Histomorphological studies of the distal internal thoracic artery which support its use for coronary artery bypass grafting.

The use of the internal thoracic artery (ITA) for myocardial revascularization in coronary artery disease increased because of its relative immunity to atherosclerotic obstruction. This study investigated the distal part of the vessel, the region of anastomosis by means of histology to focus the visualization of this region of interest. The histological examination of arterial segments showed minor intimal thickening in 48 out of 100 patients. Twelve patients demonstrated a severe intimal thickening, the residual patients were without any changes. In 52% the elastic type dominated in the distal part. Hybrid and muscular patterns were found in 22 and 26%, respectively. The media could be classified into three different types: muscular, hybrid and elastic type. There was no correlation concerning the different histological type and the incidence of intimal thickening. No evidence whatsoever of atherosclerotic lesion was encountered in any of the investigated vessels. There is no limitation in the use of the distal part of the ITA for coronary artery revascularization.

Event-related brain responses to morphological violations in Catalan.

The ERP (event-related potential) violation paradigm was used to investigate brain responses to morphologically correct and incorrect verb forms of Catalan. Violations of stem formation and inflectional processes were examined in separate experimental conditions. Our most interesting finding is that misapplications of stem formation rules elicit an early left preponderant negativity. This complements our previous ERP results on morphological violations in other languages in which misapplications of inflectional rules were shown to produce such effects. We make use of the linguistic distinction between lexically stored and rule-based word forms and suggest a unified interpretation of the experimental results, arguing that these negativities vary as a function of processes involved in morpho-syntactic structure building.

Brain potentials in the processing of complex sentences: an ERP study of control and raising constructions.

In the present study we made use of Event-Related Potentials (ERPs) to examine raising and subject control constructions in German. Our most salient result is that the ERPs elicited at the empty subject position of a raising construction are clearly different from those elicited at the corresponding position of an otherwise identical subject control construction, the former producing a stronger P600. We argue that this result provides an electrophysiological correlate of the theoretical distinction between NP trace and PRO.

Morphological priming in the German mental lexicon.

We present results from cross-modal priming experiments on German participles and noun plurals. The experiments produced parallel results for both inflectional systems. Regular inflection exhibits full priming whereas irregularly inflected word forms show only partial priming: after hearing regularly inflected words (-t participles and -s plurals), lexical decision times on morphologically related word forms (presented visually) were similar to reaction times for a base-line condition in which prime and target were identical, but significantly shorter than in a control condition where prime and target were unrelated. In contrast, prior presentation of irregular words (-n participles and -er plurals) led to significantly longer response times on morphologically related word forms than the prior presentation of the target itself. Hence, there are clear priming differences between regularly and irregularly inflected German words. We compare the findings on German with experimental results on regular and irregular inflection in English and Italian, and discuss theoretical implications for single versus dual-mechanism models of inflection.

Lexical entries and rules of language: a multidisciplinary study of German inflection.

Following much work in linguistic theory, it is hypothesized that the language faculty has a modular structure and consists of two basic components, a lexicon of (structured) entries and a computational system of combinatorial operations to form larger linguistic expressions from lexical entries. This target article provides evidence for the dual nature of the language faculty by describing recent results of a multidisciplinary investigation of German inflection. We have examined: (1) its linguistic representation, focussing on noun plurals and verb inflection (participles), (2) processes involved in the way adults produce and comprehend inflected words, (3) brain potentials generated during the processing of inflected words, and (4) the way children acquire and use inflection. It will be shown that the evidence from all these sources converges and supports the distinction between lexical entries and combinatorial operations. Our experimental results indicate that adults have access to two distinct processing routes, one accessing (irregularly) inflected entries from the mental lexicon and another involving morphological decomposition of (regularly) inflected words into stem + affix representations. These two processing routes correspond to the dual structure of the linguistic system. Results from event-related potentials confirm this linguistic distinction at the level of brain structures. In children's language, we have also found these two processes to be clearly dissociated; regular and irregular inflection are used under different circumstances, and the constraints under which children apply them are identical to those of the adult linguistic system. Our findings will be explained in terms of a linguistic model that maintains the distinction between the lexicon and the computational system but replaces the traditional view of the lexicon as a simple list of idiosyncrasies with the notion of internally structured lexical representations.

