[ASSESSMENT OF THE CO2 CONTENT OF THE MICROCLIMATE DURING SHORT PERIODS BY MEANS OF AN INTERFEROMETER--CONTRIBUTION TO METHODS FOR MICROCLIMATE ANALYSIS].
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Carbon Dioxide↗
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[Effect of dust and warm microclimate on the occurrence of chronic non-specific diseases of the respiratory system in workers of the gypsum factory Dolina Nida in Gacki. I. Warm microclimate and prevalence of dust at place of work].
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Body Temperature Regulation↗
Effects of potential damaging agents on the microclimate-pH in the rat jejunum.
This study was designed to determine the pH of the intestinal surface in the rat jejunum in an attempt to investigate the effect of potential damaging agents on the microclimate-pH. A significant pH gradient was observed between the mucosal surface and the bulk phase; however, the microclimate-pH usually ranged from 6.5 to 7.5, irrespective of the wide range in the bulk pH. When the bulk pH was either 7.3 or 4, the microclimate-pH was approximately 6.7, while the microclimate-pH was approximately 7.4 when the bulk pH was raised to 9. The distance of the pH gradient was found to be approximately 900-1300 microns. After treatment with ouabain (10 mM) or amiloride (8 mM), or replacement of Na+ with Li+, the microclimate-pH significantly increased compared with the control (buffer solution). Chlorpromazine (2 mM) and ouabain also significantly increased the microclimate-pH, but at the same time, chlorpromazine decreased the bulk pH so that a more marked pH gradient was observed. Both aspirin (10 mM) and acetazolamide (80 mg/kg, iv) significantly decreased the microclimate-pH under the condition of the acidic bulk phase pH. N-Acetyl-L-cysteine (5%) induced marked changes in microclimate-pH, the direction depending upon the bulk phase pH. Neither taurocholic acid (10 mM) nor glucose (10 mM) significantly changed the microclimate pH.
Acetazolamide↗
Effects of phenothiazine derivatives on the microclimate-pH in the rat jejunum.
The effects of several phenothiazine derivatives (PTDs) and quinidine (QD) on the jejunal microclimate-pH in rats were studied using a microelectrode. Chlorpromazine, thioridazine, chlorpromazine sulfoxide (CPZSO), trifluoperazine, prochlorperazine, and QD at concentrations of 1 mM increased this microclimate-pH by 0.15-0.3 pH units, while 1 mM diethazine and 1 mM promethazine had little effect on it. The increases in the microclimate-pH caused by PTDs and QD were concentration dependent and reversible. We studied the effects of PTDs on the fluidity of intestinal brush border membranes and on the release of proteins from the intestinal tissue to the lumen. The PTD-induced changes in microclimate-pH could not be explained by either of these nonspecific effects on the membranes. Then, the effects of PTDs on Na+,K+-ATPase activity and Mg2+-ATPase activity were studied using the jejunal homogenate. Each PTD inhibited Na+,K+-ATPase and Mg2+-ATPase activity to some extent. The inhibitory effects on Na+,K+-ATPase and Mg2+-ATPase activity were compared with the PTD-induced increases in the microclimate-pH. No good correlation was obtained between the IC50 values of PTDs for Na+,K+-ATPase activity and the concentrations required to increase the microclimate-pH by 0.1 pH unit, while IC50 values of PTDs for Mg2+-ATPase activity showed a relatively good correlation, except for that of CPZSO. These findings suggest that the effects of PTDs on the microclimate-pH were not nonspecific, although the increases in the microclimate-pH caused by PTDs cannot be fully explained by the inhibitory effects of these compounds on either Na+,K+-ATPase activity or Mg2+-ATPase activity alone.
Adenosine Triphosphatases↗
Effects of aging on the microclimate pH of the rat jejunum.
