Temperature and species differences in susceptibility of kidney cell cultures to mercury toxicity

Summary The effect of temperature on inorganic mercury toxicity was investigated using kidney tissue culture systems. The relative susceptibility of rabbit (homeothermic) kidney to mercury intoxication was compared to that of Coho salmon (poikilothermic) kidney over temperature ranges consistent with the habitat of each of the two species. It was demonstrated that susceptibility to mercury toxicity is species dependent; that is, the rabbit kidney cells tolerated higher mercury concentrations in the medium than did the fish-derived cells. Within a given species, susceptibility to mercury toxicity was temperature dependent. Decreasing the temperature increased the toxicity of mercury to cultures of rabbit kidney cells, whereas decreasing temperatures decreased the effect of mercury toxicity on the salmon kidney cells. As a consequence, fish taken from arctic waters are liable to be more toxic when introduced into mammalian food chains. Albumin was shown to act as a protective agent in vitro against inorganic mercury toxicity. Research was supported in part by the University of Victoria Faculty Grant No. 08-869 and a Medical Staff Research and Education Fund Grant from Wayne County General Hospital, Eloise, Michigan.     

Improving recognition of respiratory sensations in healthy adults

In two discrimination training studies, we noted improvements in the ability of healthy individuals to discriminate between respiratory sensations. We trained individuals to discriminate between respiratory sensations elicited during inspiration in Experiment 1 and during expiration in Experiment 2. We elicited respiratory sensations by having participants breathe through circuits that differed in their resistance to air flow. Training, in both experiments, was conducted within the context of a task in which individuals judged which member of a series of respiratory circuit pairs was easier to breathe through. To improve the accuracy of judgments, we gave participants feedback of their performance, and we faded air flow resistance. The latter procedure consisted of presenting circuit pairs in order of increasing similarity. Individuals who received performance feedback with fading of air flow resistance demonstrated reliable improvements in discrimination from pre- to posttraining in both experiments, but controls, who received either performance feedback or practice in discrimination did not. These findings may contribute to improving awareness of respiratory sensations in asthma patients, and thereby bolster efforts to manage asthma.This research was supported by a Biomedical Research Support Grant from the National Institute of Health to Ohio University and by an Academic Challenge Grant from the State of Ohio to the Ohio University Psychology Department.     

Direct connections between mitochondria and catecholamine-storage vesicles demonstrated by high voltage electron microscopy in rat adrenal medulla

Summary Tubular channels from mitochondria to catecholamine-storage vesicles have been demonstrated in thick sections of adrenal medullary tissue from hypoglycemia-stressed rats by the use of the high voltage electron microscope. The function of these connections is not presently known although they may serve as channels for the transport of materials such as high-energy nucleotides from one organelle to the other. The present study has examined only the adrenal medulla, but it should be considered that such connections may also exist in other neural cells and possibly other cells in which there is intracellular transport of ATP.This work was supported by NIH DRR 70-4136, WVU Medical Corporation Research Grants, Biomedical Research Support Grant 5 SOI RR05433, WVU Senate Research Grant, and West Virginia Heart Association Research Grant. We wish to thank Barbara Coalgate, Billie Pack, and the staffs of the HVEM laboratories at U.S. Steel and University of Colorado.     

Common source epidemics II: Toxoplasmosis in Atlanta

A discrete time stochastic model formulated for the study of common source epidemics (Shonkwiler and Thompson, 1982) is implemented to study an outbreak of toxoplasmosis in Atlanta, Georgia, in 1977. A computer simulation program is described and conclusions are drawn on the basis of the simulations. Also, the detailed empirical data are organized to illuminate the roles of visitation and location patterns, and the variation in the empirical epidemic curve with different reporting schemes. This work was partially supported by BRSG Grant S07 RR07031 awarded by the Biomedical Research Support Grant Program, Division of Research Resources, National Institutes of Health.     

