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Results for “Environment--changes”

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PubMed1975

Persistent depression of rearing behavior in rats after extensive septal lesions.

Extensive septal lesions produced a persistent (76 days) reduction in rearing behavior which was not directly attributable to altered deprivation states, emotionality, activity levels, or competing behaviors and which occurred in familiar as well as various novel testing environments. Changes in visual, olfactory, or conspecific stimuli ameliorated or had no effect on the lesion effect. The results indicate that the septal area is importantly involved in normal rearing behavior and that lesion-induced alterations in responsiveness to some forms of stimulation may play a modulatory role in reduced rearing. It is also suggested that the septal area may constitute a portion of a neural system responsible for the initiation of this form of response.

Animals↗

PubMedDate not supplied

Alterations in glutathione during storage of human platelet concentrates.

Glutathione and glutathione disulfide decline rapidly and progressively in human platelet concentrates stored for up to 7 days at 22 degrees C. Total glutathione declines progressively throughout the storage period, with an estimated half-disappearance time of 2 days. Glutathione disulfide remains constant during the first 2 days of storage but declines progressively thereafter, with an estimated half-disappearance time of 3.2 days. Based on measurements of glutathione disulfide in freshly collected platelets, the authors postulate that glutathione disulfide is elevated during the production of platelet concentrates or during the first 2 days of storage, accounting for the lag in its decay curve. Since total glutathione decreases more rapidly than glutathione disulfide, the fraction of glutathione present in the oxidized form increases throughout the storage period. Glutathione-dependent mechanisms maintain essential cell proteins in the appropriate redox states and provide avenues for the detoxification of potentially noxious compounds generated by the cell or within its environment. Changes in platelet glutathione and glutathione disulfide during storage may be responsible for storage-dependent alterations in in vitro functions and may also affect subsequent in vivo recovery and survival upon reinfusion.

Blood Platelets↗

PubMed1991

Identification of adaptive changes in an evolving population of Escherichia coli: the role of changes with regulatory and highly pleiotropic effects.

A population of Escherichia coli initiated with a single clone developed extensive morphological and physiological polymorphism after being maintained for 773 generations in glucose-limited continuous culture. To understand the mechanisms of adaptation to this environment, total protein patterns of four adaptive clones and of the parent strains were examined by two-dimensional gel electrophoresis. Approximately 20% of the proteins (approximately 160 in absolute numbers) showed significantly different levels of expression in pairwise comparisons of parent and adapted clones. The extent of these changes points to the importance of mutations with regulatory and/or highly pleiotropic effects in the adaptive process. The four evolved clones all expressed fewer proteins than did the parent strain, supporting the hypothesis of energy conservation during evolutionary change. Forty-two proteins that could be assigned to known cellular functions were identified. The changes in some of them indicated that the evolved clones developed different adaptive mechanisms to glucose-limited environment. Changes were observed in the expression levels of proteins associated with translation, membrane composition, shock response, and active transport. A fraction of the changes could not be either explained or predicted from a consideration of the nature of the environment in which the clones evolved.

Adaptation, Biological↗

PubMed1985

Experimental observation of transplantation of vein graft to lymphatics.

We attempted to transplant a vein graft to normal lymphatics (LVL) to investigate whether it could survive and remain joined to the lymphatics as the environment changed. A total of 152 rabbits were divided into 3 groups. Group 1 was an LVL saline-irrigated group (n = 40), with a patency rate of 52.5%. Group 2 was an LVL nonirrigated group (n = 34), with a patency rate of 29.4%. Group 3 was an LV group (n = 78), with a patency rate of 32%. All specimens were examined under either light microscope or scanning electron microscope. The data indicated that an LVL anastomosis is practical and that preanastomotic irrigation can improve the patency rate. In both the LVL and the LV groups, endothelial regeneration, originating from the adjacent endothelium, commenced within 1 week after the anastomosis, with complete healing within 3 to 4 weeks. The vein graft tended to become "lymphaticized." Thrombosis was the main cause of obstruction. The patency rate can be increased by irrigation of the ends with saline before performing the anastomosis. The graft intima must be kept intact, the nutritive blood vessels of the lymphatics must be preserved, and the flow must be artificially increased soon after the anastomosis.

