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Biomedical subjects

C Müller

Publications and source records attributed to C Müller.

At least 433 records · Page 24Linked to original sources
PubMed1993

Intramedullary pressure, strain on the diaphysis and increase in cortical temperature when reaming the femoral medullary cavity--a comparison of blunt and sharp reamers.

Clinical application has shown intramedullary nailing to be a safe therapeutic procedure, although damage to the vascular system and fat embolism have been demonstrated in animal experiments. The main negative factors were presumed to be the increase in intramedullary pressure and the increase in cortical temperature. In this study, the effect of the blunting of the reamers on the increase in intramedullary pressure, the tangential strain on the diaphysis and the increase in cortical temperature was to be clarified. The measurements were carried out on pairs of human femora reamed with sharp and blunt AO reamers. The pressure was measured in the middle of the diaphysis and in the metaphysis, the strain in the middle of the femur and the temperature on four aspects of the femur. The femora were reamed with identical compression and traction forces in a water bath at 37 degrees C. In comparison with the sharp reamer, the blunt reamer develops 2.1 times the positive diaphyseal pressure, 1.7 times the positive metaphyseal pressure, 1.6 times the negative diaphyseal pressure, 1.5 times the positive tangential strain, 55 times the negative tangential strain and 2.8 times the increase in cortical temperature. There is no difference in the negative metaphyseal pressure. Since blunt reamers produce greater intramedullary pressure values, greater tangential strain on the diaphysis and a greater increase in cortical temperature, the attention of surgeons and operating staff must be drawn to the fact that they should treat the reamers gently and replace them whenever necessary.

Equipment Failure↗
PubMed1993

Extent of bluntness and damage to reamers from hospitals.

The negative effects of intramedullary nailing, such as aseptic cortical necroses and fat embolisms, are mainly caused by an increase in intramedullary pressure and an increase in cortical temperature during the reaming process. The degree of bluntness of the reamers has a negative influence on these two parameters. The objective of this study was to examine the degree of bluntness and damage to intramedullary reamers in clinical use. 10 sets of intramedullary reamers returned from Swiss clinics were examined with regard to the radius of the cutting edge and the degree of damage. The following results were established (MN = medullary nailings): Sharpest reamers: hospitals with 300-400 beds. Hospitals with < 5 MN per year. Bluntest reamers: hospitals with > 1000 beds. Hospitals with 40-60 MN/year. Least damaged reamers: hospitals with 300-400 beds. Hospitals with 40-60 MN/year Most damaged reamers: hospitals with > 1000 beds. Hospitals with 40-60 MN/year Due to the fact that some of the reamers in clinical use are of inadequate quality both with regard to the sharpness of the milling lips and the degree of damage, doctors and operating staff should be instructed to check the quality of cutting tools before using them, to treat them carefully and to replace them if necessary.

Equipment Failure↗
PubMed1993

Influence of the compression force on the intramedullary pressure development in reaming of the femoral medullary cavity.

The reaming process is considered the main damage factor in intramedullary nailing, as there are repeated increases in intramedullary pressure and cortical temperature, which can lead to aseptic cortex necroses and fat embolisms. In this study, the influence of the compression force on the increase in pressure is to be examined. The intramedullary pressure was measured in the middle of the diaphysis and in the metaphysis of human femora reamed under various compression forces. The compression force exerted by the surgeon was measured on polyurethane femora. It was observed that an increase in the compression force of 1.8 times led to an increase in the diaphyseal pressure of 4.7 times and of the metaphyseal pressure of 3.1 times. As surgeons exert high compression forces, peak pressures of 970 mmHg diaphyseally and 1150 mmHg metaphyseally must be expected in the hospital. If reaming is carried out with less compression force, the intramedullary pressure can easily be reduced by 79% in the area of the diaphysis and by 68% in the metaphysis.

Femoral Fractures↗
PubMed1993

Effect of flexible drive diameter and reamer design on the increase of pressure in the medullary cavity during reaming.

Reaming the medullary cavity before insertion of an intramedullary nail, results in an increase in both temperature and pressure. This may lead to aseptic necrosis of the cortex and to fat embolism, whereby the increased pressure in the medullary cavity plays a significant role. This paper aims to determine whether a reduction of the drive diameter combined with a different reamer design reduces the amount of intramedullary pressure. The pressure levels were measured in plexiglass tubes filled with a mixture of vaseline and paraffin. The viscoelastic properties of this mixture at 20 degrees C were equivalent to those of bovine medullary fat at 36 degrees C. In comparison with the conventional reamer system (9.0 mm drive + 9.5 mm AO reamer), the 7.0 mm drive+AO reamer and the 7.0 mm drive+hollow reamer, the pressure values were reduced as follows: 1. 9.0 mm drive + 9.5 mm hollow reamer: diaphyseally by 19%, metaphyseally by 21% 2. 7.0 mm drive + 9.5 mm AO reamer: diaphyseally by 48%, metaphyseally by 49% 3. 7.0 mm drive + 9.5 mm hollow reamer: diaphyseally by 61%, metaphyseally by 66%. If the gap between the flexible shaft and the wall of the plexiglass tube became large enough, only small pressure values were recorded for all three types of reamer. In summary, it can be stated that the reduction of the drive diameter causes a sustained reduction in the intramedullary pressure, but that the newly developed hollow reamer only leads to a further reduction in pressure in combination with a thin flexible drive.

