Showing papers by "University of Erlangen-Nuremberg published in 1992"

Three-dimensional sensing of rough surfaces by coherence radar

Abstract: We introduce a three-dimensional sensor designed primarily for rough objects that supplies an accuracy that is limited only by the roughness of the object surface. This differs from conventional optical systems in which the depth accuracy is limited by the aperture. Consequently, our sensor supplies high accuracy with a small aperture, i.e., we can probe narrow crevices and holes. The sensor is based on a Michelson interferometer, with the rough object surface serving as one mirror. The small coherence length of the light source is used. While scanning the object in depth, one can detect the local occurrence of interference within the speckles emerging from the object. We call this method coherence radar.

Dynamic and static components of mechanical hyperalgesia in human hairy skin

Abstract: The principle finding of the present study is that there are two types of mechanical hyperalgesia developing in human hairy skin following injurious stimuli. Mechanical hyperalgesia comprises a dynamic component (brush-evoked pain, allodynia) signalled by large myelinated afferents and a static component (hyperalgesia to pressure stimuli) signalled by unmyelinated afferents. While the static component is only found in the injured area, the dynamic component also extends into a halo of undamaged tissue surrounding the injury. The irritant chemicals, mustard oil or capsaicin, were applied transdermally in 20 subjects to a patch (2 x 2 cm) of hairy skin. Both substances evoked burning pain and hyperalgesia to mechanical stimuli. While stroking normal skin with a cotton bud was perceived only as touch prior to chemical stimulation, there was a distinctly unpleasant sensation afterwards. This component of mechanical hyperalgesia persisted for at least 30 min and was present in the skin exposed to the irritants (primary hyperalgesia) as well as in a zone of untreated skin surrounding the injury (secondary hyperalgesia) measuring 38 +/- 4 cm2 after capsaicin. Pressure pain thresholds dropped to 55 +/- 8% of baseline level after mustard oil and to 46 +/- 9% after capsaicin. However, this drop of thresholds was short-lived, lasting 5 min following mustard oil but persisting more than 30 min following capsaicin treatment. The reduction of pressure pain thresholds was only observed for treated skin areas, but not in the surrounding undamaged tissue from where brush-evoked pain could be evoked. When pressure pain thresholds were lowered, the pain had a burning quality which differed distinctly from the quality of brush-evoked pain. On-going burning pain and both types of mechanical hyperalgesia were critically temperature dependent. Mildly cooling the skin provided instant relief from on-going pain, abolished brush-evoked pain and normalized pressure pain thresholds. Rewarming resulted in a reappearance of on-going pain and hyperalgesia. The effect of a nerve compression block of the superficial radial nerve on these sensations was tested in 14 experiments. When the ability to perceive light touch had been abolished, there was also no touch-evoked pain, indicating that this component of mechanical hyperalgesia is mediated by large-diameter primary afferents. At a later stage of the block when the subjects' ability to perceive cold stimuli had also been lost, application of cool stimuli still eliminated on-going burning pain, suggesting that pain relief afforded by cooling the skin acts at the peripheral receptor level and not by central masking.(ABSTRACT TRUNCATED AT 400 WORDS)

Protons selectively induce lasting excitation and sensitization to mechanical stimulation of nociceptors in rat skin, in vitro

