Detection of carriers of human Duchenne muscular dystrophy by freeze-fracture analysis of erythrocyte plasmalemmal intramembrane particles

Critical examination of plasma membrane particles on fracture faces of erythrocyte plasma membranes of human obligate carriers of Duchenne muscular dystrophy, control patients, and a patient afflicted with Duchenne muscular dystrophy revealed a 32% decrease in the number of intramembrane particles in erythrocytes of carriers compared with erythrocytes sampled from control patients. These results support the notion that quantitative analysis of intramembrane particles in freeze-fractured erythrocyte plasma membranes represents a new, rapid, simple, and highly accurate diagnostic tool for detection of carriers of human Duchenne muscular dystrophy.     

Increased lipoperoxide value and glutathione peroxidase activity in blood plasma of Type 2 (non-insulin-dependent) diabetic women

Summary The lipoperoxide values and glutathione peroxidase activity in blood plasma, along with the glutathione peroxidase, catalase and cupro-zinc superoxide dismutase activities in erythrocytes were investigated in 60 women with Type 2 (non-insulin-dependent) diabetes mellitus and in 71 healthy women. The mean lipoperoxide value and the mean plasma glutathione peroxidase activity in the diabetic patients were significantly higher than those in the control subjects (lipoperoxidep<0.001, plasma glutathione peroxidase activityp<0.01). The plasma glutathione peroxidase activities did not, however, correlate with the plasma lipoperoxide values. The erythrocyte glutathione peroxidase activity was approximately ten times higher than that of the plasma glutathione peroxidase activity, nor did they correlate with each other. In contrast to the findings of other authors on the activities of the protective enzymes in erythrocytes against oxidative damage, there were no significant differences of erythrocytes glutathione peroxidase, catalase and superoxide dismutase activities between diabetic and control women.Abbreviation SOD superoxide dismutase     

Cystinuria genotypes predicted from excretion patterns

Genotypes of 17 patients with cystinuria were predicted from data based on excretion rates of the families' obligate carriers. The methodology differed from that used by other investigators as it did not employ intestinal biopsy studies or loading dose measurements. The Type I form was more common than either Type II or Type III and frequently occurred in combination to give compound heterozygous genotypes with the Type III form.     

Assay of the β-glucosidase activity with natural labelled and artificial substrates in cultivated skin fibroblasts from homozygotes and heterozygotes with the Norrbottnian type of Gaucher disease

Fibroblasts from 13 homozygotes and 27 obligate heterozygotes with the Norrbottnian type of Gaucher disease and 17 controls were cultivated and assayed with five β-glucosidase methods, two with D- [glucose- U-¹⁴C] glucosylceramide and three with the artificial substrate 4-methylumbelliferyl-β-glucoside. Two marker enzymes were assayed on the same cell samples, 4-methylumbelliferyl-β-galactosidase and N -acetyl-β-glucosaminidase. The β-glucosidase activity of cultured fibroblasts, as measured with all five β-glucosidase methods, was significantly lower (P < 0.001) for Gaucher homozygotes than heterozygotes. There was no overlap between fibroblasts from Gaucher homozygotes and the others with any of the β-glucosidase methods used. The β-glucosidase activity was also significantly lower ( P < 0.001) for Gaucher heterozygotes than controls. However, none of the five β-glucosidase assays differentiated between all Gaucher heterozygotes and controls, as several overlaps occurred in each assay.     

Cystinuria genotypes predicted from excretion patterns.

Genotypes of 17 patients with cystinuria were predicted from data based on excretion rates of the families' obligate carriers. The methodology differed from that used by other investigators as it did not employ intestinal biopsy studies or loading dose measurements. The Type I form was more common than either Type II or Type III and frequently occurred in combination to give compound heterozygous genotypes with the Type III form.     

