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Biomedical subjects

M Dolz

Publications and source records attributed to M Dolz.

15 recordsLinked to original sources
PubMed2005

Site-bond percolation of polyatomic species.

A generalization of the classical monomer site-bond percolation problem is studied in which linear k-uples of nearest neighbor sites (site k-mers) and linear k-uples of nearest neighbor bonds (bond k-mers) are independently occupied at random on a square lattice. We called this model the site-bond percolation of polyatomic species or k-mer site-bond percolation. Motivated by considerations of cluster connectivity, we have used two distinct schemes (denoted as S intersection of B and S union of B) for k-mer site-bond percolation. In S intersection of B(S union of B), two points are said to be connected if a sequence of occupied sites and (or) bonds joins them. By using Monte Carlo simulations and finite-size scaling theory, data from S intersection of B and S union of B are analyzed in order to determine the critical curves separating the percolating and nonpercolating regions.

Journal Article↗
PubMed2000

A time-dependent expression for thixotropic areas. Application to aerosil 200 hydrogels.

Experimental determination of the areas enclosed under the up curve, sigma = sigma(;gamma), corresponding to time zero, and the down curve, which would be obtained following complete rheodestruction of the system structure, is not an easy matter. In the present study a semi-empirical procedure for calculating the hypothetical values of these parameters is proposed. With these parameters it is possible to obtain a time-dependent expression for the thixotropic areas, S(T). This procedure has been applied to the study of the thixotropic behavior of Aerosil 200 hydrogels at different concentrations. The comparative analysis of these systems has been realized by studying the relative thixotropic areas and relative thixotropic rates that are obtained from S(T).

Area Under Curve↗
PubMed1999

A simplified method for postmortem coronary angiography using gastrograffin.

OBJECTIVE: To assess the adequacy of perfusion of the heart at autopsy with a gastrograffin and dye mixture to obtain rapid postmortem angiograms while simultaneously documenting the vascular distribution of the myocardium. BACKGROUND: Postmortem coronary angiography is occasionally used in the evaluation of suspected cardiac deaths. Angiography provides legal documentation and can serve to guide subsequent cardiac dissection. Multiple techniques have been suggested in the literature for coronary angiography using infusion of radio-opaque silicone or gelatin. These techniques are cumbersome and require equipment generally not available in autopsy suites. METHODS: Following removal of the heart, a mixture of gastrograffin and colored dyes is injected into each coronary artery via a syringe. The coronary arteries are ligated and radiographs are obtained. After fixation, the heart is dissected in the usual manner. RESULTS: Adequate postmortem coronary angiograms are routinely obtained with this method. The coronary arterial distribution within the myocardium is easily documented at both the gross and microscopic levels because of the presence of differential coloration. CONCLUSIONS: The aforementioned technique using a gastrograffin and dye mixture provides a simplified approach to postmortem angiography. The novelty of the procedure stems from the low cost, ease of implementation, dual ability to assess vascular anatomy radiologically (gastrograffin), and gross distribution and histologic findings of dependent tissue using the light microscope (colored dye). This technique is inexpensive, rapid, and easily used, making it more suitable for general hospital practice and medical examiners' offices than previously described methods.

Adult↗
PubMed1999

Polycystic ovarian syndrome: assessment with color Doppler angiography and three-dimensional ultrasonography.

We conducted a three-dimensional ultrasonographic evaluation of the size and structure of the ovaries of women who had clinical and biochemical findings suggestive of polycystic ovary syndrome. We carried out a comparative color Doppler frequency and color Doppler amplitude study of the vascular patterns of these ovaries. This study involved 65 women of reproductive age with polycystic ovary syndrome and 25 eumenorrheic women who were not taking hormonal contraceptives and who had a body mass index below 25 kg/m2. Compared to controls, women with polycystic ovary syndrome had larger ovaries and thicker stroma, increased impedance in the uterine arteries, increased stromal vascularity with decreased impedance that persisted throughout the menstrual cycle, and a lack of luteal conversion.

Adult↗
PubMed1997

Thixotropy of highly viscous sodium (carboxymethyl)cellulose hydrogels.

A general method to quantify the thixotropic behavior of systems with very low thixotropy is proposed. The areas enclosed by the rheograms tau = f(gamma) must be fitted to functions with well-determined boundary conditions. From these equations the corresponding thixotropic areas are obtained, together with the theoretical area enclosed by the rheogram corresponding to the maximum rheodestruction. The proposed method is applied to high viscosity sodium (carboxymethyl)cellulose gels.

Carboxymethylcellulose Sodium↗
PubMed1995

Shear stress synergism index and relative thixotropic area.