Equipment Design↗
PubMed1993

Two FIA-based biosensor systems studied for bioprocess monitoring.

In this paper, two different FIA-based biosensor systems are described for application to different biotechnologically relevant purposes. In the first system, single fiber optodes were used to determine the pH, urea and penicillin V concentrations. A two-channel system was developed for the simultaneous monitoring of different variables to increase the analysis accuracy. This system was used for monitoring the penicillin V concentration during a cultivation of Penicillium chrysogenum. The second system described is a calorimetric immunoassay based on the use of an enzyme thermistor. A sandwich assay with protein A immobilized on a solid support for the determination of various IgGs was established. A fusion protein of protein A and beta-galactosidase obtained from a recombinant E. coli strain was used in the labelling and detection reaction. This system is designed for future application in bioprocess monitoring.

Biosensing Techniques↗
PubMed1993

The long-term prognosis of AA and AL renal amyloidosis and the pathogenesis of chronic renal failure in renal amyloidosis.

Investigation of the long-term prognosis and pathogenesis of chronic renal failure in 225 cases of AA and AL renal amyloidosis (perireticular and perireticular + pericollagenous amyloidosis) yielded the following results: 1) The prognosis of both AA and AL amyloidosis is poor, and is worse than all other types of glomerulopathy with the exception of rapidly progressive glomerulonephritis. 2) The probability of maintaining renal function in AL amyloidosis is no lower than that in AA amyloidosis. 3) The prognosis of both AA and AL amyloidosis is significantly worse in cases in which the renal cortical interstitium exhibits fibrosis at the time of the biopsy than in those in which it is normal. 4) In AA and AL amyloidosis, as in various types of inflammatory glomerulopathy, the relative area of the renal cortical interstitium shows a significant positive correlation with the serum creatinine concentration and a significant negative correlation with the creatinine clearance. However, the extent of interstitial amyloid deposition does not correlate with the serum creatinine concentration. Deposition of amyloid in the renal cortical interstitium has no effect on renal excretory function. 5) The long-term prognosis of renal amyloidosis is related to the severity of the glomerular amyloidosis in as much as it is generally worse in Grades III to V than in Grades I and II. However, it must be borne in mind that the incidence of interstitial fibrosis, which is decisive for the long-term prognosis, increases with the severity of glomerular changes. 6) The long-term prognosis of renal amyloidosis is worse if acute renal failure or interstitial fibrosis is present at the time of the biopsy. Patients with both acute renal failure and interstitial fibrosis have the worst prognosis. 7) Isolated glomerular amyloidosis, even if there is severe vascular amyloidosis (vas afferns), does not lead to renal insufficiency or even to a rise in serum creatinine concentration. 8) The number of T lymphocytes in the tubular epithelium in AA and AL amyloidosis is significantly greater than normal, and the number of T lymphocytes, macrophages/monocytes, and fibroblasts/fibrocytes per unit area of interstitium is also significantly increased. 9) As far as the pathogenesis of renal cortical interstitial fibrosis in renal amyloidosis is concerned, it is proposed that, in some cases, this develops from the interstitial edema that is seen in biopsy specimens of patients with renal amyloidosis and acute renal failure.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

Human peritoneal mesothelial cells synthesize interleukin-6: induction by IL-1 beta and TNF alpha.