Animals↗

PubMed1986

Patterns of recall in schizophrenics and normal subjects.

In two experiments it was demonstrated that the patterns of recall exhibited by schizophrenics qualitatively changed as the amount of structure present in the encoding and retrieval environments changed. When the encoding environment was structured and the retrieval environment was left unstructured (experiment 1), the schizophrenics' recall was not only lower than that of the normal subjects, but the patterns of recall of the two groups qualitatively differed. When encoding and retrieval environments were both structured (experiment 2), the patterns of recall exhibited by both groups were identical, although the schizophrenics continued to exhibit a recall deficit. This pattern of performance is more consistent with the notion that the recall deficit is caused by disease-induced depression of attentional capacity rather than by irreversible defects in ability to process information.

Adult↗

PubMed1992

Hmong women: characteristics and birth outcomes, 1990.

Current demographic characteristics and pregnancy outcomes of immigrant Hmong women in a small town in southeastern United States were documented in a retrospective study. Interviews and review of existing records were used to determine prenatal practices and perceived problems. Sixteen health professionals and two women from the community were interviewed, and the labor and delivery records from 1985 to 1990 were reviewed for parity, child spacing, and health status of the women and newborns. The greatest concerns voiced by health caregivers were multiparity and the need for contraceptive compliance. Seventy-eight full-term infants were born to 64 women in five years, with 2 stillbirths. No eclampsia, diabetes, or Rh incompatibilities were noted. Evidence is limited that birth frequency or outcome for Hmong women is a problem. Their perinatal difficulties were thought to be sociocultural rather than medical. Further study of the effects of acculturation on maternal family position, perinatal risks, and birth outcomes is imperative as lifestyle and environment change for these immigrant women.

Adolescent↗

PubMed1992

Computer-assisted three-dimensional reconstruction and simulations of vestibular macular neural connectivities.

The macular neuroepithelium is morphologically organized as a weighted neural network for parallel distributed processing of information. The network is continuous across the striola, where some type II hair cells synapse with calyces containing type I cells with tufts of opposite directional polarities. Whether other hair cell to calyx appositions that lack synapses interact because of intercellular potassium accumulation remains an open question. A functionally important inference of macular organization is that just as arrays of hair cells communicate an entire piece of information to a nerve fiber, so do macular subarrays of nerve fibers (not single units) carry the whole coded message to the brain stem. Moreover, the size of the network subarray can expand or become more limited depending upon the strength and/or duration of the input. It is the functioning of the network and its subarrays that must be understood if we are to learn how maculas carry out their work and adapt to new environments. Simulations of functioning maculas, or subparts, based on precise morphology and known physiology are useful tools to gain insights into macular information processing. The current simulations of afferent collateral electrical activity are a prelude to development of a 3-D model. The simulations demonstrate a relationship between geometry and function, with the diameter of the stem apparently being a major determinant of electrical activity transmitted to the base in the case of collaterals with short stems. Thus, while changes in synaptic number and/or size may be an important adaptive mechanism in an altered g environment, changes in diameter of the stem is another means of altering outflow. Research on the effects of microgravity should be extremely useful in examining the validity of this and other concepts of neural adaptation, since maculas are biological linear accelerometers ideally suited to the task. Maculas are also extremely interesting to study in detail because of the richness of connectivities and submicroscopic organization they present. Many of their features are common with more complex parts of the brain. It seems possible that knowledge of the three-dimensional geometric relationships operative in a functioning macula will contribute much to the understanding of the dynamics underlying more complex behavior. Computerized approaches greatly facilitate this task and provide an objective method of analysis. It is likely that, in the end, simple rules will be found to govern optimal neural architectural organization, even at higher cognitive levels. The architecture only appears complex because we do not yet grasp its meaning.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Maculae↗

PubMed1991

Two point mutations in the transmembrane domain of P68gag-ros inactive its transforming activity and cause a delay in membrane association.