The acidic microclimate layer in the vicinity of the cell surface of mammalian jejunum is important for absorption of some nutrients, such as small peptides and folate. The present study was undertaken to investigate the effect of aging on the cell surface pH (microclimate pH) of the jejunum of rats. The microclimate pH was measured in vitro in superfused preparations using single-barreled pH-sensitive microelectrodes filled with a liquid ion exchanger. The thickness of the microclimate layer was estimated by reading the distance of microelectrode advancements. The existence of a microclimate pH in the jejunum was confirmed in the senescent rats, but the value of the microclimate pH was significantly higher in the senescent (24 mo) rats (6.52 +/- 0.02) than in the young-adult (6 mo) rats (6.09 +/- 0.01) (P < 0.01). Na+ removal from the perfusate or the addition of amiloride elevated the pH in the senescent rats as well as in the young-adult rats. The microclimate layer was slightly thinner in the senescent rats than in the young-adult rats. The acidity of the microclimate layer of intestinal surface is lower in senescent animals than in the young-adult ones. One of reasons for this is the thinner mucus layer in senescent animals.
Aging↗
pH-microclimate at the luminal surface of the intestinal mucosa of guinea pig and rat.
Segments of guinea pig jejunum, proximal and distal colon and of rat jejunum were superfused either in vivo or in vitro with different electrolyte solutions. The pH in the bulk phase solution and at the surface of the epithelium was measured with two different types of glass pH-microelectrodes, a pointed tip (Hinke-type) and a flat membrane electrode (Dubuisson-type); both types of electrodes gave the same results. The existence of a pH-microclimate at the surface of the mucosa was demonstrated under both in vivo and in vitro conditions. In vivo the pH-microclimate was stable and virtually independent of changes in the luminal bulk phase pH. When the bulk phase pH of the guinea pig colon was changed between pH 5 and pH 8.6, the mean pH in the microclimate was 7.08 +/- 0.15 (n = 163) in the proximal colon and 6.91 +/- 0.14 (n = 75) in the distal colon. In the guinea pig jejunum pH in the microclimate was 7.37 +/- 0.21 (n = 10) while the luminal pH was 7.27 +/- 0.10. Under in vitro conditions, the pH in the microclimate was more acidic (guinea pig jejunum delta pH 0.93, rat jejunum delta pH 0.40, guinea pig proximal colon delta pH 0.22). Addition of glucose (10 mM) or short-chain fatty acids (80-90 mM) to the luminal solution or replacement of sodium by lithium did not influence the pH in the microclimate significantly. Also the addition of acetazolamide, amiloride, SITS or sodium deoxycholate to the luminal solution, did not affect the pH in the microclimate in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Combined effects of fabric air permeability and moisture absorption on clothing microclimate and subjective sensation during intermittent exercise at 27 degrees C.
The present paper aimed at determining the combined effects of two different levels of air permeability and moisture absorption, in terms of clothing microclimate and subjective sensation, in resting and exercising subjects at an ambient temperature of 27 degrees C, a relative humidity of 50% and an air velocity of 0.14 m s-1. Three kinds of clothing ensemble were investigated: (1) polyester clothing with low moisture absorption and low air permeability (A), (2) polyester clothing with low moisture absorption and high air permeability (B), and (3) cotton clothing with high moisture absorption and high air permeability (C). The subjects exercised for 10 min on a cycle ergometer at an intensity of 30% maximal oxygen uptake and then had a 10 min rest. This sequence was repeated four times. The main findings are summarized as follows: (1) The clothing microclimate humidity in the back area was significantly higher in A than in B, and in C than in B. (2) The clothing microclimate temperature in the chest area was significantly higher in B than in A, and in B than in C. (3) The clothing microclimate temperature in the back area was significantly higher in C than in B. (4) The clothing surface temperature was significantly higher in C than in B. (5) Although the positive relationships between the microclimate humidity and forearm sweat rate was significantly confirmed in all three kinds of clothing, the microclimate humidity at chest for the same sweat rate was lower in C than in A and B. (6) Although the positive relationships between subjective sensation and forearm sweat rates were significantly confirmed in all three kinds of clothing, the subjective discomfort seemed to be reduced more effectively in C than in A and B for the same sweat rate. These results were discussed in terms of thermal physiology and combined effects of air permeability and moisture absorbency of the fabrics.
