Neurotrophic effects of BDNF and CNTF, alone and in combination, on postnatal day 5 rat acoustic ganglion neurons

The effects of encapsulating bovine hemoglobin (BHb) in the bicontinuous cubic phase formed by monooleoylglycerol and water was investigated with Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction. Cubic phase was formed in the presence of 1-10 wt% BHb. Studies using X-ray diffraction reveal that at 0.5-2.5 wt% BHb, the cubic phase structure is characterized by the double diamond lattice (Pn3m). At 2.5-5 wt% BHb, coexistence of two cubic phase structures, Pn3m and the gyroid lattice (Ia3d), was observed while at BHb, concentrations higher than 5 wt% the gyroid structure persists. FTIR shows there is an increase in intensity of the free nu C = O (1745 cm-1) and a corresponding decrease in the intensity of the hydrogen bonded nu C = O (1720 cm-1) as the BHb concentration is increased. The nu C-O-CO peak shifts from 1183 cm-1 to 1181 cm-1 as the concentration of BHb raised from 2.5 to 10 wt% indicating BHb may induce subtle changes in the interfacial region of cubic phase monoolein. The bandwidth of the nu asCH2 stretch (2926 cm-1) increased in the presence of 5 wt% BHb compared to samples with 2.5 or 10 wt% BHb. The increase in frequency of the nu sCH2 stretch (2854 cm-1) induced by increasing temperature 20 to 60 degrees C was dampened when BHb was present compared to samples heated in isotonic buffer. Analysis of the amide I band at 1650 cm-1 showed that the secondary structure of BHb is not affected by encapsulation in monoolein. In vitro release studies showed that 45% of the entrapped BHb was released after 144 h at 37 degrees C. The porous nature of bulk cubic phase was further demonstrated by diffusion of K2Fe(CN)6 and conversion of 73% of the oxyhemoglobin to methemoglobin after 1 h. These results suggest that the cubic phase may be useful for encapsulation of Hb as a red cell substitute and for the encapsulation and delivery of other bioactive agents.     

Pilot experience with the use of an ambulatory geriatric assessment instrument

BACKGROUND: Ten percent of the Chilean population is over 60 years old and general practitioners need an instrument to assess the degree of disability and multiple ailments of elders. AIM: To develop and use an instrument to assess elders consulting in primary care outpatient clinics. PATIENTS AND METHODS: An instrument to be used by general practitioners, aimed to assess bio-psico-social risk of elders was devised by the Geriatrics Program at the Faculty of Medicine of the Catholic University of Chile. The instrument was used in 100 elders (82 female) aged 71 +/- 8 years old consulting in a primary care outpatient clinic. RESULTS: The instrument took less than 5 minutes to be used. The most frequent risk factors found were living alone in 62% of subjects, falls in the last year in 47%, memory disturbances in 62%, overweight in 76%, visual impairment in 76%, urinary incontinence in 26% and depression in 76%. Thirty percent had difficulties to climb stairs and 4% had no support in case of severe disability. CONCLUSIONS: The applied instrument is fast to apply, easily understood by patients and detects problems associated with old age, that will help to plan primary care health programs.     

Serotonin-induced vasoconstriction in rabbit femoral artery: mediation by both 5-HT2 serotonergic and alpha 1-adrenoceptors

We determined the receptors mediating the contractile response of the rabbit femoral artery to serotonin in isolated vascular rings mounted in tissue baths for the measurement of isometric contraction. Serotonin elicited a biphasic concentration-response curve (CRC). The threshold and maximal concentrations of the first phase were 0.03 and 3 microM, respectively. The respective values for the second phase were 10 and 1,000 microM. Benextramine, a selective, irreversible alpha-adrenoceptor antagonist, eliminated the second phase. Similar results were obtained with benextramine in femoral arteries acutely denervated with 6-hydroxydopamine (6-OHDA). In contrast, the reversible, competitive 5-HT2 antagonist ketanserin shifted the first phase of the serotonin CRC to the right ina concentration-dependent manner but had little or no effect on the second phase. No evidence for functional alpha 2-adrenoceptors was found. We conclude that the first phase of the serotonin CRC in rabbit femoral artery was mediated predominantly by 5-HT2 receptors and that the second phase was mediated by alpha 1-adrenoceptors.     

Evidence that mitochondrial respiration is a source of potentially toxic oxygen free radicals in intact rabbit hearts subjected to ischemia and reflow

