Search PubMed⌕ Search

Biomedical subjects

D Franco

Publications and source records attributed to D Franco.

At least 37 records · Page 2Linked to original sources
PubMed2000

Chamber formation and morphogenesis in the developing mammalian heart.

In this study we challenge the generally accepted view that cardiac chambers form from an array of segmental primordia arranged along the anteroposterior axis of the linear and looping heart tube. We traced the spatial pattern of expression of genes encoding atrial natriuretic factor, sarcoplasmic reticulum calcium ATPase, Chisel, Irx5, Irx4, myosin light chain 2v, and beta-myosin heavy chain and related these to morphogenesis. Based on the patterns we propose a two-step model for chamber formation in the embryonic heart. First, a linear heart forms, which is composed of "primary" myocardium that nonetheless shows polarity in phenotype and gene expression along its anteroposterior and dorsoventral axes. Second, specialized ventricular chamber myocardium is specified at the ventral surface of the linear heart tube, while distinct left and right atrial myocardium forms more caudally on laterodorsal surfaces. The process of looping aligns these primordial chambers such that they face the outer curvature. Myocardium of the inner curvature, as well as that of inflow tract, atrioventricular canal, and outflow tract, retains the molecular signature originally found in linear heart tube myocardium. Evidence for distinct transcriptional programs which govern compartmentalization in the forming heart is seen in the patterns of expression of Hand1 for the dorsoventral axis, Irx4 and Tbx5 for the anteroposterior axis, and Irx5 for the distinction between primary and chamber myocardium.

Animals↗
PubMed2000

Suppression of atrial myosin gene expression occurs independently in the left and right ventricles of the developing mouse heart.

Many cardiac genes are broadly expressed in the early heart and become restricted to the atria or ventricles as development proceeds. Additional transcriptional differences between left and right compartments of the embryonic heart have been described recently, in particular for a number of transgenes containing cardiac regulatory elements. We now demonstrate that three myosin genes which become transcriptionally restricted to the atria between embryonic day (E) 12.5 and birth, alpha-myosin heavy chain (MHC), myosin light chain (MLC) 1A and MLC2A, are coordinately downregulated in the compact myocardium of the left ventricle before that of the right ventricle. alpha-MHC protein also accumulates in the right, but not left, compact ventricular myocardium during this period, suggesting that this transient regionalization contributes to fktal heart function. dHAND and eHAND, basic helix-loop-helix transcription factors known to be expressed in the right and left ventricles respectively at E10. 5, remain regionalized between E12.5 and E14.5. Downregulation of alpha-MHC, MLC1A, and MLC2A in iv/iv embryos, which have defective left/right patterning, initiates in the morphological left (systemic) ventricle regardless of its anatomical position on the right or left hand side of the heart. This points to the importance of left/right ventricular differences in sarcomeric gene expression patterns during fktal cardiogenesis and indicates that these differences originate in the embryo in response to anterior-posterior patterning of the heart tube rather than as a result of cardiac looping. Dev Dyn 2000;217:75-85.

Animals↗
PubMed2000

An atrioventricular canal domain defined by cardiac troponin I transgene expression in the embryonic myocardium.

During early cardiac development the atrial myocardium is continuous with the ventricular myocardium throughout the atrioventricular canal. The atrioventricular canal undergoes complex remodelling involving septation, formation of atrioventricular valves and insulation between atria and ventricles except at the level of the atrioventricular node. Understanding of these processes has been hampered by the lack of markers specific for this heart region. We have generated transgenic mice expressing beta-galactosidase under the control of the cardiac troponin I gene that show transgene expression mainly confined to the atrioventricular canal myocardium during early embryonic development. With further development beta-galactosidase positive cells are observed in the atrioventricular node and in the lower rim of both right and left atria, supporting the view that atrioventricular canal myocardium contributes to the atrioventricular node and is in part incorporated into the lower rim of the atria. These results identify the atrioventricular canal myocardium as a distinct transcriptional domain.

