The absence of testicular atrophy and in vivo and in vitro effects on hepatocyte morphology and peroxisomal enzyme activities in male rats following the administration of several alkanols

Previous studies have shown that ethylhexanol (2-EH) and its oxidation products, but not n-hexanol, produce hepatomegaly, peroxisomal proliferation and hypotriglyceridaemia. In the present studies we have confirmed that at 1 mmol/kg doses, neither the linear nor branched chain alcohols induce testicular atrophy, hepatomegaly, peroxisome proliferation or hypolipidaemia. In vivo, neither the free alcohols nor their metabolic products seem to be responsible for the activity of the parent plasticiser. The released monoesters are probably the more potent metabolic products responsible for the hepatomegaly, peroxisomal proliferation and hypolipidaemia. This contention is supported by the in vitro hepatocyte data which demonstrate the induction of peroxisomal oxidative enzymes by MEHP whereas the alcohols were without effects.     

Prospective evaluation of chymopapain sensitivity in patients undergoing chemonucleolysis

Immediate anaphylactic reactions after intradiscal chymopapain (CP) injection may occur in 1% of patients undergoing chemonucleolysis (CN). Skin prick testing to CP (10 mg/ml), a prescreening history, and CP serum-specific IgE determinations by the RAST method were performed in order to identify patients presensitized to CP before CN. Follow-up repeat CP skin testing and serum-specific IgE were done 2 to 6 weeks after CN to detect CP IgE-mediated sensitization resulting from the injection. Three of 84 patients who exhibited positive skin tests to CP before CN did not receive CP injections. Only one of the three patients (33%) was detected with elevated CP serum-specific IgE before CN. No immediate severe anaphylactic reactions caused by CP injection were encountered in the remaining 81 patients with negative CP skin tests and RASTs before CN. Eight (10%) nonlife-threatening immediate and late reactions were associated with conversion from negative skin tests and RASTs before CN to positive skin tests or RASTs after CN. Overall, 19 of 52 (37%) patients who returned for follow-up testing developed cutaneous sensitization to CP after CN. Despite the fact that RAST values after CN in these patients were significantly higher (p less than 0.002) than those with negative skin tests after CN, the sensitivity of the RAST was only 72% for identifying patients who developed positive CP skin tests after CN. This study demonstrated that CP skin testing is essential for prescreening patients because it was more sensitive than RAST for identification of CP sensitivity both before and after CN. Late allergic reactions and cutaneous sensitization to CP were common sequelae of CN.     

新生儿膈疝胸腔镜治疗后存活率的影响因素分析

目的先天性膈疝(congenital diaphragmatic hernia,CDH)是指因先天性膈肌结构缺损致腹腔内容物疝入胸腔。本研究旨在总结首都儿科研究所附属儿童医院近5年入院诊断为CDH患儿的临床资料,分析CDH患儿生存率的影响因素,为患儿产前及生后病情评估提供循证依据,进而提高CDH患儿诊疗技术。方法本组患儿经产科儿科产前咨询,新生儿外科医生产房待产,生后经绿色通道转运至我中心SNICU,由新生儿外科与超声科、NICU、心脏外科等多学科对患儿进行围术期的联合诊疗,首选胸腔镜治疗。结果2014年4月至2019年12月经我中心普通(新生儿)外科诊治的58例CDH患儿中,42例行胸腔镜手术修补膈肌,35例存活,7例死亡,死亡率占总经治量的12%,其中6例为胸腔镜手术中转为开放手术,4例存活,2例死亡,死亡率占总经治量3%;13例行开放手术修补膈肌,5例存活,8例死亡。另有3例产前诊断发现CDH,术前死亡。存活患儿与死亡患儿在产前诊断孕周、住院时间、有创通气时间、手术时机及手术方式上比较差异存在统计学意义(P<0.05)。结论胸腔镜手术在新生儿CDH治疗中安全可行。产前诊断时间、手术时机、手术方式是预测患儿预后情况的重要指标。     

