Comparison of number of air-borne bacteria in operating rooms with turbulent mixing ventilation and unidirectional airflow when using reusable scrub suits and single-use scrub suits

INTRODUCTION

Low counts of air-borne bacteria in the operating room is a mean to prevent surgical site infection.

AIM

To investigate levels of air-borne bacteria during surgical procedures in two operating rooms with turbulent mixing ventilation (TMV) and unidirectional airflow (UDAF), both with an air supply of 2600 L/s, when staff used either reusable scrub suits made from a mixed material (dry penetration ≤ 300 CFU) or single-use scrub suits made from polypropylene (dry penetration ≤ 100 CFU).

MATERIAL AND METHODS

In the TMV-room colony forming units (CFU) per m³ air was measured during eight procedures with staff wearing reusable scrub suits and seven procedures with single-use scrub. In the UDAF-room CFU/m³ air was measured during seven procedures with staff wearing reusable scrub suits.

FINDINGS

Mean values of CFU/m³ air were 1.3 to 10.8 in the TMV-room with staff dressed in reusable scrub suits and 0.8 to 4.0 with staff dressed in single-use scrub suits (p < 0.01). Mean values of CFU/m³ air were 0.2 to 4.5 in the UDAF-room with staff dressed in reusable scrub suits. The difference obtained with reusable scrub suits in the two rooms was significant (p < 0.01).

CONCLUSIONS

The mode of ventilation affects the CFU-levels when staff is dressed in less occlusive scrub suits despite a high air supply. It is possible to decrease the CFU-levels in a TMV-room by using scrub suits made from a tight material thus reaching the same levels that are achieved by less protective scrub suits in a UDAF-room.

Laparoscopic lavage for perforated diverticulitis in the LapLav study: population-based registry study

BACKGROUND

The standard treatment for Hinchey III perforated diverticulitis with peritonitis was resection with or without a stoma, but recent trials have shown that laparoscopic lavage is a reasonable alternative. This registry-based Swedish study investigated results at a national level to assess safety in real-world scenarios.

METHODS

Patients in Sweden who underwent emergency surgery for perforated diverticulitis between 2016 and 2018 were studied. Inverse probability weighting by propensity score was used to adjust for confounding factors.

RESULTS

A total of 499 patients were included in this study. Laparoscopic lavage was associated with a significantly lower 90-day Comprehensive Complication Index (20.9 versus 32.0; odds ratio 0.77, 95 per cent compatibility interval (c.i.) 0.61 to 0.97) and overall duration of hospital stay (9 versus 15 days; ratio of means 0.84, 95 per cent c.i. 0.74 to 0.96) compared with resection. Patients had 82 (95 per cent c.i. 39 to 140) per cent more readmissions following lavage than resection (27.2 versus 21.0 per cent), but similar reoperation rates. More co-morbidity was noted among patients who underwent resection than those who had laparoscopic lavage.

CONCLUSION

Laparoscopic lavage is safe in routine care beyond trial evaluations.

European Society of Coloproctology: guidelines for the management of diverticular disease of the colon

AIM

The goal of this European Society of Coloproctology (ESCP) guideline project is to give an overview of the existing evidence on the management of diverticular disease, primarily as a guidance to surgeons.

METHODS

The guideline was developed during several working phases including three voting rounds and one consensus meeting. The two project leads (JKS and EA) appointed by the ESCP guideline committee together with one member of the guideline committee (WB) agreed on the methodology, decided on six themes for working groups (WGs) and drafted a list of research questions. Senior WG members, mostly colorectal surgeons within the ESCP, were invited based on publication records and geographical aspects. Other specialties were included in the WGs where relevant. In addition, one trainee or PhD fellow was invited in each WG. All six WGs revised the research questions if necessary, did a literature search, created evidence tables where feasible, and drafted supporting text to each research question and statement. The text and statement proposals from each WG were arranged as one document by the first and last authors before online voting by all authors in two rounds. For the second voting ESCP national representatives were also invited. More than 90% agreement was considered a consensus. The final phrasing of the statements with < 90% agreement was discussed in a consensus meeting at the ESCP annual meeting in Vienna in September 2019. Thereafter, the first and the last author drafted the final text of the guideline and circulated it for final approval and for a third and final online voting of rephrased statements.

