Atomic force microscopy imaging of the human trigeminal ganglion.

This paper describes an investigation of gangliocytes via imaging semithin sections of two human trigeminal ganglia with an atomic force microscope (AFM). Whereas semithin sections are usually employed for transmission electron microscopy, we adopted this special type of sample preparation for our AFM studies to extract topographical data from the gangliocyte itself and from the nucleus, the nucleolus, the crystal-arranged lipofuscin granules, and the cell-surrounding mantle cells; simultaneously we characterized the samples with error signal mode. This AFM-related technique revealed no information concerning friction force and elasticity due to the presence of the embedding material (epoxy), but it gave additional topographical contrast. These are the first images of the human trigeminal ganglion by AFM.

An anatomical variant of the extensor carpi radialis brevis muscle.

BACKGROUND: Variations in musculature are of interest not only to the anatomist but also to the surgeon, insofar as they can be a source of error in both diagnosis and treatment. Muscular anomalies in the lower arm and in the hand have frequently been described in the literature; some of the lesions they can be confused with are ganglia and other soft tissue tumors. CASE REPORT: In the course of preparation of a small, fine-jointed right upper extremity, an accessory muscle was discovered in the forearm and hand region; it branched off from the extensor carpi radialis brevis (ECRB) muscle. Its tendon crossed over the extensor retinaculum and attached to the dorsal digital expansion of the index finger. Both muscles were innervated by a branch of the deep branch of the radial nerve. The observations made here supplement our knowledge of variations in the antebrachial and dorsal regions of the arm and hand, which should be quite useful in hand surgery.

Changes of biochemical and biomechanical properties in Dupuytren disease.

BACKGROUND: The major biochemical characteristic of Dupuytren disease is the progressive and irreversible deposition of excess fibrous collagen characterized by an enhanced type III collagen proportion. OBJECTIVE: To investigate the influence of changes of the collagen spectrum on the biophysical properties of the palmar aponeurosis. DESIGN: Variably affected palmar regions from 30 individuals with Dupuytren disease were classified according to histologic test results and clinical stage. Biochemical, biomechanical, and thermal contracture studies were performed. RESULTS: The relative type III collagen content increased with increasing tissue involvement and was found to correlate with calorimetric and biomechanical properties with the exception of the Young modulus. In experiments on the thermal isometric contracture, the collagen denaturation temperature decreased with increasing type III collagen content, ie, increasing involvement. To study the dependence of biophysical properties from the collagen type distribution independent of structural changes, as seen in Dupuytren disease, we investigated rat skins from animals of an age range characterized by dramatic changes in type III collagen content (0-18 months). Biomechanical data also correlated significantly with type III collagen content in rat skin with the exception of the time constant of stress relaxation. CONCLUSION: In light of these results, we suggest that structural changes, such as reduced collagen fibril diameters, associated with alterations in the type III collagen proportion may influence biophysical properties of connective tissues in the involved palmar aponeurosis in addition to alterations of the cross-linking pattern.

Differential scanning calorimetry, biochemical, and biomechanical analysis of human skin from individuals with diabetes mellitus.

The aim of this work was to compare biochemical, two-dimensional biomechanical and calorimetric parameters of diabetic skin vs. control skin. Skin specimens taken from the palms and backs of the hands of aged persons with non-insulin-dependent diabetes mellitus (NIDDM) and of controls (CO) were compared (age range 68-85 years). Only skin specimens from individuals with diabetes mellitus (DM) showed an increased fluorescence specific for the formation of advanced glycation end-products (AGEs) and the presence of tissue AGEs, such as N(e)-(Carboxymethyl)lysine (CML). Differential scanning calorimetry (DSC) revealed an elevation of the heat flow per unit mass during collagen denaturation in diabetic skin samples. However, the temperatures of the heat flow maximum and the onset of the phase transformation were not uniformly altered. Young's moduli were found to be increased in diabetic skin and correlated with AGE-fluorescence and tissue AGEs. The ratio between the Young's moduli, which defines a measure for the degree of anisotropy, was higher for dorsal skins from hands. In dorsal skin specimens from diabetic subjects the degree of anisotropy was more pronounced than in healthy controls. In general, neither of the measured parameters showed any correlation with age. However, E(1) moduli were clearly associated with the duration of diabetes.

