Biomedical subjects

A Nobre

Publications and source records attributed to A Nobre.

10 recordsLinked to original sources

PubMed2002

A physiological and enzymatic study of Debaryomyces hansenii growth on xylose- and oxygen-limited chemostats.

The effect of changing growth rate and oxygen transfer rate (OTR) on Debaryomyces hansenii physiology was studied using xylose-limited and oxygen-limited chemostat cultures, respectively, and complemented with enzymatic assays. Under xylose-limited chemostat (oxygen-excess), neither ethanol nor xylitol was produced over the entire range of dilution rate ( D). The maximal volumetric biomass productivity was 2.5 g x l(-1) x h(-1) at D =0.25 h(-1) and cell yield was constant at all values of D. The respiratory rates and xylose consumption rate increased linearly with growth rate but, above 0.17 h(-1), oxygen consumption rate had a steeper increase compared to carbon dioxide production rate. Enzymatic analysis of xylose metabolism suggests that internal fluxes are redirected as a function of growth rate. For values of D up to 0.17 h(-1), the xylose reductase (XR) titre is lower than the xylitol dehydrogenase (XDH) titre, whereas above 0.17 h(-1) XR activity is about twice that of XDH and the NADPH-producing enzymes sharply increase their titres indicating an internal metabolic flux shift to meet higher NADPH metabolic requirements. Moreover, the enzymes around the pyruvate node also exhibited different patterns if D was above or below 0.17 h(-1). Under oxygen-limited chemostat (xylose-excess) the metabolism changed drastically and, due to oxidative phosphorylation limitation, cell yield decreased to 0.16 g g(-1) for an OTR of 1.4 mmol l(-1) h(-1) and xylitol became the major extracellular product along with minor amounts of glycerol. The enzymatic analysis revealed that isocitrate dehydrogenase is not regulated by oxygen, whereas XR, XDH and the NADPH-producing enzymes changed their levels according to oxygen availability.

Culture Media↗

PubMed1999

Transport and utilization of hexoses and pentoses in the halotolerant yeast Debaryomyces hansenii.

Debaryomyces hansenii is a yeast species that is known for its halotolerance. This organism has seldom been mentioned as a pentose consumer. In the present work, a strain of this species was investigated with respect to the utilization of pentoses and hexoses in mixtures and as single carbon sources. Growth parameters were calculated for batch aerobic cultures containing pentoses, hexoses, and mixtures of both types of sugars. Growth on pentoses was slower than growth on hexoses, but the values obtained for biomass yields were very similar with the two types of sugars. Furthermore, when mixtures of two sugars were used, a preference for one carbon source did not inhibit consumption of the other. Glucose and xylose were transported by cells grown on glucose via a specific low-affinity facilitated diffusion system. Cells derepressed by growth on xylose had two distinct high-affinity transport systems for glucose and xylose. The sensitivity of labeled glucose and xylose transport to dissipation of the transmembrane proton gradient by the protonophore carbonyl cyanide m-chlorophenylhydrazone allowed us to consider these transport systems as proton symports, although the cells displayed sugar-associated proton uptake exclusively in the presence of NaCl or KCl. When the V(max) values of transport systems for glucose and xylose were compared with glucose- and xylose-specific consumption rates during growth on either sugar, it appeared that transport did not limit the growth rate.

Biological Transport, Active↗

PubMed1992

Absent left-sided atrioventricular connexion, with right atrium connected to left ventricle: prospective diagnosis in infancy, and outcome.

Prospective echocardiographic diagnosis of absence of the left atrioventricular connexion, with the right atrium connected to a morphologic left ventricle through a bileaflet morphologically mitral valve, was made in six infants. The rudimentary right ventricle was left-sided in all patients, and separated from the left atrium by sulcus tissue. The ventriculoarterial connexions were discordant. Associated defects included subpulmonary stenosis (2 patients), pulmonary atresia (1 patient), and a patent duct (4 patients). All patients developed early left atrial hypertension due to a restrictive interatrial septum, and required transcatheter septostomy (5 patients), or surgical septectomy (3 patients). One patient who had a severely restrictive ventricular septal defect died following cardiac catheterization. In three others the ventricular septal defect has become progressively restrictive on serial catheterization. Successful intermediate term palliation has been performed in two patients using a bidirectional Glenn anastomosis, together with enlargement of the ventricular septal defect and a Damus-Kay-Stansel procedure in one. It is possible to distinguish this malformation from "mitral atresia" using cross-sectional echocardiography. The long-term outlook is influenced by early relief of left atrial hypertension. Balloon atrial septostomy alone is usually inadequate, and either blade septostomy or surgical septectomy are required. Serial cardiac catheterization is mandatory for planning definitive palliation.

Cardiac Catheterization↗

PubMed1991

Traumatic ventricular septal defect: serial follow-up with Doppler ultrasound.

A three-year-old girl presented with a gunshot wound of the chest. Cross-sectional and Doppler echocardiography enabled precise location of the bullet, and assessment of the haemodynamic effects of the traumatic ventricular septal defect. Serial ultrasound examination in the acute stage confirmed that the bullet was well embedded in the left ventricular myocardium, and the ventricular septal defect was restrictive, enabling conservative management.

