It is pivotal to assess the toxicity and safety of chemicals, including medicines, in the research field of environmental health science. Here we introduce neurotoxic mechanisms in mammals of environmental organotin and Parkinson's disease-related chemicals. We clarified that low concentrations of tributyltin decrease α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptor subunit GluA2 (GluR2) expression, leading to the vulnerability of cultured neurons. That is, tributyltin reduces GluA2 prior to neuronal death. This GluA2 decrease can be used as a sensitive evaluation index of neurotoxicity, since low levels of certain chemicals, for example some agrochemicals, decrease GluA2 expression. We also elucidated the mechanisms of abnormal protein metabolism induced by low levels of two Parkinson's disease-related chemicals: 1-methyl-4-phenylpyridinium ion (MPP+) and 1,2,3,4-tetrahydroisoquinoline derivatives. It is expected that these findings will become clues in accurately evaluating the toxicity of chemicals and/or in investigating the causes of disease.
Angiotensin (Ang) II, the main bioactive component of the renin-angiotensin system, is reported to participate in either the inhibition or the facilitation of pain transmission depending on brain area. Although Ang II is known to exist in the superficial dorsal horn of the spinal cord, the role of Ang II in spinal pain transmission remains unclear. In order to elucidate that role, we examined the effect of intrathecal administration of Ang II to mice. We found that Ang II produced pain-related behavior accompanied by the phosphorylation of p38 mitogen-activated protein kinase (MAPK) via Ang II type 1 (AT1) receptors, which are highly expressed in the superficial dorsal horn (laminae I and II). In addition, pain-related behavior was caused by acting on spinal neurons and astrocytes that express AT1 receptors. We next examined whether the spinal Ang II system is responsible for diabetic neuropathic pain. In streptozotocin-induced diabetic mice, neuronal Ang-converting enzyme was upregulated in the superficial dorsal horn, which led to an increase in spinal Ang II levels. Furthermore, this increase in Ang II caused mechanical hypersensitivity accompanied by the activation of p38 MAPK via AT1 receptors. In conclusion, our findings suggest that Ang II may act as a neurotransmitter and/or neuromodulator in spinal pain transmission. This review describes our recent efforts regarding the role of spinal Ang II in spinal pain transmission.
Tissues of the small intestine are crucial to understanding drug disposition because these tissues regulate the bioavailability of drugs. However, no evaluation system is currently available for precise and comprehensive analysis of intestinal pharmacokinetics. To address this, functional intestinal epithelial cells were generated from human induced pluripotent stem (iPS) cells for use in pharmacokinetic studies. An improved intestinal differentiation method was established by screening a variety of small molecule compounds against cells during differentiation. The mRNA expression levels of intestinal markers, drug transporters, and CYP3A4 were found to increase following treatment with compounds that act as inhibitors of mitogen-activated protein kinase, DNA methyltransferase, and transforming growth factor-β. Therefore, we inferred that these compounds enhanced differentiation into intestinal epithelial cells. The differentiated intestinal epithelial cells in the presence of these compounds possessed drug-metabolizing enzyme activities, such as those of CYPs, UDP-glucuronosyltransferase, and sulfotransferase. In addition, these cells had the ability to induce CYP3A4 in the presence of 1α,25-dihydroxyvitamin D3. The differentiated intestinal epithelial cells seeded on cell culture inserts formed loose-tight junctions, similar to those in the human small intestine, rather than Caco-2 cells. The cells exhibited polarity, such as apical and basal sides. We also demonstrated that the uptake and efflux transport activities in the cells occurred via peptide transporter and breast cancer resistance protein, respectively. Taken together, it was suggested that human iPS cell-derived intestinal epithelial cells are pharmacokinetically functional, and represent a promising model system for pharmacokinetic studies of drug candidates.
