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At least 253 records · Page 14Linked to original sources
PubMed2003

Sympathetic mediated vasomotion and skin capillary permeability in diabetic patients with peripheral neuropathy.

AIMS/HYPOTHESIS: A loss of sympathetic function could lead to changes in capillary fluid filtration in diabetic patients. We investigated whether a decreased sympathetically mediated vasomotion in the skin in diabetic patients with peripheral neuropathy is associated with an abnormal capillary leakage. METHODS: Three matched groups were studied: 18 diabetic patients with documented peripheral neuropathy (DN), 18 diabetic patients without peripheral neuropathy (D), and 18 healthy control subjects (C). Sensory and motor nerve function of the distal extremities were assessed by standard neurography, and expressed in a sensory-motor nerve function score. Sympathetic vasomotion of the skin microcirculation was assessed by determining the power of blood flow variability in the low-frequency (0.02-0.14 Hz) band by spectral analysis of laser Doppler flowmetry at the median ankle. Skin capillary leakage was evaluated by sodium fluorescein videodensitometry at the same site of the foot. RESULTS: Sympathetically mediated vasomotion of the foot skin microcirculation was lower in diabetic patients with documented peripheral neuropathy compared with diabetic patients without peripheral neuropathy and control subjects (p<0.001). Capillary sodium fluorescein leakage was larger in 18 diabetic patients with documented peripheral neuropathy than in diabetic patients without peripheral neuropathy (p<0.02) and C (p<0.005). Multiple regression analysis disclosed that a reduced sympathetically mediated vasomotion, together with a lower sensory-motor nerve function score, independently contributed to the variance in sodium fluorescein leakage, for 30% (p<0.001) and 17% (p<0.01), respectively. CONCLUSIONS: A loss of sympathetic tone, apart from sensory-motor nerve dysfunction, seems to be a major determinant of an increased capillary permeability in diabetic patients with neuropathy.

Capillary Permeability↗
PubMed1984

Intratumor distribution of capillary permeability surface area product (PS) correlated to tumor vascular space and blood flow.

The intratumor distribution of the capillary permeability surface area product (PS) correlated to the intratumor distribution of vascular space and of blood flow was studied by labeled albumin in a transplantable rat fibrosarcoma. A wide heterogeneity in intratumor distribution of PS was found. The tumor PS values were not significantly correlated to tumor vascular space or to blood flow values. This might suggest that intravascularly administered drugs could reach a comparative high intratissue concentration also in less vascularized tumor areas.

Albumins↗
PubMed1976

Measurement of an index of muscle capillary permeability and its correlation with serum insulin values in maturity-onset diabetic subjects.

1. An index of capillary permeability was obtained by measuring the ratio of the clearance rate of 77Br to that of 133Xe in the anterior tibial muscle, after a short period of maximal ischaemic exercise. 2. Seventeen control subjects and thirty-two maturity-onset, non-insulin-treated diabetic subjects, aged 60 years or less, were studied. Short glucose tolerance tests were performed in the diabetic subjects during which blood sugar and serum insulin concentrations were estimated. 3. The 77Br/133Xe clearance ratio was increased in the diabetic subjects compared with the control subjects. In the diabetic subjects, there was an inverse correlation between the insulin at 60 min after glucose and the 77Br/133Xe clearance ratio. There was also a direct correlation between the 77Br/133Xe clearance ratio and the age of the patient in the diabetic group but not in the control group. 4. The results demonstrate that a reduced insulin response to oral glucose is associated with increased capillary permability and may play a role in the development of microangiopathy.

Adult↗
PubMed1990

Capillary permeability of 131I-albumin in the resting human forearm.

STUDY OBJECTIVE: The aim was to examine capillary permeability of 131I-albumin in the normal, resting human forearm. DESIGN: A bolus injection of 131I-albumin was injected into the brachial artery, and the residue function was measured by external registration over the forearm tissues. The results were analysed by indicator kinetic "black box" theory using the single injection, residue detection method which is based on indicator diffusion principles. SUBJECTS: Seven normal volunteers participated in the study. MEASUREMENTS AND MAIN RESULTS: The mean capillary extraction fraction of 131I-albumin was 0.023 (SD 0.0056), n = 7, at a mean plasma flow rate of 2.1 (0.34) ml.100 g-1.min-1. At an estimated capillary surface area of 70 cm.g-1 the permeability coefficient was 11.10(-8) cm.s-1. CONCLUSIONS: According to the theories of restricted diffusion and equivalent pores the results are compatible with an equivalent pore radius estimate of 113 A using additional previously published results from experiments with 51Cr-EDTA.

