Developmental Exposure to PCBs,MeHg, or Both: Long-Term Effects on Auditory Function

Background

Developmental exposure to polychlorinated biphenyls (PCBs) or methylmercury (MeHg) can result in a variety of neurotoxic effects, including long-term auditory deficits. However, little is known about the effects of combined exposure to PCBs and MeHg on auditory function.

Objective

We developmentally exposed rats to PCBs and/or MeHg and assessed auditory function in adulthood to determine the effects of exposure to these contaminants individually and in combination.

Methods

We exposed female Long-Evans rats to 1 or 3 mg/kg PCB in corn oil, 1.5 or 4.5 ppm MeHg in drinking water, or combined exposure to 1 mg/kg PCB + 1.5 ppm MeHg or 3 mg/kg PCB + 4.5 ppm MeHg. Controls received corn oil vehicle and unadulterated water. Dosing began 28 days before breeding and continued until weaning at postnatal day (PND) 21. Auditory function of the offspring was assessed at approximately PND 200 by measuring distortion product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABRs).

Results

Groups exposed to PCBs alone had attenuated DPOAE amplitudes, elevated DPOAE thresholds, and elevated ABR thresholds compared with controls. Groups exposed to MeHg alone did not differ from controls. Unexpectedly, the effects of PCB exposure appeared to be attenuated by coexposure to MeHg.

Conclusion

Developmental exposure to PCBs can result in permanent hearing deficits, and the changes in DPOAE amplitudes and thresholds suggest a cochlear site of action. Coexposure to MeHg appeared to attenuate the PCB-related deficits, but the mechanism for this unexpected interaction remains to be determined.     

高效液相色谱法测定消痰咳片的含量

目的：采用反相色谱法同时测定消痰咳片中两种主要成分甲氧苄啶和磺胺体的含量。方法：以乙腈：0.1%H3PO4(15:85)为流动相，检测波长254nm，HPLC法测定含量。结果：试验表明，甲氧苄啶和磺胺林在0.8-8ug范围内呈良好的线性关系，回归方程分别为Y＝－1127.1＋110.2x(r=0.9994),Y=-1852.3 256.2x(r=0.9996),相对标准偏差分别为2.1%和0.8%。结论：该方法简便、准确、可靠。     

5种注射剂的细菌内毒素检查法初步考察

目的：考察５种注射剂盐酸林可霉素注射液，盐酸精氨酸注射液，注射用玻璃酸酶，肝素钠注射液和顺铂注射液的细菌内毒素检查法可行性。方法：中国药典细菌内毒素检查法。结果；除ｄ外，其余原液及稀释液均于有干扰作用。结论：ｄ的原液及ａ的２０倍以上稀释液可用灵敏度为０．５ＥＵ／ｍｌ的鲎试剂作细菌内毒素检查，而ｂ，ｃ和ｅ尚需进一步探讨。     

磁性明胶微球体内分布实验研究

对磁性明胶微球进行了同位素标记。用γ-闪烁照相技术观察了磁性明胶微球在兔体内的分布。结果表明:靶部位的放射活性加磁场是未加磁场的15倍,而且施加磁场时间长和磁场强度大有利于磁性明胶微球定位于靶区。文中也介绍了自行设计的外加磁场装置。     

Chronic daily headache with migrainous features due to papilledema-negative idiopathic intracranial hypertension

Patients with the syndrome of chronic daily headache often report migrainous symptoms and consequently are diagnosed as having a primary headache syndrome. We report two cases of idiopathic intracranial hypertension causing chronic daily headache with migrainous features in the absence of associated papilledema.     

Trichinella infection in travelers

To define the incidence of trichinosis associated with foreign travel and characterize the epidemiologic and clinical features of cases acquired abroad, all case report forms submitted to the Centers for Disease Control through state health departments and the National Morbidity Reporting System from 1975 to 1989 were reviewed. Twenty-six cases of travel-associated trichinosis were identified during that period. Most reported cases (73%) occurred between 1982 and 1987. Affected patients were more likely to have traveled to Mexico and Asian countries (65%). Reported high-risk behaviors included consumption of undercooked pork products, use of unsanitary cooking practices, and importation of potentially contaminated meat products into the United States. Trichinosis should be considered in the differential diagnosis of eosinophilia in travelers returning from abroad. Pretravel counseling that includes information concerning the risk of eating improperly prepared meat products may help future travelers minimize the risk of acquiring this illness.     