Shear stress synergism index and relative thixotropic area are introduced as quantifiers of viscous synergism and comparative thixotropy. The utility of these terms is demonstrated by their application to microcrystalline cellulose-sodium carboxymethyl cellulose (MCC-NaCMC) hydrogel, a starch of different botanical origins hydrogels and their combinations.

Carboxymethylcellulose Sodium↗
PubMed1991

[Transient polyuria in pregnancy in diabetes insipidus and gestational diabetes].

Two pregnant women developed overt polyuria (up to 11 l/day) and polydipsia during their second and third trimesters of pregnancy. In one patient hydronephrosis was present. Both patients suffered from mild gestational diabetes mellitus. Plasma sodium was 145 and 162 mmol/l. Polyuria and urinary hypo-osmolality responded well to desmopressin acetate. After delivery, polyuria and polydipsia disappeared in one patient and significantly improved in the other. Infusion of hypertonic saline one and two weeks respectively after delivery led to plasma hyper-osmolality (294 mosmol/kg and 305 mosmol/kg) without detectable stimulation of arginine vasopressin (AVP). Anterior pituitary function was normal. No stimulation of AVP occurred following insulin-induced hypoglycemia. AVP plasma disappearance after i.v. pulse injection of 1 microgram AVP as well as AVP plasma concentration after continuous infusion of 10 ng AVP/min was studied two weeks after delivery in one patient. The results suggested markedly elevated degradation of AVP compared to control subjects, probably due to an increased vasopressin activity. Eight months after delivery, hypertonic saline infusion in one patient led to a plasma-osmolality of 312 mosmol/kg without stimulation of AVP. In the second patient, AVP was not detectable (less than 0.2 pg/ml) six months after delivery when plasma osmolality was 290 mosmol/kg. Our studies demonstrate that a subclinical compensated diabetes insipidus was preexistent in both patients. Exacerbation occurred due to an increased AVP-clearance and presumably due to the hemodynamic and hormonal alterations during pregnancy, including a mild gestational diabetes mellitus.

Adult↗
PubMed1989

Evaluation of the elastic behaviour of central venous PVC, polyurethane and silicone catheters.

Eighty used and 20 new silicone, polyurethane and polyvinylchloride central venous catheters were tested to establish the Young's modulus and the bending stiffness of the catheters and their introducers. The catheters were subjected to longitudinal traction forces and their lengthening measured. Young's modulus and the geometric moment of inertia were then calculated. It is shown that polyurethane catheters show least variation in their elastic characteristics, and that silicone catheters offer least resistance to bending and do not change their elastic properties after use. All catheters were equally unlikely to cause thrombus production if this is related to excessive bending stiffness.

Catheterization↗
PubMed1985

[Transrectal prostatosonography. Follow-up in prostate cancer therapy].

Thirty-five cases of prostate carcinoma were followed after orchiectomy and during drug therapy using both ultrasound and digital palpation to measure the prostate. Following orchiectomy and drug therapy the prostate shrunk an average of one third within six months independent of the grading and staging of the carcinoma. The biggest shrinkage was observed in the first two months after therapy. There was agreement between transrectal ultrasonography (TPS) and digital palpation in judging the prostate capsule in two thirds of the cases. Ultrasonographically, a downstaging of the capsule in twenty per cent and an upstaging in fourteen per cent of the cases was found. Three quarters of the G II prostate carcinomas improved ultrasonographically in structure and capsule in the twelve month period of observation while two thirds of the G III prostate carcinomas did not improve. According to our results the routine use of TPS seems not to be indicated when only gross measurement is desired. However TPS is an objective and reliable method für testing the effects of medication on prostate carcinomas.

Adenocarcinoma↗
PubMedDate not supplied

[The urinary excretion of pregnanediol during pregnancy determined by gas-liquid chromatography. I. Its evolution throughout the normal and pathological pregnancy (author's transl)].

Employing the technique described by Van Kampen and Anker, modified by Macarulla et al., 180 pregnant women have been studied (66 normals and 114 with different pathology: infertility, toxemia, diabetes, Rh isoinmunization, gemelar pregnancy and abortions), taking 319 determinations of pregnanediol in 24 hours urine samples. The analysis of the results show in normal pregnancy a progressive increase of the urinary pregnanediol from the beginning of gestation, this increase being more intense from the 20th week, reaching the maximum value in the 37th week and from this point descending slowly. In patients with toxemia, the values of pregnanediol (in the majority of the cases) are decreased, while in pregnant women with antecedents of infertility are increased from the 36th week of pregnancy, although they had protective treatment from first months of pregnancy. No manifest deviations of urinary pregnanediol from the normal values exist in diabetic pregnant women, Rb isoinmunization or gemelar pregnancies. In aborted pregnancies the pregnanediol values are markedly decreased without a tendency to increase, contrary to the threats of abortion in full-term pregnancies.

