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Biomedical subjects

T Lopez

Publications and source records attributed to T Lopez.

At least 37 records · Page 2Linked to original sources
PubMed1991

Neuropathological effects and deaths of cattle and sheep in Argentina from Phalaris angusta.

Neuropathological disorders and mortality occurred in cattle and sheep grazing P angusta. This native plant of South America is frequently found as a good quality component of natural pastures. Cattle and sheep feeding in pastures where P angusta was dominant started dying or showing signs 3 to 5 d after rain-falls started following a period of drought. Some animals died suddenly, while others nervous effects( incoordination, inability to walk normal, recumbency) and death for up to 2 w after the beginning of the signs. Postmortem findings were bilaterally symmetrical, greenish pigmented areas in the grey matter of the brain stem and diencephalon. A greenish tinge was also noted between the cortex and the medulla of the kidneys. Granules of a brown pigment were noted within the cytoplasm of neurons. An alkaloid substance was detected in the plant. Morbidity was 2.3 to 10.5% in herds B and A, and 0 to 3.4% in flocks D and C, respectively. Mortality was 0.8 to 1.0% in herds B and C, and 3.4 to 11.7% in flocks D and C, respectively. P angusta behaves, in terms of toxicity, as other Phalaris spp. Its widespread distribution in areas of extensive grazing poses a threat to cattle and sheep production in Argentina.

Alkaloids↗
PubMed1991

An outbreak of Vicia villosa (hairy vetch) poisoning in grazing Aberdeen Angus bulls in Argentina.

Vicia villosa (hairy vetch) is used as a forage source in some cattle-producing areas in Argentina. The plant had no previous reports of toxicity in this country. A herd of 33 Aberdeen Angus bulls grazed during 20 days in October on a pasture composed mainly of hairy vetch. Eight animals developed conjunctivitis, rinitis, dermatitis, loss of hair and fever. All of them died within 15 d after the development of signs with a marked loss of body condition. No more animals became sick 5 d after the removal of the herd from the pasture. Serum parameters tested (calcium, phosphorus, magnesium, GOT, alfa-GT and bilirubin) enlarged liver and spleen, generalized hemorrhage in the abomasum, dilated kidneys and multiple pale areas on the heart. Severe necrotizing granulomatous myocarditis, interstitial nephritis, and necrotizing cholangitis were the most striking microscopic changes. Close observation of animals feeding on pastures in which V villosa is dominant is the only prevention.

Animals↗
PubMed1991

[Carotid thromboendarterectomy. Comparison of two anesthesiologic techniques].

The authors have examined two homogeneous groups of patients suffering from "carotid stenosis", operated by TEAC with two different techniques of anaesthesia: general and local-regional (block). Neurological and cardiovascular complications have been recorded in pre and post-operative period. The results analysed statistically with the Pearson test, were homogeneous. However the authors, on the basis of their experience, prefer local-regional (block) anaesthesia for good haemodynamic stability and a better neurologic control. Moreover the block anaesthesia was better in patients.

Aged↗
PubMed1990

Percent reduction in blood urea concentration during dialysis estimates Kt/V in a simple and accurate way.

Urea Kt/V is an accurate tool to estimate the adequacy of hemodialysis (HD) therapy; however, the current methods of calculating Kt/V are too complex for routine clinical use and require great care in order to avoid major inaccuracies. As percent reduction in blood urea concentration during dialysis (PRU) is a function of dialyzer urea clearance, length of dialysis, and urea distribution volume of the patient, it might correlate with Kt/V. Thus, analyzing retrospectively data of 78 studies, we found that the following linear regression equation existed between Kt/V values calculated by means of direct dialysis quantification (DDQ) and PRU values: Kt/V = 0.023 x PRU - 0.284 (r = 0.92). Furthermore, a good correlation existed between Kt/V values measured both by means of DDQ and of the classical algorithm (CA) of the urea kinetic model (UKM) (r = 0.98). Then, a prospective study was started in which 145 Kt/V values calculated by means of the above equation were correlated with the corresponding ones computed by means of a modified algorithm (MA) of UKM, perfectly fitting those generated by CA of UKM. Although the relationship was exponential, it was linear in the clinically important range of PRU between 40% and 70%, corresponding to a Kt/V between 0.64 and 1.33. Furthermore, an excellent correlation (r = 0.96) and no statistically significant difference existed in this range between the two series.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1990

Consumption of food and nutrients by infants in Huascar (Lima), Peru.

