PubMed Health⌕ Search

Biomedical subjects

M Fernandez

Publications and source records attributed to M Fernandez.

At least 127 records · Page 7Linked to original sources
PubMed1994

Biodegradable estradiol microspheres do not affect uterine involution or characteristics of postpartum estrus in mares.

Quarterhorse mares were used to investigate effects of estradiol-17beta on uterine involution, duration of estrus, interval to ovulation, and fertility achieved by breeding on the first postpartum estrus. On the day of foaling, mares were injected with biodegradable poly (DL-lactide) microspheres containing either 100 mg estradiol-17beta (25 mares) or no drug (27 mares). The treatment period was considered to last for 12 to 15 d. Estrus was determined by teasing mares (n=16) with a stallion. Ovulation was detected by transrectal ultrasonographic examination of ovaries (n=48). On Days 6, 11 and 16 post partum, transrectal ultrasonography was used to measure cross-sectional diameters of the uterine body, uterine horns, and fluid within the uterine lumen (n=28). Uteri were swabbed for bacteriologic culture, and uterine biopsies were obtained from the previously gravid uterine horn on Days 11 and 16 post partum, for assessment of endometritis and morphometric analysis of endometrial histioarchitecture (n=19). Twenty-two mares were bred on foal-heat, and pregnancy was determined by transrectal ultrasonography on 14 to 16 and 30 to 35 d after breeding. With only one exception (diameter of previously gravid uterine horn on Day 11), mean values for all measures of uterine involution did not differ between treatment groups (P > 0.05). No differences were detected between treatment group means for length of estrus or interval to ovulation (P > 0.05). No differences were detected between treatment group liklihoods for recovery of potential bacterial pathogens, presence of endometritis, or presence of intrauterine fluid at 11 or 16 d post partum (P > 0.05). Pregnancy rate of mares treated with estradiol (5 11 ; 45%) was not different from that of control mares (9 11 ; 82%; P > 0.05). Estradiol treatment did not hasten uterine involution, increase duration of estrus, delay ovulation, or increase fertility in these postpartum mares.

Journal Article↗
PubMed1994

Cooperative binding of heat shock transcription factor to the Hsp70 promoter in vivo and in vitro.

The minimal promoter of the Drosophila hsp70 gene contains a TATA box and two nonidentical HSE sequences, HSEI and HSEII, that synergistically activate the promoter. We have examined stereospecific alignment and spatial constraints in this promoter. Similar to deletion of HSEII, insertion in the spacer between the HSEs of 1 to 5 or 11 to 14 nucleotides (nt) reduced promoter activity to about 10%. In contrast, HSEII was capable of contributing to promoter activity when the spacer was either shortened by 2 or 4 nt or extended by 6 to 10 or 16 or 18 nt. Hence, half of the possible helical arrangements of HSEs are compatible, whereas the other half are essentially incompatible with efficient promoter function. HSEII was ineffective when its distance to HSEI was increased by more than 18 nt. In vitro, HSEII is a weak and HSEI a strong binding site for heat shock transcription factor HSF, and HSF binds to HSEII cooperatively. To find out whether the above periodicity reflects cooperative binding of HSF in vivo or represents the need of stereoalignment for synergistic activation of transcription, the weak HSF binding site HSEII was replaced with the strong binding site HSEI. This substitution greatly attenuated promoter periodicity, suggesting that the periodic effects are caused by cooperative binding of HSF to HSEII, and that stereoalignment of HSEs is not required for transcription activation. In agreement, in vitro assays using spacer mutants revealed cooperative binding of purified, recombinant HSF to HSEII with a similar periodicity as observed in vivo. Changing the distance between TATA and the HSEs did not produce promoter periodicity, indicating that stereoalignment of these elements is not important.

Animals↗
PubMed1994

Discrimination between and among schizophrenics and other pathologies using a Spanish version of the Whitaker Index of Schizophrenic Thinking.

