Effect of vitamin E on doxorubicin and paclitaxel-induced memory impairments in male rats

PURPOSE

In addition to peripheral neuronal dysfunction, conventional chemotherapy can be associated with other neurological treatment-limiting adverse effects, including cognitive dysfunction, memory impairment, and anxiety, which are referred to as "chemobrain". This study aimed to investigate the effects of doxorubicin (DOX) and paclitaxel (PAC) on learning and memory in rats using radial arm water maze (RAWM) and investigated a potential beneficial effect of vitamin E (Vit. E).

METHODS

Adult male rats were injected with four doses of 2 mg/kg/week DOX, or 2 mg/kg PAC every other day intraperitoneally. Vit. E was co-administered with these drugs in other groups to study its antioxidative effects. Using the RAWM, each rat was assessed for learning and memory performance through two sets of six trials separated by a 5-min rest period evaluating both short- and long-term effects on memory.

RESULTS

There was no deficit in learning or long-term memory in both drug groups compared to control. However, rats in both drug groups made significantly more errors in all short-term memory trials. This effect was mitigated when Vit. E was co-administered with either drug. Moreover, PAC (but not DOX) induced hippocampal lipid peroxidation by increasing the levels of standard biomarker thiobarbituric acid reactive substances (TBARS). Interestingly, Vit. E prevented PAC-induced hippocampal oxidative stress. Furthermore, both DOX and PAC were correlated with reduction in Brain-Derived Neurotrophic Factor (BDNF) expression levels in the hippocampus, which was overcome by the co-administration of Vit. E.

CONCLUSION

There is a potential role of Vit. E in alleviating short-term memory impairment in rats exposed to chemotherapy, possibly by reducing hippocampal oxidative stress and neurodegeneration.

The impact of vitamin and mineral supplements usage prior to COVID-19 infection on disease severity and hospitalization

The COVID-19 pandemic has caused a global public health emergency. Nutritional status is suggested to be related to the severity of COVID-19 infection. Herein, we aimed to explore the impact of using vitamin and mineral supplements prior to COVID-19 infection on disease severity and hospitalization. In addition, the prior use of aspirin as an anticoagulant on the disease severity was investigated. A cross-sectional, self-administered survey was conducted between March and July 2021. Recovered COVID-19 individuals (age ≥ 18 years, n = 2148) were recruited in the study. A multivariate logistic regression was used to evaluate the associations of supplements and aspirin use with COVID-19 disease severity and hospitalization status. Among the participants, 12.1% reported symptoms consistent with severe COVID-19, and 10.2% were hospitalized due to COVID-19. After adjustment for confounding variables (age, gender, BMI, cigarette smoking status, and the number of comorbidities), the multivariate logistic regression model showed that the consumption of vitamin D supplements prior to COVID-19 infection was associated with a significant decrease in disease severity (OR = 0.68, 95% CI 0.50-0.92; p = 0.01), and a lower risk of hospitalization (OR = 0.64, 95% CI 0.45-0.89; p = 0.01). On the other hand, there were no significant differences in the frequencies of severe illness and hospitalizations with the consumption of vitamin A, folic acid, vitamin B12, vitamin B complex, vitamin C, zinc, iron, selenium, calcium, magnesium, omega 3, and aspirin before COVID-19 infection. Among the investigated nutrients, the use of vitamin D prior to COVID-19 infection was associated with reduced disease severity and hospitalization. However, more studies are required to confirm this finding.

A single nucleotide polymorphism in BCAT1 gene is associated with type 2 diabetes mellitus

The level of circulatory branched chain amino acids (BCAAs) is often increased in type 2 diabetes mellitus (T2DM). Catabolism of BCAAs involves a transamination reaction mediated by the branched chain amino acid aminotransferase (BCAT1) enzyme. Differences in the level of BCAT1 were found to be linked with hypertension, obesity, and cancer. Herein, using a case control design, we tested the association of rs9668920 and rs12321766 polymorphisms in BCAT1 gene with T2DM. Three hundred subjects were recruited in the study. Genotyping of the indicated polymorphisms was achieved using restriction fragment length polymorphism technique after amplification of the target sequences. The results showed that, under a recessive inheritance model, the GG genotype of rs9668920 increased the risk of T2DM (P=0.026; OR 2.60; 95% CI 1.119–6.048). This effect was independent of the age, body mass index, waist circumference, serum glucose, cholesterol, triglycerides, and BCAAs (P>0.05). In conclusion, The GG genotype of BCAT1 rs9668920 SNP might be a risk factor of T2DM. More studies are required to confirm this finding.

