Hormonal determinants of mammalian tolerance to acceleration stress

1961 ◽  
Vol 16 (2) ◽  
pp. 211-214 ◽  
Author(s):  
B. David Polis
Keyword(s):  
Technical Assistance ◽  
Critical Factor ◽  
Significant Loss ◽  
Significant Drop ◽  
Tolerance Level ◽  
High Acceleration ◽  
Positive Acceleration ◽  
Hypophysectomized Rats ◽  
Normal Rat ◽  
Acceleration Stress

The pituitary-adrenal hormonal axis has been implicated as a critical factor in the survival of the rat to acceleration stress. The physiological end point for the tolerance of animals to high positive acceleration stress was obtained by determining the time to reduce the heart rate from 8 to 2 beats/sec. at 20 g. With this technique, a significant increase (300%) in the survival time of rats to 20 g was found following hypophysectomy. A significant loss (60%) of tolerance to high acceleration stress was found in adrenalectomized rats. The procedures of hypophysectomy plus adrenalectomy apparently opposed the effect of each operation alone in the rat to yield an animal that tends to approach the normal rat in its ability to tolerate acceleration. A significant drop in the tolerance to acceleration of hypophysectomized rats was found 7 and 15 weeks after operation compared to that found with the animals 3 weeks after hypophysectomy and a significant increase in the tolerance of the adrenalectomized rat was found 11 weeks after operation compared to the tolerance at 5 weeks after adrenalectomy. In both operated populations, the direction of change was toward the tolerance level of the normal rat. Note: (With the Technical Assistance of Anne Zella) Submitted on September 12, 1960

Cardiovascular changes during acceleration stress in dogs

1960 ◽  
Vol 15 (6) ◽  
pp. 1065-1068 ◽  
Author(s):  
Edward J. Hershgold ◽  
Sheldon H. Steiner
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Technical Assistance ◽  
Peripheral Resistance ◽  
Cardiovascular Changes ◽  
Positive Acceleration ◽  
Acceleration Stress ◽  
Circulatory Disturbances

Dogs were accelerated on the Wright-Patterson AFB human centrifuge in positive and transverse vectors. Cardiac output, blood pressure and heart rate were measured, and stroke volume and peripheral resistance calculated. In positive (headward) acceleration, the cardiac output and stroke volume were reduced; the peripheral resistance was increased. In the transverse vectors, the cardiac output was stable or increased; stroke volume was stable, and peripheral resistance was reduced. The results suggest that the circulatory disturbances associated with positive acceleration may limit tolerance to acceleration and that these may be avoided in transverse acceleration. Note: (With the Technical Assistance of Peter Grenell) Submitted on December 3, 1959

THE ROLE OF THE ADRENAL GLAND IN THE CONTROL OF AMINO ACID INCORPORATION INTO PROTEIN OF ISOLATED RAT LIVER MICROSOMES

1960 ◽  
Vol 21 (2) ◽  
pp. 177-189 ◽  
Author(s):  
A. KORNER
Keyword(s):  
Amino Acid ◽  
Rat Liver ◽  
Liver Microsomes ◽  
Female Rats ◽  
Male Rats ◽  
Rat Liver Microsomes ◽  
Hypophysectomized Rats ◽  
Normal Rat ◽  
Secondary Result

SUMMARY 1. Microsomes, isolated from rat liver a day after adrenalectomy, incorporate more radioactive amino acid into their protein in vitro than microsomes from normal rat liver. This enhanced rate of incorporation progressively declines with time after adrenalectomy until it reaches a plateau level which is below the normal rate of incorporation. 2. Following adrenalectomy microsomes isolated from liver of male rats show a greater rise in incorporating ability than those from liver of female rats, and maintain it longer. 3. Most of the increased incorporation observed in the in vitro system soon after adrenalectomy of the rat, and most of the decreased incorporation observed in rats adrenalectomized for some time, results from alterations in the microsomes which change their ability to incorporate activated amino acids into proteins. 4. Treatment of rats with cortisol acetate results in an increase in the ability of liver microsomes to incorporate amino acid into protein. This heightened incorporating ability is probably a secondary result of the breakdown of extrahepatic tissue protein which is stimulated by cortisol. 5. Somewhat similar responses to acute adrenalectomy and to treatment with cortisol were found in hypophysectomized rats. 6. The protein anabolic response of adrenalectomized rats to treatment with insulin, and of adrenalectomized-hypophysectomized rats to treatment with insulin or growth hormone, is greater than that shown by rats which possess adrenal glands.

