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B Decker

Publications and source records attributed to B Decker.

At least 19 recordsLinked to original sources
PubMed2004

Large-scale homogeneous molecular templates for femtosecond time-resolved studies of the guest-host interaction.

Self-assembled monolayer films based on iodobenzoyloxy-functionalized resorc[4]arenes were prepared on gold substrates to serve as model systems for future time-resolved studies of molecular recognition, a mechanism of outstanding importance in bioorganic systems. The film properties were tested using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and imaging ellipsometry. An apparatus for time-resolved electron spectroscopy utilizing femtosecond soft X-ray pulses is capable of detecting iodine core-level photolines and the photoinduced dissociation after ultraviolet illumination. The developed technique holds promise for tracking the temporal evolution of chemical shifts of atomic markers as local probes for the dynamics of the guest-host interaction.

Benzoates↗
PubMed1998

Localization of carbonic anhydrase IV in rat and human heart muscle.

We investigated carbonic anhydrase IV (CA IV) in rat and human heart with immunohistochemical methods by both light and electron microscopy. In cryosections that were incubated with anti-CA IV/FITC, the capillaries showed a strong reaction for CA IV. In paraffin and semithin sections treated with anti-CA IV/ABC (avidin-biotin-peroxidase complex) blood vessels, capillaries, and sarcolemma (SL) were positively stained. By staining ultrathin sections with anti-CA IV/immunogold, CA IV could also be demonstrated at the latter two locations, including the specialized sarcolemmal structures intercalated discs, and T-tubules. In addition, by this method CA IV was seen to be associated with the sarcoplasmic reticulum (SR). The absence of immunostaining in SR and/or SL with some techniques probably indicates a problem of accessibility of the antigenic sites. In line with the immunohistochemical results, CA IV mRNA expression was visualized in both endothelial and muscle cells by in situ hybridization histochemistry.

Animals↗
PubMed1997

Action of FMRFamide-like peptides on porcine gastrointestinal motility in vitro.

Mechanical activity was recorded in circular and longitudinal smooth muscle preparations isolated from extensive regions of the porcine gastrointestinal tract in response to the FMRFamide-like neuropeptides F8Famide and A18Famide. In all preparations, the peptides were about equipotent in producing phasic contractions or enhancing spontaneous activity. The most prominent responses were observed in jejunal longitudinal strips which were on the average 91% (+/- 4% SEM, n = 15; 10(-6) M) of the histamine (10(-5) M) responses. The peptide-induced phasic activity was completely abolished by nifedipine but was unaffected by tetrodotoxin, atropine, phentolamine, yohimbine, phenoxybenzamine, propranolol, methysergide, cimetidine, indomethacin, levallorphane or naloxone. Both peptides enhanced acetylcholine-induced contractions. However, bovine ileum and guinea-pig taenia coli was not affected by these peptides. The results indicate that F8F- and A18F-amide contract porcine gastrointestinal smooth muscle by acting directly via non-opioid receptors on L-type calcium channels. In addition an increase of the sensitivity to cholinergic stimulation occurs.

Animals↗
PubMed1996

The morphological effects of synthetic augmentation in posterior cruciate ligament reconstruction: an experimental study in a sheep model.

The treatment of posterior cruciate ligament (PCL) injuries remains controversial. Due to various problems, PCL reconstruction has not consistently produced the knee stability desired. Biological graft tissue undergoes a remarkable healing process comprising different phases. The strength of autogenous graft material decreases soon after operation. During this early healing phase synthetic augmentation could protect the graft tissue from overloading or overstretching, supporting the tissue revitalization and remodeling process. In order to evaluate the morphological effects of the ligament augmentation device (LAD) on a free patellar tendon autograft in PCL reconstruction, a comparative study in sheep was conducted. In 24 mature sheep, the PCL was replaced with either a patellar tendon autograft alone or a patellar tendon autograft augmented by the LAD. The LAD was fixed at both ends. After the operation the animals were not immobilized. Tibial fixation was released 8 weeks postoperation. The autografts of both groups were histologically evaluated after 2, 6, 16, 26, 52, and 104 weeks. In addition to necrotic and degenerative alterations, a remarkable inflammatory reaction could be seen in the LAD-augmented autografts early postoperation. Compared with the nonaugmented autografts, tissue formation and remodeling were delayed in the augmented group. After 1 and 2 years, the morphology of the autograft tissue was similar in both the augmented and nonaugmented group and differed from that of a normal PCL. The LAD was surrounded by a chronic inflammatory reaction, and collagen fiber ingrowth into the LAD was not observed. Using transmission electron microscopy, small diameter collagen fibrils were predominant in the graft tissue of both groups. Thus, a better remodeling of the autograft tissue in the presence of the LAD could not be demonstrated in this particular study. The value of synthetic augmentation of biological grafts in PCL reconstruction seems to be questionable at present.

