Computed tomographic scanning versus radioisotope imaging in adrenocortical diagnosis

Referral patterns from internists to departments of nuclear medicine or radiology are important determinants of whether adrenal glands are imaged by computed tomography (CT) or by radioisotope scintigraphy. To assist clinicians in making an informed choice, computed tomographic scans were compared with isotope scintigrams using 131I-19-iodocholesterol (19-IC) and 131I-6 beta-iodomethyl-19-norcholesterol (NP-59). In general, imaging techniques serve to localize diseases that are diagnosed on the basis of biochemical tests of adrenal function. Computed tomographic scanning and NP-59 scanning are of comparable diagnostic accuracy. Both are superior to 19-IC scanning in the diagnosis of Cushing's syndrome and primary aldosteronism. Computed tomographic scanning is faster and less expensive, and involves lower radiation doses to the patient than scintigraphy. Adrenocortical isotope scanning as a routine procedure has been superseded by computed tomographic scanning at the Mayo Clinic.     

The negative association between plasma ghrelin and IGF-I is modified by obesity, insulin resistance and type 2 diabetes

Aims/hypothesis Ghrelin is a natural growth hormone-releasing peptide thought to be involved in the regulation of energy metabolism. The recent studies concerning the association between ghrelin and insulin-like growth factor-I (IGF-I) concentrations have shown either negative correlation or no correlation at all. The aims of this study were to clarify the association between ghrelin and IGF-I concentrations in a large cohort and to characterize whether obesity, insulin resistance and type 2 diabetes affect this association.Methods We analysed fasting plasma ghrelin and IGF-I concentrations of 1,004 middle-aged subjects of the population-based OPERA study. Insulin resistance was estimated using QUICKI.Results IGF-I concentrations were negatively associated with ghrelin concentrations in the analysis of all subjects before (=–0.32, p<0.001) and after adjustments for BMI, insulin levels, sex and age (=–0.40, p<0.001). The association was particularly strong in males and in the higher BMI tertiles. The degree of association varied in relation to the glycaemic status: no insulin resistance: r²=6.5% (p<0.001), insulin resistance without type 2 diabetes: r²=21.0% (p<0.001), type 2 diabetes: r²=25.4 (p<0.001). IGF-I levels explained larger proportion (r²=9.8%) of the variation in ghrelin concentrations compared to fasting insulin concentration (r²=3.0%) and BMI (r²=1.5%).Conclusions/interpretation There is a negative and independent association between ghrelin and IGF-I concentrations in middle-aged subjects. The interaction between IGF-I and ghrelin is modified by obesity, IR and type 2 diabetes. Further studies are warranted to elucidate the role of ghrelin in the development of these states.     

砖茶氟在大鼠体内24小时代谢实验观察

目的观察砖茶氟在大鼠体内24h吸收、分布及排泄的动态变化。方法将Wistar大鼠分为两组,用灌胃方法分别给予砖茶水和氟化钠(NaF),含氟均为300mg/L。在染氟后0.25、0.5、1、2、4、8、16、24h处死动物,取血、小肠、股骨、肌肉、心、肝、肺、脾、脑及肾,用氟离子选择电极法测定氟水平。结果两组大鼠骨氟最高,24h内呈现明显的蓄积作用,至24h时,砖茶组骨氟增加了约77mg/kg,NaF组骨氟增加了约70mg/kg,两组比较,NaF在大鼠体内的代谢速度较砖茶氟快,表现为在各组织中达到峰值的时间早,排泄的速度快,24h内在软组织中无蓄积作用。砖茶氟吸收、分布及排泄的速度均较NaF慢,在各组织器官中的浓度较NaF组稍高,除骨外,在小肠、心脏中也有轻微的蓄积作用。结论砖茶氟在大鼠体内24h代谢速度较NaF慢,且砖茶氟在多种组织中均似有蓄积作用。     

Zinc Administration Improves Gastric Alcohol Dehydrogenase Activity and First-Pass Metabolism of Ethanol in Alcohol-Fed Rats