Animals↗
PubMed2000

[Effect of portal branch ligation on liver regeneration in the rat].

GOAL: The aim of this study was to assess liver regeneration after partial portal ligation. METHODS: 70% partial portal occlusion was obtained by ligation of the left portal vein branch. Total liver weight ratio were measured 96 hours after partial portal occlusion and in sham operated animals. The kinetics of hepatocytes division was evaluated by measuring the incorporation of 5-bromo-21-deoxyuridine into replicating cells at various time points by immunohistochemistry. RESULTS: Partial portal occlusion did not alter the total liver weight 96 hours after surgery. It resulted in atrophy of the ligated lobes and hypertrophy of the lobes with preserved portal flow. Hypertrophy was associated to an increase of the percentage of replicating hepatocytes. The replication rate was maximum at 28 hours with a peak at 12.5% and was prolonged beyond the 48th hour. CONCLUSIONS: Partial portal occlusion results in major and prolonged regeneration process in the liver lobes with preserved portal flow.

Animals↗
PubMed2000

Isolation by size of epithelial tumor cells : a new method for the immunomorphological and molecular characterization of circulatingtumor cells.

We have developed a new assay, ISET (isolation by size of epithelial tumor cells), which allows the counting and the immunomorphological and molecular characterization of circulating tumor cells in patients with carcinoma, using peripheral blood sample volumes as small as 1 ml. Using this assay, epithelial tumor cells can be isolated individually by filtration because of their larger size when compared to peripheral blood leukocytes. ISET parameters were defined using peripheral blood spiked with tumor cell lines (HepG2, Hep3B, MCF-7, HeLa, and LNCaP). ISET can detect a single, micropipetted tumor cell, added to 1 ml of blood. We also demonstrate that fluorescence in situ hybridization can be used to perform chromosomal analyses on tumor cells collected using ISET. Polymerase chain reaction-based genetic analyses can be applied to ISET-isolated cells, and, as an example, we demonstrate homozygous p53 deletion in single Hep3B cells after filtration and laser microdissection. Finally, we provide evidence for the in vivo feasibility of ISET in patients with hepatocellular carcinoma undergoing tumor resection. ISET, but not reverse transcriptase-polymerase chain reaction, allowed analysis of cell morphology, counting of tumor cells, and demonstration of tumor microemboli spread into peripheral blood during surgery. Overall, ISET constitutes a novel approach that should open new perpectives in molecular medicine.

Carcinoma, Hepatocellular↗
PubMed2000

Evaluation of extracts from Gevuina avellana hulls as antioxidants.

The antioxidant activity of the extracts from Gevuina avellana hulls was evaluated and compared with that of BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole), using the beta-carotene bleaching assay, the accelerated oxidation of crude soybean oil, and the 2,2-diphenyl-beta-picrylhydrazyl (DPPH) radical scavenging method. Solvents of different polarity were used to obtain the extracts. Both the extraction yield and the antioxidant activity were strongly dependent on the solvent. The ethanol and diethyl ether soluble fractions were the most active with the beta-carotene assay. Ethanol and methanol extracts were the most active in hydrogen radical scavenging activity. Water and methanol inhibited more efficiently the oxidation of soybean oil at 70 and 80 degrees C, respectively. As a general trend, increased antioxidant activity was observed for increased extract concentration. Except the acetone extracts, all were stable after 6 months storage at 4 degrees C. The ethanol solubles from G. avellana hulls present antioxidant activity similar to that of synthetic antioxidants and to other reported residual agroindustrial materials.

Antioxidants↗
PubMed2000

Analgesic effect of low-dose intrathecal morphine and bupivacaine in laparoscopic cholecystectomy.

