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PubMedDate not supplied

Bair hugger forced-air warming maintains normothermia more effectively than thermo-lite insulation.

STUDY OBJECTIVE: To compare the ability of forced-air warming and reflective insulation to maintain intraoperative normothermia. DESIGN: Prospective, randomized clinical trial. SETTING: Operating rooms of a general hospital. PATIENTS: 20 ASA physical status I and II patients undergoing elective total hip arthroplasty. INTERVENTIONS: Patients were randomly assigned to be warmed intraoperatively using forced-air or reflective insulation. Inspired gases were conditioned using a heat-and-moisture exchanger in both groups, and infused intravenous fluids were warmed to 37 degrees C. MEASUREMENTS AND MAIN RESULTS: Distal esophageal (core) temperatures decreased approximately 0.5 degrees C in both groups during the first 45 minutes of anesthesia. Subsequently, core temperatures increased slightly in the patients given forced-air warming. In contrast, core temperatures continued to decrease in patients covered with reflective insulation. After 135 minutes of anesthesia, core temperatures were 36.4 +/- 0.6 degrees C (mean +/- SD) in the forced-air group but only 35.4 +/- 0.6 degrees C in the insulated group (p < 0.01, unpaired t-test). These data indicate that forced-air warming is superior to reflective insulation. CONCLUSION: Reflective insulation was unable to maintain intraoperative normothermia during total hip arthroplasty. Active warming, such as that provided by forced air, was required to prevent hypothermia.

Aged↗

PubMed2005

Thermal insulation and SIDS-an investigation of selected 'Eastern' and 'Western' infant bedding combinations.

BACKGROUND: Differences in the incidence of SIDS between 'Western' and 'Eastern' countries has been attributed to cultural practices, which may affect the infants care and thermal environment. AIM: The purpose of this work was to estimate for selected 'commonly' used bedding, sleep positions and practices in Japan, Korea and New Zealand, the intrinsic 'dry' thermal resistance of bedding. Insulation levels are also discussed in the context of published information about the thermal environment in which the bedding is likely to be used. METHOD: Selected Japanese, Korean and New Zealand bedding was loosely tucked over an infant manikin in the lateral, prone and supine sleep positions. Thickness in use was measured, and intrinsic 'dry' thermal resistance estimated using the Wilson Laing model which accommodates the effect on insulation of the three-dimensional arrangement of bedding combinations during use. RESULTS AND DISCUSSION: Thickness of under- and upper-bedding varied among countries with thickness and estimated 'dry' thermal resistance of the upper-bedding affected by the type/combination of bedding and the infants sleep position. Insulation levels are discussed in relation to environmental conditions within and among countries and between seasons. Further information on thermal environments, bedding combinations used and care practices within both Asian and Western countries is needed. CONCLUSIONS: 'Eastern' infants appear likely to be generally covered in bedding combinations of greater insulation than those used to cover 'Western' infants in comparable seasons. Differences existed between insulation of the Japanese and Korean bedding combinations investigated. Lower rates of SIDS apparent in 'Asian' populations do not appear attributable to use of lower levels of bedding insulation only.

Bedding and Linens↗

PubMed1983

Passive transfer of insulitis and lymphopenia in the BB rat.