A single nucleotide polymorphism in BCAT1 gene is associated with type 2 diabetes mellitus

The level of circulatory branched chain amino acids (BCAAs) is often increased in type 2 diabetes mellitus (T2DM). Catabolism of BCAAs involves a transamination reaction mediated by the branched chain amino acid aminotransferase (BCAT1) enzyme. Differences in the level of BCAT1 were found to be linked with hypertension, obesity, and cancer. Herein, using a case control design, we tested the association of rs9668920 and rs12321766 polymorphisms in BCAT1 gene with T2DM. Three hundred subjects were recruited in the study. Genotyping of the indicated polymorphisms was achieved using restriction fragment length polymorphism technique after amplification of the target sequences. The results showed that, under a recessive inheritance model, the GG genotype of rs9668920 increased the risk of T2DM (P=0.026; OR 2.60; 95% CI 1.119-6.048). This effect was independent of the age, body mass index, waist circumference, serum glucose, cholesterol, triglycerides, and BCAAs (P>0.05). In conclusion, The GG genotype of BCAT1 rs9668920 SNP might be a risk factor of T2DM. More studies are required to confirm this finding.

The protective effects of pioglitazone against cognitive impairment caused by L-Methionine administration in a rat model

PURPOSE

Accumulating evidence indicates that elevated levels of methionine are associated with cognitive decline including loss of memory. The exact mechanisms behind this observation are not completely understood but could be related to an increase in oxidative stress markers in hippocampal tissues. The above increase in oxidative stress could be directly caused by an increase in the blood levels of methionine (hypermethioninemia) or one of its metabolites, such as homocysteine. Pioglitazone is a drug primarily used for the treatment of type 2 diabetes mellitus. Several reports showed that using pioglitazone protects against cognitive decline observed in Alzheimer's disease. Pioglitazone has antioxidant properties independent of its hypoglycemic effects. Taken together, we hypothesized that pioglitazone protects against memory loss triggered by elevated levels of methionine through lowering of oxidative stress in the hippocampus.

METHOD

To test this hypothesis, we used chronic administration of L-methionine in a rat model. Spatial learning and memory were evaluated in the model using a radial arm water maze (RAWM). The levels of several markers related to oxidative stress were measured in hippocampal tissues recovered from experimental rats.

RESULTS

Current results showed that administration of L-methionine was associated with a significant loss of short- and long-term memory and an increase in blood homocysteine levels. The above memory changes were associated with an increase in lipid peroxidation and a decrease in the activity of catalase and glutathione peroxidase antioxidant enzymes in the hippocampus. The combined treatment of pioglitazone with L-methionine protected rat model from memory loss. It also prevented changes observed in lipid peroxidation and changes in the activity of catalase and glutathione peroxidase enzymes.

CONCLUSION

Current findings indicate that pioglitazone is a viable therapeutic option that protects against cognitive changes observed upon administration of L-methionine.

Increased Adherence to Infection Control Practices Among Medical Laboratory Technicians During the COVID-19 Pandemic: A Self-Reported Survey Study

Background

The adherence of medical laboratory technicians (MLT) to infection control guidelines is essential for reducing the risk of exposure to infectious agents. This study explored the adherence of MLT towards infection control practices during the COVID-19 pandemic.

Method

The study population consisted of MLT (n = 444) who worked in private and government health sectors in Jordan. A self-reported survey was used to collect data from participants.

Findings

More than 87% of the participants reported adherence to hand-washing guidelines and using personal protective equipment (PPE) when interacting with patients (74.5%), and handling clinical samples (70.0%). Besides, 88.1%, 48.2%, and 7.7% reported wearing of lab coats, face masks, and goggles, at all times, respectively. The majority reported increased adherence to infection control practices during the COVID-19 pandemic. This includes increased PPE use at the workplace (94.2%), increased frequency of disinfection of laboratory surfaces (92.4%) and laboratory equipment (86.7%), and increased frequency of handwashing/use of antiseptics (94.6%). Having a graduate degree was significantly associated with increased adherence of participants to the daily use of goggles/eye protection (p = 0.002), and the use of PPE while handling clinical samples (p = 0.011). Having work experience of >10 years was associated with increased adherence to the use of PPE while handling clinical samples (p = 0.001).

Conclusion

MLT reported very good adherence with most assessed infection control practices. In addition, they reported increased conformity with infection control guidelines during the COVID-19 pandemic.

Fear of COVID-19 and stigmatization towards infected people among Jordanian people

AIM

This study aims to explore the prevalence rates of stigma and fear among people in Jordan during COVID-19 pandemic and to assess socio-demographic and personal factors contributing to the prevalence rates of fear and stigma among people in Jordan during COVID-19 pandemic.

METHOD

Cross-sectional descriptive design was utilized to attain the study aim. An anonymous online survey targeting people of Jordan was used and distributed to adults in Arabic language. The survey included a previously validated fear scale. Stigma was measured using developed instrument by authors.