Consumption of breast milk, liquids, and foods by 131 poor Peruvian infants was measured on 1661 child-days of observation during their first year of life. Breast-milk intake was estimated by 12-h test-weighing; macronutrients were analyzed in samples of milk. Other foods and liquids were weighed at preparation and consumption; nutrient contents were estimated from food composition tables. Mean energy intakes increased with age but declined from 95% to 78% of recommended amounts during the year. Mean protein intakes were generally above recommended amounts but more than one-third of infants received less than 80% of the suggested safe intakes in the second (6-mo) semester. Breast milk was the major source of energy and protein during the first semester. Breast milk and cow milk together contributed more than half the energy and protein during the second 6 mo, when cereals were also an important source of energy and protein. Mean intakes of calcium, thiamin, and ascorbic acid were less than recommended at some ages but mean intakes of other selected micronutrients exceeded recommendations.

Age Factors↗
PubMed1990

A modified algorithm of the single pool urea kinetic model.

Urea Kt/V, calculated according to the variable volume single pool urea kinetic model (UKM), has been accepted as the yardstick reflecting the adequacy of haemodialysis therapy. However, the classical algorithm of UKM requires great care in dialyser urea clearance (K) measurement in order to avoid major inaccuracies in estimating the urea distribution volume (V). Thus, we suggest a modified algorithm of UKM which avoids the measurement of K. It assumes an arbitrary V value and then calculates kinetically K as a function of the assumed V value. The rationale of the modified algorithm can be derived from the knowledge that the classical algorithm imposes a proportionality ration between K and V: given a particular set of data, a change in the attributed value of K leads to a proportional change in the calculated V value, so that the ratio K/V remains nearly constant. Aims of the study were (1) to validate the modified algorithm by comparing the resulting Kt/V and normalised protein catabolic rate (NPCR) values with the homologous ones obtained using the classical algorithm in a group of 33 patients on thrice-weekly haemodialysis; plasma water urea concentrations were used with the classical algorithm (CApw) and the modified algorithm (MApw); and (2) to verify the possibility of using plasma urea concentrations with the modified algorithm (MAp) instead of the more rigorous plasma water concentrations. NPCR (g/kg per day) was 1.33 +/- 0.05 in CApw, 1.29 +/- 0.05 in MApw and 1.28 +/- 0.04 in MAp. Kt/V was 1.27 +/- 0.03 in CApw, 1.25 +/- 0.03 in MApw and 1.26 +/- 0.03 in MAp.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1989

The relationship between knowledge about acquired immunodeficiency syndrome and the implementation of universal precautions by registered nurses.

The relationship between the level of knowledge of registered nurses (RNs) concerning acquired immunodeficiency syndrome (AIDS)-related issues and the practical observance of universal precautions was studied. It was hypothesized that the more knowledge a nurse has concerning AIDS the more likely he or she is to implement universal precautions. All registered nurses who have direct patient contact (N = 400) and are employed at a Northeastern teaching medical center, were provided a packet of three questionnaires and encouraged to participate. Two hundred thirteen (53%) RNs returned completed questionnaires. Subgroups were examined for trends relating such parameters as age and the amount of AIDS knowledge, using analysis of variance. The major hypothesis was tested by correlating the overall scores for AIDS knowledge and the implementation score. Results indicated no relationship between knowledge and the implementation of universal precautions (r = -0.12). When evaluating scores according to work areas, those subjects with higher knowledge scores had lower practice scores. Other demographic variables showed no influence on either knowledge or implementation scores as measured by this study. Further study is needed to understand what factors will motivate RNs to implement universal precautions.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Amniotic fluid embolism associated with castor oil ingestion.

