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Biomedical subjects

F Rosa

Publications and source records attributed to F Rosa.

At least 19 recordsLinked to original sources
PubMed2006

Occurrence of alkylphenolic substances in a Great Lakes coastal marsh, Cootes Paradise, ON, Canada.

Occurrence and fate of alkylphenols (APs), known endocrine disruptors, were investigated in a Great Lakes coastal wetland, Cootes Paradise, ON. The wetland, which receives discharges from a Wastewater Treatment Plant (WTP) and several Combined Sewer Overflows (CSOs), is an important spawning ground for fish and crucial habitat for other fauna. Elevated concentrations of nonylphenol ethoxylates (NPEs) and their degradation product nonylphenol (NP) were found in water and sediment samples near the sources. Since transfer of APs through the food chain is of concern, we compared their concentrations in invertebrates from clean and contaminated sites. The results reveal transfer of alkylphenolics from sediments to biota and their accumulation in the invertebrate tissue, particularly the highly hydrophobic 4-NP, whose concentrations ranged from 1.9 to 6.3 microg g(-1). To our knowledge, this is the first study to evaluate AP concentrations in tissue of benthic invertebrates under real environmental conditions.

Animals↗
PubMed2005

[Guideline on radiation protection in medicine requires documentation of radioiodine therapy and follow-up: What are the benefits of an electronic database?].

AIM: The lately updated German guideline on radiation protection in medicine (Richtlinie Strahlenschutz in der Medizin) requires the physician who administers radioactive substances for therapy, to perform and document follow-ups. In order to decrease the administrative burden, an electronic database was developed that interfaces with a word processing software to generate written reports and statistic analysis. METHODS: Based on Microsoft Access and Microsoft Visual Basic a database was created to monitor patients with benign and malignant thyroid disorders after radioiodine therapy. It permits automatic creation of therapy documents and necessary patient reports in Microsoft Word. Intuitive handling, third level of normalization in database architecture and automatic plausibility checks guarantee integrity of the data and the efficacy of the database. RESULTS, CONCLUSION: The new software has been a success in over 1500 patients and over 3800 in- and outpatient therapies and visits. The effort of data entry is easily offset by the automatic generation of the necessary patient reports. The required supervision of the follow-up appointments is now also user-friendly and efficient.

Databases, Factual↗
PubMed2004

Application of the Max-Lloyd quantizer for ECG compression in diving mammals.

This article presents a practical implementation of an ECG compression algorithm using a Max-Lloyd quantizer, to optimize the low resources of an ECG acquisition and transmission system (telemetry system) for dolphins and human divers. The algorithm scheme is based on a first-order differential pulse code modulation (DPCM) and uses a Max-Lloyd quantizer to code the difference between the current and predicted samples. The use of the non-uniform quantizer instead of a uniform quantizer improves the percent root mean-square difference (PRD), thereby producing a low distortion in the reconstructed signals. Due to its low computational complexity, the compression process can be accomplished on-line during the ECG acquisition process.

Algorithms↗
PubMed2004

Colorectal cancer patients before resection of hepatic metastases. Impact of (18)F-FDG PET on detecting extrahepatic disease.

AIM: Evaluation of the role of FDG-PET in comparison to conventional staging methods for detecting extrahepatic tumour deposits prior to resection of liver metastases. PATIENTS, METHODS: In our prospective study, 58 patients (24 women, 34 men; age 33-81 years) with liver metastases of colorectal carcinoma underwent FDG-PET. Images were acquired in 3D-mode including transmission scans and reconstructed iteratively. For conventional staging all patients underwent abdominal ultrasound, helical computed tomography (CT) of the thorax and abdomen, and colonoscopy/rectoscopy. A preliminary therapeutic decision was established without knowledge of the FDG-PET findings. Thereafter, it was revised or confirmed according to the results of FDG-PET. RESULTS: In 3/58 patients extrahepatic tumour deposits were concordantly identified with both conventional staging methods and FDG-PET. However, in one case, both conventional methods and FDG-PET were false positive regarding pulmonary metastases. In 12/58 patients, nothing but FDG-PET detected extrahepatic tumour masses, which were later confirmed either by histology or follow-up. CONCLUSION: Our study suggests that in 21% of patients exclusively FDG-PET is an appropriate diagnostic tool to reveal extrahepatic metastases or local recurrence of colorectal carcinoma. Our results demonstrate that FDG-PET provides relevant additional information for accurate therapeutic planning as compared to the conventional combination of staging methods. Therefore, FDG-PET has to exert a decisive influence on the decision for resection of hepatic metastases.

Adult↗
PubMed2002

Cooperative action of ADMP- and BMP-mediated pathways in regulating cell fates in the zebrafish gastrula.

