甲醛对作业工人职业危害的调查

本文以某木材加工厂在职接触甲醛工人１０４人为调查对象，进行了甲醛职业危害的调查，结果表明长期接触空气浓度在３ｍｇ／ｍ３左右的甲醛，工人头昏、胸闷、咽充血、慢性鼻炎等症状体征出现率显著高于对照组；肺功能亦有不良影响，以小气道功能异常为主，与对照组相比，差别有极显著性（Ｐ＜０．０１）．实验室末稍血白细胞计数及血红蛋白测定在两组间未见显著差异。     

Ascorbate peroxidase in bovine retinal pigment epithelium and choroid

Peroxidase, catalyzing hydrogen peroxide reduction concurrent with ascorbate oxidation, was demonstrated in the extract of retinal pigment epithelium and choroid. The peroxidase in the choroid, RPE, and retina are 236.1, 25.1, and 0.5 units/mg protein respectively. Ammonium sulfate fractionation and high pressure liquid chromatography showed that the peroxidase in the RPE-choroid is associated with a group of heme proteins with absorption maxima at 410 nm, and optimal activity at pH 4.5. The high peroxidase activity in the RPE-choroid explains the observation of dehydroascorbate in these tissues and indicates a possible role of this enzyme in the removal of H2O2.     

Inhibition of matrix-induced bone differentiation by advanced glycation end-products in rats

Summary Glycation of long-lived proteins is an inevitable consequence of aging that is accelerated in patients with diabetes mellitus. Treatment of demineralized bone matrix particles from 35-week-old normal Long-Evans rats with glycolaldehyde, a precursor of advanced glycation end-products, was used to assess the effects of bone-matrix glycation on the process of bone differentiation. Matrix was incubated in phosphate buffered saline alone, phosphate buffered saline containing glycolaldehyde, glycolaldehyde plus the advanced glycation product-inhibitor aminoguanidine, or glycolaldehyde plus the advanced glycation product-inhibitor sodium cyanoborohydride. Glycolaldehyde increased the matrix advanced glycation product content as measured by specific fluorescence more than two-fold, while inhibiting bone differentiation more than 90 % as measured by in vivo ⁴⁵CaCl₂ uptake, alkaline phosphatase levels, and histology. In contrast, simultaneous incubation with the advanced glycation product-inhibitor aminoguanidine or sodium cyanoborohydride not only reduced fluorescence to normal, but also restored bone differentiation. Furthermore, the inhibition of bone differentiation by glycolaldehyde was not reversed by subsequent application of recombinant bone morphogenetic protein-2. These observations suggest that formation of advanced glycation products on bone matrix alters its ability to induce bone formation, and probably involves alterations of binding sites for extractable proteins with direct bone inductive properties such as bone morphogenetic protein-2. Decreased bone formation associated with aging and diabetes may result, in part, from advanced glycation product formation on matrix proteins.     

Pharmacokinetics of norethindrone: Effect of particle size

In 24 healthy women between the ages of 19 and 35 years who had not used oral contraceptive preparations for at least 60 days, it was found that the smaller the particle size of norethindrone (NET) administered, the higher was the plasma NET level obtained. Three different preparations having particle sizes of NET smaller than 250 μm, 44 μm or 10 μm were tested in a crossover pattern. The time required to reach maximum plasma concentration (T_max) became shorter with decreasing particle size, 1.69 hr, 1.52 hr and 1.06 hr, respectively. As particle size was reduced, the maximum NET plasma concentration (C_max) increased for the 3 different 1 mg NET preparations, i.e. 8.66 ng/ml, 10.53 ng/ml and 15.73 ng/ml. A trial with a 2 mg NET preparation made with NET utilizing the 44 μm size material displayed a T _maxsimilar to the 1 mg NET preparation having the same particle size while the C_max reached a level of 17.56 ng/ml. The area under the plasma concentration versus time curve from 0–24 hrs and the extrapolated total area under the curve, increased with decreasing particle size. The use of a smaller particle size allows for more rapid dissolution of oral contraceptive tablets when measured in vitro; however, there is no evidence that such faster dissolution leads to a significant difference in efficacy. Oral contraceptive tablets have, since their inception, utilized both large and small NET particle size material in various preparations.     

Cryopreservation of rabbit corneas: assessment by microscopy and transplantation.

