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Biomedical subjects

A Cobo

Publications and source records attributed to A Cobo.

At least 19 recordsLinked to original sources
PubMed2001

Use of fluorescence in situ hybridization to assess the chromosomal status of embryos obtained from cryopreserved oocytes.

OBJECTIVE: To analyze the chromosomal status of human embryos obtained from frozen-thawed oocytes. DESIGN: Fluorescence in situ hybridization analysis of embryos obtained after oocyte cryopreservation. SETTING: Department of Obstetrics and Gynecology at the University of Perugia, Italy, and the Instituto Valenciano de Infertilidad, Spain. PATIENT(S): Oocyte donors (n = 43). Fertilization, development, and chromosomal status of the embryos were compared with a control group (n = 18) of patients undergoing preimplantation genetic diagnosis for sex chromosome-linked diseases. INTERVENTION(S): Collection of oocytes after conventional ovarian stimulation and cryopreservation using propanediol as the cryoprotectant and a slow freezing procedure. Microinjection of surviving metaphase II oocytes and evaluation of fertilization and embryo development up to blastocyst stage. Chromosomal analysis after embryo biopsy. MAIN OUTCOME MEASURE(S): Survival, fertilization, and blastocyst rates. Embryo chromosomal analysis employing specific probes for chromosomes 13,18,21, X and Y. RESULT(S): The overall survival rate was 59.4%. There was no difference between cryopreservation and control groups in fertilization rates (76.5% vs. 90.5%) or blastocyst development (29.6% vs. 35%). The percentage of blastocysts from the original number of cryopreserved oocytes was only 5.6%, comparable to the 5.9% obtained in the control group. The percentage of embryos with abnormal number of chromosomes in the cryopreservation group (28.6%) was comparable to the 26% observed in the controls. CONCLUSION(S): Fertilization and cleavage rates after oocyte freezing are acceptable. Survival is, however, still poor, leading to overall results that make the technique clinically inefficient. There is no increase in the rate of chromosomal abnormalities, indicating that the technique is, nevertheless, safe enough to be further explored and improved.

Adult↗
PubMed2001

Attentional shifts between surfaces: effects on detection and early brain potentials.

Two consecutive events transforming the same illusory surface in transparent motion (brief changes in direction) can be discriminated with ease, but a prolonged interference ( approximately 500 ms) on the discrimination of the second event arises when different surfaces are concerned [Valdes-Sosa, M., Cobo, A., & Pinilla, T. (2000). Attention to object files defined by transparent motion. Journal of Experimental Psychology: Human Perception and Performance, 26(2), 488-505]. Here we further characterise this phenomenon and compare it to the attentional blink AB [Shapiro, K.L., Raymond, J.E., & Arnell, K.M. (1994). Attention to visual pattern information produces the attentional blink in RSVP. Journal of Experimental Psychology: Human Perception and Performance, 20, 357-371]. Similar to the AB, reduced sensitivity (d') was found in the two-surface condition. However, the two-surface cost was associated with a reduced N1 brain response in contrast to reports for AB [Vogel, E.K., Luck, S.J., & Shapiro, K. (1998). Electrophysiological evidence for a postperceptual locus of suppression during the attentional blink. Journal of Experimental Psychology: Human Perception and Performance, 24(6), 1656-1674]. The results from this study indicate that the two-surface cost corresponds to competitive effects in early vision. Reasons for the discrepancy with the AB study are considered.

Adult↗
PubMed2000

Attention to object files defined by transparent motion.

Two interspersed and differently colored sets of dots were rotated in opposite directions and were perceived as superimposed transparent surfaces. Probes consisting of brief changes in dot motion direction were reported. Two probes affecting the same surface were discriminated accurately. The 2nd probe was discriminated poorly if it affected a surface different from the 1st and if the time between probes was less than 600 ms. This reflects a difficulty in switching attention rapidly between surfaces. Spatial proximity increased the interference. Controls were incompatible with traditional spatial mechanisms (2- or 3-dimensional) or with simple sensory filters. Instead, probes were apparently selected by object files. The interference is not simply due to an inability to process 2 objects at once but requires close spatial proximity of incompatible motion signals.

Adult↗
PubMed1999

Growth plate cartilage formation and resorption are differentially depressed in growth retarded uremic rats.

