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At least 595 records · Page 33Linked to original sources
PubMed2026

Genome agnostic, multi-level non-oncogene addiction-based systems pharmacology for rescuing metastatic relapsed/refractory neoplasias.

Rescue therapies for relapsed/refractory (r/r) metastatic neoplasias present significant unmet needs. Tumor tissue editing regimen for 13 r/r tumor types, carcinomas, sarcomas and hematologic neoplasias, included in 15 phase I/II trials, nuclear/cytokine receptor agonists, pioglitazone, plus/minus dexamethasone or all-trans retinoic acid or interferon-α to counterbalance tumor tissue homeostasis and reprogramming of cancer hallmarks, stress response inhibitors, COX-2 inhibitor, everolimus, lenalidomide, or clarithromycin, and a stress response inducer, low-dose metronomic chemotherapy with treosulfan, trofosfamide, capecitabine, or azacitidine. CR in three, cCR in another five r/r neoplasias, as the best response occurred after transcriptional reprogramming of cancer hallmarks, inflammation control or differentiation induction. Receptor agonist combinations for cCR induction can be identical among quite different tumor types and diversified within the same tumor histology. Data reveal ubiquitous, differential transcriptional access to non-oncogene addiction (NOA) networks that cope with cancer hallmarks/stress responses and three levels of therapeutic NOA targeting. (1) Agonists of nuclear/cytokine receptor NOAs critically target tumor identity and viability, while (2) transcriptional reprogramming of NOA networks that contribute to tumor tissue addiction, thereby genome-agnostically counteracting oncogene addictions. (3) Targeting edited NOAs may improve long-term outcome with CR/cCR (everolimus, IMiD). Transcriptionally accessible NOA targets offer high specificity, modest toxicity profile, low cost of therapy and outpatient treatment, independent of comorbidities. Adaptive targeting of the transcriptomic landscapes of tumor cell compartments breaks tumor tissue addiction and overcomes M-CRAC, post-therapy metastasis, cancer cell recolonization, acquired resistance and genetic heterogeneity. Thus, editing approaches provide a template for controlling metastatic r/r tumors. In the future, diagnostics of NOA networks and transcription factors involved in tumor tissue addiction may be as valuable for therapy selection as histological/molecular genetic tumor typing for the establishment of personalized hematology/oncology.

Hodgkin’s lymphoma↗
PubMed2026

Extravascular coagulation stabilizes pro-fibrotic stromal states via tumor-intrinsic PAR1 signaling in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) exhibits a desmoplastic stroma with context-dependent tumor-restraining and tumor-promoting functions, highlighting the need to selectively reprogram stromal states. Extravascular coagulation is a prominent feature of the PDAC tumor microenvironment, yet whether it functions as an upstream regulator of fibrotic stromal states, rather than merely a byproduct of tumor-associated vascular dysfunction, has remained unclear. Here, we identify extravascular coagulation as a tumor-amplified regulatory module that stabilizes pro-fibrotic stromal states via tumor-intrinsic protease-activated receptor-1 (PAR1) signaling. To interrogate this axis mechanistically, we integrated human tumor bioinformatics with microphysiological tumor-stroma (MPTS) models that reconstruct tumor-stroma interactions under controlled coagulation exposure, followed by cross-scale validation in vivo. Analysis of The Cancer Genome Atlas (TCGA) revealed heterogeneous F2R (PAR1) expression across tumors, with elevated expression associated with fibrotic transcriptional programs and reduced survival. Consistently, thrombin induced coordinated pro-fibrotic programs in tumor cells and cancer-associated fibroblasts (CAFs), which were recapitulated in MPTS where tumor-intrinsic PAR1 was required for amplification of extracellular matrix deposition and CAF activation. Mechanistically, PAR1 signaling amplified tumor-stroma communication, in part through induction of TGF-β1-dependent pathways, establishing a reinforcing feedback loop that stabilizes fibrotic remodeling. Pharmacologic inhibition of PAR1 selectively suppressed the fibrotic transcriptional program within myofibroblastic CAFs while reducing the abundance of other CAF subtypes, reprogramming stromal states and attenuating tumor progression across MPTS and in vivo models. These findings establish a coagulation-PAR1 axis as an upstream organizer of PDAC stromal architecture and identify pharmacologic PAR1 inhibition as a mechanistically grounded strategy for selectively reprogramming the tumor-promoting stroma.