A Spanish version of Forms A and B of the Whitaker Index of Schizophrenic Thinking (WIST) was administered to two sets of subjects. In the first study, the WIST was administered to 147 subjects of both sexes grouped into one of six categories: acute paranoid schizophrenic, acute nonparanoid schizophrenic, chronic paranoid schizophrenic, chronic nonparanoid schizophrenic, normal, and university student. Results revealed significant group differences; schizophrenics scored significantly higher. Further, chronic schizophrenics, regardless of the existence of paranoia, scored higher than acute subjects. In the second study, a heterogenous group of schizophrenics was compared to heroin addicts and depressed subjects (total N = 93). Significant group differences again were noted; the schizophrenics scored higher than the two other clinical samples.

Adult↗
PubMed1994

Effects of light on the cytotoxicity and genotoxicity of benzo(a)pyrene and an oil refinery effluent in the newt.

The genotoxicity and/or toxicity of benzo(a)pyrene (BaP) were evaluated under different lighting conditions in larvae and embryos of the newt Pleurodeles waltl. Visible light alone (1,220 lx; 2.1 mW/cm2), UVA alone (250 microW/cm2), or BaP alone (500, 50, 25, 12.5 ppb) had no toxic effects on the larvae. Conversely, toxic effects were observed in animals exposed to BaP (500 ppb)+daylight, or BaP (> or = 25 ppb)+UVA. BaP solutions (50 or 12.5 ppb) were irradiated for 24 hr (Irr BaP) prior to being assayed in the dark. The genotoxicity of BaP (50 ppb) as evaluated in the micronucleus test (on day 8) was halved by its previous exposure to UVA, and was abolished at the lowest concentration (12.5 ppb). In other experiments, the larvae were exposed alternatively to BaP or Irr BaP (18 hr in the dark) and UVA (6 hr in water), every day for 8 days. All animals that had accumulated non-irradiated BaP (50 ppb) showed signs of severe toxicity, and 90% died before the end of the test. On the other hand, irradiated BaP (50 ppb) was 4-fold less toxic and half as genotoxic as non-irradiated BaP. In addition, exposure of the animals to UVA alone for 4 days prior to treatment with BaP did not affect the genotoxicity or toxicity of this hydrocarbon. In the dark, the embryotoxicity of BaP was markedly attenuated by the presence of the jelly coats (10% vs. 24%). With dejellied embryos, comparable mortality (24%) was observed after exposure to 25 ppb BaP for 54 or 312 hr. Although UVA alone did not affect growth of the embryos, the toxicity of BaP was enhanced by the combined action of the two agents together or in succession (BaP+UVA or BaP then UVA). Larvae were treated with an oil refinery effluent (EF). At the concentration employed (125 ml/l), EF was not found to be genotoxic in the dark. However, in animals exposed to both EF and UVA, there was a progressive increase in level of micronucleated erythrocytes with increasing duration of daily exposure to UVA (9, 15, 24 hr). Moreover, the genotoxic potential of irradiated EF+UVA was systematically below that of non-irradiated EF+UVA for all durations of exposure to ultraviolet light. Irradiation of this type of effluent might help reduce its harmful effects on aquatic species. Our results also suggest that metabolic activation is not necessary for hydrocarbons to induce toxic effects.

Animals↗
PubMed1994

Green bean hypersensitivity: an occupational allergy in a homemaker.

As a member of the legume family, the green bean is frequently associated with food allergy. However, allergic reactions caused by skin contact or by inhalation of vapors from boiling legumes are rare. This article presents a case of occupational asthma in a homemaker; symptoms occurred during preparation and cooking of raw green beans. Skin prick, rub, and bronchial provocation tests were performed on the patient. In vitro tests were done with the serum samples of the patient and 10 control subjects (5 atopic and 5 nonatopic). Test results indicate that the patient has type I hypersensitivity to raw green bean antigen(s). This case is of interest because it demonstrates that a food allergen, when inhaled, can induce respiratory symptoms in sensitized patients and may even be the source of primary sensitization.

