摘要:

SummaryFour patients with hereditary glucose phosphate isomerase (GPI) deficiency and their parents have been studied by means of various enzymatic, immunologic, electrophoretic, and stability methods. The four defective mutants enzymes (identified here as “GPI Barcelona,” “GPI Utrecht,” “GPI Nijmegen,” and “GPI Kortrijk”) were antigenically identical with normal enzyme as judged by double immunodiffusion and microcomplement fixation tests. Immunologic specific activity (i.e., the ratio of enzyme activity to antigen concentration) was slightly lowered for three variants (between 60 and 75% of normal). The various methods used allowed us to establish that all of the patients were heterozygous for two different mutated alleles inherited from each parent. One of them was a silent allele which did not seem to code for any enzymatic cross-reacting material; the other mutated gene coded for a structurally modified glucose phosphate isomerase subunit.In two parents heterozygous for a structurally modified gene, only two enzymatic forms were detected, even in the young cells synthesizing actively proteins such as granulocytes: one was the normal homodimer, and the other corresponded to the heterodimer “normal subunit-mutant subunit”; the mutant homodimer was not detected. The assumption that, in these heterozygotes, the mutant subunit dimerized more easily with a normal subunit than with another mutant subunit could be proposed. In contrast, the three expected enzyme forms were detected in the leukocytes from a woman heterozygous for GPI Nijmegen.From these results the defect in activity observed in the patients could be explained in the following way: 50% of the defect was due to the inheritance of a silent gene. The decrease below 50% of the residual activity in red cells was due to the molecular instability of the mutant enzyme associated in three cases (GPI Barcelona, GPI Utrecht, and GPI Kortrijk) with the decreased immunologic specific activity.SpeculationIn spite of the relatively high frequency of the mutations which are responsible for a silent GPI structural gene, GPI deficiency due to the inheritance of two silent genes has never been described. It can be speculated that the homozygous state of such a mutation, which would lead to null enzyme activity in all the tissues, could be lethal. As in most cases of genetic disorders due to silent genes, the nature of the mutation involved is unknown. A deletion, a polar mutation, a structural mutation leading to a highly labile product, or a cis-dominant regulator mutation are the different genetic hypotheses which could be put forward.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryThis study reports a serologic method for the measurement of kidney-derived antigens in the urine of healthy children and of children with renal diseases. Two hundred twenty patients were studied. Four groups were recognized:group A, patients with no evidence of renal disease;group B, patients with past history of active urinary tract infection;group C, patients with active urinary tract infection;group D, patients with other renal diseases.Urinary renal antigen concentration was tested by the complement fixation method, in which titers of antigens in the urine were compared with a standard human renal antigen extract. The distribution of renal antigen concentrations ingroup Cdiffered significantly (P(X2) less than 0.001) from the other three groups. About 85% of patients ingroups A, B, andDhad levels below 0.6 mg/ml, whereas ingroup Conly 53% of patients had similar concentrations. After factoring the results by the urinary concentration of creatinine, 85% of patients ingroup Chad antigen levels above 0.6 mg/ml as opposed to 24%, 44%, and 27% ingroups A, B, andD, respectively. The results of the study are consistent with the assumption that the rate of discharge of renal antigenic material in the urine is accelerated in certain renal diseases.SpeculationTiters of renal antigen in urines of patients with urinary tract infection may differentiate parenchymal disease from lower tract disease. Monitoring of the pattern of renal antigen excretion may provide an index for optimal duration of antibacterial therapy in pyelonephritis.