Capillary Space Research Articles

Is there a role for a brachytherapy vaginal cuff boost in the adjuvant management of patients with uterine-confined endometrial cancer?

Purpose/Objective: Many patients who have uterine-confined endometrial cancer with prognostic factors predictive of recurrence are treated with adjuvant pelvic radiation. The addition of a brachytherapy vaginal cuff boost is controversial. Materials and Methods: Between 1983 and 1993, 270 patients received adjuvant postoperative pelvic irradiation following hysterectomy for Stage I or II endometrial cancer. Group A includes 173 patients who received external beam irradiation alone (EBRT), while group B includes 97 patients who received EBRT with a vaginal brachytherapy application. The median dose of EBRT was 45 Gy. Vaginal brachytherapy consisted of a low dose rate ovoid or cylinder in 41 patients, a high dose rate cylinder in 54 patients, and a radioactive gold seed implant in two patients. The median follow-up time was 64 months. The two groups were compared in terms of age, histologic grade, favorable versus unfavorable histology, capillary space invasion, depth of myometrial invasion, and pathologic stage. Results: Chi-square analysis revealed that the only difference between the two groups was the presence of more Stage II patients in group B (38% versus 14%). No difference was detected for 5 year pelvic control and disease-free survival rates between groups A and B. Conclusion: There is no suggestion that the addition of a vaginal cuff brachytherapy boost to pelvic radiation is beneficial for pelvic control or disease-free survival for patients with Stage I or II endometrial cancer. Prospective randomized trials designed to study external irradiation alone versus external beam treatment plus vaginal brachytherapy are unlikely to show a positive result. Because EBRT provides excellent pelvic control, protocol development for uterine-confined corpus cancer should focus on identifying patients at risk for recurrence as well as other means of augmenting EBRT (e.g. addition of chemotherapy) in order to improve disease free survival in those subgroups.

Which prognostic factors influence the outcome of patients with surgically staged endometrial cancer treated with adjuvant radiation?

Despite the fact that retrospective reviews have documented pelvic failure rates ranging from 15-20% in patients with high-risk uterine-confined endometrial cancer who have received no or "inadequate" RT, the role of RT has been questioned. We sought to analyze pelvic control and disease-free survival for a large data base of women with corpus cancers managed with initial surgery followed by adjuvant irradiation. Between 1983 and 1993, 294 patients received adjuvant postoperative RT from one of three academic radiation practices. RT consisted of vaginal brachytherapy alone in 28 patients, pelvic RT in 173 patients, pelvic RT with vaginal brachytherapy in 97 patients, and whole abdominal RT in 2 patients. Lymph nodes were evaluated in 49%. The median number of pelvic and periaortic LN in the pathology specimen were 6 and 4, respectively. Median follow up was 63 months. 5-year disease-free survival (DFS) rate and pelvic control rates were 86 and 95%, respectively. Patient-related, treatment-related, and tumor-related characteristics were assessed for the effect on time to relapse. Unfavorable histology, older age, and capillary space invasion were univariately associated with decreased DFS and pelvic control. Pathologic Stage II patients had significantly worse DFS than Stage I patients. Multivariate analysis revealed that age, capillary space invasion, and histology were jointly predictive of disease free survival. The excellent pelvic control and disease-free survival of patients with uterine-confined disease in this series suggest that adjuvant RT should continue for patients with high risk disease. This analysis of a large group of postoperatively treated patients will provide a basis for determining alternative treatment strategies for patients who have an increased risk of disease recurrence despite RT.

Mathematical investigation of some physiological factors involved in hemodialysis hypotension.

