Chronic lymphocytic leukemia in China

Chronic lymphocytic leukemia (CLL) is a very common form of leukemia among middle-aged and elderly persons in Western countries. In the Japanese, or in those with Japanese ancestry born and living in the USA, CLL is rather rare. It is also rare in China, but convincing data to support this statement are found primarily in the Chinese literature. We have reviewed previously unpublished data from Peking Union Medical College (PUMC) concerning the frequency of CLL among adult patients with the four common types of leukemia. Of 4,174 such patients (1952-1986), 4.6% had CLL; 22.9% chronic myeloid leukemia (CML); 50.3% acute myeloid leukemia (AML); and 22.3% acute lymphoblastic leukemia (ALL). This low frequency of CLL is none the less higher than that found in a multiinstitutional collection of Chinese patients with leukemia. Various clinical and laboratory aspects of a carefully studied, previously published group of patients with CLL from PUMC were compared to similar published findings in patients from the University of Utah. No differences in the overall nature of the disease were detected between these groups. However, not unexpectedly, the duration of symptoms before the diagnosis was made longer in Chinese than in USA patients and the proportion diagnosed at a time when no CLL related symptoms had been noted was less in Chinese. Neither differences in life span in the two populations nor an excess of CML, AML, and ALL at the expense of CLL were viable hypotheses to explain the rarity of CLL in China. We suggest that the dearth of CLL in Chinese is on a genetic basis, as it is thought to be in the Japanese.

Effect of C-banded heterochromatin on centromere separation

The present study is to determine the effects of centromeric heterochromatin on centromere separation. Amniotic cell cultures in which the centromeric heterochromatin of one chromosome was at least twice as large (qh+) as the heterochromatin (qh) in the homologous chromosome were selected. Fifteen amniotic cell samples with 1qh+, 9qh+ or 16qh+ were studied. The size of the centromeric heterochromatin was directly correlated with the delay in centromere separation. The chromosome with the smaller centromeric heterochromatin tended to show earlier centromere separation than the homologue with the larger heterochromatin. Our results suggest that the quantity of centromeric heterochromatin may influence the genetic control of centromere separation.

Investigations of primary and secondary structure of porcine ubiquitin. Its N epsilon-acetylated lysine derivative

N epsilon-acetylation in vitro of internal lysyl residues of Ub by p-nitro-phenyl acetate at pH 8.0 was performed. The position of acetylation sites are determined. (e.g. Fully acetylated: Lys-6, Lys-11 and Lys-33; partially free internal lysines: Lys-27, Lys-29; Lys-48 and probably Lys-63.) 55 cycles Edman degradation were performed and the first 53 N-terminal residues were identified. Secondary structural studies of ubiquitin have been carried out using the circular dichroism (CD) technique. No changes are noted upon heating to 100 degrees C at neutral pH even in the presence of 8 M urea but in 6 M guanidine-HCl extensive modification results. Ubiquitin with an average of 4.4 of its 7 lysines in the N epsilon-acetyl form shows little deviation from native protein. After reduction with dithiothreitol and subsequent removal of the mercaptan, significant changes in the secondary structure are noted. Circular dichroic measurements of ubiquitin indicated an alpha-helical content of about 10% whereas the secondary structural predictions of Chou and Fasman suggest a level of about 45%.

Complete amino acid sequence of mung bean trypsin inhibitor

The mung bean trypsin inhibitor has been found to be microheterogeneous at N-terminal region due to the presence of several isomers. After treatment with aminopeptidase M it becomes homogeneous and is suitable for sequence determination. Based on the determination of the structures of two active fragments the complete amino acid sequence of mung bean trypsin inhibitor has been elucidated. It consists of 72 amino acid residues with 7 pairs of disulfide bonds. The results show that this inhibitor belongs to the Bowman-Birk inhibitor family.