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Biomedical subjects

L Izquierdo

Publications and source records attributed to L Izquierdo.

At least 19 recordsLinked to original sources
PubMed1995

DNA-based prenatal diagnosis of generalized recessive dystrophic epidermolysis bullosa in six pregnancies at risk for recurrence.

Linkage analyses in generalized recessive dystrophic epidermolysis bullosa (RDEB) have implicated the type VII collagen gene (COL7A1), which encodes the major component of anchoring fibrils, and recent identification of COL7A1 mutations has provided direct evidence for COL7A1 defects underlying RDEB. In this study, COL7A1 gene analysis was used to successfully perform first-trimester prenatal diagnosis in six families at risk for recurrence of the disease. In four families, three affected with the most severe variant of RDEB (the Hallopeau-Siemens form, HS-RDEB) and one with generalized nonmutilating RDEB, prenatal diagnosis was established by linkage analysis using polymerase chain reaction-based detection of PvuII and AluI intragenic restriction fragment length polymorphism. In two other HS-RDEB families, prenatal diagnosis was carried out by direct detection of mutations in COL7A1, using denaturing gradient gel electrophoresis analysis of polymerase chain reaction-amplified genomic fragments. Analysis of fetal DNA from chorionic villus biopsy or from amniotic fluid cells showed that the fetus had inherited at least one normal COL7A1 allele in all cases. Therefore, the fetus was predicted to be unaffected in the six pregnancies, and this has been confirmed in the newborn infants. Genotype analysis with COL7A1 polymorphic markers, or direct COL7A1 mutation detection in families at risk for the disease, represent early and rapid diagnostic alternatives to second-trimester evaluation of fetal skin samples, and thus offer a major advance in prenatal diagnosis of this life-threatening form of epidermolysis bullosa.

Base Sequence↗
PubMed1994

Experimental model of graft vs. host disease in non-immunosuppressed F1 (CBA/J x C57BL/6) mice.

The experimental model of graft vs. host disease (GvHD) has a potential use in the evaluation of different manipulation procedures of the immune system applicable to development of vaccines. In the present study an experimental model of GvHD in F1 (CBA/J x C57BL/6) mice by means of the parenteral inoculation of spleen lymphoid cells from parental male CBA/J to 10-day-old animals (experimental group) was developed. Animals inoculated with Medium 199 (n = 42) (Medium 199 group), or with splenic lymphoid cells either from the hybrids (n = 16) (F1 group), or from mice of the inbred strain Balb/c (n = 10) (Balb/c group) were used as controls. In all groups body and spleen weights, relative spleen index (RSI), and spleen index (SI) were determined. Additionally, histopathologic and morphometric studies were done in the spleens of the animals studied. Significant increases in body and spleen weights, RSI, and lymphocytic perimeter and area were associated with distinctive splenic GvHD lesions found in the experimental group. The experimental SI value was higher than twice the SI value of any of the control groups. We conclude that ours is a useful model of GvHD with many potential applications in the field of vaccine production.

Animals↗
PubMed1994

Sequential study of an experimental model of graft vs. host disease (GvHD) in non-immunosuppressed F1 (CBA/J x C57BL/6) mice.

In order to determine the optimal day for the evaluation of an experimental model of GvHD in F1 mice and the histopathologic evolution of the lesions in different organs, we studied 10-day-old F1 (CBA/J x C57BL/6) mice inoculated with splenic lymphoid cells of the male parental CBA/J strain (n = 42) that were sacrificed between 1 and 14 days postinoculation. The evolution of the relative spleen index (RSI) and the histopathologic lesions in different organs were also determined. F1 mice inoculated with Medium 199 were used as controls. Significant RSI increases (p < 0.0001) were found in the experimental group between 2 and 14 days postinoculation, with a peak at the eighth day, associated with the most severe histopathologic lesions in the organs studied. We suggest the eighth day as the optimal time for evaluation of this experimental model.

Animals↗
PubMed1994

Histopathologic and humoral study of Balb/c mice inoculated with BCG by different routes.

