Two-stage fermentation process for alginate production by Azotobacter vinelandii mutant altered in poly-beta-hydroxybutyrate (PHB) synthesis.

AIMS: A two-stage fermentation strategy, based on batch cultures conducted first under non-oxygen-limited conditions, and later under oxygen-limited conditions, was used to improve alginate production by Azotobacter vinelandii (AT6), a strain impaired in poly-beta-hydroxybutyrate (PHB) production. METHODS AND RESULTS: The use of sucrose as carbon source, as well as a high oxygen concentration (10%), allowed to obtain a maximum biomass concentration of 7.5 g l(-1) in the first stage of cultivation. In the second stage, the cultures were limited by oxygen (oxygen close to 0%) and fed with a sucrose solution at high concentration. Under those conditions, the growth rate decreased considerably and the cells used the carbon source mainly for alginate biosynthesis, obtaining a maximum concentration of 9.5 g l(-1), after 50 h of cultivation. CONCLUSION: Alginate concentration obtained from the AT6 strain was two times higher than that obtained using the wild-type strain (ATCC 9046) and was the highest reported in the literature. However, the mean molecular mass of the alginate produced in the second stage of the process by the mutant AT6 was lower (400 kDa) than the polymer molecular mass obtained from the cultures developed with the parental strain (950 kDa). SIGNIFICANCE AND IMPACT OF THE STUDY: The use of a mutant of A. vinelandii impaired in the PHB production in combination with a two-stage fermentation process could be a feasible strategy for the production of alginate at industrial level.

Preservation of canine myocardial high-energy phosphates during low-flow ischemia with modification of hemoglobin-oxygen affinity.

Conventional approaches for the treatment of myocardial ischemia increase coronary blood flow or reduce myocardial demand. To determine whether a rightward shift in the hemoglobin-oxygen saturation curve would reduce the metabolic and contractile effects of a myocardial oxygen-supply imbalance, we studied the impact of a potent synthetic allosteric modifier of hemoglobin-oxygen affinity, a 2-[4-[[(3,5-disubstituted anilino)carbonyl]methyl] phenoxy] -2-methylproprionic acid derivative (RSR13), during low-flow ischemia. Changes in myocardial high-energy phosphate levels and pH were studied by 31P nuclear magnetic resonance (NMR) spectroscopy in 12 open-chest dogs randomized to receive RSR13 or vehicle control during a reversible reduction of left anterior descending (LAD) coronary artery blood flow. Changes in cardiac metabolites and regional ventricular function studied by pressure segment-length relations were also investigated in additional animals before and after RSR13 administration during low-flow LAD ischemia. The intravenous administration of RSR13 before ischemia resulted in a substantial increase in the mean hemoglobin p50 and attenuated the decline in cardiac creatine phosphate/adenosine triphosphate (PCr/ATP), percent PCr, and pH during ischemia without a change in regional myocardial blood flow, heart rate, or systolic blood pressure. RSR13 given after the onset of low-flow ischemia also improved cardiac PCr/ATP ratios and regional function as measured by fractional shortening and regional work. Thus, synthetic allosteric reduction in hemoglobin-oxygen affinity may be a new and important therapeutic strategy to ameliorate the metabolic and functional consequences of cardiac ischemia.

Simplified nonlinearity correction of oxygen-15-water regional cerebral blood flow images without blood sampling.

UNLABELLED: A noninvasive method, the double-integration method, was developed to estimate regional cerebral blood flow (rCBF) by using 15O-water and PET. It relies on the acquisition of images with a correction of nonlinearity of brain tissue counts and can produce rCBF images on a pixel-by-pixel basis. METHODS: Oxygen-15-water PET studies were performed on five normal human volunteers, and continuous sampling from the radial artery was conducted to generate functional CBF images according to the invasive catheterization method. The method centers on a computer-based program elaborated to calculate an arterial input function with an assumption of the whole brain blood rate of 50 ml/dl/min and consequently does not require arterial catheterization or arterial input function sampled from other studies. RESULTS: The results indicate a good correlation between this method and the invasive method (r > 0.966, p < 0.001). CONCLUSION: This noninvasive method was demonstrated to provide an accurate estimation of rCBF and may simplify the activation studies.

Easy detection of tumor in oncologic whole-body PET by projection reconstruction images with maximum intensity projection algorithm.

Whole-body PET scanning for an oncology study produces a large number of transaxial images by data acquisition over multiple bed positions. The sagittal and coronal reformatted images are often used for better understanding of radioisotope distribution. We reduced the number of PET images by calculating projection images and evaluated the merit of additional data processing for the visualization and detection of tumors. After reconstructing whole-body 18F-FDG PET images (6-8 bed positions) of eight cancer patients, antero-posterior and lateral projection images were calculated by the maximum intensity projection (MIP) algorithm, the standard deviation projection (SD) algorithm and the summed voxel projection (SUM) algorithm. The projection images were compared with 2D whole-body images for visualizing foci. The focal uptakes of various positions in original whole-body PET data (294-392 transaxial images) were visualized on only two MIP reformatted images when superimposition of hot spots did not occur. Even if one hot spot was superimposed over the other hot spot, we could recognize the existence of at least one focus and determine the true positions of the hot spots from corresponding transaxial images. The SD image was found inferior for showing a contrast of small foci to the corresponding MIP images in the neck, mediastinum and abdomen. The SUM image failed to visualize many metastatic lesions. MIP is a promising technique for the easy preliminary assessment of tumor distribution in oncologic whole-body PET study.

