Simulating the human body's microclimate using automatic coupling of CFD and an advanced thermoregulation model.

This study aims to develop an approach to couple a computational fluid dynamics (CFD) solver to the University of California, Berkeley (UCB) thermal comfort model to accurately evaluate thermal comfort. The coupling was made using an iterative JavaScript to automatically transfer data for each individual segment of the human body back and forth between the CFD solver and the UCB model until reaching convergence defined by a stopping criterion. The location from which data are transferred to the UCB model was determined using a new approach based on the temperature difference between subsequent points on the temperature profile curve in the vicinity of the body surface. This approach was used because the microclimate surrounding the human body differs in thickness depending on the body segment and the surrounding environment. To accurately simulate the thermal environment, the numerical model was validated beforehand using experimental data collected in a climate chamber equipped with a thermal manikin. Furthermore, an example of the practical implementations of this coupling is reported in this paper through radiant floor cooling simulation cases, in which overall and local thermal sensation and comfort were investigated using the coupled UCB model.

Measuring the human body's microclimate using a thermal manikin.

UNLABELLED: The human body is surrounded by a microclimate, which results from its convective release of heat. In this study, the air temperature and flow velocity of this microclimate were measured in a climate chamber at various room temperatures, using a thermal manikin simulating the heat release of the human being. Different techniques (Particle Streak Tracking, thermography, anemometry, and thermistors) were used for measurement and visualization. The manikin surface temperature was adjusted to the particular indoor climate based on simulations with a thermoregulation model (UCBerkeley Thermal Comfort Model). We found that generally, the microclimate is thinner at the lower part of the torso, but expands going up. At the head, there is a relatively thick thermal layer, which results in an ascending plume above the head. However, the microclimate shape strongly depends not only on the body segment, but also on boundary conditions: The higher the temperature difference between the surface temperature of the manikin and the air temperature, the faster the airflow in the microclimate. Finally, convective heat transfer coefficients strongly increase with falling room temperature, while radiative heat transfer coefficients decrease. The type of body segment strongly influences the convective heat transfer coefficient, while only minimally influencing the radiative heat transfer coefficient. PRACTICAL IMPLICATIONS: The findings of this study generate a better understanding of the human body's microclimate, which is important in fields such as thermal comfort, HVAC, or indoor air quality. Additionally, the measurements can be used by CFD users for the validation of their simulations.

Roles of tandem-pore K+ channels in plants - a puzzle still to be solved.

The group of voltage-independent K(+) channels in Arabidopsis thaliana consists of six members, five tandem-pore channels (TPK1-TPK5) and a single K(ir)-like channel (KCO3). All TPK/KCO channels are located at the vacuolar membrane except for TPK4, which was shown to be a plasma membrane channel in pollen. The vacuolar channels interact with 14-3-3 proteins (also called General Regulating Factors, GRFs), indicating regulation at the level of protein-protein interactions. Here we review current knowledge about these ion channels and their genes, and highlight open questions that need to be urgently addressed in future studies to fully appreciate the physiological functions of these ion channels.

Er81 is expressed in a subpopulation of layer 5 neurons in rodent and primate neocortices.

Laminar organization is a fundamental cytoarchitecture in mammalian CNS and a striking feature of the neocortex. ER81, a transcription factor, has recently been utilized as a marker of cells in the layer 5 of the neocortex. We further pursued the distribution of ER81 to investigate the identity of the ER81-expressing cells in the brain. Er81 transcript was expressed in a subset of pyramidal cells that were scattered throughout the entire width of layer 5. In the rat cortex, Er81 transcripts were first detected in the ventricular zone at E15, remained expressed in putative prospective layer 5 neurons during infant and juvenile stages. The ER81-expressing subpopulation in adult layer 5 neurons did not segregate with the phenotypes of the projection targets. By retrograde labeling combined with immunohistochemistry or reverse transcription-polymerase chain reaction analysis, we found ER81 expression in nearly all of the layer 5 neurons projecting to the spinal cord or to the superior colliculus, while in only one-third of the layer 5 neurons projecting to the contralateral cortex. Er81 was also detected in layer 5 neurons in a P2 Japanese macaque monkey but not in adult monkey cortices. These findings suggest that a neuron class defined by a molecular criterion does not necessarily segregate with that defined by an anatomical criterion, that ER81 is involved in cell differentiation of a subset of layer 5 projection neurons and that this mechanism is conserved among rodents and primates.