With the aim of determining the distribution and humoral immunogenicity of the bacillus Calmette-Guérin (BCG) administered by the oral (O), intravenous (IV) and subcutaneous (SC) routes, we studied 54 male Balb/c mice weighing 17-22 g that had been inoculated with BCG (10(6) CFU) by the O (n = 18), IV (n = 18) and SC (n = 18) routes. At weekly intervals we determined the distribution of the microorganism using histopathological techniques including Ziehl-Neelsen staining. Serum samples of the same animals were analyzed by ELISA and Western blot to determine the antibody response to the microorganism. In all groups, distinctive histopathologic lesions harboring the microorganism were found. Using the SC route the lesions were located at the inoculation site, whereas there was systemic dissemination with the O and IV routes, being more prominent with the latter. Anti-BCG antibodies were detected by ELISA in all groups; this response was more intense in the IV group, followed by the SC and O groups. In the Western blot analysis, reactivity against multiple bands and the predominant recognition of a 65 kd band in all groups was observed.

Administration, Oral↗
PubMed1992

Evidence for genetic heterogeneity in hereditary hydronephrosis caused by pelvi-ureteric junction obstruction, with one locus assigned to chromosome 6p.

Hereditary hydronephrosis (MIM 143400) is an autosomal dominant trait that causes unilateral or bilateral pelvi-ureteric junction (PUJ) obstruction. Linkage analysis was undertaken in 5 families with hereditary PUJ obstruction using the major histocompatibility complex locus as a test marker. The data as a whole supported a hereditary hydronephrosis locus on 6p. Maximal lod scores were 3.090 at a recombination fraction of 0.1 with full penetrance, and 2.486 at a recombination fraction of 0.1 with a penetrance of 90%. However, analysis of two point lod scores using the HOMOG program revealed significant evidence for genetic heterogeneity with one locus on 6p in 4 of the families, and a different locus in one family. After exclusion of this unlinked family, two point analysis gave a maximal lod score of 3.9 at a recombination fraction of 0.05 with full penetrance, and 4.2 at a recombination fraction of 0.0 with 90% penetrance. These data support the assignment of one of the loci for hereditary hydronephrosis to chromosome 6p.

Chromosomes, Human, Pair 6↗
PubMed1992

Short-acting beta-adrenergic blockade and the fetus. A case report.

An infant was born to a woman who received intravenous esmolol for intrapartum supraventricular tachyarrhythmia. Despite the very short acting and cardio-selective beta-1 adrenergic blockade induced by that agent, neonatal effects can occur up to 48 hours after delivery.

Adrenergic beta-Antagonists↗
PubMed1991

Genuine hereditary hydronephrosis in a three-generation family. Clinicopathological and genetic implications with a review of the literature.

The clinical features and management of genuine hereditary hydronephrosis (GHH) in 4 members of the same family are presented. Genealogical studies provide evidence of a dominant autosomal inheritance with complete penetrance. All affected members of the family had inherited the same HLA haplotype through the male line. This finding, added to those from previous association studies with histocompatibility typing (in 3 families), lends support to the localization of the GHH gene/s in the 6p human chromosome. Based on our findings from the present familial study and on a review of the literature, we suggest that all first-degree relatives of children or adults with genuine hydronephrosis should be screened by ultrasound. Such a prospective screening, including fetal echography, will lead to earlier diagnosis and treatment of asymptomatic cases and, moreover, will identify GHH cases for possible genetic counseling with regard to the empiric recurrence risk.

Adult↗
PubMed1990

Vaginal ultrasonographic assessment of cervical length changes during normal pregnancy.

We measured the cervical length of 166 normal, gravid patients between 8 and 37 weeks' gestation by vaginal ultrasonography. Patients were assigned to one of five groups according to gestational age at the time of the measurements. Cervical length was longest (48 mm) in group 3 (20 to 25 weeks) and significantly longer than that of groups 1 (8 to 13 weeks), 2 (14 to 19 weeks), and 5 (32 to 37 weeks). The use of vaginal ultrasonography to assess cervical length eliminates some technical problems encountered with abdominal ultrasonography. Nomogram of cervical length throughout pregnancy was established. This may aid in early diagnosis and management of preterm labor and cervical incompetence.

