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Biomedical subjects

C Miranda

Publications and source records attributed to C Miranda.

At least 19 recordsLinked to original sources
PubMed2005

Isolation of Mycoplasma hominis from extragenital cultures.

In order to document the characteristics of extragenital Mycoplasma hominis infections, the clinical features of 36 cases in which M. hominis was isolated from extragenital sites of adult patients were reviewed. In most cases, the organism was detected in conventional bacterial cultures (from specimens obtained from surgical and immunosuppressed patients) that had been incubated for at least 72 h. The results indicate that in cases in which M. hominis involvement is suspected, prolonged incubation or specialized microbiological techniques for detecting Mycoplasma spp. should be employed.

Abscess↗
PubMed2005

[The role of laparoscopy in emergency abdominal surgery].

Abdominal emergencies can also be operated on through the laparoscopic approach: the approach can be diagnostic laparoscopy, surgery assisted by laparoscopy or laparotomy directed according to the findings of the laparoscopy. The general contraindications refer above all to the state of haemodynamic instability of the patient and to seriously ill patients (ASA IV). In the absence of any specific counter-indications for the specific laparoscopic procedure to be carried out, many abdominal diseases requiring emergency surgery can be performed with the laparoscopic approach. The most frequent indications are appendicitis, acute colecistitis, gastroduodenal perforation, occlusion of the small intestine, and some abdominal traumas. With a correct selection of patients and the appropriate experience of the surgeon, the results are excellent and better than open surgery (less infection of the wound, complications, hospital stay and postoperative pain). A detailed explanation is given of the basic aspects of the surgical technique in the most frequent procedures of emergency laparoscopy.

Abdomen↗
PubMed2002

Biological activity of the thyroid TRK-T3 oncogene requires signalling through Shc.

The thyroid TRK-T3 oncogene, produced by a chromosomal translocation, is a chimeric, constitutively activated version of the NTRK1/NGF receptor and it is able to transform NIH3T3 cells and differentiate PC12 cells. TRK-T3 oncoprotein triggers multiple signal transduction pathways. Among others, TRK-T3 binds and phosphorylates the Shc and SNT1/FRS2 adaptor proteins both involved in coupling the receptor tyrosine kinase to the mitogen-activated protein kinase pathway by recruiting Grb2/SOS. We were interested in defining the role of Shc in the oncogenesis by TRK-T3. The mutation of TRK-T3 tyrosine 291, docking site for both Shc and FRS2, abrogates the oncogene biological activity. To directly explore the role of Shc we used the ShcY317F mutant, which carries the mutation of a tyrosine residue involved in Grb2 recruitment. We demonstrated that the ShcY317F mutant exerts an inhibitory effect on TRK-T3 transforming activity. Such effect can be modulated by the amount of ShcY317F protein and affects the viability of cells expressing TRK-T3 by means of a mechanism involving apoptosis. Our results indicate a definitive role of the adaptor protein Shc in TRK-T3 transforming activity.

3T3 Cells↗
PubMed2002

Trinucleotide repeats in 202 families with ataxia: a small expanded (CAG)n allele at the SCA17 locus.

BACKGROUND: Ten neurodegenerative disorders characterized by spinocerebellar ataxia (SCA) are known to be caused by trinucleotide repeat (TNR) expansions. However, in some instances the molecular diagnosis is considered indeterminate because of the overlap between normal and affected allele ranges. In addition, the mechanism that generates expanded alleles is not completely understood. OBJECTIVE: To examine the clinical and molecular characteristics of a large group of Portuguese and Brazilian families with ataxia to improve knowledge of the molecular diagnosis of SCA. PATIENTS AND METHODS: We have (1) assessed repeat sizes at all known TNR loci implicated in SCA; (2) determined frequency distributions of normal alleles and expansions; and (3) looked at genotype-phenotype correlations in 202 unrelated Portuguese and Brazilian patients with SCA. Molecular analysis of TNR expansions was performed using polymerase chain reaction amplification. RESULTS: Patients from 110 unrelated families with SCA showed TNR expansions at 1 of the loci studied. Dominantly transmitted cases had (CAG)(n) expansions at the Machado-Joseph disease gene (MJD1) (63%), at SCA2 (3%), the gene for dentatorubropallidoluysian atrophy (DRPLA) (2%), SCA6 (1%), or SCA7 (1%) loci, or (CTG)(n) expansions at the SCA8 (2%) gene, whereas (GAA)(n) expansions in the Freidreich ataxia gene (FRDA) were found in 64% of families with recessive ataxia. Isolated patients also had TNR expansions at the MJD1 (6%), SCA8 (6%), or FRDA (8%) genes; in addition, an expanded allele at the TATA-binding protein gene (TBP), with 43 CAGs, was present in a patient with ataxia and mental deterioration. Associations between frequencies of SCA2 and SCA6 and a frequency of large normal alleles were found in Portuguese and Brazilian individuals, respectively. Interestingly, no association between the frequencies of DRPLA and large normal alleles was found in the Portuguese group. CONCLUSIONS: Our results show that (1) a significant number of isolated cases of ataxia are due to TNR expansions; (2) expanded DRPLA alleles in Portuguese families may have evolved from an ancestral haplotype; and (3) small (CAG)(n) expansions at the TBP gene may cause SCA17.

