PubMed Health⌕ Search

Biomedical subjects

C R Scott

Publications and source records attributed to C R Scott.

At least 55 records · Page 3Linked to original sources
PubMed1989

Factor IXPortland: a nonsense mutation (CGA to TGA) resulting in hemophilia B.

Male siblings with severe hemophilia b were studied for the molecular defect responsible for their disorder. To define the precise DNA alteration, a 362-bp fragment in the first part of exon VIII of the factor IX gene was amplified and sequenced. A single-base-pair substitution of C----T at the nucleotide sequence 30875 was found which resulted in a nonsense mutation (TGA) and terminated the protein synthesis of factor IX at amino acid residue 252. The single-base change occurred as a classic CG dinucleotide alteration to TG (or CA), a common mechanism for point mutations in mammals.

Base Sequence↗
PubMed1988

An insertion within the factor IX gene: hemophilia BEl Salvador.

A patient with moderate to severe hemophilia B has been found to have a large insertion within his factor IX gene. The site of insertion is located in a DNA segment of approximately 0.8 kb between exon IV and an EcoRI site within intron D. The size of the DNA insertion is approximately 6 kb, and it contains at least two TaqI sites, two EcoRI sites, and one HindIII site. The insert probably originates from outside the FIX gene and does not represent an internal duplication. We propose that this abnormal FIX gene be called FIX El Salvador in recognition of the birthplace of the patient.

Adolescent↗
PubMed1987

MspI polymorphic site within the factor IX gene. Localization of the site and an improved method for detection.

We have localized the position of the MspI polymorphic site that exists within the factor IX gene. The location of the MspI polymorphic site is within intron D, 1.9 kb upstream from the beginning of exon V and 4 kb downstream from a known polymorphic TaqI site. The use of a specific genomic probe simplifies the interpretation of the MspI polymorphism by reducing the number of non-overlaping DNA fragments to three bands; 2.4, 3.4, and 5.8 kb.

Chromosome Mapping↗
PubMed1986

Laboratory studies of a family manifesting premature exfoliation of deciduous teeth.

In a previous publication, we described the clinical and radiographic findings of a family in which the children manifested premature exfoliation of the deciduous teeth. We now report for the same family the results of extensive laboratory studies performed on blood and urine, analysis of periodontal microflora, and a family pedigree. We demonstrated the presence of putative periodontal pathogens in the subgingival microflora, elevated levels of serum antibodies reacting to Bacteroides gingivalis, Capnocytophaga gingivalis, and C. sputigena in 2 of the children, and significantly suppressed monocyte chemotaxis in all 3 children. Phosphoethanolamine was found in the urine of the father and all 3 children, but not in the mother. Likewise, serum alkaline phosphatase was abnormally low for all 3 children, and was at the extreme low end of normal range for the father, but was normal for the mother. On the basis of the alkaline phosphatase and phosphoethanolamine measurements, we assigned a diagnosis of hypophosphatasia to the 3 children. Phosphoethanolamine and alkaline phosphatase were also abnormal in the paternal grandmother and her brother. The son of this brother who was deceased had a daughter manifesting premature loss of the primary teeth. The data are consistent with an autosomal dominant mode of transmission. In the light of our findings, hypoplastic cementum must be considered in the etiology of some forms of early-onset periodontitis.

Adult↗
PubMed1985

An intragenic deletion of the factor IX gene in a family with hemophilia B.

A family of seven patients severely afflicted with hemophilia B has been studied for their factor IX genes through the use of factor IX cDNA and genomic DNA probes. The patients had detectable (less than 10% of normal) factor IX antigen in urine and no detectable inhibitors in sera to factor IX protein. Based on the DNA hybridization analysis, these patients showed a partial intragenic deletion in their factor IX gene. The deletion included two exons (exons V and VI) coding for the amino acid sequence from number 85 to 195 of the factor IX protein. The deleted portion of the gene contained the entire factor IX activation peptide. The length of the deletion was estimated to be 10 +/- 0.3 kilobase pairs. This specific gene has been named FIXSeattle. In this family both the deletion and a Taq 1 restriction fragment length polymorphism can be used as a useful marker for accurate detection of female carriers of the deficient factor IX gene.

Chromosome Deletion↗
PubMed1983

The metabolism of deoxyguanosine and guanosine in human B and T lymphoblasts. A role for deoxyguanosine kinase activity in the selective T-cell defect associated with purine nucleoside phosphorylase deficiency.

Purine nucleoside phosphorylase (NP; EC 2.4.2.1) deficiency is associated with defective T-cell and normal B-cell immunity. Biochemical mechanisms were investigated by measuring deoxyguanosine and guanosine metabolism in normal T and B lymphoblasts and NP-deficient B lymphoblasts. Deoxyguanosine kinase activity was specifically measured by using an anti-NP antibody to prevent alternative-product formation. Kinase activity towards deoxyguanosine was significantly higher in T-cells, whereas NP activity was similar in both B- and T-cells. Only in T-cells was dGTP produced from exogenous deoxyguanosine, and this was prevented by the simultaneous addition of deoxycytidine, which resulted in a concomitant increase in GTP synthesis. Inhibition by 8-aminoguanosine of NP activity in T lymphoblasts increased formation of dGTP and decreased that of GTP from deoxyguanosine and decreased the formation of GTP from guanosine. These data suggest a central role for deoxyguanosine kinase activity in the T-cell selectivity of the immune defect.

B-Lymphocytes↗
PubMed1981

Use of genetic markers to certify fetal origin of cultured amniotic fluid cells.

