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Biomedical subjects

M Schulz

Publications and source records attributed to M Schulz.

At least 127 records · Page 7Linked to original sources
PubMed1995

Trophic effect of collicular proteoglycan on neonatal rat retinal ganglion cells in situ.

Naturally occurring neuronal death is widespread in the central nervous system of mammals. To date, the causes and mechanisms of such death are poorly understood. A major hypothesis is that developing neurons compete for limited amounts of trophic factor(s) released from their target centres as in the case of the peripheral nervous system and nerve growth factor. The present study aims to test this 'trophic hypothesis' in the mammalian central nervous system. In the rat, more than 50% of retinal ganglion cells die in the early post-natal period. Schulz and coworkers [57] purified a potential trophic agent from their major target, the superior colliculus, which was identified as a 480 kDa chondroitin sulfate proteoglycan. This proteoglycan or control solutions were injected into the eyes of rat pups during the post-natal part of the period of naturally occurring ganglion cell death. It was found that the collicular proteoglycan prevented the death of a significant number of the ganglion cells that would normally have been lost over a post-injection period of one or two days. The effect of the proteoglycan was dose- and time-dependent. These results support the notion that trophic interactions are a determining factor in the survival of retinal ganglion cells during the period of naturally occurring cell death. It is also the first time that a proteoglycan has been shown to possess neurotrophic properties in situ.

Animals↗
PubMed1995

Effect of collicular proteoglycan on the survival of adult rat retinal ganglion cells following axotomy.

Consistent with numerous previous studies, we have found that in adult rats 29% of cells retrogradely prelabelled by injections into retino-recipient nuclei are lost 1 week after intraorbital section of the optic nerve. This figure increases to 76% 2 weeks after axotomy. Intraocular injections of 150 ng of 480 kDa chondroitin sulphate proteoglycan purified from the superior colliculi of neonatal rats were performed every third day after axotomy. This procedure resulted in the loss of only 3 and 28% of the axotomized retinal ganglion cells 7 and 14 days respectively after optic nerve section. Intraocular injections of chondroitin sulphate type C, one of the sugar types present on the collicular proteoglycan, also resulted in a significant saving of axotomized ganglion cells (with the loss of only 48% 14 days after optic nerve lesion). These findings suggest that the collicular proteoglycan, and to a lesser extent its sugar moieties, substantially slows down the degeneration of adult retinal ganglion cells following axotomy.

Animals↗
PubMed1995

Acute rejection of vascular heart allografts by perforin-deficient mice.

To study the role of perforin in cell-mediated graft rejection, vascularized hearts were grafted to perforin-deficient C57BL/6 and control C57BL/6 recipient mice. Fully allogeneic heart grafts (BALB/c) were acutely rejected by both recipients within 6 days. Peritoneal exudate lymphocytes from control mice but not from perforin-deficient mice exhibit a strong alloreactive cytotoxic activity in vitro. Histological analysis of the rejected tissues demonstrated extensive mononuclear cell infiltrates in both recipients. Flow cytometry analysis and immunohistology of graft-infiltrating cells showed similar proportions of lymphocyte subsets (CD8 >> CD4). Collectively, these data indicate that perforin is not essential in the cell-mediated acute rejection of a fully mismatched heart allograft. However, perforin-dependent effector mechanisms appeared to be limiting in the T cell-mediated rejection of heart allografts differing only at a single major histocompatibility complex class I antigen (bm1), because these grafts survived longer (mean 87.8 days) in perforin-deficient than in control mice (mean 31.5 days).

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PubMed1995

Glial reactivity in the retina of adult rats.

The present study aimed to characterize the reaction of mammalian (rat) retinal macroglia (Müller cells and astrocytes) to disturbances of their environment in the form of intraorbital section of the optic nerve, intraocular insertion of a thin glass capillary (without damage to the retina) or a combination of both. Glial reactivity was assessed through the use of a battery of antibodies which recognise four different proteins--glial fibrillary protein (GFAP) and three other proteins designated respectively MA1, 4D6 and 4H11. Retinal astrocytes did not exhibit any changes in normally expressed GFAP or MA1. By contrast, the expression of GFAP and MA1 in Müller cells increased 14 days following section of the optic nerve and/or intravitreal insertions of a glass capillary. Three days postoperatively, the expression of GFAP, but not MA1, had already increased significantly in Müller cells. 4D6 and 4H11 proteins were not expressed in astrocytes. In Müller cells, the levels of these proteins increased significantly following combined optic nerve section and intraocular insertion of a glass capillary. Thus, a mechanical disturbance of the intraocular environment constitutes a more effective stimulus in increasing the expression of some Müllerian proteins than damage to the axons of retinal ganglion cells. Such changes have important implications for various ocular treatments that involve intraocular administration of drugs, as well as for the survival/regeneration potential of retinal ganglion cells undergoing Wallerian degeneration.

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PubMed1995

Expression of osteoblastic markers in cultured human bone and fracture callus cells.

