Is there a rational basis for cannabinoids research and development in ocular pain therapy? A systematic review of preclinical evidence.

BACKGROUND: Purpose of the present systematic review is to investigate preclinical evidence in favor of the working hypothesis of efficacy of cannabinoids in ocular pain treatment. METHODS: Literature search includes the most relevant repositories for medical scientific literature from inception until November, 24 2021. Data collection and selection of retrieved records adhere to PRISMA criteria. RESULTS: In agreement with a priori established protocol the search retrieved 2471 records leaving 479 results after duplicates removal. Eleven records result from title and abstract screening to meet the inclusion criteria; only 4 results are eligible for inclusion in the qualitative synthesis impeding meta-analysis. The qualitative analysis highlights the antinociceptive and anti-inflammatory efficacy of Δ8-tetrahydrocannabinol, cannabidiol and its derivative HU-308 and of new racemic CB1 allosteric ligand GAT211 and its enantiomers GAT228 and GAT229. Moreover, CB2R agonists RO6871304 and RO6871085 and CB2R ligand HU910 provide evidence of anti-inflammatory efficacy. CB2 agonist HU308 reduces of 241% uveitis-induced leukocyte adhesion and changes lipidome profile. Methodological and design issues raise concern of risk of bias and the amount of studies is too small for generalization. Furthermore, the ocular pain model used can resemble only inflammatory but not neuropathic pain. CONCLUSIONS: The role of the endocannabinoid system in ocular pain is underinvestigated, since only two studies assessing the effects of cannabinoid receptors modulators on pain behavior and other two on pain-related inflammatory processes are found. Preclinical studies investigating the efficacy of cannabinoids in ocular inflammatory and neuropathic pain models are needed to pave the way for clinical translation.

Pollinosis and all-cause mortality among middle-aged and elderly Japanese: a population-based cohort study.

BACKGROUND: Having an allergic disease may have health implications beyond those more commonly associated with allergy given that previous epidemiological studies have suggested that both atopy and allergy are linked to mortality. More viable immune functioning among the elderly, as indicated by the presence of an allergic disease, might therefore be associated with differences in all-cause mortality. OBJECTIVE: Using data from a Japanese cohort, this study examined whether having pollinosis (a form of allergic rhinitis) in a follow-up survey could predict all-cause and cause-specific mortality. METHODS: Data came from the Komo-Ise cohort, which at its 1993 baseline recruited residents aged 40-69 years from two areas in Gunma prefecture, Japan. The current study used information on pollinosis that was obtained from the follow-up survey in 2000. Mortality and migration data were obtained throughout the follow-up period up to December 2008. Proportional hazard models were used to examine the relation between pollinosis and mortality. RESULTS: At the 2000 follow-up survey, 12% (1088 of 8796) of respondents reported that they had pollinosis symptoms in the past 12 months. During the 76 186 person-years of follow-up, 748 died from all causes. Among these, there were 37 external, 208 cardiovascular, 74 respiratory, and 329 neoplasm deaths. After adjusting for potential confounders, pollinosis was associated with significantly lower all-cause [hazard ratio 0.57 (95% confidence interval = 0.38-0.87)] and neoplasms mortality [hazard ratio 0.48 (95% confidence interval = 0.26-0.92)]. CONCLUSIONS AND CLINICAL RELEVANCE: Having an allergic disease (pollinosis) at an older age may be indicative of more viable immune functioning and be protective against certain causes of death. Further research is needed to determine the possible mechanisms underlying the association between pollinosis and mortality.

Omega-3 polyunsaturated fatty acids ameliorate the severity of ileitis in the senescence accelerated mice (SAM)P1/Yit mice model.

