Biomedical subjects

C Cunha

Publications and source records attributed to C Cunha.

At least 19 recordsLinked to original sources

PubMed2004

Phylogenetic structure of Zacco platypus (Teleostei, Cyprinidae) populations on the upper and middle Chang Jiang (=Yangtze) drainage inferred from cytochrome b sequences.

We examined the genetic structure and phylogenetic relationships of some Chinese populations from the Chang Jiang (=Yangtze) drainage of the cyprinid Zacco platypus. We sequenced the complete mitochondrial cytochrome b gene of 64 individuals from 6 upper and middle tributaries of the Sichuan and Hunan Provinces to assess their population structure and systematics. The combined analyses of the phylogenetic information and the population structure suggested that Chinese Z. platypus consist of four distinct mtDNA lineages which exhibit high genetic variation and haplotypic diversity (Zacco A-D). The high molecular divergence observed among Zacco A-D mtDNA lineages (TrN+I (0.76) distance, mean 8.9%+/-1.7%) and their phylogeographic structure indicate that all four lineages have evolved independently. Analysis of molecular variance (AMOVA) indicates that most of the genetic variation observed is found among the four Zacco mtDNA lineages (thetaCT = 0.94) suggesting restricted gene flow among the Chang Jiang populations. Long-term interruption of gene flow was also evidenced by thetaST values higher than 0.9 that could be favoured by the discontinuous distributions of the lineages inhabiting upper (Sichuan Province) and middle (Hunan Province) Chang Jiang tributaries. The significant correlation between the geographic and genetic distances provide support for the importance of geographic discontinuity in shaping the Zacco genetic structure. Nested clade analysis (NCA) results were congruent with phylogenetic relationships recovered and confirm the genetic distinctiveness of four independent Zacco groups. These four groups correspond to the four Zacco A-D mtDNA lineages recovered in the phylogeny and were defined by nucleotide synapomorphies permitting bootstrapped and Bayesian confidence of 95% or greater. The high level of mitochondrial sequence divergence separating all Zacco mtDNA lineages suggested that the Z. platypus populations from the Chang Jiang drainage probably correspond to four different species.

Animals↗

PubMed2004

Phylogeographical insights into the origins of the Squalius alburnoides complex via multiple hybridization events.

The origin, the phylogeographical structure and divergence times of hybridrogenetic Squalius alburnoides complex were analysed based on the complete mitochondrial cytochrome b gene (1140 pb). The molecular phylogenetic analyses suggest that the S. alburnoides complex has at least five asexual lineages of independent origin. The events that produced this ancestral hybridization took place over a long period of time. There have been multiple hybridization events throughout time, beginning in the upper Pliocene and probably continuing into the present. Increased humidity caused by climate changes in the Pliocene, along with tectonic lifting and vasculation of the Iberian Peninsula, led to the formation of current river drainages which, in turn, contributed to these hybridization events. We postulate that the Northwestern (Mondego and Douro) and the Southwest (Quarteira) drainages of the Iberian Peninsula delimited the border of the maternal ancestral distribution and that vicariant events led to the disappearance of the maternal ancestor in these regions, leaving today only the hybrid species. Two hypotheses have been suggested to explain the similarities between the mtDNA diversity observed in S. alburnoides and its maternal ancestor (S. pyrenaicus). The first hypothesizes that mtDNA similarity results from the recent extinction of the paternal ancestor, while the other postulates that: 'reconstituted non hybrid males' assumed the place of the extinct bisexual paternal ancestor and produced new hybridizations with S. pyrenaicus females.

Animals↗

PubMed2004

First isolation of Borrelia lusitaniae from a human patient.

The first human isolate of Borrelia lusitaniae recovered from a Portuguese patient with suspected Lyme borreliosis is described. This isolate, from a chronic skin lesion, is also the first human isolate of Borrelia in Portugal. Different phenotypic and molecular methods are used to characterize it.

Base Sequence↗

PubMed2001

The posterior interosseous flap: a review of 81 clinical cases and 100 anatomical dissections--assessment of its indications in reconstruction of hand defects.

