Vascular and extravascular fluid changes during six days of bedrest
Human vascular and extravascular fluid changes during six days bedrest based on fluid volume and ideal body weight from individual heights
Carpentier, W. R.↗
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Adaptation of the vascular system to extremal factors
Exposure to g-forces causes changes in the vascular systems of animals. The vessels are distorted and their contents may escape. Various parts of a given organ may react differently according to their structure, and arteries will undergo changes that depend on their position relative to the direction of the g-force vector.
Prives, M. G.↗
Application of vascular aquatic plants for pollution removal, energy and food production in a biological system
Vascular aquatic plants such as water hyacinths (Eichhornia crassipes) (Mart.) Solms and alligator weeds (Alternanthera philoxeroides) (Mart.) Griesb., when utilized in a controlled biological system (including a regular program of harvesting to achieve maximum growth and pollution removal efficiency), may represent a remarkably efficient and inexpensive filtration and disposal system for toxic materials and sewage released into waters near urban and industrial areas. The harvested and processed plant materials are sources of energy, fertilizer, animal feed, and human food. Such a system has industrial, municipal, and agricultural applications.
Wolverton, B. C.↗
Applications of Doppler ultrasound in clinical vascular disease
Doppler ultrasound has become the most useful and versatile noninvasive technique for objective evaluation of clinical vascular disease. Commercially available continuous-wave instruments provide qualitative and quantitative assessment of venous and arterial disease. Pulsed Doppler ultrasound was developed to provide longitudinal and transverse cross-sectional images of the arterial lumen with a resolution approaching that of conventional X-ray techniques. Application of Doppler ultrasound in venous, peripheral arterial, and cerebrovascular diseases is reviewed.
Barnes, R. W.↗
Digital image processing of vascular angiograms
The paper discusses the estimation of the degree of atherosclerosis in the human femoral artery through the use of a digital image processing system for vascular angiograms. The film digitizer uses an electronic image dissector camera to scan the angiogram and convert the recorded optical density information into a numerical format. Another processing step involves locating the vessel edges from the digital image. The computer has been programmed to estimate vessel abnormality through a series of measurements, some derived primarily from the vessel edge information and others from optical density variations within the lumen shadow. These measurements are combined into an atherosclerosis index, which is found in a post-mortem study to correlate well with both visual and chemical estimates of atherosclerotic disease.
Selzer, R. H.↗
Compiled data on the vascular aquatic plant program, 1975 - 1977
The performance of a single cell, facultative sewage lagoon was significantly improved with the introduction of vascular aquatic plants. Water hyacinth (Eichhornia crassipes) was the dominant plant from April to November; duckweed (Lemna spp.) and (Spirodela spp.) flourished from December to March. This 2 ha lagoon received approximately 475 cu m/day of untreated sewage and has a variable COD sub 5 loading rate of 22-30 kg/ha/day. During the first 14 months of operation with aquatic plants, the average influent BOD sub 5 was reduced by 95% from 110 mg/l to an average of 5 mg/l in the effluent. The average influent suspended solids were reduced by 90% from 97 mg/l to 10 mg/l in the effluent. Significant reductions in nitrogen and phosphorus were effected. The monthly kjeldahl nitrogen for influent and effluent averaged 12.0 and 3.4 mg/l, respectively, a reduction of 72%. The total phosphorus was reduced on an average of 56% from 3.7 mg/l influent to 1.6 mg/l effluent.
Wolverton, B. C.↗
Effect of gravitational acceleration, hypokinesia and hypodynamia on the structure of the intestinal vascular bed
A series of experiments comparing single and combined effects of hypokinesia and gravitational acceleration on morphology of intestinal blood vessels are discussed. Results indicate that hypokinesia has a whole body nonspecific effect reflected even in an organ whose activity shows little or no change due to hypokinesia. In early hypokinetic stages blood redistribution caused anorexia, intestinal atonia, and secretory disruption. Destructive changes from further exposure include aneurisms, varicoses, extravascular movement of blood elements, and vascular wall muscle fiber degeneration. The effect of acceleration is greatest in the ventrodorsal direction. Changes due to acceleration then hypokinesia are like those due to hypokinesia alone; changes due to acceleration before and after hypokinesia are like those due to acceleration. Adaptation raises acceleration tolerance but the effects do not survive four-week hypokinesia.