RESULTS

This guideline contains 38 evidence based consensus statements on the management of diverticular disease.

CONCLUSION

This international, multidisciplinary guideline provides an up to date summary of the current knowledge of the management of diverticular disease as a guidance for clinicians and patients.

Children aged 0-16 admitted to Swedish intensive care units and paediatric intensive care units showed low mortality rates

AIM

This study described the basic characteristics of children aged 0-16 years who were treated in intensive care units (ICUs) and paediatric ICUs (PICUs), compared their outcomes and examined any causes of death.

METHODS

This was a retrospective cohort study of admissions to 74 ICUs and three PICUs in Sweden that were recorded in the Swedish Intensive Care Registry from January 1, 2008 to December 31, 2012.

RESULTS

We retrieved data on 12 756 children who were admitted 17 003 times. The case mix differed between the ICUs, which were mainly admissions for injuries, accidents and observation, and PICUs, which were mainly admissions for malformations, genetic abnormalities and respiratory problems (p < 0.001). The median stays in the ICUs and PICUs were 1.4 and 3.5 days (p < 0.001), respectively. The respective crude mortality rates were 1.1% and 2.0, and the Paediatric Index of Mortality version 2 standardised mortality ratios were 0.43 and 0.50. None of these differences were significant. Most deaths were within 24 hours: About 57% in the ICUs, mainly from brain anomalies, and 13% in the PICUs, mainly from circulatory problems.

CONCLUSION

Sweden had a low mortality rate in both ICUs and PICUs and the children admitted to these two types of unit differed.

Low dose of hydroxyethyl starch impairs clot formation as assessed by viscoelastic devices

OBJECTIVE

High doses of the synthetic colloid hydroxyethyl starch (HES) used for plasma expansion have been associated with impaired haemostasis and hypocoagulation. Less is known about effects on clot formation in the low haemodilutional range (< 40%). This study evaluated the effects of low haemodilution with HES and albumin on coagulation using two different viscoelastic methods.

METHODS

Clot formation was studied in vitro in healthy donor blood after 10% and 30% haemodilution with 60 g/L HES 130/0.4 or 50 g/L albumin with free oscillation rheometry (FOR) and rotational thromboelastography.

RESULTS

Clotting time was not significantly affected at 10% haemodilution but was prolonged with both substances at 30% dilution (p < 0.01-0.001). The effect was significantly more pronounced with HES than with albumin. The elasticity of the clot was slightly reduced at 10% dilution with albumin, more pronounced at 10% dilution with HES (p < 0.05), further reduced at 30% dilution with albumin and to a still greater extent at 30% dilution with HES (p < 0.05). With albumin the functional activity of fibrinogen was not reduced in excess of the dilutional effect. HES in contrast produced a further reduction in clot elasticity than caused by mere dilution at both 10% and 30% dilutions (p < 0.001).

CONCLUSIONS

There is an adverse effect on clot formation even at low grade haemodilution with both albumin and HES. The effect on coagulation is significantly more pronounced with HES than with albumin.

Late-onset neonatal sepsis, risk factors and interventions: an analysis of recurrent outbreaks of Serratia marcescens, 2006-2011

BACKGROUND

Between 2006 and 2011, 11 patients with Serratia marcescens sepsis and 47 patients colonized due to the spread of various clones were observed. These recurrent clusters brought about interventions to reduce spread between patients.

AIM

To evaluate the effect of stepwise interventions to prevent S. marcescens colonization/sepsis and to analyse risk factors for late-onset sepsis (LOS).

METHODS

An open retrospective observational study was performed to evaluate the interventions. A retrospective case-control study was performed to analyse the risk factors for LOS.

FINDINGS

S. marcescens sepsis and colonization decreased after the stepwise adoption of hygiene interventions. Low gestational age, low birth weight, indwelling central venous or umbilical catheter, and ventilator treatment were identified as risk factors for LOS. Compliance with basic hygiene guidelines was the only intervention monitored continuously from late 2007. Compliance increased gradually to a steady high level in early 2009. There was a decrease in S. marcescens LOS, clustering after the second quarter of 2008. After the first quarter of 2009, S. marcescens colonization decreased.

CONCLUSION

It was not possible to identify the specific effects of each intervention, but it is likely that an update of the hospital's antibiotic policy affected the occurrence of S. marcescens LOS. The delayed effect of interventions on S. marcescens colonization was probably due to the time it takes for new routines to have an effect, illustrated by the gradual increase in compliance with basic hygiene guidelines.

Effects of food or sleep deprivation during civilian survival training on clinical chemistry variables

OBJECTIVE

To describe clinical chemistry and weight changes after short-term food or sleep deprivation or multiple deprivations during civilian survival training.

METHODS

Data from one baseline-controlled two-period crossover study designed to compare sleep deprivation for up to 50 hours with food deprivation for up to 66 hours (n = 12) and data from regular multiple-deprivations survival training comparing participants (n = 33) with nondeprived instructors (n = 10).

RESULTS

Food deprivation was associated with decreased body weight, blood glucose, serum triglycerides, sodium, chloride, and urine pH, and there were increases in blood and urine ketones and serum free fatty acids. Sleep deprivation was associated with a minor decrease in hemoglobin and erythrocyte particle count and volume fraction and an increase in leukocytes.

CONCLUSIONS

The clinical chemistry and body weight changes associated with food deprivation were qualitatively similar to those observed in fasting obese patients but developed quicker in the survival training setting. Sleep deprivation had few effects on the clinical chemistry profile except for hematological variables. Physicians evaluating clinical chemistry data from patients subjected to short-term food or sleep deprivation should take the physiological state into account in their assessment.

The Effect of Mineral Variability on the Solubility of Some Actinides: an Uncertainty Analysis

The use of computer simulations in the performance assessment for a repository for spent nuclear fuel, are in many cases the only method to get information on how the rock-repository system will work. One important factor is the solubility of the elements released if the repository is breached. This solubility may be determined experimentally or simulated. Ifit is simulated, several factors such as thermodynamical uncertainties will affect the reliability of the results. If these uncertainties are assumed to be small, the composition of the water used in the calculations may play a major part in the uncertainties in solubility. The water composition, in tum, is either determined experimentally or calculated through water-rock interactions. Thus, if the mineral composition of the rock is known, it is possible to foresee the water composition. However, in most cases a determination of the rock composition is made from drilling cores and is thus quite uncertain. Therefore, if solubility calculations are to be based on water properties calculated from rock-water interactions another uncertainty is introduced. This paper is focused on uncertainty and sensitivity analysis of rock-water interaction simulations and the uncertainties thus obtained are propagated through a program making uncertainty and sensitivity analysis of the solubility calculations. In both cases the latin hypercube sampling technique have been used. The results show that the solubilities are in most cases log normal distributed while the different elements in the simulated groundwater in some cases diverge significantly from such a distribution. The numerical results are comforting in that the uncertainty intervals of the solubilities are rather small, i.e. up to 30%.

A human vascular model based on microdialysis for the assessment of the vasoconstrictive dose-response effects of norepinephrine and vasopressin in skin

OBJECTIVE

Microdialysis enables drug delivery in the skin and simultaneous measurement of their effects. The present study aimed to evaluate dose-dependent changes in blood flow and metabolism during microdialysis of norepinephrine and vasopressin.

METHODS

We investigated whether increasing concentrations of norepinephrine (NE, 1.8-59 μmol/L) and vasopressin (VP, 1-100 nmol/L), delivered sequentially in one catheter or simultaneously through four catheters, yield dose-dependent changes in blood flow (as measured using urea clearance) and metabolism (glucose and lactate).

RESULTS

We found a significant dose-dependent vasoconstriction with both drugs. Responses were characterized by a sigmoid dose response model. Urea in the dialysate increased from a baseline of 7.9 ± 1.7 to 10.9 ± 0.9 mmol/L for the highest concentration of NE (p < 0.001) and from 8.1 ± 1.4 to 10.0 ± 1.7 mmol/L for the highest concentration of VP (p = 0.037). Glucose decreased from 2.3 ± 0.7 to 0.41 ± 0.18 mmol/L for NE (p = 0.001) and from 2.7 ± 0.6 to 1.3 ± 0.5 mmol/L for VP (p < 0.001). Lactate increased from 1.1 ± 0.4 to 2.6 ± 0.5 mmol/L for NE (p = 0.005) and from 1.1 ± 0.4 to 2.6 ± 0.5 mmol/L for VP (p = 0.008). There were no significant differences between responses from a single catheter and from those obtained simultaneously using multiple catheters.

