The therapeutic effect and mechanism of Chinese medicine Xuan-Yun-Ding on posterior circulation ischemia with vertigo in a rabbit model.

The aim of research is to unveil the mechanisms of the beneficial effects of XYD on PCIV in a rabbit model. 40 New Zealand white rabbits were randomly divided into 5 groups,including normal control group (NC), model control group (MC), low-dose of XYD group (LXYD), high-dose of XYD group (HXYD) and Yang-Xue-Qin-Nao group (YXQN). PCIV rabbit model was established by feeding high-fat diet companied with paravertebral sclerotherapy and rotation exercise. The general observation, step-down test, rheoencephalogram, blood tests, histopathological detection and the plasma concentration of the effective component of XYD were investigated. After pharmacological intervening, the step-down time, REG, PL, IPL, blood viscosity, the levels of blood lipids, CRGP were significantly improved. Moreover, the vertebral artery showed the reduced stenosis of arterial lumen and less proliferation of fibrous tissue in the arterial wall in the LXYD, HXYD and YXQN group. Based on the LC-MS detection, the blood concentrations of puerarin in the LXYD and HXYD group were significantly increased after pharmacological intervening. XYD could ameliorate the symptoms of vertigo, Qi-deficiency and blood stasis in PCIV rabbits via effectively regulating the levels of blood lipids and vasoactive substances, decreasing blood viscosity, increasing CBF and protecting vestibular function.

Posterior osseous bridging of C1.

The sulcus of the vertebral artery is located behind the lateral mass of the atlas and in some cases is converted into a foramen by anomalous ossification known as the posterior ponticulus (osseous bridge). This study involved anatomical observations of 158 isolated anatomical specimens of dry C1 vertebrae. The incidence and types of posterior osseous bridging were identified for the 158 dry samples of atlas vertebrae. In nine (5.6%) dry C1 vertebrae, partial osseous bridging was detected (bilaterally in eight vertebrae and unilaterally on the left in one). Complete osseous bridging (arcuate foramen) was observed in six (3.8%) dry C1 vertebrae (bilaterally in one vertebra, unilaterally on the left in three, and on the right in two). Awareness of the types of posterior osseous bridging of C1 in craniocervical junction surgery is essential, and may be helpful in surgical interventions in this region.

An investigation of a sympathetic innervation of the vertebral artery in primates: is there a neurogenic substrate for vasoconstriction?

Vasoconstriction of the vertebral artery may be neurogenic in origin. Although the existence of a perivascular sympathetic plexus of the vertebral artery is not in doubt, no method used to date has conclusively demonstrated a direct sympathetic innervation of the vascular smooth muscle cells and, hence, vasomotor function. It was the aim of this study, therefore, to visualise and localise noradrenergic fibres in the wall of the vertebral artery. Intracranial vertebral artery specimens (10 vervet monkeys and 10 baboon vessels) were sectioned (40 mm serial sections) and treated with anti-tyrosine hydroxylase, anti-dopamine b-hydroxylase, and anti-chromogranin-A antibodies. Some evidence of catecholaminergic fibres in the tunica adventitia but not penetrating the external elastic lamina or tunica media of the vertebral artery wall was seen. These findings were confirmed by electron microscopy. It was concluded that although a perivascular sympathetic plexus exists, the vertebral artery of primates was not shown to have a direct sympathetic innervation and a neurogenic vasoconstrictor function is unlikely.

Development of gold stents for the treatment of intracranial aneurysms: an experimental study in a canine model.

BACKGROUND AND PURPOSE: Gold has often been used in medicine because of its radiopacity and flexibility. To perform stent-supported coil embolization of intracranial aneurysms, we prepared a gold stent and examined its flexibility, radiopacity, and thrombogenic properties in comparison with a stainless steel device implanted in vitro and in vivo. METHODS: Gold stents were prepared by plating gold on stainless steel stents as a template. Their mechanical properties and trackability in vitro were determined and compared with those of stainless steel stents of the same design. Twenty gold stents and two stainless steel stents were implanted in canine external carotid, vertebral, and renal arteries, as a muscle branch of the maxillary arteries, to examine their performance in vivo. RESULTS: The gold stent exhibited much less radial force and greater flexibility than the stainless steel stent. It also demonstrated superior trackability and radiopacity in the experimental endovascular procedures in canines. Histologic examination showed good patency of the stented artery with slight endothelial hypertrophy. CONCLUSION: Although there is still room for more radial strength, less influence on intimal hypertrophy, a more suitable flexibility, and a smoother surface, the superior trackability and radiopacity of gold stents seem to support use of this device for the endovascular treatment of intracranial aneurysms.

