Transgenic rabbit models for biomedical research: Current status, basic methods and future perspectives

The creation of genetically modified laboratory and livestock animals is one of the most dramatic advances derived from recombinant DNA technology. Over the past decade, the development of a large mammal transgenic model, transgenic rabbits, has provided unprecedented opportunities for investigators to study the mechanisms of human diseases and has also provided a novel way to produce foreign proteins for both therapeutic and commercial purposes. Recent progress in gene targeting and animal cloning has opened new avenues for production of transgenic rabbits. In this review, we will introduce the reader to the progress that has been achieved in transgenic rabbits with emphasis on the application of these rabbits as human disease models and bioproducers of human therapeutic proteins.     

Latest developments in gene transfer technology: achievements, perspectives, and controversies over therapeutic applications

Over the last decade, more than 300 phase I and phase II gene-based clinical trials have been conducted worldwide for the treatment of cancer and monogenic disorders. Lately, these trials have been extended to the treatment of AIDS and, to a lesser extent, cardiovascular diseases. There are 27 currently active gene therapy protocols for the treatment of HIV-1 infection in the USA. Preclinical studies are currently in progress to evaluate the possibility of increasing the number of gene therapy clinical trials for cardiopathies, and of beginning new gene therapy programs for neurologic illnesses, autoimmuno diseases, allergies, regeneration of tissues, and to implement procedures of allogeneic tissues or cell transplantation. In addition, gene transfer technology has allowed for the development of innovative vaccine design, known as genetic immunization. This technique has already been applied in the AIDS vaccine programs in the USA. These programs aim to confer protective immunity against HIV-1 transmission to individuals who are at risk of infection. Research programs have also been considered to develop therapeutic vaccines for patients with AIDS and generate either preventive or therapeutic vaccines against malaria, tuberculosis, hepatitis A, B and C viruses, influenza virus, La Crosse virus, and Ebola virus. The potential therapeutic applications of gene transfer technology are enormous. However, the effectiveness of gene therapy programs is still questioned. Furthermore, there is growing concern over the matter of safety of gene delivery and controversy has arisen over the proposal to begin in utero gene therapy clinical trials for the treatment of inherited genetic disorders. From this standpoint, despite the latest significant achievements reported in vector design, it is not possible to predict to what extent gene therapeutic interventions will be effective in patients, and in what time frame.     

Evaluation of commonly-used farm disinfectants in wet and dry models of Salmonella farm contamination

Two experimental models of Salmonella contamination were used in an attempt to mimic the conditions of disinfectant use on farms. A wet model, for conditions such as boot dips, used disinfectant application to a slurry of poultry faeces inoculated with Salmonella Enteritidis or Salmonella Typhimurium. A dry model, for disinfectant application to surfaces and equipment with adherent or residual organic material, used Salmonella-inoculated poultry faeces that were air-dried onto wooden dowels, immersed in disinfectant solution then left in air at room temperature overnight. All samples were subjected to a disinfectant neutralization step and resuscitation in broth, followed by Salmonella culture on semi-solid then indicator media. Disinfectants were tested at 0.5x, 1x and 2x the concentrations specified for the general control of bacterial pathogens on livestock premises in the UK (Defra General Orders rates). Chlorocresol-based disinfectants provided consistently high rates of Salmonella killing in both wet and dry tests. Formaldehyde-containing disinfectants showed very high efficacy in the dry test but were less effective in the shorter wet test, whereas the efficacy of glutaraldehyde without formaldehyde was variable between products. Other chemical classes tested (quaternary ammonium compounds, amphoteric surfactants, iodine preparations, peroxygens and a substituted phenol blend) were only moderately effective. They often required concentrations above General Orders rates to eliminate the test salmonellas, and frequently elimination was not achieved even under maximal conditions of concentration and exposure.     

Synovial sarcoma (SS): new perspectives supported by modern technology

Based upon the experience of 256 cases of synovial sarcoma (SS), the present review analyzes structural, biological and molecular pathology of this poorly known sarcoma. The histology displays a multiphenotype with two major components: biphasic and monophasic SS. In addition, a number of variants have been described: undifferentiated Ewing's like, myoxid and predominantly epithelial (monophasic epithelial sarcoma). Microcalcifications and squamous metaplasia are often seen in the tumor. Immunohistochemistry with EMA and cytokeratin in the epithelial or epithelioid component is diagnostic for SS together with vimentin positivity in the spindle cells. Several other epitopes are also expressed (CD99, CD56, C-MET, HGF/SF, CD44). The ultrastructure confirms the variegated pattern of the neoplasm demonstrating the epithelial component and the epithelioid or spindle cell type closely associated with each other. Transition of epithelial cells to epithelioid and spindle-like mesenchymal component is seen. Nude-mice xenografts and cell lines after in vitro culture confirm heterogeneity of this sarcoma. Molecular histology of the SS has provided high utility not only for their differential diagnosis due to a specific chromosomal translocation: t(X;18)(p11.2;q11.2) but also after cloning these breakpoints resulting in the fusion of two genes: SYT at 18q11 and SSX at Xp11. Further observations have lead to distinguish the existence of two related genes: SSX1 and SSX2, that provide a highly specific and sensitive diagnostic marker for SS. Moreover, clinical correlations have demonstrated that SYT-SSX1 leads to a poor clinical outcome while the fusion SYT-SSX2 provides survival advantages to the patients.     