We report a case of an amniotic fluid embolism (AFE) causing a cardiorespiratory arrest associated temporally with ingestion of castor oil in a full-term normal pregnancy. Risk factors usually associated with AFE were not found in this patient.

Adult↗
PubMed1987

Estrogenic effect of phenol red in MCF-7 cells is achieved through activation of estrogen receptor by interacting with a site distinct from the steroid binding site.

MCF-7 cells serially subcultured in media containing phenol red show poor stimulation of progesterone receptor (PR) synthesis in response to estradiol compared to cells grown in phenol red-free media. Phenol red, when added to cytosol, did not compete with [3H]estradiol for estrogen binding sites in concentrations ranging from 2 microM-1 mM. However 25 microM of the dye was sufficient to increase nuclear translocation of estrogen receptor (ER) in the intact cell. Phenol red activates cytoplasmic ER as indicated by DNA-cellulose binding studies. When cells grown in phenol red-free medium were exposed to phenol red for 48 h, PR levels increased in a dose dependent manner. From these data, it may be concluded that phenol red causes estrogenic effect in MCF-7 cells through activation of cytoplasmic receptor by interacting at a site distinct from the steroid binding site.

Binding Sites↗
PubMed1987

Are estrogen receptors cytoplasmic or nuclear? Some immunocytochemical and biochemical studies.

The subcellular localization of estradiol receptor (ER) has been examined using various experimental approaches. Immunocytochemical studies using the monoclonal antibody JS 34/32, raised against calf uterine cytosolic ER, yielded only equivocal results. In general, cells and tissues pretreated with estradiol showed positive immunostaining in the nuclei whereas those not exposed to the steroid did not show any staining. Nuclear translocation of ER was examined in intact MCF-7 cells using compounds which are known to influence receptor activation. When MCF-7 cells were exposed to molybdate (20 mM), nuclear translocation was completely inhibited while dithiothreitol (20 mM), dibutyryl cAMP (1 microM) and dibutyryl cGMP (1 microM) increased the translocation 2-3-fold. Phenol red, at the range of concentrations generally used in tissue culture media, also increased translocation. The physiological validity of such translocation was examined using cellular progesterone receptor (PR) synthesis as a specific parameter. When MCF-7 cells were grown in media containing phenol red for 48 h, the PR synthesis increased significantly. We further examined whether cytoskeletal proteins are involved in the translocation of ER. Colchicine, an inhibitor of microtubule assembly, inhibited translocation of ER in MCF-7 cells at 1-10 microM. PR synthesis was also inhibited by colchicine in a dose-dependent manner. It may be concluded from these and other published data that ER may not be located at all times in a single subcellular compartment but may rather exist in a dynamic equilibrium between the plasma membrane, cytoplasm and nucleus.

Antibodies, Monoclonal↗
PubMed1981

Effects of exercise on the biochemical aging of mammalian myocardium. II. Creatine phosphokinase.

Male Fischer 344 rats from a long inbred colony (by brother-sister mating) were subjected to moderate (forced swimming) physical activity on a regular basis, beginning at 3 weeks following weaning. Normally caged, sedentary littermates were employed as controls at each age level. Exercised animals showed a greater total ventricular mass and correspondingly lower body weight, and the heart to body weight ratio for experimental animals about 25% higher at all ages, beginning at 3 months following onset of exercise. Finally, the specific activity of myocardial creatine phosphokinase was consistently higher for the exercised animals, beginning at 3 months of age and through 16 months of such exercise. These data support previous findings from this laboratory, as well as by others, that long-term moderate exercise begun early in life has a continuing, beneficial effect on the mammalian heart, both at the gross functional and intracellular biochemical levels.

Aging↗
PubMed1981

Effects of exercise on the biochemical aging of mammalian myocardium. I. Actomyosin ATPase.