Journal Article↗
PubMed2003

[Effects of 50 to 60 Hz and of 20 to 50 kHz magnetic fields on the operation of implanted cardiac pacemakers].

UNLABELLED: The effect of 50 Hz and 60 Hz (frequencies of current distribution) and 20 kHz to 50 kHz (frequencies of induction cooktop) magnetic interference on implanted pacemakers have been assessed with the present generation of device technology. Sixty patients implanted in 1998 and 1999 with dual chamber pacemakers from 9 different manufacturers were monitored with telemetry while passing through, and standing between a system of two coils. They generated a 50 Hz or a 60 Hz magnetic field at 50 microT. Then, patients used a cooktop at different power. The recordings were made with the standard setting of "medically correct" sensing parameters chosen for the patients. Then pacemakers were reprogrammed to the unipolar mode, with the highest atrial (A) and ventricular (V) sensitivity that did not induce muscular inhibition while moving. Between each exposure (50 Hz, 60 Hz or 20 kHz to 50 kHz), the pacemaker programmation was controlled. At the end of the tests, pacemakers will be reprogrammed with the standard setting. The medical observer being blind to the existence or not of the magnetic field. No pacemaker was influenced by the vicinity of the magnetic field at medically correct settings. At unipolar high sensitivity, no inhibition nor reprogramming was observed. Transient reversion to interference mode was observed in 6 cases, 3 transient acceleration due to atrial detection of the interference, and one T wave detection by the ventricular lead. All were observed with the 60 Hz, and only 3 with the 50 Hz magnetic field. One device (Biotronik) shifted out of its special program (hysteresis research) during the tests with the induction cooktop, but it maintained its standard program, and the event could not be repeated despite further testing. CONCLUSION: Actual pacemakers do not present any electromagnetic interference with 50 Hz and 60 Hz or induction cooktop frequency working. They are insensitive with medically correct settings. Unusual high sensitivity leads only to noise reversion mode, or transient ventricular tracking.

Dose-Response Relationship, Radiation↗
PubMedDate not supplied

[Aging and limited capacity for division of normal, diploid amphibian fibroblasts in vitro in relation to cell nucleus transplantations in amphibia].

In many experiments Hayflick had proved the limited division capacity of lung fibroblasts derived from different mammalian species, chicken and tortoise. Gurdon transplanted the nuclei of differentiated Xenopus cells into enucleated eggs yielding a complete development of the hybrid individuals. These results arise the question about a reprogramming of cell nuclei concerning their division capacity. On the other hand, amphibian cells may not show any proliferative limit. Thus, primary cultures were established from tadpoles, recently metamorphosed frogs and adult animals, respectively. The latent period of the tissue explants proved to be dependent on donor age. The cell strain I401 showed the characteristic degeneration phenomena after six subcultivations and ceased to proliferate. These results lead to the conclusion that nuclear transplantation into an enucleated egg yields reprogramming of the nucleus, including the reprogramming of the division capacity as much as the biological age of the nucleus.

Animals↗
PubMed1983

Early experience with a universal (DDD) pacing device.

To assess the advantages and complications of a new universal (DDD) pacemaker, we studied retrospectively the initial 38 patients who received such a pacing device. This group consisted of 27 men and 11 women whose ages ranged from 23 to 89 years. The pacemaker was the initial one for 32 patients and was the replacement unit for 6. Indications for dual-chamber pacing included a need to maintain atrioventricular synchrony, the previous occurrence of the pacemaker syndrome or the presence of intact ventriculoatrial conduction, and previous success with atrioventricular sequential pacing. Pacemaker-mediated tachycardia developed in six patients during the follow-up period. All six were successfully treated by a change in pacing mode. Eighteen pacemakers remained in the DDD mode, 17 were reprogrammed to the DVI mode, and 3 were reprogrammed to the VVI mode. Seven patients experienced difficulties with loss of capture or undersensing, the most common problem being failure of atrial sensing. This was corrected in four of five patients by noninvasive reprogramming. Pacemaker-mediated tachycardia is a frequent complication that can be avoided by assessing ventriculoatrial conduction before implantation of the pacemaker. Use of the DDD device should be considered in patients in whom atrioventricular synchrony must be maintained or who have previously had the pacemaker syndrome with VVI pacing.

Adult↗
PubMedDate not supplied

Long term performance of atrial leads.

