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Biomedical subjects

G Pereira

Publications and source records attributed to G Pereira.

At least 37 records · Page 2Linked to original sources
PubMed1996

The spindle pole body component Spc98p interacts with the gamma-tubulin-like Tub4p of Saccharomyces cerevisiae at the sites of microtubule attachment.

Tub4p is a novel tubulin found in Saccharomyces cerevisiae. It most resembles gamma-tubulin and, like it, is localized to the yeast microtubule organizing centre, the spindle pole body (SPB). In this paper we report the identification of SPC98 as a dosage-dependent suppressor of the conditional lethal tub4-1 allele. SPC98 encodes an SPB component of 98 kDa which is identical to the previously described 90 kDa SPB protein. Strong overexpression of SPC98 is toxic, causing cells to arrest with a large bud, defective microtubule structures, undivided nucleus and replicated DNA. The toxicity of SPC98 overexpression was relieved by co-overexpression of TUB4. Further evidence for an interaction between Tub4p and Spc98p came from the synthetic toxicity of tub4-1 and spc98-1 alleles, the dosage-dependent suppression of spc98-4 by TUB4, the binding of Tub4p to Spc98p in the two-hybrid system and the co-immunoprecipitation of Tub4p and Spc98p. In addition, Spc98-1p is defective in its interaction with Tub4p in the two-hybrid system. We suggest a model in which Tub4p and Spc98p form a complex involved in microtubule organization by the SPB.

Amino Acid Sequence↗
PubMed1995

Multiple overlapping positions of nucleosomes with single in vivo rotational setting in the Hansenula polymorpha RNA polymerase II MOX promoter.

In vivo nucleotide-level mapping of nucleosomes in the promoter of the methanol oxidase (MOX) gene in the yeast Hansenula polymorpha is reported. The 4 nucleosomes analyzed are organized in families; they localize in alternative positions along a unique rotational phase, and the linker regions can be occupied by alternative nucleosomes. This organization underscores a substantial freedom of choice by histone octamers when nucleating on a promoter region.

Alcohol Oxidoreductases↗
PubMed1994

Role of positive end-expiratory pressure changes on functional residual capacity in surfactant treated preterm infants.

Both surfactant replacement and positive end-expiratory pressure (PEEP) increase lung volume in infants with respiratory distress syndrome (RDS). We measured pulmonary mechanics and functional residual capacity (FRC) in 21 preterm infants with RDS, > 48 hr post-surfactant therapy (BW, 1,168 +/- 441 g; GA, 28.3 +/- 2.8 weeks; postnatal age, 3-7 days). A non-linear but significant increase in mean FRC was noted as PEEP increased from 2 to 5 cmH2O: 18.4 +/- 4.7 mL/kg at 2 cmH2O; 19.7 +/- 4.3 mL at 3 cmH2O; 22.6 +/- 5.5 ml/kg at 4 cmH2O; and 26.2 +/- 6.2 mL/kg at 5 cmH2O (P < 0.01). Because of the synergistic combined effect on lung volume, surfactant treated neonates should be weaned cautiously from PEEP during ventilatory management. Our study also suggests that the occurrence of inadvertent end-distending pressure during FRC measurement in the ventilated neonate lead to erroneous results.

Female↗
PubMed1991

Effect of the in vitro ageing on the restriction of sheep erythrocyte lysis by horse serum.

Fresh sheep erythrocytes are resistant to lysis by horse serum but gradually became susceptible to this source of complement after storage (ageing) in the blood at 4 degrees C. This occurs faster when the fresh cells are stored in isotonic buffer. The supernatant of the buffer/red cell suspension stored at 4 degrees C for 10-15 days restrict lysis by horse serum when incubated back at 37 degrees C or 43 degrees C with the 'aged' sheep cells or fresh guinea pig red cells. In assays using fresh guinea pig erythrocytes this effect is described by reincubation of the cells in buffer, and is specific to horse serum when compared to human serum.

Animals↗
PubMed1988

Nutritional and metabolic profile of children with epidermolysis bullosa.

The clinical features of epidermolysis bullosa (EB) include oral, pharyngeal, gastrointestinal, and total-body blistering. This results in the potential for decreased oral intake, malabsorption, anemia, and depressed visceral protein stores, and a multifactorial etiology for the development of malnutrition and growth retardation. Thus, it was the purpose of this study to document the nutritional and metabolic profile of seven children with junctional or recessive dystrophic EB as compared to seven age- and sex-matched controls. Each child underwent a comprehensive nutritional assessment, including evaluation of anthropometric, dietary, and biochemical values and determination of resting energy expenditures. This study demonstrated that subjects with EB are statistically different for all anthropometric values studied and represent a population suffering from the effects of acute and chronic malnutrition. Nutrient deficiencies were reported for zinc, magnesium, calcium, potassium, and iron; vitamines A, D, E, B1, B12, and B6; protein, and calories. Comparison of laboratory values revealed significantly lower values for hemoglobin, hematocrit, and zinc. This research illustrates the magnitude of the growth deficits, and nutrient and biochemical deficiencies present in children with EB. The results provide a strong argument for the value of nutritional assessment and intervention and their potential impact in this population. Optimizing nutritional status may be one viable method of improving the morbidity and mortality associated with the disease and ultimately improving the overall quality of life.