Animals↗
PubMed1996

Membrane-associated carbonic anhydrase IV in skeletal muscle: subcellular localization.

Carbonic anhydrase IV (CA IV) was examined by light microscopy and electron microscopy in rat soleus muscle. Semithin sections of aldehyde-fixed Epon-embedded muscle were stained with rabbit anti-rat lung CA IV and the avidin-biotin-peroxidase complex. With this technique, capillaries and sarcolemma showed positive CA IV staining. For electron microscopy, rat soleus specimens were aldehyde-fixed, with or without subsequent osmication, and embedded in Epon. Ultrathin sections were immunostained with anti-rat lung CA IV/immunogold. Omitting osmium allowed ample antigen-antibody reactions but could not prevent the release of glycosylphosphatidylinositol-anchored CA IV from the membranes, which led to apparent background staining. Postosmication significantly reduced tissue antigenicity but kept the antigen bound to the membranes and thus allowed a very precise localization of CA IV. By electron microscopy, membrane-bound CA IV is found to be associated with capillary endothelium, sarcolemma, and sarcoplasmic reticulum (SR). Conceivably, the presence of SR staining in ultrathin sections and its absence in semithin sections reflect a problem of accessibility of the antigenic sites.

Animals↗
PubMed1996

[Morphologic aspects of alloplastic augmentation in replacement of the posterior cruciate ligament. An experimental study on the sheep].

The treatment of injuries to the posterior cruciate ligament (PCL) remains controversial. Various problems have prevented PCL reconstruction from consistently producing the knee stability desired. Biological graft tissue undergoes a remarkable healing process comprising different phases. The strength of autogenous graft material decreases soon after the operation. During this early healing phase synthetic augmentation could protect the graft tissue from overloading or overstretching, supporting the tissue restoration process. In order to evaluate the morphological effects of the ligament augmentation device (LAD) on a free patellar tendon autograft in PCL reconstruction a comparative study in sheep was conducted. In 24 mature sheep the PCL was replaced with either a patellar tendon autograft alone or a patellar tendon autograft augmented by the LAD. The LAD was fixed at both ends. The animals were not immobilized after the operation. Tibial fixation was released 8 weeks after the operation. The autografts of both groups were histologically evaluated after 2, 6, 16, 26, 52 and 104 weeks. In addition to necrotic and degenerative alterations a pronounced inflammatory reaction could be seen in the LAD-augmented autografts soon after the operation. Compared with the non-augmented autograft, tissue formation and remodeling was delayed in the augmented group. After 1 and 2 years, the morphology of the autograft tissue was similar in the augmented and the non-augmented group and was different from that of a normal PCL. The LAD was surrounded by a chronic inflammatory reaction, and collagen fiber ingrowth into the LAD was not observed. Transmission electron microscopy showed that small-diameter collagen fibrils were predominant in the graft tissue of both groups. Thus, better remodeling of the autograft tissue in the presence of the LAD was not demonstrable in this particular study. The value of synthetic augmentation of biological grafts of PCL reconstruction seems to be questionable at present.

Animals↗
PubMed1995

Relationships between endothelial cells, pericytes, and osteoblasts during bone formation in the sheep femur following implantation of tricalciumphosphate-ceramic.

