Uptake,incorporation and metabolism of (3H)triolein in the isolated perfused rabbit heart

The purpose of these experiments was to study the uptake and metabolism of exogenous triglyceride in the isolated perfused rabbit heart. When infused into the rabbit heart, [9,10-³H(N)]triolein was retained and incorporated into a lipid fraction that had the chromatographic mobility of authentic triolein. Incorporation of labeled triolein was not likely to be the result of a lipoprotein lipase-mediated lipolysis/resynthesis cycle, since: (i) The distribution of radioactivity following administration of [³H]oleic acid was markedly different from the distribution of radioactivity following the administration of [³H]triolein; (ii) heparin was administered to the rabbits at the time of sacrifice; and (iii) the hearts were perfused with a protein-free buffer for 20 min prior to the labelling period. When isoproterenol was administered to hearts labelled with [³H]triolein, there was an increased output of total radioactivity, composed of labelled free fatty acids, diacylglycerol and monoacylglycerol. In these same hearts, there was an increased output of glycerol in response to isoproterenol. However, following the administration of bradykinin or angiotensin II, neither the radioactivity nor the glycerol content of the perfusate was changed. These data suggest that [³H]triolein is selectively incorporated into the triglyceride pool of the isolated perfused rabbit heart. Furthermore, this [³H]triolein is available to hormonally-activated lipolytic enzymes. This work was presented in part at the meeting of the Federation of American Societies for Experimental Biology, Las Vegas, Nevada, May 1988.     

Nasal cerebral heterotopic tissue (nasal glioma) in the adult: a rare cause of primary cerebrospinal fluid rhinorrhea

BACKGROUND: Nasal cerebral heterotopia is a congenital lesion that is mainly detected in early childhood. The rare cases of this disorder found in adult patients are located intranasally. A common symptom is compromised nasal air passage. Clinical findings include polypoid masses in either the nasal cavity or the paranasal sinuses. To our knowledge, primary cerebrospinal fluid (CSF) rhinorrhea has been reported only twice in these patients. PATIENT: A 64-year-old female patient presented with CSF rhinorrhea proven by beta 2-transferrin testing. Previous head injury or intranasal manipulation were excluded. Anterior rhinoscopy revealed a watery drainage from the right middle meatus. CT scan showed a defect in the lateral roof of the right ethmoid sinus, approximately 5 mm in diameter; MRI revealed a mass in the right ethmoid and frontal sinuses, penetrating the anterior skull base. The lesion was resected by an extranasal approach. It showed a fibrous connection to the frontal lobe. Histologically, the lesion consisted of neural tissue composed of gray and white matter, both with a normal structuring. Dura and skull base were reconstructed. There were no signs of a CSF leak postoperatively. RESULTS AND CONCLUSIONS: The differential diagnosis of CSF rhinorrhea includes traumatic events and neoplasms, elevated intracranial pressure, and connate lesions as encephaloceles and, in rare cases, nasal cerebral heterotopia.     

Structure and mechanical behaviour of short glass fibre-reinforced ethylene-tetrafluoroethylene copolymers

A copolymer of ethylene, tetrafluoroethylene, hexafluoropropylene and perfluoropropylvinylether has been investigated. Uniaxial tensile tests at small strains showed improved mechanical properties, when the copolymer was filled with short glass fibres. This is due to a change in superstructure, as can be seen with small-angle X-ray scattering (dynamic measurements during heating with synchrotron radiation). This results in some kind of bonding between matrix and fibres: scanning electron micrographs of fracture surfaces obtained at temperatures between –192 and +160 °C show the bonding as well as the nucleating influence of the fibres on the matrix in their surroundings. Wide-angle X-ray scattering up to 170 °C (made with a Guinier camera) shows that the crystalline structure itself was not influenced by the fibres and that the crystallites in the copolymer were longitudinally disordered to a high degree.     

Distribution of Heavy Metal and Organic Contaminants in Plants and Soils of Windsor and Essex County,Ontario

Concentrations of four contaminants were determined in the soils and plants of Essex County and the city of Windsor in southwestern Ontario. Concentrations of lead and cadmium in county soils were not significantly greater than accepted provincial background levels; average concentrations were 12 mg kg^–1 and 0.38 mg kg^–1 dry soil for lead and cadmium, respectively. Lead concentration in tissues of crop plants was less than 1/4 of that in adjacent soil; cadmium concentration was similar to that in adjacent soil. Concentrations of both metals were significantly higher within the city. Soil lead averaged 44.8 mg kg^–1 and soil cadmium 0.62 mg kg^–1 dry soil. These concentrations correlated significantly with traffic volume on nearby streets. In roots of Chenopodium averages were 18.1 mg kg^–1 for lead and 0.60 mg kg^–1 for cadmium. PCBs were generally undetectable or present only in trace amounts in both soils and goldenrod plants in Essex County. Octachlorostyrene (OCS), while undetectable in soil, was found in leaves at concentrations of about 1 μg kg^–1 in the county. City soils contained higher concentrations of PCBs; average Arochlor 1260 concentration was 13.17 μg kg^–1; OCS was not detectable. Concentrations of both OCS and Arochlors 1254 and 1260 were higher in goldenrod tissues in the city than in parallel county samples. These data suggest limited dispersal of pollutants from urban-industrial sources into the surrounding area.     

