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Biomedical subjects

D Romero

Publications and source records attributed to D Romero.

At least 55 records · Page 3Linked to original sources
PubMed1998

Description of the characteristics of cases with noncontiguous neural tube defects identified in a series of consecutive births.

Van Allen et al. [(1973) Am. J. Med. Genet. 47:723-743] provided evidence for multisite closure of the neural tube in humans. Reynolds et al. [(1995) Proceedings of the Greewood Genetic Center 14:70-71] and Seller [(1995) J. Med. Genet. 32:205-207] described 13 and seven cases of noncontiguous neural tube defects (NTDs) respectively and concluded that the presence of noncontiguous NTDs cannot be explained on the basis of the model of a single initiation site with bidirectional closure. Here we present a series of 14 consecutive infants with noncontiguous NTDs, describing their characteristics. These show that noncontiguous NTDs are clinically heterogeneous, may have differences in sex ratio, and could have causal heterogeneity. The different combinations of closure failure defects have shown proportions in our population that are different from those in the populations studied by Reynolds et al. and Seller.

Birth Weight↗
PubMed1998

Anaesthetic management of the surgical separation of a pair of thoracopagus-cardiopagus twins.

We describe the anaesthetic management of the surgical separation of a pair of thoracopagus-cardiopagus twins with a common right atrium and a myocardial tissue bridge containing vascular channels between their ventricles. One of them died during the procedure, the surviving twin is now two years old. The survival of one twin for two years without significant sequelae, after the surgical separation of twins with shared right atrium and fused ventricles, has not previously been reported. Careful preoperative assessment is essential to anticipate potential serious problems during the procedure.

Anesthesia, General↗
PubMed1998

Multiple recombination events maintain sequence identity among members of the nitrogenase multigene family in Rhizobium etli.

A distinctive characteristic of the Rhizobium genome is the frequent finding of reiterated sequences, which often constitute multigene families. Interestingly, these families usually maintain a high degree of nucleotide sequence identity. It is commonly assumed that apparent gene conversion between reiterated elements might lead to concerted variation among members of a multigene family. However, the operation of this mechanism has not yet been demonstrated in the Rhizobiaceae. In this work, we employed different genetic constructions to address the role of apparent gene conversion as a homogenizing mechanism between members of the plasmid-located nitrogenase multigene family in Rhizobium etli. Our results show that a 28-bp insertion into one of the nitrogenase reiterations can be corrected by multiple recombination events, including apparent gene conversion. The correction process was dependent on the presence of both a wild-type recA gene and wild-type copies of the nitrogenase reiterations. Frequencies of apparent gene conversion to the wild-type nitrogenase reiterations were the same when the insertion to be corrected was located either in cis or in trans, indicating that this event frequently occurs through intermolecular interactions. Interestingly, a high frequency of multiple crossovers was observed, suggesting that these large plasmid molecules are engaging repeatedly in recombination events, in a situation akin to phage recombination or recombination among small, high-copy number plasmids.

Base Sequence↗
PubMed1998

Genes essential for nod factor production and nodulation are located on a symbiotic amplicon (AMPRtrCFN299pc60) in Rhizobium tropici.

Amplifiable DNA regions (amplicons) have been identified in the genome of Rhizobium etli. Here we report the isolation and molecular characterization of a symbiotic amplicon of Rhizobium tropici. To search for symbiotic amplicons, a cartridge containing a kanamycin resistance marker that responds to gene dosage and conditional origins of replication and transfer was inserted in the nodulation region of the symbiotic plasmid (pSym) of R. tropici CFN299. Derivatives harboring amplifications were selected by increasing the concentration of kanamycin in the cell culture. The amplified DNA region was mobilized into Escherichia coli and then into Agrobacterium tumefaciens. The 60-kb symbiotic amplicon, which we termed AMPRtrCFN299pc60, contains several nodulation and nitrogen fixation genes and is flanked by a novel insertion sequence ISRtr1. Amplification of AMPRtrCFN299pc60 through homologous recombination between ISRtr1 repeats increased the amount of Nod factors. Strikingly, the conjugal transfer of the amplicon into a plasmidless A. tumefaciens strain confers on the transconjugant the ability to produce R. tropici Nod factors and to nodulate Phaseolus vulgaris, indicating that R. tropici genes essential for the nodulation process are confined to an ampliable DNA region of the pSym.