Adult↗
PubMed1994

Stallion karyotype variability and lack of association with abortion: a case report.

Karyotype analysis was done on a stallion that impregnated 23 mares during the 1991 breeding season, of which 14 aborted between 2 and 4 mo fo gestation. Lymphocytes examined contained a 64,XY complement of normal appearing sex chromosomes and autosomes, except for slight dimorphism of the centric heterochromatin of chromosome No. 1. A skin biopsy was procured form the stallion for karyotype analysis, and the stallion was bred to 11 mares. Three mares were detected pregnant 16, 35, 45 d after breeding. The fetuses were recovered transcervically using curved intestinal forceps 47 (n=2) and 49 (n=1) d after breeding. Fetal tissue was rinsed and packed in culture media, transported overnight in a chilled container, cultured by standard tissue culture techniques, and prepared for karyotype analysis. No abnormalities were found in standard karyotypes from those cultures. One fetal karyotype revealed slight dimorphism of the heterochromatin of chromosome No. 1. Chromosome spreads obtained from the stallion's skin biopsy revealed a normal karyotype with no difference in the amount of heterochromatin present in No. 1 chromosomes. During the 1992 breeding season, the stallion impregnated 23 of 25 mares bred. Only 1 mare aborted, at 8 mo of gestation. Apparently, the amount of heterochromatin of No. 1 horse chromosomes can vary, and caution should be used in diagnosing this as a cause of pregnancy failure.

Journal Article↗
PubMed1994

Triiodothyronine induces the expression of the uncoupling protein in long term fetal rat brown adipocyte primary cultures: role of nuclear thyroid hormone receptor expression.

Fetal rat brown adipocytes at the beginning of culture showed a minimal T3 nuclear binding capacity and very low expression of the c-erbA genes, with low steady state levels of the mRNA forms beta-type and 5.5- and 2.6-kilobase (kb) alpha-types. The levels of these mRNA species increased after 7 days in culture in the presence of thyroid hormone-depleted serum; however, no significant increase in nuclear T3-binding capacity was observed. The addition of T3 incremented the abundance of the c-erbA beta-mRNA, induced the appearance of the 6.6-kb c-erbA alpha-mRNA and increased the nuclear T3-binding capacity by 30-fold. Parallel analysis of the uncoupling protein (UCP) mRNA, immunoreactive UCP, and functional UCP (detected by its ability to bind GDP) demonstrated that T3 induced the expression of the UCP gene in long term treated fetal brown adipocytes in culture. The presence of noradrenaline, a positive control for UCP expression, increased only the level of expression of the 5.5-kb c-erbA alpha-mRNA, but values for nuclear T3-binding capacity similar to those obtained in T3-treated cells were observed. Simultaneous addition of both hormones gave a pattern of expression of the c-erbA-mRNA forms similar to those obtained with these agents individually, and no further increment in their separate effects was observed on the nuclear T3-binding capacity and UCP expression.

Adipose Tissue, Brown↗
PubMed1993

Structure/activity relationships in porphobilinogen oxygenase and horseradish peroxidase. An analysis using synthetic hemins.

The apo-enzymes of porphobilinogen oxygenase and horseradish peroxidase were reconstituted with hemin IX, deuterohemin IX, 2,4-diacetyldeuterohemin IX, 2-vinyl-4-deuterohemin IX and hemin I. The apoproteins did not reconstitute with the dimethyl or diethyl esters of hemin IX. The native enzymes and the synthetic hemoproteins showed similar oxygenase activities toward porphobilinogen in the presence of dithionite and oxygen. They also showed peroxidase activity in the presence of H2O2, which was affected by the side-chain substitution pattern of the hemes. Oxygenase activities, however, were not affected by the heme structure. Iron chelators completely inhibited the oxygenase, but not the peroxidase activities. The EPR spectra of the native and synthetic porphobilinogen oxygenase showed that dithionite reduction produced a rapid disappearance of the high-spin heme-iron signal at g = 6.0. It reappeared 1 min later but the enzyme retained its catalytic activity. The changes in the EPR spectra could be correlated with the biphasic kinetics of the oxygenase reaction which was very fast during the first minute and then decreased to a half-value rate. The oxygenase reaction was inhibited by addition of superoxide dismutase during the fast rate phase, but not during the slower phase. These results could be explained by the formation of a superoxide anion during the first minute of the oxygenase reaction, after which a protein-stabilized radical (g = 2.0) is generated (very likely a tyrosyl radical). The latter then oxidizes the substrate porphobilinogen and facilitates its reaction with O2 to give oxopyrrolenines.

