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At least 505 records · Page 28Linked to original sources

PubMed1994

Pulse-generated run-off versus dependent Doppler ultrasonography for assessment of calf vessel patency.

Pulse-generated run-off (PGR) is an established technique in the assessment of calf vessel patency. Dependent Doppler ultrasonography is proposed as a fast and simple alternative. Twenty-six limbs with severe ischaemia were evaluated by PGR, dependent Doppler examination and intra-arterial digital subtraction angiography (DSA). PGR was performed and scored as previously described. Dependent Doppler ultrasonography was performed after 5 min of foot dependency and scored as for PGR. Angiograms were scored by an independent radiologist, who awarded 2 for a vessel widely patent to the ankle, 1 for a diseased vessel crossing the ankle and 0 if no vessel was visualized. Of 78 calf vessels evaluated, 59 (76 per cent) appeared patent on PGR and dependent Doppler examination but only 33 (42 per cent) appeared patent to the ankle with intra-arterial DSA. There was very good agreement between PGR and dependent Doppler for detection of patent calf vessels (kappa = 0.93). Doppler signals were biphasic in six calf vessels on dependency and in 22 vessels with PGR. PGR and dependent Doppler ultrasonography detected 26 vessels communicating with the pedal arch compared with seven detected angiographically. There was good agreement between PGR and dependent Doppler examination for diagnosis of the most suitable vessel for distal anastomosis (kappa = 0.80). The wide availability and simplicity of dependent Doppler ultrasonography mean that no patient with a critically ischaemic limb should be denied reconstructive surgery on the basis of angiographic findings alone.

Angiography, Digital Subtraction↗

PubMed2003

Pressurized wet digestion in open vessels.

The High Pressure Asher (HPA-S) was adapted with a Teflon liner for pressurized wet digestion in open vessels. The autoclave was partly filled with water containing 5% (vol/vol) hydrogen peroxide. The digestion vessels dipped partly into the water or were arranged on top of the water by means of a special rack made of titanium or PTFE-coated stainless steel. The HPA-S was closed and pressurized with nitrogen up to 100 bars. The maximum digestion temperature was 250 degrees C for PFA vessels and 270 degrees C for quartz vessels. Digestion vessels made of quartz or PFA-Teflon with volumes between 1.5 mL (auto sampler cups) and 50 mL were tested. The maximum sample amount for quartz vessels was 0.5-1.5 g and for PFA vessels 0.2-0.5 g, depending on the material. Higher sample intake may lead to fast reactions with losses of digestion solution. The samples were digested with 5 mL HNO(3) or with 2 mL HNO(3)+6 mL H(2)O+2 mL H(2)O(2). The total digestion time was 90-120 min and 30 min for cooling down to room temperature. Auto sampler cups made of PFA were used as digestion vessels for GFAAS. Sample material (50 mg) was digested with 0.2 mL HNO(3)+0.5 mL H(2)O+0.2 mL H(2)O(2). The analytical data of nine certified reference materials are also within the confidential intervals for volatile elements like mercury, selenium and arsenic. No cross contamination between the digestion vessels could be observed. Due to the high gas pressure, the diffusion rate of volatile species is low and losses of elements by volatilisation could be observed only with diluted nitric acid and vessels with large cross section. In addition, cocoa, walnuts, nicotinic acid, pumpkin seeds, lubrication oil, straw, polyethylene and coal were digested and the TOC values measured. The residual carbon content came to 0.2-10% depending on the sample matrix and amount.

Journal Article↗

PubMed2001

Changes in gastrointestinal lymph and blood vessels in patients with cirrhotic portal hypertension.

BACKGROUND: The aim of this study was to characterize the lymph vessels in different parts of the gastrointestinal tract and also to evaluate morphometric changes in these vessels during cirrhotic portal hypertension. METHODS: Sixteen patients with cirrhotic portal hypertension and 18 control subjects without portal hypertension were enrolled in the study. Tissue specimens were collected at autopsy or surgery, and were stained enzyme histochemically, using 5'-nucleotidase and alkaline phosphatase to distinguish lymph vessels and blood vessels, respectively. The numbers of vessels and their luminal areas were estimated using computer graphics software (National Institutes of Health [NIH] image program). RESULTS: The numbers and luminal areas of the lymph vessels varied considerably among the different organs of the gastrointestinal tract, both in controls and in the patients with cirrhotic portal hypertension. There was no significant difference in the numbers of lymph vessels between controls and patients with cirrhotic portal hypertension. However, the luminal area of the lymph vessels in the esophagus and stomach was significantly greater in the patients with cirrhotic portal hypertension than in the controls. These differences in lymph vessels were not seen in the small intestine and colon. CONCLUSIONS: These data indicate that dilatation of lymph vessels may be related to the absorption of excess interstitial fluid, resulting from congestion, in cirrhotic portal hypertension.