Abstract: In ischemic and in inflamed tissues, pH levels down to 54 have been measured, and this local acidosis may contribute to pain and hyperalgesia in disease states To evaluate the role of acid pH in nociception, we have studied identified primary afferents in a rat skin-saphenous nerve preparation in vitro where the receptive fields can be superfused at the highly permeable corium side with controlled solutions The nerve endings were exposed to CO2-saturated synthetic interstitial fluid (SIF;pH 61) and to carbogen-gassed SIF phosphate buffered to different acid pH levels (5 min duration, 10 min intervals) Mechanical thresholds were repeatedly tested in a "blind" fashion by von Frey hair stimulation Low-threshold mechanosensitive A beta- (n = 12) and A delta-fibers (n = 11) were not excited or sensitized by acid pH levels In 24 of 96 nociceptor type C- and A delta-fibers, irregular low-frequency discharge with poor response characteristics was induced However, a distinct subpopulation of mechanoheat sensitive, "polymodal" C-units (n = 25; 38%) showed stimulus-related responses increasing with proton concentration and encoding the time course of the pH change Threshold levels were found to range from pH 69 to 61; mean maximum discharge was at pH 52 All such fibers responded to CO2 as well as to phosphate-buffered solution at the same pH 61 The CO2 responses, however, displayed significantly shorter latencies and more pronounced dynamic phases The carboanhydrase blocker acetazolamide markedly delayed and reduced the CO2 responses Prolonged application of acid pH (30 min) evoked nonadapting activity irrespective of oxygen supply Many, but certainly not all, fibers sensitive to protons were also driven by capsaicin (10(-6) M, 10(-5) M) and vice versa Repeated or prolonged treatment with low pH induced a significant and lasting decrease of the mechanical (von Frey) thresholds in almost all C-fibers tested (from 35 to 16 mN, on average), and this occurred whether or not a fiber was excited by protons The sensitizing effect was more pronounced the higher the initial von Frey thresholds (075 rank correlation) This sensitization to mechanical stimulation was in contrast to the combined action of other inflammatory mediators, bradykinin, 5-HT, histamine and prostaglandin E2 In conclusion, we suggest that pH sensitivity of nociceptors may be an important source of pain and hyperalgesia

Primary structure of the herpesvirus saimiri genome.

Abstract: This report describes the complete nucleotide sequence of the genome of herpesvirus saimiri, the prototype of gammaherpesvirus subgroup 2 (rhadinoviruses). The unique low-G + C-content DNA region has 112,930 bp with an average base composition of 34.5% G + C and is flanked by about 35 noncoding high-G + C-content DNA repeats of 1,444 bp (70.8% G + C) in tandem orientation. We identified 76 major open reading frames and a set of seven U-RNA genes for a total of 83 potential genes. The genes are closely arranged, with only a few regions of sizable noncoding sequences. For 60 of the predicted proteins, homologous sequences are found in other herpesviruses. Genes conserved between herpesvirus saimiri and Epstein-Barr virus (gammaherpesvirus subgroup 1) show that their genomes are generally collinear, although conserved gene blocks are separated by unique genes that appear to determine the particular phenotype of these viruses. Several deduced protein sequences of herpesvirus saimiri without counterparts in most of the other sequenced herpesviruses exhibited significant homology with cellular proteins of known function. These include thymidylate synthase, dihydrofolate reductase, complement control proteins, the cell surface antigen CD59, cyclins, and G protein-coupled receptors. Searching for functional protein motifs revealed that the virus may encode a cytosine-specific methylase and a tyrosine-specific protein kinase. Several herpesvirus saimiri genes are potential candidates to cooperate with the gene for saimiri transformation-associated protein of subgroup A (STP-A) in T-lymphocyte growth stimulation.

Role of octreotide in the prevention of postoperative complications following pancreatic resection.

Abstract: Though morbidity and mortality rates following pancreatic resection have improved in recent years, they are still around 35% and 5%, respectively. Typical complications, such as pancreatic fistula, abscess, and subsequent sepsis, are chiefly associated with exocrine pancreatic secretion. In order to clarify whether the perioperative inhibition of exocrine pancreatic secretion prevents complications, we assessed the efficacy of octreotide, a long-acting somatostatin analogue. We conducted a randomized, double-blind, placebo-controlled, multicenter trial in 246 patients undergoing major elective pancreatic surgery. Patients were stratified into a high-risk stratum (limited to patients with pancreatic and periampullary tumors) or low-risk stratum (patients with chronic pancreatitis). Patients received octreotide (3 x 100 micrograms) or placebo subcutaneously for 7 days perioperatively. Eleven complications were defined: death, leakage of anastomosis, pancreatic fistula, abscess, fluid collection, shock, sepsis, bleeding, pulmonary insufficiency, renal insufficiency, and postoperative pancreatitis. Two hundred patients underwent pancreatic head resection, 31 patients underwent left resection, and 15 patients had other procedures. The overall mortality rate within 90 days was 4.5%, with 3.2% in the octreotide group and 5.8% in the placebo group. The complication rate was 32% in the patients receiving octreotide (40 of 125 patients) and 55% in patients receiving placebo (67 of 121 patients) (p less than 0.005). In the patients in the high-risk stratum, complications were observed in 26 of the 68 (38%) patients treated with octreotide and in 46 of 71 (65%) patients given placebo (p less than 0.01). Whereas in patients in the low-risk stratum, the complication rate was 25% (14 of 57 patients) in those treated with octreotide and 42% (21 of 50 patients) in patients given placebo (p = NS). The perioperative application of octreotide reduces the occurrence of typical postoperative complications after pancreatic resection, particularly in patients with tumors.