Based on our experience of 100 cadaveric dissections and a series of 81 clinical cases, we have assessed the indications for the posterior interosseous flap in reconstruction of the hand. Large fasciocutaneous island flaps can be harvested, even when the radial or ulnar pedicles are damaged, sacrificing only vessels of secondary importance to the perfusion of the hand. Compound flaps can be dissected based on muscular, musculoperiosteal and fascioperiosteal branches. The primary indications for using this flap are dorsal hand defects up to the metacarpal joints, reconstruction of the first web space up to the interphalangeal joint of the thumb and extensive lesions on the ulnar border of the hand.

Adolescent↗

PubMed2001

Transcription-dependent nucleocytoplasmic distribution of hnRNP A1 protein in early mouse embryos.

A unique feature of certain members of the heterogeneous nuclear ribonucleoprotein (hnRNP) family of proteins is that they shuttle continuously between nucleus and cytoplasm and their accumulation in the nucleus is transcription-dependent. An extensively characterised protein of this group is hnRNP A1. To date, most studies addressing the transcription-dependent transport of hnRNP A1 have been performed on cultured cell lines treated with transcription inhibitors. Here we have analysed the nucleocytoplasmic distribution of hnRNP A1 in early mouse embryos, where the haploid pronuclei remain transcriptionally inactive for a period of several hours. Consistent with its small molecular size (36 kDa), the hnRNP A1 protein diffuses passively through the nuclear pores and equilibrates between the nucleus and the cytoplasm of transcriptionally inactive embryos. In contrast, following transcriptional activation the A1 protein becomes accumulated in the nucleus. This accumulation of the A1 protein in the nucleus is blocked by the lectin wheat germ agglutinin (WGA), which binds to nuclear pore proteins and prevents translocation of receptor-cargo complexes through the pores. This indicates that a carrier-mediated transport pathway is required for the concentration of A1 in transcriptionally active nuclei. To further analyse how transcription is coupled to nucleocytoplasmic transport, we transplanted transcriptionally inactive pronuclei into the cytoplasm of transcriptionally active embryos. The results show that the presence of newly synthesised RNAs in the cytoplasm is not sufficient to induce the accumulation of hnRNP A1 in the nucleus. Rather, the appearance of nascent transcripts in the nucleus appears to be the crucial event. Since hnRNP A1 is a shuttling protein, an increase in its steady state nuclear concentration could be the result of either faster nuclear import or slower export to the cytoplasm. We propose that binding of A1 to nascent transcripts retards its export to the cytoplasm and therefore contributes to its concentration in the nucleus.

Animals↗

PubMed2000

The human autoantigen MCP1 is required during early stages of DNA replication.

Metaphase chromosome protein 1 (MCP1) is a nuclear autoantigen that is associated with condensed chromosomes throughout mitosis. During interphase, this antigen shows a speckle distribution in the nucleus, excluding the nucleolus. Additionally, MCP1 binds tightly to the scaffold/matrix component of nuclei and isolated chromosomes. In order to determine the in-vivo localization of the antigen, we have expressed MCP1 fused to EGFP in tissue culture cells. The results demonstrate that MCP1 is located in the nucleus during interphase and during mitosis associates tightly to condensed chromosomes. Furthermore, microinjection of specific antibody confirms these results. We have used a specific monoclonal antibody (mAb 402) against MCP1 to assess the function of this antigen during cell cycle progression. HeLa and Ptk-2 cells that were microinjected into the nucleus and/or cytoplasm at G1/S and very early S phase were not able to progress and complete DNA replication. However, injection of mAb 402 at mid or late S phase does not prevent completion of DNA replication and subsequent progression into mitosis. Microinjection of mAb 402 in Ptk-2 cells synchronized in mitosis did not interfere with progression of mitosis and cells divided. Our results suggest that MCP1 is required at the G1/S transition and during early S phase.

Animals↗

PubMed2000

Chromatin condensation during Scrobicularia plana spermiogenesis: a controlled and comparative enzymatic ultracytochemical study.

