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Biomedical subjects

E Beutler

Publications and source records attributed to E Beutler.

At least 163 records · Page 9Linked to original sources
PubMed1993

Study of glucose-6-phosphate dehydrogenase: history and molecular biology.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency was discovered in the 1950s. The history of the development of knowledge about G6PD deficiency is reviewed here. In the first decade after its discovery, the clinical manifestations of G6PD deficiency began to be understood. In the second decade, attention was focused on the degree of variability of this enzyme and the distinction of the various biochemical variants from one another. In the last decade, it has been possible to understand the mutations that effect this enzyme at the DNA level. Some 40 different mutations have now been characterized. Analysis of these mutations indicates that, while diversity sometimes exists within a mutation considered biochemical homogeneous, more often variants thought to be distinct prove to be identical. The study of G6PD mutations is beginning to provide insight into structure-function relationships.

Genetic Variation↗
PubMed1993

Variants of glucose-6-phosphate dehydrogenase are due to missense mutations spread throughout the coding region of the gene.

Glucose-6-phosphate dehydrogenase (G6PD) is remarkable for its genetic diversity in humans. Many variants of G6PD have been described with wide ranging levels of enzyme activity and associated clinical symptoms. Fifty-eight different mutations have now been identified and these account for 97 named G6PD variants. The mutations are almost exclusively missense mutations, causing single amino acid substitutions. They are spread throughout the coding region of the gene, although there appears to be a cluster of mutations that cause a more severe clinical phenotype towards the 3' end of the gene. The absence of large deletions, frameshift mutations and nonsense mutations is consistent with the notion that a total lack of G6PD activity would be lethal.

Amino Acid Sequence↗
PubMed1993

Identification of six new Gaucher disease mutations.

The four most common mutations account for 97% of the Gaucher disease-producing alleles in Jewish patients and 75% of the alleles in non-Jewish patients. Although at least 15 other mutations and some examples of gene conversion and/or fusion genes have been described, a number of mutations remain unidentified. We have now identified six new mutations, a deletion of a C at the 72 position of the cDNA, a 481C-->T mutation (122Pro-->Ser), a 751T-->C (212Tyr-->His), a 1549G-->A (478Gly-->Ser), a 1604G-->A (496Arg-->His), and a 55-bp deletion. All but one of these were found in single families. The 1604A mutation, however, was observed in four unrelated individuals.

Adolescent↗
PubMed1993

Frequency of glucose-6-phosphate dehydrogenase (G6PD) mutations in Chinese, Filipinos, and Laotians from Hawaii.

In a Hawaii Hereditary Anemia Screening Project, 4,984 participants were tested for glucose-6-phosphate dehydrogenase (G6PD) deficiency by a filter paper blood spot fluorescence test. Abnormal samples and suspected heterozygotes were checked by quantitative G6PD assay (normal 4.5 to 14 units/g Hb). G6PD was deficient (< 1.5 units/g Hb) in 188 of 2,155 males; 7 other males had low activity (1.5 to 2.8 units/g Hb). The gene frequency, estimated from males after excluding referred and related cases, was 0.037 for Chinese, 0.134 for Filipinos, and 0.203 for Laotians. Among 2,829 females tested, family data showed 111 females were obliged to be at least heterozygous, regardless of G6PD activity, and 43 others had low G6PD activity. Most heterozygotes probably remained undetected by G6PD screening. In 28 females, activity was under 10%; in another 9 females, activity was < 1.5 units/g Hb. Since only 25 homozygotes would be predicted, this apparent excess of females with deficient activity could be due to unequal X-inactivation in some heterozygotes. DNA analysis by polymerase chain reaction amplification and special analytic procedures revealed 10 different missense mutations in 75 males. The nucleotide 835 A-->T and 1360 C-->T transitions were first detected in this Hawaiian Project; we found that the nucleotide 1360 mutation was the most common cause of G6PD deficiency in Filipinos. This is the first report of G6PD screening and analysis of molecular G6PD mutations in Filipino and Laotian populations.

Adult↗
PubMed1993

Molecular analysis of G6PD variants in northern Italy: a study on the population from the Ferrara district.

In the Ferrara district, an area south of the Po delta, four different variants of glucose-6-phosphate dehydrogenase (G6PD;E.C.1.1.49) have been described as a result of biochemical characterization of the enzyme protein: one was G6PD Mediterranean (G6PD Med) and three were local variants named Ferrara I, II, and III. The Ferrara I variant was recently analysed at the DNA level and shown to correspond to G6PD A376G/202A, while the mutations causing the variants II and III, still remain unknown. We analysed the G6PD coding region of 18 apparently unrelated G6PD deficient subjects, whose families have lived in the Ferrara district for at least three generations: 12 subjects had G6PD Med563T/1311T, 3, G6PD Santamaria376G/542T and 2, G6PD A-376G/202A. In one subject we found a new mutation, a G-->A transition at nucleotide 242 causing an Arg-->His amino-acid replacement at position 81. We named this new variant G6PD Lagosanto242 A. Phenotypically the enzyme has nearly normal kinetic properties and appears different from the variants Ferrara II and III.

