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P Pacheco

Publications and source records attributed to P Pacheco.

At least 19 recordsLinked to original sources
PubMed2006

Participation of estradiol and progesterone in the retrograde labeling of pubococcygeus motoneurons of the female rat.

Retrograde labeling with horseradish peroxidase conjugated to wheat germ agglutinin showed that the pubococcygeus muscles of the female rat are innervated by a population of motoneurons located in a column approximately 2 mm in length in the central region of lamina IX of the sixth lumbar-first sacral spinal cord segments. These neurons have a dendritic distribution that projects to the lateral, medial and ventral regions of the gray matter. Values for soma size, primary dendrite length and arborization area obtained from intact animals that were in diestrous-2, were significantly reduced following ovariectomy. After hormone priming of the ovariectomized animals with estradiol benzoate and progesterone, an additional injection of estradiol benzoate alone or followed by progesterone increased the labeled length of the primary dendrites distributed to the lateral, but not to the medial or ventral regions of the gray matter in the spinal cord. However, dendritic labeling was not significantly increased when only progesterone was additionally injected. It therefore seems that pubococcygeus muscle motoneurons of the female rat are sensitive to the effects of gonadal hormones.

Animals↗
PubMed2005

Effects of pulp and paper mill effluents on the microplankton and microbial self-purification capabilities of the Biobío River, Chile.

Most studies focus on the ecotoxicity of pulp and paper mill effluents, rather than on how they affect the physicochemical and biological structure and the intrinsic ecological capabilities of the receiving watercourses. We investigated the impact of such effluents on the water quality, microplankton system and microbial self-purification capacity (degradation of polymeric organic compounds via extracellular enzymes) of the Biobío River in Chile. The physicochemical impact on the water quality was indicated by raised conductivity, by the pollution of the water body with nitrate, nitrite and soluble reactive phosphorus, by the appearance of tannin and lignin, and by the steady accumulation of inorganic and organic suspended matter (SPM) along the river. From the biological structure of the microplankton system, very low and declining concentrations of chlorophyll a and heterotrophic flagellate densities were determined. The pulp and paper mill effluents introduced high bacterial abundances and biomass concentrations into the river water. This reflects the effective use made of the abundantly available inorganic and organic nutrients within this industrial and municipal process water by bacteria adapted to these extreme environments, additionally supported by concomitant low grazing pressure derivable from low heterotrophic flagellate abundances. Indeed, in one section of the river affected by a pulp mill, the plant was found to significantly contribute to the self-cleaning capacity of the river. However, this elevated degradation capacity was not enough to compensate for the additionally discharged organic material which, together with the toxic effects of the paper plant effluents, significantly interferes with the ecological status of the Biobío River.

Animals↗
PubMed2004

[First non-autologous vascular access for hemodialysis: PTFE fistula].

INTRODUCTION: Since 1999 to 2003 we have tried to perform an antebraquial "loop" PTFE fistula (PTFEa) as first vascular access for hemodialysis in patients without suitable superficial venous system. MATERIAL AND METHODS: We have performed a prospective study to analyze the results (permeability and complications) with this approach. RESULTS: We could perform 44 PTFEa in 46 consecutive patients (in two cases we used the axillary vein as return vessel). Early failure was 0%. One year primary and secondary permeability were 66% and 90% respectively. CONCLUSIONS: PTFEa is a good solution as first vascular access in patients without a suitable superficil venous system.

Aged↗
PubMed2002

Environmental fate of metalaxyl and chlorothalonil applied to a bentgrass putting green under southern California climatic conditions.