The BB rat spontaneously develops insulitis followed by impaired glucose tolerance (IGT) or an insulin-dependent diabetic (IDDM) syndrome. Passive transfer of insulitis from newly detected diabetic BB rats to nude mice has been achieved by intraperitoneal or intravenous injection(s) of blood and spleen lymphocytes. After a single injection of cells, 37% of the mice (n = 72) showed insulitis with a mean intensity of 1.9 +/- 0.3 (on a scale of 0 to 3). After three successive injections, 58% of the recipient mice (n = 12) showed insulitis with a mean intensity of 2.5 +/- 0.3. Only one of the control mice (n = 45) demonstrated mild insulitis. The small number of affected islets (13% after a single injection, 17% after three injections) probably explains the absence of random or post IP glucose hyperglycemia in the recipient mice. During this study the yield of lymphocytes in diabetic BB rats was found to be consistently lower than in control normal Wistar rats. This lymphopenia was found not only in the blood and the spleen but also in the thymus and the lymph nodes. Peripheral blood lymphopenia antedated glucoregulatory disturbances. All rats showing either insulitis alone or with IGT or IDDM were lymphopenic. None with normal lymphocyte counts developed any abnormality. Diabetics showed a marked decrease in the proportions of T+ lymphocytes in all tissues whereas the proportion of B(Ia+) lymphocytes was normal in blood, spleen, and thymus but increased in lymph nodes. However, in absolute terms both T+ and Ia+ lymphocytes were decreased. The subset decreased by the greatest proportion in all tissues, except in the thymus was the one that includes helper T lymphocytes. This lymphopenia could be related to the presence of circulating antilymphocyte antibodies. These results strongly support a role for altered immunity in the etiology of the syndrome. If the observed anomalies of lymphocyte numbers and subsets are responsible, then a novel mechanism different from most other "autoimmune" disorders must be implicated.

Animals↗

PubMed1998

Polycomb and trithorax group proteins mediate the function of a chromatin insulator.

Chromatin boundaries or insulator elements affect the interaction between enhancers and promoters. The gypsy insulator contains two proteins, Su(Hw) and Mod(mdg4). Both proteins colocalize on several hundred sites on polytene chromosomes and are distributed in a punctated pattern in the nuclear matrix. Mutations in mod(mdg4) have properties characteristic of a trxG gene. In addition, mutations in trxG genes enhance insulator effects on adjacent enhancers, whereas mutations in Pc have the opposite result. These alterations correlate with changes in the pattern of nuclear localization of insulator components. The results suggest a model in which PcG and TrxG proteins regulate insulator function by establishing higher order domains of chromatin organization required for the assembly of functional insulators at the nuclear matrix.

Animals↗

PubMed1997

Effect of experimental infection with Trypanosoma congolense and scrotal insulation on Leydig cell steroidogenesis in the ram.

Testicular steroid content and Leydig cell steroidogenesis in vitro were investigated in rams on Days 28 and 58 after Trypanosoma congolense infection and were compared with those of rams in which testicular temperature had been raised artificially by insulation of the scrotum for 58 d. Testicular testosterone content increased significantly on Day 28 after infection but was lower than that of controls on Day 58 while it increased in scrotal-insulated rams compared with that of controls by Day 58. Testicular progesterone was undetectable in the control and trypanosome-infected groups throughout the experiment, but it increased in the insulated rams by day 58. Basal (unstimulated) Leydig cell testosterone production in the infected rams was similar to that of control rams on Day 28 but was significantly lower on Day 58. Stimulation of Leydig cell testosterone production with hCG or 22R-hydroxycholesterol (22ROHC) significantly reduced in infected rams at both 28 and 58 d after infection as well as in scrotal-insulated rams on Day 58. It is concluded that the increase in testicular testosterone content in the infected and scrotal-insulated rams on Days 28 and 58, respectively, was induced by elevation of testicular temperature by trypanosome infection, perhaps through an effect on testicular blood flow. Reduced testosterone production by Leydig cells from infected and scrotal-insulated rams in response to hCG and 22ROHC suggests that trypanosome-induced pyrexia might be involved in reducing Leydig cell steroidogenesis and subsequent plasma testosterone levels, possibly by affecting enzymes involved in steroid biosynthesis.

Journal Article↗

PubMed1980

Evaluation of insulating materials used during cryosurgery.

