To clarify the regulation of drug absorption by the enteric nervous system, we investigated how adrenergic agonists (adrenaline (ADR), clonidine (CLO), dobutamine (DOB)) and dibutyryl cAMP (DBcAMP) ...affected P-glycoprotein (P-gp) function by utilizing isolated rat jejunal sheets and Caco-2 cell monolayers. ADR and CLO significantly decreased the secretory transport (P
) of rhodamine-123 and tended to decrease the transport via P-gp (P
) and passive transport (P
). In contrast, DBcAMP significantly increased and DOB tended to increase P
and both tended to increase P
and P
. Changes in P-gp expression on brush border membrane by adrenergic agonists and DBcAMP were significantly correlated with P
, while P-gp expression was not changed in whole cell homogenates, suggesting that the trafficking of P-gp would be responsible for its functional changes. P
was inversely correlated with transmucosal or transepithelial electrical resistance, indicating that adrenergic agonists affected the paracellular permeability. Adrenergic agonists also changed cAMP levels, which were significantly correlated with P
. Furthermore, protein kinase A (PKA) or PKC inhibitor significantly decreased P
in Caco-2 cell monolayers, suggesting that they would partly contribute to the changes in P-gp activity. In conclusion, adrenergic agonists regulated P-gp function and paracellular permeability, which would be caused via adrenoceptor stimulation.
Serum uric acid (UA) concentration is linked to the risk of progression of Parkinson's disease (PD).
The aim of this study was to examine the association between serum UA concentration and the ...occurrence of wearing-off fluctuation (WOF) in Japanese PD patients.
A total of 123 Japanese patients with PD were enrolled in this study. We collected data on demographics, clinical features, medications, and laboratory findings including serum UA concentration, and examined the presence of WOF. The association between serum UA concentration and WOF was assessed using multivariate logistic regression analysis.
After adjusting for possible confounders, it was found that the odds ratio (OR) for WOF decreased with increasing quartile of UA (highest quartile vs. lowest quartile, adjusted OR 0.218, 95% confidence interval CI 0.053-0.891). This association was significant only in male PD patients, regardless of the use of sex-specific quartiles of UA. Additionally, disease duration (OR 7.80, 95% CI 2.62-23.17) and daily levodopa dosage (OR 4.06, 95% CI 1.45-11.38) were associated with the occurrence of WOF.
Our results showed that serum UA concentration was associated with the occurrence of WOF. Serum UA concentration may be a predictive factor for WOF.
It is well known that the enteric nervous system (ENS) regulates the movement and function of the small intestine, but the effects of ENS on drug absorption from the small intestine still remain to ...be clarified. Focusing on adrenergic effect, we tried to evaluate how adrenergic stimulation influences the drug absorption via passive diffusion using Caco-2 cells as model epithelial cells, a terminal effector of ENS. Adrenaline, an adrenergic agonist, did not affect the transport of small molecules such as antipyrine, phenacetin and mannitol, but decreased the transport of large molecules such as FITC-dextran (FD)-20 and FD-40 without transepithelial electrical resistance (TEER) change. These results suggested that the transport of large molecules via paracellular route would be attenuated by adrenergic stimulation. Only clonidine, an α2-agonist, among selective adrenoceptor agonists decreased FD-40 transport across Caco-2 cell monolayers and the agonist also decreased intracellular cAMP. Furthermore, H-89, a protein kinase A inhibitor, significantly decreased FD-40 transport and dibutyryl cAMP, a cAMP derivative, increased it. These results suggest that the decrease in FD-40 transport would be mainly attributed to the decrease in intracellular cAMP and subsequent decrease in PKA activity via α2-receptor stimulation.
Purpose
Serotonin (5-HT) is important for gastrointestinal functions, but its role in drug absorption remains to be clarified. Therefore, the pharmacokinetics and oral absorption of cephalexin (CEX) ...were examined under 5-HT-excessive condition to understand the role of 5-HT.
Methods
5-HT-excessive rats were prepared by multiple intraperitoneal dosing of 5-HT and clorgyline, an inhibitor for 5-HT metabolism, and utilized to examine the pharmacokinetics, absorption behavior and the intestinal permeability for CEX.
Results
Higher levels of 5-HT in brain, plasma and small intestines were recognized in 5-HT-excessive rats, where the oral bioavailability of CEX was significantly enhanced. The intestinal mucosal transport via passive diffusion of CEX was significantly increased, while its transport via PEPT1 was markedly decreased specifically in the jejunal segment, which was supported by the decrease in PEPT1 expression on brush border membrane (BBM) of intestinal epithelial cells. Since no change in antipyrine permeability and significant increase in FITC dextran-4 permeability were observed in 5-HT-excessive rats, the enhanced permeability for CEX would be attributed to the opening of tight junction, which was supported by the significant decrease in transmucosal electrical resistance. In 5-HT-excessive rats, furthermore, total body clearance of CEX tended to be larger and the decrease in PEPT2 expression on BBM in kidneys was suggested to be one of the reasons for it.
Conclusions
5-HT-excessive condition enhanced the oral bioavailability of CEX in rats, which would be attributed to the enhanced permeability across the intestinal mucosa via passive diffusion through the paracellular route even though the transport via PEPT1 was decreased.
Abstract
Background
The anti‐paraneoplastic (Ma2/Ta) antibody is related to testicular, lung and ovarian cancers, and might cause paraneoplastic neurological disorders.