AtTPK4, an Arabidopsis tandem-pore K+ channel, poised to control the pollen membrane voltage in a pH- and Ca2+-dependent manner.

The Arabidopsis tandem-pore K(+) (TPK) channels displaying four transmembrane domains and two pore regions share structural homologies with their animal counterparts of the KCNK family. In contrast to the Shaker-like Arabidopsis channels (six transmembrane domains/one pore region), the functional properties and the biological role of plant TPK channels have not been elucidated yet. Here, we show that AtTPK4 (KCO4) localizes to the plasma membrane and is predominantly expressed in pollen. AtTPK4 (KCO4) resembles the electrical properties of a voltage-independent K(+) channel after expression in Xenopus oocytes and yeast. Hyperpolarizing as well as depolarizing membrane voltages elicited instantaneous K(+) currents, which were blocked by extracellular calcium and cytoplasmic protons. Functional complementation assays using a K(+) transport-deficient yeast confirmed the biophysical and pharmacological properties of the AtTPK4 channel. The features of AtTPK4 point toward a role in potassium homeostasis and membrane voltage control of the growing pollen tube. Thus, AtTPK4 represents a member of plant tandem-pore-K(+) channels, resembling the characteristics of its animal counterparts as well as plant-specific features with respect to modulation of channel activity by acidosis and calcium.

Can imaginary head tilt shorten postrotatory nystagmus?

In healthy subjects, head tilt upon cessation of a constant-velocity yaw head rotation shortens the duration of postrotatory nystagmus. The presumed mechanism for this effect is that the velocity storage of horizontal semicircular canal inputs is being discharged by otolith organ inputs which signal a constant yaw head position when the head longitudinal axis is no longer earth-vertical. In the present study, normal subjects were rotated head upright in the dark on a vertical-axis rotational chair at 60 degrees/s for 75 s and were required to perform a specific task as soon as the chair stopped. Horizontal position of the right eye was recorded with an infra-red video camera. The average eye velocity (AEV) was measured over a 30-s interval following chair acceleration/deceleration. The ratios (postrotatory AEV/perrotatory AEV) were 1.1 (SD 0.112) when subjects (N=10) kept their head erect, 0.414 (SD 0.083) when subjects tilted their head forward, 1.003 (SD 0.108) when subjects imagined watching a TV show, 1.012 (SD 0.074) when subjects imagined looking at a painting on a wall, and 0.995 (SD 0.074) when subjects imagined floating in a prone position on a lake. Thus, while actual head tilt reduced postrotatory nystagmus, the imagination tasks did not have a statistically significant effect on postrotatory nystagmus. Therefore, velocity storage does not appear to be under the influence of cortical neural signals when subjects imagine that they are floating in a prone orientation.

Reaction of neuronal nitric-oxide synthase with oxygen at low temperature. Evidence for reductive activation of the oxy-ferrous complex by tetrahydrobiopterin.

The reaction of reduced NO synthase (NOS) with molecular oxygen was studied at -30 degreesC. In the absence of substrate, the complex formed between ferrous NOS and O2 was sufficiently long lived for a precise spectroscopic characterization. This complex displayed similar spectral characteristics as the oxyferrous complex of cytochrome P450 (lambda max = 416.5 nm). It then decomposed to the ferric state. The oxidation of the flavin components was much slower and could be observed only at temperatures higher than -20 degreesC. In the presence of substrate (L-arginine), another, 12-nm blue-shifted, intermediate spectrum was formed. The breakdown of the latter species resulted in the production of Nomega-hydroxy-L-arginine in a stoichiometry of maximally 52% per NOS heme. This product formation took place also in the absence of the reductase domain of NOS. Both formation of the blue-shifted intermediate and of Nomega-hydroxy-L-arginine required the presence of tetrahydrobiopterin (BH4). We propose that the blue-shifted intermediate is the result of reductive activation of the oxygenated complex, and the electron is provided by BH4. These observations suggest that the reduction of the oxyferroheme complex may be the main function of BH4 in NOS catalysis.