During the performance of cryosurgery it is of paramount importance to protect surrounding normal tissue from injury during the freezing process. This study evaluates three different insulating materials that are commonly used: petrolatum gauze, wooden tongue depressors, and styrofoam. To measure the effectiveness of these different insulators, the temperature gradient that developed across these barriers during a freezing cycle was measured. Five separate trials were carried out with each of the insulators, and the grafts demonstrated the results of these experimental trails. The superior insulator was styrofoam. Significant protection was afforded by wood and little protection by the layers of petrolatum gauze. In spite of the similarity in protection offered by the styrofoam and wood insulators, styrofoam is superior because of its flexibility. Our studies indicate that styrofoam is the best and most practical insulator to use during cryosurgical procedures in the head and neck area.

Bandages↗

PubMed2000

A chromatin insulator determines the nuclear localization of DNA.

Chromatin insulators might regulate gene expression by controlling the subnuclear organization of DNA. We found that a DNA sequence normally located inside of the nucleus moved to the periphery when the gypsy insulator was placed within the sequence. The presence of the gypsy insulator also caused two sequences, normally found in different regions of the nucleus, to come together at a single location. Alterations in this subnuclear organization imposed by the gypsy insulator correlated with changes in gene expression that took place during the heat-shock response. These global changes in transcription were accompanied by dramatic alterations in the distribution of insulator proteins and DNA. The results suggest that the nuclear organization imposed by the gypsy insulator on the chromatin fiber is important for gene expression.

Animals↗

PubMed2004

Poly(ADP-ribosyl)ation regulates CTCF-dependent chromatin insulation.

Chromatin insulators demarcate expression domains by blocking the cis effects of enhancers or silencers in a position-dependent manner. We show that the chromatin insulator protein CTCF carries a post-translational modification: poly(ADP-ribosyl)ation. Chromatin immunoprecipitation analysis showed that a poly(ADP-ribosyl)ation mark, which exclusively segregates with the maternal allele of the insulator domain in the H19 imprinting control region, requires the bases that are essential for interaction with CTCF. Chromatin immunoprecipitation-on-chip analysis documented that the link between CTCF and poly(ADP-ribosyl)ation extended to more than 140 mouse CTCF target sites. An insulator trap assay showed that the insulator function of most of these CTCF target sites is sensitive to 3-aminobenzamide, an inhibitor of poly(ADP-ribose) polymerase activity. We suggest that poly(ADP-ribosyl)ation imparts chromatin insulator properties to CTCF at both imprinted and nonimprinted loci, which has implications for the regulation of expression domains and their demise in pathological lesions.

Animals↗

PubMed1999

Positional enhancer-blocking activity of the chicken beta-globin insulator in transiently transfected cells.

It is thought that insulators demarcate transcriptionally and structurally independent chromatin domains. Insulators are detected by their ability to block enhancer-promoter interactions in a directional manner, and protect a transgene from position effects. Most studies are performed in stably transformed cells or organisms. Here we analyze the enhancer-blocking activity of the chicken beta-globin insulator in transient transfection experiments in both erythroid and nonerythroid cell lines. We show that four tandem copies of a 90-bp fragment of this insulator were able to block an enhancer in these experiments. In circular plasmids, placement on either side of the enhancer reduced activity, but when the plasmid was linearized, the enhancer-blocking activity was observed only when the insulator was placed between the promoter and the enhancer. These observations are consistent with the position-dependent enhancer-blocking activity of the insulator observed in stable transformation experiments.

Animals↗

PubMed2000

Transcriptional repression mediated by polycomb group proteins and other chromatin-associated repressors is selectively blocked by insulators.

Polycomb group (PcG) proteins repress gene activity over a considerable distance, possibly by spreading along the chromatin fiber. Insulators or boundary elements, genetic elements within the chromatin, may serve to terminate the repressing action of PcG proteins. We studied the ability of insulators to block the action of chromatin-associated repressors such as PcG proteins, HP1, and MeCP2. We found that the Drosophila special chromatin structure insulator completely blocks transcriptional repression mediated by all of the repressors we tested. The Drosophila gypsy insulator was able to block the repression mediated by the PcG proteins Su(z)2 and RING1, as well as mHP1, but not the repression mediated by MeCP2 and the PcG protein HPC2. The 5'-located DNase I-hypersensitive site in the chicken beta-globin locus displayed a limited ability to block repression, and a matrix or scaffold attachment region element was entirely unable to block repression mediated by any repressor tested. Our results indicate that insulators can block repression mediated by PcG proteins and other chromatin-associated repressors, but with a high level of selectivity. This high degree of specificity may provide a useful assay to define and characterize distinct classes of insulators.