The effects of zinc on first-pass metabolism (FPM) of ethanol and gastric and hepatic alcohol dehydrogenase (ADH) activities have been investigated in two groups of male Wistar rats fed a liquid ethanol diet with normal zinc content (7.6 mg/liter), or zinc supplemented (76 mg/liter), for 21 days, and in two pair-fed groups receiving the same diets without ethanol. Alcoholic rats with normal dietary zinc had lower FPM (1.64 ± 0.25 vs. 2.43 ± 0.20 mM ± hr, p < 0.05) and gastric ADH activity (184 ± 7 vs. 335 ± 41 μmol/min/mg protein, p < 0.01) than control rats. Zinc supplementation did not produce any change in FPM or in gastric ADH activity in control rats. By contrast, in alcoholic rats, the zinc supplement increased gastric ADH activity (247 ± 31 vs. 184 ± 7 μmol/min/mg protein, p < 0.05) and decreased the areas under the curve of blood ethanol concentrations after the intragastric administration of 0.25 g/kg of body weight of ethanol (0.78 ± 0.07 vs. 1.71 ± 0.24 mM ± hr, p < 0.05), thereby increasing the FPM. In conclusion, in alcohol-fed rats, the administration of zinc supplements restores gastric ADH activity and improves the FPM of ethanol. These effects may be one of the mechanisms in which zinc has a beneficial role in preventing the development of alcoholic hepatic lesions.     

氟铝联合中毒对小鼠骨代谢生物标志物的影响

目的 分析氟铝联合染毒小鼠骨代谢标志物的变化,探讨氟铝联合对骨毒性效应的特征和机制.方法 采用2因素3水平析因设计方法将昆明种小鼠分成9组,由氟化钠(NaF,0、50、150mg/L)、氯化铝(AlCl3,0、200、600 mg/L)经饮水染毒,24周后采集血清、尿液,测定血清钙(Ca)、磷(P)、镁(Mg)、碱性磷酸酶(ALP)、骨钙素(BGP)、甲状旁腺激素(PTH)及尿Ca、P.结果 氟铝联合对血清Ca、BGP和尿Ca的影响存在交互作用(F值分别为17.370、4.399、9.448,P<0.01),对血清P、Mg、ALP、PTH和尿P的影响不存在交互作用(F值分别为0.416、0.415、1.921、1.362、1.630,P0.05).高氟组血清Ca[(1.13±0.27)mmoL/L]、BGP[(6.56±5.74)μg/L]比对照组[(1.82±0.37)mmol/L、(23.45±15.40)μg/L]降低(P<0.05),高氟低铝组升高到(1.76±0.36)mmol/L、(10.57±4.28)μg/L,高氟高铝组升高到(2.10±0.51)mmoL/L、(15.73±3.15)μg/L;低氟组尿Ca[(6.24±2.61)mmol/mmol Cr]比对照组[(3.12±2.04)mmol/mmol Cr]升高(P<0.05),与低铝、高铝联合时降低[(0.81±0.44)、(1.23±0.41)mmol/mmol Cr],联合作用与氟单独效应相反.高铝组血清Ca为(1.07±0.68)mmol/L、BGP为(7.21±5.22)μg/L.低氟高铝组升高到(1.47±0.18)mmol/L、(10.98±4.35)μg/L,高氟高铝组升高到(2.10±0.51)mmoL/L、(15.73±3.15)μg/L,联合作用对BGP的影响与铝单独作用随剂量增高的效应趋势相同.结论 本实验条件下,铝拮抗氟对部分骨代谢标志物的作用,氟则促进铝的作用,氟铝联合染毒时骨代谢标志物均降低,联合作用抑制骨形成和骨矿化过程,造成骨代谢紊乱.     

