Channa Shalitin

Haptoglobin-related protein as a serum marker in malignant lymphoma.

A novel serum 21 kDa haptoglobin-related protein (Hpr) was investigated in patients with malignant lymphoma, to evaluate its correlation with clinical and histologic features at presentation and its possible role as a tumor marker for patient outcome. One hundred fifty eight serum samples were taken from 88 patients with non-Hodgkin’s lymphoma (n=58) and Hodgkin’s disease (n=30) at presentation and in the course of follow-up. Sera from 61 healthy volunteers served as normal controls. Serum Hpr levels in the lymphoma patients (median 430xl03 u/ml, range 0-4000xl03) were significantly higher than in the control group (median 68xl03 u/ml, range 0-180xl03) (p=0.0001). Higher median Hpr values were detected in patients with advanced disease (p=0.013), “B” symptoms (p=0.029) and in males (p=0.053). There was also a significant correlation between Hpr and erythrocyte sedimentation rate (p=0.028). Serial determinations showed a significant decrease of the initial Hpr values obtained after treatment in 41 patients, 38 of whom achieved complete remission. In the follow-up period additional Hpr measurements were taken from 17 patients. Three of them eventually relapsed, and showed increased Hpr levels at the time of relapse. Hpr levels remained low in 11 of 14 patients who maintained complete remission, and increased in three. In conclusion, serum Hpr is a new serum tumor marker of potential use in the clinical setting of lymphoma.

Spermidine inhibits degradation of yeast chromatin

A procedure has been developed for the isolation of intact yeast chromatin from yeast nuclei. Autodigestion of chromatin observed during nuclear preparation was inhibited by the addition of 5 mM spermidine. The procedure is useful for the analysis of proteins associated with yeast chromatin.

Competence of membrane-bound T4rII DNA for in vitro “late” mRNA transcription

Abstract The effect of ionic strength on the transcription of phage T4 DNA by endogenous RNA polymerase has been examined in a DNA-enzyme-membrane system. Using the above system and competition hybridization studies it is shown that (1) addition of monovalent cations and omission of Mg2+ ions, conditions known to restrict the development of T4rII in λ-lysogens, mimics the abnormality in the transcription pattern of T4rII in vivo; (2) late mRNA is synthesized in T4rII-infected λ-lysogens at low ionic strength. The in vitro formation of late mRNA by membrane-bound T4rII DNA, unable to transcribe late species in vivo, indicates (1) the ionic control of T4 transcription in addition to other known control mechanisms, and (2) the intrinsic competence of endogenous rII-DNA and RNA polymerase for late transcription under the appropriate ionic conditions.

Alkynyl phosphates are potent inhibitors of serine enzyme

Propynyl, hexynyl and t‐butylethynyl diethyl phosphates were found to be very powerful covalent inhibitors of serine enzymes. Esterases were inhibited with second‐order rate constants of 107–108 M−1 min−1. Most proteases were inhibited with a rate constant of 104–105 M−1 min−1. By inhibiting chymotrypsin with (3‐14C)‐1‐propynyl diethyl phosphate, it was established that inhibition was caused by binding of the phosphate group to the enzyme active site.

An improved isolation procedure for yeast two-micrometer minichromosomes

SummaryTwo micrometer minichromosomes from Saccharomyces cerevisiae were isolated without detergent using metrizamide gradients. 2 μm minichromosomes showed a lower density in metrizamide gradients relative to genomic chromatin. Our results suggest a lower ratio of proteins to DNA in 2-μm minichromosomes as compared with genomic chromatin. The procedure described herein yields minichromosomes free of cellular chromatin and ribosomal protein contamination. This method may be useful for the isolation and characterization of other yeast minichromosomes.

Induction of virus-like particles in cell cycle mutants of Saccharomyces cerevisiae

Virus-like particles isolated from Saccharomyces cerevisiae have a sedimentation coefficient of 135 S and a buoyant density of 1.36 g/cm 3 in CsCl gradients. The production of virus-like particles in yeast cells was examined in three different cell cycle mutants ( cdc ) that are defective in nuclear deoxyribonucleic acid replication and which contain the “killer character.” In cdc4 and cdc7 , which are defective in the initiation of nuclear DNA synthesis, and in cdc14 defective in late nuclear division, an induction of virus-like particles at the restrictive temperature was observed. Examination of the killer-sensitive strains ( cdc7 K − and cdc4 K − ) has shown that the complete double-stranded RNA (dsRNA) genome is essential for the induction of virus-like particles at the restrictive temperature.