Frequency-difference MIT imaging of cerebral haemorrhage with a hemispherical coil array: numerical modelling.

The feasibility of detecting a cerebral haemorrhage with a hemispherical MIT coil array consisting of 56 exciter/sensor coils of 10 mm radius and operating at 1 and 10 MHz was investigated. A finite difference method combined with an anatomically realistic head model comprising 12 tissue types was used to simulate the strokes. Frequency-difference images were reconstructed from the modelled data with different levels of the added phase noise and two types of a priori boundary errors: a displacement of the head and a size scaling error. The results revealed that a noise level of 3 m degrees (standard deviation) was adequate for obtaining good visualization of a peripheral stroke (volume approximately 49 ml). The simulations further showed that the displacement error had to be within 3-4 mm and the scaling error within 3-4% so as not to cause unacceptably large artefacts on the images.

Forward modelling of magnetic induction tomography: a sensitivity study for detecting haemorrhagic cerebral stroke.

For a magnetic induction tomography (MIT) system operating at 10 MHz, the signals produced by a haemorrhagic cerebral stroke were computed using an anatomically realistic, multi-layer, finite element (FE) head model comprising 12 tissues. The eddy-current problem was approximated using the commercial FE package, Comsol Multiphysics, and the numerical techniques employed were validated using a benchmark test. Mesh convergence for the head model was investigated for first- and second-order elements. MIT signals were computed for strokes of different sizes and locations in the brain to judge the sensitivity of the MIT configuration. The results revealed that for a large peripheral stroke (volume 50 cm(3)), 27% of the signals were above the phase noise level achievable in our current data-collection hardware (approximately 20 m degrees). In order to detect the same percentage of the signals due to a centrally located small stroke, a reduction in phase noise to 1 m degrees was necessary.

Imaging cerebral haemorrhage with magnetic induction tomography: numerical modelling.

Magnetic induction tomography (MIT) is a new electromagnetic imaging modality which has the potential to image changes in the electrical conductivity of the brain due to different pathologies. In this study the feasibility of detecting haemorrhagic cerebral stroke with a 16-channel MIT system operating at 10 MHz was investigated. The finite-element method combined with a realistic, multi-layer, head model comprising 12 different tissues, was used for the simulations in the commercial FE package, Comsol Multiphysics. The eddy-current problem was solved and the MIT signals computed for strokes of different volumes occurring at different locations in the brain. The results revealed that a large, peripheral stroke (volume 49 cm(3)) produced phase changes that would be detectable with our currently achievable instrumentation phase noise level (17 m degrees ) in 70 (27%) of the 256 exciter/sensor channel combinations. However, reconstructed images showed that a lower noise level than this, of 1 m degrees , was necessary to obtain good visualization of the strokes. The simulated MIT measurements were compared with those from an independent transmission-line-matrix model in order to give confidence in the results.

Glucosaminylmuramyl dipeptide (GMDP) modulates endothelial cell activities in vitro but has no effect on angiogenesis in vivo.

OBJECTIVE AND DESIGN: The aim of the study was to evaluate the effects of GMDP on angiogenesis in vivo and as a modulator of human umbilical vein endothelial cell proliferation, cell surface antigen expression and cell adhesion in vitro. MATERIALS: Human umbilical vein endothelial cells (HUVEC), fertilized white leghorn chicken eggs, antibodies against adhesion molecules and glucosaminylmuramyl dipeptide (GMDP). TREATMENT: GMDP [0.01-100 micrograms/ml] applied to cell cultures for 6-72 h and to the chick chorioallantoic membrane (CAM) for four days. METHODS: Angiogenic activity of GMDP in vivo was assessed using the CAM assay; HUVEC proliferation was measured by tritiated thymidine incorporation and cell cycle studies; cell surface antigen expression by indirect immunofluorescence and flow cytometry; cell adhesion by quantification of [3H]-thymidine labeled leukocyte adherence to HUVEC monolayers. Statistical analysis was performed using one-way ANOVA and if necessary was followed by Duncan's multiple range test for variables. RESULTS: GMDP induced [3H]-thymidine incorporation in a concentration- and time-dependent manner (p < 0.003) and significantly increased the porportion of cells in the S phase of the cell cycle (p < 0.03). It weakly augmented the expression of ICAM-1 and CD31 but not adhesion of leukocytes to HUVEC monolayers GMDP was not angiogenic in the CAM assay. CONCLUSIONS: GMDP can modulate endothelial cell activity without the induction of angiogenesis in vivo which may have implications for its use as a therapeutic agent.