RESULTS

The prevalence of fear among study participants was 52%. In addition, the prevalence of stigma towards infected people and their contact was 64%. The predictors of stigma towards infected people with COVID-19 and their contact were income, living area and downloaded application to trace COVID-19 cases. Moreover the predictors of fear were income living area and downloaded application to trace COVID-19 cases (P ≤ .001).

CONCLUSION

More than 50% of the respondents were afraid from COVID-19 and 64% had stigma towards infected people and their contact during the COVID-19 pandemic. The present study highlights the need for an intervention that provides psychological support to citizens during the pandemic.

Adverse Health Impacts of Living Near an Oil Refinery in Jordan

INTRODUCTION

Air pollution can adversely affect the health of communities and manifest as a variety of symptoms.

OBJECTIVE

This study aimed at assessing health symptoms among populations living near an oil refinery in Jordan.

METHODS

A cross-sectional survey study was conducted utilizing convenient random sampling at Al-Hashimeya town (where the refinery is located) and Bal'ma town (about 12 km further away from refinery). A total of 486 participants were recruited for the study. The data were checked, coded, and entered to excel sheet and exported to the Statistical Package for Social Science (SPSS) Version 20 for further analysis. Both bivariate and multivariate logistic regressions were used to identify associated factors. Variables having a P ⩽ 0.25 were fitted to multivariate logistic regression so as to assess the presence and strength of associations between socio-demographic characteristics and health symptoms and outcomes. A P value < 0.05 was considered for statistical significance.

RESULTS

In the cross tabulation analysis, there were significant differences in the reported respiratory health problems and history of abortions in the family between residents in the 2 towns (P < 0.05). Only 4.7% of Al-Hashimeya residents were extremely enjoying their town compared to 32.9% among Bal'ma residents (P < 0.001). In addition, residents of Al-Hashimeya were at several folds higher risk to have phlegm and about 3 times more likely to have skin problems compared to participants from Bal'ma (P < 0.001). Furthermore, reporting asthma was substantially higher among Al-Hashimeya residents (odds ratio [OR] = 5.20; 95% confidence interval [CI]: 2.11-12.84), and they were more likely to perceive the neighboring oil refinery industry as the leading cause of their health problems than Bal'ma residents (OR = 86.40; 95%CI: 45.95-162.44).

CONCLUSION

Residents living close to the oil refinery industry in Jordan report adverse impacts on their health, including respiratory problems, skin diseases, and perception of poor health.

Jordanian National Study of Nurses' Barriers and Predictors for Research Utilization in Clinical Settings

Background

The nurses are the healthcare providers and researchers in the health institutions. Investment in the research potential of nurses will ultimately benefit society. The purpose of this study was to survey nurses regarding barriers to participating in research studies.

Methods

This was a cross-sectional descriptive study using electronic surveys sent by email, and social media groups (WhatsApp). A total of 447 nurses agreed to participate in this study. Barriers were measured using the Barriers of Research Utilization (BRU) Scale.

Results

More than half (53.3%) of the participants perceived the barriers to be high, whereas a small fraction (8.9%) perceived them as low. Barriers related to the organization scored the highest (P<0.01) compared to the other domains (nurse, innovation, and communication). The regression analysis model showed that age, working experience, and nationality were associated with barriers to participate in research (P<0.05).

Conclusion

More than half of the nurses in Jordan perceived barriers to participating in research studies to be high. The barriers associated with the organization had more influence. A comprehensive approach should be developed to boost research utilization among nurses by overcoming the barriers identified in the current study.

Perceptions Towards Medical Research Participation: A Study from Jordan

PURPOSE

Progress and development in medical researches require the participation of volunteers in such research, but unfortunately, the participation rate is low. This study aimed to assess Jordanian public perceptions towards participation in medical research and to understand motivators and barriers that may affect their participation.

PATIENTS AND METHODS

This is a cross-sectional study that was conducted from December 2019 to February 2020. Adults from the public were invited to participate in this paper-based survey. The survey assessed public perception (values, trust and ethics), motivators, and barriers towards participation in medical research.

RESULTS

During the study period, 2000 subjects were recruited. Around 82.3% (n = 1643) strongly agreed/agreed that medical research is important for the advancement of science. Helping the society was found to be the main motivators to participate in medical research (n = 1708, 85.4%), while time constrains (n = 1400, 70.0%), lack of opportunity (n = 1278, 63.9%), and the lack of knowledge and awareness about these researches (n = 1152, 57.6%) were among the top barriers towards the participation in medical research. Finally, results showed that previous participation in medical research was correlated with lower overall perception of values and ethics of research, and higher trust in research (p-value <0.001).