Glucose Transporters and Glucose Utilization in Rat Brain after Acute Ethanol Administration

In the normal adult brain, glucose provides 90% of the energy requirements as well as substrate for nucleic acid and lipid synthesis. In the present study, effects of ethanol on glucose transporters (GLUT) and glucose utilization were examined in rat brain. Male Sprague-Dawley rats weighing 250-300 gms were given either ethanol 3 gm/kg BW or saline IP 4 hrs prior to the animal sacrifice and removal of the cerebral cortical tissue. The cortical plasma membranes analyzed by cytochalasin B binding assay showed a decrease in GLUT number but not in GLUT affinity in the ethanol treated rats as compared to the control rats. The estimated Ro values were 70 ± 8.9 Vs 91 ± 8.9 pmoles/mg protein (p < 0.05 N=4) and the estimated Kd values were 0.37 ± 0.03 and 0.28 ± 0.05 M (p: NS) in ethanol and control experiments respectively. Immunoblots of purified cerebral plasma membranes and low density microsomal fraction showed 17% and 71% decrease for GLUT1 and 54% and 21% (p<0.05 or less; n=6) for GLUT3 respectively in ethanol treated rats than in control animals. Immunofluoresence studies also showed reduction of GLUT1 immunoreactively in choroid plexus and cortical microvessels of ethanol treated rats as compared to control rats. The effect of ethanol on regional cerebral metabolic rates for glucose (CMR_Gle) was studied using [6-¹⁴C] glucose and showed statistically insignificant decrease in brain glucose utilization. These data suggest that ethanol invivo decrease GLUT number and protein content in rat cerebral cortex     

Effects of disulfiram on the metabolism of nitrosodiethylamine during liver carcinogenesis

Summary We have studied the effects of disulfiram (DSF) administration on the metabolism of nitrosodiethylamine (NDEA) in rats during acute and chronic administration. DSF was found to have the following effects during the course of carcinogenesis: (a) marked decrease in the exhalation of ¹⁴CO₂ derived from ¹⁴C-NDEA; (b) reduction of the total levels of DNA and RNA ethylation in the liver. In acute experiments DSF caused an incrase in the amount of NDEA in organs and in the urine. We suggest that inhibition of NDEA biotransformation and the subsequent decrease in the total level of DNA ethylation may prevent specific chemical interactions relevant to carcinogenesis.Abbreviations DSF disulfiram - NDEA N-nitrosodiethylamine     

Hemiagenesis of the thyroid gland.

Three patients with hemiagenesis of the typhoid gland are described. One was clinically euthyroid, whereas the other two were more unusual in that one had coincident Graves' disease with thyrotoxicosis, and one had primary myxodema. In all three cases diagnosis of hemiagenesis was established by the administration of thyroid-stimulating hormone (TSH). The literature on hemiagenetic thyroid glands with and without associated thyroid disease is reviewed. Although the anomaly is uncommon, awareness and recogniton of its existence may clarify an otherwise puzzling clinical thyroid evaluation, and thus possible avert an unnecessary surgical procedure.     

Experimental toxicology of formaldehyde

Summary Formaldehyde is a reactive chemical which undergoes spontaneous reactions with various cellular constituents. Mutagenicity data may be interpreted on the background of this behavior. Mice are better able to reduce the irritating effect of formaldehyde than rats and to reduce their ventilation rate when formaldehyde acts on the respiratory tract. Subacute exposure of rats to concentrations higher than 2 ppm inhibits mucociliary clearance of the nasal epithelium and leads to progressive histological and ultrastructural lesions at this site. The occurrence of squamous cell carcinomas of the nasal epithelium of rats after 2 years inhalation of 14.3 ppm formaldehyde (CIIT study) is probably the result of chronic and recurrent local toxicity; this is supported by species differences in susceptibility to the tissue damaging and carcinogenic effect of formaldehyde (rat, mouse, hamster). Data on formaldehyde-DNA interaction further support the argument that a direct risk extrapolation from the formaldehyde effects in rats to those expected for man is not possible.Cancer Research and Clinical Oncology will publish in loose succession Editorials and Guest Editorials on topical and controversial problems in experimental and clinical oncology. These contributions will represent the personal opinion of the author. We would like to ask our readers to send their comments directly to the author.