[Biomaterials and the living system].

Biomaterials, whatever their applications: cardiovascular surgery, orthopaedic surgery, ophthalmology, plastic surgery, urology, membranes for renal dialysis have some common approach. It is a very interdisciplinary field that needs intervening bioengineers, M.D, biologists and materials scientists.

Induction of Toxoplasma gondii cystogenesis and multiplication arrest by treatments with a phosphatidylcholine-specific phospholipase C inhibitor.

A model of tissue cyst formation was developed using D609, a specific inhibitor of phosphatidylcholine specific-phospholipase C. The phospholipase inhibitor induced a decrease in Toxoplasma gondii multiplication and several successive treatments could lead to an arrest in parasite multiplication and full encystment of the parasites. This could be a first step towards an in vitro model of T.

Anatomic and mechanical properties of the lateral disc attachment of the temporomandibular joint.

Purpose: This study measured the strength to failure of the human temporomandibular joint (TMJ) lateral disc attachment (LDA) using a tension-compression machine. These data were correlated with the LDA location and its morphologic aspects, the age and sex of the subjects, and the amount of the lateral pterygoid muscle (LPM) inserted in the disc.

Methods: Forty-two TMJs without any obvious internal damage were carefully dissected to preserve the LDA.

The acoustic and structural properties of the human femur.

This study evaluates the variations in the acoustic properties of the human femur at ten evenly spaced locations along its length, as well as differences that exist within given transverse sections. Six pairs of human femora, three male and three female, were sectioned, ground, and polished, and scanned with a microprocessor-driven scanning acoustic microscope. Images with a resolution of approximately 140 microns were used to calculate the average acoustic impedances for each transverse cross section and each quadrant within a cross section.

Addition of fibrin sealant to ceramic promotes bone repair: long-term study in rabbit femoral defect model.

Despite their impact on the healing of soft connective tissue, fibrin sealants have not been shown conclusively to have an important role in the healing of bone defects. We report the positive influence of fibrin sealants on repair of cancellous bone cavities filled with a porous, resorbable ceramic. We studied two fibrin sealants: Autocolle and Tissucol.

Differential expression and function of PACAP and VIP receptors in four human colonic adenocarcinoma cell lines.

Human colonic adenocarcinoma cell lines have conserved several features of the native tissue. Among these is the expression of cell surface receptors for hormones and neurotransmitters that may be involved in the regulation of proliferation and differentiation processes in these cancer cells. Here, we confirm that high-affinity binding sites for the Vasoactive Intestinal Polypeptide (VIP) and for the VIP analogue Pituitary Adenylate-Cyclase Activating Polypeptide (PACAP), were expressed in 4 human colonic adenocarcinoma cell lines, HT29, SW403, DLD-1 and Caco-2, that spontaneously displayed variable phenotypic properties in culture.

Cytokine release from marrow mononuclear cells is negatively correlated to cortical elasticity in non-osteoporotic postmenopausal women.

Activation of bone remodeling is likely to be under the control of mechanical factors acting, in part, through soluble local factors. We therefore investigated a relationship between cytokine production by marrow cells and bone elasticity. We studied 36 non-osteoporotic postmenopausal women undergoing hip arthroplasty for hip arthrosis (mean age: 68 +/- 8 years; lumbar BMD Z-score: +0.

[Locked nail plate: a new treatment for unstable pertrochanteric fractures].

Purpose Of The Study: This work is the outcome of a preliminary study on pertrochanteric fractures which showed that impaction with simple nail plates (SNP) was lead by hypercorrection in valgus demineralization and malposition of the nail in the femoral neck. To improve anchoring of the nail in the cervico-cephalic part, the authors propose to use a locked nail-plate (LNP), an innovative device based on the addition to the normal nail plate, of a screw securing neck and nail.

Mechanical Study: Mechanical flexion and compression tests carried out on 8 pairs of femurs of fresh cadavers showed comparable rigidity for the two mounting, SNP and LNP.

Scanning Acoustic Microscopy of human and canine cortical bone microstructure at high frequencies.

An Olympus UH3 Scanning Acoustic Microscope (Tokyo, Japan) has been used in the burst mode at 400 and 600 MHz to study the elastic properties of osteons and osteonic lamellae in both canine and human compact cortical bone. The nominal resolution at each frequency is within the width of an individual lamella. Three important new observations have been made regarding the acoustic properties of individual lamellae.

On the mechanical characterization of compact bone structure using the homogenization theory.

In a previous paper (Crolet et al., 1993, J. Biomechanics 26, 677-687), a modelling of the mechanical behavior of compact bone was presented, in which the homogenization theory was the basic tool of computation.

Switches in the expression and function of PACAP and VIP receptors during phenotypic interconversion in human neuroblastoma cells.

Clonal human neuroblastoma cells SH-IN undergo a very conspicuous phenotypic change in culture. Large substrate-adherent cells with a slow growth rate give rise to small cells emerging in focal aggregates and growing to high cell densities. This is accompanied by a dramatic switch in the expression of receptors for the structurally related neuropeptides VIP (vasoactive intestinal polypeptide) and PACAP (pituitary adenylate cyclase activating polypeptide).

Variation in the inflammatory properties of basic calcium phosphate crystals according to crystal type.

Objective: To determine the inflammatory potential of basic calcium phosphate (BCP) crystals, which have been identified in human joints.

Methods: Hydroxyapatite, carbonate apatite, whitlockite, and octacalcium phosphate crystals were injected in rat air pouches. Volume and cellularity of the exudate were measured.

Novel assays based on human growth hormone receptor as alternatives to the rat weight gain bioassay for recombinant human growth hormone.

