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Biomedical subjects

V D Deshmukh

Publications and source records attributed to V D Deshmukh.

At least 19 recordsLinked to original sources
PubMed1992

Subclinical cognitive deficits in cancer patients: a preliminary P300 study.

A preliminary study of event related potentials (P300) in a group of 16 cancer patients, without cerebral metastases or focal neurological deficits, is being reported. As compared to a group of 28 normal adults, 9 out of 16 cancer patients were found to have prolonged P300 latencies, and 6 made more than two errors in their cognitive performance. These subclinical cognitive impairments in cancer patients may be related to some remote effects of cancer. These patients had not undergone any chemotherapy or radiation therapy prior to P300 studies. Further studies in a larger group of patients with gynecological cancer are being conducted.

Adolescent↗
PubMed1991

Cascading morphoregulatory energy and the biological form: theory and reality.

It is proposed that biological forms are not determined by a single molecule or a single process but by multiple forms of energies, acting on a network of molecules. The molecular organization of biological form is determined by not only its molecular composition but also the different forms of internal and external energies acting on those molecules. A concept of cascading morphoregulatory energy is proposed which is defined as the quantal, differential energy--total internal minus total external energy--that acts on the biological form at a given moment in time. It is a quantal composite form of energy consisting of chemical, electromagnetic and phononic or quantum fluid mechanical energy. It is further proposed that biological forms are extremely dynamic and are constantly dominated by internal and external flow-induced fluid forces and energy patterns. Some of the well known variables that influence these fluid patterns include internal and external temperature, salinity, proton and other ionic gradients, surface tension, hydrostatic pressures and organic compositions. A biological process and its products form a unit. A biological process serves as a source and its products are subject t] local dispersive fluid forces constrained by chaotic streamlines. The process and products together form a unitary biological form. The biomolecular fluid patterning seems to follow curvilinear geometry. On the basis of these general principles computer simulations of most biological structures seem to be feasible. This would provide a good beginning for the physical modelling of biological forms.

Acoustics↗
PubMed1991

Limbic autonomic arousal: its physiological classification and review of the literature.

The object of this article is to present a novel physiological classification of Limbic-Autonomic (LA) arousal on the basis of human physiological data, specifically the oro-nasal breathing patterns in man. It is proposed that the multidimensional LA arousal can be classified into five grades: Grade I: Non-nasal (NN) or oral breathing with bilateral nasal congestion, and nonactive behavior, Grade II: Left Nasal (LN) breathing and quiet behavior, Grade III: Right Nasal (RN) breathing and active behavior, Grade IV: Bilateral Nasal (BN) breathing and very active behavior, and Grade V: Oral and Bilateral Nasal (ON) breathing with maximal behavioral activation. The data from polygraphic electroencephalographic recordings from five healthy volunteers, before, during and after exercise are presented in support of this physiological classification of LA arousal. On the basis of Limbic-Autonomic asymmetry a novel concept of "Visceral Dominance" is also proposed.

Arousal↗
PubMed1991

Physiological classification of sleep-wake states: based on tri-vesicular (3V) model of the brain.

A new physiological classification of sleep-wake states, based on a novel Tri-Vesicular (3V) model of the brain is proposed. The 3V model consists of an interconnected network of three primal brain vesicles, namely, right and left Arch-Encephalon (Mesencephalon + Diencephalon + Telencephalon) and one DeuterEncephalon (Metencephalon + Myelencephalon). Nine sleep-wake states are defined on the basis of the central activational index (activation and/or inhibition of the 3 brain vesicles), and the level of global arousal. Four sleep states I-IV, four wake states I-IV, and one transitional sleep-wake state, are characterized. The four sleep states correspond with the four non-REM sleep stages, the transitional sleep-wake state correlates with REM sleep, and four wake states are defined in terms of minimal, low, moderate, and high, global behavioral arousal. Three sets of data in the form of polysomnographic and aerobic exercise studies in five adult subjects, and 30 days' data of self-monitored arousal and oro-nasal breathing patterns, are provided in support of this physiological classification of sleep-wake states and the 3V brain model.