Synthetic substrate ß-glucosidase activity in leukocytes: A reproducible method for the identification of patients and carriers of Gaucher''s disease

A method is described for the identification of patients and carriers of Gaucher's disease, using leukocytes from a small volume of blood. The fluorogenic substrate, 4-methylumbelliferyl-beta-D-glucopyranoside, was assayed in the presence of pure sodium taurocholate (2.5 mg/ml) and Triton X-100 (2.0 mg/ml). Some commercial brands of pure sodium taurocholate were satisfactory for this purpose. The pH optimum for controls, Gaucher disease carriers and Gaucher disease patients was 5.4 using citrate-phosphate buffer. Although leukocytes prepared from only a small amount of blood (2-8 ml) are required, there is sufficient quantity for measuring other lysosomal enzymes as controls. Using this method, 12 patients with all types of Gaucher's disease and 12 obligate heterozygotes were identified. Carrier status was predicted in six other family members and ruled out in six others. Eight unaffected people married to Gaucher carriers or Gaucher patients were predicted to be non-carriers of Gaucher's disease, thereby ruling out children affected with Gaucher's disease in that mating.     

肝移植患者围手术期红细胞免疫功能与T、B淋巴细胞亚群的关系

背景：国内多中心研究结果表明：红细胞天然免疫黏附功能的变化与肝脏损伤程度密切相关,可作为分析病情严重程度、判断病情预后的一项灵敏指标,但在肝移植领域尚未见相关研究与应用。 目的：了解肝移植围手术期患者红细胞天然免疫黏附功能和T、B淋巴细胞亚群的变化及二者相关性。 方法：采用红细胞C3b受体酵母形成花环实验的方法,检测21例肝移植围手术期患者的红细胞天然免疫黏附功能和T、B淋巴细胞亚群的变化,并进行相关性分析。 结果与结论：①肝移植围手术期患者移植前红细胞天然免疫黏附功能低于健康人,移植后第1天降至最低点,移植后2周至移植后1个月可基本恢复至健康人的水平。②肝移植患者移植前T、B淋巴细胞亚群组合中仅表现为CD45低于正常参考范围,其余指标均基本正常;CD4、CD8、CD45于移植后第1天降至最低点,移植后第1周恢复到移植前水平;CD4/CD8、B淋巴细胞在整个围手术期过程中均无明显变化。③红细胞天然免疫黏附功能与T、B淋巴细胞亚群指标之间呈正相关。肝移植围手术期红细胞天然免疫黏附功能的变化较T、B淋巴细胞亚群的变化明显。结果表明红细胞天然免疫黏附功能是反映肝移植围手术期患者肝脏损伤恢复趋势及机体免疫功能变化的更加灵敏的指标。     

Glycoprotein storage in Gaucher disease: lectin histochemistry and biochemical studies

Lectin histochemical studies were performed on formalin-fixed, frozen, and paraffin-embedded tissue sections from 19 patients with glucosylceramide lipidosis (i.e., Gaucher disease). Eleven different lectins were used to identify the specific carbohydrate residues in the undegraded stored compounds in the cytoplasm of Gaucher cells. In all cases studied, Gaucher cells stained with Concanavalia ensiformis agglutinin, Datura stramonium agglutinin, Lens culinaris, Ricinus communis agglutinin-I, and wheat germ agglutinin. These results demonstrated common carbohydrate residues in the undegraded material stored within Gaucher cells and indicated the presence of fucosylated N-linked complex oligosaccharides, and glycans containing N-acetyllactosamine repeating sequences, as well as nonreducing terminal beta-galactosyl and sialyl residues. In order to confirm these findings using biochemical methods, livers and spleens from Gaucher patients and controls, and from a patient with Niemann-Pick disease type C (included for comparison) were digested with Pronase and the resulting glycopeptides separated by gel filtration into fractions with high and low molecular weight. In the high-molecular-weight fractions from livers of Gaucher patients, the levels of sugars corresponding to N-linked glycans, as measured by gas-liquid chromatography, were elevated over those in controls. In the high-molecular-weight fractions from spleens, the levels of the same sugars were elevated in both Gaucher and Niemann-Pick type C patients. Digestion of the glycopeptides with endo-beta-galactosidase, which specifically cleaves polylactosaminoglycans, showed the presence of material containing N-acetyllactosamine repeating units in Gaucher liver glycopeptide fractions, but not in control and Niemann-Pick type C derived glycopeptide fractions. Our histochemical and biochemical studies demonstrated that in addition to glucosylceramide, affected tissues of patients with Gaucher disease accumulate glycoproteins. This accumulation could not have been predicted on the basis of the primary enzymatic defect.     