Excitatory effect of acetylcholine on different types of neurons in the first somatosensory neocortex of the rat: laminar distribution and pharmacological characteristics

In rats anaesthetized with either urethane, pentobarbital or fluothane the effects of acetylcholine, cholinergic agonists and antagonists (applied by iontophoresis) were studied on single cortical neurons of first somatosensory region. The laminar distribution of the neurons excited by acetylcholine was determined by the reconstruction of each electrode track based on a dye-deposit made at the last recording site. Neurons were identified using antidromic stimulation of the pyramidal tract, the ventrobasal thalamus and the corpus callosum. Neurons excited by acetylcholine could be segregated into two groups: one encompassing layer Vb and the upper part of layer VI, the other more deeply located at the limit between the cerebral cortex and the subjacent white matter. Neuronal responses to glutamate and nicotine, unlike those to actylcholine were evenly distributed in the cortex. Pyramidal tract neurons had corticothalamic neurons were frequently excited by acetylcholine and were shown to be located with the first group of acetylcholine sensitive neurons. Commissural neurons were rarely excited by acetylcholine and were not restricted to either group. The analysis of neuronal responses to acetylcholine and various agonists (carbachol, nicotine, acetyl-beta-methylcholine, carbamyl-beta-methylcholine, butyrylcholine) and antagonists (atropine, mecamylamine) revealed a prominent but not exclusive muscarine character. It is included (i) that cortical neurons of first somatosensory cortex which are excited by acetylcholine belong to two populations, one consisting, at least in part, of projection neurons (upper group) and the other of interneurons (lower group); (ii) that cortical acetylcholine receptors are of a 'mixed' type strongly weighted toward the muscarinic side.     

Functional validation of projection topography in the nigrostriatal dopamine system

Anatomical investigations have revealed that the nigrostriatal pathway is topographically organised. In two experiments, nigrostriatal topography was investigated with catecholamine specific procedures, using paradigms which reflect the functional activity of dopaminergic neurones. Data were analysed with the intention of discovering possible relationships between the mesencephalic location of stimulating electrodes or injection cannulae, the extent and location of dopamine histofluorescence depletion within the striatum, and the effects of amphetamine and apomorphine on rotational behaviour. In animals pretreated with 250 mg/kg alpha-methyl-p-tyrosine it was found that unilateral stimulation with medially-placed nigral electrodes produced maximal depletion of dopamine histofluorescence in anterior dorso-medial regions of the striatum, while laterally-located electrodes principally depleted posterior, ventro-lateral areas. In the second experiment, 2 micrograms of 6-hydroxydopamine in a volume of 0.5 microliter was injected unilaterally at varying loci within the ventral midbrain of animals pre-treated with desmethylimipramine (25 mg/kg). It was discovered that the lateral injection coordinate was significantly associated with both the extent and location of the depletion of dopamine-related fluorescence from the ipsilateral striatum. Rotational behaviour, induced by dopamine-agonists was related firstly, to the overall extent of dopamine depletion from the striatum, and secondly, the contraversive turning induced by apomorphine in particular was related to the dorsoventral coordinate of the mesencephalic 6-hydroxydopamine injection. The results provide functional validation for the pattern of topographical projection within the nigrostriatal dopaminergic system proposed on the basis of intracellular tracing techniques.     

Association between leukocyte count and the presence and extent of coronary atherosclerosis as determined by coronary arteriography

