Stimulus structure in visual persistence: an examination of selective adaptation effects on phenomenal continuity

The effects of adaptation by stimuli composed of the dimensions of color, orientation and size were measured on the visual persistence of a red vertical 3.5 c/d grating. Adaptation by the stimulus that shared an identical level on each of the three-component dimensions of the test stimulus decreased the visual persistence of the test stimulus. There was no effect of adaptation on visual persistence when the adapting stimulus and test stimulus shared an identical level on zero-, one-, or two-dimensional components. The present results extend the investigation of selective adaptation effects on visual persistence by Meyer, Lawson , Cohen, and Maquire to color, size and orientation. In addition, these results are in excellent agreement with Burns' finding that physically integral stimuli are represented in iconic memory as integral unitary wholes and not as dimensional components.

Increased cardiac output following occlusion of the descending thoracic aorta in dogs

Occlusion of the thoracic aorta (AO) in dogs with a constant volume right ventricular extracorporeal bypass increased cardiac output (Q) by 43% and mean arterial pressure by 46%, while mean systemic pressure (MSP) was unchanged. We compared AO with occlusion of the brachiocephalic and left subclavian arteries (BSO) which decreased cardiac output by 5%, increased mean arterial pressure by 32%, and increased MSP by 11%. We feel these results confirm that AO elevates preload by transferring blood volume from the splanchnic veins to the vascular system drained by the superior vena cava. If the heart is competent to keep right arterial pressure at or near zero, this increase in preload will elevate Q above control levels. Comparing our data with results of other authors who have not controlled right atrial pressure, emphasizes the importance of a competent right ventricle in allowing venous return to determine Q.

Changes in lung membrane diffusing capacity for oxygen produced by halothane

The effect of halothane on membrane diffusing capacity for O2 (DMO2) was measured in isolated left lower lobes of dog lungs using the sodium dithionite method. At 25 degrees C, halothane reduced DMO2 according to the regression equation: per cent control DMO2 = -4.85(per cent halothane) + 97.5 (r = -0.55, P = 0.0007). Although DMO2 was reduced from control by halothane administration, lung volume (VL) increased at higher halothane concentrations and tended to restore DMO2 by increasing surface area. There was a better correlation between the DMO2/VL ratios and per cent halothane: per cent (DMO2/VL) = -5.76 (per cent halothane) + 95.6 (r = -0.65, P = 0.00003). Effects of halothane on DMO2 and VL were reversible and were not influenced by gas mixing efficiency since argon dilution half-times over two decades were unchanged by halothane. It is unlikely that altered vascular recruitment affected the measured DMO2 since resistance to blood flow was unchanged. We conclude that halothane decreases DMO2 by either decreasing the physical diffusion coefficient (D') for O2 or decreasing the effective O2 solubility (alpha), or both, in the alveolar-capillary membrane.

Interactions between placental O2 and CO transfer

In 14 pregnant ewes the fetal side of the placenta was artificially perfused with adult sheep blood or with an emulsion of the fluorocarbon FC-47 containing varying amounts of CO. We measured diffusing capacities for O2 and Ar and permeability for urea and tritiated water (3H2O). We found that O2 diffusing capacity fell markedly in the presence of low levels of CO but that AR diffusing capacity and the permeability of urea and 3H2O remained constant at different levels of exposure to CO. We interpret the results as being consistent with the hypothesis that placental O2 transport is partially carrier mediated and that O2 and CO compete for the same carrier.

A comparison of laterality indices in college and retarded subjects

The relation of laterality to intelligence was assessed by administration of Berman's ICD (Index of Cerebral Dominance) to 20 male and female college students and 20 retarded Ss (IQs 33-75) of comparable age and sex. The college Ss were more lateralized in hand, foot, ear, and eye, but it was primarily foot lateralization that distinguished the groups, despite the fact that hand was the most lateralized subsystem in both groups. While these results are not entirely consistent with Berman's, they are generally confirmatory of a positive relation of laterality and intelligence.

Morphologic features of prognostic significance in uterine smooth muscle tumors: a review of eighty-four cases

Independent microscopic review of the most cellular and pleomorphic areas of 84 smooth muscle tumors of the uterus by two pathologists yielded 23 leiomyosarcomas, 43 cellular leiomyomas, 16 bizarre leiomyomas, and two intravenous leiomyomas. Greater than 5 mitotic figures/10 high-power fields (hpf) correlated with malignant clinical behavior, but this occurred in only 75% of the leiomyosarcomas. Five cases with fewer than 5 mitoses/10 hpf pursued a malignant course. The mean age of the patients with malignant tumors (52.5 years) was similar to the mean age of those with bizarre leiomyomas (48.0 years) but those patients with cellular leiomyomas were significantly younger (42.0 years; p less than 0.01). Gross evidence of extrauterine extension was diagnostic of malignancy as was vascular invasion by anaplastic tumor. Fifteen of the 19 patients with leiomyosarcoma died of disease at an average of 28 months postoperatively. Inadequate sampling and interobserver variation are discussed.

