Biomedical subjects
Publications and source records attributed to M Richter.
We report the case of a 70-year-old man who suffered recurrent dislocations of the temporomandibular joint secondary to severe Parkinson syndrome. The patient was given repeated injections of botulinum toxin. After 3 injections over a 9-month period, no further dislocation occurred. Botulinum toxin may be an alternative to surgery.
The cholinergic system is critically involved in oscillatory network activity and synaptic plasticity in the entorhinal cortex (EC) hippocampal formation. Here we demonstrate robust inhibition of field potentials in layer II of the medial EC evoked by stimulation in the deep EC or in the lateral layer II by carbachol (CCh, 0.1-100 microM, K(D) approximately 1 microM). This effect appears not to be mediated by suppression of presynaptic Ca(2+)-signals since paired pulse facilitation was increased by CCh. Blockade of the effect by the muscarinic antagonists atropine and pirenzepine demonstrates mediation by muscarinic receptors, most likely of the M1 subtype. The effect is characterized by absence of desensitization and should be important for laminar shaping of oscillatory activity and synaptic plasticity during acetylcholine-dependent theta-rhythmic activity.
The fast and slow reversible components of non-photochemical chlorophyll fluorescence quenching commonly assigned to the qE and the qI mechanism have been studied in isolated pea thylakoids which were prepared from leaves after a moderate photoinhibitory treatment. Chlorophyll fluorescence decays were measured at picosecond resolution and analyzed on the basis of the heterogeneous exciton/radical pair equilibrium model. Our results show that the fast reversible non-photochemical quenching is completely assigned to the PS II antenna and is related to zeaxanthin. The slow reversible qI type quenching is located at the PS II reaction center and involves enhanced nonradiative decay of the primary charge separated state to its ground state and/or triplet excited state. Apart from its independence from the proton gradient, the qI quenching shows striking similarities to a particular form of qE quenching which is also located at the PS II reaction center and has resently been resolved in isolated thylakoids from dark-adapted leaves [Wagner, B., et al. (1996) J. Photochem. Photobiol., B 36, 339-350]. Our data suggest that during exposure to the supersaturating light the reaction center qE component was replaced by qI quenching. This qE to qI transition is supposed to be part of the mechanism of the long-term downregulation of PS II during photoinhibition. It is also evident that under the conditions used in our study zeaxanthin-dependent antenna quenching is not involved in the slow reversible downregulation of PS II but that it retains its dependence on the proton gradient during exposure to strong light.
HISTORY AND ADMISSION FINDINGS: A 70-year-old woman with type 2B diabetes mellitus was referred to the dermatology department because of inflammatory skin changes of unknown origin over the trunk and limbs. On admission follicular and parafollicular livid-red papulae with central crusts and reddened margins were noted over the lower legs and the lumbosacral region. INVESTIGATIONS: Further physical examination revealed no additional abnormalities. Erythrocyte sedimentation rate was 41/79 mm. The day-time blood-glucose profile was raised (10.2, 12.6 and 8.6 mmol/l), as was the glycosylated haemoglobin HbA1c (9.0%). Swabs from fresh lesions gave no evidence of fungal or bacterial infection. Biopsies revealed areas of widened epidermis with central ulceration filled with fibrin, granulocytes and collagen fibres. DIAGNOSIS, TREATMENT AND COURSE: The clinical and histological findings indicated an acquired reactive perforating collagenosis (dermatosis) which should be judged in relation to the long-standing diabetes mellitus. The cutaneous changes were covered with salicylate- and steroid-containing preparations, while individual lesions were excised or removed by curettage. CONCLUSION: The condition of acquired reactive perforating collagenosis is, like Kyrle's disease (perforating follicular and parafollicular hyperkeratotic dermatosis), perforating serpiginous elastosis and perforating folliculitis classified among the perforating dermatoses. In the presence of renal failure and (or) diabetes mellitus these dermatoses must be thought of in the differential diagnosis, in addition to the more frequent pruriginous conditions, if there are corresponding skin changes.