The effect of glucosaminylmuramyl dipeptide injection to mice on the course of tuberculous infection and in vitro superoxide anion production.

Immunotherapy as an adjunct to chemotherapy is of interest for optimizing therapeutic regimens for tuberculosis. In this context, we investigated the influence and mode of action ofglucosaminylmuramyl dipeptide (GMDP) in mouse experimental models. Intermittent injections of GMDP to Mycobacterium tuberculosis-infected mice reduced the viable bacilli in the lungs, but increased the counts in the spleens at 16 weeks, but not at earlier harvests after infection. Injections of GMDP selectively ameliorated also in the lungs the spontaneous relapse of infection following chemotherapy. The mode of GMDP action was examined in respect of superoxide anion production. The O2 production by phorbol myristate-induced peritoneal macrophages in vitro was reduced by preinjection of mice with 100 microg of GMDP. Notably, this outcome contrasts and can also override the previously known enhancing effect of MDP on O2- production. The inhibitory activity of GMDP became even more pronounced when testing macrophages from Mycobacterium bovis BCG-infected mice. However, these results do not explain readily the grounds for the contrasting effects of GMDP on the growth patterns of tubercle bacilli in the lungs and spleens. Although the observed effects on bacillary counts have been modest, such action of GMDP could represent a beneficial adjunct to suitably formulated chemotherapeutic regimens.

The Study of Serum Level and Immunochemical Properties of Natural Antibodies to N-Acetylglucosaminyl-N-Acetylmurarnyl Dipeptide in Healthy Donors.

ELISA assay showed that sera from each of 729 healthy donors contained antibodies to the minimal component of bacterial cell walls, N-acetylglucosaminyl-N-acetylmuramyt dipeptide (GMDP). Anti-GMDP antibody levels were determined for 686 sera, which were classified into 3 groups: high- (17.6%), medium- (68.7%) and low-responder (13.7%). Inhibition analysis performed on representative sera showed that a proportion contained specific anti-GMDP antibodies reacting only with GMDP (i.e., GMDP interaction with anti-GMDP antibodies was inhibited by GMDP only) whereas the remaining sera reacted both with GMDP and with tetrasaccharide (GlcNAc-MurNAc)(2) (i.e., GMDP interaction with anti-GMDP antibodies in the latter sera was inhibited by both GMDP and tetrasaccharide). Inhibition analysis indicated, moreover, that the anti-GMDP antibodies contained in high-responder sera had higher affinity than those present in low-responder ones: GMDP inhibited the GMDP + anti-GMDP antibody interaction by 88.7% in the former sera vs. 53% in the latter. Sera contained both IgM and IgG antibodies to GMDP, but the mean level of anti-GMDP IgG antibodies in the high-responder sera was 30 times higher than in the low-responder ones.

Adjuvancy and reactogenicity of N-acetylglucosaminyl-N-acetylmuramyl-dipeptide (GMDP) orally administered just prior to trivalent influenza subunit vaccine. A double-blind placebo-controlled study in nursing home residents.

One hundred and fifty-three nursing home residents received 0, 5, 25 or 50 mg N-acetylglucosaminyl-N-acetylmuramyl-dipeptide (GMDP) orally, and trivalent influenza subunit vaccine intramuscularly. One day after intervention, there was a strong increase of total leucocytes, monocytes and neutrophils in the groups receiving 25 or 50 mg GMDP. A GMDP dose dependent increase in systemic, but not in local, vaccine side-effects was observed. No significant differences in post-vaccination haemagglutination inhibiting serum antibody titres were observed between the four groups, indicating that oral administration of GMDP together with influenza vaccination, does not lead to a higher vaccine efficacy.

The occurrence of natural antibodies to minimal component of bacterial cell wall (N-acetylglucosaminyl-N-acetylmuramyl dipeptide) in sera from healthy humans.