BACKGROUND: The origin of osteoblasts is still controversial. Whereas several authors consider the stromal fibroblast of the bone marrow as the osteoprogenitor cell, others propose that the osteoblasts can be derived from the "capillary system." The present study examines the replacement of tricalciumphosphate (TCP)-ceramic implanted into an artificial bone defect by newly formed bone. The results support the hypothesis that osteogenic cells can be derived from invading blood vessels. METHODS: The spongiosa of the trochanter major of sheep was removed and the defect was filled with TCP-ceramic. Two months after surgery the ceramic implants together with the surrounding bone were removed and processed for transmission electron microscopy. Serial ultrathin sections of three newly formed osteons were examined. RESULTS: The osteons contain one or two small sprouting capillaries, a peripheral layer of osteoblasts, and in between, a network of glycogen-rich cells. Some of the glycogen-rich cells are completely or partly surrounded by the endothelial basal lamina and are thereby characterized as pericytes. Weibel-Palade bodies, which are considered to be a marker of endothelial cells, were occasionally observed in glycogen-rich pericytes. CONCLUSIONS: Since pericytes differentiate into osteoblasts under in vivo and in vitro conditions, and have thus been regarded as osteoprogenitor cells, the presence of Weibel-Palade bodies in these cells suggest that osteogenic cells can be derived from endothelial cells.

Animals↗
PubMed1995

Collagen fibril diameter distribution in patellar tendon autografts after posterior cruciate ligament reconstruction in sheep: changes over time.

The alterations in collagen fibril diameter distribution, mean fibril diameter and the area occupied by collagen after posterior cruciate ligament reconstruction using a patellar tendon autograft were estimated 2, 6, 16, 26, 52 and 104 wk postoperatively. Patellar tendons and posterior cruciate ligaments from unoperated animals were used as control tissues. Collagen fibrils were divided into histograms according to their diameter in order to analyse distribution maxima. There was a significant decrease in mean fibril diameter of the grafts in comparison with the control tissues. At 104 wk it was only about 51% of that for control posterior cruciate ligaments. The total area occupied by collagen was significantly reduced at 6 wk postoperatively and was about 57% in comparison with normal posterior cruciate ligaments. A considerable increase of small diameter collagen fibrils together with a loss of large fibrils was responsible for these results. There was no evidence of reestablishment of large diameter fibrils, which are normally found in tendon and ligaments, up to 2 y after transplantation. The total area covered by collagen was still reduced at this stage although the number of fibrils had increased.

Animals↗
PubMed1994

Changes in the extracellular matrix of the autogenous patellar tendon graft after posterior cruciate ligament reconstruction: a biochemical study in sheep.

The left knee joints of female German sheep were operated, replacing the posterior cruciate ligament by the central third of the patellar tendon. After 2, 6, 16, 26 and 52 weeks the graft of the operated leg as well as the contralateral central third of the patellar tendon and the posterior cruciate ligament were dissected and used for biochemical analysis. The total glycosaminoglycan content in grafts increases within the first year up to 5 fold and is higher than that of the patellar tendon, but is lower than that of the cruciate ligament. The distribution pattern of glycosaminoglycans differ in the posterior cruciate ligament and the patellar tendon. In cruciate ligament the main components are chondroitin sulfate (76%) and hyaluronan (15%). In the patellar tendon a higher portion of dermatan sulfate (approx. 16%) was found, next to 52% chondroitin sulfate and 22% hyaluronan. During the examination time the grafts show changes in the concentration and the distribution pattern of glycosaminoglycans. The chondroitin sulfate content increases during the experimental period from 1.4 +/- 1.2 mumol/g dry weight (d.w.) to 8.7 +/- 2.9 mumol/g d.w. After 1 year the chondroitin sulfate content in the graft does not differ significantly from that of the cruciate ligament. In the grafts the concentration of chondroitin (non sulfated) increases after 6 weeks up to 1.3 +/- 0.6 mumol/g d.w. in comparison to the value after 2 weeks (0.2 +/- 0.1 mumol/g d.w.) and also in the other groups (16, 26 and 52 weeks) it remains significantly increased. After 1 year the dermatan sulfate content in the graft has increased up to the fifth-fold compared to the value after 2 weeks and is higher than in the patellar tendon and in the cruciate ligament. In graft the hyaluronan content (1.0 +/- 0.4 mumol/g d.w. does not differ significantly in the groups 2, 6, 16, 26 and 52 weeks after operation, but in all five groups it is lower than in the cruciate ligament (2.4 +/- 1.0 mumol/g d.w.). Dermatan and heparan sulfate are not or only little detected in all three tissues. The distribution pattern of glycosaminoglycans in graft shows chondroitin sulfate and dermatan sulfate being the major parts of glycosaminoglycans with a slight increase of these components in the different groups during the experimental period. Hyaluronan makes up to 24 +/- 5% of the whole content of glycosaminoglycans after 2 weeks and decrease to 8 +/- 1% after 52 weeks.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Histochemical aspects of the proteoglycans of patellar tendon autografts used to replace the posterior cruciate ligament.

