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Biomedical subjects

D B Amos

Publications and source records attributed to D B Amos.

At least 55 records · Page 3Linked to original sources
PubMed1980

Association of HLA-linked hemochromatosis with idiopathic refractory sideroblastic anemia.

Five of seven patients with idiopathic refractory sideroblastic anemia carried an HLA-A3 alloantigen (relative risk, 7.3; P = 0.02). The significance of this association was strengthened by study of two pedigrees. An abnormality in iron metabolism was found in two siblings who had an HLA-A3,B14 haplotype in common with the first proband. A second proband with idiopathic refractory sideroblastic anemia had clinically manifest hemochromatosis. His brother had clinically manifest hemochromatosis but not sideroblastic anemia. This proband and his brother shared only the HLA-A3,B12 haplotype. Our findings infer that patients with idiopathic refractory sideroblastic anemia carry a single allele for hemochromatosis, that this allele accounts for the increased iron loading in this form of anemia, and that clinically manifest hemochromatosis may develop in an occasional patient with only one allele for hemochromatosis in the presence of the sideroblastic factor.

Adult↗
PubMed1980

Homozygosity for hemochromatosis: clinical manifestations.

We identified 35 homozygotes for hemochromatosis through pedigree studies. Thirteen were asymptomatic. Arthropathy was present in 20, hepatomegaly in 19, transaminasemia in 16, skin pigmentation in 15, splenomegaly in 14, cirrhosis in 14, hypogonadism in six, and diabetes in two. No homozygote was in congestive failure. Only one had the triad of hepatomegaly, hyperpigmentation, and diabetes. Serum iron was increased in 30 of 35, transferrin saturation was increased in all 35, serum ferritin in 23 of 32, urinary iron excretion after deferoxamine in 28 of 33, hepatic parenchymal cell stainable iron in 32 of 33, and hepatic iron in 27 of 27. Iron loading was 2.7 times greater in men than in women. No female had hepatic cirrhosis. Diagnosis of asymptomatic hemochromatosis is important because organ damage may be prevented by early therapy. Clinical diagnosis of early hemochromatosis is difficult. Persons with unexplained elevation of transferrin saturation should be studied for hemochromatosis.

Adolescent↗
PubMed1979

Hereditary hemochromatosis. Phenotypic expression of the disease.

Previous studies have shown that hemochromatosis is an inherited, autosomal-recessive disease and that the gene is closely linked to the HLA locus on chromosome 6. We obtained a lod score for linkage of +9.8 for a recombination fraction of 0.0 and a gene frequency of 0.056, the frequency estimated in this population. We studied the phenotypic expression of the disease in 261 members of 10 pedigrees. In heterozygotes over 20 years of age, there was an intermediate increase in transferrin saturation and a limited increase in hepatic iron but no clinical manifestations. In male heterozygotes, the average amount of iron in the liver increased from about 0.2 to 1.3 g. Abnormal homozygotes accumulated iron progressively with time, with men accumulating about 18 g in the liver. All measurements of iron status were increased in abnormal homozygotes. Hemochromatosis is inherited as an autosomal-recessive disease, with partial biochemical expression in heterozygotes.

Adolescent↗
PubMed1979

HLA serum screening based on an heuristic solution of the set cover problem.

A computer program initially written by the Milwaukee Blood Bank has been modified to use a new algorithm for the assignment of HLA specificities to antisera. The assignment is based on the reactions of cells with known specificities. Specificities which are present only on cells which do not react are first ruled out. This step is followed by one or more steps in which the 'least reactive' specificities are ruled out. The rationale for the algorithm is discussed and an example is presented.

Computers↗
PubMed1979

Mixed lymphocyte reactions in serum-free medium.

Tissue culture medium supplemented with bovine serum albumin (BSA), rather than human serum, was found capable of supporting the proliferative response of cryopreserved human lymphocytes to allogeneic cells in a one-way mixed lymphocyte culture. Although total tritiated thymidine uptake was lower in BSA supplemented cultures than in serum supplemented cultures, stimulation indices were equivalent. Using 0.5% (w/v) BSA, peak tritiated thymidine uptake was observed on day 5 using 2 X 10(5) responders and 4X 10(5) stimulators per microtitre well. Calf skin gelatin was also found capable of substituting for serum, but gave lower levels of proliferation. Use of BSA offers distinct advantages for investigating the proliferative responses of human lymphocytes in serum-free media.

