Development of a receptor on a foreign nerve fiber in a Pacinian corpuscle

When the sensory fiber of a Pacinian corpuscle (in cat mesentery) is transected (at the inferior mesenteric nerve) transduction fails within 30 hours: the nerve ending produces no generator potentials in response to mechanical stimulation. Electrically elicited nerve impulse conduction continues for at least another 18 hours. A transducer mechanism develops on a regenerating nerve fiber when this fiber enters the denervated corpuscle. Such transducer development takes place on myelinated fibers from the inferior mesenteric nerve, which normally supplies corpuscles, as well as on myelinated hypogastric nerve fibers, which normally do not go to corpuscles, including fibers larger than the original corpuscle afferents.     

Polyamine metabolism: a potential therapeutic target in trypanosomes

alpha-Difluoromethylornithine (RMI 71,782), a specific irreversible inhibitor of the first step in polyamine biosynthesis, that is, the formation of putrescine from ornithine by ornithine decarboxylase, cures mice infected with a virulent, rodent-passaged strain of Trypanosoma brucei brucei. This parasite is closely related to the trypanosomes that cause human sleeping sickness. The drug, which is remarkably nontoxic, was effective when administered in drinking water or by intubation. The ability of the compound to inhibit ornithine decarboxylase in vitro was demonstrated by the reduced amounts of putrescine synthesized from tritiated ornithine in Trypanosoma brucei suspensions. These observations direct attention to polyamine metabolism as a target for chemotherapy of parasitic diseases.     

Polyamines and plant stress: activation of putrescine biosynthesis by osmotic shock

The putrescine content of oat leaf cells and protoplasts increases up to 60-fold within 6 hours of exposure to osmotic stress (0.4 to 0.6 molar sorbitol). Barley, corn, wheat, and wild oat leaves show a similar response. Increased arginine decarboxylase activity parallels the rise in putrescine, whereas ornithine decarboxylase remains unchanged. DL-alpha-Difluoromethylarginine, a specific irreversible inhibitor of arginine decarboxylase, prevents the stress-induced rise in increase in arginine decarboxylase activity and putrescine synthesis, indicating the preferential activation of this pathway.     

Tumor suppression with a combination of alpha-difluoromethyl ornithine and interferon

alpha-Difluoromethyl ornithine and mouse type 1 interferon, when administered simultaneously, were highly toxic to B16 melanoma cells in culture. Oral administration of alpha-difluoromethyl ornithine suppressed B16 melanoma development in mice 85 percent whereas interferon given subcutaneously inhibited tumor growth only 24 percent. Total or near total suppression of tumor growth was observed in mice receiving both treatments.     

建昌鸭和天建杂交肉鸭蛋氨酸需要量的研究

本试验分别用建昌鸭,天建杂交肉鸭(天府肉鸭×建昌鸭白羽系)进行了蛋氨酸需要的研究。以期确定蛋氨酸的需要量。结果表明:在基础饲粮中添加适量的蛋氨酸可提高肉鸭的生产性能,饲喂基础饲粮的肉鸭血浆尿酸以及血浆游离赖氨酸、精氨酸、甘氨酸、鸟氨酸的含量显著提高,在后期饲喂高蛋氨酸水平的饲粮,可降低七周龄肉鸭的皮脂率,提高腿肌率。以体增重为主,综合考虑血浆尿酸、游离氨基酸和后期屠宰性能指标所确定的蛋氨酸需要量分别为天建杂交鸭前期(0—3周)0.390—0.441％、后期(4—7周)0.221—0.250％,建昌鸭前期(0—3周)0.310—0.374％、后期(4—7周)0.300—0.370％。     

Myocardial failure in cats associated with low plasma taurine: a reversible cardiomyopathy

Thousands of pet cats die each year with dilated cardiomyopathy, the cause of which is unknown. Although taurine is present in millimolar concentrations in the myocardium of all mammals, taurine depletion has not previously been associated with a decrease in myocardial function in any species. In this study, low plasma taurine concentrations associated with echocardiographic evidence of myocardial failure were observed in 21 cats fed commercial cat foods and in 2 of 11 cats fed a purified diet containing marginally low concentrations of taurine for 4 years. Oral supplementation of taurine resulted in increased plasma taurine concentrations and was associated with normalization of left ventricular function in both groups of cats. Since myocardial concentrations of taurine are directly related to plasma concentrations and low plasma concentrations were found to be associated with myocardial failure in cats, a direct link between decreased taurine concentration in the myocardium and decreased myocardial mechanical function is proposed.     