To characterize the modifications of growth plate in individuals with growth impairment secondary to chronic renal failure, young rats were made uremic by subtotal nephrectomy (NX) and, after 14 d, their tibial growth plates were studied and compared with those of sham-operated rats fed ad libitum (SAL) or pair-fed with NX (SPF). NX rats were growth retarded and severely uremic. Growth plate height (mean +/- SD) was much greater (P<0.05) in NX (868.4+/-85.4 microm) than SAL (570.1+/-93.5 microm) and SPF (551.9+/-99.7 microm) rats as a result of a higher (P<0.05) hypertrophic zone (661.0+/-89.7 versus 362.8+/-71.6 and 353.0+/-93.9 microm, respectively). The increased size of the growth plate was associated with a greater number of chondrocytes and modifications in their structure, particularly in the hypertrophic zone adjacent to bone. In this zone, chondrocytes of NX animals were significantly (P<0.05) smaller (12080.4+/-1158.3 microm3) and shorter (34.1+/-2.5 microm) than those of SAL (16302.8+/-1483.4 microm3 and 37.8+/-2.0 microm) and SPF (14465.8+/-1521.0 microm3 and 36.3+/-1.8 microm). The interface between the growth plate cartilage and the metaphyseal bone appeared markedly irregular in NX rats. Kinetics of chondrocytes was also modified (P<0.05) in the NX rats, which had lower cell turnover per column per day (5.4+/-0.9), longer duration of hypertrophic phase (89.0+/-15.2 h), and reduced cellular advance velocity (7.4+/-2.2 microm/h) compared with SAL (8.0+/-1.6, 32.1+/-6.7 h, and 11.3+/-2.7 microm/h) and SPF (7.2+/-1.1, 34.8+/-5.1 h, and 10.1+/-2.5 microm/h). Cell proliferation was no different among the three groups. Because the growth plates of SPF and SAL rats were substantially not different, modifications observed in the NX rats cannot be attributed to the nutritional deficit associated with renal failure. These findings indicate that chronic renal failure depresses both the activity of the growth plate cartilage by altering chondrocyte hypertrophy and the replacement of cartilage by bone at the metaphyseal end. The two processes are differentially depressed since cartilage resorption is more severely lowered than cartilage enlargement and this leads to an accumulation of cartilage at the hypertrophic zone.

Animals↗
PubMed1998

Transparent motion and object-based attention.

The difficulty in processing two stimuli at once increases with their separation. Therefore to demonstrate constraints in dividing attention between objects, the effects of their spatial separation must be controlled. Duncan used superimposed objects to achieve this, and showed that judging two attributes is more accurate if they concern one object than if they concern two objects (Duncan, J. 1984. Journal of Experimental Psychology: General, 113, 501-517). However, critics claim that differences in the spatial or spatial-frequency extent of attention exist between these conditions. We studied transparent motion defined by two sets of differently colored dots that were interspersed in the same region of space, and matched in spatial and spatial frequency properties. Each set moved in a distinct and randomly chosen direction. We found that simultaneous judgments of speed and direction were more accurate when they concerned only one set than when they concerned different sets. Furthermore, appraisal of the directions taken by two sets of dots is more difficult than judging direction for only one set, a difficulty that increases for briefer motion. We conclude that perceptual grouping by common fate exerted a more powerful constraint than spatial proximity, a result consistent with object-based attention. Evidence that this type of object-based attention operates at early stages of vision is examined.

Adult↗
PubMed1996

Chronic renal failure and human growth hormone treatment do not modify endothelium-dependent reactions in the rat aorta in vitro.

