Longitudinal in vivo effects of growth hormone overexpression on bone in transgenic mice.

In this study we examined the effect of systemic overexpression of GH on bone in transgenic mice longitudinally in vivo over a period of 9 months. We observed substantially increased BMC in GH transgenic mice and a significant reduction in serum osteocalcin. GH effects on bone were strongly dependent on gender and developmental stage. INTRODUCTION: State-of-the-art bone marker and microimaging technology was applied in this longitudinal study to examine bone metabolism, BMC, bone density, and cortical bone structure over the life span of growth hormone (GH) transgenic (tg) mice. MATERIALS AND METHODS: Thirty-eight mice from four genetic groups (male, female, tg, and controls) were examined with DXA, and their femur and tibia were examined with peripheral QCT (pQCT). Osteocalcin (formation) and collagen cross-links (resorption) from serum and urine were also measured at postnatal weeks 3, 6, 9, 12, 18, 26, and 38. RESULTS: GH tg mice displayed a significant increase in body weight (up to 50%) and BMC (up to 90%), but serum osteocalcin was significantly reduced compared with controls. GH tg females (but not males) displayed increased trabecular density over controls up to week 12. In contrast, male (but not female) GH tg mice displayed a higher cortical cross-sectional area than controls. Cortical density was significantly lower in both male and female GH tg mice compared with control mice. CONCLUSIONS: The increase in BMC in GH tg mice is associated with reduced serum osteocalcin levels, indicating that bone turnover may be lower than in the control mice. On a structural level, bone responds to GH excess in a gender-specific manner, with alterations varying substantially between different developmental stages.     

A framework for evaluating image segmentation algorithms.

The purpose of this paper is to describe a framework for evaluating image segmentation algorithms. Image segmentation consists of object recognition and delineation. For evaluating segmentation methods, three factors-precision (reliability), accuracy (validity), and efficiency (viability)-need to be considered for both recognition and delineation. To assess precision, we need to choose a figure of merit, repeat segmentation considering all sources of variation, and determine variations in figure of merit via statistical analysis. It is impossible usually to establish true segmentation. Hence, to assess accuracy, we need to choose a surrogate of true segmentation and proceed as for precision. In determining accuracy, it may be important to consider different 'landmark' areas of the structure to be segmented depending on the application. To assess efficiency, both the computational and the user time required for algorithm training and for algorithm execution should be measured and analyzed. Precision, accuracy, and efficiency factors have an influence on one another. It is difficult to improve one factor without affecting others. Segmentation methods must be compared based on all three factors, as illustrated in an example wherein two methods are compared in a particular application domain. The weight given to each factor depends on application.     

Molecular properties and structure-function relationships of lethal peptides from venom of Wagler's pit viper, Trimeresurus wagleri.

Two new lethal peptides (waglerins) were purified from the venom of Trimeresurus wagleri, and sequenced. We found them to be analogs of lethal peptides (waglerins) I and II reported previously (Weinstein et al., Toxicon 29, 227-236, 1991), with an additional Ser-Leu on the amino terminus. Three of the four waglerins were synthesized and the products were chemically and biologically equivalent to the naturally occurring counterparts in venom. Murine i.p. LD50 for synthetic waglerins I, SL-I and II were 0.33, 0.22, and 0.51 mg/kg, respectively. The single, intramolecular disulfide bond in each synthetic peptide formed rapidly in high yield. The reduced (cysteine-containing) forms of the peptides appeared to have significant toxicities, even without prior disulfide bond formation, but synthetic analogs with serine substituted for cysteine were not toxic. The synthetic dimer of waglerin I, formed by two intermolecular disulfide bonds, was not toxic, but rapidly rearranged to lethal, monomeric waglerin I at alkaline pH upon the addition of 5 mM beta-mercaptoethanol. Waglerin I was inactivated by cleavage at Tyr-15 with chymotrypsin.     

