing hormone receptor genes.

Activating mutations encoding substitutions at positions Arg201 and Gln227 of the alpha-subunit of the stimulatory G protein. G10 have been found in about 40% of pituitary somatotroph tumors. Although the etiology of thyrotroph adenomas is unknown, their autonomous behavior and blunted response to stimulatory hypothalamic hormone superficially resemble those of somatotroph tumors. We hypothesized that a subset of thyrotroph tumors might be caused by dominant somatic mutations that lead to inappropriate activation of the Gq/phospholipase C beta/Ca2+/protein kinase C. pathway normally triggered by occupancy of the TRH receptor (TRHR). We, therefore, screened samples from nine thyrotroph tumors for the presence of activating mutations of the alpha q, alpha 11, and TRHR genes. Fragments of alpha q and alpha 11 complementary DNA encompassing residues (Arg183 and Gln209) that correspond to Arg201 and Gln227 of alpha q were amplified and sequenced. Temperature gradient gel electrophoresis was used to screen for heterozygous mutations in the TRHR coding sequence as well as for known alpha s mutations. No mutations were detected. We conclude that mutations in these regions of the alpha q, alpha 11, alpha s, and TRHR genes occur infrequently, if at all, in human thyrotroph tumors. Alternative mechanisms underlying thyrotroph tumorigenesis, including changes in the expression levels of G protein alpha-subunits or TRHR, dysregulation of downstream components, inappropriate activation of other stimulatory pathways, or loss of inhibitory inputs, remain to be explored.

Adult↗
PubMed1996

Immunoglobulins from Graves' disease patients stimulate phospholipase A2 and C systems in FRTL-5 and human thyroid cells.

We have studied the effects of immunoglobulin G from Graves' disease patients on phospholipase A2 (PLA2) and C(PLC) systems in FRTL-5 and human thyroid cells. Immunoglobulin G (IgG) from Graves' disease patients stimulated arachidonic acid (AA) release in a time- and dose-dependent manner. In FRTL-5 thyroid cells, removal of external calcium had no significant effect on the IgG (20 micrograms/ml)-induced AA release in FRTL-5 thyroid cells. U-73122 (3 mumol/l), a PLC inhibitor, and quinacrine (100 mumol/l) but not U-26384 (5 mumol/l), PLA2 inhibitors, blocked the IgG-induced (20 micrograms/ml) AA release in FRTL-5 thyroid cells. Immunoglobulin G (100 micrograms/ml) also stimulated accumulation of inositol-1,4,5-triphosphate (IP3) in a time- and dose-dependent (20-300 micrograms/ml) manner in FRTL-5 cells. Immunoglobulin G from Graves' disease patients induced a significant increase of IP3 production (p = 0.01) compared to IgG from normal subjects. Removal of external calcium had no significant effect on the IgG-induced IP3 production. The PLC inhibitor U-73122 completely blocked IgG-induced IP3 production from FRTL-5 thyroid cells. Also, in human thyroid cells, IgG from Graves' disease patients induced a significant increase of AA release (p = 0.001) and IP3 production (p = 0.004) compared to the IgG from normal subjects. These data indicate that IgG from Graves' disease patients induced PLA2 activity that was PLC dependent, a pattern referred to as sequential activation. Our studies suggest that IgG from Graves' disease patients activates PLA2 and PLC systems in FRTL-5 and human thyroid cells. These signal transduction pathways could be involved in the pathogenesis of Graves' disease and future studies are warranted to investigate this area.

Adult↗
PubMed1996

Increases in HSF1 translocation and synthesis in human epidermoid A-431 cells: role of protein kinase C and [Ca2+]i.