Pseudoexfoliation syndrome, ocular manifestation of a systemic disorder?

Abstract: The pseudoexfoliation syndrome has recently been suggested to represent the local manifestation of a more widespread disorder. In this study, a case of classic bilateral pseudoexfoliation syndrome with systemic distribution of pseudoexfoliation material involving a variety of organ systems is described. Using transmission electron microscopy, typical pseudoexfoliation fibers were identified in autopsy tissue specimens of skin, heart, lungs, liver, kidney, and cerebral meninges in addition to the classic intraocular locations. The pseudoexfoliation material was mainly localized to connective-tissue portions or septa traversing the various organs. The pseudoexfoliation fibers were consistently associated with connective-tissue components, particularly fibroblasts and collagen and elastic fibers; myocardial tissue specimens; and heart-muscle cells. These findings provide evidence for the systemic nature of the pseudoexfoliation syndrome, which apparently involves an aberrant connective-tissue metabolism throughout the body.

Role of human T-cell leukemia virus type 1 X region proteins in immortalization of primary human lymphocytes in culture.

Abstract: Human T-cell leukemia virus type 1 (HTLV-1) immortalizes human CD4+ T lymphocytes in culture. Previous studies show that in the context of a herpesvirus saimiri vector, the sequence of the X region at the 3' end of the HTLV-1 genome is also capable of immortalizing CD4+ lymphocytes in the absence of HTLV-1 structural proteins. The X region of HTLV-1 encodes two trans-acting viral proteins, the 42-kDa Tax protein and the 27-kDa Rex protein. Infection of human cord blood cells with herpesvirus saimiri recombinants which contain HTLV-1 X region sequences defective for expression of tax, rex, or both tax and rex demonstrates that tax function is necessary and sufficient for immortalization of primary human CD4+ cord blood lymphocytes in culture in the context of the herpesvirus saimiri vector.

Stable growth transformation of human T lymphocytes by herpesvirus saimiri.

Abstract: Herpesvirus saimiri induces T-cell lymphomas in various species of New World monkeys and in rabbits, and it is able to immortalize monkey T lymphocytes in vitro. Sequences responsible for these effects have been localized to a region of the genome that varies significantly among the virus subgroups A, B, and C. We now report that infection of human blood lymphocytes and thymocytes with strains of subgroup C, in contrast to viruses of the other subgroups, yields continuously proliferating T-cell lines with the phenotype of mature CD4- or CD8-positive cells. Infection with strains of Herpes-virus saimiri subgroup C can thus be used to generate human T-cell lines for a variety of immunological and developmental studies.

Cloning of TRAP, a ligand for CD40 on human T cells

Abstract: A cDNA clone, designated TRAP (TNF-related activation protein) was isolated from a collection of T cell activation genes. The polypeptide encoded by a mRNA of approx. 2.3 kb is 261 amino acids long with a calculated M(r) of 29.3 kDa. The structural features predict a type II transmembrane protein, but are also compatible with a secreted form. TRAP is highly similar to an identified murine CD40 ligand both at the cDNA (82.8% identity) and the protein (77.4% identity) levels, and related to tumor necrosis factor/lymphotoxin. Expressed in a murine myeloma, TRAP was identified as a ligand for CD40 by binding to a soluble CD40 construct. TRAP mRNA is expressed in a T cell-specific fashion with a maximum at 8 h after stimulation. The TRAP gene is located in the q26.3-q27.1 region of the X chromosome.