Agrobacterium tumefaciens↗
PubMed1997

Generation of Rhizobium strains with improved symbiotic properties by random DNA amplification (RDA)

To select for bacterial strains with enhanced phenotypes, random fragments of a whole genome, or a defined region of the genome, are cloned in a nonreplicating vector. The resulting plasmids are integrated by recombination into the homologous DNA region of the original strain. Integration gives rise to a nontandem direct duplication of the corresponding DNA region separated by the vector moiety of the plasmid. Recombination between the direct repeats leads to tandem duplication and further amplification of the entire integrated DNA, including the vector. Bacteria harboring the amplified DNA are selected by increasing the dosage of an antibiotic corresponding to a resistance marker of the integrated vector. Pooled strains carrying amplifications are then challenged with a selective pressure for the desired phenotype. After repeated selection cycles, the most fit strains are isolated. We used this process, which we called random DNA amplification, to select Rhizobium strains with increased competitiveness for nodule formation. Derivatives containing randomly amplified DNA regions of the symbiotic plasmid of Rhizobium tropici CFN299 strain were generated. Pools of amplified strains were inoculated onto various tropical legumes. After several cycles of selection through plants, amplified derivatives showing an increased competitiveness for nodule formation with the leguminous plant Macroptilium atropurpureum were obtained.

Cloning, Molecular↗
PubMed1997

Gene amplification and genomic plasticity in prokaryotes.

Gene amplification is a common feature of the genome of prokaryotic organisms. In this review, we analyze different instances of gene amplification in a variety of prokaryotes, including their mechanisms of generation and biological role. Growing evidence supports the concept that gene amplification be considered not as a mutation but rather as a dynamic genomic state related to the adaptation of bacterial populations to changing environmental conditions or biological interactions. In this context, the potentially amplifiable DNA regions impose a defined dynamic structure on the genome. If such structure has indeed been selected during evolution, it is a particularly challenging hypothesis.

Gene Amplification↗
PubMed1997

Injectable contraceptive discontinuation and subsequent unintended pregnancy among low-income women.

OBJECTIVES: This study investigated rates of discontinuation of the recently introduced injectable contraceptive depot medroxyprogesterone acetate (DMPA) and postdiscontinuation rates of unprotected intercourse and unintended pregnancy. METHODS: A sample of 402 low-income, urban, minority women were interviewed when they initiated DMPA use and 12 months later. RESULTS: The 12-month life-table discontinuation rate was 58%, with half of the discontinuers stopping after only one injection. Menstrual changes and other side effects were the most frequently cited reasons for discontinuation. Approximately half of the discontinuers at risk for unintended pregnancy either did not make the transition to another contraceptive or used contraception only sporadically. The cumulative unintended pregnancy rate by 9 months postdiscontinuation was 20%. CONCLUSIONS: DMPA initiators were at substantial risk for unintended pregnancy because most quickly discontinued use and did not make the transition to consistent use of another contraceptive.

Adolescent↗
PubMed1997

[Internal ophthalmoplegia: a rare complication of varicella].

INTRODUCTION: Internal ophthalmoplegia complicating Chickenpox is rare. Fifteen cases have been reported so far. CLINICAL CASE: We reported a new case of this neurological complication in a 3 1/2 year old girl that 6 days after the onset of the typical rash, the right pupil was dilated and fixed to light and accommodation. Pupillary dilatation and accommodative paralysis persist after five years, but spectacle correction has restored the visual acuity.

