Effect of Methamidophos on cerebellar neuronal cells

Summary: Methamidophos is a toxic organophosphorus compound that inhibits acetlycholinesterase activity, and induces neurotoxicity. It is a synthetic chemical commonly used as pesticides to limit pest damages to cultivated plants. Currently, there is serious public health concern over its safety and use due to its global nature, persistence and bioaccumulations. We have previously reported that methamidophos suppressed thyroid hormone receptor (TR)-mediated transcription, but did not dissociate the interaction between TR and its response element (thyroid hormone  response element; TRE), neither did it interact with nuclear cofactors. In the present study, we investigated the effects of methamidophos on  cerebellar neuronal cells. Using primary cerebellar culture from new born rats, We observed that Purkinje cell dendrite arborization were greatly impaired in the absence of thyroid hormone (TH), However, low dose  methamidophos 10-6 M did not significantly impair dendrite arborization of cerebellar Purkinje cells in the presence of thyroid hormone (TH). However, using granule cell reaggregate culture, we observed that low dose  methamidophos 10-6 M remarkably suppressed granule cell neurite extension in the presence of TH. Taken together, our study shows that low dose methamidophos may negatively impact TH-mediated cerebellar neuronal cell development and function, and consequently could interfere with TH-regulated neuronal events.Keywords: Methamidophos, Thyroid hormone, Purkinje cells, Granule cell, Neuronal developmen

Hypertension, and blood pressure response to graded exercise in young obese and non- athletic Nigerian university students.

Hypertension, and the effect of graded exercise on Blood pressure (BP), in 60 obese nonathletic young medical students (40 females and 20 males) with Body Mass Index (BMI) greater than 30 were studied. The subjects were in the age range of 18-22 years with mean age of 20.301.32 years. Twenty percent of the males and 7 percent of the females were found to be hypertensives (P<0.05) and the severity of the hypertension significantly (P< 0.05) increased linearly with increase in BMI (r =0.6). Our study reveals a positive direct correlation between obesity and socioeconomic status and BP. Marked increases in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), time of return (RT) were observed in the obese individuals compared to control at all levels of graded exercise with the highest rises seen during severe exercise. Among the obese subjects,the increases in BP were more in the males than females, but time of return was higher in females than males. This study further confirms that obese young individuals are prone to early onset of hypertension and thus other cardiovascular diseases and less tolerant to physical exercises. Our results add to the evidence that hypertension is common among obese young adults

Impact of Noise on Hearing Amongst Commercial Motor Bike Riders in Benin- City, Nigeria.

The ambient noise level and noise-induced hearing impairment (NIHI) in 200 motorbike riders from six motorbike parks were evaluated. All were males aged between 20- 62 years. Subjects were sampled using a cluster sampling technique. Parameters measured were environmental noise using the noise meter (peters) and hearing function using an audiometer (amplaid). A control group of 150 males was selected from amongst the staff of the University of Benin Teaching Hospital and students of University of Benin after informed consent was obtained. The mean ambient noise for motor bike riders was 90 \ub110 dB a level significantly (x=0.000), higher than the International Standard Organization (ISO) standard of 60dB. That for control group was 50 \ub1 10dB. While there was no NIHI in control group, a significant hearing impairment for both air conduction (AC) and Bone conduction (BC) was observed in the study group. Unlike previous observations AC and BC impairment were predominantly in the left ear. Development of both AC and BC impairments increased with period of exposure. Environment noise impacts adversely on hearing and is a risk factor in commercial motorbike riders. Development of NIHI is significantly higher in the left ear than right unlike in other occupations

Temporal effects of thyroid hormone (TH) and decabrominated diphenyl ether (BDE209) on Purkinje cell dendrite arborization

Thyroid hormones (TH) 3,3’,4-tri-iodothyronine (T3) and 3,3’,4,4’-tetra-iodothyronine (T4) plays crucial role in cerebellar development. Deficiency of TH consistently results in aberrant growth and development of the cerebellum including reduced growth and branching of the Purkinje cells. In rodents, the critical period of thyroid hormone action on cerebellum development is within the first two to three weeks, after which thyroid hormone replacement cannot fully reverse abnormal cerebellar development induced by thyroid hormone insult. Decabrominated diphenyl ether (BDE209) is an industrial reagent used as an additive flame retardant to reduce flammability of various commercial and household produce. BDE209 has bio-accumulative potential and is neurotoxic. Previously, we have shown that T4 (10-8 M) induced extensive dendrite arborization of Purkinje cells and low dose BDE209 (10-10 M) remarkably suppressed TH-induced Purkinje cell dendrite arborization. In the present study, we show that the critical period for TH-induced Purkinje cell growth and dendrite arborization in culture is much earlier than reported in animal models. Also, we show for the first time that low dose BDE209 suppressed TH-induced dendrite arborization in a time-dependent manner. Taken together, our study indicates that hypothyroidism and exposure to BDE209 during critical stage of cerebellar development can lead to impaired Purkinje cell growth and dendrite arborization and may consequently disrupt normal cerebellar functions