We assessed the peri-operative analgesic efficiency of low-dose intrathecal morphine combined with a low dose of bupivacaine after elective laparoscopic cholecystectomy since postoperative pain in such procedures, although less than after a conventional open technique, may be significant, particularly during the first 12-24 h. After informed consent, 34 ASA I or II patients were randomly allocated to one of two groups to receive either a lumbar intrathecal injection of morphine (75 or 100 microg) combined with 5 mg of isobaric bupivacaine (spinal group) or a subcutaneous injection of a saline solution (control group). Intra-operatively, opioid requirements, blood pressure response and heart rate changes after insufflation were recorded. Postoperatively, morphine requirements, pain scores and opioid-related side-effects were assessed by a physician blinded to the randomisation. Intra-operative opioid requirements did not differ significantly between groups. Mean (SD) postoperative morphine requirements were significantly lower in the spinal group [13 (10) vs. 23 (10) mg; p = 0.04] as were postoperative pain scores (p < 0.001). Side-effects were of comparable incidence and severity between groups. Low-dose intrathecal morphine combined with low-dose bupivacaine provided effective postoperative analgesia for elective laparoscopic cholecystectomy.

Adult↗
PubMed2000

Activation of V(D)J recombination induces the formation of interlocus joints and hybrid joints in scid pre-B-cell lines.

V(D)J recombination is the mechanism by which antigen receptor genes are assembled. The site-specific cleavage mediated by RAG1 and RAG2 proteins generates two types of double-strand DNA breaks: blunt signal ends and covalently sealed hairpin coding ends. Although these DNA breaks are mainly resolved into coding joints and signal joints, they can participate in a nonstandard joining process, forming hybrid and open/shut joints that link coding ends to signal ends. In addition, the broken DNA molecules excised from different receptor gene loci could potentially be joined to generate interlocus joints. The interlocus recombination process may contribute to the translocation between antigen receptor genes and oncogenes, leading to malignant transformation of lymphocytes. To investigate the underlying mechanisms of these nonstandard recombination events, we took advantage of recombination-inducible cell lines derived from scid homozygous (s/s) and scid heterozygous (s/+) mice by transforming B-cell precursors with a temperature-sensitive Abelson murine leukemia virus mutant (ts-Ab-MLV). We can manipulate the level of recombination cleavage and end resolution by altering the cell culture temperature. By analyzing various recombination products in scid and s/+ ts-Ab-MLV transformants, we report in this study that scid cells make higher levels of interlocus and hybrid joints than their normal counterparts. These joints arise concurrently with the formation of intralocus joints, as well as with the appearance of opened coding ends. The junctions of these joining products exhibit excessive nucleotide deletions, a characteristic of scid coding joints. These data suggest that an inability of scid cells to promptly resolve their recombination ends exposes the ends to a random joining process, which can conceivably lead to chromosomal translocations.

Abelson murine leukemia virus↗
PubMed1999

Beta-catenin mutations in hepatocellular carcinoma correlate with a low rate of loss of heterozygosity.

To determine the frequency of Wnt/Wingless beta catenin pathway alteration in human hepatocellular carcinoma, a beta catenin and APC gene mutation screening was performed in a series of 119 tumors. An activating beta catenin mutation in exon 3 was found in 18% of the cases. Among tumors lacking beta catenin mutation, no APC mutation has been evidenced in a subset of 30 cases tested. The correlation between beta catenin mutation status and chromosome segment deletions was studied on a set of 48 hyperploid tumors. Chromosome 1p, 4q and 16p deletions were significantly associated with the absence of beta catenin mutation (P<0.05). Furthermore the Fractional Allelic Loss was significantly smaller in the beta catenin mutated tumors than in the non-mutated tumors (0.12 versus 022). Taken together, these results suggest, the existence of two carcinogenesis mechanisms. The first mechanism implies a beta catenin activating mutation associated with a low rate of loss of heterozygosity. The second mechanism, operating in a context of chromosomal instability, would involve tumor suppressor genes.

Aneuploidy↗
PubMed1999

Expression of mutated hepatitis B virus X genes in human hepatocellular carcinomas.