BACKGROUND: It is known that heat shock increases both heat shock protein 70 kd (HSP-70) mRNA synthesis, and intracellular cytosolic free calcium concentration ([Ca2+]i). The latter enhances the heat inducible form of HSP-70 production by increasing the complex formation between heat shock transcriptional factor (HSF) and heat shock elements (HSE). In this study, we investigated the effect of agonists (PMA; ionomycin) and antagonists (BAPTA; staurosporine) of protein kinase C (PKC), and calcium channel on translocation and synthesis of HSF1, and activation of HSP-70 gene in human epidermoid A-431 cells. METHODS: Cells were incubated with poly 12-myristate 13-acetate (PMA) or ionomycin at different concentrations for various periods of time. Messenger RNAs of HSF and HSP-70 were measured with RT-PCR. The HSP-70 protein was determined with Western blots, and HSF protein was measured by gel mobility retardation assay. RESULTS: Significant increases in HSF binding to [32P]labeled HSE were found at 30 minutes in nuclear extract and at 4 hours in both nuclear and cytosol extracts. The PMA- and ionomycin-induced increases in HSF were in a concentration-dependent manner with a maximal increase at 10(-6) mol/L of each drug. Meanwhile, the mRNAs encoded for HSF1 and HSP-70, but not HSF2, were significantly increased and reached the maximum at 1 hour after the treatment. The PMA increased [Ca2+]i by 92% because of Ca2+ influx. The increases in mRNA of HSF1 and HSP-70 induced by treatment with 1 mumol/L PMA were completely blocked by preincubating cells with either 2 mumol/L staurosporine in the presence of extracellular Ca2+ or 100 mumol/L BAPTA-am in absence of extracellular Ca2+. Like PMA, the increases induced by ionomycin were also inhibited by 100 mumol/L BAPTA-am in absence of extracellular Ca2+. Furthermore, Western blots show that 1 mumol/L PMA or ionomycin induced maximal increase in HSP-70 after 7 hours of continuous incubation with either agent. When cells were simultaneously treated with 1 mumol/L PMA and ionomycin together for 1 hour, the increase in HSP-70 and HSF1 mRNAs reached a greater level than the level stimulated by either drug alone. CONCLUSIONS: These results indicate that both PMA and ionomycin stimulate HSF1, but not HSF2, translocation and synthesis leading to the HSP-70 expression and that their effects are Ca(2+)-dependent.

Calcium↗
PubMed1996

Evidence for the involvement of protein kinase C isoforms in alpha-1 adrenergic activation of phospholipase A2 in FRTL-5 thyroid cells.

BACKGROUND: FRTL-5 thyroid cells are a cell line extensively used for the investigation of thyroid functions. Activation of alpha-1 adrenergic receptors stimulates both arachidonic acid (AA) release and cytosolic Ca2+ increase in this cell line. Cytosolic Ca2+ and arachidonic acid are known to be important second messengers regulating a variety of thyroid functions. The generation of these messengers is regulated primarily by two different types of phospholipases, phospholipase C (PLC) and phospholipase A2 (PLA2). METHODS: Norepinephrine (NE, 10 mumol/L) was used as an alpha-1 adrenergic activator, and cytosolic-free Ca2+ concentration ([Ca2+]i) was determined using the fluorescent dye indo-1. Arachidonic acid release was measured as an indicator of PLA2 activation, and protein kinase C (PKC) activity determination and isoforms identification were performed using commercial kits. RESULTS: Norepinephrine increased [Ca2+]i and AA release. Prevention of NE-induced cytosolic Ca2+ influx, either by removal of extracellular Ca2+ or by use of Ca2+ channel blockers, NiCl2 or CoCl2, inhibited AA generation entirely. Inhibition of NE-induced increase in [Ca2+]i by the Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), also significantly suppressed NE-induced AA release. Inhibition of PKC activity by PKC inhibitors (H-7 or staurosporine) or downregulation induced by prolonged treatment with phorbol 12-myristate 13-acetate (PMA) or thyleametoxin (TX) significantly blocked the NE-induced AA release, which indicates PKC is involved in mediating NE-induced AA release. Protein kinase C activity measurement indicated that NE induced an activation of PKC in 5 minutes. To further characterize the role of PKC or Ca2+ in regulation of AA release, we identified PKC isoforms by immunoblotting with specific antibodies against 8 different Protein kinase C isoforms. PKC-alpha, -beta I, -beta II, -gamma, delta, -epsilon, -zeta, and -eta isoforms were identified. Norepinephrine induced translocation of PKC-alpha, -beta I, -beta II, -gamma, -delta, and -epsilon isoforms but not -zeta and -eta from cytosol to membrane. Chelation of intracellular Ca2+, prevention of Ca2+ influx, or prolonged treatment with thymeleatoxin (TX) completely blocked the NE-induced translocation of PKC-alpha. CONCLUSIONS: These results, taken together with data obtained from AA experiments, suggest that PKC plays a critical role in alpha-1 adrenergic receptor mediated PLA2 activation and subsequent AA release. Extracellular Ca2+ influx is a prerequisite for both PKC-alpha translocation and AA release. Whether Ca2+ acts directly upon the PLA2, or via PKC-alpha, to regulate AA generation is an intriguing question that remains to be clarified.

