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At least 343 records · Page 19Linked to original sources
PubMed1996

[The ananlysis of relationship between fetal stress and blood dynamics in fetal vessels and placental bed vessels].

OBJECTIVE: To evaluate the value of color Doppler ultrasound examination in perinatal monitoring. METHOD: Doppler ultrasound results of 22 cases with fetal stress and 6 cases with perinatal mortality were retrospectively analyzed, and compared that of 555 normal pregnancies with same gestational age (36 to 40 weeks) using Ultramark 9 HDI color Doppler ultrasound. RESULTS: The resistance of fetal umbilical artery (FUA), fetal renal artery (FRA) and placental bed artery (PBA) in fetal stress group were significantly higher than that in normal pregnant group; there were no changes of resistance in middle cerebral artery (MCA). In perinatal mortality group, the resistance of FUA, FRA and PBA were the highest, the resistance of MCA was the lowest, and end-diastolic flow in FUA and FRA were absent or reverse. CONCLUSION: The results showed that fetal and placental flow dynamics study examined by color Doppler ultrasound is an effective method in the assessment of fetal well-being.

Adult↗
PubMed2005

An analytical study of 'Poisson conduction shape factors' for two thermally significant vessels in a finite, heated tissue.

To conveniently and properly account for the vessel to vessel and vessel to tissue heat transfer rates to predict in vivo tissue temperature distributions, this paper analyses two different types of Poisson conduction shape factors (PCSFs) for unheated and/or uniformly heated, non-insulated, finite tissue domains. One is related to the heat transfer rate from one vessel to another (vessel-vessel PCSF (VVPCSF)) and the other is related to the vessel to tissue heat transfer rates (vessel-tissue PCSF (VTPCSF)). Two alternative formulations for the VTPCSFs are studied; one is based on the difference between the vessel wall and tissue boundary temperatures, and the other on the difference between the vessel wall and the average tissue temperatures. The effects of a uniform source term and of the diameters and locations of the two vessels on the PCSFs are studied for two different cases: one, when the vessel wall temperatures are lower than the tissue boundary temperature, i.e., the vessels cool the tissue, and vice versa. Results show that, first, the VVPCSFs are only geometry dependent and they do not depend on the applied source term and the vessel wall and tissue boundary temperatures. Conversely, the VTPCSFs are strong functions of the source term and of the temperatures of the vessel walls and tissue boundary. These results suggest that to account for the vessel to vessel heat transfer rates, the VVPCSFs can be evaluated solely based on the vessel network geometry. However, to account for the vessel to tissue heat transfer rates, the VTPCSFs should be used iteratively while solving for the tissue temperature distributions. Second, unlike the tissue boundary temperature-based VTPCSFs which may become singular only in heated tissues, the average tissue temperature-based VTPCSFs have the potential to become singular in both unheated and heated tissues. These results suggest that caution should be exercised in the use of the VTPCSFs since they may approach singularity by virtue of their definition and thus may introduce large errors in the evaluation of tissue temperature distribution. Presented results are new and complementary to the previous shape factor results since these include the effect of (1) source term and (2) unequal vessel-tissue heat transfer rates from the two vessels to the tissue.

Animals↗
PubMed1992

Effect of completeness of revascularization on long-term outcome of patients with three-vessel disease undergoing coronary artery bypass surgery. A report from the Coronary Artery Surgery Study (CASS) Registry.