Long term performance of 163 atrial leads implanted in 158 patients between July 1981 and June 1993 was evaluated. There were 122 DDD and 36 AAI units, with 125 (77%) polyurethane and 38 (23%) silicone leads. One hundred and nine (67%) unipolar and 54 (33%) bipolar leads were used. Patients were followed in the Pacemaker Clinic for 6 to 124 months (mean 50 +/- 39 months). Five patients were lost to follow up. Transient malfunction was observed in 18 cases (sensing 13, pacing 5) within the first 2 weeks. In 13 cases failure to sense subsided spontaneously and in 4 pacing malfunction could be corrected by reprogramming. Lead dislodgement occurred in 4 patients (2.5%), all within the first week. After the 1st month malfunction was uncommon. Between 1 and 12 months undersensing occurred in 4 (2.5%). In 3 cases it could be corrected by reprogramming. In the first year, reoperation was performed in 5 cases for lead related problems (3 dislodgements, 2 insulation failures). Beyond 12 months complications were as follows: failure to sense-8 (5%), failure to pace-3 (2%), insulation break -1 (0.6%). Majority of these problems could be managed by reprogramming. Reoperation was performed in 1 case with insulation break. The pacing mode had to be changed in 5 (3%) patients with dual chamber units who had loss of P wave sensing. During follow-up 98%, 98%, 96%, 95% and 83% of the leads were working satisfactorily at 1,2,3,4 and 9 years respectively. Thus atrial leads have excellent long term performance and an acceptable rate of late malfunction.

Adolescent↗
PubMed2026

Proteomic signatures of adipocyte recruitment in breast cancer.

The tumor microenvironment (TME) is increasingly recognized as a dynamic regulator of breast cancer progression, with adipocytes functioning as active contributors rather than passive bystanders. Here, we investigated the proteomic and morphologic reprogramming of breast cancer-associated adipocytes (BrCAAs) in response to triple-negative breast cancer (TNBC). Using conditioned medium from HCC1143 cells, we established an in vitro BrCAA model and performed mass spectrometry-based proteomics. Comparative profiling revealed 256 differentially expressed proteins, enriched for pathways including fatty acid degradation, carbon metabolism, and glycogen turnover, consistent with a metabolic shift from energy storage to energy supply. Gene ontology and protein-protein interaction analyses further identified cytoskeletal remodeling, adhesion dynamics, and secretory pathway activation, supporting BrCAA-driven microenvironmental remodeling. In the MMTV-PyMT mouse model, morphometric analysis demonstrated progressive size reduction and increased contour irregularity of adipocytes adjacent to tumors, correlating with proteomic evidence of metabolic stress. Importantly, BrCAAs localized at tumor interfaces were associated with increased microvessel density and CD105+ endothelial activation compared to desmoplastic zones. Proteomic enrichment highlighted pro-angiogenic remodeling, with validation of basigin (BSG), integrin αV (ITGAV), and 2,4-dienoyl-CoA reductase 1 (DECR1). Collectively, our findings establish BrCAAs as metabolically and structurally reprogrammed stromal components that promote tumor metabolism and localized angiogenesis, representing potential therapeutic targets in aggressive breast cancer.

Female↗
PubMed2026

Efferocytosis regulatory factors in atherosclerosis: A preclinical systematic review.

BACKGROUND: Impaired efferocytosis is a key driver of plaque instability during atherosclerosis progression. Efficient clearance of apoptotic cells through efferocytosis relies on the coordinated action of multiple regulatory factors. METHODS: PubMed, Web of Science, ScienceDirect, OVID MEDLINE, and Scopus were searched for studies published up to February 7, 2026. Eligible preclinical studies were systematically reviewed to identify endogenous factors that regulate efferocytosis in atherosclerosis. Clinical evidence was also incorporated to enable a preliminary translational assessment of these regulatory factors. RESULTS: Thirty-five endogenous regulatory factors were identified from 36 included studies, and their functional roles across distinct stages of efferocytosis were characterized. Notably, metabolic regulators such as PKM2, PFKFB3, GLS1, and Drp1 were involved in distinct efferocytosis stages. This suggests that metabolic reprogramming may provide the metabolic support require for efficient efferocytosis and inflammation resolution. Ten factors were supported by preliminary clinical evidence consistent with preclinical data. PKM2 was the only candidate biomarker with prospective observational data. However, its independent predictive value still requires validation in multicenter prospective studies. CONCLUSIONS: This review provides a systematic synthesis of 35 endogenous efferocytosis regulators and elucidates their regulatory network in atherosclerosis based on a functional stage framework. Metabolic reprogramming is identified as a central hub linking efferocytosis efficiency to inflammation resolution. This review offers a new theoretical basis for efferocytosis-targeted intervention strategies.