Transgenic plants in vaccinology

The problem of transgenic plants application to production of antigens, antibodies, enzymes, and hormones is discussed. Transgenic plants are a highly effective system for production of bioactive molecules. Prospects for using transgenic plants expressing viral and bacterial antigens for mucosal immunization are discussed.     

Internet in medicine--development and perspectives

Internet is one of information technologies marking the transition from the second to the third millennium. The present role and expansion of Internet in medicine and healthcare is reviewed together with the perspective of further development. The beginning and initial expansion of the use of Internet in medicine are described. The World Wide Web (WWW or Web) is recognized as a major reason for this expansion, reaching a state described as a Web-pandemic. The rapid increase of the number of papers dealing with Internet in medical literature is presented as well as the appearance of several journals dedicated to Internet in medicine. First specialized symposia, among them MEDNET world conferences, are noted. First uses of Internet in medicine comprised databases, discussion groups, electronic newsletters, software archives and online public access catalogues. The appearance of the Web has led to a significant improvement of the Internet use in medicine, which is reflected in an exponential increase in the number of publications. It is noted that Internet allows "to do old things in new ways", but also "to do new things". It has become clear that the information revolution evoked by the internet shall leave a deep trace in medicine, as health information has become accessible to the public and ceased to be in exclusive control of health professionals. New medical fields--telemedicine and cybermedicine--appeared as the result of the development and global expansion of information and communication technologies, with cybermedicine dealing more specifically with the use of Internet. The advantages and disadvantages of cybermedicine are discussed, and major problems related to the quality of health information are highlighted. Several systems for quality criteria of health related Web-sites are described, indicating that Websites have to conform with the quality criteria such as transparency and honesty, accountability, privacy and data protection, currency, accountability and accessibility. A review of the development of the use of Internet in medicine in Croatia is given. It is ever more recognized worldwide that the Internet is capable to create conditions for partnership between patients and clinicians. In concluding remarks, the reasons are given for a sooner access to the Internet and its daily use in healthcare activity.     

Bacterial DNA in house and farm barn dust

Early in life, natural exposure to microbial components (eg, endotoxin) may mitigate allergy and asthma development in childhood. Bacterial DNA is a potent stimulus for the innate immune system; its immune stimulatory potential in dust is unknown.     

Studies of stress in farm animals

Major changes have taken place in animal production over the last three decades. Housing conditions have changed dramatically over this period, and there has been a striking increase in production. Agricultural animals try to cope with these highly demanding conditions (stressors) using behavioural and physiological stress responses aiming to restore homeostasis. When these responses are not successful or when they are thwarted, typical behavioural and physiological symptoms of chronic stress occur. In this situation, the welfare of the animal is clearly at stake. Moreover, chronic stress may seriously affect the efficiency of animal production and the quality of the product. Ultimately, detailed knowledge of stress responses in agricultural animals will allow the formulation of housing and management requirements, including handling by humans, which will benefit welfare and health of farm animals as well as production efficiency. This paper briefly addresses some important issues regarding the study of stress and welfare in farm animals, and discusses some recently developed experimental methods as well as relevant results obtained in our laboratory. Originally presented at ECCP 97.     

Progress and perspectives in computational neuroanatomy

The tremendous increase in processing power of personal computers has recently allowed the construction of highly sophisticated models of neuronal function and behavior. Anatomy plays a fundamental role in supporting and shaping nervous system activity, yet to date most details of such a role have escaped the efforts of experimental and theoretical neuroscientists, mainly because of the problem's complexity. When accurate cellular morphologies are included in electrophysiological computer simulations, quantitative and qualitative effects of dendritic structure on firing properties can be extensively characterized. Complete models of dendritic morphology can be implemented to allow the computer generation of virtual neurons that model the anatomical characteristics of their real counterparts to a great degree of approximation. From a restricted and already available experimental database, stochastic and statistical algorithms can create an unlimited number of non-identical virtual neurons within several mammalian morphological classes, storing them in a compact and parsimonious format. When modeled neurons are distributed in three-dimensional and biologically plausible rules governing axonal navigation and connectivity are added to the simulations, entire portions of the nervous system can be "grown" as anatomically realistic neural networks. These computational constructs are useful to determine the influence of local geometry on system neuroanatomy, and to investigate systematically the mutual interactions between anatomical parameters and electrophysiological activity at the network level. A detailed computer model of a "virtual brain" that was truly equivalent to the biological structure could in principle allow scientists to carry out experiments that could not be performed on real nervous systems because of physical constraints. The computational approach to neuroanatomy is just at its beginning, but has a great potential to enhance the intuition of investigators and to aid neuroscience education. Anat Rec (New Anat): 257:195-207, 1999.     

The major histocompatibility complex and diseases in farm animals

Breeding for genetic resistance to disease and development of veterinary vaccines are major stimuli for research of the major histocompatibility complex (MHC) in farm animals. Genetically determined resistance is an attractive preventive measure because it precludes veterinary services, and is consistent over generations. Also many infectious diseases in farm animals cannot be prevented by vaccination. In a recent seminar sponsored by the European Community, the MHC of farm animals was discussed, its association with diseases was assessed, and other means of selection for disease resistance were evaluated.