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M R Cruz

Publications and source records attributed to M R Cruz.

13 recordsLinked to original sources
PubMed2003

Transcriptome characterization of the dimorphic and pathogenic fungus Paracoccidioides brasiliensis by EST analysis.

Paracoccidioides brasiliensis is a pathogenic fungus that undergoes a temperature-dependent cell morphology change from mycelium (22 degrees C) to yeast (36 degrees C). It is assumed that this morphological transition correlates with the infection of the human host. Our goal was to identify genes expressed in the mycelium (M) and yeast (Y) forms by EST sequencing in order to generate a partial map of the fungus transcriptome. Individual EST sequences were clustered by the CAP3 program and annotated using Blastx similarity analysis and InterPro Scan. Three different databases, GenBank nr, COG (clusters of orthologous groups) and GO (gene ontology) were used for annotation. A total of 3,938 (Y = 1,654 and M = 2,274) ESTs were sequenced and clustered into 597 contigs and 1,563 singlets, making up a total of 2,160 genes, which possibly represent one-quarter of the complete gene repertoire in P. brasiliensis. From this total, 1,040 were successfully annotated and 894 could be classified in 18 functional COG categories as follows: cellular metabolism (44%); information storage and processing (25%); cellular processes-cell division, posttranslational modifications, among others (19%); and genes of unknown functions (12%). Computer analysis enabled us to identify some genes potentially involved in the dimorphic transition and drug resistance. Furthermore, computer subtraction analysis revealed several genes possibly expressed in stage-specific forms of P. brasiliensis. Further analysis of these genes may provide new insights into the pathology and differentiation of P. brasiliensis.

Base Sequence↗
PubMed2001

Suspected side effects of a herbicide on dung beetle populations (Coleoptera: Scarabaeidae).

This paper addresses the association between use of a herbicide and anecdotal reports of reduced dung degradation and dung beetle populations. Dung beetles were monthly collected at two adjacent ranches in Mexico. Ranches were similar in area, elevation, exposition, soil, and vegetation, but differed in weed control. Ranch A controlled weeds manually, and ranch B controlled unwanted vegetation with applications of the herbicide Tordon 101M. The main species recovered on each ranch (Ataenius apicalis) was significantly more abundant at ranch A than at ranch B. Conversely, similar numbers of a second species, Ataenius sculptor, were recovered from both ranches. Three lines of evidence support the tentative conclusion that herbicide applications may be causing a decline in populations of A. apicalis on ranch B. First, the greatest reductions of A. apicalis were observed during periods of herbicide application. Second, A. sculptor, apparently little affected by these same herbicide applications, is active primarily during months without herbicide applications. Third, preliminary results of laboratory studies show that exposure to herbicide can impair reproductive function of the dung beetle Canthon cyanellus.

2,4-Dichlorophenoxyacetic Acid↗
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↗
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

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↗
PubMed1993

Synthesis of alpha 1-antichymotrypsin and alpha 1-antitrypsin by human trophoblast.

alpha 1-Antichymotrypsin (alpha 1-ACHY) and alpha 1-antitrypsin (alpha 1-AT) are closely related glycoprotein protease inhibitors, present in plasma and other extracellular fluids, that neutralize proteases released by leukocytes in response to trauma and inflammatory stimuli. Both inhibitors are synthesized primarily by hepatocytes, although lower levels of synthesis by monocytes and breast and intestinal epithelial cells have been demonstrated. Recently, the immunohistochemical localization of alpha 1-AT and alpha 1-ACHY in intrauterine and extrauterine human trophoblastic tissue has been reported. In the present study, we have sought to determine whether human trophoblast is also able to synthesize alpha 1-AT and alpha 1-ACHY. Messenger RNA for both inhibitors was found by Northern blotting in chorionic villi obtained from first trimester and term placenta. Substantial differences in messenger levels for both inhibitors among individual placentas were noted. alpha 1-ACHY and alpha 1-AT messenger was also present in trophoblast cells in primary culture. Synthesis of alpha 1-AT and alpha 1-ACHY protein was demonstrated by SDS-PAGE after immunoprecipitation of [35S]-labeled alpha 1-AT and alpha 1-ACHY from conditioned media of trophoblast cells in culture metabolically labeled with [35S]-methionine. It is of some interest that the M(r) of the alpha 1-AT and alpha 1-ACHY secreted by trophoblast were 50,000 and 49,000, respectively, compared with 54,000 and 68,000 for these proteins in plasma (or secreted by HepG2 human hepatoma and MCF-7 human breast cancer cells).(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Neoplasms↗
PubMed1993

alpha 1-Antitrypsin- and anchorage-independent growth of MCF-7 breast cancer cells.