Responsiveness and functional attributes of electrically localized terminals of cutaneous C-fibers in vivo and in vitro

Abstract: 1. The purpose of the present study was to compare the responsiveness unmyelinated cutaneous units in vivo and in vitro and to determine the proportion of primary afferents innervating the rat hairy skin that do not respond to transient mechanical or thermal stimuli. We have adopted electrical search strategies to locate the terminal arborization of unmyelinated fibers before testing the sensitivity to adequate stimuli. 2. A total of 144 unmyelinated units were studied, of which 31 were obtained from in vivo and 113 from in vitro experiments. 55 afferents were investigated after chronic surgical sympathectomy. Units recorded from sympathectomized rats did not differ in their conduction velocity, electrical thresholds, or receptive properties from units in intact animals. 3. There were only minor differences between the properties of units recorded in vivo and in vitro. This probably reflects technical differences of the setups rather than biological changes introduced by the in vitro conditions. Except for a higher prevalence of mechano-cold sensitive units in vitro, there was no significant difference between the distributions of receptor types. 4. Eight of 31 units (26%) recorded in vivo and 17 of 113 units (15%) obtained from in vitro experiments failed to respond to transient mechanical or thermal stimuli. In vivo, one of eight initially unresponsive units was activated by repeated mechanical and thermal stimulation. Two further units became responsive after topical application of mustard oil. In vitro, 2 of 17 unresponsive units were activated by repeated stimulation. Ten of the remaining unresponsive units were treated with a combination of inflammatory mediators. Four of these units were activated: three developed ongoing activity, and two of them also became responsive to mechanical and/or heat stimuli. The fourth unit responded to probing but was not spontaneously active. 5. We conclude that transient mechanical or thermal stimuli can excite the majority of unmyelinated cutaneous units. However, in vivo and in vitro, part of unmyelinated units are initially unresponsive even to noxious forms of stimulation. Because those unresponsive units were also encountered in sympathectomized preparations, and because some units can be recruited with repeated noxious stimuli or inflammatory agents, it is unlikely that all of them are sympathetic efferents. The same substances that cause sensitization of "normal" nociceptors are capable of recruiting initially unresponsive unmyelinated afferents.

Results of endoscopic sinus surgery for the treatment of inverted papillomas.

Abstract: Fifty-one patients suffering from inverted papillomas of the nose and paranasal sinuses were reexamined in a retrospective study. Thirty-five had undergone surgery by an intranasal endoscopic approach and 16 had undergone surgery by an extranasal approach. The recurrence rate following endoscopic interventions was 17% (6/35), as compared to 19% (3/16) after extranasal operations. Endoscopic surgery proved to be successful even in the treatment of large lesions affecting the posterior ethmoidal sinus, the nasofrontal duct, or the sphenoidal sinus. Its indication thus no longer needs to be restricted to limited lesions of the anterior nasal cavity. Patients with inverted papillomas will benefit from this surgical technique which remains minimally invasive and thus retains the paranasal bony framework, preserves unaffected mucosa capable of recovery, and prevents damage to the patients' cosmetic features.

Count and density of human retinal photoreceptors.

Abstract: This investigation was directed at determining the count and regional distribution of photoreceptors in the eyes of 21 human cornea donors aged between 2 and 90 years. Mean count of rods was 60 123 000 ±12907000, and mean cone count was 3173000 ± 555000. Determined 40 μm away from the foveola, cone density measured 125 500 cones/mm2. Extrapolating the distribution curve, cone concentration in the foveal center can be assumed to be about 150 000 cells/mm2 to 180 000 cones/mm2. Towards the retinal periphery, cone density decreased from 6000 cones/mm2 at a distance of 1.5 mm from the fovea to 2500 cells/mm2 close to the ora serrata. Comparing different fundus regions, cone concentration was significantly highest in the nasal region. Cone diameter increased from the center towards the periphery. At a distance of 40 μm away from the foveola, it measured about 3.3 μm, and in the outer retinal regions about 10 μm Rod density was highest in a ring-like area at a distance of about 3–5 mm from the foveola with a mean of 72 246 ± 17 295 cells/mm2. Rod density peaked at 150 000 rods/mm2. It decreased towards the retinal periphery to 30 000–40 000 rods/mm2. Rod diameter increased from 3 μm at the area with the highest rod density to 5.5 μm in the periphery. The hexagonal rod and cone inner segments were regularly arranged in a honey-comb fashion.

Glaucomatous parapapillary atrophy. Occurrence and correlations.

