Water-soluble treatments to enhance glucose permeability of protein-resistant polymer overlayers

This study employed two water-soluble and nontoxic molecules, sucrose and glycerol, to enhance the permeability of PEG-PHEMA polymer gels coated onto 100 kDa molecular weight cutoff polyethersulfone (PES) microdialysis probes. Sucrose precoating of the probes prior to prepolymer coating prevented penetration of the prepolymer into the microdialysis membrane. Glycerol mixed with the prepolymer introduced porosity in the polymer coating upon curing. The sucrose and glycerol were completely removed by soaking in PBS after curing of the polymer coat on the probe tip. Polymer coated probe glucose permeability was tested by measuring glucose recovery from PBS solutions. Biocompatibility was assessed by measuring glucose recovery of polymer coated probes from heparanized whole porcine blood. Results show that the sucrose and glycerol treatments yielded polymer coated probes with glucose permeability nearly equal to bare probes when tested in PBS solution, but that this increased permeability was not observed when tested in whole blood. This suggests that the thickness of the polymer films (10-100 microm), while not a limiting factor in PBS solution, may have presented a diffusion barrier to glucose recovered from blood. Surprisingly, however, the polymer coated probes exhibited less thrombus formation that did the bare probes after blood exposure.     

Skeletal dysplasia syndrome with progeroid appearance,characteristic facial and limb anomalies,multiple synostoses,and distinct skeletal changes: A variant example of the Lenz–Majewski syndrome

Here we report a 10 year-old mentally retarded, deaf boy with a unique pattern of anomalies: progeroid appearance, characteristic facial and limb anomalies, multiple synostoses, and distinct skeletal changes. He represents a variant example of “hyperostotic dwarfism” as delineated by Lenz and Majewski.     

Morphology and distribution of Alzheimer neuritic (senile) and amyloid plaques in striatum and diencephalon

Summary Mapping of striatal and diencephalic plaque distribution was conducted in 25 cases of dementia of the Alzheimer type. This analysis was carried out by fluorescence microscopy of paraffinembedded tissue sections treated with Thioflavine S as fluorochrome. Consistent differences in plaque morphology and density between nuclei and fiber tracts were observed. Striatal and pallidal distribution was uneven, with plaque aggregation near and within certain fiber tracts: capsules, medullary laminae, and radial fasciculi. Diencephalic plaques showed also preferred aggregation near and within fiber tracts and within the intralaminar nuclei.The different subcortical plaque morphologies observed according to the nuclear or fiber tract location of the amyloid plaque, indicates that the peripheral (halo) portion of the plaque is determined by the neuropil response to the primary event: the amyloid deposit.No correlation was observed between the distribution of plaques and any particular neurotransmitter system. In that respect, plaques were present within the nucleus basalis. Neurofibrillary tangle distribution was also seen to be dissociated from plaque distribution.     

Conformational mimicry in Alzheimer's disease. Role of apolipoproteins in amyloidogenesis.

Several apolipoproteins are known to be closely associated with amyloid fibrillogenesis. Serum amyloid A, apolipoprotein (apo) AII and apo A1 are each deposited as biochemically distinct forms of amyloid. Late-onset Alzheimer's disease is linked to one isotype of apo E, apo E4. Apo E and apo E4 in particular have been shown to modulate amyloid fibril formation by amyloid-beta peptides in vitro. Furthermore, the carboxy terminus of apo E has been shown to be a constituent of plaque amyloid. We show immunohistochemically and electron microscopically the presence of apo A1 in senile plaques. The intact apo A1 can itself form amyloid-like fibrils in vitro that are Congo Red positive. We propose that some proteins when misfolded can propagate this misfolding to identical units, either autocatalytically or to other proteins that are induced to fold into the same abnormal conformation. This conformational mimicry may initiate and/or augment fibrillogenesis in Alzheimer's disease.     

Continually improving the health and value of health care for a population of patients: the panel management process

Today's primary care provider faces the challenge of caring for individual patients as well as caring for populations of patients. This article offers a model--the panel management process--for understanding and managing these activities and relationships. The model integrates some of the lessons learned during the past decade as we have worked to gain an understanding of the continual improvement of health care after we have understood that care as a process and system.     