Animals↗
PubMed1995

Phospholipase A2-induced neurotoxicity in vitro and in vivo in rats.

The present study evaluated the neurotoxic potential of phospholipase A2 (PLA2) in in vitro (primary neuronal cultures) and in vivo (EEG and behavior) rat models of CNS excitability. In vitro, PLA2 (0.0038-5.8 nM) or melittin (a potent activator of endogenous PLA2; 100-5000 nM), were highly neurotoxic, causing approximately 500 units/ml LDH release. The neurotoxic EC50s for PLA2 and melittin were 1.8 (1.4-2.3) and 848 (501-1280) nM, respectively. Neurotoxic concentrations of PLA2 stimulated neuronal release of [3H]AA. Preliminary in vitro experiments evaluating changes in neuronal calcium flux indicated that PLA2 caused transient, and melittin sustained, increases in [Ca2+]i. In vivo, PLA2 (0.5-5 micrograms i.c.v.) or melittin (2.5-20 micrograms i.c.v.) produced nonconvulsive EEG seizures, which generalized to status epilepticus. While the onset of seizure development was markedly delayed for PLA2 (1.5-4.5 h), the seizure inducing effects of melittin were evident within 3.5 +/- 0.2 min and more severe. Both PLA2 and melittin were lethal, exhibiting LD50s of 0.62 micrograms and 8.4 micrograms, respectively. Pretreatment with (+)-MK801 (5 micrograms, i.c.v.) significantly attenuated melittin, but not PLA2, in vivo neurotoxicity. PLA2 induced neuropathology in surviving rats revealed extensive cortical and subcortical injury to forebrain neurons and fibre pathways. Collectively, these results demonstrate the potent neurotoxic potential of PLA2, the delayed clinical nature of its in vivo neurotoxicity and the applicability of these model systems to future studies on mechanisms of PLA2 neurotoxicity and the development of potential PLA2 antagonists.

Animals↗
PubMed1995

Acquired von Willebrand's disease: a rare manifestation of postpartum thyroiditis.

This report describes the diagnosis of acquired type I von Willebrand disease in a 30-year-old woman (G5P5) who presented with complaints of excessive bleeding in the postpartum period. The patient's additional complaints of fatigue, depression, and inability to lose weight resulted in laboratory testing that indicated hypothyroidism due to thyroiditis. Clinical symptoms and laboratory tests for von Willebrand disease and hypothyroidism normalized with L-thyroxine replacement. Thyroiditis resulting in symptomatic hypothyroidism occurs in 2-4 per cent of postpartum women. The possibility of underlying hypothyroidism should be considered for those patients, especially if they are parous women, who appear to have an acquired bleeding disorder suggestive of von Willebrand disease.

Adolescent↗
PubMed1995

Effects of an aminosteroid inhibitor of phospholipase C-dependent processes on the TCR-mediated signal transduction pathway in human T cells.

Phospholipase C (PLC) is a key enzyme in the T cell antigen receptor (TCR)-mediated signal transduction pathway in human T cells. Agonist-induced PLC activation leads to a cascade of intracellular events that ultimately regulate gene transcription and T cell activation. We studied the effects of U-73122, a putative inhibitor of PLC-dependent events, on TCR/CD3 complex-mediated early and late events in human T cells. Both anti-CD3 monoclonal antibody-induced 1,4,5-inositol trisphosphate (IP3) and free intracytoplasmic calcium [Ca2+]i increases were inhibited by U-73122 (0.05-0.1 microM), but not by the related inactive analog, U-73343. U-73122 did not affect thapsigargin-evoked [Ca2+]i increase in T cells, indicating a specific mode of inhibition of CD3 signaling. Late events in T cell activation like CD3-mediated T cell proliferation and mitogen-induced interleukin 2 receptor (IL2-R) expression were also inhibited by this agent. T cell proliferation induced by a combination of a phorbol ester and ionomycin was not affected by U-73122. Although an agonist effect on basal IP3 and [Ca2+]i levels was observed with high concentrations of U-73122, the inhibitor alone did not induce any proliferative effect or IL2-R expression in T cells. Our results demonstrate for the first time that U-73122 is a specific inhibitor of PLC-dependent processes in human T cells and could serve as a valuable tool for studying T cell signal transduction pathways.