In the female German black-faced sheep the posterior cruciate ligament was replaced by a free patellar tendon autograft and after 2, 6, 16, 26 and 52 weeks tissue samples of the graft's center (axial region far from bones) were removed for histochemistry and electron microscopy. To localize the proteoglycans Alcian Blue and 0.3 M MgCl2 were added to the fixative solution. The distribution of the proteoglycans in the graft was compared to that of a normal patellar tendon and of a normal posterior cruciate ligament. In the patellar tendon spindle-shaped cells predominated and proteoglycans appeared as short filaments at regular intervals between the collagen fibrils. In the posterior cruciate ligament chondroid cells and long filaments in a net-work-like arrangement were seen. In the patellar tendon autografts short interfibrillar filaments prevailed after 2, 6 and 16 weeks. After 26 weeks and particularly after 52 weeks long filaments also appeared. Digestion with Chondroitinase ABC, AC and Hyaluronidase suggested that the short filaments were PGs containing dermatan sulfate. In grafts, in the early phases the fibroblasts predominated, while in the late phases mainly chondroid cells were observed. The grafts showed aspects of the normal posterior cruciate ligament. However, differences remained, for example the thin collagen fibrils, which could represent one of the reasons for a secondary graft failure.

Actin Cytoskeleton↗
PubMed1992

The relationship of mechanical properties to morphology in patellar tendon autografts after posterior cruciate ligament replacement in sheep.

In a sheep model the posterior cruciate ligament (PCL) was replaced by a patellar tendon autograft (PTAG) using the central one-third of the ipsilateral patellar tendon (PT). The sheep were sacrificed at 16, 26, 52 and 104 weeks postoperation. The PTAG, and, as controls, the contralateral PCL and PT were harvested. These were examined using biomechanical testing as well as light and transmission electron microscopy, including immunohistological techniques. The material properties (maximum stress, elastic modulus) were compared to the morphological features. The cellular distribution, the distribution of glycosaminoglycans (GAGs), the collagen fibril diameter and the occurrence of Type III collagen were studied. Prior to transplantation, the PTAG was shown to be superior in maximum stress (57.2 +/- 5.5 MPa vs 41.3 +/- 1.9 MPa) and elastic modulus (368.8 +/- 49.3 MPa vs 172.3 +/- 14.6 MPa) to the PCL. The early decline in material properties of the PTAG (maximum stress 22% and elastic modulus 42% of the control) after free grafting paralleled a cell- and capillary-rich PTAG tissue with remnants of necrosis and a poorly organized extracellular matrix. Two years after implantation, with progressive alignment of the tissue matrix, maximum stress and elastic modulus acquired approximately 60 and 70% of the control, respectively. However, there was also an evidence of degenerative changes characterized by acellular areas, loss of the normal bundling pattern of collagen fibers and abnormal accumulation of GAGs. Ultrastructurally, there was a predominant shift to thin collagen fibrils in the PTAG compared to PCL and PT, both consisting of thick and thin collagen fibrils. Thin fibrils were demonstrated to be, in part, split thick fibrils as well as newly formed fibrils. Most of these thin fibrils revealed a positive reaction with antibodies to Type III collagen.