A previously developed mathematical model is used to investigate the role of some hemodynamic, regulatory, and osmotic factors in the development of symptomatic hypotension during hemodialysis. Sensitivity analysis of the model parameters suggests that a decrease in atrial pressure, with a consequent fall in cardiac output (Frank-Starling mechanism), is the primary hemodynamic perturbation induced by ultrafiltration. Also, during the first hours of a hemodialysis session, the sympathetic mechanism working on systemic resistance is the main factor responsible for arterial pressure maintenance, and the physiological response is probably characterized by a prevalence of the cardiopulmonary over the arterial baroreflex control. During this period, a decrease in plasma osmolarity, caused mainly by urea removal, may contribute to the reduction of vascular refilling. During the last hours of the session, the arterial pressure level is also significantly affected by other factors that influence vascular refilling and mean circulatory filling pressure (systemic compliance; action of feedback mechanisms working on venous unstressed volume; plasma oncotic pressure; and, especially, capillary wall permeability and interstitial space elastance). Simulation of hemodialysis with different modalities emphasizes the importance of avoiding high ultrafiltration rates and of maintaining the sodium concentration in the dialysate close to the sodium concentration of the extracellular fluid to limit the risk of symptomatic hypotension. Higher values of sodium in the dialysate are, however, associated with poor sodium removal from the extracellular pool with risks of interdialytic morbidity. In the future, the model may be used to optimize the ultrafiltration rate and sodium profile in the dialysate according to individual patient prescriptions.

Evaluation of Recycled Glass and Compost as a Turfgrass Media

ABSTRACT Analysis of the particle size distribution of a Maui and Oahu glass sand and an imported silica sand indicated that only the Oahu glass sand met USGA guidelines for greens construction without additional screening. Bulk density, total porosity, capillary pore space, air-filled pore space, and water retention capacity of the silica and Oahu glass sand alone and with 4:1 (v:v) mixtures of several sources of organic matter were measured. Total porosity, capillary porosity, total air-filled porosity, and water retention capacity in the various mixtures of silica sand were lower than the USGA recommendations for putting greens. Organic matter-Oahu glass sand mixes had the desired bulk density and total porosity for putting greens in most instances, although performance of specific organic matters and composts varied with individual tests. Water retention capacity (or capillary porosity) and air-filled porosity of glass sand-organic matter mixtures were beyond the recommended range. Ma-cadamia husk com...

Simulation of cement hydration and the connectivity of the capillary pore space

Abstract A lot of work has been carried out previously on modeling the microstructure of cement paste. These models can be classified in three categories: overall kinetics, particle kinetics, and hybrid kinetics. We have implemented an integrated particle kinetics model for three-dimensional simulation of the evolution of tricalcium silicate (C3S) microstructure during hydration. This model explicitly takes into account the effect of interparticle contacts and the accessibility of water in pores on the rate of hydration and on structure formation. The hydration process is controlled by different mechanisms. One of the mechanisms, of parabolic nature, allows us to introduce the effect of interconnections. The microstructural development is shown at various degrees of dehydration. The size of pores in this simulation can approach zero. The overall degree of hydration, the hydraulic radius, and the connectivity of the capillary pore space of the hydrated cement with different water-to-cement (w/c) ratios, are calculated at each step of time. Plotting pore connectivity in terms of porosity results in a single curve that is independent of w/c ratio.

Simulation of Cement Hydration and the Connectivity of the Capillary Pore Space

Simulation of Cement Hydration and the Connectivity of the Capillary Pore Space

Improved outcome in patients treated with postoperative radiation therapy for pathologic stage [formula omitted] endometrial cancer

