Effect of Acute Propanil Exposure on the Immune Response of C57BI/6 Mice

Effect of Acute Propanil Exposure on the Immune Response ofC57BI/6 Mice. BARNETT, J. B., AND GANDY, J. (1989). Fundam.Appl. Toxicol. 12, 757–764. Propanil is a herbicide thatis used extensively in rice farming to kill weeds without damagingthe rice plant The immunotoxic effects of acute exposure topropanil were determined in adult C57B1/6 female mice exposedintraperitoneally to propanil at doses of 0, 10, 25, 50, 100,200,or 400 mg/kg body wt. One week following exposure, the immunecompetency of the animals was assessed. Contact hypersensitivityresponse (CHR), blastogenic response to T- and B-cell-specificmitogens, and mixed lymphocyte reaction (MLR) were significantlydepressed only in propanil-treated animals at 400 mg/kg. However,the number of splenic antibody-producing cells was also significantlydepressed in a dose-dependent manner at the lower doses of 50,100, and 200 mg/kg. In addition, a significant reduction inthe thymus weight and an increase in absolute and relative spleenweight were also measured in animals treated with 200 and 400mg/kg. The increase in spleen weight also showed a concomitantrise in spleen cellularity. These data indicate that propanilhas a dose-dependent immunotoxic effect on the adult mouse thataffects primarily the humoral response     

Affinity Constants and β-Adrenoceptor Reserves for Isoprenaline on Cardiac Tissue from Normotensive and Hypertensive Rats

To determine whether there are differences in cardiac β-adrenoceptor responsiveness, isoprenaline affinity constants and fractional β-adrenoceptor occupancy—response relationships for isoprenaline in the early stages of established hypertension, we studied the effects of bromoacetylalprenololmenthane (BAAM) and ([3,5-diamino-6-chloro-N-(1[N-β-(2-hydroxyl-3-α-naphthoxypropylamino)ethylcarbamoyl]-1-methylethyl)-pyrazine-2-carboxamide (ICI 147 798), slowly reversible β-adrenoceptor antagonists, on the isoprenaline responses of the left ventricular papillary muscle and the left and right atria of 6-month-old Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). The papillary muscles, but not the right and left atria, of the SHR were less responsive to isoprenaline than those of the WKY. The isoprenaline pD₂ values (the negative logarithms of the molar concentrations of agonist producing 50% of the maximum response) were 7.72 and 8.00 on the SHR and WKY papillary muscles, respectively. On the WKY papillary muscle the isoprenaline K_A values were 2–3 times 10^?6M, which is as expected for isoprenaline at β₁ or β₂-adrenoceptors. Isoprenaline had 100-fold greater affinity on the WKY and SHR left atria than on the papillary muscles; the isoprenaline K_A values were 2–4 times 10^?8M. On the WKY papillary muscle and left atrium, isoprenaline had to occupy 3–4% of the β-adrenoceptors to produce a 50% maximum response; on the WKY papillary muscle and left atrium isoprenaline had to occupy 25–35% and 55%, respectively, of the β-adrenoceptors to produce a 90% maximum response. The SHR papillary muscles and left atrium had smaller β-adrenoceptor reserves for isoprenaline than did the WKY tissues. We were unable to obtain isoprenaline K_A values on the WKY right atrium. The isoprenaline K_A value on the SHR right atrium was 1–4 times 10^?8M. Because the isoprenaline K_A values for the left and right atria are markedly different from those previously reported for isoprenaline at β₁ or β₂-adrenoceptors, we suggest that atypical β-adrenoceptors might be present on the atria of WKY and SHR. We have also demonstrated a lower β-adrenoceptor reserve on SHR papillary muscle and atria in the early stages of established hypertension.     

A controlled,longitudinal study of home visits compared to telephone contacts to prevent early childhood caries

International Journal of Paediatric Dentistry 2013; 23: 23–31 Background. Home visits (HV) provide excellent opportunities for health promotion. Aim. This longitudinal study compared the effects of HV and telephone contacts (TC) in preventing early childhood caries (ECC) and colonisation of mutans streptococci (MS) and lactobacilli (LB) from 0 to 24 months. Design. A total of 325 children were recruited from community health centres at mean age of 42 days, and randomly assigned to receive either HV or TC. A total of 188 children completed three, 6 monthly HV, and another 58 had three, 6 monthly TC. An additional 40 age‐matched children from childcare facilities served as reference controls (RC). At 24 months, all groups were examined at a community dental clinic. Results. At 24 months, three HV children of 188 (1.5%) had caries, compared to four TC of 58 (6.8%) and nine RC of 40 (22.5%) (P < 0.001 for HV versus RC; P = 0.05 for HV versus TC and P = 0.03 for TC versus RC). There were also more children with MS in the TC (47%) and RC (35%) compared to HV (28%) group (P = 0.01 and P = 0.02). Conclusions. Home visits and telephone contacts conducted 6 monthly from birth are effective in reducing ECC prevalence by 24 months.     

A randomised,controlled clinical trial comparing chlorhexidine gel and low‐dose fluoride toothpaste to prevent early childhood caries

International Journal of Paediatric Dentistry 2013; 23: 216–224 Objectives. This randomised, controlled trial compared the effectiveness of 0.12% chlorhexidine (CHX) gel and 304% fluoride toothpaste to prevent early childhood caries (ECC) in a birth cohort by 24 months. Methods. The participants were randomised to receive either (i) twice daily toothbrushing with toothpaste and once daily 0.12% CHX gel (n = 110) or (ii) twice daily toothbrushing with toothpaste only (study controls) (n = 89). The primary outcome measured was caries incidence and the secondary outcome was percentage of children with mutans streptococci (MS). All mothers were contacted by telephone at 6, 12, and 18 months. At 24 months, all children were examined at a community dental clinic. Results. At 24 months, the caries prevalence was 5% (3/61) in the CHX and 7% (4/58) in the controls (P = 0.7). There were no differences in percentages of MS‐positive children between the CHX and control groups (54%vs 53%). Only 20% applied the CHX gel once daily and 80% less than once daily. Conclusions. Toothbrushing using 304% fluoride toothpaste with or without the application of chlorhexidine gel (0.12%) reduces ECC from 23% found in the general community to 5–7%. The lack of effect with chlorhexidine is likely to be due to low compliance.