Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “VESSELS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMedDate not supplied

Trace metal content of cerebral vessels in American Blacks, Caucasians and Nigerian Africans.

Trace metal contents of cerebral vessels in age-matched and sex-matched subjects from three population groups were estimated. The trace metals included calcium, manganese, zinc, magnesium, copper and iron. The American blacks in Washington, D.C., who are ethnologically related to Nigerian Africans, have different patterns of trace metal contents in their cerebral vessels and the observed levels also differed in some respects from Minnesota Caucasians living in a similar environment. The greatest amounts of calcium, zinc, and copper were found in the vessels of American blacks while the greatest amount of magnesium was found in vessels of Minnesota Caucasians. There was no statistically significant difference in the manganese content of the cerebral vessels in three population groups. Nigerian Africans had the least amounts of copper and magnesium but had the highest iron content. A similar high level of iron was observed in the vessels of American blacks. Since it has been shown that American blacks have the most extensive and severe degree of atherosclerosis among the three population groups, it would appear that iron, calcium and manganese in the cerebral vessels may not directly relate to the severity of cerebral atherosclerosis. Relatively high levels of copper and magnesium, which were observed in the cerebral vessels of American blacks and Caucasians, may be of significance in the pathogenesis of cerebral atherosclerosis. The low levels of the trace metals in Nigerians may be protective. The possible role of zinc requires further studies.

Black or African American↗
PubMed2006

Short-term retinal vessel diameter variability in relation to the history of cold extremities.

PURPOSE: To test whether the regularity and short-term changes of retinal vessel diameter are related to the history of cold hands and feet and to nailfold circulatory response to cooling. METHODS: In 13 vasospastic and 13 nonvasospastic young healthy women (based on their history of cold extremities and nailfold capillaroscopy) 20- to 30-second recordings of the ocular fundus was obtained with a retinal vessel analyzer. The spatial regularity of arterioles and venules was analyzed by means of the coefficient of variation of vessel diameter and by exploratory Fourier analysis of spatial frequencies. Temporal variability was analyzed as excursion amplitude of the vessel diameter, as a correlation of means and standard deviations of vessel diameter within a defined time period, and by Fourier analysis of temporal diameter change in the heartbeat frequency range. RESULTS: Mean diameters of selected segments of arterioles (129.9 +/- 15.3 and 124.4 +/- 24.4 microm) and venules (150.8 +/- 14.6 and 149.3 +/- 19.6 microm) were not different between the vasospastic and nonvasospastic groups, respectively. Spatial variability: The coefficient of variation in arterioles was 8.8% +/- 2.8% and 6.1% +/- 1.7%, in venules 3.8% +/- 1.4%, and 3.6% +/- 0.9% in the vasospastic and nonvasospastic groups, respectively (difference by ANOVA, P = 0.017). Fourier analysis revealed differences between arterioles in the two groups, with relative Fourier power spectrum amplitudes of spatial frequencies higher in vasospastic eyes (Mann-Whitney P = 0.029). Temporal variability: The excursion amplitudes of vessel diameters were comparable in the two groups. Individual coefficients of correlation of successive means and standard deviations of the vessel diameter were 0.11 +/- 0.23 and 0.09 +/- 0.23 in the nonvasospastic group, and 0.25 +/- 0.40 and 0.24 +/- 0.22 in the vasospastic group, in the arterioles and venules, respectively (ANOVA: vasospastic versus nonvasospastic; P = 0.038). Fourier analysis in the heartbeat frequency range revealed differences in relative power spectrum amplitudes of temporal frequencies between arterioles in the two groups (higher in the vasospastic group, Mann-Whitney P = 0.029). CONCLUSIONS: Retinal arterioles in healthy vasospastic women show higher spatial irregularity and an increased vessel diameter variation within the temporal frequency of the heartbeat than do arterioles in nonvasospastic women.

Adult↗
PubMed1987

Comparative morphometric analysis of cochlear vessels in Wistar-Kyoto rats, spontaneously hypertensive rats, and aged spontaneously hypertensive rats.