Coronary blood flow in conscious miniature swine during +GZ acceleration stress

1980 ◽  
Vol 49 (3) ◽  
pp. 462-470 ◽  
Author(s):  
M. H. Laughlin ◽  
W. M. Witt ◽  
R. N. Whittaker ◽  
E. F. Jones
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Coronary Blood Flow ◽  
Diastolic Pressure ◽  
Regional Distribution ◽  
Critical Value ◽  
Left Ventricular ◽  
Miniature Swine ◽  
Positive Acceleration ◽  
Acceleration Stress

One of the factors determining tolerance to +GZ acceleration may be the ability to maintain adequate coronary blood flow. Consequently, the purpose of these studies was to determine the effect of acute exposure (60 s) to several levels of positive acceleration (+GZ) on total and regional coronary blood flow in conscious adult miniature swine. Blood flow was measured with the radiolabeled microsphere technique in chronically instrumented miniature swine during 60-s exposures to accelerations of +3 GZ, +5 GZ, or +7 GZ with anti-G suit support. All levels of acceleration stress caused two- to threefold increases in coronary blood flow. The regional distribution of coronary blood flow during +GZ was similar to that under resting control conditions as long as aortic diastolic pressure was maintained. All left ventricular endocardial/epicardial flow ratios were significantly greater than one, except in two animals, during exposure to +7 GZ. These were the only animals to have aortic diastolic pressures less than 100 Torr during +GZ stress. These studies indicate that, if an animal is able to compensate and maintain a cardiovascular steady State, coronary blood flow will remain adequate for myocardial needs. However, if decompensation occurs and aortic diastolic pressure falls below a critical value, subendocardial blood flow may become inadequate.

Effect of chronic administration of insulin on pituitary gland content of growth hormone in the normal rat

1970 ◽  
Vol 48 (2) ◽  
pp. 85-89 ◽  
Author(s):  
Robert L. Hazelwood ◽  
John G. Galaznik
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Young Adult ◽  
Pituitary Gland ◽  
Chronic Administration ◽  
Female Rats ◽  
Pituitary Glands ◽  
Hypophysectomized Rats ◽  
Normal Rat ◽  
Gland Content

Acetone-dried pituitary glands from young adult female rats (starting weight 165–168 g) previously injected (s.c.) with doses of insulin of 0.5 U to 1.0 U/kg body weight for 4 days, and then with 2.0 U/kg 6 days a week for an additional 34 days, were bioassayed in young hypophysectomized rats for growth hormone content. Insulin-injected rats gained significantly more weight than saline-injected controls. The tibia cartilage width of the insulin-injected donor rats was greater than that of control rats after 9, 17, 24, and 31 days of insulin; pituitary gland preparations from these insulin-injected rats increased tibia cartilage widths slightly but significantly over those of rats injected with control pituitary gland preparations.

scholarly journals Differential Cytotoxicity of Different Sizes of Graphene Oxide Nanoparticles in Leydig (TM3) and Sertoli (TM4) Cells

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 139 ◽  
Author(s):  
Sangiliyandi Gurunathan ◽  
Min-Hee Kang ◽  
Muniyandi Jeyaraj ◽  
Jin-Hoi Kim
Keyword(s):  
Graphene Oxide ◽  
Cell Viability ◽  
Graphene Nanosheets ◽  
Critical Factor ◽  
Biological Properties ◽  
Significant Loss ◽  
Toxic Effects ◽  
Biological Behavior ◽  
Ros Generation ◽  
Size Dependent