Abstract: Glaucomatous optic nerve damage is typically associated with intrapapillary changes, such as neuroretinal rim loss. In this study, parapapillary chorioretinal atrophy was evaluated in 691 normal eyes, 1081 glaucomatous eyes, and 31 eyes with ocular hypertension. It was significantly larger and occurred more often in the glaucomatous eyes (parapapillary atrophy area, 1.07 +/- 0.83 mm2) (mean +/- SD) than in the normal eyes (0.55 +/- 0.64 mm2) or in the eyes with ocular hypertension (0.55 +/- 0.37 mm2). These differences were significant also for eyes with moderate glaucomatous damage (0.86 +/- 0.62 mm2). Parapapillary chorioretinal atrophy was associated with shallow glaucomatous cupping, diffuse nerve fiber loss, a marked tessellated fundus, and only moderately elevated intraocular pressure. It increased with a decreasing neuroretinal rim area. It showed a spatial correlation to neuroretinal rim loss inside the optic disc. In unilateral glaucoma, it was larger in the affected eye than in the unaffected eye. Parapapillary chorioretinal atrophy is associated with glaucoma.

The role of the crabtree effect and an endogenous fuel in the energy metabolism of resting and proliferating thymocytes

Abstract: Rat thymocytes have been used to characterize the changes in energy metabolism that occur as cells undergo a resting/proliferation transition. In the resting state, anaerobic ATP production accounts for only 4% of ATP turnover. The remainder is fueled by the oxidation of a mixture of an unidentified endogenous fuel (62%), glucose (18%) and glutamine (16%). 48 h after mitogen stimulation, the ATP turnover has increased twofold. In these proliferating cells, glucose inhibits oxygen consumption by 58%, indicating a profound Crabtree effect which is not present in resting cells. Consequently, proliferating cells, in the presence of glucose and glutamine, fuel the majority (61%) of ATP turnover anaerobically, producing lactate from glucose. The development of a Crabtree effect may be the result of the 8-10-fold increase in glycolytic enzyme activities which occurs with proliferation. Possible advantages of such a proliferative metabolism are a sparing of endogenous fuel, and a minimizing of oxidative metabolism, with its concurrent production of free radicals.

Neural networks for solving systems of linear equations and related problems

Abstract: Various circuit architectures of simple neuron-like analog processors are considered for online solving of a system of linear equations with real constant and/or time-variable coefficients. The proposed circuit structures can be used, after slight modifications, in related problems, namely, inversion and pseudo-inversion of matrices and for solving linear and quadratic programming problems. Various ordinary differential equation formulation schemes (generally nonlinear) and corresponding circuit architectures are investigated to find which are best suited for VLSI implementations. Special emphasis is given to ill-conditioned problems. The properties and performance of the proposed circuit structures are investigated by extensive computer simulations. >

Spectral Theory, Zeta Functions and the Distribution of Periodic Points for Collet-Eckmann Maps

Abstract: We study unimodal interval mapsT with negative Schwarzian derivative satisfying the Collet-Eckmann condition |DTn(Tc)|≧Kλcn for some constantsK>0 and λc>1 (c is the critical point ofT). We prove exponential mixing properties of the unique invariant probability density ofT, describe the long term behaviour of typical (in the sense of Lebesgue measure) trajectories by Central Limit and Large Deviations Theorems for partial sum processes of the form\(S_n = \Sigma _{i = 0}^{n - 1} f(T^i x)\), and study the distribution of “typical” periodic orbits, also in the sense of a Central Limit Theorem and a Large Deviations Theorem.

Excitation of cutaneous afferent nerve endings in vitro by a combination of inflammatory mediators and conditioning effect of substance P.