It was shown in Xenopus and chick that Spemann's organizer activity is regulated through the negative action of Anti-Dorsalizing Morphogenetic Protein (ADMP). We report the characterization and functional properties of admp in zebrafish. admp expression profile is consistent with a role in the organizer, including the tail organizer. We studied admp function through overexpression experiments, with the use of a dominant-negative form (TR-ADMP) and of an antisense morpholino-modified oligonucleotide. Our results indicate that the ADMP pathway causes the restriction of anterior and axial fates and that ADMP, BMP2b, and BMP7 pathways have distinct actions but cooperate in establishing proper dorso-ventral regionalization. This is shown by partial rescue of the dorsalized mutant snailhouse and of the ventralized mutant chordino, upon admp and tr-admp RNA injection, respectively. Moreover, ADMP and BMP7 probably form heterodimers as shown by the ability of TR-ADMP and BMP7 to antagonize each other. We observed that a MYC-tagged ADMP was secreted and detected in the extracellular space, suggesting that admp could act at a distance. Simultaneous local inhibition of bmp function at the blastoderm margin and impairment of ADMP secretion led to the induction of secondary head structures, confirming that the two pathways cooperatively regulate organizer formation and activity.

Amino Acid Sequence↗
PubMed2001

A crucial component of the endoderm formation pathway, CASANOVA, is encoded by a novel sox-related gene.

casanova (cas) mutant zebrafish embryos lack endoderm and develop cardia bifida. In a substractive screen for Nodal-responsive genes, we isolated an HMG box-containing gene, 10J3, which is expressed in the endoderm. The cas phenotype is rescued by overexpression of 10J3 and can be mimicked by 10J3-directed morpholinos. Furthermore, we identified a mutation within 10J3 coding sequence that cosegregates with the cas phenotype, clearly demonstrating that cas is encoded by 10J3. Epistasis experiments are consistent with an instructive role for cas in endoderm formation downstream of Nodal signals and upstream of sox17. In the absence of cas activity, endoderm progenitors differentiate into mesodermal derivatives. Thus, cas is an HMG box-containing gene involved in the fate decision between endoderm and mesoderm that acts downstream of Nodal signals.

Amino Acid Sequence↗
PubMed2001

Identification of nodal signaling targets by array analysis of induced complex probes.

Nodal signaling controls germ layer formation, left-right asymmetry, and patterning of the brain in the vertebrate embryo. Cellular responses to Nodal signals are complex and include changes in gene expression, cell morphology, and migratory behavior. Only little is known about the genes regulated by Nodal signaling. We designed a subtractive screening strategy by using a constitutively active Nodal receptor to identify putative target genes of Nodal signals in the early gastrula of zebrafish embryos. By quantitative analysis of macro-array hybridizations, 132 genes corresponding to 1.4% of genes on the entire macro-array were identified, which were enriched in the Nodal-induced probe pool. These genes encode components of signal transduction pathways, transcription regulators, proteins involved in protein metabolism but also cytoskeletal components and metabolic enzymes, suggesting dramatic changes of cell physiology in gastrula cells in response to Nodal signals.

Animals↗
PubMed2001

Expression of brain subtype creatine kinase in the zebrafish embryo.

Creatine kinases (CK) play crucial roles in intracellular energy transfer. We have isolated a cDNA from zebrafish embryos, which encodes a CK highly related to the mammalian brain subtype creatine kinase (BCK). The bck mRNA is expressed maternally in the zebrafish embryo and transcripts are distributed uniformly in blastula and gastrula stages. Expression becomes restricted to the prechordal plate and the nervous system during subsequent somitogenesis stages. bck transcripts are abundant in primary neurons in the developing central nervous system of the 1-day-old embryo. While some bck expression persists in the hindbrain, expression vanishes in the spinal cord of the 2-day-old embryo. In summary, the expression pattern of bck is highly dynamic and suggests a role for bck during gastrulation and neuronal differentiation.

Amino Acid Sequence↗
PubMed2001

Structure-function analysis of the EGF-CFC family member Cripto identifies residues essential for nodal signalling.

Cripto is the founding member of the family of EGF-CFC genes, a class of extracellular factors essential for early vertebrate development. In this study we show that injection of Cripto recombinant protein in mid to late zebrafish Maternal-Zygotic one-eyed pinhead (MZoep) blastulae was able to fully rescue the mutant phenotype, thus providing the first direct evidence that Cripto activity can be added extracellularly to recover oep-encoded function in zebrafish early embryos. Moreover, 15 point mutations and two deletion mutants were generated to assess in vivo their functional relevance by comparing the ability of cripto wild-type and mutant RNAs to rescue the zebrafish MZoep mutant. From this study we concluded that the EGF-CFC domain is sufficient for Cripto biological activity and identified ten point mutations with a functional defective phenotype, two of which, located in the EGF-like domain, correspond to loss-of-function mutations. Finally, we have developed a three-dimensional structural model of Cripto protein and used it as a guide to predict amino acid residues potentially implicated in protein-protein interaction.