The transforming protein of the avian sarcoma virus UR2 is a 68-kDa transmembrane tyrosine protein kinase. We examined the relationship between membrane localization and transforming activity of P68 by changing Val-168-Val-169 in its hydrophobic domain into Asp-168-Glu-169. The resulting transmembrane (TM) mutant (P68TM) lost transforming activity toward chicken embryo fibroblasts (CEF). We found that the mutant protein was expressed and rapidly degraded into a smaller form which was still membrane associated and kinase active. The instability of the TM mutant protein is a phenomenon only manifested in CEF, because the same mutant protein was expressed with efficiency and stability similar to those of the wild-type protein in a transient expression system in COS cells. However, there are several differences between the wild-type and the TM mutant proteins in COS cells. The wild-type protein is more heavily phosphorylated and associated with membrane fractions in a cotranslational manner. It is enzymatically active when recovered from membrane fractions. The TM mutant protein is less phosphorylated, more labile toward protease degradation, and delayed in membrane association, with a lag period of 30 min or longer, and has little kinase activity when recovered from membrane fractions. Most of the kinase-active TM mutant protein was found in the cytosol fractions. Despite the delay, most of the TM protein in COS cells was found to be membrane associated, and its orientation on the cell surface was similar to that of the wild-type protein. It is probable that loss of the CEF-transforming activity of the TM mutant protein is due to its susceptibility to protease degradation resulting from improper membrane association of the newly synthesized product. The differences in the kinetics of membrane association and the distribution of kinase activity in COS cells might not be directly applicable in explaining the inability of the TM mutant to transform CEF but are intriguing as regards protein biosynthesis and translocation. The difference between CEF and COS cells implies that different factors or pathways are involved in the biosynthesis and processing of the TM mutant protein in these two cellular environments. Changes of P68TM in the kinetics of membrane association indicate that the transmembrane domain of ros, besides functioning as a membrane anchor, also plays a role in directing initial membrane association.

Animals↗

PubMed1988

In vivo effects of glucocorticoid excess on the contents of the rat fetal liver in erythroid progenitors.

Following a laparotomy of the pregnant rat at 12 days of gestation, erythroid cell suspensions prepared from the fetal livers at 14 days contained an increased proportion of progenitor cells forming colonies after 2 or 7 days of culture. When laparotomy was performed at 14 days and the fetal livers were sampled at 16 days, the opposite effects were observed. Injection of 0.25 mg/kg dexamethasone to the 12 days pregnant rat increased the proportion of erythroid progenitors in suspensions from 14 days fetal livers; injection of 10 mg/kg (a long-acting dose) produced the opposite effects. Both the composition of the erythroid cell line and its environment change between 12 and 14 days, and these modifications might explain the inversion of glucocorticoid effects between these two stages.

Animals↗

PubMed1977

Development of stress-induced pituitary prolactin and TSH release in male rats.

Blood was collected from male rats of various ages under control conditions and after introduction of two stress factors. All animals were sacrificed between 15.00 and 16.00 h. Serum prolactin levels in immature male rats were found to be very low between birth and day 15 after birth. Neither exposure to a new environment, for example removal from the animal rooms for the duration of 10 min, nor exposure to concentrated ether vapour resulted in increased serum prolactin levels. Between day 20 and 35 basal serum prolactin levels were increased, they then fell at adult values. During this period of increasing serum prolactin levels pituitary prolactin release became stress-susceptable; i.e. elevated serum prolactin levels were observed after introduction of stress factors as in adult male rats. Serum TSH levels were found to be high between birth and day 10. Low TSH levels measured between day 15 and 40 and adult values were detected after day 40. Neither ether nor removal of the animals from their normal environment changed serum TSH levels at any age tested. The results indicate that the hypothalamo-pituitary in immature rats reacts in a similar way as that in adult animals from day 16-20 onwards. Serum TSH levels in these animals, however, are reduced, indicating that an increase in serum TSH is not necessary for normal processes of maturation.

Age Factors↗

PubMed1988

Divergent selection for growth in Japanese quail under split and complete nutritional environments. 1. Genetic and correlated responses to selection.