Vessel density and the ratio of the tissue area to the vessel surface area were studied by morphometric analysis techniques in normal rats, spontaneously hypertensive rats (SHR), and aged spontaneously hypertensive rats (aged SHR). Horseradish peroxidase was injected intravenously and the animals were killed 10 minutes later. The temporal bones were harvested, fixed in glutaraldehyde, and decalcified in 10% ethylenediamine tetraacetic acid (EDTA). After 7 days of decalcification, the cochleas were dissected and incubated with a diaminobenzidine tetrahydrochloride solution. Sections with stained vessels were projected onto the digitizing plate with the help of the camera lucida. The computer was used to calculate tissue area, vessel length, and vessel surface area. A statistically significant increase (p less than 0.05) in both the tissue area to vessel length ratio and the tissue area to vessel surface area ratio was demonstrated in the SHR and the aged SHR groups when compared to the WKY in the stria vascularis. No statistically significant difference was found between the two SHR groups. These data show a decrease of the vessel density in the capillary beds of the stria vascularis in spontaneously hypertensive rats. No statistically significant difference was found in the diameters of the capillary among the three groups.

Animals↗
PubMed2005

Comparison of 1- and 2-marker techniques for calculating system magnification factor for angiographic measurement of intracranial vessels.

BACKGROUND AND PURPOSE: Accurate estimation of an intracranial vessel size is crucial during a diagnostic or therapeutic angiography procedure. The use of 1 or 2 external markers of known size is previously proposed to manually estimate the magnification factor (MF) of an intracranial vessel. The authors evaluated the use of different external marker techniques commonly used during angiographic measurements. METHODS: Forty-three intracranial vessels in 17 patients were measured using 1-and 2-marker techniques. To obtain the MF, 2 metallic markers were attached to the frontal-temporal regions. The MFs for the targeted vessels were obtained from the x-ray films by measuring the image sizes of the markers and their positions with respect to the target vessel. RESULTS: Using a phantom, the errors resulted from (a) linear interpolation of MFs, (b) linear interpolation of inverse MFs, and (c) using the MFs of 1 marker, which were 1.23% to 2.23%, 0.8% to 1.55%, and 3.85% to 14.62%, respectively. A similar trend was observed for the measurement of cerebral arteries. CONCLUSION: The use of 2 markers can result in a more accurate estimation of the vessel size. The use of only 1 external marker can lead to substantial error based on the location of the target vessel. Optimizing image acquisition is also crucial for accurate determination of vessel size.

Adult↗
PubMed2006

Investigation of the influence of blood flow rate on large vessel cooling in hepatic radiofrequency ablation.

Radiofrequency (RF) ablation using high-frequency current has become an important treatment method for patients with non-resectable liver tumors. Tumor recurrence is associated with tissue cooling in the proximity of large blood vessels. This study investigated the influence of blood flow rate on tissue temperature and lesion size during monopolar RF ablation at a distance of 10 mm from single 4- and 6-mm vessels using two different approaches: 1) an ex vivo blood perfusion circuit including an artificial vessel inserted into porcine liver tissue was developed; and 2) a finite element method (FEM) model was created using a novel simplified modeling technique for large blood vessels. Blood temperatures at the inflow/outflow of the vessel and tissue temperatures at 10 and 20 mm from the electrode tip were measured in the ex vivo set-up. Tissue temperature, blood temperature and lesion size were analyzed under physiological, increased and reduced blood-flow conditions. The results show that changes in blood flow rate in large vessels do not significantly affect tissue temperature and lesion size far away from the vessel. Monopolar ablation could not produce lesions surrounding the vessel due to the strong heat-sink effect. Simulated tissue temperatures correlated well with ex vivo measurements, supporting the FEM model.

Animals↗
PubMed2001

Postnatal development of lymphatic vessels and their smooth muscle cells in the rat diaphragm: a confocal microscopic study.