Arthroscopic synovectomy of rheumatoid shoulder and elbow

Surgical Principles Radical arthroscopic synovectomy of rheumatoid shoulder and elbow. Revised Version from: Operat. Orthop. Traumatol. 4 (1992), 112–129 (German Edition).     

Intrathecal administration of substance P in the rat: the effect on bladder and urethral sphincteric activity.

At the lumbosacral spinal cord level in the rat, substance P-positive neurons are present in dense concentration in the dorsal horn and the sacral parasympathetic nucleus. We undertook the present study to investigate the effect of intrathecal substance P (10 micrograms at the L6-S1 level) on urinary bladder and urethral sphincteric activity and to compare these effects with those of intravenous and intra-arterial administration. Three different bladder pressure responses were triggered by intrathecal substance P: (A) an immediate, strong bladder contraction (n = 5); (B) augmentation of the micturition reflex, as indicated by strong detrusor contractions in response to intravesical saline perfusion (n = 4); and (C) a slow, gradual increase to a high, steady peak (n = 8). The sphincteric electromyographic (EMG) activity was consistently increased. When substance P was given intravenously (n = 10) and intra-arterially (n = 3), the form, duration, and maximal amplitude of bladder contractions (owing to a direct smooth-muscle action) were comparable with those of Group A. The effects in intrathecal Groups B and C suggest that substance P provides a tonic influence on motor horn cells and on the preganglionic neurons in the sacral parasympathetic nucleus at the lumbosacral spinal cord level, where neuronal circuits controlling bladder and sphincteric activity are located.     

Histochemical light and electron microscopic investigations on an eosinophilic granuloma]

An eosinophilic granuloma has been investigated by means of histochemical proofs for enzymes and tissue elements and common staining methods. The best method was be found the proof for the enzyme phenol oxidase (EC 1.14.18.1). In this way it is possible to determine eosinophils rapidly and surely and to receive an overview on the frequency and distribution of these cells. The histiocytic-like cells was identified electron microscopical as Langerhans' cells. This cells are in narrow contact to many eosinophilic granulocytes. Their granula have manifold changes in their structure. The granula are possibly able to produce new structures of the cell. The eosinophilic granuloma correspond to a cell mediating immunological defence reaction approximate to the type of a delayed hypersensitivity.     

Responsiveness of the somatosensory system after nerve injury and amputation in the human hand

We studied the responsiveness of the somatosensory system in humans after prolonged deprivation of peripheral input. Eight patients with traumatic transection of the median or ulnar nerve and 6 patients with amputation of a finger or hand underwent microneurography and intraneural stimulation. Bundles of nerve fibers were electrically stimulated through a microelectrode placed in the affected nerve proximally to the site of damage or in the case of amputees, in a nerve fascicle supplying the stump. During intraneural stimulation the subjects with nerve injuries reported distinct percepts in the hypoesthetic skin. Their projections were usually confined to the territory of a single or two adjacent palmar digital nerves, similar to the fascicular territories of healthy nerves in control subjects, but there was much less microneurographically recordable afferent activity than in normal subjects. In amputees intraneural stimulation evoked sensations in a phantom digit or digits in over three fourths of the fascicles studied. We conclude that (1) the somatosensory system remains able to process information from a nerve fascicle that has lost its cutaneous territory, and (2) somatosensory localization remains accurate despite the presumed central reorganization that takes place after nerve division or amputation. This lack of functional adaptation has important implications with regard to our understanding of human central nervous system plasticity.     

Evaluation of the Transverse Sinus by Magnetic Resonance Venography: Limitations-An Illustrative Case Report

Many techniques of magnetic resonance angiography depend on flow velocity. The broad normal range of venous flow velocities and preferential patterns of drainage, particularly in the transverse sinuses, may produce images that are diagnostically misleading. This reports such a case, with samples of various flow patterns in the transverse sinuses of other individuals, as demonstrated by one magnetic resonance angiographic technique (time-of-flight).