Purpose : To evaluate prognostic factors and treatment outcome for high risk pathological Stage I and II endometrial cancer patients treated with consistent postoperative radiation therapy (RT) in a single institution and to compare these results to series where RT was variably applied. Methods and Materials : Between 1986 and 1993, 98 pathologic Stage I and II endometrial cancer patients received postoperative RT at the Fox Chase Cancer Center. Papillary serous and clear cell histologies were excluded. Fifty-five patients underwent lymph node evaluation. In 17 patients, RT consisted of intracavitary brachytherapy alone to a median dose of 21 Gy, and in 81 patients, RT consisted od external beam RT to a median dose of 45 Gy followed by intracavitary brachytherapy to a median dose of 12 Gy. Intracavitary brachytherapy generally consisted of three high dose rate implants with the dose prescribed to a depth of 0.5 cm. Median follow up was 47 months. Results : The 5-year overall survival (OS), disease free survival (DFS), and freedon from pelvic recurrence (FPR) rates were 83, 85, and 89%, respectively. Pelvic recurrence either as the sole pattern of failure or combined with distant metastases was seen in 2 and 7% of patients, respectively. Distant metastases alone occurred in 4% of the patients. Univariate analysis of prognostic factors including age, grade, capillary lymphatic space invasion, depth of myometrial invasion, type of lymph node evaluation, pathologic stage, the use of brachytherapy and the number of risk factors was perfomed for OS, DFS, FPR, and FDM. Capillary kymphatic space invasion was the only statistically significant predictor for reduced DFS. Absence of lymph node dissection as well as a higher number of risk factors showed a trend toward poorer DFS ( p = 0.06 for both). Multivariate analysis revealed older age to be the only factor significant for reduced DFS, with the presence of capillary lymphatic space invasion and the absence of a lymph node dissection showing a trend toward poorer outcome (p = 0.07). Conclusion : The results of this study suggest a continued role for the use of postoperative RT in the treatment of patients with high risk endometrial cancer and eill be compared tp other series with similar high-risk factors.

Effect of intravascular ligand binding on parameter estimates derived from tracer kinetic modelling

The purpose of this study was to assess the effect of intravascular ligand binding on parameter estimates derived from tracer kinetic modelling. To this end intravascular ligand kinetics between the free and a bound compartment in plasma and the exchange of tracer between the capillary space and tissue were analysed using a simple compartment model. The effect of non-equilibrated intravascular compartments on parameter estimates was evaluated in a computer simulation. It was found that three kinetic situations must be distinguished. If the intravascular compartments are fully equilibrated when the ligand reaches the target organ, intravascular binding simply acts as a scale factor for the transport-related parameter K1. If the intravascular kinetics is very slow, only minimal binding will occur. In between there is a range where ongoing equilibration leads to time variability of K1. Since tracer kinetic modelling usually does not account for such time variability, the parameter estimates become biased, the degree of the bias depending on the intravascular binding kinetics. Furthermore the bias may be dependent on receptor density, meaning that model-derived receptor estimates are not linearly related to the true receptor density. It is concluded that intravascular ligand binding can severely affect parameter estimates derived from tracer kinetic modelling. Especially disturbing are effects due to ongoing intravascular equilibration following the arrival of the ligand in the target organ. These can be avoided by letting the ligand equilibrate with blood in a syringe prior to injection.

