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PubMed1992

Study of lipid changes in freeze-dried fish during storage. I. The interaction of relative humidity and tissue lipids.

Several studies on lipid stability of freeze-dried fish pointed out the relationship between relative humidity (RH) and autoxidation of highly unsaturated fatty acids. The present study shows the changes of tissue lipids in two different fish, freeze-dried and stored under various RH conditions. Fillets of Scomber scomber L and Sardina pilchardus sardina were freeze-dried and stored for 1, 3, 6 and 9 months. periodically, the sample of both fish were analyzed to evaluate the autoxidation of lipids. The results show that the autoxidation of lipids is quicker during 1st-3rd month of storage, while in a high humidity environment the tissue lipids change slower. According to these results both time of storage and relative humidity must be controlled to maintain the nutritive value of freeze-dried fish.

Animals↗

PubMed1992

Heat stress in protective clothing: validation of a computer model and the heat-humidity index (HHI).

Ability to work while wearing protective clothing is often limited by rising body temperature. Peterson analyzed the combined effects of heat, humidity and workload using the Texas Model of Thermoregulation and suggested that environmental heat load imposed on a person wearing heavy, semipermeable clothing could be predicted using the Heat-Humidity Index (HHI = 0.5 Tdb + 0.5 Twb), where Tdb = dry bulb temperature and Twb = wet bulb temperature. Our study was designed to: 1) test the validity of this computer model; and 2) evaluate the applicability of the HHI to heavily clothed subjects working in a variety of thermal environments. Nine men wearing chemical defense clothing were each studied under eight conditions over the range Tdb = 20 - 40 degrees C, Tbg = Tdb + 5 degrees C, relative humidity = 9-75%, and oxygen uptake = 14-27 ml.kg-1 x min-1. Variables analyzed included tolerance time (TT), rectal temperature (Tre), skin temperature, heart rate (HR), weight loss, sweat rate, evaporation rate, and evaporative efficiency. Experiments were designed to last 30-180 min, and continued until Tre = 39 degrees C except when subjective tolerance limits occurred first (12 of 72 experiments). The observed time to reach Tre = 39 degrees C bracketed the predicted time in the more severe conditions, but the model seriously underestimated heat storage in the milder conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗

PubMed2004

Bacterial growth characteristics in craniocerebral gunshot wound of cat in a hot and humid environment.

OBJECTIVE: To investigate the growth behavior of characteristics in craniocerebral gunshot wound of cats in a hot and humid environment. METHODS: Twenty-three cross-bred cats were randomly divided into 4 groups: group A, the gunshot wound control group at normal temperature, in which tissue sampling was performed immediately after the wounding; group B, another gunshot wound control group at normal temperature, in which the samples were taken 6 h after the wounding; group C, the gunshot wound group subjected to a hot and humid environment, in which the tissue samples were obtained 6 h after the wounding; group D, the control group without undergoing the wound. The tissues from the wound tract and the surrounding tissues were sampled for bacterial culture and counting. RESULTS: The bacterial counts of the tissues from the wound tract, the tissues within 5 mm and within 5-10 mm from wound tract varied insignificantly between groups A, B and C (P>0.05). In each group, the bacterial counts declined in the tissues as the distance of the sampling sites from the wound tract increased (P<0.01). The bacterial counts of the tissues from the wound tract and within 5 mm from the wound tract in group A, B and C were significantly different from those in group D (P<0.01). CONCLUSION: Hot and humid environment does not significantly affect the bacterial growth in the craniocerebral gunshot wound within the first 6 h, which is a safe period against rapid bacterial growth and suitable for debridement.

Animals↗

PubMed1992

Impact of tropical conditions on thin layer chromatography in analytical toxicology: high temperatures and moderate humidities.

The impact of high temperatures (24 to 39 degrees C) and low to moderately high humidities (20 to 70%) on the applicability of TLC systems for drug identification was studied during a 6 month climatologic cycle in Burkina Faso (West Africa). In general, the Rf values as observed on the plates were found to be substantially affected as compared with values obtained at temperate climates. Some TLC systems were more affected than others and the largest deviations of up to 30 Rf units were at low humidities. Tropical conditions also had a negative effect on the reproducibility of Rf values. However, when an Rf-correction procedure was applied, using reference mixtures of known drugs on each plate, accuracy as well as reproducibility of the resulting Rfc values were drastically improved and data thus corrected were found to be compatible with existing TLC data bases developed under moderate climatological conditions. The impact of high to extremely high humidities (70 to 100%) remains to be investigated.