Adjuvants, Immunologic↗
PubMed1995

Identification of protein kinase C and its multiple isoforms in FRTL-5 thyroid cells.

Protein kinase C (PKC) has been implicated as an important regulator of signal transduction in the FRTL-5 thyroid cell line, but little is known about its isoforms in this cell line. In the present investigation, we characterized the activation of PKC by measuring the enzyme activity and identifying its isoforms in both cytosol and membrane fractions. Phorbol 12-myristate 13-acetate (PMA) was used as a PKC activator in this study. PKC activity assay revealed that PMA (300 nM) induced a rapid translocation from cytosol to membrane within 1 min and led to an almost complete translocation within 15 min. Multiple PKC isoforms were examined by Western blot analysis with specific antibodies against alpha, beta, gamma, delta, epsilon, and zeta isoforms. PKC alpha, delta, epsilon, and zeta were identified in this cell line, but PKC beta and gamma were not. Exposure of the cells to PMA (300 nM) for 5 to 30 min led to the translocation of PKC alpha, delta, and epsilon from the cytosol to the membrane fraction, while PKC zeta was not affected. Treatment with PMA (300 nM) for 24 h resulted in the down-regulation of PKC alpha, delta, and epsilon, but not PKC zeta. This study demonstrates for the first time direct evidence for the activation of PKC, and expression and distribution of its isoforms in FRTL-5 thyroid cells.

Animals↗
PubMed1994

A phospholipase C inhibitor, U-73122, blocks TSH-induced inositol trisphosphate production, Ca2+ increase and arachidonic acid release in FRTL-5 thyroid cells.

To characterize the role of phospholipase C (PLC)-mediated intrathyroid signal transduction by thyrotropin, we studied the effect of U-73122, an aminosteroid inhibitor of PLC-dependent activity, on TSH-activated PLC-Ca2+ and arachidonic acid (AA) signalling systems in cultured FRTL-5 rat thyroid cells. In the presence of extracellular Ca2+, TSH (0.1 microM) increased intracellular free calcium concentration ([Ca2+]i) by 63 +/- 6% with a sustained plateau phase, and AA release by 160 +/- 16%. By deletion of extracellular Ca2+, TSH induced a similar maximal [Ca2+]i increase, but the plateau phase and AA release were entirely suppressed. U-73122 (5 microM) inhibited TSH stimulation of 3H-labelled inositol trisphosphates (IP3) production by 73 +/- 3% (P < 0.01) in one study, and completely in another. U-73122 concentration-dependently blocked the TSH-induced Ca2+ increase in either the presence or absence of external Ca2+. U-73122 also showed a similar concentration-response inhibition of TSH-induced AA release. These results provide direct evidence of PLC mediation of TSH-stimulated signal transduction in FRTL-5 thyroid cells. TSH-induced external Ca2+ entry, as well as intracellular Ca2+ mobilization, is probably a PLC-mediated process. From an IP3-sensitive intracellular pool, TSH induces intracellular Ca2+ mobilization. External Ca2+ entry seems to be a prerequisite for TSH-induced AA release. U-73122 inhibition of both cytosolic Ca2+ increase and AA release further confirms [Ca2+]i dependence for TSH stimulation of AA release.

Animals↗
PubMed1994

Sodium cyanide increases cytosolic free calcium: evidence for activation of the reversed mode of the Na+/Ca2+ exchanger and Ca2+ mobilization from inositol trisphosphate-insensitive pools.