Child↗
PubMed1993

GPI Mount Scopus--a variant of glucosephosphate isomerase deficiency.

Glucosephosphate isomerase (GPI) deficiency is an unusual cause of hereditary nonspherocytic hemolytic anemia. The disease, inherited as an autosomal recessive disorder, is most often manifested by symptoms and signs of chronic hemolysis, ameliorated by splenectomy. We recently diagnosed GPI deficiency in a 23-year-old Ashkenazi Jewish man who displayed the typical clinical course of this disorder. The biophysical characteristics of the GPI variant are slow electrophoretic mobility, presence of only one of the two bands normally present, and extreme thermolability. To the best of our knowledge, this is the first report of GPI deficiency in a patient of Jewish descent, and we propose to designate this enzyme variant "GPI Mount Scopus".

Adult↗
PubMed1993

Gaucher disease mutations in non-Jewish patients.

The DNA from 64 non-Jewish patients with Gaucher disease was examined for 29 different glucocerebrosidase mutations that are known to cause the disease. The most common was mutation 1448C and the second most common 1226G. Twenty of the mutations remained unidentified. These results were compared to those obtained from 122 Jewish patients, in whom the most common mutations were 1226G and 84GG. Among the non-Jewish patients 15.6% of the mutations remained unidentified, while among the Jewish patients only 1.2% remained unidentified, and even screening for the five most common mutations identified all but 2.9% of the Jewish mutations. The greater diversity of mutations among the non-Jewish patients has important implications with respect to DNA-based screening, diagnosis and counselling.

Adolescent↗
PubMed1993

Binding, internalization, and degradation of mannose-terminated glucocerebrosidase by macrophages.

Mannose-terminated glucocerebrosidase (alglucerase; Ceredase) was designed for enzyme replacement therapy in Gaucher disease to take advantage of mannose receptor-mediated endocytosis by macrophages. To provide a rational basis for designing enzyme replacement therapy protocols, we examined the in vitro binding, uptake, and degradation of alglucerase by murine and human macrophages. Both were found to have approximately 500,000 mannose-dependent receptors for alglucerase per cell with a Kd of 10(-7) M at 0 degrees C. In contrast, the number of binding sites for mannose-bovine serum albumin (mannose-BSA), the classical ligand for the mannose receptor, was only approximately 20,000 with a Kd of 10(-8) M. Alglucerase was also bound in a mannose-dependent manner by cells that lack the capacity to bind mannose-BSA, such as Cos-1 cells, endothelial cells, and peripheral blood monocytes. The fact that the binding of alglucerase by macrophages was mediated principally by a receptor distinct from the classical mannose receptor that binds mannose-BSA was confirmed by differential inhibitors, viz., alpha-methyl-glucoside, fucose, and mannose-BSA, and by its independence on Ca2+. Uptake of alglucerase by macrophages at 37 degrees C was concentration dependent and half maximal at 10(-6) M. However, at a concentration of 10(-7) M, only 0.5% of the added alglucerase was incorporated into macrophages and approximately 50% of the alglucerase taken up was quickly released into the medium. Endothelial cells also manifest mannose-dependent binding and uptake of alglucerase and may therefore account for a large proportion of the infused alglucerase. Our data suggest that only a small amount of the alglucerase administered is effectively delivered to macrophages and that a more efficiently targeted enzyme might have a marked therapeutic advantage over mannose-terminated glucocerebrosidase.

Animals↗
PubMed1993

2-Chlorodeoxyadenosine dose escalation in nonhematologic malignancies.

PURPOSE: We performed a dose-escalation study of 2-chlorodeoxyadenosine (2-CdA) in solid tumors to determine the maximum-tolerated dose (MTD) and define its toxicity profile at higher doses. PATIENTS AND METHODS: Twenty-one patients, seven with malignant astrocytoma, twelve with metastatic melanoma, and two with metastatic hypernephroma, were enrolled onto the study. Patients were entered onto cohorts that received 0.10, 0.15, or 0.20 mg/kg/d of 2-CdA by continuous intravenous infusion for 7 days every 28 days. 2-CdA levels were determined by radioimmunoassay. In tumor tissue samples, deoxycytidine kinase (dCK) levels were measured by both enzyme activity and immunoreactive protein analysis. RESULTS: Of seven patients treated with 2-CdA at 0.1 mg/kg/d, one experienced grade 3 or 4 myelotoxicity. Of 11 patients treated at 0.15 mg/kg/d, four experienced myelotoxicity, two after a single course of 2-CdA. All three patients who received 2-CdA at 0.2 mg/kg/d experienced myelosuppression. Neurologic events occurred in two patients, both with malignant melanoma. Two of seven patients (28.6%) with astrocytomas obtained partial responses with a median duration of 8 months. 2-CdA penetrated the blood-brain barrier. An association was found between dCK levels as measured by enzymatic activity and immunoreactive proteins, but this did not correlate with 2-CdA tumor responsiveness. CONCLUSION: The MTD for 2-CdA delivered as a 7-day intravenous infusion in patients with nonhematologic malignancies was determined to be 0.1 mg/kg/d, the same as the MTD for patients with hematologic malignancies. There was no clinical correlation with dCK expression and response to 2-CdA. The responses noted in patients with malignant astrocytoma warrant further phase II study.

