A model system for increasing the intensity of whole-cell biocatalysis: investigation of the rate of oxidation of D-sorbitol to L-sorbose by thin bi-layer latex coatings of non-growing Gluconobacter oxydans.

We developed a novel <50-microm thick nano-porous bi-layer latex coating for preserving Gluconobacter oxydans, a strict aerobe, as a whole cell biocatalyst. G. oxydans was entrapped in an acrylate/vinyl acetate co-polymer matrix (T (g) approximately 10 degrees C) and cast into 12.7-mm diameter patch coatings (cellcoat) containing approximately 10(9) CFU covered by a nano-porous topcoat. The oxidation of D-sorbitol to L-sorbose was used to investigate the coating catalytic properties. Intrinsic kinetics was studied in microbioreactors using a pH 6.0 D-sorbitol, phosphate, pyruvate (SPP) non-growth medium at 30 degrees C, and the Michaelis-Menten constants determined. By using a diffusion cell, cellcoat and topcoat diffusivities, optimized by arresting polymer particle coalescence by glycerol and/or sucrose addition, were determined. Cryo-FESEM images revealed a two-layer structure with G. oxydans surrounded by <40-nm pores. Viable cell density, cell leakage, and oxidation kinetics in SPP medium for >150 h were investigated. Even though the coatings were optimized for permeability, approximately 50% of G. oxydans viability was lost during cellcoat drying and further reduction was observed as the topcoat was added. High reaction rates per unit volume of coating (80-100 g/L x h) were observed which agreed with predictions of a diffusion-reaction model using parameters estimated by independent experiments. Cellcoat effectiveness factors of 0.22-0.49 were observed which are 20-fold greater than any previously reported for this G. oxydans oxidation. These nano-structured coatings and the possibility of improving their ability to preserve G. oxydans viability may be useful for engineering highly reactive adhesive coatings for multi-phase micro-channel and membrane bioreactors to dramatically increase the intensity of whole-cell oxidations.

Non-traumatic subdural hygroma.

Subdural hygroma consists of a cerebrospinal fluid-like subdural fluid collection with a low oncotic pressure in comparison with venous blood. Its etiology and pathophysiology, which may be different from other subdural fluid collections, are reviewed. We report the clinical history of a 80-year-old woman with a bilateral frontal subdural hygroma. Serial CT-scanning demonstrated a rapid increase in volume after two years of slow evolution. In our patient dehydration may have been the triggering factor. The course of non-traumatic subdural hygroma is not well known. This report illustrates that subdural hygroma can have a dramatic evolution and that therapeutic decisions in these patients should be based on repeated CT-scans.

Monoaminergic neurotransmitters in Alzheimer's disease. An HPLC study comparing presenile familial and sporadic senile cases.

Norepinephrine, epinephrine, dopamine, serotonin and their major metabolites were measured in 20 regions of the left hemisphere in 4 presenile familial cases of Alzheimer-type dementia and 4 sporadic senile cases. Both groups were compared to values in normal brains obtained in our laboratory. Quantitative determination of the monoamines was performed by HPLC with electrochemical detection. The clinical diagnosis of Alzheimer-type dementia was confirmed by histological examination of the right hemisphere and brain stem. The serotonergic system was dramatically affected in the familial cases with very low or undetectable serotonin concentrations in most cortical and subcortical areas studied and an important cell loss in the nucleus raphe dorsalis, origin of the main ascending serotonergic system. In the senile demented patients the serotonergic deficit is less important but still clearly present. The noradrenergic, adrenergic and dopaminergic systems were less affected by the disease process in senile sporadic as well as in the presenile familial type of Alzheimer's disease.

Dissociated ipsilateral horizontal gaze palsy in one-and-a-half syndrome: a clinicopathologic study.

We report a patient with a one-and-a-half syndrome due to an isolated small infarction in the left rostral part of the paramedian pontine reticular formation and the ipsilateral medial longitudinal fasciculus. Oculocephalic movements toward the left were preserved (dissociated ipsilateral horizontal conjugate gaze palsy).

Brain stem infarction as a complication of giant-cell arteritis.

Two cases of brain stem infarction as an early and fatal complication of giant-cell arteritis are reported. These complications occurred despite adequate treatment with corticosteroids. The findings at autopsy are compared with those of the literature. The possible pathogenetic mechanisms of vertebro basilar occlusion and the therapeutical implications are discussed.

Coma as presenting manifestation of Wernicke's encephalopathy.

A patient in whom coma was the presenting manifestation of Wernicke's encephalopathy is reported. Clinical reports on coma in Wernicke's encephalopathy are scarce, but postmortem studies have demonstrated that this form of presentation is often not recognized. The diagnosis of Wernicke's encephalopathy should be suspected in any patient presenting with coma of unclear etiology.

Familial oligodendroglioma. Case report.

A case of familial oligodendroglioma, occurring in a mother and her daughter, is presented.

Electron-microscopic visualization of binding of antibodies from sera of glioma patients on cultured glioma cells.

Several human cell lines (normal and neoplastic glia, cerebral metastases from adenocarcinoma, fibroblasts) were incubated with sera from patients with well and poorly differentiated glioma and with sera from healthy donors and then stained with PAP complex to define and localize the antibody reaction with cell surface antigens by means of electron microscopy. The sera of glioma patients proved to contain antibodies which bound the tumor-associated antigenic determinants on the cell membranes of gliomas and of cerebral metastases from adenocarcinoma in tissue cultures. Further, absorption testing of the reactive sera on normal brain, well-differentiated astrocytoma and cultured glioblastoma cells, together with cross-reactivity experiments suggests that at least two antigens or groups of antigens are expressed on the glioma cell surface: one shared by well and poorly differentiated glioma cells and the other by poorly differentiated glioma cells and the cells of cerebral metastases from adenocarcinoma.

Two separate membrane-bound antigens on human glioma cells in tissue culture detected with sera from glioma patients by immunofluorescence.

Sera from patients with malignant and benign gliomas, as well as sera from healthy donors, were tested by indirect immunofluorescence to detect antibodies against antigens on the membrane of glioblastoma, astrocytoma, reactive perimetastatic glia, normal glia and fibroblasts in tissue culture. Sera from glioblastoma patients reacted with glioblastoma, astrocytoma and reactive glial cells; they were negative on normal glia and on fibroblasts, whereas sera from astrocytoma patients were unreactive. Sera from control patients were positive in 7 out of 15 cases, although some differences were noted in the pattern of reaction. Absorption with astrocytoma powder, with glioblastoma and reactive glial cells indicated that all the positive cell lines expressed an astrocytoma-associated antigen "A", while only glioblastoma lines and reactive glial line shared a supplementary antigen "G". Neither of these 2 antigens seemed to be present in significant amount in normal brain, since the positive reactions could not be abolished by absorption with normal brain powder. The relationship between these 2 antigens and the process of increasing malignancy in gliomas is briefly discussed.

Absorption of free and antibody-conjugated horseradish peroxidase to fixed glial cells in tissue culture, a possible source of error in immunohistochemistry.

Incubation of cellular preparations with antibody-conjugated peroxidase result in a very strong unspecific staining, for one electropolar binding of the basic enzymic protein with the cell structures. In immunohistochemical practice, it may represent an evil as import as when dealing with immunofluorescence techniques. This background can to a great extent be avoided by rinsing the preparations in buffer at pH = 6.2.