Absorption↗
Intestinal lumen and mucosal microclimate H+ and NH3 concentrations as factors in the etiology of experimental amebiasis.
Axenically cultivated Entamoeba histolytica, trophozoites, strains HM-1:IMSS and HM-38, were suspended in solutions of NaCl, 330 mOsm, of varying pH and ammonium concentrations. Short-term viability was inversely proportional to the ammonia concentration of the medium and was independent of the ammonium concentration and pH. The NH3-induced ameba killing was associated with a cellular alkalosis and cell swelling. While short-term trophozoite viability was unaffected by changes in the medium pH over the range 5.5-8.0, long-term viability was reduced by high pH, and of three pH values tested (6.27, 7.27, and 8.27), trophozoite growth was greatest at the lower value. Chemotaxis was observed in media over the pH range 5.5-8.0, and attenuated chemotaxis was observed in trophozoites in media containing NH3 (0.1 mM). The cecal content total ammonia concentration and pH and the in vivo mucosal microclimate pH were measured in young adult male rats, hamsters, and gerbils. Ceca of the three rodent species were also inoculated with HM-38 trophozoites and 7 days later the cecal contents were studied for signs of amebic infection. Infections were absent in the rat, the species with highest luminal total ammonia concentration and mucosal microclimate pH. All gerbils were infected. This species had the lowest mucosal microclimate pH. The hamster, with the intermediate microclimate pH, had a low infection rate (1 of 5). It is proposed that when ammonium diffuses from the large intestinal lumen into a more basic mucosal microclimate, it is converted to ammonia, and the combination of this ammonia and the high microclimate pH threatens Entamoeba trophozoite viability and reduces the probability of a given ameba penetrating the mucus blanket and invading the mucosal epithelium.
Amebiasis↗
The effects of two kinds of mask (with or without exhaust valve) on clothing microclimates inside the mask in participants wearing protective clothing for spraying pesticides.
AIM: The study aimed at discovering the effects of wearing two types of protective mask on the clothing microclimate (temperature, humidity) inside the mask, physiological parameters and subjective sensations. METHOD: Five healthy female students performed intermittent step exercise while wearing the protective clothing in a climate chamber at 28 degrees C and 60% relative humidity (RH). One mask was made of non-woven fabric and had no exhaust valve (mask A), and the other had an exhaust valve (mask B). RESULTS: (1) Clothing microclimate temperature inside the mask was significantly lower in mask B than in mask A. The final values were 35.5 +/- 0.3 degrees C in mask A and 34.6 +/- 0.8 degrees C in mask B. (2) Clothing microclimate humidity inside the mask was significantly lower in mask B than in mask A. The final values were 37.9 +/- 0.9 g/m3 in mask A and 35.7 +/- 2.0 g/m3 in mask B. (3) Cheek skin temperature inside the mask was kept significantly lower in mask B than in mask A. (4) Clothing microclimate humidity at trunk level increased more slowly with mask B than with mask A for four participants. (5) Rectal temperature increased more slowly with mask B than with mask A for three participants. (6) Tympanic temperature increased more slowly with mask B than with mask A for two out of four participants. DISCUSSION: We discussed these findings from the viewpoint that the dry and wet heat loss was accelerated through the nose under the influence of a reduced level of clothing microclimate inside mask B, having probably helped selective brain cooling by cooling more effectively the vein circulating blood through the nose.
Agricultural Workers' Diseases↗
The acidic microclimate in poly(lactide-co-glycolide) microspheres stabilizes camptothecins.
