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PubMed2005

Air quality, tobacco smoke, urban crowding and day care: modern menaces and their effects on health.

BACKGROUND: The known adverse health effects of outdoor air pollution were reduced in the last century by effective legislation and pollution control. Although combustion of biomass fuels in the indoor environment remains a major hazard in developing countries, there has been a change in the nature of the traffic-generated air pollutants in outdoor air in developed countries. The role of day care and siblings in increasing the risk of infection early in life contrasts with protection from allergic disease later. METHODS: The mechanisms of how these pollutants exert their effects are poorly understood, but there is emerging evidence that the toxic effects may be related to infection. This synopsis discusses the epidemiologic relationship of the menaces of modern living, including air pollution, urban crowding and infection, and will explore some of the mechanisms of how they act synergistically to cause exacerbations of illnesses in individuals with preexisting respiratory conditions, such as asthma. It will also discuss the roles of day care and siblings in relation to respiratory disease risk. RESULTS: Current evidence suggests that much of the morbidity and mortality related to sources of both indoor and outdoor pollution occur by causing or interacting with respiratory infection and other acute or chronic health conditions, such as asthma. CONCLUSION: Improvements in air quality through efforts to tackle environmental problems such as pollution and tobacco smoke will help achieve better health. Day care and siblings increase infectious disease early in life but are associated with protection against development of allergic disease later.

Adolescent↗
PubMed2004

Sex-specific response of a mosquito to parasites and crowding.

Host-parasite interactions are significantly influenced by the sex of the host and the environment in which the host is found. Sex-specific responses to parasite infection, however, may change according to the host environment. I examine the combined effect of parasite infection and crowding on males and females of the mosquito Aedes albopictus. At a high larval density, infected males experienced a greater relative reduction in body size than did infected females, whereas the pattern was reversed at low density. This experiment demonstrates the importance of the environment on sex-specific responses to parasites and contributes to a growing body of work examining sources of variation in host-parasite interactions.

Aedes↗
PubMed2002

Risk factors for burns in children: crowding, poverty, and poor maternal education.

OBJECTIVE: To characterize the presentation of burns in children and risk factors associated with their occurrence in a developing country as a basis for future prevention programs. DESIGN: Case-control study. SETTING: Burn unit of the National Institute of Child Health (Instituto Nacional de Salud del Niño) in Lima, Peru. METHODS: A questionnaire was administered to all consenting guardians of children admitted to the burns (cases) and general medicine (controls) units during a period of 14 months. Guardians of patients were questioned regarding etiology of the injury, demographic and socioeconomic data. RESULTS: 740 cases and controls were enrolled. Altogether 77.5% of the cases burns occurred in the patient's home, with 67.8% in the kitchen; 74% were due to scalding. Most involved children younger than 5 years. Lack of water supply (odds ratio (OR) 5.2, 95% confidence interval (CI) 2.1 to 1 2.3), low income (OR 2.8, 95% CI 2.0 to 3.9), and crowding (OR 2.5, 95%CI 1.7 to 3.6) were associated with an increased risk. The presence of a living room (OR 0.6, 95% CI 0.4 to 0.8) and better maternal education (OR 0.6, 95% CI 0.5 to 0.9) were protective factors. CONCLUSIONS: To prevent burns interventions should be directed to low socioeconomic status groups; these interventions should be designed accordingly to local risk factors.

Adolescent↗
PubMed2001

Ward crowding and incidents of violence on an acute psychiatric inpatient unit.

