Effect of reinforcement particle size on the tribological properties of nano-diamond filled polytetrafluoroethylene based coating.

The tribological properties of PTFE composite coatings reinforced by nano-diamonds were investigated. Mechanical particle size reduction and dispersion of nano-diamond aggregates were performed by milling with ceramic beads in an organic solvent. Particle size was controlled by the milling time. Pastes comprising a PTFE solution mixed with nano-diamond having various sizes were coated on the aluminum substrate. Ball-on-plate type wear test was performed to investigate the friction and wear behavior. The results indicated that the addition of nano-diamonds effectively improved tribological performance of the PTFE coating. The reduction in nano-diamond sizes were not always improved the wear resistance of PTFE coating. This unexpected behavior was explained by observation on the worn surfaces and wear debris.

Effect of immature dendritic cell injection before heterotropic cardiac allograft.

Although dendritic cells (DCs) are unrivaled for initiation of immune responses, the immunomodulatory capacity of chemically fixed DC has not been thoroughly evaluated. We monitored the tolerogenic capacity of chemically fixed DCs using allogeneic heart transplantations. Bone marrow progenitors were differentiated into immature DCs which were then chemically fixed and injected intravenously into recipient mice at 14 days before allogeneic heart transplantation. Chemically fixed DCs markedly prolonged graft survival in the major histocompatibility complex (MHC) I/II mismatch cardiac transplantation (B6 --> B10.A; median survival time [MST] 12.5 days vs >70 days). T cells that encountered chemically fixed DCs showed attenuated apoptotic cell death and inactivated phenotypes after allogeneic heterotropic heart transplantation. Furthermore, when DCs from interleukin (IL)-10-/- mice were treated, the in vitro T-cell response was greater than that from IL-12-/- mice. We have suggested that the chemically fixed DCs may mediate peripheral T-cell tolerance, with therapeutic potential for allogeneic transplantation.

Phylogenetic relationships of the seven coat protein subunits of the coatomer complex, and comparative sequence analysis of murine xenin and proxenin.

The coatomer complex is involved in intracellular protein transport and comprises an assembly of seven polypeptide subunits designated alpha, beta, beta', gamma, delta, epsilon, and zeta COP. Rooted phylogenetic trees constructed from the full-length cDNA and amino acid sequences of 49 COP entities in different eukaryotes from yeast to man generally revealed striking conservation of each subunit through evolution. Both nucleotide and protein trees displayed close relationships between alpha and beta' subunits, between beta and gamma subunits, and between delta and zeta subunits, implying evolution from common ancestors as well as functional similarity. Interestingly, although 6 out of 7 epsilon-COP genes appeared to be grouped and related to the beta-COP genes, 4 out of 7 epsilon

Case report: greatly enlarged jugular fossa with progressive sensorineural hearing loss.

A case of a five-year-old child with a greatly enlarged jugular fossa and high jugular bulb with associated progressive sensorineural hearing loss is presented. While various forms of this anatomical variant have been described by many authors, this is an extreme example, and progressive symptoms are most unusual.

Clinical investigation of hearing loss in the elderly.

The prevalence of hearing loss increases with age. Epidemiological and histopathological studies relating hearing loss to age are reviewed and clinical evidence presented suggesting that hearing loss is due not only to age but also to disease processes known to be associated with hearing threshold deterioration. 80 elderly patients presenting with a hearing problem at hospital have been studied and compared with 287 'non-complainers'. 83% of the study group were found to have factors, additional to age, contributing to their hearing loss; 50% had a medical condition previously unrecognized; 30% were taking potentially ototoxic drugs. Audiometric measurements indicate that hearing thresholds of the elderly are influenced by numerous disease processes. Patients attending hospital with hearing impairment are at greater risk of having a vascular or biochemical abnormality than a group of elderly 'non-complainers'. Elderly patients presenting with hearing loss should therefore be adequately investigated before being labelled as having presbyacusis.

Obstructive hydrocephalus caused by a growing, giant aneurysm on the upper basilar artery.

We describe the case of a giant aneurysm on the basilar artery not treated surgically after the first subarachnoid hemorrhage causing obstructive hydrocephalus 12 years later by growing. The problems of pathogenesis of growing aneurysms are discussed.

[Valvulography for the evaluation of the cerebrospinal shunt in childhood hydrocephalus (author's transl)]. / Die Kontrastmitteldarstellung des ableitenden Shuntsystems beim kindlichen Hydrocephalus.

Infection and obstruction of the cerebrospinal shunt are the most important disturbances in the management of childhood hydrocephalus. Often an occlusion of the shunt cannot be localized by conventional diagnostic means. Therefore the patency of Heyer-Systems was studied in 28 hydrocephalic children aged 2 months to 15 years with clinical signs of an increased intracranical pressure. The so-called valvulography with 99mTc-pertechnetate or Metrizamide (Amipaque). In more than 96% the results were confirmed during operation. The advantages of the X-ray method are: instrument and contrast medium are available at any time and the combination with cranial computertomography gives more precise data than scintigraphy alone.