5'-Nucleotidase↗

PubMed1998

Flow resistance and drag forces due to multiple adherent leukocytes in postcapillary vessels.

Computational fluid dynamics was used to model flow past multiple adherent leukocytes in postcapillary size vessels. A finite-element package was used to solve the Navier-Stokes equations for low Reynolds number flow of a Newtonian fluid past spheres adhering to the wall of a cylindrical vessel. We determined the effects of sphere number, relative geometry, and spacing on the flow resistance in the vessel and the fluid flow drag force acting to sweep the sphere off the vessel wall. The computations show that when adherent leukocytes are aligned on the same side of the vessel, the drag force on each of the interacting leukocytes is less than the drag force on an isolated adherent leukocyte and can decrease by up to 50%. The magnitude of the reduction depends on the ratio of leukocyte to blood vessel diameter and distance between adherent leukocytes. However, there is an increase in the drag force when leukocytes adhere to opposite sides of the vessel wall. The increase in resistance generated by adherent leukocytes in vessels of various sizes is calculated from the computational results. The resistance increases with decreasing vessel size and is most pronounced when leukocytes adhere to opposite sides of the vessel.

Biophysics↗

PubMed1995

Infrared video imaging of subsurface vessels: a feasibility study for the endoscopic management of gastrointestinal bleeding.

The feasibility of infrared video imaging of subsurface vessels in the stomach was investigated both experimentally and in more detail using computer simulations of light propagation. Infrared video imaging was first attempted in several experimental situations. Images of a human arm illuminated with infrared light (wavelength > 700 nm) revealed subcutaneous venous structures not revealed by visible light (wavelength of 500 to 600 nm). An infrared-sensitive video endoscope was used to view both a human arm and normal stomach wall. Infrared illumination within the stomach enhanced only the larger subsurface vessels. Infrared transillumination of a rat skin flap window chamber allowed video recording of images during injection of an absorbing dye, indocyanine green, into the blood volume and showed that indocyanine green can enhance the contrast in infrared images of small vessels. Computer simulations of vessels of varying depths and sizes indicated successful detection was possible by infrared imaging. Computer simulations demonstrated that the shadow caused by an imaged subsurface vessel has two characteristics: (1) the central loss of reflectance, which indicates the size of the vessel, and (2) the full-width half-maximum of the reflectance loss, which indicates the depth of the vessel. The simulations further suggested that images of small vessels can be dramatically enhanced (68-fold) by indocyanine green, which attenuates the transmittance of scattered light from behind the vessels to the surface for observation. On the other hand, indocyanine green enhances the contrast of large vessels to a lesser degree (2.6-fold). The ultimate goal is to develop an endoscopic video imaging system capable of capturing reflected light from the stomach wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Recovery of testicular blood flow following ligation of testicular vessels.

To determine whether initial ligation of the testicular vessels of the high undescended testis followed by a delayed secondary orchiopexy is a viable alternative to the classical Fowler-Stephens procedure, a series of preliminary experiments were conducted in the rat in which testicular blood flow was measured by the 133xenon washout technique before, and 1 hour and 30 days after ligation of the vessels. In addition, testicular histology, and testis and sex-accessory tissue weights were measured in 6 control, 6 sham operated and 6 testicular vessel ligated rats 54 days after vessel ligation. The data demonstrate that ligation and division of the testicular blood vessels produce an 80 per cent decrease in testicular blood flow 1 hour after ligation of the vessels. However, 30 days later testis blood flow returns to the control and pre-treatment value. There were no significant changes in testis or sex-accessory tissue weights 54 days after vessel ligation. Histologically, 4 of the surgically operated testes demonstrated necrosis of less than 25 per cent of the seminiferous tubules while 1 testis demonstrated more than 75 per cent necrosis. The rest of the tubules in all 6 testes demonstrated normal spermatogenesis. From this study we conclude that initial testicular vessel ligation produces an immediate decrease in testicular blood flow but with time the collateral vessels are able to compensate and return the testis blood flow to its normal pre-treatment value. These preliminary observations lend support for the concept that initial ligation of the testicular vessels followed by a delayed secondary orchiopexy in patients with a high undescended testis may be a possible alternative to the classical Fowler-Stephens approach.

