Variation in Quantitative Requirements for Na for Transport of Metabolizable Compounds by the Marine Bacteria Alteromonas haloplanktis 214 and Vibrio fischeri

The rates of uptake by Alteromonas haloplanktis of 19 metabolizable compounds and by V. fischeri of 16 of 17 metabolizable compounds were negligible in the absence of added alkali-metal cations but rapid in the presence of Na. Only d-glucose uptake by V. fischeri occurred at a reasonable rate in the absence of alkali-metal cations, although the rate was further increased by added Na, K, or Li. Quantitative requirements for Na for the uptake of 11 metabolites by A. haloplanktis and of 6 metabolites by V. fischeri and the characteristics of the Na response at constant osmotic pressure varied with each metabolite and were different from the Na effects on the energy sources used. Li stimulated transport of some metabolites in the presence of suboptimal Na concentrations and for a few replaced Na for transport but functioned less effectively. K had a small capacity to stimulate lysine transport. The rate of transport of most of the compounds increased to a maximum at 50 to 300 mM Na, depending on the metabolite, and then decreased as the Na concentration was further increased. For a few metabolites, the rate of transport continued to increase in a biphasic manner as the Na concentration was increased to 500 mM. Concentrations of choline chloride equimolar to inhibitory concentrations of NaCl were either not inhibitory or appreciably less inhibitory than those of NaCl. All metabolites examined accumulated inside the cells against a gradient of unchanged metabolite in the presence of Na, even though some were very rapidly metabolized. The transport of l-alanine, succinate, and d-galactose into A. haloplanktis and of l-alanine and succinate into V. fischeri was inhibited essentially completely by the uncoupler 3,5,3',4'-tetrachlorosalicylanilide. Glucose uptake by V. fischeri was inhibited partially by 3,5,3',4'-tetrachlorosalicylanilide and also by arsenate and iodoacetate.     

Sensitivity of some marine bacteria, a moderate halophile, and Escherichia coli to uncouplers at alkaline pH.

The inhibitory effects of uncouplers on amino acid transport into three marine bacteria, Vibrio alginolyticus 118, Vibrio parahaemolyticus 113, and Alteromonas haloplanktis 214, into a moderate halophile, Vibrio costicola NRC 37001, and into Escherichia coli K-12 were found to vary depending upon the uncoupler tested, its concentration, and the pH. Higher concentrations of all of the uncouplers were required to inhibit transport at pH 8.5 than at pH 7.0. The protonophore carbonyl cyanide m-chlorophenylhydrazone showed the greatest reduction in inhibitory capacity as the pH was increased, carbonyl cyanide p-trifluoromethoxyphenylhydrazone showed less reduction, and 3,3',4',5-tetrachlorosalicylanilide was almost as effective as an inhibitor of amino acid transport at pH 8.5 as at pH 7.0 for all of the organisms except A. haloplanktis 214. Differences between the protonophores in their relative activities at pHs 7.0 and 8.5 were attributed to differences in their pK values. 3,3',4',5-Tetrachlorosalicylanilide, carbonyl cyanide m-chlorophenylhydrazone, 2-heptyl-4-hydroxyquinoline-N-oxide, and NaCN all inhibited Na+ extrusion from Na+-loaded cells of V. alginolyticus 118 at pH 8.5. The results support the conclusion that Na+ extrusion from this organism at pH 8.5 occurs as a result of Na+/H+ antiport activity. Data are presented indicating the presence in V. alginolyticus 118 of an NADH oxidase which is stimulated by Na+ at pH 8.5.     

An ultrastructural study of dentinogenesis and amelogenesis in rat molar tooth germs cultured in vitro

Summary Molar tooth germs from three-day-old rats were cultured successfully for fourteen days, permitting the study of the development in vitro of both extracellular matrix and cellular elements such as odontoblasts and ameloblasts. The ultrastructure of the cultured tooth germs was compared with the ultrastructure of tooth germs in vivo at a comparable developmental stage. Progenitor cells of odontoblasts and ameloblasts were found to differentiate in vitro. Odontoblasts seemed to contain more lysosome-like bodies and fewer secretory granules than in vivo. They formed normally mineralizing dentine or a thick layer of dense, unmineralized predentine with incidentally some amorphous, extracellular material. Enamel was exclusively present opposite well developed dentine. It was often hyperor hypomineralized and enamel rods were not as regularly shaped as in vivo. In places where no enamel formation had taken place, large amounts of amorphous extracellular material were sometimes seen. From these observations it can be concluded that cellular development in cultured tooth germs appeared more or less normal, but extracellular matrix formation and mineralization were sometimes disturbed.     

Further studies on the sub-units of α-crystallin

1. A new procedure is described for the purification of alpha-crystallin, including: preparative zone electrophoresis, density-gradient centrifugation and gel filtration. The total amino acid composition of highly purified samples prepared according to this procedure has been determined. 2. Evidence is presented for the presence of intermediates in the urea-induced splitting of alpha-crystallin into sub-units. A possible mechanism for this splitting is proposed. 3. The recombination of sub-units has been studied by polyacrylamide-gel electrophoresis and ultracentrifugal analysis. As judged from these criteria, only a partial recovery of starting material was obtained. 4. The origin of the minor bands in the electrophoretic pattern of alpha-crystallin on 7m-urea-polyacrylamide gel has been investigated. No evidence was found that their presence is due to carbamoylation or sulphide-disulphide interchange. They probably arise from isomerization. 5. The mean molecular weight of the sub-units was calculated to be 24000 (Archibald's method). Determination of the sedimentation-diffusion equilibrium revealed a value of 21000 at the meniscus. Assuming that all sub-units contain one cysteine residue/molecule, 23000 can be derived for the mean molecular weight.     