Burkina Faso↗

PubMed2004

[Changes of cat cerebral microcirculation and blood-brain barrier in early stage of craniocerebral gunshot wound in the hot and humid environment].

OBJECTIVE: To study the changes of cat cerebral microcirculation in early stage after craniocerebral gunshot wound in the hot and humid environment to provide laboratory evidence for clinical treatment of such wound. METHODS: Craniocerebral gunshot wound was induced in 24 cats according to the method described by Carey with modifications, and the cats were placed in a cabin with environmental temperature and humidity of 25 degrees Celsius and 50% (group A), and 35 degrees Celsius and 85% (group B), respectively, to observe the changes in all the indices of cerebral microcirculation. RESULTS: All the cats survived and notable changes occurred in the morphology and permeability of cerebral microvascular along with obvious pathological changes in the brain tissue, and the vital signs, hemorheology and blood-brain barrier were significantly different between groups A and B. CONCLUSION: Hot and humid environment induces obvious changes in cat cerebral microcirculation and blood-brain barrier function in the early stages after craniocerebral gunshot wound.

Animals↗

PubMed2004

[Hemorheological changes in hot and humid environment].

OBJECTIVE: To observe the changes in hemorheology of human under hot and humid environment. METHODS: Ninety soldiers serving in the Nansha Islands were divided into veteran group, recruit group and urapidil-treated recruit group, all of whom were required to complete 3 000-meter running exercise in 20 min in hot and humid environment. Their hemorheology were examined before and after the exercise. RESULTS: There were significant difference in the hemorheology between the 3 groups (P<0.05) both before and after the exercise, and the changes were most obvious in the veteran group followed by the new recruit group and urapidil-treated recruit group. No significant differences in the plasma indexes were detected between the 3 groups. CONCLUSIONS: Hot and humid environment causes obvious changes in the hemorheology, for which veterans and recruits have different tolerances and adaptabilities. Uradipil may help lower the magnitude of the the hemorheological changes after exercise by reducing body metabolism.

Adult↗

PubMedDate not supplied

Effect of humidity on the disintegrant property of alpha-cellulose.

A study has been carried out to investigate the effect of humidity on the disintegrant property of alpha-cellulose in paracetamol tablets. The disintegrant alpha-cellulose or maize starch (for comparative studies) was incorporated intragranularly or extragranularly. The tablets were prepared by a wet granulation technique and then exposed to relative humidities (RH) 1%, 78% and 100% at an ambient temperature of 28 to 30 degrees C for various time intervals up to 2 weeks. They were evaluated for disintegration time, hardness and moisture uptake. Tablets stored under RH% and 78% disintegrated within 15 minutes while those containing alpha-cellulose stored at RH 100% for a period > or = 24 h failed to disintegrate within 60 minutes. The time taken for this conversion from disintegrating to non-disintegrating tablets varied with disintegrant concentrations and its mode of incorporation. Tablets containing maize starch did not display this moisture effect. The observation is thought to relate to the gelling of the alpha-cellulose particles upon moisture sorption. Thus, high relative humidities impair the disintegrant property of alpha-cellulose, which underlines the need to prevent such tablets from moisture.

Acetaminophen↗

PubMed2005

[Changes of brain p38 MAPK in rabbits with craniocerebral gunshot injury in hot and humid environment].

OBJECTIVE: To study the activation of p38 mitogen-activated protein kinase (MAPK) in the brain of rabbits after craniocerebral gunshot injury in a hot and humid environment (HHE) and explore its possible mechanism. METHODS: Craniocerebral gunshot injury model was established in 30 New Zealand white rabbits, which were subsequently exposed to environment of normal temperature (at 22.0% +/- 0.5 degrees C; with relative humidity of 50%) or HHE at 39.0 +/- 0.5 degrees C; with relative humidity of 80%-85% for 10 min, 30 min, 1 h, 1.5 h, and 2 h groups, respectively, with 5 rabbits in each group. p38 MAPK activity in the brain tissues of the rabbits following the injury and environmental exposure were detected by Western blotting and analyzed semi-quantitatively by Bio-Profil gel image analysis system. RESULTS: p38 MAPK activity in the cortex and hypothalamus was significantly elevated following gunshot injury and HHE exposure, reaching the peak level at 1 h of HHE exposure and then decreased. p38 MAPK activity was significantly higher in the hypothalamus than in the cortex. CONCLUSION: p38 MAPK activity increases in the early stage following craniocerebral gunshot injury and HHE exposure in rabbits, the mechanism of which might involve the secondary brain insult.