ELISA assay showed that sera from each of 729 healthy donors contained antibodies to the minimal component of bacterial cell walls, N-acetylglucosaminyl-N-acetylmuramyl dipeptide (GMDP). Anti-GMDP antibody levels were determined for 686 sera which were classified into 3 groups: high (17.6%), medium (68.7%), and low responder (13.7%). Inhibition analysis performed on representative sera showed that a proportion contained specific anti-GMDP antibodies reacting only with GMDP (i.e., GMDP interaction with anti-GMDP antibodies was inhibited by GMDP only) whereas the remaining sera reacted both with GMDP and with the tetrasaccharide (GlcNAc-MurNAc)2 (i.e., GMDP interaction with anti-GMDP antibodies in the latter sera was inhibited by both GMDP and the tetrasaccharide). Inhibition analysis indicated, moreover, that the anti-GMDP antibodies contained in high-responder sera had higher affinity than those present in low-responder ones: GMDP inhibited the GMDP + anti-GMDP antibody interaction by 88.7% in the former sera vs. 53% in the latter. Sera contained both IgM and IgG antibodies to GDMP, but the mean level of anti-GMDP IgG antibodies in the high-responder sera was 30 times higher than in the low-responder ones.

Application of angiogenic oligosaccharides of hyaluronan increases blood vessel numbers in rat skin.

Angiogenic oligosaccharides of hyaluronan were applied to the backs of young, adult male rats and the number of blood vessels, within a depth of 136 microns beneath the base of the epidermis, were evaluated. Application of hyaluronan oligosaccharides significantly increased the mean number of blood vessels/mm skin length in six of 11 treated rats when compared with controls. Application of radiolabeled hyaluronan oligosaccharides to skin of one rat demonstrated a penetration to a depth of approximately 800 microns, suggesting that the blood vessels beneath the epidermis would be exposed to the hyaluronan. Hyaluronan has previously been shown to stimulate endothelial cell proliferation; we demonstrate here that these hyaluronan oligosaccharides also specifically stimulate endothelial cell migration. This action of hyaluronan oligosaccharides may prove useful in retarding blood vessel paucity and degeneration observed during the ageing process and following radiotherapy.

In vitro cutaneous biotransformation of propranolol.

The metabolism of propranolol by human skin and by several cell preparations has been investigated in vitro. The major metabolites produced by human skin in organ culture and by keratinocytes were N-desisopropylpropranolol (DIP), propranolol glycol (GLY), and naphthoxylactic acid (NLA). Formation of GLY and NLA was linear with incubation time up to 6 d and was directly proportional to propranolol concentration. Fibroblasts and melanocytes also produced GLY and NLA, but appeared to have lower propranolol-biotransforming activity than keratinocytes. The three metabolites detected arise from side-chain oxidation of propranolol, and the use of specific enzyme inhibitors determined that monoamine oxidase and cytochrome P450 isozymes are involved in their formation. Aldehyde and alcohol dehydrogenases are also probably involved in the formation of NLA and GLY, but attempts to inhibit these enzyme systems were inconclusive, possibly due to the chemical instability of the intermediate aldehyde resulting from monoamine oxidase activity. No evidence was found for conjugation or ring oxidation by the skin or isolated cells. Induction of keratinocyte differentiation with Ca++ or phorbol ester treatment resulted in an increase of overall biotransformation and the NLA/GLY ratio.

The influence of heparin on the wound healing response to collagen implants in vivo.

The biologic response to fibrillar collagen (collagen) and fibrillar collagen plus heparin (collagen/heparin) implants have been compared in the rat subcutaneous and guinea pig dermal wound models. The reconstituted bovine dermal collagen implants were injected subcutaneously in rats at concentrations ranging from 18 to 30 mg/ml and in volumes ranging from 0.5 to 1.0 ml. The biologic response to the collagen implants alone was characterized by a transient invasion of a modest number of inflammatory cells within the first three days of implantation that was followed by limited fibroblast invasion into the peripheral 1/3 of the implant during the course of the next three to four weeks. Occasionally, blood vessels were observed to invade the peripheral regions of the implant. The degree (number) and extent (depth) of cell invasion were inversely related to initial collagen implant concentration. Addition of heparin (0.3-20 micrograms/mg collagen) to these implants resulted in a significant dose-dependent increase in the degree and extent of fibroblast invasion. Radiolabeling studies showed that the collagen and collagen/heparin implants were cleared from the subcutis at identical rates. Implantation of these formulations in a guinea pig dermal wound model was also performed, using a semi-occlusive wound dressing (Opsite) to maintain the implant in the wound site. The fibrillar collagen implant alone was pushed upward by developing granulation tissue at the base of the wound and served as a support for epidermal cell migration, proliferation, and differentiation as wound closure proceeded. The implant was slowly invaded and turned over as granulation tissue developed from the base and margins of the wound bed. The inclusion of heparin in these implants resulted in a significantly different pattern of wound healing. The collagen/heparin implants histologically presented a more broken-up or porous appearance following implantation, which was associated with a greater degree of penetration of developing granulation tissue into the implant itself as compared to the collagen implants. Radiolabeling studies revealed that clearance rates of implants with and without heparin from wound sites were similar, as noted in the rat subcutis. Laser doppler flowmetry studies suggested that the heparin--containing implants were more vascular than control wound sites or sites treated with collagen alone.