Case presentation
We present a ...25‐year‐old woman presenting various neurological symptoms of myokymia, chronic widespread pain, tremor, excessive daytime sleepiness, impaired eye of movements, and seizures and autonomic symptoms related to anti‐Ma2/Ta antibodies. Needle electromyography showed spontaneous multiplet and myokymic discharges in the left vestus lateralis. Thus, we diagnosed her as Morvan syndrome. After initiation of steroids, plasma exchange and dantrolene, her symptoms partially improved with decreasing intensity of the antigen of anti‐Ma2/Ta antibodies, from moderate strong to borderline.
Conclusions
The present case expands the clinical spectrum of anti‐Ma2/Ta antibodies‐related disorders to include the existence of neuroimmune activation and Morvan syndrome.
Marchiafava–Bignami disease is a rare, alcohol‐associated disease that primarily involves corpus callosum demyelination. As these corpus callosum lesions increase in size, they can affect the optic ...chiasm, optic tract and other white matter regions. Here, we report a case that includes the autopsy findings in a 53‐year‐old man diagnosed with Marchiafava–Bignami disease. The patient developed a visual impairment that preceded a consciousness disturbance by 6 months. Histopathological examination showed optic tract, deep white matter and corpus callosum involvement. Although Marchiafava–Bignami disease can affect the optic tract, visual impairment is not reported as an initial symptom of Marchiafava–Bignami disease. We propose that visual impairment in patients with chronic alcohol abuse might be an early symptom of Marchiafava–Bignami disease.
The ubiquitin (Ub) kinase PINK1 and the E3 Ub ligase Parkin, two gene products associated with young-onset Parkinson's disease (PD), participate in mitochondrial quality control. The phosphorylation ...of mitochondrial polyUb by PINK1, which is activated in a mitochondrial membrane potential (ΔΨm)-dependent manner, facilitates the mitochondrial translocation and concomitant enzymatic activation of Parkin, leading to the clearance of phospho-polyUb-tagged mitochondria via mitophagy. Thus, Ub phosphorylation is a key event in PINK1-Parkin-mediated mitophagy. Here, we examined the role of phospho-Ub signaling in the pathogenesis of PD using fly PD models, human brain tissue and dopaminergic neurons derived from induced pluripotent stem cells (iPSCs) containing Parkin or PINK1 mutations, as well as normal controls. We report that phospho-Ub signaling is highly conserved between humans and Drosophila, and that phospho-Ub signaling and the relocation of axonal mitochondria upon ΔΨm reduction are indeed compromised in human dopaminergic neurons containing Parkin or PINK1 mutations. Moreover, phospho-Ub signaling is prominent in tyrosine hydroxylase-positive neurons compared with tyrosine hydroxylase-negative neurons, suggesting that PINK1-Parkin signaling is more required for dopaminergic neurons. These results shed light on the particular vulnerability of dopaminergic neurons to mitochondrial stress.
Abstract
Mutations in CHCHD2 are linked to a familial, autosomal dominant form of Parkinson’s disease (PD). The gene product may regulate mitochondrial respiratory function. However, whether ...mitochondrial dysfunction induced by CHCHD2 mutations further yields α-synuclein pathology is unclear. Here, we provide compelling genetic evidence that mitochondrial dysfunction induced by PD-linked CHCHD2 T61I mutation promotes α-synuclein aggregation using brain autopsy, induced pluripotent stem cells (iPSCs) and Drosophila genetics. An autopsy of an individual with CHCHD2 T61I revealed widespread Lewy pathology with both amyloid plaques and neurofibrillary tangles that appeared in the brain stem, limbic regions and neocortex. A prominent accumulation of sarkosyl-insoluble α-synuclein aggregates, the extent of which was comparable to that of a case with α-synuclein (SNCA) duplication, was observed in CHCHD2 T61I brain tissue. The prion-like activity and morphology of α-synuclein fibrils from the CHCHD2 T61I brain tissue were similar to those of fibrils from SNCA duplication and sporadic PD brain tissues. α-Synuclein insolubilization was reproduced in dopaminergic neuron cultures from CHCHD2 T61I iPSCs and Drosophila lacking the CHCHD2 ortholog or expressing the human CHCHD2 T61I. Moreover, the combination of ectopic α-synuclein expression and CHCHD2 null or T61I enhanced the toxicity in Drosophila dopaminergic neurons, altering the proteolysis pathways. Furthermore, CHCHD2 T61I lost its mitochondrial localization by α-synuclein in Drosophila. The mislocalization of CHCHD2 T61I was also observed in the patient brain. Our study suggests that CHCHD2 is a significant mitochondrial factor that determines α-synuclein stability in the etiology of PD.
Individual taste sensitivity influences food preferences, nutritional control, and health, and differs greatly between individuals. The purpose of this study was to establish a method of measuring ...and quantifying an individual's taste sensitivity and to evaluate the relationship between taste variation and genetic polymorphisms in humans using agonist specificities of the bitter taste receptor gene, TAS2R38, with the bitter compound 6-n-propylthiouracil (PROP). We precisely detected the threshold of PROP bitter perception by conducting the modified two-alternative forced-choice (2AFC) procedure with the Bayesian staircase procedure of the QUEST method and examined genetic variation in TAS2R38 in a Japanese population. There were significant differences in PROP threshold between the three TAS2R38 genotype pairs for 79 subjects: PAV/PAV vs AVI/AVI, p < 0.001; PAV/AVI vs AVI/AVI, p < 0.001; and PAV/PAV vs PAV/AVI, p < 0.01. Our results quantified individual bitter perception as QUEST threshold values: the PROP bitter perception of individuals with the PAV/PAV or PAV/AVI genotypes was tens to fifty times more sensitive than that of an individual with the AVI/AVI genotype. Our analyses provide a basic model for the accurate estimation of taste thresholds using the modified 2AFC with the QUEST approach.
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