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Biomedical subjects

A Salinas

Publications and source records attributed to A Salinas.

At least 19 recordsLinked to original sources
PubMed2005

Ergosterol from Phytophthora drechsleri, a unusual metabolite of a member of this genus.

Ergosterol was isolated from the plant pathogenic pseudofungus Phytophthora drechsleri grown on clarified V8 booth (CV8-B). Its structure was confirmed by comparison to an authentic sample. The species was identified by morphological analysis and molecular characterization by PCR: ITS (Internal transcribed spaces). This is the first report of this sterol in Phytophthora. This result is unusual because Phytophthora fungi were previously thought to be unable to synthesize sterols and the Oomycetes in general do not produce ergosterol.

Culture Media↗
PubMed2005

Glucocorticoids and the development of agonistic behaviour during puberty in male golden hamsters.

During puberty, the agonistic behaviour of male golden hamsters undergoes a transition from play fighting to adult aggression. Repeated exposure to social stress early in puberty accelerates this transition. The present study investigated the possible role of glucocorticoids on the maturation of agonistic behaviour. First, we compared serum cortisol levels following a 20-min restraint stress during early puberty, mid-puberty or adulthood. Across puberty, animals exhibited a two-fold increase in post-restraint cortisol levels. We also compared corticotrophin-releasing hormone (CRH) immunoreactive fibres projecting to the median eminence between animals in early puberty and adulthood. The CRH fibre density was two-fold greater in adults compared to juveniles. Furthermore, we investigated the effects of stress hormones on the maturation of agonistic behaviour. Male hamsters were injected daily with dexamethasone, a corticosteroid receptor type II agonist (0, 10 or 40 microg/100 g), early in puberty from postnatal day 31 (P-31) to P-36. When paired with a smaller and younger intruder on P-37, attack frequency did not differ between groups. However, dexamethasone-treated animals showed a dose-dependent decrease in the percentage of play-fighting attacks and an increase in the percentage of adult attacks. In summary, puberty can be described as a period of increasing hypothalamic-pituitary-adrenal activity in male golden hamsters. Moreover, increasing glucocorticoid levels influence the maturation of agonistic behaviour. These data shed new light on the neuroendocrine mechanisms that regulate the maturation of social behaviours during puberty.

Aggression↗
PubMed2004

Behavioural and neuroendocrine adaptations to repeated stress during puberty in male golden hamsters.

In adult animals, the consequences of stress are often severe and long lasting. Repeated subjugation in adult male golden hamsters inhibits aggression and increases submissive and avoidant behaviours. By contrast, subjugation during puberty enhances offensive aggression. The goals of this study were to characterize behavioural and neuroendocrine responses of naïve and repeatedly subjugated juveniles to social defeat and to assess potential recovery from social stress. From the onset of puberty on postnatal day 28 (P28) to mid puberty (P42), animals were either socially subjugated or placed in a clean and empty cage for 20 min daily. The subjugated and control groups were further divided into subgroups and sacrificed under basal conditions or after social defeat on P28, P35 (early puberty), P45 (mid puberty) and P70 (early adulthood). On P35 and P45, repeatedly subjugated juveniles showed a complete inhibition of olfactory investigation (i.e. risk assessment) towards aggressive adults. Repeatedly subjugated also animals had lower postdefeat cortisol levels than controls on P45. Interestingly, basal cortisol levels increased gradually during puberty but did not differ between treatment groups at any point. Repeated subjugation was also associated with increased tyrosine hydroxylase immunoreactivity (ir-TH) within the extended medial amygdala. After a 4-week recovery period, none of these variables differed between subjugated and control groups. In an additional experiment, subjugated adults also had increased ir-TH in the medial extended amygdala, suggesting that these neurones are particularly responsive to social stress. In conclusion, puberty may be a developmental period characterized by behavioural and neuroendocrine plasticity in stress responsiveness. Furthermore, peri-pubertal changes in stress hormones may explain why juvenile hamsters are more resilient to social stress than adults.

Adaptation, Physiological↗
PubMed2001

First highly regio- and diastereoselective [3+2] cycloaddition of chiral nonracemic Fischer carbene complexes with azomethine ylides: an enantioselective synthesis of (+)-rolipram.

