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Biomedical subjects

J M Romeo

Publications and source records attributed to J M Romeo.

At least 19 recordsLinked to original sources
PubMed1995

Factors associated with hyperdynamic or hypodynamic circulation and role of platelet-activating factor in hemodynamic alterations in bacterial peritonitis in conscious rats.

Male Wistar rats injected intraperitoneally (i.p.) with 10(9) U Escherichia coli ATCC 25922 developed acute bacterial peritonitis. Hemodynamic studies, with microspheres labeled with 103Ru 57Co, and 113Sn, were performed before, 30 min after bacterial injection, and 30 min after administration of either the platelet-activating factor (PAF) antagonist BN-52021 (5 mg/kg body weight) or isotonic saline. A blood sample of 0.3 ml was obtained for bacterial culture and endotoxemia measurements. Plasma PAF levels were measured in a different group of 10 control rats and 20 animals with experimental peritonitis. One group of rats injected with E. coli (n = 13) displayed hyperdynamic circulation, with an increase in cardiac output (CO) from 15.1 +/- 1.2 to 19.4 +/- 1.1 ml/min/100 g body weight and a decrease in total peripheral resistance (TPR) from 19.5 +/- 2.4 to 14.9 +/- 1.1 dynes.s.cm-5 10(-4). Furthermore, these rats showed high endotoxin blood concentrations and low hemoculture levels. The remaining 7 peritonitic rats showed a significant decrease in CO from 16.3 +/- 1.6 to 12.7 +/- 1.2 ml/min/100 g body weight and an increase in TPR from 17.3 +/- 1.8 to 22.6 +/- 2.8 dynes.s.cm-5 10(-4). In addition, these rats showed low endotoxin blood concentrations and high hemoculture levels. Endotoxin blood concentrations were positively correlated with the change in CO (r = 0.87, p < 0.05), and cell hemocultures were positively correlated with CO (r = 0.89, p < 0.05). Rats with high endotoxin blood levels showed higher PAF plasma levels than control rats or peritonitic rats with low endotoxin blood levels. When peritonitic rats were injected with the specific PAF-receptor blocker BN-52021 (5 mg/kg body weight) as a bolus, CO and TPR returned to baseline values in both groups of animals. These data suggest that the hemodynamic changes induced by bacterial peritonitis depend on endotoxemia and bacteremia in opposite ways. In addition, PAF appears to be involved in both the hyperdynamic and hypodynamic hemodynamic changes shown by peritonitic rats.

Animals↗
PubMed1994

Cellular latency in human immunodeficiency virus-infected individuals with high CD4 levels can be detected by the presence of promoter-proximal transcripts.

We have investigated the molecular basis of human immunodeficiency virus type 1 (HIV-1) latency in a tissue culture model and in HIV-infected people. We show that increased levels of Tat, but not Rev, can release the proviruses from latency in U1 cells. The absence of Tat in these cells is manifested by the accumulation of promoter-proximal viral transcripts, whereas the presence of Tat correlates with increased expression of viral proteins and an increase in promoter-distal transcripts. The presence of promoter-proximal transcripts also serves as a marker for latency in humans. We observed the exclusive presence of promoter-proximal viral transcripts in peripheral mononuclear cells from the majority (10/11) of asymptomatic HIV-infected individuals examined. Activation of these cells in vitro, and viremia in vivo, correlated with a switch from promoter-proximal transcription to promoter-distal transcription. These results suggest that the control between latency and replication of HIV in vivo is at the level of transcription elongation.

Base Sequence↗
PubMed1994

Rare detection of hepatitis B and hepatitis C virus genomes by polymerase chain reaction in seronegative donors with elevated alanine aminotransferase.