BACKGROUND: Complete revascularization after coronary artery bypass surgery is a logical goal and improves symptomatic outcome and survival. However, the impact of complete revascularization in patients with three-vessel coronary disease with varying severities of angina and left ventricular dysfunction has not been clearly defined. METHODS AND RESULTS: The study was performed as a retrospective analysis of 3,372 nonrandomized surgical patients from the Coronary Artery Surgery Study (CASS) Registry who had three-vessel coronary disease. Group 1 (894 patients) had class I or II angina (Canadian Cardiovascular Society criteria) and group 2 (2,478 patients) had class III or IV angina. In group 1, adjusted cumulative 4-year survivals according to the number of vessels bypassed were 85% (one vessel), 94% (two vessels), 96% (three vessels), and 96% (more than three vessels) (log rank, p = 0.022). Adjusted event-free survival (death, myocardial infarction, definite angina, or reoperation) was not influenced by the number of vessels bypassed, nor was the anginal status among patients remaining alive after 5 years. In group 2, adjusted cumulative 5-year survivals were 78% (one vessel), 85% (two vessels), 90% (three vessels), and 87% (more than three vessels) (log rank, p = 0.074). Adjusted event-free survivals after 6 years were 23% (one vessel), 23% (two vessels), 29% (three vessels), and 31% (more than three vessels) (p = 0.025); at 5 years, those with more complete revascularization were more likely to be asymptomatic or free of severe angina. Among group 2 patients with ejection fractions less than 0.35, 6-year survival was 69% for those with grafts to three or more vessels versus 45% for those with grafts to two vessels (p = 0.04). Placing grafts to three or more vessels was independently associated with improved survival and event-free survival in group 2 but not group 1 patients. The case-fatality rates among 529 patients experiencing a myocardial infarction during follow-up was significantly higher for patients with less complete revascularization. CONCLUSIONS: Complete revascularization (grafts to three or more vessels) in patients with three-vessel coronary disease appears to most benefit those with severe angina and left ventricular dysfunction.

Angina Pectoris↗
PubMed2002

Thoracoscopic discectomy and fusion in an animal model: safe and effective when segmental blood vessels are spared.

STUDY DESIGN: Disc-endplate excision and spine fusion were compared in animals randomly assigned to segmental vessel-spared and segmental vessel-ligated groups in an in vivo goat model of anterior spine discectomy and fusion using thoracoscopic techniques. OBJECTIVES: To compare safety and completeness of disc and endplate excision, and to perform a histologic and biomechanical comparison between fusion masses when the segmental vessels are spared and when they are ligated using thoracoscopic techniques. SUMMARY OFF BACKGROUND DATA: Because thoracoscopy is relatively new and technically demanding, many surgeons ligate the segmental blood vessels to enhance spine exposure and limit the risk of injury during discectomy and fusion. Although rare, spinal cord compromise secondary to segmental vessel ligation has been reported. METHODS: This study was divided into two phases. In Phase 1, 10 mature goats were randomly assigned to either the segmental vessel-ligated or the segmental vessel-spared group. Disc and endplate excision was performed at six consecutive thoracic levels in each animal (30 levels per group). The animals were killed, and the depth of disc excision was measured in the transverse and sagittal planes. The vertebral bodies then were separated through the disc space; photographic images of the endplates were digitized, and the area of endplate excision was calculated. In Phase 2, 12 mature goats were randomly assigned to the segmental vessel-ligated or vessel-spared group, and five noncontiguous thoracic segments were fused using autologous iliac crest graft. At 4 months the animals were killed, and the spines were harvested. At each disc level, the three-dimensional rotational and translational motions were analyzed and histomorphometric analysis was performed. RESULTS: Phase 1: Each animal survived the operative procedure, and no surgical complications occurred. No difference was found between vessel-ligated and vessel-spared groups in operative time (21.8 vs 22.7 minutes per disc), blood loss (97 vs 159 mL), or transverse (81% vs 74%) or sagittal (85% vs 85%) disc excision. The total area of endplate excision was 70% in the vessel-ligated group and 67% in the vessel-spared group (P > 0.1). Phase 2: Biomechanical testing demonstrated no difference in stiffness of the fused segments between the two groups in flexion-extension or axial rotation. However, greater flexibility in lateral bending was found in the specimens whose vessels were ligated (P < 0.05). The percentage of trabecular bone volume was similar between the two groups. CONCLUSIONS: The segmental vessels in the thoracic spine can be effectively spared without injury during disc excision and fusion. Although slightly more disc area was excised with ligation of the vessels, this was not statistically significant, and the fusion mass was similar between the two groups. Sparing the segmental vessels may provide blood supply that aids fusion mass, and the result may be greater spine stiffness in the coronal plane. Sparing the segmental vessels during thoracoscopic anterior disc excision and fusion can be safe. It should be considered in patients with a high risk for neurologic injury because of decreased spinal cord perfusion in revision surgery, severe kyphosis, congenital anomalies. Because the neurologic risk of vessel ligation has not been clearly established for idiopathic scoliosis, the surgeon will have to consider the risk-benefit ratio of adopting these methods when deciding not to ligate vessels in these patients.