In Scrobicularia plana testis, a nuclear acid phosphatase (ACPase) activity was detected in mid and late spermatids with the improved Gomori-chloride procedure. Lead deposits were first observed in mid spermatids at focal points over condensed chromatin strands, increasing in density as chromatin further condensated. In late spermiogenesis, lead deposits became concentrated between chromatin aggregates, and after total DNA compaction were transfered to the nuclear periphery and then shed into the cytoplasm. The specificity of the nuclear ACPase was tested against different pH values (3.9, 7.2, 7.8, 9.0), substrates (TPP, IDP, TMP, p-NCS, ATP, GTP, AMP, ADP, AMP-PNP) and inhibitors (NaF, levamisole, Zn, vanadate, theophylline). To further specify the nature of this nuclear ACPase, other enzymes were comparatively studied at their optimal pH values and at pH 5.0: nucleoside-diphosphatase, thiamin-pyrophosphatase, inorganic trimetaphosphatase, lysosomal arylsulfatases A and B, ATPase, GTPase, 5'-nucleotidase, adenylate kinase, and adenylate cyclase. Several other controls were introduced to exclude artefactual deposits induced by lead ions and tissue molecules. The results showed that the enzyme has an optimal pH at 5.0, a high specific affinity for beta-GP, and is inhibited by NaF, which suggests that it behaves as a type B-ACPase, and all controls demonstrated the specificity of the enzymic activity. Because lead deposits were specifically and temporally associated with spermatid chromatin condensation, when DNA and RNA synthesis, histones, phosphoproteins and RNA molecules strongly decrease, it is possible to suggest that the nuclear ACPase could be associated with DNA processing during chromatin compaction or involved in the hydrolysis of 2' and 3' nucleotides resulting from nuclear RNase action during RNA degradation.

Acid Phosphatase↗

PubMed1998

Effects of ethanol on Pavlovian autoshaping in rats.

Approach responses, consummatory behaviors, and directed motor responses maintained by food reward resemble autoshaping CRs and are increased by lower doses of ethanol. This study evaluated the effects of presession i.p. injections of ethanol doses (0.00, 0.25, 0.50, 0.70. or 1.00 g/kg) on the acquisition of lever-press autoshaping CR performance in groups of male Long-Evans hooded rats. Paired groups received 15 daily sessions of Pavlovian autoshaping procedures, wherein the insertion of a retractable lever for 5 s (CS) was followed by the response-independent presentation of food (US). Ethanol facilitated lever-press autoshaping CR acquisition, as revealed by dose-related increases in the number of trials on which CRs were performed. The form of the dose-effect curve was inverted U-shaped with maximal responding induced during sessions 1-5 by the 0.70 g/kg ethanol dose. A similar dose-effect curve was observed during sessions 11-15, revealing that the effects of ethanol on autoshaping CR performance were relatively stable. A pseudoconditioning control group injected presession with 0.50 g/kg ethanol received training wherein the food US was presented randomly with respect to the lever CS. Few lever-presses were performed by the Random 0.50 group, indicating that ethanol's effects on autoshaping CR acquisition and maintenance observed in the Paired 0.50 group were not due to its psychomotor activating effects. A non-injection control group performed more autoshaping CRs than did the control group injected presession with saline, indicating that daily presession i.p. injections per se suppress autoshaping CR performance. Results reveal that low doses of ethanol enhance Pavlovian conditioning of directed motor and consummatory-like responding maintained by food reward. Implications for autoshaping accounts of impulsivity and drug abuse are considered.

Animals↗

PubMed1998

Localization of hepatitis delta virus RNA in the nucleus of human cells.

Hepatitis delta virus (HDV) is a human pathogen that can greatly increase the severity of liver damage caused by an hepatitis B infection. HDV contains a circular, single-stranded RNA genome that encodes a unique protein, the delta antigen. Two forms of the delta antigen, deltaAg-S and deltaAg-L, are derived from a single open reading frame by RNA editing. Here we analyze the subcellular distribution of HDV RNA and its spatial relationship to known intranuclear structures. The human hepatoma cell line Huh7 was stably transfected with wild-type HDV cDNA and the viral RNAs were localized by in situ hybridization and fluorescence confocal microscopy. HDV RNA is detected throughout the nucleoplasm, with additional concentration in focal structures closely associated with nuclear speckles or clusters of interchromatin granules. Both the smaller form of the delta antigen (deltaAg-S), which is required for HDV genomic replication, and the larger form of the delta antigen (deltaAg-L), which represses replication, co-localize with delta RNA throughout the nucleoplasm and in the foci. However, the foci do not incorporate bromo-UTP and do not concentrate either RNA polymerase II or cleavage and polyadenylation factors required for viral RNA synthesis and 3' end processing, respectively. Thus, it is unlikely that the delta foci represent major sites of viral transcription or replication. In conclusion, the data show that viral RNA-protein complexes accumulate in structures closely associated with interchromatin granules, a subnuclear domain highly enriched in small nuclear ribonucleoproteins, poly(A+) RNA, and RNA splicing protein factors. This implies a specific compartmentalization of ribonucleoproteins in the nucleus.

