摘要:

ExtractWe have described two siblings who excrete massive amounts (up to 3.89 mmol/24 hr) ofN-formiminoglutamic acid (FIGLU) in their urine. This unusual compound was isolated from urine, purified, and firmly identified as FIGLU by combined gas chromatography-mass spectrometry. The patients presumably have a deficiency in activity of the hepatic enzyme, glutamate formiminotransferase, which carries out the fourth sequential step in the main pathway of histidine degradation. Unlike children reported previously with this disorder, our patients had normal serum folate levels, had no hematologic abnormalities, and were not mentally retarded. Very small amounts of FIGLU were present in the plasma of one of the patients, but FIGLU was not detectable in the cerebrospinal fluid of either patient. Administration of pharmacologic doses of folic or folinic acid produced a decrease in excretion of FIGLU in urine. Histidine loading caused a small and comparable urinary excretion of FIGLU in the children's parents and in control adult subjects.SpeculationGlutamate formiminotransferase deficiency may represent a further example of a genetically determined metabolic error which does not result either in accumulation of a toxic metabolite or in failure to synthesize a crucial metabolite, and which therefore produces no clinical disease syndrome.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThe molecular basis for the complex electrophoretic banding patterns of serum α1-antitrypsins of different protease inhibitor (PI) types is unknown. In order to demonstrate the role of sialic acid residues in this polymorphism, serums of homozygous PI, types FF, MM, and ZZ, were studied by acid starch and crossed electrophoresis, before and after treatment with neuraminidase. Increasing enzyme concentrations, temperatures, and times of incubation led to greater release of sialic acid and progressive slowing of PI bands. Exhaustive incubation of the three serum types with neuraminidase produced a single broad cathodal peak of α1-antitrypsin.Isoelectric focusing in gel with a pH 4–6 gradient, followed by immunoprecipitation of α1-antitrypsin bands, resulted in complex banding patterns with the expected differences in isoelectric points among the three serum types. After exhaustive neuraminidase treatment, each of the banding patterns remained complex, but shifted toward a more basic pH. Although sialic acid residues are one of the major determinants of the net charge and electrophoretic mobility of different PI types, differences remain after removal of sialic acids which may represent other genetically determined differences in primary structure.SpeculationDifferences in isoelectric point of the banding patterns of PI, FF, MM, and ZZ α1-antitrypsins, remaining after removal of their terminal sialic acid residues, suggest that other primary molecular differences exist among these inherited variants. By analogy with other well known protein polymorphisms, these differences are likely to consist of variations in primary amino acid sequence. Detailed analysis of purified PI system variants will be required to establish this possibility.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThe concentration of plasma ferritin was measured in serial samples of blood removed from six preterm neonates undergoing exchange transfusion for hyperbilirubinemia. The average plasma ferritin concentration in the infants was 218 ng/ml compared with 47 ng/ml in the donors. The mean concentration of ferritin decreased an average of 62 ng/ml during the exchange transfusions. The plasma ferritin half-life was computed to be 2.5 and 5.5 min in the two infants weighing 2,000 and 2,500 g compared with a half-life of 4 min in the rat. In four infants weighing between 1,000 and 1,180 g, the half-life ranged from 9.1 to 34 min. These data support the concept of a rapid plasma ferritin turnover and indicate that ferritin may transport a large amount of iron through the plasma compartment in spite of its low concentration.SpeculationPlasma ferritin appears to play an important role in iron transport in man.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractSolutions containing D-glucose (1–20 mg/ml) were perfusecin situthrough the jejunum + ileum of anesthetized rats 7–8 and 14–15 (suckling), 21–23 (weanling), 35–36, and 70–7: days old. The amounts of glucose absorbed, expressed as percentage of load perfused (normalized for intestinal weight milligrams per hour per gram wet weight), were greater in the weanling than in the suckling pups. Rate of glucose absorption increased with increase in glucose concentration in the perfused solutions and reached a plateau when concentration exceeded 3 mg/ml in the suckling and 10 mg/ml in the weanling rats. Based on intestinal weight, absorption rate (milligrams per hour per gram wet weight) from solution containing 10 mg/ml glucose were 2 times greater in the 21–23 than in the 7–8-day-old pups (64 versus 30;P< 0.01) Glucose absorption rates (milligrams per hour per gram we weight of the perfused intestine) from the 20 mg/ml solution were similar in the 21–23 (64), 35–36 (60), and 70–7 (58)-day-old rats. The above results suggested that under the experimental conditions in rats the ability of the small intestine to absorb glucose per unit weight about doubles a the time of weaning as compared with the suckling period with no further enhancement thereafter.SpeculationIn the rat at the time of weaning, intestinal lactase activity decreases, whereas that of sucrase increases. The findings o our study suggest that the same stimulus that increase; small intestinal sucrase activity also brings about changes in the glucose transporting mechanism. Other studies showing an increase in rates of glucose absorption in the small intestine under conditions where sucrase activity is enhanced will lend further support to the association between intestinal sucrase activity and glucose absorption rate.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Extract4-Pentenoic acid, an analog of hypoglycin which is believed to cause Jamaican vomiting sickness, was administered intraperitoneally to rats in an attempt to produce the features of Reye's syndrome in rats. Mean ammonia levels in plasma were found to be elevated approximately four-fold after injection of 200 mg/kg pentenoic acid in fed rats. Pentenoic acid caused hypoglycemia in fasted rats and hyperglycemia in fed rats. In chronic experiments rats were injected intraperitoneally every 4 hr with 50 mg/kg body weight of pentenoic acid for 10 doses, followed by a single dose of 200 mg/kg. The livers of the treated group were enlarged and yellow and showed extensive fatty degeneration. The blood-urea-nitrogen (BUN) was significantly higher and the free fatty acids (FFA's) significantly lower in these rats. This study shows that pentenoic acid administered to rats produces findings similar to those of Reye's syndrome and Jamaican vomiting sickness.SpeculationThe similarity of the features of Reye's syndrome, Jamaican vomiting sickness, and pentenoic acid and hypoglycin toxicity