Japanese quail were divergently selected for 4-wk body weight under two different nutritional environments. In one environment quail were divergently selected for high and low body weight (H and L) under a split diet (SD) with quail having the opportunity to self-select feed from high protein and high energy diets. In the other environment, quail were similarly selected (H and L) under a normal (28% protein) complete diet (CD). After 11 generations of selection, H-SD and H-CD lines were 48.9 and 49.7% higher in 4-wk body weight than controls. Quail from L-SD and L-CD lines were 46.5 and 45.4% lower in 4-wk body weight than controls. Realized heritabilities for 4-wk body weight were .36 +/- .03, .30 +/- .03, .52 +/- .02, and .47 +/- .03 for H-SD, L-SD, H-CD, and L-CD lines, respectively. Selection differentials were significantly higher in the SD than in the CD environment. Changes in 2-wk, adult body, and egg weight across generations paralleled that of the trait under selection (4-wk body weight). Selection also resulted in decreased hatchability and egg production with increased age to sexual maturity in both environments. The SD environment was determined to be a stress environment because of birds' inferior growth there compared with growth in the CD environment. Rate of growth, however, to reach adult body size was superior for L-SD quail once the stress environment was removed. There was also evidence that eggs were larger for quail in the SD than the CD environment.

Animals↗

PubMed1990

The immuno-suppressed patient--what are the implications?

Dentists, doctors, and other health professionals are increasingly involved in interacting with immunosuppressed and immuno-deficient patients. As the medico-legal and health-economic environments change, an increasing range of progressively more difficult problems is developing. Like other health professionals, dentists must accept their role as advocates for patients, despite the stresses that this will entail. The psychological and social stresses inherent in handling life-long management problems based upon immuno-suppression and immuno-deficiency exceeds the hazards to dentists and others which result from exposure to various viruses and bacteria. There are implications in terms of history taking, organisation of laboratory and organ-imaging investigations, for continuing education, and for intra-professional referral procedures.

Attitude↗

PubMed1989

Toward the necessary universalizing of a disability policy.

Issues confronting people with disabilities do not result solely from physical or mental impairment, but from the fit between impairments and practically every feature of the social, economic, physical, and political environment. Changes in housing, transportation, and employment policies would augment the quality of daily living for those with disabilities today and in the future. With the entire population facing chronic illness and activity limitations, a universal approach to disability is virtually required, rather than policies focusing exclusively on a person's special needs. The absence of such a universal perspective will lead to the expansion and perpetuation of the segregated and unequal society visible at present.

Aged↗

PubMed1988

Polymorphism of rat gastric mucosal histidine decarboxylase: effects of the coenzyme and sulfhydryl groups.

Several factors are examined for their implication in the charge heterogeneity and form conversion of rat gastric mucosal histidine decarboxylase. The apoenzyme and the holoenzyme are undistinguishable with respect to their pI and to the distribution of enzyme activity in the three forms. The latter are not produced by differential coenzyme binding. Studies for glycoprotein characterization provide evidence that the heterogeneity does not arise from enzyme-bound carbohydrate. Oxidative or reductive environments change the distribution between forms without modifying the molecular weight. Conversion of form III to forms I and II can be effected by treatment with dithiothreitol. A similar loss of negatively charged form occurs upon ageing and is not prevented by an alkylating agent. All three forms show equal sensitivity to N-ethylmaleimide and dithiothreitol inhibitions. The oxidation-reduction state of exposed sulfhydryl groups may be responsible at least in part for the charge heterogeneity.

Animals↗

PubMed1986

Developmental concerns and the health of midlife women.

Prior to providing anticipatory guidance to a woman approaching or at middle age, the nurse should explore her own and her client's expectations of middle age and work to dispel any existing myths. Menopause is not inevitably a time of increased depression or nervous symptomatology. In addition, women whose children are gone from the home are not at increased risk for depression or low life satisfaction. However, we do know that the majority of women experience vasomotor symptoms including hot flashes and night sweats which are directly attributable to the hormonal changes accompanying menopause. The middle-aged woman may begin to note changes in her physical appearance and level of physical energy. This point in life can also be associated with a variety of transitions, including changes in the parental and marital role, the care and death of aging parents, and the loss of a spouse through death or divorce. As the familial environment changes for a woman, work outside the home may take on a different meaning. This stage of life can be one of growth as the woman seeks new directions or it can be a time of dissatisfaction. No one factor distinguishes those who cope well from those who do not. When identifying those women at risk for midlife developmental crises, the nurse must consider the interaction risk for midlife developmental crises, the nurse must consider the interaction of multiple factors. Preliminary evidence suggests that some women may experience a decreased sense of life satisfaction at the time of menopause.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Psychological↗

