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PubMed2005

Effects of arginine vasotocin (AVT) on the behavioral, cardiovascular, and corticosterone responses of starlings (Sturnus vulgaris) to crowding.

Previous studies in European starlings have concluded that conspecific crowding can be a significant stressor that is capable of simultaneously altering behavior, heart rate, and corticosterone (CORT) concentrations. It was hypothesized that the peptide hormone arginine vasotocin (AVT) has a role in the regulation of these three types of responses to crowding. Four male and four female resident starlings were submitted to nine combinations of 3 crowding treatments (0, 1, or 5 intruder starlings) and 3 subcutaneous injections (1, 4 microg AVT, and saline control). Resident starlings were given a treatment injection, their heart rate and behavior were monitored for 30 min, 0, 1, or 5 intruder Starlings were allowed to enter the residents cage, and HR and behavior were monitored for another 30 min. Blood samples were taken before and after all treatments to assess CORT concentrations. Exogenous AVT decreased the frequency of maintenance behaviors (feeding, drinking, preening, and beak wiping), as well as activity in resident starlings. Although aggressive behaviors upright posture, head feather expansion, and pecking) increased during crowding, these increases were significantly attenuated by AVT. Heart rate was significantly lower during these behavioral effects, and the CORT data indicate that the cardiovascular and behavioral effects are not dependent on significant increases in CORT. These data support the hypothesis that AVT's attenuation of general behavior and crowding induced aggression are modulated by a cardiovascular mechanism.

Aggression↗
PubMed2000

Cross-cultural differences in tolerance for crowding: fact or fiction?

It is widely believed that cultures vary in their tolerance for crowding. There is, however, little evidence to substantiate this belief, coupled with serious shortcomings in the extant literature. Tolerance for crowding has been confused with cultural differences in personal space preferences along with perceived crowding. Furthermore, the few studies that have examined cultural variability in reactions to crowding have compared subgroup correlations, which is not equivalent to a statistical interaction. Although the authors found a statistical interaction indicating that Asian Americans and Latin Americans differ in the way they perceive crowding in comparison to their fellow Anglo-American and African American citizens, all four ethnic groups suffer similar, negative psychological distress sequelae of high-density housing. These results hold independently of household income.

Adult↗
PubMed2003

A conceptual model of emergency department crowding.

Emergency department (ED) crowding has become a major barrier to receiving timely emergency care in the United States. Despite widespread recognition of the problem, the research and policy agendas needed to understand and address ED crowding are just beginning to unfold. We present a conceptual model of ED crowding to help researchers, administrators, and policymakers understand its causes and develop potential solutions. The conceptual model partitions ED crowding into 3 interdependent components: input, throughput, and output. These components exist within an acute care system that is characterized by the delivery of unscheduled care. The goal of the conceptual model is to provide a practical framework on which an organized research, policy, and operations management agenda can be based to alleviate ED crowding.

Acute Disease↗
PubMed1995

Perception of crowding among children and adolescents.

The effects of spatial orientation (closed vs. open) and furniture arrangement (side vs. central) on Indian children's (6 to 8 years) and adolescents' (16 to 18 years) perceptions of crowding were studied, using Desor's (1972) Crowding Perception Test. The results indicated that spatial orientation and furniture arrangement had different effects on children's and adolescents' perceptions of crowding. The children perceived less crowding than the adolescents did, and central furniture arrangement was perceived as more crowded than side furniture arrangement was.

Adolescent↗
PubMed2003

Development and validation of a new index to measure emergency department crowding.