This paper reports on how lymphatic vessels and their smooth muscle cells develop in the diaphragm of postnatal rats. Lymphatic endothelial cells in the diaphragm were labeled by an intraperitoneal injection of DiI-labeled acetylated low-density lipoprotein (DiIac-LDL). During postnatal week 1, DiI-ac-LDL was detected in many free cells in addition to distinct endothelial cells that formed lymphatic vessels. Occasionally, saccular lymphatics isolated from previously formed lymphatics were recognized; these were referred to as lymphatic islands. The DiI-ac-LDL-labeled free and lymphatic endothelial cells showed immunoreactivity for CD 34 and Flt-4, but most of them did not express either OX 62 or ED 1 immunoreactivity, with only some showing ED 1 immunoreactivity. This suggests that most of the DiI-ac-LDL-labeled elements were lymphatic endothelial cells, and that some were macrophages. After postnatal week 1, the DiI-ac-LDL positive cells were restricted to lymphatic vessels. Until postnatal week 6, lymphatic vessels increased as the diaphragm enlarged. Towards the end of postnatal week 2, free cells expressing alpha-smooth muscle actin (alpha-SMA) immunoreactivity increased in the diaphragm, and some of these were in contact with lymphatics. A coarse plexus of smooth muscle cells surrounding the lymphatic vessels first appeared at postnatal week 2, and this plexus became denser with age. Our findings indicate that lymphatic vessels are formed not only by sprouting from previously formed lymphatic vessels but also by migrating endothelial cells, and that smooth muscle cells may be differentiated from mesenchymal cells to form a plexus surrounding the lymphatic vessels.

Animals↗
PubMed2006

Classic beta-amyloid deposits cluster around large diameter blood vessels rather than capillaries in sporadic Alzheimer's disease.

Various hypotheses could explain the relationship between beta-amyloid (Abeta) deposition and the vasculature in Alzheimer's disease (AD). Amyloid deposition may reduce capillary density, affect endothelial cells of blood vessels, result in diffusion from blood vessels, or interfere with the perivascular clearance mechanism. Hence, the spatial pattern of the classic ('cored') type of Abeta deposit was studied in the upper laminae (I,II/III) of the superior frontal gyrus in nine cases of sporadic AD (SAD). Sections were immunostained with antibodies against Abeta and with collagen IV to study the relationships between the spatial distribution of the classic deposits and the blood vessel profiles. Both the classic deposits and blood vessel profiles were distributed in clusters. In all cases, there was a positive spatial correlation between the clusters of the classic deposits and the larger diameter (>10 microm) blood vessel profiles and especially the vertically penetrating arterioles. In only 1 case, was there a significant spatial correlation between the clusters of the classic deposits and the smaller diameter (<10 microm) capillaries. There were no negative correlations between the density of Abeta deposits and the smaller diameter capillaries. In 9/11 cases, the clusters of the classic deposits were significantly larger than those of the clusters of the larger blood vessel profiles. In addition, the density of the classic deposits declined as a negative exponential function with distance from a vertically penetrating arteriole. These results suggest that the classic Abeta deposits cluster around the larger blood vessels in the upper laminae of the frontal cortex. This aggregation could result from diffusion of proteins from blood vessels or from overloading the system of perivascular clearance from the brain.

Aged↗
PubMed2004

Triple-phase dynamic MRI of intratumoral vessel density and hyalinization grade in uterine leiomyomas.

OBJECTIVE: Our purpose was to clarify the relationship between the tissue vascularity shown on triple-phase dynamic MRI and the number of intratumoral vessels and degree of hyalinization, which are two histopathologic changes in leiomyoma. SUBJECTS AND METHODS. The subjects were 10 premenopausal patients with 20 leiomyomas who had undergone surgery without preoperative gonadotropin-releasing hormone analogue treatment. Intratumoral vessel density was determined by the mean number of intratumoral vessels with at least one smooth-muscle layer in the optic fields magnified 100 times. Hyalinization grade was determined by the severity of hyalinization, histopathologically classified in three grades. The enhancement index (EI) of the leiomyoma was calculated using the formula EI(t) = [S(t) - S(0)] / S(0), where S(0) is the signal intensity on pre-enhanced T1-weighted images and S(t) is the signal intensity on each dynamic phase image (t = 20, 60, and 180 sec) [corrected]. The histopathologic parameters of intratumoral vessel density and hyalinization grade were compared with the enhancement indexes obtained from the triple-phase dynamic MRI. RESULTS: We found positive correlations between intratumoral vessel density and EI(60) and between intratumoral vessel density and EI(180) (in both cases, p = 0.0028 and r = 0.69). We found significant differences among the mean enhancement indexes for each hyalinization grade at all dynamic phases (p < 0.01). The leiomyomas with lower intratumoral vessel densities tended to show greater hyalinization. CONCLUSION: Our results showed that leiomyomas with only slight hyalinization or with abundant vessels were well enhanced, but the leiomyomas with severe hyalinization enhanced poorly.

