Biochemical medicine最新文献

The purpose of this study was to find out how genetic and biochemical limitations influence psycho-social performance and to partially test the validity of justification theory. The ability to convert phenylalanine to tyrosine was compared with intellectual and personality characteristics in PKU family members.

Each of the tested persons was given an oral dose of phenylalanine, the Shipley-Hartford Intelligence Test, and the Minnesota Multiphasic Personality Inventory (MMPI). Only those persons with reading ability at the sixth grade level or higher were tested. Eighty-six persons were tested: fifteen PKUs, forty-three siblings, and twenty-eight parents.

A comparison was made among parents, PKUs, and the siblings. Siblings with the higher $\text{2}\text{3}\text{'}\text{s}$ of $\text{P}{}^2\text{T}$ ratios were contrasted with those with the lowest $\text{1}\text{3}$ of ratios on measures of intelligence and psychopathology.

Statistical analyses of the data reflected a trend in support of the justification theory. PKUs had significantly lower intelligence than their sibs and parents. The PKUs' mean IQ was 95 (homozygotes born of heterozygotes), followed by the upper $\text{2}\text{3}\text{'}\text{s}$ sibling mean IQ of 105 (heterozygotes born of nonheterozygote mothers). The lower $\text{1}\text{3}$ siblings' mean IQ was 107 (nonheterozygotes born from heterozygote mothers), and finally, the parents' mean IQ was 109 (heterozygotes, among them 50% were born from nonheterozygote mothers). The latter three mean IQs are not significantly different from each other.

The personality tests revealed a trend toward more abnormality in PKUs than in their heterozygote siblings. The lowest rate of abnormality occurred in the nonheterozygote sibling group; that rate was significantly lower than in all other groups. The parents had the highest absolute rate of personality abnormality, but statistically so compared only to the low-ratio siblings.

The object of the study was to explain the differences in bilirubin level in various experimental jaundice models. The Bil constituents in conjugated hyperbilirubinemic dog models were identified. Total Bil was measured using the Jendrassik and Grof method and direct spectrophotometry. Conjugated and unconjugated Bil were measured using the Weber-Schalm extraction method. Bilirubin covalently bound to albumin was measured indirectly from the total Bil and the non-CBBA fraction. The non-CBBA was estimated either as the sum of the CB and UCB concentrations determined by the W-S method or as the nonprecipitated fraction after deproteinization with ammonium sulfate-saturated ethanol when using DS.

The TB, CB, UCB, and CBBA levels were compared in two hyperbilirubinemic dog models: (a) chronic bile duct ligation (CBDL) and (b) internal choledochocaval anastomosis (CDCA). The mean TB in internal CDCA (16.5 ± 3.67 mg%) was significantly higher than in CBDL (3.4 ± 1.75 mg%). Most of the serum Bil in these two models was conjugated, 13.4 ± 2.24 and 3.2 ± 1.7 mg%, respectively. No CBBA was found in the CBDL or in the partially obstructed internal-CDCA dogs. The TB in an external-CDCA model was essentially similar to the internal-CDCA model. The indirect Bil level in the external-CDCA model was six to seven times higher than the UCB level, and the CBBA level varied between 30 and 80% of the TB. Up to 50% CBBA was found also in patients with intra- or extrahepatic cholestasis.

The findings indicate that, unlike the commonly assumed hypothesis, the serum TB level in the CDCA models, which was higher than in the CBCL one, is not due to high UCB levels. Rather, hyperbilirubinemia in the external-CDCA model is due to increased levels of CBBA or, perhaps, to variations in the amount and/or composition of CB entering the blood and cleared by the kidney.

Myoadenylate deaminase deficiency, the most common of the known enzyme deficits of muscle, appears to occur in two forms. The primary type seems to be inherited as a complete gene block in an autosomal recessive pattern. Although occasionally diagnosed in infancy, when muscle biopsy is performed on a hypotonic but normoreflexic child, the deficiency is usually not symptomatic until adult or middle age, when muscle cramping and exercise intolerance develop. The skeletal muscle isozyme is immunologically, and presumably genetically, unique, and these patients have normal levels of adenylate deaminase in their other cells and tissues. A presumptive diagnosis can usually be made by an ischemic forearm exercise test, which shows a negligible increase in blood ammonia, despite a normal rise in lactate. Despite the absence of more than 99% of normal adenylate deaminase activity, the muscle biopsy shows no anatomic pathology, and other enzymes are at normal levels. These patients do not suffer progressive disease, and should be reassured, and encouraged to maintain physical activity. The heterozygous state is probably asymptomatic, except, perhaps, on extreme exercise, but may be associated with an increased incidence of malignant hyperthermia susceptibility.

Since the gene defect is not rare, it is not surprising that some cases of the deficiency will be coincidentally associated with other neuromuscular disease. However, there is also a secondary form of myoadenylate deaminase deficiency, consequent to muscle damage from other disease. In this form, the residual activity is higher (1–10% of normal), may present rare foci of positive stain in the section, and reacts normally with antibody to the muscle isozyme. Other muscle enzymes are also depleted, although not as severely, and the prognosis in such cases is dictated by the primary disease. Since the heterozygous state is common, these patients might have been carriers, whose adenylate deaminase levels have been lowered to the deficient category by the advent of other neuromuscular disease.

Glycerol, glycerol-3-phosphate (G3P), and dihydroxyacetone phosphate (DHAP) were evaluated as inhibitors of gluconeogensis on rat liver enzymes in vitro, and for their effects on glucose formation in vivo in well-nourished and malnourished rats. DHAP was more potent as an inhibitor than G3P on fructose-1,6-diphosphatase (FDPase), phosphoenolpyruvate carboxykinase (PEPCK), and glucose-6-phosphatase (G6Pase). The I₅₀ for DHAP was 2, 8, and 9 × 10⁻³m, respectively. No effect was observed on rat liver pyruvate carboxylase (PC). Glycerol was a weak inhibitor of FDPase and PEPCK, but did not inhibit PC and G6Pase. In vivo, when G3P was injected before a parenteral l-alanine (Ala) challenge, it produced a hypoglycemic effect in malnourished rats and a lesser, but noticeable, blood glucose level reduction in well-fed animals. Glycerol caused a smaller reduction in glucose formation from Ala. No comparable effects were observed after a fructose pretreatment. These results underscore the potential hypoglycemic effects of phosphorylated glycerol metabolites and identify the steps in gluconeogenesis where this action is exerted. The study also stresses the nutritional component in the glycerol intolerance syndrome, apparent from the far more severe effects observed in malnourished rats given G3P or glycerol prior to Ala.

Glucocerebrosidase was isolated from bovine brain by cholate extraction, ammonium sulfate fractionation, acid precipitation at pH 5.35, and hydrophobic chromatography. The purification is about 2400-fold with a specific activity of about 286,000 nmole/hr/mg protein. Molecular weight as determined by chromatography on Bio-Gel P-200 was 138,000. On SDS-polyacrylamide gel electrophoresis the enzyme protein resolved into two bands with apparent molecular weights of 63,000 and 56,000. These bands are cross-reactive to monospecific polyclonal antibody to homogeneous human placental glucocerebrosidase. The enzyme was found to be a complex glycoprotein based on its lectin binding specificity. Brain enzyme was found to be similar to placental glucocerebrosidase in its pH optima, heat stability at 52°C, and substrate affinity. Enzyme kinetics were measured in the presence of conduritol-β-epoxide, an irreversible inhibitor, and gluconolactone, and competitive inhibitor.