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Biomedical subjects

F Clemente

Publications and source records attributed to F Clemente.

At least 37 records · Page 2Linked to original sources
PubMed1994

Potent glycogenic effect of GLP-1(7-36)amide in rat skeletal muscle.

GLP-1(7-36)amide is an intestinal post-translational proglucagon product released mainly after carbohydrate ingestion, the glucose dependent insulinotropic and antidiabetogenic actions of which have been documented. In this work, by exploring whether GLP-1(7-36)amide has any effect on the glucose metabolism of the muscle, we have observed that this peptide, at physiological concentrations, exerts in this tissue an increment of the D-[U-14C]glucose incorporated into glycogen, which is accompanied by an increase in the glycogen synthase a activity; also, it stimulates both glucose oxidation and lactate formation. These data indicate that the skeletal muscle is one of the target tissues for GLP-1(7-36)amide, where its insulin-like effect explains, at least in part, its plasma glucose lowering action; thus, GLP-1(7-36)amide may well be implicated in the physiological control of glucose homeostasis after meals, not only by acting as an incretin, but also by directly promoting glucose disposal.

Animals↗
PubMed1993

Caerulein and gastrin(2-17 ds) regulate differently synthesis of secretory enzymes, mRNA levels and cell proliferation in pancreatic acinar cells (AR4-2J).

In order to characterize the biological functions coupled to cholecystokinin (CCK) A and B receptors, the effects of gastrin(2-17 ds) and caerulein were compared. An isolated cell model, the pancreatic acinar cell line AR4-2J, was used and the experiments were carried out in serum-free media. Caerulein was found to evoke no mitogenic effects either alone or in the presence of the CCK antagonists L364,718 and CR1409. Gastrin(2-17 ds) increased cell proliferation by 2-fold with an IC50 of 150 pM, corresponding to the occupancy of the CCK B receptors. CR1409, at concentrations that fully occupied CCK B receptors, inhibited the gastrin(2-17 ds) effects. Caerulein enhanced chymotrypsinogen biosynthesis by 100% and the corresponding mRNA level by 75%; amylase biosynthesis and mRNA level were enhanced by 40% only. Half-maximal increases in chymotrypsin activity and mRNA level were recorded in response to caerulein at concentrations of 100 pM and 50 pM respectively. Gastrin(2-17 ds) at 100 nM enhanced chymotrypsinogen biosynthesis by 26% and its mRNA level by 35%; these responses were lower than those evoked by 0.1 nM caerulein. Furthermore, CR1409 completely inhibited caerulein- and gastrin(2-17 ds)-stimulated chymotrypsinogen synthesis, with similar IC50 (4 microM). These results suggest that both peptides induced the synthesis of the secretory enzyme after occupancy of CCK A receptors.

Amylases↗
PubMed1992

Decreased expression of transforming growth factor alpha during differentiation of human pancreatic cancer cells.

The relationship between cell differentiation and transforming growth factor alpha (TGF-alpha) expression in human pancreatic cancer cells was analyzed in Capan 1 cells. These cells differentiate either spontaneously or after butyrate treatment. During differentiation (spontaneous or butyrate induced), TGF-alpha messenger RNA (mRNA) levels decreased, whereas the TGF-beta 1 mRNA levels remained unchanged. TGF-alpha was present in cells as proTGF-alpha, which decreased after butyrate treatment. Secretion of TGF-alpha was not found. Under the two conditions of differentiation, the membrane-bound protein kinase C activity was also reduced. Conversely, long-term phorbol ester treatment increased both membrane-bound protein kinase C activity (260%) and TGF-alpha mRNA level (500%), a not significant increase of TGF-beta 1 mRNA was observed. However, phorbol 12-myristate-13-acetate did not induce TGF-alpha synthesis or secretion. These data suggest that expression of TGF-alpha can be reduced in cancer cells; they also suggest the existence of a relationship between TGF-alpha expression and cell differentiation. In addition, the protein kinase C-induced TGF-alpha mRNA level was not followed by the increase of TGF-alpha biosynthesis, suggesting a translational control. Finally, the expression of TGF-alpha and -beta 1 messengers appears to be differently regulated.

Butyrates↗
PubMed1992

[Transfection of pancreatic acinar cells (AR4-2J) by bFGF modifies cell morphology and biosynthesis of pancreatic secretory enzymes].

Basic fibroblast growth factor (bFGF or FGF-2) is present in the basal membrane of pancreatic cells during the pancreatic embryonic development. The expression of bFGF receptors has been described in normal pancreatic cells. By contrast, pancreatic cancer cells express not only the bFGF receptors but also the bFGF itself. With the aim of understanding the effects induced by the production of bFGF by pancreatic cancer cells, the pancreatic acinar cell line (AR4-2J) was used. AR4-2J cells do not produce bFGF but express bFGF receptors. These cells were transfected with a vector containing the bFGF cDNA encoding the three different forms of bFGF characterized in tumor cells. Results showed that the bFGF expression induced important phenotypic and enzymatic modifications. The transfected cells lost some morphological features of the acinar cells and expressed amylase and lipase at low levels (a 90% decrease for amylase activity, whereas lipase activity was barely detectable). These results suggest that bFGF could be involved in maintaining pancreatic cells in a slightly differentiated state.

