Passive tensile stress and energy of the human hamstring muscles in vivo

The present study measured passive resistance to stretch in the hamstring muscles during a standardized stretch maneuver to estimate tensile forces and energy of the individual hamstring muscles in 7 flexible and 6 inflexible persons defined according to joint range of motion. Using a dynamometer, knee joint moment was measured during slow passive knee extension to a maximal angle (dynamic phase) followed by a 90-s static phase. Cross-sectional areas (CSA) of the separate hamstring muscles were obtained with magnetic resonance (MR) imaging. Mathematical modeling was used to calculate instantaneous muscle length and joint moment arm for each muscle. Subsequently, passive muscle tension (N/cm2) was calculated based on moment arm lengths, knee joint moments, and CSA. Maximal tolerated joint angle was greater in flexible (delta1.30+/-0.06 rad) than inflexible (delta0.84+/-0.06 rad) subjects, P<0.01. The peak tension at maximal angle was greater in flexible (81.8+/-12.5 N/cm2) than inflexible subjects (29.3+/-4.1 N/ cm2), P<0.001. For the separate muscles the overall change in muscle length (delta cm) and moment arm (delta cm) differed between groups, P<0.01. Similarly, muscle stiffness (delta tension/delta muscle length) was greater in flexible than inflexible subjects in the final 3 cm, P<0.01, and in the final 20% of length change, P<0.01. Absorbed energy (mJ/cm2) was greater in flexible than inflexible subjects in the final 40% of length change, P<0.05. These data show that flexible persons can attain a greater angle of stretch with an accompanying greater tensile stress and energy than inflexible persons due to an apparent greater tolerance to the externally applied load, and larger change in moment arm. The obtained stress data appear to be in the toe region of a 'classical' stress-strain curve, and energy rather than stiffness may therefore be more appropriate to analyze during the stretch procedure.     

Paralysis of the first dorsal interosseous muscle after external fixation of a distal radial fracture treated by transfer of the extensor indicis proprius tendon

We describe a patient in whom the motor branch to the first dorsal interosseous muscle was injured by the pins of an fixator used to treat an unstable fracture of the distal radius. She was successfully treated by extensor indicis proprius transfer to the base of the proximal phalanx of the index finger.     

Experimental infusion thrombophlebitis

On the basis of clinical experience it has been claimed that glucose results in a higher incidence of infusion thrombophlebitis than fructose, and that glucose solutions in concentrations higher than 5% are extremely irritant to the venous endothelium. The validity of these two assertions has been investigated by an experimental method based on a quantitative histological study of rabbit-ear veins into which infusions were given under standardized conditions. In two series of experiments, it was shown (1) that fructose solutions caused significantly more inflammatory changes in the veins than did glucose solutions, and (2) that glucose in 10% solutions caused significantly more injury to the veins than 5% solutions, although the difference in the average inflammatory changes was only slight.     

Arthroscopy of the proximal interphalangeal joints of the finger

Cadaveric studies were carried out to evaluate the technique, portals and possible indications for arthroscopy of the proximal interphalangeal joints of the finger. We suggest horizontal placement of the hand instead of using a traction tower, as it is important to be able to flex the joint freely. The recommended arthroscopic portals are either between the central slip and the lateral bands of the extensor mechanism or between the lateral band and the collateral ligament. A blunt technique of introduction is used to avoid iatrogenic cartilage damage and possible digital nerve injury.     

Immediate versus delayed meniscal allograft transplantation in sheep

The aim of the current study was to assess the effect of immediate and delayed transplantation on articular cartilage. Icelandic sheep had surgery on the medial menisci in both knees. The knees were divided into four groups; 16 control knees had sham surgery, 15 knees had meniscectomy, 14 knees had immediate allograft transplantation, and 14 knees had delayed transplantation 3 months after meniscectomy. The two horns of the fresh allograft were fixed with suture anchors through bone tunnels. The sheep had autopsies 6 months after surgery. An additional six knees were examined 3 months after meniscectomy to examine the cartilage before the delayed implantation. Four standardized samples were taken from the medial compartment of the knee for histologic evaluation according to a modification of Mankin's system, where degenerative changes to the articular cartilage were scored semiquantitatively for structure, proteoglycan content, cellularity, and cell cloning. Knees that had meniscectomy and delayed transplantation showed equally high scores in articular cartilage degeneration, and both scored higher than knees that had immediate transplantation, which again scored higher than the control knees. In short-term observations, immediate medial meniscal allograft transplantation reduced but did not prevent degeneration of the articular cartilage. Immediate transplantation was superior to delayed transplantation in preventing cartilage degeneration.     

Sub-classification of low-grade cerebellar astrocytoma: is it clinically meaningful?