To explore the role of hepatitis B virus (HBV) X protein in liver carcinogenesis, independently from its role in viral replication, we have analyzed X gene structure and expression in tumorous and non-tumorous tissues obtained from 9 hepatitis B surface antigen (HBsAg)-negative, HBV DNA-positive patients. HBV replication was undetectable in tumorous tissues. HBV X gene was truncated at its 3' end in 5 of 9 tumorous tissues and 1 of 8 non-tumorous livers. Sequence analysis performed on uninterrupted X genes from 3 tumors and 3 surrounding non-tumorous tissues showed a high rate of mutations, selectively in the tumorous livers. In 1 of the 3 tumors, a frameshift mutation induced a new stop at codon 129. HBV RNAs were tested by reverse transcriptase-polymerase chain reaction (RT-PCR) with surface (S), core (C) and X specific primers. X, but not S and C, RNA expression was found in 6 of 8 tumors and in 6 of 7 non-tumorous tissues. This finding was consistent with immunohistochemical detection of X, but not S and C, antigens in all tumors also expressing X RNA. Our results provide evidence for selective expression of HBV X, but not S and C, RNA and protein in the tumorous and non-tumorous tissue of HBsAg-negative, HBV DNA-positive patients. It also shows that the structure of the X gene is modified (interrupted or highly mutated) in the majority of tumorous livers. Taken together, our findings are consistent with a potential role of mutated X proteins in HBV-related liver oncogenesis.

Adolescent↗
PubMed1999

Myosin light chain 2a and 2v identifies the embryonic outflow tract myocardium in the developing rodent heart.

The embryonic heart consists of five segments comprising the fast-conducting atrial and ventricular segments flanked by slow-conducting segments, i.e. inflow tract, atrioventricular canal and outflow tract. Although the incorporation of the flanking segments into the definitive atrial and ventricular chambers with development is generally accepted now, the contribution of the outflow tract myocardium to the definitive ventricles remained controversial mainly due to the lack of appropriate markers. For that reason we performed a detailed study of the pattern of expression of myosin light chain (MLC) 2a and 2v by in situ hybridization and immunohistochemistry during rat and mouse heart development. Expression of MLC2a mRNA displays a postero-anterior gradient in the tubular heart. In the embryonic heart it is down-regulated in the ventricular compartment and remains high in the outflow tract, atrioventricular canal, atria and inflow tract myocardium. MLC2v is strongly expressed in the ventricular myocardium and distinctly lower in the outflow tract and atrioventricular canal. The co-expression of MLC2a and MLC2v in the outflow tract and atrioventricular canal, together with the single expression in the atrial (MLC2a) and ventricular (MLC2v) myocardium, permits the delineation of their boundaries. With development, myocardial cells are observed in the lower endocardial ridges that share MLC2a and MLC2v expression with the myocardial cells of the outflow tract. In neonates, MLC2a continues to be expressed around both right and left semilunar valves, the outlet septum and the non-trabeculated right ventricular outlet. These findings demonstrate the contribution of the outflow tract to the definitive ventricles and demonstrate that the outlet septum is derived from outflow tract myocardium.

Animals↗
PubMed1999

Liver resection and needle liver biopsy cause hematogenous dissemination of liver cells.

We have investigated whether liver resection and needle liver biopsy cause dissemination of liver cells into peripheral blood circulation, using a reverse-transcription polymerase chain reaction (RT-PCR)-based assay targeted against alpha-fetoprotein (AFP) mRNA. Twelve patients with and 16 without primary liver cancer (PLC) undergoing liver resection were tested before skin incision, after liver mobilization, after hepatic parenchyma transection, after abdominal wall suture, and 4 days after surgery. Two patients with and 20 without PLC were tested before, 20 minutes after, and 24 hours after needle liver biopsy. Six of 14 patients with and 0 of 36 patients without PLC scored positive before intervention (P <.001). Liver cell spreading was induced at different times after surgery and liver biopsy in 14 of 14 patients with but also 23 of 36 without PLC (P <.05). We conclude that liver resection and needle liver biopsy induce release of cells from the liver, which are not necessarily liver tumor cells, into the peripheral blood circulation. This may be, however, an important mechanism of liver cancer cell dissemination deserving further investigations.