Abstract: A broad mixture of inflammatory mediators ("inflammatory soup") was used to investigate the responsiveness of primary afferents from rat hairy skin in an in vitro skin-saphenous nerve preparation. In addition, a conditioning effect of the tachykinin substance P on chemosensitivity of nociceptors was examined. Inflammatory soup (IS) was made up in synthetic interstitial fluid from bradykinin, serotonin, histamin and prostaglandin E2 (all 10(-5) M). In addition, the potassium and the hydrogen ion concentration (7 mM, pH 7.0) and the temperature (39.5 degrees C) were elevated. The latter agents, in a control solution, did not excite nociceptors (n = 5). IS was repeatedly superfused over the receptive fields for 5 min at 10 min intervals; substance P (SP 10(-6) and 10(-5) M) was applied during the last 5 min of the interval and during the subsequent IS stimulation. IS excited more than 80% of the mechano-heat sensitive ("polymodal") afferents with slowly conducting nerve fibres (n = 72), but none of the low-threshold mechanoreceptive slow and fast conducting units (n = 17). Slow conducting afferents with high mechanical threshold (n = 35) were weakly, and less frequently (< 20%), driven by IS. A majority, but not all, of the responsive units showed tachyphylaxis upon repeated IS application. None, however, lost its responsiveness completely. Conditioning heat stimulation (32-46.5 degrees C in 20 s) did not enhance the subsequent IS response, which may indicate that sensitizing substances normally released by a noxious heat stimulus were already contained in IS. No sensitization to mechanical (von Frey) or heat stimulation could be established in the period after the IS response had subsided and after the washout was completed, respectively. A short-lived sensitization may have been overlooked under these temporal restrictions. Conditioning SP in 10(-5) M but not in 10(-6) M concentration significantly increased the IS response of polymodal C fibres, by 58% on average (n = 14). SP did not excite the units. Comparing with previous data, we conclude that there is a significant synergism between inflammatory mediators, acting to induce more intense and more sustained discharge via many nociceptors than single mediators alone could achieve. Conditioning substance P can further enhance this algogenic action. Mechanisms of interaction and relative contributions of single substances remain to be elucidated.

New aspects of the mixed state from six-terminal measurements on Bi2Sr2CaCu2Ox single crystals.

Abstract: We attached two current and two voltage contacts on both sides of ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{\mathit{x}}$ single crystals and performed transport measurements applying the current parallel to the ${\mathrm{CuO}}_{2}$ layers. In the Ohmic regime, the voltage signal on the side of the current contacts was more than a factor of 100 larger than at the opposite side. The results are interpreted within an anisotropic resistivity model to obtain the true resistivities ${\mathrm{\ensuremath{\rho}}}_{\mathit{a}\mathit{b}}$(B,T) and ${\mathrm{\ensuremath{\rho}}}_{\mathit{c}}$(B,T). A model is presented based on the movement of pancake vortices involving vortex shear, vortex cutting, and generation of Josephson vortices between the layers.

Ictal and interictal activity in partial epilepsy recorded with multichannel magnetoelectroencephalography: correlation of electroencephalography/electrocorticography, magnetic resonance imaging, single photon emission computed tomography, and positron emission tomography findings.

Abstract: Ictal and interictal epileptic activity was recorded for the first time by multichannel magnetoencephalography (MEG) in three patients with partial epilepsy. Pre- and intra-operative localization of the epileptogenic region was compared. The interictal epileptic activity was localized at the same region of the temporal or frontal lobe as the ictal activity. Main zones of ictal activity were shown to evolve from the tissue at the centers of interictal activity. Pre- and intra-operative electrocorticography (ECoG) as well as postoperative outcome confirmed localization in the temporal and frontal lobe. Results also correlated with findings from scalp EEG, interictal and ictal single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI). Combined multichannel MEG/EEG recording permitted dipole localization of interictal and ictal activity.

Activation of collagen type II expression in osteoarthritic and rheumatoid cartilage.

Abstract: In situ hybridization and immunohistochemical techniques were applied to investigate gene expression and extracellular deposition of collagen type II in normal, osteoarthritic and rheumatoid human articular cartilage. Normal cartilage showed an essentially even extracellular distribution of type II collagen with polyand monoclonal antibodies, while only a few cells were positive for al(II) collagen mRNA. In situ hybridization of osteoarthritic and rheumatoid cartilage, however, showed strong enhancement of type II collagen gene expression; transcripts were observed predominantly in the upper middle zone of the articular cartilage while the upper layer was mostly negative and correlated with a zone of reduced proteoglycan staining. The elvated mRNA levels frequently coincided with pericellular immunostaining ] for type II collagen, indicative for enhanced synthesis of the protein. In two samples, however, pericellular loss of collagen type II staining was found despite positive cytoplasmic signals with the α 1(11) RNA probe, suggesting enhanced collagen destruction. Control hybridization with a probe for 18S rRNA revealed very few negative cells throughout both normal and arthritic cartilage samples, ruling out major cell necrosis in the specimens investigated. Thus, our observations identify sites of activated type II collagen synthesis in osteoarthritic cartilage that were predicted by previous biochemical studies and support the notion that damaged cartilage attempts to restore matrix by enhanced synthesis of its components.