Doppler sonography of normal fetal vertebral and internal carotid arteries during pregnancy.

PURPOSE: The aim of this study was to determine the resistance index (RI) in the fetus in both the vertebral artery and the internal carotid artery and to evaluate the relationship of those RIs with that of the umbilical artery. METHODS: In this prospective study, color Doppler examinations of the vertebral, internal carotid, and umbilical arteries were performed in fetuses with normal growth between 17 and 41 weeks' gestational age. For every week, the 10th, 50th, and 90th percentiles of the RIs in the 3 arteries plus the ratios of the RIs of the vertebral and umbilical arteries and of the internal carotid and umbilical arteries were calculated. RESULTS: In 225 examinations in 114 women, the vertebral and internal carotid arteries showed similar RI patterns, with higher RIs at mid gestation. The only difference was that the RIs in the internal carotid artery reached maximum values at a slightly later gestational age (26-28 weeks) than did those in the vertebral artery (24-25 weeks). Also, the RIs in the vertebral artery were slightly higher than were those in the internal carotid artery. RI values in the umbilical artery decreased progressively throughout gestation. Conversely, the ratios of the RIs in the vertebral and umbilical arteries and those of the RIs in the internal carotid and umbilical arteries increased slightly until the end of pregnancy, with the former ratios always higher than the latter ones. CONCLUSIONS: In normal fetuses, the pattern of blood flow resistance in the vertebral artery resembles that in the internal carotid artery. However, compared with the internal carotid artery, the vertebral artery shows higher absolute RIs with maximum values appearing earlier in the course of pregnancy.

Morphology of cerebral arteries.

A comparison of the major cerebral arteries between humans and rats shows many similarities, including anomalies in their general organization, the structure of these vessels at the light and electron microscope levels and their morphological changes associated with cerebral vascular diseases. The general organization of the major cerebral arteries shows the following main differences between humans and rats. In rats, the internal carotid arteries have become an integral part of the circle of Willis. In the anterior cerebral arteries, a common variation in humans is the underdevelopment of one of the two arteries, whereas in rats, buttonhole-like structures are common in one or both arteries. The anterior communicating artery present in humans is absent in rats. The olfactory artery is prominent in rats, but absent in humans. The posterior communicating artery in humans is the most variable component of the circle of Willis, being asymmetric in its origin, diameters and branches. Similarly, the posterior cerebral arteries in rats often exhibit asymmetrical origin from the basilar artery. There was some confusion in the literature regarding the name of the posterior cerebral arteries in rats, but this was caused mainly by misquotations and incorrect interpretations of the papers. In humans, most aneurysms occur in the anterior half of the circle of Willis, and the incidence is higher in females than males; the middle cerebral artery is most often the one to become occluded, and the vertebral arteries are common sites for thrombosis. The various channels that constitute collateral circulation in humans provide a margin of safety, so that in case of cerebral occlusion due to thrombosis, atherosclerosis, or vasospasm related to hemorrhage, blood supply to the affected area can be maintained through these collaterals. Collateral circulation is also present in rats. However, in rats, information on the presence of various types of aneurysms, their location and frequency in normal and experimental models of hypertension and stroke is still lacking. Cerebral arteries from humans and rats are characterized by the absence of external elastic lamina, as compared with systemic arteries. A type of multipolar cell resembling the interstitial cell of Cajal is present in the cerebral arteries of humans. Its function is unknown. Earlier reports of cerebral valves have been shown to represent intimal cushions near the branching points of the cerebral arteries. Intravascular bridges present in human cerebral arteries, have not been reported in rats. Finally, the presence of vascular remodeling, as found in the cerebral arterioles of hypertensive rats, remains to be established in the cerebral arterioles of human hypertensives.(ABSTRACT TRUNCATED AT 400 WORDS)

Drainage of the prelymphatics of the brain via the adventitia of the vertebral artery.

