The popularity of neurology in Spain: An analysis of specialty selection. / Popularidad de Neurología en España: análisis de la elección de la especialidad.

INTRODUCTION: Neurology is one of the medical specialties offered each year to residency training candidates. This project analyses the data associated with candidates choosing neurology residency programmes in recent years. METHODS: Data related to specialty selection were obtained from official reports by the Spanish Ministry of Health, Social Services, and Equality. Information was collected on several characteristics of teaching centres: availability of stroke units, endovascular intervention, national reference clinics for neurology, specific on-call shifts for neurology residents, and links with medical schools or national research networks. RESULTS: The median selection list position of candidates selecting neurology training has been higher year on year; neurology was among the 4 most popular residency programmes in 2016. Potential residents were mainly female, Spanish, and had good academic results. The median number of hospitals with higher numbers of beds, endovascular intervention, stroke units, and national reference clinics for neurology is significantly lower. This is also true when centers are analysed by presence of specific on-call shifts for neurology residents and association with medical schools or national research networks. The centres selected by candidates with the highest median selection list position in 2012-2016 were the Clínico San Carlos, 12 de Octubre, and Vall d'Hebron university hospitals. CONCLUSIONS: Neurology has gradually improved in residency selection choices and is now one of the 4 most popular options. Potential residents prefer larger centres which are more demanding in terms of patient care and which perform more research activity.

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.

Activity of a phage-modified RNA polymerase at hybrid promoters. Effects of substituting thymine for hydroxymethyluracil in a phage SP01 middle promoter.

Transcription of bacteriophage SP01 middle promoters is specifically initiated by a complex of the Bacillus subtilis host's RNA polymerase core (E) with the SP01 gene 28 transcription-regulating protein, gp28. Normal SP01 DNA contains hydroxymethyluracil (hmUra) in place of thymine and E . gp28 preferentially transcribes hmUra-containing DNA. Hybrid DNA molecules containing an SP01 middle promoter, PM25 . 1, have been constructed in which one DNA strand contains T and the other hmUra. The major feature of these reciprocal hybrid promoters is that one has, predominantly, T substituted for hmUra in the central -35 recognition sequence in the transcribed strand, while the other has, predominantly, T substituted for hmUra in the -10 recognition sequence in the non-transcribed strand. Binding by the E . gp28 RNA polymerase and transcription of these hybrid promoters and of the normal, all-hmUra, promoter have been compared. Both hybrid promoters are weaker than the normal PM25 . 1 promoter, but the hybrid promoter with T substituted in the -10 sequence is the weakest of the set. The DNase I footprint of the normal PM25 . 1 promoter shows temperature-dependent protection of a relatively long stretch of DNA downstream from the transcriptional start site, correlating with a thermal transition of transcriptional activity of promoter complexes. The stronger of the hybrid promoters also undergoes this transition, but the weaker does not. We discuss these findings in terms of protein-DNA interactions determining specificity for a modified nucleotide at this promoter.

Effect of endothelin on systemic and regional hemodynamics in rats.

In this study we analyzed the changes in systemic haemodynamics induced by endothelin, 1 nmol/kg, given as an i.v. bolus to anaesthetized rats. Endothelin induced a dramatic decrease in cardiac output whereas the total peripheral resistance increased more than two times. In addition, renal blood flow decreased while renal vascular resistance increased to a similar extent. A marked decrease in blood flow to the splanchnic organs was also observed. In conclusion, endothelin seems to modulate peripheral vasomotor tone, at least under certain conditions.

[Hemodynamic changes in an acute pancreatitis experimental model in awaken rats]. / Alteraciones hemodinámicas en un modelo de pancreatitis aguda experimental en ratas despiertas.

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.

[Effect of somatostatin on the hemodynamic changes induced by acute experimental pancreatitis in the conscious rat]. / Efecto de la somatostatina sobre los cambios hemodinámicos inducidos por la pancreatitis aguda experimental en la rata despierta.

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.

[Portal hypertension secondary to an arterioportal fistula. Treatment by embolization]. / Hipertensión portal secundaria a fístula arterioportal. Tratamiento mediante embolización.

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.

[The physiopathology of acute pancreatitis: the role of platelet-activating factor (PAF)]. / Fisiopatología de la pancreatitis aguda: el papel del factor activador plaquetario (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.

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.

Cloning of the gene for myxobacterial hemagglutinin and isolation and analysis of structural gene mutations.

Myxobacterial hemagglutinin (MBHA) is a major developmentally induced protein that accumulates during the period of cellular aggregation in the bacterium Myxococcus xanthus. It has been shown that this lectin is targeted to the cell surface and periplasmic space of developmental cells, suggesting that it may play a role in cell-cell recognition or agglutination. We have cloned the structural gene for MBHA by using synthetic deoxyoligonucleotides containing sequences deduced from the amino acid sequence of MBHA and have used the cloned gene to construct strains of M. xanthus that cannot synthesize MBHA. We found that although the MBHA-deficient strains are delayed in their developmental time course, they are otherwise able to aggregate and sporulate normally. Our results suggest that MBHA may function to increase the efficiency of fruiting-body formation but is not a critical component of cellular aggregation.

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.

Nucleotide sequence of the myxobacterial hemagglutinin gene contains four homologous domains.

Myxococcus xanthus, a Gram-negative bacterium, has a complex life cycle that includes fruiting-body formation, a primitive form of multicellular development. Myxobacterial hemagglutinin (MBHA) is a lectin that is induced during the aggregation phase of fruiting-body formation. We have cloned the gene for MBHA and determined its sequence by the dideoxy chain-termination technique. The sequence data show the probable sites for translational initiation and termination and suggest that MBHA does not contain a cleaved leader signal peptide. The DNA sequence shows four strong internal homologies. The deduced amino acid sequence shows that the protein (Mr 27,920) consists of four highly conserved domains each consisting of 67 amino acids. Thus MBHA is physically multivalent in structure, a requirement for all hemagglutinins.