Effects of hyperglycaemia and sorbitol accumulation on erythrocyte deformability in diabetes mellitus.

Erythrocyte deformability was studied in a total of 83 poorly controlled diabetics (mean blood glucose 12.2 mmol/l) who were divided into three groups, each with matched healthy controls. There was no appreciable difference between diabetics and matched controls regarding the filtration of erythrocytes through 3 micron diameter straight channel pores (25 diabetics) or tortuous channel pores (28 diabetics), or for the measurement of erythrocyte elongation over a range of osmolalities in the Ektacytometer (30 diabetics). When erythrocytes from 17 additional diabetics and 17 healthy controls were incubated for two hours at 37 degrees C in hyperglycaemic (50 mmol glucose/l) buffer, however, there was a considerable reduction in erythrocyte filterability for both diabetics and controls in parallel with an increase in erythrocyte sorbitol concentration. This loss of filterability was prevented by the addition of an aldose reductase inhibitor (Sorbinil). High glucose concentrations (congruent to 50 mmol/l) impair the filterability of erythrocytes through 3 micron pores, and the intracellular accumulation of sorbitol in poorly controlled outpatients is therefore unlikely to have a major adverse effect on erythrocyte rheology in diabetes mellitus.     

Gaucher disease: accurate identification of asymptomatic French-Canadian carrier using nonlabeled authentic sphingolipid substrate N-palmitoyl dihydroglucocerebroside

Gaucher disease is an autosomal recessive sphingolipidosis associated with deficient glucocerebroside beta-glucosidase activity. It is a panethnic metabolic disorder, but the carrier frequency is particularly high among Ashkenazi Jews (estimated between 1:12-1:25). In order to establish a reliable and convenient biochemical assay method for differentiating asymptomatic Gaucher carriers from normal individuals, glucocerebroside beta-glucosidase activity was determined in peripheral blood lymphocytes and cultured skin fibroblasts of 11 Gaucher obligate heterozygotes using the authentic nonlabeled sphingolipid substrate N-palmitoyl dihydroglucocerebroside and the artificial fluorogenic substrate 4-methylumbelliferyl-beta-D-glucopyranoside (4MUGP). The level of lymphocyte beta-glucosidase activity on the glucocerebroside substrate was observed to range from 42-65% of that of the control mean, and there was no overlap of enzyme activity between the Gaucher heterozygotes and controls. However, when the artificial fluorogenic substrate 4MUGP was used, the level of beta-glucosidase activity in 2 of the Gaucher obligate heterozygotes was noted to overlap with that of the control individuals. Contrary to findings in the lymphocytes, cultured skin fibroblasts appear to be a reliable enzyme source for Gaucher carrier detection even when the artificial fluorogenic 4MUGP substrate was used, as the level of beta-glucosidase activity in all of the Gaucher obligate heterozygotes tested was intermediate and distinctly separated from that of the control persons. Using the lymphocyte glucocerebroside beta-glucosidase assay and fibroblast 4MUGP beta-glucosidase assay methods, we identified the carrier status in 3 other relatives and ruled it out in 4 others. These data suggest that nonlabeled glucocerebroside is a reliable and highly specific substrate for either lymphocyte or fibroblast beta-glucosidase activity assay in identifying asymptomatic Gaucher carriers. Use of the 4MUGP substrate for differentiating Gaucher heterozygotes from control persons, on the other hand, should be restricted to the fibroblast enzyme assay method, as considerable overlap of enzyme activity was noted in lymphocytes.     

