Biomedical subjects
Publications and source records attributed to E J Haas.
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Ribulose-1,5-bisphosphate carboxylase/oxygenase is the key enzyme for photosynthesis. The wild-type and mutant (amino-acid substitutions in the catalytically important loop 6 region) enzymes from Chlamydomonas reinhardtii, a unicellular green alga, were crystallized. Wild-type, single-mutant (V331A) and two double-mutant (V331A/T342I and V331A/G344S) proteins were activated with cofactors CO2 and Mg2+, complexed with the substrate analog 2'-carboxyarabinitol-1,5-bisphosphate, and crystallized in apparently isomorphous forms. Unit-cell determinations have been completed for three of the enzymes. They display orthorhombic symmetry with similar cell parameters: wild type a = 130.4, b = 203. 3, c = 208.5 A; single mutant (V331A) a = 128.0, b = 203.0, c = 207. 0A; and double mutant (V331A/T342I) a = 130.0, b = 202.1, c = 209.7 A. Crystals of the wild-type and single-mutant (V331A) enzymes diffracted to approximately 2.8 A. A small crystal of the double-mutant (V331A/T342I) enzyme diffracted to approximately 6 A. A partial data set (68% complete) of the wild-type protein has been collected at room temperature to about 3.5 A.
Native American populations have a limited HLA polymorphism compared with other ethnic groups. In spite of this, many novel HLA-B locus alleles, not observed in other populations, have been identified in South American tribes, and rapid evolution of this locus has been suggested. We have studied unrelated subjects of the Toba (TOB n = 116), Wichi (WIC n = 46) and Pilaga (PIL n = 14) tribes from northeastern Argentina to investigate the extent of the HLA polymorphism and obtain clues of selective forces that may have acted in these populations. In these tribes the number of HLA alleles is small at all loci except HLA-B, which presents 22 alleles. Seven novel alleles were characterized including 5 of HLA-B (B*35092, B*3518, B*3519, B*4009, B*4803) 1 at HLA-A (A*0219) and 1 at DRB1 (DRB1*0417). All these variants may have arisen by gene conversion events. Some of the novel variants represent the most frequent alleles of these populations (B*4803 in TOB and PIL; B*3519 in WIC) or are the most frequent subtypes in their lineages. HLA-A, B, DRB1,DQA1 and DQB1, but not DPB1, display relatively similar gene frequencies. This results in high heterozygosity in all the tribes for all the loci studied except HLA-DPB1. The larger polymorphism and the generation and maintenance of novel alleles at the HLA-B locus suggests a more specialized response of this locus to evolutionary forces. These effects may be related to the nature of the polymorphism, to the number of founder alleles and to the functional characteristics of the individual alleles.
We prepared a series of overlapping peptides (29 in total, 20 amino acids each) containing the sequence of the entire extracellular domain of the human TSH receptor. Three peptides (181-200, 376-394, and EC3 (629-639)) bound IgG from patients with Graves' disease in an enzyme linked immunoassay. Peptide 181-200 bound IgG from 9 of 10, EC3 from 8 of 10, and 376-394 from 6 of 10 patients respectively, compared to 0 of 9 controls. We affinity purified TSHr auto-antibodies from four Graves' patients using the three above noted peptides bound to epoxy-activated sepharose. Thyroid stimulating activity was enriched in the bound fraction from at least two of the three peptide affinity columns in each of the four patients, although the pattern of affinity enrichment differed between patients. One patient was found to possess a combination of stimulatory and inhibitory TSHr antibodies and, after affinity purification, the anti-376-394 and anti-EC3 fractions were enriched in stimulatory activity, suggesting that those regions of the receptor were epitopes for stimulatory antibodies. However, affinity purification against peptide 181-200 produced an IgG preparation that was not stimulatory, but was a potent thyroid inhibitor. Thus, we have not only partially purified TSHr auto-antibodies, but also successfully separated stimulatory and inhibitory antibodies from a single patient using combination TSHr peptide affinity.
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A total of 107 Mapuche Indians living in western Argentina were studied with respect to 16 genetic systems. For HLA, there were a few differences in relation to previous studies; and considering the averages observed in 15 other South American tribes, Mapuche Indians showed low values for A2, A9 and C3, but high ones for A28 and B16. This is the first report of the presence (in low frequencies, 1-6%) of alleles C2, C6 and C7, as well as of DR antigens (most frequent alleles DR4 and DR2) in South American Indians. Some peculiar reactions shown by products of locus B suggest the presence of antigens that are characteristic of the Mapuche. As for the other systems, the frequencies of R1 (Rh) and PGM1(1) were lower but those for r (Rh), GLO1 and Hp1 were higher than the averages obtained considering previous studies of this ethnic group. Other salient findings were the variability observed in the PGM2 and C3 systems, and the low prevalence of Bfs.
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We analyzed the clinical and laboratory findings of 19 patients with tuberculous meningitis seen between 1966 and 1974 at the Henry Ford Hospital. Eighteen patients were adults at the time of diagnosis. In eight patients, the history suggested that the infection with the tubercle bacillus had occurred in the remote past. Cerebrospinal fluid analysis was often typical for tuberculous meningitis; stains for Mycobacterium tuberculosis were usually negative. Of 16 patients who were treated, five died and five suffered permanent neurological sequelae. The addition to rifampin to isoniazid therapy did not improve either survival or permanent sequelae. We were not able to analyze the effect of steroids on the disease.
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The concentration of cephazolin in the serum, gall bladder bile, common duct bile, and gall bladder wall were consideredably higher than cephalothin especially with IV administration and indicate that cephazolin should be a useful antibiotic in the surgical treatment of acute cholecystitis.
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