Animals↗
PubMed2026

Maternal transfer of nonylphenol drives oxidative, immune, and epigenetic dysregulation in zebrafish offspring.

Nonylphenol (NP), a widespread surfactant and endocrine-disrupting pollutant, poses significant ecological and public health risks globally; however, its transgenerational effects remain poorly understood. Using zebrafish (Danio rerio), we compared chronic maternal NP exposure (50 and 100 µg/L, 28 days) with acute embryonic exposure (0.22 µmol/L) during 0-3 days post-fertilization (dpf) to delineate mechanistic differences in toxicity. Maternal NP exposure produced severe developmental defects in offspring, including edema, axial curvature, impaired swim bladder inflation, reduced growth, cardiac dysfunction, and decreased viability. These phenotypes were accompanied by systemic molecular disruptions including oxidative stress, altered estrogen receptor (ER) expression, dysregulated mitogen-activated protein kinase (MAPK) signaling, and suppressed innate immune response characterized by attenuated neutrophil/macrophage density, reduced CD68 and complement protein C3 expression, diminished nitrite load, and downregulation of pro-inflammatory mediators at both transcript and protein levels. Maternal exposure further induced apoptosis and persistent epigenetic reprogramming (alterations in DNA methylation and histone-modifying enzymes), hallmarks of transgenerational toxicity. In contrast, direct embryonic NP exposure elicited morphological abnormalities without significant lethality, accompanied by induction of pro-inflammatory cytokines, nitric oxide (NO) synthesis, and MAPK activation, reflecting an augmented inflammatory response. These mechanistic contrasts reveal that maternal NP exposure is a potent driver of systemic, heritable molecular reprogramming, whereas embryonic exposure triggers acute inflammatory pathways. Together, our findings underscore the global relevance of NP as a transgenerational toxicant, advocating for its urgent inclusion in ecotoxicological risk assessments and regulatory frameworks.

Animals↗
PubMed2026

Matrix Mechanics Governs Mechano-Metabolic Adaptation across Cancer Grades in Bladder Spheroids.

Extracellular matrix (ECM) mechanics is pivotal regulators of tumor progression, yet how viscoelasticity and matrix architecture converge to shape metabolic and invasive adaptation remains insufficiently defined. We postulate that mechanical stimuli from the ECM induce coordinated changes in adhesive and metabolic pathways, and that the nature of this independent mechano-metabolic pathway is conserved across benign, low-invasive, and high-invasive bladder cancer phenotypes. Therefore, we engineered collagen-hyaluronan hydrogels with tunable stiffness to recapitulate soft and rigid tumor microenvironments and profiled bladder cancer spheroids representing benign, low-invasive, and highly invasive states. Integrating hydraulic force spectroscopy, rheology, and molecular phenotyping, we show that matrix stiffening differentially reprograms spheroid architecture, motility, and adhesion- and metabolism-related gene expression. Spheroid behavior emerged from the interplay between intrinsic mechanical properties, matrix rheology, and molecular adaptation. HCV29 spheroids formed rigid, compact structures, relying on cell-matrix adhesion rather than metabolic or proteolytic remodeling. HT1376 spheroids activated glycolysis (HK2) and MMP-2-dependent ECM remodeling in soft matrices, but remained largely nonmigratory, indicating decoupling of invasive priming from motility. T24 spheroids were soft, deformable, and highly migratory in compliant matrices, integrating metabolic reprogramming, adhesion remodeling (E-/N-cadherin, SDC4), and radial collagen fiber alignment to drive invasion. Notably, canonical FAK/AKT/mTOR signaling was absent across all spheroids, while pS6 ribosomal protein and ILK indicated noncanonical, SDC4/integrin-ILK-dependent mechanotransduction supporting cytoskeletal dynamics, metabolism, and ECM remodeling. Collagen organization further differed across spheroid types, with dense, radially aligned fibers in HT1376, intermediate architecture in HCV29, and loose, disorganized networks in T24, closely matching their distinct migratory behaviors and cell-ECM interactions. These findings reveal stage-specific mechanometabolic strategies in bladder cancer, demonstrating how ECM mechanics and architecture jointly guide invasion, metabolic adaptation, and local immune modulation, including the regulation of immune cell infiltration and tumor immune evasion.