Adult↗
PubMed2000

Effects of side cooling on temperature, humidity and water recycling efficiency in a culture vessel for a space experiment--results of ground experiment.

Seed-to-seed experiments using dwarf plants will be conducted in Cell Biology Experiment Facility (CBEF) set up in the International Space Station (ISS). Development of a simple system to recycle water transpired by plants is necessary to save space and electrical power. A cooling system using a cooling plate that cools one side of the ventilated culture vessel to enhance water vapor condensation was developed. Effects of side cooling on air temperature, relative humidity and water recycling efficiency in the culture vessel were investigated on the ground. Decreasing the cooling plate temperature lowered temperatures of cooled side and inside air. Cooling treatment also decreased relative humidity inside the vessel less than 90% and lowered the amount of water vapor lost from the vessel through ventilation filters. This seemed to be due to the increased water vapor condensation onto the cooled side. To investigate the effect of increases in outside humidity on water recycling efficiency in the culture vessel, a water vapor transfer model was established. The calculation results indicate that an increase in relative humidity around the vessel can decrease water vapor loss from the vessel, increase water condensation onto the cooled side, and therefore, enhance water recycling efficiency in the vessel. The side cooling system seems to be useful for the CBEF in ISS because relative humidity in the CBEF is controllable.

Air Conditioning↗
PubMed2005

The openings of uteroplacental vessels with villous infiltration at different gestational ages.

CONTEXT: The number of uteroplacental vessels flowing into the intervillous space in mature placentas has been reported in some studies to increase and in others to decrease. Both villous infiltration and proliferation in the vessels have been neglected in histologic examinations and need to be studied. OBJECTIVE: To clarify these conflicting findings regarding villous infiltration and proliferation in the uteroplacental vessels. DESIGN: A retrospective study was done using placental sections of different gestational ages. The openings of the vessels in each section were counted, noting if they were with or without villous infiltration. The frequency of openings per section was calculated, and the findings were grouped by gestational age. RESULTS: The frequency of total openings was significantly lower in the 41 to 37 weeks group (1.2) than in the 36 to 30 weeks group (2.0), the 29 to 20 weeks group (2.2), and the 19 to 13 weeks group (2.4) (P < .001). The frequency of openings with villous infiltration decreased similarly in mature placentas. Chorionic villi infiltrated the openings and proliferated in uteroplacental vessels. Differentiation between arteries and veins was difficult in the basal plate, because all vessels had veinlike structures. CONCLUSIONS: This decreasing frequency of openings in mature placentas suggests that the amount of intervillous blood flow is limited in full-term and postterm pregnancy. Villous infiltration into the vessels is considered a normal finding with gestation and can provide trophoblast for uteroplacental arteries. The relationship between placental development and villous proliferation in the vessels is presented.

Chorionic Villi↗
PubMed2001

Losartan, an angiotensin type I receptor antagonist, improves conduit vessel endothelial function in Type II diabetes.

We have demonstrated previously that inhibition of angiotensin-converting enzyme (ACE) with enalapril and angiotensin II blockade with losartan improve acetylcholine-dependent endothelial function in resistance vessels of patients with Type II diabetes. It was therefore of interest to examine the effect of losartan on conduit vessel function in this group. The influence of losartan (50 mg daily for 4 weeks) on endothelium-dependent and -independent vasodilator function was determined in 12 subjects with Type II diabetes using a randomized, double-blind, placebo-controlled crossover protocol. Conduit vessel endothelial function was assessed using high-resolution ultrasound and the brachial artery response to reactive hyperaemia (flow-mediated dilation; FMD); glyceryl trinitrate (GTN) was used as a non-endothelium-dependent dilator. Losartan administration significantly increased the FMD response from 5.2+/-0.7% (mean+/-S.E.M.) to 7.4+/-0.6% of vessel diameter (P<0.05; paired t-test). There was no effect of losartan on the endothelium-independent responses to GTN (17.8+/-1.8% to 17.6+/-1.2%). Consistent with our previous findings in resistance vessels, administration of 50 mg of losartan daily improves NO-mediated dilation in the conduit vessels of subjects with Type II diabetes. Together with the findings that both ACE inhibition and angiotensin II blockade improve resistance vessel function in this group, it is likely that at least some of the beneficial effect is mediated through the angiotensin II/type I receptor pathway. A type I receptor antagonist seems a reasonable alternative to an ACE inhibitor to maintain conduit vessel endothelial function in Type II diabetic subjects.