CONCLUSION

Jordanians have positive perception toward participation in medical research, which could be improved by increasing awareness, trust, and training of researchers on responsible conduct of research(RCR) in the country.

Effect of Prenatal Exposure to Waterpipe Tobacco Smoke on Learning and Memory of Adult Offspring Rats

Introduction

Waterpipe tobacco smoking has increased in prevalence worldwide, including among pregnant women. In this study, we investigated the effect of prenatal maternal waterpipe tobacco smoke (WTS) exposure during different stages of pregnancy on learning and memory of adult offspring rats.

Methods

Pregnant rats received either fresh air or mainstream WTS (2 hours daily) during early, mid, late, or whole gestational period. Male offspring rats were followed through 20 weeks. Outcomes included (1) spatial learning and memory using the radial arm water maze (RAWM), (2) levels of brain derived neurotrophic factor (BDNF) in the hippocampus, and (3) oxidative stress biomarkers (superoxide dismutase, catalase, glutathione peroxidase and thiobarbituric acid reactive substances).

Results

Relative to offspring whose mothers were exposed to fresh air, prenatal exposure to WTS at any stage of pregnancy resulted in short- and long-term memory impairment in adult offspring rats (p < .05). This impairment was associated with reduced levels of BDNF in hippocampus (p < .05). However, prenatal WTS did not affect the level of oxidative stress biomarkers in hippocampus. Prenatal WTS during late gestation increased the activity of catalase as compared to control.

Conclusion

Prenatal maternal WTS exposure can impair the memory of adult male offspring. These results support development of interventions that target pregnant women who smoke waterpipe during pregnancy.

Implications

We examined for the first time the effect of prenatal waterpipe tobacco smoke exposure on learning and memory of offspring. The results showed that in utero exposure to waterpipe tobacco smoke was associated with impaired memory and decreased brain derived neurotrophic factor in hippocampus of adult male offspring rats.

Tobacco and waterpipe use among university students in Saudi Arabia: impact of tobacco sales ban

Background

Waterpipe smoking is a method of tobacco consumption that continues to spread globally. In 2002, a ban of tobacco sales was adopted in the Saudi Arabian cites of Mecca and Medina.

Aims

This study aimed to examine prevalence of waterpipe and cigarette smoking among students of Taibah University, the biggest in Medina, where the tobacco sales ban has been implemented.

Methods

A structured questionnaire was distributed between February and April 2015 to examined tobacco use among Taibah University students.

Results

The prevalence of current and ever waterpipe use was 24.2% and 36.04%, respectively, compared with 31.9% and 42.7% for current and ever cigarette smoking. This prevalence is similar to that reported in other Saudi cities where tobacco sales are allowed. Multivariate analysis showed that waterpipe use was higher among senior students; those with pocket money spending of > 500 Saudi Arabia riyal (SAR)/month; and if > 5 individuals were living in the household. In addition, waterpipe use was lower among students with monthly household income of 5000-9000 SAR. In contrast, current cigarette smoking was more frequent in those aged > 22 years; among male students; in those with pocket money spending of > 500 SAR/month; and those who lived away from their parents.

Conclusions

Waterpipe and cigarette smoking, despite the ban on tobacco sales, is still common among Taibah University students in Medina, Saudi Arabia.

Association of LOXL1 gene common sequence variants in Jordanian patients with exfoliation syndrome and exfoliative glaucoma

AIM

To investigate the association between single nucleotide polymorphisms (SNPs) in the LOXL1 gene with exfoliation syndrome/glaucoma (XFS/XFG) among Jordanians.

METHODS

Sixty-one patients with XFS/XFG and 59 healthy control individuals were recruited in the study. Patients were diagnosed with XFS/XFG using standard clinical examination techniques. The exonic rs1048661 SNP and the intronic rs2165241 SNP in LOXL1 gene were genotyped using sequencing technique. Allele and genotype frequencies were compared between cases and controls using Chi-square analysis.

RESULTS

The G allele of the rs1048661 SNP and the T allele of the rs2165241 SNP were common in the sample with frequencies of 86.4% and 81.4%, respectively. In addition, there were no significant differences in the genotypic and allelic distributions between patients and controls for rs1048661 SNP (P=0.770, OR=1.21, 95%CI: 0.56-2.60) and for rs2165241 SNP (P=0.605, OR=1.12, 95%CI: 0.59-2.09). In addition, no significant associations were found between haplotypes of the examined SNPs and XFS/XFG in the sample (P>0.05).

CONCLUSION

Variations in LOXL1 gene may not be associated with XFS/XFG in the Jordanian population. More studies are required to confirm the current findings.