Putting greens usually receive high inputs of fertilizers and pesticides to meet the high demand for visual quality and to overcome the stress from close mowing and traffic. In this study, two commonly used fungicides, metalaxyl (methyl N-(methoxyacetyl)-N-(2,6-xylyl)-DL-alaninate) and chlorothalonil (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile), were evaluated for their partitioning and persistence in a bentgrass (Agrostis palustris Huds) putting green under southern California climatic conditions. The putting green site was constructed according to the US Golf Association (USGA) specifications. Lysimeter assemblies installed at the center of each plot were used to monitor the leachate, flux chambers were used to measure volatilization, clippings were collected to determine the residues on grass, and soil cores were sampled to determine residues in the soil profile. Results showed that cumulative volatilization loss accounted for 0.10 and 0.02%, clipping removal 0.11 and 0.13%, and cumulative leaching 0.71 and 0.002% of the applied metalaxyl and chlorothalonil, respectively. The two fungicides were mainly found in the top 10 cm of the soil profile due to the high organic carbon content in the thatch and mat layers. The dissipation half-life was 1.4 days for metalaxyl and 4.9 days for chlorothalonil on grass, shorter than those found in agricultural fields. This study showed that, under normal turf management practices, the offsite transport of the parent fungicides was minimal. Future research should focus on investigating the fate and mobility of the metabolites of the fungicides.

Adsorption↗
PubMed2002

NS-398: cyclooxygenase-2 independent inhibition of leukocyte priming for lipid body formation and enhanced leukotriene generation.

Because the induction of new lipid body formation in leukocytes correlates with and likely contributes to their enhanced 'primed' prostaglandin and leukotriene formation, we evaluated two selective cyclooxygenase (COX)-2 inhibitors. Three types of stimuli, cis -unsaturated fatty acids, platelet activating factor and protein kinase C activators, stimulate lipid body formation. NS-398 (0.1-10 microM), but not another COX-2 inhibitor, SC58125 (0.1- 10 microM), blocked leukocyte lipid body formation elicited by all three types of stimuli and also blocked priming for enhanced LTB(4) production and PGE(2) production. The effect of NS-398 on lipid body formation was independent of its inhibitory effects on COX-2 since arachidonate-induced lipid body formation in COX-2-deficient mouse leukocytes was also inhibited by NS-398. By means of its ability to inhibit leukocyte lipid body formation, NS-398 may exert actions independent of its COX-2 inhibition and more broadly contribute to the suppression of formation of COX-1 and lipoxygenase-derived eicosanoids.

Animals↗
PubMed2001

Effects of genitofemoral nerve transection on copulatory behavior and fertility in male rats.

Selective transection of peripheral nerves that innervate the pelvic region results in the alteration of some aspects of copulatory behavior, including seminal plug weight. Both branches of the genitofemoral nerve primarily innervate the cremaster muscle although the genital branch has a wide distribution in the cremasteric sac. Thermoregulation of spermatogenesis and the mechanical event of ejaculation largely depend on cremaster contractility. In this study, we analyzed the effects of bilateral transection of the genitofemoral nerve on male copulatory behavior and on fertility. Sexually experienced adult male rats were submitted to sexual behavior tests before and after surgical transection of the genitofemoral nerve. Tests were made four times before and on Days 9, 12, 15, 18 and 21 after surgery, and seminal plug weight was also analyzed. In addition, fertility was tested using two different approaches: by allowing the male to ejaculate once in an estrous female or keeping the male with three females during 15 days. Results showed that there were no differences in any of the copulatory parameters, including seminal plug weight. Regarding fertility, both procedures showed that the ability to induce pregnancy was significantly diminished in the neurectomized males tested at different times after surgery. These results support the notion that genitofemoral nerve regulation of fertility via contraction of the male cremaster muscle is an important factor in reproduction in rats.

Animals↗
PubMed2001

First report on chlorinated pesticide deposition in a sediment core from a small lake in central Chile.