Association between Asymmetric Dimethylarginine and Neopterin in Patients with and without Angiographic Coronary Artery Disease

The increase of circulating asymmetric dimethylarginine (ADMA) concentrations, a competitive inhibitor of the nitric oxide synthases, is associated with an increased cardiovascular risk and is considered to play a role in endothelial dysfunction. Recently, ADMA production was observed in stimulated human peripheral mononuclear cells. In this study, we examined a potential relationship between concentrations of ADMA and of the immune activation marker neopterin in patients scheduled for coronary angiography. In a cross-sectional approach, blood concentrations of ADMA, homocysteine, neopterin, folic acid and vitamins B6 and B12 were compared in 2030 patients, which were recruited as participants of the LUdwigshafen RIsk and Cardiovascular Health (LURIC) study. ADMA concentrations did not differ between patients with coronary artery disease (CAD) (mean ± SD: 0.82 ± 0.15 μmol/l) and controls (0.81 ± 0.14 μmol/l; Welch's t- test: P  = n.s.). ADMA concentrations correlated with homocysteine ( r _s = 0.207) and vitamin B6 ( r _s = −0.190), and an even stronger correlation with neopterin ( r _s = 0.276; all P  < 0.0001) was observed. In conclusion, increased ADMA concentrations in patients at risk for atherosclerosis are associated with increased neopterin concentrations. Data suggest that immune activation may contribute to increased ADMA production in CAD patients.     

Increased dimerization of alpha-synuclein in erythrocytes in Gaucher disease and aging

Gaucher disease (GD) patients and carriers of glucocerebrosidase mutations are at an increased risk for Parkinson's disease (PD). The presynaptic protein alpha-synuclein (AS) is linked to PD. In the current work we examined biochemical properties of AS in GD patients. We generated membrane-enriched lysates from erythrocytes of 27 patients with GD and 32 age- and sex-matched controls and performed Western immunoblotting with antibodies against AS. Levels of monomeric AS did not differ between GD patients and controls and did not change as a function of age. However, the ratio of dimeric to monomeric AS was significantly increased in GD patients, and showed a significant positive correlation with age. Therefore, two major risk factors for PD, aging and GD status, are associated with an increased AS dimer to monomer ratio in erythrocytes. This ratio needs to be validated in further studies as a potential biomarker for PD risk.     

Protective effect of melatonin on experimental otitis media with effusion in guinea pigs

The aims of this study were: (a) to assess whether the increased oxidative stress in otitis media with effusion (OME) induced in guinea pigs by histamine injection into the middle ear cavity is reflected by lipid peroxidation in erythrocytes, plasma, and middle ear effusion fluid; (b) to survey the alterations of oxidant and antioxidant enzyme activities in experimental OME; and (c) to determine the effects of melatonin and methylprednisolone on this oxidative stress. Malondialdehyde (MDA) level, erythrocyte total (enzymatic plus non-enzymatic) superoxide scavenger activity (TSSA), non-enzymatic superoxide scavenger activity (NSSA), superoxide dismutase (SOD), catalase (CAT), and xanthine oxidase (XO) activities were measured in 4 groups of 7 guinea pigs at 3 hr after injection of 0.1 ml of histamine (or saline) into the middle ear. Group I was the control group, Group II was an experimental group with OME induced by histamine, Group III was a melatonin-pretreated OME group, and Group IV was a methylprednisolone-pretreated OME group. In erythrocyte, plasma, and middle ear effusion samples, MDA levels were significantly increased in guinea pigs with OME (Group II), compared to controls (Group I); erythrocyte TSSA and SOD activities were lower and erythrocyte XO activity was increased in guinea pigs with OME (Group II) compared to controls (Group I). No significant differences were found in erythrocyte NSSA and CAT activities. In Group III, pretreatment of guinea pigs with i.p. melatonin at 1 hr prior to histamine induction of OME decreased the erythrocyte, plasma, and effusion MDA levels, compared to Group II; erythrocyte XO activity was diminished and erythrocyte TSSA, SOD, and CAT activities were increased in Group III compared to Group II. In Group IV, pretreatment of guinea pigs with i.p. methylprednisolone at 1 hr prior to histamine induction of OME decreased the plasma and effusion MDA levels and increased the erythrocyte TSSA and SOD activities, compared to Group II. These results suggest that reactive oxygen species (ROS) play a role in histamine-induced OME. Pretreatment with i.p. melatonin or methylprednisolone both decrease the ROS generated by experimental OME, but melatonin appears to be more effective than methylprednisolone.     