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryPulmonary clearance forStaphylococcus aureushas been examined in two inbred strains of mice with some hereditary alterations resembling cystic fibrosis (CF). These mice were mice with abnormal electrolyte metabolism (DBA/2J-Cri), mice with spontaneous pneumonitis (C57BL/6J-bgJ), and mice without any CF-like alterations (BALB/c).The methods used to produce pulmonary infection were essentially those of Laurenzi and associates adapted as needed for mutant mice. The animals mentioned above were exposed to a finely divided aerosol suspension of a coagulase-positive strain ofS. aureusin phosphate buffer.Immediately after the exposure, half of the animals were killed, and the remaining half were killed 4 hr later. In each experimental unit the mice killed immediately after the exposure were as similar as possible to the mice killed 4 hr later with respect to genotype, age, and sex; some were siblings.The uncleared bacteria (UBR) in 4 hr were 0.20 for the mice without any CF-like alterations (BALB/c) and the C57BL/6J-bg, bg/bggenotypes; 0.28 for C57BL/6J-ftg, +/? genotypes; 0.50 for the DBA/2J-cri, +/? genotypes; and 0.56 forcri/crimice.The number of viable staphylococci found immediately after the aerosol exposure (Co) in the C57BL/6J-bgstrain is significantly lower than the Co of the BALB/c (P< 0.05) and DBA/2J-cristrain (P< 0.01). The latter two did not differ from each other.There was no sex difference with respect to the UBR and Co data. The DBA/2J-cristrain of mice, where thecrimutation first appeared, has a decreased capacity for clearance ofS. aureusby the lung. Together with the other CF-like alterations of thecrimutation, namely failure for the reabsorption of Na+by the parotid duct, high level of Na+in the fur, and CF abnormal serum factor activity in the scrum ofcri/crimice, we suggest that the cribriform degeneration mouse mutant may provide a potential animal model for studying CF.SpeculationThe finding of a mouse mutation with electrolyte alterations and CF-like abnormal scrum activity, similar to the activity found in CF children, in an inbred strain of mice with a decreased bacterial clearance by the lungs, makes these mice very useful for CF studies.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryThis investigation examined factors that affect methylenetetrahydrofolate (methylene-H4PteGlu) reductase activity in cultured human cells. Activity was demonstrable in extracts of cultured normal human skin fibroblasts, amniotic fluid cells, and lymphoblasts. The velocity of the reaction was maximal at pH 6.3 in extracts of all three cell types. Subcellular localization studies indicated that 83–94% of the reductase activity was extranuclear in the three cell types. The reductase activity was not substantially altered by growth of lymphoblasts whether in Eagle's minimum essential medium (MEM) supplemented with homocysteine alone or with additional hydroxocobalamin and folic acid, or in media containing a 5-fold greater concentration of methionine. In normal fibroblasts the methylene-H4PteGlu reductase activity varied little when the confluent cells were exposed to media deficient in or supplemented with varying amounts and combinations of methionine, homocysteine, folic acid, and cobalamin. Under our conditions the addition of purifiedS-adenosylmethionine to give a final concentration of 48 mM in the assay reaction mixture reduced the reductase activity to 38% of control in the fibroblast extract and to 13% of control in the extract of rat liver. This sensitivity to inhibition byS-adenosylmethionine and the lack of response to varied levels of methionine, homocysteine, folic acid, and cobalamin are further evidence that the reductase activities in mammalian liver and fibroblasts are similar.SpeculationCultured human skin fibroblasts and peripheral blood lymphoblasts may provide a useful, convenient system for studying the biochemical-genetic regulation of 5,10-methylene-H4PteGlu reductase activity and, ultimately, of the levels of its folate product, 5-methyl-H4PteGlu.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryMethylenetetrahydrofolate (methylene-H4PteGlu) reductase activities in extracts of both normal and reductase-deficient cells were low and quite variable during the logarithmic phase of growth. Higher activities were detected reproducibly when the cultures were confluent. Methylene-H4PteGlu reductase activities in extracts of fibroblasts from the parents of patientCPwere about half of the level observed in normal control subjects. In fibroblasts from patientCP, the activity was 20% of normal whereas, from patientsLMandBM, the activities were 19% and 14% of normal, respectively. When incubated at 55° in a solution containing all the components of the standard reaction mixture except the 5-methyl-H4PteGlu substrate, the reductase activity in extracts of fibroblasts from two unrelated normal control subjects decreased to 31% and 22%, respectively, of the initial values after 30 min of incubation. In contrast, the reductase in extracts of cells patientCPwas rapidly and exponentially inactivated at 55°. The reductase activity in extracts from patientsLMandBM, the