Rare variant of the brachial artery: superficial lateral inferior type VII EAB.

This study concerns a variant of the brachial artery with a modified origin and course. The artery was studied in 418 upper limbs removed from cadavers. In one upper limb the left brachial artery bifurcated into: (1) a superficial brachial a. (the variant) crossing superficially to the bicipital aponeurosis in the cubital region and assuming the course, position, and supply area of the radial artery, and (2) the deep brachial a. (another variant). An embryologic interpretation of this anomaly is based on a variant vascular development derived from the eighth intersegmental artery. The variant is termed according to Adachi's classification schedule as arteria brachialis superficialis lateralis inferior Type VII with the addition EAB (epiaponeurosis bicipitalis, i.e., superficial to the bicipital aponeurosis). Accurate information concerning unusual patterns of the arteries in the upper limbs is clinically relevant, especially in the avoidance of accidental intra-arterial injection with reflectory vascular occlusion leading to necrosis.

Alterations of biochemical and two-dimensional biomechanical properties of human skin in diabetes mellitus as compared to effects of in vitro non-enzymatic glycation.

OBJECTIVE: The aim of this study was to evaluate whether multiaxial analysis of diabetes-specific biomechanical changes generated in vitro by non-enzymatic glycation of human skin samples from healthy subjects reflect the changes seen in skin from subjects with diabetes mellitus. DESIGN: Descriptive study. BACKGROUND: Non-enzymatic glycation of skin in vitro causes an increased stiffness comparable to in vivo changes seen in diabetic patients. These changes are probably due to increased cross-linking of collagen molecules. METHODS: Skin specimens from 7 subjects with diabetes mellitus and 7 controls (age range: 74-90) were analyzed for biomechanical changes using a multiaxial tensile testing device. Control skins from healthy individuals in the age range of 50-65 yr were artificially glycated. One part of these samples was coincubated with the glycation inhibitor aminoguanidine. Glycation of tissues was determined by measuring fluorescence of solubilized samples. Multiaxial biomechanical analysis allows the determination of maximum (a(I)) and minimum elastic modulus (a(II)). These parameters describe the amplitude of the elastic stress response, which is exponentially related to strain. RESULTS: Principal stresses, both maximum and minimum, were increased in skins from diabetic subjects as compared to controls. The increases of the principal stresses were comparable to those obtained by in vitro glycation of normal skins. CONCLUSION: These results, which can be detected unequivocally with the multiaxial test mode, show that our in vitro model closely reflects changes in skin samples from individuals with diabetes mellitus. Aminoguanidine partially inhibited these as well as biochemical changes. RELEVANCE: Multiaxial testing of in vitro glycated skin samples can be used as a model for in vivo changes caused by diabetes mellitus. In addition, therapeutical effects of aminoguanidine, an inhibitor of non-enzymatic glycation, can be monitored in this model.

Comparison of palmar aponeuroses from individuals with diabetes mellitus and Dupuytren's contracture.

