Pathogenesis of malignant ascites formation: initiating events that lead to fluid accumulation

Initiating events leading to the accumulation of malignant ascites in the peritoneal cavity were investigated in two syngeneic transplantable murine ascites-producing tumors, MOT mouse ovarian tumor and the TA3/St mammary carcinoma. The transport of two tracers, 125I-labeled human serum albumin (125I-HSA) and 51Cr-labeled red blood cells (51Cr-RBC), into and out of the peritoneal cavity was studied at early times after i.p. tumor cell injection, prior to abundant fluid accumulation, and at intervals of 5 to 360 min after i.v. or i.p. tracer injection. Tracer influx and efflux rates were estimated from the mass of tracer passing into or out of the peritoneal cavity following a bolus injection of tracer into either the blood or the peritoneal cavity. Efflux of 125I-HSA from the peritoneal cavity was markedly reduced (3- to 5-fold) within 1 day of i.p. injection of either type of tumor cell. Significantly reduced efflux preceded any increase in tumor cell number and by itself did not induce peritoneal fluid accumulation. 125I-HSA tracer influx from plasma to peritoneal fluid did not increase detectably until 5 to 7 days after tumor cell injection, when the tumor cell number had increased by 10- to 100-fold. Only at relatively late stages of ascites tumor growth, when the flow rate into the peritoneal cavity had increased relative to the flow rate out of the peritoneum, was there net peritoneal fluid accumulation. Thus, increased influx, in addition to impaired efflux, were required for malignant ascites accumulation. Following i.p. injection, the efflux rates of 125I-HSA always exceeded those of 51Cr-RBC, even in ascites tumor-bearing animals. Furthermore, 125I-HSA tracer disappeared from the peritoneal cavity more rapidly than it appeared in the plasma, suggesting that 125I-HSA moves more rapidly through the channels by which 51Cr-RBC egress from the peritoneum (primarily diaphragmatic lymphatics) and/or has access to additional pathways not open to 51Cr-RBC. Finally, flow rates into and out of the blood and peritoneum were used to obtain kinetic parameters that characterized tracer transport: k1, the rate constant for tracer transport from the blood to the peritoneum; k2, the rate constant for tracer transport from the peritoneal cavity to the blood; and k6, the rate constant for tracer transport from the peritoneal cavity to surrounding interstitial tissue.(ABSTRACT TRUNCATED AT 400 WORDS)     

New telechelic polymers and sequential copolymers by polyfunctional initiator transfer agents (inifers)

Summary The Kennedy-Smith plot routinely used for the characterization of end-reactive (telechelic) polyisobutylenes has been recast to increase its accuracy and thus to increase its diagnostic value for the compositional analysis of telechelic polymers containing chromophores. A detailed error estimation is given. The plotting method and error limits are shown for representative mono-, di-, and tri-ended telechelic polyisobutylenes.     

Examination of the iron, copper and zinc contents in the daily menu of teen-agers

The Fe, Cu- and Zn contents of the daily menu of teen-agers were examined over two years with 124 samples taken. The samples were homogenized, subsequently dried at 104 degrees C finally incinerated at 480 degrees C. The ash was dissolved by heating with 3 N HCl. Determination of the three micro-elements was carried out by atomic absorption spectrophotometry. It was found that the daily intake of the micro-elements investigated is much below the value proposed by FAO/WHO, however, somewhat higher than the calculated Hungarian data. According to measurements, the average daily micro-element intake is 10.77 +/- 4.42 mg for iron; 1.23 +/- 0.65 mg for copper and 9.44 +/- 2.39 mg for zinc. With enumeration of iron, copper and zinc sources, dietary recommendations are given in order to increase the average values.     

pH control of the condensation reaction and its effect on the properties of formaldehyde/urea resins

The conditions of the preparation of formaldehyde/urea (F/U) resins have been supervised with the aim to reduce formaldehyde emission by influencing the ratio of methylene/dimethylene-ether-bridge linkages in the product. The most crucial point of this task is to keep the pH values of the reacting mixtures on the required level. The effect of formic acid, unevitably present in industrial formaldehyde solutions, was neutralized by applying a new buffer system, containing boric acid and ethylene glycol.     