OBJECTIVES: To develop a quantitative measure of emergency department (ED) crowding and busyness. METHODS: A five-week study in spring 2002 in an urban teaching ED compared a new index (the Emergency Department Work Index [EDWIN]) with attending physician and nurse ratings of crowding. EDWIN is defined as summation operator n(i)t(i)/N(a)(B(T)-B(A)), where n(i) = number of patients in the ED in triage category i, t(i) = triage category, N(a) = number of attending physicians on duty, B(T) = number of treatment bays, and B(A) = number of admitted patients in the ED. The triage system used is the Emergency Severity Index (ESI), which was modified by reversing the ranking of triage categories; that is, an ESI score of 1 represented the least acute patient and 5 the sickest. EDWIN was calculated every two hours in a convenience sample of 60 eight-hour shifts. With each measurement, the charge attending physician and nurse estimated how busy/crowded the ED was, using a Likert scale. Nurse and physician assessments were averaged and compared with EDWIN scores. Data were analyzed with SPSS 10.0 (SPSS Inc., Chicago, IL). RESULTS: A total of 2,647 patients aged 18 years and older were assessed at 225 time points over 35 consecutive days. Nurses and physicians showed good interrater agreement of crowding assessment (weighted kappa 0.61, 95% confidence interval = 0.53 to 0.69). Median EDWIN scores and interquartile ranges (IQRs) when the ED was rated as not busy, average, and very busy were 1.07 (IQR = 0.80 to 1.55), 1.55 (IQR = 1.16 to 1.93), and 1.83 (IQR = 1.42 to 2.45) (p < 0.001). The ED was on diversion for 17 time blocks (6.5% of all blocks), with a median EDWIN of 2.77 (IQR = 1.83 to 3.63), compared with an EDWIN of 1.45 (IQR = 1.05 to 2.00) when not on diversion (p < 0.001). EDWIN scores correlated weakly with various process-of-care measures chosen as secondary end points. CONCLUSIONS: EDWIN correlated well with staff assessment of ED crowding and diversion. The index can be programmed into tracking software for use as a "dashboard" to alert staff when the ED is approaching crisis. If validated across other sites, EDWIN may provide a tool to compare crowding levels among different EDs.

Adult↗
PubMed2001

Crowding and violence on psychiatric wards: explanatory models.

OBJECTIVE: Violence is widely prevalent on acute-care psychiatric wards, and crowding has been identified as a major risk factor. This paper explores why patients may respond to crowding with violence. METHOD: We carried out a literature review on Medline, using the key words "violence" and "crowding." We conducted an additional hand search of the references collected from the reviewed papers. RESULTS: Factors specific to the relation between crowding on acute-care inpatient psychiatric wards and violence can be divided under the following headings: 1) patient density, privacy, and control; 2) ward architecture; 3) the social organization of psychiatric wards; 4) interpersonal space; 5) phylogenic theories; and 6) anthropological theories of human behaviour. CONCLUSIONS: We offer explanatory models for this relation and suggest strategies to counter the effects of crowding. Recommendations are made for future studies.

Crowding↗
PubMed2004

Care in the emergency department: how crowded is overcrowded?

OBJECTIVES: To examine how emergency department (ED) overcrowding has been defined in the medical literature. METHODS: Using the National Library of Medicine's PubMed and MEDLINE databases (1966 to 2002), a comprehensive review of the English-language medical literature was conducted to identify explicit criteria for defining ED overcrowding. Inclusion criteria were original articles, editorials, and reviews; news articles and letters to the editor were excluded. Using a standardized extraction form, publications were described as primary if the title or an objective statement in the introductory or methods paragraph referred to crowding or overcrowding; all other citations were categorized as secondary. Each report was then evaluated to determine whether crowding or overcrowding was defined explicitly or implicitly. Explicit definitions included phrases such as "Crowding was defined as ..." or "Overcrowding occurred when ..."; other definitions were characterized as implicit. RESULTS: A total of 231 candidate articles were identified; 91 met inclusion criteria, and 53 (58%) were primary articles about ED crowding or overcrowding. Among these primary articles, 23 (43%) had explicit definitions of crowding or overcrowding. The definitions varied widely in content and focus, including ED, hospital, or external (nonhospital) factors. CONCLUSIONS: Although ED overcrowding has been a topic of frequent investigation, current definitions of the problem are often implicit or focus on factors outside of the ED itself. A more consistent approach to defining ED overcrowding would help to clarify the distinctions between causes, characteristics, and outcomes of overcrowding.

Crowding↗
PubMed1987

Effect of dietary supplementation with vitamin C or carbadox on weanling pigs subjected to crowding stress.