Nikitin, M. V.↗
Coagulating activity of the blood, vascular wall, and myocardium under hypodynamia conditions
In order to study the effects of hypodynamia on the coagulating properties of the blood, vascular wall, and myocardium, chinchilla rabbits were kept for varying periods in special cages which restricted their movements. At the end of the experiment, blood samples were taken and the animals were sacrificed. Preparations were made from the myocardium venae cavae, and layers of the aorta. Two resultant interrelated and mutually conditioned syndromes were discovered: thrombohemorrhagic in the blood and hemorrago-thrombotic in the tissues.
Petrovskiy, B. V.↗
Renal responses to central vascular expansion are suppressed at night in conscious primates
The renal and hemodynamic responses of squirrel monkeys to central vascular volume expansion induced by lower body positive pressure (LBPP) during the day and night are investigated. Twelve unanesthetized animals trained to sit in a metabolism chair in which they were restrained only at the waist by a partition separating upper and lower body chambers were subjected to 4 h of continuous LBPP during the day and night, and hemodynamic, urinary and drinking data were monitored. LBPP during day and night is found to induce similar increases in central venous pressure, rises in heart rate and elevations in mean arterial blood pressure. However, although daytime LBPP induced a significant increase in urine flow and sodium excretion, a marked nocturnal inhibition of the renal response to LBPP is observed. Analysis of the time course and circadian regulation patterns of the urinary responses suggests that several separate efferent control pathways are involved.
Kass, D. A.↗
Chronic central vascular expansion induces hypokalemia in conscious primates
Central vascular expansion maintained for four days in conscious squirrel monkeys reconciles the apparently conflicting short-term fluid and electrolyte responses to water immersion and atrial balloon distension, with those described for prolonged weightlessness during space flight. The monkeys are subjected to an increased lower body positive air pressure (LBPP) of 20 torr which produces a 3 cm water increase in the central venous pressure. Results show a marked increase in the urinary excretion of sodium, potassium, and water during the firxt six hours of LBPP, and the diuresis is maintained throughout the period of LBPP, although the levels of sodium and potassium excretion decline after 24 hours of exposure. Plasma aldosterone transiently drops within the first three hours of LBPP, and then regains normal levels within 24 hours, after which time these levels are maintained despite the continued LBPP stimulus. It is suggested that the normal plasma aldosterone levels observed in the experiments, as well as during space flight, might, epresent a relative hyposecretion in terms of volume homeostasis and a relative hypersecretion with respect to plasma potassium regulation. Thus, kaliuresis and marked natriuresis is confined primarly to the first 24 hours of central volume expansion, a period for which comparable data from space flights are lacking.
Moore-Ede, M. C.↗
Method for treating wastewater using microorganisms and vascular aquatic plants
A method for treating wastewater compresses subjecting the wastewater to an anaerobic setting step for at least 6 hours and passing the liquid effluent from the anaerobic settling step through a filter cell in an upflow manner. There the effluent is subjected first to the action of anaerobic and facultative microorganisms, and then to the action of aerobic microorganisms and the roots of at least one vascular aquatic plant.
Wolverton, B. C.↗
Increase in whole-body peripheral vascular resistance during three hours of air or oxygen prebreathing
Male and female subjects prebreathed air or 100% oxygen through a mask for 3.0 hours while comfortably reclined. Blood pressures, heart rate, and cardiac output were collected before and after the prebreathe. Peripheral vascular resistance (PVR) was calculated from these parameters and increased by 29% during oxygen prebreathing and 15% during air prebreathing. The oxygen contributed substantially to the increase in PVR. Diastolic blood pressure increased by 18% during the oxygen prebreathe while stystolic blood pressure showed no change under either procedure. The increase in PVR during air prebreathing was attributed to procedural stress common to air and oxygen prebreathing.
Waligora, J. M.↗
Effects of heavy ion radiation on the brain vascular system and embryonic development
The present investigation is concerned with the effects of heavy-ion radiation on the vascular system and the embryonic development, taking into account the results of experiments with neonatal rats and mouse embryos. It is found that heavy ions can be highly effective in producing brain hemorrhages and in causing body deformities. Attention is given to aspects of methodology, the induction of brain hemorrhages by X-rays and heavy ions, and the effect of iron particles on embryonic development. Reported results suggest that high linear energy transfer (LET) heavy ions can be very effective in producing developmental abnormalities.