Animals↗
PubMed1996

Prevalence, morphology, and topography of blood vessels in herniated disc tissue. A comparative immunocytochemical study.

STUDY DESIGN: Ninety disc herniations removed during surgery were studied by immunocytochemistry, using two different endothelial cell markers, to study the prevalence, morphology, and topography of blood vessels in disc herniations. OBJECTIVES: To increase the specific localization of even very small blood vessels present in disc herniations by using specific antibodies to endothelial cells; to study blood vessels comparatively with two different endothelial cell antibodies, comparing their prevalence; and to study blood vessel morphology and topographic relationships of blood vessels to other tissue elements, particularly disc cells. SUMMARY OF BACKGROUND DATA: In many previous macroscopic studies and in studies using conventional histologic methodology, blood vessels have been observed in degenerated and injured intervertebral discs. In a smaller patient sample, the authors previously observed blood vessels in approximately 80% of disc herniations by immunocytochemistry, the blood vessels co-localizing with macrophage cells. Many of these blood vessels are the product of very active neovascularization after disc tissue injury. The presence of such blood vessels has not, however, been studied in greater detail or in larger patient samples. Immunocytochemistry offers superior visualization and more specific localization and was thus used in the present study. METHODS: Thin frozen sections from 90 disc herniations were immunostained in parallel with von Willebrand factor and Ulex europaeus antibodies, both of which localize endothelial cells specifically. Indirect immunocytochemistry by avidin-biotin-peroxidase complex or alkaline phosphatase-antialkaline phosphatase were used for immunolocalization. Blood vessels were classified as being: +, abundant: (+), very few; or +, totally absent. RESULTS: The prevalence of blood vessels in disc herniations was found in 82 of 90 (91%) disc herniations with von Willebrand factor antibody and in 75 of 90 (83%) disc herniations with Ulex europaeus antibody. In 59 disc herniations (66%), blood vessels were observed with both antibodies in parallel, whereas they were observed with neither antibody in only six of 90 disc herniations. Furthermore, the ratio of abundant to very few blood vessels was 73:9 with von Willebrand factor antibody and 63:12 with Ulex europaeus antibody, further supporting the abundance of blood vessels in disc herniations. Blood vessels were most prevalent in sequestrated discs, but they were also observed in six of eight protrusions. Dense blood vessel networks were observed to penetrate the disc tissue, and blood vessels were also present in areas of inflammatory cell infiltration. Topographically, blood vessels were, on several occasions and with both antibodies, seen to pass close by or to surround disc cells. CONCLUSIONS: By immunocytochemistry with endothelial cell markers, blood vessels can be observed to be numerous, and their prevalence in herniated discs is very high, presumably as a result of a very intense neovascularization process after the disc injury. A close apposition to disc cells may suggest attempts to increase the nutrition of these cells and will influence the metabolism of the cells.

Adolescent↗
PubMed1996

Contributions of donor and host blood vessels in CNS allografts.