This study characterized the cytosolic free Ca2+ concentration ([Ca2+]i) in NaCN-treated human A-431 cells. The resting [Ca2+]i was 85 +/- 8 nM (n = 141) in untreated cells at 37 degrees C, determined with the fura-2 fluorescence probe. When cells were treated with NaCN, [Ca2+]i increased in a time- and NaCN concentration-dependent manner. When cells were exposed to 10 mM NaCN for 10 min, [Ca2+]i increased 278 +/- 28% (n = 5) but returned to normal within 45 min after treatment. The [Ca2+]i increase depended on the presence of external Ca2+. La3+ and Cd2+, but not verapamil or nifedipine, inhibited the NaCN-induced [Ca2+]i increase. The NaCN-induced [Ca2+]i increase also depended on external Na+ (K1/2 = 85 mM). The intracellular Na+ concentration, measured with the fluorescence probe SBFI, increased 267 +/- 16% after NaCN treatment. The NaCN-induced [Ca2+]i increase was modulated by treatment with ouabain or veratridine and was completely blocked by tetrodotoxin, amiloride (K1/2 = 5.4 microM), and dichlorobenzamil (K1/2 = 0.28 microM). These results suggest NaCN activates the Na+/Ca2+ exchange system. TMB-8 and ryanodine both partially blocked the increase in [Ca2+]i in the presence of external Ca2+, indicating that Ca2+ release from intracellular pools also occurred after the initial Ca2+ influx. NaCN decreased inositol trisphosphates production. U-73122, bradykinin, or monensin did not prevent the NaCN-induced increase in [Ca2+]i. However, the magnitude of the [Ca2+]i increase caused by NaCN was abolished in ionomycin-treated the [Ca2+]i increase caused by NaCN was abolished in ionomycin-treated cells, indicating that intracellular Ca2+ release induced by NaCN is derived from an ionomycin-sensitive Ca2+ pool. The results suggest that NaCN initially increased Na+ influx, which activated the reverse mode of a Na+/Ca2+ exchanger, leading to an increase in Ca2+ influx. The Ca2+ influx induced a Ca2+ mobilization from only an ionomycin-sensitive intracellular Ca2+ pool containing ryanodine receptors.

Amiloride↗
PubMed1994

Psychologic symptoms before and after parathyroid surgery.

PURPOSE: To identify in an outpatient setting the type and number of psychologic symptoms of patients with primary hyperparathyroidism before and after surgery. PATIENTS AND METHODS: A convenience sample of 18 patients with primary hyperparathyroidism and a comparison sample of 20 patients with benign thyroid disease were scheduled by their primary care physician to have surgery. Assessments of psychologic symptoms, using the Symptom Checklist-90-Revised, and measurements of serum total calcium, ionized calcium, parathyroid hormone, albumin, alkaline phosphatase, urea nitrogen, creatinine, protein, and phosphate were obtained preoperatively. and at 1, 3, and 6 months postoperatively. RESULTS: The hyperparathyroid group had significantly higher (p < 0.01) levels of total and ionized serum calcium and parathyroid hormone preoperatively, with biochemical normalization 1 month postoperatively. These patients showed multidimensional psychologic symptom distress preoperatively in the areas of obsession-compulsion, interpersonal sensitivity, depression, anxiety, hostility, and psychoticism; they also had a greater number and intensity of distressful symptoms. Paranoid ideation was significantly higher in the hyperparathyroid group than in the comparison group, but it did not quite reach the clinical range. The greatest improvement in symptoms occurred by 1 month after surgery, with the hyperparathyroid group approaching the normative mean. There were no group differences before or after surgery for the areas of somatization and phobic anxiety. CONCLUSIONS: The Symptom Checklist-90-Revised is a simple, quick, and cost-effective way to quantitatively assess the psychologic symptoms of patients with primary hyperparathyroidism. We found that psychologic symptom distress is multidimensional, that symptoms had profoundly improved by 1 month after parathyroidectomy, and that somatization and anxiety did not differ between our groups.

Adult↗
PubMed1994

P2-purinergic stimulation of iodide efflux in FRTL-5 rat thyroid cells involves parallel activation of PLC and PLA2.

Extracellular ATP increases inositol phosphates, cytosolic Ca2+ concentration ([Ca2+]i), arachidonic acid (AA) release, and iodide efflux in FRTL-5 cells. To examine the sequence of events in P2-purinergic receptor activation by ATP, a phospholipase C (PLC) inhibitor (U-73122) and a phospholipase A2 (PLA2) inhibitor (U-26384), as well as 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'- tetraacetic acid (BAPTA) and downregulation of protein kinase C (PKC) were used. ATP increased inositol trisphosphate (IP3), [Ca2+]i, AA release, and 125I efflux dose dependently. U-73122 inhibited the IP3 and calcium increase but not AA; U-26384 prevented AA release but not the increase in calcium. Both agents inhibited iodide efflux. BAPTA prevented any ATP-induced increase in [Ca2+]i without affecting AA release or 125I efflux. PKC downregulation had no effect on ATP-stimulated AA release, but reduced 125I efflux. We conclude that ATP-induced iodide efflux involves parallel, not sequential, activation of PLC and PLA2. No increase in [Ca2+]i or PKC activity is required for PLA2 activation. In contrast, an increase in 125I efflux depends on PKC and PLA2 activities, but not an increase in [Ca2+]i.

Adenosine Triphosphate↗