清除骨髓中癌细胞的磁性微球研究 II.聚苯乙烯磁性微球的研制

为制备能用于清除骨髓中癌细胞的磁性微球,首先合成了单分散、大粒径的多孔聚苯乙烯交联微球,借助微球多孔结构对其进行磁化。探讨了影响磁化效果的主要因素。为使其与单抗连接紧密,在微球表面聚合了一层聚丙烯醛膜,使其表面带上易与单抗反应的醛基。同时测定了所制微球的磁响应性。X-射线衍射证明磁性物质为γ-Fe₂O₃。     

An outbreak of Trichinella spiralis infection in southern Lebanon.

An outbreak of trichinosis occurred during January 1995 in a south Lebanese village with a population of 800-1000 persons. The estimated number of persons treated for a Trichinella-like illness was 200. Sixty-three persons sought medical attention at a local infirmary: 44 of them were diagnosed as having trichinosis or suspected trichinosis according to their clinical symptoms, signs and laboratory tests. An environmental investigation indicated that the source of infection was pork obtained from a single butcher in the village and consumed uncooked, as an ingredient of ''kubeniye'' (a local dish), during Christmas and New Year''s meals. Sera of patients, suspected patients, and asymptomatic controls were tested for the presence of anti-Trichinella antibodies. Eight (89%) of the 9 tested patients were positive, 1 (11%) was negative. Among the 7 suspected patients, 2 (28.5%) were positive, 3 (42.9%) had equivocal results, and 2 (28.5%) were negative. Among the 20 asymptomatic persons, 3 (15%) were positive, 12 (60%) negative and 5 (25%) had equivocal results. Specimens from the implicated pork meat were examined by microscopy and were found to contain encysted larvae of Trichinella spiralis. This outbreak of trichinosis is one of the largest reported. Previous outbreaks in Lebanon occurred under very similar circumstances, indicating a need to control and prevent the trading of pork meat that is not under veterinary control, and to increase the awareness of the population for this problem.     

A randomized prospective comparison of oral versus intraperitoneal ofloxacin as the primary treatment of CAPD peritonitis

Summary: Oral ofloxacin has been successfully used in our centres for the primary treatment of peritonitis complicating continous ambulatory peritoneal dialysis (CAPD). In view of the progressive rise in the resistance rate to ofloxacin among peritoneal bacterial isolates, a study was conducted to determine if oral ofloxacin remains a viable first line treatment for CAPD peritonitis in our centres and if the result can be improved by changing from an oral to an intraperitoneal (i.p.) route. In patients on three 2 L daily CAPD exchanges, ofloxacin given at the i.p. dosage of 200 mg loading followed by 25 mg/L of peritoneal dialysate achieved overnight trough peritoneal levels which are at least four times the minimal 90% inhibitory concentration (MIC90) of most bacterial pathogens without significant accumulation in the systemic circulation. This i.p. dosage was therefore chosen for the clinical study and the result was compared to that using ofloxacin given in the oral dosage of 400 mg loading followed by 300 mg once daily as maintenance. of all the recruited episodes, 35 were eligible for analysis. the overall primary cure rate including primary failures and relapses was 55.6% (10/18) in the oral treatment group and 70.6% (12/17) in the i.p. treatment group. the corresponding figures for gram positive bacterial (g +) infections were 36.4% and 50%, for gram negative bacterial (g -) infections were 66.7 and 80% and for culture negative infections were 75 and 80%. In culture positive cases, all treatment failures were due to resistant infections which were observed in 42.3% of all bacterial isolates, 47.1% of g + isolates and 33.3% of g - isolates. Due to the high background level of bacterial resistance among our CAPD population, ofloxacin monotherapy given either by the oral or the i.p. route can no longer be recommended for the primary treatment of CAPD peritonitis.     

The in vivo biologic effect of interleukin 2 and interferon alfa on natural immunity in patients with head and neck cancer

Given the association of deficient natural immunity with the risk of metastatic disease, the ability to activate natural killer cell function may have a therapeutic significance. The effect of continuous infusion of interleukin 2 plus intramuscular interferon alfa on natural immune status was, therefore, analyzed in eight patients with head and neck cancer. Also evaluated was the effect of interleukin 2-interferon alfa therapy on lymphokine-activated killer cell activity as well as total lymphocyte count, percent of lymphocyte subsets, and levels of both circulating immune complexes and antibody classes. Both the percent and absolute number of natural killer cells (ie, CD56+ CD3- lymphocytes) within peripheral blood as well as natural killer cell activity against K562 targets increased significantly with treatment. The remaining immune parameters were not significantly altered. The demonstrated capacity to modulate natural immune function supports the potential use of interleukin 2-containing regimens as a preventive measure against metastatic disease in patients with head and neck cancer.