A rapid extraction method for serum calcitonin

Low cerebrospinal fluid and plasma orexin-A (hypocretin-1) concentrations in combat-related posttraumatic stress disorder

The hypothalamic neuropeptide, orexin-A has a number of regulatory effects in humans and pre-clinical evidence suggests a link to neuroendocrine systems known to be pathophysiologically related to posttraumatic stress disorder (PTSD). However, there are no reports of central nervous system (CNS) or peripheral orexin-A concentrations in patients with PTSD, or any anxiety disorder. Cerebrospinal fluid (CSF) and plasma levels of orexin-A were serially determined in patients with PTSD and healthy comparison subjects to characterize the relationships between orexin-A (in the CNS and peripheral circulation) and central indices of monoaminergic neurotransmission and to determine the degree to which CNS orexin-A concentrations reflect those in the circulating blood. CSF and plasma samples were obtained serially over a 6-h period in 10 male combat veterans with chronic PTSD and 10 healthy male subjects through an indwelling subarachnoid catheter. Orexin-A concentrations were determined in plasma and CSF and CSF levels of the serotonin metabolite, 5-hydroxyindolacetic acid (5-HIAA), and the dopamine metabolite, homovanillic acid (HVA), were determined over the sampling period. CSF and plasma orexin-A concentrations were significantly lower in the patients with PTSD as compared with healthy comparison subjects at all time points. In addition, CSF orexin-A concentrations strongly and negatively correlated with PTSD severity as measured by the Clinician-Administered PTSD Scale (CAPS) in patients with PTSD. Peripheral and CNS concentrations of orexin-A were correlated in the healthy comparison subjects and peripheral orexin-A also correlated with CNS serotonergic tone. These findings suggest low central and peripheral orexin-A activity in patients with chronic PTSD are related to symptom severity and raise the possibility that orexin-A is part of the pathophysiological mechanisms of combat-related PTSD.

Estimation of Bioavailability of Salmon Calcitonin from the Hypocalcemic Effect in Rats (I): Pharmacokinetic-Pharmacodynamic Modeling Based on the Endogenous Ca Regulatory System

The hypocalcemic effect of salmon calcitonin (sCT) after intravenous administration was explained on the basis of an integrated pharmacokinetic-pharmacodynamic (PK-PD) model with the endogenous Ca regulatory system in the rat. The pharmacokinetics of sCT described by a conventional two-compartment model showed the extremely rapid elimination of sCT from plasma (MRT; 6.86 min). The hypocalcemic effect of sCT reached a peak from 0.5 to 1.5 hrs after administration, and the peak time tended to prolong with increasing doses. This delay in pharmacological effect of sCT against plasma concentration may be a result of a summation of multiple actions of the endogenous Ca regulatory system including feedback control. The plasma Ca regulation system in the rat was investigated by i.v. bolus administration of calcium gluconate and/or endogenous (rat) calcitonin (rCT). Since non-linearity in the relationship between Ca and rCT concentrations in plasma was observed, we assumed that rCT was secreted in accordance with the plasma Ca level via an exponential function. The pharmacokinetics of rCT was represented as a linear one-compartment model. To link the rCT level with plasma Ca level, an additional effect compartment was required to explain the delay in onset and decline of the pharmacological effect. This Ca regulation model explained the observed Ca and rCT profiles in plasma after administration of Ca and/or rCT. The plasma Ca levels after administration of sCT could be well described by the present integrated model. This suggested the potential for prediction of plasma sCT concentration only from the hypocalcemic effect after extravascular administration of sCT, using this PK-PD model.

Behavior of mucoadhesive nanoparticles having hydrophilic polymeric chains in the intestine

The behavior of nanoparticles having surface hydrophilic poly(N-isopropylacrylamide), poly(N-vinylacetamide), poly(vinylamine) or poly(methacrylic acid) chains in the intestine was examined. The permeability of salmon calcitonin (sCT) from the mucosal to serosal side of the everted jejunum was enhanced in the presence of nanoparticles. This enhancement, which correlated with the amount of sCT incorporated in nanoparticles, disappeared completely after removal of the mucous layer. When fluorescein isothiocyanate-dextran (FD-4) was used instead of sCT, its permeability through the everted jejunum with and without mucous layer was not enhanced by any nanoparticles, because FD-4 was not incorporated in nanoparticles at all. These findings indicated that the accumulation of nanoparticles incorporating sCT in the mucous layer resulted in the enhancement of sCT permeability. Nanoparticles with poly(N-isopropylacrylamide) or poly(vinylamine) on their surfaces did not cause any damage to the intestinal mucosa. Also, none of the nanoparticles opened the tight junction of the intestinal membrane. It was concluded that mucoadhesion of nanoparticles incorporating sCT to the gastrointestinal mucosa contributed to the absorption enhancement of sCT.

Circulating monomer-like calcitonin in osteoporotic patients

Physiological concentrations of monomeric calcitonin can inhibit osteoclastic bone resorption in vitro. We therefore investigated the circulating molecular forms, including monomer-like calcitonin, and their concentrations in 9 men and 9 women with established osteoporosis. Calcitonin was immunoextracted from serum by the use of rabbit calcitonin antibodies coupled to Sepharose 4B. The lyophilized extracts were incubated with 6 M urea overnight and gel chromatographed in a fast protein liquid chromatography (FPLC) system; calcitonin was measured by radioimmunoassay in the fractions. FPLC disclosed immunoreactive calcitonin of three different molecular sizes in the patients. The two largest forms were approximately 30 and 10 kDa and one eluted at the same position as monomeric calcitonin (3.4 kDa). After extraction and FPLC we found slightly higher calcitonin concentrations in osteoporotic women than previously reported levels in age-matched healthy women. Male patients had higher levels than female patients. None of the osteoporotic patients lacked monomer-like calcitonin. There was no significant correlation between the extracted total or monomer-like calcitonin and bone mineral density of the femoral neck. It is concluded that the circulating calcitonin in both male and female patients comprises three different molecular forms and that there is no deficiency of the monomer-like form. The calcitonin levels in the female patients were slightly higher than in a previous control group.