Clinical studies using omega-3 polyunsaturated fatty acids (omega3-PUFA) to Crohn's disease (CD) are conflicting. Beneficial effects of dietary omega3-PUFA intake in various experimental inflammatory bowel disease (IBD) models have been reported. However, animal models of large intestinal inflammation have been used in all previous studies, and the effect of omega3 fat in an animal model of small intestinal inflammation has not been reported. We hypothesized that the effects of omega3 fat are different between large and small intestine. The aim of this study was to determine whether the direct effect of omega3 fat is beneficial for small intestinal inflammation. Senescence accelerated mice (SAM)P1/Yit mice showed remarkable inflammation of the terminal ileum spontaneously. The numbers of F4/80-positive monocyte-macrophage cells as well as beta7-integrin-positive lymphocytes in the intestinal mucosa were increased significantly compared with those in the control mice (AKR-J mice). The area of mucosal addressin cell adhesion molecule-1 (MAdCAM-1)-positive vessels was also increased. The degree of expression levels of monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-6 and interferon (IFN)-gamma mRNA were increased significantly compared with those in the control mice. The feeding of two different kinds of omega3 fat (fish-oil-rich and perilla-oil-rich diets) for 16 weeks to SAMP1/Yit mice ameliorated inflammation of the terminal ileum significantly. In both the omega3-fat-rich diet groups, enhanced infiltration of F4/80-positive monocytes/macrophages in intestinal mucosa of SAMP1/Yit mice cells and the increased levels of MCP-1, IL-6 and IFN-gamma mRNA expression were ameliorated significantly compared with those in the control diet group. The results suggest that omega3 fat is beneficial for small intestinal inflammation by inhibition of monocyte recruitment to inflamed intestinal mucosa.

Effect of Ginkgo biloba (EGb 761) on differential gene expression.

Supplementation of diets with plant extracts such as ginkgo biloba extract (EGb 761) (definition see editorial) for health and prevention of degenerative diseases is popular. However, it is often difficult to analyse the biological activities of plant extracts due to their complex nature and the possible synergistic and/or antagonistic effects of their components. Genome-wide expression monitoring with high-density oligonucleotide arrays provides one way to examine the molecular targets of plant extracts and may prove a useful tool in evaluating their therapeutic claims. Here, we will briefly describe some of our work on the effect of EGb 761 on differential gene expression in relation to its potential anti-carcinogenic, photoprotective and neuromodulatory properties.

The in vivo neuromodulatory effects of the herbal medicine ginkgo biloba.

Extracts of Ginkgo biloba leaves are consumed as dietary supplements to counteract chronic, age-related neurological disorders. We have applied high-density oligonucleotide microarrays to define the transcriptional effects in the cortex and hippocampus of mice whose diets were supplemented with the herbal extract. Gene expression analysis focused on the mRNAs that showed a more than 3-fold change in their expression. In the cortex, mRNAs for neuronal tyrosine/threonine phosphatase 1, and microtubule-associated tau were significantly enhanced. Hyperphosphorylated tau is the major constituent of the neurofibrillary tangles in the brains of Alzheimer's disease patients. The expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-2, calcium and chloride channels, prolactin, and growth hormone (GH), all of which are associated with brain function, were also up-regulated. In the hippocampus, only transthyretin mRNA was upregulated. Transthyretin plays a role in hormone transport in the brain and possibly a neuroprotective role by amyloid-beta sequestration. This study reveals that diets supplemented with Ginkgo biloba extract have notable neuromodulatory effects in vivo and illustrates the utility of genome-wide expression monitoring to investigate the biological actions of complex extracts.

Studies on the constituents of bark of Parameria laevigata Moldenke.

One new trimeric proanthocyanidin, epicatechin-(2beta-->O-->7, 4beta-->6)-epicatechin-(2beta-->O--->7, 4beta-->8)-epicatechin (5) and two new tetrameric proanthocyanidins, epicatechin-(2beta-->O-->7, 4beta-->8)-[epicatechin-(4beta-->6)]-epicatechin-(4beta-->8)-epicatechin, named as parameritannin A-1 (6), and epicatechin-(2beta-->O-->5, 4beta-->6)-[epicatechin-(2beta-->O-->7, 4beta-->8)]-epicatechin-(4beta-->8)-epicatechin, named as parameritannin A-2 (7), have been isolated from the bark of Parameria laevigata Moldenke (Apocynaceae) along with the two known dimers, proanthocyanidin A-2 (1) and proanthocyanidin A-6 (2), and two trimers, cinnamtannin B-1 (3) and aesculitannin B (4). These structures were elucidated by spectral and chemical evidence.

[Selenium deficiency and brain functions: the significance for methylmercury toxicity].