Biofeedback of alveolar carbon dioxide tension and levels of arousal

This is a preliminary study designed to investigate the potential usefulness of alveolar (lung) CO₂ feedback training in promoting sleep onset in primary insomniacs. The present study was undertaken to determine if normal subjects could, without obvious manipulation of breathing, bring alveolar (lung) CO₂ tension under voluntary control using biofeedback techniques and, if so, whether this control would be accompanied by shifts in level of wakefulness. Subjects participated in five baseline and five training sessions in which EEG, alveolar CO₂ tension, and thoracic/abdominal respiratory movement were monitored. The feedback consisted of a pitch-modulated tone plus visual scores. We found that CO₂ tension in awake portions of up trials was significantly higher than for awake portions of down trials (p<.01), indicating that learning had occurred. In the initial trials, when subjects raised CO₂ tension they became drowsy and often fell asleep, and when they lowered CO₂ tension they aroused themselves. However, when subjects were awakened immediately upon falling asleep, there developed a decoupling of EEG and CO₂ changes. The presence of such a decoupling phenomenon makes it unclear whether CO₂ feedback will be useful in promoting sleep onset in primary insomniacs.This study was supported by National Institute of Mental Health Research Fellowship MH05151, Research Grant MH29369, Research Scientist Development Award MH38897, and by a Biomedical Research Support Grant to Langley Porter Institute, 507RR05755.     

The effects of multiple reflex pathways on the oscillations in neuro-muscular systems

Summary A model of mammalian neuro-muscular systems described previously (Ouztöreli and Stein, 1975) has been extended to include multiple reflex pathways, as have been shown to exist in primates, including man (Milner-Brown et al., 1975). A number of general mathematical properties of the extended system are described. In the final section, using computer solutions, it is shown that the presence of multiple reflex pathways can effectively reduce the tendency for oscillation which will exist if high reflex gain were concentrated in a single pathway. High loop gain is desirable for good control in any negative feedback system, so the presence of multiple reflex pathways could improve reflex control, while limiting the magnitude of tremor or other unwanted oscillations in neuromuscular systems.This work was partly supported by the National Research Council of Canada (Grant NRC-A4345) and by the Medical Research Council of Canada (Grant MRC-MA 3307) through the University of Alberta.     

Conflicting results in EEG alpha feedback studies

Success or failure of EEG feedback training for alpha enhancement can depend on how alpha activity is quantified and fed back. Alpha-enhancement failures usually employ a percent time(%) technique; successes typically use amplitude integration(). To dramatize the differences between percent and integration techniques, we derived both measures simultaneously from left occipital(O ₁ ) and left central(C ₃ ) sites for 16 male subjects who were given 5.6 hours of integrated alpha feedback from the midline occipital(O_z ) site. At both the O ₁ and C ₃ sites the integrated and percent measures were not equivalent and not linearly related. Statistically significant differences in the(integrated, percent) correlation coefficients(z-transformed) were observed under the different recording conditions: alpha enhancement, alpha enhancement, alpha suppression, and baselines. Theoretical discussion of integration and percent techniques is given and the adoption of amplitude integration measures and feedback stimuli is strongly advocated.This study was supported by the following grants and contracts: National Institute of Mental Health (NIMH) Predoctoral Fellowship #1 F01 MH51704-01, NIMH General Research Support Grant #LPNI 185, and a Langley Porter Neuropsychiatric Institute Postdoctoral Fellowship (Interdisciplinary Training Program, NIMH #7082) to James V. Hardt, and by NIMH Research Scientist Development Award 2K02 MH38897, NIMH Research Grant #1 R01 MH24820, Office of Naval Research (ARPA) Contract N00014-70-C-0350, and Instruction and Research Funds, Computer Center Accounts (UCSF) #1431 and #1437 to Joe Kamiya.     

Linkage relationships of biochemical markers to Q- and C-band variants in a large black kindred

Summary Lod scores are reported for 86 biochemical to cytogenetic marker comparisons in a Black kindred. Analysis with unconfirmed locus assignments resulted in 12 exclusions of close linkage.This paper is based on a thesis submitted by the senior author in partial fulfillment of the Ph.D. degree at North Carolina State University, Raleigh.Research supported by the National Heart and Lung Institute Grant HLO-3341, National Institute of Mental Health Grant MH 26621, and National Institute of General Medical Sciences Grant GN 16697; paper number 6281 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, North Carolina.     

The treatment of psychophysiologic insomnia with biofeedback: A replication study

To replicate a previous study, 16 psychophysiological insomniacs were randomly assigned to either Theta feedback or sensorimotor rhythm (SMR) feedback. Evaluations by home sleep logs and by 3 nights in the laboratory were done before biofeedback, immediately after biofeedback, and 9 months later. Results from this study replicate previous findings. Both Theta and SMR feedback seemed effective treatments of insomnia according to home sleep logs. According to evaluations at the sleep laboratory, tense and anxious insomniacs benefited only from Theta feedback but not from SMR feedback, while those who were relaxed at intake but still could not sleep benefited only from SMR but not from Theta feedback.This research was supported by Grant No. MH24268 from NIMH. The authors would like to thank Michael Sateia, Elaine Olmstead, Molly Oldfield, and Boyd Hayes for their assistance with this paper.     