Animals↗

PubMed2005

[Kinetic study on the degradation of penicillin potassium at different temperature and relative humidity].

OBJECTIVE: To perform a kinetic analysis and formulation of the degradation of penicillin potassium in the solid phase at different temperature and relative humidity. METHODS: Penicillin potassium was incubated in a temperature-and-humidity-controlled oven at different temperature and relative humidity, and was determined by HPLC at suitable time intervals during the incubation. RESULTS: The reaction rate was expressed as -dc/dt=k(c0-c+B), where c is the residual concentration, k degradation rate constant, c0 original concentration and B a constant related to original concentration of degradant. Degradation curves were fitted with c=c0-Bexp (kt)+B. The k was expressed as k=Aexp(-Ea/RT)exp(mHr), where active energy E. is 77.26 kJ/mol and constant m 0.1159. CONCLUSION: The degradation of penicillin potassium could be expressed with c=c0-Bexp [Aexp (-Ea/RT)exp (mHr)t]+B.

Drug Stability↗

PubMed1991

[Disturbances in the process of hatching of larvae Argas (A) reflexus (Fabr.) (Acari: Ixodida: Argasidae) exposed to various thermal and humidity conditions].

The most cases of abnormal hatch larvae (40.2%) of A. reflexus were in relative humidity 90% and temperature 25 degrees C; the least (0-2.8%)--at the low relative humidity levels (10 and 30%) in all examined temperatures of experiments. The rise of relative humidity caused the greater number of the disturbances of hatch larvae. The most often +non-separation of integument eggs from body of larvae was observed, what made impossible normal formation of legs and made difficult locomotive faculty.

Animals↗

PubMed1976

Effect of temperature and relative humidity on variola virus in crusts.

The viability of variola virus in crusts under different conditions of temperature and relative humidity was studied for 16 weeks. At the ambient temperature of 25.8-26.4 degrees C and 85-90% relative humidity, the virus survived only 8 weeks but at lower temperatures and relative humidities the survival time was considerably prolonged.

Humans↗

PubMed1990

[Characteristics of the relative humidity and temperature in the inspiratory part of the Dräger circle system and their influence on the function of the ciliary epithelium].

Changes in relative humidity and temperature of the anaesthetic gases were measured in the inspiratory limb of the Dräger circle system next to the carbon dioxide absorber in 29 patients requiring ENT surgery under general anaesthesia. Immediately following intubation and prior to extubation, nasal and tracheal cytologic samples were taken with a brush technique and ciliary beat frequency was determined. At a fresh gas flow of 6 l/min, relative humidity increased from 57.6 +/- 1.5 to 62.5 +/- 1.8% (p less than 0.05) after 110 minutes. Temperature increased continuously from 21.96 +/- 0.97 degrees C to 23.83 +/- 0.48 degrees C after 200 minutes. The number of vital ciliated cells in the tracheal samples decreased from 24.4% following induction of anaesthesia to 6% at the end of anaesthesia (p less than 0.05), and from 35.7% to 26.8% (p less than 0.05) in the nasal samples. Ciliary beat frequency remained unchanged at the end of anaesthesia as compared to control in tracheal as well as in nasal samples. It is concluded that the output of relative humidity and temperature in the circle system is not sufficient to prevent broncho-epithelial damage. Ciliary beat automaticity appears to behave according to an all or nothing principle.

Adult↗

PubMed1989

[Drug interactions during storage of mixtures of the antacid group. III. Effect of relative humidity on structural changes in mixtures aluminum hydroxide gel and magnesium hydroxide in the solid phase].

Mixtures of A1(OH)3 gel and Mg(OH)2 were stored for 14 months in the solid phase in chambers with relative air humidity of 35%, 55%, 76% and 92%. IR spectra of the stored mixtures were measured. In mixtures stored at relative air humidity of 35% there were found no changes in IR spectra, while the mixtures stored at relative air humidity of 92% proved to exhibit IR spectra characteristic for hydrotalcite.

Aluminum Hydroxide↗

PubMed1988

Humid air increases airway resistance in asthmatic subjects.