Animals↗

PubMed1999

Chemical components of shredded paper insulation: a preliminary study.

We conducted an evaluation of shredded paper insulation to identify potentially toxic components. The study was to provide a preliminary characterization of a few samples of insulation currently in use. The following samples were analyzed: previously produced insulation (PPI) containing fire retardants, shredded recycled paper (PPI feedstock), freshly produced insulation (FPI), and insulation which had been installed in a residence (II). Volatile constituents were analyzed by GC-MS from headspace air of samples held at room temperature or heated to 90 degrees C. Extractable constituents were sampled by extracting with methylene chloride, and analyzing by GC-MS. Formaldehyde analysis was done according to EPA Method TO11. Headspace air at room temperature contained no detectable quantities of volatile constituents for any sample measured. In headspace air at 90 degrees C, only PPI contained traces of aliphatic and aromatic hydrocarbons and higher aldehydes, and FPI traces of toluene. Extracts of PPI contained traces of octadecadienoic acid methyl ester and aliphatic and aromatic hydrocarbons and higher aldehydes. Extracts of PPI feedstock contained traces of a substituted cyclohexenecarboxylic acid. FPI contained extractable diethyl phthalate (30-50 micrograms/g). Extracts of II contained traces of methyl palmitate, an octadecenoic acid methyl ester, and a phthalate plasticizer. No formaldehyde was detected. PPI was composed of approximately 98 percent paper fiber and 2 percent pre-gelatinized starch. PPI samples agglomerated together with less than 0.01 percent separating from clumps as fine dust. Boron and sodium were expected and confirmed because they were added to PPI and FPI as fire retardants. Chromium, copper, iron, potassium, magnesium, manganese, phosphorus, and silicon were present at detectable concentrations. Study calculations indicate that an occupant would have to completely consume all the fine particles produced from 3.3 kg of insulation per day to have an intake of boron equivalent to the EPA RfD. No other constituent appeared to be present even close to toxicologically relevant amounts.

Air Pollutants↗

PubMed1999

Determination of heat loss from the feet and insulation of the footwear.

This study compared the methods of determining the footwear insulation on human participants and the thermal foot model. Another purpose was to find the minimal number of measurement points on the human foot that is needed for insulation calculation. Bare foot was tested at 3 ambient temperatures on 6 participants. Three types of footwear were tested on 2 participants. The mean insulation for a bare foot obtained on the participant and model were similar. The insulation of warm footwear measured by the 2 methods was also similar. For thin footwear the insulation values from the participants were higher than those from the thermal model. The differences could be related to undefined physiological factors. Two points on foot can be enough to measure the insulation of footwear on human participants (r =.98). However, due to the big individual differences of humans, and good repeatability and simplicity of the thermal foot method, the latter should be preferred for testing.

Adult↗

PubMed2005

Assessment of fungal growth on sodium polyborate-treated cellulose insulation.

Cellulose insulation has rapidly gained a large market share among general contractors and homeowners. Recent interest regarding health effects of high concentrations of fungi within indoor environments (building-related illnesses or sick building syndrome) has promoted concern about susceptibility of building materials, including wood products (in general) and cellulose insulation (specifically), to fungal attack. This study reports an assessment of fungal growth on cellulose insulation made from recycled paper and treated with varying concentrations of sodium polyborate within half-scale wall units exposed to variable and high ambient temperatures and relative humidities throughout the summer. Boron-treated and untreated (control) cellulose insulation within the wall units were challenged with a suspension containing high concentrations of spores of five fungal species commonly found in indoor environments. Our results suggest that cellulose insulation treated with sodium polyborate (a) precludes the growth of the five common fungal species; (b) harbors fewer fungal species before and after being challenged with the fungal spore suspension; and (c) is likely having a cytotoxic or sporocidal effect on many, if not all, fungal species. These results suggest that cellulose insulation treated with sodium polyborate, when properly applied and installed, precludes fungal growth for at least 124 days at high temperatures and relative humidities.