This paper presents a first report on chlorinated pesticide deposition analyzed through sedimentary records in a small mesotrophic lake (Chica de San Pedro) in central Chile. The sediment core was sliced and dated using 210Pb, 137Cs and pollen analyses. Organochlorine pesticides were analyzed by gas chromatography with electron capture detection (GC-ECD). From these results, pesticide deposition over the last 50 years was estimated. No pesticides were detected below the 1940 slice of the core. Concentrations were in the range 0.640-1.4 ng/g d.w. for total DDTs, 0.046-0.362 ng/g d.w. for lindane and 0.015-0.310 ng/g d.w. for alpha-hexachlorohexane. Highest concentrations of pp'DDT were found in 1993-1996 and higher concentrations of pp'-DDE and pp'-DDD were found in the seventies (1972-1978). Total organic carbon (TOC) normalized data were used for statistical analysis. Although significant correlation was observed between concentrations of DDE and DDD, no correlation was found for DDT, suggesting that it had a different source. Factorial analysis grouped DDE together with DDD, while DDT was grouped together with gamma- and alpha-HCH. Total DDT fluxes were highest during the 1970s, while those for HCHs have been increasing in the 1990s. In Chile, organochlorine compounds were banned in 1985, and the historical deposition patterns seem to indicate that such measures have been effective. On the other hand, results point out a relatively new occurrence of pp'-DDT in the watershed, but the source remains unknown.

Chile↗
PubMed2000

Nonsense mutations in the human beta-globin gene lead to unexpected levels of cytoplasmic mRNA accumulation.

Generally, nonsense codons 50 bp or more upstream of the 3'-most intron of the human beta-globin gene reduce mRNA abundance. In contrast, dominantly inherited beta-thalassemia is frequently associated with nonsense mutations in the last exon. In this work, murine erythroleukemia (MEL) cells were stably transfected with human beta-globin genes mutated within each of the 3 exons, namely at codons 15 (TGG-->TGA), 39 (C-->T), or 127 (C-->T). Primer extension analysis after erythroid differentiation induction showed codon 127 (C-->T) mRNA accumulated in the cytoplasm at approximately 20% of the normal mRNA level. Codon 39 (C-->T) mutation did not result in significant mRNA accumulation. Unexpectedly, codon 15 (TGG-->TGA) mRNA accumulated at approximately 90%. Concordant results were obtained when reticulocyte mRNA from 2 carriers for this mutation was studied. High mRNA accumulation of codon 15 nonsense-mutated gene was revealed to be independent of the type of nonsense mutation and the genomic background in which this mutation occurs. To investigate the effects of other nonsense mutations located in the first exon on the mRNA level, nonsense mutations at codons 5, 17, and 26 were also cloned and stably transfected into MEL cells. After erythroid differentiation induction, mRNAs with a mutation at codon 5 or 17 were detected at high levels, whereas the mutation at codon 26 led to low mRNA levels. These findings suggest that nonsense-mediated mRNA decay is not exclusively dependent on the localization of mutations relative to the 3'-most intron. Other factors may also contribute to determine the cytoplasmic nonsense-mutated mRNA level in erythroid cells. (Blood. 2000;96:2895-2901)

Animals↗
PubMed2000

Beta-thalassaemia in Cubans: novel allele increases the genetic diversity at the HBB locus in the Caribbean.

In order to establish the molecular basis of beta-thalassaemia in Cubans, a total of 75 unrelated individuals, with beta-thalassaemia major (7), Hb S-beta-thalassaemia (28), Hb C-beta-thalassaemia (1), and beta-thalassaemia trait (39) yielding 82 beta-thalassaemia alleles, were analyzed. Seventeen different point mutations were identified accounting for 93% of the beta-thalassaemia alleles studied, revealing a high genetic heterogeneity at the HBB locus in this population. The more prevalent mutations, namely, CD 39 (C --> T) (30.5%), -29 (A --> G) (13.4%), IVS-I-110 (G --> A) (8.5%), and IVS-II-1 (G --> A) (8.5%), reflect the Mediterranean and African predominant ancestry of the extant Cuban population. We also report the identification of a novel allele, IVS-I-108 (T --> C), that possibly activates a cryptic branch site, in a beta-thalassaemia carrier with no other molecular defect within the beta-globin gene and its proximal promoter. This study shows that prenatal diagnosis of beta-thalassaemia should be feasible in about 60% of at-risk pregnancies by direct detection of selected point mutations. However, due to the wide spectrum of mutations, and in order to offer fully informative prenatal diagnosis to more than 87% of at-risk couples, the screening for beta-thalassaemia mutations in Cubans should be performed by using a general point mutation detection method, such as DGGE (denaturing gradient gel electrophoresis).

