Biomedical subjects

M Morlock

Publications and source records attributed to M Morlock.

28 records · Page 2Linked to original sources

PubMed1998

[Dream contents of sleep disordered patients].

The present study investigates dreams reports of patients with sleep disorders. Whereas, the findings scarcely showed specific dream contents for different sleep disorders, e.g. problematic dreams in insomniacs, breathing-related dreams in sleep-apnea-patients, a remarkable relationship between waking life and dream contents did occur. Private problems and occupational stress are reflected in dreams by means of increased negative feelings, aggression and occupational themes. The results suggest that dreams can be made use of in psychological invention methods in sleep disorders, e.g. stress management.

Adult↗

PubMed1997

Long-term in vivo alterations of polyester vascular grafts in humans.

OBJECTIVES: To examine the influence of in vivo hydrolysis on the physical properties of polyester grafts and their correlation to the period of implantation in the human body. MATERIALS AND METHODS: Sixty-five explanted vascular grafts were obtained after 0-23 years of implantation due to suture aneurysms (18), occlusion (12), graft infection (12), failure of graft material (7) and post-mortem (16). The surface was examined by scanning electron microscopy, the molecular integrity by infra-red spectroscopy and physical strength by probe puncture. RESULTS: Scission of macromolecular chains and loss of strength were shown. It was demonstrated that hydrolytic degradation of polyester takes place with increasing time of implantation in humans. Analysis by linear regression showed that polyester grafts lose 31.4% of their bursting strength in 10 years and 100% in 25-39 years after implantation. CONCLUSIONS: Regular follow-ups of patients with aged vascular grafts and the precise documentation of implanted materials are necessary to estimate graft degradation.

Blood Vessel Prosthesis↗

PubMed1996

[Childhood memories and adult dreams].

The present retrospective study investigated the often cited clinically relevant relationship between dreams and childhood memories. Indeed, the hypothesis was confirmed that high dream recallers remember more childhood memories than low dream recallers. Whether this is a pure cognitive relationship (memory) or could reflect general personality tendencies request further investigations. Additionally, the high incidence of childhood nightmares in a normal population was stressed.

Adolescent↗

PubMed1990

Possible role of H1 histone in the differentiation of mouse erythroleukemia cells.

Serum-starved mouse erythroleukemia cells, stationary phase cells or cells cultured in dibutyryl cAMP (1 mM) can be induced to differentiate by addition of 20% fetal calf serum plus cycloheximide. Culturing unstarved log phase cells in 20% fetal calf serum plus low levels of cycloheximide and histone H1 also causes a significant level of differentiation. These same concentrations of cycloheximide and H1 histone employed separately with 20% fetal calf serum do not induce differentiation. The role these procedures may have in causing an accumulation of histone H1 and cell differentiation is discussed.

Animals↗

PubMed1989

The appropriate use of regression equations for the estimation of segmental inertia parameters.

Linear regression equations are commonly used in conjunction with experimental data to provide linear relationships between quantities which are dimensionally distinct. In many cases theoretical relationships between such quantities are known and can be used as a basis for non-linear regression equations. This study compares linear and non-linear approaches for estimating the segmental moments of inertia from anthropometric measurements using the data of Chandler et al. [Chandler et al. (1975) Investigation of inertial properties of the human body. AMRL Technical Report 74-137, Wright Patterson Air Force Base. OH.] Right limb data were used to derive the equations while left limb data were used as a cross-validation sample to evaluate the inertia estimates calculated from the equations. For the limb segments the standard error estimates had average values of 21% for the linear equations and 13% for the non-linear equations. Data on a 10 yr-old boy was used to compare the two approaches outside the sample range. The mean percentage residuals were 286% for the linear equations and 20% for the non-linear equations. A set of non-linear equations is provided.

Arm↗

PubMed1987

The influence of lateral heel flare of running shoes on pronation and impact forces.

The purpose of this investigation was to study the influence of the flare at the lateral side of the heel of running shoes on: initial and total pronation; impact forces in heel-toe running; and to explain the results with a mechanical model. The experimental part of the study was performed by using 14 male runners. Their running movement (4 m/s) was quantified by using a force platform and high-speed film (100 frames X s-1). Three shoes were used, identical except in their lateral heel flare, one shoe with a conventional flare of 16 degrees, a second shoe with no flare, and a third shoe with a rounded heel (negative flare). The experimental results indicate that (for the used set of shoes); increasing heel flare increases the amount of initial pronation; changes in heel flare do not affect the magnitude of the total pronation; and changes in heel flare do not alter the magnitude of the impact force peaks. Since shoes with rounded lateral heels do reduce initial pronation, it is speculated that this construction could be used to prevent anterior medial compartment syndrome at the tibia of runners. It was concluded that more research is needed to specify whether the reported result is representative for various shoe types or is shoe specific.

Biomechanical Phenomena↗

PubMedDate not supplied

[Water jet discotomy with microinvasive approach--in vitro testing and initial clinical aspects of a new procedure].