Results obtained with piracetam in foetal distress during labour.

A double-blind study was performed on ninety-six parturients of the Lima Maternity Hospital, Peru, with some evidence of foetal distress who were given indistinguishably piracetam or a placebo at random in order to investigate the effects of the drug on the foetus. The conditions of the new-born babies who had received piracetam were superior to those of the babies treated with the placebo, as evaluated with the Apgar at 1, 5 and 10 minutes after birth and on the basis of the neurological and clinical examination as from 24 hours until they were released. In addition, the reduction of the duration of the labour in the patients treated with piracetam as compared with the control group was obvious.

[Delirium rating scale-revised-98 (DRS-R-98): Colombian adaptation of the Spanish version]. / Escala revisada-98 para valoración del delirium (DRS-R-98): adaptación colombiana de la versión española.

INTRODUCTION: Delirium is associated with high morbidity and mortality. There are no available instruments validated for evaluation and follow-up of this syndrome in Columbia. METHODS: An expert's panel adapted the Spanish DRSR- 98. In 110, randomly selected, medical-surgical hospitalized patients, 17 (15.5 %) of them with delirium diagnosed with DSM-IV-TR criteria, the inter-rater reliability, validity and sensitivity to clinical change of the new adaptation of the scale were measured. RESULTS: Internal consistency (Cronbach's alpha: 0.956), inter- rater reliability (ICC: 0.95) and validity (94.8 % under the ROC curve area) were very good. For the Cut-off score of 14 for the total scale score, sensitivity was 82.4% and specificity 97.8 %. The scale was sensitive to clinical change, with a mean difference of 12.9 (t: 4.071; p=0.007). CONCLUSIONS: The Colombian adaptation of the Spanish DRS-R-98 is sensitive, specific and reliable for assessment of delirium in hospitalized adults in medical surgical settings.

Epidemiologic studies of Cyclospora cayetanensis in Guatemala.

In 1996 and 1997, cyclosporiasis outbreaks in North America were linked to eating Guatemalan raspberries. We conducted a study in health-care facilities and among raspberry farm workers, as well as a case-control study, to assess risk factors for the disease in Guatemala. From April 6, 1997, to March 19, 1998, 126 (2.3%) of 5, 552 surveillance specimens tested positive for Cyclospora; prevalence peaked in June (6.7%). Infection was most common among children 1.5 to 9 years old and among persons with gastroenteritis. Among 182 raspberry farm workers and family members monitored from April 6 to May 29, six had Cyclospora infection. In the case-control analysis, 62 (91%) of 68 persons with Cyclospora infection reported drinking untreated water in the 2 weeks before illness, compared with 88 (73%) of 120 controls (odds ratio [OR] 3.8, 95% confidence interval [CI] 1.4, 10.8 by univariate analysis). Other risk factors included water source, type of sewage drainage, ownership of chickens or other fowl, and contact with soil (among children younger than 2 years).

Arrangement of beta tubulin in bull spermatozoa during nuclei decondensation.

Eukaryotic cells have internal scaffolding of microtubules cytoskeleton that gives them their characteristic shapes. We analyzed by immuno-fluorescence the shift and distribution of tubuline during in vitro bull sperm nuclei swelling by the action of heparin-reduced glutathione physiological decondensing agents. Sperm tubulin display a pattern that shows tubulin fluorescence all over the head, leaving the acrosome tip devoid of tubulin. In the second stage we can observe that the acrosomal zone is practically devoid of fluorescence and a net of fluorescent microtubules that seems to be anchored in the basal plate in the postacrosomal region. It is also possible to observe green spots of tubulin fluorescence in the nucleus periphery, that might represent clusters of chromatin hub-like bodies and/or the microtubule organizing center (MTOC). In the third stage, practically all tubulin moves backwards to the basal plate in the neck region of the sperm nuclei remaining in only the green fluorescence spots in the periphery of the swollen sperm nuclei. The results allow us to assume that tubulin mechanism rearrangement is considered to be necessary for the normal fertilization process.

Resultados obtenidos con piracetam en el sufrimiento fetal durante el parto / Results with peracetam in fetal distress during labor

Se hizo un estudio doble ciego en 96 parturientas de Hospital Maternidad de Lima.Peru, con evidencias de sufrimiento fetal, a quienes se les administro indistintamente piracetam o placebo por randomizacion, para estudiar los efectos de la droga sobre el feto. Las condiciones de los recien nacidos que recibieron piracetam fueron superiores a la de aquellos a los que se administro placebo, evaluados por el Apgar a 1,5 y 10 minutos del nascimiento, y por el examen neurologico y clinico, desde las 24 horas hasta que fueron dados de alta.Fue notoria, ademas, la abreviacion de la labor de parto en las pacientes que recibieron piracetam, con relacion al grupo control