Effect of atrazine in combination with captan or thiram upon fungal and bacterial populations in the soil

Pesticides were added to soil at a rate of 10 mg/kg and then planted with corn, wheat, or bean seeds. Captan and thiram caused an initial decrease in the fungal populations but by 108 days the populations returned to levels found in untreated soils. The bacterial populations fluctuated inversely with the fungal populations. In soil planted with corn, atrazine had no effect on the microbial populations, however, in soil containing wheat and beans, populations of fungi and bacteria increased. Stimulation of the microbial populations in the atrazine-treated soils was attributed to the decay of the dead wheat and bean plants. Atrazine in combination with captan or thiram had neither synergistic nor antagonistic effects on the microbial populations. This study was supported by Public Health Service Research Grant No. CC 00284, from the National Communicable Disease Center, Atlanta, Georgia. This study was supported by Public Health Service Research Grant No. CC 00284, from the National Communicable Disease Center, Atlanta, Georgia.     

Contingently faded heart rate biofeedback: Attempted replication of large-magnitude decreases

McKinney et al. (1980) reported large-magnitude reductions in heart rate (HR) from resting baseline levels, employing shaping and fading techniques and a reinforcement program in which a secondary reinforcer was awarded both contingently and immediately during training. The four male subjects in this group showed significantly greater HR decreases than a group of four males receiving beat-by-beat analogue HR feedback. The present study compared decreases in HR in 20 male subjects receiving the contingently faded biofeedback procedure to those shown by 10 male subjects for whom reinforcement was contingent on vigilant observation of a visual display, and independent of HR. The former group showed significantly greater decreases in HR that could not be attributed to elevated baseline levels. However, the decreases in HR were not as large as those reported by McKinney et al. (1980). It is argued that future research should assess variables contributing to individual differences in performance.This research was supported by Ontario Heart Foundation Research Grant 15–37 to R. Pavloski.     

Diffusion-driven instability in a predator-prey system with time-varying diffusivities

We consider an ecological model by Levin and Segel (1976) for predator-prey planktonic species, which consists of two reaction-diffusion equations, and extend it to plankton populations with time-varying diffusivities. The local stability of uniform equilibria is examined both analytically and numerically. It is found that diffusive instability is less likely to occur in systems with time-varying diffusivity than those with constant diffusivity. Contribution No. 803 of the Marine Sciences Research Center, State University of New York, Stony Brook Supported by the Danish Science Research Council (Grant nos. 11-7128, 11-8321), the Danish Research Academy (Grant nos. E-880011, V-890085) and a Travel Grant for Mathematicians (Rejselegat for Matematikere) Supported by Hudson River Foundation, Grant no. 01488AO37     

Common source epidemics I: A stochastic model

A discrete time stochastic model is formulated for the spread of a disease which is transmitted to an uninfected but susceptible individual through an environmental source and not through contact (either direct or indirect) with infected individuals. The model incorporates both exposure and infection components. The exposure component includes consideration of the introduction of an infectious agent into the environment and the subsequent diffusion of the agent. It also includes time and location patterns for visits by individuals in the target population to the affected environment. The infection component incorporates physiological responses of exposed individuals to the infectious agent. The goal of the model is to provide a method for developing a predicted epidemic curve. Comments are given on an application of the model to the study of an outbreak of toxoplasmosis in Atlanta, Georgia, in 1977. This work was partially supported by BRSG Grant S07 RR0731 awarded by the Biomedical Research Support Grant Program, Division of Research Resources, National Institutes of Health.     