sisters, decreased to 22% and 38%, respectively, of the initial values. In repeated experiments the heat inactivation of reductase activity in extracts of cells fromLMandBMclosely resembled the normal control subjects in total extent and time course of inactivation. The reductase activity in extracts fromWMa, a fourth, unreleated patient was also completely inactivated but somewhat less rapidly than with patientCP.These results provide strong evidence that the reductase deficiency in these three families is due to different alleles. The data suggest that inCPandWMathere is a mutationally induced structural defect in the aporeductase as the basis for the observed alteration in thermostability, presumably reflecting reduced ability to bind the FAD cofactor.SpeculationThe observation that methylene-H4PteGlu reductase activity in crude fibroblast extracts from two of the three families studied shows reduced thermal stability as well as decreased activity raises the possibility that this enzyme is unusually susceptible to mutationally induced alterations in cofactor binding.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryThe abnormal metabolites 3-hydroxypropionic acid (1.6–4.0 mg/day) and methylcitric acid (3.7–5.8 mg/day) were identified and quantitated in the urine of a patient in whom biotin-responsive 3-methylcrotonylglycinuria and deficiency of 3-methylcrotonyl-CoA carboxylase had previously been documented. The level of excretion of these metabolites was in the lower range of those found in patients with propionic acidemia in whom there is a deficiency of propionyl-CoA carboxylase. The activity of this enzyme in fibroblasts derived from the patient and grown in media low in biotin was 4% of normal. This is in the range of patients with propionyl-CoA carboxylase deficiency. Documented deficiency in this patient of two carboxylases, both of which contain biotin, suggests that the primary defect is in the metabolism of biotin.SpeculationThe deficiency of two mitochondrial carboxylases in a patient suggests the presence of a fundamental defect in either the transport of biotin or in the holocarboxylase synthetase that attaches biotin covalently to both carboxylases.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryThis study utilized isoelectric focusing and electrophoresis in an attempt to detect a cystic fibrosis (CF) scrum factor(s), for which there is considerable indirect evidence. The method of isoelectric focusing in polyacrylamide gels (IEFAG) specified by Wilsonet al.(53), as reproduced in our laboratory, did not enable the detection of a CF factor protein reported to focus near pH 8.4–8.5. Consequently, we employed our modified IEFAG techniques, which enabled us to demonstrate significantly enhanced resolution and striking heterogeneity in serum γ-globulins. Despite the significant increase in the number of bands resolved by our methods, neither a difference at pH 8.4–8.5 nor other differences throughout the alkaline pH range could be detected consistently in the CF and heterozygous sera. The two-step IEFAG/disc electrophoresis technique outlined by Alt-landet al.(2), as reproduced in our laboratory, indicated that at least one small, cationic protein could be fractionated from all serum samples. Improvements in the method of disc electrophoresis resulted in the observation of numerous bands from some samples and of differences among the samples, but no protein band unique to the CF genotypes was observed.Our approach, employing different electrophoretic techniques and varying the conditions of sample analysis, should have increased the likelihood of detecting a protein or proteins specific for the CF genotypes. Despite the many variations in our approach, no consistently unique protein was observed in the CF or heterozygous sera.SpeculationA CF serum factor cannot be readily demonstrated by the electrophoretic techniques described. The value of the “biophysical assay” and the “nonbiologic technique” reported in the literature is suspect, and the promise and applicability of these techniques as diagnostic tests for the CF gene should be carefully evaluated.