The contributions of blood vessels in various transplantation paradigms of solid CNS tissue or cell suspension allografts placed into adult host brains were investigated immunohistochemically using the PVG-RT1C and PVG-RT1U inbred rat strains and a panel of highly specific monoclonal antibodies. The monoclonal antibodies included OX-27 and U9F4 against major histocompatibility complex (MHC) class I antigens of the PVG-RT1C and PVG-RT1U rats, respectively; OX-26 against the rat transferrin receptor located on blood-brain barrier (BBB) endothelia; and OX-7 against rat neuronal Thy 1.1 for evaluating graft survival. Our study is the first to address the immunogenicity of blood vessels in surviving CNS allografts. Solid fetal or neonatal PVG-RT1C cortex was grafted into the third or lateral cerebral ventricle or caudate/putamen of PVG-RT1U adult hosts for 30 days to 7 months. All allografts expressed demonstrable Thy 1.1 immunoreactivity with OX-7 antibody and appeared well-vascularized with blood vessels that immunostained with the OX-26 antibody against the transferrin receptor. For the most part, the allografts were supplied sparsely with donor (PVG-RT1C) MHC class I-positive (OX-27) blood vessels clustered in pockets. Donor MHC class I-positive vessels entered the host brain only from allografts in the third ventricle; these vessels were restricted to the host median eminence and no longer immunostained with OX-26 for the transferrin receptor (normally the median eminence is supplied with non-BBB vessels that do not possess the transferrin receptor and do not stain with OX-26). In host brains harboring a third ventricle allograft, host MHC class I-positive vessels immunostained with the U9F4 antibody were evident throughout the host CNS, including the median eminence, and throughout the allografts excluding sites inhabited by donor PVG-RT1C vessels. Cell suspension neural allografts (donor PVG-RT1C) placed within the brain parenchyma of PVG-RT1U hosts revealed no significant differences in vascular contributions between donor and host when compared to results obtained from solid CNS allografts. A unique immunohistochemical approach of introducing ascites fluid OX-27 as the primary antibody intravenously to the PVG-RT1U host demonstrated that in donor PVG-RT1C posterior pituitary allografts, donor and not host vessels predominate and are restricted to the graft. Finally, blood vessels isolated from adult PVG-RT1C brains were mixed with solid fetal PVG-RT1U cortical tissue and grafted into the brain parenchyma of adult PVG-RT1U hosts. Immunostaining with OX-27 antibody against MHC class I of the PVG-RT1C rat strain disclosed that the PVG-RT1C blood vessels survived and were confined to the PVG-RT1U syngeneic graft. The results suggest that blood vessels supplying CNS allografts placed within the host brain are predominantly of host origin; surviving donor vessels are restricted to the allograft with rare exceptions, which may be dictated by the type of neural allograft and the host CNS site receiving the allograft. The survival of isolated allogeneic CNS blood vessels grafted into the host brain suggests that such blood vessels can present an endothelial genotype and phenotype different from those of host vessels indigenous to the CNS site receiving the allogeneic vessel graft. This finding may have implications in the circumvention of the blood-brain fluid barriers for the CNS delivery of blood-borne therapeutics.

Age Factors↗
PubMed2006

Lymphangiogenesis by blind-ended vessel sprouting is concurrent with hemangiogenesis by vascular splitting.

Development of effective vascular therapies requires the understanding of all modes of vessel formation involved in angiogenesis (here termed "hemangiogenesis") and lymphangiogenesis. Two major modes of vessel morphogenesis include sprouting of a new vessel from a preexisting vessel and splitting of a preexisting parent vessel into two offspring vessels. In the quail chorioallantoic membrane (CAM) during mid-development (embryonic days E6-E9), lymphangiogenesis progressed primarily via blind-ended vessel sprouting. Isolated lymphatic endothelial progenitor cells were recruited to the tips of growing vessels. During concurrent hemangiogenesis, parent blood vessels expanded from the capillary network and split into offspring vessels, accompanied by transient capillary expression of alpha smooth muscle actin (alphaSMA) and recruitment of polarized mural progenitor cells. Lymphatics and blood vessels were identified by confocal/fluorescence microscopy of vascular endothelial growth factor (VEGF) receptor VEGFR-2, alphaSMA (specific to CAM blood vessels), homeobox transcription factor Prox1 (specific to lymphatics), and the quail hematopoetic marker, QH-1. VEGFR-2 was expressed intensely in isolated cells and lymphatics, and moderately in blood vessels. Prox1 was absent from isolated progenitor cells prior to lymphatic recruitment. Exogenous vascular endothelial growth factor-165 (VEGF165) increased blood vessel density and anastomotic frequency without changing endogenous modes of vascular/lymphatic vessel formation or marker expression. Although VEGF165 is a key cellular regulator of hemangiogenesis and vasculogenesis, the role of VEGF165 in lymphangiogenesis is less clear. Interestingly, VEGF165 increased lymphatic vessel diameter and density as measured by novel Euclidean distance mapping, and the antimaturational dissociation of lymphatics from blood vessels, accompanied by lymphatic reassociation into homogeneous networks.

Animals↗