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D Santos

Publications and source records attributed to D Santos.

At least 37 records · Page 2Linked to original sources
PubMed1992

nov: a new genetic locus that affects the response of Escherichia coli K-12 to novobiocin.

We have identified a new gene locus (nov) affecting the resistance of Escherichia coli K-12 to novobiocin. The gene also affects, although to a lesser extent, tolerance to another gyrase inhibitor coumermycin. Transductional and complementation analysis show that nov is located between att phi 80 and the osmZ (hns) genes at minute 27 of the E. coli K-12 genetic map. In standard laboratory strains of E. coli K-12 nov exists at least in two allelic forms.

Alleles↗
PubMed1991

[Nephrotic syndrome in children. Retrospective study at a concentration hospital].

In order to evaluate the usefulness of certain clinical and paraclinical characteristics to be able to discriminate the minimal change disease (MCD) from other histopathological lesions associated with the nephrotic syndrome (NS), the clinical charts of 31 patients were reviewed and relevant data were analyzed. Those patients with no history of biopsy and those with documented MCD through biopsy, were placed in one group (MCD = 25) and the rest as others (others = 6). None of the clinical or paraclinical indicators analyzed showed significant differences between either group. In the MCD group, 76% of the patients entered remission after receiving steroid treatment, while none of the others entered remission. The magnitude of the proteinuria, hypoalbuminemia, hypercholesterolemia, and the presence of hematuria, hypertension or hyperazoemia, were not useful to discriminate those with MCD from other lesions. The response to treatment with prednisone was the most useful data to differentiate the groups.

Child↗
PubMed1990

[Histocompatibility antigens and acute vascular purpura].

INTRODUCTION: Some kidney diseases are associated to HLA antigens. Nyulassy found an increase in HLA-B35 in patients with Henoch-Schönlein's purpura suffering nephritis (HSP-N). Our study searched for associations of HLA antigens and anaphylactoid purpura nephritis in Mexican mestizo patients. MATERIAL AND METHODS: HLA-A,B, and C antigens were detected by two-step microcytotoxicity in 22 patients with HSP-N and compared to those of 665 healthy subjects of the same ethnic background. RESULTS: A significant association was found between HSP-N and HLA-Aw19 single (pc less than 0.05) or in haplotype form (Aw19-B35) (pc less than 0.005). HLA B35 alone was associated to HSP-N but only at non corrected level (pc less than 0.05). DISCUSSION: The significant association between HLA-Aw19 and Aw19-B35 and HSP-N may indicate a risk factor in Mexican mestizo patients to develop this case.

Adolescent↗
PubMed1988

Comparison of methods of carbamazepine dosage, individualization in epileptic patients.

The aim of the present work was to analyse the predictive capacity of different optimization methods for carbamazepine dosage regimens according to population pharmacokinetic parameters and/or serum levels data. Calculations were performed using a multiple non-linear regression program (MULTI 2 BAYES) with two different options: (a) using the ordinary least squares methods and (b) the least squares method based on the Bayesian algorithm. The predictive capacity of the three methods was analysed comparing the serum levels values in patients predicted by each method and those observed later. The performance obtained was poor and even unacceptable when dosage prediction was based on the mean parameters of the population studied (Method A) and when only one data point relating to the serum carbamazepine levels was available (Method B). When two serum levels data were used the standard deviation of the mean prediction error was only clinically acceptable when Bayesian non-linear regression was applied (Method C). When the number of serum levels data points was 3 or 4 the errors were acceptable from a clinical point of view and no significant differences could be found between the use of the simple and Bayesian version at the same level of information.

Adolescent↗
PubMed1987

The construction and use of a human-mouse myeloma analogue suitable for the routine production of hybridomas secreting human monoclonal antibodies.

A human-mouse myeloma analogue termed HMMA2.11TG/O was constructed by fusion of the mouse myeloma cell line P3x63Ag8.653, a mutant derivative of MOPC21, with bone marrow mononuclear cells from a patients with IgA myeloma. The HMMA2.11TG/O cell line is resistant to 6-thioguanine and ouabain and sensitive to HAT. The cell line secretes no detectable immunoglobulin and has a hybrid karyotype and cell surface phenotype. An average fusion efficiency for growth of hybridomas of 1/17,000 fused cells was obtained in fusions with human peripheral blood mononuclear cells (PBM), Pokeweed Mitogen (PWM) stimulated PBM, and Epstein-Barr Virus (EBV) transformed polyclonal B cell lines. Over 75% of hybrids secrete detectable immunoglobulin and the cloning efficiency of the hybrids at 1 cell/well averages 25%. Antibody secreting cloned hybridoma cell lines were obtained by fusion directly with PBM from an immunized volunteer and by fusion with in vitro, secondarily immunized, EBV transformed polyclonal cell lines. Five hybridomas secreting human monoclonal IgM anti-tetanus antibodies and 2 secreting human monoclonal IgG anti-tetanus antibodies were selected and cloned from 6 fusions performed specifically for anti-tetanus antibody. Immunoglobulin and antibody secretion by cloned hybrids has been stable for 5-10 months at present. Immunoglobulin and antibody secretion in routine cultures passaged every 3-4 days has been 8-42 micrograms/ml. This human-mouse myeloma analogue should prove useful for the routine production of human monoclonal antibodies.

Animals↗
PubMed1984

Bupivacaine protein binding in the term parturient: effects of lactic acidosis.