Osmosis and reverse osmosis in fine-porous charged diaphragms and membranes

The theory of osmosis and reverse osmosis in fine-porous charged membranes and diaphragms is presented in a deductive way with several well-structured levels of consideration. The analysis starts from the discontinuous version of irreversible thermodynamics where the membrane is considered as an absolutely black box without any information needed about its internal structure. As a trade-off for generality, however, the thermodynamic forces must be small. A number of qualitative conclusions is drawn proceeding from rather evident assumptions about the order of magnitude of various phenomenological coefficients. In the case of electrolyte mixtures those conclusions turn out surprisingly numerous and non-trivial including predictions of reflection coefficients larger than unity and strong negative osmosis. Both those anomalous phenomena are confirmed by experimental findings. The next step is the introduction of a ‘uniformly black’ box, namely a macroscopically homogeneous membrane with otherwise unspecified internal structure. That permits to employ the continuous version of irreversible thermodynamics thus allowing to drop the restriction of small thermodynamic forces. In the case of binary electrolytes general solutions in quadratures are obtained for the problems of apparent osmotic pressure and of reverse osmosis, and a very accurate approximate solution in quadratures is obtained for the problem of osmosis. Some of the theoretical predictions are compared with experimental data on the reverse osmosis of binary electrolytes in track-etched membranes with the pore size of 8 nm. In the case of electrolyte mixtures a semi-quantitative asymptotic analysis is performed in the limiting case of reverse osmosis at sufficiently large Péclet numbers, and in the particular case of one dominant electrolyte in the mixture an exact solution in quadratures is obtained. Those analyses make possible to predict a number of non-trivial regularities that are confronted with experimental data on the pressure-driven transport or ternary electrolyte mixtures across various charged porous membranes. A good qualitative agreement between the theory and experiments is recorded. The next step is the specification of phenomenological coefficients within the scope of a general capillary model. That makes the box grey but not transparent, yet, as the shape of capillary cross-section as well as the nature of surface forces are not specified. General expressions for phenomenological coefficients derived in terms of ion distribution and diffusion coefficients make possible a qualitative analysis of the effect of inhomogeneity of ion distribution inside pores. Finally, the capillary space charge model is introduced making the analysis completely mechanistic. Several approaches are considered to the approximate description of the structure of overlapped diffuse parts of double electric layers in fine pores. Since qualitative effects of microscopic heterogeneity appear to be not dependent on the details of the pore geometry sample numerical calculations are performed for slit-like capillaries where there is a general solution of Poisson-Boltzmann equation in quadratures. A more general model of pores in an electrically conducting gel is introduced in an attempt to quantitatively describe the results of complete characterization of cation-exchange membranes in terms of irreversible thermodynamics.

Quantitative analysis of dynamic Gd-DTPA enhancement in breast tumors using a permeability model.

The MRI signal enhancement in a breast tumor, measured as a function of time after a bolus injection of Gd-DTPA, may contain enough information to differentiate malignant from benign tissue. We find a physiological model for measuring capillary permeability and leakage space (P. S. Tofts, A. G. Kermode, measurement of the blood-brain barrier permeability and leakage space using dynamic MR imaging. 1. Fundamental concepts. Magn. Reson. Med. 17, 357-367 (1991)) fits the data well. The enhancement curve is particularly sensitive to the preinjection T1 of the tumor, the dose, and the time of injection. This model may provide a means of characterizing the pathophysiology of breast tumors from the Gd-DTPA enhancement curve.

Administration route dependency of distribution of PEGylated recombinant human tumor necrosis factor binding protein (rhTNFbp-PEG20K dimer) following i.v. and s.c. injection in rats

Administration route dependency on the distribution of PEGylated recombinant human tumor necrosis factor binding protein (rhTNFbp-PEG20K dimer) was observed following a subcutaneous (sc) and an intravenous (iv) administrationin rats. rhTNFbp-PEG20K dimer is composed of two rhTNFbp molecules (molecular weight 18,278 daltons each) joined by polyethylene glycol 2000 (PEG20K). The steady state distribution volume of rhTNFbp-PEG20K was 55 ml/kg and 359 ml/kg following the i.v. and s.c. administrations, respectively. These results suggest that the distribution of rhTNFbp-PEG20K is limited within the capillary space after i.v. administration, while rhTNFbp-PEG20K can distribute into a space (35.9% of body weight) which is between extracellular space and total body water. A lymphatic absorption may play a role in the distribution of rhTNFbp-PEG20K dimer following the sc administration. The present study suggests that the administration route of large protein molecule should be determined depending upon target sites.

