Biomedical subjects

R C Janzer

Publications and source records attributed to R C Janzer.

59 records · Page 4Linked to original sources

PubMedDate not supplied

Dexamethasone selectively regulates the activity of enzymatic markers of cerebral endothelial cell lines.

Two endothelial cell lines were derived from grafts of the central nervous system using retrovirus mediated gene transfer to introduce the polyoma middle-T oncogene into fetal rat brain endothelial cells and transplantation of these cells into adult rat brain. In this report, we further characterize these cells and the effect of dexamethasone on the expression of specific enzymatic markers. These cells take up acetylated low density lipoprotein, leucine, and glucose, and express Factor VIII-related antigen, angiotensin converting enzyme, alkaline phosphatase, gamma-glutamyltranspeptidase, and as yet undescribed aminopeptidase A and B-like enzymes. When grown on semi-permeable membranes, these transformed cells do not spontaneously retain small hydrophilic molecules. In culture, one of the lines (EC 193) forms a confluent monolayer of spindle-shaped cells homogenously expressing gamma-glutamyltranspeptidase at a level comparable to primary cells. The other cell line (EC 219) grows as clusters of elongated cells, and gamma-glutamyltranspeptidase activity is expressed mainly in cells forming the clusters. This clustered pattern changes to a confluent one after culture on type-I collagen. Dexamethasone increases angiotensin-converting enzyme activity, and decreases the expression of gamma-glutamyltranspeptidase and aminopeptidase A, whereas the aminopeptidase B activity is little modified. Inhibition of aminopeptidase A activity by amastatin, potentiates angiotensin II effects on DNA synthesis. These results indicate that retrovirally transformed brain endothelial cells are a useful model for studying the blood-brain barrier in vitro and that dexamethasone, an agent with the potential to reduce brain edema, directly affects some blood-brain barrier properties in these endothelial cell lines.

Aminopeptidases↗

PubMedDate not supplied

Astrocytes induce blood-brain barrier properties in endothelial cells.

The highly impermeable tight junctions between endothelial cells forming the capillaries and venules in the central nervous system (CNS) of higher vertebrates are thought to be responsible for the blood-brain barrier that impedes the passive diffusion of solutes from the blood into the extracellular space of the CNS. The ability of CNS endothelial cells to form a blood-brain barrier is not intrinsic to these cells but instead is induced by the CNS environment: Stewart and Wiley demonstrated that when avascular tissue from 3-day-old quail brain is transplanted into the coelomic cavity of chick embryos, the chick endothelial cells that vascularize the quail brain grafts form a competent blood-brain barrier; on the other hand, when avascular embryonic quail coelomic grafts are transplanted into embryonic chick brain, the chick endothelial cells that invade the mesenchymal tissue grafts form leaky capillaries and venules. It is, however, not known which cells in the CNS are responsible for inducing endothelial cells to form the tight junctions characteristic of the blood-brain barrier. Astrocytes are the most likely candidates since their processes form endfeet that collectively surround CNS microvessels. In this report we provide direct evidence that astrocytes are capable of inducing blood-brain barrier properties in non-neural endothelial cells in vivo.

Animals↗

PubMedDate not supplied

Primitive neuroectodermal tumor with choroid plexus differentiation.

A case of a cerebral juvenile undifferentiated round cell tumor with unusual formation of glandular structures is presented. The round cell component showed focal expression of glial fibrillary acidic protein, S-100 protein, neurofilament protein and neuron-specific enolase. The glandular part consisted of papillary epithelial structures with a central PAS-positive lumen. Ultrastructural findings supported the interpretation of these parts as choroid plexus. This route of differentiation was recognizable at the first operation at the age of 5 years and was much more prominent in the recurrence found 7 1/2 years later. The unusually benign course of this primitive neuroectodermal tumor (PNET) may be due to its intrinsic progressive tendency towards choroid plexus differentiation.

Biopsy↗

PubMedDate not supplied

A case of congenital non-progressive sensory neuropathy with tonic pupils.

One case of a non-progressive congenital neuropathy is reported. Clinical findings included subtotal analgesia, and diminished temperature, vibration and proprioceptive sense in arms and legs. The sensory nerve action potentials were absent. Autonomic dysfunctions were restricted to tonic pupils. Sural nerve biopsy taken at the age of 8 1/2 showed fascicular hypoplasia, subtotal loss of myelinated nerve fibers and severe loss of unmyelinated nerve fibers with a pathological size distribution. In the skin biopsy, including several cutaneous nerves, no myelinated nerve fibers were present, the unmyelinated nerve fibers were severely reduced and the collagen density was increased. Perivascular and periglandular innervation was significantly reduced. The findings in this case are suggestive of a malformative or fetally acquired lesion and further illustrate the difficulties in classification of the hereditary sensory neuropathies.

Child↗

PubMedDate not supplied

A case of dissection of intracranial cerebral arteries with segmental mediolytic "arteritis".

The intravital diagnosis of intracranial arterial dissection is not always possible due to atypic and non-specific clinical and radiological presentations. The postmortem pathological examination of cerebral blood vessels is therefore necessary to establish or confirm the presence of a dissecting aneurysm of intracranial arteries. Most of the described cases showed no significant underlying vascular pathology. Here we present the case of a 24-year-old women who died 5 days after admission to the hospital for a rapidly developing right-sided hemisyndrome. Neuroradiological examination had revealed ill-defined bifrontal hypodense lesions and angiographic findings were compatible with a dissection of the left extracranial internal carotid artery with embolic subocclusion of both anterior cerebral arteries. The pathological evaluation ruled out a thromboembolic occlusion of cerebral arteries and an extracranial internal carotid artery dissection but showed an extended dissecting process of variable age in the anterior circulation of the circle of Willis. The dissected vessels showed pathological changes characteristic of segmental mediolytic "arteritis" [Slavin and Gonzalez-Vitale 1976]. To our knowledge this is the first report on intracranial arteries being affected by this pathologic entity. Our case illustrates the importance of a postmortem examination of dissecting aneurysms of intracranial arteries. Careful serial section studies of dissected intracranial arteries in young subjects should be performed and may allow for a better understanding of the vascular pathology underlying the dissection processus.

Adult↗