Adult↗
PubMed1999

Permissiveness of human biliary epithelial cells to infection by hepatitis C virus.

The cellular tropism of hepatitis C virus (HCV) is an important but much debated issue. Permissivity to HCV of biliary cells has never been demonstrated. In this context, we used gallbladder epithelial cells (GBEC) as a model of the more proximal biliary epithelium. These cells were isolated from HCV-positive and -negative individuals and cultured for up to 40 days. Biliary cells from HCV-negative subjects were infected in vitro with various inocula. The retention of GBEC functional characteristics was assessed by the expression of cystic fibrosis transmembrane conductance regulator (CFTR). All 12 GBEC tested from HCV-negative patients were successfully infected by HCV. This was assessed by: 1) the detection of HCV-RNA positive and negative strands; 2) the detection of the viral capsid by immunofluorescence; and 3) the combination of single-strand conformation polymorphism (SSCP) and HVR1 sequence analysis demonstrating the distinct majoritary HCV genomes in serum and in GBEC. The level of HCV RNA in cell extracts and supernatants was low, but HCV infection was highly reproducible. Our results expand those showing the cellular tropism of HCV, and demonstrate the sensitivity of biliary cells to HCV infection. This might have an important impact in terms of pathogenesis and pathological features of HCV infection. In addition, given the easy access to these cells and the high reproducibility of in vitro infection, they should constitute an important tool for studies aimed at analyzing the issue of HCV penetration and neutralizing antibodies.

Base Sequence↗
PubMed1999

Elective laparoscopic sigmoid colectomy for diverticulitis. Results of a prospective study.

BACKGROUND: We undertook a prospective evaluation of elective laparoscopic sigmoid colectomy for diverticulitis in order to assess the risks and benefits of this approach. METHODS: Between November 1992 and November 1996, 54 consecutive patients were included in this study. Their mean age was 59 +/- 13 years (range, 36-81). The number of attacks of diverticulitis before colectomy ranged from one to four (mean, 2.2 +/- 0.7). The operative technique consisted of elective division of the inferior mesenteric vessels, left colonic flexure mobilization, and colorectal anastomosis using the cross-stapling technique. RESULTS: Five procedures (9.2%) were converted. The primary cause for conversion was obesity. These patients had a simple postoperative course. There were no postoperative deaths. Three patients (6.1%) developed abdominal complications, and four patients (8.2%) had abdominal wall complications. Postoperative paralytic ileus lasted only 2.3 +/- 0.7 days (range, 1-6), allowing for a rapid reintroduction of regular diet. The mean postoperative hospital stay was 6.4 +/- 2.7 days (range, 4-15). CONCLUSIONS: Elective laparoscopic colectomy for diverticulitis is feasible in most cases. In most cases, the operative risk is low and the postoperative course is uneventful. Elective sigmoid laparoscopic colectomy should be considered a good therapeutic option for symptomatic diverticulitis.

Adult↗
PubMed1999

[Laparoscopic cholecystectomy in acute cholecystitis].