STUDY DESIGN: The primary biomechanical stability of anterior internal fixation of the cervical spine obtained with a new monocortical expansion screw in vitro was evaluated. OBJECTIVES: To determine whether the anterior internal fixation of the spine obtained with the new monocortical expansion screw provides biomechanical stability comparable with that obtained with bicortical fixation. SUMMARY OF BACKGROUND DATA: The anterior plate instrumentation used with bicortical screw fixation in the cervical spine provides a primary stability superior to that associated with monocortical screw fixation. However, bicortical screws have the potential to perforate the posterior cortex. Therefore, monocortical instrumentation systems were developed, but without the biomechanical stability associated with bicortical systems. A new expansion screw for monocortical fixation was developed to improve biomechanical stability of monocortical systems. METHODS: Three different internal fixation systems were compared in this study: 1) H-plate with AO 3.5-mm bicortical screws, 2) cervical spine locking plate with monocortical screws, and 3) H-plate with the new monocortical expansion screws. Eight fresh human cadaver spine segments from C4 to C7 were tested in flexion-extension, axial rotation, and lateral bending using pure moments of +/- 2.5 Nm without axial preload. Five conditions were investigated consecutively: 1) intact spine; 2) uninstrumented spine with the segment C5-C6 destabilized; 3-5) instrumentation of the segment C5-C6 with the three implants mentioned above after removal of the disc and insertion of an interbody spacer. RESULTS: Between bicortical and monocortical expansion screw H-plate fixation, no significant differences were observed in all load cases concerning range of motion and neutral zone. The neutral zone and range of motion were significantly larger for the cervical spine locking plate than for bicortical and monocortical expansion screw fixation in all load cases, except neutral zone for axial rotation versus bicortical screw fixation. The instrumented cases only had a significantly lower range of motion and neutral zone than the intact cases in extension-flexion, whereas for lateral bending and axial rotation no significant differences could be observed. Because the experimental design precluded any cyclic testing, the data represent only the primary stability of the implants. CONCLUSIONS: In anterior instrumentation of the cervical spine using a H-plate, the new monocortical expansion screw provides the same biomechanical stability as the bicortical 3.5-mm AO screw and a significantly better biomechanical stability than the cervical spine locking plate. Therefore, the expansion screw may be an alternative to the bicortical fixation and does not involve the risk of penetration of the posterior vertebral body cortex.
At the Heavy Ion Research Institute GSI in Darmstadt an experimental cancer treatment program with a five years duration has been developed. A new method for cancer treatment with ions is applied, using rasterscan method in addition to an active pulse to pulse variation of ion beam properties, including the energy, intensity and focusing. An overview of this Cancer Therapy Project is presented, that covers both accelerator aspects to provide the required beam variations within a short time and the installations at the treatment place for rasterscan control. In addition to a description of the technical design (control-hard- and software) experimental results will be shown, containing the achieved beam properties and measurements of rasterscan performance.
INTRODUCTION: Injuries precede the vast majority of all odontoid pseudarthroses. Because of specific anatomic conditions type II injuries lead more often than other types to non unions. For its development insufficient internal or external fixation and a persisting fracture gap are crucial. METHODS AND RESULTS: In 71 patients after operative stabilization of odontoid fractures with two anterior lag-screws we detected 8 non unions. In 3 patients the interval between accident and operation amounted to more than 5 weeks, seven times we did not succeed in closing the fracture gap. Technical mistakes like insufficient reduction (n = 1) or screw misplacement (n = 3) were additional reasons. According to the literature and own observations an os odontoideum must be considered in most instances as a pseudarthrosis after a lesion of the subdental synchondrosis in childhood. The most important diagnostic tool in odontoid non unions is a dynamic examination of the upper cervical spine under fluoroscopic control in maximum flexion and extension. We propose a classification of posttraumatic dens non unions into 4 types. Type I corresponds to a stable "non union" in approximate anatomical position of the dens and without signs of instability in the former fracture zone. Type II describes a relatively stable grossly displaced non union that is not to be reduced by simple, closed means. Type III means an unstable non union and Type IV a posttraumatic os odontoideum. CONCLUSIONS: Therapeutical recommendations need to be differentiated. Unstable non unions are most often responsible for persistent pain, may result in acute or chronic myelopathy++ and therefore - as well as ossa odontoidea - need operative fixation. In considerably displaced non unions a closed reduction manoeuver with long term traction should be tried. The operative treatment of choice is the posterior transarticular screw fixation C1/C2 desirably in a percutaneous technique. Tight, "stable" pseudarthroses in the sense of a persisting fracture gap in painfree patients should first be controlled radiologically. If the odontoid position remains unchanged, non operative treatment may be continued.