OBJECTIVES: The objectives were to identify prognostic factors for the survival of children with cerebellar astrocytoma, and to evaluate the reproducibility and prognostic value of histological sub-classification and grading. METHODS: Children aged 0-14 years treated in Denmark for a cerebellar astrocytoma in the period 1960-1984 were included and followed until January 2001 or until their death. The histological specimens from each patient were reviewed for revised grading and classification according to three different classification schemes: the WHO, the Kernohan and the Daumas-Duport grading systems. RESULTS: The overall survival rate was 81% after a follow-up time of 15-40 years. The significant positive prognostic factors for survival were "surgically gross-total removal" of the tumour at surgery and location of the tumour in the cerebellum proper as opposed to location in the fourth ventricle. No difference in survival time was demonstrated when we compared pilocytic astrocytoma and fibrillary astrocytoma. Moreover, we found that the Kernohan and the WHO classification systems had no predictive value and that the Daumas-Duport system is unsuitable as a prognostic tool for low-grade posterior fossa astrocytomas. CONCLUSION: Discordant observations due to interobserver variability make histological sub-classification of low-grade cerebellar astrocytomas in children insufficient for predicting prognosis and biological behaviour. Similar survival rates in a population of paediatric low-grade cerebellar astrocytomas of grades I and II indicate that tumour grade has no prognostic significance within this group of patients. "Surgically gross-total removal", especially if the tumour is located in the fourth ventricle is of the highest importance for long-term survival. Histological sub-classification of the tumours has no predictive value.     

Effects of gastric bypass surgery on glucose absorption and metabolism during a mixed meal in glucose-tolerant individuals

Aims/hypothesis

Roux-en-Y gastric bypass surgery (RYGB) improves glucose tolerance in patients with type 2 diabetes, but also changes the glucose profile in response to a meal in glucose-tolerant individuals. We hypothesised that the driving force for the changed postprandial glucose profiles after RYGB is rapid entry of glucose into the systemic circulation due to modified gastrointestinal anatomy, causing hypersecretion of insulin and other hormones influencing glucose disappearance and endogenous glucose production.

Methods

We determined glucose absorption and metabolism and the rate of lipolysis before and 3 months after RYGB in obese glucose-tolerant individuals using the double-tracer technique during a mixed meal.

Results

After RYGB, the postprandial plasma glucose profile changed, with a higher peak glucose concentration followed by a faster return to lower than basal levels. These changes were brought about by changes in glucose kinetics: (1) a more rapid appearance of ingested glucose in the systemic circulation, and a concomitant increase in insulin and glucagon-like peptide-1 secretion; (2) postprandial glucose disappearance was maintained at a high rate for a longer time after RYGB. Endogenous glucose production was similar before and after surgery. Postoperative glucagon secretion increased and showed a biphasic response after RYGB. Adipose tissue basal rate of lipolysis was higher after RYGB.

Conclusions/interpretation

A rapid rate of absorption of ingested glucose into the systemic circulation, followed by increased insulin secretion and glucose disappearance appears to drive the changes in the glucose profile observed after RYGB, while endogenous glucose production remains unchanged.

Trial registration

ClinicalTrials.gov NCT01559792.

Funding

The study was part of the UNIK program: Food, Fitness & Pharma for Health and Disease (see www.foodfitnesspharma.ku.dk). Funding was received from the Novo Nordisk foundation and the Strategic Research Counsel for the Capital Area and Danish Research Agency. The primary investigator received a PhD scholarship from the University of Copenhagen, which was one-third funded by Novo Nordisk.     

Novel methods for tendon investigations

Purpose.?Tendon structures have been studied for decades, but over the last decade, methodological development and renewed interest for metabolic, circulatory and tissue protein turnover in tendon tissue has resulted in a rising amount of investigations.

Method.?This paper will detail the various modern investigative techniques available to study tendons.

Results.?There are a variety of investigative methods available to study the correlations between mechanics and biology in tendons.

Conclusion.?The available methodologies not only allow for potential insight into physiological and pathophysiological mechanisms in tendon tissue, but also, to some extent, allow for more elaborate studies of the intact human tendon.     

Preliminary experience with mammography. Reliability of mammography in patients with a palpable tumour of the breast

Radiologists with very limited practical experience in mammography initially achieved a low PVpos (0.50) and a high PVneg (0.95) in blind mammography of 80 patients with 85 excised and histologically examined breast tumours. After having read films from approximately 2500 patients the initial films were blindly reevaluated. PVneg was unchanged, whereas PVpos was elevated significantly (0.80). The intraobserver variation was 11.5 per cent. The actual interobserver variation was 3.2 per cent. These findings indicate that the reliability of blind mammography in patients with palpable tumours of the breast is considerable, also in case of only limited mammographic experience.     

Genetic alterations of the BRI2 gene: familial British and Danish dementias

Classic arguments sustaining the importance of amyloid in the pathogenesis of dementia are usually centered on amyloid beta (Abeta) and its role in neuronal loss characteristic of Alzheimer disease, the most common form of human cerebral amyloidosis. Two non-Abeta cerebral amyloidoses, familial British and Danish dementias, share many aspects of Alzheimer disease, including the presence of neurofibrillary tangles, parenchymal pre-amyloid and amyloid deposits, cerebral amyloid angiopathy, and a widespread inflammatory response. Both early-onset conditions are linked to specific mutations in the BRI2 gene, causing the generation of longer-than-normal protein products and the release of 2 de novo created peptides ABri and ADan, the main components of amyloid fibrils in these inherited dementias. Although the molecular mechanisms and signal transduction pathways elicited by the amyloid deposits and their relation to cognitive impairment remain to be clarified, new evidence indicates that, independent of the differences in their primary structures, Abeta, ABri, and ADan subunits are able to form morphologically compatible ion-channel-like structures and elicit single ion-channel currents in reconstituted lipid membranes. These findings reaffirm the notion that non-Abeta amyloidosis constitute suitable alternative models to study the role of amyloid deposition in the mechanism of neuronal cell death.