Decomposition of morphologically complex words in English: evidence from event-related brain potentials.

To explain processing differences between regular (e.g., start/started) and irregular (e.g., think/thought) word formation linguistic models posit either a single mechanism handling both morphological clusters or separate mechanisms for regular and irregular words. The purpose of the present study is to investigate how these processing differences map onto brain processes by assessing electrophysiological effects of English past tense forms, using the repetition priming paradigm. Event-related brain potentials (ERPs) were recorded from 59 scalp sites as 19 subjects read stem forms of regular and irregular verbs from a list of 1152 words; the stem forms were either preceded (5-9 intervening items) by their past tense forms (=primed condition) or by past tense forms of unrelated verbs (=unprimed condition). The difference between the ERPs to the primed and unprimed stems was taken as a measure of morphological priming. We found that the ERPs to regular verbs were clearly different from those to irregular verbs: the former were associated with an N400 reduction in the primed condition; primed irregular verb stems, however, showed no such effect. Control conditions demonstrated that the N400 modulation for regular verbs cannot be attributed to formal (i.e., phonological or orthographical) priming. These ERP effects indicate that regular verbs serve as more powerful primes for their corresponding stem forms than irregular past tense forms, suggesting that regular (but not irregular) past tense forms may be decomposed into stem plus affix.

Syntax and morphology in Williams syndrome.

Williams syndrome (WS) is a neuro-developmental disorder which is characterized by an unusual fractionation of language abilities and other cognitive functions. We have investigated four cases of English-speaking subjects with WS, and we show that despite their low IQs the WS children's performance on syntactic tasks and on regular inflection is not impaired. Irregular inflection, however, is affected causing many errors. We also report results from studies investigating the same linguistic phenomena in children with specific language impairment. These children exhibit a different pattern of impairment, with relatively poor performance on syntactic tasks and regular inflection. We suggest a linguistic characterization of the morphosyntax in WS according to which WS subjects are impaired in accessing (particular kinds of) information from lexical entries, with their computational system for language appearing to be intact. We interpret the selective impairments found in WS and SLI as supporting the theoretical distinction between a computational system and an associative memory system for language.

[Factors influencing the anchoring stability of spinal bone screws--an experimental study]. / Einflussfaktoren auf die Verankerungsstabilität von Wirbelsäulenknochenschrauben--Eine experimentelle Studie.

INTRODUCTION AND AIM OF THE STUDY: The primary assumption for successful internal fixation of the spine is a stable screws fixation. Aim of this experimental examination was to point out the influences on axial pull-out strength of screws and to suggest improvements for its increase. METHODS: Eight specifically manufactured screw-prototypes were tested in standardized pull-out tests in comparison by pairs. An isotropic, synthetic hard-foam was used as test material. It resembled to the spongiose bone and reduced the deviation of the results. To show the transferability of the results on bone there were made pull-out tests out off calf vertebra. RESULTS: A significant increase of axial pull-out strength can be achieved by a wide external diameter, a big insertion depth, a flat angel of tooth profile and a small thread pitch. This examination could not prove a significant advantageous influence on axial pull-out strength by fast pull-out, asymmetrical "Butress-thread" or proportion of core- and external diameter difference. CONCLUSIONS: Referring to the aim of this examination a wide outside-diameter can be recommended. Likewise the depth of insertion should be as deep as the anatomic conditions permit. The influence of these two factors are considerable. In contrast to other author's statements the maximum axial stability increases significantly by a small thread pitch and a flat angel of tooth profile.

Cell survival following bone-anterior cruciate ligament-bone allograft transplantation: DNA fingerprints, segregation, and collagen morphological analysis of multiple markers in the canine model.