Anthropometry↗
PubMed1984

Differences in the mean fat cell diameter of males between 1 and 48 months of age.

The mean fat cell diameter was determined from measurements of abdominal adipose cells, obtained during inguinal hernia repair, of 126 white and 95 black males ranging in age from 1 through 48 months of age. The mean diameters of black and white subjects did not differ significantly, suggesting that differences in fatness among adults of these two ethnic groups have their origin beyond the age range of this study. The mean fat cell diameter increased through the 6-8 month age group, decreased until the end of the first year, and then levelled off through 48 months of age. Comparison of this curve with those for the triceps, subscapular, abdominal, and suprailiac skinfolds of the same subjects showed generally parallel courses except for the triceps, which continued to increase in size after the means of fat cell diameters and the other skinfolds had levelled off. Our data indicate that changes in body fatness on the trunk at least in the first 4 years of life may be accounted for by changes in fat cell size.

Abdominal Muscles↗
PubMed1984

Urinary excretion of dimethylarginines in premature infants.

Urinary excretion of NG,N'G-dimethylarginine (NG,N'G-Me2Arg) and NG,NG-dimethylarginine (NG,NG-Me2Arg) was measured in premature infants. The NG,N'G-Me2Arg/NG,NG-Me2Arg ratio was much higher in newborn infants than in older children or adults. Linear regression analysis showed a significant negative correlation between the degree of maturity and the excretion of NG,N'G-Me2Arg. A significant direct linear relationship also was found between the excretion of NG,N'G-Me2Arg and the rate of whole body nitrogen flux and of protein synthesis and catabolism. No correlation was found between the excretion of the dimethylarginines and 3-methylhistidine, but the dimethylarginine/3-methylhistidine ratio declined with advancing conceptual age. A direct linear relationship was found between excretion of NG,N'G-Me2Arg and NG,NG-Me2Arg and whole body nonskeletal muscle protein breakdown. No correlation was found between nonskeletal muscle protein catabolism and 3-methylhistidine excretion. We estimate that approximately 0.34 mumole of dimethylarginine are excreted per gram of nonskeletal muscle protein catabolized. Dietary intake did not affect the excretion of either NG,N'G-Me2Arg or NG,NG-Me2Arg. The data suggest that measurement of urinary dimethylarginines might be useful in the nutritional assessment of premature infants.

Adolescent↗
PubMed1983

Prealbumin as a biochemical marker of nutritional adequacy in premature infants.

To determine whether serum prealbumin would be useful in identifying adequacy of protein and calorie intake in premature infants, 17 infants between 26 and 33 weeks gestational age were studied throughout hospitalization. Serial anthropometric measurements, nutritional intake, and serum prealbumin concentrations were correlated. When mean intake of calories and protein was lower than 100 kcal/kg/day and less than 2 gm/kg/day, respectively, there was a significant difference in mean prealbumin values, compared with those in infants with a higher intake (P much less than 0.001). For infants with birth weights of 1000 gm or less, prealbumin correlated with protein intake (r = 0.66) and calorie intake (r = 0.64). In these infants, when protein intake exceeded 2 gm/kg/day, prealbumin concentrations increased to values reported for full-term infants in the first months of life. There was no significant correlation between intake of calories or protein and prealbumin values for infants born weighing greater than 1000 gm. Anthropometric measurements did not correlate with protein or calorie intake. We conclude that prealbumin is a sensitive measure of protein and calorie intake in premature infants, and that the definition of adequate nutrition may be different for premature infants of different birth weights and at various postconceptional ages.

Body Weight↗
PubMed1983

Osteoblasts isolated from mouse calvaria initiate matrix mineralization in culture.