A new procedure for the synthesis of 1,3,4-trisubstituted and 1,4-disubstituted pyrrolidin-2-one derivatives in an enantioselective fashion is reported. The 1,3-dipolar cycloaddition of (+/-)-menthol and (-)-8-phenylmenthol derived Fischer alkoxy alkenyl carbene complexes with in situ generated functionalized azomethine ylides gives the corresponding cycloadducts as chelated tetracarbonyl Fischer carbene complexes. Only one regioisomer is detected in all cases, and the diastereoselectivity of the reaction is very high when (-)-8-phenylmenthol derived carbenes are employed. Oxidation and further transformation of the cycloadducts provide an easy access to pyrrolidin-2-ones. The anti-inflammatory and antidepressant drug (+)-Rolipram is readily prepared in four steps in a 20% overall yield by taking advantage of this newly developed methodology.

Antidepressive Agents↗
PubMed2000

Note on matrices of random numbers.

The statistical and structural characteristics of 13 matrices of random numbers in which both the cells and the entries were randomly chosen are discussed. Each matrix was explored considering row means, standard deviations, and correlations as well as column means, standard deviations, and correlations. A study concerning the sequential arrangement of digits was performed by finding out in tables of random numbers how many times the values 0 to 9 are followed by any other digit. Analyses indicate clear factor structures when factor analyzing correlations of rows and of columns and when examining sequential arrangements, concluding that for a given set of digits it is possible to assert both randomness and nonrandomness depending on how the data are examined.

Humans↗
PubMed1999

Serosurvey for selected disease agents in white-tailed deer from Mexico.

Serum samples from 350 white-tailed deer (Odocoileus virginianus texanus) collected in March 1994 from northeastern Mexico were tested for the prevalence of antibody activity against five infectious diseases of ruminants. The prevalence rate was 81% for bluetongue virus (BTV) of all serotypes, 72% for epizootic hemorrhagic disease virus (EHDV), 3% for Borrelia burgdorferi, 69% for Anaplasma marginale, and 0% for Brucella abortus, B. melitensis, and B. ovis. These are diseases that affect domestic ruminants, and deer may act as a reservoir of infection. In addition, if deer are translocated, they may introduce pathogens to formerly disease-free areas. The high seroprevalence of BTV and EHDV cannot be related to the presence of hemorrhagic disease in the deer in this region. This is the first report to indicate the presence of B. burgdorferi infection of deer in Mexico. Despite the high prevalence of A. marginale titers, it is uncertain that deer play a role in the epizootiology of cattle anaplasmosis in the region. Apparently, white-tailed deer are unimportant in the epizootiology of brucellosis of both cattle and goats in northeastern Mexico.

Anaplasma↗
PubMed1998

Human medial temporal lobe in aging: anatomical basis of memory preservation.

The integrity of the hippocampal formation is necessary for the correct function of declarative memory for facts and events. Normal aging is associated with a widespread decrease in cortical volume, including the hippocampal formation and related cortical areas, although in many cases, memory is only minimally impaired. In the present study, we quantified the extent of the parahippocampal gyrus (entorhinal cortex, as well as the medial temporal lobe proisocortical areas related to memory function, such as temporopolar cortex, perirhinal cortex, and posterior parahippocampal cortex) in 42 control cases. After detailed cytoarchitectonic analysis (based on homology with the nonhuman primate medial temporal lobe), planimetric measurement (calculated area) of a two-dimensional reconstruction of the parahippocampal gyrus was performed, and cases older than 70 years were compared with cases younger than 70 years. All areas showed atrophy with aging (average, entorhinal cortex, 5%; perirhinal cortex, 4%; posterior parahippocampal cortex, 15%; temporal pole, not assessable). Both entorhinal and posterior parahippocampal cortices reached statistical significance. Our results suggest that cortical areas relevant in memory function, and anatomically linked to the hippocampus, present a small degree of atrophy with aging, thereby permitting the reciprocal flow of information between the hippocampus and the cerebral cortex necessary for memory encoding and retrieval.

