低剂量γ射线辐照对血清一氧化氮及一氧化氮合酶水平的影响

目的：观察低剂量γ射线照射人离体外周血对血清中一氧化氮（NO）和一氧化氮合酶（NOS）水平的影响。方法：采集10份健康献血员全血，肝素抗凝，然后采用γ射线照射，照射剂量率为17Gy／min，总吸收剂量为1Gy，分别于照射前及照射后1h，2h采用分光光度法检测血清中NO含量和NOS活性。结果：经γ射线照射1h后，血清中NO及NOS水平与照射前比较明显升高（P〈0.01）；照射后2h，血清中NOS水平与照射后1h比较无统计学差异（P〉0、05），但是还明显高于照射前的水平（P〈0．01）；在照射后2h，血清中NO含量与照射后1h比较明显降低（P〈0.01），但仍明显高于照射前水平（P〈0．01）。结论：采用剂量为1Gy的γ射线照射外周血，可引起血清中NO水平及NOS活性的显著升高．从而为低剂量辐照自体血回输对肿瘤的辅助治疗提供了理论支持。     

近红外信息辐照对免疫抑制大鼠体液免疫功能的影响

本实验观察了近红外信息辐照(辐照)对免疫抑制大鼠体液免疫功能的调整作用。取大鼠54只随机分为三组:甲组各鼠腹腔注射环磷酰胺(CY,75mg/kg)和伤寒沙门氏菌鞭毛抗原(HAg,7×10~8菌体/只),同时各鼠每天全身辐照1h,共4周;乙组腹腔注射CY和HAg丙组仅腹腔注射HAg。结果甲、乙、丙三组于第四周末的存活率分别为83.3％、38.1％和66.7％(甲与乙组比较P<0.05);第四周末血清总IgG含量分别为141.4±17.6U/ml,120.3±16.6U/ml和117.0±22.9U/ml(甲组与其它两组比较P<0.01);第二周末抗H抗体效价分别为1:91.9、1:46.6和1:149.3(甲与乙组比较P<0.05;乙与丙组比较P<0.01)。结果表明,辐照对免疫功能低下的机体有增强免疫功能的作用。     

微波辐射免疫比浊法加速测定免疫球蛋白

本文应用微波辐射免疫比浊法加速测定免疫球蛋白(IgG、IgA、IgM).结果表明:用本法测定的线性范围较宽:IgG从3.24～51.92/L;IgA从0.49～7.92g/L;IgM从0.36～5.75/L.批内、批间精密度(CV):IgG从44～7.4%;IgA从4.1～9.5%;IgM从4.0～8.8%.本法与传统免疫比浊法和进口试剂自动免疫比浊法(Monarch 2000)测定比较,其结果相关良好,r从0.950至0.996,P>0.05.本法的特点是操作简便、快速,可明显缩短抗原和抗体反应达到终点的时间.     

Deoxyribonucleic acid turnover in immature neurons of the rat cerebral cortex

To test for metabolic deoxyribonucleic acid (DNA) turnover in differentiating neurons, [methyl-3H]thymidine was injected into the lateral cerebral ventricles of newly born rats, and after 6, 24 and 96 h, neuronal nuclei were prepared from the immature cerebral cortex. Enzymatic treatment converted virtually all of the DNA into soluble deoxynucleosides which were fractionated by high-performance liquid chromatography for determination of specific activity. The specific activity of thymidine was found to decline rapidly with time. The rate of this loss correlated with the radioactivity initially incorporated into the DNA. This suggested that DNA was being replaced by DNA repair as a consequence of radiation damage, rather than by spontaneous metabolic DNA turnover.     

Local and systemic consequences of acute,low-dose ultraviolet B radiation are mediated by different immune regulatory mechanisms

Acute, low-dose ultraviolet B (UVB) radiation alters the local skin site such that epicutaneous application of hapten fails to induce contact hypersensitivity (CH), but induces tolerance in UVB-susceptible mice. Although the inability of irradiated skin to support CH induction may be a strictly local effect, there may also be systemic immune consequences of UVB radiation delivered in this manner. To examine this matter, abdominal skin of C57BL/6 mice was exposed to acute, low-dose UVB radiation. Dinitrofluorobenzene was immediately painted directly on the irradiated site, or at a distant (unirradiated) site. In separate experiments, epicutaneous application of the hapten on a distant site was delayed for 1–3 days. The mice were tested for acquisition of CH, and for tolerance, i.e. the capacity to become sensitized when exposed subsequently to hapten via normal body wall skin. It was found that, immediately after completion of the UVB regimen, CH was inducible via unirradiated, but not via irradiated, skin. At 3 days post-UVB exposure, CH was no longer inducible even through unirradiated skin. Mice that first encountered hapten via UVB-exposed skin developed tolerance, as did mice that first encountered hapten via unirradiated skin of UVB-treated mice. Neutralizing anti-tumor necrosis factor-α TNF-α antibodies failed (a) to restore the ability of unirradiated skin to support induction of CH, and (b) to interfere with tolerance induction, whether hapten was first painted on irradiated or unirradiates skin. The data indicate that the acute, low-dose regimen of UVB radiation produces effects on the immune system that are manifest locally as well as systemically. By demonstrating that the disruption of CH induction following UVB radiation is TNF-α dependent, whereas locally and systemically induced tolerance is not, our findings encourage further search for other UVB-related modulators of systemic immunity and tolerance.     

