New surface modification for Ti-6Al-7Nb alloy: oxygen diffusion hardening (ODH)

PVD-TiN coating and N+ implantation of Ti-6Al-7Nb alloy resulted in surface hardening to a depth of less 3 microns. The new oxygen diffusion hardening (ODH) treatment increased the hardness gradually to 50 microns. PUD-TiN showed an improvement in the tribological properties, while N+ implantation increased the PE wear rate. The wear rate of the ultrahigh-molecular-weight as well as the friction coefficient were reduced to one-half of the values achieved with the combination of CoCrMo-alloy when paired against the ODH-treated surface. In pairing with ZrO2-containing bone cement the ODH-treated surface showed only a minimal reaction.     

Pathogenesis and changes in the aetiology of arterio-venous fistulae

There has been a marked shift in the causes of arterio-venous fistulae. Gunshot and stab wounds used to be the most frequent cause but iatrogenic fistulae, especially those arising as a result of reconstructive skeletal operations or following diagnostic and therapeutic procedures, are now becoming increasingly common. If morphological vascular changes have not yet occurred and cardiac volume overloading has not led to permanent damage, a recently established arterio-venous fistula can be easily corrected by resection and oversewing of the artery and vein. The special cases of arterio-venous fistulae arising as a result of catheter procedures in the groin have to be identified in terms of cause and morphology in order to facilitate early surgical correction.     

Cryotherapy in rectal cancer. A palliative local tumor treatment]

Cryotherapy was applied to 182 rectal cancer patients in the Department of General Surgery, University of Ulm, between 4/1982 and 4/1991. Recipients of this tumor freezing therapy were patients whose general condition was bad, patients with an advanced inoperable carcinoma, patients with tumor recurrence and patients refusing operation. Rectal carcinomas, mostly in an advanced stage, were usually freezed several times. Only 4 patients with general inoperability reached the survival time margin of 5 years. In 18 patients local tumor destruction was possible by application of cryotherapy. In 80% of cases disagreeable tumor symptoms like tenesma, mucous discharge and oozing hemorrhages could be reduced or completely removed. Perianal pain and intense tumor bleeding could be relieved temporarily or definitely in only 50% of patients. An artificial anus could be avoided in 80% of cases by local tumor destruction/reduction or arrest of tumor growth. The mean survival time of patients with tumor recidivation was 11 months after onset of the recurrence. Tumor progression, incontinence and iatrogenic rectal perforation made an artificial anus necessary in 14 patients.     

Induction of mediator release from human glomerular mesangial cells by the terminal complement components C5b-9.

Exposure of cultured human glomerular mesangial cells (GMC) to normal human serum and an activator of the complement system results in rapid uptake of the terminal complement proteins C5b-9 by the cells. This 'innocent bystander' complement attack, however, does not result in cell killing, but in the stimulation of the GMC to release prostaglandin E (PGE), interleukin 1 (Il-1) and tumor necrosis factor (TNF). Endogenously synthesized Il-1 in turn activates PGE release, indicating that the C5b-9 attack initiates an autocrine feedback stimulation. Together with the fact that C5b-9 is found in many forms of glomerulonephritis, the data point to a role of the terminal complement proteins in the initiation and perpetuation of an inflammatory response.     

Coping strategies and individual meanings of illness.

Every person has a subjective understanding of their own illness. The personal attitude towards disease and the corresponding coping mechanisms go beyond biomedical factors to influence the course of the disease. Lipowski described eight different disease concepts which were supplemented by the theory of control conviction (external-internal control). Several hypotheses about disease concepts, coping strategies and psychopathology were globally confirmed in a study of 205 chronic patients: Ability to control and acceptance lead to a more active and problem-related coping, whereas emotional coping modi occur more often in persons who do not accept their illness or do not consider it to be controllable. Results confirm the necessity of a differentiated analysis.     

Isolation and interspecies-transfer of a plasmid from Pasteurella multocida encoding for streptomycin resistance

A plasmid encoding streptomycin-resistance could be detected in 13 of 32 Pasteurella multocida-cultures isolated from cattle and swine. The plasmid of these cultures proved to be similar upon Southern blot hybridization. It could be transformed into Escherichia coli 490A, where it also expressed streptomycin resistance.     

Development of glutamate neurotoxicity in cortical cultures: induction of vulnerability by insulin.

The effect of insulin on the development of excitotoxic vulnerability in primary cultures of the rat cerebral cortex was examined. Cells were maintained for two weeks in serum-supplemented culture media, in the presence or absence of increasing insulin concentrations. Excitotoxic cell death was induced by 1 mM glutamate. The vulnerability of cells was evaluated by phase contrast microscopy and by the measurement of lactate dehydrogenase (LDH) release due to cytotoxic injury. In addition to a moderate (less than 50%) stimulation of protein and DNA synthesis, insulin produced more than a twofold increase in the excitotoxic vulnerability of cells. The effect of insulin was specific, concentration-dependent and required an intact molecular structure of insulin. Our findings indicate that insulin induces significant changes in cerebral neurons by increasing the lethal vulnerability of cortical cells to excitatory amino acids (EAAs).     

Pressure stability of nasal CPAP and bilevel devices

Summary Question of the study   Nasal continuous positive airway pressure (CPAP) prevents collapse of the upper airway during sleep in patients with obstructive sleep apnea provided that a positive transmural pressure can be maintained during inspiration. We examined pressure-flow characteristics in seven CPAP and bilevel devices during spontaneous breathing.
Methods   The CPAP devices were set to a pressure level of 9.8  hPa (10  cm H₂O) and adapted to a pneumotachograph using a standard CPAP hose and an outlet valve. We continuously measured flow, volume and pressure during resting ventilation and increasing voluntary hyperventilation and analysed the dependence of the variables on a breath-to-breath basis.
Results   Mean CPAP pressures differed between the devices (9.9 – 10.6  hPa) despite the same settings. In all machines pressure fell during inspiration to 8.4 – 9.8  hPa and increased during expiration to 11.1 – 11.7  hPa. This effect increased with higher flow rates. Maximum expiratory pressures rose to 12 – 19  hPa at peak flow rates of 2 l/s, mean expiratory pressures to 9.5 – 16  hPa. Inspiratory pressures dropped to 8.5 – 4.5  hPa (minimum) and 10.5 – 6.0 (mean). Bilevel devices showed a higher stability than CPAP devices. Pressure swings during the respiratory cycle increased the additional work of breathing.
Conclusions   Due to differences in mean and effective CPAP levels CPAP devices are not simply exchangeable but should be individually adapted. Patients with higher minute ventilation might benefit from more stable CPAP machines. The impact on patients' compliance remains to be evaluated.     

Memory search for faces and digits in patients with unilateral brain lesions.

To clarify whether the impairment of right-brain-damaged (RBD) patients in face recognition is related to perceptual or mnestic processing stages, we tested unilaterally lesioned patients and controls in a Sternberg-type memory search task. Subjects had to memorize sets of 1, 2, or 3 faces (or, in a control condition, digits) and were then to recognize these memorized stimuli among new ones by speeded choice reactions. In this task, deficits in stimulus encoding and memory search should show up in increased intercepts and slopes, respectively, of the RT function over memory set size. A face-specific impairment of the RBD patient group, consisting in longer reaction times and higher error rates, was confirmed but could not be unequivocally attributed to either stimulus encoding or memory search. However, inspection of individual data suggested that (1) some RBD patients are virtually unimpaired in face recognition and (2) if impairment after right hemisphere damage is present, it may selectively affect either stimulus encoding or memory search.