Alleles↗
PubMed2000

Fertility ratio in male rats: effects after denervation of two pelvic floor muscles.

Fertility ratio is defined here as the proportion of females that a male can impregnate after a constant period of in-polygyny living. This ratio was investigated in male rats after denervation of two pelvic floor muscles, the pubococcygeus and iliococcygeus. Denervation was carried out by transecting the somatomotor branch of the pelvic nerve. The lesion did not modify the sexual behavior of males or their overall fertility, but decreased the weight of the ejaculated seminal plug. Consequently, the number of days living in cohabitation to induce pregnancy was increased in lesioned males (approximately 13 days) compared with intact and sham animals (approximately 5 days). These results showed that the fertility ratio was optimal when intact/sham males cohabited with females for two consecutive estrous cycles, but that lesioned males needed up to four cycles to induce most pregnancies. Two hypotheses are raised by our results. The first is that pelvic floor denervation decreases the forceful tension required to expel the semen from the prostatic urethra to the vagina, then an incomplete seminal plug is expelled. The second is that denervation cut afferent fibers that reflexively promote the continence of the semen deposited in the prostatic urethra during seminal emission, allowing some to leak out before ejaculation. The latter hypothesis can also explain the recovery of the fertility ratio in lesioned males. It could be a compensatory mechanism mediated by the pudendal nerve supply to the coccygeus muscle, the other pelvic floor muscle.

Abdominal Muscles↗
PubMed2000

Cystic fibrosis F508del patients have apically localized CFTR in a reduced number of airway cells.

Present state of knowledge, mostly based on heterologous expression studies, indicates that the cystic fibrosis transmembrane conductance regulator (CFTR) protein bearing the F508del mutation is misprocessed and mislocalized in the cytoplasm, unable to reach the cell surface. Recently, however, it was described that protein levels and localization are similar between F508del and wild-type CFTR in airway and intestinal tissues, but not in the sweat glands. In this study, we used immunocytochemistry with three different anti-CFTR antibodies to investigate endogenous CFTR expression and localization in nasal epithelial cells from F508del homozygous patients, F508del carriers, and non-CF individuals. On average, 300 cells were observed per individual. No significant differences were observed for cell type distributions among CF, carrier, and non-CF samples; epithelial cells made up approximately 80% to 95% of all cells present. CFTR was detected mostly in the apical region (AR) of the tall columnar epithelial (TCE) cells, ciliated or nonciliated. By confocal microscopy analysis, we show that the CFTR apical region-staining does not overlap with either anti-calnexin (endoplasmic reticulum), anti-p58 (Golgi), or anti-tubulin (cilia) stainings. The median from results with three antibodies indicate that the apical localization of CFTR happens in 22% of TCE cells from F508del homozygous patients with CF (n = 12), in 42% of cells from F508del carriers (n = 20), and in 56% of cells from healthy individuals (n = 12). Statistical analysis indicates that differences are significant among all groups studied and for the three antibodies (p < 0.05). These results confirm the presence of CFTR in the apical region of airway cells from F508del homozygous patients; however, they also reveal that the number of cells in which this occurs is significantly lower than in F508del carriers and much lower than in healthy individuals. These findings may have an impact on the design of novel pharmacological strategies aimed at circumventing the CF defect caused by the F508del mutation.

Cell Line↗
PubMed2000

[Clinical features and response to systemic treatment of primary and secondary episcleritis and scleritis resistant to local treatment].

