Modeling the interaction between FK506 and FKBP12: a mechanism for formation of the calcineurin inhibitory complex

FK506 is a naturally occurring immunosuppressant whose mode of action involves formation of an initial complex with the cytosolic protein FKBP12. The composite surface of this complex then binds to and inhibits the protein phosphatase calcineurin (PP2B). To investigate why FK506 does not inhibit calcineurin directly we have conducted molecular modeling and conformational studies on published structures of FK506 both alone and in complex with FKBP12. From studies of the structure of FK506 in CDCl3 and Z-Arg32-ascomycin in water (a water soluble analogue of FK506) we suggest that the FK506 molecule can be viewed as consisting of three separate regions. The pipecolate region which extends from C24 to C10 including the pipecolate ring shows strongly conserved conformation in both solvents. The loop region which extends from C25 to C16 shows general conservation of the loop structure and the pyranose region made up of the pyranose ring and C15-C17 which shows highly variable conformation depending on solvent. Comparison of the structure of Z-Arg32-ascomycin in water with structures of FK506 bound to FKBP12 indicate that the conformation of the pipecolate region is conserved during the binding process. The conformation of the loop region was generally conserved but a significant reduction (approximately 1.7 A) in the diameter of the loop in the bound structure was observed. The conformation of the pyranose ring and C15-C17 region was found to be significantly altered in the bound structure resulting in displacements of the C13 and C15 methoxyl groups of 2.8 and 3.5 A, respectively. From computer models and molecular dynamics simulations of interactions between FK506 and FKBP12 we suggest that the conformational changes observed in bound FK506 are induced by the interaction between the 80's loop of FKBP12 and the pyranose ring of FKBP12. These interactions result in the formation of a complex with the both correct shape and surface polarity for interaction with calcineurin.     

Prosthodontic considerations when using implants for orthodontic anchorage

Between 8 December 1995 and 16 January 1996 seven laboratory confirmed cases of septicaemia owing to infection with Neisseria meningitidis serogroup C strains and one highly probable case of meningococcal septicaemia occurred in three electoral wards in south Rotherham and the Retford area of north Nottinghamshire. All cases occurred among children aged 1-17 years. One patient died. The public health response to this outbreak was the largest community prophylactic antibiotic and immunization programme against meningococcal infection, to date, in the United Kingdom. The target group for each Health Authority was 8900 for Rotherham Health Authorities and 8000 for North Nottinghamshire Health. Local logistical factors led to differences in the implementation of the programme by each Health Authority. At the completion of each programme, 8320 doses of vaccine had been administered (92.5 per cent coverage) during the Rotherham Health Authorities programme and 7660 (95.7 per cent coverage) during the North Nottinghamshire Health programme. The additional financial cost of the exercise amounted to approximately Pounds 125000 for each Health Authority. This paper describes the evolution of the outbreak, the decision-making process resulting in the immunization programme in each Health Authority, the implementation of each programme, problems identified and lessons learned.     

The prevalence of early postpartum psychiatric morbidity in Dubai: a transcultural perspective

The surface roughness of artificial blood contacting devices is an important surface property that is closely related to blood cell trauma. The present study investigated the effect of the surface roughness of a pump housing on hemolysis in an impeller-type centrifugal blood pump, a pivot bearing supported Gyro C1E3 pump. The purpose of the study was to determine which part of a housing has the greatest surface roughness effect on hemolysis in a centrifugal pump. Seven Gyro C1E3 pumps were prepared, each with a smooth surface impeller and a housing with differing areas of altered surface roughness. Both top and bottom housings were divided into half subregions, each with the same area. Seven test pumps were produced by subjecting various subregions of the housings to vapor polishing and sandblasting. The treated surfaces were then examined by a surface profile instrument. Using these 7 pumps with different areas of altered housing roughness, in vitro hemolysis tests were performed simulating cardiopulmonary bypass (5 L/min, 350 mm Hg). The results of this study are as follows. First, the surface roughness of the top housing had a greater effect on hemolysis than that of the bottom housing. Second, on the surface of the top housing, the surface roughness of the outer half area had a greater effect on hemolysis than that of the inner half area. Third, on the surface of the bottom housing, the surface roughness of the inner half area had a greater effect on hemolysis than that of the outer half area. These findings concur with previous studies of flow patterns in pumps. Thus, it is expected that the method in this study, comparative in vitro hemolysis tests of the pumps with surfaces of the same roughness but different locations, can be used to detect the high shear area inside a pump.     

