ABSTRACT
The use of base metal alloys in dentistry has gained wide popularity in recent years. However, claims of their safety have not been universally accepted. An artificial oral environment capable of reproducing three-dimensional force-movement cycles of human mastication was used to determine whether nickel, chromium, and beryllium ions were leached from base metal alloy. Twelve pairs of crowns were articulated in the following combinations: metal versus metal, metal versus enamel, metal versus porcelain, and metal versus metal without chewing as a control. In a simulated 1-year period of mastication, the results showed that nickel and beryllium metals were released both by dissolution and occlusal wear. These findings suggest that if these conditions occur in the oral cavity, the stability of base-metal alloys is subject to question. Further studies are needed to determine whether the leaching reported has long-term consequences for patients receiving base metal restorations.
Subject(s)
Beryllium/chemistry , Chromium Alloys/chemistry , Chromium/chemistry , Mastication/physiology , Mouth/physiology , Nickel/chemistry , Analysis of Variance , Bite Force , Crowns , Dental Porcelain/chemistry , Humans , Materials Testing , Models, Biological , Molar , Saliva, Artificial/chemistry , Solubility , Surface PropertiesABSTRACT
An hypothesis is proposed to explain the surge of new diseases appearing in the world. Mass immunization with live viral vaccines increases the probability of genetic recombination between live vaccine viruses and between live vaccine viruses and other viruses. Perhaps this is the reason for origination of new diseases within the last twenty years. Nucleic acid hybridization techniques might be used to test the hypothesis.
Subject(s)
Acquired Immunodeficiency Syndrome/microbiology , Vaccines, Attenuated/adverse effects , Viral Vaccines/adverse effects , Cell Transformation, Viral , Genes, Viral , Humans , Hybridization, Genetic , Recombination, Genetic , Slow Virus Diseases/microbiologyABSTRACT
An hypothesis is presented which could lead to cancer treatment by passive immunotherapy. It is based on the specificity of antigen-antibody reactions. Essential enzymes produced by cancer cells which are involved in the replication and invasiveness of cancer might be nullified by such treatment.
Subject(s)
Antibodies, Monoclonal , DNA Ligases/immunology , Immunotherapy , Neoplasms/therapy , Polynucleotide Ligases/immunology , Antigen-Antibody Complex , Humans , Neoplasms/enzymologyABSTRACT
The initial acid-base status of eight survivors of Reye's syndrome was characterized by acute respiratory alkalosis (Pco2=32 mm Hg; Hco3-=22.0 mEq/liter) while that of eight children who died was associated with metabolic acidosis as well (HCO3-=10.0 mEg/liter). Arterial-internal jugular venous ammonia concentration differences on day 1 (299 mg/100 ml) and day 2 (90 mg/100 ml) reflected cerebral uptake of ammonia while those on days 3 and 4 (-43 and -55 mg/100 ml) demonstrated cerebral release. Arterial blood hyperammonemia can be detoxified safely in the brain as long as the levels do not exceed approximately 300mug/100 ml. Beyond that level lactic acidosis is observed, particularly in cerebral venous drainage. Arterial blood hyperammonemia was also related to the extent of alveolar hyperventilation. These findings are very similar to those seen in experimental hyperammonemia and support the concept that neurotoxicity in children with Reye's syndrome is at least partly due to impaired oxidative metabolism secondary to hyperammonemia.