A 2 X 3 factorial arrangement was used in each of two trials with two levels of floor space allowance (.25, .13 m2/pig) and three dietary treatments (basal, basal + 660 ppm vitamin C, basal + 55 ppm carbadox). The reduction in floor space allowance was achieved in trial 1 by doubling the number of pigs/pen from eight to 16 and in trial 2 by reducing the size of pens by half. An 18% protein starter diet was used as the basal diet. Total numbers of pigs used were 216 in trial 1 and 144 in trial 2. Pigs were weaned between 4 and 5 wk of age (7.5 kg average wt) and fed ad libitum for 28 d. Reducing floor space allowance caused a (P less than .05) reduction in weight gain of weanling pigs in both trials. When the reduction of floor space allowance was done by increasing number of pigs/pen (trial 1), pigs responded with a significantly reduced feed intake with no change in efficiency of feed utilization. However, when floor space allowance was reduced by changing the size of the pen (trial 2), feed intake of pigs was not affected but efficiency of feed utilization was reduced significantly. Neither form of crowding affected vitamin C concentration in adrenal glands and weights of adrenal glands, spleen and thymus. Dietary supplementation of carbadox, but not vitamin C, produced significantly greater weight gain, feed efficiency, and spleen weight of pigs in both trials. Although there was no interaction between crowding and dietary treatment in affecting the performance of pigs, supplemental carbadox improved the performance of crowding-stressed pigs by maintaining an adequate level of feed intake and improving feed efficiency, whether crowding was caused by increased pig density or by reduced pen size. No significant differences in phytohemagglutinin (PHA) skin test response or in the neutrophil-to-lymphocyte ratio (N/L) were observed among treatments in trial 1, while a significantly reduced response to PHA and a higher N/L were detected in crowding-stressed pigs in trial 2.

Animals↗
PubMed1982

[The influence of persistent crowding on the spontaneous motor activity of the aging rat (author's transl)].

In the course of a long-term cohort study of stress and aging, the spontaneous activity of 169 male Sprague-Dawley rats was measured at various ages from 9 to 30 months. 84 animals were submitted to crowding from the age of 5 months onwards by housing them in groups of 12 per Makrolon-IV cage. 85 rats, kept as usual in groups of 6 per makrolon-IV cage, served as a control. Spontaneous activity was assessed by an electronic instrument (Animex Activity Meter), which also enabled us to distinguish between total and large movements. During senescence, the spontaneous activity of the control animals decreased slightly by approximately 20% after the age of 18 months. In addition to the quantitative change, a progressive flattening of the activity rhythm was observed. The animals kept under crowded conditions did not reveal any age-related decrease in spontaneous activity. At an advanced age, this resulted in significantly higher activity values in the crowded group as compared with the controls. The differences appeared even earlier and seemed to be more pronounced in the number of large movements. However, the progressive disappearance of the endogenous rhythm was apparent in both the crowded and the control group. It can be concluded that at least two types of change in the central nervous system may be responsible for the aging-changes in spontaneous activity: one which disintegrates the "time structure" of the organism, and a second one which affects motivational centers. Crowded conditions seem to improve the latter, whereas they have no effect on the aging of the "biological clock".

Age Factors↗
PubMedDate not supplied

Crowding.

Crowding is the situation in which case a large number of animals, including man, are restricted in environmental space. Such an occurrence may start with just a few animals. In plants, including bacteria in culture, agriculture may be considered as an artificial example of this process. We see the ontogenic forms of crowding developing from stress into superorganisms (such as certain social insects) and from stress into pathological crowding in animals, plants and man. Crowding is shown by environmental changes such as in the introduction of new species of certain rodents and lagomorphs into the Australian environment. Aspects of crowding play a role during the housing of zoos, domestic or laboratory animals. Space limitations and overpopulation initiates stress and infections such as tuberculosis and tumours. This is found in man himself in the development of slums through to urbanisation as seen in Asia particularly, in prisons, in the workplace, in the school or home.

Animals↗
PubMed1976

Crowding and human reproduction.