Humans↗
PubMed2026

Multimodal Analysis Reveals Aberrant Expression of SUMO2 and Its Significant Association With Key Mechanisms of Metabolic Pathways in Hepatocellular Carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide. However, the role of small ubiquitin-like modifier 2 (SUMO2), a core member of the small ubiquitin-like modifier (SUMO) family, regarding its expression patterns and metabolism-related functions in HCC remains inadequately understood. METHODS: A multidimensional analytical framework was applied, integrating immunohistochemistry (153 HCC vs. 21 non-HCC samples), proteomics (159 paired samples), bulk transcriptomics (3240 HCC vs. 2267 non-HCC samples), single-cell RNA sequencing (RNA-seq) (10 HCC vs. 8 non-HCC samples), spatial transcriptomics, and external CRISPR/Cas9 functional genomics data. Systematic analyses included standardized mean difference (SMD), pathway enrichment, pseudotime trajectory inference, in silico knockout, cell-cell communication, metabolic flux scoring, immune infiltration, clinical correlation, drug sensitivity prediction, and molecular docking. RESULTS: At the protein level, immunohistochemistry (nuclear positivity) and external proteomic data collectively demonstrated consistent SUMO2 overexpression in HCC. Consistent upregulation was also observed at the mRNA level across large-scale cohorts. Single-cell RNA-seq and spatial transcriptomics localized SUMO2 enrichment to malignant hepatocytes and tumor-dominant regions. CRISPR-mediated SUMO2 knockout suppressed proliferation in multiple HCC cell lines. Mechanistically, high SUMO2 expression was significantly associated with metabolic reprogramming involving glycolysis/gluconeogenesis, pyruvate metabolism, and the tricarboxylic acid cycle. SUMO2-high malignant hepatocyte subpopulations exhibited enhanced activity of the macrophage migration inhibitory factor signaling axis and enhanced iron-sensor interactions. Further, the immune infiltration analysis revealed a negative correlation between SUMO2 expression and M1 macrophages and a positive correlation between follicular helper T cells and regulatory T cells. Clinically, elevated SUMO2 levels were found to be associated with adverse prognostic features. Furthermore, high SUMO2 expression was associated with increased sensitivity to dasatinib, and molecular docking simulations predicted potential binding between SUMO2 and dasatinib, with a Vina score of -8.5 kcal/mol. CONCLUSIONS: SUMO2 is aberrantly expressed at the protein, mRNA, single-cell, and spatial transcriptomic levels in HCC and is significantly associated with metabolic reprogramming and altered migration inhibitory factor (MIF)-mediated intercellular communication, suggesting its potential as a novel biomarker for diagnosis and treatment.

Humans↗
PubMed2026

Induced Pluripotent Stem Cells in Non-Model Species: Applications and Challenges.

Induced pluripotent stem cells have revolutionized biomedical research-yet the vast majority of life on Earth remains beyond their reach. Non-model species lack the annotated genomes, validated reagents, and species-specific culture infrastructure that make iPSC technology routine in humans and mice, and this infrastructure deficit, compounded by genuine biological differences in pluripotency network architecture across taxa, is what has kept the field narrow. The deep conservation of the core pluripotency network across vertebrates suggests that reprogramming may, in principle, be achievable across a far broader range of species than currently demonstrated-though the extent to which this holds across more divergent taxa remains to be established. This review consolidates current progress and future potential of iPSC technology across five domains: technical reprogramming challenges and advances; conservation applications including genetic rescue, in vitro gametogenesis, and de-extinction; medical applications within a one medicine framework; agricultural applications spanning disease resistance, climate resilience, and cultured meat; and species-specific iPSC-derived systems in ecotoxicology. Throughout, we distinguish what has been demonstrated from what remains aspirational and identify the priorities that will determine whether the iPSC revolution can be extended-rigorously and at scale-beyond model organism research.

Induced Pluripotent Stem Cells↗
PubMed2026

Enzyme-Metabolite Network Analysis of Endometrial Cancer-Derived Extracellular Vesicles Through Integrated Proteomics and Metabolomics.

