Delivery of a hammerhead ribozyme specifically down-regulates the production of fibrillin-1 by cultured dermal fibroblasts

The hammerhead ribozyme is a small catalytic RNA molecule. Potential hammerhead ribozymes that possess a catalytic domain and flanking sequence complementary to a target mRNA can cleave in trans at a putative cleavage site within the target molecule. We have investigated the potential of hammerhead ribozymes to down-regulate the product of the fibrillin-1 gene (FBN1). Fibrillin is a 347 kDa glycoprotein that is a major constituent of the elastin-associated microfibrils. Mutations in the FBN1 gene are responsible for Marfan syndrome (MFS), a common systemic disorder of the connective tissue. Many FBN1 mutations responsible for MFS appear to act in a dominant-negative fashion, raising the possibility that reduction of the amount of product from the mutant FBN1 allele might be a valid therapeutic approach for MFS. A trans-acting hammerhead ribozyme (FBN1-RZ1) targeted to the 5' end of the human FBN1 mRNA has been designed and synthesized, and shown to cleave its target efficiently in vitro. FBN1-RZ1 cleavage is magnesium dependent and efficient at both 37 and 50 degrees C. Delivery of the FBN1-RZ1 ribozyme into cultured dermal fibroblasts, by receptor- mediated endocytosis of a ribozyme-transferrin-polylysine complex, specifically reduces both cellular FBN1 mRNA and the deposition of fibrillin in the extracellular matrix. These results suggest that the use of hammerhead ribozymes is a valid approach to the study of fibrillin gene expression and possibly to the development of a therapeutic approach to MFS.      

Protective cytotoxic T lymphocyte responses against paramyxoviruses induced by epitope-based DNA vaccines: involvement of IFN-gamma

Plasmid DNA vectors have been constructed with minigenes encoding a single cytotoxic T lymphocyte (CTL) epitope from either the M2 protein of respiratory syncytial virus (RSV) or from the nucleoprotein of measles virus (MV) with or without a signal sequence (also called secretory or leader sequence). Following intradermal immunization, plasmids in which the CTL epitopes were expressed in-frame with the signal sequence were more effective at inducing peptide- and virus- specific CTL responses than plasmids expressing CTL epitopes without the signal sequence. This immunization resulted in protection against MV-induced encephalitis and a significant reduction in viral load following RSV challenge. The reduction of viral load following RSV challenge was abrogated by prior injection with anti-IFN-gamma antibodies. These results highlight the ability of epitope-based DNA immunization to induce protective immune responses to well-defined epitopes and indicate the potential of this approach for the development of vaccines against infectious diseases.      

Possible involvement of receptors in the entry of Kunjin virus into Vero cells

Summary The results obtained from electron microscopy, adsorbed and internalised virus assays and immunofluorescence studies supported that the most likely mode of entry of Kunjin virus into Vero cells was by receptor-mediated endocytosis. This was deduced indirectly from the time sequence of events that occurred. Electron microscopy revealed that endocytosis of the virus through coated vesicles had occurred. The adsorbed and internalised virus assay and immunofluorescence studies showed that there were two factors being recycled during endocytosis: the receptor for the virus and clathrin, the protein found on coated pits and vesicles. The study showed that clathrin was recycled first, followed by the receptor.     

Paradigm shift in gastrointestinal surgery − combating sarcopenia with prehabilitation: Multimodal review of clinical and scientific data

A growing body of evidence has demonstrated the prognostic significance of sarcopenia in surgical patients as an independent predictor of postoperative complications and outcomes. These included an increased risk of total complications, major complications, re-admissions, infections, severe infections, 30 d mortality, longer hospital stay and increased hospitalization expenditures. A program to enhance recovery after surgery was meant to address these complications; however, compliance to the program since its introduction has been less than ideal. Over the last decade, the concept of prehabilitation, or “pre-surgery rehabilitation”, has been discussed. The presurgical period represents a window of opportunity to boost and optimize the health of an individual, providing a compensatory “buffer” for the imminent reduction in physiological reserve post-surgery. Initial results have been promising. We review the literature to critically review the utility of prehabilitation, not just in the clinical realm, but also in the scientific realm, with a resource management point-of-view.     