Adult↗
PubMed1990

Stress-adaptation failure hypothesis of Alzheimer's disease.

It is proposed that the higher incidence of chronic stress-adaptation failure in patients with Alzheimer's disease is of specific etiopathological significance. Such chronic stress-adaptation failure leads to a vicious circular reaction, namely: intense, stressful stimuli----neocortico-limbic excitation----hypothalamo-pituitary-adrenocortical (HPA) axis activation----excessive secretion of neurohormones including cortisol----stimulation of inhibitory glucocorticoid sensitive hippocampal neurons----failure to terminate the HPA axis response----chronic excessive secretion of neurohormones including cortisol----overstimulation degeneration of glucocorticoid sensitive hippocampal inhibitory neurons----progressive cognitive-affective behavioral disorganizational failure which is typical of dementia of the Alzheimer's type. Possibilities of neuropharmacological corrections and neurobehavioral re-education are suggested.

Adaptation, Physiological↗
PubMed1989

Logistic patterning of brain activity.

Brain activity is a set of electrochemical events in the neural tissue during a specified period of time. Neural networks are the functionally connected and dynamically organized population of neurons and neuroglial cells, serving as a unified interface between environmental input and behavioral output at a specified time. They are patterned dynamically in neural space, time and intensity. It is proposed that 1. the electrophysiological patterning of brain activity follows the laws of logistic growth, decay and impulse response function and 2. that this process of logistic transform (LOGIT) of electrochemical processes is itself the general code of information transfer in the brain. A mathematical model of logistic transformation and new electrophysiological data based on the topographic mapping of event-related potentials (ERP) during selective auditory attentional tasks from nine healthy adults is presented. The N100-P200 and the N200-P300 segments of ERP's were analyzed at 20 ms intervals. Logarithmic latencies and voltages were highly correlated. Significant correlation was found between the mathematically estimated and actual values. The interpeak latencies also followed the logistic growth pattern and could be predicted by the model. A general equation of logistic transformation of brain activity, including variables of cortical voltage and frequency is proposed.

Adult↗
PubMed1988

A chain of suprasegmental neuroscillatory circuits: a human brain theory.

A novel electrophysiological model of human brain electrical activity and functions is proposed. It views the human central nervous system as a chain of three suprasegmental neuroscillatory circuits, namely prosencephalic, mesencephalic, and rhombencephalic. Each circuit consists of a network of periventricular paracrine core neurons, efferent motor plate neurons, and sensory-associative alar plate neurons mediating suprasegmental electroclinical phenomena. The model is based on the exponential analyses of well established human data from the fields of electroencephalography, evoked potentials, wake-sleep spectrum, stages of anesthesia, and a variety of human tremors. This neuroscillatory chain is functionally analogous to the chain of cardiac pacemaker neurons.

Anesthesia↗
PubMed1978

Indirect sympathomimetic agents and cerebral blood flow and metabolism.

The effects upon cerebral blood flow (CBF) and oxygen consumption (CMRO2) of the infusion into the internal carotid artery of tyramine and amphetamine were investigated in 24 anaesthetized baboons. The infusion of tyramine was without effect upon CBF and CMRO2 at normocapnia, even at concentrations which significantly raised arterial blood pressure. However, marked reductions in cerebral blood flow were noted at hypercapnia during the infusion of tyramine (2.5 X 10(-7) moles/kg/min). The infusion of amphetamine (7.5 X 10(-10) moles/kg/min) resulted in significant increases in CBF (32%) and CMRO2 (37%). However, an increased concentration of amphetamine (2.5 X 10(-7) moles/kg/min) significantly reduced CBF (22%) and CMRO2 (20%). It is suggested that amphetamine, by virtue of being able to cross the blood--brain barrier and interact with the cerebral monoamine systems, is able to influence cerebral blood flow by inducing changes in cerebral metabolism, and that the minimal reactivity of the cerebral circulation to the infusion of tyramine is the result of the inability of tyramine to cross the blood--brain barrier.