Animals↗
PubMed1992

A comparison of the individualized education plan and the individualized family service plan.

The individualized education plan (IEP) and the individualized family service plan (IFSP) are mandated for children with special needs. Occupational therapists participate in the development of both the IEP and the IFSP. This paper summarizes the similarities and the differences in the mandated components. The components addressed are (a) information about the child's status, (b) information about the family, (c) outcomes for the child and family, (d) intervention services, (e) other services, (f) dates and duration of services, (g) selection of a case manager, and (h) transition plans.

Child↗
PubMed1991

The glomerular filtration barrier of the kidney in seven vertebrates classes. Comparative morphological and histochemical observations.

In the mammalian kidney, the glomerular filtration barrier (GFB) is mostly composed of endothelial and epithelial cells with the glomerular basement membrane interposed. In lower vertebrates, extensive regions of the GFB consist of the endothelial and epithelial cells, each lying on its own basement membrane. These two basement membranes border the mesangium, which contains mesangial cells (surrounded by its own discontinuous basement membrane), microfibrils and collagens (cross-striated fibrils, anchoring fibrils, and 5 nm interfibrillar filaments). Occurrence and extension of these mesangial components decrease from fish to mammals. Anionic binding sites associated with the different structures of the GFB of all animal species have been demonstrated by using dyes such as Alcian blue (with or without addition of electrolytes), Ruthenium red or Safranine O. The surface coat of endothelial and epithelial cells, the laminae rarae (interna and externa) of the glomerular basement membrane, the laminae rara and diffusa (wherever distinct endothelial and epithelial basement membranes occurred) as well as the collagen fibrils show particles (with polycationic dyes) or filaments (with monocationic dyes). The mesangial microfibrils are usually well preserved and intensively stained.

Animals↗
PubMed1991

Ultrastructural changes of the patellar tendon as a cruciate ligament substitute (one year and two year results).

In four black-faced sheep, the posterior cruciate ligament was replaced with a free autogenous patellar tendon transplant. Tissue samples from the transplants were investigated by light and electron microscopy 1 year and 2 years after surgery. The normal contralateral posterior cruciate ligament and the normal contralateral patellar tendon were used as controls. The structural differences concerned cells, collagen fibrils, elastic tissue and proteoglycans. Most of the cells of the contralateral patellar tendon were spindle-shaped, whereas those of the transplant were frequently chondroid. In the central region of the transplant as well as in the area far from the bone, cell degenerations, and occasionally hypo- or even acellular zones were found. Measurements of the diameter of collagen fibrils in both contralateral patellar tendon and posterior cruciate ligament showed a more or less pronounced bimodal distribution. A unimodal distribution with mainly thin fibrils (20-60 nm) was demonstrated in the transplant tissue which also revealed some morphological alterations of the collagen fibrils. Thin elastic fibers (microfibrils and amorphous material) were randomly scattered among the collagen fibrils of the control samples, bundles of microfibrils (without amorphous material) characterized the transplant. Staining with Alcian blue in the presence of 0.3 M MgCl2 demonstrated a close relationship between proteoglycans and collagen fibrils as well as elastic components in patellar tendon. This arrangement was lost in the transplant where abundant proteoglycans were revealed which, however, composed a tight irregular network between the collagen fibrils. The results serve as a baseline for understanding the impaired biochemical properties of a free autogenous patellar tendon transplant.

Animals↗
PubMed1989

Biological aspects of long-term failure of autografts after cruciate ligament replacement.

The alterations of the ultrastructure of the posterior cruciate ligament autograft of patellar tendon origin were examined in a sheep model 1 year after surgery. The ultrastructure was also compared with that of the normal contralateral posterior cruciate ligament and patellar tendon. The most striking finding was the unimodal distribution of the collagen fibrils, with a predominance of loosely packed thin fibrils in the central portion of the autograft. The results suggested that the remodeled autograft tissue became highly organized but never exhibited the ultrastructural features of a ligament. This could be responsible for the decreased biomechanical properties and the long-term failure of a patellar tendon autograft.

Animals↗