Chickenpox↗
PubMed1996

Inflammatory extracavitary right atrial mass and pulmonary thromboembolism.

A 40 year old male patient diagnosed as having pulmonary thromboembolism, was found to have a right atrial mass, after being subjected to an echocardiogram, a CT thoracic Scan and magnetic resonance imaging. An intracardiac exploration by cardiopul-monary bypass was performed. The mass was located and excised, but in fact found to be an extracardiac, inflammatory and cavitated mass. The wall of the right atrium was infiltrated due to the inflammatory process. This case illustrates the advantage of echocardiography, followed by surgery, in the clinical diagnosis and also shows how to treat cardiac masses and tumors.

Adult↗
PubMed1996

[A new classification of lower infarcts with important prognostic significance].

BACKGROUND: The initial therapy of acute myocardial infarction is often determined by the electrocardiogram. OBJECTIVE: To evaluate a classification of inferior myocardial infarctions according to the first electrocardiogram. DESIGN AND SETTING: Prospective study in a coronary care unit. PATIENTS: 116 patients admitted due to a first acute myocardial infarction of the inferior wall. METHODS: "Type 1" electrocardiogram was defined as ST segment elevation without distortion of the QRS. Patients were considered "type 2" when, besides ST segment elevation, they presented a distortion of the terminal portion of the QRS complex in two inferior leads. MAIN RESULTS: Twenty-nine patients (25%) were considered "type 2". These patients were older and had worse Killip class than "type 1". The mortality rate was 1.2% in "type 1", and 24.1% in "type 2" (p = 0.0002). After multivariate analysis, which included Killip class, age, smoking, type of electrocardiogram and fibrinolysis, the type of electrocardiogram remained significantly predictive of death (p = 0.014). CONCLUSIONS: We conclude that "type 2" electrocardiogram is an independent predictor of adverse outcome in inferior infarctions. Further investigation is needed concerning its implications in the clinical management of these patients, although reperfusion therapy is warranted.

Adult↗
PubMed1995

Sinus tachycardia and J wave masquerading as atrial flutter.

The admission electrocardiogram (ECG) from a patient with severe heart failure was considered diagnostic of atrial flutter with 2:1 atrioventricular conduction. Slowing of the heart rate revealed sinus tachycardia with prominent 'J' waves that had been previously thought to be 'F' waves.

Aged↗
PubMed1995

Acute myocardial infarction in a young man after heat exhaustion.

A 33-year-old man with heat exhaustion was admitted to our hospital suffering from severe chest pain. Serum creatine kinase elevation and new Q waves revealed myocardial infarction of the inferior wall. Technetium-99m-pyrophosphate suggested diffuse myocardial damage, although the left ventricular function was normal by echocardiography. This case highlights the importance of early recognition of heat stroke and heat exhaustion, as they are associated with widespread tissue injury.

Adult↗
PubMed1995

Discrete amplifiable regions (amplicons) in the symbiotic plasmid of Rhizobium etli CFN42.

Frequent tandem amplification of defined regions of the genome, called amplicons, is a common characteristic in the genomes of some Rhizobium species, such as Rhizobium etli. In order to map these zones in a model Rhizobium replicon, we undertook an analysis of the plasticity patterns fostered by amplicons in the pSym (390 kb) of R. etli CFN42. Data presented in this article indicate the presence of four amplicons in pSym, used for the generation of tandem amplifications and deletions. The amplicons are large, ranging from 90 to 175 kb, and they are overlapping. Each amplicon is usually flanked by specific reiterated sequences. Formation of amplifications and deletions requires an active recA gene. All the amplicons detected are concentrated in a zone of roughly one-third of pSym, covering most of the symbiotic genes detected in this plasmid. No amplicons were detected in the remaining two-thirds of pSym. These data support the idea that most of the known symbiotic genes in this plasmid are located in a genomic region that is prone to the formation of frequent tandem amplification.

Crossing Over, Genetic↗
PubMed1995

[Tuberculous splenic abscess in an immunocompetent patient].

