PubMed Health⌕ Search

Biomedical subjects

J Tapia

Publications and source records attributed to J Tapia.

At least 19 recordsLinked to original sources
PubMed2002

Prenatal detection of ductal-dependent congenital heart disease: how can things be made easier?

OBJECTIVE: To improve the detection of ductal dependence in fetuses with severe anomalies of the outflow tracts by observing, with directional power Doppler, reverse flow through the aortic arch or ductus arteriosus in a transverse view of the upper mediastinum. METHODS: A slight cranial move of the ultrasound beam from the three-vessel view allows the transverse view of the aortic arch and ductus arteriosus to be visualized simultaneously. This view is orthogonal to the fetal body axis and parallel to the plane of the four-chamber view. In normal fetuses, directional power Doppler interrogation at this level identifies forward flow in both oblique vessels. RESULTS: We examined 43 fetuses with cardiac defects. In five of the cases, there was reversed flow in the aortic arch or ductus arteriosus in addition to severe anomalies of the outflow tracts, including four with hypoplastic left ventricle and one with pulmonary atresia. CONCLUSIONS: Prenatal detection of reversed flow in the aortic arch or ductus arteriosus is associated with complex congenital heart disease with major diminution of forward flow to the corresponding great vessels.

Aorta, Thoracic↗
PubMed2001

Renal structures in type 2 diabetic patients with elevated albumin excretion rate.

Renal biopsies were obtained from type 2 diabetic patients with elevated albumin excretion. The aim was to obtain quantitative structural data to correlate with clinical findings. Biopsies from 27 diabetic patients and 12 non-diabetic cases were analysed. Stereological methods were applied by light- and electron microscopy. Diabetic patients showed quantitatively markedly expressed diabetic glomerulopathy, but also an increase in glomerular volume, in prevalence of new-vessel formation at the vascular pole, prevalence of glomerular occlusion and in interstitial volume fraction. A significant correlation was not observed between the degree of interstitial and glomerular involvement. The glomerular hypertrophy is interpreted as a compensatory phenomenon, leading to preservation of filtration surface in the open glomeruli. Close correlation was seen between glomerulopathy and glomerular function, and also with the stage of retinopathy. New vessel formation at the vascular pole was most frequent in patients with proliferative retinopathy. Signs of non-diabetic glomerulopathy were not observed, but various atypical ultrastructural changes accompanying the advanced stages are illustrated. Our present findings correspond to data from type I diabetic patients. It is emphasised that all compartments of the kidney are affected by the diabetic state. It is suggested that the interstitial and glomerular lesions are influenced by different factors.

Adult↗
PubMed2001

Cloning and characterization of the cDNA coding for the catalytic alpha subunit of CK2 from tobacco.

We have previously reported the participation of the protein kinase CK2 in the mechanism by which salicylic acid activates transcription of genes, such as those coding for glutathion S-transferases, in tobacco. With the purpose of further studying the participation of CK2 in this signal transduction pathway, we isolated and sequenced the cDNA from the NtCK2A gene, coding for the catalytic alpha subunit of CK2 from tobacco. The NtCK2A cDNA was isolated by screening of a tobacco cDNA library with a heterologous probe from Arabidopsis thaliana, followed by 3' RACE to obtain the 3' region. Sequence analysis of the NtCK2A cDNA showed a high level of identity between this CK2alpha protein sequence and the corresponding sequences of other plant species such as Arabidopsis and maize (92-95% identity), or those of animal species such as human and Xenopus laevis (75% identity). The expression of the NtCK2A gene in different tissues from tobacco plants was analyzed by Northern blot. High levels of expression of this gene were observed in proliferating tissues such as shoot and root apical meristems. A recombinant CK2alpha protein was obtained after expression of the NtCK2A cDNA in Escherichia coli. The ability of this recombinant CK2alpha subunit to phosphorylate casein was inhibited by heparin and stimulated by the CK2beta subunit from Xenopus laevis.