Animals↗
PubMed1993

Transcriptional regulation of the isocitrate lyase encoding gene in Saccharomyces cerevisiae.

In this work, we studied the transcriptional regulation of isocitrate lyase synthesis. In Northern blot analyses we first showed that the steady-state ICL1 mRNA levels depend on the carbon source used for growth. In addition, we determined the kinetics of transcriptional repression upon a shift of ethanol-grown cells to glucose and of the induction when cells were transferred from glucose to ethanol. By deletion analyses as well as by studying the influence on expression of different fragments cloned into the heterologous CYC1 promoter lacking its own UAS sequences, we defined UAS and URS elements in the ICL1 promoter. A region mediating the control by CAT3, a gene also involved in the control of expression of other genes subject to carbon catabolite repression, was found to overlap with one of these UAS elements.

Base Sequence↗
PubMed1993

In vivo detection of waste water and industrial effluent genotoxicity: use of the Newt Micronucleus Test (Jaylet Test).

The genotoxic potential of various waste waters has been evaluated in a micronucleus test using amphibian larvae. Genotoxicity was detected after dilution, in waste water from tanneries and from various petrochemical industries. Further studies have shown that sample treatment used for in vitro testing may affect the genotoxic response. Sterilization by gamma irradiation lowered genotoxic activity. Furthermore, microfiltration of effluent and extraction of organic micropollutants on XAD-4 resins, lead to the preparation of extracts which are not fully representative of the initial water sample. Testing of concentrates, as required for in vitro studies, will limit the scope of a survey to that part of the organic matter that can be recovered by concentration techniques. Many of the problems encountered in in vitro genotoxicity studies of waters, may be circumvented with direct testing on aquatic organisms. Thus, there is no need to concentrate or sterilise a sample. The tests can be carried out with intact animals, thus taking into account uptake and elimination, internal transport and metabolism. Finally, in vivo test-systems, such as the Newt Micronucleus Test, are more relevant to eukaryotes than bacterial assays and are suitable to assess the real impact of genotoxins discharged in the aquatic environment.

Animals↗
PubMed1993

Amygdala kindling rate is altered in rats with a deficit in the responsiveness of the hypothalamo-pituitary-adrenal axis.

Fisher and Lewis rats were amygdala kindled in the morning and in the evening. Fisher rats displayed a diurnal variation in the rate of kindling through stage 2 which did not exist in the Lewis rats. Lewis rats also take much longer to kindle through stage 2 and a subcutaneous corticosterone pellet accelerates this rate. These observations are consistent with the hypothesis that the hormones of the hypothalamo-pituitary-adrenal (HPA) axis, particularly the glucocorticoids, play a role in epileptogenesis.

Amygdala↗
PubMed1993

The effect of adrenalectomy on the circadian variation in the rate of kindled seizure development.

The hypothalamic-pituitary adrenal axis (HPAA) is activated during kindled seizures and the circadian changes in this axis may contribute to the circadian variation in the kindling rate. Changes in the rate of seizure development were examined in rats that were amygdala kindled in the a.m., at midday and in the p.m.. Sham operated control groups were compared to adrenalectomized groups. Adrenalectomy had no effect on the midday rate but abolished the normal circadian variation by accelerating the rate in the a.m. and decreasing the rate in the p.m.. These results suggest a complicated relationship of kindled seizure rate to the hormones of the HPAA axis.