Carcinoma, Hepatocellular↗

PubMed1998

[Microsurgical reconstruction of the head and neck: experience of 63 free flaps].

The authors present the experience of 63 clinical cases of microsurgical reconstruction of the head and neck. These reconstructions were accomplished by different microvascular free flaps which were selected according to the type, size and location of the defects. Fasciocutaneous, osteofasciocutaneous, adipofascial, myo, myocutaneous, myosseous, jejunum and great omentum flaps were applied. The etiology was traumatic in 10 cases, tumoral in 41 cases, congenital in 7 cases, iatrogenic in 3 cases and infectious in 2 cases. The reconstructed anatomical regions were the scalp in 6 cases, the skull base in 1 case, the orbit in 3 cases, the nose in 1 case, the hemiface in 7 cases, the lips in 1 case, the intraoral cavity in 21 cases, the mandible in 8 cases, the intraoral cavity plus mandible in 11 cases and the cervical esophagus in 1 cases. An analysis was made of surgical times, selection and survival rate of the free flaps and the morphofunctional quality of the reconstructions. Considering the good quality of reconstructions, the amelioration of quality of life and the low morbidity in these patients, microvascular free flaps are considered a first choice technique for head and neck reconstruction when the size and location of the defect prevents the use of local flaps.

Adult↗

PubMed1998

[Microsurgical reconstruction of the upper extremity. Experience with 24 free flaps].

The authors present the experience of 24 clinical cases of microsurgical reconstruction of the upper limb. These reconstructions were accomplished by different microvascular free flaps which were selected according to the type, size and location of the defects, having applied fasciocutaneous, adipofascial, myo, myocutaneous, tendofasciocutaneous, omentum flaps and 2nd toe transfers. The etiology was traumatic in 23 cases and tumoral in 1 case. A careful analysis was made for surgical times, selection and survival rate of the free flaps and the morphofunctional quality of the reconstructions. Microvascular free flaps are considered the choice technique for upper limb reconstruction, particularly for the hand in certain defects, considering the better anatomic and functional quality of the reconstructions.

Adolescent↗

PubMed1997

Presession noise increases sensitivity to chlordiazepoxide's discriminative stimulus in pigeons.

1. Pigeons were trained to discriminate chlordiazepoxide (CDP) from saline using two-key food reinforced drug discrimination procedures. Discriminative control by CDP was maintained despite extended training with vehicle-like doses of CDP, by using a modified "fading" procedure that provided for a mixture of drug discrimination training sessions preceded by an i.m. injection of either 8.0 mg/kg CDP, or a lower training dose of CDP (4.0, 2.8, 2.0, 1.4, 1.0, 0.7, or 0.5 mg/kg CDP), or saline. The lower training dose was decreased across blocks of sessions. 2. Four lower training doses (1.4, 1.0, 0.7, and 0.5 mg/kg CDP) were retrained, with 10 min of 98 dB of noise administered 75 min prior to each drug discrimination training session. Presession exposure to noise increased percent CDP-appropriate choices for each of the four lower training doses by 15-20% over those obtained previously. 3. It is concluded that brief presession exposure to loud noise increases sensitivity to the discriminative stimulus effects of low training doses of CDP.

Animals↗

PubMed1997

The cdk7-cyclin H-MAT1 complex associated with TFIIH is localized in coiled bodies.