Amino Acid Sequence↗
PubMed1999

Jejunostomy: techniques, indications, and complications.

Jejunostomy is a surgical procedure by which a tube is situated in the lumen of the proximal jejunum, primarily to administer nutrition. There are many techniques used for jejunostomy: longitudinal Witzel, transverse Witzel, open gastrojejunostomy, needle catheter technique, percutaneous endoscopy, and laparoscopy. The principal indication for a jejunostomy is as an additional procedure during major surgery of the upper digestive tract, where irrespective of the pathology or surgical procedures of the esophagus, stomach, duodenum, pancreas, liver, and biliary tracts, nutrition can be infused at the level of the jejunum. It is also used in laparotomy patients in whom a complicated postoperatory recovery is expected, those with a prolonged fasting period, those in a hypercatabolic state, or those who will subsequently need chemotherapy or radiotherapy. As a sole procedure it is advised for neurologic and congenital illnesses, in geriatric patients who pose difficult care demands, and for patients with tumors of the head and neck. The complications seen with jejunostomy can be mechanical, infectious, gastrointestinal, or metabolic. The rate of technical complications of the Witzel longitudinal technique is 2.1%, for the transverse Witzel up to 6.6%, for the Roux-en-Y 21%, for open gastrojejunostomy from 2%, and for the needle catheter technique from 1.5% with 0.14% mortality. The percutaneous endoscopic procedures have as much as a 12% complication rate; no figures exist for laparoscopy. The complications are moderate and severe: tube dislocation, obstruction or migration of the tube, cutaneous or intraabdominal abscesses, enterocutaneous fistulas, pneumatosis, occlusion, and intestinal ischemia. The infectious complications are aspiration pneumonia and contamination of the diet. The gastrointestinal complications are diarrhea 2.3% to 6.8%, abdominal distension, colic, constipation, nausea, and vomiting. The metabolic complications are hyperglycemia 29%, hypokalemia 50%, water and electrolyte imbalance, hypophosphatemia, and hypomagnesemia. These complications are secondary to inadequate selection of nutrition relative to the characteristics of the patient, to inadequate management of the mixture, and to deficient clinical care. The ideal jejunostomy technique depends on the material resources but more importantly on the experience of the surgeon. The benefits of jejunostomy justify the risks.

Aged↗
PubMed1998

[Cardiac rhythm and systemic embolism in long-term follow up of patients with non-valvular paroxysmal atrial fibrillation].

BACKGROUND: Paroxysmal atrial fibrillation may predispose to systemic embolism. There is little information about the evolution of cardiac rhythm and the occurrence of new embolic events in these patients. AIM: To report the results of a long term follow up of patients with paroxysmal atrial fibrillation. PATIENTS AND METHODS: Patients consulting for non valvular paroxysmal atrial fibrillation were followed for a mean period of 5 years. An EKG, 2D echocardiogram and brain CT scans were performed on admission and at the end of the follow up period to all patients. RESULTS: Sixty eight patients aged 65 +/- 1.5 years were studied. Thirty two had an idiopathic atrial fibrillation, 28 had a history of mild hypertension and 8 had a history of coronary artery disease. Evidence of systemic emboli was found in 17 patients at entry (to the brain in 14 patients). During the follow up 87% of patients required antiarrhythmics, 27% were anticoagulated and 28% received aspirin. Five patients had new embolic episodes. Of these, four had a history of prior embolism. Forty one percent of patients continued in sinus rhythm and remained asymptomatic, 32% had at least one recurrence of paroxysmal atrial fibrillation and nine patients evolved to chronic atrial fibrillation. Five patients required a permanent pacemaker due to symptomatic bradycardia. CONCLUSIONS: Most patients with non valvular paroxysmal atrial fibrillation remain in sinus rhythm but one third have recurrences of the arrhythmia. A main risk factor for embolism is the history of previous embolic episodes.

Aged↗
PubMed1997

Value of logistic discriminant analysis for interpreting initial visual field defects.

