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Biomedical subjects

W Endres

Publications and source records attributed to W Endres.

At least 19 recordsLinked to original sources
PubMed2000

Characteristics of L-ornithine: 2-oxoacid aminotransferase and potential prenatal diagnosis of gyrate atrophy of the choroid and retina by first trimester chorionic villus sampling.

A deficiency of the mitochondrial matrix enzyme L-ornithine: 2-oxoacid aminotransferase causes gyrate atrophy of the choroid and retina with hyperornithinemia (MIM 258870), a blinding degenerative disease, which is inherited as an autosomal recessive trait. We have developed a sensitive microradioisotopic method for enzyme assay by using 2-oxo-[5-14C] glutarate as the substrate and performing the separation of the product, [5-14C] glutamate from the substrate on a cation-exchange column. The enzyme activity was determined in human and rat tissues and in cultured cells. The enzyme activity in fibroblasts from a patient was deficient and that of the parents ranged between 25 and 60% of the control values. In addition we have found the enzyme expressed in native and cultured chorionic villi indicating a potential detection of the disease during the first trimester of pregnancy.

Animals↗
PubMed1997

Quantitation of total homocysteine in human plasma by derivatization to its N(O,S)-propoxycarbonyl propyl ester and gas chromatography-mass spectrometry analysis.

Much evidence supports the hypothesis that mild or moderate hyperhomocysteinaemia represents an important and independent risk factor for occlusive vascular diseases. Therefore, the accurate and reliable determination of total plasma homocysteine has gained major importance for risk assessment. Furthermore, it can help in the detection of folate and vitamin B12 deficiency. This has prompted us to develop a sensitive gas chromatography-mass spectrometry (GC-MS) method in order to quantify total homocysteine in human plasma. Prior to chromatography, reduced homocysteine was released from disulfide bonds by incubation with excess dithiothreitol and converted into its N(O,S)-propoxycarbonyl propyl ester by derivatization with n-propyl chloroformate. Aminoethylcysteine served as internal standard. The method proved to be highly linear over the entire concentration range examined (corresponding to 0-266 microM homocysteine) and showed intra-assay and inter-assay variation (relative standard deviations) of approximately 5 and 5-10%, respectively. External quality control by comparison with duplicate analysis performed on a HPLC-based system revealed satisfactory correlation. The newly developed GC-MS based method provides simple, reliable and fast quantification of total homocysteine and requires only inexpensive chemicals, which are easy to obtain.

Circadian Rhythm↗
PubMed1997

Inherited metabolic diseases affecting the carrier.

The objective of this review is to draw attention to those inherited metabolic traits which are potentially harmful also for the carrier, and to outline preventive measures, at least for obligate heterozygotes, i.e. parents of homozygous children. Concerning carriers of food-dependent abnormalities, early vascular disease in homocystinuria, hyperammonaemic episodes in ornithine transcarbamylase deficiency, presenile cataracts in galactosaemia as well as galactokinase deficiency, spastic paraparesis in X-linked adrenoleukodystrophy, and HELLP syndrome in mothers of babies with long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency have to be mentioned. In the group of food-independent disorders, clinical features in carriers may be paraesthesias and corneal dystrophy in Fabry disease, lens clouding in Lowe syndrome, lung and/or liver diseases in alpha 1-antitrypsin deficiency, and renal stones in cystinuria type II and III. Finally, two monogenic carrier states are known which in pregnant individuals could possibly afflict the developing fetus, i.e. heterozygosity for galactosaemia and for phenylketonuria. Elevated levels of galactose-1-phosphate have been found in red blood cells of infants heterozygous for galactosaemia born to heterozygous mothers. Aspartame in very high doses is reported to increase blood phenylalanine levels in heterozygotes for phenylketonuria, thus being a risk for the fetus of a heterozygous mother. For some of these carrier states preventive measures can be recommended, e.g. restriction of lactose in parents and heterozygous grandparents of children with galactosaemia and galactokinase deficiency as well as transiently in infants heterozygous for galactosaemia, dietary supplementation with monounsaturated fatty acids in symptomatic carriers for X-linked adrenoleukodystrophy, avoidance of smoking and alcohol in heterozygotes for alpha 1-antitrypsin deficiency, avoidance of episodes of dehydration in heterozygotes for cystinuria, and restriction of aspartame in pregnant women.

