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PubMed2000

Air-interface condition promotes the formation of tight corneal epithelial cell layers for drug transport studies.

PURPOSE: To identify the growth conditions that would favor the development of a functional primary culture of pigmented rabbit corneal epithelial cells on a permeable support comparable to the intact tissue in bioelectric properties. METHODS: Rabbit corneal epithelial cells were isolated and cultured on precoated fibronectin/collagen/laminin permeable filters. Cells were grown at an air-interface with supplemented DMEM/F12 medium. Immunofluorescence and electron microscopy techniques, respectively, were used to confirm cornea-specific marker and morphological features. Permeability of the cell layers to model polar compounds was evaluated using 14C-mannitol, fluorescein isothiocyanate (FITC) and fluorescein isothiocyanate-dextran of 4,000 molecular weight (FD4). RESULTS: We found that culturing the epithelial cells at an air-interface (AIC) was a critical factor in the formation of tight cell layer and that omitting fetal bovine serum and keeping the concentration of epidermal growth factor at 1 ng/ml were equally important. Phenotypically, the AIC cell layers were found to express cornea-specific 64 kD keratin. Compared with cells cultured under the liquid-covered (LCC) condition, those cultured under AIC exhibited a significantly higher peak transepithelial electrical resistance (TEER) of up to 5 kOhm x cm2, a higher potential difference (PD) of up to 26 mV, and an estimated short-circuit current (Ieq) of 5 microA/cm2 after 7-8 days of culture. These values were comparable to those in the excised cornea. Consistent with the TEER, the AIC cell layers were 4-40 times less permeable to paracellular markers than their LCC counterpart. CONCLUSIONS: The AIC model merits further characterization of drug transport mechanisms as well as drug, formulation, physiological, and pathological factors influencing corneal epithelial drug transport.

Animals↗
PubMed1978

[Investigation of the hygienic standard in two hospitals including the control of disinfection (author's transl)].

In two operative departments with different architectural presuppositions, the hygienic standard was checked up. Under favourable conditions in clinic B (Hosch-filter, sluice-systems) the relative frequency of demonstrable bacteria amounted to 55%. In clinic A, where these conditions failed, it amounted to 80%. Among the non pathogenic bacteria DNase-negative staphylococci were demonstrated more frequently than others. 13.4% and 18.9% resp. of the bacteria were DNase-positive staphylococci. We used Clostridium perfringens for detecting invasion-paths of germs. The most important ones are leaky windows, air conditioning and insufficient sluice-systems. The success of desinfection was examined. It fluctuates from 67% to 100%. One control amounted to 42%. The results show, that it is impossible to establish sterile rooms for common operative departments. But they show as well that a satisfying hygienic standard cannot be arrived without sluice-systems and appropriate air conditioning.

Bacteria↗
PubMed2005

Airborne exposure to trihalomethanes from tap water in homes with refrigeration-type and evaporative cooling systems.

This study evaluates airborne concentrations of common trihalomethane compounds (THM) in selected living spaces of homes supplied with chlorinated tap water containing >85 ppb total THM. Three small homes in an arid urban area were selected, each having three bedrooms, a full bath, and approximately 1000 square feet; two homes had standard (refrigeration-type) central air conditioning and the third had a central evaporative cooling system ("swamp cooler"). A high-end water-use pattern was used at each home in this exposure simulation. THM were concurrently measured on 4 separate test days in tap water and air in the bathroom, living room, the bedroom closest to the bathroom, and outside using Summa canisters. Chloroform (trichloromethane, TCM), bromodichloromethane (BDCM), and dibromochloromethane (DBCM) concentrations were quantified using U.S. EPA Method TO-14. The apparent volatilization fraction consistently followed the order: TCM > BDCM > DBCM. Relatively low airborne THM concentrations (similar to outdoors) were found in the living room and bedroom samples for the home with evaporative cooling, while the refrigeration-cooled homes showed significantly higher THM levels (three- to fourfold). This differential remained after normalizing the air concentrations based on estimated THM throughput or water concentrations. These findings indicate that, despite higher throughput of THM-containing water in homes using evaporative coolers, the higher air exchange rates associated with these systems rapidly clears THM to levels similar to ambient outdoor concentrations.

Air Conditioning↗
PubMed1986

Evaluation of building ventilation systems.