OBJECTIVE: Violence in psychiatric wards is common, and it is on the rise. This study examined the relationship between ward occupancy level and staff-to-patient ratio and incidents of aggressive behavior, both physical and verbal, on an acute inpatient unit in rural New Zealand. METHODS: Logistic regression was used to analyze data collected from the ward's log of adverse incidents and the ward census over a 12-month period. A physical incident was defined as an unwelcome physical contact or willful damage to property. Incidents of self-harm were excluded. Verbal aggression was any threat of physical or sexual harm. RESULTS: Among 381 admissions during the study period, 58 incidents were recorded--25 incidents of verbal aggression and 33 incidents of physical violence. Logistic regression demonstrated that the occupancy level was positively associated with the occurrence of any type of violent incident. The average occupancy level when an incident occurred was 77 percent, compared with 69 percent when no incidents occurred. The average occupancy level was significantly higher when verbal incidents occurred (80 percent) than when physical incidents occurred (70 percent). No association was found between violence and staff-to-patient ratio. Incidents were significantly more likely to occur during the afternoon shifts (3 p.m. to 11 p.m.). CONCLUSIONS: Crowding was found to be significantly associated with aggressive incidents, and in particular with verbal aggression.

Acute Disease↗
PubMed1999

Crowding and aggression on inpatient psychiatric wards.

The association between crowding and aggressive behavior among psychiatric inpatients was investigated. Aggressive incidents were documented on two closed psychiatric wards between February 1 and December 15, 1996. A modest correlation between number of patients on the ward and number of aggressive incidents per patient was found. Enlargement of the physical space by the addition of a courtyard to one of the wards midway through the study did not lead to a significant decline in incidents. Possibly, a lack of psychological space-having no privacy or not being able to get sufficient rest-may be more important in triggering aggression than a lack of physical space.

Adolescent↗
PubMed1999

Crowding and violent behavior: the influence of patient density on violent and self-harming behaviour at a medium secure unit.

This study examines the influence of patient density (crowding) and number of potential perpetrators on the number of incidents of violence and self-harm at a medium secure unit. Of 2,053 incidents examined over a period of 974 days, 73% were perpetrated by 20% of the patients, the majority by patients identified as potential perpetrators. Increased patient density was not associated with increased risk of violence or self-harm. There was no evidence to suggest that the presence of those identified as potentially violent or self-harming increased the risk of others engaging in such behaviour.

Crowding↗
PubMed1977

Socialization and the human physiologic response to crowding.

Cross-sectional data were analyzed for a possible relationship between household densities and physiologic alteration, based on socialization experiences with siblings in an earlier home environment. The measure of household density was persons-per-room and the measure of physiologic alteration was urinary vanillylmandelic acid. The results show an interaction between number-of-sibs and number-of-younger-sibs, with a statistically significant positive correlation between household densities and VMA values for subjects with fewer total sibs and no younger sibs, while a negative correlation was observed for subjects with one or more younger sibs. One possible interpretation of these results is that the physiologic response to crowding in humans is dependent at least in part on the earlier socialization experiences of the individual.

Cross-Sectional Studies↗
PubMedDate not supplied

Placing emergency department crowding on the decision agenda.

The causes of emergency department crowding (EDC), and the outcomes and strategies for resolution are reviewed. This is a call to the nursing profession to elevate EDC on hospital, community, and national agendas to garner resources to restore timely emergency care.

Crowding↗
PubMedDate not supplied

Hospital crowding and ED delays: a case study.

Strategic Planning: By growing its organizational capacity, Lehigh Valley Hospital and Health Network in Allentown, Pa., found multiple ways to reduce hospital crowding and ED delays.

Accidents, Traffic↗
PubMed1990

The "crowding effect" phenomenon in Ascaris lumbricoides.

Ascaris lumbricoides worm populations were studied from 150 Filipino children (0-14 years) dewormed with pyrantel pamoate (Combantrin) or oxantel-pyrantel pamoate (Quantrel). Populations were classified according to intensity of infection: very light, light, moderate or heavy. A total of 2072 adult worms were sexed (939 males and 1133 females) and weighed. Descriptive statistics on the weights obtained from each sex were derived and one-way ANOVA was performed to compare the mean weights among the 4 intensity classes. Linear regression analysis (individual worm weight versus total worm burden) was also employed to equalize the possible influence of host factors. Statistical analysis revealed that mean weights of both sexes were significantly different and decreased as worm burden increased. This strongly suggests that the "crowding effect" phenomenon may also apply to Ascaris lumbricoides, and not only to tapeworms, as reported in the literature.