Diet↗
PubMed1996

Simplified PCR-SSO procedure for DQA and DQB typing. Simultaneous hybridization of two probes to one membrane.

To simplify DQA and DQB oligotyping, we applied our improved PCR-SSO procedure for DR typing. We used 12 oligonucleotide probes for DQA typing and 18 for DQB typing. Oligonucleotide probes that require the same hybridization and stringent washing conditions were selected as pairs for simultaneous hybridization to a dot-blot membrane containing various DNA samples. One probe of each pair was labeled with digoxigenin and the other with biotin. After hybridization, the dot-blot membranes were incubated with a mixture of conjugates. Specific binding of the corresponding DNA probes was visualized on an X-ray film using a chemiluminescent substrate (CSPD) and by staining using a chromogenic substrate (TMB). This approach, previously employed for DR typing, is also suitable for DQA and DQB oligotyping and significantly reduces the labor inherent in PCR-SSO typing.

Genotype↗
PubMed1996

No significant influence of HLA determinants on susceptibility to hepatitis C virus infection in Caucasian patients with end-stage renal disease.

In hepatitis C, both susceptibility to infection and the course of disease may depend on differences in the immune response. As the major histocompatibility complex (MHC) plays a crucial role in antigen presentation, we investigated a possible relationship between susceptibility to hepatitis C virus (HCV) infection and human leucocyte antigen (HLA) alleles. Therefore, phenotype frequencies of HLA were compared in 186 anti-HCV positive patients with end-stage renal disease (ESRD) to 328 anti-HCV negative patients with ESRD. HLA class I alleles were determined serologically and HLA class II alleles (DRB1, DQA1, DQB1) by the polymerase chain reaction sequence-specific oligonucleotide (PCR-SSO) technique. Additionally, in anti-HCV positive patients we looked for a relationship between the activity of hepatitis C (indicated by elevation of transaminases or the presence of viremia) and HLA determinants. For the three criteria (antibody status, elevation of transaminases and viremia) a significant association to HLA alleles was not found in patients with ESRD. This suggests that neither susceptibility to HCV infection nor the biochemical activity of hepatitis and HCV-RNA positivity seem to be strongly related to HLA status in Caucasian patients with end-stage renal disease.

Adult↗
PubMed1996

Relationship between human leukocyte antigen determinants and courses of hepatitis B virus infection in Caucasian patients with end-stage renal disease.

BACKGROUND: Divergent results have been reported with regard to the relationship between the course of hepatitis B virus (HBV) infection and the human leukocyte antigen (HLA) determinants. The aim of the present study was to investigate the phenotype frequencies of HLA class-I and -II alleles in Caucasians with and without HBV infection. METHODS: Fifty-eight patients with persistent HBV infection (group 1), 119 patients with resolved HBV infection (group 2), and 106 patients neither infected by HBV nor vaccinated against HBV (group 3) were analyzed. All patients had end-stage renal disease. HLA class-I antigens were serologically determined. For HLA class-II typing we performed DRB1, DQA1, and DQB1 genotyping using a polymerase chain reaction-sequence-specific oligonucleotide procedure. RESULTS: Compared with group 2, group 1 showed increased frequencies of HLA-B8, DR3 (P < 0.05), A30, DQA1*0501 (P < 0.01), and a decreased frequency of HLA-B12 (P < 0.05). Decreased frequencies of HLA-B27, B40, DR13, and DQ1*0604 (P < 0.05) and an increased frequency of HLA-B35 (P < 0.05) were found in groups 1 and 2 compared with controls (group 3). None of the differences detected in the phenotype frequencies of HLA alleles were statistically significant after correction. CONCLUSIONS: We conclude that the susceptibility to HBV infection and the different courses of HBV infection are not strongly related to HLA status in Caucasians.