It is well known that Dupuytren's contracture is often associated with diabetes mellitus. Palmar fascia from individuals with diabetes mellitus and/or Dupuytren's contracture as well as controls were subjected to differential scanning calorimetry, biomechanical and biochemical analysis. The collagen denaturation temperature of the palmar aponeurosis from individuals with diabetes mellitus in the presence (71.0 degrees C) or absence of Dupuytren's contracture (70. 6 degrees C) was increased as compared with controls (68.5 degrees C), while this parameter was significantly reduced (about 3.5 degrees C) in contracture bands of Dupuytren's contracture. Stress relaxation experiments revealed that the viscous fraction was slightly reduced in diabetes mellitus (6.5%) vs. controls (8.3%), whereas in Dupuytren's contracture, irrespective of additional diabetes mellitus, a pronounced increase of this parameter was seen (36.5% vs. 24.5%) in the presence of diabetes mellitus. The time constants were significantly elevated by both disorders, this increase being more pronounced in Dupuytren's contracture. Taken together, these changes can be explained by increased cross-linking in diabetes mellitus, while in Dupuytren's contracture other structural changes, such as increased collagen type III content and loss of fascicular organization, play an additional role besides the finding of reduced cross linking.

Biomechanical stability of abductor pollicis longus muscles with variable numbers of tendinous insertions.

BACKGROUND: In the course of a study of different variants of the tendon of the abductor pollicis longus (APL) muscle, the unusual finding of a tendon with six subdivisions was observed in the first compartment. Using this preparation and others with various numbers of tendons (2, 3, 4, and 6), we intended to establish whether the multitendoned muscles increased the strength of the thumb. METHODS: Fifty-two upper extremities were examined with attention to the tendons of the APL muscle. The strain on each tendon was biomechanically determined using a microcomputer and potentiometer. The stress was measured continuously and plotted against strain. RESULTS: Following treatment with elastase, it is seen that the significance of changes in stability and Young's modulus is inversely proportional to the number of tendons arising from the APL. CONCLUSIONS: Division of the tendon into several parts leads to better mechanical distribution of stress and extension on thumb abduction. In addition, palmar-flexion in the wrist may be supported.

Musculus sartorius bicaudatus.

While dissecting 88 lower limbs, a distal division of the sartorius muscle was detected in one of the specimens. The larger posteromedial portion was found to take a normal course to the so-called superficial pes anserinus. The thinner anterolateral portion attached to the medial meniscus anteromedially. The smaller anterolateral part approached the medial meniscus anteromedially, pushing the synovial membrane into the joint. Its meniscal attachment ensures that the medial meniscus is stabilized in its primary position during bending and external rotation in the knee joint, thus preventing its herniation or injury during sudden extension. The accessory part of the sartorius muscle thus acts as a protector of the medial meniscus.

Supernumerary tendons of the abductor pollicis.

During a study of variants of the tendon of the abductor pollicis longus (APL) muscle, in 1 of 110 upper extremities prepared, we recorded the rare finding of a division of the APL muscle tendon into 7 sections in the first tunnel. Whereas the actual main tendon inserted at the base of the first metacarpal bone, as depicted in the textbooks, the supernumerary tendons attached to the fascia of the opponens pollicis muscle to the radial edge of the abductor pollicis brevis muscle and to the dorsoradial third of the base of the first metacarpal bone. All accessory tendons were arranged in a radial formation around the main tendon within the same synovial sheath, but the main tendon occupied a separate compartment. In 80% of the upper extremities prepared for this study, the classical description of the abductor tendon did not apply. The classical representation of a single abductor tendon applied to only 20% of the upper extremities examined. In about one third of the wrists prepared, the first tunnel was clearly divided by a septum, so that 2 or more osteofibrous tunnels were present within the main tunnel. The number, thickness and length of such accessory tendons have a functional significance in the development of de Quervain's stenosing tendovaginitis and possibly also have a practical significance, as they may be regarded as a source of transplant material for plastic reconstructions.

Abnormality of the labyrinthine artery and its topographical relation to the abducent nerve.

A case of duplication of the labyrinthine artery arising from the basilar artery is described. The more slender branch takes a dorsal course and penetrates the abducent nerve in its uppermost fibres, while the thicker branch passes by the nerve on the ventral side. The two branches of the labyrinthine artery run separately to the internal auditory meatus. This variant was found only in one brain and only on the left side. The clinical relevance of this finding is discussed.