Recent studies have demonstrated increased levels of IL-6 in the peritoneal cavity during CAPD peritonitis. The current investigation was initiated (i) to examine the human peritoneal mesothelial cell (HPMC) as a possible source of this secreted IL-6 and (ii) to characterize the released product and examine its regulation by other cytokines. Unstimulated HPMC under growth arrested conditions released IL-6 in a time dependent manner. After 24-hour HPMC IL-6 release (mean +/- SEM, N = 13) (expressed as pg/micrograms cell protein) was 1.67 +/- 0.33. Stimulation of HPMC with IL-1 beta or TNF alpha resulted in a time (increasing up to 48 hr) and dose dependent IL-6 generation. After 24 hours the levels induced by IL-1 beta and TNF alpha (both at 1000 pg/ml) were (mean +/- SEM, N = 13) 19.08 +/- 2.98 and 6.62 +/- 1.72, respectively. Stimulation with combinations of IL-1 beta and TNF alpha resulted in additive increases in IL-6 release. This release could be inhibited by co-incubation with anti-IL-1 beta and/or anti-TNF alpha antibodies. The level of released HPMC IL-6 measured by immunometric assay (ELISA) correlated directly with that detected in the 7TD1 IL-6 bioassay (r = 0.63; P < 0.001). Western blot analysis of concentrated HPMC supernatants using specific anti-IL-6 antibody demonstrated immunoreactive bands at 23 and 28 Kd following IL-1 beta or TNF alpha treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1993

Determination of the acrosome reaction in human spermatozoa is predictive of fertilization in vitro.

The acrosome reaction was determined in aliquots from ejaculates of 74 patients undergoing in-vitro fertilization at the University of Giessen, Germany, by means of the triple-stain technique. The percentage of acrosome-reacted spermatozoa after low-temperature induction of the acrosome reaction was not significantly related with the fertilization rate (H test, P = 0.693, SJ test, P = 0.366). However, all patients showing < 13.0% acrosome-reacted spermatozoa had poor fertilization rates. Highly significant differences between patients could be detected by correlating the inducibility of the acrosome reaction with the fertilization rate (H test, P = 0.018; SJ test, P = 0.004); patients with high fertilization rates showed a corresponding high inducibility of acrosome reactions. From our results, it is evident that percentages of acrosome-reacted spermatozoa < 13.0% or an inducibility of the acrosome reaction of < 7.5% are indicative of subfertility.

Acrosome↗
PubMed1993

MCP-1 mRNA expression in basal keratinocytes of psoriatic lesions.

In addition to hyperproliferation of keratinocytes, psoriasis is characterized by pronounced leukocytic infiltration. In contrast to the epidermal localization of neutrophils and T lymphocytes, macrophages are almost exclusively restricted to the dermal compartment. By immunohistologic analysis, these dermal macrophages were mainly encountered in the papillary dermis and arranged along the rete ridges in close proximity to proliferating keratinocytes. Monocyte chemoattractant protein (MCP-1) anti-sense RNA probes yielded abundant signals over the proliferating basal keratinocytes of the tips of the rete ridges, and, to a lesser extent, in cells in the papillae. Thus, the strongest MCP-1 message in psoriatic lesions is found above the dermal-epidermal junction and this may explain the characteristic sub-basal distribution of dermal macrophages. These results suggest that MCP-1 is important in regulating the interaction between proliferating keratinocytes and dermal macrophages in psoriasis pathogenesis.

Antigens, CD↗
PubMed1993

The level of neuromuscular block needed to suppress diaphragmatic movement during tracheal suction in patients with raised intracranial pressure: a study with vecuronium and atracurium.

The effects of tracheobronchial suction before and after neuromuscular blockade with vecuronium (0.12 mg.kg-1; ED95 x 2; group A) and atracurium (0.4 mg.kg-1; ED95 x 2; group B) on intracranial pressure were studied in 18 neurosurgical patients with a Glasgow Coma Scale < 7. Despite adequate sedation, moderate to severe diaphragmatic movements (bucking and coughing) in response to carinal stimulation with significant increases in intracranial pressure (A: 18 SD 7 to 24 SD 8 mmHg; B: 19 SD 7 to 27 SD 5 mmHg) and subsequent decreases in cerebral perfusion pressure (group A: 69 SD 11 to 63 SD 8 mmHg; group B: 63 SD 11 to 59 SD 17 mmHg) could be observed without muscle relaxation. After a bolus dose of vecuronium or atracurium, profound neuromuscular paralysis quantified by the post-tetanic count, was observed after an onset time of 253 SD 72 s (vecuronium) and 159 SD 54 s (atracurium). Slight diaphragmatic movements could be elicited in only two patients in group A and in two patients in group B during tracheal suction; intracranial pressure (group A: 20 SD 8 to 20 SD 8 mmHg; group B: 19 SD 7 to 19 SD 7 mmHg) and cerebral perfusion pressure (group A: 65 SD 13 to 65 SD 13 mmHg; group B: 66 SD 12 to 65 SD 11 mmHg) remained unchanged. When coordinating respiratory therapy in neurosurgical intensive care patients, profound neuromuscular block, quantified by a post-tetanic count of at least 5 for vecuronium and 1 for atracurium, it is necessary to rule out any impact of diaphragmatic movement on intracranial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Comparison of cytokeratin fragment 19 (CYFRA 21-1), tissue polypeptide antigen (TPA) and tissue polypeptide specific antigen (TPS) as tumour markers in lung cancer.