Amino Acid Sequence↗
PubMed2000

Coregulation of anterior and posterior mesendodermal development by a hairy-related transcriptional repressor.

During embryonic development in vertebrates, the endoderm becomes patterned along the anteroposterior axis to produce distinct derivatives. How this regulation is controlled is not well understood. We report that the zebrafish hairy/enhancer of split [E(spl)]-related gene her5 plays a critical role in this process. At gastrulation, following endoderm induction and further cell interaction processes including a local release of Notch/Delta signaling, her5 expression is progressively excluded from the presumptive anterior- and posteriormost mesendodermal territories to become restricted to an adjacent subpopulation of dorsal endodermal precursors. Ectopic misexpressions of wild-type and mutant forms of her5 reveal that her5 functions primarily within the endodermal/endmost mesendodermal germ layer to inhibit cell participation to the endmost-fated mesendoderm. In this process, her5 acts as an active transcriptional repressor. These features are strikingly reminiscent of the function of Drosophila Hairy/E(spl) factors in cell fate decisions. Our results provide the first model for vertebrate endoderm patterning where an early regulatory step at gastrulation, mediated by her5 controls cell contribution jointly to the anterior- and posteriormost mesendodermal regions.

Amino Acid Sequence↗
PubMed2000

Portable data acquisition system for EKG measurements in marine environments.

In the present paper, an electronic prototype designed to acquire electrocardiographic signals from marine mammals has been developed. The system consists of a portable device that allows the on-line acquisition of EKG signals through a parallel port interface that is connected to a laptop computer. The EKG waveform, the voltage level, the bandwidth and the most relevant information from this type of signals is stored and analysed under real-time conditions by means of specifically implemented software. The whole system has been successfully tested to obtain the EKG from captive dolphins. The characteristics of the equipment presented here, with its low cost, size and energy requirements accomplish a portable system suitable for the acquisition of this type of signals in conductive media such as the seawater.

Animals↗
PubMed2000

The ventralizing activity of Radar, a maternally expressed bone morphogenetic protein, reveals complex bone morphogenetic protein interactions controlling dorso-ventral patterning in zebrafish.

In Xenopus and zebrafish, BMP2, 4 and 7 have been implicated, after the onset of zygotic expression, in inducing and maintaining ventro-lateral cell fate during early development. We provide evidence here that a maternally expressed bone morphogenetic protein (BMP), Radar, may control early ventral specification in zebrafish. We show that Radar ventralizes zebrafish embryos and induces the early expression of bmp2b and bmp4. The analysis of Radar overexpression in both swirl/bmp2b mutants and embryos expressing truncated BMP receptors shows that Radar-induced ventralization is dependent on functional BMP2/4 pathways, and may initially rely on an Alk6-related signaling pathway. Finally, we show that while radar-injected swirl embryos still exhibit a strongly dorsalized phenotype, the overexpression of Radar into swirl/bmp2b mutant embryos restores ventral marker expression, including bmp4 expression. Our results suggest that a complex regulation of different BMP pathways controls dorso-ventral (DV) patterning from early cleavage stages until somitogenesis.

Alleles↗
PubMed2000

Central conduction time of magnetic brain stimulation in attention-deficit hyperactivity disorder.

Twenty-seven children and adolescents aged 4 to 18 years, fulfilling the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria for attention-deficit hyperactivity disorder, were included in this study. The diagnosis was determined by a pediatric neurologist and a psychologist examined all 27 subjects with tests that included the Wechsler Intelligence Scale for Children-Revised (WISC-R) and reading, writing, handedness, personality, and anxiety scores. Subjects with histories of epilepsy, head injury, drug abuse, or psychotic disorders were excluded. Culturally based causes or emotional disorders were also excluded. Transcranial magnetic stimulation was performed on all subjects, with recording of the motor evoked potential at the biceps brachii. Central motor conduction time was calculated by cervical root stimulation. Due to shape variability, the amplitude of the motor responses was not measured in the study. The mean value of central conduction time in the subjects was very significantly increased (P < .001) compared to that in a group of normal controls, case-matched for IQ, age, and sex. A central motor conduction time greater than 12 ms indicates abnormality. A second finding in the subjects was the significant difference of central conduction time on the side-to-side stimulation (P = .03). These findings are correlated with delay in the maturation of the corticomotoneuronal system and might provide neurophysiologic data for diagnosis.