BACKGROUND: Since screening for antibody to hepatitis C virus (HCV) was introduced in 1990, posttransfusion hepatitis has been reduced to nearly background levels. This has led to reconsideration of the value of testing donated blood for elevated alanine aminotransferase (ALT). The contribution of ALT testing in detecting seronegative infection was evaluated by the performance of polymerase chain reaction (PCR) for hepatitis B virus (HBV) or HCV in plasma from ALT-elevated blood units. STUDY DESIGN AND METHODS: Testing was performed on 375 units of plasma, derived from an equivalent of 47,500 blood donations, with a highly sensitive hemi-nested PCR procedure. Using a triplet of primers directed at the conserved regions of HBV DNA and 5'-noncoding regions of HCV RNA, the hemi-nested PCR assay can reliably amplify 10 viral molecules to levels detectable in ethidium bromide-stained agarose gels. Pools of plasma from groups of four donors were screened with hemi-nested PCR. For any reactive pools, the plasma from individual donors was retested twice on different aliquots. RESULTS: Two of 375 units, both with midrange ALT elevation, were repeatedly reactive in hemi-nested PCR (one each for HBV DNA and HCV RNA). However, samples from the two suspect donors tested 9 and 5 months later revealed no seroconversion, elevated ALT, or viral genomes in hemi-nested PCR. CONCLUSION: The lack of confirmed HBV or HCV infection in this study representing an estimated 47,500 voluntary blood donations suggests that routine ALT testing for further prevention of posttransfusion hepatitis after exclusion of HBV- and/or HCV-seropositive blood may be superfluous.

Alanine Transaminase↗
PubMed1994

[Effect of somatostatin on the hemodynamic changes induced by acute experimental pancreatitis in the conscious rat].

The aim of this study was to determine the hemodynamic effect of somatostatin, either prophylactically or therapeutically, in shock caused by acute necrohemorragic pancreatitis in conscious rats. For this purpose, radioactive microspheres were used in 3 groups (control pancreatitis, therapeutic somatostatin and prophylactic somatostatin), performing a basal and final hemodynamic study. In the control group, acute necrohemorragic pancreatitis resulted in overwhelming shock with decrease of 55% in cardiac output, 58% in renal blood flow, increase in total peripheral resistances of 342%, and death after 70 min. Therapeutic somatostatin decreased cardiac output by 42%, renal blood flow by 47%, and increased total peripheral resistances by 153%. Prophylactic somatostatin decreased cardiac output by 24%, and renal blooded flow by 28%; it increased peripheral resistances by 146%, and improved survival up to 97 min. In conclusion, therapeutic somatostatin, and particularly prophylactic somatostatin, improved hemodynamic shock after acute necrohemorragic pancreatitis in conscious rats.

Acute Disease↗
PubMed1993

An improved method for the detection of hepatitis C virus RNA in plasma utilizing heminested primers and internal control RNA.

The majority of transfusion-associated, non-A, non-B hepatitis cases are caused by hepatitis C virus (HCV), a positive-stranded RNA virus. Although high titers of HCV in clinical specimens have been reported, in some cases extremely low titers of virus are not uncommon. Therefore, an extremely sensitive and reliable assay is required to determine viremia and replication of HCV accurately. We report here the systematic investigation of factors influencing the detection of HCV RNA by a reverse transcription-polymerase chain reaction (RT-PCR) assay utilizing "drop in-drop out" heminested primers derived from the conserved 5' non-coding region of the viral genome. A genetically engineered 5' noncoding region has been constructed and used as an internal control. Addition of the control RNA to each test not only allowed semiquantitation of positive reactions but also validated the performance of reverse transcription and PCR for every specimen. The optimized heminested PCR (HN-PCR) protocol is capable of amplifying one molecule of cloned HCV DNA or 10 molecules of in vitro-transcribed HCV RNA to levels detectable in ethidium bromide-stained agarose gels. We evaluated the improved method for the detection of HCV RNA on a human plasma sample containing the pedigreed strain H of HCV with a chimpanzee infectious dose of 10(6)/ml. Utilizing the internal control RNA, we calculated 2 x 10(7) virions in 1 ml of the original human plasma. The HN-PCR achieves the sensitivity and specificity of the double-nested PCR (DN-PCR) in a simplified format that avoids the false-positive results associated with DN-PCR.

Base Sequence↗
PubMed1993

Analysis of hepatitis C virus RNA prevalence and surrogate markers of infection among seropositive voluntary blood donors.