Recently CYFRA 21-1, a new tumour marker measuring a fragment of cytokeratin 19, was introduced and proved to be suitable for the follow-up care and monitoring of the therapy of non-small cell lung carcinomas, especially squamous cell carcinomas of the lung. Besides CYFRA 21-1, there are two other tumour markers available, called tissue polypeptide antigen (TPA) and tissue polypeptide specific antigen (TPS), which also measure different cytokeratins in serum. In a retrospective study we investigated the clinical significance of these 3 cytokeratin markers in lung cancer compared with carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC) and neuron-specific enolase (NSE). We investigated the sera of 50 healthy persons, 273 patients with various benign diseases and 218 patients with histologically proven lung cancer. In a first step the specificity versus benign diseases of the lung was established for all the markers, and was fixed at 95%. Then the single and combined sensitivities were calculated. CYFRA 21-1 proved to possess the highest sensitivity in lung cancer in general (61%), in non-small cell lung carcinomas (64%), in squamous cell carcinomas (79%), in adenocarcinomas (54%) and in large cell carcinomas (65%). In small cell lung carcinomas, neuron-specific enolase proved again to be the marker of first choice (55%). Combined determinations proved clearly increased sensitivity only for large cell carcinomas (CYFRA 21-1 + TPA: 77%) and for small cell lung carcinomas (CYFRA 21-1 + NSE: 62%).(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Neoplasm↗
PubMed1993

Prediction of fixation failure in femoral neck fractures. Comminution and avascularity studied in 40 patients.

We performed 99m-Tc diphosphonate scintimetries in 40-elderly patients who had undergone screw fixation for a recent subcapital femoral fracture and analyzed their preoperative radiographs. The data were subjected to a logistic regression analysis. Both comminution of the calcar femorale and reduced scintimetric uptake were predictive for failure of the osteosynthesis during the first year. Fracture comminution was more predictive for early failures during 3 months and scintimetry for the later failures.

Aged↗
PubMed1993

Relationship of antibodies against CD4+ T cells in HIV-infected patients to markers of activation and progression: autoantibodies are closely associated with CD4 cell depletion.

Antibodies against lymphocytes have been shown in human immunodeficiency virus (HIV)-infected patients, but their relevance in the pathogenesis of acquired immune deficiency syndrome (AIDS) remains controversial. We investigated increased levels of lymphocyte surface Ig and antibodies against CD4+ T cells in the plasma. The relationship to CD4 cell depletion and serological parameters were analysed. A three-colour flow cytometric method was used to detect surface Ig on the surface of patients' cells and antibodies in the plasma of the patients. We observed a high percentage of patients with increased surface Ig on CD4+ T cells (94%-47/50). Antibodies in the plasma reacting with healthy donors' CD4+ T cells were detectable in 72% (23/32) of the patients. CD4 cell-surface Ig correlated well with surface Ig on different T-cell subpopulations but not with increased surface Ig on B cells. Only one control showed elevated surface Ig, plasma antibodies against lymphocytes were not detectable. Surface Ig levels of CD4+ T cells were closely associated with the CD4 cell number in HIV-infected patients of all stages of disease (r = -0.67, P = 0.00005). Other lymphocyte subsets' surface Ig did not show a significant association to CD4 cell depletion. Surface Ig and antibodies against CD4+ T cells were not related to levels of beta 2-microglobulin, p24 antibodies or interleukin-6 (IL-6), and did not depend on hypergammaglobulinaemia. In conclusion surface Ig on CD4+ T cells is likely to have an autoantibody origin. The high prevalence and association to CD4 depletion support the view that autoimmune phenomena could be involved in the pathogenesis of AIDS.

Autoantibodies↗
PubMed1993

Hepatocyte aggregate culture technique for bioreactors in hybrid liver support systems.

Utilizing a modified culture technique for hepatocytes, a high performance suspension culture is possible in which hepatocytes spontaneously form cell aggregates. The aggregates of 20-100 cells have been histologically confirmed to hold a three-dimensional structure, they show a long-term external metabolism and a survival time comparable with standard adhesion cultures. This technique has several advantages in the construction of large scale bioreactors for hybrid liver support systems.

Animals↗
PubMed1993

[Visuo-vestibular interaction in determination of orientation behavior in weightlessness].

We measured vertical vection during a short term space flight and 2 long term space flights to evaluate the state of adaptation to microgravity. The first phase of microgravity adaptation showed with major changes of vertical vection perception such as "inverted vection". This method will be used to reveal mechanisms of adaptation to altered vestibular inputs.

Adaptation, Physiological↗