Endometrial cancer (EC) is the most common gynecological malignancy in high-income countries. Extracellular vesicles (EVs) are key mediators of intercellular communication and metabolic reprogramming, but their molecular cargo in EC remains poorly characterized. EVs were isolated from four EC cell lines representing Type I and Type II subtypes (AN3CA, ISHIKAWA, HEC1A, and KLE). Untargeted metabolomics was performed by HILIC-LC-MS/MS, proteomics by data-independent acquisition (DIA) mass spectrometry, and multi-omics integration using MetaboAnalyst and OmicsNet. Metabolomic profiling identified 1463 annotated features and revealed significant differences among EC cell lines (PERMANOVA, p = 0.002). Twenty-eight differentially abundant metabolites, including lactic acid, succinic acid, and uric acid, were identified. Proteomic analysis quantified 8513 proteins with subtype-specific expression patterns. Integrated analysis revealed seven significantly enriched pathways, including glycolysis/gluconeogenesis, central carbon metabolism in cancer, and the pentose phosphate pathway. Increased LDHA abundance in metastatic AN3CA-derived EVs was confirmed by Western blot (p = 0.047). EC-derived EVs display subtype- and metastatic-status-specific metabolo-proteomic signatures, with glycolysis, TCA cycle remodeling, and central carbon metabolism as convergent pathway signatures of molecular reprogramming. These findings establish a multi-omics framework for characterizing EV cargo in EC and identify candidate enzyme-metabolite nodes for future biomarker validation in patient-derived specimens.

Female↗
PubMed1997

Regulation of gene expression in the preimplantation mouse embryo: temporal and spatial patterns of expression of the transcription factor Sp1.

Activation of the embryonic genome during preimplantation mouse development entails a dramatic reprogramming of the pattern of gene expression. The complement of transcription factors that are present in the early embryo and that must intrinsically be involved in this reprogramming is essentially uncharacterized. We and others have demonstrated that transcription factor Sp1 is present in the mouse oocyte and early cleavage stage preimplantation embryo. Due to Sp1's prominent role in regulating the expression of a vast array of genes that are involved in cell proliferation and differentiation, as well as in general housekeeping functions, we characterized the temporal and spatial patterns of Sp1 expression during preimplantation development. The relative abundance of Sp1 transcripts, as well as transcripts for the TATA box-binding protein TBP, decreases during oocyte maturation and reaches a minimum level in the two-cell stage, after which time the abundance of these transcripts increases progressively to the blastocyst stage. Immunoblotting experiments detect Sp1 species of Mr = 95,000 and 105,000 at all stages of preimplantation development. The amount of Sp1 increases about 8-fold during preimplantation development, and an alpha-amanitin-insensitive increase is observed between G1 and G2 of the one-cell embryo; this increase may reflect the mobilization of a maternal Sp1 transcript. Immunocytochemical experiments also reveal a similar increase in the amount of Sp1 during preimplantation; the nuclear concentration of Sp1 is greater in the trophectoderm cells than in the inner cell mass cells. Finally, gel-shift experiments document an increase during preimplantation development of a DNA-binding activity that is likely due to Sp1. These increases in the abundance of the Sp1 protein and an Sp1-like DNA-binding activity parallel increases in the rate of transcription that occur during preimplantation development.

Animals↗
PubMed1999

Nucleolar ultrastructure in bovine nuclear transfer embryos.

Nuclear transfer experiments in mammals have attempted to reprogram a donor nucleus to a state equivalent to the zygotic one. Reprogramming of the donor nucleus is, among other features, indicated by a synthesis of ribosomal RNA (rRNA). The initiation of rRNA synthesis is simultaneously reflected in nuclear morphology as a transformation of the nucleolus precursor body into a functional rRNA synthesising nucleolus with a characteristic ultrastructure. We examined nucleolar ultrastructure in bovine in vitro produced (control) embryos and in nuclear transfer embryos reconstructed from a MII phase (nonactivated) or S phase (activated) cytoplasts. Control embryos were fixed at the two-, four-, early eight- and late eight-cell stages; nuclear transfer embryos were fixed at 1 and 3 hr post fusion and at the two-, four-, and eight-cell stages. Control embryos possessed a nucleolar precursor body throughout all three cell cycles. In the eight-cell stage embryo, a primary vacuole appeared as an electron lucid area originating in the centre of the nucleolar precursor body. In nuclear transfer embryos reconstructed from nonactivated cytoplasts, the nuclear envelope was fragmented or completely broken down at 1 hr after fusion and, by 3 hr after fusion, it was restored again. At this time, the reticulated fibrillo-granular nucleolus had an almost round shape. The nucleolar precursor body seen in the two-cell stage nuclear transfer embryos consisted of intermingled filamentous components and secondary vacuoles. A nucleolar precursor body typical for the two-cell stage control embryos was never observed. None of the reconstructed embryos of this group reached the eight-cell stage. Nuclear transfer embryos reconstructed from activated cytoplasts, in contrast, exhibited a complete nuclear envelope at all time intervals after fusion. In the two-cell stage nuclear transfer embryo, the originally reticulated nucleolus of the donor blastomere had changed into a typical nucleolar precursor body consisting of a homogeneous fibrillar structure. A primary vacuole appeared in the four-cell stage nuclear transfer embryos, which was one cell cycle earlier than in control embryos. Only nuclear transfer embryos reconstructed from activated cytoplasts underwent complete remodelling of the nucleolus. The reorganisation of the donor nucleolar architecture into a functionally active nucleolus was observed as early as in the four-cell stage nuclear transfer embryo. These ultrastructural observations were correlated with our autoradiographic data on the initiation of RNA synthesis in nuclear transfer embryos.

