Mechanism of action of bovine testicular hyaluronidase. Mapping of the active site.

The reactions of purified, homogeneous bovine testicular hyaluronidase have been studied with radioactively labeled oligomers of hyalobiuronic acid, (GlcUA-GlcNAc)n, as substrates and acceptors. Transglycosylation occurs by transfer of a glycosyl residue with retention of configuration from a leaving group to an acceptor. On the basis of detailed examination of cleavage and transglycosylation patterns for the trimer; comparison of trimer, tetramer, and polymer as substrates; comparison of acceptors; equilibrium binding; and other data, it is proposed that the enzyme's active site consists of five subsites for hyalobiuronate residues. In the terminology of Schechter, I., and Berger, A. ((1966) Biochemistry 5, 3371), these are s2-s1-s' 2-s3, where the reducing terminus is to the right, and cleavage occurs between s1 and s' 1. It is proposed that subsite s'2 has a high affinity for a substrate residue, while s1 and s'1 have low substrate affinity, and s2 and s' 3 are intermediate in affinity. This proposal is seen to have mechanistic implications. The reactions of several substrates show similar bell-shaped pH dependences, with optima in the region of pH 5 to 5.5.     

Molecular mapping of Or, a gene inducing beta-carotene accumulation in cauliflower (Brassica oleracea L. var. botrytis).

The cauliflower (Brassica oleracea L. var. botrytis) Or gene is a semi-dominant, single-locus mutation that induces the accumulation of high levels of beta-carotene in various tissues of the plant, turning them orange. As part of a map-based cloning strategy, molecular mapping of the Or gene in the cauliflower genome was undertaken in a mapping population consisting of 195 F2 individuals. By using amplified fragment length polymorphism (AFLP) in conjunction with bulked segregant analysis, we identified 10 AFLP markers closely linked to the Or gene. Four of the most closely linked flanking markers were converted into restriction fragment length polymorphism (RFLP) markers. Mapping of these markers in the mapping population placed two of them at 0.5 cM from the Or locus on one side, while another marker flanked the Or gene at 1.6 cM on the other side. Three of these markers were also successfully converted into sequence-characterized amplified region (SCAR) markers. These PCR-based markers will be useful for a large-scale application in facilitating the positional cloning of the Or gene.     

Cytochemistry of the skin of patients with mucopolysaccharidoses.

The distribution of complex carbohydrates has been investigated at the light and electron microscope levels in sweat glands of normal subjects and patients with Hurler's or Hunter's disease. Normal sweat glands examined with a battery of light microscopic histochemical methods revealed sulphated complex carbohydrate in secretory granules of the dark cells. These granules lacked affinity for dialysed iron (DI) at the light and electron microscope levels. The DI method demonstrated acid complex carbohydrates ultrastructurally on the surface of the intercellular canaliculi and central lumen in normal sweat glands. DI-reactive acidic material, presumably of mucopolysaccharide nature, surrounded and extended between collagen bundles in the stroma of normal skin, but was absent from the band which ensheathed the sweat gland and consisted of individual rather than bundled collagen fibrils. DI-reactive mucopolysaccharide lined and partially filled vacuoles of dark cells showing a laminar distribution in vacuoles of clear cells in sweat glands of a Hunter patient. The DI method also visualized mucopolysaccharide distributed throughout vacuoles in fibroblasts of this patient. DI-reactive acid material covered the luminal surface of the sweat gland, coated collagen bundles in the stroma and spared the periglandular collagenous sheath in skin from Hurler and Hunter patients as in that from normal controls. Acid phosphatase was localized ultrastructually in vacuoles and nearby cytoplasm and on plasmalemmae of clear cells, dark cells and myoepithelial cells of sweat glands from Hurler and Hunter patients. Vacuoles of dermal fibroblasts and Schwann cells in these specimens also exhibited strong acid phosphatase activity.     