Selenium has been long recognized as one of the essential trace elements. Although many selenoproteins have been identified in the last decade, the physiological roles of Se and selenoproteins remain to be elucidated. Since iodothyronine deiodinases (DIs), which regulate the tissue levels of thyroid hormone, are (likely to be) selenoproteins, Se might have specific roles for developing brain. In fact, when rodents are depleted of Se perinatally, the thyroid hormone economy of the fetus is disturbed, which may lead to the abnormal development of the brain and to the abnormal postnatal behavior observed in Se-deficient animals. When the animals were depleted of Se after weaning, when the role of thyroid hormone on brain development is minimal, neurochemical and neurophysiological alterations were found in the dopaminergic system. These postnatally-depleted rodents also showed abnormal open-field behavior, which was distinct from that observed with perinatally-depleted animals. The molecular events that convert Se-deficient status to these neurochemical, neurophysiological, and behavioral functions are largely unknown, and need to be further examined. The interaction between Se and mercury compounds has also been the focus of many research, but there have been few reports on the interaction between the physiological (nutritional) level of Se and the toxicity of prenatal methylmercury (MeHg). Experimental findings showed that Se-deficient rodents are more susceptible to the prenatal toxicity of MeHg. It is noteworthy that MeHg specifically altered the metabolism of Se in fetal/neonatal brain. Significance of the alteration of the activities of selenoenzymes such as glutathione peroxidase and DIs in animals by prenatal MeHg exposure are discussed in relation to the neurobehavioral toxicity of MeHg.

Efficacy of yeast phytase in improving phosphorus bioavailability in a corn-soybean meal-based diet for growing pigs.

Crossbred barrows (n = 66; 6 wk old) were used in a 6-wk experiment to evaluate the efficacy of phytase from yeast or Aspergillus niger on performance, tibial characteristics, and serum inorganic P concentration. We also investigated the stability of these phytases in acidic solutions with pepsin, which simulated gastric conditions. Pigs were fed a P-adequate diet containing .34% nonphytate-P or a low-P diet containing .20% nonphytate-P. The low-P diet was supplemented with 0, 1,000, 2,000, or 4,000 phytase units (PU; the activity at optimal pH, i.e., pH 4.2 for yeast phytase and pH 5.5 for phytase from Aspergillus niger)/kg of yeast phytase, or 1,000 PU/kg phytase from Aspergillus niger. The graded level of yeast phytase linearly increased ADG (P = .047), tibial weight (P = .091), tibial density (P < .001), and P concentration in tibial cortex (P = .018). Aspergillus niger phytase also increased ADG (P = .022), serum inorganic P concentration (P < .001), tibial density (P = .007), and tibial P concentration (P = .025). The pigs given 1,000 PU/kg Aspergillus niger phytase showed greater ADG (P = .091), tibial density (P= .001), and tibial P concentration (P = .062) than those given 1,000 PU/kg yeast phytase. No measurements differed (P > .31) between the pigs given 1,000 PU/kg Aspergillus niger phytase and those given 4,000 PU/kg yeast phytase. These results suggested that yeast phytase improves bioavailability of P in the diet for growing pigs but the efficacy of yeast phytase is less than that of Aspergillus niger phytase. During incubation in acidic solutions with pepsin, yeast phytase (P < .001) lost more of its activity than Aspergillus niger phytase. This lesser stability of yeast phytase may be responsible for the poorer efficacy of yeast phytase than that of Aspergillus niger. In summary, supplementation of swine diets with yeast phytase is beneficial, but its efficacy is less than that of Aspergillus niger phytase.

In utero methylmercury exposure differentially affects the activities of selenoenzymes in the fetal mouse brain.

Pregnant ICR mice were subcutaneously injected with 0,5, or 3x3 mg Hg/kg of methylmercury (MeHg) on days 12,13, and 14(G12-14) of gestation and were sacrificed on G17. Activity of selenoenzymes, including glutathione peroxidase (GPx) and 5'- or 5-iodothyronine deiodinases (5'-DI, 5-DI), was determined in fetal brain and placenta. MeHg did not affect the concentration of Se in these tissues, while it significantly inhibited the activity of GPx in the fetal brain and placenta, but not in the maternal brain. Although the levels of thyroid hormones in the maternal and fetal plasma were not affected by MeHg, 5-DI decreased and 5'-DI increased in the fetal brain, as if they had responded to hypothyroidism. Because the level of T4 in the fetal plasma was not affected by MeHg, these changes in enzymatic activities may result in a harmful excess of T3 in the fetal brain. In addition, 5-DI activity was increased in the placenta of MeHg-treated mice. These effects of prenatal MeHg exposure on fetal and placental DIs differed from those of dietary-induced Se deficiency, where the activities of DIs were decreased or not affected. Further evaluation of the effect of MeHg on selenoenzymes, especially 5-DIs, is warranted.