Age-specific Parkinson disease risk in GBA mutation carriers: information for genetic counseling

PurposeWe sought to estimate age-specific risk of Parkinson disease in relatives of patients with Gaucher disease, who are obligate carriers of GBA mutations and who were not ascertained by family history of Parkinson disease.MethodsA validated family history of Parkinson disease questionnaire was administered to 119 patients with Gaucher disease who were evaluated at the Mount Sinai School of Medicine from 2009 to 2012; the ages of their parents, siblings, and children, history of Parkinson disease, age at onset of Parkinson disease, and ethnic background were obtained. Kaplan–Meier survival curves were used to estimate age-specific Parkinson disease penetrance among parents of patients with Gaucher disease, who are obligatory GBA mutation carriers.ResultsTwo participants with Gaucher disease were affected by Parkinson disease (5.4% of those who were 60 years or older). Of the 224 informative parents of patients with Gaucher disease, 11 had Parkinson disease (4.9%). Among the parents (obligatory carriers), cumulative risk of Parkinson disease by ages 65 and 85 was estimated to be 2.2% ±2.1% and 10.9% ±7.2%, respectively.ConclusionWe provide useful age-specific estimates of Parkinson disease penetrance in patients with Gaucher disease and GBA heterozygous carriers for genetic counseling. Although GBA mutations may increase the risk for PD, the vast majority of patients with Gaucher disease and heterozygotes may not develop the disease. Further studies are needed to identify what modifies the risk of Parkinson disease in GBA mutation carriers.Genet Med 2013:15(2):146–149     

Miglustat as a therapeutic agent: prospects and caveats

A viable treatment for lysosomal storage disease has been very difficult to attain. One option is pharmacological inhibition of synthetic pathways to reduce substrate accumulations. Miglustat N-butyldeoxynojirimycin (NBDNJ), an inhibitor of glucosylceramide synthase, has shown much promise in clinical trials for the treatment of Type I Gaucher disease. The molecular events invoked by NBDNJ in cell culture and in animal models have not been so definitive. This review discusses the biochemical and molecular impact of NBDNJ as it relates to its potential as a therapeutic drug.     

The Asn9 variant of lipoprotein lipase is associated with the — 93G promoter mutation and an increased risk of coronary artery disease