Adult↗
PubMed1993

2-Chlorodeoxyadenosine: hairy cell leukemia takes a surprising turn.

2-Chlorodeoxyadenosine (2CdA; Cladribine; Leustatin) was developed as a result of the discovery that the death of lymphocytes in hereditary adenosine deaminase deficiency was the result of the accumulation of deoxynucleotides, specifically in lymphocytes, because of their unique enzymatic profile. This deoxyadenosine analog was selected from 25 candidate compounds because it was resistant to deamination by ADA and because it had a favorable therapeutic index. The lymphoid specific action of this drug is a function of the high deoxycytidine kinase and low 5' nucleotidase activity of lymphocytes. The drug appears to trigger apoptosis, very likely by preventing the repair of nicks in double-stranded DNA. Accordingly, 2-CdA has been found effective against a variety of lymphoid neoplasms. Hairy cell leukemia has proved to be most sensitive to its action, with approximately 80% of patients achieving a complete, long-lasting remission after a single five- or seven-day infusion. 2-CdA also shows promise in the treatment of autoimmune disorders.

2-Chloroadenosine↗
PubMed1993

Gaucher disease: gene frequencies in the Ashkenazi Jewish population.

DNA from over 2,000 Ashkenazi Jewish subjects has been examined for the four most common Jewish Gaucher disease mutations, which collectively account for about 96% of the disease-producing alleles in Jewish patients. This population survey has made possible the estimation of gene frequencies for these alleles. Eighty-seven of 1,528 individuals were heterozygous for the 1226G (N370S) mutation, and four presumably well persons were homozygous for this mutation. The gene frequency for the 1226G allele was calculated to be .0311, and when these data were pooled with those obtained previously from another 593 Jewish subjects, a gene frequency of .032 with a standard error of .004 was found. Among 2,305 normal subjects, 10 were found to be heterozygous for the 84GG allele, giving a gene frequency of .00217 with a standard error of .00096. No examples of the IVS2(+1) mutation were found among 1,256 samples screened, and no 1448C (L444P) mutations were found among 1,528 samples examined. Examination of the distribution of Gaucher disease gene frequencies in the general population shows that the ratio of 1226G mutations to 84GG mutations is higher than that in the patient population. This is presumed to be due to the fact that homozygotes for the 1226G mutation often have late-onset disease or no significant clinical manifestations at all. To bring the gene frequency in the patient population into conformity with the gene frequency in the general population, nearly two-thirds of persons with a Gaucher disease genotype would be missing from the patient population, presumably because their clinical manifestations were very mild.

Base Sequence↗
PubMed1993

Molecular characterization of glucose-6-phosphate dehydrogenase variants from Brazil.

Electrophoretic surveys of 7794 individuals from different regions of Brazil and a study of subjects with hemolytic anemia have disclosed 9 putative G6PD variants in addition to the B, A, A-, and Mediterranean types. No variants were found among the 3739 Brazilian Indians tested. Four variants underwent DNA analysis. Three were identified with the Mediterranean, Seattle, and Anaheim types, but the fourth variant was previously undescribed and we propose to designate it G6PD São Borja.

Brazil↗
PubMed1992

A less costly regimen of alglucerase to treat Gaucher's disease.

BACKGROUND: Alglucerase (Ceredase) provides effective enzyme-replacement treatment for patients with Gaucher's disease, but at the usually recommended dose of 60 U per kilogram of body weight every two weeks (130 U per kilogram per month), it costs $382,200 per year for a 70-kg patient. Theoretical considerations suggest that more frequent administration would be more efficient. METHODS: Fourteen patients with type 1 Gaucher's disease that was moderately severe to severe were given 30 U of alglucerase per kilogram per month, in divided doses given either daily or three times weekly, or 120 U given three times weekly. The effect of the treatment on the size of the liver and spleen and on blood counts was compared with published data on patients who received a total dose four to five times as large as the lower dose we used and who received treatment every two weeks. RESULTS: The response to 30 U of alglucerase per kilogram per month, fractionated into three or seven doses weekly, was approximately the same as that reported after the administration every two weeks of a dose four or five times as large, given in the large infusions usually recommended. A fourfold increase in the dose given three times weekly, from 2.3 to 9.2 U per kilogram, did not substantially increase the rate of improvement. CONCLUSIONS: The treatment of Gaucher's disease with smaller total doses of alglucerase given more frequently yields satisfactory results. A dose of 2.3 U per kilogram three times weekly yields major financial benefits with no sacrifice of therapeutic effect. Even taking into account the increased ancillary costs of more frequent administration, this method of administering alglucerase reduces the annual cost of the drug for a 70-kg patient to about $100,000.

Administration, Oral↗