Adenine↗
PubMed2001

Dopamine interaction in the absence and in the presence of Cu2+ ions with macrocyclic and macrobicyclic polyamines containing pyrazole units. Crystal structures of [Cu2(L1)(H2O)2](ClO4)4 and [Cu2(H-1L3)](ClO4)3*2H2O.

The interaction with Cu2+ and dopamine of three polyazacyclophanes containing pyrazole fragments as spacers is described. Formation of mixed complexes Cu2+-macrocycle-dopamine has been studied by potentiometric methods in aqueous solution. The crystal structures of the complexes [Cu2(L1)(H2O)2](ClO4)4*2H2O (4) (L1 = 13,26-dibenzyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo[22.2.1.1(11,14)]octacosa-1(27),11,14(28),24-tetraene) and [Cu2(H-1L3)](HClO4)(ClO4)2*2H2O (6) (L3 = 1,4,7,8,11,14,17,20,21,24,29,32,33,36-tetradecaazapentacyclo[12.12.12.1(6,9).1(19,22).1(31,34)]hentetraconta-6,9(41),19(40),21,31,34(39)-hexaene) are presented. In the first one (4), each Cu2+ coordination site is made up by the three nitrogens of the polyamine bridge, a sp2 pyrazole nitrogen and one water molecule that occupies the axial position of a square pyramid. The distance between the copper ions is 6.788(2) A. In the crystal structure of 6, the coordination geometry around each Cu2+ is square pyramidal with its base being formed by two secondary nitrogens of the bridge and two nitrogen atoms of two different pyrazolate units which act as exobidentate ligands. The axial positions are occupied by the bridgehead nitrogen atoms; the elongation is more pronounced in one of the two sites [Cu(1)-N(1), 2.29(2) A; Cu(2)-N(6), 2.40(1) A]. The Cu-N distances involving the deprotonated pyrazole moieties are significantly shorter than those of the secondary nitrogens. The Cu(1)...Cu(2) distance is 3.960(3) A. The pyrazole in the noncoordinating bridge does not deprotonate and lies to one side of the macrocyclic cavity. One of the aliphatic nitrogens of this bridge is protonated and hydrogen bonded to a water molecule, which is further connected to the sp2 nitrogen of the pyrazole moiety through a hydrogen bond. The solution studies reveal a ready deprotonation of the pyrazole units induced by coordination to Cu2+. In the case of L2 (L2 = 3,6,9,12,13,16,19,22,25,26-decaazatricyclo[22.2.1.1(11,14)]octacosa-1(27),11,14(28),24-tetraene), deprotonation of both pyrazole subunits is already observed at pH ca. 4 for 2:1 Cu2+:L2 molar ratios. All three free receptors interact with dopamine in aqueous solution. L3 is a receptor particularly interesting with respect to the values of the interaction constants over five logarithmic units at neutral pH, which might suggest an encapsulation of dopamine in the macrocyclic cage. All three receptors form mixed complexes Cu2+-L-dopamine. The affinity for the formation of ternary dopamine complexes is particularly high in the case of the binuclear Cu2+ complexes of the 1-benzyl derivative L1.

Cations, Divalent↗
PubMed2001

Growth-inhibitory effect of STI571 on cells transformed by the COL1A1/PDGFB rearrangement.