In utero exposure to methylmercury and Se deficiency converge on the neurobehavioral outcome in mice.

Pregnant female ICR mice, maintained on torula-based diets containing various amounts of Se (0.02, 0.05, or 0.4 mg/kg diet), were given methyl-mercury (MeHg; 0, 5, or 9 mg Hg/kg in total) on the 12-14th days of gestation. The neurobehavioral function of the offspring born to these dams was evaluated with respect to reflex and motor development, thermal preference, and open-field activity. Se deficiency per se as well as exposure to MeHg exerted additive or synergistic effects on the neurobehavioral functions examined. The group of mice most affected was the group given the lowest amount of Se and the highest dose of MeHg. Thus, the neurobehavioral outcome of in utero MeHg exposure and Se deficiency converged. Although the dietary level of Se did not affect the Hg concentration in the fetal brain, the Se concentration and the activity of glutathione peroxidase, a selenoenzyme, were severely depressed by MeHg in the neural tissue. The possibility that functional Se deficiency by MeHg exposure partly accounts for the neurobehavioral toxicity of MeHg is discussed.

Separation of selenium-containing proteins in human and mouse plasma using tandem high-performance liquid chromatography columns coupled with inductively coupled plasma-mass spectrometry.

An analytical method that uses two different high-performance liquid chromatography (HPLC) columns in tandem has been developed that separates three major selenium-containing proteins (albumin, glutathione peroxidase, and selenoprotein P) found in human blood plasma. The first column was a heparin affinity column and the second was a gel filtration column whose outlet was directly connected to an inductively coupled plasma-mass spectrometer. The method successfully separated plasma selenium into the three selenium-containing proteins and revealed the preferential retention of selenium in the form of selenoprotein P in a selenium-deficient human and in selenium-deficient mice. Our results also confirm the results of previous studies that showed a preference for supplemented selenium to be taken up as selenoprotein P in rats. Advantages of the tandem column method are that it allows rapid and convenient analyses of the distribution of plasma selenium, and that it is suitable for stable isotope tracer studies and metal interaction studies.

Effects of mild chronic heat exposure on the concentrations of thiobarbituric acid reactive substances, glutathione, and selenium, and glutathione peroxidase activity in the mouse liver.

To determine whether mild and chronic heat stress leads to oxidative stress and to differentiate such effects of different exposure periods, we kept male ICR-mice at an ambient temperature of either 35 degrees C or 25 degrees C for 6 hours, 3 days, or 7 days and measured the concentrations of thiobarbituric acid reactive substances (TBARS), glutathione (GSH), selenium (Se), and glutathione peroxidase (GSH-Px) activities in the liver. Since the food consumption of the heat-exposed group was only half that of the control, we prepared pair-fed groups, which were kept at 25 degrees C and whose food consumption were limited to those of the heat-exposed group for the 3-day and the 7-day exposure. TBARS concentrations of the liver was significantly higher in the heat group than the control after the 3-day exposure, while there was no significant difference among the groups after the 7-day exposure. There was no significant difference in GSH concentrations between the heat-exposed group and the control after the 7-day exposure, when the GSH concentration of the pair-fed group was significantly lower than that of the control. Hepatic cytosolic Se GSH-Px activity in the heat group was significantly less than that in the control group after the 6-hour exposure and it tended to be lower in the heat group than that of the control group after the 7-day exposure, while there was no difference in the total GSH-Px activity among the three groups. Our results showed that mild and chronic heat exposure may cause oxidative damage to organisms and that GSH-related anti-oxidative systems would play an important role to defensive reaction.

Effect of spikelets of Miscanthus sinensis on IgE-mediated biphasic cutaneous reaction in mice.

