Dimensional complexity of EEG waveforms in neuroleptic-free schizophrenic patients and normal control subjects.

Dimensional complexity reflects the number of independent variables contributing to a dynamic process. EEG epochs recorded from 12 neuroleptic-free schizophrenic patients and 11 normal control subjects were Laplacian-filtered to highlight activity specific to prefrontal and parietal areas, and dimensional complexity measures of the resulting signals were then derived. Complexity of EEG waveforms generated by schizophrenic patients was depressed relative to that of normal subjects, especially in left frontal and right parietal regions. These data suggest that complexity of underlying is also reduced.

Evaluation of the influence of the aqueous phase bioconstituent environment on the F-19 T1 of perfluorocarbon blood substitute emulsions.

Oxygen-sensitive F-19 magnetic resonance imaging of perfluorocarbon compounds requires that fluorocarbon T1 changes correlate with the local PO2 and not with the composition of the surrounding aqueous phase. The influence of various bioconstituents and paramagnetic ions within the aqueous phase on the F-19 fluorocarbon phase T1 for PFC emulsions was evaluated at 0.14 and 0.66 T. T1 was measured for FC-43, perflubron, and a fluorinated surfactant. Controlled variables introduced in the aqueous phase included annex solution constituents, blood, pH changes, and Gd-DTPA. For a constant PO2, the F-19 T1s were independent of the emulsion constituents, blood concentration, and pH. For FC-43 and perflubron, F-19 T1 was independent of the Gd-DTPA concentration, while the aqueous phase T1 decreased by more than an order of magnitude. XMO-10 (smallest emulsion particle size) showed a slight decrease in F-19 T1 with increasing Gd-DTPA concentration at 0.66 T.

Perfluorooctylbromide (PFOB) as a vitreous substitute in non-human primates.

We evaluated the toxicity of perfluorooctylbromide in the primate eye as a short-term postoperative vitreous substitute. Four eyes of 4 African green monkeys underwent complete vitrectomy and vitreous replacement with 1.5-2.0 ml of PFOB. One additional animal received BSS as a control vitreous substitute in one eye. Animals were examined twice weekly for clarity and consistency of the vitreous replacement substance. Anterior segment and lenses remained clear in all eyes, although in the immediate postoperative period one eye became inflamed and had a culture-negative vitritis. The other eyes showed a minimal anticipated postoperative vitreous inflammation. Emulsification of the PFOB began within 3 days of injection and progressed up to 3 weeks, precluding fundus examination and fluorescein angiography after 2 weeks. Eyes were enucleated and light microscopy performed at 2 days, 10 days, 33 days, and 45 days. No toxic effects to the retinal cells were detectable by histological examination, but perivasculitis of retinal vessels was noted at 45 days. Indirect examination was normal up to 10 days; thereafter, the fundus view was obscured by the emulsified PFOB. Because of cellular migration into the vitreous cavity and retinal perivasculitis, observed histologically, PFOB seems most suitable for intraoperative rather than postoperative use.

Evaluation of silicone gel as a long-term vitreous substitute in non-human primates.

Two preparations of silicone gels were evaluated as long-term vitreous substitutes in the vitrectomized and lensectomized eyes of primates. Both preparations were injected in liquid form and polymerized in the vitreous cavity. There was no toxic effect on the ocular structures up to 13 months after implantation. Fundus examination and fluorescein angiography were possible through the less rigid gel, whereas the preparation with higher rigidity consistently appeared cloudy.

Arterial blood gases and brain oxygen availability following infusion of intratracheal fluorocarbon neat liquids.

Eight adult New Zealand Swiss rabbits (3-5 kg) having previously implanted chronic bilateral platinum electrodes in the visual cerebral cortex and subcutaneous silver reference electrodes were tranquilized and monitored in multiple 2-3 hour sessions using voltammetric techniques. Six of these were given intratracheal neat liquid fluorocarbons ranging in boiling point from 132 degrees C to 215 degrees C at doses of 2 or 4cc/kg. Each animal received only one fluorocarbon liquid. Two additional rabbits were match-studied as controls. Half of the rabbits have survived more than five months. Both controls and two experimental rabbits were sacrificed after more than seven months due to gastric hairballs. The period of daytime monitoring sessions, when cathodic brain oxygen currents (aO2), arterial blood gases and pH were obtained, was between 34 and 263 days. In some animals the arterial pCO2 was increased during the first week but the pO2 and pH remained nearly normal in all eight animals throughout. The two best fluorocarbons for liquid breathing on the basis of this limited but intensive work are F-methyldecalin and F-5,6H-dec-5-ene (F44E).

Response of the rabbit lung as a criterion of safety for fluorocarbon breathing and blood substitutes.

From the first liquid breathing experiments until now, the lung, not surprisingly, has played a central role in the evolution of fluorocarbon blood substitutes. The first breathable fluorocarbon, a mixture of F-alkylfurans(FC75), bp 102 degrees C, while a poor solvent for the lung's lining and a good solvent for oxygen and carbon dioxide, proved to cause a characteristic gas/vapor microbubble embolism following intravenous administration as an emulsion. Higher boiling fluorocarbons, e.g. F-tributylamine (FC47), bp 174 degrees C, do not produce such gas-vapor emboli. However, intermediate boiling compounds such as F-decalin (PP5), bp 141 degrees C, produce lungs which, although they certainly appear not to contain microbubble emboli, do not collapse when the thorax is opened. Such hyperinflated non-collapsible lungs (HNCL) occur in the rabbit after the intravenous infusion of F-decalin emulsions as well as after the intratracheal infusion of F-decalin neat liquid. F-decalin induced HNCL retain their appearance and low specific gravity for many weeks, gradually returning toward normal after many months. F-methyl decalin, bp 165 degrees C, does not cause HNCL after intravascular or intratracheal administration. Fluorocarbons having boiling points between 140 degrees C and 165 degrees C are being tested in order to find a perfluorinate with the highest transpiration rate, and hence vapor pressure, compatible with an acceptable body dwell time. We have given fluorocarbons intratracheally to 75, intravenously to 221 and both intratracheally and intravenously to 8 rabbits. Free radical trapping agents, antineutrophil, antiinflammatory and other drugs have been administered without appreciable decrease of HNCL. Fluorocarbon critical solution temperature, lipid solubility, emulsifiability, and other physicochemical properties may mediate the pulmonary effect. One method of preventing and treating low dose F-decalin-induced HNCL in rabbits is described.