BACKGROUND: Scleritis and episcleritis may extend to adjacent ocular tissues with blinding consequences and may be associated with potentially lethal systemic disorders. AIM: To evaluate the ocular complications and systemic disease associations of the different types of scleritis and episcleritis. PATIENTS AND METHODS: Forty six patients with refractory scleritis and episcleritis were studied and treated during the period 1991 to 1998. RESULTS: Necrotizing type was the most common and severe category in the scleritis group of patients. A decrease in vision occurred in 58.3% of patients with scleritis v/s a 23.5% of patients with epiescleritis (p < 0.05). Uveitis was present in 35.4% of patients with scleritis and scleromalacia was present in 33.3% (p < 0.05). A specific disease association was uncovered in 51% of scleritis and in 38% of episcleritis patients. Rheumatoid arthritis, primary systemic vasculitic disease and Sjögren syndrome with vasculitis were the most common associated systemic diseases. Three patients with scleritis had tuberculosis. CONCLUSIONS: Scleritis is more severe than episcleritis, and necrotizing scleritis is the most severe type of scleritis. Classification of scleritis and episcleritis provides valuable prognostic information. A meticulous approach for the detection of a specific associated disease must be undertaken. Scleritis associated with vasculitis has a worse ocular prognosis than other non infectious diseases. Cyclophosphamide is the most effective immunosuppressive treatment to control severe ocular involvement.

Adolescent↗
PubMed1999

Spinal organization and steroid sensitivity of motoneurons innervating the pubococcygeus muscle in the male rat.

Male rat motoneurons innervating the pubococcygeus muscle were located in the ventral nucleus of lamina IX at the sixth lumbar (L6) and first sacral (S1) spinal cord segments. Retrograde labeling with horseradish peroxidase-wheat germ agglutinin was transported up to second-order dendrites and revealed that these motoneurons have a "U-shaped arborization" of dendrites toward the intermediolateral and intermediomedial nuclei area of lamina VII. This dendritic organization makes a wide "final common path" that probably integrates afferent information from several sources, accounting for the participation of the pubococcygeus muscle in autonomic and somatic processes, such as those related to micturition and reproduction. Castration produced a decrement in the morphometry of these motoneurons. A main effect was a decrement in dendritic length. Steroid replacement indicated that testosterone and estradiol, but not dihydrotestosterone, are able to induce a recovery of morphometric alterations. However, estrogen induced recovery after 2 weeks of treatment, whereas testosterone took 4 weeks. Thus, it is proposed that supraspinal aromatization of testosterone in the male central nervous system might be an important process for the appropriate organization of the pubococcygeus muscle motoneurons and that estradiol seems to need a shorter time of action than testosterone because of differential up-regulation and down-regulation of steroid receptors.

Animals↗
PubMed1999

Peripheral nerves mediating penile erection in the rat.

We examined the effects in male rats of bilateral transection of two nerves previously implicated in erectile function, the viscerocutaneous branch of the pelvic nerve (Vc) and the hypogastric nerve (HgN). In Experiment 1 (conducted in Storrs), males underwent simultaneous or successive section of Vc and HgN and were tested for copulation, reflexive erection, and noncontact erection (NCE), i.e. in response to remote cues from estrous females. NCE is considered to be analogous to 'psychogenic' erection in humans, for which the HgN has been ascribed a significant role. In all three types of test, males had a moderate to severe deficit in erectile function after Vc transection. Section of HgN alone had no apparent pro- or anti-erectile effect in any context, nor did it affect the decrement resulting from Vc surgery. Regardless of treatment, all groups retained some erectile potential in each type of test. The loss of bladder function after Vc surgery and of seminal plug deposition after HgN section gave evidence that the targeted nerves were in fact severed. In Experiment 2 (conducted in Xalapa), males were tested only for NCE, but (a) they were tested every 3 days beginning 3 days after each surgery, (b) the interval between the two surgeries was more than 2 weeks, rather than 1 week as in Experiment 1, to allow more time for recovery from general effects of surgery and for hypothetical plasticity of neural function. In the first test after the first surgery, all groups had a modest reduction in the proportion of males displaying NCE, relative to sham-operated males. However, this deficit did not extend to measures of NCE latency or number, and was absent after the second test. After the second surgery, when all males except those with sham operations had both nerves cut, none of the groups exhibited a significant deficit in NCE, and all groups had at least one test in which at least half the males responded. Thus, (a) HgN section did not significantly impair NCE, reflexive erection, or copulation; (b) Vc section impaired, but did not eliminate, erection in all three contexts, but even those effects may be transient; and (c) transection of both nerves, simultaneously or successively, did not cause a greater impairment in erection than did cutting just the Vc. We infer that the HgN may have no pro-erectile role in erection in rats, even in a model analogous to psychogenic erection. The Vc is probably the most important nerve mediating pro-erectile function in NCE, as in reflexive erection and copulation, but this nerve may not be essential for erection in rats in any context, at least in some males.