1. Growth hormone (GH) increases glomerular filtration rate and renal plasma flow and decreases renal vascular resistance. Sustained GH-induced hyperfiltration might be undesirable in children with chronic renal failure (CRF) who are receiving recombinant human GH (rhGH) therapy. 2. In order to determine the effect of CRF on vascular reactivity and the modifications induced by rhGH administration, two endothelium-dependent effects, acetylcholine relaxation and decrease of contractile response to noradrenaline, were studied in aorta segments of various groups of male Sprague-Dawley rats: CRF rats (CRF, n = 8) with serum urea nitrogen (SUN) 68 +/- 16 mg dl-1 (mean +/- SEM), CRF rats treated with intraperitoneal rhGH at 10 IU kg-1 day-1 for 13 days (CRFGH, n = 6, SUN = 88 +/- 15 mg dl-1), sham operated rats (SHAM, n = 8, SUN: 21 +/- 1 mg dl-1) and control rats (CONTROL, n = 8, SUN 20 +/- 1 mg dl-1), housed in identical conditions but without undergoing surgical intervention or manipulation. CRF was induced by 5/6 two stage nephrectomy. 3. Rats were sacrificed and a segment of thoracic aorta was immediately removed, cut into spirals, and suspended in organ baths according to standard procedures. First, dose-response curves to noradrenaline and acetylcholine relaxation, in strips previously exposed to noradrenaline, were determined. Then, the endothelium was removed and both dose-response curves were repeated. Acetylcholine induced a greater relaxation, P < 0.05, in the aorta of CONTROL rats (82.6 +/- 6.1%) as compared with SHAM (60.3 +/- 4.7%), CRF (60.0 +/- 6.8%) and CRFGH (54.8 +/- 8.2%) rats. 4. Endothelium removal only caused a greater contractile response to noradrenaline (10(-9) and 3 x 10(-9)M) in the CONTROL group, P < 0.05. 5. No differences to acetylcholine and noradrenaline responses were found among the SHAM, CRF and CRFGH groups. 6. These results suggest that the endothelium-dependent vascular reactivity was modified by the experimental protocol to induce chronic renal failure but no further changes resulted from uraemia and rhGH treatment.

Acetylcholine↗
PubMed1996

Morphometry of uremic rat growth plate.

Growth retardation is a common manifestation of chronic renal failure in children. To gain insight into the alterations of bone growth plate of chronic uremia, a morphometric study of tibia proximal growth plate was performed in 5/6 nephrectomized rats (NX, n = 4) and sham animals (SHAM, n = 4). Toluidine blue stained sagittal sections (5-6 microns) from ethanol-fixed and methylmethacrylate-embedded tibias were analyzed. Widths (X +/- SEM) of growth plate (GPW), proliferative (PZW) and hypertrophic zones (HZW) were calculated. Results were as follows: [table: see text] Growth plate modifications in uremia are rather due to alterations in the hypertrophic than proliferative zone. This is consistent with an abnormal metabolism of condrocytes as shown by a lower mean area of extracellular matrix (EMA) per cell in the hypertrophic zone of the NX rats (0.23 vs. 0.58 microns 2).

Animals↗
PubMed1996

Assessment of protein intake in children with chronic renal insufficiency.

Daily nitrogen intake was estimated in 19 children, aged (mean +/- SD) 9.9 +/- 5.0 (range: 1-19) years with chronic renal insufficiency (creatinine clearance 47.1 +/- 19.3 ml/min/1.73 m2, range: 11-75) by 31 three-day prospective dietary records (NIDR) and simultaneous 24-hour urine urea excretion (NIUE). Daily nitrogen intake was 11.05 +/- 3.9 g by NIDR and 8.52 +/- 3.3 g by NIUE, and a significant correlation (r = 0.61; p = 0.0003) existed between both methods of measurement. However, the difference in nitrogen intake estimated from dietary records and from 24-hour urine collection (NIDR-NIUE) was 2.5 +/- 3.3 g, greater than the mean estimated nitrogen intake calculated from both methods, (NIDR + NIUE)/2, 95% limits of agreement being +9.1 to -4.1. Thus, NIDR and NIUE values show a good correlation in children with chronic renal insufficiency, although both methods may provide quite a different estimation in a given child.

Adolescent↗
PubMed1996

Analysis of growth in five-sixths-nephrectomized rats.