PURPOSE: The camptothecin (CPT) analogue, 10-hydroxycamptothecin (10-HCPT) has been shown previously to remain in its acid-stable (and active) lactone form when encapsulated in poly(lactide-co-glycolide) (PLGA) microspheres (1). The purpose of this study was to determine the principal mechanism(s) of 10-HCPT stabilization. METHODS: CPTs were encapsulated in PLGA 50:50 microspheres by standard solvent evaporation techniques. Microspheres were eroded in pH 7.4 buffer at 37 degrees C. The ratio of encapsulated lactone to carboxylate was determined by HPLC as a function of time, initial form of drug encapsulated, fraction of co-encapsulated Mg(OH)2, CPT lipophilicity, and drug loading. Two techniques were developed to assess the microclimate pH, including: i) measurement of H+ content of the dissolved microspheres in an 80:20 acetonitrile/H2O mixture and ii) confocal microscopy of an encapsulated pH-sensitive dye, fluorescein. RESULTS: The encapsulated carboxylate converted rapidly to the lactone after exposure to the release media, indicating the lactone is favored at equilibrium in the microspheres. Upon co-encapsulation of Mg(OH)2, the trend was reversed, i.e., the lactone rapidly converted to the carboxylate form. Measurement of -log(hydronium ion activity) (paH*) of dissolved microspheres with pH-electrode and pH mapping with fluorescein revealed the presence of an acidic microclimate. From the measurements of H+ and water contents of particles hydrated for 3 days, a microclimate pH was estimated to be in the neighborhood of 1.8. The co-encapsulation of Mg(OH)2 could both increase the paH* reading and neutralize pH in various regions of the microsphere interior. Varying the drug lipophilicity and loading revealed that the precipitation of the lactone could also stabilize CPT. CONCLUSIONS: PLGA microspheres prepared by the standard solvent evaporation techniques develop an acidic microclimate that stabilizes the lactone form of CPTs. This microclimate may be neutralized by co-encapsulating a base such as Mg(OH)2, as suggested by previous work with poly(ortho esters) (2).
Antineoplastic Agents↗
Effects of two kinds of underwear on thermophysiological responses and clothing microclimate during 30 min walking and 60 min recovery in the cold.
Thermophysiological responses and clothing microclimate under the influences of different underwear materials were compared during walking and recovery in the cold. Two kinds of underwear were used: two layers of cotton underwear with two-piece long-sleeved shirt and long-legged trousers (C), two layers of polypropylene underwear with two-piece long-sleeved shirt and long-legged trousers (P). In addition, the subject put on a two-piece ski suit of 100% polyester including 100% polyester padding. Seven adult females served as subjects in this study. The test was done in a climatic chamber at an ambient air temperature of 2 degrees C, a relative humidity of 65% and an air velocity of 0.14 m.s-1. The subject walked on a motor-driven treadmill with a 6 km/h speed for 30 min followed by 60 min recovery. Rectal temperature, skin temperatures, clothing microclimate (temperature, humidity), metabolic heat production and heart rate were measured. Furthermore, subjective ratings on thermal sensation, sweating/shivering sensation, clothing wettedness sensation and skin wettedness sensation for whole body were asked. The major findings are summarized as follows: 1) Mean skin temperature was not significantly different during walking, but it was significantly higher in P than in C during the recovery. 2) The absolute humidity of innermost layer and outermost layer were not significantly different during walking, but it was significantly higher in P than in C during the recovery. 3) Clothing microclimate temperature of innermost was not significantly different during the first half of walking, but it was significantly higher in C than in P during the second half of walking and significantly lower in C than in P during the recovery. Clothing microclimate temperature of outermost was not significantly different during walking, but it was significantly higher in P than in C during the recovery. 4) Metabolic heat production for the last 10 min during recovery tended to be higher in P. 5) The degree of skin wettedness sensation and clothing wettedness sensation for whole body was significantly higher in P during walking and recovery. Thus, it was concluded that two kinds of underwear with different properties to moisture could influence, not only clothing microclimate, but also physiological parameters like skin temperatures and metabolic heat production in the cold differently.
Adult↗
Factors affecting the microclimate pH in rat jejunum.