Carbon particles injected into the cortex of the cerebellum of the rat were found in the Virchow-Robin spaces of the adjacent capillaries, and in the adventitia of the cerebellar artery, basilar artery and vertebral artery--both inside and outside the skull. They were also found in some portions of the deeper cervical lymph nodes. However, while tracers injected into the cerebral hemispheres are drained via the tissue channels in the adventitia of the internal carotid arteries, tracers injected into the cerebellar hemispheres are drained via those of the vertebral arteries.

The cranial arachnoid and pia mater in man: anatomical and ultrastructural observations.

The objects of the present study were: (1) to define the relationships of the arachnoid mater to blood vessels in the subarachnoid space; (2) to establish the structure of leptomeningeal trabeculae and their relationships to the pia mater; and (3) to investigate the fine structure of the human pia mater. Intracranial portions of vertebral artery were taken at post mortem, and normal cerebral cortex and overlying leptomeninges were obtained from surgical lobectomies. Tissue from these specimens was examined by scanning and transmission electron microscopy, by light microscopy and by immunocytochemistry for the presence of basement membrane, desmosomal proteins and vimentin. Results of the study showed that as the vertebral artery pierced the posterior atlanto-occipital membrane and entered the subarachnoid space, it acquired a leptomeningeal coat as the arachnoid was reflected on to it. It has been demonstrated previously that as vessels enter the brain, the leptomeningeal coat is reflected on to the surface of the cortex as the pia mater. The arachnoid mater was seen to consist of a subdural mesothelial layer and a compact central layer as previously reported. From the inner layer of the arachnoid, collagen bundles coated by leptomeningeal cells extended as trabeculae across the subarachnoid space to fuse with the pia mater. The pia itself was composed of a delicate but apparently continuous layer of cells joined by desmosomes and gap junctions but no tight junctions were observed. It was possible to detect pia mater cells in the perivascular spaces of the brain by immunocytochemical techniques using light microscopy. The significance of the observed anatomical arrangement for cerebrospinal fluid physiology is discussed.

Altered cerebral vessel innervation in the spontaneously hypertensive rat.

Autonomic innervation in the cerebral arterial walls of adult male spontaneously hypertensive rats and of normotensive Wistar-Kyoto rats was studied. When examined by fluorescence microscopy, dense catecholamine fluorescence was observed in anterior cerebral and middle cerebral arteries of both Wistar-Kyoto and spontaneously hypertensive rats. However, vertebral and basilar arteries and small pial arteries of Wistar-Kyoto rats received extremely sparse or no catecholamine fluorescence, whereas, in the respective regions of spontaneously hypertensive rats, catecholamine fluorescence was found to be significantly elevated. The endogenous norepinephrine content was also higher in cerebral arteries of spontaneously hypertensive than of Wistar-Kyoto rats. When examined ultrastructurally (potassium permanganate fixation), the incidence of granular vesicle-containing nerves, indicative of sympathetic nerves, was found to be significantly elevated in all cerebral arteries of spontaneously hypertensive rats examined. In contrast, the agranular vesicle-containing nerve, indicative of nonsympathetic nerves, with close synaptic cleft distance (less than 2 micron) was found to decrease or remain unchanged in the cerebral arteries of spontaneously hypertensive rats. These results suggest that cerebral sympathetic vasoconstriction may become more prominent than nonsympathetic vasodilation in spontaneously hypertensive rats. This finding lends further credence to the previous in vivo findings that cerebral sympathetic vasoconstrictor nerves become more functional and exhibit a protective effect against brain lesions during hypertension. The potential roles of neurogenic components involved in cerebral blood flow autoregulation are also discussed.

Microscopy anatomy of the vertebral artery in the suboccipital and intracranial segments.

The authors studied the structure and the orientation of the connective-muscular component of the tunicae of the vertebral artery along the suboccipital and intracranial segments utilizing the following coloration methods: Weigert's resorcin fuchsin, Orcein solution and counterstain with Van Gieson's picrofuchsin. In the above mentioned segments, it was established that the wall of the vertebral artery exhibits a muscular structure. The tunica intima in both portions, has developed structure and the internal elastic lamina is evident; the tunica media is formed by fascicles of smooth muscle fibers disposed circularly in relation to the vascular lumen and interposed by thin elastic fibers. In the most external layer of the tunica media, these fibers form a external elastic lamina. The tunica adventitia is formed by a fibrous-elastic stratum which is reinforced by fascicles of circular collagenic fibers which mainly originates from the dura mater.