Corrosion resistance of a passivated and non-passivated cobalt-chromium alloy

Abstract – The release of cobalt and chromium from a passivated and non-passivated cobalt-chromium alloy in artificial saliva has been measured using nuclear tracer technique. The corrosion resistance of the passivated specimens was improved by a factor of about four compared to the non-passivated specimens with regard to the initial cobalt release. The specimens were exposed to the saline solutions for periods up to about 8 wk. The cobalt release is associated mainly with electrochemical corrosion processes, since particulate matter retained on a filter was only registered to a minor extent. It is suggested that the decrease in release of cobalt and chromium after passivation is connected to the formation of Cr-O and/or Cr-OH bonds in the protective film which impede the movement of cobalt and chromium from the alloy into the saliva.     

Diagnosis and Management of Acute Aortic Dissection,Clinical and Radiological Follow-up

ABSTRACT A clinical series of acute aortic dissections is presented. Twenty cases were of type A and 10 of type B. Acute severe chest pain was common, in type A also blood pressure difference between the arms and aortic regurgitation. The diagnosis was established by echocardiography, computerized tomography and/or aortography. Antihypertensive therapy was instituted immediately after diagnosis and was in type A cases followed by acute surgery unless definite contraindications existed. Of 14 surgically treated type A patients 13 survived the operation. On follow-up 1.5–3.5 years later, 12 patients were still alive and doing well, but the false channel remained open in all cases where it had not been resected totally. Only one of six conservatively treated type A patients survived. Type B dissections were operated on only if conservative therapy failed. Four of five conservatively and two of five surgically treated type B patients survived.     

Pathophysiological mechanisms for restenosis following coronary angioplasty: possible preventive alternatives

Abstract. Restenosis after successful percutaneous transluminal coronary angioplasty (PTCA) remains an unsolved medical problem. The search for the underlying pathophysiological mechanisms have identified intimal proliferation of smooth muscle cells (SMC) to be the prevailing cause of late restenosis, with endothelial cells (EC) and platelets being important participators in the process. According to the most accepted present theory, SMC would be stimulated to migrate and proliferate shortly after the angioplasty by the release of growth factors from injured EC and accumulated platelets. However, clinical trials of agents interfering with these mechanisms have not significantly diminished the rate of restenosis, which suggest both that our knowledge of the process is incomplete, and that new ways of administrating the agents may be required.     

Solid-phase peptide synthesis on proteins

A new method for solid-phase peptide synthesis in which a protein is used as the solid support has been developed. Two aspects of the method have been demonstrated. The peptides H-Phe-Leu-Glu-Glu-Val-OH (1) and H-Leu-Leu-Ala-Glj-Val-OH (2), respectively, were synthesized on the amino groups of BSA via a cleaveable linker, using the Fmoc group protecting scheme. The free peptides were obtained by cleavage from the protein with 95% TFA. precipitation in diethyl ether and additional work-up by either dialysis or centrifugation through a membrane followed by gel filtration. The identity of the products was determined by amino acid analysis and HPLC. The peptide-protein conjugates, H-Ser-Met-Asp-Thr-Ser-Asn-Lys-Glu-Glu-Lys-BSA (3) and H-Thr-Val-Leu-BTG (4), were obtained in the same manner, omitting the cleavable linker group. It was found that 35-50 peptide chains were conjugated per molecule BSA and BTG, respectively. Immunization of rabbits with conjugate 3 gave rise to peptide specific antibodies. This method will be useful for generation of sequence specific antibodies, since the peptide is conjugated to the carrier protein exclusively via its C-terminus, and will allow synthesis of highly specific peptide-protein conjugates.     

Tissue distribution of epimucosally applied 3H DNFB: an autoradiographic study

Abstract – The distribution of ³H-labeled 2,4-dinitrofluorobenzene (DNFB) has been autoradiographically investigated in buccal mucosa after topical application to sensitized or nonsensitized rats. The rats were killed between 3 min and 24 h after challenge. No significant labeling pattern differences were found between plastic embedded and frozen sections. Surface epithelium was heavily labeled and labeled cells were observed in the lamina propria shortly (3–6 min) after application. These cells were clearly dendritic. Specific accumulation of hapten in epithelial Langerhans cells (LC) could not be clearly demonstrated. The connective tissue labeling gradually diminished and at 24 h post-elicitation, remaining label could be detected only in the epithelial surface layers.     

Treatment of dentin with stannous fluoride – SEM and electron microprobe study

Abstract – The effect of SnF₂-treatment of dentin surfaces was investigated by means of scanning electron microscopy (SEM) and electron microprobe analysis. Human dentin was treated with aqueous SnF₂ solutions of concentrations varying from 1 to 10%. The treatment periods lasted for 1, 5, 10, or 60 min. Both tin and fluoride were identified on the surfaces. The concentration varied depending on the extensiveness of the treatment. Immersion in 1 M KOH for 15 h removed both tin and fluoride from the surfaces. This reaction was not observed after immersion in H₂O for the same time period. Examination of the SnF₂-treated dentin surfaces showed a dense layer of globular particles and in addition some larger particles. The dentinal tubules were totally covered even after the treatment with the lowest concentration of SnF₂. Deposition of tin- and fluoride-coniaining globules on dentin surfaces may be of clinical interest. This layer may have importance both for the caries resistance of dentin and for hypersensitivity reactions.     

Subgingival microorganisms and bacterial virulence factors in periodontitis

Considerable information has come forth in recent years on the pathogenic organisms in human periodontilis and the sequence of events by which they produce periodontal disease. Important pcriodontopatliogens include Bactcroidcs gingivalis, Bactcroidcs intcnnedius and Actinobacillus actinomycetemcomitans. Virulence factors of B. gingivalis and B. intermcdius may mainly involve enzymes with potential to interfere with host defenses and to disintegrate periodontal tissues. Pathogenic properties of A. actinomycetemcomitans appear predominantly to be exerted by leukotoxin and other noxious products.     

9-Acridinylpeptides and 9-acridinyl-4-nitrophenylsulfonylpeptides

The preparation of 6-(9-acridinylamino)hexanoic acid DHBT ester and Nα-Fmoc-N³ - (4-nitrophenylsulfonyl)-l -lysine DHBT ester and their application in solid phase peptide synthesis are described. The 9-acridinylamino ligand was shown to confer high DNA affinity, probably by intercalation, to the resulting peptides. The 4-nitrophenylsulfamido ligand furthermore resulted in “photonuclease” activity of some of the modified peptides.