Albumins↗
PubMed1989

Acute effects of low-dose cranial irradiation on regional capillary permeability in experimental brain tumors.

To determine the acute effects of low-dose cranial irradiation (CRT) on regional capillary permeability (RCP) of normal brain, brain tumor and damaged brain surrounding the tumor, we used quantitative autoradiography (QAR) to measure regional blood-to-tissue transport (K) of [14C]aminoisobutyric acid (AIB) in experimental C6 brain tumors 3-4 h after a single dose of 3 Gy CRT. K increased 63% in cortex, 30% in basal ganglia and 31% in brain surrounding the tumor (BST) vs. controls (P less than 0.005). K did not change in the tumor or in the brain adjacent to the tumor (BAT), suggesting that capillaries of normal parenchyma are more sensitive to the acute effects of CRT than capillaries of damaged parenchyma or tumor.

Aminoisobutyric Acids↗
PubMed1993

Capillary permeability in experimental rat glioma and effects of intracarotid CDDP administration on tumor drug delivery.

We have examined the capillary permeability within and adjacent to experimental rat gliomas, and the effect of intracarotid administration of cisplatin in this model. Permeability to 14C-sucrose was 25-fold and six-fold higher within the brain tumor and in the tumor periphery and adjacent tissue respectively than in the normal cortex. Intracarotid administration of cisplatin resulted in ten-fold increase in experimental gliomas and also a significant increase in the tumor periphery and adjacent tissue, when compared to the intravenous route. Intracarotid administration of cisplatin to rat did not cause acute vascular damage in either the brain or brain tumor at the dosage used.

Animals↗
PubMed1992

Changes in lung function and pulmonary capillary permeability after cardiopulmonary bypass.

OBJECTIVE: To assess the possibility that changes in lung function following cardiopulmonary bypass are associated with increased pulmonary capillary permeability. DESIGN: A prospective, descriptive study. SETTING: Adult cardiothoracic ICU in a post-graduate teaching hospital. PATIENTS: Ten sequential patients undergoing cardiac surgery requiring cardiopulmonary bypass. MEASUREMENTS: Arterial blood gas tensions, helium dilution end-expiratory lung volume, and carbon monoxide transfer were measured by a rebreathing technique preoperatively and 2 hrs postoperatively. Lung extravascular protein accumulation index was measured by a double-isotope technique 2 hrs postoperatively and in a group of normal controls. RESULTS: Mean +/- SEM alveolar-arterial PO2 gradient increased from 77 +/- 14 torr (10.3 +/- 1.8 kPa) to 138 +/- 24 torr (18.5 +/- 3.2 kPa) (p less than .01). Functional residual capacity decreased by 20.2 +/- 5.6% (p less than .01). Carbon monoxide transfer decreased by 26.7 +/- 5.3% (p less than .01) for the lung as a whole and by 17.9 +/- 3.2% (p less than .01) per liter of accessible gas volume. Protein accumulation index ranged from 0.03 to 3.2 x 10(-3) (median 0.6) postoperatively (median for normal subjects 0.4; p less than .05), although only one patient had a value indicative of clinically important endothelial injury. CONCLUSIONS: Cardiac surgery involving cardiopulmonary bypass results in a deterioration in lung function characterized by a loss of lung volume, a reduction in carbon monoxide transfer, and an increase in the alveolar-arterial PO2 gradient. These changes do not appear to be mediated by an increase in pulmonary endothelial permeability.

Aged↗
PubMed1964

THE USE OF CHANGES IN CAPILLARY PERMEABILITY IN MICE TO DISTINGUISH BETWEEN NARCOTIC AND NONNARCOTIC ALALGESICS.

An extension of the "squirming test" is described which makes the method specific for nonnarcotic analgesics. The intraperitoneal injection of acetic acid causes squirming and an increase in capillary permeability that is measured by direct estimation of plasma-bound dye (Pontamine Sky Blue) which has leaked into the peritoneal cavity. Nonnarcotic analgesics inhibit squirming and leakage of dye. Values for the oral ED50s for both effects are given for a number of typical compounds. Narcotic analgesics, in doses that produce analgesia, inhibit squirming but do not significantly affect leakage of dye. Drugs that stimulate the central nervous system and also inhibit squirming have no significant effect on leakage of dye over the range of doses which inhibit squirming. Corticosteroids do not significantly inhibit either squirming or leakage of dye.