Cardiac allograft vasculopathy: a review

Cardiac allograft vasculopathy (CAV) remains a troublesome long-term complication of heart transplantation. It is manifested by a unique and unusually accelerated form of coronary disease affecting both intramural and epicardial coronary arteries and veins.CAV is characterized by vascular injury induced by a variety of noxious stimuli, including the immune system response to the allograft, ischemia-reperfusion injury, viral infection, immunosuppressive drugs, and classic risk factors such as hyperlipidemia, insulin resistance, and hypertension. The obstructive vascular lesions are thought to progress through repetitive endothelial injury followed by repair response. The role of major histocompatibility complex donor-recipient differences in the pathogenesis of CAV has not yet been completely elucidated. Intracoronary ultrasound studies reveal a dual morphology with donor-transmitted or de novo focal, noncircumferential plaques in proximal segments and/or a diffuse, concentric pattern observed in distal segments. A lack of correlation between microvascular and epicardial vessel disease suggests discordant manifestations and progression of CAV. Apoptosis and loss of functional vascular remodeling have to be considered as important mediators of clinically relevant CAV. Strategies for blocking T-cell costimulation and expression of adhesion molecules may help prevent chronic rejection in clinical transplantation. 3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors and antiproliferative drugs may slow progression of CAV by various effects. Methods to augment endogenous nitric oxide bioavailability as well as newer immunosuppressive regimens may be protective. Balloon angioplasty has a limited role in the treatment of focal lesions. Experiences with coronary stenting, coronary artery bypass grafting, and transmyocardial laser revascularization are limited. Retransplantation has a worse outcome than initial transplantation.     

Absorption heat of GHz sound in polycrystalline metal films detected by multiple-beam interferometry and second-sound emission

In the GHz range, sound attenuation in polycrystalline films is dominated by elastic scattering at the grain boundaries. The attenuation by the much smaller absorption is hidden in the whole attenuation. We present a first attempt to detect the absorption. Sound-pulse experiments were done at low temperatures at frequencies of 8.8 GHz and 24 GHz in wedge-shaped Cu and Ag films using the method of multiple-beam interferometry with a lateral movable, highly collimated sound beam. The absorption heat is detected by recording the power of the second sound pulses emitted into the surrounding superfluid helium. The absorption coefficients can be obtained by fitting the measured interferograms to a proposed scattering model. They are many orders of magnitude lower than the measured attenuation coefficients, but are comparable with the predictions of Pippard.     

Oligomers of the cytoplasmic fragment from the Escherichia coli aspartate receptor dissociate through an unfolded transition state

The kinetic and equilibrium properties of a clustering process were studied as a function of temperature for two point mutants of a 31 kDa fragment derived from the cytoplasmic region of the Escherichia coli aspartate receptor (C-fragment), which were shown previously to have a greater tendency to form clusters relative to the wild-type C-fragment [Long, D. G., & Weis, R. M. (1992) Biochemistry 31, 9904-9911]. The clustering equilibria were different for the two C-fragments. Monomers of a serine-461 to leucine (S461L) mutant C-fragment were in equilibrium with dimers, while monomers of a S325L C-fragment were in equilibrium with trimers. The positive values for delta H degree, delta S degree, and delta Cp degree of dissociation estimated from a van't Hoff analysis, and the differences in the CD spectra of isolated monomers and oligomers, demonstrated that the monomers were less well-folded than the clustered forms. The oligomer dissociation rate exhibited a marked temperature dependence over the range from 4 to 30 degrees C and was remarkably slow at low temperatures; e.g. t1/2 of dimer dissociation for the S461L C-fragment was 85 h at 4 degrees C. The values for delta H degree +2, delta S degree +2, and delta Cp degree +2 derived from the temperature dependence of the dissociation rate were comparable to the corresponding parameters determined in a DSC study of C-fragment denaturation [Wu, J., Long, D. G., & Weis, R. M. (1995) Biochemistry 34, 3056-3065], which indicated that the transition state resembled thermally denatured C-fragment. Octyl glucoside accelerated the dissociation rate by 3-5-fold presumably by lowering the barrier to dissociation. This acceleration and the positive value of delta Cp degree +2 were interpreted as evidence for an increase in solvent accessible hydrophobic groups in the transition state. The molecular basis for the slow rate of dissociation is proposed to result from the conversion of intermolecular coiled coils in the oligomers to an intramolecular coiled coil in the monomer.     

Investigation of the structural changes of the neutron irradiated amorphous alloy Fe83B17 by the method of partial radial distribution analysis

The crystallization behaviour of amorphous Fe₈₃B₁₇ alloy after irradiation by thermal neutrons has been studied. The radiation effects on the atomic arrangement have been investigated by X-ray diffraction as well as by electrical resistance measurement. It was found that the crystallization of the alpha-iron was the eminent irradiation effect in the damaged region of the sample.