Malignant melanoma of the vulva treated by radical hemivulvectomy. A prospective study of the gynecologic oncology group

Beginning in 1983, the Gynecologic Oncology Group (GOG) conducted a prospective clinicopathologic study of primary malignant melanoma of the vulva. The objectives of this study were to determine the relationship of histopathologic parameters and microstaging to the International Federation of Gynaecology and Obstetrics (FIGO) staging and prognosis. All patients with primary untreated malignant melanoma of the vulva and no history of previous or subsequent other primary invasive malignancy were eligible for study entry. All patients were required to have modified radical hemivulvectomy as minimal therapy. Groin dissection was optional. Histopathologic specimens were reviewed for capillary space involvement, Clark's level, Breslow's depth of invasion, cell type, and melanin distribution. Patient characteristics were analyzed in their relationship to groin node status and recurrence-free interval. Between 1983 and 1990, 81 patients were entered in the study. Of these, 71 were evaluable. Thirty-four patients underwent radical hemivulvectomy, and 37 patients underwent radical vulvectomy. In addition, 56 patients underwent groin node dissection. The factors that were independently correlated with groin node status were: capillary lymphatic space involvement (p = 0.0001) and central primary tumor location (i.e., bilateral/clitoral/T3) (P = 0.003). The other factors that were significant--clinical tumor size, vulvar staging (FIGO), GOG performance status, and Breslow's depth of invasion--were not independent predictors of positive nodes. The factor with the highest significant correlation with recurrence-free interval was the 1992 staging system of the American Joint Committee on Cancer (AJCC) for malignant melanoma of the skin. Using multiple regression, AJCC stage was the only independent prognostic factor. In the absence of AJCC stage, Breslow's depth of invasion was the most prognostic. The biologic behavior of vulvar melanoma is similar to other nongenital cutaneous malignant melanoma.

Physical Properties of Hawaiian Golf Course Sands

Physical properties (particle size distribution, bulk density, capillary pore space, non-capillary pore space, hydraulic conductivity, and water retention) of three imported silica sands (Perth, Malaysian, and Newcastle), a man-made sand product (Mansand), and coral sand alone and in peatmoss mixtures were determined to evaluate their suitability as golf-green substrates. Based on laboratory evaluation of physical properties, the silica sands amended with peatmoss (15%) were superior to coral sand or crushed basalt (Mansand) amended with 15% peatmoss for use in high-traffic turfgrass areas.

Atmospheric aerosol particles and their role in the formation of dew on the surface of plant leaves

Measurements of the electrical conductivity along the surface of leaves or conifer needles show that the wetting of such surfaces coated with wax already starts below a relative humidity of 100%. To explain the observations, the deposition of water soluble atmospheric aerosol particles on these surfaces is taken into account. It is shown that the capillary space between particle and settling surface and, as an additional indispensable condition, the water solubility of at least some constituents of the atmospheric aerosol particle (i.e. a combined capillary-solution effect), permits the formation of condensate or dew water significantly below a r.h. of 100%.

Phenomenological theory of pressure-driven transport of ternary electrolyte solutions with a common coin and its specification for capillary space—charge model

Pressure-driven transport of ternary electrolyte solutions have been considered within the scope of irreversible thermodynamics. At small thermodynamic forces, a general solution for an n-ionic system has been obtained and, further, specified and examined for a ternary system with a common coion. With the help of the continuous version of irreversible thermodynamics, two further limiting cases have been considered, namely, one of large Peclet numbers and one of a small addition of one of the electrolytes. Thermodynamic results have been exemplified within the scope of the capillary space—charge model. Parameters which govern the separation of counterions have been examined as functions of fixed charge density, pore size, feed ionic strength, the ratio of counterion mobilities and charges. A significant separation of counterions with different mobilities and/or charges was predicted.

Modelling the leaching of calcium hydroxide from cement paste: effects on pore space percolation and diffusivity

As concrete is exposed to the elements, its underlying microstructure can be attacked by a variety of aggressive agents. For example, rainwater and groundwater can degrade the concrete by dissolving soluble constituents such as calcium hydroxide. Using computer simulation, this paper examines the effects of calcium hydroxide dissolution on two material properties: the percolation properties or connectivity of the capillary pore space, and the relative ionic diffusivity. A microstructural model for cement paste is used to produce a hydrated specimen which is subsequently subjected to the leaching process. Pore space percolation characteristics and relative ionic diffusivity are computed throughout the leaching process as a function of total capillary porosity. Material variables examined are water: solids ratio and silica fume content. Percolation theory is used to develop the concept of a critical volume fraction of calcium hydroxide plus capillary pore space. It is shown that this critical combined volume fraction determines the magnitude of the effect of leaching on relative ionic diffusivity.

