In this study neutrophil (PMN) phagocytic capacity was investigated using a conventional radiometric ingestion assay (IN) in comparison with PMN respiratory burst activity assessed by luminol-enhanced chemiluminescence (LCL) in response to phorbolesters and LCL induction during phagocytosis of opsonized Staphylococcus aureus (STLCL) in diabetes mellitus and healthy controls. PMN ingestion was measured with 3H-thymidine-labelled S. aureus in a kinetic radiometric assay. LCL and STLCL were assessed in a parallel detecting microtitre-plate luminometer (MTP-Reader). PMN of diabetic subjects showed a highly significant reduction of peak LCL in response to PMA as well as during phagocytosis of S. aureus (STLCL) compared to non-diabetic controls (p < 0.001 respectively). PMN ingestion in diabetic patients (51.8 +/- 4.6%) was significantly reduced compared to controls (78.3 +/- 6.2%) (p < 0.01). The in vitro data displayed impaired PMN oxidative burst activity at glucose concentrations > or = 13.8 mmol/L, whereas PMN IN was significantly reduced at glucose levels > or = 27.75 mmol/L. The control group showed a positive correlation of peak LCL response and IN (p < 0.05) but not of STCL and IN; in diabetic patients this was also true, but did not reach statistical significance. The data obtained in this study clearly demonstrated impaired PMN respiratory burst activity and markedly reduced phagocytic PMN functions in diabetic patients ex vivo and in vitro as measured by LCL and by ingestion of 3H-thymidine-labelled S. aureus suggesting inhibitory effects of elevated glucose concentrations on various PMN-functions, which might be of clinical importance concerning altered host defence.

Adolescent↗

PubMedDate not supplied

Ultrastructural damage in "protectively" treated, frozen-thawed, tomato fruit parenchyma.

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Cryoprotective Agents↗

PubMedDate not supplied

Reflex and humoral responses to pulmonary embolism.

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Adenosine Diphosphate↗

PubMedDate not supplied

N-alpha-biotinylated-neuropeptide Y analogs: syntheses, cardiovascular properties, and application to cardiac NPY receptor visualization.

Two monobiotinylated analogs of neuropeptide Y (NPY) were synthesized by coupling the N-hydroxysuccinimidyl esters of biotin and (6-biotinylamido)-hexanoic acid, respectively, to the free alpha-NH2 group of the side chain protected NPY peptide resin. Crude peptides obtained by HF cleavage were purified by RPLC and their integrities were confirmed by amino acid and mass spectral analysis. As with NPY, both biotinylated analogs inhibited 125I-NPY binding and adenylate cyclase activity of rat cardiac ventricular membranes in a dose-dependent manner. N-alpha-[(6-biotinylamido)-hexanoyl]-NPY exhibited potencies comparable to that of NPY whereas N-alpha-biotinyl-NPY was slightly less potent. In the in vivo experiments, however, both the biotinylated analogs exhibited responses comparable to NPY in increasing arterial blood pressure and decreasing heart rate in anesthetized rats. The responses of the biotinyl analogs were longer lasting than those of NPY. Histochemical studies revealed that N-alpha-[(6-biotinylamido)-hexanoyl]-NPY could label the NPY receptors in rat cardiac ventricular tissues. This labeling was specific since intact NPY inhibited the staining. These studies show that biotinyl-NPY analogs exhibit biological potencies comparable to intact NPY and can therefore be used to further probe the NPY-receptor interaction.

Adenylyl Cyclases↗

PubMedDate not supplied

Salmon pancreatic polypeptide exhibits neuropeptide Y-like activities in rats.

Salmon pancreatic polypeptide (sPP) is a 36 residue peptide amide isolated from salmon pancreas. It has 83% sequence identity with porcine neuropeptide Y (NPY). To confirm the sequence and obtain sufficient quantity of peptide for biological investigations, sPP was synthesized by automated t-Boc solid phase synthesis. The purified product had the expected amino acid composition, primary structure and mass, and was chemically and biologically indistinguishable from natural sPP. Investigation of its biological properties revealed that, like NPY, sPP increased blood pressure and decreased heart rate in anesthetized rats in a dose-dependent manner. There was no significant difference in the responses of NPY and sPP. Furthermore, administration of sPP directly into the hypothalamus of rats induced a feeding response comparable to that induced by NPY. Based on these investigations it may be suggested that synthetic and natural sPP are identical, and that sPP can express NPY-like activities in mammals presumably by interacting with the receptors of NPY.

Amino Acid Sequence↗