Adsorptive voltammetric procedure for the determination of platinum baseline levels in human body fluids

Abstract: An extremly sensitive procedure for the determination of platinum in human body fluids is presented. A high pressure decomposition of the samples is followed by adsorptive voltammetric measurement. A detection limit down to 0.2 ng Pt/l sample allowed baseline levels of platinum in body fluids (urine: 0.5–15 ng/l, blood and blood plasma: ≤0.8–6.9 ng/l) to be evaluated. The concentration ranges in body fluids of occupationally exposed people were determined to 21–2900 ng/l (urine), 32–180 ng/l (blood) and 95–280 ng/l (blood plasma).

Gold and Platinum Diffusion: The Key to the Understanding of Intrinsic Point Defect Behavior in Silicon

Abstract: The study of gold and platinum diffusion is found to allow the separate observation of the intrinsic point defects, i.e., of silicon self-interstitials and of vacancies. The diffusion of gold in float zone (FZ) silicon is found to be dominated by the kick-out mechanism for temperatures of 800° C and higher. The diffusion of platinum in FZ silicon is described by the kick-out mechanism for temperatures above approximately 900° C, whereas for temperatures below approximately 850° C the dissociative mechanism governs platinum diffusion. As a result of numerical simulations, we suggest a complete and consistent set of parameters which describes the diffusion of platinum in silicon in the temperature range from 700° C to 950° C and the diffusion of gold in the temperature range from 800° C to 1100° C. The generation or recombination of self-interstitials and vacancies is found to be ineffective at least below 850° C. The concentration of substitutional platinum is determined by the initial concentration of vacancies at diffusion temperatures below 850° C. Platinum diffusion below 850°C can be used to measure vacancy distributions in silicon quantitatively.

The structure of pneumococcal lipoteichoic acid. Improved preparation, chemical and mass spectrometric studies.

Abstract: Pneumococcal lipoteichoic acid was extracted and purified by a novel, quick and effective procedure. Structural analysis included methylation, periodate oxidation, Smith degradation, oxidation with CrO3, and fast-atom-bombardment mass spectrometry. Hydrolysis with 48% (by mass) HF and subsequent phase partition yielded the lipid anchor (I), the dephosphorylated repeating unit of the chain (II) and a cleavage product of the latter (III). The proposed structures are: (I) Glc(beta 1----3)AATGal(beta 1----3)Glc(alpha 1----3)acyl2Gro, (II) Glc(beta 1----3)AATGal(alpha 1----4)GalNAc(alpha 1----3)GalNAc(beta 1----1)ribitol and (III) Glc(beta 1----3)AATGal(alpha 1----4)GalNAc(alpha 1----3)GalNAc, where AATGal is 2-acetamido-4-amino-2,4,6-trideoxygalactose, and all sugars are in the pyranose form and belong to the D-series. Alkaline phosphodiester cleavage of lipoteichoic acid, followed by treatment with phosphomonoesterase, resulted in the formation of II and IV, with IV as the prevailing species: [sequence: see text] The linkage between the repeating units was established as phosphodiester bond between ribitol 5-phosphate and position 6 of the glucosyl residue of adjacent units. The chain was shown to be linked to the lipid anchor by a phosphodiester between its ribitol 5-phosphate terminus and position 6 of the non-reducing glucosyl terminus of I. The lipoteichoic acid is polydisperse: the chain length may vary between 2 and 8 repeating units and variations were also observed for the fatty acid composition of the diacylglycerol moiety. Preliminary results suggest that repeating units II and IV are enriched in separate molecular species. All species were associated with Forssman antigenicity, albeit to a various extent when related to the non-phosphocholine phosphorus. Owing to its unique structure, the described macroamphiphile may be classified as atypical lipoteichoic acid.