Cobalt containing glass fibres and their synergistic effect on the HIF-1 pathway for wound healing applications

Introduction and Methods: Chronic wounds are a major healthcare problem, but their healing may be improved by developing biomaterials which can stimulate angiogenesis, e.g. by activating the Hypoxia Inducible Factor (HIF) pathway. Here, novel glass fibres were produced by laser spinning. The hypothesis was that silicate glass fibres that deliver cobalt ions will activate the HIF pathway and promote the expression of angiogenic genes. The glass composition was designed to biodegrade and release ions, but not form a hydroxyapatite layer in body fluid.

Results and Discussion: Dissolution studies demonstrated that hydroxyapatite did not form. When keratinocyte cells were exposed to conditioned media from the cobalt-containing glass fibres, significantly higher amounts of HIF-1α and Vascular Endothelial Growth Factor (VEGF) were measured compared to when the cells were exposed to media with equivalent amounts of cobalt chloride. This was attributed to a synergistic effect of the combination of cobalt and other therapeutic ions released from the glass. The effect was also much greater than the sum of HIF-1α and VEGF expression when the cells were cultured with cobalt ions and with dissolution products from the Co-free glass, and was proven to not be due to a rise in pH. The ability of the glass fibres to activate the HIF-1 pathway and promote VEGF expression shows the potential for their use in chronic wound dressings.

Cobalt-containing bioactive glasses reduce human mesenchymal stem cell chondrogenic differentiation despite HIF-1α stabilisation

Bioactive glasses (BGs) are excellent delivery systems for the sustained release of therapeutic ions and have been extensively studied in the context of bone tissue engineering. More recently, due to their osteogenic properties and expanding application to soft tissue repair, BGs have been proposed as promising materials for use at the osteochondral interface. Since hypoxia plays a critical role during cartilage formation, we sought to investigate the influence of BGs releasing the hypoxia-mimicking agent cobalt (CoBGs) on human mesenchymal stem cell (hMSC) chondrogenesis, as a novel approach that may guide future osteochondral scaffold design. The CoBG dissolution products significantly increased the level of hypoxia-inducible factor-1 alpha in hMSCs in a cobalt dose-dependent manner. Continued exposure to the cobalt-containing BG extracts significantly reduced hMSC proliferation and metabolic activity, as well as chondrogenic differentiation. Overall, this study demonstrates that prolonged exposure to cobalt warrants careful consideration for cartilage repair applications.

Highly porous scaffolds of PEDOT:PSS for bone tissue engineering

Conjugated polymers have been increasingly considered for the design of conductive materials in the field of regenerative medicine. However, optimal scaffold properties addressing the complexity of the desired tissue still need to be developed. The focus of this study lies in the development and evaluation of a conductive scaffold for bone tissue engineering. In this study PEDOT:PSS scaffolds were designed and evaluated in vitro using MC3T3-E1 osteogenic precursor cells, and the cells were assessed for distinct differentiation stages and the expression of an osteogenic phenotype.

Ice-templated PEDOT:PSS scaffolds presented high pore interconnectivity with a median pore diameter of 53.6 ± 5.9 µm and a total pore surface area of 7.72 ± 1.7 m²·g⁻¹. The electrical conductivity, based on I-V curves, was measured to be 140 µS·cm⁻¹ with a reduced, but stable conductivity of 6.1 µS·cm⁻¹ after 28 days in cell culture media. MC3T3-E1 gene expression levels of ALPL, COL1A1 and RUNX2 were significantly enhanced after 4 weeks, in line with increased extracellular matrix mineralisation, and osteocalcin deposition. These results demonstrate that a porous material, based purely on PEDOT:PSS, is suitable as a scaffold for bone tissue engineering and thus represents a promising candidate for regenerative medicine.

Statement of Significance

Tissue engineering approaches have been increasingly considered for the repair of non-union fractions, craniofacial reconstruction or large bone defect replacements. The design of complex biomaterials and successful engineering of 3-dimensional tissue constructs is of paramount importance to meet this clinical need. Conductive scaffolds, based on conjugated polymers, present interesting candidates to address the piezoelectric properties of bone tissue and to induce enhanced osteogenesis upon implantation. However, conductive scaffolds have not been investigated in vitro in great measure. To this end, we have developed a highly porous, electrically conductive scaffold based on PEDOT:PSS, and provide evidence that this purely synthetic material is a promising candidate for bone tissue engineering.

Learning and generalization in cascade network architectures

Incrementally constructed cascade architectures are a promising alternative to networks of predefined size. This paper compares the direct cascade architecture (DCA) proposed in Littmann and Ritter (1992) to the cascade-correlation approach of Fahlman and Lebiere (1990) and to related approaches and discusses the properties on the basis of various benchmark results. One important virtue of DCA is that it allows the cascading of entire subnetworks, even if these admit no error-backpropagation. Exploiting this flexibility and using LLM networks as cascaded elements, we show that the performance of the resulting network cascades can be greatly enhanced compared to the performance of a single network. Our results for the Mackey-Glass time series prediction task indicate that such deeply cascaded network architectures achieve good generalization even on small data sets, when shallow, broad architectures of comparable size suffer from overfitting. We conclude that the DCA approach offers a powerful and flexible alternative to existing schemes such as, e.g., the mixtures of experts approach, for the construction of modular systems from a wide range of subnetwork types.