Vitamin B12 protects against DNA damage induced by hydrochlorothiazide

DNA damage induced by hydrochlorothiazide was previously reported in cultured human lymphocytes. In this study, we aimed to investigate the harmful effects of hydrochlorothiazide on DNA by measuring the spontaneous frequency of sister chromatid exchanges (SCEs) in cultured human lymphocytes. We also aimed to investigate the possible protection of that damage by vitamin B12. The results showed that hydrochlorothiazide (5 µg/mL) significantly increased the frequency of sister chromatid exchanges (P < 0.001) in human lymphocytes in comparison with control. Additionally, the frequency of hydrochlorothiazide-induced SCEs was significantly decreased by co-treatment with vitamin B12 at concentration of 13.5 µg/mL (P < 0.001). In conclusion, hydrochlorothiazide is genotoxic to human lymphocytes and its toxicity is reduced by vitamin B12.

Vascular endothelial growth factor receptor inhibition enhances chronic obstructive pulmonary disease picture in mice exposed to waterpipe smoke

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is marked by destruction of alveolar architecture. Preclinical modelling for COPD is challenging. Chronic cigarette smoke exposure, the reference animal model of COPD, is time-inefficient, while exposure to waterpipe smoke (WPS), a surging smoking modality, was not fully tested for its histopathological pulmonary consequences. Since alveolar damage and pulmonary vascular endothelial dysfunction are integral to COPD pathology, lung histopathological effects of WPS were temporally evaluated, alone or in combination with vascular endothelial growth factor receptor (VEGFR) inhibition in mice.

MATERIALS AND METHODS

Mice were exposed to WPS, 3 hours/day, 5 days/week, for 1, 2, 3, or 4 months. Another group of mice was exposed to WPS for 1 month, while being subjected to injections with the VEGFR blocker Sugen5416 (SU, 20 mg/kg) 3 times weekly. Control mice were exposed to fresh air in a matching inhalation chamber. Histopathological assessment of COPD was performed. Alveolar destructive index (DI) was counted as the percentage of abnormally enlarged alveoli with damaged septa per all alveoli counted. Mean linear intercept (MLI) was calculated as a measure of airspace enlargement.

RESULTS

Exposure to WPS resulted in significant increases in alveolar DI and MLI only after 4 months. Lung inflammatory score was minimal across all time-points. Importantly, combination of WPS and SU resulted in significantly increased DI, MLI, and inflammatory scores as early as 1 month post exposure.

CONCLUSIONS

Combined exposure to WPS and SU results in COPD picture, highlighting the role of pulmonary vascular endothelial dysfunction in the disease.

Human diversity in Jordan: polymorphic Alu insertions in general Jordanian and Bedouin groups

Jordan, located in the Levant region, is an area crucial for the investigation of human migration between Africa and Eurasia. However, the genetic history of Jordanians has yet to be clarified, including the origin of the Bedouins today resident in Jordan. Here, we provide new genetic data on autosomal independent markers in two Jordanian population samples (Bedouins and the general population) to begin to examine the genetic diversity inside this country and to provide new information about the genetic position of these populations in the context of the Mediterranean and Middle East area. The markers analyzed were 18 Alu polymorphic insertions characterized by their identity by descent, known ancestral state (lack of insertion), and apparent selective neutrality. The results indicate significant genetic diffferences between Bedouins and general Jordanians (p = 0.038). Whereas Bedouins show a close genetic proximity to North Africans, general Jordanians appear genetically more similar to other Middle East populations. In general, these data are consistent with the hypothesis that Bedouins had an important role in the peopling of Jordan and constitute the original substrate of the current population. However, migration into Jordan in recent years likely has contributed to the diversity among current Jordanian population groups.

Changes in the expression and protein level of matrix metalloproteinases after exposure to waterpipe tobacco smoke

Waterpipe smoking has become a worldwide epidemic with health consequences that only now are beginning to be understood fully. Because waterpipe use involves inhaling a large volume of toxicant-laden smoke that can cause inflammation, some health consequences may include inflammation-mediated lung injury. Excess matrix metalloproteinase expression is a key step in the etiology of toxicant exposure-driven inflammation and injury. In this study, changes in the level and mRNA of major matrix metalloproteinases (MMP-1, -9, and -12) in the lungs of mice following exposure to waterpipe smoke were investigated. Balb/c mice were exposed to waterpipe smoke for one hour daily, over a period of 2 or 8 weeks. Control mice were exposed to fresh air only. ELISA and real-time PCR techniques were used to determine the protein and mRNA levels of MMP-1, -9, and -12 in the lungs. Our findings showed that MMP-1, -9, and -12 levels in the lung significantly increased after both 2 (p < 0.05) and 8 weeks (p < 0.01) exposures. Similarly, RT-PCR findings showed that mRNA of those proteinases significantly increased following 2 (p < 0.01) and 8 weeks (p < 0.001) exposures. In conclusion, waterpipe smoking is associated strongly with lung injury as measured by elevation in the expression of MMPs in the lung tissue.