alpha 1-Antitrypsin (alpha 1-AT) and alpha 1-antichymotrypsin (alpha 1-ACHY) are closely related protease inhibitors, synthesized primarily by the liver, which play major roles in modulation of the inflammatory response. Previously, we had shown that MCF-7 human breast cancer cells were able to synthesize active alpha 1-AT and alpha 1-ACHY and that the synthesis of both inhibitors varied among different MCF-7 sublines. We now show that when MCF-7(ML) cells (a subline synthesizing low levels of alpha 1-AT) are grown in soft agar in medium depleted of its trypsin inhibitory capacity (i.e. alpha 1-AT-free), addition of alpha 1-AT (50 micrograms/ml) significantly reduces colony formation in both the presence and absence of estradiol (34% and 44%, respectively). Under these conditions, incubation with 10(-7) M estradiol alone increased colony formation 2- to 3-fold. Colony formation was also significantly reduced by serum leukocyte protease inhibitor, which, like alpha 1-AT, is a potent inhibitor of elastase-like enzymes. We also found that a variety of inflammatory mediators, cytokines, and steroid hormones are able to stimulate synthesis of alpha 1-AT and alpha 1-ACHY by MCF-7 cells. Stimulation by interleukin-6 (IL-6; 200 U/ml), epidermal growth factor (4 nM), and estradiol (10(-7) M) was 2- to 3-fold, whereas stimulations by tetradecanoylphorbol-13-acetate (TPA; 80 nM) and IL-1 (10 U/ml) were 2- to 5-fold and 5- to 10-fold, respectively. In each instance, protein synthesis, monitored by immunoprecipitation of 35S-labeled proteins followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and steady state mRNA levels, monitored by Northern blot analysis with specific cDNA probes, increased to the same extent. Consistent with their ability to stimulate alpha 1-AT synthesis, TPA and IL-1 reduced colony formation in the absence of estradiol by 65% and 63%, respectively. In addition, the effects of both TPA and IL-1 could be reversed by antibody to alpha 1-AT. These results suggest that local synthesis of alpha 1-AT and possibly other protease inhibitors may be important in regulating the tumorigenic potential of MCF-7 breast cancer cells.

Breast Neoplasms↗
PubMed1985

The storage pool deficiency in platelets from humans with the Chédiak-Higashi syndrome: study of six patients.

Functional and biochemical studies of platelets from human Chédiak-Higashi syndrome (CHS) are scarce and/or incomplete. In the present report, the aggregation response to a variety of inducers of platelet aggregation, the content of the dense granule constituents ATP, ADP, serotonin and calcium, the secretion of ATP, ADP, and calcium induced by thrombin, the total content of magnesium, the incorporation of 14C-adenine in the cytoplasmic pool of adenine nucleotides, as well as the content of intracellular cyclic-AMP, have been quantitated in six patients with CHS. Furthermore, data is presented on the kinetics of uptake of radiolabelled serotonin and its storage in human CHS platelets. An abnormal aggregation behaviour was found in all patients. However, the response of CHS platelets to the different inducers studied did not show a uniform pattern. The total content and the maximal amounts of the dense granule constituents secretable by thrombin were greatly decreased in all six patients. Total magnesium content was similar to that of normal platelets. The ATP/ADP ratio was higher than in controls. Uptake of radiolabelled serotonin by CHS platelets closely followed the uptake by normal platelets; during the first 2-3 min, however, incorporation of the amine by CHS platelets came rapidly to a plateau which contrasts with the steady, linear increase in uptake found in controls. CHS platelets loaded with radiolabelled serotonin and gel-filtered, showed a spontaneous release of radioactivity not observed in normal platelets under the same conditions. The cyclic-AMP content of CHS platelets was similar to that of normals. In contrast to platelets from patients with storage pool disease, the secretable calcium from CHS platelets represents a 67% of total platelet calcium (61% in normals), suggesting that the absolute values for the non-secretable portion in CHS platelets must be very low. The results reported confirm the existence of a true storage pool deficiency of the dense granule constituents as a common defect in CHS platelets. The variety of responses among patients, to the different aggregatory stimuli studied, can not be solely ascribed to the storage pool deficiency described.