Animals↗

PubMed2001

Validity of transabdominal sonography in the detection of a two-vessel umbilical cord.

OBJECTIVE: To determine the validity of transabdominal ultrasound in the detection of a two-vessel and a three-vessel umbilical cord. METHODS: The ultrasound and pathology databases were collated between January 1, 1999, and December 31, 2000. Only those cases with ultrasound and pathology information concerning the number of vessels in the umbilical cord were included for analysis (group 1). In addition, 27 cases with a two-vessel umbilical cord were included from the ultrasound database before January 1, 1999, for which pathologic information was also obtained (group 2). RESULTS: A total of 1295 ultrasound/pathology reports were entered from January 1, 1999, through December 31, 2000; 268 cases did not have complete information, leaving 1027 for analysis (group 1). The visualization rate of the number of vessels in the umbilical cord increased from 15 to 17 weeks' gestation (74.1-97.6%; P <.001). The visualization rate remained stable from 17.0 to 35.9 weeks' gestation, and then declined to 83.3% (P <.01). The sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of a two-vessel umbilical cord were 85%, 99.7%, 85%, and 99.7%, respectively. CONCLUSION: The detection rate of either a two-vessel or three-vessel umbilical cord is best achieved between 17 and 36 weeks' gestation. In the majority of two-vessel umbilical cords that were called three-vessel, an appropriate transverse image of the umbilical cord was not obtained.

Adult↗

PubMed1998

Inhibition of chronic vessel wall intimal hyperplasia following acute anticoagulant treatment: relative effects of heparin and dermatan sulphate.

Surface-bound thrombin which contributes to vessel wall hyperplasia, is resistant to inhibition by heparin/antithrombin III (/ATIII) but not to inhibition by dermatan sulphate/heparin cofactor II (/HCII). To determine the effects of heparin and dermatan sulphate on vessel wall hyperplasia after a first or second injury, rabbit carotid arteries first were injured, using a standard procedure (first injury). Half of the first-injury rabbits were given heparin, dermatan sulphate, or saline, 5 minutes before and at 30-minute intervals over 2 hours post-injury, and then allowed to recover. Four weeks later, the first-injury treated animals were killed and their injured carotid arteries were processed histologically. The remaining untreated first-injury rabbits were also allowed to recover. At 4 weeks, those rabbits were re-anesthetized and their first-injury arteries (which were occluded >75%), were isolated, and vessel wall lumen patency was re-established by endarterectomy (second injury). During this second injury, the animals were treated with heparin, dermatan sulphate, or saline as described above. Four weeks after this second injury, these rabbits were killed and their second injury arteries were processed histologically. Intimal hyperplasia determined histologically, was expressed as an x-fold increase in vessel wall cross-sectional area (i.e., [(media+intima area) media area]). Vessel wall lumen occlusion was expressed as [1-(lumen area/internal elastic lamina area) x 100; % occlusion]. Vessel wall area in the saline-treated animals, increased 2.6+/-1.2 and 2.4+/-1.0 fold respectively, means+/-SD, n = 12, within 4 weeks of the first and second injuries. These increases were due to intimal hyperplasia and associated with 75+/-19% and 79+/-21% occlusion of the vessel wall lumen, respectively. Heparin had little effect, whereas dermatan sulphate (1) decreased hyperplasia by 45% after the first injury and by 47% after the second injury, p<0.008 and <0.03, respectively, and (2) decreased vessel wall occlusion 47+/-12% and 33+/-5% after the first and second injury, respectively. We conclude that (1) dermatan sulphate/HCII may be a useful inhibitor of vessel wall hyperplasia following vessel wall injury, and (2) this effect can be achieved by an acute anticoagulant treatment at the time of injury, unlike heparin/ATIII.