Prospective use of intramuscular triamcinolone acetonide in pseudogout

OBJECTIVE: To prospectively assess the efficacy of intramuscular (i.m.) triamcinolone acetonide in the treatment of pseudogout. METHODS: Fourteen patients with crystal proven pseudogout presenting with an acute attack within 5 days of onset were treated with intramuscular triamcinolone acetonide 60 mg and followed for 30 days. Patients with inadequate response were eligible for a 2nd triamcinolone acetonide injection on Day 1-2. RESULTS: Twelve patients had contraindication to nonsteroidal antiinflammatory agents (NSAID). Acute arthritis was monoarticular in 10 patients, and involved 2 or more joints in 4 patients. All patients had good clinical response to triamcinolone acetonide based on restoration of near baseline joint range of motion and joint circumference, and at least 50% improvement in patient and physician global assessment. Major clinical improvement occurred by Day 1-2 (2 patients), Day 3-4 (11 patients), and Day 10-14 (one patient). Six patients required a 2nd triamcinolone acetonide injection on Day 1-2. Toxicities were not observed. CONCLUSION: I.m. triamcinolone acetonide appears to be safe, well tolerated, and effective in the treatment of pseudogout. It may be a reasonable alternative therapy when NSAID are contraindicated, and for polyarticular attacks where intraarticular corticosteroids are impractical.     

The adenohypophysis of Mediterranean yellowtail, Seriola dumerilii (Risso, 1810): an immunocytochemical study

The adenohypophysis (ADH) of the Mediterranean yellowtail was studied using the peroxidase-antiperoxidase technique. Human corticotropin (ACTH) (1-24)-immunoreactive (ir) cells were found bordering the neurohypophysis (NH) and salmon prolactin (PRL)-ir cells were arranged in thick cords, both in the rostral pars distalis (RPD). Gonadotropin (GTH)-, thyrotropin (TSH)- and growth hormone (GH)-ir cells were observed in the proximal pars distalis (PPD). Anti-chum salmon GTH I and anti-chum salmon GTH II immunostained the same cells in the outermost part of the ADH at the level of the PPD and the PI. In addition to these cells, some cells grouped in the inner areas of the posterior PPD were revealed by catfish alpha, beta-GTH antiserum. Human beta-TSH-ir cells formed small groups and discontinuous strands in the PPD often in contact with the NH. Tilapia GH-ir cells formed cords mainly surrounding the NH in the central PPD, while cod somatolactin- and alpha MSH-ir cells mainly surrounded the NH branches in the PI.     

Association in the same patient of autosomal dominant progressive external ophthalmoplegia with multiple mtDNA deletions and X-linked ichthyosis: clinical, biochemical, histological, submicroscopic and molecular genetic study

Previous work demonstrated that several antiarrhythmic agents and antidepressive drugs block transient outward K+ current (I(to)) in rat ventricular myocytes. The antiarrhythmic drug, disopyramide, and the tricyclic antidepressants, imipramine and amitriptyline, block the I(to) channel mainly when it is in the open state. The rate of recovery from block induced by disopyramide is so slow that the drug produces a use-dependent block at 1 Hz, whereas the rate of recovery from block in the presence of imipramine and amitriptyline is fast enough so as not to induce any use-dependent block at this frequency. We studied the effects of the combinations of disopyramide-imipramine and disopyramide-amitriptyline on I(to) to detect possible interactions between the drugs on I(to) blockade. The effects of imipramine and amitriptyline on the use-dependent effect induced by disopyramide and on the rate of recovery of the channels blocked by this drug allow us to conclude that there is only one common receptor site in the channel molecule for the three drug molecules.     

Insulin-like growth factors counteract the effect of interleukin 1 beta on type II phospholipase A2 expression and arachidonic acid release by rabbit articular chondrocytes

Interleukin 1 beta was found to stimulate arachidonic acid release, and the synthesis and secretion of type II phospholipase A2 by rabbit articular chondrocytes in vitro. Interleukin 1 beta had no effect on the level of cytosolic phospholipase A2 mRNA. Insulin-like growth factors, which help stabilize the cartilage matrix, reduced the effect of interleukin 1 beta on type II phospholipase A2 activity and mRNA level, and decreased the Interleukin 1 beta-stimulated arachidonic acid release to the basal values. This suggests that type II phospholipase A2 plays a key role in arachidonic acid release from rabbit articular chondrocytes and that insulin-like growth factors counteract the effect of interleukin 1 beta. They may therefore be considered as potential antiinflammatory agents.     

Failure analysis of die-attachment on static random access memory (SRAM) semiconductor devices

Different combinations of the SRAM die and the substrates to yield a better die-attachment are studied. Cleanliness of die backside, plasma etching of contaminated die backside, new frames and old frames are the factors considered. The number of rejects due to die cracking in the die-attachment can be minimized if (1) production die and new frames are used, (2) 100% eutectic coverage is performed, (3) no gold preforms is added for substrates that are already coated with a thin layer of 98% Au-2% Si and (4) plasma etcher is used in clean surface preparation for suspected contaminated die backside surfaces. To whom correspondence should be adressed.