Angiographic evidence of coronary artery disease (CAD) was correlated with leukocyte count (WBC), red cell count (RBC), cigarette smoking, age, sex, and cholesterol and triglyceride concentrations in 573 patients who underwent coronary arteriography and who did not have evidence of infection or recent myocardial infarction. Smokers had a higher WBC (7,449 ± 1,964leukocytes/mm³ vs 6,533 ± 1,557, p = 0.0001) and RBC (4.921 × 10⁶ ± 0.491 × 10⁶ erythrocytes/mm³ vs 4.753 × 10⁶ ± 0.480 × 10⁶ p = 0.0001) than nonsmokers. Patients with CAD had a higher WBC (7,280 ± 1,926 vs 6,664 ± 1,700, p = 0.0005) and RBC (4.903 × 10⁶ ± 0.488 vs 4.777 × 10⁶ ± 0.485 × 10⁶, p = 0.0062) than those with normal coronary arteriograms. A positive correlation between WBC and the severity of CAD (sum of arterial diameter narrowing) was noted (r = 0.16, p = 0.0001). Multiple regression showed an independent contribution of WBC in predicting severity of CAD (F = 9.26, p = 0.0025), after accounting for the effects of age, sex, serum cholesterol and triglyceride levels. When smoking was entered into the equation, the contribution of WBC in predicting the severity of angiographic CAD became weaker (F = 4.46, p = 0.035). Similar relations were seen when only smokers were analyzed and when patients with history of remote myocardial infarction were excluded. In nonsmokers these associations became either insignificant or much weaker. Thus, the relation of WBC, and RBC with CAD is mainly due to the elevation of WBC and RBC and the increase of CAD risk induced by cigarette smoking.     

CO and CN? syntheses by [FeFe]-hydrogenase maturase HydG are catalytically differentiated events

The synthesis and assembly of the active site [FeFe] unit of [FeFe]-hydrogenases require at least three maturases. The radical S-adenosyl-l-methionine HydG, the best characterized of these proteins, is responsible for the synthesis of the hydrogenase CO and CN⁻ ligands from tyrosine-derived dehydroglycine (DHG). We speculated that CN⁻ and the CO precursor ⁻:CO₂H may be generated through an elimination reaction. We tested this hypothesis with both wild type and HydG variants defective in second iron-sulfur cluster coordination by measuring the in vitro production of CO, CN⁻, and ⁻:CO₂H-derived formate. We indeed observed formate production under these conditions. We conclude that HydG is a multifunctional enzyme that produces DHG, CN⁻, and CO at three well-differentiated catalytic sites. We also speculate that homocysteine, cysteine, or a related ligand could be involved in Fe(CO)_x(CN)_y transfer to the HydF carrier/scaffold.Many microorganisms can either oxidize molecular hydrogen or reduce protons according to the reaction H₂ = 2H⁺ + 2 e⁻. The enzymes that catalyze this reaction fall into two phylogenetically unrelated groups, the [NiFe]- and [FeFe]-hydrogenases (1, 2). Initial crystallographic studies of the [FeFe]-hydrogenases from Clostridium pasteuranium (3) and Desulfovibrio desulfuricans (4) showed that the active site is composed of a conventional [4Fe-4S] cubane connected by a cysteine thiolate to a binuclear FeFe unit, in which each iron ion is terminally coordinated by one CN⁻ ligand and one CO ligand and by a third CO molecule that bridges the two metals (5). Unexpectedly, we also found that a small molecule first postulated (6), and now indirectly confirmed (7), to be dithiomethylamine (DTMA) bridges the two Fe ions (Fig. 1).Open in a separate windowFig. 1.[FeFe]-hydrogenase H-cluster from D. desulfuricans (6). Only the cysteine residue bridging the [4Fe-4S] and [FeFe] subsites is depicted as Cys. The cysteine ligands of the [4Fe-4S] cluster are shown as straight lines.The [4Fe-4S] cubane bridged to the binuclear [FeFe] unit has been collectively called the H-cluster (1). Work from several laboratories has shown that the maturation of the [FeFe] center requires at least three protein maturases: HydF that has GTPase activity and appears to be both a [FeFe] center scaffold and carrier (8, 9), HydG that synthesizes CO and CN⁻ from tyrosine (10–13), and HydE that, by elimination, should be involved in the synthesis of the DTMA bridge (14, 15). Both HydE and HydG are members of the large radical S-adenosyl-l-methionine (SAM) protein family (16, 17). With the recent reports of HydG crystal structures from Carboxydothermus hydrogenoformans (Ch) by us (18) and from Thermoanaerobacter italicus (Ti) by Dinis et al. (19), X-ray models are now available for the three maturases (20, 21); however, unambiguous structure-function relationships have been proposed only in the case of HydG. Indeed, site-directed mutational studies have shown that CO and CN⁻ syntheses are affected by either the deletion of the maturase C-terminal region, where a second iron-sulfur cluster binds (22), or Cys-to-Ser mutations in its corresponding CxxCx₂₂C binding motif (10, 13). In addition, it has been shown that HydG synthesizes Fe(CO)_x(CN)_y precursors (x = 1 or 2; y = 1) of the [FeFe] catalytic unit (23). The two HydG crystal structures are very similar at the SAM and [4Fe-4S] cluster-containing (β/α)₈ TIM-like barrel, common to several radical SAM proteins (16) (Fig. 2). Conversely, there are significant differences in the composition of the extra C-terminal second (s) iron-sulfur cluster. In our crystals, ChHydG lacks this center (18), whereas TiHydG coordinates a [4Fe-4S]_s cluster in one of the two molecules of the asymmetric unit and a second center with a fifth iron in the other molecule (19). This fifth iron has been described as being bound by His265, a putative alanine molecule and a sulfide bridge to a [4Fe-4S] unit coordinated by the CxxCx₂₂C motif. Two water molecules complete the octahedral Fe coordination (19). Here the different second cluster structures are collectively called [FeS]_s.Open in a separate windowFig. 2.Structures of (A) Ch HydG depicting tunnel I, the SAM cofactor, and [4Fe-4S] cluster (Top Right), the tyrosine active site cavity (Top Center), tunnel II, and the Cl⁻ binding cavity (Bottom Center) (18) and (B) Ti HydG with its additional second iron-sulfur cluster (19).     