Ultrastructural localization of dentine phosphoprotein in rat tooth germs by immunogold staining

Summary Dentine phosphoprotein (DPP) was localized on thin frozen sections of fixed rat tooth germs by indirect immunogold staining. Antisera were directed against DPP and against glutaraldehyde-treated DPP and were characterized by immuno-electroblotting. In odontoblasts, DPP was found to be localized in the cisternae of the rough endoplasmic reticulum (RER) and the Golgi apparatus and in Golgi-associated vesicles. Odontoblastic processes were moderately positive for DPP and dentine was intensely labeled on frozen sections of unfixed tissue. Predentine showed a slight immunoreactivity. These results indicate the synthesis of DPP in the RER, its accumulation in the Golgi apparatus and its vesicular transport and secretion via the odontoblastic processes into dentine. The close association of the gold particles with the dentinal collagen fibres makes a role of DPP in linking mineral to collagen conceivable. Matrix vesicles were negative for DPP, suggesting that the protein is not present at the sites of matrix vesicleassociated nucleation.     

Exposure of neural crest cells to elevated glucose leads to congenital heart defects, an effect that can be prevented by N-acetylcysteine

BACKGROUND: Diabetes mellitus during pregnancy increases the risk for congenital heart disease in the offspring. The majority of the cardiovascular malformations occur in the outflow tract and pharyngeal arch arteries, where neural crest cells are essential for normal development. We studied the effects of specific exposure of neural crest cells to elevated glucose on heart development. Antioxidants reduce the damaging effect of glucose on neural crest cells in vitro; therefore, we investigated the effect of supplementing N-acetylcysteine in vivo. METHODS: Cardiac neural crest of HH 8-12 chicken embryos was directly exposed by a single injection in the neural tube with 30 mM D-glucose (or 30 mM L-glucose as a control). To examine the effect of a reduction in oxidative stress, we added 2 mM N-acetylcysteine to the injected D-glucose. RESULTS: Exposure of neural crest cells to elevated D-glucose-induced congenital heart malformations in 82% of the embryos. In the embryos injected with L-glucose, only 9% developed a heart malformation. As expected, all malformations were located in the outflow tract and pharyngeal arch arteries. The frequency of heart malformations decreased from 82% to 27% when 2 mM N-acetylcysteine was added to the injected D-glucose. CONCLUSIONS: These data are the first to confirm that the vulnerability of neural crest cells to elevated glucose induces congenital heart malformations. The fact that N-acetylcysteine limits the teratogenicity of glucose implies that its damaging effect is mediated by an increase of oxidative stress in the neural crest cells.     

Regional differences in WT-1 and Tcf21 expression during ventricular development: implications for myocardial compaction

Background

Morphological and functional differences of the right and left ventricle are apparent in the adult human heart. A differential contribution of cardiac fibroblasts and smooth muscle cells (populations of epicardium-derived cells) to each ventricle may account for part of the morphological-functional disparity. Here we studied the relation between epicardial derivatives and the development of compact ventricular myocardium.

Results

Wildtype and Wt1^CreERT2/+ reporter mice were used to study WT-1 expressing cells, and Tcf21^lacZ/+ reporter mice and PDGFRα^-/-;Tcf21^LacZ/+ mice to study the formation of the cardiac fibroblast population. After covering the heart, intramyocardial WT-1+ cells were first observed at the inner curvature, the right ventricular postero-lateral wall and left ventricular apical wall. Later, WT-1+ cells were present in the walls of both ventricles, but significantly more pronounced in the left ventricle. Tcf21-^LacZ + cells followed the same distribution pattern as WT-1+ cells but at later stages, indicating a timing difference between these cell populations. Within the right ventricle, WT-1+ and Tcf21-lacZ+ cell distribution was more pronounced in the posterior inlet part. A gradual increase in myocardial wall thickness was observed early in the left ventricle and at later stages in the right ventricle. PDGFRα^-/-;Tcf21^LacZ/+ mice showed deficient epicardium, diminished number of Tcf21-^LacZ + cells and reduced ventricular compaction.

Conclusions

During normal heart development, spatio-temporal differences in contribution of WT-1 and Tcf21-^LacZ + cells to right versus left ventricular myocardium occur parallel to myocardial thickening. These findings may relate to lateralized differences in ventricular (patho)morphology in humans.     

556例多发伤患者的急诊救治临床分析

目的探讨多发伤患者的救治策略。方法回顾分析我科2000年1月至2008年5月急诊抢救的556例多发伤患者的临床资料。结果 16例患者经抢救无效死亡,死亡率2.88%;其余患者均经紧急抢救及行必要实验室检查,病情稳定,好转率达97.12%。平均抢救时间为(1.37±1.05)h。结论强化多发伤的急诊科早期救治,树立创伤急救"黄金1 h"观念,是提高多发伤患者生存率及降低死亡率的关键。