Age Factors↗
PubMed1998

Analysis of airborne radon in an ultra-low background experiment.

The contribution of 222Rn to the background in a low background experiment with a germanium detector has been estimated. We have also checked the efficacy of a standard radon cleaning system. The cleaning reduces the radon concentration two orders of magnitude with respect to the air in the laboratory. The residual 222Rn represents at most 12.5% of the background in the low energy region, a value low enough for the purpose of our experiment. A detailed study of the radioactive background is presented.

Air Pollutants, Radioactive↗
PubMed1997

Relationship between microstructure and ductility of investment cast ASTM F-75 implant alloy.

Hip replacement implants fabricated using the ASTM F-75 alloy sometimes fail in a sudden catastrophic way. In general, fractures start at microstructural defects subjected to stress-corrosion under chemical attack by body fluids. In this paper the results of a study on the effect of casting parameters on the microstructure of ASTM F-75 are presented. The preheating mold temperature and the liquid temperature were varied between 900 and 1000 degrees C, and 1410 and 1470 degrees C, respectively. Optimum static strength and ductility were obtained when shrinkage microporosity and the volume fraction of M23C6 "eutectic" carbides precipitated at grain boundaries were minimized by increasing the preheating mold temperature to 1000 degrees C and by using intermediate pouring temperatures of 1455 degrees C. Under these casting conditions, however, the solidification rates are low, leading to large grain sizes, which, in turn, reduce the strength of the material under dynamic loading conditions. The volume fraction of the M23C6 "blocky" carbides appears to be independent of the casting conditions; however, their size and spatial distributions determine the strength of the as-cast alloys.

Alloys↗
PubMed1994

[Kock's ileal reservoir: clinical course and current experience with 73 patients].

Between October 1985 and December 1993 a total of 73 patients underwent surgery for Kock's ileal reservoir (as continent urostomy in 23 patients, orthotopic vesical substitution in 36, ileo-anal reservoir in 8, and enterocystoplasty for vesical expansion [hemiKock] in 6). Overall post-operative mortality was 5.4% (3 cases in continent urostomy and 1 in pelvic-urethral reservoir). A total of 58 patients were controlled at medium and long term. In continent urostomy early complications represented 17.3%, similar to those in pelvic-urethral (16%). Late complications of continent stoma were 35% with 25% re-operations achieving complete continence in 70% of cases. In the pelvic-urethral procedure, late complications were 22.8% with 11.4% of re-operations with complete daytime continence in 82% of patients during the day and only 54% during the night. Best results for continence were obtained with the ileo-anal reservoir (functional rectosigmoid neo-bladder): 100% during the day and 87.5% during the night. Currently, a large number of patients can preserve urinary continence after radical pelvic surgery or in severe vesical dysfunctions with urinary incontinence which can not be solved using other alternatives.

Adult↗
PubMed1993

Chromatographic, immunochemical and electrophoretic studies of human uterotrophic placental factor (hUTPF).

The human uterotrophic placental factor (hUTPF) is a protein obtained from human term placentae and acts on uterine growth, mammary gland, and blastocyst development and implantation. In the present work, we further define some molecular characteristics of hUTPF using chromatographic, electrophoretic and immunochemical methods. It is concluded that in human term placenta a high molecular weight hUTPF is present, bound to albumin and immunoglobulins, which could represent a storage or transport form of this factor. hUTPF presents several molecular forms, one of them of 270 kDa and others of approximately 90 kDa and 27 kDa.

Animals↗
PubMed1992

Effect of a benzodiazepine derivate Ro 15-4513 on ethanol-free selection and CNS mitochondrial energetics in rats.

1) Females are higher EtOH drinkers than males in E.F.S. experiments in rats. 2) Ro 15-4513 inhibited intake of EtOH. 3) Hypothalamus mitochondrial energetics, studied at Sites I and II, showed Ro 15-4513 inhibition of these parameters at different doses by sex: effects were seen in females at 15 mg and in males at 10 mg/kg rat/24 h. An uncoupled effect between electron transport and ADP/O was found.

Alcohol Drinking↗