Cardiac Catheterization↗

PubMedDate not supplied

Human extrastriate visual cortex and the perception of faces, words, numbers, and colors.

Electrophysiological correlates of the processing of visual information were studied in epileptic patients with electrodes chronically implanted on the surface of striate and extrastriate cortex. In separate experiments patients viewed faces, letter strings (words and non-words), numbers, and control stimuli. A negative potential, N200, was evoked by faces, letter strings, and numbers, but not by the control stimuli. N200 was recorded bilaterally from discrete regions of the fusiform and inferior temporal gyri. These category-specific face, letter-string, and number "modules" vary in location. In most cases there was no overlap in the location of face and letter-string modules, suggesting a mosaic of functionally discrete regions. In some cases letter-string and number N200s were recorded from the same location, suggesting that these modules may be less spatially and functionally discrete. Face N200-like potentials can be recorded from temporal scalp, allowing the possibility of studying early face processing in normal subjects. Longer-latency face-specific potentials were recorded from the inferior surface of the anterior temporal lobe. Potentials evoked by colored checkerboards were recorded from a region of the fusiform gyrus posterior to the fusiform region from which category-specific N200s were recorded. These results suggest that there are several processing streams in inferior extrastriate cortex. In addition to object recognition systems previously proposed for faces and words, our preliminary results suggest a separate system dealing with numbers. Postulated systems dealing with larger manipulable objects and animals have not been detected.

Color Perception↗

PubMedDate not supplied

[Reoperation in mitral valve reconstructive surgery].

UNLABELLED: In the past few years reconstructive surgery of the mitral valve has experienced a growing popularity. It is now clearly established that restoration of a normal function valve is preferable to valve replacement. The authors report the results of the mitral valve reconstructive surgery in a population of 701 patients with high incidence of restrictive lesions of rheumatic fever. This represents an experience of 14 years. 5.1% of patients who underwent mitral valvuloplasty required late reoperation for recurrent mitral valve dysfunction. Repeat mitral valve repair resulted in successful treatment for 40% of these patients. CONCLUSION: The mitral valve repair failure are: 1--Procedure related: (58.1%); a--surgical technical related--35.8%; b--no ring implantation (in restrictive lesions)--15%; c-rupture of previously chordae shortened--7.4%. 2--Valve related: (41.9%); a--progressive primary valve disease--(25.4%); b--wrong surgical indication--(15%); c--endocarditis--(1.5%).

Adolescent↗

PubMedDate not supplied

[Pulmonary arterio-venous fistula: a clinical report].

A 44 years old female was admitted with previous history of several cerebral vascular accident (CVA). A transthoracic echocardiogram showed a patent foramen ovale (PFO) that was closed, under extracorporeal circulation. The patient remained free of symptoms for ten years. In the year 2003 she was admitted to our hospital with paresthesias of the left arm. The clinical evaluation led to the diagnosis of arteriovenous fistula (AVF) of the lung. In November 2003, the patient underwent right inferior lobectomy. This is a rare association of PFO with AVF fistula of the lung with a delayed diagnosis. The differential diagnosis, the surgical treatment and the most frequent complications of this pathology are reported and discussed.

Adult↗

PubMedDate not supplied

["Off pump" coronary surgery and simultaneous carotid endarterectomy].

The occurrence of significant carotid artery disease in patients requiring coronary artery bypass grafting (CABG), results in a dilemma regarding the best surgical management. Our philosophy has been to perform simultaneous carotid endarterectomy and CABG off-pump. We reviewed the efficacy of this therapy in six patients treated in our hospital between January 2001 and December 2002. The result was satisfactory and there was no hospital mortality.

Aged↗

PubMedDate not supplied

[Surgery of mediastinal tumors: 11-years experience].

Between 1993 and 2004, 70 operations on patients with the diagnosis of mediastinal tumors were performed in the Cardiothoracic Surgery Department of Santa Maria Hospital. In this study we did not include diagnostic surgery of mediastinal tumors. In 70 patients treated, 63 p (90%) had the tumor located in the anterior mediastinum, 21 p with thymoma, 6 p with lymphoma, 4 p with carcinoid tumors, 1 p with sarcoma and 1 p with adenocarcinoma. 3 patients had tumors located in the medium and 4 patients in the posterior mediastinum. We analysed the results of the mediastinal tumors surgery during the 11-years period. Also, we evaluated the clinical effects of the thymectomy in myasthenia gravis.

Carcinoid Tumor↗

PubMedDate not supplied

[Surgical diagnosis of mediastinal pathology: eleven-years experience].

Between January 1993 and December 2004, 68 patients with mediastinal pathology were submitted to diagnosis surgery. All the pathological process were located in the anterior mediastinum, and most of them were malignant (64.1%). The most common pathology was limphoma (26.5%), sarcoidosis (23.5%) and thymomas (23.5%). Seven cases consisted in ganglionar tuberculosis (10.3%), six cases were ganglionar metastases of lung adenocarcinoma (8.8%), and three cases were thymic carcinoma (4.4%). One patient had no definite diagnosis (1.5%). In this experience high diagnosis accuracy (98.5%), and low morbidity were demonstrated. Although the present video assisted thoracic surgery progress and development, mediastinoscopy still remains as a reliable, safe and efficient surgical approach for the diagnosis of mediastinal pathology.

Adolescent↗