Acetates↗
PubMed1988

[Changes in capillary permeability in experimental brain tumor].

It is still controversial whether edema fluid around a malignant brain tumor is derived from capillaries inside the tumor itself or not only from tumor vessels but also from peritumoral tissue. The purpose of this study is to clarify the region where the capillary permeability is increased using double autoradiographic method. A suspension of 1 X 10(4) rat glioma cells (RG-12) was stereotactically implanted into the right basal ganglia of C-D Fisher rats. In this model, all animals are dead 20 +/- 1 days after the implantation. Two kinds of tracers, 14C-alpha-aminoisobutyric acid (AIB) and 131I-human serum albumin (HSA), were administered 14 to 17 days after the tumor implantation. In all rats, 14C-AIB was intravenously injected 10 min before decapitation. 131I-HSA was given 10 min before decapitation in five animals (group 1), one hour before in four animals (group 2), and six hours before in three animals (group 3). Autoradiograms for 131I-HSA were exposed for initial one to two days after the decapitation, while the exposure for 14C-AIB was delayed until 4 months later. Autoradiograms of these two tracers were compared with the corresponding sections with H-E stain for neuropathological examination. In group 1, the distribution of HSA as well as AIB was quite similar to tumor itself. In group 2 and group 3, the distributions of AIB were similar to the tumor. However, the distributions of HSA were 1.4 fold larger (group 2) and 3.6 fold larger (group 3) than the tumor and expanded into the peritumoral region.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminoisobutyric Acids↗
PubMed1991

Upper and lower bounds on capillary permeability ratios of Cr-EDTA to cyanocobalamin in rat hindquarters.

The single injection indicator dilution technique, often used for assessing capillary permeability, was employed for estimations of the equivalent pore radius of skeletal muscle microvessels according to the theory of restricted diffusion. There are, however, certain important sources of error that must be considered in order to allow conclusions regarding the degree of restricted diffusion. In this study, we have recalculated previously published data in order to minimize the effect of heterogeneity of the second kind, i.e. a transit-time dependence of the fractional extraction values. The method used makes it possible to calculate reliable intervals of confidence for the permeability surface area products, and hence for the permeability surface area product-ratios (and equivalent pore radius), taking into account the maximal theoretical impact of back diffusion on measured extraction data. After correction for transit-time dependent effects of heterogeneity, the permeability surface area product-ratio of Cr-EDTA to cyanocobalamin (vit. B12) from 48 measurements in eight rats was found to have a theoretical 'upper bound' of 2.63 +/- 0.06 and a lower bound of 2.10 +/- 0.07, corresponding to an equivalent pore radius of 60 to 109 A. This minimum pore radius estimate was even further reduced by corrections for plasma flow dependent reductions in overall extraction fraction (heterogeneity of the first kind) to 45 A, whereas the upper bound on pore radius was reduced to 60 A. These data strongly support the presence of marked restricted diffusion of small solutes in the maximally vasodilated rat hindquarter microvasculature.

Animals↗
PubMed1992

Nailfold capillary permeability in psoriatic arthritis.

This study is the first report of the permeability status of nailfold capillaries in psoriatic arthritis (PA). "Traditional" nailfold capillary microscopy and intravital fluorescence videomicroscopy were carried out at the nailfold of 13 patients with PA. Twenty five healthy subjects served as controls for nailfold capillary microscopy, and 15 out of these for fluorescence videomicroscopy. The following parameters were assessed: capillary length, apex width, maximum loop width, maximum limb width, loop density, visibility of subpapillary venular plexus, loop tortuosity, transcapillary diffusion, and interstitial concentration at different sites and times of Na-fluorescein given in intravenous bolus. Morphometric analysis of capillaroscopic findings showed a significant increase of loop length (mean +/- SD: 290.1 +/- 73.5 microns) when compared to healthy controls (223.3 +/- 51.9 microns) (P < 0.02). Transcapillary passage of Na-fluorescein was homogeneous and symmetric both in PA patients and in controls. Mean transcapillary and interstitial diffusion was not significantly enhanced at the nailfold in PA patients. Our data support the view that PA is not characterized by a specific capillaroscopic pattern and/or significant abnormalities of microvascular dynamics at the nailfold.

Adult↗
PubMed1995

Clinical studies of alveolar-capillary permeability using technetium-99m DTPA aerosol.