一例流浪猫巴尔通氏体病的诊断与治疗

通过对1例疑似猫巴尔通氏体病患猫进行症状观察、血常规、血液涂片等检查,确诊为猫巴尔通氏体病,并进行对因对症治疗,取得了良好的治疗效果。     

肉仔鸡血浆游离氨基酸浓度变化规律的研究

给４ 组共４０ 只肉仔鸡分别强饲无氮饲粮（ＮＦＤ）、ＮＦＤ＋ ３２ ｇ·ｋｇ－ １酶解酪蛋白（ＥＨＣ）,及以豆粕为惟一氮源的粗蛋白质量浓度为５０ 和２００ ｇ·ｋｇ－ １的饲粮,于强饲后５ ｍ ｉｎ,４,２４,３６ 及４８ ｈ,采集静脉血液,观测去蛋白血浆中诸氨基酸（ＰＦＡＡ）的变化规律。结果表明,ＰＦＡＡ 浓度与采食饲粮氨基酸含量及食后时间呈复杂的函数关系。ＰＦＡＡ 浓度仅可大致估计饲料氨基酸的有效性。     

Ornithine decarboxylase is important in intestinal mucosal maturation and recovery from injury in rats

A transient increase in ornithine decarboxylase activity and polyamine biosynthesis occurs in the intestinal mucosa of the newborn rat in the third week after birth. During this period, there is a rapid conversion of the mucosa from a fetal to a mature adult status. A similar increase in ornithine decarboxylase activity also accompanies the rapid recovery of the mucosa 1 week after an injury is induced by chemotherapy in adult rats. In vivo, alpha-difluoromethyl ornithine, a highly selective, enzyme-activated, irreversible inhibitor, suppresses these increases in mucosal ornithine decarboxylase and delays both intestinal mucosal maturation and recovery from injury. Thus increased ornithine decarboxylase activity, with the resultant increase in polyamine content, may play an essential role in intestinal mucosal maturation and regeneration in the rat.     

The molecular basis of the sparse fur mouse mutation

The ornithine transcarbamylase-deficient sparse fur mouse is an excellent model to study the most common human urea cycle disorder. The mutation has been well characterized by both biochemical and enzymological methods, but its exact nature has not been revealed. A single base substitution in the complementary DNA for ornithine transcarbamylase from the sparse fur mouse has been identified by means of a combination of two recently described techniques for rapid mutational analysis. This strategy is simpler than conventional complementary DNA library construction, screening, and sequencing, which has often been used to find a new mutation. The ornithine transcarbamylase gene in the sparse fur mouse contains a C to A transversion that alters a histidine residue to an asparagine residue at amino acid 117.     

Nδ-保护鸟氨酸的微波合成研究

[目的]用微波法合成Nδ-保护鸟氨酸。[方法]以L-鸟氨酸盐酸盐为原料,与碱式碳酸铜反应得到L-鸟氨酸铜络合物,在δ-氨基上分别引入苄氧羰基、叔丁氧羰基、芴甲氧羰基、乙酰基和邻苯二甲酰基,得到了Nδ-保护鸟氨酸铜络合物,微波辐射下用EDTA-2Na脱去铜离子,得到了Nδ-苄氧羰基鸟氨酸、Nδ-叔丁氧羰基鸟氨酸、Nδ-芴甲氧羰基鸟氨酸、Nδ-乙酰基鸟氨酸和Nδ-邻苯二甲酰基鸟氨酸5个Nδ-保护鸟氨酸。探讨了微波辐射功率、时间及投料比对脱铜反应的影响。[结果]脱铜反应的最佳反应条件为：n（Nδ-保护鸟氨酸铜络合物）∶n（EDTA）=1∶1.1～1∶1.2,微波辐射功率为250～300 W,反应时间为4～6 min,收率分别为93.2%、86.2%、88.7%、86.3%和86.4%（以Nδ-保护鸟氨酸铜络合物计）。产物结构经元素分析和1H NMR确证。[结论]该合成工艺对环境友好、简便、高效,产物收率与纯度均较高。     

Repression of ornithine transcarbamylase protein formation by arginine

Arginine-repressed cells of Escherichia coli W do not form a protein immunologically related to ornithine transcarbamylase. This was determined by lack of cross-reactivity of repressed cell extracts with rabbit antisera prepared against purified ornithine transcarbamylase. The results indicate that arginine acts by blocking the synthesis of the entire enzyme-protein.     

Aminoaciduria resulting from cycloleucine administration in man

Cycloleucine (1-aminocyclopentanecarboxylic acid) administration in cancer patients resulted in a reversible marked aminoaciduria consisting predominantly of cystine, ornithine, lysine, and arginine, with only minor elevations of other amino acids. Plasma levels of amino acids were essentially unchanged except for slight decreases in ornithine and lysine. This aminoaciduria is most likely due to a blockage by the drug of the renal tubular reabsorption of cystine, ornithine, lysine, and arginine, resulting in an aminoaciduria of the type seen in cystinuria.     