Bone-anterior cruciate ligament-bone allograft transplantation has become recognized as a potential solution to reconstruction of the anterior cruciate ligament (ACL). The purpose of this study was to determine the time-dependent fibrocyte donor cell survival rate after cryopreserved bone-ACL-bone allograft transplantation. Additionally, bony incorporation of the pediculated bone plugs was examined. The ability to successfully transplant allogenous ACL fibrocytes and have them survive has not previously been documented. In this study, DNA fingerprints identified and documented the survival rate of the cellular DNA in transplanted ACL allografts for ACL re-construction in the knee joints of 10 skeletally mature dogs. At 4, 8, 26 and 52 weeks after ACL allograft transplantation, DNA probes, H & E, Giemsa, Goldner, PAS and polarized light staining was done to demonstrate the time-dependent changes in the allografts after transplantation. At 4 weeks host fibrocytes began to grow into the graft; however, histologically the cells could not be distinguished as to host or donor origin. After 4 weeks the DNA pattern reflected only the band pattern of the host. This reveals the early cellular infiltration activity of the host into the ACL allograft, also demonstrated in the light microscopy stainings. The survival rate of transplanted allogenous ACL fibrocytes had not been documented before this study. There is no evidence that ACL allograft cells survive in the intra-articular environment of the host's knee. Within 4 weeks ACL allografts became completely repopulated with host cells. The cells that migrate early into the ACL allografts are probably of synovial origin because they are present before revascularization and collagen reorganization occur. We conclude from this study that viable cells in transplanted ACL allografts did not survive longer than 4 weeks after intra-articular transplantation. Advances in molecular biology may offer new approaches to alter or stimulate fibrocyte population and function in the transplanted ACL allograft used for ACL reconstruction. New methods to maintain the viability of donor cells may be necessary to improve the biomechanical and histological properties of autografts or allografts for ACL reconstruction.

Human brain potentials to violations in morphologically complex Italian words.

Event-related brain potentials were recorded while 12 Italian-speaking subjects read correctly and incorrectly inflected verb forms. Participle forms of three types of verbs were investigated: 1st conjugation verbs (parlato 'spoken'), 3rd conjugation verbs (dormito 'slept'), and irregular 2nd conjugation verbs (preso 'taken'). We compared correct and incorrect participle forms; the latter had stem formation errors and/or incorrect participle endings. Event-related potentials (ERP) showed different responses to incorrect regular and incorrect irregular participle forms: incorrect irregulars (*prendato instead of preso) elicited a widespread negativity, whereas incorrect regulars (*parlito, *dormato) produced no effect. This difference replicates previous results on German inflection and supports the linguistic distinction between lexically-based and rule-based inflection.

How the brain processes complex words: an event-related potential study of German verb inflections.

Event-related brain potentials (ERPs) were recorded as German-speaking subjects read verbs in correct and incorrect participle forms. The critical words were presented in three different versions to three different groups of subjects, as part of a simple sentence, in a word list, and embedded in a story; for each version separate ERPs were recorded. Three types of verbs were investigated, regulars, irregulars and nonce verbs. We compared correct regular and irregular participles with incorrect ones; the latter had -(e)n on verbs that actually take -t participles (* getanz-en), or -(e)t on verbs that require -(e)n (* gelad-et). For the nonce verbs, we compared participles with the unexpected -(e)n ending with the expected -t participle forms. The ERP responses were very consistent across the three versions of the experiment: (i) incorrect irregular participles (* gelad-et) elicited a left frontotemporal negativity; (ii) incorrect regulars (* getanz-en) produced no differences to the correct ones; (iii) nonce verbs were associated with an N400 component but did not show a difference between expected and unexpected endings. We will interpret these findings with respect to psycholinguistic models of morphological processing and argue that the brain processes regularly inflected words differently from irregularly inflected ones, the latter by accessing full-form entries stored in memory and the former by a computational process that decomposes complex words into stems and affixes.

Brain potentials indicate differences between regular and irregular German plurals.