AIM: The difference in consistence of the nucleus pulposus and the annulus fibrosus allows the water jet to selectively remove the nucleus in a closed vertebral disc at a certain pressure range. The aim of the study was to investigate the use of water jet cutting in microinvasive spinal surgery. METHODS: A comparison in terms of efficiency between the water jet and those of the laser and APLD (automatic percutaneous lumbar discotomy) was achieved by plastic reconstruction of the resected spaces using the in-vitro-model of the spinal column of young pigs. The in-vitro-study was followed by a prospective clinical study with 21 patients. RESULTS: The in-vitro-employment of the three different methods showed that there were no significant differences in volume of the removed nucleus material. During the use of the hydro jet at 50 bar and simultaneous suction the intradiscal pressure measured in vitro remained below 1 bar. Clinical tests on the 21 patients showed good to very good results in 71% of the patients tested (mean follow-up 5.8 months). No complications were found. As working mechanism the pure mechanical effect and the influence on chemical processes within the nucleus remain points for discussion. CONCLUSION: The current studies results demonstrate that hydrojet spinal surgery might be a safe new method for surgery of disc protrusion and contained prolapse.

Adult↗

PubMedDate not supplied

[Use of a water jet for synovectomy: in vitro study of feasibility].

AIM: The selectivity of a water jet (WJ) is already used with clinical advantage in the surgery of liver, brain, kidney and herniated lumbar discs. The aim of the present study was to determine whether a WJ can be used for synovectomy without damaging the joint capsule and the cartilage. METHOD: 60 human cadaver knee specimens (67 +/- 14 years) were dissected into synovial and cartilage samples. They were randomly assessed to four pressure groups (pW = 3; 6; 9; 12 MPa) and three jet surface angles (beta = 30; 60; 90 degrees) The nozzle diameter was dD = 0.12 mm, the stand off distance of the jet was s = 10 mm with a feed rate of vV = 2 mm/s. The acquired parameters were depth of the cuts, histological layer, and change of the samples thickness. RESULT: There was a correlation of the cutting depth and the pressure (pW), whereas the jet-surface angle (beta) showed no correlation. The synovial layer of the cut likewise correlated with the pressure. At pW = 6 MPa the stratum subsynoviale could be cut selectively without damaging the fibrous capsule or the cartilage. The increase of the samples thickness was caused by an interstitial oedema. CONCLUSION: The different mechanical properties of the joint capsule and the stratum subsynoviale lead to the selective cutting of the water jet. Since the joint capsule was not damaged, the feasibility of WJ synovectomy has been proven. The device can be used for synovectomy in parts of the joint that are not visible as well as in very small joints.

Aged↗

PubMedDate not supplied

[Mechanical study of potential ceramic implant materials for minimal invasive anterior lumbar interbody fusion].

While autologous bone grafts are highly suitable for use in spinal arthrodesis, their use is also associated with problems (traumatization, complications). Ceramic bone substitute materials provide an attractive alternative for lumbar interbody spinal fusion. The aim of the present study was to investigate the mechanical properties of various types of ceramic using a specific fusion method. Ten specimens each of 7 different types of ceramic were tested using a hydraulic testing machine with two different sample holders: polyurethane foam (mechanical properties similar to cancellous bone) and aluminium. The parameters axial compression and axial torque were investigated. With the polyurethane foam holders, none of the ceramic implants failed under compression, while under axial rotation, two types of ceramic failed. With the aluminium holders, 3 ceramics showed no failure up to 25 kN under compression, while under torsion all the ceramics failed. One type of ceramic showed specific fracture properties with a higher load-bearing capacity after failure in comparison with all the other types studied.

Biomechanical Phenomena↗

PubMedDate not supplied

[Dream recall and sleep disorders].

The present study investigated the relationship between dream recall and sleep disorders. The sample comprised 762 patients who were diagnosed in the sleep laboratory. In the course of the examination they completed the sleep questionnaire SF-B (Görtelmeyer 1986). The results showed a heightened dream recall frequency (DRF) in insomniacs and patients with myoclonia. This result as well as the findings in the control group supports the arousal-retrieval model of dream recall (Koulack u. Goodenough 1976) which emphasizes the importance of nocturnal awakenings. However, this model seems only to be valid for males. In females, DRF is mainly influenced by emotional stress which is best explained by the salience hypothesis of Cohen and MacNeilage (1974). They pointed out that intensive dream emotions lead to high recallability of dream experience. The data gives evidence to the hypothesis of Ermann et al. (1993, 1994) which states that reduced DRF in terms of unsuccessful dream work is accompanied by frequent nocturnal awakenings. DRF of patients with sleep apnea syndrome did not differ from DRF in healthy controls. In addition, sleep apnea parameters did not correlate substantially with DRF. The finding that insomniacs reported more negatively toned dreams in comparison to persons who were examined for sleep apnea but did not showed a pathological apnea index. This may be an hint to increased emotional stress in this patient group. To summarize, the results are promising in clarifying the relationship between sleep disorders and dream life. The next step is to investigate dream reports of these patients by means of content analysis.

Adult↗