Whereas granulopoiesis during Gram-negative bacterial infection is accelerated through activation of toll-like receptor 4 (TLR4), it has not been elucidated whether Gram-positive bacterial infection can stimulate granulopoiesis. Using the well-known TLR2 agonist peptidoglycan (PGN), it was shown that neutrophils in bone marrow and spleen and plasma granulocyte colony-stimulating factor were increased in mice that had received intraperitoneal administration of PGN. Incorporation of bromodeoxyuridine into bone marrow neutrophils increased in mice administered PGN, demonstrating that PGN promotes granulopoiesis. These results illustrate that bacterial recognition by TLR2 facilitates granulopoiesis during Gram-positive bacterial infection. Thus, granulopoiesis is accelerated to suppress bacterial infection, but some bacteria can still cause severe infections. Clostridium perfringens is a Gram-positive, anaerobic pathogenic bacterium and causes life-threatening gas gangrene in humans. Of the many toxins produced by C. perfringens, α-toxin is known to be a major virulence factor during infection. Recently, it has been revealed that C. perfringens α-toxin impairs the innate immune system by inhibiting neutrophil differentiation, which is crucial for the pathogenesis of C. perfringens. Moreover, the toxin also attenuates erythropoiesis, which would cause severe anemia in clinical settings. The findings provide new insight to understand how hosts strengthen innate immunity to fight pathogenic bacteria and how they evade the hosts' immune systems.
Moderate exercise has been reported to combat several diseases, including cardiovascular diseases and depressants. However, many patients do not have ability to undergo exercise therapy due to aging and severity of the symptoms. Therefore development of new drugs that can imitate exercise therapy is desired and actually studied worldwide. The heart is one of the physical load-responsive target organs such as skeletal muscles and vascular smooth muscles. The heart can adapt from environmental stress by changing its structure and morphology (i.e., remodeling). Physiological remodeling, caused by exercise or pregnancy, can be defined by compensative and reversible changes to the heart, whereas pathological remodeling can be defined by irreversible changes of the heart, through aberrant calcium ion (Ca2+) signaling as well as production of reactive oxygen species (ROS). However, crosstalk between Ca2+ and ROS remains obscure. In this review we will introduce our recent findings on the functional crosstalk between transient receptor potential canonical (TRPC) 3 and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) 2 as a novel molecular target to mimic exercise therapy.
Hemodynamic stresses, including hypertension and myocardial infarction, activate neurohumoral factors such as the sympathetic nervous system and the renin-angiotensin system, and can lead to the progression of heart failure. Established pharmacological agents such as angiotensin II receptor blockers (ARBs), angiotensin-converting enzyme (ACE) inhibitors, and β-blockers target extra-cellular molecules and receptors on the cell membrane. These agents have shown some efficacy for the treatment of heart failure, but the long-term survival rate of patients with heart failure remains low. Additional effective pharmacological approaches are urgently required. Our previous studies have demonstrated that curcumin, a natural polyphenol derived from the root of Curcuma longa, prevented the development of heart failure in rat models of myocardial infarction and hypertensive heart disease. However, until recently curcumin's poor water solubility and extremely low bioavailability have presented serious challenges to its clinical applicability. In recent years, highly absorbable curcumin preparations have been developed using methods such as nanoparticle formation and micellization, and there are now high expectations for their wide clinical application. Our group has developed a highly absorbable curcumin formulation called Theracurmin using nanoparticulation and surface processing techniques. Our preliminary data indicated that Theracurmin may improve left ventricular diastolic function. Furthermore, we have already completed and are currently carrying out several clinical trials using Theracurmin against heart failure-related diseases. This paper summarizes and discusses the potential clinical applications of curcumin, focusing on our highly absorbable curcumin formulation, Theracurmin.
Skeletal muscle atrophy reduces quality of life and increases mortality. However, there are few available drugs for the treatment of muscle atrophy. Recently, cell signaling pathways involved in skeletal muscle atrophy or hypertrophy have been determined. To develop drugs for skeletal muscle atrophy, we have studied compounds which modulate pathways of myogenic differentiation, a pivotal step for the maintenance of skeletal muscle mass. First, we examined a K+ channel opener on myogenic differentiation, since hyperpolarization is a trigger for skeletal muscle differentiation. 5,6-Dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), an opener of the small/intermediate conductance Ca2+ activated K+ (SKCa/IKCa) channels, increases myogenic differentiation in C2C12 mouse skeletal myoblasts. This effect was inhibited by TRAM-34, an IKCa channel blocker. This suggests that K+ channels in skeletal muscle stem cells are potential targets for an anti-muscle atrophy drug. Next, we searched for drugs which prevent sepsis-induced muscle atrophy. Lipopolysaccharide (LPS), an inducer of sepsis, attenuates myogenic differentiation in C2C12 myoblasts. LPS also increases the protein expression of myostatin and activates NFκB during differentiation. The TLR4 signal inhibitor TAK-242, and an anti-TNFα neutralizing antibody, reduce these inflammatory responses. Our data suggest that LPS inhibits myogenic differentiation via the NFκB/TNFα pathway. This pathway may be involved in the development of muscle wasting caused by sepsis.