The effects of electromyographic feedback training on suppression of the oral-lingual movements associated with tardive dyskinesia

The efficacy of electromyographic feedback training in reducing the magnitude and frequency of the oral-lingual movements associated with tardive dyskinesia (TD) was investigated in a groups design. Twenty adult male inpatients diagnosed as having TD using the Abnormal Involuntary Movements Scale (AIMS) were randomly assigned to one of two treatment conditions. Following identification, all participants were initially reduced to the lowest effective dosage of neuroleptics, and then discontinued from anticholinergics. Following one month on this regimen, they were given a course of feedback training consisting of ten 14-minute sessions. Group one participants were provided with a tone contingent upon oral-lingual movements above a yoked threshold. Group two participants were given noncontingent feedback tones generated randomly. Weekly AIMS were administered as well as an initial baseline during each session to determine current level of oral-lingual activity. An analysis of session effects indicated significantly more suppression of oral-lingual activity in the contingent group versus the noncontingent feedback group. Jaw and forehead activity also measured showed reductions of similar magnitudes for both groups.This work was sponsored in part by a Research Advisory Grant from the Department of Veterans Affairs awarded to Joanne Intrator. We gratefully acknowledge the valuable contributions of K. Duvvi, S. Kemble, and L. Kolman.     

Inhibition of dark repair of ultraviolet damage in DNA by caffeine and 8-chlorocaffeine. Kinetics of inhibition

Summary The inhibition of dark repair by caffeine and 8-chlorocaffeine was investigated by a cellular enzyme kinetics system. The results suggest that the caffeine and 8-chlorocaffeine act by inhibiting the excision enzyme of the dark repair system.This work was supported by National Insitutes of Health Research Grant AI-05340, the University of Kansas Research Fund, and N.I.H. Training Grant 5 T1 GM-73.     

Application of optimal multichannel filtering to simulated nerve signals

The optimal linear filters derived in the preceding paper can be thoroughly evaluated using computer simulations, based on the properties of mammalian sensory and motor nerve fibres. Using reasonable values for action potential waveforms, conduction velocity and electrode noise, good separation of motor and sensory signals can be obtained. The performance of the filters is degraded by 1) increasing the electrode noise, 2) introducing dispersion in the conduction velocities, or 3) variation in the waveform of the action potentials from that used in designing the filters. However, the variations needed to seriously degrade performance are quite large compared to those which are likely to be present in mammalian nerves. Use of these filters to distinguish different classes of sensory (or motor) signals based on conduction velocity is discussed.This work was partially supported by the Technical Research Council of Denmark (Grant 516-6703.E406), the Medical Research Council of Canada (Grant MRC-MT3307) and the National Research Council of Canada (Grant NRC A-4345)     

Evoked potentials in artificial neural nets

A neural net model of discrete populations of formal neurons have been constructed to study evoked potentials based on our previous simulation studies (Anninos, 1972). Some interesting results came up from the examination of our findings regarding the latencies and the period of the cyclic activity of the evoked potentials. In fact, the different successive latencies for the five identical stimuli and the different periods for each of the cyclic activities, all are consequences of inhibitory and excitatory influences from a large neuronal population. Furthermore, such behavior of the system is not only related to the unknown neuronal population but was also substantially altered by what occurred in other systems at the time of stimulus, or prior to it.Computation assistance was provided by the Health Sciences Computing Facility, UCLA, sponsored by NIH Special Research Resources Grant RR-3. Research was sponsored by NSF Grant GB 30498 and NIH Grant NS-8498.     

An improved method forin vitro cultivation of murine splenic macrophages

This investigation is supported by Research Grant AI-21897, National Institutes of Allergy and Infectious Diseases (NIH).     

Golgi impregnation with mercuric chloride: studies on the precipitate by X-ray powder diffraction and selected area electron diffraction

Summary An investigation was carried out to determine the nature of the precipitate in a technique which was originally proposed by Golgi and, later, modified by Cox, to stain nerve cells by the treatment of tissue with potassium dichromate and mercuric chloride.The approach was a twofold one: the study of the patterns of X-ray diffraction of successfully impregnated tissue and the analysis of electron diffraction patterns of selected areas of tissue where impregnated structures were observed.Evidence has been obtained that the precipitate, prior to the final alkalinization process, is mercurous chloride (calomel, Hg₂Cl₂). There appears to be no formation, at any time, of mercurous or mercuric chromate. The mercurous chloride is topographically associated exclusively with the presence of stained structures and cannot be detected in the non-stained background.Following the alkalinizing process necessary for the final darkening of the stained structures, the X-ray diffraction pattern of mercurous chloride usually was no longer detectable. It appears reasonable to assume that, when no crystalline compounds can be detected, metallic liquid mercury is formed.This study was supported by U.S. P.H.S. Grant NS 07998 and by the Medical Research Council of Canada. We are indebted to Mrs. K. Sörensen and Mr. A. Meier for technical assistance.