PURPOSE: The authors evaluate logistic discriminant analysis as a method for interpreting visual field results in initial stages of several ophthalmic diseases. METHODS: The authors retrospectively studied the visual field defects of 96 patients with early glaucomatous damage and prospectively studied 84 subjects with normal eyes (n = 28), cataracts (n = 27), diabetic retinopathy (n = 14), or hypertensive retinopathy (n = 15). The visual fields were examined at least twice with program G1 of Octopus 500 (Interzeag AG, Schlieren, Switzerland). Only one eye per patient was randomly selected and included in the study. The authors created a database with all visual field information provided by Octopus and applied logistic discriminant analysis (SAS Logistic Procedures, SAS Institute, Cary, NC) to obtain classification rules capable of qualifying visual field defects as glaucomatous or nonglaucomatous. The rules were tested with an independent sample. RESULTS: There were significant differences between the groups in the distribution of visual field defects tested by program G1. Logistic discriminant analysis correctly identified the glaucomatous or nonglaucomatous origin of the defects with a sensitivity of 65% to 85% and a specificity of 60% to 92%. CONCLUSIONS: Logistic discriminant analysis is a useful tool to aid in the interpretation of early glaucomatous and nonglaucomatous visual field defects.

Data Interpretation, Statistical↗
PubMed1996

Clinical predictors of tuberculosis as a guide for a respiratory isolation policy.

An expanded respiratory isolation policy was implemented in a public hospital that cares for about 200 patients with active tuberculous each year. This led to proper isolation of > or = 95% of patients with tuberculosis on admission but involved an 8-fold overuse of isolation rooms. We developed a model policy to decrease overisolation of nontuberculous patients. Clinical findings in 295 patients admitted to respiratory isolation during a 3-mo period were evaluated for their usefulness in determining which patients had tuberculosis. Multivariate analysis identified five predictive variables: chest radiograph with upper lobe infiltrate (odds ratio, 5.00; CI, 2.38 to 10.51; p = 0.001) or cavity (odds ratio, 3.93; CI, 1.06 to 14.62; p = 0.041), history of having known someone with tuberculosis (odds ratio, 2.42; CI, 1.10 to 5.32, p = 0.027), self-reported positive tuberculin skin test (odds ratio, 5.67; CI, 1.57 to 22.01; p = 0.009), self-reported isoniazid preventive therapy (odds ratio, 0.18; CI, 0.04 to 0.82; p = 0.027). Using these variables to determine which patients required isolation would have decreased the number of isolated nontuberculous patients from 253 to 95, but it would have missed eight of 42 patients with tuberculosis. Further work is needed to identify clinical predictors that would decrease overuse of isolation beds while maintaining satisfactory sensitivity for patients with tuberculosis.

Adult↗
PubMed1996

Cerebellar hemorrhagic infarction.

We investigated 17 patients with 26 cerebellar hemorrhagic infarcts for their vascular anatomy, stroke mechanisms, and clinical course. Sixteen infarcts involved the superior cerebellar artery, nine the posterior inferior cerebellar artery, and one the anterior inferior cerebellar artery territories. The infarcts involved the full territory of the supplying arteries in 19 of 26 infarcts (73%). Sixteen of 17 patients were stable or improving when the hemorrhagic infarction was detected. All but one patient had an imaging study at the time of presentation that was negative for blood; hemorrhagic infarction was detected on routine serial scans performed during the first 15 days. Nine of the 17 patients were on anticoagulants when the cerebellar hemorrhagic infarct was detected; anticoagulation was maintained in eight of them with no clinical worsening. The stroke mechanism in all patients was considered embolic from cardiac and intra-arterial sources. The causes, imaging findings, and consequences of hemorrhagic infarcts in the posterior circulation are similar to those in the anterior circulation.

Anticoagulants↗
PubMed1996

[Cerebral hemorrhage associated with the use of phenylpropanolamine. Clinical cases].