TFIIH is a general transcription factor for RNA polymerase II that in addition is involved in DNA excision repair. TFIIH is composed of eight or nine subunits and we show that at least four of them, namely cdk7, cyclin H, MAT1, and p62 are localized in the coiled body, a distinct subnuclear structure that is transcription dependent and highly enriched in small nuclear ribonucleoproteins. Although coiled bodies do not correspond to sites of transcription, in vivo incorporation of bromo-UTP shows that they are surrounded by transcription foci. Immunofluorescence analysis using antibodies directed against the essential repair factors proliferating cell nuclear antigen and XPG did not reveal labeling of the coiled body in either untreated cells or cells irradiated with UV light, arguing that coiled bodies are probably not involved in DNA repair mechanisms. The localization of cyclin H in the coiled body was predominantly detected during the G1 and S-phases of the cell cycle, whereas in G2 coiled bodies were very small or not detected. Finally, both cyclin H and cdk7 did not colocalize with P80 coilin after disruption of the coiled body, indicating that these proteins are specifically targeted to the small nuclear ribonucleoprotein-containing domain.

Carrier Proteins↗

PubMed1997

[Importance of nutritional aspects in attention deficit hyperactivity disorders].

The attention deficit hyperactivity disorder is a common childhood syndrome that is recognized as an important medical-social problem, being the object of an exhaustive investigation related to its etiology, diagnostic approach and prevention, and treatment forms. Among the factors that can alter the cerebral function, is the malnutrition. The authors discuss the association of the syndrome with the nutritional condition of students from elementary schools.

Analysis of Variance↗

PubMed1997

[Reconstruction of the anterior cranial base with a frontal muscle flap in cerebrospinal fluid fistulae].

Craniofacial infection is a major problem for the plastic and neurosurgical team. Previous successful experiences with free muscle and omentum flaps and the galea frontalis myofascial flap have been reported, avoiding disastrous complications after frontofacial advancements and the resection of skull base tumors. The authors report the clinical use of the galea frontalis myofascial flap in the treatment of anterior fossa CSF leaks. This flap provides an adequate sized and vascularized barrier between the cranial and nasal cavities through which the cells of the inflammatory response reach the target area. This technique was used in 11 cases with complete success; in-6 patients, repair of the anterior cranial base bone defect was performed with split calvarium bone grafts, harvested from craniotomy bone. In all the patients, neither the recurrence of the CSF leakage nor post-operative meningitis or its recurrence were observed.

Adult↗

PubMed1996

The topography of chromosomes and genes in the nucleus.

At present several lines of evidence indicate that the nucleus is functionally compartmentalized into discrete structures with defined properties. For instance, it is well established that the molecular machines involved in replication, transcription, and RNA processing assemble into morphological entities but it remains unclear whether these correspond to autonomous "organelles" or rather represent temporary accumulations of either active factors recruited onto DNA templates or inactive factors stored in the vicinity of genes. According to the latter view, the spatial distribution of genes during interphase should play a major role in the subnuclear organization of nonchromatin components such as replication, transcription, and processing factors, and in this article we discuss current ideas on the functional compartmentalization of chromosomes and genes within the nucleus.

Binding Sites↗

PubMed1995

How to evaluate the quality in a system of video-microscopy in the field of anatomic pathology.

The acquisition of a video microscope image is explained by the concept of modulation transfer function to describe the quality of a microscope which should target a sensor of a video camera to allow around 50 pairs of lines per mm with a good contrast in the video-monitor. Taking this into consideration, high aperture lenses, a microscope with infinity optics, a low power video adapter and a high quality camera must be used.

Humans↗

PubMed1995

Telemedicine project in the Azores Islands.

Telemedicine projects and programmes began in Portugal only in 1992 with a telepathology programme in real time frozen section service. The main purpose and challenge of the telemedicine is to allow the access of a special and specific health care to populations as the 250,000 inhabitants of the Azores archipelago. We wish to start with telepathology, teledermatology, telecardiology, tele ORL, telepsychiatry, telematernal and foetal medicine in all islands of the archipelago, also connected with the Major University Centers in Lisbon. The system must be composed of a video conferencing station working in ISDN at 384 kb/sec connectors via a switch to the video camera applied to different video-cameras. Telemedicine improves the human, economical, social and cultural life quality to the people of the European, but depressed ultraperipherical region of Azores.

Azores↗