Adult↗
PubMed1994

Effect of high-protein meal plus aspartame ingestion on plasma phenylalanine concentrations in obligate heterozygotes for phenylketonuria.

The effect of a protein-rich meal alone or in combination with 85 mumol/kg body weight aspartame (APM) on plasma phenylalanine and large neutral amino acids (LNAA) was evaluated in obligate heterozygotes for phenylketonuria (PKU) and normal subjects (controls). Thirteen PKU heterozygotes (seven women, six men) and 13 controls (five women, eight men) ingested a 12-noon meal providing approximately 303 mumol/kg Phe. In addition, 10 PKU heterozygotes (five women, five men) and 10 controls (five women, five men) ingested the same meal with 85 mumol/kg APM (providing 75 mumol/kg Phe). Plasma amino acids were analyzed at baseline (-4 and 0 hours) and at 1, 3, and 20 hours after the meal or meal plus APM. Compared with the meal alone, ingestion of the meal plus APM significantly increased plasma Phe concentrations in both controls and PKU heterozygotes. Mean plasma Phe values were higher for controls at 1 hour (95 +/- 7 mumol/L) and for PKU heterozygotes at 3 hours (153 +/- 21 mumol/L). After the addition of APM to the meal, the highest mean plasma Phe concentration was only slightly greater than the usual postprandial range for both controls and PKU heterozygotes. Ingestion of the meal did not increase the plasma Phe/LNAA ratio in either controls or PKU heterozygotes. Compared with baseline, the plasma Phe/LNAA ratio increased significantly 1 hour after combined ingestion of the meal plus APM in both groups (P = .020 and P = .008, respectively); however, the ratios were well below the range of Phe/LNAA values in individuals with mild hyperphenylalaninemia, who are clinically normal and do not require a Phe-restricted diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

A polymerase chain reaction-sequence-specific oligonucleotide procedure for HLA class II typing using biotin- and digoxigenin-labeled probes simultaneously in hybridization.

To simplify PCR-SSO HLA-DRB generic typing, we labeled eight of 15 oligonucleotide probes with DIG and the others with biotin, and hybridized each dot blot with both a biotin-labeled probe and a DIG-labeled probe simultaneously. We chose oligonucleotide pairs which require the same hybridization and stringent washing conditions and do not compete with each other during hybridization. After incubation with a mixture of anti-DIG Fab fragment-alkaline phosphatase and streptavidin-peroxidase conjugates, specific binding of the DIG-labeled probe was revealed by a chemiluminescent substrate (CSPD) and specific binding of the biotin-labeled probe was subsequently visualized by a chromogenic substrate (TMB). The sensitivity of both probes was similar and gave comparable hybridization signals. Using this simplified procedure, the number of hybridizations or dot blots can be reduced to half the usual amount and the labor involved in PCR-SSO typing significantly reduced.

Base Sequence↗
PubMed1994

[Familial investigations of carriers of Rh 33].

The erythrocytes of a blood donor (P) showed an unusual pattern with anti-D sera: no agglutination with incomplete sera, and a strong agglutination with 2 out of 5 complete, monoclonal sera. These findings suggested the presence of an Rh 33, which was then confirmed in two external laboratories as the genotyp R0Har. Using anti-e sera, the titer scores of the cells of P were comparable with those of Ee cells but were only half as high as the scores of ee cells. This is consistent with a weak e in R0Har. The red cells of the donor's daughter (T) gave a positive reaction with all anti-D sera, but we observed no or only weak agglutination with several anti-e sera. It is very probable that T is also carrier of R0Har.

Blood Donors↗
PubMed1994

[HLA-DR typing using PCR-SSO with simultaneous hybridization of each dot blot membrane with a digoxigenin- and a biotin-marked probe].

