The microvascular architecture of the three layers in left ventricular wall of25 normal children hearts was studied by scanning electron microscopy of the vascu-lar casts,histochemical method(alkaline phosphatase stain)and light microscopy ofIndia-ink injection.A true three dimensional spatial configuration of the microcir-culation unit was obtained.The arteriolar configuration had very different characteristics from one anotherin the three layers examined.The arterioles in the epicardium presented a similarmesh distribution;tree-like branches were distributed mainly in the myocardium;thearterioles in subendocardium appeared as a plexiform distribution.The spatial struc-tures of capillary had several different characteristics:a close capillary network inthe epicardium;the capillary mesh in the myocardium showed the appearance of anarcade-type and vertex-like arrangement and parallelly arranged to the myofibers;the one in the subendocardium seems to be sheet-like.Arteriole casts from the three areas were essentially the same in the fact thatthey frequently showed prominent endothelial nuclear impressions and ring-shapeimpressions.The unusual appearance of venules called“turnip root”and“ginsengroot”was found in the three regions.The diameter of capillaries are 7.2?1.9?m,4.3?1.0?m and 5.4?1.6?m in theepicardium,myocardium and endocardium respectively.The difference between thediameter of capillaries in three layers is highly significant(P0.05).

The authors used a microvascular corrosion cast/scanning electron microscopy (SEM) technique to study the microvascular bed of the muscles of the medial pterygoid and masseter in two normal babies. The cast were prepared by perfusing the microvascular vessels with methyl methacrylate. Under SEM, the patterns of branches of the arteriole are: 1. tree like ramifications; 2. symmetrical branching; 3. fine plexiform branching. Moreover, the casts of arterial and venous vessels showed on their surfaces the typical imprint of the endothelial lining. Therefore, the venous vessels could be easily identified by the round nuclei of the endothelial cells of the venous vessels. On the other side, arteries and arterioles displayed spindle shaped nuclear imprints, oriented along the direction of the vessel. The morphological and functional characterization of the imprint of the precapillary sphincter and the two-grade anastomoses of the arcade arteries. The diameter of the capillary casts (mean?SE) was 5.6?1.9?m. Two or three capillaries join together to form a postcapillary venules, sometimes a single capillary reaches a major venous trunk was observed. These structural features were considered to play an important physiological role in the microcirculation in skeletal muscle.

Distribution and morphologic features of AChE-containing neurons were observed by the technique of AChE regeneration. There are three kinds: AChE-staining cells--heavily stained cells, medium stained cells and lightly stained cells. Most heavily stained cells are larger multipolar cells. They are located mainly in striatum, basal forebrain, hypothalamus, substantia nigra, locus coeruleus, red nucleus, ventral tegmental nucleus, parabrachial nucleus, pontine tegmental nucleus and the motor nuclei of cranial nerves. The results of AChE-staining were compared with the date of ChAT immunohistochemistry. The relationship between AChE and cholinergic neurons as well as the nature of AChE-containing neurons were discussed.

The methods of morphometry,histologic fluorescence quantification and quantita-tive histochemistry,RNA content,lipofuscin (Lp) content,nucleolar volume andneuron number (cells/250?m) were applied in the study of neurons in hippocampalCA_3 area in 4 age groups of Wistar rats (1,3,17,30 months).RNA content,nucleolar volume and neuron number decrease with advancingage.The difference between adult (17 months) and aged (30 months) rats weresignificant (P

The surface structure of the pineal recess in rat (Sprague-Dawley) was observedby using scanning electron microscope.Because of the distribution ofthe cilia and microvilli shows a regular changes from peripheralarea to central area in the recess,the surface of the recess can be divided intoperipheral,transitional and central zone.In the peripheral zone,there aresupraependymal cells in different appearance among those tufted cilia.Thetransitional zone is between peripheral and central zone.The cilia in this zone arefewer than those of the peripheral zone.We have observed the neuron-like suprae-pendymal cell with a splndle shaped cell body and numerous small holes as well assupraependymal nerve fibers in the floor of this zone.The ending of the nerve fiberis varicose.Some smooth areas devoid of cilia and microvilli were presentin the central zone.There are also neuron like cells with slender processes,roundsupraependymal cell,some fine crisscrossing fibers and some sprouted cilia.Acluster of bleb-like structures are present in this zone.The relations between thesurface of the recess and the pineal gland are discussed.

Thioredoxin reductase (TrxR) is one class of the most important antioxidant selenoproteins and is involved in regulating tumor genesis and progression. It has been reported that naphthoquinones can target and inhibit TrxR1 activity therefore produce reactive oxygen species (ROS) mediated by TrxR1, resulting into cellular redox imbalance and making the naphthoquinone compounds to become potential antitumor chemotherapy drugs. The purpose of this work is to explore the interaction between TrxR1 and menadione using biochemical and mass-spectrometric (MS) analyses, to further reveal the detailed mechanisms of TrxR1-mediated naphthoquinone reduction and inhibition of TrxR1 by naphthoquinone compounds. Using the site-directed mutagenesis and recombinantly expressed TrxR1 variants, we measured the steady-state kinetic parameters of menadione reduction mediated by TrxR1 and its variants, performed the inhibition analysis of menadione on TrxR1 activity, and eventually identified the interaction between menadione and TrxR1 through MS analysis. We found that Sec-to-Cys mutation at residue of 498 significantly enhanced the efficiency of TrxR1-mediated menadione reduction, though the Sec⁴⁹⁸ is capable to catalyze the menadione reduction, indicating that TrxR1-mediated menadione reduction is dominantly in a Se-independent manner. Mutation experiments showed that Cys⁴⁹⁸ is mainly responsible for menadione catalysis in comparison to Cys⁴⁹⁷, while the N-terminal Cys⁶⁴ is slightly stronger than Cys⁵⁹ regarding the menadione reduction. LC-MS results detected that TrxR1 was arylated with one molecule of menadione, suggesting that menadione irreversibly modified the hyper-reactive Sec residue at the C-terminus of selenoprotein TrxR1. This study revealed that TrxR1 catalyzes the reduction of menadione in a Se-independent manner meanwhile its activity is irreversibly inhibited by menadione. Hereby it will be useful for the research and development of naphthoquinone anticancer drugs targeting TrxR1.
Catalysis ; Drug Development ; Oxidation-Reduction ; Thioredoxin Reductase 1/metabolism* ; Vitamin K 3/metabolism*