The effect of spikelets of Miscanthus sinensis Andersson (M. sinensis) on IgE-mediated biphasic cutaneous reactions was investigated in BALB/c mice. Mice were passively sensitized by an intravenous (i.v.) injection of monoclonal antidinitrophenol IgE antibody (anti-DNP IgE mAb), or actively by an intraperitoneal (i.p.) injection of DNP-derivatized ovalbumin (DNP-OVA) plus aluminium hydroxide gel (Alum) as an adjuvant. Skin reactions were elicited by an epicutaneous challenge of dinitrofluorobenzene (DNFB) and occurred biphasically with peak responses at 1 and 24 h in both animal models. The administrations of a nondialysable water extract of M. sinensis within 2 h before or after DNFB challenge via oral or i.p. route significantly inhibited the biphasic cutaneous reactions in passively and actively sensitized mice. The inhibitory effect was much stronger than those of a glucocorticoid, prednisolone, and histamine release inhibitor, amlexanox, as positive controls. The active component(s) was predominantly located in the glycoprotein fraction by gel chromatography. In the ears of DNFB-challenged mice, this fraction suppressed the accumulation of inflammatory cells, including mast cells and neutrophils/macrophages. In addition, the biphasic ear swelling was also improved by an administration of the glycoprotein fraction 24 h before active sensitization. These findings indicate that the glycoprotein fraction of M. sinensis was able to inhibit not only the IgE-mediated allergic inflammatory reaction but also the IgE formation. Thus, this fraction may be a useful antiallergic therapy.

Deficiency of selenium enhances the K+-induced release of dopamine in the striatum of mice.

To determine whether a selenium (Se) deficiency in the brain leads to a functional change in dopaminergic transmission in the striatum, in vivo microdialysis was conducted in mice fed a low-Se diet. After 11-13 weeks of the diet regimen, the activity of glutathione peroxidase (GPx) in the Se-deficient brain was reduced to 60% of the control brain. A high K+ perfusion (100 mM) increased the level of dopamine in the dialysate to 67 +/- 16 times the basal level; the increase was significantly greater than that observed in the control group (28 +/- 4 times). Such a between-group difference was not observed after 4-5 weeks of the Se-diet. These results indicated that prolonged Se deficiency altered the function of striatal dopaminergic neurons in mice. A possible contribution of enhanced oxidative stress due to the reduced GPx activity is discussed.

Tissue-specific modification of selenium concentration by acute and chronic dexamethasone administration in mice.

Several clinical reports have shown changes in plasma Se concentration with corticosteroid treatments, but the results have been inconsistent. Few experimental studies have been done on this subject. In the present study the effect of dexamethasone (DEX) treatment on Se concentrations and activities of Se-dependent glutathione peroxidase (EC 1.11.1.9; SeGPx) were examined in adult male ICR mice. In the first experiment, DEX was given via drinking water containing 5 or 50 mg DEX/l. At 1 or 3 weeks of DEX treatment, mice were dissected and the Se concentrations as well as SeGPx activities in various tissues, including plasma, were determined. At 1 week the DEX-treated groups had significantly lower hepatic Se concentrations and significantly higher plasma and cerebral concentrations than the control group. The DEX-treated groups showed lower SeGPx activities in the hepatic cytosol and higher SeGPx activities in the plasma than the saline (9 g NaCl/l)-treated group, in parallel with the changes in Se concentrations. At 3 weeks, neither hepatic nor plasma Se concentrations showed a significant change. In the second experiment, mice were injected subcutaneously with DEX and, thereafter, mice were food-deprived. The DEX-injected groups had higher plasma Se concentrations. A similar finding was obtained also when the DEX- or saline-injected mice were not food-deprived. Thus, the difference between the DEX-treated and control groups was possibly caused by redistribution of tissue Se. These results suggested that the effects of DEX on Se concentrations were tissue dependent and that the higher plasma Se observed in DEX-treated groups might be explained by the release of tissue Se into plasma as plasma SeGPx.

[A case of vitamin B12 deficiency with broad neurologic disorders and canities].