A novel reverse transcription polymerase chain reaction assay has been developed that uses drop-in-drop-out primers for the heminested amplification of hepatitis C virus complementary DNA. This assay has been used for analysis of the prevalence of hepatitis C virus RNA in a set of 53 plasma specimens from blood donations that were repeatedly reactive for hepatitis C virus antibodies with the first-generation enzyme immunoassay. Of 21 specimens that were also reactive for hepatitis C virus antibodies by a four-antigen recombinant immunoblot assay (recombinant immunoblot assay 2), 20 (95%) contained detectable levels of hepatitis C virus RNA. Cryoprecipitate in three specimens reactive in the recombinant immunoblot assay led to an apparent failure of detecting hepatitis C virus RNA, but repeat tests of redissolved cryoprecipitate subsequently revealed hepatitis C virus RNA. Hepatitis C virus RNA was also detected in plasma from 5 of 29 donors nonreactive by recombinant immunoblot assay. However, evidence of viremia in these donors could not be confirmed on follow-up specimens collected more than 1 yr later. Our results demonstrate that the presence of recombinant immunoblot assay reactivity nearly always indicates hepatitis C viremia and suggest that viremia may be transient or fluctuating among some individuals who are nonreactive for hepatitis C virus antibodies by the recombinant immunoblot assay.

Algorithms↗
PubMed1992

Role of platelet-activating factor in hemodynamic derangements in an acute rodent pancreatic model.

Systemic hemodynamics were assessed in a model of experimental pancreatitis induced in rats by the retrograde injection of sodium deoxycholate, 40%, 1 mL/kg, in the pancreatic duct, using the radioactive microsphere technique before and 25 minutes after pancreatitis induction while blood pressure was stable (n = 10). A 55% decrease in cardiac out-put, a 14% decrease in heart rate, and a 3.3-fold increase in total peripheral resistances, without significant changes in blood pressure, were observed. Renal blood flow decreased by 68%. When rats were given BN-52021, a blocker of platelet-activating factor receptors (5 mg/h, IV; n = 13) coinciding with pancreatitis induction, no significant hemodynamic changes were observed. Animals treated with BN-52021 survived 89 +/- 10 minutes, whereas death occurred 67 +/- 5 minutes after pancreatitis induction in untreated rats (P less than 0.001). A different group of rats with pancreatitis showed higher blood levels of platelet-activating factor (0.28 +/- 0.06 ng/mL; n = 11) than control rats (0.16 +/- 0.03; n = 15; P less than 0.05). Very high levels of platelet-activating factor were found in peritoneal exudate from rats with pancreatitis. These data show an effective protective effect of BN-52021 on the hemodynamic impairment that follows pancreatitis induction, as well as a role of platelet-activating factor in these alterations.

Acute Disease↗
PubMed1992

Determinants of an unusually stable mRNA in the bacterium Myxococcus xanthus.

Myxococcus xanthus is a Gram-negative bacterium which has a complex life cycle that includes development (fruiting body formation). The gene for myxobacterial haemagglutinin, mbhA, is developmentally regulated and highly expressed. In this report we show that the mbhA mRNA is exceptionally stable for a prokaryotic organism, exhibiting a chemical half life (t1/2) of 150 min at 18 h of development. The mbhA mRNA was not stable in vegetatively growing cells nor was it stable when expressed in Escherichia coli. We have used site-directed mutagenesis of the mbhA gene to analyse some of the determinants which mediate the stability of the mbhA transcript. Sequences within the 3'-untranslated region (3'-UTR) were found to be crucial for mRNA stability. This region of mRNA can potentially form an extremely stable stem-loop structure immediately adjacent to the translational stop codon. A deletion within this region caused a 10-fold increase in the decay rate of the transcript. Furthermore, conditions which were associated with reduced mbhA translation or mutations that caused premature termination of translation drastically reduced mRNA stability even in the presence of the wild type 3'-UTR. These results suggest that a significant aspect of mbhA mRNA stability involves a synergistic interaction of the translational machinery with sequence elements within the 3'-UTR.