Sarcopenia is the decrease in skeletal muscle mass and muscular function that occurs with aging. The underlying mechanisms of sarcopenia include anabolic resistance, which is defined as a poor muscle protein synthetic response to previously effective stimuli such as nutrients and exercise. Among the nutrients that humans ingest, amino acids directly trigger the synthesis of muscle proteins. The essential amino acid leucine, in particular, functions as a stimulatory signal. Leucine-enriched essential amino acids help overcome anabolic resistance in elderly individuals to effectively stimulate muscle protein synthesis. Long-term intake of leucine-enriched essential amino acids has a synergistic effect with exercise to increase skeletal muscle mass, strength, and walking speed in elderly individuals, and can be an effective countermeasure to sarcopenia.
Exercise is generally considered to have health benefits for the body, although its beneficial mechanisms have not been fully elucidated. Recent progressive research suggests that myokines, bioactive substances secreted from skeletal muscle, play an important role in mediating the benefits of exercise. There are three types of myokines in terms of the muscular secretion mechanism: those in which the secretion is promoted by stimulation, such as irisin, interleukin (IL)-6, and IL-15; those whose secretion is constitutive, such as thioredoxin, glutaredoxin, and peroxiredoxin; and those whose secretion is suppressed by stimulation, such as by a macrophage migration inhibitory factor. Although dozens of myokines have been reported, their physiological roles are not well understood. Therefore, there currently exists no advanced drug discovery research specifically targeting myokines, with the exception of Myostatin. Myostatin was discovered as a negative regulator of muscle growth. Myostatin is secreted from muscle cells as a myokine; it signals via an activin type IIB receptor in an autocrine manner, and regulates gene expressions involved in myogenesis. Given the studies to date that have been conducted on the utilization of myostatin inhibitors for the treatment of muscle weakness, including cachexia and sarcopenia, other myokines may also be new potential drug targets.
Physical exercise is well known to be beneficial to our health. Therapeutic exercise is widely applicable to metabolic disorders, including obesity and diabetes. In addition, recent studies have suggested its potential benefit in the treatment of more various diseases such as mental disorders and cancer. 5′AMP-activated protein kinase (AMPK), which is an intracellular central metabolic sensor as well as a regulator, has been demonstrated to play significant roles in the contracting skeletal muscles, suggesting that AMPK should be one of the key molecules mediating metabolic effects during physical exercise. Therefore, AMPK is a desirable therapeutic target for drug discovery. In the symposium S41 held in the 137th Annual Meeting of the Pharmaceutical Society of Japan, our data on the molecular mechanisms of isoform-specific postprandial suppression of AMPK activity were shared, and we discussed potential roles of AMPK as an intersection where metabolic signals by physical exercise and feeding status crosstalk. Here, I would like to introduce basic knowledge related to AMPK and recent findings regarding how AMPK activity is regulated in response to physiological and pharmacological stimulation.
A molecular clock exists within almost all organizations in a living body, and these clocks influence the periodicity of many physiological phenomena such as eating behaviors, the sleep-wake cycle, and hormone secretion. Especially, a living body's energy metabolism is involved with the molecular clocks genetically driven in peripheral tissues, which act in strong relation to eating rhythms. However, the possibility that rhythms may also have an inverse influence has recently been pointed out. In this manuscript, we review the outline of circadian rhythms, then refer to the possibility that a clock gene in the peripheral tissues, capable of being changed by eating rhythms, may influence sleep-wake regulation and energy metabolism.
