Metyrosine-associated endocrinological changes in pheochromocytoma and paraganglioma.

Objective: Metyrosine (alpha-methyl-para-tyrosine) effectively reduces catecholamine levels in patients with pheochromocytoma/paraganglioma. However, improvements in physiological and metabolic parameters and changes in endocrine function associated with metyrosine administration should be validated in comparison to surgery. This study was performed to confirm the effects of metyrosine on the physiological, metabolic, and endocrinological functions of patients with pheochromocytoma/paraganglioma in the perioperative period. Design: This retrospective cohort study was performed at a single university hospital. Methods: We included ten patients with pheochromocytoma/paraganglioma who received oral metyrosine after α-blocker therapy and consecutive surgeries. Urinary catecholamine metabolite levels and other clinical parameters were evaluated before and after metyrosine administration, and 1 week after surgery. Results: The mean age was 53.1 ± 16.1 years. Of the ten participants (four men and six women), nine had pheochromocytoma and one had paraganglioma. The median maximum metyrosine dose was 750 mg/day. Urinary catecholamine metabolite levels significantly decreased in a dose-dependent manner after metyrosine administration. Both systolic and diastolic blood pressure significantly decreased after metyrosine and surgical treatment. Metyrosine administration significantly improved insulin sensitivity, although surgery improved the the basal insulin secretion. Additionally, serum prolactin and thyroid-stimulatory hormone levels were significantly increased by metyrosine treatment, whereas plasma renin activity was decreased. Conclusions: Metyrosine significantly reduced catecholamines in patients with pheochromocytoma/paraganglioma and ensured the safety of the surgery. Adjustment of metyrosine administration may make surgical pretreatment more effective in achieving stabilized blood pressure and improving glucose metabolism. Endocrine parameters may manifest as the systemic effects of metyrosine administration.

Eruptive xanthomas as a marker for metabolic disorders: A specific form of xanthoma that reflects hypertriglyceridemia.

Eruptive xanthomas are skin manifestations associated with hypertriglyceridemia. Accordingly, the improvement of hypertriglyceridemia can ameliorate this condition. We report a case of a patient with type 2 diabetes mellitus who was diagnosed with this skin lesion. Clinicians should be aware that eruptive xanthomas could indicate metabolic disorders associated with atherosclerosis.

Masked Diabetes Insipidus Hidden by Severe Hyponatremia: A Case of Pituitary Metastasis of Lung Adenocarcinoma.

BACKGROUND Hyponatremia is an electrolyte disorder frequently encountered by clinicians. Secondary adrenal insufficiency due to pituitary metastatic tumors should be considered as an alternative diagnosis when clinicians encounter patients with lung cancer who demonstrate hyponatremia. However, masked central diabetes insipidus should also be considered to prevent critical dehydration when glucocorticoid replacement therapy will be initiated. CASE REPORT A 70-year-old man with advanced lung adenocarcinoma demonstrated high-grade hyponatremia of 122 mmol/L. Magnetic resonance imaging disclosed a metastatic pituitary tumor and endocrinological examinations confirmed panhypopituitarism, including secondary adrenal insufficiency. Hydrocortisone replacement revealed masked diabetes insipidus with elevation of serum sodium levels that reached 151 mmol/L. Desmopressin administration was required to prevent water depletion and to immediately ameliorate the hypernatremia. CONCLUSIONS This is the first case report of masked diabetes insipidus that demonstrated high-grade hyponatremia. Secondary adrenal insufficiency can mask the hypernatremia that is a typical manifestation of diabetes insipidus. Physicians should consider adrenal insufficiency and diabetes insipidus due to pituitary metastasis of advanced malignancies, even when they encounter patients with hyponatremia.

Role of a new bioassay for thyroid-stimulating antibodies (aequorin TSAb) in Graves' ophthalmopathy.

Graves' ophthalmopathy (GO) is characterized by an autoimmune reaction against thyrotropin (TSH) receptors and is diagnosed by TSH receptor antibody (TRAb). A novel assay for thyroid-stimulating antibody (TSAb) was recently introduced using a frozen Chinese hamster ovary cell line expressing TSH receptors, cyclic adenosine monophosphate (cAMP)-gated calcium channel, and aequorin (aequorin TSAb). The aim of this study was to evaluate the role of aequorin TSAb in GO. We studied 136 Japanese patients with GO (22 euthyroid and 8 hypothyroid GO patients) at our hospital. TRAbs were estimated by first generation TRAb (TRAb 1st), second generation TRAb (hTRAb 2nd), conventional porcine TSAb, and the new aequorin TSAb assays. Aequorin TSAb, porcine TSAb, TRAb 1st, and hTRAb 2nd were positive in 125/136 (92%), 110/136 (81%), 81/130 (62%), and 93/114 (82%) patients, respectively. In patients with hyperthyroid GO, they were positive in 98/106 (98%), 96/106 (91%), 78/101 (77%), and 84/93 (90%) patients, respectively. In patients with euthyroid GO, they were positive in 19/22 (86%), 9/22 (41%), 1/21 (5%), and 6/17 (35%) patients, respectively. Aequorin TSAb levels were significantly related to TRAb 1st (r = 0.4172, p < 0.0001), hTRAb 2nd (r = 0.2592, p < 0.0001), and porcine TSAb (r = 0.4665, p < 0.0001). Clinical activity score (CAS) was significantly greater in patients with high titers of aequorin TSAb than in those with low titers. Aequorin TSAb levels were significantly related to the signal intensity ratio of the enlarged eye muscle and proptosis evaluated by MRI before steroid pulse therapy. Aequorin TSAb assay was more sensitive than the conventional assays, especially in euthyroid GO.