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.

Effect of portacaval surgical anastomosis on systemic and splanchnic hemodynamics in portal hypertensive, cirrhotic rats.

The effect of surgical end-to-side portacaval anastomosis (PCSA) on systemic and splanchnic circulation has been studied in cirrhotic rats with portal hypertension (CCl4-phenobarbital method) and in control animals. Hemodynamics have been measured using the microsphere technique, with a reference sample for the systemic hemodynamic measurements, and intrasplenic injection for portal systemic shunting rate measurements. Compared with controls, sham-operated (SO) cirrhotic rats showed a hyperdynamic circulation with increased cardiac output (CO) and decreased mean arterial pressure and peripheral resistances. PCSA in control rats induced only a small change in systemic hemodynamics, with parallel decreases in arterial pressure and peripheral resistances, and a small, nonsignificant increase in CO. In cirrhotic rats, PCSA induced a decrease of CO to values similar to those of control rats, with an increase in total peripheral resistances. PCSA induced an increase in hepatic arterial blood flow in control and in cirrhotic rats, portal pressure becoming in this latter group not different from that of control rats. Blood flow to splanchnic organs was higher in SO cirrhotic than in SO control animals. Thus portal venous inflow was also increased in SO cirrhotic rats. PCSA induced an increase in portal venous inflow in control rats, which was only significant in cirrhotic rats when expressed as a percentage of CO. In SO control animals, a significant correlation was observed between total peripheral resistances and splanchnic arteriolar resistances and between CO and splanchnic blood flow. These correlations were not observed in cirrhotic rats. These results do not support the hypothesis that hyperdynamic circulation shown by cirrhotic rats is based on increases in splanchnic blood flow and (or) massive portal systemic shunting.

The phage SPO1-specific RNA polymerase, E.gp28, recognizes its cognate promoters in thymine-containing DNA.

The bacteriophage SPO1 gene 28-encoded protein, gp28, directs specific recognition of viral middle promoters in hydroxymethyluracil-containing DNA by the Bacillus subtilis host's RNA polymerase core. Using appropriately sensitive methods of detection, we have shown that discrimination against thymine-containing DNA is not absolute and that the gp28-containing RNA polymerase precisely initiates transcription at two thymine-containing SPO1 middle promoters.

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.

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.

A transcriptional map of the bacteriophage SP01 genome. I. The major early promoters.

Bacteriophage SP01 early transcripts come predominantly from the terminally repeated 12-kilobase-pair segments of its genome. Much less early RNA comes from a relatively large region of the genome which surrounds the early regulatory gene 28. (The gene 28 protein positively regulates viral middle gene expression.) The major sites at which Bacillus subtilis RNA polymerase holoenzyme binds to SP01 DNA and initiates RNA synthesis have been mapped and the direction of transcription from each of these promoter sites has been determined. There are 12 such sites spanning 11.1 kilobase pairs at each end of the SP01 genome and each set of 12 sites defines a complex set of convergent transcription units.

A transcriptional map of the bacteriophage SP01 genome: II. The major early transcription units.

The genome of the Bacillus subtilis phage SP01 contains a 12.6-kilobase-pair terminal redundancy. The transcription units in this region, which are utilized in vitro by B. subtilis RNA polymerase holoenzme, have been mapped. In vitro transcripts were separated and characterized by gel electrophoresis. Since there is such a large number of promoters in this region, it was necessary to employ conditions of transcription under which only subsets of all the transcripts would be made. Selective synthesis was achieved by transcription of restriction fragments containing a small number of promoters and by dinucleotide priming. Transcription units were mapped by observing the shortening of transcripts that resulted from restriction enzyme cleavage of the template. The mapping indicates the presence of two blocks of overlapping transcription units, oriented so as to yield convergent transcription toward a bidirectional termination region. The frequency of readthrough at the bidirectional terminator is low. Several partial termination sites of differing efficiencies have also been identified, including two that are active only at low ribonucleoside triphosphate concentrations. We also describe an effect of NaCl concentration on the migration of RNA in gels, which is specific for only two of the SP01 early transcripts. This effect may indicate unusual secondary structures for these two RNA molecules.

Role of glucagon in the splanchnic and systemic hemodynamic changes induced by portal-systemic blood shunting.

Portal-systemic blood shunting is often accompanied by hyperglucagonemia and hemodynamic changes. To determine this causal relation, splanchnic and systemic hemodynamics (radioactive microspheres) and plasma glucagon levels (radioimmunoassay) were assessed in conditions of total portal-systemic shunting in portacaval-shunted (PCS) rats and in sham-operated (SO) normal rats. To compare these results, another hemodynamic study was undertaken basally and during glucagon infusion in nonoperated normal rats. PCS rats showed a threefold greater plasma glucagon concentration than SO animals (924 +/- 134 vs. 309 +/- 18 pg/ml, p less than 0.01), and they developed a hyperdynamic splanchnic circulation with higher portal venous inflow than SO rats (8.29 +/- 1.1 vs. 5.09 +/- 0.4 ml/min/100 g, p less than 0.05). Infusion of a pharmacological dose of glucagon in normal rats increased portal venous inflow (from 4.92 +/- 0.33 to 6.24 +/- 0.48 ml/min/100 g, p less than 0.05) so as to imply this hormone in the development of the hyperdynamic splanchnic circulation in conditions of portal-systemic shunting. However, the discrepancies in systemic hemodynamics between PCS and glucagon-infused rats may be a result of the different plasma glucagon levels reached in the two groups.