PURPOSE: To determine the feasibility, operative risk and patients' benefit of laparoscopy in emergency cholecystectomy for acute calculous cholecystitis. PATIENTS AND METHODS: From January 1991 to December 1998, 234 patients with acute calculous cholecystitis were operated on by emergency laparoscopic cholecystectomy. There were 131 women and 103 men (mean age: 57 years), (Asa 2: 48%, Asa 3: 10%). In seven patients, choledocolithiasis was detected by endoscopic ultrasonography and preoperatively treated by endoscopic sphincterotomy. The mean delay between in-hospital admission and cholecystectomy was 20 hours (2-160). Cholecystectomy was performed with primary approach of Calot's triangle. Intraoperative cholangiography, selectively performed (n = 70), detected choledocolithiasis in three patients. RESULTS: The mean duration of surgery was 149 minutes (62-313). The conversion rate was 13% and decreased through the years. The postoperative complication rate was 18%. Eight patients (3.4%) had an abdominal complication. One patient (0.4%) died of bile peritonitis after intraoperative undetected main bile duct injury. The mean postoperative hospital stay was 6.04 days. It was 3.5 days only, very old patients and those with severe associated disease being excluded. CONCLUSION: Laparoscopy appears to be a good approach for emergency cholecystectomy in patients with acute calculous cholecystitis.

Acute Disease↗
PubMed1999

Hepatocarcinoma-intestine-pancreas/pancreatic associated protein (HIP/PAP) is expressed and secreted by proliferating ductules as well as by hepatocarcinoma and cholangiocarcinoma cells.

Hepatocarcinoma-intestine-pancreas/pancreatic associated protein (HIP/PAP) gene was identified because of its increased expression in 25% of human hepatocellular carcinoma. HIP/PAP protein, a C-type lectin, binds laminin, acts as an adhesion molecule for hepatocytes, and has also been described as an acute phase secretory protein during acute pancreatitis in humans and rats. We investigated HIP/PAP protein expression in patients with various liver diseases associated with ductular reaction. At the same time, we analyzed patients with hepatocellular carcinoma and cholangiocarcinoma, and tested HIP/PAP protein levels in sera to establish the pattern of secretion. Our data show that HIP/PAP expression was not restricted to hepatocellular carcinoma, but was also detected in cholangiocarcinoma cells as well as in reactive non-malignant bile ductules. In contrast, HIP/PAP protein expression was undetectable in normal mature hepatocytes, but some ductular cells localized at the interface of portal tracts with parenchyma were HIP/PAP immunoreactive in normal liver. Finally, we present evidence that HIP/PAP serum levels were increased in 21/28 (75%) patients with hepatocellular carcinoma, and in 25/51 (49%) patients with nonmalignant cirrhosis. Altogether, these results suggest that HIP/PAP protein may be implicated in hepatocytic and cholangiolar differentiation and proliferation.

Acute-Phase Proteins↗
PubMed1999

Treatment with temozolomide and poly(ADP-ribose) polymerase inhibitors induces early apoptosis and increases base excision repair gene transcripts in leukemic cells resistant to triazene compounds.

Methylating triazenes have shown marked antileukemic effects, possibly through generation of a variety of DNA adducts. Cells tolerant to O6-methylguanine due to a defect in the mismatch repair system (MRS), might become sensitive to other methyl adducts, by inhibiting the N-methylpurine repair, which requires base excision repair (BER) and poly(ADP-ribose) polymerase (PADPRP). Therefore, MRS-deficient Jurkat leukemic cells resistant to methylating triazenes, have been treated with temozolomide (TZM) and PADPRP inhibitors. Expression of PADPRP or molecules involved in the BER system [3-methylpurine-DNA glycosylase (MPG) and X-ray repair cross-complementing 1 (XRCC1)], have been explored. Cytotoxic effects of TZM associated with PADPRP inhibitors are evident shortly after treatment, suggesting that completion of cell division is not required for the lethal effect of the drug combination. Increase of PADPRP or MPG transcripts was found after treatment with TZM alone or combined with PADPRP inhibitor. XRCC1 transcript was positively modulated only in the case of drug combination. This could suggest that in the presence of PADPRP inhibitor, persistence of DNA damage triggers XRCC1 transcription. Our results suggest that association of TZM and PADPRP inhibitors might be of benefit for MRS-deficient malignancies unresponsive to the methylating agent.

Antineoplastic Agents, Alkylating↗