Animals↗

PubMed1996

New blood vessels can be induced to invade ischemic skeletal muscle.

PURPOSE: Despite intense investigation of angiogenesis, little effort has been made to exploit this phenomenon in ischemic tissue. The few studies on this topic have focused primarily on the development of collateral arteries in existing arterial beds. A previous study showed that a perfused muscle flap transposed to an ischemic limb formed vascular connections, which were demonstrated with angiography, between the arteries of the flap and the limb vasculature. Microsphere studies suggested that these vascular connections increased the resting perfusion of the ischemic limb. This study is designed to confirm histologically that such connections develop and to quantitate the number and dimensions of these new vessels. METHODS: Through a midline laparotomy, the right common iliac artery was ligated and divided in 18 male New Zealand white rabbits. An abdominal-wall muscle flap based on the left inferior epigastric artery was transposed to the right thigh. On the seventh day, contrast dye was injected into the flap artery of eight rabbits and an arteriogram was obtained. The tissue of the remaining rabbits was perfusion-fixed at 3 days (n = 2), 7 days (n = 4), and 14 days (n = 4). Thin sections of the flap-thigh muscle interface were stained with hematoxylin and eosin and for alpha-actin and proliferating cell nuclear antigen and were examined microscopically. RESULTS: An arteriogram confirmed vascular connections between the flap and the native limb circulation in seven of the eight rabbits. Histologic evaluation of the flap-thigh muscle interface showed no new vessels on the third day. On the seventh day, 6.8 +/- 4.8 new vessels (positive alpha-actin staining, red blood cells in lumen) were seen per 40 x field; the vessels averaged 10.2 +/- 5.2 microns in diameter. On the fourteenth day, there were 7.3 +/- 3.8 vessels per 40 x field (p = 0.46), but the vessel diameter increased to 20.7 +/- 10.6 microns (p = 0.013). Proliferating cell nuclear antigen staining confirmed that these were proliferating vessels. CONCLUSION: Within seven days, new vessels that were more mature than capillaries (stained for alpha-actin, a smooth muscle cell protein) formed between the flap and the thigh muscle. These new connecting vessels continue to enlarge in diameter between 7 and 14 days, but the stimulus to form new vessels appeared to decline or disappear before the fourteenth day. Attempts to sustain this phenomenon with angiogenic factors are underway.

Angiography↗

PubMed1999

High density of small vessels expressing the tyrosine kinase receptor KDR in primary invasive breast carcinoma correlates with axillary lymph node metastases.

Although it is generally accepted that tumour growth is angiogenesis dependent, little is known about the role of angiogenesis in the metastatic process. Recent evidence suggests that the angiogenic tyrosine kinase receptor KDR is pivotal in new vessel formation. To investigate, therefore, the association between new vessel formation in primary breast carcinoma and axillary lymph node metastasis we have used computer assisted video analysis to assess the vascular distribution as well as the level of expression of KDR in individual vessels in sections of invasive breast carcinomas, some of which had metastasized to the axillary lymph nodes and some that had not. We specifically assessed the frequency distribution, perimeter, area, and density of KDR positive vessels in the same sections of tumours. Our results show that in invasive mammary carcinoma KDR is expressed exclusively on the surface and cytoplasm of endothelial cells of approximately 71% of vessels, but the level of expression in individual vessels does not correlate with the presence of axillary lymph node metastases (P > 0.10). However, we found that small vessels express higher levels of KDR (P < 0.02) than larger vessels and that there is a significantly higher frequency of relatively small (< 90 microm in perimeter) KDR positive vessels in breast tumours that had metastasized to the axillary lymph nodes than those that had not (P < 0.001). In conclusion, increased density and frequency of KDR positive small vessels in primary invasive breast carcinoma correlates with axillary lymph node metastases.

Journal Article↗

PubMed1995

Echocardiographic size of conductance vessels in athletes and sedentary people.