Angiotensin I↗
PubMed2001

Reduced blood vessel formation and tumor growth in alpha5-integrin-negative teratocarcinomas and embryoid bodies.

Embryonic stem (ES) cells-wild-type, heterozygous, or null for alpha5-integrin-were injected ectopically into syngeneic mice to develop teratocarcinomas. alpha5-null-derived teratocarcinomas were significantly smaller than the wild-type or alpha5 heterozygous tumors. Histological analysis revealed the presence of tissues derived from all three germ layers, in all tumors. However, alpha5-null teratocarcinomas displayed less undifferentiated tissue than did the controls. Decreased proliferation and increased apoptosis were observed in the undifferentiated areas of the alpha5-null teratocarcinomas. The expression of extracellular matrix proteins, fibronectin and tenascin-C, and the basement membrane components, laminin, entactin/nidogen, and collagen IV, was similar in the different tumors, although the deposition of these molecules was more disorganized in alpha5-null teratocarcinomas. The absence of alpha5-integrin in the various tissues of the alpha5-null tumors was confirmed by immunohistochemistry. Many vessels, but not all, stained positively for alpha5-integrin, showing that they were host derived. Analysis of the area occupied by vessels revealed, on average, an 8-fold decrease in alpha5-null teratocarcinomas compared with control tumors. Staining for smooth muscle alpha-actin showed that pericytes and smooth muscle cells were recruited around the vessels in all tumors, suggesting similar vessel differentiation. Deposition of EIIIA and EIIIB and fibronectin around the vessels was observed in all tumors. The fact that some, although few, alpha5-integrin-negative vessels existed in alpha5-null tumors indicated that alpha5-/- ES cells could differentiate into endothelial cells. Endothelial cell differentiation and vessel formation were analyzed also in vitro. alpha5-null ES cells were differentiated into embryoid bodies, although they were delayed in growth and attachment. Differentiation into endothelial cells was achieved, but the organization into a complex vasculature was delayed compared with controls. We conclude that alpha5beta1-integrin plays a significant role in vessel formation both in ES cell cultures and in teratocarcinomas. Reduced vascularization likely contributed to the reduced proliferation and increased apoptosis observed in alpha5-null teratocarcinomas.

Animals↗
PubMed2002

[Measurement of flow velocity in feeder vessels of choroidal neovascularization with a scanning laser ophthalmoscope and image analysis system].

PURPOSE: To measure flow velocities in feeder vessels of choroidal neovascularization(CNV) secondary to age-related macular degeneration(AMD). METHODS: We examined early images of indocyanine green(ICG) angiography in 29 eyes with CNV secondary to AMD, in which feeder vessels could be identified. ICG videoangiographic images recorded at 30 frames per second with a scanning laser ophthalmoscope were installed in a personal computer. With original software, optical density measurements made with an image analyzer were performed on ICG videoangiograms for determination of dye-dilution curves. The time(T50) from the beginning of a dye-dilution curve to the ascending parts of the curve at 50% of the peak intensity was calculated. Flow velocity in a feeder vessel was obtained by dividing the distance between two points by the circulation time between T50 s at the two points on the feeder vessel. RESULTS: The mean flow velocity in feeder vessels was 33.8 +/- 32.5 (mean +/- standard deviation) mm/sec. The mean velocity in the feeder vessels of large CNV with greatest linear diameter of 1 disc diameter(DD) or larger was 43.4 +/- 30.6 mm/sec; the mean velocity in the feeder vessels of small CNV with greatest linear diameter smaller than 1DD was 20.3 +/- 20.2 mm/sec. There was a significant difference between them. CONCLUSION: The flow velocity in feeder vessels of CNV could be measured with ICG angiography and a computer-based image analysis system. This system would be useful in evaluation of choroidal circulation.

