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.

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.

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.