Changes of the corneal endothelium after ultraviolet-B exposure in previously photokeratectomized eyes

The photorefractive effect of excimer lasers is based on an interaction between the 193-nm ultraviolet-C laser beam and the stromal chromophore molecules. Recently, in some patients an increase of subepithelial haze and a regression of refractive effect has been observed following suntanning (UV-B exposure). The aim of the study was to find out the possible endothelial damage caused by photoablation with increasing depth and the effect of subsequent UV-B exposure on previously photokeratactomized eyes. Altogether 12 chinchilla rabbits were treated. Four animals received a -5.0 D PRK; four animals a -15.0 D PRK and four animals a -30.0 D PRK treatment. The endothelial average number, size and variation were determined two weeks post-PRK. Three weeks following PRK, a half of the animals received a 1 J/cm2 ultraviolet-B radiation in a constant dermatological UV-chamber. The endothelial morphology was measured the same way with automated specular microscopy two weeks after UV-B irradiation. After PRK treatment there was no statistically demonstrable change in endothelial morphology. On the other hand, after UV-B radiation all eyes showed a decrease in endothelial number and an increase in size and variation. The ratio of hexagonality decreased, and endothelial rosette formation appeared. The early morphological changes resembled the physiological aging changes. Conditions (deep stromal photoablation, cumulative effect of suntanning or solarium treatments) may exaggerate the physiological aging processes leading to subsequent pleomorphism, polymegatism and cell loss. This may accelerate corneal dysfunction.     

Degradation reduction in optics imagery using Toeplitz structure

This paper is concerned with improvement in optical image quality by image restoration. Image restoration is an ill-posed inverse problem which involves the removal or minimization of degradations caused by noise and blur in an image, resulting from, in this case, imaging through a medium. Our work here concerns the use of the underlying Toeplitz structure of such problems, and associated techniques for accelerating the convergence of iterative image restoration computations. Denoising methods, including total variation minimization, followed by segmentation-based preconditioning methods for minimum residual conjugate gradient iterations, are investigated. Regularization is accomplished by segmenting the image into (smooth) segments and varying the preconditioners across the segments. By taking advantage of the Toeplitz structure, our algorithms can be implemented with computational complexity of onlyO (ln ² logn), wheren ² is the number of pixels in the image andl is the number of segments used. Also, parallelization is straightforward. Numerical tests are reported for atmospheric imaging problems, including the case of spatially varying blur. Research supported in part by a National Science Foundation Postdoctoral Research Fellowship. Research sponsored by the U.S. Air Force Office of Scientific Research under grant F49620-97-1-1039. Research sponsored by the U.S. Air Force Office of Scientific Research under grant F49620-97-1-0139, and by the National Science Foundation under grant CCR-96-23356. Research sponsored by the National Science Foundation under grant CCR-96-23356.     

Validation of image defect models for optical character recognition

Considers the problem of evaluating character image generators that model distortions encountered in optical character recognition (OCR). While a number of such defect models have been proposed, the contention that they produce the desired result is typically argued in an ad hoc and informal way. The authors introduce a rigorous and more pragmatic definition of when a model is accurate: they say a defect model is validated if the OCR errors induced by the model are indistinguishable from the errors encountered when using real scanned documents. The authors describe four measures to quantify this similarity, and compare and contrast them using over ten million scanned and synthesized characters in three fonts. The measures differentiate effectively between different fonts and different scans of the same font regardless of the underlying text     

Kidney Injury Caused by Preeclamptic Pregnancy Recovers Postpartum in a Transgenic Rat Model

Preeclampsia (PE) is characterized by the onset of hypertension (≥140/90 mmHg) and presence of proteinuria (>300 mg/L/24 h urine) or other maternal organ dysfunctions. During human PE, renal injuries have been observed. Some studies suggest that women with PE diagnosis have an increased risk to develop renal diseases later in life. However, in human studies PE as a single cause of this development cannot be investigated. Here, we aimed to investigate the effect of PE on postpartum renal damage in an established transgenic PE rat model. Female rats harboring the human-angiotensinogen gene develop a preeclamptic phenotype after mating with male rats harboring the human-renin gene, but are normotensive before and after pregnancy. During pregnancy PE rats developed mild tubular and glomerular changes assessed by histologic analysis, increased gene expression of renal damage markers such as kidney injury marker 1 and connective-tissue growth factor, and albuminuria compared to female wild-type rats (WT). However, four weeks postpartum, most PE-related renal pathologies were absent, including albuminuria and elevated biomarker expression. Only mild enlargement of the glomerular tuft could be detected. Overall, the glomerular and tubular function were affected during pregnancy in the transgenic PE rat. However, almost all these pathologies observed during PE recovered postpartum.     

Estimation in Random Coefficient Autoregressive Models

Abstract. We propose the quasi‐maximum likelihood method to estimate the parameters of an RCA(1) process, i.e. a random coefficient autoregressive time series of order 1. The strong consistency and the asymptotic normality of the estimators are derived under optimal conditions.