Essential role of the beta subunit in modulation of C-class L-type Ca2+ channels by intracellular pH.

Elevation of intracellular pH (pHi) enhances the activity of native L-type Ca2+ channels in cardiac and smooth muscle. We studied the modulation by pHi of expressed L-type Ca2+ channels comprised of either the alpha1c subunits alone or of alpha1c plus beta2a subunits. Ca2+ channels were expressed in human embryonic kidney cells (HEK 293) and pHi was increased from a basal level of 7.3 to 8.3 by exposure of cells to NH4Cl (20 mM) or by elevation of extracellular pH to 8.5. Elevation of pHi enhanced the activity of Ca2+ channels derived by coexpression of alpah1c and beta2a subunits. This alkalosis-induced stimulation of channel activity was mainly due to an increase in channel availability. Channels derived by expression of alpha1c alone were not affected by intracellular alkalosis. Our results demonstrate that the pHi sensitivity of L-type Ca2+ channels is conferred by the beta subunit of the channel complex.

Pregnant adolescents in the emergency department: diagnosed and not diagnosed.

A study was conducted to compare the presenting complaints and historical information of adolescents diagnosed as pregnant (DP) in the emergency department (ED) with adolescents seen in the ED who were pregnant and not diagnosed (MP). Medical records for the period 1980-94 were retrospectively analyzed to identify patients 16 years of age or younger who were diagnosed as pregnant in the ED or who had a live birth and had an ED visit during pregnancy. This analysis was done in a university-affiliated tertiary referral hospital with approximately 65,000 ED visits and 3,500 deliveries each year. The DP patients had complaints referable to the abdomen or genitourinary system more commonly than the MP patients (91% v 22%). Less than 10% of the DP patients mentioned the possibility of pregnancy at initial triage, 10.5% denied being sexually active, and 5% had a pelvic examination and sexually transmitted disease screening; 68% of MP patients did not have sexual or menstrual history documented, and 5% had a pelvic examination. The diagnosis of pregnancy can be a challenge in patients who present to a busy ED with complaints that are not necessarily suggestive of pregnancy. Historical information regarding menses and sexual activity is either not obtained or is incomplete or inaccurate. We recommend a low threshold for the consideration of pregnancy in adolescents irrespective of the presenting complaint.

PIP: A retrospective study was performed at a tertiary care hospital in Mississippi to compare the emergency room (ER) presenting complaints during 1980-1994 of the 171 pregnant adolescents 16 years old and younger whose pregnancies were diagnosed with the 100 whose pregnancies were not diagnosed. Data were collected from the medical records of those diagnosed as pregnant and from the 2945 records available of the 4125 patients under 16 who delivered babies at the hospital during the same period. It was found that 100/2945 were seen in the ER while pregnant but the pregnancy was not diagnosed. It was found that 91% of the pregnancy diagnosed patients versus 22% of the missed diagnosis patients had complaints relating to the abdomen or genitourinary system. Less than 10% of the diagnosed patients indicated the possibility of pregnancy at the initial examination, and 10.5% denied being sexually active. No sexual or menstrual history was documented for 68% of the missed diagnosis patients, and 5% of each group had pelvic examinations. No significant differences were found for patient age or demographics, gestation at ER visit, or gestation at delivery. In 30 cases of missed diagnoses (all with gestation at 8 weeks or more), 23 presented with abdominal, genitourinary, or mammary complaints, and 7 presented with drug overdoses. In 22 patients, diagnosis was missed even though the pregnancy was at 22 weeks gestation or more. One extraordinary case involved a 14-year-old who was admitted for treatment of a gunshot to the head. Her pregnancy was not diagnosed until her second follow-up visit after a lengthy hospital stay (gestation was 30 weeks at ER presentation). Because many treatments are modified by pregnancy, it is recommended that pregnancy be assumed in all females of child-bearing age presenting to the ER with consideration given to degree of sexual maturity.

