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Biomedical subjects

G Varga

Publications and source records attributed to G Varga.

At least 109 records · Page 6Linked to original sources
PubMed1989

Caerulein-induced desensitization of enzyme secretion fails in neonatal rat pancreas.

Pancreatic segments of 1-, 3-, 5-, 10-day-old and adult female OFA (Sprague-Dowley strain) rats were superfused with graded concentrations of caerulein (10(-12)-10(-7) M) to establish concentration-response relation of amylase release. Furthermore, pancreatic segments of 3-, 5-, 10-day-old and adult rats were superfused with 10(-10) or 10(-8) M caerulein and then superfusion was repeated with 10(-10) M concentration of caerulein to show whether the phenomenon of desensitization of amylase release can be induced in the postnatal period. The 1-day-old pancreas was found practically insensitive to caerulein. The 3- and 5-day-old gland was by one order of magnitude less sensitive (EDmax = 10(-8) M) than the adult pancreas (EDmax = 10(-9) M). Repeated superfusion of the 3- and 5-day-old pancreas with 10(-10) M caerulein after the first 10(-8) M caerulein superfusion failed to cause desensitization, while the same (10(-10) M) repeated superfusion of the 10-day-old adult pancreatic segments after the first 10(-8) M caerulein superfusion evoked desensitization of enzyme release. The authors suggest that the failure of desensitization of enzyme secretion for caerulein may be due to the maturation process of newborn rat pancreatic acinar cells at receptorial and postreceptorial level.

Aging↗
PubMed1989

Effect of treatment with submaximal and excessive doses of caerulein on pancreatic growth in newborn rats.

Different groups of CFY female newborn rats were treated with saline, or 1 microgram/kg or 100 micrograms/kg doses of caerulein given s. c. 3 x/day. Application of 100 micrograms/kg dose of caerulein for 3 days stimulated pancreatic growth inducing pancreatic hyperplasia; both (1 and 100 micrograms/kg) doses evoked increase in trypsin/DNA ratio inducing pancreatic hypertrophy in 4-days-old rats. Using the indices as before application of 1 microgram/kg caerulein for 10 days stimulated pancreatic growth and both (1 and 100 micrograms/kg) doses elicited glandular hypertrophy in 11-days-old rats. In 24-old-rats the 1 microgram/kg doses of caerulein given for 3 days stimulated pancreatic growth and induced pancreatic hypertrophy, the 100 micrograms/kg doses of the peptide given for 3 days, however, evoked pancreatic aplasia and atrophy.

Animals↗
PubMed1988

Effects of peptide YY on dog and rat pancreatic secretion in vivo and in vitro.

The action of peptide YY (PYY) on exocrine pancreatic secretion in dogs and rats was compared in in vivo and in vitro studies. PYY infused i.v. in the physiological dose range (125-1000 pmol/kg.h) reduced in a dose-dependent manner the pancreatic protein response to caerulein and suppressed basal and meat feeding or duodenal oleate-induced pancreatic secretion in conscious dogs. Both meat feeding and duodenal oleate caused significant elevation of plasma PYY levels and these showed several-fold increase during infusion of exogenous PYY (500 pmol/kg.h) inducing significant inhibition of the postprandial or oleate-stimulated pancreatic secretion. PYY in a dose range of 2.5-40 nmol/kg.h also inhibited the response to caerulein in conscious rats but failed to prevent the increment in the postprandial protein secretion in this species. PYY added in various concentrations (10(-11)-10(-6) M) to the incubation medium of the isolated dog and rat pancreatic acini failed to affect basal or caerulein- and urecholine-stimulated amylase release. This study shows that PYY is an effective inhibitor of the pancreatic secretion in vivo but not in vitro suggesting that the inhibition is mediated by an indirect mechanism.

Amylases↗
PubMed1988

DNA sequence (H) curves of the human immunodeficiency virus 1 and some related viral genomes.

The complete nucleotide sequences of several human immunodeficiency virus 1 (HIV-1) genomes were converted by computer to respective H curves. These three-dimensional space curves embody all the information contained in the sequence due to their abstract vectorial structure. For one sequence (HIV-1 isolate BRU) special efforts were made to maximize the available resolution (the number of nucleotides visually discernible within a unit length of the curve) when making a hard, master copy of the H curve. Using a computergraphic/photographic hybrid process the 9191 nucleotides of this HIV-1 sequence were condensed into an H curve of only 37.1 cm vertical length. Although each 1-mm segment of this curve represented 25 nucleotide residues, each of the individual nucleotides of the entire sequence was still distinguishable upon direct inspection using a simple magnifying lens. Several functionally important loci of the HIV-1 sequence could be recognized on the H curve owing to characteristic line forms at corresponding locations. Utilizing H curves of lower resolution, the total nucleotide sequences of several different HIV-1 isolates and related viral sequences [Visna, equine infectious anemia (EIAV), Moloney murine leukemia (Mo-MLV), bovine leukemia (BLV), and human T-cell leukemia, type I (HTLV-I)] were visually compared side by side. An interesting similarity was noted between the location of the S3 fragment of the EIAV sequence and that of a relatively G-C rich region on the env portion of the HIV-1 sequences.

