有机氮源对红霉素发酵影响的具体分析

红色糖多孢菌的摇瓶培养基中使用不同有机氮源时红霉素的效价明显不同。通过对不同有机氮源所含营养成分的逐步回归分析,我们得到有机氮源中的苏氨酸为影响红霉素效价的主要因子。最后向对照培养基中添加苏氨酸,则使红霉素的效价比对照培养基提高了22.85%。     

Cell volume regulation: a review of cerebral adaptive mechanisms and implications for clinical treatment of osmolal disturbances: II

Cerebral cell volume regulatory mechanisms are activated by sustained disturbances in plasma osmolality. Acute hypernatremia causes a predictable shrinkage of brain cells due to the sudden imposition of a plasma-to-cell osmolal gradient. However, during chronic hypernatremia cerebral cell volume is maintained close to the normal range as a result of the accumulation of electrolytes and organic osmolytes including myo-inositol, taurine, glutamine, glycerophosphorylcholine, and betaine. The increased cytosolic level of these molecules is generally accomplished via increased activity of sodium (Na⁺)-dependent cotransport systems. The slow dissipation of these additional osmotically active solutes from the cell during treatment of hypernatremia necessitates gradual correction of this electrolyte abnormality. Acute hyponatremia leads to cerebral cell swelling and severe neurological dysfunction. However, prolonged hyponatremia is associated with significant reductions in brain cell electrolyte and organic osmolyte content so that cerebral cell volume is restored to normal. While acute hyponatremia can be treated with the administration of moderate doses of hypertonic saline in order to control seizure activity, chronic hyponatremia should be corrected slowly in order to prevent subsequent neurological deterioration. If the rate of correction exceeds 0.5 mmol/l per hour, or if the total increment in serum [Na⁺] exceeds 25 mmol/l in the first 48 h of therapy, then there is an increased risk of the development of cerebral demyelinating lesions. Chronic hyperglycemia activates the brain cell volume regulatory adaptations in the same manner as hypernatremia. Therefore, during the treatment of diabetic ketoacidosis, it is imperative to restore normoglycemia gradually in order to prevent the occurrence of cerebral edema. It is possible that excessive administration of electrolyte-free solutions and high doses of insulin may increase the risk of this complication. While there are some data to suggest that brain cell size is disturbed during acute uremia, additional work is necessary to clarify the role of cerebral cell volume regulation during acute and chronic uremia.     

Characteristic modifications of the breathing pattern of mice to evaluate the effects of airborne chemicals on the respiratory tract

A system was developed for exposure of unanesthetized mice to airborne chemicals and for continuous measurement of their breathing pattern prior to, during and following exposure. By measuring inspiratory and expiratory airflows (VI and VE), and integration with time to yield tidal volume (VT), we obtained characteristic modifications to the normal breathing pattern. These permitted recognition that a specific portion of the respiratory tract was affected by the selected airborne chemicals. Following recognition, we also quantitated the degree of effect using one specific measurement in each case. An effect on the upper respiratory tract, induced by the sensory irritant, 2-chlorobenzylchloride, was quantitated by measuring a decrease in respiratory frequency. An effect on the conducting airways, induced by the airway constrictor, carbamylcholine, was quantitated by a decrease in VE at the mid-point of VT. An effect at the alveolar level, induced either by the vagal nerve ending stimulant, propranolol, or by the pulmonary irritant, machining fluid G, was quantitated by an increase in the length of a pause induced at the end of expiration. The system is easy to construct and operate and can be used to rapidly evaluate the effects of airborne chemicals on the respiratory tract.     

医学有机化学课引言设计方法

在医学有机化学课堂教学中，运用教学艺术提出了教学环节——引言的7种设计方法，让学生在生动活泼的气氛下，增强学习的主动性。     

Studies on capsaicin inhibition of chemically induced lipid peroxidation in the lung and liver tissues of rat

Previous work from this laboratory has already indicated that capsaicin, stabilizes the rat lung membrane lipid system on long-term treatment. This stabilization of the membrane is further supported by our present findings that capsaicin pretreatment causes significant inhibition of various chemically induced lipid peroxidative changes at both cellular and subcellular levels. Both in vivo and in vitro studies, using whole lung and liver tissue slices and mitochondrial and microsomal fractions, have shown that capsaicin pretreatment inhibits peroxidative changes at both cellular and subcellular levels. Both in vivo and in vitro studies, using whole lung and liver tissue slices and mitochondrial and microsomal fractions, have shown that capsaicin pretreatment inhibits peroxidative changes induced by different chemical irritants such as chloroform, dichloromethane, carbon tetrachloride as well as ferrous sulphate.     