Air Pollution, Indoor↗

PubMed1997

Direct evidence for the contribution of B cells to the progression of insulitis and the development of diabetes in non-obese diabetic mice.

The non-obese diabetic (NOD) mouse is an excellent animal model of autoimmune diabetes associated with insulitis. The progression of insulitis causes the destruction of pancreatic beta cells, resulting in the development of hyperglycemia. Although it has been well documented that T cells are required for the development of insulitis and diabetes in NOD mice, the importance of B cells remains unclear. To clarify the role of B cells in the pathogenesis of NOD mice, we therefore generated B cell-deficient NOD (B-NOD) mice. Surprisingly, none (of 13) of the B-NOD mice developed diabetes by 40 weeks of age, while the control littermates with B cells (B+NOD) suffered from a high proportion (43 of 49) of diabetes. The insulin reactivity of B+NOD mice was significantly impaired, while the B-NOD mice showed a good insulin response, thus suggesting the pancreatic beta cell function to be well preserved in B-NOD mice. Although B-NOD mice did develop insulitis, the extent of insulitis was significantly suppressed. These data thus provide the direct evidence that B cells are essential for the progression of insulitis and the development of diabetes in NOD mice.

Animals↗

PubMed2003

Retrovirus silencer blocking by the cHS4 insulator is CTCF independent.

Silencing of retrovirus vectors poses a significant obstacle to genetic manipulation of stem cells and their use in gene therapy. We describe a mammalian silencer blocking assay using insulator elements positioned between retrovirus silencer elements and an LCRbeta-globin reporter transgene. In transgenic mice, we show that retrovirus silencers are blocked by the cHS4 insulator. Silencer blocking is independent of the CTCF binding site and is most effective when flanking the internal reporter transgene. These data distinguish silencer blocking activity by cHS4 from its enhancer blocking activity. Retrovirus vectors can be created at high titer with one but not two internal dimer cHS4 cores. cHS4 in the LTRs has no effect on expression in transduced F9 cells, suggesting that position effect blocking is not sufficient to escape silencing. The Drosophila insulators gypsy and Scs fail to block silencing in transgenic mice, but gypsy stimulates vector expression 2-fold when located in the LTRs of an infectious retrovirus. The silencer blocking assay complements existing insulator assays in mammalian cells, provides new insight into mechanisms of insulation and is a valuable tool to identify additional silencer blocking insulators that cooperate with cHS4 to improve stem cell retrovirus vector design.

Animals↗

PubMed1991

Perioperative thermal insulation.

To determine the efficacy of passive insulators advocated for prevention of cutaneous heat loss, we determined heat loss in unanesthetized volunteers covered by one of the following: a cloth "split sheet" surgical drape; a Convertors disposable-paper split sheet; a Thermadrape disposable laparotomy sheet; an unheated Bair Hugger patient-warming blanket; 1.5-mil-thick plastic hamper bags; and a prewarmed, cotton hospital blanket. Cutaneous heat loss was measured using 10 area-weighted thermal flux transducers while volunteers were exposed to a 20.6 degrees C environment for 1 h. Heat loss decreased significantly from 100 +/- 3 W during the control periods to 69 +/- 6 W (average of all covers) after 1 h of treatment. Heat losses from volunteers insulated by the Thermadrape (61 +/- 6 W) and Bair Hugger covers (64 +/- 5 W) were significantly less than losses from those insulated by plastic bags (77 +/- 11 W). The paper drape (67 +/- 7 W) provided slightly, but not significantly, better insulation than the cloth drape (70 +/- 4 W). Coverage by prewarmed cotton blankets initially resulted in the least heat loss (58 +/- 8 W), but after 40 min, resulted in heat loss significantly greater than that for the Thermadrape (71 +/- 7 W). Regional heat loss was roughly proportional to surface area, and the distribution of regional heat loss remained similar with all covers. These data suggest that cost and convenience should be major factors when choosing among passive perioperative insulating covers. It is likely that the amount of skin surface covered is more important than the choice of skin region covered or the choice of insulating material.