Over the past several years, NIOSH has responded to health hazard evaluation requests from workers in dozens of office environments. Typically, the employees have complained of headache, eye and upper respiratory tract irritation, dizziness, lethargy and the inability to concentrate. Most often "inadequate ventilation" has been blamed for these complaints. Of paramount importance in the evaluation and correction of these problems is an effective evaluation of the building's ventilation system. Heating, ventilating and air-conditioning conditions that can cause worker stresses include: migration of odors or chemical hazards between building areas; reentrainment of exhaust from building fume hoods or through heat wheels; buildup of microorganisms in the HVAC system components; and poor odor or environmental control due to insufficient "fresh" outdoor air or system heating or cooling malfunction. The purpose of this paper is to provide an overview of building ventilation systems, the ventilation problems associated with poorly designed or operating systems, and the methodology for effectively evaluating system performance.

Air Conditioning↗
PubMed2001

Investigation of the potential antimicrobial efficacy of sealants used in HVAC systems.

Recent experiments confirm field experience that duct cleaning alone may not provide adequate protection from regrowth of fungal contamination on fiberglass duct liner (FGDL). Current recommendations for remediation of fungally contaminated fiberglass duct materials specify complete removal of the materials. But removal of contaminated materials can be extremely expensive. Therefore, a common practice in the duct-cleaning industry is the postcleaning use of antimicrobial surface coatings with the implication that they may contain or limit regrowth. Little information is available on the efficacy of these treatments. This paper describes a study to evaluate whether three commercially available antimicrobial coatings, placed on a cleaned surface that 1 year previously had been actively growing microorganisms, would be able to prevent regrowth. The three coatings contained different active antimicrobial compounds. All three of the coatings were designed for use on heating, ventilation, and air conditioning (HVAC) system components or interior surfaces of lined and unlined duct systems. Coating I was a polyacrylate copolymer containing zinc oxide and borates. Coating II was an acrylic coating containing decabromodiphenyl oxide and antimony trioxide. Coating III was an acrylic primer containing a phosphated quaternary amine complex. The study included field and laboratory assessments. The three treatments were evaluated in an uncontrolled field setting in an actual duct system. The laboratory study broadened the field study to include a range of humidities under controlled conditions. Both static and dynamic chamber laboratory experiments were performed. The results showed that two of the three antimicrobial coatings limited the regrowth of fungal contamination, at least in the short term (the 3-month time span of the study); the third did not. Before use in the field, testing of the efficacy of antimicrobial coatings under realistic use conditions is recommended because antimicrobials have different baseline activities and interact differently with the substrate that contains them and their local environment.

Air Conditioning↗
PubMed1975

[A bacteriological study of the air in a surgical intensive care unit (author's transl)].

The air in a surgical intensive care unit was analysed with the view of ascertaining the influence on the bacterial content of the air of such medical and nursing procedures as intubation, X-ray examination, bladder washout, massage, physiotherapy, bedmaking. By means of a Casella slit sampler, placed in the middle of the room, it was established that the activities mentioned above caused the bacterial count to rise by 35-310 percent above the hourly determined normal level. In some cases the count did not return to normal until 30 minutes later. Simultaneous determinations of the dust content of the air by means of a Royco particle counter showed fairly close correlation between changes in the number of particles (over 5 mu) and in the number of bacteria in the air. Petri plates exposed near the patient showed a definite relationship between medical or nursing activities involving that particular patient and the number of bacteria deposited on the plate. Continuous disinfection of the air by air-conditioning - cum-ultraviolet ray equipment succeeded in reducing the average bacterial count by 50 per cent although the figures varied in different parts of the ward.

Air Conditioning↗
PubMed1996

Immunohistochemical localization of hepatic nitric oxide synthase in normal and transgenic sickle cell mice: the effect of hypoxia.