Rapidly Progressive Toxic Leukoencephalomyelopathy with Myelodysplastic Syndrome: a Clinicopathological Correlation

Neurological disorders induced by long-term exposure to organic solvents typically have a slowly progressive clinical course, which may be arrested or even reversed following discontinuation of exposure. We report an unusual case of rapidly progressive toxic leukoencephalomyelopathy in a 29-year-old man who had worked at a chemical factory that used toluene for the manufacture of nylon 66 for 5 years. He presented with progressive weakness of legs, recurrent seizures, and cognitive decline. Widespread white-matter changes in the brain and spinal cord, and myelodysplastic syndrome were noted. He died 6 months after the onset of his symptoms, and autopsy showed discrete multifocal demyelination and necrosis in the central nervous system, and dysplastic cells of erythroid, myeloid, and megakaryotic lineages in blood vessels. The co-occurrence of leukoencephalomyelopathy and myelodysplastic syndrome highlights the vulnerability of the white matter and bone marrow to injury from organic solvents. Intravascular congestion of dysplastic hematopoietic cells might have led to his unusually rapid progression of leukoencephalomyelopathy.     

急性有机磷中毒患者的血钾变化及临床意义的探讨

目的：探讨急性有机磷中毒患的血清钾变化及其临床意义。方法：对68例发病6小时内的急性有机磷中毒的患入院后测定血清钾，并根据不同的中毒程度、中毒方式、发病时间分组在比较，并设正常对照组对照。结果：中毒各组均有明显的低钾血症，与对照组比较均有显性意义（P＜0．01）,且重度中毒组与中、轻度组比较亦有显性意义（P＞0．05），但两种不同的中毒途径与不同的中毒时间的组间血清钾的比较无显性意义（P＞0．05）。结论：急性有机磷中毒可致明显的低钾血症，中毒越重，低钾血症越明显。在发病早期应注意监测血清钾的变化，及时纠正低血钾，预防或减轻中毒后严重合并症的产生。     

Testing for skin sensitization according to the notification procedure for new chemicals: the Magnusson and Kligman test

The notification procedure for new chemicals in the European Union (called the Chemicals Act in Germany) requires a skin sensitization test when the amount of a new chemical produced exceeds 100 kg/year. The preferred test is that of Magnusson and Kligman; more than 90% of the tests submitted are performed with it. Though the Magnusson and Kligman test is described in the literature, and in the test guidelines of the European Union and of the OECD, discrepancies do occur in the performance of the test between test laboratories. In this paper, recommendations are given for standardized performance of the Magnusson and Kligman test.     

电化学共沉积制备有机高聚物/钙磷复合陶瓷膜层--Ⅱ XPS、SIMS表征及力学性能研究

通过电化学共沉积方法制备具有生物活性的有机高聚物／钙磷陶瓷复合膜层。用XPS、SIMS等对复合膜层的化学组分进行表征，证明少量有机高聚物可能在分子层次上掺杂形成有机高聚物／羟基磷灰石复合膜层。对电沉积HAP陶瓷膜层进行微刮痕实验表明，陶瓷膜层与金属基体的结合力得到显著改善。     

Effect of increased distal sodium delivery on organic osmolytes and cell electrolytes in the renal outer medulla

Sodium absorption in distal tubule segments was stimulated by increasing the distal delivery via infusion of hypertonic saline. In these animals, and in control rats, electrolyte concentrations in thick ascending limb cells, light and dark cells of the collecting duct in the outer and inner stripe of the outer medulla and in cells of the proximal straight tubule (outer stripe only) were studied. The measurements were performed by electron microprobe analysis of freeze-dried cryosections of the outer medulla. In addition, organic osmolytes (glycerophosphorylcholine, betaine and myo-inositol) were measured by high performance liquid chromatography in cortex and outer medulla. Augmented delivery of sodium chloride to the distal tubule was associated with increased sodium concentrations of thick ascending limb cells both in the outer and inner stripe and of medullary collecting duct light and dark cells in the outer stripe. While the sum of organic osmolyte concentrations was 28% higher in the outer medulla of the salt-loaded animals compared with controls, this value was unchanged in the renal cortex. These findings indicate that the primary event underlying stimulation of sodium absorption along the thick ascending limb during increased distal sodium delivery is enhanced entry of sodium across the apical cell membrane. This would be expected to lead to higher cell sodium concentrations and stimulation of basolateral active Na-K-exchange. The enhanced transport activity of outer medullary tubules may be associated with increased interstitial tonicities and intracellular retention of organic osmolytes.