Phenotypes of five polymorphic enzymes: red cell acid phosphatase, phosphoglucomutase, esterase D, adenosine deaminase, and 6-phosphogluconate dehydrogenase were determined in extracts of 24 amniotic fluid cell cultures and in the corresponding maternal red cells. Twenty-one of the 24 fetus/mother pairs can be distinguished by at least one of the markers. Thus, polymorphic enzyme markers may be useful in affirmation of fetal origin of cultured cells and to avoid possible diagnostic errors.

Acid Phosphatase↗
PubMed1980

Formycin B, purine nucleoside phosphorylase and lymphocyte function.

A genetic deficiency of purine nucleoside phosphorylase (NP) is associated with immune dysfunctin that specifically affects T cells. An absence of adenosine deaminase (ADA), the preceding enzyme in the pathway of purine recycling, is associated with failure of both T and B lymphocyte function. Formycin B, an analogue of inosine and an inhibitor of purine nucleosidase phosphorylase, was used in cell culture systems to stimulate deficiency of this enzyme. The cells used were normal circulating lymphocytes and lymphoblastoid cell lines (LCL) with T and B cell characteristics. Formycin B inhibited the growth of these cells, but its primary effect was found to be due to a mechanism other than purine nucleoside phosphorylase inhibition. The possibility that formycin B was inhibiting adenosine deaminase, for which it is a product analogue, was studied by the analysis of reaction progress curves using the integrated rate equation. The molecular structure of formycin B, whilst preventing its phosphorylytic cleavage by purine nucleoside phosphorylase, could enable this compound to function as a substrate for adenosine kinase. The resultant formation of formycin B nucleotide probably causes the observed inhibition of growth in cultured cells.

Adenosine Deaminase↗
PubMed1980

Purine nucleoside phosphorylase deficiency. Measurement of variant protein in four families with enzyme-deficient members by an enzyme-linked immunosorbent assay.

By a sensitive enzyme-linked immunosorbent assay, inactive variant nucleoside phosphorylase (NP) protein could be quantitated in red cells and cultured skin fibroblasts from the probands and parents in four families with enzyme-deficient members. Three different mutant alleles could be identified that, in the homozygous state, could lead to T-cell immunodeficiency. The mutant alleles formed proteins that differed from normal NP protein by their stability, catalytic activity, or isoelectric charge. Thus, sensitive biochemical techniques can demonstrate the presence of different mutations for purine NP. Any of the mutations can be responsible for a lack of purine NP and the development of the characteristic T-cell deficiency syndrome.

B-Lymphocytes↗
PubMed1979

Use of activated coagulation time to monitor heparin during cardiac surgery.

Activated coagulation time (ACT) for protamine reversal was monitored in 28 consecutive patients (Group 1) and a standard heparin-protamine protocol was used for an earlier series of 28 patients (Group 2). Although Group 1 received a significantly higher total heparin dose than Group 2 (p less than 0.01), the protamine dose for reversal was significantly less for the ACT group than for the controls (p less than 0.0005). The mean ratio of protamine to total heparin was 1 : 1 (range, 0.33 to 1.44) for the ACT group and 2 : 1 (range, 1.42 to 2.59) for the controls. There were no significant differences between the two groups in operative and postoperative blood loss, transfusion requirements, hematocrit, and partial thromboplastin time. This study shows that the ACT test did not reduce postoperative bleeding significantly when compared with our standard protocol. It also indicates that there is wide individual sensitivity to heparin and that significantly less protamine is required for reversal.

Blood Coagulation Tests↗
PubMed1978

Use of the integrated steady state rate equation to investigate product inhibition of human red cell adenosine deaminase and its relevance to immune dysfunction.

The analysis of progress curves using the integrated rate equation was applied to the adenosine deaminase-catalyzed conversion of adenosine to inosine. Adenosine deaminase was purified from human red blood cells of phenotypes ADA 1, ADA 2, and ADA 2-1. For all three types, no measurable product inhibition by inosine was observed. These results do not confirm the hypothesis that inosine accumulation in purine nucleoside phosphorylase deficiency causes adenosine deaminase inhibition, resulting in a common mechanism for the immune defects related to these two enzyme deficiencies.

Adenosine Deaminase↗
PubMed1978

The effect of Mycoplasma contamination on the in vitro assay of pyruvate dehydrogenase activity in cultured fibroblasts.

Cultured fibroblasts contaminated with mycoplasma were shown to have increased in levels of apparent pyruvate dehydrogenase and pyruvate dehydrogenase complex enzyme activity. The apparent pyruvate dehydrogenase specific activity was about 1000-fold greater in cultured Mycoplasma pneumoniae than in cultured fibroblasts. Several acid hydrolytic enzyme activities were also shown to be present in M. pneumoniae though a lower apparent specific activity than in cultured fibroblasts.

Cell Line↗
PubMed1978

Antenatal diagnosis of Krabbe's leucodystrophy: enzymatic and morphological confirmation in an affected fetus.

Galactosylceramide beta-galactosidase activity was assayed in cultured amniotic fluid cells from two pregnancies at risk for Krabbe's leucodystrophy. The elective termination of one pregnancy was carried out after demonstration of a severe deficiency of galactosylceramide beta-galactosidase activity. The diagnosis of Krabbe's leucodystrophy in the affected fetus was confirmed enzymatically by a deficiency of galactosylceramide beta-galactosidase inbrain, liver, kidney, and cultured skin fibroblasts, and histologically by the ultrastructural demonstration of the typical intracellular inclusions in cells of the spinal cord.

Amniocentesis↗