The purpose of the present study was to assess the size of great and medium caliber arterial and venous vessels (conductance vessels) in athletes of different sports and sedentary people. Vessel size was measured by two-dimensional echocardiography in 15 professional cyclists, 15 highly-trained long-distance runners, 15 professional volley-ball players, 10 wheelchair basketball players, 11 wheelchair distance runners and 20 sedentary controls. The following vessels were imaged and measured: aortic arch, left carotid and left subclavian artery, right pulmonary artery, abdominal aorta and mesenteric artery, superior and inferior vena cava. Vessel size was considered in absolute value and normalized for body surface area (BSA). Among the able-bodied athletes, both cyclists and long-distance runners showed a generalized increase in vessels size in respect to controls, either absolute or normalized for BSA. The increase was highly significant for normalized inferior vena cava: cyclists, mean 15.1 mm, 95% confidence intervals 14.2 to 15.8 mm; long-distance runners, 15.8 mm, 15.3 to 16.4; controls, 10.5 mm, 9.8 to 11.3. Volleyball players also showed larger vessels than controls, but this feature was clearly related to their greater body size because statistical differences were attenuated or abolished by normalization for BSA. Wheelchair athletes exhibited significantly larger upper-body vessels but significantly smaller lower-body vessels than controls when normalized for BSA. In addition, wheelchair distance runners, who trained more intensively, had larger abdominal aorta and inferior vena cava than wheelchair basket players. Long-term endurance training leads to a generalized increase in arterial and venous conductance vessels size.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1999

An investigation of the flow dependence of temperature gradients near large vessels during steady state and transient tissue heating.

Temperature distributions measured during thermal therapy are a major prognostic factor of the efficacy and success of the procedure. Thermal models are used to predict the temperature elevation of tissues during heating. Theoretical work has shown that blood flow through large blood vessels plays an important role in determining temperature profiles of heated tissues. In this paper, an experimental investigation of the effects of large vessels on the temperature distribution of heated tissue is performed. The blood flow dependence of steady state and transient temperature profiles created by a cylindrical conductive heat source and an ultrasound transducer were examined using a fixed porcine kidney as a flow model. In the transient experiments, a 20 s pulse of hot water, 30 degrees C above ambient, heated the tissues. Temperatures were measured at selected locations in steps of 0.1 mm. It was observed that vessels could either heat or cool tissues depending on the orientation of the vascular geometry with respect to the heat source and that these effects are a function of flow rate through the vessels. Temperature gradients of 6 degrees C mm(-1) close to large vessels were routinely measured. Furthermore, it was observed that the temperature gradients caused by large vessels depended on whether the heating source was highly localized (i.e. a hot needle) or more distributed (i.e. external ultrasound). The gradients measured near large vessels during localized heating were between two and three times greater than the gradients measured during ultrasound heating at the same location, for comparable flows. Moreover, these gradients were more sensitive to flow variations for the localized needle heating. X-ray computed tomography data of the kidney vasculature were in good spatial agreement with the locations of all of the temperature variations measured. The three dimensional vessel path observed could account for the complex features of the temperature profiles. The flow dependences of the transient temperature profiles near large vessels during the pulsed experiments were consistent with the temperature distributions measured in the steady state experiments and provided unique insights into the process of convective heat transfer in tissues. Finally, it was shown that even for very short treatment times (3-20 s), large vessels had significant effects on the tissue temperature distributions.

Angiography↗

PubMed2003

A comparison of laparoscopic bipolar vessel sealing devices in the hemostasis of small-, medium-, and large-sized arteries.