Previous in vitro studies have shown that isolated mitochondria can generate oxygen radicals. However, whether a similar phenomenon can also occur in intact organs is unknown. In the present study, we tested the hypothesis that resumption of mitochondrial respiration upon reperfusion might be a mechanism of oxygen radical formation in postischemic hearts, and that treatment with inhibitors of mitochondrial respiration might prevent this phenomenon. Three groups of Langendorff-perfused rabbit hearts were subjected to 30 min of global ischemia at 37 degrees C, followed by reflow. Throughout ischemia and early reperfusion the hearts received, respectively: (a) 5 mM KCl (controls), (b) 5 mM sodium amobarbital (Amytal, which blocks mitochondrial respiration at Site I, at the level of NADH dehydrogenase), and (c) 5 mM potassium cyanide (to block mitochondrial respiration distally, at the level of cytochrome c oxidase). The hearts were then processed to directly evaluate oxygen radical generation by electron paramagnetic resonance spectroscopy, or to measure oxygen radical-induced membrane lipid peroxidation by malonyl dialdehyde (MDA) content of subcellular fractions. Severity of ischemia, as assessed by 31P-nuclear magnetic resonance measurements of cardiac ATP, phosphocreatine, and pH, was similar in all groups. Oxygen-centered free radical concentration averaged 3.84 +/- 0.54 microM in reperfused control hearts, and it was significantly reduced by Amytal treatment (1.98 +/- 0.26; p < 0.05), but not by KCN (2.58 +/- 0.96 microM; p = not significant (NS)), consistent with oxygen radicals being formed in the mitochondrial respiratory chain at Site I. Membrane lipid peroxidation of reperfused hearts was also reduced by treatment with Amytal, but not with KCN. MDA content of the mitochondrial fraction averaged 0.75 +/- 0.06 nM/mg protein in controls, 0.72 +/- 0.06 in KCN-treated hearts, and 0.54 +/- 0.05 in Amytal-treated hearts (p < 0.05 versus both groups). Similarly, MDA content of lysosomal membrane fraction was 0.64 +/- 0.09 nM/mg protein in controls, 0.79 +/- 0.15 in KCN-treated hearts, and 0.43 +/- 0.06 in Amytal-treated hearts (p < 0.05 versus both groups). Since the effects of Amytal are known to be reversible, in a second series of experiments we investigated whether transient mitochondrial inhibition during the initial 10 min of reperfusion was also associated with beneficial effects on subsequent recovery of cardiac function after wash-out of the drug. At the end of the experiment, recovery of left ventricular end-diastolic and of developed pressure was significantly greater in those hearts that had been treated with Amytal during ischemia and early reflow, as compared to untreated hearts.(ABSTRACT TRUNCATED AT 400 WORDS)     

Kinetics of subcutaneous versus intravenous epoetin-beta in dogs, rats and mice

The total body clearance of recombinant human erythropoietin (rhEPO) calculated per kilogram of body weight increased in the order man = dog < rat < mouse. The differences disappeared or were reversed when clearance was expressed per square meter of body surface. There was no similar species difference in terminal half life. Total body clearance increased with the dose in dogs and mice, but not in rats. The bioavailability from a subcutaneous depot was 80% in dogs, 76% in rats, and 70% in mice. The absorption from the subcutaneous depot is rapid in rats and mice, but slow in dogs. The pharmacodynamic activity of rhEPO injected by both routes was compared in polycythemic mice. The equipotent doses were 2.44 times higher with intravenous than with subcutaneous injection. Taking into account the bioavailability of 70% from a subcutaneous depot, one obtains a potency ratio of 3.5 for absorbed subcutaneous versus intravenous rhEPO.     

Eye position influence on the parieto-occipital area PO (V6) of the macaque monkey

The aim of this work was to study the effect of eye position on the activity of neurons of area PO (V6), a cortical region located in the most posterior part of the superior parietal lobule. Experiments were carried out on three awake macaque monkeys. Animals sat in a primate chair in front of a large screen, and fixated a small spot of light projected in different screen locations while the activity of single neurons was extracellularly recorded. Both visual and non-visual neurons were found. About 48% of visual and 32% of non-visual neurons showed eye position-related activity in total darkness, while in approximately 61% of visual response was modulated by eye position in the orbit. Eye position fields and/or gain fields were different from cell to cell, going from large and quite planar fields up to peak-shaped fields localized in more or less restricted regions of the animal's field of view. The spatial distribution of fixation point locations evoking peak activity in the eye position-sensitive population did not show any evident laterality effect, or significant top/bottom asymmetry. Moreover, the cortical distribution of eye position-sensitive neurons was quite uniform all over the cortical region studied, suggesting the absence of segregation for this property within area PO (V6). In the great majority of visual neurons, the receptive field 'moved' with gaze according to eye displacements, remaining at the same retinotopic coordinates, as is usual for visual neurons. In some cases, the receptive field did not move with gaze, remaining anchored to the same spatial location regardless of eye movements ('real-position cells'). A model is proposed suggesting how eye position-sensitive visual neurons might build up real-position cells in local networks within area PO (V6). The presence in area PO (V6) of real-position cells together with a high percentage of eye position-sensitive neurons, most of them visual in nature, suggests that this cortical area is engaged in the spatial encoding of extrapersonal visual space. Since lesions of the superior parietal lobule in humans produce deficits in visual localization of targets as well as in arm-reaching for them, and taking into account that the monkey's area PO (V6) is reported to be connected with the premotor area 6, we suggest that area PO (V6) supplies the premotor cortex with the visuo-spatial information required for the visual control of arm-reaching movements.     

Regional myocardial oxygen tension: 19F MRI of sequestered perfluorocarbon

A novel noninvasive method of measuring local myocardial oxygen tension (pO2) in the perfused rat heart using 19F MRI is demonstrated. Tissue pO2 was determined on the basis of the 19F spin-lattice relaxation rate (R1) of perflubron (perfluorooctyl bromide) sequestered in the heart after IV infusion of an emulsion. Spectroscopic measurement of R1 was previously used to measure a global weighted average of oxygen status. 19F MRI now provides 3D spatial resolution indicating local cardiac pO2 under normally perfused, globally ischemic, and regionally ischemic conditions.