The effects of lactic acidosis on bupivacaine serum protein binding was studied in a group of term parturients and a group of nonpregnant female control subjects. Groups were matched in age and health. Distribution characteristics of bupivacaine in pregnancy were determined. Bupivacaine protein binding was best characterized by the model for two classes of binding sites in all studies. The parturients exhibited a lower capacity for the high-affinity, low-capacity (alpha 1-acid glycoprotein) site and higher affinity for the low-affinity, high-capacity (albumin) site. Lactic acidosis decreased the affinity constant for the high-affinity, low-capacity site in the control group but did not change binding characteristics in the parturients. Free concentration of bupivacaine (Cu) was elevated at low total bupivacaine concentrations (Ct) (less than 10 micrograms/ml). No differences in Cu were detected at concentrations in the cardiotoxic range (greater than 20 micrograms/ml). The Cu values predicted by the estimated binding parameters from in vitro experiments were compared with actual Cu measured in nine parturients at delivery; they correlated significantly (r = 0.94). Distribution changes for bupivacaine in the parturients were consistent with known physiologic changes in body composition associated with pregnancy. Alterations that occur in serum protein binding during pregnancy should not result in increased risk of central nervous system or cardiovascular system toxicity since these alterations do not increase free tissue concentration.

Absorption↗
PubMed1980

Renal function in protein-energy malnutrition.

So far, most studies on renal function in children with advanced protein-energy malnutrition have shown an impairment of glomerular filtration rate and renal plasma flow, as well as diminished ability to excrete an acid load and a concentrated urine. Investigation of these functions in eight marasmic infants and eight children with kwashiorkor once they were free of obvious infections and acute electrolyte disturbances has shown a practically normal renal performance.

Child, Preschool↗
PubMed1979

Effect of hemodialysis on glucose tolerance in children with chronic renal failure.

Five uremic (7.0 - 15.2 years), non-dialyzed children treated medically (group 1) had an intravenous glucose tolerance test (0.5 g/kg). Blood samples were obtained at frequent intervals and duplicate determinations of plasma glucose (glucose-oxidase method on Somogyi-Nelson protein-free filtrates), insulin and free fatty acids were performed. The same study was performed in eleven children (12.3 - 18.0 years) with chronic renal failure undergoing long-term hemodialysis (group 2), before and two hours after dialysis. Results were compared to a group (group 3) of eight healthy children (7.5 -- 17.5 years). In group 1 a "normal" insulin response was observed in the presence of hyperglycemia and the plasma glucose clearance was in the diabetic range. Twice weekly hemodialysis produced no beneficial acute effects on group 2, based on absolute glucose values or plasma glucose clearance rates, on groups as well as on individual basis; however, a clear hyperinsulinemia was present which was of even higher magnitude three and six months after the initial study. These results demonstrated that chronic hemodialysis had no beneficial acute effects on plasma glucose concentration or plasma glucose clearance rate. However, it may have obvious long term beneficial effects on glucose tolerance by enhancing pancreatic insulin release (to overcome peripheral insulin resistance) to such an extent as to maintain a normal carbohydrate tolerance.

Adolescent↗
PubMed1975

Isolation and characterization of a new temperature-sensitive cell division mutant of Escherichia coli K-12.

A new temperature-sensitive mutant strain of Escherichia coli K-12 which forms filaments at 42 C has been described. The mutant, Y16, maintained growth and deoxyribonucleic acid synthesis at 42 C. The resulting multinucleate filaments gradually lost their viability at 42 C but could be recovered, even after 240 min of incubation, upon return to 30 C. Septation was resumed and growth was promptly re-established at normal rates. Recovery still took place in the presence of chloramphenicol added to the culture at the time of temperature shift from 42 to 30 C. A study has been made of the effects of adenine and various nucleosides on cultures of strain Y16 as compared with another filament-forming mutant, T44 tif-. Adenine (75 mug/ml), known to promote filamentation of strain T44 tif-, prevented the development of filaments and the loss of viability in cultures of Y16. Recovery of septation after temperature shift in cultures containing adenine presented a pattern similar to that found with the adenine-less cultures. Protection afforded by adenine at 42 C could be reversed by the addition of guanosine plus cytidine (100 mug/ml each). The effects of high concentrations of adenine and nucleosides on strain Y16 thus are the reverse of those observed with mutant T44 tif-. However, whereas tif-1 mutation promotes prophage induction at restrictive temperatures, no modification could be detected in the process of prophage induction in cultures of the lambda-lysogenic derivative of Y16 at 42 C, be it spontaneous or ultraviolet-mediated induction. The osmolarity increase afforded by 1% NaCl added to the medium did not alter the phenotype characteristics of strain Y16. The mutation has been mapped between argG and bgl. A close linkage has been observed between ftsH and argG, thereby locating the new mutation near 61 min on the map of E. coli chromosome, a previously undescribed region involved in cell division. The evidence reported indicates that strain Y16 differs in several respects from the already descirbed strains of the same class.

Adenine↗
PubMed1975

[Hypercoagulability in the nephrotic syndrome of children].

Several coagulation factors were studied in twenty children less than 16 years old, bearing nephrotic syndrome. Four of them were in remission. In nephrotic syndrome there is hypercoagulability. Coagulations factors such as fibrinogen, platelet factor III, prothrombin time, and factor V are markedly altered, and to a lesser degree, total number of platelets. Fibrin degradation products factors II, VII, X and VIII are also altered. During remission, all of them improve or become normal. In no case fibrin breakdown products were found in the blood. However, if found in urine, they would be considered as a pronostic index in nephropaties. Although etiologic factors remain unknown for most of the above-mentioned alterations, increased fibrinogen synthesis, decreased fibrinolytic plasms activity and renal damage have been demonstrated.

Adolescent↗