Use of standardised patients in the evaluation of a residency mood disorders curriculum: a brief report

Background and objectives The purpose of this paper is to describe the use of resident performance on an observed structured clinical examination (OSCE) as a tool to refine a mood disorders curriculum, and to disseminate a mood disorders OSCE for use in other residency settings.Methods A depression-focused OSCE and a direct observation evaluation tool were developed and implemented. A total of 24 first-year family medicine residents (PGY1) participated in the OSCE, and their performance was used to direct changes in a mood disorders curriculum.Results Residents performed well on general interview behaviours, and 67% were able to uncover depression in a patient presenting with headaches. Less than 50% of the residents asked about suicidal ideation and recreational drug use. Curriculum was added that addressed the latter deficiencies.Conclusions Tracking of resident performance on specific behaviours during OSCE sessions can be used for curriculum evaluation purposes. The mood disorders curriculum in additional family medicine residency programmes can now be evaluated using our depression-focused OSCE and Clinical Performance Checklist.     

Breast MRI in nonpalpable breast lesions: a randomized trial with diagnostic and therapeutic outcome – MONET – study

Background

In orthodontic treatment, anchorage control is a fundamental aspect. Usually conventional mechanism for orthodontic anchorage control can be either extraoral or intraoral that is headgear or intermaxillary elastics. Their use are combined with various side effects such as tipping of occlusal plane or undesirable movements of teeth. Especially in cases, where key-teeth are missing, conventional anchorage defined as tooth-borne anchorage will meet limitations. Therefore, the use of endosseous implants for anchorage purposes are increasingly used to achieve positional stability and maximum anchorage.

Methods/Design

The intended study is designed as a prospective, multicenter randomized controlled trial (RCT), comparing and contrasting the effect of early loading of palatal implant therapy versus implant loading after 12 weeks post implantation using the new ortho-implant type II anchor system device (Orthosystem Straumann, Basel, Switzerland). 124 participants, mainly adult males or females, whose diagnoses require temporary stationary implant-based anchorage treatment will be randomized 1:1 to one of two treatment groups: group 1 will receive a loading of implant standard therapy after a healing period of 12 week (gold standard), whereas group 2 will receive an early loading of orthodontic implants within 1 week after implant insertion. Participants will be at least followed for 12 months after implant placement. The primary endpoint is to investigate the behavior of early loaded palatal implants in order to find out if shorter healing periods might be justified to accelerate active orthodontic treatment. Secondary outcomes will focus e.g. on achievement of orthodontic treatment goals and quantity of direct implant-bone interface of removed bone specimens. As tertiary objective, a histologic and microtomography evaluation of all retrieved implants will be performed to obtain data on the performance of the SLA surface in human bone evaluation of all retrieved implants. Additionally, resonance frequency analysis (RFA, Osstell? mentor) will be used at different times for clinically monitoring the implant stability and for histological comparison in order to measure the reliability of the resonance frequency measuring device.

Trial registration

Current Controlled Trials ISRCTN97142521.     

Physiological basis of reduced Al tolerance in ditelosomic lines of Chinese Spring wheat

Aluminum tolerance was assessed in the moderately Al-tolerant wheat (Triticum aestivum L.) cultivar Chinese Spring and a set of ditelosomic lines derived from Chinese Spring. Three ditelosomic lines lacking chromosome arms 4DL, 5AS and 7AS, respectively, exhibited decreased Al tolerance relative to the euploid parent Chinese Spring based on reduced root growth in Al-containing solutions. The physiological basis of the reduced Al tolerance was investigated. Measurements by inductively coupled argon plasma mass spectroscopy of root apical Al accumulation demonstrated that two of these three lines had a decreased ability to exclude Al from the root apex, the site of Al phytotoxicity. As Al-induced malate exudation has been suggested to be an important physiological mechanism of Al tolerance in wheat, this parameter was quantified and malate exudation was shown to be smaller in all three deletion lines compared with Chinese Spring. These results suggest that the decreased Al tolerance in at least two of the three ditelosomic lines is due to the loss of different genes independently influencing a single Al-tolerance mechanism, rather than to the loss of genes encoding alternative Al-tolerance mechanisms. Received: 3 July 2000 / Accepted: 9 August 2000