A nuclear cAMP binding protein in retinoic acid-treated HL-60 cells

A cAMP binding protein was detected in HL-60 cells using photoaffinity labeling with 8-azido [32P]cAMP. The binding protein was found in a 0.35 M NaCl nuclear protein extract from untreated HL-60 cells and from the HL-60 cells induced to mature with retinoic acid. While the quantity of the cAMP binding protein did not change following the induced differentiation, a second form of the subunit, altered in charge, was present at 3 and 5 days after retinoic acid treatment. The findings indicate that the regulatory subunit of the type II cAMP-dependent protein kinase could be involved in nuclear functions associated with human myeloid cell differentiation.     

Presuturing--a new technique for closing large skin defects: clinical and experimental studies

We have developed a new technique termed presuturing for aiding in the closure of large skin defects which may have otherwise required a skin graft or flap. This technique is based on biomechanical properties of skin (creep, stress relaxation) which allow skin to stretch beyond its inherent extensibility. Presuturing is performed under local anesthesia and consists of plicating intact skin over the area of planned excision the night prior to operation. Experimental studies in a pig model showed the decrease in force required to close a standard-sized wound to be 40.1 percent less than control (p less than 0.001). Fourteen patients who underwent wide excision of skin lesions had their wounds presutured. All but one wound could be closed primarily without undermining. Presuturing seems to be an easy and clinically useful technique in aiding the primary closure of large defects.     

Interaction of lymphocytes and high endothelial venules in irradiated lymph nodes

After total-body exposure to various doses of ionizing radiation, the ability of lymphocytes to interact specifically with high endothelial venules of rat cervical and mesenteric lymph nodes was analyzed in frozen sections. Following a radiation dose of 1.5 Gy, high endothelial venules remained intact and the binding of unirradiated lymphocytes to the venules was enhanced relative to unirradiated controls. At radiation doses above 5.0 Gy, damage to high endothelial venules was observed histologically as well as assessed functionally. There was a significant decrease in specific lymphocyte-venule binding and a significant increase in nonspecific binding. These findings suggest that radiation-induced damage to high endothelial venules might play a role in radiation-induced immunosuppression by interfering with the normal passage of lymphocytes from the blood into lymph nodes via a specific interaction between lymphocytes and high endothelial venules.     

Properties of a nuclear protein marker of human myeloid cell differentiation

The Mr 55,000 nuclear antigen present in the human promyelocytic cell line HL-60 is a basic protein that is extracted from nuclei or chromatin by 0.35 M NaCl. The antigen is confined to the nucleus of the interphase HL-60 cell as judged by immunocytochemical localization but disperses throughout the cell during mitosis. The antigen was not detected in leukemic cell lines with blast cell properties or in cell lines representing other lineages. Additional cell lines (ML-1, ML-2, and U937) with myeloid cell characteristics similar to those of the HL-60 cells, which also differentiate in vitro, express the antigen. The presence of antigen in normal human myeloid cells in peripheral blood and bone marrow is consistent with its proposed role in nuclear events associated with normal human myeloid cell differentiation.     

Inhibition of glycine N-methyltransferase activity by folate derivatives: implications for regulation of methyl group metabolism

Glycine N-methyltransferase, an enzyme that uses S-adenosylmethionine to methylate glycine with the production of sarcosine, was recently shown to be identical with a major folate binding protein of rat liver (Cook, R.J. and Wagner, C. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 3631-3634). We now present evidence that 5-methyltetrahydropteroylpentaglutamate (5-CH3-H4PteGlu5) is bound with high specificity, and is a powerful inhibitor of the enzyme. It is proposed that this information may be used to modify the "methyl trap" hypothesis which describes how the availability of one-carbon units is regulated by folate, vitamin B12 and methionine.     

A comparison of in vivo catalysis by creatine kinase in avian skeletal muscles with different fibre composition

The maximum activity of creatine kinase in vitro is similar in the pectoralis major muscle of the chicken and the duck. However, the flux (phosphocreatine to ATP) as measured by 31P saturation transfer NMR in vivo is almost 2-fold higher in the duck. This apparent discrepancy can be accounted for by the differences in the cytosolic free ADP concentrations in resting muscle.     

The Pragmatics of Proverb Performances in New Mexican Spanish

Performances of proverbs by Mexicanos in northern New Mexico are characterized by seven features in addition to the proverb text. These are examined with respect for the role they play in connecting basic cultural and linguistic patterns with the minute details of an ongoing social interaction. The processes of presupposition and contextualization are identified as crucial determinants of the way each feature will be realized in a given performance.