DLO2 in excised lungs perfused with blood containing sodium dithionite (Na2S2O4)

If the excised lung is perfused with blood containing the chemical sodium dithionite (DDT), the PO2 of pulmonary capillary blood is everywhere zero and the membrane diffusing capacity for O2 (DmO2) can be measured by a standard rebreathing technique. The reaction rate of DDT with O2 is not rate limiting in the DmO2. In 15--25 kg dogs anesthetized with pentobarbital sodium (30 mg/kg, iv), left lower lobe was excised, suspended horizontally and perfused with autologous blood at 25--27 degrees C. DDT was added to the blood and the rebreathing alveolar disappearance curves for O2 were measured. The DmO2 ranged from 6 to 43 (ml/min.Torr, STPD) at lung volumes of 240--780 ml (FRC at 6 cmH2O end-expiratory pressure). Lung weight, pulmonary artery pressure, and the DmO2 were stable in the presence of DDT. Histopathology indicates that dithionite in the concentrations used does not harm the lung. Effects of inequalities in the distributions of ventilation, volume, and diffusing capacity were examined in a two-compartment model and compared with the experimental findings.

Evaluation of the central canal of the spinal cord in experimentally induced hydrocephalus

The central canal of the spinal cord has been proposed as a significant compensatory alternative pathway of cerebrospinal fluid (CSF) flow in hydrocephalus. Ten dogs were made hydrocephalic by a relatively atraumatic experimental model that simulates the human circumstance of chronic communicating hydrocephalus. The central canal was studied by histopathology and compared with 10 normal control dogs. In both groups the central canal of the spinal cord was normal in size, configuration, and histological appearance. In this experimental model dilatation of the canal and increased movement of CSF does not appear to be a compensatory alternative pathway.

Saturation kinetics for steady-state pulmonary CO transfer

Steady-state diffusing capacity of the lungs for carbon monoxide (DLCO) was measured in 13 anesthetized, paralyzed dogs ventilated at constant tidal volume and rate, using four different inspired CO levels (190, 600, 1,110, and 2,000 ppm). DLCO increased and reached a maximum as the inspired CO level was raised from 190 to 600 ppm. Further increases in inspired CO concentration were accompanied by a decrease in inspired CO concentration were accompanied by a decrease in DLCO. CO dead space and Pao2 remained constant at all inspired O2 levels. In some experiments a second set of measurements was made, the results of which were similar to those of the first set. The results cannot be explained by changes in CO back pressure, pulmonary capillary volume, or reaction rate of CO with hemoglobin, but can be explained if there is carrier-mediated CO transport in the alveolar capillary membrane.

The production of cerebrospinal fluid in experimental communicating hydrocephalus

Utilizing an atraumatic model to produce chronic hydrocephalus, CSF production was measured during and after development of communicatin hydrocephalus. CSF volume production was significantly lower in animals with increased pressure. Animals with chronic hydrocephalus and normal pressures had abnormal CSF production. Diminished CSF production appears to offer a potential compensatory mechanism when CSF absorption is altered.

The Wien effect in compensated metabolic acidosis

CSF and blood acid-base values were measured in compensated metabolic acidosis, induced in anesthetized dogs by infusion of dilute HCl during hyperventilation. We observed cerebral blood flow-related steady-state differences in PCO2 between CSF and arterial venous blood from the brain. The steady-state values of CSF-blood PCO2 differences and blood H+ activity were intermediate to those observed by us previously during uncompensated acidosis and alkalosis (J. Appl. Physiol. 34: 249-254, 1973). These results are consistent with predictions of the "charged membrane hypothesis" proposed by us to explain CSF and blood acid-base relationship during uncompensated acid-base derangements (J. Appl. Physiol. 34: 243-248, 1973).

Evaluation of cerebrospinal fluid production in the development of communicating hydrocephalus

Diminished absorption of cerebrospinal fluid (CSF) is the most common cause of communicating hydrocephalus. Soon after the absorptive capacity is decreased, the CSF pressure increases, producing ventricular enlargement if the process is not halted. CSF production was measured by ventriculo-cisternal perfusion during and after the production of communicating hydrocephalus, using an atraumatic animal model. Animals with chronic hydrocephalus and normal pressure had normal CSF production. CSF production tended to be lower in animals with increased pressure. When CSF absorption is compromised, decreased CSF production does not appear to be a significant compensatory mechanism.