Graphene oxide (GO) is an common nanomaterial and has attracted unlimited interest in academia and industry due to its physical, chemical, and biological properties, as well as for its tremendous potential in applications in various fields, including nanomedicine. Whereas studies have evaluated the size-dependent cytotoxicity of GO in cancer cells, there have been no studies on the biological behavior of ultra-small graphene nanosheets in germ cells. To investigate, for the first time, the cyto- and geno- toxic effects of different sizes of GO in two different cell types, Leydig (TM3) and Sertoli (TM4) cells, we synthesized different sized GO nanosheets with an average size of 100 and 20 nm by a modification of Hummers’ method, and characterized them by various analytical techniques. Cell viability and proliferation assays showed significant size- and dose-dependent toxicity with GO-20 and GO-100. Interestingly, GO-20 induced significant loss of cell viability and cell proliferation, higher levels of leakage of lactate dehydrogenase (LDH) and reactive oxygen species (ROS) generation compared to GO-100. Both GO-100 and GO-20 induced significant loss of mitochondrial membrane potential (MMP) in TM3 and TM4 cells, which is a critical factor for ROS generation. Furthermore, GO-100 and GO-20 caused oxidative damage to DNA by increasing the levels of 8-oxo-dG, which is formed by direct attack of ROS on DNA; GO-100 and GO-20 upregulate various genes responsible for DNA damage and apoptosis. We found that phosphorylation levels of EGFR/AKT signaling molecules, which are related to cell survival and apoptosis, were significantly altered after GO-100 and GO-20 exposure. Our results showed that GO-20 has more potent toxic effects than GO-100, and that the loss of MMP and apoptosis are the main toxicity responses to GO-100 and GO-20 treatments, which likely occur due to EGFR/AKT pathway regulation. Collectively, our results suggest that both GO-100 and GO-20 exhibit size-dependent germ cell toxicity in male somatic cells, particularly TM3 cells, which seem to be more sensitive compared to TM4, which strongly suggests that applications of GO in commercial products must be carefully evaluated.

scholarly journals Determinants of Small-Scale Commercial Vegetable Farming Among Vegetable Growers in Nepal

SAGE Open ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 215824402110101
Author(s):  
Niraj Prakash Joshi ◽  
Luni Piya
Keyword(s):  
Land Tenure ◽  
Poverty Reduction ◽  
Technical Assistance ◽  
Land Development ◽  
Critical Factor ◽  
Probit Analysis ◽  
Small Scale ◽  
Vegetable Production ◽  
Vegetable Crops ◽  
Vegetable Farming

Various socio-economic factors play important roles in the adoption of commercial vegetable farming. Understanding these factors is crucial in enhancing the existing low rate of vegetable commercialization in Nepal, thereby achieving the overall development goal of poverty reduction. This article analyzes the personal, technical, and business factors associated with the adoption using Nepal Vegetable Crops Survey 2009–2010 data. A probit analysis is carried out. Caste/ethnicity is a critical factor hindering the adoption in Nepal. An awareness program to facilitate marketing of vegetables produced by the socially disadvantaged caste/ethnic groups and targeting them in interventions would be helpful in enhancing the rate of vegetable commercialization. Similarly, facilitating access to technical factors, mainly technical assistance, chemical fertilizers, pesticides, and improved seeds, would promote commercial vegetable farming. Such interventions can be introduced in vegetable production potential areas of Hills and Tarai. Land consolidation might not be important. Rather, any program or policies to facilitate secure land-tenure, which encourages farmers to invest in land development, would boost vegetable commercialization. Similarly, identification of vegetable cultivation areas and provision of irrigation in those land parcels would be vital.

scholarly journals Contribution of very short-lived substances to stratospheric bromine loading: uncertainties and constraints

2012 ◽  
Vol 12 (11) ◽  
pp. 30283-30326
Author(s):  
J. Aschmann ◽  
B.-M. Sinnhuber
Keyword(s):  
Large Scale ◽  
Transport Model ◽  
Gas Injection ◽  
Critical Factor ◽  
Significant Loss ◽  
Convective Transport ◽  
Heterogeneous Reactions ◽  
Minor Role ◽  
Tropical Tropopause ◽  
Ice Particles