Chromatography, Gas↗
PubMedDate not supplied

[The urinary excretion of pregnanediol during pregnancy determined by gas-liquid chromatography. II. Its relation with other parameters controling pregnancy (author's transl)].

The relation between the urinary pregnanediol determined by gas-liquid chromatography during pregnancy, with ultrasonic findings (biparietal diameter, thickness and echorrefringency of the placenta and the appreciated quantity of amniotic fluid), with biochemical parameters of control of pregnancy (beta-glucoronidase, total and thermostable alkaline phosphatase), with amnioscopic findings, and with several studied parameters of the amniotic fluid by amniocentesis, were studied. A good relation exists with the parameters which denote placentary insufficiency and fetal risk (irregularity in the homogeneity of the placenta, elevation of the total and thermostable alkaline phosphatase, positive amnioscopy) and also with those that are related with fetal maturity (biparietal diameter, shake test, organge cells, creatinine in amniotic fluid, etc.). These results indicate that the determination of urinary pregnanediol can be one of the tests controlling the normal and pathological pregnancies, being useful in the detection of fetal risk and the diagnosis of the intrauterine fetal maturity.

Amniotic Fluid↗
PubMedDate not supplied

[The urinary excretion of pregnanediol during pregnancy determined by gas-liquid chromatography. III. Its relation with the obstetric results (author's transl)].

269 determinations of urinary pregnanediol by gas-liquid chromatography were made in 140 patients during pregnancy. A relation between the pregnandioluria and the fetal results (adequacy of the weight to gestational age, Apgar score at one and five minutes of birth, umbilical artery blood PH and perinatal mortality) as well as the global evaluation of the placenta (macroscopic aspect, vascular index of Kawai et al. and Scott and Jordan index) was studied. The results show that in the cases with fetal pathology (small for date, depression, acidosis, perinatal death) as well as in the cases with placental pathology, the values of pregnanediol were significantly decreased from the first months of pregnancy, which indicate that the placental insufficiency is a very precoz chronic process and on the other hand, that the determination of urinary pregnanediol is a good method for its detection.

Apgar Score↗
PubMedDate not supplied

[Influence of blood pressure profile on erythropoietin levels in diabetics].

UNLABELLED: The purpose of this study was to investigate the relationships between 24-h BP profil and erythropoietin level in diabetics. PATIENTS AND METHODS: This study included 58 patients (26 women and 32 men, mean age: 58.7 +/- 14.6 yrs, diabetes duration: 16 +/- 11.2 yrs). Patients were divided by 24 hrs ABPM into 2 groups, one in which night-time pressures dipped by more than 10% (dippers, n = 16) and the other in which pressures dipped by less than 10% (non-dippers, n = 42) when compared to daytime pressures. Haemoglobin (Hb) and erythropoietin (EPO) levels where compared between diabetics and a control group (n = 110) and between dippers and non-dippers. RESULTS: Hb concentration of diabetics was significantly lower than those of control subjects (13.5 +/- 1.5 vs 14.5 +/- 1 g/dL; p < 0.0001) but EPO levels did not differ from significant manner between these two groups. EPO concentrations were lower in dippers than in control subjects (13.7 +/- 5.4 vs 17.9 +/- 5 mU/mL; p < 0.01), but there was not significant difference in Hb levels. Non-dippers had a Hb level lower than dippers (13.1 +/- 1.5 vs 14.6 +/- 1.1 g/dL, p < 0.0001), but EPO concentrations did not differ from significant manner. Hb was correlated with between daytime and night-time BP difference (SBP: r = 0.262; p < 0.05 and DBP: r = 0.396; p < 0.002). Hb was negatively correlated with albumin excretion rate (r = -0.335, p < 0.01) and with creatinine level (r = -0.419: p < 0.001). CONCLUSION: These data indicated that EPO production could be impaired in diabetics with abnormal diurnal BP variation. Nephropathy and cardiac autonomic dysfunction could explain these results.

Adult↗
PubMedDate not supplied

The influence of polymer concentration on the 5-fluorouracil release rate from carbopol hydrogels.

5-Fluorouracil (5-FU) release kinetics from Carbopol 940 hydrogels prepared at pH 5.5 and five different polymer concentrations (0.0010, 0.0015, 0.0020, 0.0025 and 0.0030 w/w) were determined using Franz diffusion cells. Higuchi's equation for release from solutions was used to calculate the diffusion coefficients of 5-FU in the hydrogels. An empirical equation was obtained for the estimation of diffusivity of 5-FU as a function of polymer concentration, which from a practical view point can be considered useful in preformulation studies. Furthermore, the values of viscosity for all hydrogels assayed were determined. The diffusivity-viscosity relationship resembles the Stokes-Einstein equation for small solutes in liquid phases and provides a factor indicative of additional resistance offered by the gelling agent for drug diffusion.

Acrylic Resins↗