INTRODUCTION: The development of new energy sources for hemostasis has facilitated advanced laparoscopic procedures. Few studies, however, have documented the strength of the vessels sealed or the extent of surrounding lateral thermal injury, two important factors in maintaining hemostasis while preventing injury to surrounding structures. This study compared the burst pressure and extent of thermal injury of vessels sealed with the 5-mm laparoscopic PlasmaKinetics trade mark sealer (PK) (Gyrus Medical, Maple Grove, Minnesota) and the 5-mm laparoscopic LigaSure trade mark sealing device (LS) (Valleylab, Boulder, Colorado). METHODS: Arteries in three sizes (2-3 mm, 4-5 mm, and 6-7 mm) were harvested from domestic pigs. Eight to 17 specimens from each size were randomly sealed with the PK, and the same number with the LS. Burst pressures were measured in mm Hg. The extent of thermal injury, determined by coagulation necrosis, was measured microscopically in millimeters after staining the transected vessels with hematoxylin and eosin. Descriptive statistics, including means and standard deviations, are reported. Student's t-test and ANOVA were performed to determine significance (P <.05). RESULTS: The mean bursting pressures of the PK and the LS were equal in the 2-3 mm vessels (397 vs. 326 mm Hg, P =.49). The PK bursting pressures were significantly less than the LS in the 4-5 mm (389 vs. 573 mm Hg, P =.02) and the 6-7 mm groups (317 vs. 585 mm Hg, P =.0004). As vessel size increased, the PK was associated with significantly lower burst pressures, while the LS was associated with progressively higher burst pressures (P =.035). Thermal spread was not significantly different between the PK and the LS in the 2-3 mm (1.5 vs. 1.2 mm, P =.27), the 4-5 mm (2.4 vs. 2.4 mm, P =.79), or the 6-7 mm vessel size groups (3.2 vs. 2.5 mm, P =.32). Increasing vessel size, regardless of instrument used, was associated with increased thermal injury (P <.0001). CONCLUSION: The LS produces supraphysiologic seals with significantly higher bursting pressures than the PK in vessels ranging from 4 to 7 mm. The PK seals become progressively weaker while the LS seals increase in strength as the vessel size increases. Although thermal spread increases with vessel size, the degree of lateral thermal injury is no different between the two instruments.

Animals↗

PubMed1996

Laparoscopic division of crossing vessels at the ureteropelvic junction.

Endopyelotomy has become an accepted mode of treatment for primary and secondary ureteropelvic junction (UPJ) obstruction, but a 15% to 30% failure rate persists. The presence of crossing vessels at the UPJ has been implicated as a common cause of complications, failures, and recurrences. In the past, renal angiography was necessary to identify crossing vessels. We have utilized endoluminal ultrasonography to identify crossing vessels at the UPJ and to guide endoscopic incisional techniques. Previously, whenever crossing vessels were identified that could not be safely avoided during endopyelotomy, we had recommended dismembered pyeloplasty, an open surgical procedure with a long recovery time. We report our experience with laparoscopic division of crossing vessels in two patients, one with a symptomatic horseshoe kidney. Each patient had a large crossing vessel identified by endoluminal ultrasonography; consequently, endopyelotomy was abandoned. The location and distribution of the vessels were then delineated by angiography. The aberrant vessels were dissected free and divided laparoscopically. The patients returned to work within 1 week. Follow-up diuretic renal scans showed complete resolution of obstruction (T1/2 < 10 minutes) in one patient; no change was noted in the patient with a horseshoe kidney. Both patients have remained free of symptoms and normotensive for more than 12 months. Laparoscopic division of crossing vessels may play a role in the treatment of patients with extrinsic ureteral obstruction from aberrant vessels.

Adult↗

PubMed1996

Laparoscopic transillumination for the location of anterior abdominal wall blood vessels.

OBJECTIVE: To determine the efficacy of transillumination for locating abdominal wall vessels prior to trocar placement during laparoscopy. DESIGN: Prospective clinical descriptive study. SETTING: Normal human volunteers in an academic research environment. PATIENTS: Forty-seven white and 21 black women of various weights undergoing laparoscopy for clinical indications unrelated to this study. INTERVENTIONS: None. MAIN OUTCOME MEASURES: The location and number of abdominal wall vessels visible by transillumination were recorded for each patient. RESULTS: In women of normal weight, a single vessel could be seen approximately 5 cm from the midline in > 90% of the patients, and second vessel approximately 8 cm from the midline could also be seen in 51%. The more medial vessels did not correlate with the course of the inferior epigastric vessels seen laparoscopically. The ability to see vessels was decreased significantly by the patients' weight but not by skin color. CONCLUSIONS: Superficial abdominal wall vessels may be located by transillumination in the majority of women of normal weight regardless of skin color, but is of less value in overweight and obese women. However, the deep (inferior) epigastric vessels cannot be effectively located by transillumination, and thus other techniques should be used to minimize the risk of injury to these vessels.

Abdominal Muscles↗

PubMed1990

Xylem dysfunction in Quercus: vessel sizes, tyloses, cavitation and seasonal changes in embolism.