Dermatofibrosarcoma protuberans (DP) is a skin tumor of intermediate malignancy characterized by high recurrence rates, for which surgical excision is the main therapy. All DP cases carry a specific t(17;22) translocation, resulting in a COL1A1/PDGFB rearrangement. The subsequently deregulated production of PDGFB generates autocrine stimulation of PDGFrbeta, leading to malignant transformation. Using NIH-3T3 cells transformed by the COL1A1/PDGFB rearrangement (5A cell line), we explored the possibility of blocking the PDGFB autocrine loop, both in vitro and in vivo, using STI571, an inhibitor of the PDGF receptor and of ABL kinase activity. The presence of small amounts of serum in the culture medium was required for the in vitro growth and morphological transformation of 5A cells. In the presence of STI571, the growth rate was reduced and the associated transformed phenotype changed to a flattened one. This effect could be reversed on removal of the inhibitor. The growth rate of tumors induced by 5A cells in nude mice was reduced by STI571 administration. Interestingly, this effect was also evident on pre-existing tumors, but no tumor eradication was observed. This is consistent with the reversible effects of the inhibitor observed in vitro but differs from the eradication effect of STI571 on BCR-ABL-induced tumors. Our data indicate that STI571 might be a candidate compound for the pharmacological treatment of DP and demonstrate that the same compound may act in different ways (cytotoxic vs. cytostatic), according to the specificity of the inhibited tyrosine kinase, namely, ABL or PDGFrbeta.

3T3 Cells↗
PubMed2001

Initial sequencing and analysis of the human genome.

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

Animals↗
PubMed2001

Matrix metalloproteinase 2 in tumor cell-induced platelet aggregation: regulation by nitric oxide.

A correlation exists between the ability of tumor cells to aggregate platelets and their tendency to metastasize. Tumor cell-induced platelet aggregation (TCIPA) facilitates the embolization of the vasculature with tumor cells and the formation of metastatic foci. It is well documented that matrix metalloproteinases (MMPs) play an integral part in tumor spread and the metastatic cascade. Therefore, we have examined the role of MMPs during TCIPA and its regulation by nitric oxide (NO) in vitro. Human HT-1080 fibrosarcoma and A549 lung epithelial cancer cells induced TCIPA in a concentration-dependent manner that was monitored by aggregometry. This aggregation resulted in the release of MMIP-2 from platelets and cancer cells, as measured by zymography. HT-1080 cells released significantly more MMP-2 than A549 cells and were more efficacious in inducing TCIPA. Inhibition of MMP-2 with phenanthroline (1-1000 microM), a synthetic inhibitor of MMPs, and by neutralizing anti-MMIP-2 antibody (10 microg/ml) reduced TCIPA induced by HT-1080 cells. TCIPA was abolished by simultaneous inhibition of platelet function with acetylsalicylic acid (100 microM; thromboxane pathway inhibitor), apyrase (250 microg/ml; ADP pathway inhibitor), and phenanthroline. NO donors such as S-nitroso-n-acetylpenicillamine and S-nitrosoglutathione (both at 0.01-100 microM) inhibited TCIPA and MMP-2 release from platelets and tumor cells. The inhibitory actions of S-nitroso-n-acetylpenicillamine and S-nitrosoglutathione were reversed by 1H-[1,2,4]oxadiazole[4,3]quinoxalin-1-one (0.01-30 microM), a selective inhibitor of the soluble guanylyl cyclase. We conclude that (a) human fibrosarcoma cells aggregate platelets via mechanism(s) that are mediated, in part, by MMP-2; (b) NO inhibits TCIPA, in part, by attenuating the release of MMP-2; and (c) these effects of NO are cGMP-dependent.

Adenosine Diphosphate↗
PubMed2001

IRS-1 and IRS-2 are recruited by TrkA receptor and oncogenic TRK-T1.

TRK-T1 oncogene is generated by the rearrangement of the NGF receptor TrkA with TPR. This gives rise to the constitutive tyrosine autophosphorylation and activation of the kinase. To study TRK-T1 oncogenic signaling and compare it to that induced by the genuine receptor TrkA, we investigated the involvement of IRS-1, a docking protein implicated in mitogenic signaling induced by several growth factors, in TRK-T1 and TrkA signaling. Here, we show that IRS-1 and IRS-2 are phosphorylated on tyrosine in presence of both TRK-T1 and the activated TrkA receptor. These tyrosine phosphorylations lead to IRS-1- and IRS-2-induced recruitment of p85PI3K, SHP-2, and Grb2 and increase in PI 3-kinase activity associated with IRS-1. Furthermore, we found that TRK-T1 is able to activate c-fos serum responsive element in cooperation with IRS-1 and IRS-2. We observed that TRK-T1 stimulates DNA synthesis in wild-type fibroblasts but not in IRS-1(-/-) mouse embryo fibroblasts. Yeast two-hybrid system experiments showed the occurrence of direct interaction between TRK and IRS molecules, which suggests involvement of different modes of interactions. On the whole, our results suggest that IRS-1 and IRS-2 could be substrates of TRK-T1 and TrkA, and hence could participate in their signal generation.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Characterization of novel methyl-branched chain fatty acids from a halophilic Bacillus species.