INTRODUCTION: Traumatic dislocation is the most severe ligamentous injury of the knee. The indications for operative and conservative treatment are still controversial. METHODS AND RESULTS: From 1974 to 1994, 38 patients with documented knee dislocation were treated operatively in our department. Thirty-four of these patients were followed up for 3-16 years (mean: 8.6 years). In 29 cases of the follow-up group, reconstruction of both cruciate ligaments was performed. In the remaining cases the cruciate ligaments were left alone. At the time of follow-up, 90 % of the patients showed good knee stability, but 90 % had lack of motion as well. Post-traumatic osteoarthritis was mostly mild to moderate. Thirty-five percent of the patients achieved excellent to good results in the Lysholm Score. CONCLUSIONS: Positive prognostic factors were an age less than 40 years at the time of the accident, a low-energy trauma, e. g., a sports-related injury, early reconstruction of both cruciate ligaments, and initial postoperative functional treatment.
During 1973 and 1989, 6,378 car accidents with 8,931 injured persons were evaluated in the area of Hannover. 3,267 car drivers and passengers sustained fractures overall and 148 (4.5%) fractures of the foot. A major role in the etiology of the foot fractures evolves from the deformation of the foot room. Driver and front seat passenger showed similar injuries. Among the 286 single fractures, the forefoot was affected most often (45%), followed by ankle (38%), midfoot (11%) and hindfoot (6%). 5% were open fractures. The long term results were estimated upon the limitation of working ability caused by the foot injury in relation to the entire working ability. The evaluation concludes that the foot fractures especially in combination with other injuries were frequently not recognized within the primary examination and therefore underestimated. The long-term outcome leaded to a high degree of impairment due to foot fractures.
For posttraumatic atlantoaxial instabilities posterior transarticular screw fixation according to Magerl represents the treatment of choice. In order to be able to insert the screws steep enough the soft tissues of the neck have to be dissected down to C7. Several authors therefore described a percutaneous technique. We analysed 30 patients with a sagittal atlantoaxial instability treated with one of both methods between the years 1995 and 1998 to detect any differences of either technique. In 19 cases we used a modified percutaneous technique with special instruments as has been published by McGuire and Harkey. On lateral plain films the angle between the screws and the lower endplate of C2 was measured. 6 to 24 months after the accident 26 patients could be seen clinically and controlled radiologically, 4 patients had died in the meanwhile. The angle of the screws were significantly different with 10 degrees (percutaneous group 73.9 degrees, open group 63.9 degrees, p = 0.001). Time needed for the operative procedure averaged 35 minutes shorter with the cannulated technique (93 to 128 minutes, p = 0.05). All posterior fusions had healed radiologically. Active motion of the c-spine was restricted in both groups equally. We checked subjective criteria concerning pain and function with a visual analog scale and a special score. With these instruments advantages for the percutaneous procedure could be found (freedom of pain 43 points (percutaneous) versus 39 points (open), p = 0.05). We conclude that the soft tissue preserving percutaneous technique of screw application for C1/C2 posterior fusion allows for a better and easier placement of screws. It also leads to a shorter operating time and better subjective results. The method offers particularly advantages in cases where only a temporary stabilization of the C1/C2 complex without a regular fusion is needed.