Identification, characterization and antibiotic resistance of bacterial isolates obtained from waterpipe device hoses

The general lack of knowledge about the health effects of waterpipe smoking is among the reasons for its global spread. In this study, bacterial contamination of waterpipe hoses was investigated. Twenty hoses were collected from waterpipe cafés and screened for bacterial pathogens using standard culture and isolation techniques. Additionally, resistance of isolated bacteria to common antibiotics was determined by identifying the minimum inhibitory concentration (MIC) of each isolate. Forty eight bacterial isolates were detected. Isolates included both Gram-positive and Gram-negative pathogens from species that included Micrococcus (12), Corynebacterium (13) and Bacillus (9). In addition, some of the detected pathogens were found to be resistant to aztreonam (79%), cefixime (79%), norfloxacin, amoxicillin (47%), clarithromycin (46%) and enrofloxacin (38%). In conclusion, the hose of the waterpipe device is a good environment for the growth of bacterial pathogens, which can then be transmitted to users.

The associations of polymorphisms of TSH receptor and thyroid hormone receptor genes with L-thyroxine treatment in hypothyroid patients

OBJECTIVE

To investigate the possible association between response to levothyroxine (L-T4) doses in hypothyroid patients and variation in thyroid stimulating hormone receptor (TSHR) gene and thyroid hormone receptor (THRα) gene.

DESIGN

This cross-sectional correlation study included 228 patients with primary hypothyroidism who were using L-T4 replacement therapy. Thyroid function test was performed using standard techniques. Genotyping of rs939348 of the THRα gene, and rs2268458 and rs2239610 of the TSHR gene was performed using the polymerase chain reaction-based restriction fragment length polymorphism assay (PCR-RFLP). Patient history of illness, medication and compliance data were collected using the patients' medical files.

RESULTS

The THRα rs939348 polymorphism was associated with L-T4 replacement doses in hypothyroid patients and in central obesity. No significant correlation was detected between the examined SNPs to TSHR and L-T4 doses or the different clinical and biochemical parameters. Finally, L-T4 dose was associated with lower BMI, waist circumference and TSH, and higher free T4 (fT4) among hypothyroid patients.

CONCLUSIONS

Whereas the two tested TSHR polymorphisms were not associated with the dose of T4, the THRα rs939348 polymorphism was associated with L-T4 dose and central obesity among hypothyroid patients. T4 dose was also associated with multiple beneficial effects among hypothyroid patients.

The prevalence and factors associated with aspirin resistance in patients premedicated with aspirin

OBJECTIVE

Aspirin is a key drug used in treating patients with a high risk to develop stroke, myocardial infarction and other cardiovascular events. However, a considerable fraction of the patients develops aspirin resistance, which is a multi-factorial process that can occur due to patient's non-compliance, improper dosing, other co-morbidities or drug-drug interactions.This cross-sectional study was carried out to determine the prevalence and factors associated with aspirin resistance among Jordanians.

METHODS

The study was performed on a sample of 418 adult patients who were taking aspirin as an antiplatelet agent. To determine aspirin resistance, platelet function was assessed using a multiplate analyzer.

RESULTS

Data shows that about 18.7% (78) of the patients were aspirin resistant. Aspirin resistance was associated with female gender (P < 0.05) and was higher among diabetic subjects (P < 0.05). Statins use was correlated with improved aspirin response (P < 0.05). No association was found between aspirin response and: age, body mass index, education, smoking status, family history of cardiovascular disease, aspirin dose and duration of aspirin use (P > 0.05). In addition, aspirin resistance was not related to parameters such as HbA1c and low-density lipoprotein (LDL), comorbidities including dyslipidaemia, and hypertension, and concurrent use of other medications such as beta blockers, angiotensin-converting enzyme inhibitors (ACEIs), calcium channel blockers (CCBs), and proton pump inhibitors (PPIs) (P > 0.05).

CONCLUSION

The incidence of aspirin resistance is high in the Jordanian population. Aspirin resistance is associated with female gender and diabetes. On the other hand, the use of statins improves response to aspirin.