We report three women aged 33, 63 and 43 years old receiving an anorexigenic medication that contained phenylpropanolamine who, 30 min to 3 h after the ingestion of this medication, presented a frontal hematoma, a left putaminal hematoma and a subaracnoidal hemorrhage, respectively. Cerebral angiography, performed in all of them, did not show any vascular abnormality. This complication of phenylpropanolamine use, has been reported previously abroad and the mechanism of production, could be related to an elevation of blood pressure and the production of a vasculitis by the drug. The risk of this complication must be taken into account when prescribing phenylpropanolamine.

Adult↗
PubMed1995

Synthetic Lignin Mineralization by Ceriporiopsis subvermispora Is Inhibited by an Increase in the pH of the Cultures Resulting from Fungal Growth.

(sup14)C-synthetic lignin mineralization by the basidiomycete Ceriporiopsis subvermispora occurs at the highest rate (about 30% after 29 days) in liquid cultures containing 1% glucose and a growth-limiting amount (1 mM) of ammonium tartrate. The titers of manganese peroxidase (MnP) and laccase are lower in these cultures than in cultures containing 1% glucose and 10 mM ammonium tartrate, where the extent of lignin mineralization in the same period is only about 15%. The inverse correlation between enzyme activity and lignin mineralization is also observed when ammonium tartrate is replaced by ammonium chloride or Casamino Acids as the source of nitrogen. This phenomenon can be explained by a gradual increase in the pH of the medium that takes place only in the cultures with high nitrogen concentrations. Supporting this finding, when cultures with 1 mM ammonium tartrate were grown at different pHs, (sup14)CO(inf2) evolved more rapidly from those with pH values near the optimum for MnP activity. On the other hand, (sup14)CO(inf2) evolution from cultures containing 1% glucose supplemented with 1 mM ammonium tartrate plus 9 mM sodium tartrate was as low as that from cultures with a high ammonium tartrate concentration. Since the changes in the pH of these cultures were not as pronounced as those in cultures containing high nitrogen concentrations, tartrate itself may also be contributing to limit the extent of lignin mineralization. Considering that pH instability seems to constitute a common feature of fungal cultures, precautions must be taken to avoid underestimation of their ligninolytic efficiencies.

Journal Article↗
PubMed1995

Pyeloplasty improves renal function and somatic growth in children with ureteropelvic junction obstruction.

We studied the systemic effects of pyeloplasty in 38 children with unilateral ureteropelvic junction obstruction. Mean patient age at surgery was 2.5 years and 22 patients were age 1 year or younger. Mean followup was 18 months. We recorded serum creatinine levels, glomerular filtration rate calculated by the Schwartz formula body growth, the degree of dilatation and the excretory curve of the diuresis renogram. Pyeloplasty was effective in decreasing the degree of ultrasonographic dilatation and the excretory curve of the renogram in 36 cases. Two patients required reoperation. Individual renal function improved significantly in children younger than 1 year with preoperative differential function less than 45% but not in older children. Serum creatinine level decreased significantly after pyeloplasty in all children. Likewise, glomerular filtration rate improved significantly in all children. Preoperatively, 72% of children younger than 1 year were below the 50th percentile in height. The distribution of heights became normal after surgery. Overall, percentile rank for height increased in a significant number of patients of all ages. We conclude that unilateral hydronephrosis systemically affects body growth and overall renal function, the salutary effect of pyeloplasty goes beyond the affected kidney and pyeloplasty may be of greater benefit when performed in infancy. These parameters must be considered in protocols designed to compare outcomes in children with hydronephrosis treated surgically with those who are simply observed.

Body Height↗
PubMed1994

Cerebellar infarcts in the New England Medical Center Posterior Circulation Stroke Registry.