Yang, T. C.↗
The effects of normal and therapeutic baths on the central vascular organs of persons with healthy hearts, as measured by X-ray
According to current information, baths have a four-fold effect on the circulation: (1) Dilation or constriction is produced in the area of the blood vessels in the skin as a result of thermal, chemical or mechanical stimuli; (2) This reaction in the dermal vascular system produces a further effect on the central vessels in the extremities, the area of the splanchnicus, and other body cavities; (3) The reflect transposition of other organ systems, i.e., the respiratory organs, has a reaction on the circulation; and (4) The water pressure of the bath has a hydrostatic effect, i.e., on the one hand it empties peripheral veins more rapidly, and on the other it increases the intra-abdominal pressure and this reduces once again the circulation in the area of the splanchnicus.
Boehm, G.↗
Leg vascular responsiveness during acute orthostasis following simulated weightlessness
The effect of weightlessness on vascular response to orthostatic stress was investigated in human subjects by measuring changes in the arterial pulse volume (APV) of the legs during exposure to lower body negative pressure (LBNP) applied before and after 10 days of continuous 6-deg head-down bed rest. Heart rate, mean arterial blood pressure (MAP), and impedance rheographic indices of APV were measured during rest and at 1 min of -30 mm Hg LBNP. Bed rest was found not to alter the responses of MAP to LBNP. Resting APV was decreased after bed rest; however, APV was reduced upon transfer from rest to 1-min LBPN by the same relative magnitude before and after bedrest. It is concluded that peripheral arterial vasoconstriction, as indicated by reduction in APV during LBNP, is not affected by bedrest. The results suggest that there was no apparent alteration in responsiveness of the leg vasculature following simulated weightlessness, and that the control mechanisms of peripheral resistance do not contribute significantly to reduced orthostatic tolerance following spaceflight.
Blamick, Cynthia A.↗
Intraocular pressure, retinal vascular, and visual acuity changes during 48 hours of 10-deg head-down tilt
Intraocular pressures, retinal vascular diameters, and visual acuities of nine men, were repeatedly measured while the subjects were tilted 10 deg head-down for 48 h and while they were seated before (baseline), and after the tilt. An immediate increase in intraocular pressure, measured by pneumatonometer was recorded when subjects assumed the head-down position, and diurnal variations in intraocular pressures were observed for the 48 h. The initial and final head-down intraocular pressures were not significantly different. However, when subjects resumed the sitting position, intraocular pressures fell below the initial sitting values. Computer image analysis of the retinal vasculature detected a 6 percent and 2 percent reduction in the caliber of arteries and veins, respectively, as compared with sitting baseline values. No changes in visual acuity were documented during the 48 h of head-down tilt. The data suggest that the choroidal blood reservoir increases in volume over 48 h at continuous head-down position with a compensatory decrease in aqueous volume. These findings may explain intraocular pressure changes noted in astronauts during previous space missions and in studies associated with change in body position.
Mader, Thomas H.↗
Carotid-cardiac baroreflex influence on forearm vascular resistance during low level LBNP
Twelve healthy males were tested at low levels of lower body negative pressure (LBNP) with and without artificial stimulation of the carotid-cardiac baroreceptors. The carotid-cardiac baroreceptors were stimulated by applying a pressure of 10 mmHg to the carotid artery via a pressurized neck chamber. During the procedure, forearm blood flow (FBF) and forearm vascular resistance (FVR) were measured using a Whitney mercury silastic strain gauge technique. FBF decreased while FVR increased with increased intensity of LBNP. Both FBF and FVR were unaffected by carotid-cardiac baroreceptor stimulation.
Ludwig, David↗
Effect of leg exercise training on vascular volumes during 30 days of 6 deg head-down bed rest
In order to investigate the effects of leg exercise training on vascular volumes during 30 d of 6-deg head-down bed rest, plasma and red cell volumes, body density, and water balance were measured in 19 men confined to bed rest (BR). One group had no exercise training (NOE), another near-maximal variable-intensity isotonic exercise (ITE) for 60 min/d, and the third near-maximal intermittent isokinetic exercise (IKE) for 60 min/d. Mean energy costs for the NOE, IKE, and ITE regimens were determined. Body densities within groups and mean urine volumes between groups were unchanged during BR. Changes in red cell volume followed changes in plasma volume. There was close coupling between resting plasma volume and plasma protein and osmotic content. It is argued that the ITE training protocol is better than the IKE protocol for maintaining plasma volume during prolonged exposure to BR.
Greenleaf, J. E.↗