Abstract. Very short-lived substances (VSLS) still represent a major factor of uncertainty in the quantification of stratospheric bromine loading. One of the major obstacles for short-lived source gases in contributing to the stratosphere is generally thought to be loss of inorganic bromine (Bry) in the tropical tropopause layer (TTL) due to dehydration. We use sensitivity calculations with a~three-dimensional chemistry transport model comprising a consistent parametrization of convective transport and a comprehensive chemistry scheme to investigate the associated processes. The model considers the two most important bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2). The organic bromine source gases as well as the resulting profile of inorganic bromine in the model are consistent with available observations. In contrast to its organic precursors, Bry is assumed to have a~significant sorption capacity regarding sedimenting liquid or frozen particles thus the fraction of intact source gases during their ascent through the TTL is a critical factor. We find that source gas injection is the dominant pathway into the stratosphere, about 50% of CHBr3 and 93% of CH2Br2 is able to overcome the cold point tropopause at approximately 17 km altitude, modulated by the interannual variability of the vertical transport efficiency. In fact, our sensitivity calculations indicate that the extent of source gas injection of CHBr3 is highly sensitive to the strength of convection and large-scale ascent; in contrast, modifying the photolysis or the destruction via OH yields a significantly smaller response. In principal, the same applies as well to CH2Br2, though it is considerably less responsive due to its longer lifetime. The next important aspect we identified is that the partitioning of available Bry from short-lived sources is clearly shifted away from HBr, according to our current state of knowledge the only member of the Bry family which is efficiently adsorbed on ice particles. This effect is caused by very efficient heterogeneous reactions on ice surfaces which reduce the HBr/Bry fraction below 15% at the tropical tropopause. Under these circumstances there is no significant loss of Bry due to dehydration in the model, VSLS contribute fully to stratospheric bromine. In addition, we conduct several sensitivity calculations to test the robustness of this result. If heterogeneous chemistry is ignored, the HBr/Bry fraction exceeds 50% and about 10% of bromine from VSLS is scavenged. Dehydration plays a minor role for Bry removal under the assumption that HOBr is efficiently adsorbed on ice as well since the heterogeneous reactions alter the partitioning equilibrium of Bry in favor of HOBr. In this case, up to 12% of bromine from VSLS is removed. Even in the extreme and unrealistic case that adsorbed species on ice particles are instantaneously removed the maximum loss of bromine does not exceed 25%. In conclusion, considering the average abundance of bromine short-lived source gases in convective updrafts of 6 parts per trillion by volume (pptv) we find a most likely contribution of VSLS to stratospheric bromine in the range of 4.5–6 pptv.

Sodium and potassium content of brain and muscle of rats subjected to high acceleration

1959 ◽  
Vol 14 (4) ◽  
pp. 621-624 ◽  
Author(s):  
Benjamin F. Burgess ◽  
Charles F. Gell ◽  
Doris Cranmore
Keyword(s):  
Rest Period ◽  
Rectus Femoris ◽  
Stress Pattern ◽  
Potassium Content ◽  
Radial Acceleration ◽  
High Acceleration ◽  
Acceleration Stress ◽  
Rectus Femoris Muscle ◽  
Sodium And Potassium ◽  
Femoris Muscle

Male Albino (Wistar) rats were subjected to a radial acceleration stress on an eight-foot centrifuge. Each centrifugation of 20 positive g (head to foot) lasted 20 seconds followed by a 1-minute rest period. The stress pattern consisted of 40 exposures to this sublethal stress in approximately 1 hour. The entire brain and a section of the rectus femoris muscle were removed and analyzed for their sodium and potassium content. There was a significant decrease in muscle and brain potassium and a significant increase in muscle sodium; brain sodium remained unchanged. In one series of rats a sublethal intraperitoneal injection of sodium amytal was given 3 minutes prior to decapitation. In contrast to the unanesthetized series, this group showed an increase in brain potassium in the stress animals. Submitted on January 14, 1959

Studies of positive radial acceleration on mice

1959 ◽  
Vol 14 (1) ◽  
pp. 52-54 ◽  
Author(s):  
Sung Jang Chung
Keyword(s):  
Radial Acceleration ◽  
Male And Female ◽  
Female Mice ◽  
Probability Of Survival ◽  
Positive Acceleration ◽  
Pathologic Findings ◽  
Acceleration Stress

One hundred and ninety-one mice were subjected to positive acceleration of from 3 to 85 g, for periods of 5 seconds to 80 minutes. Data on mortality and on pathologic findings are presented. No significant differences were observed in the resistance of male and female mice to positive g. ECG tracings from mice exposed to 8 g for 25 minutes were examined. Formulas are presented to express probability of survival of mice in terms of exposure and magnitude of acceleration stress. Submitted on May 21, 1958

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