The 4-methylated fatty acids 4,9-dimethyldecanoic, 4,11-dimethyldodecanoic, 4,10-dimethyldodecanoic, and 4,13-dimethyltetradecanoic acid as well as the 2-methylated fatty acids 2,13-dimethyltetradecanoic and 2,12-dimethyltetradecanoic acid were identified for the first time in nature in the halophilic bacterium Bacillus sp. isolated from the salt pans of Burgas in Bulgaria. The principal fatty acids in this bacterium were a series of iso-anteiso fatty acids with chain lengths between C11 and C19, but an interesting series of linear alkylbenzene fatty acids with chain lengths between C10 and C14, such as 12-phenyldodecanoic acid, were also identified. The novel 4-methylated fatty acids were characterized using a combination of GC-MS and chemical transformations such as N-acylpyrrolidide derivatization. The 2-methylated fatty acids were also identified by GC-MS and gas chromatographic coelution with synthetic samples. The novel methyl-branched fatty acids probably originated from the selective incorporation of methylmalonyl-CoA by one of the fatty acid-synthesizing enzymes of the bacterium.

Bacillus↗
PubMed2001

Insulin modifies the proliferation and function of chicken testis cells.

We investigated whether insulin plays a role in the proliferation and androgen production of chick testis cells. Testes from 18-d-old chick embryos or newly hatched chickens were dissociated and precultured in the presence of fetal bovine serum (FBS) for 24 h. After this period, testis cells from 18-d-old chick embryos were cultured in serum-free medium for 1 h with 0, 10, 50, or 100 microg/mL of insulin and were then exposed to human chorionic gonadotropin (hCG) for 3 h. In addition, some cells were incubated for 18 h with only insulin or insulin plus hCG. Androgens were measured by radioimmunoassay in the spent media. To study the influence of insulin on testis cell proliferation, cells were exposed to insulin for 18 h. A pulse of 3H-thymidine was added thereafter. We found that 18-d-old embryonic testis cells responded to hCG, increasing androgen production. Incubation with insulin for 1 h did not affect basal androgen production but modified the subsequent response to hCG. The addition of insulin plus hCG for 18 h resulted in important downregulation of the hCG effect. In addition, insulin significantly increased the proliferation of embryonic testis cells. The cells from testes of newly hatched chickens were precultured as described for embryonic cells and then exposed to insulin for 1 h in a serum-free medium. This treatment significantly increased the basal androgen production. Insulin also significantly enhanced the response to hCG of the testis cells from newly hatched chickens. These results strongly suggest that insulin has a role in the activity and in the proliferation of cultured testis cells throughout the perinatal period.

Androgens↗
PubMed2001

Release of norepinephrine from human ovary: coupling to steroidogenic response.

We investigated the possibility that norepinephrine from the human ovary is released after nerve stimulation and that this neurotransmitter is coupled to a steroidogenic response. Biologically significant levels of both norepinephrine and dopamine were found in human ovarian biopsies. [3H]norepinephrine incorporated in vitro was readily released by electrical stimulation in a Ca2+-dependent process. Ovarian membrane preparations exhibited specific binding sites for the beta-adrenergic antagonist [3H]dihydroalprenolol. Displacement of [3H]dihydroalprenolol with zinterol (a specific beta2-agonist) indicated that 72% of these sites were type beta2-receptors. beta-receptors were also present on granulosa cells. Stimulation of granulosa cells with luteinizing hormone or the beta-agonist isoproterenol increased the release of progesterone after 4 d in culture. These results suggest that the sympathetic nerves present in human ovary are coupled to beta-adrenergic receptors present in endocrine cells and, as in nonprimate mammals, appear to participate in the regulation of ovarian function.

Adrenergic beta-Agonists↗
PubMed2001

Combined endovascular treatment of dissecting vertebral artery aneurysms by using stents and coils.