Nitric oxide (NO) generated from L-arginine and molecular oxygen by nitric oxide synthase (NOS) has been shown to influence hepatocellular function and pathology in response to ischemia and certain hepatotoxins. In the present study, we examined the liver of a transgenic line of sickle cell mice for hepatocellular injury and localization of two isoforms of NOS, the endothelial constitutively expressed isoform (EcNOS) and the inducible isoform (iNOS) by immunohistochemistry. Diffuse expression of EcNOS was observed in hepatocytes of control and sickle cell animals maintained under room air conditions. In contrast, iNOS was observed only in the sickle cell mice, well-localized to hepatocytes surrounding the central veins of the lobules. When normal mice were exposed to hypoxic conditions for 4 to 5 days, iNOS immunostaining appeared de novo in a patchy distribution throughout the liver lobules. In the sickle cell mice, hypoxia appeared to increase the subjective intensity of pericentral staining of iNOS. Liver histology was normal in the sickle cell mice maintained under room air conditions, but showed multifocal areas of necrosis when sickling was exacerbated by chronic hypoxic conditions. However, a pericentral zone of preserved architecture was present, corresponding to the region of iNOS staining. We postulate that pericentral induction of iNOS under ambient conditions occurs in transgenic sickle cell mice in response to particularly intense hypoxic conditions near the central veins of the liver. Increases in NO synthesis may occur in this region, which would serve to protect these cells from ischemic damage either directly or by maintaining blood flow. These findings could be relevant to liver pathophysiology in patients with sickle cell disease.

Anemia, Sickle Cell↗
PubMed2003

Attenuated thermoregulatory sweating and cutaneous vasodilation after 14-day bed rest in humans.

We investigated the effect of head-down bed rest (HDBR) for 14 days on thermoregulatory sweating and cutaneous vasodilation in humans. Fluid intake was ad libitum during HDBR. We induced whole body heating by increasing skin temperature for 1 h with a water-perfused blanket through which hot water (42 degrees C) was circulated. The experimental room was air-conditioned (27 degrees C, 30-40% relative humidity). We measured skin blood flow (chest and forearm), skin temperatures (chest, upper arm, forearm, thigh, and calf), and tympanic temperature. We also measured sweat rate by the ventilated capsule method in which the skin area for measurement was drained by dry air conditioned at 27 degrees C under similar skin temperatures in both trials. We calculated cutaneous vascular conductance (CVC) from the ratio of skin blood flow to mean blood pressure. From tympanic temperature-sweat rate and -CVC relationships, we assessed the threshold temperature and sensitivity as the slope response of variables to a given change in tympanic temperature. HDBR increased the threshold temperature for sweating by 0.31 degrees C at the chest and 0.32 degrees C at the forearm, whereas it reduced sensitivity by 40% at the chest and 31% at the forearm. HDBR increased the threshold temperature for cutaneous vasodilation, whereas it decreased sensitivity. HDBR reduced plasma volume by 11%, whereas it did not change plasma osmolarity. The increase in the threshold temperature for sweating correlated with that for cutaneous vasodilation. In conclusion, HDBR attenuated thermoregulatory sweating and cutaneous vasodilation by increasing the threshold temperature and decreasing sensitivity. HDBR increased the threshold temperature for sweating and cutaneous vasodilation by similar magnitudes, whereas it decreased their sensitivity by different magnitudes.

Adolescent↗
PubMed1989

[Microbiological measurement of air-borne bacteria at an office building].

Following a request of a cleaning firm microbiological measurings were carried out in (large building) office areas. Air was supplied through an air conditioner and all windows were locked and could not be opened. Office employees were on the opinion that illness had increased and felt endangered by colleagues' germs. To find out the reason of these complaints measurings were conducted in various rooms and floors also in the air conditioner. It must be stressed that in spite the continuous air conditioning, almost all doors were open to the corridors. This, declared one of the questioned employees had above all a communication expansion effect.

Air Conditioning↗
PubMed1984

Calculation of long jump performance by numerical integration of the equation of motion.

The aerial phase of the long jump is calculated by numerical integration of the equations of motion. Consideration is given to the effects on performance of the horizontal and vertical components of velocity at takeoff, aerodynamic drag, wind assistance and the vertical displacement of the center of mass which occurs during the course of the jump. For still air conditions it is shown that an analytical solution due to Lamb compares very favorably with the numerical solution, providing an excellent description of the trajectory. Calculations neglecting the effect of aerodynamic drag are shown to overestimate the jump distance of world-class athletes by from 9 to 11 cm under still air conditions.

Biomechanical Phenomena↗
PubMed2005

Correlations between growth parameters of spoilage micro-organisms and shelf-life of pork stored under air and modified atmosphere at -2, 4 and 10 degrees C.