The results of prospective anterior cruciate ligament (ACL) refixation in 33 patients with high proximal rupture is reported at 20-28 months' follow-up: mean age was 31.1 +/- 12.5 years. The surgical technique was a specially developed refixation of the ACL using a multiple suture loop (modified Marshall technique) augmented with intra-articular PDS II (polydioxanon, resorbable, Ethicon, Hamburg, Germany) to avoid derangement of blood circulation and to guarantee early functional rehabilitation. All patients were operated on within 7.3 +/- 4.5 days after injury. According to the IKDC evaluation score, 22 patients showed excellent and 10 patients good subjective function. Twenty regained their pre-injury level of activity. Anterior stability was tested manually and by KT-1000 max (Medmetric, San Diego). Twenty-eight patients had a firm end-point, although there was a positive Lachman test in 16 patients. Maximal joint laxity as measured by KT-1000 showed a 1-2 mm, 3-5 mm, 6-10 mm and > 10 mm anterior drawer for 16, 14, 2 and 1 patients, respectively. Twenty-five of the evaluated knee joints had a negative pivot shift test. Three patients had a limited range of motion. The potential advantages of PDS II-augmented refixation of acute proximal ACL ruptures are anatomic reconstruction without destruction of other anatomic structures used as grafts, early functional rehabilitation and possibly better proprioception.
The aim of this study was to examine sensitivity and specificity of Durkan test in 54 patients with carpal tunnel syndrome confirmed by electrophysiological testing, as compared to a control group of 54 patients without clinical signs of the syndrome. Sensitivity and specificity of Durkan test alone, as well as in combination with Phalen test and Hoffmann-Tinel test, were determined. The sensitivity of Durkan test was 0.87, its specificity was 0.96. The sensitivity of Phalen test was 0.85 with a specificity of 0.96. It was discovered that the combination of Phalen with Durkan test achieved a sensitivity of 0.94 and a specificity of 0.96, thus equalling the respective values for electrophysiological testing (nerve conduction velocity, electromyography) which so far is regarded as the golden standard diagnostic test for carpal tunnel syndrome. If Hoffmann-Tinel test is included as a further clinical parameter, then both sensitivity and specificity reach 0.96. This study, therefore, raises the question of whether costly electrophysiological testing is in fact necessary before surgery for carpal tunnel syndrome, when the clinical tests have already proven positive.
A series of continuous ambient tropospheric ozone measurements were taken in Mendoza, Argentina, for a period of one year starting in November 1995. The data obtained were analyzed in terms of diurnal and annual variation. Indications were found of the strong impact of the mountain-valley circulation system, which ventilates and considerably cleans the air in Mendoza. The data are discussed in comparison with air pollution in the German city of Leipzig. In Mendoza, the high concentration of precursors and the strong solar radiation contribute to high levels of ozone. In fact, monitoring reveals considerably lower concentrations than in Leipzig, owing to the diluting effect of local meteorology. The low-level jet is mainly active during the summer. It lowers the peak mid-day ozone concentration and produces a temporary concentration increase at night. The Environmental Protection Agency standard of a maximum one-hour mean concentration of 0.250 mg ozone/m3 (125 ppb) is never reached, and the World Health Organization standard of 0.113 mg ozone/m3 (56.5 ppb) is only rarely exceeded during winter.
A case of calcium pyrophosphate dihydrate (CPPD) crystal deposition arthropathy of the temporomandibular joint is reported. The patient presented a 10-year history of swelling and pain of the left preauricular region. Magnetic resonance imaging showed a calcified mass filling the joint space and destroying the roof of the joint. Radiographs showed chondrocalcinosis of other joints. The authors discuss the diagnosis of this arthropathy and the reason why the temporomandibular joint is more affected than the other joints in the patient reported.
PURPOSE: To evaluate whether the different signal intensities at magnetic resonance (MR) imaging of melanoma are associated with a higher content of melanin. MATERIALS AND METHODS: In a prospective study, MR imaging and ophthalmoscopic examination findings in 42 patients (19 women, 23 men; age range, 30-87 years) with uveal melanoma were compared with histopathologic examination findings obtained after enucleation. MR imaging was performed with 2-mm sections by using a 5-cm surface coil. T1- and T2-weighted images were obtained before and after contrast material administration. RESULTS: In 33 (79%) of the patients, there was homogeneous tumor pigmentation, whereas in nine (21%) patients, there was inhomogeneous bipartite tumor pigmentation. Compared with the histopathologic data, the results of qualitative evaluation were accurate in 29 (58%) of 50 and in 26 (53%) of 49 tumorous areas on T1- and T2-weighted images, respectively. Quantitative evaluation yielded better results, especially at T1-weighted imaging; an 86% correlation was found. Because of methodological reasons, only the superficial pigmentation of inhomogeneous tumors could be evaluated with ophthalmoscopy. CONCLUSION: Thin-section MR imaging of the eye enables an accurate prediction of melanomatous pigmentation with quantitative evaluation of plain T1-weighted images and is superior to ophthalmoscopy in cases of inhomogeneous pigmentation.
Descriptions of affective disorders among Jews date back to biblical times. For over a century the psychiatric literature has debated whether Jews are more vulnerable to affective disorders. To ascertain the validity of this finding we undertook a meta-analysis of data extracted from the literature published to date. Forty-three studies were identified that could be analysed statistically using Cohen's d and a Mantel-Haenszel summary odds ratio. An increased, but weak overall risk was found for males. Possible biases of the literature are discussed, including differential help-seeking patterns, lack of accounting for readmission rates, failure to control for confounding variables, and an anti-Semetic orientation on the part of researchers. Reasons for why Jews have higher rates of affective disorders than non-Jews are explored.
Flavonoids are among the best candidates for mediating the protective effect of diets rich in fruits and vegetables with respect to colorectal cancer. To gain additional information about their growth effects on colorectal tumors and their cellular mechanisms of action, a series of related flavonoids was added to cultures of colonic tumor cells. Most compounds induced growth inhibition and cell loss at concentrations of 1-100 microM, relative effectivity being quercetin > apigenin > fisetin > robinetin and kaempferol. Myricetin was only slightly effective. Quercetin was the strongest inducer of apoptosis in a process that was reversible until 10 hours by flavonoid removal and until 24 hours by fetal calf serum. Cells were preferentially retained in the S phase. On the cellular level, quercetin sensitivity was correlated with epidermal growth factor (EGF) receptor levels, rapid growth, and poor differentiation, indicating the possibility of targeting those cells most harmful for the organism. The flavonoid transiently inhibited EGF receptor phosphorylation but had only little effect on other signaling molecules. Even after recovery of receptor phosphorylation, cells remained resistant to EGF stimulation. In summary, the data indicate that inhibition of EGF receptor kinase is an integral part of quercetin-induced growth inhibition, but additional mechanisms also contribute to the overall effect.
Intramedullary nailing of metaphyseal fractures may be associated with deformity as a result of instability after fixation. Our aim was to evaluate the clinical use of Poller screws (blocking screws) as a supplement to stability after fixation with statically locked intramedullary nails of small diameter. We studied, prospectively, 21 tibial fractures, 10 in the proximal third and 11 in the distal third in 20 patients after the insertion of Poller screws over a mean period of 18.5 months (12 to 29). All fractures had united. Healing was evident radiologically at a mean of 5.4+/-2.1 months (3 to 12) with a mean varus-valgus alignment of -1.0 degree (-5 to 3) and mean antecurvatum-recurvatum alignment of 1.6 degrees (-6 to 11). The mean loss of reduction between placement of the initial Poller screw and follow-up was 0.5 degrees in the frontal plane and 0.4 degrees in the sagittal plane. There were no complications related to the Poller screw. The clinical outcome, according to the Karström-Olerud score, was not influenced by previous or concomitant injuries in 18 patients and was judged as excellent in three (17%), good in seven (39%), satisfactory in six (33%), fair in one (6%), and poor in one (6%).