Studies of crowding in lower animals repeatedly demonstrate that compressed living conditions depress the ability of the species to reproduce. In a sample of 470 urban Toronto women we examined the effect of neighborhood and household crowding on the probability of a pregnancy and on the probability that any given product of the pregnancy will not survive until one year of age. Crowding did not influence fertility nor fetal and infant survival within the range of crowding found in this sample. If crowding has any influence on reproduction it would more profitably be investigated beyond the range of living density and housing markets found in North American urban areas.

Abortion, Legal↗
PubMed2006

Effect of molecular crowding on DNA polymerase activity.

Live cells contain high concentrations of macromolecules, but almost all experimental biochemical data have been generated from dilute solutions that do not reflect conditions in vivo. To understand biomolecular behavior in vivo, properties studied in vitro are extrapolated to conditions in vivo; however, the molecular conditions within live cells are inherently crowded. The present study investigates the effect of molecular crowding on DNA polymerase activity using polyethylene glycol PEG of various molecular weights as a crowding agent. Polymerase activity assays under various conditions demonstrated that the activities of T7 and Taq DNA polymerases depend on the molecular weight and concentration of the crowding agent. Furthermore, equilibrium and kinetic analyses demonstrated that the binding affinity and catalytic activity of the polymerase increase and decrease, respectively, with increasing PEG concentrations. Based on quantitative parameters of the polymerase reactions, we improved the efficiency of PCR amplification under conditions of molecular crowding. These results suggest that quantitative measurements of biomolecular structure and function are useful for understanding the behavior of biomolecules in vivo and for biotechnology applications in vitro.

Colloids↗
PubMed2007

Albumin is a redox-active crowding agent that promotes oxidative folding of cysteine-rich peptides.

Oxidative folding that occurs in a crowded cellular milieu is characterized by multifaceted interactions that occur among nascent polypeptides and resident components of the endoplasmic reticulum (ER) lumen. Macromolecular crowding has been considered an essential factor in the folding of polypeptides, but the excluded volume effect has not been evaluated for small, disulfide-rich peptides. In the research presented, we examined how macromolecular crowding agents, such as albumin, ovalbumin, and polysaccharides, influenced the kinetics and thermodynamics of forming disulfide bonds in four model peptides of varying molecular size from 13 residues (1.4 kDa) to 58-residues (6.5 kDa): conotoxins: GI, PVIIA, r11a, and bovine pancreatic trypsin inhibitor. Our results indicate that the excluded volume effect does not significantly alter the folding rates nor equilibria for these peptides. In stark contrast, folding reactions were dramatically accelerated, when protein-based crowding agents were present at concentrations lower than those predicted to provide the excluded volume effect. Submillimolar albumin alone was as effective as glutathione in promoting the oxidative folding of GI conotoxin at concentrations typically found in the ER. To the best of our knowledge, this is the first report and quantitative characterization of oxidative folding of peptides mediated by other than thioredoxin-based protein disulfide bonds. Our work raises a possibility that concurrent secretory and ER-resident proteins may influence the oxidative folding of small, cysteine-rich peptides not as crowding agents, but as redox-active factors.

Albumins↗
PubMed2004

Biochemical effects of molecular crowding.

Cell cytoplasm contains high concentrations of high-molecular-weight components that occupy a substantial part of the volume of the medium (crowding conditions). The effect of crowding on biochemical processes proceeding in the cell (conformational transitions of biomacromolecules, assembling of macromolecular structures, protein folding, protein aggregation, etc.) is discussed in this review. The excluded volume concept, which allows the effects of crowding on biochemical reactions to be quantitatively described, is considered. Experimental data demonstrating the biochemical effects of crowding imitated by both low-molecular-weight and high-molecular-weight crowding agents are summarized.

Cytoplasm↗
PubMed1981

A biometric study of tooth size and dental crowding.