Evaluation of vitamin B12 effects on DNA damage induced by pioglitazone

Pioglitazone is a prototype of thiazolidinediones, used for the treatment of type 2 diabetes mellitus. Previous studies suggest that pioglitazone might cause DNA damage by generation of oxidative species. In this study, we investigated the mutagenic effects of pioglitazone using sister chromatid exchanges (SCEs), and chromosomal aberrations (CAs) assays in cultured human lymphocytes. In addition, oxidative DNA damage was evaluated in cells culture by measuring 8-hydroxy-2'-deoxyguanosine (8-OH-dG) marker. We also investigated the possible protective effects of vitamin B12, which is associated with DNA repair, on DNA damage induced by pioglitazone. Treatment of the human lymphocytes with pioglitazone (100μM) significantly increases the frequency of SCEs and CAs (p<0.01). In addition, significant elevation in 8-OH-dG release from lymphocytes was observed after treatment with pioglitazone (p<0.01). On the other hand, pretreatment of cultures with vitamin B12 (13.5μg/ml) protected lymphocytes from the genotoxic effect of pioglitazone. Therefore, we conclude that pioglitazone is genotoxic, and it induces chromosomal and oxidative DNA damage in cultured lymphocytes and this toxicity is prevented by pretreatment with vitamin B12.

Exploring behavioral and molecular mechanisms of nicotine reward in adolescent mice

Tobacco smoking during adolescence has become a prominent preventable health problem faced in the United States. Addictive properties of smoking are thought to have a pronounced effect at a young age, thereby increasing vulnerability to a life-long addiction and decreasing the likelihood of smoking cessation during adulthood. Learning and memory involvement in nicotine reward was assessed in early adolescent (PND 28-34) and adult (PND 70+) male ICR mice by conducting conditioning sessions of nicotine (0.5mg/kg) acquisition at varying time-spans, and evaluating extinction and reinstatement of nicotine preference using Conditioned Place Preference. Acquisition studies resulted in a significant preference for nicotine after 3 days of conditioning for both age groups, but not after only 1 or 2 conditioning days. In the extinction study, adolescent mice exhibited preference for nicotine 72 h after the last conditioning session, whereas preference for nicotine was extinct in adult mice by 72 h. Reinstatement studies showed adolescent mice, but not adult mice, recovering nicotine preference after a priming injection of 0.1mg/kg nicotine on day 9 after the mice underwent extinction. No significant differences were found when nAChRs were quantified in both early adolescent and adult mice using binding techniques including cytisine sensitive, α-conotoxin-MII sensitive, and α-bungarotoxin sensitive nAChRs. Levels of striatal dopamine release were measured in both age groups using a dopamine release assay over a range of nicotine doses, which also resulted in no significant differences. More sensitive assays may facilitate in understanding the mechanisms of nicotine reward in adolescent mice.

Post-translational regulation of an Aplysia glutamate transporter during long-term facilitation

Regulation of glutamate transporters accompanies plasticity of some glutamatergic synapses. The regulation of glutamate uptake at the Aplysia sensorimotor synapse during long-term facilitation (LTF) was investigated. Previously, increases in levels of ApGT1 (Aplysia glutamate transporter 1) in synaptic membranes were found to be related to long-term increases in glutamate uptake. In this study, we found that regulation of ApGT1 during LTF appears to occur post-translationally. Serotonin (5-HT) a transmitter that induces LTF did not increase synthesis of ApGT1. A pool of ApGT1 appears to exist in sensory neuron somata, which is transported to the terminals by axonal transport. Blocking the rough endoplasmic reticulum-Golgi-trans-Golgi network (TGN) pathway with Brefeldin A prevented the 5-HT-induced increase of ApGT1 in terminals. Also, 5-HT produced changes in post-translational modifications of ApGT1 as well as changes in the levels of an ApGT1-co-precipitating protein. These results suggest that regulation of trafficking of ApGT1 from the vesicular trafficking system (rough endoplasmic reticulum-Golgi-TGN) in the sensory neuron somata to the terminals by post-translational modifications and protein interactions appears to be the mechanism underlying the increase in ApGT1, and thus, glutamate uptake during memory formation.

In vivo regulation of an Aplysia glutamate transporter, ApGT1, during long-term memory formation

Regulation of glutamate transporters often accompanies glutamatergic synaptic plasticity. We investigated the mechanisms responsible for the increase in glutamate uptake associated with increased glutamate release at the Aplysia sensorimotor synapse during long-term sensitization (LTS) and long-term facilitation. An increase in the V(max) of transport, produced by LTS training, suggested that the increased glutamate uptake was due to an increase in the number of transporters in the membrane. We cloned a high-affinity, Na(+)-dependent glutamate transporter, ApGT1, from Aplysia central nervous system that is highly enriched in pleural sensory neurons, and in pleural-pedal synaptosome and cell/glial fractions. ApGT1, expressed in Xenopus oocytes, demonstrated a similar pharmacological profile to glutamate uptake in Aplysia synaptosome and cell/glial fractions (strong inhibition by threo-beta-benzyloxyaspartate and weak inhibition by dihydrokainate) suggesting that ApGT1 may be the primary glutamate transporter in pleural-pedal ganglia. Levels of ApGT1 and glutamate uptake were increased in synaptosomes 24 h after induction of LTS by electrical stimulation or serotonin. Regulation of ApGT1 during LTS appears to occur post-transcriptionally and results in an increased number of transporters in synaptic membranes. These results suggest that an increase in levels of ApGT1 is responsible, at least in part, for the long-term increase in glutamate uptake associated with long-term memory.