Adolescent↗
PubMed1988

Effects of social isolation and crowding upon adrenocortical reactivity and behavior in the rat.

The effects of social isolation and crowding on adrenocortical function and upon behavioral responsiveness to electric shock have been studied in male and female rats. All female experimental groups showed higher corticosterone levels and heavier adrenals than their male counterparts. The major effect of housing condition concerned the corticosterone response to stress, while basal hormone concentration was not modified. Socially housed rats showed a more intense adrenocortical response and also a greater behavioral reactivity to electric shock than the isolates.

Adrenal Glands↗
PubMed1988

Stressful crowding during pregnancy advances onset of offspring adrenocortical rhythm.

Stress by crowding and disturbance during the final third of pregnancy in mice advanced the onset of the diurnal plasma corticosterone rhythm in the male offspring from day 25 to day 18. Treated pups showed this altered development whether fostered to treated or to control dams, but it was not apparent in control pups raised by treated dams. Graded adrenocortical responses to increasingly stressful stimuli were not affected by stress during gestation.

Adrenal Cortex↗
PubMed1983

The effects of crowding on adults of Philophthalmus gralli (Trematoda) grown in chickens.

Chickens were infected with six, 10, 30, 50, or 100 metacercariae of Philophthalmus gralli per eye and the adults were harvested 9, 14, 21, 35, and 50 days later. The worms recovered were measured and assessed for maturity. Significantly more adults from infections of six and 10 metacercariae per eye were recovered than from infections of 100 per eye. When metacercariae were placed in one eye, over one-fourth of the resulting adults were found in the opposite eye. Worms recovered from groups of zero to 10 were significantly longer than those in groups of 41 to 50 and 51 to 60 at all ages sampled. The normal movement of worms from the conjunctival sac to the outside of the nictitating membrane was hindered by crowding; when more than 10 were present, some worms developed in the sac to mature adults. Worms in all groups produced eggs in which miracidia developed at the same rate.

Animals↗
PubMedDate not supplied

[Oxyuriasis: its indoor transmission correlated with crowding in housing].

In two different human settings in the province of Pavia, Italy, statistically significant correlations were found between socioeconomic level of the families or crowding in the houses, and prevalence of oxyuriasis in schoolchildren. An indoor transmission is postulated.

Chi-Square Distribution↗
PubMed2004

Using hydrogen bonds to direct the assembly of crowded aromatics.

This Minireview details the design, synthesis, and self-assembly of a new class of crowded aromatics that form columnar superstructures. The assembly of these subunits produces helical and polar stacks, whose assembly can be directed with electric fields. In concentrated solutions, these self-assembled helical rods exhibit superhelical arrangements that reflect circularly polarized light at visible wavelengths. Depending on the side chains employed, spin-cast films yield either polar monolayers or isolated strands of molecules that can be visualized with scanning probe microscopy. Also detailed herein are methods to link these mesogens together to produce monodisperse oligomers that fold into defined secondary conformations.

Hydrocarbons, Aromatic↗
PubMed2006

Remarkable interplay of redox states and conformational changes in a sterically crowded, cross-conjugated tetrathiafulvalene vinylog.