Cervix Uteri↗
PubMed1990

Effect of cell contact on regionalization of mouse embryos.

Cytochemical demonstrations of 5'-nucleotidase and alkaline phosphatase reveal the activity of these enzymes on regions of cell apposition from the late four-cell stage onward. These enzyme activities also appear on regions of artificial cell contact between aggregated embryos having more than four cells. Cytochemistry of single two-cell embryos does not reveal 5'-nucleotidase nor alkaline phosphatase activity, however, these enzyme activities appear at both the artificial and natural contacts in chimaeras of two two-cell embryos. We interpret these results as meaning: (1) that cell contact causes the regionalization of 5'-nucleotidase and alkaline phosphatase activity on the cell surface, (2) that these enzyme activities can be induced or enhanced by contact between two two-cell embryos, (3) that a signal is transmitted from the artificial to the natural contact.

5'-Nucleotidase↗
PubMed1988

C18 solid-phase isolation and high-performance liquid chromatography/ultraviolet diode array determination of fully methoxylated flavones in citrus juices.

A new analytical methodology for the determination of fully methoxylated flavones (FMFs) in citrus juices is described. Isolation of the FMFs is carried out by percolation of 30 mL of clarified citrus juice (to which tetramethyl-o-kaempferol is previously added as internal standard) through a C18 Sep-Pak cartridge, washing with 3 mL of water followed by 5 mL of water/acetonitrile (3:1), and selective elution of the retained FMFs with 5 mL of water/acetonitrile (9:11). Determination of the isolated FMFs is carried out by reversed-phase high-performance liquid chromatography (HPLC) and UV diode array detection (DAD). Signals at wavelengths 320, 335, and 345 nm (bandwidth 4 nm) are simultaneously acquired, stored, plotted, and integrated. The column used is a microbore (200 x 2.1-mm) Hypersil ODS 5 microns. Elution is in gradient mode, using a ternary mobile phase (water/acetonitrile/tetrahydrofuran). Column temperature is 40 degrees C. Recovery yields are nearly 100% for all the FMFs detected and identified: isosinensetin, hexamethyl-o-gossypetin, sinensetin, tetramethyl-o-isoscutellarein, hexamethyl-o-quercetagetin, nobiletin, tetramethyl-o-scutellarein, heptamethoxyflavone, and tangeretin. Chromatographic separation of the FMFs is extremely dependent upon the minor changes of the mobile phase composition and percentages, gradient rate, and temperature. The UV spectra (230 to 400 nm) of the FMFs obtained under chromatographic conditions are given. The FMFs relative response factors at 320, 335, and 345 nm and their concentrations in hand-squeezed and commercial concentrated orange and mandarin juices are tabulated. The FMF concentration differences found among samples are discussed.

Beverages↗
PubMed1984

Plasma membrane regionalization and compaction of mouse cleaving embryos: effect of microtubule and microfilament inhibitors.

Two-cell embryos were incubated during 44 h in media containing either microtubule or microfilament inhibitors. The lowest doses that inhibit cleavage were found to be 0.5 micrograms/ml for colchicine and colcemid, 5 micrograms/ml for cytochalasin B and 0.5 micrograms/ml for cytochalasin D. After incubation with the minimal doses of these drugs, embryos were either fixed immediately or transferred to fresh media without drugs and cultured for different times before fixation. Then, embryos were processed for scanning electron microscopy. Following incubation with microtubule inhibitors, less than 10% of the embryos were compacted and about 20% became so in fresh medium. Regionalization was revealed by the cytochemical demonstration of alkaline phosphatase or 5'-nucleotidase on the apposing surfaces of blastomeres in 50% of the embryos, including all those that were compacted. By scanning microscopy microvilli were seen evenly distributed on the embryo surface, as they are observed in normal 2-cell embryos. Following incubation with microfilament inhibitors, few embryos were compacted and about 90% compacted within 4 h in fresh medium. Alkaline phosphatase activity was detected between blastomeres in all compacted embryos and in one half of those still uncompacted. Scanning microscopy showed patches of microvilli on the outer surface which had become otherwise smooth. During incubation in fresh medium, microvilli concentrated in two large patches placed at the antipodes of the embryo. From these results we conclude that cytokineses is not required for cell membrane regionalization, that blastomeres regionalize before they compact, that microtubule and microfilament inhibitors affect differently the array of microvilli on the external surface of arrested embryos.