Polarographic cerebral oxygen availability, fluorocarbon blood levels and efficacy of oxygen transport by emulsions.

In order to relate blood perfluorocarbon (PFC) level to brain tissue oxygen availability (aO2) and respiratory oxygen (FIO2), twelve conscious rabbits with chronically implanted platinum cathodes were infused with six types of emulsions in 14 infusions and their response to oxygen and carbogen breathing recorded. Blood was removed for sampling and to avoid a volume overload. Blood lactate was measured as an indicator of adequacy of perfusion. Glucose, osmotic pressure, packed cell volume, PFC by combustion and volatilization were also measured in blood samples. Methyl prednisolone was administered to 5 rabbits. Blood PFC levels measured by the commonly used centrifugation method (Fluorocrit) were subject to considerable variation, depending mainly upon centrifugation time. Fluorocrit values after Oxypherol infusion decreased from an average of 43% for 5 minutes to 15% for 30 minutes centrifugation. Fluorocrit tended to slightly increase with time of centrifugation when phospholipid was used as the emulsifier, early in PFC infusion and on the next day. Blood fluorocarbon was always lower, about half that of 30 minutes of centrifugation, when determined by combustion or by volatilization, than by centrifugation. The increase in brain a O# response to oxygen and carbogen was observed at a lower PFC blood level than expected and in some animals appeared in either the right or left hemisphere, but not in both, suggesting that oxygen transport, at least near the electrode, was by other than oxygen solubility in blood PFC. Blood lactate proved to be an excellent monitor of whole body perfusion. Animals with a blood lactate above 5 mM/L at 1 hour post infusion died the following day. The fluorocrit after 5, 10, 20, and 30 minutes of centrifugation, which we have named the "fluoro-gram," can have a sharp downward, a slight upward curve, or stay level, depending upon the type of emulsifier, the amount of PFC circulating and the time it has circulated. The fluorocarbon-induced increases in aO2 persist through the third day. This enhanced cerebrocortical aO2 current can be very roughly calculated as: aO2 current equals the air aO2 current plus (the 30 minute fluorocrit times K) where K for oxygen is 0.05 and for carbogen is 0.07. Some enhancement of the aO2 current in oxygen lingers to the fifth day after the blood PFC level is vanishingly small. Methyl prednisolone has a transient effect in suppressing the PFC enhanced oxygen and carbogen aO2 responses and no effect on the Oxypherol fluorogram.(ABSTRACT TRUNCATED AT 400 WORDS)

Deconvolution techniques for removing the effects of chemical shift in 19F nuclear magnetic resonance imaging of perfluorocarbon compounds.

Nuclear magnetic resonance (NMR) imaging of perfluorocarbon (PFC) emulsions and neat liquids has shown potential for in vivo oxygen imaging in blood and organ tissue. PFC compounds exhibit complicated NMR spectra caused by chemical shifts and spin-spin couplings which can lead to artifacts and degraded spatial resolution of resulting NMR images. To correct for the chemical shift artifacts, the technique of spectral deconvolution has been applied to NMR imaging of PFC compounds. The temporal filter for this process can be directly applied to raw free induction decay data in projection reconstruction or to spin-echo data in two-dimensional Fourier transform imaging techniques. The effect of chemical shift artifacts was demonstrated through the NMR imaging of two PFC compounds (F-tributylamine and F-decalin) in phantoms. Methods are presented and demonstrated which allow the chemical shift artifacts to be removed and true images of the spatial distribution of the PFC's to be recovered.

MR imaging of the lung using liquid perfluorocarbons.

Certain perfluorocarbon (PFC) compounds, commonly used as the oxygen transport components of "blood substitutes," may be breathed as neat liquids with survival because of their chemical inertness and their high solubility for oxygen and carbon dioxide. In addition, the paramagnetism of oxygen reduces the fluorine T1 value according to an inverse relationship allowing a potential method of monitoring PO2 gradients in vivo. This article presents the results of magnetic resonance (MR) imaging of the lungs of mice and rats following breathing of four PFC liquids (FC-43, FC-75, PFOB, APF-215). The images presented were obtained at two magnetic field strengths (0.66 and 0.14 T) under conditions of breathing either ambient air or pure oxygen. Spin-lattice relaxation times (T1) for the PFCs are measured both in vitro and in vivo (in the lungs) as a function of the state of oxygenation. A MR image signal strength enhancement of up to 90% is demonstrated in vivo under conditions of pure oxygen breathing.

Experience with pancreatoduodenectomy in a cancer hospital.

Records of twenty-nine patients with adenocarcinoma of the pancreas, ampulla of Vater, common bile duct, and colon who were treated with pancreatoduodenectomy were reviewed. Operative mortality was 24 per cent. Survival was adversely affected by incomplete excision of the primary lesion, the presence of metastases in lymph nodes, and severe biliary obstruction. Twenty-two patients (76 per cent) died from the operation or were not cured. Pancreatoduodenectomy was of dubious value in the treatment of carcinoma of the head of the pancreas.