Derivatives of 9-[2-(1,3-dithiol-2-ylidene)ethylidene]thioxanthene have been synthesized using Horner-Wadsworth-Emmons reactions of (1,3-dithiol-2-yl)phosphonate reagents with thioxanthen-9-ylidene-acetaldehyde (5). Further reactions lead to the sterically crowded cross-conjugated "vinylogous tetrathiafulvalene" derivative 9-[2,3-bis-(4,5-dimethyl-1,3-dithiol-2-ylidene)-propylidene]thioxanthene (10). X-ray crystallography, solution electrochemistry, optical spectroscopy, spectroelectrochemistry, and simultaneous electrochemistry and electron paramagnetic resonance spectroscopy, combined with theoretical calculations performed at the B3LYP/6-31G(d) level, elucidate the interplay of the electronic and structural properties in these molecules. For compound 10, multistage redox behavior is observed: the overall electrochemical process can be represented by 10-->10(.+)-->10(2+)-->10(4+) with good reversibility for the 10-->10(.+)-->10(2+) transformations. At the tetracation stage there is the maximum gain in aromaticity at the dithiolium and thioxanthenium rings. Theory predicts that for 10, 10(.+), and 10(2+) the trans isomers are more stable than the cis isomers (by ca. 2-18 kJ mol(-1)), whereas for 10(4+) the cis isomer becomes more stable than the trans isomer (by ca. 25 kJ mol(-1)) [trans and cis refer to the arrangement of the two dithiole moieties with respect to the central ==C(R)--C(H)== fragment]. These data explain the detection in cyclic voltammograms of both trans and cis isomers of 10 and 10(.+) during the reduction of 10(4+) at fast scan rates (>100 mV s(-1)) when the cis-trans isomerization is not completed within the timescale of the experiment. The X-ray structure of the charge-transfer complex (CTC) of 10 with 2,4,5,7-tetranitrofluorene-9-dicyanomethylenefluorene (DTeF) [stoichiometry: 10(.+)(DTeF)(2) (.-)2 PhCl] reveals a twisted conformation of 10(.+) (driven by the bulky thioxanthene moiety) and provides a very rare example of segregated stacking of a fluorene acceptor in a CTC.

Journal Article↗
PubMed1981

Studies on a human melanoma cell line: effect of cell crowding and nutrient depletion on the biophysical and kinetic characteristics of the cells.

In an investigation of the changes that occur in cultured neoplastic cells as they outgrow their supply of nutrient, MM96 human melanoma cells were found to diminish in size and to proliferate more slowly. These changes were accompanied by a moderate increase in the proportion of cells with a G1-like DNA content. When replated under favorable conditions, many of these cells gradually resumed active proliferation. Continuing adverse culture conditions led to a continued fall in cell size, loss of reproductive viability, and finally to rapid cell death. Simultaneous buoyant-density and velocity-sedimentation-fractionation experiments showed that cells from exponential cultures were moderately dense and rapidly sedimenting, cells from postexponential cultures were less dense and much more slowly sedimenting, and dye-excluding cells from reproductively nonviable, late postexponential cultures were of widely variable though generally high density, and were moderately rapidly sedimenting. Although neither fractionation method resulted in significant enrichment of clonogenic cells, depletion was seen at both extremes of both types of profile. Cells fractionated by velocity were sorted according to DNA content and hence location in the cell cycle. The relationship between sedimentation rate and cell-cycle location was reflected in the continuous thymidine labeling patterns of the separated cells. Study of these patterns suggested that cycle durations lengthened as crowding increased and nutrient became depleted, and shortened upon reseeding at low density into fresh medium.

Cell Line↗
PubMedDate not supplied

Crowding in extremophiles: linkage between solvation and weak protein-protein interactions, stability and dynamics, provides insight into molecular adaptation.

The study of the molecular adaptation of microorganisms to extreme environments (solvent, temperature, etc.) has provided tools to investigate the complex relationships between protein-solvent and protein-protein interactions, protein stability and protein dynamics, and how they are modulated by the crowded environment of the cell. We have evaluated protein-solvent and protein-protein interactions by solution experiments (analytical ultracentrifugation, small angle neutron and X-ray scattering, density) and crystallography, and protein dynamics by energy resolved neutron scattering. This review concerns work from our laboratory on (i) proteins from extreme halophilic Archaea, and (ii) psychrophile, mesophile, thermophile and hyperthermophile bacterial cells.

Adaptation, Biological↗