A method is presented for isolating osteoblasts from newborn mouse calvaria without the use of digestive enzymes. The procedure is based on the ability of osteoblasts to migrate from bone onto small glass fragments (Jones, S.J., and A. Boyde, 1977, Cell Tissue Res., 184:179-193). The isolated cells were cultured for up to 14 d in Dulbecco's modified Eagle's medium supplemented with 10% fetal calf serum and 50 micrograms/ml of ascorbic acid. 7-d cultures were incubated for 24 h with [3H]proline. High levels of collagen synthesis relative to total protein were found, as measured by collagenase digestion of medium and cell layer proteins. Analysis of pepsin-digested proteins from the same cultures by SDS PAGE showed that type I collagen was predominantly produced with small amounts of type III and V (alpha 1 chains) collagens. Osteoblasts grown in the presence of beta-glycerophosphate were able to initiate mineral deposition in culture. Electron microscopic analysis of the cultures revealed the presence of needle-shaped apatite-like crystals associated with collagen fibrils and vesicles in the extracellular space. Mouse skin fibroblasts cultured under identical conditions failed to initiate mineralization. Electron histochemical studies revealed the presence of alkaline phosphatase activity, associated with osteoblast membranes, matrix vesicles and on or near collagen fibrils. Thus these isolated osteoblasts retained in culture their unique property of initiating mineralization and therefore represent a model of value for studying the mineralization process in vitro.

Animals↗
PubMed1983

Effects of conceptual age and dietary intake on protein metabolism in premature infants.

Protein turnover was studied in eight premature infants of conceptual age 26-37 weeks. A stochastic model based upon [15N]urea or [15N]ammonia excretion following a single injection of [15N]glycine was used to estimate rates of whole body protein synthesis and catabolism. The urinary 3-methylhistidine/creatinine ratio was determined to differentiate skeletal muscle protein breakdown from total protein catabolism. The rates of whole body protein synthesis ranged from 5.2 to 13.2 g X kg-1 X day-1 and protein catabolism ranged from 4.1 to 12.4 g X kg-1 X day-1. Linear regression analyses of conceptual age versus (a) whole body nitrogen flux, (b) protein synthesis, and (c) protein catabolism showed significant inverse relationships. A similar relationship obtained between conceptual age and the urine 3-methylhistidine/creatinine ratio. Muscle protein breakdown did not vary with conceptual age, but the fraction of whole body protein breakdown derived from muscle protein breakdown increased significantly with advancing maturation. The ratio net tissue protein gain/total body protein synthesis increased significantly with increasing body weight. Net tissue protein gain appeared to be directly related to protein and caloric intake. The ratio of the rate of whole body protein synthesis and protein intake was greatest in the youngest infants and declined with maturation. A similar relationship was not found between the ratio of protein synthesis and caloric intake and the degree of maturity. More than 90% of nitrogen entering the metabolic pool was used for protein synthesis and more than 50% of calories administered were similarly utilized. We conclude that: (a) protein turnover in premature infants is far more rapid than in term infants, children, or adults and is inversely related to conceptual age; (b) muscle protein turnover constitutes a greater fraction of overall turnover with advancing maturity; (c) energy and protein intake affect net tissue protein gain significantly in rapidly growing infants; and (d) the efficiency of protein synthesis as a function of protein intake is higher in the most immature infants.

Body Weight↗
PubMed1983

Fibrinogen degradation products in acute renal failure of the newborn.

Acute parenchymal renal failure (ARF) in the newborn infant has emerged as a major problem since the advent of neonatal intensive care units. Because intravascular and/or intrarenal coagulation may be important in the development of ARF, a prospective study of coagulation was performed on 20 babies with ARF, with particular emphasis on the measurement of fibrinogen degradation products (FDP) in serum and urine. Thirteen babies with respiratory distress syndrome (RDS) and 40 healthy neonates served as controls. Initial serum FDP levels were significantly higher in ARF than in RDS or normals (P less than 0.001); initial urine FDP levels were higher in ARF than in normals (P less than 0.01). Levels of FDP did not differentiate among the various etiologies of ARF. Since initial urine FDP levels are high in normal newborns, serial urine FDP were compared among patient groups and found to be highest in ARF. Initial serum and urine FDP levels could not differentiate among the 11 survivors and 9 nonsurvivors, but FDP levels declined as the duration of ARF (e.g., survival) increased, often antedating the recovery of renal function. We conclude: (1) serum and urine FDP are significantly elevated in most newborns with ARF; (2) factors other than hypoxia may be involved in the pathogenesis of elevated serum FDP in RDS with ARF newborns, indicating the importance of coagulation; (3) serial measurements of serum and urine FDP may be early indicators of recovery of renal function.

Acute Kidney Injury↗
PubMed1978

Ultrastructural localization of cations in the rat pars distalis under various experimental conditions.

Modifications of the pyroantimonate technique were used to localize intracellular sites of bound cations in the pars distalis of normal and hypothyroid rats and in rats with increased levels of plasma calcium. In the normal animal, cations were localized within most intracellular organelles and sometimes on the membranes involved in exocytosis. The amount of bound cations within pituitary intracellular organelles was considerably augmented in rats injected intravenously with calcium chloride. However, in the thyroidectomy cells of hypothyroid rats, the amount of cation precipitate appeared to be selectively increased in the dilated rough endoplasmic reticulum (RER). The calcium chelator, EGTA, and X-ray microprobe analysis revealed the presence of calcium in cation deposits.

Animals↗