Prevalence of sexually transmitted diseases in juvenile prostitutes and street youth

Four groups of adolescents - 35 juvenile prostitutes, 36 street youth, 31 monogamous sexually active adolescents and 35 non-sexually active adolescents - were studied between January 1, 1988 and December 31, 1988 for the presence of sexually transmitted diseases and other genital pathogens. The high prevalence of sexually transmitted diseases found in the juvenile prostitutes (Neisseria gonorrhoeae, 49%; Chlamydia trachomatis, 83%) is in contrast to other studies, which document much lower rates of infection. This could be due to the fact that there are few studies done on juvenile prostitutes as a well defined group. Despite high risk sexual behaviour, the consistent use of contraception was low. No contraceptives were used by 57% of the juvenile prostitutes and 85% of the street youth. None of the adolescents sought medical attention although 48% of the juvenile prostitutes and 53% of the street youth had genital symptoms. It appears that the present public health education and health care delivery do not reach this high risk population.     

Response from lieberman and colleagues

Respond on comments on Lieberman's article: Cyclosiloxanes Produce Fatal Liver and Lung Damage in Mice. Environ Health Perspect 107:161-165     

Net postprandial utilization of [15N]-labeled milk protein nitrogen is influenced by diet composition in humans

The aim of this study was to follow the fate of dietary nitrogen to assess the postprandial utilization of purified milk protein and to determine the acute influence of energy nutrients. For this purpose, a [15N]-labeling dietary protein approach was used. Twenty-five subjects swallowed an ileal tube and ingested [15 N]-milk protein alone or supplemented with either milk fat or sucrose. The absorption and postprandial deamination of dietary protein was monitored for 8 h. Sucrose delayed the absorption of protein longer than fat, but the ileal digestibility did not differ among groups (94.5-94.8%). Sucrose, but not fat, significantly reduced the postprandial transfer of [15N]-milk nitrogen to urea. Consequently, the net postprandial protein utilization (NPPU) of milk protein calculated 8 h after meal ingestion was 80% when ingested either alone or supplemented with fat and was significantly greater with sucrose (NPPU = 85%). This study shows that energy nutrients do not affect the nitrogen absorption but modify the metabolic utilization of dietary protein in the phase of nitrogen gain. Our method provides information concerning the deamination kinetics of dietary amino acids and further allows the detection of differences of dietary protein utilization in acute conditions. The diet composition should be carefully considered, and protein quality must be determined under optimal conditions of utilization.     

A novel biological-based assay for the screening of neutralizing antibodies to ricin

A novel approach to screen hybridomas producing antibodies directed against ricin was developed. Anti-ricin antibodies were produced and characterized based on protection of Sp2/mIL6 myeloma cells and in vivo studies demonstrating neutralization of the toxic effects of ricin in mice. During the production of hybridomas, cells were plated in media supplemented with hypoxanthine, aminopterin, and thymidine supplement (HAT), HAT + ricin, or ricin. Three hybridomas, designated HRF4, HHRD7 and HHRD9, were selected from the media supplemented with ricin and were shown to produce antibodies directed against ricin. Intraperitoneal injection of hybridoma supernatant containing anti-ricin antibodies combined with 0.5 microg ricin (a toxic dosage) protected Balb/C mice from the deleterious effects of the ricin. Hybridoma, HHRD9, did not contain high titre antibodies to ricin but appeared to neutralize the toxic effects of ricin in mice.     

Antibiotic resistance. An impending crisis

The global emergence of antimicrobial resistance has become a pre-eminent concern in medicine and public health. Antimicrobial resistance is of particular concern because the problem is widespread, the causative factors are uncontrolled, and national strategies to address the problem are lacking. The persisting burden of infectious diseases makes elimination of antibiotic use unethical, but dramatic overuse and misuse of antimicrobial agents around the world must be reduced to extend the useful lifetimes of these drugs. Population genetic models suggest that resistance emerges rapidly under the selective pressure of antibiotics, but decays slowly once that pressure is removed. Hence, measures to prevent the emergence of resistance must be implemented urgently. A multiplicity of factors drive antibiotic resistance, and solutions require the collaboration of governmental agencies, the pharmaceutical companies, healthcare providers, and consumers. Leadership in the form of a national steering committee on antimicrobial resistance is needed in the Kingdom of Saudi Arabia to guide collective action to control the threat of antibiotic resistance.