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Biomedical subjects

N F Paoni

Publications and source records attributed to N F Paoni.

23 records · Page 2Linked to original sources
PubMed1979

Permeabilization of cells for studies on the biochemistry of bacterial chemotaxis.

The cell membranes of Salmonella typhimurium and Escherichia coli have been made permeable in order to introduce S-adenosylmethionine into the cell for study of the course of methylation. A series of protein bands in the Mr 60,000 region were methylated, the specific bands and the extent of methylation depending on the attractant used. The change in levels of methylation was essentially the same as the in vivo responses, indicating that the permeabilization procedure maintains the relative relationships of the cellular proteins. A shift in intensity of the methylated bands occurred over time, indicating that a sequential process is involved in the methylation of these proteins. The permeabilization technique appears to offer major advantages in tracing the biochemical processes of the behavioral system.

Animals↗
PubMed1977

Isolation and characterization of native and lower molecular weight forms of sheep plasminogen.

Two major forms of native sheep plasminogen (SPg-a) have been isolated from plasma by affinity chromatography. These forms differ in molecular weight, charge characteristics, affinity for epsilon-aminocaproic acid (epsilon-Ahx), and carbohydrate content. Upon treatment of SPg-a with plasmin, lower molecular weight plasminogens can be isolated. A plasminogen (SPg-b) of molecular weight approximately 8,000 less than native plasminogen is rapidly produced when either major plasminogen form is treated with plasmin. The molecular weight differences found in the major SPg-a forms are retained in the SPg-b forms, derived from each SPg-a. Upon protracted treatment of either major form of SPg-a or SPg-b with plasmin, a plasminogen (SPg-c) or molecular weight approximately 32,000 less than SPg-b is produced. A single peptide (P) is also produced in this step. The SPg-c species produced from each original SPg-a major form possess essentially the same molecular weights and carbohydrate compositions; but the P cleaved retains the molecular weight and carbohydrate differences found in each major SPg-a or SPg-b form. A large decrease in the S20,w of SPg-a is observed upon the binding of epsilon-Ahx to this protein. A much smaller alteration in the S20,w of SPg-b and SPg-c is observed upon binding of epsilon-Ahx to these proteins.

Amino Acids↗
PubMedDate not supplied

Treatment with growth hormone enhances contractile reserve and intracellular calcium transients in myocytes from rats with postinfarction heart failure.

BACKGROUND: Recombinant human growth hormone (GH) improves in vivo cardiac function in rats with postinfarction heart failure (MI). We examined the effects of growth hormone (14 days of 3.5 mg. kg-1. d-1 begun 4 weeks after MI) on contractile reserve in left ventricular myocytes from rats with chronic postinfarction heart failure. METHODS AND RESULTS: Cell shortening and [Ca2+]i were measured with the indicator fluo 3 in myocytes from MI, MI+GH, control, and normal animals treated with GH (C+GH) under stimulation at 0.5 Hz at 37 degrees C. Cell length was similar in MI and MI+GH rats (150+/-5 and 157+/-5 microm) and was greater in these groups than in the control and C+GH groups (140+/-4 and 139+/-4 microm, P<0.05). At baseline perfusate calcium of 1.2 mmol/L, myocyte fractional shortening and [Ca2+]i transients were similar among the 4 groups. We then assessed contractile reserve by measuring the increase in myocyte fractional shortening in the presence of high-perfusate calcium of 3.5 mmol/L. In the control and C+GH groups, myocyte fractional shortening and peak systolic [Ca2+]i were similarly increased in the presence of high-perfusate calcium. In the presence of high-perfusate calcium, both myocyte fractional shortening and peak systolic [Ca2+]i were depressed in the MI compared with the control groups. In contrast, myocyte fractional shortening (14.1+/-.9% versus 11.1+/-.9%, P<0.05) and peak systolic [Ca2+]i (647+/-43 versus 509+/-37 nmol/L, P<0.05) were significantly higher in MI+GH than in MI rats and were comparable to controls. Left ventricular myocyte expression of sarcoplasmic reticulum Ca2+ ATPase 2 (SERCA-2) and left ventricular SERCA-2 protein levels were increased in MI+GH compared with MI rats. CONCLUSIONS: Calcium-dependent contractile reserve is depressed in myocytes from rats with postinfarction heart failure. Long-term growth hormone therapy increases contractile reserve by restoring normal augmentation of systolic [Ca2+]i in myocytes from rats with postinfarction heart failure.

Analysis of Variance↗