Animals↗
PubMed1978

Differences in the time course of regional cerebral hemo-dynamics of gray and white matter during experimental hypertension.

Investigations concerned with the pathogenesis of hypertensive encephalopathy have reported two opposing changes in cerebral hemodynamics during induced hypertension: (1) vasospasm or vasoconstriction of the leptomeningeal arteries and (2) increase of cerebral blood flow which has been termed "breakthrough" of the cerebral autoregulation. To resolve this apparent conflict, continuous measurements of focal cerebral flow and oxygen availability were made in 17 baboons by the use of implanted platinum electrodes placed in both gray and white matter during induced hypertension. Autoregulation was initially well maintained in gray matter followed by "breakthrough" but the autoregulatory response was poorly maintained in the cerebral white matter. The vasoconstriction of the leptomeningeal arteries reported in earlier investigations from observations made through a skull window appears to be due to a marked autoregulatory response to hypertension rather than vasospasm. The autoregulatory response appears to be efficient in gray matter but relatively deficient in white matter.

Acute Disease↗
PubMed1978

Time course of the cerebral circulatory response to metabolic depression.

Baboons anesthetized with halothane and N2O/O2 were given an intravenous steroid anesthetic (Althesin; Glaxo Laboratories Ltd., U.K.). The drug bolus was labeled with 99mTc, and the time from central venous injection to peak radioactivity in the brain was designated drug brain arrival (DBA-peak). The electroencephalogram slowed 1.2 +/- 0.9 s after DBA-peak (P greater than 0.2), and approximately 2 s after DBA-peak, internal carotid blood flow (ICarBF) decreased and calculated internal carotid vascular resistance (ICarVR) rose. During this 2-s delay in the cerebrovascular response to the arrival of a cerebral metabolic depressant in the brain, the decrease in mean cortical Pco2 was calculated to be less than 0.26 mmHg from cortical CO2 solubility, and less than 0.32 mmHg from cortical CO2 diffusivity, which indicated that mean cortical Pco2 changes do not control cerebral blood flow (CBF). The unaltered time course of the changes in EEG, ICarBF, and ICarVR after acute cervical sympathectomy and alpha-adrenergic receptor blockade excluded the involvement of the sympathetic nervous system in the vasoconstrictor response. Intracarotid Althesin showed that the cerebral vasoconstriction was not a direct effect of the drug. The postulated link between the effects of Althesin on CBF and cerebral metabolism remains to be elucidated but is probably indirect, involving the brainstem.

Adrenergic alpha-Antagonists↗
PubMed1977

Neurotransmitter precursor amino acids in the treatment of multi-infarct dementia and Alzheimer's disease.

Ten patients with severe dementia due to Alzheimer's disease (AD) or multi-infarct dementia (MID) or both, were treated with the precursor amino acids of the neurotransmitters serotonin and dopamine. The precursor amino acids (PAA) were given orally in a preparation that included tyrosine (4 gm daily) and 5-hydroxy-tryptophan (5-HTP) (800 mg daily), plus carbidopa (100 mg daily) as an aromatic amino-acid decarboxylase inhibitor. Diagnosis was established by an electroencephalogram, brain scan, computerized axial tomographic scan, and in one case by necropsy findings. Serial clinical evaluations and measurements of neuropsychologic function were performed. Levels of homovanillic acid (HVA) and 5-hydroxyindole-acetic acid (5-HIAA) were determined before and after administration of probenecid. Side effects of the PAA therapy were diarrhea, drowsiness, nausea, vomiting and agitation, all of which were controlled by reducing the dosage. One patient with MID and one with AD+MID showed clinical and psychologic improvement, but the others did not improve. Analysis of the cerebrospinal fluid for HVA and 5-HIAA before and after the probenecid test indicated some improvement in the metabolic turnover of these acid metabolites of serotonin and dopamine after administration of their precursor amino acids.

5-Hydroxytryptophan↗