Animals↗
PubMed1999

Cystic fibrosis patients with the 3272-26A-->G mutation have mild disease, leaky alternative mRNA splicing, and CFTR protein at the cell membrane.

We characterized the 3272-26A-->G mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, creating an alternative acceptor splice site in intron 17a, that competes with the normal one, although we predict from consensus values, with lower efficiency. We analyzed five Cystic Fibrosis (CF) Portuguese patients with the 3272-26A-->G/F508del genotype. Besides clinical and haplotype characterization of those patients, we report here results from CFTR transcript analysis in nasal brushings from all five patients. RT-PCR analysis supports alternative splicing in all patients and carriers, but not in controls. By sequencing, we determined that the alternative transcript includes 25 nucleotides from intron 17a, which predictively cause frameshift and a premature stop codon. The use of this alternative splice site causes a reduction in the levels of normal transcripts from the allele with this mutation and, most probably, of normal protein as well. By immunocytochemistry of both epithelial primary cell cultures and slices from CF polyps, CFTR protein is detected at the cell membrane, with three different antibodies. Ussing chamber analysis of one nasal polyp shows a high sodium absorption, characteristic of CF. Altogether, the results suggest that the main defect caused by the 3272-26A-->G mutation is a reduction in normal CFTR transcripts and protein and therefore this mutation should be included in class V, according to Zielenski and Tsui.

Adolescent↗
PubMed1999

Regulation of noncontact erection in rats by gonadal steroids.

Male rats exhibit erections in the presence of inaccessible estrous females, and we investigated which gonadal steroids regulate these noncontact erections (NCEs). Sexually experienced Wistar males (n >/= 8/group) were tested for NCE four times (every 3 days) before castration, after castration, and after receiving subcutaneous implants of 10-mm Silastic capsules that were empty or filled with crystalline testosterone propionate (TP), dihydrotestosterone (DHT), estradiol benzoate (EB), or DHT + EB (10 mm each). Before castration, males responded with NCE in approximately 50% of tests. No males had NCEs after castration, beginning 3 days after surgery. Also, no males responded after treatment with EB or empty capsules. After receiving implants of TP, DHT, or DHT + EB, 50% of males had NCEs, beginning with the first test 3 days after treatment. On every measure of NCE, males treated with DHT or DHT + EB were indistinguishable from each other and from TP-treated males. Among the sexual responses of male rats, NCE appears to be more sensitive than other behaviors to changes in gonadal condition. In its profile of response to gonadal steroids (testosterone+, dihydrotestosterone+, estradiol-), NCE is similar to reflexive erection, for which spinal systems are sufficient, and unlike copulation (T+, DHT-, E+), which depends on discrete areas of the brain. We nonetheless conclude that NCE depends on androgen-sensitive systems in the brain, but androgen-sensitive neurons in the lumbosacral spinal cord may also play a role.

Animals↗