The glycoprotein (GP) Ib-EX complex on the surface of human platelets functions as the von Willebrand factor receptor and mediates von Willebrand factor-dependent platelet adhesion to blood vessels. GPIX is a relatively small (Mr, 17,000) protein that may provide for membrane insertion and orientation of the larger component of the complex, GPIb (Mr, 165,000). Using antibody screening, we cloned a cDNA encoding GPIX from a human erythroleukemia cell cDNA library constructed in phage Agtll. Lacking a 5' untranslated region and start codon, the cDNA sequence includes 604 nucleotides, beinning with 495 bases at the 5' end coding for 165 amino acids, followed by a stop codon and 106 noncoding bases at the 3' end. By Northern blot analysis, the GPIX cDNA hybridizes with a single 1.0-kilobase species ofplatelet poly(A)+ RNA. Translation of the cDNA sequence gives a predicted protein sequence beinning with a truncated putative signal sequence of 5 amino acids followed by a sequence of 17 amino acids matching that determined directly by Edman degradation of intact GPIX. The predicted amino acid sequence of mature GPIX includes an NH2-terminal extracytoplasmic domain of 134 residues, a transmembrane domain of 20 residues, 6 intracytoplasmic residues, and 1 N-linked glycosylation site. GPIX contains a leucine-rich glycoprotein (LRG) sequence of 24 amino acids similar to conserved LRG sequences in GPIb and other proteins from humans, Drosophia, and yeast."Flanking" sequences of %22 amino acids are present at the NH2 and/or COOH sides of the "central" LRG sequence(s) in GPIX, GPIb, and the other human and Drosophila members of the LRG family. The role of the flank-LRG center-flank structure in the evolution and function of the LRG proteins remains to be defined.

A data bank of substituent constants of 26 ortho and 34 meta and para benzenoid substituents is presented for use in physicochemical-activity relations (PAR) studies. The distributive parameters pri and pri-, a bulk parameter based on molar refraction, and positionally weighted electronic parameters F and R are listed for the three substituent positions. There are no gaps in the table caused by missing values and the interparameter correlation are low.

gentamicin and tobramycin resistance by standardized disk testing. For Pseudomonas isolates, gentamicin resistance was 17.1% and tobramycin resistance was 2.8%. For other gram-negative bacilli, gentamicin resistance was 5.5% and tobramycin resistance was 5.4%. Seventy-four patients from whom gentamicin-resistant organisms were isolated from 1 January to 30 June 1976 were studied prospectively. These patients were elderly, had serious underlying diseases, and had received prior antibiotic therapy. Eleven patients carried gentamicin-resistant organisms at the time of transfer to our hospital from community hospitals or nursing homes. Of the 82 isolates from these 74 patients, 52 were from the urine. Pseudomonas was found most frequently (32 isolates), followed by Klebsiella (15 isolates), Enterobacter (10 isolates), Serratia (10 isolates), and Proteus (9 isolates). Only 3 of 32 Pseudomonas isolates caused symptomatic infection, while 16 of 50 other gram-negative bacilli were responsible for symptomatic infection. Although amikacin was the most active drug against gentamicin-resistant gram-negative bacilli and had not been used in our hospital at the time of this study, 25% of Pseudomonas and 18% of all gram-negative bacilli showed resistance to this aminoglycoside.

No abstract

No abstract