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryOne to 4 days before birth of their litters, pregnant buffalo rats were injected intravenously with 200 μCi of [2-14C]glycine in order to label a cohort of fetally produced red blood cells (RBC). Shortly after birth, the newborn rats were transferred to noninjected foster mothers, and RBC survival was determined by the rate of production of14CO in the expired air of the newborn animals. In separate experiments, pregnant rats were injected 1–2 days before birth of their litters; blood was collected from the newborn at 5 days of age, washed, transfused into normal adult hosts, and RBC survival determined from the resultant14CO production. When compared with adult RBC,in situsurvival of fetally produced RBC was 22% of normal (mean life span of 12.1 days in the fetus, and 54.5 ± 1.5 (SE) days in the adult). This shortening of survival resulted from an acceleration of RBC senescence (15.7 days for fetal RBC and 66.2 ± 0.7 days for adult RBC) and an increased rate of random hemolysis (3.70%/day in the fetal RBC and 0.67 ± 0.07%/day in adult RBC). Although cross-transfusion of adult RBC into compatible adult rat hosts resulted in only a modest shortening of RBC lifespan (mean RBC survival reduced from 54.5 ± 1.5 days to 52.8 ± 0.8 days), similar treatment of fetally produced RBC resulted in a marked acceleration of senescence from 15.7 days to 5.8 days. Examination of the RBC survival curves for those litters injected less than 72 hr before birth indicated the presence of an additional population of cells with survival in the range of 25–40 days. The proportion of cells surviving longer than the major cohort (but shorter than times characteristic of adult RBC) increased as the time interval between isotope injection and birth decreased.SpeculationThe magnitude of the shortening in survival noted for fetal RBC suggests the presence of structural and/or metabolic alterations peculiar to these cells, rather than alterations secondary to increased erythropoietic rate alone.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryCord blood erythrocytes from nine term infants were separated by density gradient centrifugation into cohorts of intact cells of progressively increasing density and compared with red cells treated in a similar manner from four healthy adults. Pyruvate kinase (PK), an age-dependent enzyme, progressively decreased in activity from the lightest to the heaviest fractions, in both neonatal and adult red cells, indicating that red cells from newborn infants exhibit the same relationship between red cell age and density that had previously been demonstrated in red cells from adults. The rate of decline of red cell PK activity was essentially the same in neonates and adults, whereas phosphofructokinase (PFK) activity in cord erythrocytes decreased at a significantly faster rate when compared to adults. These data suggest that PFK has an accelerated rate ofin vivodecay in neonatal red cells and is an unstable enzyme in the newborn.SpeculationThe finding that PFK from cord blood has an accelerated rate ofin vivodecay suggests that the relative PFK deficiency that exists in neonatal red cells is secondary to normal synthesis of an unstable enzyme, and leads to the speculation that red cell PFK in newborn infants is an isozyme (a “fetal” PFK).

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryA postnatal contraction of extracellular fluid occurs in low birth weight infants. Patterns of postnatal renal maturation were assessed with the assumption that changes in body composition were mediated in part by the developing kidney. Twenty-two appropriate for gestational age, low birth weight infants (birth weight mean = 1380 g, gestational age mean 31 weeks) were studied between 12 hr and 61 days of age to evaluate simultaneously glomerular and tubular functional maturation. Since most low birth weight infants have respiratory morbidities (respiratory distress followed by chronic lung disease), the infants were grouped into:group I(13 infants), transient or absent respiratory morbidities; andgroup II(9 infants), persistent and severe respiratory morbidities. Sodium excretion decreased with postnatal age in both groups. Sodium intake did not vary with postnatal age. The percentage of fractional sodium excretion was inversely related to postnatal age. Creatinine clearance correlated directly with postnatal age in both groups. Increased sodium excretion and percentage of fractional sodium excretion in the first 10 days of life may reflect extracellular fluid solute losses through the kidney. The premature kidney matured in a balanced fashion and persistent respiratory morbidities did not alter this pattern.SpeculationThe kidney of low birth weight infants probably plays an important role in the regulation of body fluid during the first week of life. The adjustment in renal tubular handling of sodium with greater sodium loss in the first days reflects its compensation to fit the demand of greater sodium excretion from the contraction of the extracellular fluid compartment. In an infant with a stable circulatory status, the presence of respiratory complications did not influence this adjustment process.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID