Role of Saccharomyces cerevisiae Rap1 protein in Ty1 and Ty1-mediated transcription

Binding sites for the transcription factor Rap1 are widespread in the yeast genome. With respect to many, but not all, genes, Rap1p has an apparent activation function. Whether Rap1 is itself a transcriptional activator, or whether it is in some way required for activation by additional factors, is not clear. We have identified a previously unrecognized Rap1p binding site in the internal regulatory region of Ty1 elements. We demonstrate that this site is capable of binding Rap1 in vitro and that, in vivo, Rap1p plays an important regulatory role in Ty1 and Ty1-mediated adjacent gene expression. Our data suggest that in Ty1 elements, maximal levels of RAP1-mediated activation depend on the formation of a complex with Mcm1, an independent DNA-binding protein that functions in transcription as well as in DNA replication, and with a third factor, IBF, previously identified as a binding activity with a site situated between the Rap1p and Mcm1p binding sites in this region of Ty1 elements.

Strong association between west african rainfall and u.s. Landfall of intense hurricanes

Intense hurricanes occurred much more frequently during the period spanning the late 1940s through the late 1960s than during the 1970s and 1980s, except for 1988 and 1989. Seasonal and multidecadal variations of intense hurricane activity are closely linked to seasonal and multidecadal variations of summer rainfall amounts in the Western Sahel region of West Africa. The multidecadal nature of West African precipitation variations and their association with variations of intense Atlantic hurricane activity can be observed in data going back nearly a century. The apparent recent breaking of the 18-year Sahel drought during 1988 and 1989 suggests that the incidence of intense hurricanes making landfall on the U.S. coast and in the Caribbean basin will likely increase during the 1990s and early years of the 21st century to levels of activity notably greater than were observed during the 1970s and 1980s.

Auxin regulates SCF(TIR1)-dependent degradation of AUX/IAA proteins

The plant hormone auxin is central in many aspects of plant development. Previous studies have implicated the ubiquitin-ligase SCF(TIR1) and the AUX/IAA proteins in auxin response. Dominant mutations in several AUX/IAA genes confer pleiotropic auxin-related phenotypes, whereas recessive mutations affecting the function of SCF(TIR1) decrease auxin response. Here we show that SCF(TIR1) is required for AUX/IAA degradation. We demonstrate that SCF(TIR1) interacts with AXR2/IAA7 and AXR3/IAA17, and that domain II of these proteins is necessary and sufficient for this interaction. Further, auxin stimulates binding of SCF(TIR1) to the AUX/IAA proteins, and their degradation. Because domain II is conserved in nearly all AUX/IAA proteins in Arabidopsis, we propose that auxin promotes the degradation of this large family of transcriptional regulators, leading to diverse downstream effects.

The recent increase in Atlantic hurricane activity: causes and implications

The years 1995 to 2000 experienced the highest level of North Atlantic hurricane activity in the reliable record. Compared with the generally low activity of the previous 24 years (1971 to 1994), the past 6 years have seen a doubling of overall activity for the whole basin, a 2.5-fold increase in major hurricanes (>/=50 meters per second), and a fivefold increase in hurricanes affecting the Caribbean. The greater activity results from simultaneous increases in North Atlantic sea-surface temperatures and decreases in vertical wind shear. Because these changes exhibit a multidecadal time scale, the present high level of hurricane activity is likely to persist for an additional approximately 10 to 40 years. The shift in climate calls for a reevaluation of preparedness and mitigation strategies.

Interactions of the COP9 signalosome with the E3 ubiquitin ligase SCFTIRI in mediating auxin response

The COP9 signalosome is an evolutionary conserved multiprotein complex of unknown function that acts as a negative regulator of photomorphogenic seedling development in Arabidopsis. Here, we show that plants with reduced COP9 signalosome levels had decreased auxin response similar to loss-of-function mutants of the E3 ubiquitin ligase SCFTIR1. Furthermore, we found that the COP9 signalosome and SCFTIR1 interacted in vivo and that the COP9 signalosome was required for efficient degradation of PSIAA6, a candidate substrate of SCFTIR1. Thus, the COP9 signalosome may play an important role in mediating E3 ubiquitin ligase-mediated responses.

Function of the ubiquitin-proteasome pathway in auxin response

The plant hormone auxin regulates many aspects of growth and development. Despite the importance of this hormone, the molecular basis for auxin action has remained elusive. Recent advances using molecular genetics in Arabidopsis have begun to elucidate the mechanisms involved in auxin signaling. These results suggest that protein degradation by the ubiquitin pathway has a central role in auxin response.

Identification of an SCF ubiquitin-ligase complex required for auxin response in Arabidopsis thaliana

The plant hormone auxin regulates diverse aspects of plant growth and development. We report that in Arabidopsis, auxin response is dependent on a ubiquitin-ligase (E3) complex called SCFTIR1. The complex consists of proteins related to yeast Skp1p and Cdc53p called ASK and AtCUL1, respectively, as well as the F-box protein TIR1. Mutations in either ASK1 or TIR1 result in decreased auxin response. Further, overexpression of TIR1 promotes auxin response suggesting that SCFTIR1 is limiting for the response. These results provide new support for a model in which auxin action depends on the regulated proteolysis of repressor proteins.

High temperature promotes auxin-mediated hypocotyl elongation in Arabidopsis

Physiological studies with excised stem segments have implicated the plant hormone indole-3-acetic acid (IAA or auxin) in the regulation of cell elongation. Supporting evidence from intact plants has been somewhat more difficult to obtain, however. Here, we report the identification and characterization of an auxin-mediated cell elongation growth response in Arabidopsis thaliana. When grown in the light at high temperature (29 degreesC), Arabidopsis seedlings exhibit dramatic hypocotyl elongation compared with seedlings grown at 20 degreesC. This temperature-dependent growth response is sharply reduced by mutations in the auxin response or transport pathways and in seedlings containing reduced levels of free IAA. In contrast, mutants deficient in gibberellin and abscisic acid biosynthesis or in ethylene response are unaffected. Furthermore, we detect a corresponding increase in the level of free IAA in seedlings grown at high temperature, suggesting that temperature regulates auxin synthesis or catabolism to mediate this growth response. Consistent with this possibility, high temperature also stimulates other auxin-mediated processes including auxin-inducible gene expression. Based on these results, we propose that growth at high temperature promotes an increase in auxin levels resulting in increased hypocotyl elongation. These results strongly support the contention that endogenous auxin promotes cell elongation in intact plants.

A system for psychomotor evaluation; design, implementation and practice effects in volunteers

This paper describes the design, implementation and assessment of PsychE, psychomotor evaluation system. Six standard tests are included: numeric vigilance, a dual task, probed memory recall, simple reaction time, choice reaction time and semantic long-term memory. The test presentations are described in detail. Practice effects were assessed in 10 healthy volunteers and were only evident in the performance measures for the simple reaction time test. For the remaining five tests, stable performance was reached within a single test session. The volunteers were healthy and most were regular users of computers. Therefore, the lack of practice effects cannot be assumed for the general population. A control group is essential for all studies using these tests. The system is implemented on an IBM-compatible personal computer and includes a database shell for the convenient collection, storage and analysis of performance data.

The TIR1 protein of Arabidopsis functions in auxin response and is related to human SKP2 and yeast grr1p

Genetic analysis in Arabidopsis has led to the identification of several genes that are required for auxin response. One of these genes, AXR1, encodes a protein related to yeast Aos1p, a protein that functions to activate the ubiquitin-related protein Smt3p. Here we report the identification of a new gene called TRANSPORT INHIBITOR RESPONSE 1 (TIR1). The tir1 mutants are deficient in a variety of auxin-regulated growth processes including hypocotyl elongation and lateral root formation. These results indicate that TIR1 is also required for normal response to auxin. Further, mutations in TIR1 display a synergistic interaction with mutations in AXR1, suggesting that the two genes function in overlapping pathways. The TIR1 protein contains a series of leucine-rich repeats and a recently identified motif called an F box. Sequence comparisons indicate that TIR1 is related to the yeast protein Grr1p and the human protein SKP2. Because Grr1p and other F-box proteins have been implicated in ubiquitin-mediated processes, we speculate that auxin response depends on the modification of a key regulatory protein(s) by ubiquitin or a ubiquitin-related protein.

Activated alleles of yeast SLN1 increase Mcm1-dependent reporter gene expression and diminish signaling through the Hog1 osmosensing pathway

Two-component signal transduction systems involving histidine autophosphorylation and phosphotransfer to an aspartate residue on a receiver molecule have only recently been discovered in eukaryotes, although they are well studied in prokaryotes. The Sln1 protein of Saccharomyces cerevisiae is a two-component regulator involved in osmotolerance. Phosphorylation of Sln1p leads to inhibition of the Hog1 mitogen-activated protein kinase osmosensing pathway. We have discovered a second function of Sln1p by identifying recessive activated alleles (designated nrp2) that regulate the essential transcription factor Mcm1. nrp2 alleles cause a 5-fold increase in the activity of an Mcm1-dependent reporter, whereas deletion of SLN1 causes a 10-fold decrease in reporter activity and a corresponding decrease in expression of Mcm1-dependent genes. In addition to activating Mcm1p, nrp2 mutants exhibit reduced phosphorylation of Hog1p and increased osmosensitivity suggesting that nrp2 mutations shift the Sln1p equilibrium toward the phosphorylated state. Two nrp2 mutations map to conserved residues in the receiver domain (P1148S and P1196L) and correspond to residues implicated in bacterial receivers to control receiver phosphorylation state. Thus, it appears that increased Sln1p phosphorylation both stimulates Mcm1p activity and diminishes signaling through the Hog1 osmosensing pathway.

Flow dynamics through spinal needles

We examined the flow pattern produced when liquid dye was actively injected into a fluid medium at various flows through five different commonly used spinal needles. At all flows, the Whitacre-type needles produced a directional stream exiting at an angle from the longitudinal axis. At intermediate rates the stream developed tracks which disappeared at faster rates. The Quincke needle always produced an undeviated stream of dye and did not form tracks at any flow rate. When a perspex plate (representing the spinal cord) was interposed in front of the needle, the dispersion of dye was always unidirectional from the Whitacre needle and bidirectional from the Quincke needle. The dye adhered to the surface of the plate as a concentrated film at slow rates and at faster rates it dispersed turbulently for both types of needle.

Isolation and analysis of the yeast TEA1 gene, which encodes a zinc cluster Ty enhancer-binding protein

A genetic screen for mutants that affect the activity of internal regulatory sequences of Ty retrotransposons led to the identification of a new gene encoding a DNA-binding protein that interacts with the downstream enhancer-like region of Ty1 elements. The TEA1 (Ty enhancer activator) gene sequence predicts a protein of 86.9 kDa whose N terminus contains a zinc cluster and dimerization motif typical of the Gal4-type family of DNA-binding proteins. The C terminus encodes an acidic domain with a net negative charge of -10 and the ability to mediate transcriptional activation. Like other zinc cluster proteins, purified Tea1 was found to bind to a partially palindromic CGGNxCCG repeat motif located in the Ty1 enhancer region. The Ty1 Tea1 binding site has a spacing of 10 and is located near binding sites for the DNA-binding proteins Rap1 and Mcm1. Analysis of the phenotype of tea1 deletion mutants confirmed that the TEA1 gene is required for activation from the internal Ty1 enhancer characterized in this study and makes a modest contribution to normal Ty1 levels in the cell. Hence, Tea1, like Rap1, is a member of a small family of downstream activators in Saccharomyces cerevisiae. Further analysis of the Tea1 protein and its interactions may provide insight into the mechanism of downstream activation in yeast cells.

Skin conductance responses in patients sedated with midazolam or propofol

We have measured the skin conductance response under resting conditions and to innocuous auditory stimuli in 45 patients receiving midazolam (group M), propofol (group P) or no sedative drug (group ND) before minor hand surgery under local anaesthesia. Administration of the sedative drugs was titrated to the end-point of slurring of speech and ptosis. The mean dose of midazolam was 0.06 (SD 0.01) mg kg-1 and the mean infusion rate of propofol was 2.2 (0.39) mg kg-1 h-1. Subjective ratings of anxiety and sedation were measured using visual analogue scales. These were similar in groups M and P and significantly different from those reported by group ND (P = 0.001-0.005). However, measures of skin conductance in group M were significantly lower than in group P (P = 0.002-0.013) and group ND (P = 0.004-0.016). These measures were similar in groups P and ND. Skin conductance measures were related significantly to anxiety scores only in groups M and ND (P < 0.05). We conclude that skin conductance is not a non-specific index of sedative-anxiolytic action and therefore is not useful in comparative studies of anxiolytic drugs that exert their effects by different pharmacological mechanisms.

Skin conductance responses to auditory stimuli and anticipatory responses before venepuncture in patients premedicated with diazepam or morphine

We have measured the skin conductance response to innocuous auditory stimuli and the anticipatory response before venepuncture in 45 patients receiving diazepam, morphine or no premedication before general anaesthesia. Subjective ratings of anxiety and sedation were measured using visual analogue scales. Skin conductance was less in subjects receiving diazepam than in the other groups, and the pattern of change of skin conductance in this group indicated superior adaptation to the environment during presentation of the innocuous stimuli compared with the other groups. After warning of venepuncture there was a large increase in skin conductance in all groups. There was a significant relationship between anxiety and skin conductance in unpremedicated patients and those receiving diazepam.

Towards a standardized anaesthetic state using isoflurane and morphine

In 34 patients undergoing major surgery, the inspired isoflurane concentration was adjusted by a control system designed to maintain systolic arterial pressure at a predetermined value. An empirical rule allowed additional morphine administration if the demand of the system for isoflurane was excessive. Satisfactory control of systolic arterial pressure was achieved in 31 patients and the anaesthetic state was clinically acceptable to an independent observer; no awareness was reported and the mean recovery time was 9.6 min. In these patients, control of systolic arterial pressure produced a pattern of clinical signs recognizable as general anaesthesia.

Oxford Optronix MPM 3S: a clinical assessment of a microvascular perfusion monitor

The Oxford Optronix MPM 3S is a new microvascular perfusion monitor which is promoted as a device for use in the operating theatre. It uses a semiconductor laser diode and applies the Doppler principle to derive a semi-quantitative estimation of microvascular flow. We assessed this instrument with eight healthy volunteers who each performed eight different orthostatic arm manoeuvres while forearm skin blood flow was monitored. The different manoeuvres caused statistically significant changes in the instrument's reading which generally were consistent with expected changes in blood flow. The monitor also was assessed in the theatre environment with four anaesthetized patients. It proved easy to use, and was not subject to electrical interference from other equipment including short-wave diathermy. The major practical limitation of the technique is the semi-quantitative nature of the measurement. The instrument appears to have potential clinical uses in plastic and vascular surgery.

Towards a standardized anaesthetic state using enflurane and morphine

General anaesthesia was maintained in 22 patients undergoing major surgery using a proportional-plus-integral control system. The system automatically adjusted the dose of enflurane according to the systolic arterial pressure (SAP). Additional morphine was administered if the system's demand for enflurane exceeded preset limits. In 21 patients, satisfactory control of SAP was achieved and anaesthesia was clinically adequate; no awareness was reported and the mean recovery time was 6.7 min (SD 3.5 min).

Nitrous oxide and formiminoglutamic acid: excretion in surgical patients and anaesthetists

We have investigated the possible toxicity of nitrous oxide on vitamin B12 and its sequelae upon folic acid metabolism using the urine formiminoglutamic acid excretion test, an index of the functional state of folate metabolism. Ten control subjects not exposed to nitrous oxide and five patients receiving limb surgery under local anaesthesia excreted normal amounts of formiminoglutamic acid in urine for 6 days. Fifty patients received nitrous oxide anaesthesia for similar surgery and, of these, 22 had a dose-dependent increase in excretion on the first 2 days after operation. There were large individual variations. Exposure to 70% nitrous oxide appeared to cause abnormal metabolism of folate when exposure was greater than 90 min. Ten anaesthetists demonstrated normal excretion of formiminoglutamic acid; their exposure to nitrous oxide was typical of that in other studies of theatre environmental pollution.

Automatic control of neuromuscular block with atracurium

We have developed and tested a system for providing automatic control of neuromuscular block with atracurium. The degree of neuromuscular block was monitored in the small muscles of the hand using a Datex Relaxograph, and the signal was used as the controlled variable for a proportional plus integral controller. A preloaded integral was used to shorten the period of stabilization. The system was tested in 36 patients undergoing surgery and found to produce stable block. For a target T1 of 20% of control value, the mean block was 18.7 (SD 1.3) % of baseline T1 and the mean consumption of atracurium was 5.39 (SD 1.23) micrograms kg-1 min-1. The block was sufficiently stable to act as a background for studies of pharmacological and physiological interactions with atracurium.

Occupational exposure to nitrous oxide in four hospitals

Diffusive samplers were used to measure the exposure of the anaesthetist, anaesthetic assistant and circulating nurse to nitrous oxide in every operating theatre of four Glasgow hospitals. Each theatre was surveyed over 1 or 2 weeks; samples were taken during every operating session. The exposures were in general surprisingly high. The anaesthetist's exposure was greater than ppm on about half the occasions. The study underlines the need for theatre ventilation systems and scavenging equipment to be properly maintained and for scavenging facilities to be used effectively. It is concluded that regular monitoring of staff exposures is required to check the effectiveness of antipollution measures.

Dependence of the output of a halothane vaporizer on thymol concentration

The effect of thymol accumulation inside a Fluotec 3 vaporizer on the concentration of halothane delivered by the vaporizer was investigated. The vaporizer output was reduced progressively as the thymol concentration increased, but the reduction was less than that predicted by Raoult's Law. A reduction of 5% in output required an increase in thymol concentration of a factor of 650 compared to the concentration in fresh halothane, while a reduction of 10% required a 1100-fold increase in thymol concentration. The equilibration of the thymol from the wicks throughout the vaporizing chamber was very slow after the vaporizer was drained and filled with fresh halothane; the half-time was 2.7 days.

Long-term performance of Tec vaporizers. Basis for a rational maintenance policy

We reviewed the maintenance records of Tec vaporizers which had been in clinical use for up to 4 years. Tec 4s and Enfluratec 3s were found to be extremely reliable, but Fluotec 3s suffered progressively from mechanical and calibration problems. Their most recurrent fault was sticking valves caused probably by thymol crystallizing on the valve faces. This fault did not occur with Fluotec 4s, which are designed to prevent liquid agent reaching the valve surfaces. We found, in a study of the effects of thymol accumulation, that only occasional draining of a Fluotec vaporizer is required to keep thymol concentration below the level at which its output is reduced. We conclude that, if regular field calibration checks are carried out as a safety measure, the service interval for Tec vaporizers could be extended beyond Ohmeda's present recommendation of one year.

Measurement of arterial pressure using catheter-transducer systems. Improvement using the Accudynamic

The dynamic performance of arterial manometers depends upon the values of the natural frequency fo and the damping factor beta. Satisfactory reproduction of all arterial waveforms requires that fo should be greater than about 13 Hz; for an fo of 13 Hz, beta should have a value of 0.5, but, as fo increases, an increasing range of beta values is permissible. We measured fo and beta for two pressure transducers (Gould P23 Statham and Gould Disposable) in combination with Portex or Gould catheter tubing of lengths varying from 100 cm to 300 cm. All combinations were considerably underdamped, with the best having an fo of 30 Hz and a beta of 0.1. We also investigated the performance of a commercial device, the Accudynamic, designed to allow beta to be increased without affecting fo. We found that the Accudynamic worked well, allowing acceptable performance to be obtained from the Gould Disposable transducer with catheters up to 200 cm in length.

A vaporizer controller

A Cyprane Enfluratec 3 vaporizer has been modified so that it can be operated under computer control. Details are given of construction and of safety precautions employed.

Tax Equity and Fiscal Responsibility Act of 1982: an incentive to improve productivity in health care

The productivity incentives of TEFRA are compared, using a sample that includes ten patients, four on Medicare and the remainder being either private pay patients or patients covered by commercial insurance. The effect of a ten percent increase or decrease in productivity on Medicare reimbursement before and after TEFRA is examined.

Exposure of midwives to nitrous oxide in four hospitals

The exposure of midwives to nitrous oxide in four hospitals was measured with personal samplers. In three of the four hospitals the average exposure was not significantly less than 100 parts per million (ppm). In one hospital the average exposure was 360 ppm; this was reduced by a factor of about 2.5 when a trial scavenging system was used. Differences in working practices and in the layout, size, and ventilation of the labour suites contributed to the observed differences in average exposure. Midwives and other staff working in the labour room are potentially at risk from excessive occupational exposure to nitrous oxide.

A critical appraisal of a rapid radiographic method of determining total lung capacity

We have demonstrated that the total lung capacities of normal caucasian adults, can be satisfactorily estimated by means of a regression equation derived from a single set of three measurements taken from a specially exposed plain X-ray film of the chest. However, these equations differ from those found by workers who have studied patients with lung disease. It is concluded from this that different regression equations are to be expected for normal and diseased lungs, and that, the appropriate equation will depend not only on the presence of disease, but also on its type and severity. It is also concluded that the rapid radiographic method of estimating total lung capacity can make little contribution to the diagnostic assessment of lung disease. However, the regression equations appropriate to particular ethnic groups could be used to measure TLC in normal subjects rapidly and inexpensively in places where specialised respiratory equipment and trained personnel are lacking.

A static calibration method for the gas chromatographic determination of per cent concentrations of volatile anaesthetic agents

A method is described for preparing static standards of per cent concentrations of volatile anaesthetic agents, that is designed to minimize adsorptive losses in the container used for the standards. The extent to which this aim has been realized was investigated for atmospheres of halothane, enflurane and isoflurane, both by monitoring the relative concentration within the container over a period of 30 min after the standard was prepared, and by measuring the absolute concentration of the volatile agents. Gas chromatography was used for both sets of measurements, with liquid standards being used for the absolute measurements. No discernible loss of volatile agent occurred over the 30-min period, and the measured concentrations agreed closely with the predicted values. The standard mixtures prepared by the method were suitable for calibrating a gas chromatograph, and allowed accurate determinations of volatile anaesthetics to be made. The relative standard error of the predicted concentration for a single standard mixture was less than 0.5%, and the calibration accuracy could be further improved by taking the mean chromatograph response to several standard mixtures prepared in succession.

An evaluation of the Datex Normac anaesthetic agent monitor

A new monitor for volatile anaesthetics, the Datex Normac, was assessed in the laboratory and operating theatre. The instrument had a warm up time of 90 minutes from cold, but only 5 minutes from standby. Zero drift was less than 0.01% over 7 hours, and repeated measurements of gain showed a coefficient of variation of less than 1%. However, gain drift of 6% occurred when the instrument was switched off between periods of use. Signal noise was less than 0.02 vol% on a new instrument, but was about six times greater on an instrument that had been in use for a year. The response time of 550 ms is short enough to allow breath by breath monitoring. When the instrument was calibrated on the enflurane setting, measurements made on the enflurane, halothane and isoflurane settings were accurate to within 6% of the reading. This is satisfactory for clinical purposes, but not for more demanding applications. Calibration canisters are available, and two that we tested were accurate to better than 0.1 vol%. Nitrous oxide, carbon dioxide and water vapour have very small effects on the monitor. The instrument provided trouble-free monitoring in theatre.

Nitrous oxide and wound healing

Following a paravertebral surgical incision, mature, female rats under ether anaesthesia were exposed to either 3% nitrous oxide, continuously for 48 h, or 50% nitrous oxide, 4 h each day for 7 days. For each exposure group, a similar number of rats was exposed to atmospheres containing no nitrous oxide. Wound healing was assessed by measurement of the breaking strengths of wound samples. No statistically significant influence on breaking strength could be attributed to nitrous oxide following either exposure sequence.

The evacuated canister method of personal sampling. An assessment of its suitability for routine monitoring of operating theatre pollution

Although there is a recognised need for routine monitoring of the exposure of operating theatre staff to waste anaesthetic gases, there is as yet no standard method for carrying out such measurements. We have assessed a commercial version of one proposed sampling system--the evacuated canister--by testing it in the laboratory and also using it to carry out pilot surveys in operating theatres. We encountered many difficulties in using the system; some of these were caused by design faults in the commercial equipment, but others are inherent in the concept of using an evacuated canister for personal sampling.

Medishield AGS system and servo 900 ventilators. Investigation and remedy of hazard caused by defeat of 'low expired minute volume' alarm

The use of the new Medishield anaesthetic gas scavenging system with ventilators in the Siemens-Elema Servo 900 series was investigated. It was discovered that this combination of equipment creates the hazard that a disconnexion in the patient breathing system may not be detected by the ventilator alarm. This happens because the suction generated by the scavenging system draws a considerable flow of room air through the expiratory system of the ventilator when a disconnexion occurs. Possible solutions to the problem were investigated, and it was discovered that the problem can be overcome by applying a small amount of positive end-expiratory pressure to counteract the suction from the scavenging system.

Calibration atmosphere generator for operating theatre pollution studies. A system for the controlled production of trace concentrations of inhalation anaesthetics

The design and performance of an apparatus for producing accurately known trace concentrations of anaesthetic agents in air is described. The generator was constructed to facilitate the testing and calibration of equipment used in measuring the personal exposure of operating theatre staff to waste anaesthetic gases, and operates on the principle of the controlled injection of the pure anaesthetic agent into a diluting air stream. It is compact, simple to construct and easy to operate. Furthermore, it has a short stabilization time and can provide a wide range of predetermined concentrations with very good repeatability. It appears to be considerably more flexible than systems which have been described previously and should be of interest to groups involved in monitoring pollution in the operating theatre.

Assessment of the design and performance of the Sage syringe pump model 341A, with particular reference to its accuracy and stability

Consideration of the timing circuitry employed in the Sage pump model 341A indicates that the pump's performance will be strongly affected by component tolerances, and our measurements have confirmed this impression. Thus, delivered flow rates may deviate considerably from those indicated on the calibration chart; our instrument was about 10% slow at all settings. For many applications it will be necessary to carry out a full calibration procedure, which should be repeated following any repairs to the electronic circuitry. The pump also suffered from drift at certain settings because an inappropriate component had been used in the timing circuitry. These findings will also apply to the Sage pump models 240A and 242A, which employ similar timing circuitry to the 341A. When precautions are taken to overcome these problems, the pump's performance is satisfactory for both clinical use and some laboratory applications.

The effects of whole-body irradiation on the serum levels and kinetics of thyroid hormones in rats

The effects of a single whole-body dose of X-rays on the serum levels and kinetics of thyroid hormones in rats were studied. The influence of radiation-induced anorexia was monitored by using pair fed control groups. A dose of 800 rad caused a reduction in T4 levels and 750 rad had a similar effect on T3; in each case the control group showed a smaller reduction. The kinetic results indicated that, in the control groups, the early reduction in hormone concentrations was caused, by a change in the distribution of the hormone; however, the continuing reduction in hormone levels in the irradiated rats appeared to results from decreased production. The results suggest that the thyroid system may play an active part in the early metabolic changes which follow whole-body irradiation.

The value of provocative and acute urography in patients with intermittent loin pain

Twenty-two patients with intermittent loin pain thought to be typical of primary pelvic hydronephrosis but with normal appearances at standard excretion urography were subjected to diuretic urography using Frusemide-induced diuresis. If this was normal, acute urography was performed when the patient had pain. Abnormal appearances were shown in only 15 patients. In 4, only the erect films revealed the hydronephrosis. Dilatation occurred in response to a diuretic load in 9 and the abnormality was shown at the time of an attack of pain in 4. The hydronephrosis was shown only during the attack of pain in 2, a diuretic urogram having been normal. In 2 patients the nephrographic signs of acute obstruction were shown to be due to occlusion of the pelvi-ureteric junction at the time of an attack of pain. The importance of sequential examination, the value of erect films and acute urography are stressed.

On Partialing A Simplex Out Of Binary Data

Using four illustrative data sets, the procedure developed by Horst for partialing a simplex out of a binary data matrix is shown to result in poorer factor recovery than if the procedure were not applied to the data set.

Cumulative radiation effect. Part VI: simple nomographic and tabular methods for the solution of practical problems

In five previous papers, the concept of the Cumulative Radiation Effect (CRE) has been presented as a scale of accumulative sub-tolerance radiation damage. The biological effect generated in normal connective tissue by fractionated or continuous radiation therapy given in any temporal arrangement is described by the CRE on a unified scale of assessment, so that a unique value of the CRE describes a specific level of radiation effect. The basic methods of evaluating CREs were shown in these papers to facilitate a full understanding of the fundamental aspects of the CRE-system, but these methods can be time-consuming and tediuous for complex situations. In this paper, simple nomographic and tabular methods for the solution of practical problems are presented. An essential feature of solving a CRE problem is firstly to present it in a concise and readily appreciated form, and, to do this, nomenclature is introduced to describe schedules and regimes as compactly as possible. Simple algebraic equations are derived to describe the CRE achieved by multi-schedule regimes. In these equations, the equivalence conditions existing at the junctions between schedules are not explicit and the equations are based on the CREs of the constituent schedules assessed individually without reference to their context in the regime as a whole. This independent evaluations of CREs for each schedule results in a considerable simplification in the calculation of complex problems. The calculations are further simplified by the use of suitable tables and nomograms, so that the mathematics involved is reduced to simple arithmetical operations which require at the most the use of a slide rule but can be done by hand. The order of procedure in the presentation and calculation of CRE problems can be summarised in an evaluation procedure sheet. The resulting simple methods for solving practical problems of any complexity on the CRE-system are demonstrated by a number of examples.

Cumulative radiation effect. Part VII: computer calculations and applications in clinical practice

In five previous papers, the concept of the Cumulative Radiation Effect (CRE) has been presented as a scale of accumulative sub-tolerance radiation damage. The biological effect generated in normal connective tissue by fractionated or continuous radiation therapy given in any temporal arrangement is described by the CRE on a unified scale of assessment, so that a unique value of the CRE describes a specific level of radiation effect. The basic methods of evaluating CREs were shown in the papers to facilitate a full understanding of the fundamental aspects of the CRE-system, but these methods can be time-consuming and tedious for complex situations. In the previous papers in this series, one way of overcoming the difficulties in evaluating CRE problems was presented in simple nomographic and tabular methods for the solution of practical problems. An alternative way of overcoming the difficulties in the evaluation of CRE problems is to use computers and it is the purpose of this paper to outline computer calculations and applications in clinical practice in connection with the CRE-system. In a general appraisal of the applications of computers to the CRE-system, the various problems encountered in clinical radiotherapy are categorised into those involving the evaluation of a CRE at a point in tissue and those involving the calculation of CRE distributions. As a general guide, the computer techniques adopted at the Glasgow Institute of Radiotherapeutics for the solution of CRE problems are presented, and consist basically of a package of three interactive programs for point CRE calculations and a Fortan program which calculates CRE distributions for iso-effect treatment planning. Many examples are given to demonstrate the applications of these programs, and special emphasis has been laid on the problem of treating a point in tissue with different doses per fraction on alternate treatment days. The wide range of possible clinical applications of the CRE-system has been outlined and described under the categories of routine clinical applicatons, retrospective and prospective surveys of patient treatment, and experimental and theoretical research. Some of these applications such as the results of surveys and studies of time optimisation of treatment schedules could have far-reaching consequences and lead to significant improvements in treatment and cure rates with the minimum damage to normal tissue.

Metastatic Crohn's disease

Metastatic Crohn's disease is a term used to describe a granulomatous reaction occurring in flexures, and separated from the affected areas of the gastro-intestinal tract by normal skin. Previous reports refer to such lesions affecting the groins, the male genitalia, a flexure on the anterior abdominal wall of an obese patient, and submammary regions. A further case, in which the retro-auricular areas are involved, is presented.

Characteristics of bacteria isolated by the anaerobic roll-tube method from cheeses and ground beef

In this study the methods of Hungate were used to quantitate the anaerobic bacteria present in commercially available ground beef, cheddar cheese, and German hand cheese. Of 235 anaerobic roll-tube isolates from ground beef and German hand cheese, all were facultative anaerobes. Of 213 anaerobic roll-tube isolates from cheddar cheese, 91% were facultative anaerobes and 9% were obligate anaerobes. Using results of biochemical tests, 14 or the 17 obligately anaerobic isolates from cheddar cheese were Propionibacterium acnes, two were strains of Propionibacterium that could not be speciated, and one was tentatively identified as a strain of Streptococcus evolutus. Obligate anaerobes were estimated to be present in the cheddar cheese at a level of about 10(6)/g. The possible significance of these levels of P. acnes in nonsterile foods is discussed.

Cumulative radiation effect. part IV. Normalisation of fractionated and continuous therapy - area and volume correction factors

In three previous papers, a scale of accumulated sub-tolerance radiation damage, the Cumulative Radiation Effect (CRE), was described for fractionated treatment regimes and continuous radiation therapy from both long-lived and short-lived sources. This scale provides a means of assessing and comparing the biological effects of various treatments. In this paper, it is intended to further the scope of application of the CRE-system by describing in detail the normalisation between the assessments of fractionated and continuous therapy. To do this, it is necessary to consider area and volume correction factors, whose roles are to modify the values of uncorrected CREs so that a specific biological effect, regardless of the area or volume treated, is described by a unique value of the corrected CRE. The problem arising when the CRE achieved by a treatment regime is not constant over a volume is briefly discussed and a simple hypothesis is proposed which may stimulate interest in this problem. The establishment of a normalisation procedure between fractionated treatment regimes and continuous radiation therapy, which is the primary aim of this paper, serves to integrate the concept of the CRE into a unified system of assessment of biological damage, so that a unique value of the CRE describes a specific level of biological damage regardless of the area or volume treated, or the time course of administration of the radiation employed.