1. Single-barrelled pH-sensitive microelectrodes filled with liquid ion exchanger were used to study the layer of microclimate pH in the vicinity of the surface of rat jejunum in vitro. 2. During perfusion with a Na+-containing solution of pH 7.30, a layer having a pH gradient ranging from 7.30 (pH of the luminal bulk phase) to 6.05 +/- 0.03 (pH of the deepest region) was detected in eighteen different animals. The thickness of the layer was estimated to be 600-700 microns. No regional difference was seen along the height of the villus. 3. The addition of D-glucose to the perfusion solution significantly augmented the acidity of the deepest region without changing the thickness of the layer. On the other hand, the elimination of Na+ from the perfusion solution caused a significant reduction of the pH gradient. The lowest pH changed from a control value of 6.18 +/- 0.15 (n = 13 measurements from three animals) to 6.46 +/- 0.06 (n = 13). The gradient was sensitive to amiloride in the presence of Na+, K+, Ca2+ and Cl- had no significant effect on the microclimate pH. 4. Depletion of the surface mucus by treatment with dithiothreitol significantly raised the pH of the deepest region. 5. Glycylglycine and L-carnosine were found to reduce the microclimate pH gradient significantly, while glycine did not. 6. These results indicate that H+ secretion by the Na+-H+ antiport and the formation of mucus layer are important factors for maintaining the microclimate pH layer, and that H+-coupled co-transport, such as H+-dipeptide co-transport, causes a significant diminution of the microclimate pH gradient.
Amiloride↗
Mechanism of intestinal fatty acid uptake in the rat: the role of an acidic microclimate.
1. Micellar solubilization of lipolytic products is an important step in lipid absorption. However, micelles are not absorbed intact; dissociation of lipolytic products from bile salt micelles must occur. The dissociation of micelles has been postulated to occur in an acidic microclimate. 2. The effect of an acidic microclimate on the uptake of micellar fatty acid was examined in the rat intestine. We reported that the presence of a lower pH microclimate is associated with a higher fatty acid uptake, suggesting that a lower pH enhances fatty acid uptakes from the micelles. 3. Fatty acid uptake from solutions containing a constant amount of bile salt (10 mM) and varying amounts of fatty acid (3.3-26.4 mM) revealed a saturation phenomenon which reflects the fatty acid carrying capacity of a 10 mM-taurocholate solution. 4. There was a linear relationship between fatty acid uptake and fatty acid concentration when the micellar solutions contained a constant ratio of fatty acid and taurocholate (1.32). 5. Our results indicate that the fatty acid carrying capacity of the micelle and the number of micelles in the solution are both important determinants for the amount of fatty acids delivered to the microclimate. The amount of fatty acids derived from the dissociation of micelles within the microclimate determines fatty acid uptake by the intestine.
Animals↗
Epidermal growth factor as a regulatory hormone maintaining a low pH microclimate in the rat small intestine.
This study was designed to determine the effect of epidermal growth factor (EGF) in the lumen on the pH of the intestinal surface in the rat jejunum, which is referred to as "microclimate-pH". In the control experiment, a significant pH gradient was observed between the mucosal surface (approximately pH 6.8) and the bulk phase (approximately pH 7.3). The microclimate-pH was decreased by 0.2-0.6 pH units after addition of higher concentrations of EGF (3-100 nM) to the lumen. The microclimate-pH thus decreased recovers to the control value by replacing EGF with TES buffer, suggesting that the EGF effect is reversible. Considering that the Na+-H+ exchanger exists on the luminal membrane of the intestinal cells, the decrease in the microclimate-pH which was induced by EGF added to the luminal side may be due to the activation of Na+-H+ exchanger.
Animals↗
A Comparison of Skin Temperatures and Clothing Microclimate During Moderate Intermittent Exercise in the Cold Between One and Two Layers of Cotton and Polypropylene Underwear.
The purpose of this study was to compare the effects of 2 kinds of underwear made from hydrophobic and hydrophilic fabrics on the mean skin temperatures and clothing microclimate (temperature, humidity) in participants performing intermittent exercise in cold environmental conditions. One or 2 layers of cotton underwear (C1, C2) with a 2-piece long-sleeved shirt and long-legged trousers, and 1 or 2 layers of polypropylene underwear (P1, P2) with a 2-piece long-sleeved shirt and long-legged trousers were used as experimental underwear. In addition, the participants wore a 2-piece ski suit as 100% polyester clothing including 100% polyester padding. Ten young adult females volunteered as participants. The experiments were performed in a climatic chamber at an ambient temperature (Ta) of 0°C and an air velocity of 0.26 m s-1. The major findings are summarized as follows: (a) Although the clothing microclimate humidity was not different within the ski suit of outer clothing between C1 and P1, it was significantly higher in P2 than in C2; (b) Clothing microclimate temperature inside the ski suit did not differ between C1 and P1, whereas it was significantly higher in P2 than in C2; (c) The thermal gradient between innermost and outermost of clothing microclimate at back level did not show any difference between C1 and P1, but it was significantly higher in C2 than in P2. These results are discussed in terms of thermal physiology and clothing sciences.
clothing microclimate↗
Physiological reaction to work in cold microclimate.