Inducible nitric oxide synthase and the regulation of central vessel caliber in the fetal rat.

BACKGROUND: The purpose of this study was to evaluate the possibility that inducible nitric oxide synthase (iNOS) regulates the fetal circulation. METHODS AND RESULTS: Positive evidence for iNOS gene expression was noted in heart central vessels and placenta of untreated rat fetuses. Rats in the last week of pregnancy were treated for 5 days with L-NG-(1-Iminoethyl)lysine (L-NIL), a selective inhibitor of iNOS, at 1, 10, and 100 micrograms/mL in the drinking water. To raise NO levels, lipopolysaccharide (LPS) 30 micrograms/kg was given by intraperitoneal injection, and sodium nitroprusside (SNP) was placed in mini-osmotic pumps to deliver 10 micrograms/kg per minute. Control animals were undisturbed. On day 21 of gestation, dams were anesthetized and fetuses were delivered by cesarean section and rapidly frozen in isopentane chilled in liquid nitrogen. Frozen sections (10 microns) were used to reconstruct a computer-generated three-dimensional image of the great vessels and ductus arteriosus. Significant constriction of the great vessels and ductus arteriosus was observed with L-NIL, whereas both LPS and SNP dilated these vessels. The vasorelaxant effect of LPS was blocked by L-NIL. NO release from placental explants was 633 +/- 41 nmol/L under basal conditions, increasing to 4.0 +/- 0.4 mumol/L with LPS administration, although placental iNOS message and protein levels were unchanged. CONCLUSIONS: We suggest that nitric oxide, generated by iNOS, plays a significant role in control of major vessel and ductus arteriosus caliber in the rat fetus. In regard to the nitrergic regulation of the circulation, the fetus is clearly different from the adult.

Removal of femoral sheaths by registered nurses: issues and outcomes.

The results of this evaluation indicate that specially trained critical care nurses can remove femoral sheaths with an acceptable margin of safety. As a result, these nurses can provide quality, cost-effective care to angioplasty patients. However, before this procedure is included as part of the RN's responsibility, written protocols are needed to identify appropriate patients, proper removal technique, and specific actions to take if complications occur. In addition, plans must be developed for initial education and ongoing competency evaluation to ensure that each nurse involved maintains an adequate knowledge base and skill level.

Fetal growth retardation in rats may result from apoptosis: role of peroxynitrite.

Administration of the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) results in fetal growth retardation. This study was designed to further examine the influence of NO on fetal growth, specifically, the potential role of inducible NOS and to evaluate the possibility that apoptosis contributed to uteroplacental dysfunction. L-NAME administration caused a paradoxical increase in NO synthesis determined by direct detection of NO by electrochemistry, nitrite accumulation, and cGMP levels, indicating that a lack of NO was not the cause of the fetal growth retardation. Additionally, supplemental L-arginine or NO donors failed to reverse the effects of L-NAME on fetal and placental size. Administration of low dose endotoxin (30 micrograms/kg IP daily for 6 d) also caused significant reductions in fetal and placental size and increased NO synthesis comparable to that seen with L-NAME. Inducible NOS was constitutively expressed in the pregnant uterus (smooth muscle and epithelia) and placenta (sinusoids and macrophages) but was absent in the nonpregnant state as determined by RT-PCR and immunohistochemistry. Neither L-NAME nor endotoxin modified the expression of iNOS. In situ evidence for apoptosis (DNA fragmentation) was minimal to absent in control pregnant rats, but markedly evident in the placenta (decidua) and uterus of rats treated with L-NAME or endotoxin. Immunohistochemical evidence for nitrotyrosine, a marker for peroxynitrite formation, was absent in control rats but colocalized with apoptosis in the L-NAME and LPS groups. We conclude that L-NAME-induced fetal growth retardation is not due to a lack of NO, but as for endotoxin, results from a net reduction in cellular proliferation due to the induction of apoptosis, possibly in response to peroxynitrite formation.

Perinatal nitric oxide synthase inhibition retards neonatal growth by inducing hypertrophic pyloric stenosis in rats.