Thyroid hormone receptor-mediated transcription is suppressed by low dose Phthalate

Summary: Phthalates are synthetic chemicals used mainly as solvents, additives and plasticizers in polyvinylchloride (PVC) products to increase their flexibility. Phthalate plasticizers are not chemically bound to PVC, so they easily leach into the environment. There is currently heightened concern about potential health risk, especially endocrine disrupting effects associated with the use of these chemicals. We therefore investigated the effects of phthalate on thyroid hormone receptor (TR)-mediated transcription using transient transfection studies and found that low dose phthalate (10-7) M suppressed thyroid hormone (TH)-induced TR-mediated transcription by 30%. We further examined the effect of phthalate on TR-thyroid hormone response element (TRE) binding, and found no dissociation of TR from TRE. Phthalate did not also dissociate coactivator (steroid receptor coactivator-1) from TR neither did it recruit corepressor (nuclear corepressor; NCoR) to TR in the presence of TH. Our results indicate that low phthalate can disrupt TR-mediated gene expression and interfere with TH balance in TH-sensitive organs including the developing brain

HYPERTENSION, AND BLOOD PRESSURE RESPONSE TO GRADED EXERCISE IN YOUNG OBESE AND NON- ATHLETIC NIGERIAN UNIVERSITY STUDENTS.

Hypertension, and the effect of graded exercise on Blood pressure (BP), in 60 obese non-athletic young medical students (40 females and 20 males) with Body Mass Index (BMI) greater than 30 were studied. The subjects were in the age range of 18-22 years with mean age of 20.30±1.32 years. Twenty percent of the males and 7 percent of the females were found to be hypertensives (P<0.05) and the severity of the hypertension significantly (P< 0.05) increased linearly with increase in BMI (r =0.6). Our study reveals a positive direct correlation between obesity and socioeconomic status and BP. Marked increases in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), time of return (RT) were observed in the obese individuals compared to control at all levels of graded exercise with the highest rises seen during severe exercise. Among the obese subjects, the increases in BP were more in the males than females, but time of return was higher in females than males. This study further confirms that obese young individuals are prone to early onset of hypertension and thus other cardiovascular diseases and less tolerant to physical exercises. Our results add to the evidence that hypertension is common among obese young adults

Peak Expiratory Flow Rate and Respiratory Symptoms Following Chronic Domestic Wood Smoke Exposure in Women in Edo, Nigeria

Peak expiratory flow rate (PEFR) of 350 rural women aged (20-70 years) in Edo State, Nigeria who actively used wood as a source of fuel for cooking was measured. The height, chest circumference, weight and blood pressure of the women were also measured. Respiratory symptoms of cough with sputum production, dyspnea, wheezing, chest tightness and chest pain were markedly elevated in the subjects compared to control. The mean PEFR value for the wood exposed women (289±19.6L/mm) was significantly lower than control (364±17.2L/mm), P <0.05.The predicted PEFR values for both Africans and Caucasians were significantly higher than the measured values. The PEFR decreased with increase in years of exposure to wood smoke and the fall was neither accounted for by age nor height. The increase in respiratory symptoms and the low PEFR values observed for women exposed to wood smoke, the severity of which is related to exposure time indicate that prolonged exposure to wood smoke is capable of impairing lung functions

Epidemiologic Studies of the Prevalence of Arterial Hypertension among Commercial Motor Bike Riders in Benin City, Nigeria.

An epidemiologic study was carried out in the dry season on 250 male commercial motor bike riders from five different parks. 69% of the bike riders were in the (year) 31– 40 and 41–50 age range while 31% were in 21–30, 51– 60 and 61 – 70 age range. Half of the population studied were normotensive. Arterial hypertension was found in 63 (25%) of the examined workers (

Impact of Noise on Hearing Amongst Commercial Motor Bike Riders in Benin- City, Nigeria.

The ambient noise level and noise-induced hearing impairment (NIHI) in 200 motorbike riders from six motorbike parks were evaluated. All were males aged between 20- 62 years. Subjects were sampled using a cluster sampling technique. Parameters measured were environmental noise using the noise meter (peters) and hearing function using an audiometer (amplaid). A control group of 150 males was selected from amongst the staff of the University of Benin Teaching Hospital and students of University of Benin after informed consent was obtained. The mean ambient noise for motor bike riders was 90 ±10 dB a level significantly (x=0.000), higher than the International Standard Organization (ISO) standard of 60dB. That for control group was 50 ± 10dB. While there was no NIHI in control group, a significant hearing impairment for both air conduction (AC) and Bone conduction (BC) was observed in the study group. Unlike previous observations AC and BC impairment were predominantly in the left ear. Development of both AC and BC impairments increased with period of exposure. Environment noise impacts adversely on hearing and is a risk factor in commercial motorbike riders. Development of NIHI is significantly higher in the left ear than right unlike in other occupations