Event-related brain potentials were recorded as 18 German-speaking subjects read sentences that contained as critical words German nouns in correct and incorrect plural forms. Two types of plurals were investigated: regular -s plurals (e.g. Karussell-s 'roundabouts') and irregular -(e)n plurals (Muskel-n "muscles'). We compared correct regular and irregular plurals with incorrect ones; the latter had -(e)n on nouns that actually take -s plurals (*Karussell-en), or -s on nouns that require -(e)n (*Muskel-s). ERPs showed different responses to regular and irregular plurals: incorrect irregular plurals (*Muskel-s) elicited a ramp-shaped left frontotemporal negativity, whereas incorrect regulars (*Karussell-en) produced a central phasic negativity with a maximum at 380 ms. This dissociation supports the view that regularly inflected words are processed differently from irregularly inflected ones.

German inflection: the exception that proves the rule.

Language is often explained as the product of generative rules and a memorized lexicon. For example, most English verbs take a regular past tense suffix (ask-asked), which is applied to new verbs (faxed, wugged), suggesting the mental rule "add -ed to a Verb." Irregular verbs (break-broke, go-went) would be listed in memory. Alternatively, a pattern associator memory (such as a connectionist network) might record all past tense forms and generalize to new ones by similarity; irregular and regular patterns would differ only because of their different numbers of verbs. We present evidence that mental rules are indispensible. A rule concatenates a suffix to a symbol for verbs, so it does not require access to memorized verbs or their sound patterns, but applies as the "default," whenever memory access fails. We find 21 such circumstances for regular past tense formation, including novel, unusual-sounding, and rootless and headless derived words; in every case, people inflect them regularly (explaining quirks like flied out, sabre-tooths, walkmans). Contrary to the connectionist account, these effects are not due to regular words constituting a large majority of vocabulary. The German participle -t applies to a much smaller percentage of verbs than its English counterpart, and the German plural -s applies to a small minority of nouns. But the affixes behave in the language like their English counterparts, as defaults. We corroborate this effect in two experiments eliciting ratings of participle and plural forms of novel German words. Thus default suffixation is not due to numerous regular words reinforcing a pattern in associative memory. Because default cases do not occupy a cohesive similarity space, but do correspond to the range of a symbol, they are evidence for a memory-independent, symbol-concatenating mental operation.

Sterilisation of canine anterior cruciate allografts by gamma irradiation in argon. Mechanical and neurohistological properties retained one year after transplantation.

Bone-ACL-bone allograft transplantation is a potential solution to the problem of reconstruction of the anterior cruciate ligament (ACL), but sterilisation by gamma irradiation or ethylene oxide causes degradation of the graft. We have studied the biomechanical and histological properties of deep-frozen canine bone-ACL-bone allografts sterilised by gamma irradiation (2.5 Mrad) under argon gas protection. Particular attention was paid to their collagen structure and neuroanatomy compared with those of non-irradiated allografts. We used 60 skeletally mature foxhounds. In 30 animals one ACL was replaced by an irradiated allograft and in the other 30 a non-irradiated graft was used. In both groups the graft was augmented by a Kennedy Ligament Augmentation Device. Examination of the allografts at 3, 6 and 12 months after implantation included mechanical testing, histology, collagen morphometry, neuroanatomical morphology (silver and gold chloride stain) and studies of the microvasculature (modified Spalteholz technique). At 12 months the irradiated ACL allografts failed at a mean maximum load of 718.3 N, 63.8% of the strength of the normal canine ACL. The non-irradiated allografts failed at 780.1 N, 69.1% of normal. All the allografts showed a well-orientated collagen structure one year after transplantation and there was no difference between the irradiated grafts and the others. The silver staining technique demonstrated Golgi tendon organs and free nerve endings within both groups of allografts. As in the normal ACL these structures were most commonly found near the surface of the graft and at its bony attachments. At 12 months the irradiated allografts showed slight hypervascularity compared with the non-irradiated grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

[Function of the glenohumeral ligaments in active protection of shoulder stability]. / Uber die Funktion der glenohumeralen Ligamente bei der aktiven Sicherung der Schulterstabilität.

