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Biomedical subjects

M Carmo

Publications and source records attributed to M Carmo.

7 recordsLinked to original sources
PubMed2006

Relationship between retroviral vector membrane and vector stability.

The present work studies the physico-chemical properties of retroviral vector membrane, in order to provide some explanation for the inactivation kinetics of these vectors and to devise new ways of improving transduction efficiency. For this purpose, vectors with an amphotropic envelope produced by TE Fly A7 cells at two culture temperatures (37 and 32 degrees C) were characterized by different techniques. Electron paramagnetic resonance (EPR) results showed that vectors produced at 32 degrees C are more rigid than those produced at 37 degrees C. Further characterization of vector membrane composition allowed us to conclude that the vector inactivation rate increases with elevated cholesterol to phospholipid ratio. Differential scanning calorimetry (DSC) showed that production temperature also affects the conformation of the membrane proteins. Transduction studies using HCT116 cells and tri-dimensional organ cultures of mouse skin showed that vectors produced at 37 degrees C have higher stability and thus higher transduction efficiency in gene therapy relevant cells as compared with vectors produced at 32 degrees C. Overall, vectors produced at 37 degrees C show an increased stability at temperatures below 4 degrees C. Since vector membrane physico-chemical properties are affected in response to changes in culture temperature, such changes, along with alterations in medium composition, can be used prospectively to improve the stability and the transduction efficiency of retroviral vectors for therapeutic purposes.

Animals↗
PubMed2004

Quantitation of MLV-based retroviral vectors using real-time RT-PCR.

Murine leukaemia virus-based vectors quantitation is a time consuming process that can take up to five days. In order to reduce this time a real-time RT-PCR was developed. This method quantifies vectors without an RNA extraction step, using AMV reverse transcriptase and LightCycler technology. Besides a low quantitation time, this method has the advantages of using a plasmid DNA standard curve with good reproducibility, and of having a high sensitivity (3 x 10(2) particles/microl) as well as an excellent intra- and inter-assay reproducibility. Although the method described quantifies vector particles with RNA whether these particles are infectious or not, it is possible to use it to determine infectious particles concentration after the establishment of a correlation between particles with RNA and infectious particles, for a given set of conditions. This method can also be used to study vector stability by comparison of infectious particles, total particles and particles with RNA.

Genetic Vectors↗
PubMed2002

Alteration of elastin, collagen and their cross-links in abdominal aortic aneurysms.

OBJECTIVES: although the mechanism of arterial dilation and aneurysm development has not been clarified, the degradation of elastin and collagen plays undoubtedly a critical role. We evaluated the elastin and collagen content through the detection of their cross-links in aneurysmal and non-aneurysmal abdominal aortic walls. MATERIALS AND METHODS: in 26 human abdominal aortic aneurysm specimens obtained during surgery and in 24 autopsy control samples of non-aneurysmal abdominal aorta the tissue content of elastin and collagen cross-links were measured by HPLC. Collagen was also detected by evaluating two characteristic amino acids, 4-hydroxyproline (4-hypro) with a colorimetric method and 5-hydroxylysine (5-hylys) by gas chromatography. RESULTS: significantly fewer elastin cross-links were found in aneurysm samples compared to controls (desmosines and isodesmosines: 90% reduction; p<0.01). The opposite was true for pyridinoline collagen cross-links (350% increase) and deoxypyridinolines (100% increase, p=0.01). Tissue content of 5-hylys, 4-hypro and total amino acids were reduced significantly by 50% in aneurysmal samples. CONCLUSIONS: beside confirming decreased elastin content in aneurysmal walls, these results show a concurrent increase of collagen cross-links. Since total collagen markers were decreased (decreased 4-hypro and 5-hylys) it is reasonable to suggest that in aneurysmal aortic walls old collagen accumulates cross-links while new collagen biosynthesis is somehow defective.

Aged↗
PubMed2000

Enzymatic determination of choline in milk using a FIA system with potentiometric detection.

The development of a FIA system for the determination of total choline content in several types of milk is described. The samples were submitted to hydrochloric acid digestion before injection into the system and passed through an enzymatic reactor containing choline oxidase immobilised on glass beads. This enzymatic reaction releases hydrogen peroxide which then reacts with a solution of iodide. The decrease in the concentration of iodide ion is quantified using an iodide ion selective tubular electrode based on a homogeneous crystalline membrane. Validation of the results obtained with this system was performed by comparison with results from a method described in the literature and applied to the determination of total choline in milks. The relative deviation was always < 5%. The repeatability of the method developed was assessed by calculation of the relative standard deviation (RSD) for 12 consecutive injections of one sample. The RSD obtained was < 0.6%.

Animals↗
PubMed1996

Aneurysms of anomalous splenomesenteric trunk: clinical features and surgical management in two cases.

Aneurysms of the splenic artery that anomalously arise from a splenomesenteric trunk are a rarity. Aneurysmal disease of visceral arteries is found in only 0.2% of the general population. The celiac trunk and superior mesenteric artery (SMA) are involved in less than 10% of all visceral aneurysms. Although rupture seems to occur in 20% to 22% of patients, the related mortality rate can rise as high as 100%. Anomalies of the celiac trunk and SMA, more common than previously claimed, include the splenic artery arising from the SMA, which occurs in only 1% of patients. We present two cases of young patients who had 4-cm aneurysms behind the pancreas that involved an anomalous splenic artery. The first patient required dissection of the entire splenopancreatic bloc through a transverse abdominal incision to excise the aneurysm and repair the SMA. The second patient was treated by the classic approach, through a median incision and by entering the mesenteric root. There do not seem to be reports of similar cases, except for two cases of aneurysms involving the celiomesenteric trunk. The cause of these aneurysms can be attributed to mesenchymal alterations during the embryonic formation of aortic collateral branches. A correct surgical approach to splanchnic aneurysms calls for awareness of potential vascular variations of the arteries and their collateral pathways.

Adult↗
PubMed1986

Allergy to oil of turpentine in Portugal.

Oil of turpentine is still a common allergen in Portugal although it does not contain delta 3-carene, as ascertained by gas chromatography. Patch tests with 6 terpenes on 22 patients revealed that 17 were allergic to alpha-pinene and 15 to dipentene; 12 were allergic to both. 4 patients were sensitive to delta 3-carene, 3 to alpha-terpineol and 2 to beta-pinene. These results explain the incidence of allergy to oil of turpentine in Portugal.

Dermatitis, Contact↗