Adult↗

PubMed1993

Distribution of pancreatic macrophages preceding and during early insulitis in young NOD mice.

Indirect evidence suggests there may be early influx of beta-cell-directed macrophages into the islets of NOD mice, and before the onset of T-cell insulitis. We have therefore examined immunohistochemically the pancreas of young female NOD mice with monoclonal antibody F4/80 for the presence of macrophages in intraislet, peri-islet, exocrine, and perivascular regions preceding insulitis (days 18 and 22) and during early insulitis (days 30 and 40) and compared their distribution in age-matched normal Swiss mouse pancreas. In the absence of insulitis (day 18 and day 22) and during very early insulitis (day 30) macrophage-positive cells had a predominantly exocrine and perivascular distribution with reduced numbers in the peri-islet area. Intraislet macrophages usually occurred singly and were sparse. At day 40, an enhanced influx of the immune cells was observed in intra- and peri-islet locations and in parallel with increased numbers in the exocrine areas. At this age, higher numbers of macrophages were observed within the islet, distributed among the T-cell infiltrate and also scattered among the endocrine cells. During the study period, the number of macrophages in the peri-, intraislet, and exocrine regions was significantly higher among NOD mice than in the Swiss mouse group (p = 0.003, p = 0.005, and p = 0.0009, respectively). In the absence of insulitis (days 18 and 22), although the number of positive cells tended to be higher in NOD mice, this difference reached statistical significance in the peri-islet area (p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1970

The total thermal insulation of the new-born baby.

1. One hundred and seventeen healthy new-born babies weighing between 0.9 and 4.8 kg at delivery have been studied during the first ten days of life, and sixteen of these babies have been studied serially for 6 weeks after birth. The babies lay supine in a draught-free environment (air speed 4-5 cm/sec) of moderate humidity. The operative temperature was between 26 and 38 degrees C for the babies who were studied naked.2. Total non-evaporative heat loss was calculated from simultaneous measurements of oxygen consumption, evaporative water loss and the concomitant change in mean body temperature.3. Approximately 10% of the total body surface area was in contact with the mattress or floor. Conductive heat loss accounted for only about 5% of all non-evaporative heat loss when the naked baby was lying on a thick foam mattress, but for as much as 25% when the baby was lying in a water-jacketed chamber with a floor of clear plastic approximately 5 mm thick.4. Insulation to heat loss by convection and radiation varied with environmental temperature. Total specific insulation was low in a warm environment when the naked baby vasodilated, and rose by between 16 and 25% to a maximum in an environment of 31 degrees C. It decreased significantly when the baby became physically active in environments with a temperature less than this.5. Total specific insulation in an environment of 31 degrees C varied with body size: it averaged 0.156 degrees C.m(2).hr/kcal in seven naked babies weighing 0.9-1.2 kg, rose to 0.190 degrees C.m(2).hr/kcal in twelve babies weighing 1.8-2.2 kg, and averaged 0.201 degrees C.m(2).hr/kcal in the thirty-four babies who weighed over 3 kg. Tissue insulation accounted for 23% of this total specific insulation in the smaller babies, and about 28% of the total in babies weighing over 3 kg.6. Clothing ten babies in a vest, napkin and long cotton nightdress increased the total specific insulation by an average of 0.23 degrees C.m(2).hr/kcal.

Birth Weight↗