We report the clinical findings and stroke mechanisms of 63 patients with cerebellar infarcts. We divided the intracranial vertebrobasilar circulation into the proximal territory (P), fed by the intracranial vertebral arteries and their branches; the middle territory (M), fed by the proximal and middle basilar artery and its branches; and the distal territory (D), fed by the rostral basilar artery and its branches. Cerebellar infarcts were classified by vascular territories P, M, D, P&D, and middle-plus (P&M, M&D, and P&M&D). Patients with P infarcts (11 patients) frequently had vertigo, gait instability, limb ataxia, and headache, whereas patients with D infarcts (15 patients) most often had limb ataxia, gait instability, and dysarthria. Patients with P&D infarcts (17 patients) had signs and symptoms of both groups combined. Infarcts in which the middle territory was involved, either alone (three patients) or combined with other territories (17 patients) were dominated by brainstem signs and symptoms. The predominant stroke mechanisms in the P, D, and P&D groups were embolic due to intra-arterial or cardiac embolism. When the M territory was involved, either alone or with P, D, or P&D territories, stroke mechanisms were more varied, and there was often large-artery occlusion with hemodynamic ischemia.

Adult↗
PubMed1994

[Multidisciplinary study of cerebrovascular disorders. II. Cardiovascular profile of occlusive vascular disorders].

Ischemic stroke constitute a mayor cause of morbidity and mortality in the adult population, particularly in the elderly. Heart disease may predispose to ischemic stroke, especially in the presence of transient or permanent precipitating factors such as atrial fibrillation. To elucidate the role of heart disease in predisposing to ischemic stroke we studied the clinical and non invasive cardiac profile (EKG, 2D-Echo, Holter) of 186 consecutive patients, 91 of them embolic (GI) and 96 non embolic (lacunar, atherothrombotic, others) (GII), as determined by brain CT scan and thorough clinical evaluation. Age and male/female ratio were significantly different (71 + 13 vs 65 + 12 years, 40/60 vs 65/35, p < 0.003). Hypertension was equally common in both groups (38 and 40%). Patients in GI had higher prevalence of valvular heart disease (23 vs 1%), atrial fibrillation (67 vs 10%), 2D Echo left atrial enlargement (45 vs 16%) and supraventricular ectopy in Holter (59 vs 32%) p < 0,001. By contrast absence of heart disease (45 vs 19%), ST-T changes in EKG (28 vs 14%), left ventricular hypertrophy in 2D Echo (28 vs 9%) and ventricular ectopy in Holter (54 vs 23%) were more prevalent in GII patients, p < 0.001. Multiple stepwise logistic regression analysis showed age > 70 years (relative risk (RR) 1.67), valvular heart disease (RR 2.25), chronic AF (RR 2.44) and paroxysmal AF (RR 1.89) were significant independent predictors of embolic stroke, whereas the presence of left ventricular hypertrophy in 2D-Echo (RR 0.76) and frequent ventricular premature beats in Holter (RR 0.47) were predictors of occlusive non embolic stroke. Thus, the clinical and non invasive cardiac profile of embolic and non embolic ischemic stroke is significantly different, which is relevant to preventive strategies.

Age Factors↗
PubMed1993

Divergence between biochemical and cytogenetic differences in three species of the Callicebus moloch group.

Specimens from three species of the Callicebus moloch group--C. moloch (N = 80), C. brunneus (N = 166), and C. cupreus (N = 23)--were studied. Twenty genetic loci were investigated through electrophoresis, genetic distances were estimated, and the results compared with the available cytogenetic data. Low values of genetic distance were encountered, contrasting with relatively large chromosome differences. We propose that recent karyotypic rearrangements, rather than other Pleistocene events, were the major evolutionary mechanisms determining speciation in these three taxa.

Animals↗
PubMed1993

Histologic assessment of the age of recent brain infarcts in man.