First transmission electron micrograph of continuous mitotic spindle fibers between polar area and chromosome ends

Congenital and/or nevoid skin disorders following the lines of Blaschko may have a delayed onset after birth. They have to be differentiated from acquired dermatoses exhibiting the same linear pattern. In common dermatoses, such as psoriasis or lichen planus, lesions in a blaschkolinear distribution most often occur together with scattered lesions, but occasionally they may be isolated. Less common self-limited dermatoses such as lichen striatus and adult blaschkitis always present in a blaschkolinear fashion. In these diseases, or some other conditions occasionally distributed along these lines (chronic graft versus host reaction, fixed drug eruption, lupus erythematosus, atopic dermatitis, etc.), the cause of the disease may lead to the unmasking of tolerance to an abnormal keratinocyte clone that remained hidden in these lines. In addition to epithelial cells, other cells may be involved in the occurrence of acquired blaschkolinear dermatoses. In linear atrophoderma and linear fibromatosis, the histogenesis seems to involve hypothetic dermal clones. The extension of an acquired dermatosis on a preexisting linear nevoid disorder is an argument in favor of an early embryonic somatic mutation of a skin cell line.     

A novel assay for lysosomal pepstatin-insensitive proteinase and its application for the diagnosis of late-infantile neuronal ceroid lipofuscinosis

A highly sensitive assay for mammalian lysosomal pepstatin-insensitive proteinase (LPIP) is described using a synthetic peptide substrate coupled to aminotrifluoromethyl coumarin (AFC). LPIP is an endocarboxyl proteinase which has specific sequence requirements of Phe-Phe around the carboxyl terminal. This HPLC based assay can detect patients suffering from late-infantile neuronal ceroid lipofuscinosis (LINCL) and also heterozygote carriers in cultured lymphoid cells and skin fibroblasts. None of the patients analyzed had detectable enzyme activity confirming the defective gene product, while carriers had about 50% activity when compared with the normal controls. Neurological controls comprised of patients with other neurodegenerative disorders have LPIP activities similar to normal controls. LPIP activity is also detectable in amniocytes and chorionic villi. Thus the assay reported can also be used for prenatal diagnosis of LINCL.     

Apolipoprotein E alters metabolism of AbetaPP in cells engaged in beta-amyloidosis

Canine smooth muscle cells (SMCs), cultured from amyloid-affected brain blood vessels accumulate Alzheimer amyloid-beta peptide (Abeta) intracellularly, either spontaneously or after treatment with apolipoprotein E (apoE). ApoE is codeposited with Abeta, which suggests that apoE participates in Abeta accumulation. We tested the hypothesis that apoE-induced accumulation of Abeta in SMCs is caused by an increased production of amyloid-beta precursor protein (AbetaPP) and/or its altered metabolism. We found that 24 hours of treatment with apoE3 or apoE4 induced intracellular accumulation of Abeta-immunoreactive deposits in SMCs but did not influence AbetaPP production and processing. The treatment with apoE3 or E4 for 3 days resulted in the following: increased Abeta-accumulation; reduced levels of secreted Abeta; increased production and cellular retention of mature AbetaPP770; and reduced culture growth, cell proliferation, and viability. ApoE4, but not apoE3, increased cellular levels of mRNA AbetaPP 770 (the main form produced in SMCs) about ninefold. ApoE3 stimulated production and cellular retention of endogenous apoE. We hypothesize that Abeta accumulation is triggered by apoE, which may bind and immobilize soluble Abeta produced in SMCs. The newly formed Abeta deposits may further accelerate Abeta accumulation by altering metabolism of AbetaPP.     

Ultracytochemical studies of the blood-meningeal barrier (BMB) in rat spinal cord

Summary Alkaline phosphatase(AP),5-nucleotidase(5N) and nucleoside diphosphatase (NDPase) activities were studied by cytochemical methods applied to light and electron microscopy in the microvasculature of spinal cord leptomeningeal strips of normal and protamine sulfate (PS) treated rats. The increased permeability to intravenously injected horseradish peroxidase was observed in some segments of microvessels of PS treated rats. Enhanced formation of plasmalemmal pits and deep invaginations, formation of numerous pinocytic vesicles and the appearance of channel-like structures in the cytoplasm of endothelial cells were the most striking ultrastructural evidence of increased permeability of the affected microvessels. All of these structures also showed activity of AP, and to lesser extent, of NDPase; 5N activity was mainly associated with the delimiting membranes of pinocytic vesicles. Our data present evidence that a shift of enzymatic activity from luminal to abluminal surface of affected endothelial cells results from membrane flow accompanying increased transport activity via formation of pinocytic vesicles and channel-like structures.Supported in part by a grant from NINCDS No. 17271-01Visiting scientist from the Neurological Institute of the University of Vienna, Vienna, Austria