5'-Nucleotidase↗
PubMed1983

Nitrate and nitrite contents in Cuban cheese of the Gouda type.

The nitrate and nitrite contents in cheese of the Gouda type, produced by the Milk Complex of Havanna, were investigated and compared with those found in 5 types of imported cheese consumed in Cuba. No significant differences were found in the mean value (mean) of NaNO3, whereas in the mean value (mean) of NaNO2 differences were found when comparing all cheeses against each other. From these results it is inferred that the consumption of Gouda type cheese does not represent an important contribution to the daily intake of nitrates and nitrites, precursors in the synthesis of cancerogenic N-nitroso compounds.

Cheese↗
PubMed1983

Effect of LiCl on differentiation of mouse embryos beyond the blastocyst stage.

In order to test the effect of Li+ on cell differentiation, 2-cell embryos were cultured in vitro with or without Li+ to the blastocyst stage and then, in a "implantation" culture medium, with or without Li+, up the early egg-cylinder stage. Our results show: 1) that Li+ in the preimplantation medium diminishes "implantation" success significantly; 2) that trophoblastic vesicles, produced by culturing preimplantation embryos with Li+, do not generate an inner cell mass when further cultured in "implantation" medium; 3) that the ultrastructure of "implanted" embryos is similar in all experimental series.

Animals↗
PubMed1982

Electron microscope observations on preimplantation mouse embryos cultured with LiCl.

We have recently shown that LiCl in the culture medium retards cleavage of mouse preimplantation embryos without delaying their blastulation and causes the formation of blastocysts with few large cells and a reduced or absent inner cell mass (Izquierdo and Becker 1982). In this study we compare the ultrastructure of major cellular organelles of Li+-treated and control embryos. No subcellular alterations were found that correlate with the altered morphology of the blastocysts. On the basis of these results we submit that the malformation of blastocysts developed in a Li+-containing medium is the morphogenetic consequence of a retardation of cleavage coupled with a normal timing in the establishment of zonular tight junctions around the peripheral cells of the morula.

Animals↗
PubMed1982

Cell membrane regionalization in early mouse embryos as demonstrated by 5'-nucleotidase activity.

The distribution of 5'-nucleotidase activity in pre-implantation mouse embryos is studied by means of a cytochemical method adapted from Uusitalo & Karnovsky (1977). The enzyme activity is detected, from the 4-cell stage up to the morula stage, on discrete patches of the cell membrane between blastomeres. Appropriate controls show that this distribution is not a localization artifact due to selective retention of the enzyme reaction product in the narrow interblastomeric spaces. In early blastocysts, as the blastocysts expands the enzyme activity on its lining disappears. The external surface of the trophectoderm in early blastocysts lacks any enzyme activity, whereas in late blastocysts a strong enzyme activity is detected at the embryonic trophectoderm, decreasing in intensity towards the opposite pole of the embryo. These results are compared to previous observations by other authors and the differences are mainly ascribed to differences in the cytochemical procedure employed. We conclude that during cleavage a gradual cell membrane regionalization unfolds, revealing a pattern that may be related to morphogenesis; in particular, to the localization of zonular tight junctions around the peripheral blastomeres of the morula (Izquierdo, 1977; Izquierdo, López & Marticorena, 1980).

5'-Nucleotidase↗