In order to design a dating system based on the microscopic picture of brain infarcts of recent onset, we performed the histological examination of 31 infarcts covering the first 4 weeks of evolution in 30 autopsy cases. The date of the cerebral vascular accident was clinically established in every case. There were 13 men and 17 women with a mean age of 65 years. Hemorrhagic infarcts were found in 15 cases and anemic infarcts in 16 cases. Based on the histological features four periods were identified: the first period, from day 1 through day 4, was characterized by the predominance of eosinophilic neurons and necrotic oligodendrocytes; the second period, from day 5 through day 7, differed from the first by the appearance of macrophages and of newly formed blood vessels; the third period, from day 8 through day 14, showed neuronal ghosts, macrophages, astrocytic proliferation, gemistocytes, and absence of neutrophils; and in the fourth period, from day 15 through day 27, there were no eosinophilic neurons, and neither necrotic oligodendrocytes nor myelin in the central portion of the infarct were identified. By assessing the histological features and accurately correlating the findings with the corresponding clinical data, we have been able to describe four distinct microscopic patterns of the first month of evolution of brain infarcts. The present findings may be considered useful morphological clues to better characterize the early evolutional phase of brain infarcts in humans.

Aged↗
PubMed1992

Risk factors for systemic embolism in patients with paroxysmal atrial fibrillation.

The purpose of this study was to define the risk factors for systemic embolism in patients with recently diagnosed paroxysmal atrial fibrillation. We therefore studied 63 consecutive patients with symptomatic nonvalvular paroxysmal atrial fibrillation and performed a clinical and noninvasive cardiac, peripheral vascular, and neurologic evaluation that included two-dimensional echocardiography, 24-hour Holter monitoring, and computed tomographic brain scan. Patients with predisposing clinical conditions for systemic embolism (valvular heart or coronary artery disease) or paroxysmal atrial fibrillation (sick sinus disease, preexcitation, or thyroid dysfunction) were excluded. At entry 34 patients had idiopathic paroxysmal atrial fibrillation and 29 had hypertension. Fourteen patients had a recent systemic embolic complication: nine had a recent occlusive nonlacunar cerebrovascular accident, two had transient ischemic attacks, and three had peripheral systemic emboli that required surgery. In addition, five patients had evidence of old cerebrovascular accident on the computed tomographic scan (group 1). Forty-four patients had no systemic embolism (group 2). Results of univariate analysis showed that patients in group 1 were older (72 +/- 9 vs 63 +/- 13 years, p less than 0.05), had a higher incidence of hypertension (70% vs 35%, p less than 0.01), and had an increased left atrial diameter (4.1 +/- 0.7 vs 3.6 +/- 0.5 cm, p less than 0.05). Multiple stepwise logistic regression analysis showed that a history of hypertension and left atrial enlargement on two-dimensional echocardiography were significant independent risk factors for systemic embolism in patients with symptomatic nonvalvular paroxysmal atrial fibrillation.

Aged↗
PubMed1992

[Multidisciplinary study of cerebrovascular accidents: I. Definition, design, and general results].

Cerebrovascular accidents (CVA) constitute a major cause of adult cardiac cardiovascular mortality in Chile. From July 87 to August 89 we prospectively studied 300 patients with CVA utilizing a multidisciplinary approach. Besides clinical evaluation this included brain CT scan (48 hrs), glucidic and lipid profile. Occlusive CVA were additionally studied with 2D-Echocardiogram, 24 hr Holter, Cerebral Angiography and/or carotid Duplex Echotomograph, and a second brain CT scan was performed within the first week. We found a 62.3% incidence of cerebral infarcts, 28.3% of cerebral hemorrhages and 9.3% of transient ischemic attacks. Cerebral infarcts were found to be cardiac related in 33.5% of cases, whereas 13.2% were lacunar, 4.4% were atherothrombotic and 14% had no precise etiology. Hypertension was associated to cerebral hemorrhages in 76% of cases, 26% of which were intracranial. At 2 months of follow-up 16.3% of patients were severely handicapped and mortality was 19.3%. We have confirmed that cerebral infarcts constitute the most common cause of CVA and most of them are cardiac related. Hypertension appears to be the most important cause of cerebral hemorrhage. A multidisciplinary approach to cerebrovascular accidents allowed a more precise diagnosis and contributed to implement appropriate therapeutic and preventive strategies. Proper identification of high risk patients could contribute to decrease the high incidence and mortality of CVA in our community.

Aged↗