Adolescent↗
PubMed1999

Databases in the assessment of the effects of drugs during pregnancy.

There is limited information on the effects of marketed drugs in pregnant women, largely because premarketing studies are not conducted in this population unless the agent is intended for specific use during pregnancy. Current information on the use of available medications during pregnancy includes 3 types of data: (1) case reports, (2) case-control studies, and (3) cohort studies. Assessments of pregnancy risk related to medication use most commonly involve case reports, and each year the Food and Drug Administration catalogs approximately 1000 suspected adverse drug experiences during pregnancy. The Food and Drug Administration, working with Michigan Medicaid, has developed a database of several hundred thousand pregnancy outcomes. Results of this study for asthma medications used between 1980 and 1992 are presented. However, interpretation of the results is complicated, and substantially more data are required, particularly as new medications become available.

Asthma↗
PubMed1998

Conversion of zebrafish blastomeres to an endodermal fate by TGF-beta-related signaling.

The endoderm contributes cells to the gut, and participates in the induction and patterning of the vertebrate head and heart. The mechanisms controlling the formation of endoderm are poorly understood. Commitment of endoderm cells occurs at the onset of gastrulation and requires cell interactions; studies in vitro have implicated transforming growth factor Beta (TGF-beta)-related molecules in this process. TARAM-A is a zebrafish receptor kinase that is related to the type I subunit of the TGF-beta receptor, and is expressed in presumptive endomesodermal cells at gastrulation. We provide here evidence for its involvement in endoderm formation in vivo. Activation of TARAM-A was found to drive blastomeres towards an endodermal fate. The induced endoderm behaved ad endogenous endoderm during gastrulation: it migrated in contact with the yolk and expressed endoderm-specific markers. Loss-of-function mutations in the zebrafish one-eyed-pinhead (OEP) gene lead to defects in heart formation, defects of the ventral central nervous system (CNS) and cyclopia. Mutant embryos also lack endoderm and anterior mesoderm. Endoderm formation in oep mutant embryos was found to be restored by the activation of the TARAM-A signaling pathway. Cardiac and ocular defects, but not midline CNS structures, were rescued non-autonomously, demonstrating that endoderm may provide signals that can pattern the eye anlage, and which are distinct form those specifying the ventral midline of the CNS.

Animals↗
PubMed1998

Vertebrate genome evolution and the zebrafish gene map.

In chordate phylogeny, changes in the nervous system, jaws, and appendages transformed meek filter feeders into fearsome predators. Gene duplication is thought to promote such innovation. Vertebrate ancestors probably had single copies of genes now found in multiple copies in vertebrates and gene maps suggest that this occurred by polyploidization. It has been suggested that one genome duplication event occurred before, and one after the divergence of ray-finned and lobe-finned fishes. Holland et al., however, have argued that because various vertebrates have several HOX clusters, two rounds of duplication occurred before the origin of jawed fishes. Such gene-number data, however, do not distinguish between tandem duplications and polyploidization events, nor whether independent duplications occurred in different lineages. To investigate these matters, we mapped 144 zebrafish genes and compared the resulting map with mammalian maps. Comparison revealed large conserved chromosome segments. Because duplicated chromosome segments in zebrafish often correspond with specific chromosome segments in mammals, it is likely that two polyploidization events occurred prior to the divergence of fish and mammal lineages. This zebrafish gene map will facilitate molecular identification of mutated zebrafish genes, which can suggest functions for human genes known only by sequence.

Animals↗
PubMed1997

Pharmacological modulation of the cardiovascular response to hypertonic NaCl injection in the anteroventral area of the rat brain third ventricle.

The anteroventral area of the rat brain third ventricle (AV3V) was stimulated by stereotaxically placed microinjections (1 microliter) of hypertonic 1.5 mol/l NaCl and the responses of mean arterial pressure (MAP) and heart rate (HR) were recorded. Previous injection of terazosin or propranolol (5.0 micrograms) into AV3V, 15 min before 1.5 mol/l NaCl microinjection, did not alter the cardiovascular response pattern induced by 1.5 mol/l NaCl. Prior AV3V treatment with ketanserin (1.0 microgram) significantly reduced (p < 0.01) the MAP and HR increase induced by 1.0 microliter of 1.5 mol/l NaCl without changing basal cardiovascular parameters. Prior AV3V treatment with losartan (10.0 micrograms) significantly reduced (p < 0.01) the hypertension and tachycardia induced by hypertonic NaCl administration. Thus, AV3V serotonin and angiotensin II-sensitive neurons may exert an excitatory role on blood pressure and HR involved with the sympathetic discharge produced by hypertonic NaCl stimulation.

Angiotensin I↗