Amylases↗
PubMed1991

Characterization of trypsinogens 1 and 2 in two human pancreatic adenocarcinoma cell lines; CFPAC-1 and CAPAN-1.

Proteins with trypsin-like immunoreactivity (first detected by a specific immunoenzymatic assay) were isolated from CAPAN-1 and CFPAC-1 cell culture-conditioned media by chromatography on an immunoadsorbent prepared with a polyclonal antibody directed against trypsin 1. The adsorbed proteins were devoid of free trypsin activity but trypsin activity was present after enterokinase activation demonstrating that the immunoreactive trypsin present in cell supernatants corresponds to trypsinogens. When characterised by Western blotting using a monoclonal antibody directed against human trypsin 1 two protein bands corresponding to trypsinogen 1 (23 kDa) and trypsinogen 2 (25 kDa) gave a positive reaction. These results demonstrate the presence of trypsinogens 1 and 2 in CAPAN-1 and CFPAC-1 cells and in their culture-conditioned media.

Adenocarcinoma↗
PubMed1991

Regulation of amylase and chymotrypsinogen expression by dexamethasone and caerulein in serum-free-cultured pancreatic acinar AR4-2J cells. Influence of glucose.

The direct effects of dexamethasone and caerulein on two pancreatic enzymes, amylase and chymotrypsin, were determined in AR4-2J cells cultured under serum-free conditions at two glucose concentrations (1.0 and 4.5 g/l). In the absence of any hormone, the higher glucose concentration resulted in a 1.6-1.8-fold increase in the basal levels of amylase and chymotrypsinogen. Dexamethasone (50 nM) increased the biosynthesis and mRNA levels of both enzymes at both glucose concentrations. However, dexamethasone had a more pronounced effect on amylase biosynthesis (5-fold induction) than on chymotrypsinogen biosynthesis (1.8-fold induction). The parallel increases in mRNA and protein indicated the existence of pre-translational regulation. This is in contrast with what was observed in serum-containing media, where a translational regulation of amylase biosynthesis took place, probably under the control of both glucose and some serum factors. By contrast, caerulein (10 nM) exerted a more specific action on chymotrypsinogen. The increases in chymotrypsinogen mRNA were 2.2- and 2.1-fold, and increases in chymotrypsin activity were 1.6- and 2.9-fold at 1.0 and 4.5 g of glucose/litre respectively. Thus the regulation by caerulein occurred mainly through the enhancement of chymotrypsinogen transcription and/or mRNA stabilization.

Amylases↗
PubMed1991

Lipid-dependent proliferation of pancreatic cancer cell lines.

Capan 1, a human pancreatic cancer cell line, is routinely grown in 10% fetal calf serum (FCS). In order to characterize the factors needed for its proliferation, FCS was replaced by a synthetic serum (Ultroser G). For Capan 1 proliferation we found that Ultroser G was as efficient as FCS. A subfraction of Ultroser G containing insulin, transferrin, and lipids was found to be responsible for that response since a combination of these compounds reproduced the growth observed with 10% FCS. Lipids stimulated cell proliferation even in the absence of other factors. Other human (MIA PaCa 2, AsPC1, Panc 1) or rat (AR4-2J) pancreatic cancer cell lines tested proliferated in the reconstituted medium containing insulin (100 ng/ml), transferrin (100 micrograms/ml), fatty acid-free albumin (1 mg/ml), and bovine serum lipids (0.7%), as in 10% FCS. Furthermore, the growth of nonpancreatic cell lines (HT29, A431, CREF) was not enhanced by lipids. Lipoproteins were found to be involved in the mitogenic response of pancreatic cells to lipids, whereas phosphatidylcholine and fatty acids were either inefficient or inhibitors (MIA PaCa2 and AR4-2J). Alkaline phosphatase and amylase content, differentiation markers for Capan 1 and AR4-2J cells, respectively, were not modified by the reconstituted medium. These data suggest that lipids, insulin, and transferrin are the essential factors for the proliferation of pancreatic cancer cell lines, reproducing the growth effect of 10% FCS. Moreover, in the absence of most of the seric growth factors, pancreatic cells remained differentiated.

Blood Substitutes↗
PubMed1991

Interstitial 15q deletion without a classic Prader-Willi phenotype.

We report on a newborn boy with pronounced hypotonia, cryptorchidism, minor facial anomalies, congenital heart defect, neurologic anomaly, deafness, renal anomaly, and bifid uvula. The patient has a de novo proximal interstitial deletion of chromosome 15 reaching to band q14, larger than that usually seen in Prader-Willi and Angelman syndromes.

Chromosome Banding↗
PubMed1991

A real-time FFT analyser for monitoring muscle fatigue.

