Biomedical subjects

N Reis

Publications and source records attributed to N Reis.

8 recordsLinked to original sources

PubMed2006

Proof-of-concept of a novel micro-bioreactor for fast development of industrial bioprocesses.

The experimental performance of a novel micro-bioreactor envisaged for parallel screening and development of industrial bioprocesses has been tested in this work. The micro-bioreactor with an internal volume of 4.5 mL is operated under oscillatory flow mixing (OFM), where a controllable mixing and mass transfer rates are achieved under batch or continuous laminar flow conditions. Several batch fermentations with a flocculent Saccharomyces cerevisiae strain were carried out at initial glucose concentrations (S(0)) range of approximately 5-20 g/L and compared to yeast growth kinetics in a stirred tank (ST) bioreactor. Aerobic fermentations were monitored ex situ in terms of pH, DO, glucose consumption, and biomass and ethanol production (wherever applicable). An average biomass production increase of 83% was obtained in the micro-bioreactor when compared with the ST, with less 93.6% air requirements. It also corresponded to a 214% increase on biomass production when compared with growth in a shaken flask (SF) at S(0) = 20 g/L. Further anaerobic fermentations at the same initial glucose concentration ranges gave the opportunity to use state-of-the-art fiber optics technology for on-line and real-time monitoring of this bioprocess. Time profiles of biomass concentration (measured as optical density (OD)) were very similar in the ST bioreactor and in the micro-bioreactor, with a highly reproducible yeast growth in these two scale-down platforms.

Biomass↗

PubMed2006

Application of a novel oscillatory flow micro-bioreactor to the production of gamma-decalactone in a two immiscible liquid phase medium.

A novel micro-bioreactor based on the oscillatory flow technology was applied to the scale-down of the biotechnological production of gamma-decalactone. A decrease up to 50% of the time required to obtain the maximum concentration of the compound was observed, when compared with other scaled-down platforms (stirred tank bioreactor or shake flask). A three-fold increase in gamma-decalactone productivity was obtained by increasing oscillatory mixing intensity from Re(o) approximately 482 to Re(o) approximately 1447. This was presumably related to the effective contribution of the reactor geometry to enhanced mass transfer rates between the two immiscible liquid phases involved in the process by increasing the interfacial area.

Bioreactors↗

PubMed2003

Novel collagen scaffolds with predefined internal morphology made by solid freeform fabrication.

Novel collagen scaffolds possessing predefined and reproducible internal channels with widths of 135 microm and greater have been produced. The process employed to make the collagen scaffold utilises a sacrificial mould, manufactured using solid freeform fabrication technology, and critical point drying technique. A computer aided design (CAD) file of the mould to be produced is created. This mould is manufactured using a phase change ink-jet printer. A dispersion of collagen is then cast into the mould and frozen. The mould is dissolved away with ethanol and the collagen scaffold is then critical point dried with liquid carbon dioxide. The effect of processing on the tertiary structure of collagen is assessed by monitoring the wavenumber of the N-H stretching vibration peak using Fourier transform infra-red spectroscopy and it is found that processing does not denature the collagen. Ultraviolet-visual spectroscopy was used to detect the presence of any contamination from the sacrificial mould on the collagen. The ability to use computer aided design and manufacture (CAD/CAM) provides a route to optimise scaffold designs using collagen in tissue engineering applications.

Animals↗

PubMed2001

Subunit interaction maps for the regulatory particle of the 26S proteasome and the COP9 signalosome.

The 26S proteasome plays a major role in eukaryotic protein breakdown, especially for ubiquitin-tagged proteins. Substrate specificity is conferred by the regulatory particle (RP), which can dissociate into stable lid and base subcomplexes. To help define the molecular organization of the RP, we tested all possible paired interactions among subunits from Saccharomyces cerevisiae by yeast two-hybrid analysis. Within the base, a Rpt4/5/3/6 interaction cluster was evident. Within the lid, a structural cluster formed around Rpn5/11/9/8. Interactions were detected among synonymous subunits (Csn4/5/7/6) from the evolutionarily related COP9 signalosome (CSN) from Arabidopsis, implying a similar quaternary arrangement. No paired interactions were detected between lid, base or core particle subcomplexes, suggesting that stable contacts between them require prior assembly. Mutational analysis defined the ATPase, coiled-coil, PCI and MPN domains as important for RP assembly. A single residue in the vWA domain of Rpn10 is essential for amino acid analog resistance, for degrading a ubiquitin fusion degradation substrate and for stabilizing lid-base association. Comprehensive subunit interaction maps for the 26S proteasome and CSN support the ancestral relationship of these two complexes.