No extended HV service.

There is little call for evening, weekend and night health visiting services either from health visitors, health authorities or clients, according to a survey from Barnet HA.

The preparation and physicochemical characterization of an injectable form of reconstituted, glutaraldehyde cross-linked, bovine corium collagen.

Pepsin-solubilized bovine corium collagen was purified, reconstituted, and treated with various levels of glutaraldehyde. Treatment of suspensions of fibrillar collagen with low concentrations of glutaraldehyde appeared to have little effect on the gross morphology of fibrils, as judged by electron microscopy, but did have a significant impact on their physicochemical stability. Fibrillar collagen treated with glutaraldehyde at a concentration equal to or greater than 0.0075% demonstrated significant decreases in neutral solubility at elevated temperatures as compared to noncross-linked controls. Differential scanning calorimetry provided a convenient and quantitative means to correlate increases in melting temperature with increases in glutaraldehyde treatment concentration. Fibrillar collagen cross-linked with glutaraldehyde concentrations as low as 0.0075% demonstrated a significantly greater resistance to proteolytic degradation than did noncross-linked fibrillar collagen samples. The residual, extractable aldehyde content of such preparations was between 1 and 3 ppm. Rheological measurements on such cross-linked suspensions demonstrated that they were non-Newtonian, shear-thinning fluids, and that they were two- to threefold more viscous than corresponding preparations of noncross-linked collagen.

Structural variability of collagen fibers in the calcareous axial rod of a sea pen.

Previous studies revealed that the organic matrix of the skeletal rod of the sea pen, Veretillum cynomorium, contained about 50% collagenous protein. The present ultrastructural study, based upon conventional staining methods, shows the existence of an abundant, longitudinally arranged nonbanded and fibrillar material separated by a reticular matrix. After incubation with 3 H-proline, labeling is specifically localized on the fibrillar material. Some fibers occasionally display a transverse striation with a period of 11 to 14 nm which can be associated with a chevron striation. Infrequently, some other fibers display a more distinct banding of 55 to 70 nm or even yield a checkerboard pattern. However, a majority of fibers remain without a regular structure comparable to the periodic striations observed in the collagen of other animals. After treatment with 1% PTA in 70% ethanol, all the fibers show a clear banding of 14 nm and some of them possess two types of striations. The same result is obtained on fibers mechanically dissociated and negatively stained. As these methods show a periodic banding pattern on all the fibers, it is likely that all the fibers (striated or not) observed after routine electron microscopy correspond to collagen material. This collagen appears to be both polymorphic and completely new in comparison to that which is characteristic of the mesoglea. The polymorphic aspect is compared to that obtained from vertebrate collagens.

ConA- and PNA-binding glycoproteins of human epidermis.

Concanavalia ensiformis agglutinin (ConA) and Arachis hypogaea agglutinin (PNA) binding glycoproteins in NP-40 extracts of human epidermis and epidermal cell preparations have been investigated by incubation of SDS-polyacrylamide gels with 125I-labeled lectins. In whole epidermis, 125I-ConA labels numerous glycoproteins, of which some appear to be restricted to the more differentiated upper layers of the epidermis and thus may represent markers of epidermal differentiation. These glycoproteins are not expressed by cells cultured on collagen. 125I-PNA labels a limited number of components, of which the major one is intercellular and/or extremely trypsin-sensitive. This material is expressed in low amounts after 13 days in culture.