The circadian clock modulates core steps in long-term memory formation in Aplysia

The circadian clock modulates the induction of long-term sensitization (LTS) in Aplysia such that long-term memory formation is significantly suppressed when animals are trained at night. We investigated whether the circadian clock modulated core molecular processes necessary for memory formation in vivo by analyzing circadian regulation of basal and LTS-induced levels of phosphorylated mitogen-activated protein kinase (P-MAPK) and Aplysia CCAAT/enhancer binding protein (ApC/EBP). No basal circadian regulation occurred for P-MAPK or total MAPK in pleural ganglia. In contrast, the circadian clock regulated basal levels of ApC/EBP protein with peak levels at night, antiphase to the rhythm in LTS. Importantly, LTS training during the (subjective) day produced greater increases in P-MAPK and ApC/EBP than training at night. Thus, circadian modulation of LTS occurs, at least in part, by suppressing changes in key proteins at night. Rescue of long-term memory formation at night required both facilitation of MAPK and transcription in conjunction with LTS training, confirming that the circadian clock at night actively suppresses MAPK activation and transcription involved in memory formation. The circadian clock appears to modulate LTS at multiple levels. 5-HT levels are increased more when animals receive LTS training during the (subjective) day compared with the night, suggesting circadian modulation of 5-HT release. Circadian modulation also occurred downstream of 5-HT release because animals treated with 5-HT to induce LTS exhibited significantly greater LTS when treated during the (subjective) day compared with the night. Together, our studies suggest that the circadian clock modulates LTS at multiple steps and locations during the formation of long-term memory.

Coregulation of glutamate uptake and long-term sensitization in Aplysia

In Aplysia, long-term facilitation (LTF) at sensorimotor synapses of the pleural-pedal ganglia is mediated by an increase in the release of a neurotransmitter, which appears to be glutamate. Glutamate uptake also is increased in sensory neurons 24 hr after the induction of long-term sensitization (Levenson et al., 2000b). The present study investigated whether the same signaling pathways were involved in the long-term increase in glutamate uptake as in the induction of LTF. Thus, roles for cAMP, PKA (cAMP-dependent protein kinase), MAPK (mitogen-activated protein kinase), and tyrosine kinase in the regulation of glutamate uptake were tested. We found that 5-HT increased cAMP and activated PKA in sensory neurons. Exposure of pleural-pedal ganglia to analogs of cAMP or forskolin increased glutamate uptake 24 hr after treatments. Inhibitors of PKA (KT5720), MAPK (U0126 and PD98059), and tyrosine kinase (genistein) blocked the long-term increase in glutamate uptake produced by 5-HT. In addition, bpV, a tyrosine phosphatase inhibitor, facilitated the ability of subthreshold levels of 5-HT to increase glutamate uptake. Inhibition of PKC, which is not involved in LTF, had no effect on the long-term increase in glutamate uptake produced by 5-HT. Furthermore, activation of PKC by phorbol-12,13-dibutyrate did not produce long-term changes in glutamate uptake. The results demonstrate that the same constellation of second messengers and kinases is involved in the long-term regulation of both glutamate release and glutamate uptake. These similarities in signaling pathways suggest that regulation of glutamate release and uptake during formation of long-term memory are coordinated through coregulation of these two processes.

Circadian modulation of long-term sensitization in Aplysia

As the mechanisms for learning and memory are elucidated, modulation of learning and memory becomes a central issue. We studied the modulation of learning and memory by investigating the circadian regulation of short- and long-term sensitization of the siphon withdrawal reflex in Aplysia. We found that Aplysia exhibited diurnal and circadian rhythms of long-term sensitization (LTS) with significantly greater LTS occurring when animals were trained and tested during the day relative to those trained and tested at night. In contrast to the modulation of LTS, short-term sensitization was not regulated by the circadian clock. Time of training rather than time of testing determined the circadian rhythm of LTS. Animals trained during the subjective day demonstrated LTS when tested during either the day or the night. Conversely, when animals were trained during the night, LTS was not observed when animals were tested either at night or during the day. Thus, the circadian rhythm of LTS is a rhythm in learning rather than a rhythm in recall. The threshold required to elicit siphon withdrawal and the duration of siphon withdrawal were not regulated by the circadian clock. These results indicate that the circadian oscillator exerts strong modulatory influences on one form of long-term memory in Aplysia.