Aged↗
PubMed2000

[Experimental study on the extent of injured blood vessels in an avulsion amputation model].

OBJECTIVE: To measure the length and extent of the injured blood vessels in an avulsion amputation model. METHODS: Twenty rabbits were randomly divided into 2 groups. Group A was a sharp amputation group, and group B was an avulsion amputation group. The length and extent of the injured blood vessel was observed with naked eye, operation microscope and electron microscope, and the limbs were replanted. Group A and B were explored at three days and ten days after the replantation respectively. The patency rate and healing process were compared. RESULTS: All the severed ends of vessels in group A were neat with almost the same injured range in the three layers of the vessel wall about 1 mm away from the severed end. The vessels of group B were damaged seriously, the endothelial cells were deleted. The "jumping-like" damage could be observed in the elastic fibers. The injury of 2 to 3 mm away from the normal vessel wall could be observed by operation microscope. CONCLUSION: The damage of avulsion amputation vessels was irregular, 2 to 3 mm or more tissues should be excised under the microscope in the process of operation in order to ensure the healthy intact blood vessel walls.

Amputation, Traumatic↗
PubMed2002

[Changes in adrenomedullin and receptor activity-modifying protein 2 mRNA in myocardium and vessels during L-NNA-induced hypertension in rats].

To explore the changes in adrenomedullin (ADM) and receptor activity-modifying protein 2 (RAMP2) mRNA in myocardium and vessels in hypertension, a hypertensive rat model was prepared by administering L-NNA. Contents of ADM in plasma, myocardium and vessels were measured by radioimmunoassay (RIA). The levels of pro-ADM mRNA of myocardium and vessels were determined by competitive quantitative RT-PCR. The results showed that L-NNA induced hypertension and cardiomegaly. The ratio of heart to body weight increased by 35.5% (P<0.01). In hypertensive rats the ir-ADM in plasma, myocardium and vessels was increased by 80%, 72% and 57% (P<0.01), respectively compared with the control. The amounts of ADM mRNA in myocardium and vessels were increased by 50% and 109.2% (P<0.05), respectively, and the amounts of RAMP2 mRNA was increased by 132% and 87% (P<0.01), respectively, compared with control. The levels of ADM in myocardium and vessels were positively correlated with RAMP2 mRNA, the correlation coefficients were 0.741 and 0.885 (P<0.01), respectively. The results obtained indicate that in hypertensive rats, ADM is elevated in plasma, myocardium and ves-myocardium and vessel, and ADM and RAMP2 mRNA are up-regulated in myocardium and vessel. The ADM/RAMP2 system may play an important role in the pathogenesis of hypertension.

Adrenomedullin↗
PubMed2003

Influence of substrate salinity on structure characteristics of petiole vessel elements of Bruguiera gymnorrhiza.

The anatomy of the mature leaf's petioles of one-year-old Bruguiera gymnorrhiza seedlings cultured in greenhouse was studied in this paper. The results are as follows: (1) Most of the vessel elements of the petioles of B. gymnorrhiza are of scalariform. Helical vessels and their transition type only account for a small portion of the total vessels. However, there is a notable increase in the number of helical vessels and their transition type with increasing salinity. (2) The length of petioles, diameter and length of scalariform vessel elements, and bar number of a scalariform perforation plate all exhibit of parabolic relationship with substrate salinity. They maximized at salinity between 20 g/L and 30 g/L. (3) It is new phenomenon that there are two scalariform perforation plates, facing differently, at the polar of the vessel element of the petioles in the seedlings under 10 g/L treatment. (4) Under low salinity, the changes in the structure of vessel elements had the tendency to promote the transportation of water with increasing salinity. While under high salinity, it tended to raise the reliability of the water transportation. The adaptive significance of the morphological characteristics of vessel elements in the petiole was discussed.