A study was conducted for the purpose of comparing mesiodistal tooth widths between a group of patients with good tooth alignment and a group of patients with crowded dental arches. Crowded arches were defined as those with more than 4 mm. of space deficiency. The hypothesis tested was whether the arches with more than 4 mm. of crowding consistently had larger teeth than the ones with lesser or no crowding. The difference in sizes between the groups (forty males and forty females) for all teeth measured was found to be statistically significant (p less than 0.001). The multivariate data analysis indicated that the two groups were derived from two different populations and that the maxillary lateral incisors and second premolars and the mandibular canines and premolars were particularly different in these groups. It was also determined that the teeth in males were uniformly larger than in females, but not to a statistically significant level. There was less correlation, however, between the sex and the status of the tooth alignment in dental arches, so that both sexes had similar distribution of crowding versus noncrowding. On the basis of this study of eighty North American Caucasians, it is suggested that one should consider the sum of mesiodistal widths of teeth, in addition to the arch length analysis, in formulating an orthodontic treatment plan. When the cumulative tooth mass of the twenty permanent teeth is 140 mm. or more, the clinician may want to consider extraction therapy for such a case.

Adolescent↗
PubMed2004

Postretention relapse of mandibular anterior crowding in patients treated without mandibular premolar extraction.

Treatment stability is one of the most important objectives in orthodontics, but, despite decades of research, it is still agreed that the stability of aligned teeth is variable and largely unpredictable. This study aimed to evaluate the relapse of mandibular anterior crowding in patients treated without mandibular premolar extraction. The sample comprised 40 patients of both sexes with Class I or II malocclusions who received nonextraction treatment in the mandibular arch with edgewise mechanics. Lateral cephalograms and dental casts of each patient were obtained at pretreament, posttreatment, and 5 years postretention. Relapse of mandibular anterior crowding was assessed, and associations between this relapse and other clinical factors were also investigated. Mandibular anterior crowding was measured by the Little irregularity index, and the data were evaluated by the Mann-Whitney test. The mean relapse of mandibular anterior crowding was 1.95 mm (26.54%) over the long term. No clinical factor studied was predictive of crowding relapse in the long term.

Bicuspid↗
PubMed2026

Glycogen-dependent demixing of frog egg cytoplasm at increased crowding.

Crowding increases the tendency of macromolecules to aggregate and phase separate, and regulated crowding contributes to subcellular organization and stress response. To explore the effect of crowding in a well-characterized model cytoplasm, we developed methods to concentrate the macromolecule components of Xenopus egg extracts without changing small molecules. Egg cytoplasm contains a high concentration of glycogen that serves as an energy store for early development. When crowding was increased 1.4&#xd7;, the egg cytoplasm demixed into two liquid phases of approximately equal volume, one of which was highly enriched in glycogen. Glycogen hydrolysis prevented and reversed demixing. Quantitative proteomics showed that the glycogen-rich phase was enriched in proteins that bind glycogen, participate in carbohydrate metabolism, or are part of very high-molecular-weight complexes. The glycogen-depleted phase was enriched in ribosomes, endoplasmic reticulum (ER), and mitochondria. Smaller soluble proteins were approximately equipartitioned. Glycogen is usually observed in aggregates in intact cells, and recent work suggested a role for phase separation in its localization. Our results show that glycogen particles can spontaneously demix and suggest that demixing may be regulated by crowding.

Animals↗
PubMed2004

Molecular crowding as a mechanism for tick secretory granule biogenesis.

During feeding ticks secrete bioactive components into the host to counter-act its immune and hemostatic defense systems. These bioactive components are stored in secretory granules that are secreted during feeding in an exocrine stimulus-response type of mechanism. All proteins destined for secretion are packaged into these granules during granule biogenesis. Up to date no mechanism for granule biogenesis has been proposed, except to note that biogenesis occurs under conditions of high protein and calcium concentrations in an acidic environment. Previously, the most abundant proteins (TSGPs) found in the salivary glands of the soft tick, Ornithodoros savignyi, were suggested to play a part in granule biogenesis, based on their high abundance. The TSGPs are part of the lipocalin family, of which numerous members have been identified in ticks. We consider here the high concentrations of the TSGPs in salivary glands and what effect this will have on the crowded environment inside the secretory granules. It is shown that the TSGPs occur at concentrations that will lead to molecular crowding of which one result is the non-specific aggregation of components to reduce crowding effects. Aggregation of proteins as a mechanism of granule biogenesis has been proposed before, but not in terms of molecular crowding. We thus propose molecular crowding as the general mechanism of granule biogenesis, in tick secretory granules, but can also be extended to other forms of secretory granules in general.

Animals↗