Two mutations in the lipoprotein lipase (LPL) gene, a T to G transition at position −93 of the proximal promoter region and an Asp9Asn substitution in exon 2, were examined in 762 Dutch males with angiographically-diagnosed coronary artery disease (CAD) and 296 healthy normolipidemic Dutch males. The two mutations exhibited strong linkage disequilibrium (D'=0.975). A significantly higher proportion of cases (4.86%) than controls (1.37%) carried the −93G/Asn9 allele (p=0.008). In the combined sample of cases and controls, adjusted mean plasma total cholesterol (TC) levels were significantly higher in −93G/Asn9 carriers (6.20±0.13 mmol/l) than in non-carriers (5.93±0.03 mmol/l; p=0.048), while mean high-density lipoprotein cholesterol (HDL-C) levels were lower in carriers (0.88±0.03 mmol/l) than in non-carriers (0.98±0.01 mmol/l; p=0.002). There was a trend towards higher triglyceride (TG) levels in carriers (1.96±0.14 mmol/l) compared with non-carriers (1.73±0.03 mmol/l) (p=0.08). Additionally, carrier frequencies in tertiles of TC, HDL-C, TG, and LPL activity, suggested an association of the −93G/Asn9 variant with higher TC and TG levels, and with lower HDL-C and LPL activity levels. Logistic regression revealed a significant odds ratio (OR) for the combined −93G/Asn9 genotype in CAD cases relative to controls (OR: 5.36; 95% CI: 1.57–18.24), with age, body mass index (BMI), smoking, and plasma total- and HDL-cholesterol levels included in the model. In conclusion, we show that the LPL Asp9Asn mutation is in non-random association with a T→G substitution at position −93 of the proximal promoter region and that the combined −93G/Asn9 genotype predisposes to decreased HDL-C levels and an increased risk of CAD.     

Type 1 Gaucher disease: null and hypomorphic novel chitotriosidase mutations-implications for diagnosis and therapeutic monitoring

Human plasma chitotriosidase (Chito) is a useful diagnostic and therapeutic biomarker for Type 1 Gaucher disease (GD). However, approximately 40% of Caucasians are heterozygous or homozygous for a common null mutation, c.1049_1072dup24 (dup24) in the chitotriosidase gene (chitinase 1, CHIT1), that complicates interpretation for heterozygotes and precludes use for null homozygotes. 320 Type 1 GD patients were screened for CHIT1 genotype and plasma Chito enzyme levels; 37% were heterozygous and 4% were homozygous for the CHIT1 dup24 allele. Four patients who had no or very low plasma Chito activities had wild-type (wt)/dup24 or wt/wt CHIT1 genotypes, suggesting the presence of other mutations. Sequencing their CHIT1 genes revealed three novel mutations: p.E74K (E74K), p.G102S (G102S), and a complex exon 10 lesion (c.[1060G>A; 1155G>A; 1156+5_1156+8delGTAA], p.[G354R; L385L; missplicing], designated "complex E/I-10"). The G102S mutation was common in Type 1 GD patients and controls ( approximately 30% of alleles). In contrast, the E74K mutation was rare, present only in three Type 1 GD patients ( approximately 1% of alleles), all of Ashkenazi Jewish (AJ) descent, but it was not found in normal controls. The complex E/I-10 mutation occurred in two Caribbean Hispanic/African Type 1 GD patients and was present in 0 to 6% of alleles among normal controls from different populations. In vitro expression demonstrated that the E74K and G102S alleles had approximately 51% and approximately 23% of wild-type Chito catalytic efficiency, respectively. Expression of the G354R allele alone or with the L385L silent substitution did not produce detectable Chito activity or protein. RNA studies indicated that the complex E/I-10 allele also caused missplicing. Recognition of these mutations, particularly G102S, will facilitate the use and interpretation of plasma Chito activities for disease diagnosis, estimating disease severity, and monitoring therapeutic efficacy in GD.     

Influence of methimazole treatment on parameters of oxidative stress in patients with Graves’ disease