Dose-Response Relationship, Drug↗
PubMed1992

The role of microvascular damage in photodynamic therapy: the effect of treatment on vessel constriction, permeability, and leukocyte adhesion.

Intravital microscopy of the rat cremaster muscle was used to evaluate changes in vessel constriction, vessel permeability, and leukocyte adhesion during and after photodynamic therapy (PDT). Animals were given Photofrin doses of 0-25 mg/kg i.v. 24 h before treatment. Cremaster muscles were exposed to 135 J/cm2 light at 630 nm. Animals given 5 mg/kg Photofrin showed no vessel constriction or increase in vessel permeability to albumin. Doses of 10 and 25 mg/kg Photofrin caused a dose-related constriction of arterioles which was observed within the first minutes of illumination at the higher drug dose. After the initial constriction, arteriole response to PDT was biphasic in nature, with some vessels relaxing to nearly control levels while others remained fully constricted. Constriction of venules occurred only at the highest porphyrin dose studied (25 mg/kg) and was delayed in comparison to arteriole constriction. Photofrin doses which produced arteriole constriction also caused an increase in venule permeability to albumin, which occurred shortly after the start of light treatment and was progressive with time. Leakage began at specific sites along the venule wall but became uniform along the entire length of the venule by 1 h after treatment. Changes in the adherence of polymorphonuclear leukocytes to venule endothelium were also observed with PDT. Photofrin doses of 25 mg/kg and 45 J/cm2 light were sufficient to cause polymorphonuclear leukocytes to become adherent to the vessel wall. A second group of animals was given indomethacin trihydrate to examine the involvement of cyclooxygenase products such as thromboxane in vessel response to PDT. Animals given 5 mg/kg indomethacin intraarterially 1 h before light treatment showed no constriction of arterioles or venules at all Photofrin and light doses studied. No increases in venule permeability to albumin were seen in this group of animals. This suggests that cyclooxygenase products including thromboxane are important in causing vessel constriction and changes in permeability during PDT. The initiating event which causes the release of these vasoactive agents remains unknown.

Animals↗
PubMed2003

Distribution of the epithelial rests of Malassez and their relationship to blood vessels of the periodontal ligament during rat tooth development.

BACKGROUND: There is some evidence that the epithelial cell rests of Malassez partition the root surface from the periodontal ligament blood vessels, and may protect the root from resorption. OBJECTIVE: The aim of the present study was to determine the distributions of the epithelial rests of Malassez (ERM) and blood vessels in the periodontal ligament (PDL) of the developing rat first molar before, during and after emergence. METHODS: Four Sprague-Dawley rats were sacrificed at two days, one week, two weeks, three weeks, four weeks and six weeks of age. After processing, the maxillae were embedded in paraffin, and sectioned longitudinally and transversely. The sections were stained with a double immuno-histochemical technique which utilised a keratin antibody AE1-AE3 (1:2,000) and an endothelial antibody Factor VIII (1:10,000) to enable simultaneous labelling of ERM and blood vessels. ERM and blood vessel counts were obtained from the mesio-buccal roots of three week, four week and six week-old rats, whilst qualitative observations were made for the earlier developmental stages. RESULTS: ERM cells and cell clusters were found in the tooth third of the PDL width at the three, four and six week stages. Cells and cell clusters increased in number with age, especially in the upper third of the mesio-buccal root. The largest numbers of cells and clusters were found on the distal surfaces of the roots in all age groups. Cells and clusters in all root surfaces increased from three to four weeks, but decreased from four to six weeks. The greatest number of blood vessels was found in the bone-side third of the PDL. The distal surface had the highest proportion of blood vessels, and the palatal surface the least proportion. The number of blood vessels in all surface quadrants did not vary much from three to four weeks of age, but increased from four to six weeks of age, possibly as a reaction to tooth emergence and occlusal function. Physiological root resorption was only observed after tooth emergence, and appeared to be related to loss of continuity of the ERM network and the incursion of blood vessels. CONCLUSIONS: Orthodontic root resorption can be regarded as an exaggerated response to loss of PDL homeostatic control, possibly mediated by the epithelial rests of Malassez.

Age Factors↗