B-Lymphocytes↗
PubMed1979

B cell antigens of Black Americans.

Fourty-four unrelated North American Blacks and one Black family were tested for B-cell specific antigens with 7th International Workshop antisera. DR specificities were clearly defined in this group, but were generally less frequent than reported for Black Americans in the 7th Workshop report and were most similar in frequency to those reported for African Blacks. Five new B-cell specificities (DuB40-43, 45) were identified. In contradistinction to Caucasians, Black Americans type for HLA-D with homozygous typing cells failed to exhibit strong linkage disequilibrium between D and DR types.

B-Lymphocytes↗
PubMed1979

Cross-reactions of HLA antibodies: VII. Rate of sensitization and serological specificity.

Varying the sensitization time of the complement-dependent antibody mediated cytotoxicity test, while carefully controlling other test conditions, has enabled us to characterize the subtle reactivities of several broadly reactive sera. In particular, we can discriminate between classes of cells, e.g., HLA-B7 from B27; subclasses cells, e.g., Bw51 from Bw52; and cells carrying new antigens, e.g., Ao79. This manipulation of the cytotoxicity test is discussed in view of its usefulness in separating primary from cross-reactive specificities and in detecting new specificities.

Adult↗
PubMed1979

HLA histocompatibility antigens in a Polynesian population -- Cook islanders of Mauke.

Polynesians living on the island of Mauke in the Cook Island group were typed for HLA-A and -B locus antigens. The Mauke population has restricted HLA polymorphism, with five A-locus antigens and four B-locus antigens accounting for a majority of the HLA phenotypes. Although some differences in antigen frequency were found when Mauke Islanders were compared with Polynesians from Easter Island and Samoa, the Mauke Islanders were closer in their HLA antigenic profile to polynesians than to Melanesians.

Epitopes↗
PubMed1978

Natural killing and antibody-dependent cellular cytotoxicity are independent immune functions in the Minnesota miniature swine.

Peripheral blood lymphocytes from Minnesota miniature pigs were tested for natural killing (NK) and antibody-dependent cellular cytotoxicity (ADCC) in a 2- to 4-hr 51Cr release assay against human myeloid and lymphoid tumor target cells. Adult specific pathogen-free and germfree animals exhibited normal levels of activity in both assays. In addition, the NK and ADCC activities of peripheral blood lymphocytes from colostrum-deprived newborn piglets were examined. These animals were obtained by hysterectomy and previously shown to be immunologically "virgin." We found that these newborn piglets exhibited normal ADCC but lacked NK activity. The differences in the ontogeny of the two activities suggest that they are distinct. Preliminary effector cell characterization studies suggest that: (i) NK and ADCC in the pig are physically not separable; (ii) the majority of the cytotoxic activity on a cell-per-cell basis is mediated by the non-T lymphocyte fraction; and (iii) the rosetted T cells, which account for about 60% of the total pig peripheral blood lymphocytes, have low but demonstrable cytotoxic activity as well.

Animals↗
PubMed1978

Factors which have a significant effect on the survival of human skin grafts.

Survival of 436 ABO-compatible skin grafts exchanged in 97 Caucasian families was prolonged if donor and recipient were genotypically, as compared with phenotypically, HLA identical. Among skin grafts between haploidentical family members, a mismatch at the A locus was equivalent to a mismatch at the B locus. Skin grafted from child to mother survived longer than did skin grafted between other family members, other variables being equivalent. A highly significant positive correlation was found between the age of recipient and skin graft survival. In addition, a significant interaction was found between the relationship of donor and recipient and degree of antigen match.

Graft Survival↗
PubMed1978

The distribution of HLA antigens in the Motilones Indians of Venezuela.

The HLA antigen profile of the Bari and Yupa Indians who live in the Motilones Valley on the border between Venezuela and Colombia was studied. Both groups showed very limited polymorphism. HLA--A1, A3, A11, Aw23, A25, A26, A29, Aw30, Aw32, and Aw33, and HLA--B7, B8, B12, B13, B14, B17, B18, Bw22, and B27 were not observed in either population.

Gene Frequency↗