Eight persons with asthma were exposed to seven air conditions varying in temperature (37 degrees C to 49 degrees C [98.6 degrees F to 120.2 degrees F]) and water content (44 mg H2O per liter to 79 mg H2Oper liter) . Normocapnic hyperventilation for three minutes at 40% maximal voluntary ventilation was carried out for each condition. A constant-volume body plethysmograph measured the functional residual capacity and specific airway conductance (SGaw), followed by two forced expiratory manuevers. Measurements were taken before and 1, 5, 10, and 20 minutes after each challenge. Air conditions with 100% relative humidity caused a fall in the SGaw that was maximal in 1 minute. Air conditions at 100% relative humidity caused a greater fall in both the forced expiratory volume in 1 second (FEV1) (P<.05) and the SGaw (P<.005) than did conditions of the same temperature but less water content. At 44 degrees C and 100% relative humidity, the mean percent change in FEV1 and SGaw was -2% and -40%, respectively, at 1 minute after challenge. Of the conditions examined, the optimal temperature was 44 degrees C, and we speculate that the optimal water content is less than 44 mg H2O per liter. Inhaled water concentrations exceeding 44 mg H2O per liter should probably not be used in patients with asthma.

Adult↗

PubMed1977

Studies on water vapor pressure gradient from external air through clothing to the skin in relation to external humidity and clothing conditions.

Using a hygrometric capsule method developed by the authors, water vapor pressure was measured at each layer of clothing as well as at the skin surface on a human subject under actual wearing conditions. The pattern of vapor pressure gradient from the skin surface through clothing to the external air was examined in relation to the ambient vapor pressure and ths sort of textiles worn. The following findings were obtained. 1) Water vapor pressure gradient was greater between coat and external air than that between coat and underwear. The gradient became steeper again between underwear and the skin. 2) Under given clothing conditions, vapor pressure at each layer of clothing as well as at the skin varied according to the ambient humidity. However, the pattern of vapor pressure gradient from the skin through clothing to the external air was not greatly influenced by the external humidity. 3) The pattern of vapor pressure gradient from the skin through clothing to the external air was not greatly influenced by the external humidity. 3) The pattern of vapor pressure gradient through the clothing as a whole differed according to the kinds of textiles used for coat and underwear.

Adult↗

PubMed1977

[Effect of the temperature-humidity regime during broiler raising on serum proteins and amino acids].

The study on the effect of the temperature and moisture regime on the serum proteins and amino acids in broiler chickens has revealed that under the conditions of relatively lower temperatures and higher relative moisture levels the total protein, the albumin, and the gamma-globulin fraction show higher contents. Noticeable are also some changes in the content of the bound amino acids (tyrosin, alfa- and beta-alanine, aspartic acid, and glycin) in the blood sera that are likewise depending on the temperature and moisture regime. The total amount of amino acids and the free forms of arginine and lysine are at higher levels in the broilers raised prior to the experiment at 32 degrees C and relative air humidity 70--75 per cent. With the remaining free and bound amino acids in the blood serum there are no differences in broilers raised at various temperature and moisture regimes. The body weight of broilers raised prior to the experiment at 32 degrees C and relative air humidity 70--75 per cent is higher, while the consumption of forage for kilogram weight gain is lower as compared to that with birds raised at higher temperature and lower relative humidity (35--45 and 50 per cent).

Amino Acids↗

PubMed1984

Effect of relative humidity and ageing on drug release. Part 2: Experimental phenytoin sodium capsules.

In this study the effect of ageing and relative humidity on the release rate of phenytoin sodium was investigated for an experimental capsule formulation. Phenytoin sodium capsules containing lactose as the excipient were kept in 75 and 95% relative humidities, for 8 weeks, and the variances in the in vitro dissolution profiles of the active substance were observed. In vitro dissolution results were also evaluated kinetically. In general, it was observed that there was a decrease in the in vitro dissolution rate after storage at 95% relative humidity.

Capsules↗

PubMed1983

The microclimate chamber: the effect of continuous topical administration of 96% oxygen and 75% relative humidity on the healing rate of experimental deep burns.

The healing rate of small experimental burns continuously treated topically with 96% O2 and 75% relative humidity was followed for 25 days. Serial image photographic magnifications (tenfold throughout) of the wounds enabled precise measurements of their size by means of a polar planimeter. Healing rate was expressed as decreased percentile of wound size on a given day compared to the initial area. The mean percentages of healing +/- SEM of the humidified O2 treated wounds on postburn days 6, 11, and 16 were 31.25 +/- 6.15, 82.09 +/- 3.52, and 98.29 +/- 1.46, respectively, and those for the control wounds were 7.08 +/- 2.20, 47.68 +/- 3.39, and 84.41 +/- 1.38, respectively. Analysis of variance revealed highly significant differences in the healing rate between O2-humidity-treated and control wounds (p less than 0.005). The results indicate that topical treatment with 96% O2 and 75% relative humidity improved healing of experimental burns in guinea pigs.

Administration, Topical↗