Modulation of ornithine decarboxylase activity in the normal and regenerating rat liver by different doses of hydra peptide morphogen

The authors studied the anabolic effect of peptide morphogen of the hydra undecapeptide on normal and regenerating rat liver. Ornithine decarboxylase (EC 4.1.1.17) activity served as a marker. Intraperitoneal injection of the peptide into intact animals stimulated ornithine decarboxylase activity in a dose-dependent manner. In partially hepatectomized rats the peptide stimulated ornithine decarboxylase activity in the dose of 20 micrograms/kg body weight while greater doses inhibited the enzyme activity.     

Application of halophilic nuclease H of Micrococcus varians subsp. halophilus to commercial production of flavoring agent 5'-GMP

RNA was degraded at 60 degrees C for 24 h by halophilic nuclease H in supernatants from broth cultures of Micrococcus varians subsp. halophilus containing 12% NaCl. Since contaminating 5'-nucleotidase exhibited almost no activity under these conditions, the 5'-GMP formed could be recovered from the reaction mixture, and the yield was 805 mg from 5 g of RNA.     

Spatially resolved cytosolic calcium response to angiotensin II and potassium in rat glomerulosa cells measured by digital imaging techniques

The response of cytosolic calcium [Ca2+]i to angiotensin II (AII) and potassium (K+) in individual rat glomerulosa cells was determined using the calcium-sensitive fluorescent dye, fura-2 and digital imaging. Control (4 mM K+) cytosolic calcium levels were generally in the 80-120 nM range and increased monotonically as [K+] was increased from 4 to 12 mM. There was no delay in the onset of the response. In most cells the [Ca2+]i decreased from its peak after 3-4 min, even in the presence of superfusate containing elevated K+. The time course of the change in [Ca2+]i in response to AII stimulation, on the other hand, was more variable. It was most often characterized by an early decrease followed by a large delayed increase. The response also was observed to decline during sustained AII stimulation. The majority of the cells showed some response to one or the other secretagogue with a sizeable minority (25%) having an increase in [Ca2+]i in excess of 200%. While the majority showed a response, the cell to cell variation was substantial. Finally, the pattern of cytosolic calcium increase sometimes showed a marked dependence on the secretagogue used, with different regions of the same cell being more strongly affected by one agent or the other. A few cells (10%) responded to AII only at one pole, establishing a large concentration gradient of calcium across the cell. Because of differences in time course, pattern, and degree of responsiveness, it is likely that the mechanisms underlying the Ca2+ elevation with K+ and AII are different.     

Structure of the spectrin-actin binding site of erythrocyte protein 4.1

The complete primary structure of the functional site of erythrocyte protein 4.1 involved in spectrin-actin associations has been determined. The sequence of this domain, which contains 67 amino acids and has a molecular mass of 8045 daltons, has been obtained by NH2-terminal sequence analysis of an 8-kDa chymotryptic peptide, three endoproteinase lysine C-cleaved peptides and two peptides obtained by Staphylococcus aureus protease V8 cleavage. All peptides including the 8-kDa domain peptide were purified by reverse-phase high performance liquid chromatography. Antibodies against two different synthetic peptides of the 8-kDa domain are able to inhibit the association between protein 4.1, spectrin, and F-actin, corroborating that the 8-kDa domain is responsible for the formation of a ternary complex. A computer search of the 8-kDa sequence with the National Biomedical Research Foundation database did not detect any significant homologies to known sequences. Protein 4.1 is not related to any known proteins and may represent a new protein superfamily.     

Influence of arm position on measurement of blood pressure.

A series of measurements of blood pressure in normotensive and hypertensive subjects showed that measurements made with a sphygmomanometer with the arm dependent by the side were consistently higher than those made with the arm horizontal at heart level. The mean difference in a group of 90 hypertensive outpatients was 11/12 mm Hg. Failure to appreciate the importance of arm position may lead to erroneous measurements of blood pressure. This has important implications for clinical practice and research.     

An inexpensive photosynthetic irradiance sensor for ecological field studies

The design and characteristics of inexpensive and simply constructed equal-energy response photosynthetic irradiance sensors is described for use particularly where several cells are required in comparative ecological studies either above or below water. The dimensions of the sensors can be changed proportionally to suit different applications or components. The response of the sensor to irradiance at varying angles corresponds very closely to that required by the cosine law. The sensor is comparatively insensitive to other environmental variables in field use and gave a stable output; the long term drift was proportional to electrical output but in continuous use, drift is regular and could reach -0.08 year^-1 of the total. The spectral range and cosine response is discussed in comparison to other more expensive (x 5–10) commercially available, sensors and to local standards.