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Biomedical subjects

M Melgosa

Publications and source records attributed to M Melgosa.

7 recordsLinked to original sources
PubMed2001

Membranous nephropathy associated with hepatitis B in Spanish children.

AIM: To examine retrospectively long-term evolution and treatment of pediatric membranous nephropathy (MN) cases associated with hepatitis B (HB) in the hospital "La Paz". MATERIAL AND METHODS: The clinical records of 12 children diagnosed with HB-associated MN in our hospital between 1970 and 1996. RESULTS: All patients were positive for hepatitis B surface antigen (HBsAg); 6 were tested for hepatitis Be antigen (HBeAg) and were also positive. At onset, all of them had proteinuria (8 in nephrotic range), 6 had microscopic hematuria and 4 macroscopic hematuria. Seven of 8 children who started with a nephrotic syndrome received steroids and all of them were steroid-resistant. After 9.95 +/- 5.88 years of follow-up, renal function remained normal and proteinuria and hematuria have disappeared in all of them. A family study for hepatitis B was carried out in 8 cases and 7 of them were positive. Only in one case vertical transmission was demonstrated; this patient remained HBeAg positive. In 7 patients, hepatic biopsy was performed: 3 had a chronic active hepatitis, 3 a persistent chronic hepatitis and one a residual acute hepatitis. CONCLUSIONS: Membranous nephropathy is a rare pediatric disease in our area and most of the cases are related to hepatitis B (HB). The outcome was excellent with and without treatment but all of them remained HBsAg positive.

Child↗
PubMed2000

Towards a colorimetric characterization of the human iris.

We propose a new approach to the quantitative determination of the iris colour through the spectroradiometric measurement of a set of 72 artificial irises under controlled illumination and geometry. The spread of these samples in the CIELAB colour space indicates no clearly distinguished groups within the set analysed. Colour measurements for different points of these irises and for the overall irises (pupil and specular image of the light source included) are well correlated. Complementary colour measurements were also performed for the irises of 25 ocular prostheses and 40 real observers. All these colour measurements appear to be quite consistent, the average standard deviation of any of the three a*, b*, L* co-ordinates being lower than 1.0 units. In a visual experiment where 11 normal observers matched the 25 ocular prostheses using the 72 artificial irises, the results indicate that a simple criterion based on the lowest colour-difference agreed with the observers' judgements in only 18% of the cases. This result suggests that, although colour appears to be a major parameter in the overall characterization of the human iris, additional factors such as patterns or textures should also be considered.

Colorimetry↗
PubMed1998

Absorbable screws through the greater trochanter do not disturb physeal growth: rabbit experiments.

We studied the effect of implantation of self-reinforced polyglycolic acid (SR-PGA) screws through the greater trochanter in rabbits. 15 rabbits aged 10 weeks had an SR-PGA screw inserted through the left trochanter physis. A similar drilling was made through the right greater trochanter without screw implantation. The animals were assigned to 3 groups of 5, and were killed after 1, 2 or 3 months. Radiographs of both femurs were obtained monthly and the articulo-trochanteric distance and the neck-shaft angle were measured. After killing the animals, a histological study was performed. The drilling on the right trochanter generated a bony bridge in all the animals. The SR-PGA screws did not give rise to an epiphysiodesis. The progressive peripheral degradation of the implants gave rise to the formation of only modest bridges, which were smaller in size than those observed in the control trochanter. Our findings suggest that absorbable PGA screws implanted through a growth plate cause only minor bone formation and no epiphyseodesis.

Animals↗
PubMed1997

Performance of a color indicator in a disinfecting solution for the maintenance of soft contact lenses.

An experimental study of Allergan's Oxysept Comfort system was performed by measuring the slight reddish hue that appears in the disinfecting solution, indicating to the users that their lenses are again ready to be worn. The temporal evolution of the color of the solution has been measured under standardized conditions and analyzed in the CIELAB system, from the perspective of the typical threshold discrimination of the human eye. Color differences between neutralized and non-neutralized solutions occurred in an appropriate direction of the color space to enhance discrimination and were clearly perceptible by normal observers (greater than 9.7 +/- 1.2 CIELAB units). Colorimetric analyses have been used to draw conclusions regarding observers with defective color vision. The color of the solution changes abruptly, approximately 25 min after the neutralization process begins, and remains nearly constant after about 60 min, this agreeing well with the temporal evolution of the hydrogen peroxide concentration.

Color↗
PubMed1997

Soft tissue behavior during limb lengthening: an experimental study in lambs.

The effect of femoral elongation on skeletal muscle, nerves, and vessels was studied. Three groups of five lambs were used. After the intervention, the animals were killed at 2, 3, and 4 months. A left femoral elongation of 6 cm was practiced on all of them by means of callotasis, with a distraction rate of 0.5 mm every 12 hours. The femoral elongation process was evaluated by monthly x-ray films. The nucleic acid and protein levels in the muscular tissue were quantified at the level of the elongation focus and in the control extremity. The motor conduction velocity of the sciatic nerve was measured in both posterior limbs before the intervention and immediately before the lambs were killed. The arterial blood flow of both subsequent extremities was measured at the moment of death. A histological study of quadriceps muscle, sciatic nerves, artery, and subsequent femoral vein were examined histologically at the level of the elongation focus of both extremities. After elongation, no significant differences were observed in the muscle protein and nucleic acid levels with respect to the control extremity. No significant changes of the nerve conduction velocity were observed in any animal among the different groups. The arterial blood flow of the elongated extremity showed a progressive increase, reaching its maximum value 1 month after the distraction had terminated, with subsequent normalization. This increase of the blood flow was also observed in the control extremity, suggesting a possible systemic effect. The histological study revealed a comparative thickening of the endomysium and perimysium in the elongated muscle tissue, present at the end of the distraction and which was later normalized. No histological changes of the nerve stems undergoing distraction were observed either. During elongation, the arteries showed minimal histological changes. On the other hand, the veins showed areas of endothelial damage accompanied by thrombosis phenomena, especially at the end of the distraction period. The vascular morphology presented progressive normalization after the distraction phase.

Animals↗