Animals↗
PubMed2001

DNA methylation and mammalian epigenetics.

Epigenetic modifications of DNA such as methylation are important for genome function during development and in adults. DNA methylation has central importance for genomic imprinting and other aspects of epigenetic control of gene expression, and during development methylation patterns are largely maintained in somatic lineages. The mammalian genome undergoes major reprogramming of methylation patterns in the germ cells and in the early embryo. Some of the factors that are involved both in maintenance and in reprogramming, such as methyltransferases, are being identified. Epigenetic changes are likely to be important in animal cloning, and influence the occurrence of epimutations and of epigenetic inheritance. Environmental factors can alter epigenetic modifications and may thus have long lasting effects on phenotype. Epigenetic engineering is likely to play an important role in medicine in the future.

Animals↗
PubMed1999

Planning and executing an action in Parkinson's disease.

We evaluated the possible impairment in planning and executing an action in patients with Parkinson's disease (PD). The action considered in the present study was formed by two successive motor acts: reaching-grasping an object (first target) and placing it on a second target of the same shape and size. We examined the effects of extrinsic properties of the second target (that is, distance) on the various kinematic phases of reaching-grasping movements. Distance, position, and size of both stimuli were randomly varied across the experimental session. Movements were executed with and without visual control of both targets and arm. The performance of six patients with PD was compared with an age-matched control group. The kinematics of the initial phase of reaching was influenced by position and size of the first target and by distance of the second target in both patients and control subjects. In particular, peak acceleration was higher for farther position of the second target. However, in the subsequent phase patients, differently from control subjects, removed the effects of the second target distance by modifying their reaching kinematics. This was obtained by varying the duration of the acceleration phase. In summary, the patients reprogrammed the reaching component by taking into account only the properties of the first target. The decreasing influence of second-target distance on reaching kinematics of patients was more evident during movements executed under visual control. Moreover, their movements executed without visual control were slowed down from the beginning. The second target affected the grasping kinematics only of the control subjects. Globally, these results indicate that PD patients are able to compute the general program of an action that takes into account extrinsic properties of the final target. However, the finding that PD patients reprogrammed the movement during its execution suggests a decay of the program during its time course, that is, basal ganglia can be involved in storing the plan of an action and in controlling its correct execution.

Adult↗
PubMed2004

Prolegomena to future experimental efforts on genetic code engineering by expanding its amino acid repertoire.

Protein synthesis and its relation to the genetic code was for a long time a central issue in biology. Rapid experimental progress throughout the past decade, crowned with the recently elucidated ribosomal structures, provided an almost complete description of this process. In addition important experiments provided solid evidence that the natural protein translation machinery can be reprogrammed to encode genetically a vast number of non-coded (i.e. noncanonical) amino acids. Indeed, in the set of 20 canonical amino acids as prescribed by the universal genetic code, many desirable functionalities, such as halogeno, keto, cyano, azido, nitroso, nitro, and silyl groups, as well as C=C or C[triple bond]C bonds, are absent. The ability to encode genetically such chemical diversity will enable us to reprogram living cells, such as bacteria, to express tailor-made proteins exhibiting functional diversity. Accordingly, genetic code engineering has developed into an exciting emerging research field at the interface of biology, chemistry, and physics.

Amino Acids↗