The human CD7 antigen is a glycoprotein, M(r) 40,000, expressed on the surface of peripheral blood T-lymphocytes and thymocytes, and is the earliest surface antigen to appear on T-cell lineage cells. In this study, putative mouse CD7 cDNA was identified based on its similarities with human CD7. Five independent clones originating from the same mRNA species were isolated (designated as mCD7) by screening a mouse thymocyte cDNA library with human CD7 cDNA, J61, under moderate stringency. The longest insert of a 995 base pair had an open reading frame of 210 amino acids. Northern blot analysis using the mouse CD7 cDNA probe demonstrated a single 1.2 kilobase mRNA in the thymus, spleen, bone marrow, and small intestine. The protein deduced from mCD7 cDNA consisted of the leader, extracellular, transmembrane, and cytoplasmic domains of 24, 126, 21, and 39 amino acids, respectively, based on the hydrophobicity plot and the structure of human CD7. The extracellular domain contained three potential N-glycosilation sites, while the cytoplasmic domain contained one potential protein kinase C phosphorylation site. The amino acid sequence had 45.5% similarity with human CD7, while the similarities for the individual domains ranged from 49.2% to 63.2%. The six highly conserved regions, which may possibly be involved with still unknown CD7-mediated functions, were located in the extracellular and cytoplasmic domains.

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A new method involving the introduction of tiopronin solution directly into the renal pelvis or bladder has been developed for the treatment of cystine stones. Therapeutic irrigation by tiopronin solution was done in 4 cases of residual cystine kidney stones using a nephrostomy tube, and in an infant with bladder cystine stones using a Foley 3-way catheter. In every case all of the cystine stones were dissolved completely. During the course of the treatment no abnormality was noted on blood, liver function or immunological tests. Neither have there been any negative side effects, such as eruption, anorexia, nausea, diarrhea or general fatigue. The significance of this irrigation process is that whereas nephrectomy, heminephrectomy or nephrolithotomy was necessary previously to remove kidney cystine stones, now only pyelolithotomy and nephrostomy tube insertion are necessary. Furthermore, an operation is unnecessary in cases of bladder cystine stone dissolution by tiopronin irrigation.

A DNA hybridization method with an enzyme-labeled oligonucleotide probe (mecA-ELONP) was developed to detect the methicillin-resistant gene (mecA) in methicillin-resistant Staphylococcus aureus. For rapid identification, bacterial colonies were transferred from agar plates directly onto nylon membranes. Lysis of cells, denaturation of DNA, and hybridization were performed on the membranes. These procedures required only 3 h for completion. The results obtained by this test closely corresponded with those obtained by determining the MICs of oxacillin against S. aureus. The results of the mecA-ELONP also correlated well with those of a commercially available PCR test. Thus, mecA-ELONP proved to be a reliable and convenient method for the rapid identification of methicillin-resistant S. aureus, which could be useful in clinical microbiology laboratories.

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