Isolation and identification of novel neutrophil-activating cryptides hidden in mitochondrial cytochrome C.

Although it is known that neutrophils infiltrate damaged sites immediately after tissue injury, the endogenous factors that induce their acute transmigration and activation have not been thoroughly investigated. For the candidates of those factors, we recently discovered two novel neutrophil-activating cryptides, mitocryptide-1 (MCT-1) and mitocryptide-2 (MCT-2), hidden in mitochondrial proteins. In addition, many unknown neutrophil-activating peptides other than MCT-1 and MCT-2 were also observed during their purification. Here, we isolated and purified a novel neutrophil-activating peptide from porcine hearts, which we showed by structural analyses to have an identical primary structure to porcine mitochondrial cytochrome c (68-85). We named this novel functional octadecapeptide as mitocryptide-CYC (MCT-CYC). Structure-activity relationships of cytochrome c on ß-hexosaminidase (ß-HA) release from neutrophilic-differentiated HL- 60 cells demonstrated that peptides derived from the C-terminal part of cytochrome c induced ß-HA release and that cytochrome c (70-85) was the most potent cryptide among them. Since cytochrome c is known to be involved in the apoptotic process, our results suggest that cryptides, including MCT-CYC, derived from mitochondrial cytochrome c are possible factors that induce scavenging of toxic debris produced from apoptotic cells by neutrophils.

Discovery of mitocryptide-1, a neutrophil-activating cryptide from healthy porcine heart.

Although neutrophils are known to migrate in response to various chemokines and complement factors, the substances involved in the early stages of their transmigration and activation have been poorly characterized to date. Here we report the discovery of a peptide isolated from healthy porcine hearts that activated neutrophils. Its primary structure is H-Leu-Ser-Phe-Leu-Ile-Pro-Ala-Gly-Trp-Val-Leu-Ser-His-Leu-Asp-His-Tyr-Lys-Arg-Ser-Ser-Ala-Ala-OH, and it was indicated to originate from mitochondrial cytochrome c oxidase subunit VIII. This peptide caused chemotaxis at concentrations lower than that inducing beta-hexosaminidase release. Such responses were observed in neutrophilic/granulocytic differentiated HL-60 cells but not in undifferentiated cells, and G(i2)-type G proteins were suggested to be involved in the peptide signaling. Moreover the peptide activated human neutrophils to induce beta-hexosaminidase secretion. A number of other amphipathic neutrophil-activating peptides presumably originating from mitochondrial proteins were also found. The present results suggest that neutrophils monitor such amphipathic peptides including the identified peptide as an initiation signal for inflammation at injury sites.

Cryptides: functional cryptic peptides hidden in protein structures.

Peptidergic hormones, neurotransmitters, and neuromodulators are extracellular signaling molecules that play central roles in physiological signal transmissions between various cells, tissues, and organs. These factors are primarily translated as inactive precursor proteins according to the genetic information. These precursor proteins are then cleaved by various proteases including signal peptidases and processing enzymes to produce matured bioactive factors. During these processes, various fragmented peptides are also produced from the same precursor proteins. Such fragmented peptides may have various unexpected biological activities that have not been identified yet because these peptides are considered to be produced and released along with mature factors at the same secretary pathways. Recently, we found that various fragmented peptides of mitochondrial proteins that are produced during the maturation processes, such as fragments of cytochrome c oxidase, activate neutrophils whose functions are distinct from their parent proteins. These findings suggest the existence of many different functional peptides whose functions have not been identified yet. These unidentified peptides may play a variety of roles in various regulatory mechanisms, and therefore, they are expected to provide novel regulatory and signaling mechanisms, "Peptide World".

Identification of genes expressed preferentially in the honeybee mushroom bodies by combination of differential display and cDNA microarray.

To clarify the molecular basis underlying the neural function of the honeybee mushroom bodies (MBs), we identified three genes preferentially expressed in MB using cDNA microarrays containing 480 differential display-positive candidate cDNAs expressed locally or differentially, dependent on caste/aggressive behavior in the honeybee brain. One of the cDNAs encodes a putative type I inositol 1,4,5-trisphosphate (IP(3)) 5-phosphatase and was expressed preferentially in one of two types of intrinsic MB neurons, the large-type Kenyon cells, suggesting that IP(3)-mediated Ca(2+) signaling is enhanced in these neurons.