Adenine Nucleotides↗
PubMed1983

Effects of garlic extract and of three pure components isolated from it on human platelet aggregation, arachidonate metabolism, release reaction and platelet ultrastructure.

We studied the effect of the methanol extract of garlic bulbs (EOG) and of three pure components isolated from it (F1, F2, F3), on human platelet aggregation induced by ADP, epinephrine, collagen, thrombin, arachidonate, PAF, and the ionophore A-23187. Incubation of PRP with EOG, either in methanol or in homologous PPP, inhibits platelet aggregation induced by all of the above mentioned agonists. F1, F2, and F3 also inhibit platelet aggregation, however, F3 was about four times more potent. Addition of EOG or F3 to platelets that have already been irreversibly aggregated by 10 microM ADP, induces rapid deaggregation. Inhibition of aggregation was still present after three hours. The inhibitory effect persisted even after the treated platelets were Gel-Filtered (GFP) or separated from plasma through a metrizamide gradient and resuspended in new homologous PPP. Thrombin-induced release of ATP from GFP was inhibited by 75-80% after EOG or F3 treatment. Incorporation of [3-H]-arachidonate by intact platelets was decreased by 50-60% in treated platelets. However, platelets incubated with the inhibitors after incorporation of radiolabeled arachidonate, although did not aggregate, produced, after thrombin activation similar amounts of radiolabeled TXB2 and lipoxygenase products as the controls. Electron microscopy of inhibited platelets, in the presence of thrombin, showed no degranulation but an increase of spherical forms. Our results suggest that the effects described might be mediate by a perturbation of the physicochemical properties of the plasma membrane rather than by affecting arachidonate or calcium metabolism in the cells. Chemical structures of F1, F2 and F3 have been provisionally assigned: F1 is diallytrisulfide, F2 is 2-vinyl-1,3-dithiene, and F3 is most probably allyl 1,5-hexadienyltrisulfide.

Adenosine Diphosphate↗
PubMed1981

Inhibition of the platelet reaction by a high molecular weight phosphoglycoprotein isolated from human platelet plasma membranes.

The effect of phospho-glycoprotein (HMW-GP), obtained from human platelet plasma membranes, on the aggregation and secretion of human platelets was studied. Incubation of PRP with 4 to 16 micrograms/ml of HMW-GP results in inhibition of ADP-, Epinephrine-, Collagen-, and Thrombin-induced platelet aggregation. The effect is mainly reflected on the secondary wave of aggregation. The inhibitory effect is partially overcome by higher concentrations of inducers, however, even under these conditions, a clear tendency towards disaggregation is observed. 5HT release (Col-induced) is strongly decreased from 50% to 4.5. The inhibitory effect on Thrombin-induced aggregation is markedly dependent on external calcium, being maximal at 5 mM calcium. The HMW-GP does not bind ADP or Thrombin. Membrane conformation is markedly affected, as evidenced by the effect of HMW-GP on the iodination of surface polypeptides of intact platelets. It is suggested that interaction of HMW-GP with the platelet membrane blocks the signal(s) transmission that links stimulus to activation. The inhibition observed might just represent an experimental amplification of the endogenous modulatory function that has been proposed for this high molecular weight phosphoglycoprotein.

Blood Platelets↗
PubMed1981

The phospholipase A2 from human platelets.

Studies on a purified phospholipase A2 (PLA2) from human platelets show that the enzyme, which is copurified with the plasma membrane fraction, has a MW of approximately 50 K Dalton, requires Ca++, and has a pH optimum of 9.4. Under optimal conditions, PLA2 activity corresponds to at least 13 nmol/min/10(9) platelets. Unsaturated PL are preferred substrates and the enzyme is considerably more active on the aggregated form of the substrate than on the monomers. The specific activity is markedly affected by the quality of the interface, showing variations of more than 10-fold between different substrate forms. In the absence of detergents, a 4-fold increase in rate is observed when both products are present. Maximal rates are obtained at 20 mole percent of products to substrate. 1,2-Diglyceride and phosphatidic acid stimulate the hydrolysis of PC by the purified enzyme, however, in these forms of the substrate, neither of them are hydrolyzed. Activation of this enzyme by some intermediate of the phospholipase C pathway might play a role in the stimulus-linked release of platelet arachidonic acid.

Arachidonic Acid↗