Male Fischer 344 rats were subjected to regular forced exercise beginning at weaning and continued until sacrificed at ages ranging from 2 to 18 months. Littermates served as sedentary controls. At all ages examined, the exercised animals had greater heart and lower body weights. Actomyosin was isolated from the myocardium and the ATPase activity of the contractile protein preparation was measured. Only the sedentary animals exhibited an age-related loss in enzyme activity. The physically trained animals had substantially higher ATPase specific activity than the controls at all ages. This difference in ATPase specific activity may be the result of the synthesis of different isozymic forms of myosin or changes in the regulatory proteins of actomyosin (tropomyosin and troponin). It is suggested that lifelong regular exercise may alter the known biochemical changes in the heart muscle that relate to declining cardiac function.

Actomyosin↗
PubMed1981

Age-related activity changes in actomyosin ATPase and arginine phosphokinase in male Drosophila melanogaster Meig.

The specific activity of each of the two enzymes primarily concerned with the energy metabolism of flight muscle contraction was determined in male Drosophila melanogaster, from emergence through 5 weeks postemergence. Ca++-activated actomyosin ATPase activity rose rapidly from a minimum at emergence to a peak level at 4-5 days, falling gradually thereafter to a minimum level at 10-11 days postemergence, with no change thereafter. Arginine phosphokinase activity rose more gradually to a maximum at 11-12 days postemergence and then fell slowly to a minimum at 18-19 days. These data represent a sequential pattern of biochemical changes similar to those previously observed in other dipteran species, confirming the primary role of a genetic program for maturation and senescence of flight ability in holometabolous adult insects at the functional and underlying cellular, biochemical levels.

Actomyosin↗
PubMed1981

[Comparison of acetate and bicarbonate in hemodialytic treatment. Echocardiographic and polycardiographic study of the left ventricle].

During standard haemodialysis, cause of calcium and magnesium insoluble salts formation, the bicarbonate as a buffer has been replaced by the more soluble and stable acetate. But the new and more efficient dialytic systems cause an increase of intradyalitic bicarbonate loss and acetate gain the latter, by a direct calcium binding or by calcium displacement from the active sites, has been believed to be responsible for vasodilatation and myocardial contractility depression. Aim of this study is to verify if the bicarbonate dialysis versus acetate dialysis modifies left ventricular performance, investigated by non invasive tools (systolic time index and echocardiography). This work deals with twelve patients undergoing standard haemodialysis (three times a week) since 28 months on the average. Echocardiographic and systolic time index study was performed before and after the acetate dialysis and before and after the tenth bicarbonate dialysis observing the same interdialytic period. The echo has shown improvement concerning the fractional shortening (P less than 0.025) and the cardiac output (P less than 0.05) and only before the tenth bicarbonate dialysis. Systolic time index data have shown reduction of the ratio PEP/LVET (P less than 0.05) and LVET less negative than after acetate only in the end of the tenth bicarbonate dialysis (P less than 0.05). These results seem point out left ventricular performance improvement in accordance with the decrease of clinical intradialytic (nausea, vomiting, and hypotension) and interdialytic troubles (headache, asthenia and washed-out feeling) probably due to the bicarbonate more effective as a buffer in the acid-base and electrolytic balance.

Acetates↗
PubMed1980

Changes with age of myocardial creatine phosphokinase in the male Fischer rat.

Myocardial creatine phosphokinase (CPK) was extracted from crushed tissue in 0.01 M Tris buffer at pH 9.0 and purified by successive ammonium chloride and ethanol precipitations. The CPK activity was estimated by measuring the rate of phosphocreatine formation by the transphosphorylation of creatine by ATP. There was a slight rise in CPK activity from 1 to 2 months of age. Thereafter, there was a progressive fall in the CPK activity of 14% by 7-9 months of age, 20% by about one year of age, and 25% by 16-24 months of age. These data indicate that, with advancing age, there is an inability to rapidly restore adequate cellular levels of the high-energy substrate ATP during muscular contraction. Since the loss with age of myocardial CPK parallels a strong biochemical correlate for known declining cardiac function in aging mammals, including man.

Actomyosin↗