The seasonal progression of xylem dysfunction from tyloses and embolism induced both by cavitation and frost was studied in Quercus rubra L. and Quercus alba L. branches. Vessel lengths and diameters were measured in current-year rings of branches of various ages. Vessels in current-year shoots are about the same size as those in many diffuse porous trees, but vessels in older branches are two to six times larger in diameter and typically more than 10 times longer. Large Quercus vessels were more vulnerable to cavitation than small vessels. The small vessels in current-year shoots were more vulnerable to cavitation than vessels of comparable size in diffuse porous species. Earlywood vessels are completely blocked by tyloses within a year of their formation. Tylose growth starts in winter, but the vessels are not fully blocked until the next summer. Many latewood vessels, by contrast, remain free of complete blockage for several years. In Q. rubra, loss of hydraulic conductivity in current-year shoots due to cavitation reaches 20% by August and > 90% after the first hard frost. Both laboratory and field observations confirm that the role of frost in causing loss of hydraulic conduction by embolism is much more dramatic in Quercus than in conifers and diffuse porous hardwoods.

Journal Article↗

PubMed1997

Use of cortical surface vessel registration for image-guided neurosurgery.

OBJECTIVE: We have treated patients with brain surface tumors by using video registration of a three-dimensional image to the surgical field, to identify eloquent cortices, localize the lesions, and define the tumor margins. "Skin-to-skin" registration using the skin surface to produce alignment was performed earlier but was difficult in areas with few prominent registration landmarks. For this reason, "vessel-to-vessel" registration using the cortical vessels as fiducials was applied to 17 cases, to improve accuracy. This article presents the advantages and limitations of vessel-to-vessel registration, as determined from the data for these cases. The accuracy is also estimated. METHODS: A three-dimensional model was reconstructed from magnetic resonance imaging data, and a two-dimensional projection was superimposed on the video image of the actual surgical field. The tumor was resected with guidance from the registered video image. The two-dimensional projection accuracy of vessel-to-vessel registration was compared with that of skin-to-skin registration by using a phantom study. RESULTS: All 17 tumors underwent gross total resection, and the patients experienced no major permanent neurological deficits. In the phantom study, the two-dimensional, projected, target registration error of a tumor with skin-to-skin registration was estimated as 8.9 +/- 5.3 mm and that with vessel-to-vessel registration was 1.3 +/- 1.4 mm (99th percentile confidence intervals, 24.8 and 5.5 mm, respectively). CONCLUSION: Video registration using cortical surface vessels is practical and improves two-dimensional projection accuracy significantly, compared with skin registration.

Adolescent↗

PubMed1998

Superior gluteal vessel as recipient for free flap reconstruction of lumbosacral defect.

When the lumbosacral soft-tissue defect cannot be closed with a local flap, the option of a free flap should be considered. However, very few cases of free flaps have been reported, the reason being mainly difficulties in finding a suitable recipient vessel. Several vessels, such as inferior gluteal vessel, extension of thoracodorsal vessel with vein graft were reported as recipient vessels, but each one had its own drawbacks. The superior gluteal vessel has been used as a donor vessel in breast reconstruction after mastectomy but is thought to be undesirable as a recipient for microvascular anastomosis, mainly because of technical difficulty. From May of 1993 to March of 1997, five patients (one man and four women) received microvascular transfer of latissimus dorsi myocutaneous flaps using the superior gluteal vessel as a recipient. Their ages ranged from 11 to 64 years (mean 44 years of age). The causes of lumbosacral defects were tumor (1), trauma (1), radiation (2), and pressure sore (1). Before free flap transfer, the patients received an average of 2.8 operations for sacral lesions. Mean follow-up period was 12.4 months (2 to 40 months). A lateral approach was used to the superior gluteal vessel after elevation and retraction of gluteus maximus muscle. A thoracodorsal artery and vein were anastomosed to superior gluteal artery and vein in three cases, whereas in two cases, one artery and two veins could be anastomosed. All the flaps survived with complete recovery from sacral lesions. During the follow-up period, one case of partial skin graft necrosis and one case of a small superficial pressure sore developed, but there was neither dehiscence nor recurrence. The superior gluteal vessel is large in caliber, constant, with numerous branches, lying in proximity to the lesion, and relatively unaffected despite previous radiation. The technical difficulties with the deep location and short pedicle length can be overcome with some modifications in approach to the vascular pedicle. The superior gluteal artery and vein can be used as a recipient for the free tissue transfer when the lumbosacral defects cannot be covered with a conventional method.

Adolescent↗