Daily rhythm in tyrosine concentration in human plasma: persistence on low-protein diets

The concentration of tyrosine in the plasma of normal males varies diurnally. It is lowest (9.5 +/- 0.35 micrograms per milliliter) between 0130 and 0230 hours and rises to a peak of 16.2 +/- 0.82 micrograms per milliliter by 1030 hours. This rhythm persists when subjects are maintained for 2 weeks on a diet that is very low in protein.     

N^δ-保护鸟氨酸的微波合成

[目的]用微波法合成N^δ-保护鸟氨酸。[方法]以L-鸟氨酸盐酸盐为原料,与碱式碳酸铜反应得到L-鸟氨酸铜络合物,在δ-氨基上分别引入苄氧羰基、叔丁氧羰基、芴甲氧羰基、乙酰基和邻苯二甲酰基,得到了N^δ-保护鸟氨酸铜络合物,微波辐射下用EDTA-2Na脱去铜离子,得到N^δ-苄氧羰基鸟氨酸、Nδ-叔丁氧羰基鸟氨酸、N^δ-芴甲氧羰基鸟氨酸、N^δ-乙酰基鸟氨酸和N^δ-邻苯二甲酰基鸟氨酸5个N^δ-保护鸟氨酸。探讨了微波辐射功率、时间及投料比例对脱铜反应的影响。[结果]脱铜反应的最佳反应条件为：n（N^δ-保护鸟氨酸铜络合物）∶n（EDTA）=1∶1.1～1∶1.2,微波辐射功率为250～300W,反应时间为4～6min,收率分别为93.2%、86.2%、88.7%、86.3%和86.4%（以N^δ-保护鸟氨酸铜络合物计）。产物结构经元素分析和1HNMR确证。[结论]该合成工艺对环境友好、简便、高效,产物收率与纯度均较高。     

Fast transport system of materials in mammalian nerve fibers

A fast transport system of materials is shown in cat sensory fibers of sciatic nerve. After injection of tritiated leucine into the lumbar seventh ganglia, the distribution of activity was measured in the sciatic nerves from 2 to 8 hours afterward. The distribution showed a crest of activity advancing down the fibers at a rate of approximately 410 millimeters per day. An intraaxonic locus of the activity was indicated by a block of the downflow induced by local freezing which causes the fibers to close off. Some of the activity in the nerve was due to free tritiated leucine, with most of it incorporated into polypeptide, soluble protein, and subcellular particulates.     

Linking long-term dietary patterns with gut microbial enterotypes

Diet strongly affects human health, partly by modulating gut microbiome composition. We used diet inventories and 16S rDNA sequencing to characterize fecal samples from 98 individuals. Fecal communities clustered into enterotypes distinguished primarily by levels of Bacteroides and Prevotella. Enterotypes were strongly associated with long-term diets, particularly protein and animal fat (Bacteroides) versus carbohydrates (Prevotella). A controlled-feeding study of 10 subjects showed that microbiome composition changed detectably within 24 hours of initiating a high-fat/low-fiber or low-fat/high-fiber diet, but that enterotype identity remained stable during the 10-day study. Thus, alternative enterotype states are associated with long-term diet.     

Ornithine decarboxylase stimulation in rat ovary by luteinizing hormone

In normal albino rats with a 4-day estrous cycle, the activity of ovarian ornithine decarboxylase undergoes a transitory rise on the evening of proestrus and only at that time. The response could be elicited by the administration of either luteinizing hormone or human chorionic gonadotrophin. When antiserum to luteinizing hormone was injected at 2 p.m. on the day of proestrus, the induction of ornithine decarboxylase was blocked, an indication that the enzyme is under luteinizing hormone control. The strategic positioning of the induction of ornithine decarboxylase between the normal release of luteinizing hormone and ovulation impties that putrescine is associated with the ovulatory process, and opens a new avenue of research on the control of ovulation.     

Contracture and catecholamines in mammalian myocardium

Contractures induced by KCl are produced in cat ventricular muscle after depletion of catecholamine stores by previous treatment with reserpine or by selective blocking of adrenergic receptor sites with propranalol. Contractures are reproducible for 2 to 3 hours and are markedly depressed by the addition of epinephrine. The relaxation of contracture induced by epinephrine parallels the eftect of this compound of shortening the duration of the normal twitch. The failure of the normal mammalian myocardium to maintain tension in solutions of high KCI concentration appears to be related to the endogenous amounts of catecholamines in the tissue.     

猫抓病及其他与巴尔通氏体感染有关的人畜共患病的研究进展

猫抓病是一种由巴尔通体属细菌引起的人畜共患病,在世界范围内广泛流行。猫是巴尔通体的主要宿主,通过猫蚤在猫之间传播。猫抓伤或咬伤是该病从猫传播到人的主要途径。文章就该病的病原学、流行病学、临床表现、实验室检查、病变特点、诊断及治疗方法等作一综述。