[Abnormal psychosocial development and legal responsibility--results of psychopathometric studies]

The introduction (1968) of the legal concept of Grave Abnormal Development of the Personality Amounting to a Disorder into the penal code, made possible criminal deculpation on the basis of psychosocial maldevelopment. On the basis of an intelligence- and personality-diagnostic test-battery (Psychopathometry), the findings obtained in the examination of a sample of culprits on probation under this legal provision, has been compared with a control group homogeneous in respect of the significant parameters. Psychopathometric methods can and should reasonably supplement expertises of this culprits with defective psychosocial development.

['Commitment-adequate' personality diagnosis using the Seitz (revised) Personality Questionnaire for Prisoners within the scope of forensic-psychologic-psychiatric expert assessment]

In this contribution, the necessity and expediency, but also the limits of the application of psychodiagnostic methods within the scope of forensic-psychological-psychiatric expertises are discussed. A survey is given on results of statistical analysis, revision and validation gained with a personality questionnaire relevant to prison situation (PFI acc. Seitz, 1983).

[Forensic-psychologic-psychiatric assessment from the viewpoint of perpetrators--data from a survey]

In this contribution, various aspects of the expert/culprit-relationship and of the communication behavior styles between the included persons within the scope of forensic-psychological-psychiatric expertise, are discussed. A survey is given on results gained with a questionnaire study (n = 93 culprits; Department of Forensic Psychiatry, Charité Berlin) of the most important expectations, of the social-relevant attitudes towards the assessment and physicians before the forensic investigation as well as of the experiences of own feelings, stress and of the culprit's reflections on the physician/proband relationship after the assessment. A good partnership relation between experts and culprits presupposes that the expert not only possesses a high profession but also the necessary interpersonal-social competence.

[Results of psychodiagnostic examinations in forensic-psychologically and psychiatrically evaluated criminals]

In this contribution, the necessity and expediency, but also the limits of the application of psychodiagnostic methods within the scope of forensic-psychological-psychiatric expertises are briefly discussed. On the basis of an intelligence and personality-diagnostic routine programme (RAVEN-PM, MWT-B; FPI, PpKV and Giessen test), the findings obtained in the examination of about 600 culprits who had been subjected to an expertise are presented. Test-psychological examination methods can and should reasonably supplement expertises in foro, but they will only gain their informative value and importance from the connection with the anamnesis, the content of the records, the exploration of the personality, of deed and deed experience of the person on whom expert opinion was given and the large range of neuropsychiatric diagnostic methods.

[Experiences and investigations with a Polish abbreviated form of the MMPI (DKO 74)]

Starting from a description of the advantages and weaknesses of the Minnesota multiphasic personality inventory (MMPI) test, the authors discuss the development, standardization, and normalization of an abbreviated form (DKO/74) which is used in Poland. Results of investigations made to determine the suitability of the method for establishing diagnoses, which included comparative examinations of various groups of Polish and G.D.R. patients (schizophrenics, neurotics, alcoholics, oncological subjects, and criminal offenders) as well as studies into factorial validity, are presented and show the test to be a suitable instrument for clinical and psychodiagnostic examinations.

[Relationship between (perceived) maternal rearing behavior and personality characteristics of behaviorally disturbed children and juveniles]

A survey of the literature on methodological problems associated with, and results of, the diagnosis of parental educational attitudes and practices as viewed and experienced especially by those receiving education is followed by a report on an investigation of the maternal educational behavior perceived by behaviorally disturbed children and juveniles of male sex. Correlative results obtained from the evaluation of questionnaires confirm the interrelation of disturbed (maternal) emotional relations to children and abnormal behavior shown by children. The inclusion in the diagnostic practice of reports given by those receiving education on the educational behavior shown by parents or other persons in whom the right of education is vested is considered to be a necessary and useful supplementary method.

[Psychodiagnosis of brain damage and brain damage sequelae in adults]

The author examines methodical problems of construction and validation, and the local value of psychological methods within the framework of neuropsychological diagnostics. He bases this examination on a characterization of the wide field of problems of psychological diagnostics when proving, bjectivizing, quantifying and describing psychic consequences of cerebro-organic conditioned functional lesions and their differential diagnostic delimitation with regard to other symptom images. He goes on to describe diagnostic aims, statement possibilities and the limitations of psychopathometric and psychopathognostic testing devices. Finally, more from pragmatic than from strictly theoretical aspects of neuropsychology, he gives an outline of a number of major psychodiagnostic processes commonly used in practice with a view to objecting and quantifying forms of performance and behavior resulting from cerebro-organic alterations, i.e. processes which definately occupy an equal place in the arsenal of methods employed by the neuropsychiatrist.

[On the problem of psychodiagnosis in psychiatry and psychotherapy]

Owing to the changed concept of psychiatry and psychotherapy, greater demands are also being made on psychodiagnostics. The article deals with the prerequisites, possible significance and application of the clinical methods and psychological tests, describes the problems of standardization and quality testing and discusses indications and problems of the different groups of methods. The demands of the clinician addressed to test designers are dealt with, as well as the question of which group of methods should be used and by whom.