The TMS 32010 system for a real-time muscle fatigue monitor is described; it is based on mean frequency shift in the electromyographic signal (EMG). The mean frequency of the EMG is obtained, in real time, from its power spectrum, with a 2 Hz resolution. This is made possible by combining novel hardware and software.

Computer Systems↗
PubMed1991

Pseudo velocity profiles in carotid artery through Doppler US signal processing.

In this paper a new method of obtaining hemodynamic information from spectral analysis of continuous wave Doppler ultrasound signals is presented. Some considerations of the evaluation of maximum and mean frequencies of the signal arising from scattering in the insonated volume are proposed. A new algorithm to compute the maximum frequency has been applied. Maximum and mean frequency are, respectively, proportional to the maximum and mean velocity in the insonated volume. Their application to mathematical models enables an estimate of velocity profiles into the vessels. The proposed method offers the possibility of matching an accurate evaluation of spectral broadening. In vitro tests and some clinical results involving healthy young people, arteriopathic and stenotic patients show the potential of the method in evaluating different hemodynamic conditions.

Blood Flow Velocity↗
PubMed1991

69,XXX karyotype in a malformed liveborn female. Maternal origin of triploidy.

A liveborn female with a 69,XXX karyotype and clinical features of triploidy syndrome is reported. Main phenotypical features are: intrauterine growth retardation, hypotonicity, micrognathism, low-set ears, ocular anomalies, syndactyly and atrophy of the cerebral cortex and corpus callosum. Study of chromosomal heteromorphisms revealed that triploidy might have arisen through fertilization of a diploid ovum by a haploid sperm (diginy).

Abnormalities, Multiple↗
PubMed1990

A flexible FFT algorithm for processing biomedical signals using a personal computer.

The aim was to demonstrate the possibility of using personal computer PC-DOS (or generally MS-DOS) for real-time (or quasi real-time) biomedical signal processing by adding a simple A/D conversion card and the mathematical coprocessor XXX87. We have realized an assembly written fast Fourier transform (FFT) routine derived from a radix-4 algorithm, which is autogenerated, i.e. an algorithm modified by another algorithm running off-line according to the number of FFT points. The program is implemented as a subroutine to be called upon by high-level language in different procedures. This approach reduces the computational time, which is particularly useful when many Fourier transforms on different data arrays are required. Reported here are two different applications of the routine as applied to the spectral analysis of Doppler ultrasound velocimetry and surface electromyography.

Algorithms↗
PubMed1989

Modulation of enzymatic activities during spontaneous and induced differentiation in a human pancreatic adenocarcinoma cell line CAPAN-1.

Different enzymatic activities were studied in the human pancreatic cancer cell line CAPAN-1 in order to analyze their relation to differentiation. Alkaline phosphatase (Alk Ph), acid phosphatase, aminopeptidase, dipeptidyl peptidase IV, acid and neutral alpha-glucosidases, and acid beta-galactosidase were present. Especially alkaline phosphatase, which we have found to be of the placental type isoenzyme, is being highly expressed. Spontaneous cell differentiation at confluence as well as differentiating agents: sodium butyrate and DMSO, modulated the levels of three enzymes: Alk. Ph., aminopeptidase, and acid alpha-glucosidase. The exposure of the cells to the differentiating agents amplified the modulations occurring during the spontaneous differentiation. Aminopeptidase and acid alpha-glucosidase were found to be induced by differentiation. Alk Ph specific activity was significantly increased by the spontaneous and the butyrate-induced differentiations; whereas DMSO exerted an opposite effect, probably related to its biphasic action on cell proliferation.

Adenocarcinoma↗
PubMed1987

Lipid content of human and rat pancreas.

We analyzed the lipid composition of the human pancreas and performed a parallel study on rat pancreas. Some precautions were taken in order to keep the secretory zymogens as inactive precursors in both tissues. The lipid content of the human pancreas corresponded to 5.5% of the tissue wet weight, lower than that found in pancreas of two-month-old Wistar rats (10%). In man, triglycerides and phospholipids were found at comparable levels, respectively, 37 and 30 mg/g of pancreas wet weight, not far from the values of the rat pancreas. In human pancreas, phosphatidylcholines and lysophosphatidylcholines represented about 40% of the total phospholipid fraction, phosphatidylethanolamines and lysophosphatidylethanolamines 21%, and phosphatidylserines and -inositols were found equally represented with 7.5%. The total cholesterol content accounted for about 4.5% of the total lipids; only 30% was esterified. By comparison, in rat, total cholesterol represented 3.3% of lipids and 90% was esterified. The phospholipids in human pancreas contained high amounts of saturated fatty acids (92%) mainly stearic and palmitic, whereas triglycerides contained equal amounts of saturated and unsaturated fatty acids, principally represented by oleic and palmitic acids. In rats the phospholipids contained only 63% saturated fatty acids (palmitic and stearic) and triglycerides contained 61% unsaturated fatty acids (mainly oleic and linoleic). In terms of lipid composition, there is a greater similarity between human and rat pancreas than with other known pancreas, such as the guinea pig and the ox.

Adult↗