Soluble radioaerosols such as technetium-99m diethylene triamine pentacetate (DTPA) permit simple quantitative studies of alveolar-capillary permeability to be performed, since the submicronic aerosols are deposited mainly at the lung periphery and are cleared across the alveolar-capillary membrane. Regional alterations in permeability can also be noted using this radionuclide technique. We have measured the pulmonary epithelial permeability in normal subjects and the alteration in smokers, in glue-sniffers, in patients with inhalation burns, in chronic obstructive pulmonary disease (COPD) and in patients with lung metastases from thyroid cancer treated with radioiodine 131I. In the normal volunteers, the time taken for 50% of inhaled 99mTcDTPA to be cleared form the lungs (T1/2) was 66 minutes +/- 1sd of 12 mins. The smokers had a mean T1/2 of 20 mins +/- 1sd 4 min. In the hard-core glue-sniffing group, the majority were smokers who had stopped smoking and glue-sniffing for periods varying from 1 day to 42 days, and it was possible to note the changes in clearance times against period of abstinence. In the patients with inhalations burns, there was change in lung clearance arising from pulmonary epithelial damage; these patients showed increased rate of clearance (short T1/2) with mean T1/2 of 36 min +/- 1sd of 11 mins, while the retention images revealed regional lung damage in moderately severe inhalation burns. Twenty-four patients with COPD had inhalation scans done with Tc-99m tin colloid radioaerosol, and these images were compared with the perfusion lung scans done with 99mTc macroaggregated albumin (MAA); in general the perfusion images matched the defects noted in the inhalation scans. The 99mTc DTPA clearance rate in these patients was normal i.e. T 1/2 = 78 +/- 14 mins. In the thyroid cancer patients with lung metastases, who had high doses of radioiodine treatment, the T 1/2 values were normal or prolonged slightly, mean T1/2 = 76 min +/- 23.

Adolescent↗
PubMed1994

Myocardial capillary permeability to iohexol. Evaluation with fast x-ray computed tomography.

RATIONALE AND OBJECTIVES: The accuracy and sensitivity of fast x-ray computed tomography (CT) for estimating myocardial capillary permeability to iohexol was evaluated. The long-term goal is to quantitate capillary integrity. METHODS: Anesthetized pigs were scanned during coronary infusion of adenosine and an aortic root injection of iohexol. The CT images were used to compute myocardial perfusion (F) and capillary extraction factor (E). The permeability-surface area product (PS) was calculated as follows: PS = -F.ln(1-E). Accuracy of the PS value was evaluated with catheter-sampled dual-dilution curves (DDC) resulting from simultaneous injection of cobalt-58 EDTA and iodine-125 albumin. A second group of pigs was scanned while bradykinin (5, 10 or 20 ng/kg/min) was infused into the coronary artery. RESULTS: The DDC and CT-based PS values (mean +/- standard deviation) were as follows: 0.149 +/- 0.107, 0.125 +/- .067; 0.127 +/- 0.072, 0.129 +/- 0.053; and 0.132 +/- 0.043, 0.190 +/- 0.111 for 350, 230, and 175 mg iodine/mL, iohexol respectively. The regression was PS = 0.22 [bradykinin] + 0.083, r = .845. CONCLUSIONS: Dual-dilution curve-obtained and CT-obtained PS values are well correlated. The data show that concentration of iohexol has little (P > .1) impact on the calculated PS value and the bradykinin data suggest good sensitivity.

Adenosine↗
PubMed1979

Capillary permeability to interstitial microinjections of macromolecules and influence of capillary hydrostatic pressure on endothelial ultrastructure.

The transcapillary flux of horseradish peroxidase (HRP, mol. diam. 50--60 A) and ferritin (mol. diam. 110--120 A), microinjected interstitially into the biceps femoris muscle of rats, was analyzed in the electron microscope. From 1 min postinjection HRP was observed to occupy endothelial plasmalemmal vesicles in all positions to be expected if a vesicular transendothelial transport of material occurs in the interstitium-to-lumen direction. Permeation of HRP through the intercellular clefts of the endothelium could not be demonstrated unequivocally. The periendothelial basement membrane appeared to constitute a significant permeability barrier against ferritin. The endothelial ultrastructure in muscle capillaries was analysed morphometrically after artificial perfusions of rat hindquarters at venous outflow pressures of -4 cm H2O and +10 cm H2O. In the "high pressure" material the endothelium was thinner and the frequency of vesicles open towards the interstitium was lower than after perfusion at low outflow pressure. The findings may indicate that net transendothelial transport via vesicles varies with hemodynamics.

Animals↗