Base Sequence↗
PubMed1988

Effect of bombesin and its mammalian counterpart, GRP, on exocrine pancreas in the rat.

The effect of equimolar doses (6 nmol/kg) of bombesin and its mammalian counterpart, GRP, on pancreatic growth and secretion was studied in adult rats. Both peptides were administered intraperitoneally three times a day for 5 consecutive days. Saline-treated rats were used as controls. At the end of the treatment, animals were anaesthetized and pancreatic juice was collected in basal conditions and after caerulein (0.75 nmol/kg i.p.) stimulation. Afterwards, the rats were sacrificed and growth and composition of the pancreatic tissue were determined. Compared with the control (saline) values, either basal or stimulated secretion was significantly increased after short-term treatment with both peptides. In addition, both bombesin and GRP increased pancreatic weight, total pancreatic protein, trypsin and amylase content. The DNA content was also increased by both peptides, although only the GRP effect proved to be significant. These results demonstrate that both bombesin and GRP have a growth-promoting effect on rat pancreas and concomitantly increase its secretory capacity. The mechanism of this peculiar biological action is likely to be connected with a direct stimulatory action on the gland.

Amylases↗
PubMed1988

Excessive doses of cerulein stimulate pancreatic growth in suckling rats but damage the pancreas of weaned rats.

The cerulein-stimulated pancreatic growth response was evaluated in 4- and 11-day-old female suckling CFY rats and compared with the pancreatic response of cerulein-treated 24-day-old weaned rats. Cerulein was given subcutaneously in saline in 1-, 10- and 100-micrograms/kg doses t.i.d. The increase in pancreatic DNA content was regarded as an index for hyperplasia, and the increase in pancreatic weight, protein content and enzyme activity related to milligrams of DNA as an index for hypertrophy. Three-day administration of 1- and 10-micrograms/kg doses of cerulein increased the pancreatic trypsin/DNA ratio, and doses of 100 micrograms/kg cerulein evoked pancreatic hypertrophy and hyperplasia in 4-day-old rats. Ten-day administration of 1- and 10-micrograms/kg doses induced pancreatic hypertrophy and hyperplasia, while the 100-micrograms/kg doses induced pancreatic hypertrophy in 11-day-old rats. In 24-day-old weaned rats, the 3-day administration of 1-microgram/kg doses resulted in hypertrophy of the gland, while the 100-micrograms/kg doses of cerulein evoked pancreatic aplasia and atrophy. It is concluded that the growth-promoting effect of cerulein on the newborn rat pancreas is age- and dose-dependent.

Amylases↗
PubMed1988

Caerulein in supramaximal doses fails to stimulate pancreatic growth, but it forces secretory granulopoiesis.

To determine how low or high dose of caerulein, a cholecystokinin analogue influence pancreatic growth, doses of caerulein were selected which were submaximal (1 microgram/kg i.p.) and supramaximal (10 micrograms/kg i.p.) for enzyme protein secretion. Rats were injected every 8 h for 7 days with saline, low, or high dose of caerulein. The low dose of caerulein significantly increased pancreatic weight and content of DNA, protein, and digestive enzymes. The high dose caerulein group did not differ from control in these parameters of pancreatic growth. The number of zymogen granules was increased in both caerulein-treated groups. However, zymogen granules in the high dose group were atypical, appearing lucent or having a dense core with a lucent halo. These results indicate that caerulein has a biphasic effect on both enzyme secretion and the trophic response of acinar cells, and that the inhibitory effect of high dose of caerulein on pancreatic growth is accompanied by alterations in acinar cell morphology.

Amylases↗
PubMed1988

Granulocytic progenitor cells in the adherent layer of human long-term bone marrow cultures.

The importance of the adherent layer in long-term mouse bone marrow cultures as a reservoir of the most primitive stem cells is known. The role of the adherent cell layer in long-term human cultures (LTC) is examined from this point of view. Confluent adherent layers developed after about 3 weeks of culture. At that time and weekly thereafter the cellularity and granulocytic-macrophage progenitor (CFU-GM) content of the adherent fraction were determined after tripsinisation. We have documented that CFU-GM were present in the adherent layer of human cultures for at least 8 weeks. These findings emphasize the importance of assessing the progenitor cell content of the adherent layer in long-term human cultures.

Bone Marrow Cells↗