Rabbit corneas were frozen and thawed by three methods and compared by full thickness transplantation as well as specular microscopy, histology, and transmission electron microscopy. Two of the methods used a recently described technique, in which the excised cornea was immersed in a potassium-rich buffered solution containing the cryoprotectant dimethyl sulphoxide (Me2SO, 2 mol/l). This solution was designed to restrict the loss of intracellular potassium and to prevent cell swelling at low temperatures. In one group the corneas were frozen and thawed surrounded by 5 ml of medium, while in the second group corneas were drained of excess fluid and frozen in air. The third group consisted of corneas cryopreserved by Capella and colleagues' method. All the cryopreserved corneas were damaged, but those that had been frozen in air after exposure to the new medium showed better structure and function than corneas frozen by either of the other two techniques.     

Interstitial retinol-binding protein (IRBP) in subretinal fluid

Antibodies against bovine interstitial retinol-binding protein (b-IRBP) were used to detect human IRBP (h-IRBP) on immunoblots of eight samples of subretinal fluid (SRF) from patients with retinal detachments of between 2 days' and more than 2 years' duration. Using this sensitive technique, it was found that seven of the samples contained h-IRBP in concentrations estimated to range from below 5% up to 19% of normal human IPM. One of these samples displayed two immunoreactive bands of roughly equal intensity, one at a molecular weight of 135,000 (h-IRBP), the other at 115,000. The latter may have been generated by proteolytic cleavage. No h-IRBP could be detected in an eighth sample from a patient with retrolental fibroplasia. It is concluded that the reduced concentration of h-IRBP in SRF may be due to a number of factors that include dilution, proteolytic degradation, and metabolic inactivation of photoreceptors at the detachment site.     

Terminal cardiac electrical activity in adults who die without apparent cardiac disease

Prolonged electrocardiographic (Holter) recording was performed to analyze terminal electrical events in 23 hospitalized adults who died without apparent cardiac disease. Most patients showed a gradual slowing of heart rate with shifting of cardiac pacemaker downward from the sinus node or atria to the atrioventricular junction and ventricles, resulting in cardiac asystole. Dominant bradyarrhythmia was more common than ventricular tachyarrhythmia (83 vs 17%). Agonal ST-segment elevation was not uncommon (26%). These terminal electrical events became manifest from 1 to 450 minutes (mean 62) before cessation of cardiac electrical activity. Forty-eight percent of the patients continued to show deteriorating sinus or atrial activity up to the last moment. The mechanism of bradycardiac asystole in patients with no apparent cardiac disease may be attributed to generalized anoxic and toxic depression of the sinus node and subsidiary pacemakers, together with neurogenic suppression of these structures.     

Prenatal ultrasonic prediction of autopsy-proven pulmonary hypoplasia.

The sensitivity, specificity, and positive and negative predictive values for ultrasound estimation of fetal chest circumference in relation to autopsy-proven pulmonary hypoplasia are described in 58 singleton pregnancies at risk (39 with associated preterm premature rupture of the membranes at 30 weeks' gestation or less and of 12 or more days' duration, and 19 with associated anomalies). The ultrasonographic diagnosis of pulmonary hypoplasia was based on values at or below the lower limit of the 95% confidence intervals (for predicting a future observation) for normal pregnancies for each of the following tests; chest circumference in relation to gestational age and to femur length, for the chest circumference to abdominal circumference ratio and for a combination of the three measurements. At necropsy, the diagnosis of pulmonary hypoplasia was based on lung weight to birthweight ratio or radial alveolar counts. Pulmonary hypoplasia was diagnosed in 16 cases at autopsy. The clinicians and the pathologist were blinded to the ultrasonographic measurements. All tests performed well with a sensitivity of 0.55 to 0.80, specificity of 0.90 to 1.00, positive predictive value of 0.80 to 1.00, negative predictive value of 0.87 to 0.91, and an overall accuracy of 0.87 to 0.91. We conclude that ultrasound measurement of fetal chest circumference is of value with regard to the management of pregnancies at risk for lethal pulmonary hypoplasia.     

Sesquiterpene Lactones and Other Constituents from a Cytotoxic Extract of Michelia floribunda

The pentane and CHC1₃ fractions of a crude extract of Michelia floribunda exhibited cytotoxic activity when tested in KB and P388 tumor cell cultures. Repeated chromatography led to the isolation of three cytotoxic sesquiterpene lactones (costunolide, parthenolide, and santamarine) and a cytotoxic isoquinoline alkaloid (liriodenine). Inactive sesquiterpene lactones obtained during the course of this study included dihydroparthenolide and two new glucosides of dihydrotamaulipin A and dihydroreynosin (1 and 2). The structures of these new compounds were determined through interpretation of their spectroscopic data including 2D-NMR spectroscopy. Syringin was also isolated from the extract.