Mianserin hydrochloride: a novel antidepressant

The antidepressant activities of mianserin hydrochloride were investigated and compared with those of amitriptyline. The therapeutic efficacy of the two drugs appeared similar, but the incidence of side-effects was significantly higher with amitriptyline. Plasma levels of mianserin were determined during the trial and were not related to the therapeutic activity of the drug.

Activating posthypnotic conflict: emergent uncovering psychopathology repression, and psychopathology

An attempt was made to observe the process of repression and symptom formation. Emergent uncovering techniques were used to weaken a spontaneous repression that was produced by the posthypnotic activation of sexual impulses stemming from an implanted oedipa paramnesia. Twelve hypnotic and ten simulating subjects were used in a modified real-simulator design. Although it was not possible to 'lift' the spontaneous repression of derivatives of oedipal strivings in the course of uncovering via visual imagery, a wide variety of spontaneous symptoms were produced in the hypnotically conditioned subjects. The type of symptom was shown to be related to the degree of repression. Simulating subjects produced only a few symptoms. The manifestation of a symptom was concomitant with an increase in the GSR, but not the blatancy of drive representation. These findings were consistent with the phenomena observed using free imagery in emergent uncovering psychotherapy.

Physiological evidence consistent with the presence of a specific O2 carrier in the placenta

In 30 experiments we perfused the fetal side of the sheep placenta with fluids which had different solubilities for argon, N2, and O2 (dextran, blood, and fluorocarbon emulsions). In some of the experiments we partially exchange-transfused the ewe with the fluorocarbon emulsion. By these procedures we were able to change the physical solubility of argon and N2 severalfold in the fetal perfusion fluid and maternal blood. We found that the diffusing capacity for argon and N2 did not increase with increases in physical solubility in the fetal perfusion medium or in maternal blood. This indicated that the rate-limiting step in the placental transfer of these gases is the small diffusing capacity of the placenta. In contrast, O2 diffusing capacity increased markedly with increased solubility in the fetal perfusion medium. Also the Po2 was frequently the same in the venous blood leaving both sides of the placenta. This indicates that O2 may reach equilibrium between maternal and fetal capillaries in one pass through the placenta. The results are compatible with the presence of specific O2 carrier in the placenta.

Pathophysiology of chronic communicating hydrocephalus in dogs (Canis familiaris). Experimental studies

A model designed to produce chronic communicating hydrocephalus in dogs has been developed in our laboratory. The animals tolerate the procedure well and the yield of animals with communicating hydrocephalus is high. Serial cisternograms show ventricular entry first with "clearing" and later with "stasis". CSF pressures are initially increased, but when the ventricles become enlarged the pressure falls into the normal range. Grossly there is generalized ventricular enlargement and, on histological studies, the ependyma is flattened and denuded. Periventricular edema occurs in the white matter. Autoradiographs show transependymal movement of protein. CSF production appears to be normal despite obstruction to flow of CSF to areas where resorption is greatest. Diversionary shunting probably produces relief of many of the neurological symptoms by providing an efficient pathway for the removal of CSF and thus by lessening edema and ventricular enlargement. A more appropriate treatment would appear to be a noninvasive method of decreasing CSF production. Only when the basic pathophysiological alterations of CSF production and absorption are understood will this be possible. We believe that this animal model affords us the opportunity of studying these mechanisms.

Cerebrospinal fluid pressure measurements and radioisotope cisternography in dogs

Cerebrospinal fluid pressure measurements and radioisotope cisternograms were made in 16 mongrel random-source dogs (beagle breed excluded) as a screening technique in developing an experimental animal model for communicating hydrocephalus. Cerebrospinal fluid pressure measurements were made by puncturing the cisterna magna with a spinal needle through which the radiopharmaceutical was also subsequently injected. The mean cerebrospinal fluid pressure was 117 mm water, and the incidence of hydrocephalus was found to be rare. Cisternographic flow patterns also indicate that cerebrospinal fluid flow and absorption in dogs differs from that found in man.

Microvolt electric signals from fishes and the environment

Pulses in the 0.01 to 40 microvolt range, probably generated by white fiber muscle action potentials, were remotely received through dipole antennae from five fishes and one amphibian in aquarium tests. In natural environments, however, no biologically generated signals have been detected. Received instead were a multitude of similar signals originating from unknown sources. The dominant types of these "atmospheric" signals and their reception rates change diurnally and can easily be confused with the fish-generated signals.