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Biomedical subjects

E Giménez

Publications and source records attributed to E Giménez.

9 recordsLinked to original sources
PubMed2001

Variegated expression and delayed retinal pigmentation during development in transgenic mice with a deletion in the locus control region of the tyrosinase gene.

Deletion of the tyrosinase locus control region (LCR) in transgenic mice results in variegated expression in the skin. Here we investigate the pigmentation pattern of other tissues that express tyrosinase: iris, choroid, and retina in the same animals. A mosaic distribution of pigmentation appears in the iris and choroid. Interestingly, a markedly different mosaic pattern is found in the retina, where central areas contain little or no melanin while pigmentation rises to normal levels towards periphery. Further, there is a temporal delay in the initiation and accumulation of pigment in retinal pigmented epithelium (RPE) cells during development, and patterns of adult retinal melanisation in these mice appear arrested at a stage found in early embryogenesis in wild-type mice. These results demonstrate that the tyrosinase LCR is needed for the correct establishment and maintenance of this expression domain throughout development, but particularly during the later stages of retinal melanisation.

Alleles↗
PubMed2001

A simple polymerase chain reaction assay for genotyping the retinal degeneration mutation (Pdeb(rd1)) in FVB/N-derived transgenic mice.

FVB/N mice are one of the most common inbred strains for the generation of transgenic animals. This mouse strain is preferred for transgenesis because of its fertilized oocytes, which have unique pronuclei for microinjection, and its vigorous reproductive performance along with consistently large litter sizes. However, these inbred mice carry a retinal degeneration mutation caused by a proviral insertion into the Pdeb gene, encoding the beta subunit of cGMP phosphodiesterase. This mutation (Pdeb(rd1), formerly known as rd) results in postnatal rod photoreceptor degeneration and causes severe visual impairment, which may be relevant for behavioural and vision-related research. This deficit can be overcome by crossing these mice with other mouse strains carrying the wild-type allele at the Pdeb locus. We have devised a simple polymerase chain reaction (PCR)-based method for distinguishing between the mutant and the wild-type alleles, thus allowing the efficient monitoring of the Pdeb(rd1) mutation in FVB/N-derived transgenic mice prior to experimentation where visual deficit is expected to have an influence in the phenotype.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMedDate not supplied

[Influencing factors in the control of phosphorus in peritoneal dialysis. Therapeutic options].

UNLABELLED: Impaired phosphate excretion resulting in hyperphosphatemia is one of the earliest consequences of chronic renal failure. To control serum phosphate levels, we can use the following therapies: 1) Restriction of dietary phosphate (but on CAPD, obligatory protein losses via peritoneal fluid makes impractical any reduction of phosphate diet. 2) Reduction of phosphate absorption, using phosphate binders. 3) Peritoneal phosphate removal. OBJECTIVE: 1) To evaluate the factors affecting peritoneal phosphate removal such as plasma phosphate, peritoneal membrane transport type, peritoneal dialysis modality prescription (CAPD or APD) and daily dialysate volume. 2) To test the best calcium concentration in the peritoneal dialysis fluid (5, 6 or 7 mg/dl) in order to permit the use of calcium carbonate or acetate without the risk of hypercalcemia or hyperparathyroidism. METHOD: Phosphate was measured in seventy 24-hour dialysate collections, 33 from patients on CAPD and 37 from patients on APD. 24-hour peritoneal phosphate removal (mg/24 hours) and weekly peritoneal phosphate clearance was calculated (L/week). The peritoneal membrane was studied by the peritoneal equilibrium test (PET), using a 2.27% glucose. We calculated also the peritoneal calcium balance in 25 daily peritoneal fluid collections from patients using a calcium dialysate concentration of 5, 6 or 7 mg/dl each one. IPTH levels and doses of vitamin D were compared at 6 months in patients using a calcium concentration of 5, 6 or 7 mg/dl from the beginning of peritoneal dialysis (5 patients of each calcium dialysate concentration). RESULTS: Weekly peritoneal phosphate clearance (WPC) were higher or APD than on CAPD (51 +/- 21 vs 41 +/- 14, p < 0.005). Daily dialysate volume was also higher on APD (14 +/- 4 vs 7.8 +/- 1.8 L/day, p < 0.001). WPC was higher on APD when a mild-day exchange was done (61 +/- 23 vs 45 +/- 15, p < 0.005), instead an equal total daily volume of the dialysate. Peritoneal calcium balance was significantly more negative in patients using a calcium in the dialysis fluid of 5 than 6 or 7 mg/dl (-125 +/- 7 vs -18 +/- 41 vs -11 +/- 49, p < 0.001). At 6 months, patients using a calcium fluid concentration of 5 mg/dl increased iPTH levels (from 160 +/- 101 to 332 +/- 153, p < 0.001) and vitamin D needs (from 0 to 1.87 +/- 0.37 mcg/week, p < 0.001). In summary, peritoneal phosphate clearance depends on plasma phosphate levels, daily volume of dialysate prescribed and peritoneal membrane transport characteristics. It can be improved by increasing the total peritoneal fluid. On APD, a mild-day exchange may improve phosphate clearance, without total volume increase. The risk of secondary hyperparathyroidism can be decreased with a calcium fluid concentration of 6 mg/dl, which was shown to be better than 5 mg/dl when calcium phosphate binders are not correctly taken.

Calcium↗