The present study was designed in an attempt to better define the pattern of growth in five-sixths-nephrectomized rats. Male Sprague-Dawley rats underwent two-stage (days 0 and 7) five-sixths nephrectomy (NX, n = 16) or sham surgery (SHAM, n = 9). At the time of sacrifice (day 21), renal failure (CRF) of NX rats was confirmed by elevated (p < or = 0.0001) serum concentrations (X +/- SEM) of urea nitrogen (SUN) (56 +/- 5 vs. 20 +/- 1 mg/dl) and creatinine (0.7 +/- 0.04 vs. 0.4 +/- 0.02 mg/dl) and reduced SUN (0.13 +/- 0.02 vs. 0.44 +/- 0.05 ml/min/100 g) and creatinine clearances (0.23 +/- 0.02 vs. 0.58 +/- 0.05 ml/min/100 g). As shown by lower cumulative gains of weight (41 +/- 6 vs. 74 +/- 4 g) and length (5.0 +/- 0.4 vs. 6.8 +/- 0.3 cm), NX rats grew subnormally. Detailed analysis of growth data revealed: (1) In spite of being identically matched in weight and length on day 0, at day 7, NX rats already weighed less than SHAM animals (147.1 +/- 2.3 vs. 153.4 +/- 1.9 g, p = 0.03). (2) From day 7 on, daily gain of weight was lower in the NX group only on days 8 (-6.08 +/- 0.52 vs. -1.60 +/- 0.69 g/100 g body weight) and 9 (-0.41 +/- 1.73 vs. 5.18 +/- 0.63 g/100 g body weight). (3) Following the early post-second-nephrectomy period, two subgroups of NX rats were clearly differentiated according to whether or not their daily growth rate was lower than that of SHAM animals. Maintained subnormal growth rate was observed in rats with severe CRF (SUN 73 +/- 5 mg/dl, range 54-90) but not in rats having milder uremia (42 +/- 3 mg/dl, range 31-51). Thus, growth in five-sixths-nephrectomized rats should be reported based on daily weight increments (g/100 g body weight). Subnormal growth can be attributed to CRF provided SUN is at least 3 times as high as normal while growth impairment of rats with less marked reduction of renal function is likely related to transient acute renal failure and postsurgical catabolic state.

Animals↗
PubMed1995

Nutritional status of children with moderate chronic renal failure.

Nutritional status was evaluated in 15 children (11 males) with moderate chronic renal failure (CRF). Two 3-day prospective dietary records, anthropometric measures and biochemical determinations were performed 3 months apart. Energy, protein, carbohydrate, fat, polyunsaturated, monounsaturated and saturated fatty acid intakes, expressed as percentages of international recommendations, were 87 +/- 14, 223 +/- 42, 73 +/- 12, 110 +/- 27, 55 +/- 31, 129 +/- 51 and 111 +/- 26%, respectively. The relative distribution of calories was 15 +/- 2% from proteins, 48 +/- 5% from carbohydrates and 37 +/- 5% from lipids. Anthropometric indices, expressed as standard deviation score, were: weight -0.50 +/- 0.8, height -0.94 +/- 1.3, growth velocity -0.61 +/- 1.8, triceps skinfold thickness -0.30 +/- 0.6, subscapular skinfold thickness -0.19 +/- 0.8, mid-arm muscle circumference 0.38 +/- 0.3 and body mass index -0.22 +/- 1.0. Serum concentrations of albumin, total protein, transferrin, IgG, IgA, IgM, C3 and C4 and blood lymphocyte counts were within normal limits. The mean serum insulin-like growth factor-I concentration, expressed as standard deviation score, as 0.74 +/- 1.5. No anthropometric or biochemical signs of malnutrition were found in children with moderate CRF. However, their dietary intake of calories and carbohydrates was low and the protein and saturated fatty acid intake excessively high.

Adolescent↗
PubMed1994

Anticipation in myotonic dystrophy: a parental-sex-related phenomenon.

We report anticipation in an extensive sample of myotonic dystrophy (MyD) kindreds taken from an epidemiological survey recently conducted in Guipúzcoa, Spain. Analysis of the parent-child pairs ascertained showed a mean anticipation of 2.86 decades (range 0-6). Greater anticipation occurred when the transmissor parent was the mother. These results suggest a possible sex-related effect in the transmission of the MyD gene, and are in agreement with recent discoveries at the molecular level.

Adolescent↗
PubMed1993

[Clinical manifestations of myotonic dystrophy: epidemiologic survey].