Similar-appearing press-through package (PTP) sheets (also known as blister packs) that contain different medicines may result in incorrect medication due to confusion errors. To evaluate the significance of this problem and to identify the factors that may lead to such errors, we conducted a questionnaire survey for pharmacists. Three hundred and eighty-two pairs of PTP sheets with similar appearance were included in the questionnaire. Factors related to color (sheet color at the front of the sheet 90.9%, color of tablet/capsule 57.1%, print color at the front of the sheet 45.9%) were most frequently selected as influencing the perceived similarity of the reported pairs, followed by tablet/capsule shape (46.2%), sheet size (32.4%), and mark and character positioning on sheets (6.8%). In the pairs of similar PTP sheets, pairs manufactured by the same pharmaceutical company accounted for 15%. The frequency of confusion errors or near-errors due to similar appearance of PTP sheets was highest at the time of collecting PTP sheets from the medicine shelf and returning the sheets to the medicine shelf, followed by the time of inspection of prepared medicines and medication instructions. The questionnaire results also indicate that patients themselves can confuse similar PTP sheets and take the wrong medicine. Further quantitative studies are needed to clarify the key factors that cause confusion errors due to similar appearance and to identify potential remedial measures.
Similar-appearing PTP sheets (a.k.a. blister packs) that contain different medicines may result in incorrect medication due to confusion errors. To identify the factors that may lead to such errors, the authors conducted a questionnaire survey for pharmacists. Factors related to color (sheet, tablet/capsule, print) were most frequently selected as influencing the perceived similarity. The questionnaire results also indicate that patients themselves can confuse similar PTP sheets. Further quantitative studies are looked forward to clarify the key factors causing confusion errors.
The increase in medical expenditure has been worsening and poses a serious social problem. Commonly, leftover drugs are retained by patients. We estimated the possible reduction in prescription rates by appropriately reusing leftover drugs, and investigated the medication efficacy classifications that render leftover drugs due to the medication non-adherence. A retrospective cross-sectional survey of prescription data was performed at community pharmacies engaged in the appropriate reuse of leftover drugs through the SETSUYAKU-BAG campaign. We evaluated the drug costs and number of drugs originally prescribed, the reduction in expenditure and numbers after the use of leftover drugs, and then calculated the prescription reduction ratio (PRR) based on the number of drugs. Factors contributing to non-adherence were analyzed by the PRR. After reviewing the prescription information of 1792 patients, the reduction rate in drug expenditure was found to be 20.1%. Purgatives, Chinese medicines, and agents for peptic ulcer had higher PRRs and belonged to the top ten medications according to the prescription efficacy classifications. Non-adherence associated with the medication efficacy classifications was assessed by analyzing 5466 formulations. Thirty percent of formulations were found to be non-adherent. According to the medication efficacy classifications, six medications including agents for hyperlipidemias, peptic ulcer, psychotropics agents, and others, were less adherent than antihypertensives. These results suggest that adjusting prescriptions by appropriately reusing leftover drugs in community pharmacies could reduce medical costs. Further considerations are necessary for improving medication adherence in Japan. Healthcare providers should monitor medication adherence more carefully, with the results identified in this study.
Incretin-based therapy consists of dipeptidyl peptidase-4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists. Whether switching from DPP-4 inhibitors to one of the GLP-1 receptor agonists, dulaglutide, has greater beneficial effects remains unknown. Therefore, this study aimed to investigate the effectiveness of switching from DPP-4 inhibitors to dulaglutide in four patients with type 2 diabetes. All four patients with hyperglycemia who switched from DPP-4 inhibitors to dulaglutide demonstrated noticeable decreased plasma glucose levels on the next day after switching. Two of the patients observed maintained a decreased plasma glucose level over 14 day after switching. Moreover, all patients demonstrated decreased glycosylated hemoglobin A1c levels during the observation period (1-6 months) after switching and lost weight from 6 to 27 day. Minor and manageable hypoglycemia, nausea, and diarrhea were observed as side effects in one case. The current findings suggest that dulaglutide is a suitable treatment alternative in patients with type 2 diabetes who are not currently achieving adequate glycemic control with DPP-4 inhibitors.