Adrenalectomy↗
PubMed1993

Two structural genes are encoding malate synthase isoenzymes in Saccharomyces cerevisiae.

We report on the isolation of a gene encoding yeast malate synthase. A yeast genomic library was screened using a probe homologous to the yeast enzyme obtained by the polymerase chain reaction. The nucleotide sequence of the cloned gene was determined. Computer analysis showed that the isolated gene is identical to the one previously described as DAL7, which is involved in allantoin metabolism [Mol. Cel. Biol. 9 (1989) 3231-3243]. Enzymatic activities of multicopy transformants, Southern analysis and disruption mutants predict the existence of two genes encoding malate synthases that are differentially regulated at the transcriptional level.

Amino Acid Sequence↗
PubMed1993

Antagonism of Pseudomonas cepacia against phytopathogenic fungi.

Two strains of Pseudomonas cepacia, RJ3 and ATCC 52796, have been identified as potential antagonists of fungal plant pathogens. We have compared the antagonistic activity of these two strains against various fungal pathogens. Although both strains displayed high levels of antagonism, ATCC 52796 was slightly more antagonistic than RJ3. The antagonist from RJ3 has been identified as the antifungal compound pyrrolnitrin after purification by HPLC and characterization by UV, IR, NMR, and mass spectroscopy. Both strains also antagonized the fungi by production of volatile compound(s), which have not yet been identified. Both strains are similar with respect to in vitro antagonism, mechanism of antagonism, and sensitivity to antibiotics.

Antibiosis↗
PubMed1993

Amphibian micronucleus test(s): a simple and reliable method for evaluating in vivo genotoxic effects of freshwater pollutants and radiations. Initial assessment.

A micronucleus test was developed using larvae from two urodele amphibians (Pleurodeles waltl and Ambystoma mexicanum) and an anuran (Xenopus laevis). The methods for maintenance of adults, egg laying, and rearing the larvae are described, and the conditions required for optimal response are given for each of these species. The tests are carried out during a period of intense erythropoiesis when red blood cells are actively dividing in circulating blood. The micronuclei are observed on blood smears. The genotoxic effects of X-rays were evaluated at 12 different doses over a range of 6-1200 rad. All doses, even the very low dose of 6 rad, gave positive results. The test substances were added to the water in which the larvae were reared, and the results obtained after treatment for 12 days and/or 8 days with 47 different chemical compounds are listed. Detailed results are given as the lowest concentration producing a positive response or the highest concentration producing a negative response. The reliability of the test system using the newt is now well established, while the tests using the other two amphibian species are still under evaluation. Integration of this test in a test battery for quality control of water would aid the evaluation of risks to human health, as well as the protection of aquatic ecosystems.

Ambystoma mexicanum↗
PubMed1993

Kinevac-assisted cholescintigraphy as an accurate predictor of chronic acalculus gallbladder disease and the likelihood of symptom relief with cholecystectomy.

Thirty patients with chronic upper abdominal pain and no evidence of cholelithiasis were entered into this study. All had negative ultrasonography of the gallbladder, and most had a host of other negative investigations. These patients were referred to a surgeon to evaluate the possibility of atypical biliary colic associated with chronic acalculous cholecystitis. All patients underwent cholecystokinin-stimulated cholescintigraphy and were offered cholecystectomy if the ejection fraction was less than 35 per cent. Of the 30 patients, 27 (90%) had pathologically abnormal gallbladders. Follow-up averaged over 1 year (13.2 mo), and relief of symptoms occurred in 28 (94%). The authors conclude that in appropriately selected patients with symptoms of biliary colic (typical or atypical) and no evidence of cholelithiasis, a cholecystokinin-stimulated cholescintigram is a significant help in predicting not only which patients have gallbladder disease, but also how likely cholecystectomy is to result in an improvement in their symptoms.

Adolescent↗