UNLABELLED: We harvested the joint capsule, the glenohumeral ligaments, and the coracohumeral ligaments of 8 fresh formalin-preserved shoulder specimen. We made use of the van Gieson technique and a special silver impregnation for staining peripheral axons according to Nowotny. The ligaments were cut into slices with a thickness of 15 microns. In total we performed 10,000 cuts. We discovered axons in all ligaments. These axons had no relation to vessels or vessel walls. Besides these axonal structures we detected type II mechanoreceptors (Pacini receptor). CLINICAL SIGNIFICANCE: The neural structures discovered in the glenohumeral capsule are of clinical importance especially in consideration of the high account of recurrent shoulder dislocation and concomitant Bankart lesions. Receptors located in the glenohumeral ligaments might control the stabilizing shoulder musculature. On this premises, rupture or detachment of these ligaments will lead to a loss of the feedback mechanism.

[Effects of various rehydration periods on the stability and water content of bone transplants following freeze-drying, gamma sterilization and lipid extraction]. / Einfluss verschiedener Rehydratationszeiten auf die Stabilität und den Wassergehalt von Knochentransplantaten nach Gefriertrocknung, Gammasterilisation und Fettextraktion.

UNLABELLED: Several studies demonstrated the necessity of rehydration of lyophilized bone allografts prior to implantation. The purpose of the presented study was to evaluate the influence of different rehydration periods on the stability of human cortical lyophilized and gamma-irradiated allografts, the capability of lyophilized bone for rehydration, as well as the effects of lipid extraction on rehydration. Breaking strength of lyophilized irradiated cortical bone after different rehydration periods (0.5, 1, 2, 4, 8 hours) showed no significant difference. Weight reduction after lyophilization of human femoral heads was between 7.6% and 41%. Further weight reduction occurred after lipid extraction (38.7%). Total weight loss was 56.9%. There was a significant influence of intraosseous lipid content on the rehydration capability. After lyophilization alone the rehydration weight after 8 hours was only 18.1%, whereas after lipid extraction the weight increase was 43% after 0.5 hours, 36.4% after 1 hour, 57.6% after 2 hours, 60% after 4 hours, and 92.7% after 8 hours. CLINICAL RELEVANCE: Based on the presented data rehydration time of 0.5 hours seems to have no disadvantage compared to longer time periods concerning breaking strength. Therefore a longer intraoperative time period seems not to be necessary. This is of advantage for a possible secondary contamination while the allograft is rehydrated. Rehydration after lipid extraction is more effective than rehydration after lyophilization alone. However, the question whether lipid extraction alter bone stability has to be proved in further studies.

Anterior cruciate ligament reconstruction using cryopreserved irradiated bone-ACL-bone-allograft transplants.

Bone-ACL-bone allograft transplantation has been investigated as a potential solution to reconstruction of the anterior cruciate ligament (ACL). To minimize disease transmission (e.g. the acquired immuno deficiency syndrome), bony and collagenous tissues should be sterilized. Recent animal studies indicate that gamma irradiation and ethylene oxide sterilization result in diminished histological and biomechanical properties. The purpose of the present study was biomechanical and histological determination of the fate of deep-frozen gamma-irradiated (2.5 Mrad) canine bone-ACL-bone allografts with argon gas protection. Particular attention was paid to collagenous and neuroanatomical morphology 3, 6 and 12 months after implantation, by comparison to a non-irradiated control group. Sixty skeletally mature foxhounds were operated on in this study, divided up in two groups of 30 dogs each. In group A animals the ACL was replaced by a deep-frozen (-80 degrees C) bone-ACL-bone LAD-augmented allograft subjected to 2.5 Mrad gamma irradiation with argon gas protection. The animals in group B received an LAD-augmented ACL-allograft transplant without gamma irradiation. All knees from both groups were evaluated 3, 6 and 12 months after implantation in regard to biomechanical properties, collagen morphology and routine histology (haematoxylin and eosin stain, polarization microscopy), neuroanatomical morphology (silver and gold chloride stain) and microvasculature (modified Spalteholz technique). The irradiated ACL allografts withstood a maximum load that was 63.8% (718.3 N) of the maximum load of normal ACLs after 12 months. By contrast, the non-irradiated allografts failed at 69.1% (780.1 N) of the maximum load of normal control ACLs.(ABSTRACT TRUNCATED AT 250 WORDS)

[Neurohistological studies in allogeneic cruciate ligament transplants as intra-articular ligament replacement]. / Neurohistologische Untersuchungen bei allogenen Kreuzbandtransplantaten als intraartikulärer Bandersatz.