Hydrodynamics, organisms and pollution of coastal sands

This account concerns the movement of water in sublittoral sands, the exchange of air and water in littoral sands, the role of organisms in these ecosystems and the modifications caused by pollution. The patchy distribution of sand organisms, and the capacity of coastal sands for the degradation of organic debris, are considered. Porosity, permeability and the related concepts of specific permeability, capillary and cavity space, generated by fluid-flow and recognised by amphioxus acting as an environmental probe, are discussed. The importance of the organic component, consisting of bacterial films on sand-grains above and below the redox potential discontinuity as a modifier of sand properties, is emphasised. In sublittoral sands, where air is absent, the mechanisms causing irrigation are outlined. The effects of pollution by fine mineral particles, sewage and heated effluents are considered. In littoral sands, where both water and air are present, the relative movement and distribution of water and air, due to irrigation by tidal fluctuation, water inputs from the land and capillarity, are considered. The effects of pollution by low concentrations of detergents on the permeability of beaches are discussed.

Immobilization of Anabaena azollae in hallow fibre photobioreactors for ammonia production

Hollow fibres made from polysulphone and polypropylene were used for testing the growth of Anabaena azollae. The surface properties of the fibres for attachment of cyanobacteria and the morphological features of A. azollae growing on the surfaces and in the extra capillary space of the fibres were examined by scanning electron microscopy. Three types of photobioreactors for the photosynthetic production of ammonia by A. azollae were constructed. The reactors were made of hollow fibres and fibres with a calcium alginate gel matrix in the interfibre region. Dilute ammonia produced in the medium was concentrated with a membrane separator by absorption with HCl. Ammonia production was studied with and without the inhibitor MSX. The ammonia concentration in the effluent reached 600–700 μ m with MSX and 120–350 μ m without MSX in the medium.

Pulmonary aspergillosis causing right ventricular failure and ascites in meat‐type chickens

Experimentally induced pulmonary aspergillosis in one-day-old chicks resulted in some with no clinical signs or little damage while others developed marked interstitial pneumonia. Chicks with severe lung damage died from respiratory failure (60%) or developed pulmonary hypertension followed by right ventricular hypertrophy and dilation, right ventricular failure from valvular insufficiency, portal hypertension and ascites (10.7%). Chicks that developed ascites before day 16 (13/31) had shown mouth-breathing and other signs of hypoxia and developed pulmonary hypertension, probably from hypoxia-induced polycythaemia. Most chicks that developed ascites after day 16 (18/31) had not shown an increased depth or rate of respiration indicating that they had not been significantly hypoxic. Microscopic examination of lung tissue indicated that in these chicks the pulmonary hypertension was caused by lung consolidation and fibrosis restricting blood capillary space and resulting in cor pulmonale.

Quantitative assessment of the rat stria vascularis

Stria vascularis tissues from standardized regions in the basal, middle and apical turns of the rat cochlear duct were assessed quantitatively. Strial width, number of marginal cells across the strial width, radial area, as well as the volume density of the different components of the stria vascularis were determined for each standardized region. Strial width, number of marginal cells across the strial width and the radial area were greatest in the basal region and least in the apical region of the cochlea. The volume density of intermediate cells and capillary space was statistically unchanged in the three examined regions of the stria vascularis. However, the volume density of marginal cells and that of basal cells were different between regions. The volume density of marginal cells was highest in the basal turn while the volume density of basal cells was greatest in the apical turn. An objective assessment of the response of the stria vascularis to environmental conditions can be made by kant of its cellular architecture, providing a means to compare the effects of various agents between animal models used to study human inner ear dysfunction.