PubMed1986

Regulation of hematopoiesis in rats exposed to antiorthostatic hypokinetic/hypodynamia: II. Mechanisms of the "anemia".

Results are presented which demonstrate a close similarity between the ability of antiorthostatic hypokinetic/hypodynamia and orthostatic hypokinetic/hypodynamia to induce anemia in laboratory rats. The "restraint anemia" (whether mediated directly by reduced activity or indirectly by possible changes in blood circulation or in altered weight-bearing capacity of the skeleton) was largely due to reduced food and/or water consumption and displayed the classical symptoms of inadequate nutrition, i.e. decreased serum erythropoietin (Ep) titers and reduced Ep sensitivity of hematopoietic tissue. Only changes in red blood cell (RBC) clearance were unique to the head-down (antiorthostatic) posture. During suspension, RBC clearance was reduced and then accelerated when suspension was terminated or the cells transfused into a normal environment. Changes in RBC clearance were due to both cell-associated and cell-independent factors and may be related to the alterations in RBC survival seen in rats during or immediately after space flight. In both suspension and weightlessness, these changes were limited to alterations in the force and/or direction of the gravity vector.

Anemia↗

PubMed1967

Qualitative and quantitative characteristics adult Culex pipiens fatigans populations according to time, site and place of capture.

The composition of a vector population is largely influenced by the pressures and modifying effects of the environment. Changes in the latter, whether natural or induced (e.g., by insecticides) will be reflected in the former. Thus if the existing characteristics of a vector population are determined, the parameters can subsequently be used to assess the effect of control measures.The effect of environmental conditions on the density and parity of Culex pipiens fatigans in catches in Burma is illustrated by a comparison of results obtained in Kemmendine, which is served by a bucket system for the removal of night-soil, with those from South Okkalapa, which has pit latrines; in the latter area there is a large preponderance of young mosquitos in the monsoon period, in contrast to the situation in Kemmendine.In Kemmendine, the inside-biting catch is reduced by about one-half if an inside-resting catch is made simultaneously. This suggests that C. p. fatigans rests indoors before biting indoors and that an efficient insecticide for inside application would markedly reduce the mosquito population. When a correction is made for the inside-resting catch it is shown that there is little to choose between inside- and outside-biting catches as measures of the activity of C. p. fatigans. The chances of acquiring infection are at least as great out of doors as indoors and this may account for differences in infectivity among different ethnic groups, according to the extent that they sleep out of doors.Differences in parity and in the state of infection of mosquitos according to the type of catch and the time of catching are discussed. Finally, it is noted that, although most male mosquitos are obtained in inside-resting catches, a considerable number, surprisingly, are taken on bait; the reason for this is not yet known.

Adaptation, Biological↗

PubMed1977

Carboxyhaemoglobin saturation in relation to smoking and various occupational conditions.

The effects of smoking and occupational conditions on COHb saturation were studied among employees on traffic duty, in restaurants, in iron foundries, and in an office. The subjects were 139 smokers and 152 nonsmokers working in the same environments. Changes in COHb saturation were observed in samples of blood obtained before and after the working period. Samples of air were collected during the working hours in restaurants, in foundries and in office, 190 samples in all, for the determination of content of CO. Among the nonsmokers there was no change in COHb saturation in restaurants and in office work. On traffic duty and in iron foundries the increase was significant, but the values after work were less than half the permitted occupational threshold limit value (TLV) level of 6 per cent units. In the smoking group the mean values of COHb saturation before work were about twice the mean COHb saturation in the nonsmokers after work. In office work and in foundries the mean COHb saturations after the work exceeded the permitted TLV.

Adolescent↗