The correlations of the growth parameters (the initial cell number (N(0)), maximum cell number (N(max)), maximum specific growth rate (mu(max)), lag-phase (lambda)) of typical spoilage micro-organisms (lactic acid bacteria (LAB), coliforms, pseudomonads, Brochothrix thermosphacta) growing on sliced pork to the sensory shelf-life and microbial shelf-life were investigated. The changes in sensory quality and proliferation of micro-organisms on pork shoulder were studied at different atmosphere conditions (air and 40%CO(2)/59%N(2)/1%O(2)) and temperatures (-2, 4 and 10 degrees C). Microbial counts were fitted to the modified-Gompertz equation to obtain the growth parameters of different micro-organisms. B. thermosphacta and coliforms were predominant bacteria associated with spoilage of pork under all temperatures and air conditions. However, pseudomonads could only dominate under regular atmosphere condition. Using multiple linear regression, high correlations were found between the lag-time (lambda) of LAB (0.9814, 0.9830), B. thermosphacta (0.9895, 0.9849), or the maximum specific growth rate (mu(max)) of coliforms (-0.9583, -0.9695) and the microbial shelf-life and sensory shelf-life, respectively. The mu(max) and lambda of micro-organisms correlated well with microbial and sensory shelf-life. The shelf-life of pork is mainly correlated with the growth parameters of mu(max) and lambda than by N(max).

Animals↗
PubMed1984

[Cancer mortality in smaller regions with different structures and conditions of air quality].

The study attempts a comparative evaluation of 5 Styrian regions as to their mortality rate of cancer in general as well as cancer of the respiratory system in particular. Regions were not established according to political or administrative districts; instead, communities from areas with homogeneous characteristics as to topography, climate, and air-quality were combined in regions. Among these 5 regions, 2 are industrial centers (region Voitsberg-Köflach with 31.000 inh. and Aichfeld-Murboden with 45.000 inh.), 2 have low to average air pollution (Ausseerland with 13.000 inh. and Deutschlandsberg with 13.000 inh.), 1 is a city with appr. 247.000 inh. (Graz). The disadvantage of the small number of samples was compensated for by observing each region over a period of 11 years. The results clearly demonstrate that the region Voitsberg-Köflach has a statistically significant high mortality rate both of cancer in general as well as of cancer of respiratory system in particular. The collected data provide ample ground for the assumption that environmental conditions are to a large degree responsible for the high mortality rate; this study will provide the basis for systematic investigations of its causes.

Adolescent↗
PubMed2003

Effect of ultraviolet germicidal lights installed in office ventilation systems on workers' health and wellbeing: double-blind multiple crossover trial.

BACKGROUND: Workers in modern office buildings frequently have unexplained work-related symptoms or combinations of symptoms. We assessed whether ultraviolet germicidal irradiation (UVGI) of drip pans and cooling coils within ventilation systems of office buildings would reduce microbial contamination, and thus occupants' work-related symptoms. METHODS: We undertook a double blind, multiple crossover trial of 771 participants. In office buildings in Montreal, Canada, UVGI was alternately off for 12 weeks, then turned on for 4 weeks. We did this three times with UVGI on and three times with it off, for 48 consecutive weeks. Primary outcomes of self-reported work-related symptoms, and secondary outcomes of endotoxin and viable microbial concentrations in air and on surfaces, and other environmental covariates were measured six times. FINDINGS: Operation of UVGI resulted in 99% (95% CI 67-100) reduction of microbial and endotoxin concentrations on irradiated surfaces within the ventilation systems. 771 participants appeared to remain masked, and reported no adverse effects. On the basis of within-person estimates, use of UVGI was associated with significantly fewer work-related symptoms overall (adjusted odds ratio 0.8 [95% CI 0.7-0.99]), as well as respiratory (0.6 [0.4-0.9]) and mucosal (0.7 [0.6-0.9]) symptoms than was non-use. Reduction of work-related mucosal symptoms was greatest among atopic workers (0.6 [0.5-0.8]), and never-smokers (0.7 [0.5-0.9]). With UVGI on, never-smokers also had large reduction of work-related respiratory (0.4 [0.2-0.9]), and musculoskeletal symptoms (0.5 [0.3-0.9]). INTERPRETATION: Installation of UGVI in most North American offices could resolve work-related symptoms in about 4 million employees, caused by microbial contamination of heating, ventilation, and air-conditioning systems. The cost of UVGI installation could in the long run prove cost-effective compared with the yearly losses from absence because of building-related illness.