OBJECTIVES: In Poland, occupational exposure to cold microclimate is quite common (5.1 workers/1000 occupationally active people). Reports on health effects of this exposure are rather scarce. The aim of the study was to evaluate the physiological reaction in workers occupationally exposed to cold microclimate. MATERIALS AND METHODS: Examinations were performed in a group of 102 workers (41 women and 61 men) employed at cold storage units. The mean age in the group was 39.1 +/- 9.9 years and the duration of employment under conditions of cold environment was over 12 years. The study population was divided into four groups, according to microclimate conditions (group I, ambient temperature -26 degrees C; group II, 10-14 degrees C; group III, 18-20 degrees C, control group; and group IV, 0-10 degress C). The workers underwent the following procedures: general medical examinations, cold pressor test, ambulatory blood pressure monitoring, and heart rate variability (HRV) analysis (time- and frequency-domain parameters). RESULTS: The results were adjusted for confounding factors (age, smoking and drinking habits). The analysis of HRV parameters did not reveal any significant differences between the study groups. However, systolic and diastolic blood pressure (BP) in the daytime and at night was significantly higher in group IV compared to group II. Mean heart rate (HR) in the daytime and at night and the BP and HR day/night ratio did not differ between the groups. The analysis of BP by gender revealed that in women, systolic BP during the day and at night was significantly higher in group IV than in group II. In the group of workers with hypertension (18 men and 5 women), men reacted to the cold pressor test either by increased or decreased BP while all the women reacted by the increased BP. CONCLUSIONS: Our findings indicated that in workers exposed to cold microclimate, the physiological reaction was dependent on gender and ambient temperature. Women seemed to be more sensitive to cold stress than men. However, this finding must be further investigated.
Adult↗
[The results and prospects of research on the hygiene of the industrial microclimate].
The main directions in the research and study of industrial microclimate are represented in the article. Evaluation of the microclimate based on thermophysiology, studies of correlation between the environmental temperature and the human functional status helped to establish the normal parameters, measures of the overheating and the overcooling prophylaxis. New data about the immediate and late effect of single microclimate parameters on the human functional status necessitate the creation of new methodic approaches to the evaluation and control of microclimate conditions.
Animals↗
Potassium microclimate at the mucosal surface of the proximal and the distal colon of guinea pig.
K+ concentrations were measured with K+ sensitive liquid ion exchanger microelectrodes in situ and in vitro in the mucus layer at the luminal cell surface of the proximal and the distal colon in guinea pig. In a first series of experiments K+ concentrations were increased in the luminal solution from 0 to 70 mmol X l-1; the serosal K+ concentrations were kept in vitro at 5.4 mmol X l-1. In the proximal colon mean K+ concentration in the microclimate was in vitro 7.9 +/- 3.5 mmol X l-1, and independent from mucosal concentrations. In the distal colon in vitro, and in situ in the proximal as well as in the distal colon, K+ concentrations in the microclimate were increased slightly when K+ concentrations were elevated in the luminal solution up to 70 mmol X l-1. In a second series of in vitro studies K+ concentrations were also altered in the serosal fluid. In the proximal and in the distal colon K+ concentrations increased linearly with elevated K+ concentrations in the serosal solutions. A temporarily interrupted mucosal blood flow resulted in a significant increase in the K+ concentration in the microclimate. A paracellular shunt pathway and a high preepithelial diffusion barrier for K+ would explain the observed K+ concentrations in the microclimate at the luminal cell surface.
Animals↗