Environmental conditions and variation in levels of sun exposure among children in child care

Sun exposure in childhood is 1 of the risk factors for developing skin cancer, yet little is known about levels of exposure at this age. This is particularly important in countries with high levels of ultraviolet radiation (UVR) such as Australia. Among 49 children 3 to 5 years of age attending child care centers, UVR exposure was studied under 4 conditions in a repeated measures design; sunny days, cloudy days, teacher’s instruction to stay in the shade, and a health professionals instruction to apply sunscreen. Three different data collection methods were employed: (a) completion of questionnaire or diary by parents and researcher, (b) polysulphone dosimeter readings, and (c) observational audits (video recording). Results of this study indicated that more than half the children had been sunburnt (pink or red) and more than a third had experienced painful sunburn (sore or tender) in the last summer. Most wore short sleeve shirts, short skirts or shorts and cap, that do not provide optimal levels of skin protection. However, sunscreen was applied to all exposed parts before the children went out to the playground. Over the period of 1 hr (9–10 a.m.) the average amount of time children spent in full sun was 22 min. On sunny days there was more variation across children in the amount of sun exposure received. While the potential amount of UVR exposure for young children during the hour they were outside on a sunny day was 1.45 MED (Minimum Erythemal Dose), they received on average 0.35 MED, which is an insufficient amount to result in an erythemal response on fair skin even without the use of sunscreen.     

Radioprotective efficacy and acute toxicity of 5-androstenediol after subcutaneous or oral administration in mice

We previously showed that one subcutaneous (sc) injection of 5-androstene-3beta,17beta-diol (AED) stimulated the innate immune system in mice and prevented mortality due to hemopoietic suppression after whole-body ionizing irradiation with gamma rays. In the present study, we tested whether there was any significant toxicity in mice that might hinder development of this steroid for human use. There were no indications of toxicity in chemical analyses of serum after sc doses as high as 4000 mg/kg. At this dose, 2 of 54 mice died when given AED alone. When 4800 mg/kg was given orally, no deaths resulted. The only adverse findings attributed to AED administration were 1) a moderate elevation of granulocytes in abdominal organs and fat after sc injections of 320 mg/kg; and 2) occasional wasting of skin over the injection site in female B6D2F1 but not male C3H/HeN mice. Significant weight loss (6%) was observed after sc injections of 320 mg/kg but not 160 or 80 mg/kg. When male C3H/HeN mice were injected sc with AED at doses of 0-200 mg/kg 24 h before whole body gamma-irradiation (9 Gy), a significant improvement in survival was observed at doses as low as 5 mg/kg. Oral administration of AED produced significant survival enhancement at a dose of 1600 mg/kg. We conclude that the radioprotective efficacy of AED is accompanied by low toxicity.Androst-5-ene-3 beta, 17 beta-diol; Ionizing radiation; Experimental radiation injuries; Toxicity; Clinical chemistry; Histopathology     

Influence of food on the intravenous and oral dose kinetics of propranolol in the dog

The intravenous and oral dose kinetics of propranolol were studied in the dog both in a fasted state and immediately after a meal consisting of 100 g of cooked beef liver. Fifty Ci of³H-propranolol was administered intravenously simultaneously with a 40-mg oral dose of unlabeled propranolol. Plasma³H-propranolol was measured by specific extraction and liquid scintillation spectrometry, and unlabeled plasma propranolol was determined by gas chromatography-mass spectrometry. Feeding significantly reduced (25%) the elimination half-life and increased (52%) the systemic clearance of intravenous propranolol. The increase in the systemic clearance of propranolol after feeding was mostly due to an increase (60%) in apparent hepatic blood flow, which appeared to remain elevated for 5–7 hr. The meal had no influence on the apparent volume of distribution or plasma binding. Feeding did not affect the area under the concentration-time curve of oral propranolol, but significantly delayed the rate of oral propranolol absorption, shifting the time to reach peak plasma levels from 60 to 158 min. The results of this study suggest that feeding alters the disposition of propranolol in the dog by producing a sustained increase in hepatic blood flow.This work was supported by National Institute of Health grants GM 07534, GM 20387, and HL 29566.     

Radiation therapy for pancreatic cancer: eleven year experience at the JCRT

Radiation therapy (XRT) for 41 patients with unresectable pancreatic cancer resulted in a median survival of 7.0 months. There was no difference in median survival for patients receiving external beam alone (3500 to 5600 cGy) (n = 28), intraoperative (IORT) boost plus external beam (5040 to 6750 cGy) (n = 9), or a gold-198 implant +/- external beam radiation (n = 4). A pilot study using orthovoltage IORT boost indicates no acute toxicity with doses of 1250 to 1750 cGy. Serious late damage has not been observed in any patients followed to 2 years. Local recurrence in patients treated post-operatively after "radical" surgery occurred in one of 10 (10%). This adjuvant treatment is safe and appears to improve local control rates compared to historical data, but survival is still poor. The median survival for the post-operative group is 10 months; three patients are alive without disease 8 months to 8.3 years after treatment.     

No disturbance of myelination in the central nervous system by selective3Hβ-irradiation

Summary The effect of a selective irradiation of myelin by³H -particles was studied by light and electron microscopic methods in guinea pig spinal cord. The animals were injected with [³H]leucine shortly after birth when the rate of myelin biosynthesis is high and sacrificed 130 days later. In spinal cord the radioactivity was mainly preserved in myelin because the half life of myelin proteins is much higher than that of most other CNS protein. As a consequence the irradiation dose in the white matter was much higher than in the gray matter. In myelin internally irradiated by³H -particles within 130 days at a dose of 10 Gy no alterations could be detected either by morphological or by morphometric methods.Supported by the Deutsche Forschungsgemeinschaft