Administration of the nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) during pregnancy has been shown to compromise fetal growth. This study was designed to determine whether aminoguanidine, a predominate inhibitor of inducible NOS, affects fetal outcome. In addition, we extended the prenatal administration of L-NAME into the postnatal period (14 d) to determine whether neonatal growth and maturation were also affected. L-NAME, but not aminoguanidine, compromises fetal and placental growth. When compared with control 14-d-old pups, postnatal L-NAME compromised neonatal growth, whether it was given directly (intraperitoneally) (39.7 +/- 1.1 versus 24.1 +/- 1.0 g) or indirectly (38.6 +/- 0.5 versus 22.2 +/- 1.2 g) via maternal breast milk. Neonatal growth retardation was asymmetric, with brain sparing, suggesting a nutritional origin. L-NAME administration resulted in growth retardation that extended into adulthood, without evidence of catch-up growth. Treated neonates displayed the hallmarks of hypertrophic pyloric stenosis. Significant increases in stomach weight/pup weight (9.9 +/- 0.3 versus 8.2 +/- 0.4 x 10(3)) and stomach volume/pup weight (12.0 +/- 0.6 versus 9.4 +/- 0.6 mL/100 g) with a concomitant decrease in small intestine weight/length (2.10 +/- 0.08 versus 3.18 +/- 0.13 g/100 cm) was noted in treated versus control pups (p < 0.05). Muscularis hypertrophy at the pyloric sphincter in the L-NAME-treated pups was noted by histology. Blood pressure was elevated in the L-NAME-treated pups (93 +/- 6 versus 60 +/- 5 mm Hg in control pups, p < 0.05). These findings are consistent with inhibition of neuronal and endothelial NOS activity. We conclude that NO, formed via the constitutive isoforms of NOS, is a critical determinant of fetal and neonatal growth and maturation.

Nitric oxide synthase inhibition decreases tolerance to hyperoxia in newborn rats.

We evaluated the effects of sustained perinatal inhibition of NO synthase (NOS) on hyperoxia induced lung injury in newborn rats. N(G)-nitro-Larginine-methyl-ester (L-NAME) or untreated water was administered to pregnant rats for the final 7 days of gestation and during lactation; followed by postnatal exposure to hyperoxia (>95% O(2)) or room air. The survival rate of L-NAME treated pups when placed in > 95% O(2) at birth was significantly lower than controls from day 4 (L-NAME, 87%; control pups, 100%, p < 0.05) to 14 (L-NAME, 0%; control pups, 53%, p < 0.05). Foetal pulmonary artery vasoconstriction was induced by L-NAME with a decrease in internal diameter from 0.88 +/- 0.03 mm to 0.64 +/- 0.01 mm in control vs. L-NAME groups (p < 0.05), respectively. We conclude that perinatal NOS inhibition results in pulmonary artery vasoconstriction and a decreased tolerance to hyperoxia induced lung injury in newborn rats.

Nitric oxide inhibition causes intrauterine growth retardation and hind-limb disruptions in rats.

OBJECTIVE: Our purpose was to determine the effects of nitric oxide synthase inhibition on maternal and fetal health in the last third of pregnancy. STUDY DESIGN: Pregnant rats were treated from gestational day 13 to day 19 or 20 with the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester, which was administered in the drinking water ad libitum. Control animals received the inactive enantiomer NG-nitro-D-arginine methyl ester or no treatment. Maternal blood pressure, blood chemistry studies, and placenta and pup size were determined. A separate group of rats received nitroprusside sodium in conjunction with NG-nitro-L-arginine methyl ester. RESULTS: NG-nitro-L-arginine methyl ester caused a dose-dependent reduction in placenta and pup size. Amniotic fluid levels of cyclic guanosine monophosphate were significantly reduced at 0.1 mg/ml but not at higher doses. Hemorrhagic necrosis of fetal hind limbs occurred only with treatment with NG-nitro-L-arginine methyl ester and was prevented by coadministration of nitroprusside sodium. Maternal blood pressure and blood and urine chemistry studies were unaffected by NG-nitro-L-arginine methyl ester. CONCLUSION: Chronic reductions of nitric oxide production in the last third of pregnancy result in significant intrauterine growth retardation and hemorrhagic disruptions of hind limbs. Maternal complications were minimal and did not mimic preeclampsia.