OBJECT: With the recent development and refinement of endovascular stents, the significant potential for these devices in the treatment of wide-necked dissecting and fusiform aneurysms has become apparent. In this article the authors report on the use of stents and coils to treat dissecting and fusiform vertebral artery (VA) aneurysms. METHODS: Eight consecutive patients harboring eight dissecting aneurysms and one fusiform aneurysm of the VA were succesfully treated using a procedure in which the authors inserted an intravascular stent and secondary endosaccular coils when needed. In all but one patient complete aneurysm occlusion was achieved, and in all cases there was no neurological complication. Follow-up angiography examinations were performed in all patients (mean duration of follow-up angiography review 13.1 months, range 3-42 months). The patients remained stable throughout the clinical follow-up period (mean 14.1 months, range 4-42 months). No rebleeding was recorded. CONCLUSIONS: At present this combined approach represents a reliable and safe alternative for the treatment of VA dissecting aneurysms, especially in patients who cannot tolerate occlusion tests.

Adult↗
PubMed2001

[Endovascular treatment of partially clipped aneurysms].

Partial clipping may occur in about 4% of surgical procedures. The risk of hemorrhage persists if the aneurysm is not completely excluded. Reoperations are often difficult, technically demanding and may carry an increased risk of complications. We report our experience with the use of Guglielmi detachable coils in the treatment of 9 aneurysm remnants. Five patients (55.6%) presented with a second subarachnoid hemorrhage. Eight of the aneurysms (88.9%) were located on the anterior circulation. Postoperative angiography showed complete occlusion in 8 cases (88.9%). Certain partial clipping types may assist and favor a stable coiling procedure allowing a more compact cast. On the other hand, the clip may interfere with the correct visualization of the neck. In this series, there was no neurological morbidity associated with the procedure. There were no hemorrhagic events during or after the embolization. Endovascular treatment of aneurysm remnants can be performed safely and may constitute a valuable option to microsurgery.

Adult↗
PubMed2001

[Deciding about pacing mode in sinus node dysfunction: should carotid sinus massage be performed and in which circumstances?].

OBJECTIVE: To state the incidence of carotid sinus syndrome (CSS) with atrioventricular node manifestation in patients with sinus node dysfunction (SND) and indication for a definitive pacemaker (PM), we propose a new protocol between atrial pacing AAI and double chamber DDD. POPULATION AND METHODS: 69 patients (PTS) (male 71%), median age 65 +/- 10 years, with SND (normal PQ and no intraventricular conduction defect), that had a PM implant following the protocol that included carotid sinus massage for the pacing decision, were followed prospectively between December 1995 and November 1999. During the protocol we implanted DDD PM in PTS with Wenckebach less than 130 or Wenckebach equal/over 130 and CSS. At least, in PTS with Wenckebach equal/over 130 and no CSS we implanted AAI PM. The follow-up was between 4 months and 4 years, with clinical evaluation in the first and fourth months and then half yearly, with carotid sinus massage in the first evaluation. RESULTS: About 1/4 of the 69 patients followed had SND without carotid sinus syndrome, or atrioventricular node repercussion; the SND involved the atrioventricular node in 56% of the patients, and there was a relation between the SND and carotid sinus syndrome in 18.8%. The follow-up revealed, in all patients, a complete remission of the symptoms, and when we repeated the carotid sinus massage in the first evaluation, there was a response like in the surgery room, in all patients. CONCLUSIONS: There is a significant number of patients with SND and carotid sinus syndrome. The carotid sinus massage performed in the surgery room does not influence the test sensitivity and specificity in the diagnosis of carotid sinus syndrome. The authors think that carotid sinus massage should be considered in the protocol that defines the pacing mode, in patients with SND, and that influence the choice of pacemaker in 18.8% of patients.

Aged↗
PubMed2000

Unique origin and specific ethnic distribution of the Friedreich ataxia GAA expansion.

The GAA triplet repeat expansion that causes Friedreich ataxia is found only in individuals of European, North African, Middle Eastern, or Indian origin (Indo-European and Afro-Asiatic speakers). Analysis of normal alleles of the GAA repeat and of closely linked markers suggests that expansions arose through a unique two-step process. A major implication of these findings is that Friedreich ataxia may not exist among sub-Saharan Africans, Amerindians, and people from China, Japan, and Southeast Asia.

Africa, Northern↗