Splenic tuberculosis is a rare entity. The case of an 18-year old patient admitted for fever and general malice is described. Echography and abdominal CT showed a hypodense image localized in the spleen. Splenic tuberculosis was diagnosed upon observation of alcohol acid resistant bacilli (AARB) in the biopsy obtained by punction of the abscess. Correct tuberculostatic treatment led to disappearance of the splenic abscess with no further therapeutic measures being required.

Abscess↗
PubMed1995

[Age is the independent prognostic factor in acute myocardial infarct. The clinical course of infarct in the elderly patient].

We analyze the influence of age in the evolution of patients with acute myocardial infarction admitted to our Coronary Care Unit throughout two years (1990 and 1991). All 542 patients admitted during this period were classified in three groups: 299 less than 65 year old (group A), 170 between 65 and 74 year old (group B), and 73 with 75 year old or more (group C). Aged patients had a worse clinical condition, with significantly more previous heart failure, diabetes or hypertension, and the Killip's class was worse in group C than in group B, and worse in this than in group A (p = 0.00000). The mortality rate was 6.7% in group A, 12.9% in group B, and 31.5% group C (p = 0.00000). After a multivariate analysis, only three factors were significantly associated to prognosis: previous stroke, Killip's class, and group of age. Fibrinolytic therapy and coronary arteriography were less frequent with old people (p = 0.00000 and p = 0.00000 respectively). We conclude that age is an independent factor of prognosis during myocardial infarction. Old people have a worse clinical condition and the treatment is less aggressive than in young people.

Age Factors↗
PubMed1995

Changes in viral expression and cytokine profile induced by a polyantigenic immunomodulator in HIV-infected peripheral blood mononuclear cells.

This is the first time, to our knowledge, that evidence is presented showing that a polyantigenic immunomodulator (PAI), acting as a biological response modifier, can either induce or suppress HIV expression depending on the viral load of infected PBMC. PAI consists of a mixture of inactivated bacteria with influenza virus vaccine. PBMC from HIV-infected patients (asymptomatic, age 22-36, symptomatic, age 30-59 and pediatric, < 2 years old) were co-cultured with PHA-stimulated PBMC from uninfected individuals in medium containing IL-2 and PAI. Parallel co-cultures were carried out in a PAI-free medium. Cultures were fed with PHA-stimulated PBMC from uninfected donors on a weekly basis. HIV-p24 ag and cytokine profiles (IL-1 beta, IL-2, IL-4, IFN-gamma and TNF-alpha) were determined on supernatants on day 14. Peripheral blood samples from each patient were evaluated at the beginning of the experiment as to total CD3, total CD19, CD3/CD4, CD3/CD8, CD16/CD56, CD8/HLA-DR and CD8/CD38 markers through flow cytometry. PAI was able to induce viral expression (up to 11,881 pg/ml of p24 antigen) in cultures showing a low (less than 16 pg/ml) or no viral titer. In contrast, in those cultures with high viral titer (10(2)-10(5) pg/ml), a substantial reduction on the titer was observed upon exposure to PAI. PAI was able to induce the production of IFN-gamma and TNF-alpha while that of IL-4 and IL-1 beta was reduced. The predominant cell type detected in the blood samples of the studied subjects were CD8+, CD8+/CD38+ or CD8+/HLA-DR+.(ABSTRACT TRUNCATED AT 250 WORDS)

ADP-ribosyl Cyclase↗
PubMed1994

Anorexia nervosa and myocardial infarction.

A 39-year-old woman with long-standing anorexia nervosa was admitted to our hospital because of extreme weakness and cachexia. During a hyperalimentation therapy, she developed chest pain, revealing the electrocardiogram and cardiac enzymes a myocardial infarction of the inferior wall. We suggest that anorexia nervosa does not 'protect' against coronary atherosclerosis, and that some of the cases of sudden death could be related to myocardial ischemia.

Adult↗