Arabidopsis Proteins↗

PubMed2000

Simple sequence repeats in Cucumis mapping and map merging.

Thirty-four polymorphic simple-sequence repeats (SSRs) were evaluated for length polymorphism in melon (Cucumis melo L.) and cucumber (Cucumis sativus L.). SSR markers were located on three melon maps (18 on the map of 'Vedrantais' and PI 161375, 23 on the map of 'Piel de Sapo' and PI 161375, and 16 on the map of PI 414723 and 'Dulce'). In addition, 14 of the markers were located on the cucumber map of GY14 and PI 183967. SSRs proved to be randomly distributed throughout the melon and cucumber genomes. Mapping of the SSRs in the different maps led to the cross-identification of seven linkage groups in all melon maps. In addition, nine SSRs were common to both melon and cucumber maps. The potential of SSR markers as anchor points for melon-map merging and for comparative mapping with cucumber was demonstrated.

Chromosome Mapping↗

PubMed1999

Left-handed women have earlier age of menopause.

Association between handedness and age of menopause was assessed. A significant difference in the mean age of menopause was found between left-handed and right-handed women. There was a significant correlation between age at menopause and hand preference in right-handed women. These findings suggest that earlier age of menopause in left-handed women may be due to a more active and effective immune system in left-handers.

Adult↗

PubMed1996

Detection of coccidioidal antibodies by 33-kDa spherule antigen, Coccidioides EIA, and standard serologic tests in sera from patients evaluated for coccidioidomycosis.

During a 9-month study of patients being evaluated for coccidioidomycosis, 1 or more serum samples were obtained from 138 patients with an illness suggestive of recent infection. In this group, standard immunodiffusion tests of unconcentrated sera were positive for 25; 49 additional patients had at least 1 reactive test result by newer enzyme-linked serologic tests. At least 11 of these 49 patients had coccidioidomycosis as determined by culture or subsequent standard serologic tests. Patients with coccidioidomycosis identified only by newer tests had fewer or milder clinical abnormalities than did patients in whom the disease was detected by standard tests. For 31 other patients with illness of a chronic or undetermined duration, newer tests detected only 10 more than the 18 identified by standard tests, suggesting that later in the course of illness, standard testing gains in sensitivity for coccidioidal infection.

Antibodies, Fungal↗

PubMed1984

Bacteriuria screening by direct bioluminescence assay of ATP.

A direct bioluminescence assay for bacteriuria screening is described and compared with the MS-2 system (Abbott Laboratories, Irvine, Tex.) and the chemical strip, Gram smear, and calibrated-loop methods. A total of 973 specimens were tested. Unlike previously described bioluminescence methods, this test measures total ATP in urine without pretreatment of samples to remove somatic ATP. The result was compared with an ATP standard (20 ng/ml). A low result (less than 3% of standard) was interpreted as negative and a high result (greater than 10% of standard) as positive. Samples with intermediate results (38% of total) were incubated at 35 degrees C in thioglycolate broth (1:10). A 2% increase in ATP concentration was interpreted as positive. The sensitivity of this method for detecting greater than 10(5) pathogens per ml was 92.3% and was comparable to those of the MS-2 system (92.7%) and the Gram smear method (90.5%). The chemical strip method was less sensitive (84.0%). The direct bioluminescence method was more sensitive than were the MS-2 system and the Gram smear method for detecting low-level bacteriuria (less than 10(3) to 10(5) organisms per ml), primarily because of associated pyuria. Thioglycolate broth provided a suitable medium for ATP production, and 5% CO2 decreased bacterial ATP synthesis during log-phase growth. The direct bioluminescence assay is rapid, simple, cost-effective, and reliable for bacteriuria screening.

Adenosine Triphosphate↗