Here we present a PCR-SSO procedure designed to simplify HLA-DR typing. We labelled 8 of a total of 16 oligonucleotide probes with digoxigenin, the others with biotin, and formed 8 pairs, each containing a digoxigenin- as well as a biotin-labelled probe. Each pair was hybridized simultaneously to one of eight dot blot membranes containing the DNA to be typed. Specific binding was detected by incubation with a mixture of the appropriate conjugates followed by sequential addition first of a chemiluminescent substrate to detect the digoxigenin-labelled probe and then a chromogenic substrate for detection of the biotin-labelled probe. With this procedure, the specific binding of two different probes to the same dot blot membrane could be evaluated, considerably reducing the labor inherent in PCR-SSO typing.

Biotin↗
PubMed1993

Multiple respiratory chain abnormalities associated with hypertrophic cardiomyopathy and 3-methylglutaconic aciduria.

In a 4.5-month-old boy presenting with marked muscular hypotonia in the neonatal period, hepatomegaly, cardiac hypertrophy, recurrent hypoglycemia, metabolic acidosis, and secondary carnitine deficiency, there was a considerable urinary excretion of 3-methylglutaconic and 3-methylglutaric acid. Estimation of 3-methylglutaconyl-CoA hydratase, 3-hydroxy-3-methylglutaryl-CoA lyase and initial enzymatic steps of cholesterol biosynthesis in cultured fibroblasts and in different tissues postmortem revealed no enzyme deficiency. Analyses of the respiratory chain in postmortem tissues demonstrated severe impairment of complex I (NADH ubiquinone oxidoreductase) and complex IV (cytochrome c oxidase) activities in skeletal muscle and reduced complex IV activity in heart.

Acidosis, Lactic↗
PubMed1992

Hartnup syndrome, progressive encephalopathy and allo-albuminaemia. A clinico-pathological case study.

Clinical, biochemical, neuropathological and neurochemical findings in a case of Hartnup syndrome are reported. After initially normal development, the affected girl suffered progressive neuropsychiatric decline with statomotor and mental retardation and intractable seizures and died at the age of 2 years. Postmortem neuropathological and neurochemical investigations showed a combination of extensive neuronal degeneration and cerebral dysmyelination. Pathogenetic hypotheses and the relationship between neuropsychiatric disease and Hartnup syndrome are discussed. Additionally, a fast type bisalbuminaemia present in the girl and her mother is described.

Amino Acids↗
PubMed1992

[Differential diagnosis and therapy of various forms of hyperphenylalaninemia: facts and fiction].

The various conditions which can lead to elevated blood phenylalanine (PHE) levels must be differentiated promptly in the neonatal period so that the correct treatment can be implemented as soon as possible. In order to exclude the rare tetrahydrobiopterin (BH4) deficiency, it is advisable to perform a BH4 loading test and to determine the renal excretion of pterins, as well as the dihydropteridine reductase activity in erythrocytes. The practical consequence of differentiating the various types of PHE hydroxylase deficiency is that with both phenylketonuria (PKU; PHE greater than 20 mg/dl) and hyperphenylalaninemia (HPA) with PHE levels above 15 mg/dl a diet restricted in PHE is initiated, whereas HPA infants with PHE levels below 8 mg/dl are fed normally. In the case of PHE concentrations between 8 and 15 mg/dl standardized protein intake can be used to decide whether a diet restricted in PHE or only a restriction of protein intake has to be instituted. Optionally a protein challenge can be performed at the age of six months in order to evaluate the individual PHE tolerance. Psychometric investigations of PKU patients after diet discontinuation at different ages, as well as animal studies are in favour of a diet-for-life. The diet in PKU patients is known to lead to some side effects such as bony changes and amino acid imbalance, as well as deficiency of selenium and carnitine. Finally, great efforts have to be made in order to avoid the increasing danger of PHE embryofetopathy in the offspring of PKU mothers (maternal PKU).

Biopterins↗