The patient was a 48-year-old woman with gait disturbance as her initial symptom. Two years after the onset of the gait disturbance, she developed motor weakness and a sensory disturbance in her limbs, and dementia. On admission to our hospital, the patient's serum vitamin B12 and folic acid levels were low, and she was found to have normochromic anemia. She also had widespread coarse hair and canities was diagnosed. The patient's paresthesia resolved in response to injection of 500 micrograms mecobalamin every other day, and the Hasegawa dementia scale score and the patient's hand grip strength improved. Her gait also improved, and she became able to walk on tiptoe. Her hair returned to normal. Supplementation with high-dose methyl B12 appeared to be effective to some extent in treating a broad range of neurologic disorders besides subacute combined degeneration of the spinal cord. In addition, the hair abnormality may be a marker of vitamin B12 deficiency.

Determination of selenium in the human brain by graphite furnace atomic absorption spectrometry.

For the investigation of neurological disorders, a development of simple and accessible methods for determining selenium in human brain samples is required. We devised a method of determining selenium using graphite furnace atomic absorption spectrometry (GFAAS). An electrodeless discharge lamp provided the sufficient sensitivity to determine brain selenium. The matrix interferences were avoided by using high temperature, a prolonged pyrolysis step, and a palladium matrix modifier. The technique of standard addition was used to evaluate the sample concentrations. The accuracy of the method was confirmed by a bovine liver reference material. The detection limit of selenium was 0.04 ng. The determined selenium concentrations of human brain cortex and white matter were higher than those of putamen (115-155 and 206-222 ng/g wet wt, respectively). These GFAAS values agreed with those obtained by fluorometric analysis (r = 0.91, n = 10). Moreover, the GFAAS values were compatible to those reported by other researchers (99-274 ng/g wet wt), in which selenium concentrations in putamen also tended to be higher than the other two regions. We conclude that GFAAS is useful for selenium analysis in brain samples.

Lessons for neurotoxicology from selected model compounds: SGOMSEC joint report.

The ability to identify potential neurotoxicants depends upon the characteristics of our test instruments. The neurotoxic properties of lead, methylmercury, polychlorinated biphenyls, and organic solvents would all have been detected at some dose level by tests in current use, provided that the doses were high enough and administered at an appropriate time such as during gestation. The adequacy of animal studies, particularly rodent studies, to predict intake levels at which human health can be protected is disappointing, however. It is unlikely that the use of advanced behavioral methodology would alleviate the apparent lack of sensitivity of the rodent model for many agents.

Distribution of selenium in human plasma detected by high performance liquid chromatography-plasma ion source mass spectrometry.

The distribution of selenium in human plasma has been investigated by high performance liquid chromatography (HPLC) connected directly to inductively coupled plasma mass spectrometry (ICP-MS). Human plasma was loaded on to a size exclusion column and eluted with 0.01 M sodium phosphate buffer (pH 7.0) at a flow rate of 0.6 ml/min. Four peaks of selenium were detected in the chromatogram. The first selenium peak was obtained in the void volume. The retention time of the third peak was in accord with that of bovine serum albumin as a standard. The forth peak was thought to be a ghost. The method was applied to identify the chemical form of selenium in blood plasma immediately after intestinal absorption. The chromatographic pattern of selenium in postprandial human plasma was compared with that in fasting plasma. The first and third peaks in the postprandial plasma sample were slightly higher than those in the fasting plasma sample. This finding suggests that absorbed selenium is associated with the high molecular weight fraction and mercaptalbumin in blood plasma.

Consistent relationship between selenium and apolipoprotein A-II concentrations in the sera of fasting middle-aged male abstainers and regular consumers of alcohol.

Several studies have suggested that selenium serum levels may be associated with serum lipids and apolipoproteins. In the present study, 99 clerical workers aged 40-49 yr were selected based on their drinking and smoking habits. The serum concentration of selenium was not affected by these lifestyle factors. The regular drinkers had raised serum high-density lipoprotein cholesterol, apo A-I, and apo A-II concentrations. Correlation analysis showed that serum selenium was positively and consistently associated with apo A-II regardless of alcohol consumption. Factor analysis revealed that serum selenium had no association with factors that represented each lipoprotein fraction (LDL, HDL, and VLDL). The present study indicates that serum selenium is positively correlated only with apo A-II levels.