Adult↗
PubMed1992

Five office workers inadvertently exposed to cypermethrin.

Five cases of poisoning by cypermethrin, a pyrethroid pesticide, are presented. The chemical was inadvertently introduced to the air-conditioning ducts and the patients inhaled it. Exposed patients experienced shortness of breath, nausea, headaches, and irritability. The exposure was compounded by repeated entry into the contaminated area and slow referral to a physician experienced in pesticide exposures.

Adult↗
PubMed2005

Numerical simulation of intranasal air flow and temperature after resection of the turbinates.

BACKGROUND: Radical surgical resection of the turbinates leads to a reduced intranasal air conditioning. The aim of this study was to determine the effect of turbinate resection on intranasal heating and airflow patterns using a numerical simulation. METHODS: A bilateral model of the human nose with resection of the turbinates on one side based on a CT-scan was reconstructed. A numerical simulation applying the computational fluid dynamics (CFD) solver Fluent 6.1.22 was performed displaying inspiratory intranasal air temperature and airflow patterns. RESULTS: Due to resection of the turbinates the airflow pattern is disturbed resulting in a spacious vortex throughout the entire nasal cavity. Hence, contact between air and surrounding nasal wall is less intense. Consequently, intranasal heating of the inspired air is relevantly reduced. CONCLUSIONS: Surgical resection of the turbinates leads to a disturbed intranasal air conditioning. The presented numerical simulation demonstrates the close relation between airflow patterns and heating.

Body Temperature↗
PubMed1997

Ventilation system, indoor air quality, and health outcomes in Parisian modern office workers.

A cross-sectional study was carried out to determine the effect on health of exposure to different types of ventilation, taking indoor environmental measurements (IEMs) of major contaminants and aeroallergens into account. Three buildings ventilated with heating, ventilating, and air conditioning (HVAC), fan coil units (FCUs), and natural ventilation were selected. One thousand one hundred forty-four workers answered health questionnaires. After adjusting for potential confounders, HVAC and FCU systems were related to a slightly higher risk of nonspecific symptoms (compared with natural ventilation), short-term throat irritation, work-related nasal discharge, nasal blockage on awakening, migraine, and usual coughing induced by cold air. Studying the potential effects of environmental contaminants and aeroallergens on health outcomes, taking the floor and type of ventilation into account, did not explain the observed excess of nonspecific symptoms.

Adult↗
PubMed1984

[Survey of Legionella in the Parisian environment. Practical implications].

A qualitative and quantitative survey of environmental Legionella in the Paris area was undertaken because of its epidemiological implications. Over a 2-year period, 322 water samples from the Paris area (unrelated to a legionnaires' disease outbreak) were examined for the presence of Legionella. No Legionella strain was isolated from the main water supplies of the municipality or from the distribution entry points of 36 buildings. Inside buildings, however, 84/190 (44.2%) tap water samples yielded one or several strains of Legionella (10(2) to 10(6) CFU/l). Contamination was significantly more frequent in hot tap water than in cold tap water. Legionella was isolated from 11 out of 14 air-conditioning systems investigated. Sixty-four of the 132 strains isolated were L. pneumophila serogroup 1. Other strains were L. pneumophila serogroups 2 to 6 (including a serogroup 4-5 variant), L. longbeachae serogroup 2 and 6 atypical Legionella.

Air Conditioning↗
PubMed1982

Sensitivity to heat and water loss at rest and during exercise in asthmatic patients.

We investigated the respiratory heat and water loss in 24 asthmatic patients who performed bicycle exercise while inspiring air conditioned to varying temperatures and water contents. Measurements of peak expiratory flow and forced expiratory volume in 1 s were made at rest, during and after exercise to determine changes in airways resistance. Respiratory heat and water loss were measured using rapid thermistors and a mass spectrometer to measure inspired and expired temperature and water vapour pressure. Exercise-induced asthma (EIA) was enhanced as the inspired water content of the air was reduced. However, there was a wide variation in sensitivity to the loss of heat and water between individual patients. This variability could not be accounted for by differences in body size. When patients inspired air conditioned to body temperature and fully saturated with water vapour, EIA was significantly reduced; however, half the patients still had an attack of asthma following exercise which had induced no significant loss of heat or water. It is suggested that the bronchoconstriction induced by water loss from the airways during exercise may be due to a change in osmolarity in the respiratory tract fluid.

Adolescent↗