Two methods, High-Performance Receptor Binding Chromatography (HPRBC) and Cell Proliferation (CP), have been developed as alternatives to the classical hypophysectomized rat weight gain bioassay for the determination of potency for recombinant human growth hormone (rhGH). In the HPRBC assay, rhGH is combined with an excess of the soluble extracellular domain of the recombinant human growth hormone receptor (referred to as 'receptor' in the discussion of the HPRBC assay). Nondenaturing size-exclusion chromatography is used to analyzed the resulting complex, which forms in a 2:1 receptor to rhGH ratio.

A new apparatus for studying the effect of hydrostatic pressure on cells in culture : application to osteoblastic cells ROS 17/2.8.

Although mechanical stresses have long been recognized as an important factor in the regulation of bone remodeling, the mechanism underlying this effect has remained obscure. A number of methods have been devised to apply forces to bone tissues and bone-derived cells in order to investigate the biochemical results of mechanical stimuli. In this paper we report a method for applying a well controlled cyclic hydrostatic pressure on cultured ROS 17/2.

[Axillary lymphoceles after breast cancer surgery. Pathogeny, prevention].

We report a retrospective series of 126 patients seen in 1992 for conservative surgery (group T) or Patey procedure (group P) for breast cancer. We looked for factors predictive of axillary lymphocele and their prevention. Axillary lymphadenectomy performed in patients undergoing surgery for breast cancer leads to a certain degree of morbidity including the development of lymphoceles.

[Bradycardia during treatments of weight loss].

Sinus bradycardia was observed in 10 adolescents participating in a weight loss diet conducted in a health centre. The precise cause was assessed. The subject's age ranged from 10 to 15 years and weight loss ranged from 8 to 24 kg over a period ranging from 8 to 23 weeks.

[Cat-scratch disease presenting as a pseudotumor. Imaging by x-ray computed tomography and MRI].

Cat-scratch disease is usually a self-limiting illness but it can initially present as a tumor. A case of a lesion of the arm is described, with CT and MR findings. The radiologic appearance is not characteristic but the diagnosis can be suggested in a predisposing clinical setting.

VIP as a cell-growth and differentiation neuromodulator role in neurodevelopment.

In addition to its commonly recognized status as a neuromodulator of virtually all vital functions, including neurobiological, the neuropeptide VIP plays a role in the control of cell growth and differentiation and of neuronal survival. Through these actions, VIP, whose impact appears early in ontogeny, may possess developmental functions. VIP can be stimulatory or inhibitory on cell growth in function of the model considered.

[Orthopedic biomaterials].

It is very challenging to insure long term security and effectiveness for joint arthroplasties, artificial ligaments, extensive bone replacement and some other orthopaedic biomaterials. How can we predict the long term security and efficacy of such an implant? Only an interdisciplinary approach can provide a satisfactory answer. The surgeon must define the needs, he must find the appropriate surgical techniques and conduct the clinical trial.

[Experimental capsulo-ligamentar lesions of the knee during passive hyperextension. Biomechanical aspects. A lesional evaluation and consequences].

Purpose Of The Study: Passive hyperextension is a rare mechanism of injury of knee ligaments in clinical practice. The lesions are often complex and no consensus exists about their sequence. Our purpose was to study the mechanical behavior and the anatomical lesions of the knee following passive hyperextension until rupture.

Analysis of the general features of the soft tissue response to some metals and ceramics using quantitative histomorphometry.

This article analyzes the general features of the tissue response to orthopedic biomaterials when implanted in the paraspinal muscles in rats for periods between 1 week and 1 year. Using a computer-assisted cell counting method, it was shown that the membrane thickness was a stable parameter that poorly correlated with the other histomorphometric parameters except fibrocyte distance parameters. Macrophages were significant in number only in the short term and were always located at the implant-tissue interface.

Infection with Toxoplasma gondii does not Alter TNFalpha and IL-6 Secretion by A human Astrocytoma Cell Line.

The secretion of tumour necrosis factor-alpha (TNFalpha), interleukin-1alpha (IL-alpha) and interleukin-6 (IL-6) by a human astrocytoma cell fine was studied 1 h, 3 h, 6 h and 24 h after infection with tachyzoites from three Toxoplasma gondii strains (virulent, RH; cystogentc, 76K and Prugniaud strains). The astrocytoma cell fine constitutively secreted TNFalpha and IL-6, but no IL-1alpha. A positive control was obtained by stimulation with phorbol esters inducing a significant increase (p < 0.

Protein conjugates of defined structure: synthesis and use of a new carrier molecule.

A new carrier molecule, NH2OCH2CO-(Gly)3-[Lys(H-Ser-)]5-Gly-OH, has been synthesized to facilitate the preparation of protein conjugates of defined structure. Special features are as follows: (i) (aminooxy)-acetyl as a terminal group, which reacts specifically to form an oxime bond under very mild conditions with an aldehyde group placed on a protein in a prior step; (ii) a spacer group of three Gly residues; and (iii) a set of five Lys residues, each of which is acylated with a Ser residue. A second form of the carrier molecule, HCO-m-C6H4CH = NOCH2CO-(Gly)3-[Lys(H-Ser)]5-Gly-OH, was also prepared.

Scanning acoustic microscope studies of the elastic properties of osteons and osteon lamellae.

Scanning acoustic microscopy (SAM) provides the means for studying the elastic properties of a material at a comparable level of resolution to that obtained by optical microscopy for structural studies. SAM is nondestructive and permits observation of properties in the interior of materials which are optically opaque. Two modes of ultrasonic signals have been used in a Model UH3 Scanning Acoustic Microscope (Olympus Co.