Bacterial Proteins↗
PubMed1992

[The physiopathology of acute pancreatitis: the role of platelet-activating factor (PAF)].

PAF-acether (platelet-activating factor) is a vasoactive substance appearing in plasma under certain pathological circumstances. The aim of our study was to determine plasma, peritoneal exudate and tissular levels of PAF-acether in bile reflux acute necro-hemorrhagic pancreatitis (ANP) in the conscious rat 60 minutes after induction. As we have previously demonstrated, ANP causes overwhelming shock in conscious rats. PAF-acether levels increased in plasma and peritoneal exudate of rats with ANP. In contrast, tissular PAF levels were similar to basal values. In conclusion, these data suggest a role of PAF-acether in the hemodynamic impairment that follows induction of pancreatitis.

Acute Disease↗
PubMed1991

Transcription of the myxobacterial hemagglutinin gene is mediated by a sigma 54-like promoter and a cis-acting upstream regulatory region of DNA.

Myxobacterial hemagglutinin (MBHA) is a major developmentally induced protein that accumulates during the period of cellular aggregation of the fruiting bacterium Myxococcus xanthus. In this study, DNA sequences mediating the transcriptional regulation of mbhA have been identified. Examination of nucleotide sequences upstream of the start site for mbhA transcription has indicated a region of DNA that bears strong homology to the consensus sequence for promoters recognized by the sigma 54 holoenzyme form of RNA polymerase of Escherichia coli and other eubacteria. Deletion of this sequence completely abolished mbhA transcription. Additionally, a cis-acting DNA element, affecting the efficiency of mbhA transcription, has been mapped within a region of DNA 89 to 276 nucleotides upstream of the sigma 54-like sequence. Transposon insertions, mapping within the cis element, drastically reduced mbhA transcriptional activity. These observations suggest that transcription of mbhA requires a productive interaction between a form of RNA polymerase that recognizes a sigma 54-like sequence and a transcriptional activator that binds to DNA sequences upstream of the mbhA promoter.

Base Sequence↗
PubMed1991

Renal function derangements induced by portacaval anastomosis in normal rats.

The purpose of this study was to determine the renal function derangements that portacaval shunting caused in previously normal rats. Eight rats suffered a surgical portacaval shunt (PCS) and another 8 a sham operation (SHAM). Renal function was investigated by determining urinary volume, sodium, potassium, creatinine and aldosterone excretion, in basal conditions and after sodium overload. Plasma renin concentration and urinary excretion of PGE2, 6-keto-PGF1 alpha and TXB2 were also determined in basal conditions. PCS rats showed increased urinary volume, creatinine excretion and endogenous creatinine clearance, either in basal conditions or after sodium load. After the latter, PCS animals also showed sodium retention and hyperaldosteronuria. PCS caused in basal conditions a striking diminution in urinary excretion of all prostaglandins and no changes in plasma renin. In conclusion, PCS in the normal rat caused a renal dysfunction consisting of polyuria, possibly related to ADH disfunction and an inability to manage a sodium load.

Aldosterone↗
PubMed1991

[Portal hypertension secondary to an arterioportal fistula. Treatment by embolization].

We report a case of arterioportal fistula which was probably the result of percutaneous liver biopsy. Portal hypertension with hemorrhage by esophageal varices was the clinical presentation. We describe the features of the ultrasound, selective arteriography and Doppler ultrasound examination. The fistula was catheterized superselectively and successfully embolized with steel coils.

Adult↗
PubMed1991

[Hemodynamic changes in an acute pancreatitis experimental model in awaken rats].

The aim of the present study was to determine the hemodynamic effect of acute hemorrhagic pancreatitis in conscious rats. For this purpose, radioactive microspheres were used in 3 groups: control (n = 5); 25 min pancreatitis (n = 10); 50 min pancreatitis (n = 10), performing a basal and final (25 or 50 minutes postpancreatitis) hemodynamic study. Acute hemorrhagic pancreatitis was induced in 25 min and 50 min pancreatitis groups overwhelming shock with decrease of 55% in cardiac output, 58% in renal blood flow while total peripheral resistance increased in 342%. No changes were registered the in control group.