A multiplicity of surgical operations have been developed in an attempt to achieve satisfactory function after ACL repair. None of these procedures have been able to duplicate the fiber organization, attachment site anatomy, vascularity, or function of the ACL. 18 foxhounds received a deep frozen bone-ACL-bone allograft and a ligament augmentation device (LAD). Neurohistological changes were evaluated 3, 6, and 12 months following implantation. Modified silver impregnation method and gold chloride technique were used to examine the presence of nerve endings and axons. Two morphological distinct mechanoreceptors were identified, and then were categorized as follows: free nerve-endings golgi-like tendon receptors. Fine nerve endings were frequently ramified freely into ligament collagen bundles. Nerves and blood vessels were commonly associated. Like in normal ACL's both neuroreceptors were mostly located near the surface of the allografts and at both bony attachments. This study demonstrated the first histological evidence of viable mechanoreceptors and free nerve-endings in transplanted ACL-allografts, not previously reported in other ACL-substitutes using for ACL-reconstruction. Particularly important for post-op. rehabilitation, this technique may allow to reconstruct the proprioreceptive functions of normal anterior cruciate ligaments.

[Homologous cruciate ligament transplantation as intra-articular ligament replacement]. / Die homologe Kreuzbandtransplantation als intraartikulärer Bandersatz.

A multiplicity of surgical operations have been developed in an attempt to achieve satisfactory function after ACL repair. None of these procedures have been able to duplicate the fiber organization, attachment site anatomy, vascularity, or function of the ACL. 29 foxhounds received a deep frozen bone-ACL-bone allograft and a ligament augmentation device (LAD). Biomechanical, microvascular, and histological changes were evaluated 3, 6 and 12 months following implantation. The maximum load of the allograft/LADs were 34.3% (387.2 N) after 3 months, 49.3% (556.6 N) after 6 months and 61.1% (689.8 N) after a year. The maximal load was 69.1% (780 N). In general, after 6 months the allografts showed a normal collagen orientation. The allografts demonstrated no evidence of infection or immune reaction. No bone ingrowth into the LAD was observed. Polarized light microscopy and PAS-staining showed that the new bone/ligament substance interface had intact fiber orientation at the area of ligament insertion. Microvascular examination using Spalteholtz-technique revealed neovascularization and the importance of infrapatellar fat pad for the nourishment of the ACL-allografts.

Function of the glenohumeral ligaments in active stabilisation of the shoulder joint.

UNLABELLED: The joint capsules and the glenohumeral ligaments of 12 human shoulder specimens were histologically investigated by light microscopy. Serial sections of 15 microns thickness were cut. The tissue was stained following the haematoxylin-eosin and van Giesson techniques. For specific identification of neural elements we made use of a special silver impregnation technique, described by Novotny, for staining axons in peripheral nerves. Axons of different diameters ranging from 0.2 microns to 70 microns were discovered within the ligaments. Close to the humeral site we found small nerves forming neurovascular bundles. Within their connective tissue sheaths, the axons exhibited a serpentine configuration, which may give extra length and may allow stretching of the nerve during motion. Most of the axons discovered were located in the subsynovial layer of the ligaments. In general the diameter of these subsynovial axons did not exceed 10 microns. In addition to these axonal structures, we detected nerve endings which can be classified according to Freeman and Wyke as type II mechanoreceptors (Pacinian corpuscles). These mechanoreceptors had a diameter of approximately 150 microns. They were also positioned directly beneath the synovial membrane and close to the humeral site of insertion of the ligaments. CLINICAL SIGNIFICANCE: The described neural structures in the glenohumeral ligaments are of particular clinical importance in the light of the high incidence of recurrent shoulder dislocation and concomitant Bankart lesions. The mechanoreceptors located in the glenohumeral ligaments may control the stabilising shoulder musculature. On this premise, rupture or detachment of these ligaments will lead to a loss of a feedback mechanism.