We compared the expression of osteoblastic markers in cultured human cells isolated from fracture calluses of various histological states of development with that in cells from adult and fetal bone. Adult osteoblasts and all callus cells produced almost exclusively type I collagen, whereas fetal osteoblasts produced also considerable amounts of type III collagen in vitro. 1,25-Dihydroxyvitamin D3 induced the synthesis of osteocalcin in all bone and callus cells but to varying extents. Fetal bone cells and early-stage callus cells synthesized less than 10% the amount of osteocalcin produced by adult bone cells. Late-stage callus cells produced intermediate levels of osteocalcin. Fetal bone cells and early-stage callus cells responded to parathyroid hormone with a less pronounced increase in intracellular cAMP than did adult bone cells. Late-stage callus cells showed the best response to parathyroid hormone. The activity of alkaline phosphatase was highest in fetal bone cells. These observations show that cells isolated from fetal bone and from fracture callus tissues express a pattern of markers clearly relating them to the osteoblastic lineage. On the basis of the different patterns of osteoblastic markers expressed in vitro we conclude that functionally distinct subtypes of osteoblasts do exist in different mineralized tissues and at different developmental stages.

Adult↗
PubMed1995

Fluconazole is removed by continuous venovenous hemofiltration in a liver transplant patient.

Fluconazole is effective for the treatment of fungal infections. A continuous venovenous hemofiltration (CVVH) was necessary in a liver transplant patient with anuria. Fluconazole treatment was started after the diagnosis of systemic candidiasis. There was no adverse effect on liver function, and the immunosuppression with cyclosporine was not affected. It is shown for the first time that CVVH effectively removes fluconazole from the blood circulation by a clearance into the hemofiltrate of approximately 21 ml/min. These data suggest that the treatment of fungal infections with fluconazole does not necessitate a reduction of the dosage during CVVH.

Anuria↗
PubMed1995

[Long-term administration of benzodiazepines--disease follow-up, sequelae, treatment. A retrospective clinical record evaluation of 194 patients].

Clinical records of all patients treated from 1983 to 1991 in a university clinic for lang-term-use of benzodiazepines were examined. Daily intake of benzodiazepines began in 80% immediately after the first prescription. At the time of admission, 34% reported intake of more than 3 DDD, i.e. more than 30 mg of diazepam. In patients 70%, additional abuse of alcohol and/or other psychotropic substances was established. Benzodiazepines were the first substances abused in 49%. The diagnosis of abuse or dependency was made in 65% before admission. Symptoms of organic brain syndrome were described in 30% of all records. Symptom leading to first benzodiazepine intake were somatic complaints (40%), depressed mood (39%), insomnia (37% and anxiety (24%). Between first intake and admission, there was a significant increase in patients with somatic complaints, depressed mood and anxiety. After detocification, symptoms leading to admission improved in 80% of all patients.

Adult↗
PubMed1994

Retinal ganglion cell survival and neurite regeneration in vitro after cell death period are dependent upon target derived trophic factor and retinal glial factor(s).

Retinal ganglion cells (RGCs) obtained from the rat retina after the cell death period were maintained in vitro by target derived retinal ganglion cell neurotrophic factor (RGNF). However, only 15% of surviving RGCs expressed neurites. On the other hand, when the culture was supplemented with retinal glia conditioned medium, nearly 80% of surviving RGCs expressed neurites which were longer than two cell diameter. Expression of neurites is not due to the presence of laminin in the glial conditioned medium as laminin coated substratum had no significant effect on the neurite growth from mature RGCs in the absence of glial factors.

Animals↗
PubMed1994

The pattern of expression of a 13-kDa protein (CS-32 antigen) in the retina and its target nuclei in developing and mature rats.

A polyclonal antibody (designated CS-32) immunopurifies a 13-kDa protein from the superior colliculus (SC) of neonatal rat. There is a strikingly inverse temporal relationship in expression of the 13-kDa protein in the developing retina and its principal target nuclei, SC and the dorsal lateral geniculate nucleus. The 13-kDa is a cell-surface protein expressed exclusively by neurones and is clearly associated with synapses.

Animals↗
PubMed1994

Retinal ganglion cell survival in vitro maintained by a chondroitin sulfate proteoglycan from the superior colliculus carrying the HNK-1 epitope.

We recently reported evidence implicating a superior colliculus-derived chondroitin sulfate proteoglycan (SCCP) in the trophic support of cultured retinal ganglion cells (Schulz et al., 1990). In the present work we show preparations of the SCCP to be reactive with an antibody (CS-56) to chondroitin sulfate types A and C and with the HNK-1 antibody. Reaction with the HNK-1 antibody allowed us partially to purify the native proteoglycan by immunoaffinity chromatography. HNK-1 reactive material was further processed by a combination of molecular sieve chromatography in the presence of 4M guanidine HCL followed by anion exchange chromatography to yield a product that migrated electrophoretically as a single band in polyacrylamide gel with an apparent molecular weight of not less than 400 k. The SCCP, when added to a fully defined culture medium, maintained the survival of the vast majority (80%) of the ganglion cells over a 16 hr culture period with 86% of these cells showing a profusion of processes; few ganglion cells (10%) survived in the absence of the proteoglycan. Electrophoretic analysis of nonreduced preparations of the molecule did not reveal any low molecular weight silver stained components that may have remained associated with the molecule after guanidine HCL treatment. However, two bands corresponding to molecular weights of around 60 and 80 k were reproducibly observed on polyacrylamide gels following electrophoresis of the molecule in the presence of beta-mercaptoethanol. Our findings provide further evidence suggesting a role for a chondroitin sulfate proteoglycan carrying the HNK-1 epitope in the trophic support of central neurones.

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