Henoch-Schönlein purpura: four cases and a review.

Henoch-Schönlein Purpura (HSP) is a common, usually self-limited, vasculitis affecting children and young adults. Manifested by a characteristic rash, the course of HSP is typically a benign one, but may be accompanied by varying degrees of abdominal pain, arthritis or arthralgia, gastrointestinal bleeding, and nephritis. The various manifestations of HSP may present at any stage during the illness and mimic other disease processes, some of which may be life threatening. Thus, the emergency physician must consider the diagnosis of HSP in order to detect complications and avoid needless intervention in what usually is an otherwise benign process. We present four cases and a brief review of the literature to highlight HSP in the differential diagnosis of patients who present with any of the typical clinical signs and symptoms.

Nucleotide sequence and analysis of the mgl operon of Escherichia coli K12.

The nucleotide sequence of the Escherichia coli K12 beta-methylgalactoside transport operon, mgl, was determined. Primer extension analysis indicated that the synthesis of mRNA initiates at guanine residue 145 of the determined sequence. The operon contains three open reading frames (ORF). The operator proximal ORF, mglB, encodes the galactose binding protein, a periplasmic protein of 332 amino acids including the 23 residue amino-terminal signal peptide. Following a 62 nucleotide spacer, the second ORF, mglA, is capable of encoding a protein of 506 amino acids. The amino-terminal and carboxyl-terminal halves of this protein are homologous to each other and each half contains a putative nucleotide binding site. The third ORF, mglC, is capable of encoding a hydrophobic protein of 336 amino acids which is thought to generate the transmembrane pore. The overall organization of the mglBAC operon and its potential to encode three proteins is similar to that of the ara FGH high affinity transport operon, located approximately 1 min away on the E. coli K12 chromosome.

Regulation and hospital strategic planning in Canada.

Constraints on resources push hospitals into strategic planning. Although this process is accelerating in the United States, Canadian hospitals need to approach planning according to the provincial structure. This study included a literature and policy review as well as interviews of key stakeholders. Decisions toward centralized planning versus hospital-initiated development were found to depend on the availability of planning and policy staff, and the views of the elected representatives. Implications for Canadian health care planners were offered.

High-affinity L-arabinose transport operon. Nucleotide sequence and analysis of gene products.

The nucleotide sequence of the "high-affinity" L-arabinose transport operon has been determined 3' from the regulatory region and found to contain three open reading frames designated araF, araG and araH. The first gene 3' to the regulatory region, araF, encodes the 23-residue signal peptide and the 306-residue mature form of the L-arabinose binding protein (33,200 Mr). The binding protein, which has been described elsewhere, is hydrophilic, soluble and found in the periplasm of Escherichia coli. This gene is followed by an intragenic space of 72 nucleotides, which contains a region of dyad symmetry 23 nucleotides long capable of forming an 11-member stem-loop. The second gene, designated araG, contains an open reading frame capable of encoding an equally hydrophilic protein containing 504 residues (55,000 Mr). Following a 14-nucleotide spacer, which does not appear to have any secondary structure, the third open reading frame, herein designated araH, is capable of encoding a hydrophobic protein containing 329 residues (34,000 Mr) that can only be envisioned as having an integral membrane location. 3' to araH there is a T-rich region containing a 24-nucleotide area of dyad symmetry centered 55 nucleotides from the termination codon. Analysis of the derived primary sequences of the araG and araH products indicates the nature and potential features of these components. The araG protein was found to possess internal homology between its amino and carboxyl-terminal halves, suggesting a common origin. The araG gene product has been shown to be homologous to the rbsA gene product, the hisP product, the ptsB product and the malK product, all of which presumably play similar roles in their respective transport systems. Putative ATP binding sites are observed within the regions of homology. The araH gene product has been shown to be homologous to the rbsC gene product, which is the first observed homology between two purported membrane proteins.