BACKGROUND: The presence of a local aggregation of cases of myotonic dystrophy (MD) allows the evaluation of clinical symptoms of the disease in a sample in which the influence of a possible genetic heterogeneity is decreased. METHODS: The degree of global neuromuscular handicap and the incidence and severity of four of the most characteristic symptoms (cataracts, myotonia, muscular weakness and neuropsycologic disturbances) were studied in 183 patients with MD (146 typical adult forms, 19 neonatal, and 18 partial syndromes) in relation with the age of onset of the symptomatology or length of disease. RESULTS: Only 8.3% of the patients (excluding the neonatal forms) were severely handicapped, and the degree of neuromuscular handicap depended fundamentally on the age of onset of the disease. Cataracts and myotonia were present in 87 and 89% of the patients, respectively. Almost all the patients above the age of 40 presented cataracts. No clinical or subclinical evidence of neuromuscular involvement was present in 11% of the patients with MD. These patients principally corresponded to the group in whom the disease initiated over the age of 50. CONCLUSIONS: The age of onset of the symptomatology appears to be the determining factor to establish both the global prognosis of neuromuscular incapacity of patients with myotonic dystrophy and the explanation of the chronology of the appearance of the most characteristic symptoms of the disease. The presence of carriers without neuromuscular symptomatology is of note, this fact reinforcing the need to incorporate DNA examination in the evaluation of asymptomatic relatives or with exclusive ocular symptomatology.

Adolescent↗
PubMed1993

Molecular diagnosis of homozygous myotonic dystrophy in two asymptomatic sisters.

The genetic defect underlying myotonic dystrophy (DM) has been identified as the expansion of an unstable trinucleotide repeat sequence, and this discovery has led to new approaches to diagnosis and genetic counselling in families with the disorder. We report the genetic analysis of a consanguineous DM family in which two asymptomatic sisters had been shown to be homozygous for the 'at risk' haplotype. PCR analysis of the region spanning the trinucleotide expansion demonstrated that both sisters possessed two alleles with repeat sizes normally seen in minimally affected patients. Extensive clinical examination failed to demonstrate any of the symptoms of DM in these women. The implications of this finding, both for understanding the disease mechanism, and for genetic counselling in such situations are discussed.

Adolescent↗
PubMed1993

Prevalence of myotonic dystrophy in Guipúzcoa (Basque Country, Spain).

Prevalence figures for inherited neuromuscular disorders are important both for health care planning purposes and for evaluating the need for DNA diagnostic services for eugenic approaches. We screened for the prevalence of myotonic dystrophy (MyD) through extensive inquiry of neurologic and primary health services of Guipúzcoa (Basque Country, northern Spain) between 1989 and 1991. Typical adult-onset and neonatal cases and relatives at risk; suffering from a partial syndrome, were included. In the latter, molecular typing was performed with DNA probes close to the MyD gene to demonstrate the MyD gene carrier status. The high prevalence detected (26.5 cases per 100,000 population) could be explained by methodological factors, but intrinsic factors, such as a possible founder genetic effect or the quick growth of the Guipúzcoa population since the last century may contribute to one of the highest MyD prevalence in the world. In the future, the methodological basis for epidemiologic surveys of MyD must combine molecular technology with more-extensive family inquiries.

Humans↗
PubMed1992

Linkage disequilibrium detected between myotonic dystrophy and the anonymous marker D19S63 in the Spanish population.

We used the following polymorphic markers: APOC2 (BanI, BglI, TaqI), CKMM (NcoI, TaqI), and D19S63 (PstI) to haplotype 33 Spanish myotonic dystrophy (DM) families. We analysed the allele and haplotype frequencies of our sample, and the possible association of alleles or haplotypes with the disease. We found a slight linkage disequilibrium between APOC2 (BanI) and DM, but no disequilibrium when using all other APOC2 and CKMM RFLPs; this agrees with data previously reported. In addition, we found a very strong linkage disequilibrium when using D19S63 (PstI), the + allele being associated with the DM locus. This disequilibrium in the Spanish population indicates that D19S63 is very close to the DM locus.

Alleles↗
PubMed1992

Expansion of the myotonic dystrophy gene in Italian and Spanish patients.

Myotonic dystrophy results from expansion of a (CTG)n repeat at the 3' untranslated region of the myotonin-protein kinase gene. We show here the genomic analysis of 322 symptomatic patients with the cDNA-25 probe detecting disease specific EcoRI restriction fragments. The expansion was found in the majority of Italian and Spanish patients (92%). The implications of these results for the detection of symptomatic patients in southern Europe are discussed.

Adult↗