It is known that hyperthyroidism is associated with oxidative stress. Graves’ disease (GD) is an autoimmune thyroid disorder responsible for 70–80% of all cases of hyperthyroidism. The aim of this study was to examine the change of oxidative stress and antioxidant enzyme activities in 23 patients with Graves’ disease before and after treatment with methimazole and in 31 healthy controls. The level of malondialdehyde (MDA) in the plasma, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities in erythrocytes were measured. Serum levels of TSH and free thyroxin (FT4) were also estimated. We observed increased concentrations of FT4 and suppressed TSH levels before treatment. The concentrations of thyroid hormones and of TSH normalized after the methimazole treatment. Significantly higher MDA concentrations were found in hyperthyroid GD patients in comparison to controls (1.96±0.10 vs 1.71±0.05 μmol/l, p<0.05). After a long-term drug treatment, the plasma levels of MDA decreased and reached values close to the controls (mean 1.73 μmol/l). Activity of GPX in erythrocytes in hyperthyroidism was higher compared to controls (9.3±1.2 vs 6.6±0.5 U/gHb, p<0.05). After thyrostatic treatment in euthyroidism, the activity of GPX was found to decrease in euthyroid GD patients in comparison to hyperthyroid patients, compared to controls (3.9±0.5 vs 9.3±1.2 U/gHb and 3.9±0.5 vs 6.6±0.5 U/gHb; p<0.001, p<0.001, respectively). Our data confirm the presence of increase in lipid peroxidation in hyperthyroid patients, which is corrected in euthyroidism. We hypothesize that in hyperthyroidism, the enhanced activity of GPX was induced by oxidative stress and was connected with TSH receptor hyperstimulation. After treatment with methimazole, GPX activity was lowered. Observed alterations of GPX activity after Graves’ disease treatment may be related to the deficiency of cellular antioxidative defense that persists during the course of disease. The disturbed antioxidative defense in patients with Graves’ disease indicates the possible usefulness of supplementation with antioxidants in particular with selenium as an important component of selenoenzymes such as GPX.     

4-pyridone-3-carboxamide ribonucleoside triphosphate accumulating in erythrocytes in end stage renal failure originates from tryptophan metabolism

We recently identified an erythrocyte nucleotide accumulating in end-stage renal disease as 4-pyridone-3-carboxamide ribonucleotide triphosphate (4PYTP), a nucleotide never described previously. Plasma tryptophan concentration has been previously reported to be reduced in patients in chronic renal failure that is in turn associated with elevated precursors of tryptophan metabolism, including l-kynurenine and quinolinic acid, both of which have been implicated in the neurotoxic manifestations of chronic renal failure. Here we compare mean erythrocyte 4PYTP, and plasma tryptophan concentrations, in controls and four patient groups with renal impairment (10 per group) and confirmed a reduction in plasma tryptophan in patients on dialysis that corrected with renal transplantation. We found: An inverse correlation between plasma tryptophan and red cell 4PYTP concentrations (R²=0.44, P<0.001) when all patients were grouped together. Restoration of both tryptophan and 4PYTP concentrations to control values was only achieved following renal transplantation. 4PYTP was absent from erythrocytes in Molybdenum cofactor (MoCF) deficiency implicating aldehyde oxidase/dehydrogenase, a Molybdenum requiring enzyme. High 4PYTP erythrocyte concentrations in adenine or hypoxanthine-phosphoribosyltransferase deficient patients in severe uremia (113 μM and 103 μM), confirmed the lack of involvement of either enzyme in 4PYTP formation. We propose that 4PYTP is formed by a novel route involving the oxidation of the intermediates of NAD turnover from quinolinic acid by aldehyde oxidase.     

Freeze-fracture analysis of intramembrane particles of erythrocytes from normal, dystrophic, and carrier mice. A possible diagnostic tool for detection of carriers of human muscular dystrophy.

Careful examination of plasma membrane protein particles on fractures faces of erythrocyte plasma membranes from mice with muscular dystrophy, carriers of the sex-linked recessive gene for this disease, and from nondystrophic control animals revealed a 42% decrease in the number of intramembrane particles in erythrocytes of carriers (and a 33% decrease in dystrophic erythrocytes) compared with samples from control animals. These results support the notion that quantitative analysis of intramembrane particles in freeze-fractured erythrocyte plasma membranes may represent a new, rapid, simple, and highly accurate diagnostic tool for detection of carriers of human muscular dystrophy.