先天性神经母细胞瘤发病机制与临床特点的研究进展CSCD

神经母细胞瘤是儿童最常见的颅外实体肿瘤,来源于肾上腺髓质或交感神经节。先天性神经母细胞瘤约占神经母细胞瘤患儿总数的5%,大多数患儿于出生后1个月内确诊。与1岁以上神经母细胞瘤患儿相比,新生儿神经母细胞瘤有其独特的病程。本文就先天性神经母细胞瘤的发病机制、临床表现、治疗方法以及预测患儿长期预后的生物学因素进行综述。     

Cracking taste codes by tapping into sensory neuron impulse traffic

Insights into the biological basis for mammalian taste quality coding began with electrophysiological recordings from "taste" nerves and this technique continues to produce essential information today. Chorda tympani (geniculate ganglion) neurons, which are particularly involved in taste quality discrimination, are specialists or generalists. Specialists respond to stimuli characterized by a single taste quality as defined by behavioral cross-generalization in conditioned taste tests. Generalists respond to electrolytes that elicit multiple aversive qualities. Na(+)-salt (N) specialists in rodents and sweet-stimulus (S) specialists in multiple orders of mammals are well characterized. Specialists are associated with species' nutritional needs and their activation is known to be malleable by internal physiological conditions and contaminated external caloric sources. S specialists, associated with the heterodimeric G-protein coupled receptor T1R, and N specialists, associated with the epithelial sodium channel ENaC, are consistent with labeled line coding from taste bud to afferent neuron. Yet, S-specialist neurons and behavior are less specific than T1R2-3 in encompassing glutamate and E generalist neurons are much less specific than a candidate, PDK TRP channel, sour receptor in encompassing salts and bitter stimuli. Specialist labeled lines for nutrients and generalist patterns for aversive electrolytes may be transmitting taste information to the brain side by side. However, specific roles of generalists in taste quality coding may be resolved by selecting stimuli and stimulus levels found in natural situations. T2Rs, participating in reflexes via the glossopharynygeal nerve, became highly diversified in mammalian phylogenesis as they evolved to deal with dangerous substances within specific environmental niches. Establishing the information afferent neurons traffic to the brain about natural taste stimuli imbedded in dynamic complex mixtures will ultimately "crack taste codes."