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractRats whose mothers received hydroxyurea (HU, 1 or 2 g/kg) at 14 days of gestation had a 30% deficit in both brain and body weight at birth, when compared with controls. Number of brain cells at birth (mainly neurons) was reduced by 33–34%. A severe reduction in postnatal whole brain growth (31–33% in adulthood) was observed, but the cerebellum was relatively spared. In the Hebb-Williams maze text in adulthood HU animals made 28% more errors than controls over 12 problems. The differences were much more marked on certain problems and for HU animals with particularly small brains. In a T-maze spatial discrimination test in adulthood HU rats learned the initial response normally but, when required to reverse this response, showed a significant tendency to make more perseverative errors than controls.SpeculationRats exposed to an inhibitor of cell division at the beginning of the major period of brain neurogenesis showed deficits in learning ability in adulthood. The large number of mentally retarded human children whose handicap is without known etiology may have suffered a similar early loss of neurons, and if so, this preparation could provide a useful animal model.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThe rabbit model ofHerpesvirus hominis(HVH) encephalitis was utilized to determine whether thymidine (TdR) kinase (EC. 2.7.1.2.1), an early enzyme in the HVH replicative cycle, is present in the cerebrospinal fluid (CSF) of rabbits with HVH encephalitis. The mean TdR kinase activity in CSF from infected rabbits was 2.30 ± 1.69 pmol product/120 min/100 μl CSF, while the mean TdR kinase activity of uninfected CSF was 0.34 ± 0.25. The enzyme appeared to be cell associated since the TdR kinase activity in the sedimented cell suspension was 5.08 ± 2.93 (seven values) while the supernatant activity was 0.14 ± 0.31 (seven values). To allow a comparison of TdR kinase from infected rabbit CSF with HVH and rabbit mononuclear cell TdR kinase, the mean ratio of TdR kinase activity at pH 6.0/pH 8.0 was calculated. The mean ratio of thymidine kinase activity, pH 6.0/pH 8.0, for infected rabbit CSF is intermediate between the ratio for HVH TdR kinase (P< 0.001) and rabbit mononuclear cell TdR kinase (P< 0.05).SpeculationThe presence of TdR kinase in CSF from HVH-infected rabbits with biochemical properties intermediate between HVH and mononuclear cell TdR kinase suggests that abortive HVH infection occurs in CSF mononuclear cells during the course of HVH encephalitis.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractFour protein dietary groups of rats were used in this study, namely: 27% casein diet fed throughout gestation and lactation (group C-C); 27% gestation, 10% lactation (group C-D); 10% gestation, 27% lactation (group D-C); 10% throughout gestation and lactation (group D-D). Mean body weight ofgroup D-Dat weaning was 19 g compared with 59 g forgroup C-C.The specific activity of Na+-K+-ATPase in isolated synaptosomes from cerebral and cerebellar tissues increases throughout the lactation period. At 1 and 7 days of age no differences in Na+-K+-ATPase activity are noted in the brain regions ofGroups C-CandD-D.At 14 and 21 days, however, the specific Na+-K+-ATPase activity was significantly reduced in isolated synaptosomes from both brain regions of the protein-deprived group. ATPase activity in cerebellar synaptosomes from dietary exchange groups (C-DandD-C)…

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThe widespread use of phototherapy for neonatal hyperbilirubinemia has caused some concern since substances other than bilirubin may be photoactivated. The toxic properties of these photoactivated substances might prove to be more harmful to the neonatal infant than bilirubin. The purpose of the present study was to investigate the effect of photoactivated riboflavin in low concentration, on purified DNA. The results demonstrate extensive changes in the structure of DNA (see Table 1) manifested by (1) a change in the peak absorbance in the ultraviolet, (2) a decrease in the temperature of the thermal helix-coil transition, (3) a slight decrease in the sedimentation coefficient, and (4) an increase in the buoyant density values (1.704–1.709). These observations are consistent with the interpretation that there has been an alteration of one of the base moieties with minimal cleavage of the phosphodiester linkages. Results with human cells in tissue culture indicate that a similar photodynamic effect of riboflavin on the DNA occurs in living cells.SpeculationIn view of the known relation between the ability of a variety of agents to modify DNA on the one hand and the potential to induce mutation and cancer on the other, the present results suggest that riboflavin supplementation as an adjunct to phototherapy for hyperbilirubinemia requires more thorough evaluation.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThere is a critical point in development when the size of an animal, arising from its previous plane of nutrition, determines its appetite thereafter, and hence its rate of growth and dimensions at maturity. A small size at this critical time, brought about by undernutrition, is not followed by “catch-up” growth, however liberal the diet.A full diet produces catch-up growth only if the undernutrition, whatever its cause, has occurred after this critical period is over. It can, moreover, only restore a young animal to its percentile channel of growth, and its ability to do this after long periods of undernutrition becomes progesssively limited by the animals chronologic age when the catch-up growth became possible.SpeculationMany of the determinants of growth and form are known but the results have presented difficulties in interpretation and have not been synthesized hitherto into a coherent whole. The present paper outlines a theory directed to this end.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID