MR imaging of ulnocarpal impaction after fracture of the distal radius

OBJECTIVE

The purpose of our study was to evaluate the incidence of ulnocarpal impaction after distal radius fracture using MR imaging and to correlate imaging findings with those of radiography and clinical findings.

CONCLUSION

Ulnocarpal impaction is a common finding after distal radius fracture. MR imaging can detect characteristic bone marrow changes of the lunate early after the trauma. A significant correlation exists between MR imaging findings and the extent of posttraumatic ulnar variance and pain levels.

Das akute CRPS I (Morbus Sudeck) nach distaler Radiusfraktur - Methoden der Frühdiagnostik

INTRODUCTION

CRPS I represents a frequent complication following distal radial fractures. Early diagnosis may prevent chronification of the disease. However posttraumatic pain, swelling and motor disturbances render the differentiation from normal fracture patients more difficult. The incidence of CRPS I in patients at risk and the diagnostic value of clinical evaluation, radiography and thermography in the early posttraumatic phase are analysed.

METHODS

158 consecutive patients with distal radial fractures were followed-up for 16 weeks after trauma. Apart from a detailed clinical examination 8 and 16 weeks after trauma, thermography and bilateral radiographs of both hands were performed.

RESULTS

At the end of the observation period 18 patients (11%) were clinically identified as CRPS I. The severity of the preceding trauma and the chosen therapy did not influence the process of the disease. 16 weeks after trauma easy differentiation between normal fracture patients and CRPS I patients was possible. 8 weeks after distal radial fracture clinical evaluation showed a sensitivity of 78% and a specificity of 94%. Thermography (58%) however and bilateral radiography (33%) revealed a poor sensitivity, respectively. The specificity was high for radiography (91%) and again poor for thermography (66%), respectively.

CONCLUSION

The results of the study support the importance of clinical evaluation in the early diagnosis of CRPS I. Plain radiographs facilitate the diagnosis as soon as bony changes develop.

No linkage of the interleukin-4 receptor locus on chromosome 16p11.2-12.1 with sarcoidosis in German multiplex families

We typed 241 members of 62 sarcoidosis families with 136 affected siblings for three single nucleotide polymorphisms of the interleukin-4 receptor alpha-chain gene (IL4R). Allele frequencies in patients were compared to those of healthy unrelated control individuals. The segregation of the three-point IL4R haplotypes completed by two flanking highly polymorphic microsatellite polymorphisms revealed no evidence for linkage of the IL4R gene locus with sarcoidosis.

Effectiveness of twice-weekly pyrimethamine-sulfadoxine as primary prophylaxis of Pneumocystis carinii pneumonia and toxoplasmic encephalitis in patients with advanced HIV infection

The safety and efficacy of a fixed 25 mg pyrimethamine-500 mg sulfadoxine combination supplemented with 15 mg folinic acid twice a week as primary prophylaxis of Pneumocystis carinii pneumonia (PCP) and toxoplasmic encephalitis was evaluated in 106 patients infected with the human immunodeficiency virus. All patients had a CD4+ T-lymphocyte count of less than 100 cells/microl at study entry. Efficacy in this single-arm open-label prospective study was analyzed on an as-treated basis. No patient received highly active antiretroviral treatment, including protease inhibitors or non-nucleoside reverse transcriptase inhibitors, while on study medication. PCP developed in four patients, one of whom had been noncompliant. No PCP episode occurred in the first year. Probabilities of freedom from PCP were 0.97 (95%CI, 0.92-1) after 24 months and 0.93 (95%CI, 0.84-1) after 36 months. Of 74 (69.8%) patients positive for anti-toxoplasma IgG antibodies, one noncompliant patient developed toxoplasmic encephalitis after 24 months. Allergic reactions were observed in 18 (17%) patients and resulted in permanent discontinuation in 7 (6.6%) patients. One (0.9%) patient who had continued prophylaxis despite progressive hypersensitivity reactions developed a serious adverse reaction (Stevens-Johnson syndrome). The median survival of study participants was 29 months, with relentless progression of AIDS accounting for most deaths. The prophylaxis regimen studied appeared safe and effective for primary prophylaxis of PCP and toxoplasmic encephalitis. Severe adverse events can likely be prevented by discontinuation of prophylaxis at the time allergic reactions are noted. Rechallenge frequently results in tolerance. Efficacy and safety compare favorably with previously studied regimens. This simple prophylactic regimen may provide a convenient alternative for patients failing or intolerant to approved regimens.

Long-term results after posterior fixation of thoraco-lumbar burst fractures

Current concepts of treating thoraco-lumbar burst-compression injuries are based on posterior transpedicular fixation techniques which are angular stable. However, the long-term results of this approach are controversial due to inconsistent reports and due to a paucity of data on late outcome. In the present study we analyzed 50 patients retrospectively who had an unstable burst-compression injury at T 11-L 2 (type A 3 according to Magerl) without a neurological deficit. All fractures were stabilized by an internal fixator either with or without transpedicular spongiosa grafting. Patients were treated between 1991 and 1997. Follow-up times ranged from 36 to 103 months. Follow-up examinations collected occupational, subjective and clinical data (activity score, Hannover spine score) and included radiographic measurements. The latter were used to calculate the sagittal index (SI) which measures deformities of the fractured vertebral body, and the sagittal plane kyphosis (SPK) which additionally describes an eventual destruction of the affected intervertebral disc. Compared with the preinjury status, the percentage of subjects who were able to do physical labor was reduced by half at follow-up, and four times as many patients had a permanent disability. Correspondingly, activity scores and Hannover spine scores declined significantly. After the initial surgical correction SI remained stable until follow-up, whereas SPK decreased again towards pre-operative values indicating a progressive deformity of the intervertebral disc space. Clinical results did not correlate with radiographic results, and neither the time until follow-up nor the type of fracture n or the use of transpedicular bone grafting affected clinical or radiographic results significantly.

The first bismuth phosphonate cluster. X-ray single crystal structure of [(ButPO3)10(ButPO3H)2Bi14O(10).3C6H(6).4H2O]

The reaction of triphenylbismuth and tert-butylphosphonic acid gives the bismuth phosphonate phase (ButPO3H)3Bi and the first bismuth phosphonate cluster [(ButPO3)10(ButPO3H)2Bi14O(10).3C6H(6).4H2O].

Stronger reactivity of the human primary motor cortex during observation of live rather than video motor acts

The monkey premotor cortex contains neurons that are activated both when the monkey performs motor acts and when he observes actions made by others. A similar mirror neuron system, involving several brain areas, has been found in humans. We recorded neuromagnetic oscillatory activity from the primary motor cortex of 10 healthy subjects when they observed live and videotaped finger movements. The left and right median nerves were stimulated alternatingly and the poststimulus level of the approximately 20 Hz rhythm was quantified. Compared with the rest condition, the approximately 20 Hz rhythm was dampened 15-19% more when the subjects observed live rather than videotaped hand movements, indicating stronger activation of the primary motor cortex. These results suggest that the human mirror neuron system differentiates natural and artificially presented movements.

Gene polymorphisms of immunoregulatory cytokines and angiotensin-converting enzyme in Wegener's granulomatosis

Wegener's granulomatosis is a granulomatous and vasculitic disease of unknown origin. Gene polymorphisms are known to affect phenotypes of numerous diseases. Polymorphisms within the angiotensin-converting enzyme (ACE), transforming growth factor-beta1 (TGF-beta1), and interleukin-10 (IL-10) genes are suspected to modify the course of granulomatous disorders. We examined whether the genotype frequencies of the named polymorphisms differ in Wegener's granulomatosis from those in healthy controls. Thirty-nine patients with Wegener's granulomatosis were genotyped for the deletion/insertion polymorphism in intron 16 of the ACE gene, a biallelic polymorphism in codon 25 of the TGF-beta1 gene and a biallelic polymorphism at position -1082 of the IL-10 gene and compared with healthy blood donors. For the ACE polymorphism no significant differences were detected neither in the allele frequencies nor in the genotype frequencies. For TGF-beta1 a trend to genotype CG was found. The most interesting result was the observed, significant shift to genotype AA of the IL-10 polymorphism in Wegener's granulomatosis. IL-10 and TGF-beta1, immunoregulatory cytokines capable of down-regulating T helper cell type 1 response, showed a significant shift or a trend, respectively towards genotypes associated with reduced cytokine release, leading to the hypothesis that different immunoregulatory cytokine patterns dependent on gene polymorphisms might be involved in the pathogenesis of Wegener's granulomatosis.

Assessment of the peripheral microcirculation using computer-assisted venous congestion plethysmography in post-traumatic complex regional pain syndrome type I

In complex regional pain syndrome type I (CRPS-I), edema of the affected limb is a common finding. Therefore, the changes in macro- and microcirculatory parameters were investigated to elucidate the underlying pathophysiology. Twenty-four patients with post-traumatic CRPS-I and 25 gender- and age-matched healthy subjects were examined by means of an advanced computer-assisted venous congestion strain-gauge plethysmograph. The recording of the volume response of the forearm to a stepwise inflation of an occlusion cuff placed at the upper arm enabled the calculation of the arterial blood flow into the arm (Q(a)), the vascular compliance (C), the peripheral venous pressure (P(v)), the isovolumetric venous pressure (P(vi); = hydrostatic pressure needed to achieve net fluid filtration) and the capillary filtration capacity (CFC)--an index of microvascular permeability. The study revealed no difference in any of the parameters between the right and left hand of healthy subjects. In CRPS-I patients, however Q(a), P(v), P(vi) and CFC were significantly (p < 0.01/0.001) elevated in the affected arm (Q(a) 11.2 +/- 7.0 ml x min(-1) x 100 ml(-1), P(v) 20.2 +/- 8.1 mm Hg, P(vi) 24.7 +/- 4.2 mm Hg, CFC 0.0058 +/- 0.0015 ml x min(-1) x 100 ml(-1) x mm Hg(-1)) compared to the unaffected arm (Q(a) 4.2 +/- 2.4 ml x min(-1) x 100 ml(-1), P(v) 10.0 +/- 5.1 mm Hg, P(vi) 13.2 +/- 3.7 mm Hg, CFC 0.0038 +/- 0.0005 ml x min(-1) x 100 ml(-1) x mm Hg(-1)) and the values obtained in healthy controls (Q(a) 5.1 +/- 1.3 ml x min(-1) x 100 ml(-1), P(v) 10.4 +/- 4.3 mm Hg, P(vi) 15.7 +/- 3.3 mm Hg, CFC 0.0048 +/- 0.0012 ml x min(-1) x 100 ml(-1) x mm Hg(-1)). Whereas the values in the unaffected arm of CRPS-I patients revealed no difference in Q(a), P(v) and P(vi) but a lower CFC (p < 0.01) compared to those from healthy controls. These results suggest profound changes in both macro- and microvascular perfusion in the affected arm of CRPS-I patients. The high CFC contributes to the edema formation, and combined with the elevated P(vi), they are in agreement with the hypothesis of an inflammatory origin of CRPS.

Results from a genome-wide search for predisposing genes in sarcoidosis

Sarcoidosis is a systemic disease of granulomatous inflammation and unknown etiology. An inherited predisposition is involved, and many candidate susceptibility genes have been tested in association studies. We have applied the more general strategy of genome-wide microsatellite linkage analysis to identify chromosomal regions that contribute to the risk of sarcoidosis. On the basis of 225 microsatellite markers tested in 63 families with affected siblings (138 patients) and multipoint nonparametric linkage (NPL) analysis, we found the most prominent peak (six adjacent markers including D6S1666; NPL score = 2.99; p = 0.001) at the major histocompatibility complex (MHC). Six minor peaks (p < 0.05) were found on chromosomes 1 (D1S1665 ), 3 (D3S1766 ), 7 (D7S821 and D7S3070), 9 (D9S934), and the X chromosome (DXS6789). A subset of nine families with more than two affected siblings (30 patients) contributed little to the peak at the MHC (D6S1666; NPL score = 0.79; p = 0.21). Our results point to locus heterogeneity of susceptibility to sarcoidosis, with a major effect of the MHC.

[Experiences with calcitonin treatment of patients with type I complex regional pain syndrome (CRPS I--Sudeck disease)]

PURPOSE/METHODS/PATIENTS: Calcitonin is a common treatment in patients suffering from Complex Regional Pain Syndrome Type 1 (CRPS I), although its effects are being controversially discussed. In a prospective study of 24 patients with CRPS I of the upper limb, we examined the tolerance of daily doses of 0.5 mg human calcitonin administered subcutaneously over 8 weeks. To assess the benefit of this therapy, the patients were clinically examined every second week. The results were compared to a consecutive group of 25 CRPS 1 patients who received only analgetics and physiotherapy.

RESULTS

With regard to all examined parameters (spontaneous pain, grip strength, edema, hand function, systematic temperature difference), the patients treated with calcitonin showed an improvement during the observation time. However, a statistically significant difference to the control group was calculated only for the reduction of the edema (P < 0.01). 83% (20/24 patients) of the calcitonin-treated patients suffered from severe, mostly gastroenterological side-effects. Hence therapy had to be discontinued in 3 cases (13%).

CONCLUSION

The therapy with calcitonin has the burden of numerous unpleasant side-effects and causes only a slight therapeutic improvement. Thus, calcitonin must only be prescribed with reservations for patients suffering from CRPS I.

Wavelet Transform in the analysis of the frequency composition of evoked potentials

This technical paper deals with the application of the Wavelet Transform to the study of evoked potentials. In particular, Wavelet Transform gives an optimal time-dependent frequency decomposition of the evoked responses, something difficult to be achieved with previous methods such as the Fourier Transform. We describe in detail the protocol for implementing the decomposition based on the Wavelet Transform and apply it to two different types of evoked potentials. In the first case we study alpha responses in pattern visual evoked potentials and in the second case, we study gamma responses to bimodal (auditory and visual) stimulation. Although in this study we focus on methodological issues, we briefly discuss physiological implications of the present time-frequency analysis. Furthermore, we show examples of the better performance of the wavelet decomposition in comparison with Fourier-based methods.

[When fracture pain does not subside. Recognizing complications]

Over the long term, the evolution of pain caused by fractures is determined by the quality of immobilization, the extent of edema, and by surgical, analgesic and physiotherapeutic treatment. Development of chronicity is initiated by secondary deterioration, persistence of pain in the absence of improvement, changes in the nature of the pain, its spontaneous occurrence, and the appearance of concomitant symptoms. Differential diagnostic considerations must include surgical complications, but also damage to nerves, or the complex regional pain syndrome (CRPS). A particular differential diagnostic problem is the differentiation between CRPS and other complications. Treatment must be matched to the diagnosis: conservative attempts at treatment may have to be followed up with surgical revision. Drug treatment of pain is oriented to the stepped WHO schema. Physiotherapy, physical treatment and ergotherapy play a major role in the treatment of CRPS.

[Important acute measures after fractures. Rapid and adequate treatment of pain]

Pain caused by bone fractures needs to be treated promptly and adequately to avoid negative secondary effects. Pain therapy and the healing of soft tissue are goals that are equally as important as healing of the fracture. The following factors have analgesic potential: reduction, immobilization, cooling measures, limb elevation and fasciotomy. Symptomatic treatment of pain is orientated to the WHO stepped approach, which attaches particular importance to the regular administration of analgesics, as dictated by clinical effectiveness.

[Corrected normal values for serum ACE by genotyping the deletion-/insertion-polymorphism of the ACE gene]

BACKGROUND

In sarcoidosis, serum ACE is widely recognised as a marker of disease activity. Since 1990 a deletion-/insertion polymorphism of the ACE gene is known and a correlation between the genotypes of this polymorphism and serum ACE levels has been observed. Homzygotes for the deletion allele (DD) have the highest levels and homozygotes for the insertion allele (II) the lowest. Heterozygote (DI) persons show intermediate levels. The extent of this influence varies in populations of different ethnic origin. In a large cohort of healthy individuals from North of Germany, genotype-based normal ranges for serum ACE were determined for the population of Germany for the first time.

METHODS

In 262 healthy individuals the genotype of the ACE D/I gene polymorphism was determined from genomic DNA by a PCR method. In addition, in serum samples of all these individuals ACE level was measured with a kinetic test.

RESULTS

The genotype DD was found in 29.4 % of the individuals examined, the genotype DI in 49.6 % and the genotype II in 21.0 %, respectively. These results are similar to those found in previous investigations in other populations of Central European origin. The mean serum ACE levels (95 % confidence interval) in individuals with the genotypes DD, DI and II are 59.8 U/l (31.8 - 87.8), 47.7 U/l (18.6 - 76.8) and 32.2 U/l (13.7 - 50.7), respectively. Without taking the genotype into account, the average value is 48.0 U/l (15.0 - 80.9). Differences between all genotype groups are highly significant (p < 0.0001).

CONCLUSIONS

In sarcoidosis patients, the determination of this ACE gene polymorphism once in the course of the disease allows a better interpretation of the serum ACE levels measured.

Local atomic environment of Si suboxides at the SiO2/Si(111) interface determined by angle-scanned photoelectron diffraction

Local environments of Si suboxides at the interface between a thermally grown SiO2 film and Si(111) were studied by angle-scanned photoelectron diffraction. Si 2p core-level spectra containing chemically shifted components were recorded. The components were deconvoluted by least squares fitting and assigned to different Si oxidation states. The obtained diffraction patterns of the various suboxides exhibit different features. Comparison of these patterns with multiple scattering calculations including a multipole R-factor analysis shows that a simple chemical abrupt interface model describes well the environment of the suboxides and indicates ordered SiO2 close to the interface.

Wavelet entropy in event-related potentials: a new method shows ordering of EEG oscillations

In this work we show the application of a measure of entropy defined from the wavelet transform, namely the wavelet entropy (WS), to the study of event-related potentials (ERPs). WS was computed for ERPs recorded from nine healthy subjects with three different types of stimuli, among them target stimuli in a cognitive task. A significant decrease of entropy was correlated with the responses to target stimuli (P300), thus showing that these responses correspond to a more "ordered" state than the spontaneous EEG. Furthermore, we propose the WS as a quantitative measure for such transitions between EEG ("disordered state") and ERP ("ordered state").

Bisensory stimulation increases gamma-responses over multiple cortical regions

In the framework of the discussion about gamma (approx. 40 Hz) oscillations as information carriers in the brain, we investigated the relationship between gamma responses in the EEG and intersensory association. Auditory evoked potentials (AEPs) and visual evoked potentials (VEPs) were compared with bisensory evoked potentials (BEPs; simultaneous auditory and visual stimulation) in 15 subjects. Gamma responses in AEPs, VEPs and BEPs were assessed by means of wavelet decomposition. Overall maximum gamma-components post-stimulus were highest in BEPs (P < 0.01). Bisensory evoked gamma-responses also showed significant central, parietal and occipital amplitude-increases (P < 0.001, P < 0.01, P < 0.05, respectively; prestimulus interval as baseline). These were of greater magnitude when compared with the unisensory responses. As a correlate of the marked gamma responses to bimodal stimulation we suggest a process of 'intersensory association', i.e. one of the steps between sensory transmission and perception. Our data may be interpreted as a further example of function-related gamma responses in the EEG.

Identification of catalytically important residues in the active site of Escherichia coli transaldolase

The roles of invariant residues at the active site of transaldolase B from Escherichia coli have been probed by site-directed mutagenesis. The mutant enzymes D17A, N35A, E96A, T156A, and S176A were purified from a talB-deficient host and analyzed with respect to their 3D structure and kinetic behavior. X-ray analysis showed that side chain replacement did not induce unanticipated structural changes in the mutant enzymes. Three mutations, N35A, E96A, and T156A resulted mainly in an effect on apparent kcat, with little changes in apparent Km values for the substrates. Residues N35 and T156 are involved in the positioning of a catalytic water molecule at the active site and the side chain of E96 participates in concert with this water molecule in proton transfer during catalysis. Substitution of Ser176 by alanine resulted in a mutant enzyme with 2.5% residual activity. The apparent Km value for the donor substrate, fructose 6-phosphate, was increased nearly fivefold while the apparent Km value for the acceptor substrate, erythrose 4-phosphate remained unchanged, consistent with a function for S176 in the binding of the C1 hydroxyl group of the donor substrate. The mutant D17A showed a 300-fold decrease in kcat, and a fivefold increase in the apparent Km value for the acceptor substrate erythrose 4-phosphate, suggesting a role of this residue in carbon-carbon bond cleavage and stabilization of the carbanion/enamine intermediate.

Clinical and physiologic evaluation of stellate ganglion blockade for complex regional pain syndrome type I

OBJECTIVE

The efficacy of peripheral sympathetic interruption after stellate ganglion blockade was assessed by a sympathetic function test. Results were compared with clinical signs such as temperature changes, pain reduction, and the development of Horner syndrome to evaluate the correlation with clinical investigations.

DESIGN

Stellate ganglion blockade with local anesthetics was carried out via an anterior paratracheal approach in 33 patients suffering from complex regional pain syndrome type I. Patients were examined before and after the procedure. For assessment of sympathetic nervous function, the vasoconstrictor response to sympathetic stimuli was assessed using laser Doppler flowmetry. Clinical parameters like surface temperature changes (thermography), pain relief (visual analogue scale), and Horner syndrome were monitored.

RESULTS

Twenty-three (70%) of 33 patients developed an increase in temperature difference between the treated hand and the contralateral hand of more than 1.5 degreesC after the procedure, which is a clinical sign of sympathicolysis. In 48% (n = 11) of these patients, the sympathetic function test showed an undisturbed sympathetic nervous function. In 10 patients, no significant increase in temperature difference was observed. Although these patients presented with a normal sympathetic vasoconstrictor response, 4 felt pain relief of more than 50%, suggesting a placebo effect. Only 7 patients with pain relief revealed both clinical sympathicolysis and extinguished sympathetic nervous function and qualified for sympathetically maintained pain.

CONCLUSIONS

Clinical investigation is not reliable in the assessment of stellate ganglion blockade. Proof of sympathetically maintained pain based on pain relief after stellate ganglion blockade is not conclusive.

A rare case of osteoporotic spine fracture associated with epidural lipomatosis causing paraplegia following long-term cortisone therapy

Cushing's syndrome is frequently associated with osteoporosis. Therefore, the incidence of osteoporotic spine fractures is significant. They are a rare cause of paraplegic syndromes. Additionally, epidural lipomatosis may occur in those patients. The combination of both fracture and lipomatosis may cause neurological deficit. A case of a young patient suffering from drug-induced Cushing's syndrome is reported. She developed progressive paraplegia. Radiographs demonstrated kyphosis of the thoracic spine from T7 to T9 and pathologic fractures. Urgent operation was planned to stabilize and decompress the spinal cord in the area of the kyphosis. Fortunately, magnetic resonance imaging (MRI) was conducted first. It confirmed pathologic fractures of T7-9 but also showed massive epidural fat extending from the level of T1 to T9. As suspected, laminectomy alone in the area of the fracture proved to be insufficient, as shown by myelography during operation. For treatment of paraplegia in this case of symptomatic epidural lipomatosis, an expanded laminectomy was necessary to remove all the epidural fat. Having undergone this procedure, the patient is now recovering from paraplegia. Our experience suggests that care should be taken before operative treatment of patients with pathological fractures in combination with Cushing's syndrome. In addition to vertebral fractures, epidural lipomatosis has to be taken into consideration. Those patients with neurological deficits have to be treated by an extensive laminectomy.

Wavelet entropy: a new tool for analysis of short duration brain electrical signals

Since traditional electrical brain signal analysis is mostly qualitative, the development of new quantitative methods is crucial for restricting the subjectivity in the study of brain signals. These methods are particularly fruitful when they are strongly correlated with intuitive physical concepts that allow a better understanding of brain dynamics. Here, new method based on orthogonal discrete wavelet transform (ODWT) is applied. It takes as a basic element the ODWT of the EEG signal, and defines the relative wavelet energy, the wavelet entropy (WE) and the relative wavelet entropy (RWE). The relative wavelet energy provides information about the relative energy associated with different frequency bands present in the EEG and their corresponding degree of importance. The WE carries information about the degree of order/disorder associated with a multi-frequency signal response, and the RWE measures the degree of similarity between different segments of the signal. In addition, the time evolution of the WE is calculated to give information about the dynamics in the EEG records. Within this framework, the major objective of the present work was to characterize in a quantitative way functional dynamics of order/disorder microstates in short duration EEG signals. For that aim, spontaneous EEG signals under different physiological conditions were analyzed. Further, specific quantifiers were derived to characterize how stimulus affects electrical events in terms of frequency synchronization (tuning) in the event related potentials.

[cyclo-CH2[Sn(CI2)CH2Si(Me2)]2O]: synthesis and complexation behaviour of a novel, cyclic, bidentate Lewis acid and its conversion into a tin-containing fluorosilane with intermolecular Si-F...Sn bridges

Acid-catalysed hydrolysis of [CH2[(Sn(Ph2)CH2Si(OiPr)Me2]2] followed by subsequent reaction with mercuric chloride in acetone afforded the novel silicon- and tin-containing eight-membered ring [cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2O] in good yield, the crystal structure of which is reported. 119Sn NMR and X-ray studies indicate that [cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2O] acts as a bidentate Lewis acid towards chloride ions exclusively forming the 1:1 complex [(Ph3P)2N]+[cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2OCl]- upon addition of [(Ph3P)2N]+Cl- . Also reported are the synthesis and structure of [K(dibenzo[18]crown-6)]+[cyclo-CH2(Sn(Cl2)CH2Si(Me2)]2OF]-, the first completely characterised organostannate with a C2SnCl2F- substituent pattern. No ring-opening polymerisation could be achieved for [cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2O] or for its perphenylated derivative [cyclo-CH2[Sn(Ph2)CH2Si(Me2)]2O]. The reaction of [cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2O] with Me3O+BF4- gave the tin-containing fluorosilane [CH2[Sn(Cl2)CH2Si(F)Me2]2], in which the Si-F bond is activated by intermolecular Si-F...Sn interactions in the solid state.

The selectively distributed theta system: functions

The present paper provides three interwoven or interrelated approaches: (1) the dependence of frontal theta response from the spontaneous activity will be pointed out. This helps in understanding that 'frontal theta' is a major oscillation of the human frontal cortex and has a response-controlling function; (2) it will be shown that complex stimulations such as bimodal stimulation enhances the theta response; and by bringing together the results outlined in a number of previous reviews the so-called 'selectively distributed theta system of the brain' is described.

Event-related oscillations are 'real brain responses'--wavelet analysis and new strategies

The EEG consists of the activity of an ensemble of generators producing rhythmic activity in several frequency ranges. These oscillators are active usually in a random way. However, by application of sensory stimulation these generators are coupled and act together in a coherent way. This synchronization and enhancement of EEG activity gives rise to 'evoked' or 'event-related oscillations'. The compound evoked potential manifests as superimposition of evoked rhythms in the EEG frequencies ranging from delta to gamma ('natural frequencies of the brain'). The superimposition principle is described with efficient strategies and by utilization of an efficient algorithm. The wavelet analysis confirms the results of the combined analysis procedure obtained by using the amplitude frequency characteristics (AFCs) and digital filtering. The AFC and adapted digital filtering methods are based on the first approach to analyze average evoked potentials. In contrast, the wavelet analysis is based on signal retrieval and selection among a large number of sweeps recorded in a given physiological or psychological experiment. By combining all these results and concepts, it can be stated that the wavelet analysis underlines and extends the expression that alpha-, theta-, delta-, and gamma-responses described in this report are the most important brain responses related to psychophysiological functions. The wavelet analysis confirms once more the expression 'real signals' which we attribute to EEG frequency responses of the brain. It will be demonstrated that the delta, theta, and alpha responses (i.e. the rhythms 'predicted' by digital filtering) are real brain oscillations. The frequency components of the event-related potential vary independently of each other with respect to: (a) their relation to the event; (b) their topographic distribution; and (c) with the mode of the physiological measurements.

Delta responses and cognitive processing: single-trial evaluations of human visual P300

Visual P300 responses were recorded by using checkerboard-type stimuli. (1) High amplitude P300-delta responses were visible even in single trial ERPs. (2) An algorithm for efficient selection of P300 single trials (based on evaluation of delta responses) is introduced. (3) The 'universal' character of the P300-delta response demonstrated in this report may open new avenues for the understanding of functional ERP components.

Angiotensin-converting enzyme (ACE) gene polymorphisms and familial occurrence of sarcoidosis

OBJECTIVES

The aim of this study was to test for genetic linkage and association between polymorphisms of the angiotensin-converting enzyme (ACE) gene and familial occurrence of sarcoidosis.

DESIGN, SETTING AND SUBJECTS

German families with more than one member suffering from sarcoidosis were contacted and a DNA bank was established. Sixty-two families (140 patients, 77 females and 63 males, and 104 unaffected relatives) were genotyped for the ACE gene insertion/deletion (I/D) polymorphism and for two flanking variable sites (ACE A-5466C and ACE 4656(CT)2/3). As controls, 100 DNAs from unrelated resident Caucasians (50 females, 50 males) were analysed. ACE allele and genotype frequencies were determined, and parametric linkage and affected sib pair analyses and transmission disequilibrium tests were performed.

RESULTS

There was a striking over-representation of the ACE I/D genotype DD in patients with sarcoidosis and their families as compared with controls of the study and well founded genotype frequencies from the literature. The same was evident for the accompanying genotypes CC and 2,2 of the flanking polymorphisms. Linkage between the segregation of ACE alleles and the disorder within families was clearly excluded for simple models of inheritance. However, there was a suggestive but not significant (P = 0.06) excess of allele sharing amongst affected siblings. There was no transmission disequilibrium for any ACE allele or haplotype.

CONCLUSIONS

ACE is involved in the pathogenesis of sarcoidosis, but the ACE polymorphisms are not an inherited main cause of the disease. They are more likely to modify the development of the disorder, and the ACE I/D genotype DD might be a promoter to clinical manifestation.

Topological distribution of oddball 'P300' responses

This report describes the frequency response of the oddball paradigm upon auditory stimuli. Other reports related to wavelet analysis of the same ERPs (Demiralp et al., 1999) and the application of visual signals (Schürmann et al., this volume) indicate that the P300 response has a dominant delta response oscillation, independent of the modality of the stimulation. Moreover, the adaptive digital filtering and the wavelet analysis lead to very similar results, confirming that delta responses are real brain responses as already mentioned, by Başar et al. (this volume). The theta response has a second late response window in comparison to auditory evoked potentials. Moreover, the functional significance of the selectively distributed theta and delta systems of the brain will be clearly demonstrated. Signal detection, short-term memory, and decision-making processes are discussed.

Selectively distributed gamma band system of the brain

Experiments from the cat brain demonstrate that gamma responses can be recorded in cortex, hippocampus, cerebellum, formatio reticularis and thalamus, independent of the mode of sensory stimulation. These results support the hypothesis of a selectively distributed gamma system of the brain.

Increased frontal phase-locking of event-related alpha oscillations during task processing

Recent findings substantiate the view that electroencephalographic (EEG) alpha rhythm (7-13 Hz) is functionally involved in cognitive stimulus processing. Our previous results have shown that enhanced alpha responses to auditory task stimuli can be well synchronized with stimulus until 800-1000 ms. The present study analyzed the effect of perceptual uncertainty and difficulty in decision making on event-related alpha oscillations in single auditory event-related brain potentials (ERPs). EEG was recorded from Fz, Cz and Pz electrodes in 10 subjects participating in two experimental sessions, in which auditory stimuli with equal physical parameters were presented under passive and task instructions. Separate measurements of single alpha response amplitude and phase-locking were performed and statistically analyzed for consecutive time windows in the post-stimulus epoch. Major results show that, during the cognitive task, the phase-locking of alpha oscillations at the frontal site is significantly increased in the time window of 500-1000 ms after stimulation. Thus, the involvement of enhanced and synchronized frontal alpha activity in higher brain processes is strongly emphasized.

Gamma, alpha, delta, and theta oscillations govern cognitive processes

The increased interest in gamma oscillations, now widely regarded as functionally relevant signals of the brain, underlines the importance of the concept of event-related oscillations for bridging the gap between single neurons and neural assemblies. Taking this concept further, we review experiments showing that oscillatory phenomena such as alpha, theta, and delta responses to events are, just as the gamma band, strongly interwoven with sensory and cognitive functions. This review argues that selectively distributed delta, theta, alpha and gamma oscillatory systems act as resonant communication networks through large populations of neurons. Thus, oscillatory processes might play a major role in functional communication in the brain in relation to memory and integrative functions.

Functional aspects of alpha oscillations in the EEG

Experimental evidence suggests a functional significance of EEG alpha rhythms. Event-related, evoked, and induced alpha rhythms may have functional correlates in primary sensory processing and preparatory processes. These results are in accordance with the view that spontaneous and induced EEG alpha rhythms have quasi-deterministic properties.

EEG responses to combined somatosensory and transcranial magnetic stimulation

OBJECTIVES

To investigate a possible interaction between sensory processing and transcranial magnetic stimulation (TMS), an experimental set-up permitting multichannel EEG measurements was used.

METHODS

A somatosensory stimulus was delivered to the right wrist, while single-pulse TMS was applied to the contralateral somatosensory cortex, either concurrent with the somatosensory stimulus or 10 ms after it. A control condition served to mimic the sound of TMS without actually resulting in brain stimulation.

RESULTS

An enhancement of the P25 component of the somatosensory-evoked potential (SEP) was consistently observed for TMS concurrent with somatosensory stimulus. The effect was topographically specific to the EEG recording sites below the TMS coil, i.e. above the somatosensory cortex contralateral to the stimulated peripheral nerve.

CONCLUSIONS

The results can be interpreted (1) as an indication of local interaction between the somatosensory-evoked cortical activity and TMS-evoked activity or (2) as support of a relationship between the background EEG and the evoked potential (EP), this relationship being 'disrupted' by TMS.

Peripheral sympathetic function as a predictor of complex regional pain syndrome type I (CRPS I) in patients with radial fracture

Complex regional pain syndrome type I (CRPS I) is a frequent complication after injuries of the upper limbs. The pathophysiology of this disease remains unclear, although disturbances of the sympathetic nervous system have been detected in several clinical studies, and sympathetic blocks resolve the symptoms in many of the cases. To investigate the meaning of sympathetic dysfunction at the beginning of the disease, 27 patients with distal radial fracture were examined prospectively during the course of the disease with regard to their clinical symptoms and their peripheral sympathetic nervous function. Sympathetic nervous function was examined by testing the vasoconstrictor response to sympathetic stimuli--recorded with laser Doppler fluxmetry--of the fingertips of both hands. Four patients developed CRPS I during the 12-week observation time and two patients presented an incomplete clinical CRPS I picture ('borderline patients'). The complaints of all patients (normal fracture patients, CRPS I patients, borderline patients) were similar during the first week after trauma with focus on pain, motoric disturbances and autonomic symptoms. After 1 or 2 weeks, a larger clinical difference developed between normal fracture patients and CRPS I or 'borderline patients'. In CRPS I patients and 'borderline patients', the sympathetic vasoconstrictor response was diminished or absent from the first posttraumatic day throughout the observation time, whereas the normal fracture patients revealed slightly impaired sympathetic nervous function on the first posttraumatic day and normal results during the rest of the observation time. With regard to the unaffected contralateral hand, CRPS I patients also showed impaired sympathetic nervous function. The results of the present study suggest that the disturbances in the sympathetic nervous system in CRPS I patients are systemic and not limited to the affected limb. Their occurrence before the clinical breakout of the disease may serve as a marker that might be useful for early therapy and lead to further understanding of the pathophysiology of CRPS I.

Clinical and finite element analysis of a modular femoral prosthesis consisting of a head and stem component in the treatment of pertrochanteric fractures

OBJECTIVE

To determine the biomechanical characteristics and potential clinical efficacy of a cementless modular femoral prosthesis consisting of a variable head (50 to 80 millimeters) and stem (length 120 to 280 millimeters, diameter 10 to 20 millimeters) component in patients with pertrochanteric femoral fracture.

DESIGN

Finite element analysis (FEA) of different lengths and diameters of prosthesis components and first clinical prospective study in pertrochanteric femoral fracture.

METHOD

Using a 3D-CAD program, a model of femoral cortical bone with a pertrochanteric fracture was created and combined with a model of the prosthesis. This model was transferred into an FEA program. After applying a torsion-bending load of 2,000 N (25 degrees, 45 degrees) on the prosthesis, stress distribution in the cortical bone was determined for different lengths (160 to 240 millimeters) and diameters (10 and 12 millimeters) of stem.

PATIENTS

Twenty-eight patients with pertrochanteric fractures (very unstable or osteoarthritis) were treated with a modular hip arthroplasty. Complications, fracture healing, and results at first follow-up (average 13 months) were determined.

RESULTS

FEA analysis indicated that reduction in stress was less when a prosthesis with a short stem was used. Shear stress in the interface bone/prosthesis was not affected by stem length. Prostheses with thin stems produced higher sheer stresses than those with thick stems. Results of FEA were used as the basis for clinical application of the device. None of the patients died, and all patients were able to walk, although some needed a cane or walker after surgery. There was no increase in thigh pain compared with reported pretrauma levels. Radiographs showed subsidence of up to 5 millimeters in 20 percent of patients. However, all but one prosthesis was stable at follow-up. Fracture healing was achieved in all patients.

CONCLUSIONS

If proximal fixation of a femoral uncemented stem cannot be achieved, stem diameter should provide maximum cortical contact to reduce sheer stress. Longer stems do not necessarily provide additional stability. By using this prosthesis and selection method, a good outcome at first follow-up was observed.

Metastatic lesions of the humerus treated with the isoelastic diaphysis prosthesis

Between January 1, 1987, and December 31, 1997, an isoelastic polyacetal resin prosthesis was used in 50 patients with metastatic bone disease to reconstruct pathologic or impending fractures of the humeral diaphysis. Fifty-seven operations were performed, including seven revision surgeries. The patients were assessed before and after surgery for limb function and quality of life using a modified Karnofsky scale. The mean survival time was 440 days. Ninety-one percent of the operations resulted in restoration or improvement of quality of life. Limb function was good or excellent in more than 80% of the patients after surgery. Breaking of the implant (n = 3), loosening of the implant (n = 2), periprosthetic fracture (n = 1), hematoma (n = 2), infection (n = 1), and one radial nerve paralysis were the main complications. In the cases of implant failure, the prosthesis broke at the site of a locking screw that was inserted across the prosthetic shaft in the cementless implantation technique. This kind of complication could be avoided by using bone cement for implantation or additional plate osteosynthesis between the prosthesis and humeral shaft. The isoelastic diaphyseal prosthesis offers a promising method of treating patients with metastatic lesions of the humeral shaft.

Electroencephalogram alpha (8-15 Hz) responses to visual stimuli in cat cortex, thalamus, and hippocampus: a distributed alpha network?

To investigate possible functional correlates of alpha (8-15 Hz) oscillations in the electroencephalogram (EEG) intracranial recordings in cats (from thalamus, occipital cortex, and hippocampus) were performed. In response to visual stimuli, event-related alpha oscillations were observed. Such alpha responses were found not only in a specific sensory (visual) pathway but also in the hippocampus, hinting at a possible distributed alpha response system.

Familial sarcoidosis is linked to the major histocompatibility complex region

Sarcoidosis is a systemic granulomatous disorder associated with high CD4+ cell activity, but no pathogen is detectable. Clustering in families occurs, and the existence of a genetic predisposition to sarcoidosis is widely accepted. The major histocompatibility complex (MHC) is believed to contribute to this susceptibility. Many studies testing this hypothesis have produced conflicting results. We have genotyped 122 affected siblings from 55 families for seven DNA polymorphisms that flank and cover the MHC region on chromosome 6, and for HLA-DPB1, a candidate gene for granulomatous disorders. Multipoint nonparametric linkage (NPL) analysis showed linkage (NPL score > 2.5; p < 0.006) for the entire MHC region with a maximum NPL score of 3.2 (p = 0.0008) at marker locus D6S1666 in the Class III gene cluster. There was a significant excess of marker haplotype sharing among affected siblings. However, the frequency of HLA-DPB1 alleles on 104 shared chromosomes did not differ from that of a control group of founders from the family panel. Transmission disequilibrium was found for allele DPB1*0201, but only nine families contributed to this result. We conclude that genes of the MHC are involved in the genetic predisposition to sarcoidosis, but HLA-DPB1 alone does not sufficiently explain this fact.

Endoscopic osteosynthesis after thoracic spine trauma: a report of two cases

Modern concepts of treating thoracic diseases suggest more and more the use of minimally invasive thoracoscopic techniques to reduce morbidity and save costs. For treatment of specific lesions at the thoracic spine, several thoracoscopic procedures have been performed successfully. The present report examines the feasibility of thoracoscopic osteosynthesis in two patients with ventral hyperextension injuries and anterior instability of the thoracic spine. After initial correction of the anatomical deformity, autologous bone was harvested from the anterior iliac crest. Using a ventral, thoracoscopic approach, the main location of the ventral, damaged spinal segment was identified by the covering pleural haematoma. After endoscopic ventral bone grafting, osteosynthesis was performed, using dynamic compression plates, cardan drills and screw drivers. The perioperative course was uneventful, and follow up examinations after 3 years and 9 months, respectively, revealed an unchanged stable spinal segment. Our results show thoracoscopic osteosynthesis to be technically possible, with a potential for yielding satisfying long-term results.

(1R*,11R*)-Bicyclo[9.4.1]hexadecane-12,16-dione

The title compound, C(16)H(26)O(2), (I), prepared by oxidation of (1R*,11R*)-12-hydroxybicyclo[9.4.1]hexadecan-16-one using pyridinium dichromate, has a trans configuration of the two fused rings and represents an interesting precursor for the synthesis of macrocyclic structures.

Oscillatory frontal theta responses are increased upon bisensory stimulation

OBJECTIVES

To investigate the functional correlation of oscillatory EEG components with the interaction of sensory modalities following simultaneous audio-visual stimulation.

METHODS

In an experimental study (15 subjects) we compared auditory evoked potentials (AEPs) and visual evoked potentials (VEPs) to bimodal evoked potentials (BEPs; simultaneous auditory and visual stimulation). BEPs were assumed to be brain responses to complex stimuli as a marker for intermodal associative functioning.

RESULTS

Frequency domain analysis of these EPs showed marked theta-range components in response to bimodal stimulation. These theta components could not be explained by linear addition of the unimodal responses in the time domain. Considering topography the increased theta-response showed a remarkable frontality in proximity to multimodal association cortices. Referring to methodology we try to demonstrate that, even if various behavioral correlates of brain oscillations exist, common patterns can be extracted by means of a systems-theoretical approach.

CONCLUSIONS

Serving as an example of functionally relevant brain oscillations, theta responses could be interpreted as an indicator of associative information processing.

Brain oscillations in perception and memory

Gamma oscillations, now widely regarded as functionally relevant signals of the brain, illustrate that the concept of event-related oscillations bridges the gap between single neurons and neural assemblies. Taking this concept further, we review experiments showing that oscillatory phenomena such as alpha, theta, or delta responses to events are strongly interwoven with sensory and cognitive functions. This review argues that selectively distributed delta, theta, alpha, and gamma oscillatory systems act as resonant communication networks through large populations of neurons. Thus, oscillatory processes might play a major role in relation with memory and integrative functions. A new 'neurons-brain' doctrine is also proposed to extend the neuron doctrine of Sherrington.