Animals↗
PubMed1990

Hepatic haemodynamic changes after portacaval anastomosis in normal, cirrhotic and chronic prehepatic portally hypertensive rats.

Radioactive microspheres were used to determine the hepatic haemodynamic response to portacaval anastomosis in normal, cirrhotic and chronic prehepatic portally hypertensive rats 20 days after operation, and in normal rats 2 months after operation. After 20 days portacaval anastomosis caused a decrease in liver mass only in normal and cirrhotic animals, whereas hepatic arterial blood flow per unit of mass increased in normal (+488 per cent), cirrhotic (+191 per cent) and prehepatic portally hypertensive rats (+133 per cent). Despite these facts, animals with portacaval anastomosis showed a reduced hepatic total perfusion (arterial plus portal inflow) per unit of mass with respect to controls in normal (-53 per cent) and cirrhotic rats (-68 per cent), but not in those with prehepatic portal hypertension. Comparing studies carried out at 2 months with those performed 20 days after portacaval anastomosis in normal rats, some recovery of liver mass and total liver blood flow was observed. In conclusion, portacaval anastomosis produced a limited increase in hepatic arterial blood flow which was unable to preserve liver mass and its total perfusion in normal and cirrhotic animals. In contrast, portacaval anastomosis did not significantly alter liver mass or its perfusion in animals with chronic prehepatic portal hypertension, as both values were previously diminished in controls. Thus, the risk of liver failure after portacaval anastomosis is higher in normal and cirrhotic rats than in those with chronic prehepatic portal hypertension.

Animals↗
PubMed1990

Hemodynamic effects of somatostatin in the rat: relationship with plasma glucagon levels.

Hepatic, splanchnic, and systemic hemodynamic effects of somatostatin infusion, as well as changes in plasma glucagon concentration, were studied in normal rats, using techniques involving radioactive microspheres and radioimmunoassay. Somatostatin infusion caused a decrease in arterial blood flow to the stomach, small intestine and spleen, with the net effect of reducing hepatic portal blood flow and portal pressure. The hepatic arterial blood flow was not altered. The systemic hemodynamic effects of somatostatin were slight, although renal blood flow diminished, Plasma glucagon concentration did not vary immediately after somatostatin infusion. The mechanism of the hemodynamic action of the hormone is not yet clear, but in normal conditions it is not related to the inhibition of glucagon secretion.

Animals↗
PubMed1990

Detection, semiquantitation, and genetic variation in hepatitis C virus sequences amplified from the plasma of blood donors with elevated alanine aminotransferase.

Hepatitis C virus (HCV) is the predominant etiologic agent of posttransfusion non-A, non-B hepatitis, characterized by undulating elevation of alanine aminotransferase (ALT) and chronic liver disease. A commercial enzyme-linked immunosorbent assay detected antibodies to HCV (anti-HCV) in 11 specimens among 101 nontransfusable plasma units obtained from asymptomatic, volunteer blood donors with elevated levels' of ALT. Using a combined reverse-transcription polymerase chain reaction (RT-PCR) assay developed by us, HCV RNA was detected in 0.6 ml of plasma from 8 of 11 (73%) of the anti-HCV-positive but in none of the 90 anti-HCV-negative specimens. The relatively low concentration of HCV RNA could be detected in the remaining three anti-HCV-positive specimens when 2.4 ml of plasma was analyzed. The plasma concentration of virions was estimated to range from 10(2) to 5 x 10(7)/ml. Direct sequencing performed on the PCR-amplified HCV cDNAs (210 base pairs) from three specimens revealed heterogeneity between 2.5 and 8.6% at the nucleotide level and less than 4% at the amino acid level. Our findings demonstrate that RT-PCR can be performed with 2.4 ml of plasma, providing an assay for the direct detection of HCV RNA and confirming the existence of an asymptomatic carrier state for HCV infection in the apparently healthy anti-HCV-positive donors.

Alanine Transaminase↗