CONCLUSIONS

Microdialysis in the skin, either with a single catheter or using multiple catheters, offers a useful tool for studying dose response effects of vasoactive drugs on local blood flow and metabolism without inducing any systemic effects.

Implications for burn shock resuscitation of a new in vivo human vascular microdosing technique (microdialysis) for dermal administration of noradrenaline

INTRODUCTION

Skin has a large dynamic capacity for alterations in blood flow, and is therefore often used for recruitment of blood during states of hypoperfusion such as during burn shock resuscitation. However, little is known about the blood flow and metabolic consequences seen in the dermis secondary to the use vasoactive drugs (i.e. noradrenaline) for circulatory support. The aims of this study were therefore: to develop an in vivo, human microdosing model based on dermal microdialysis; and in this model to investigate effects on blood flow and metabolism by local application of noradrenaline and nitroglycerin by the microdialysis system simulating drug induced circulatory support.

METHOD

Nine healthy volunteers had microdialysis catheters placed intradermally in the volar surface of the lower arm. The catheters were perfused with noradrenaline 3 or 30 mmol/L and after an equilibrium period all catheters were perfused with nitroglycerine (2.2 mmol/L). Dermal blood flow was measured by the urea clearance technique and by laser Doppler imaging. Simultaneously changes in dermal glucose, lactate, and pyruvate concentrations were recorded.

RESULTS

Noradrenaline and nitroglycerine delivered to the dermis by the microdialysis probes induced large time- and dose-dependent changes in all variables. We particularly noted that tissue glucose concentrations responded rapidly to hypoperfusion but remained higher than zero. Furthermore, vasoconstriction remained after the noradrenaline administration implicating vasospasm and an attenuated dermal autoregulatory capacity. The changes in glucose and lactate by vasoconstriction (noradrenaline) remained until vasodilatation was actively induced by nitroglycerine.

CONCLUSION

These findings, i.e., compromised dermal blood flow and metabolism are particularly interesting from the burn shock resuscitation perspective where noradrenaline is commonly used for circulatory support. The importance and clinical value of the results obtained in this in vivo dermal model in healthy volunteers needs to be further explored in burn-injured patients.

Social integration: an important factor for health-related quality of life after critical illness

OBJECTIVES

To examine to what extent availability of social integration affects health-related quality of life (HRQoL) in former intensive care unit (ICU) patients and how it relates to corresponding findings in a general reference group.

DESIGN

Controlled, multicenter, prospective, explorative study.

SETTING AND PATIENTS

HRQoL data (SF-36) were collected from three combined medical and surgical ICUs in the south-east of Sweden. Social integration was assessed by the Availability of Social Integration (AVSI) instrument (seven questions related to the social interaction of the patient). As reference group, a random sample (n = 6,093) of people from the uptake area of the hospitals was used. Social integration (AVSI), HRQoL (SF-36), and comorbidity were examined also in the reference group.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

The level of social integration significantly affected HRQoL for the former ICU patients, whereas no such effect was seen for the general reference group. For the ICU patients, social integration affected HRQoL to a larger extent than age, sex, and the ICU-related factors examined, but to a lower extent than the pre-existing diseases.

CONCLUSIONS

For a comprehensive assessment of HRQoL in former ICU patients, it is mandatory to include the effect of social integration.

Pre-existing disease: the most important factor for health related quality of life long-term after critical illness: a prospective, longitudinal, multicentre trial

INTRODUCTION

The aim of the present multicenter study was to assess long term (36 months) health related quality of life in patients after critical illness, compare ICU survivors health related quality of life to that of the general population and examine the impact of pre-existing disease and factors related to ICU care on health related quality of life.

METHODS

Prospective, longitudinal, multicentre trial in three combined medical and surgical intensive care units of one university and two general hospitals in Sweden. By mailed questionnaires, health related quality of life was assessed at 6, 12, 24 and 36 months after the stay in ICU by EQ-5D and SF-36, and information of pre-existing disease was collected at the 6 months measure. ICU related factors were obtained from the local ICU database. Comorbidity and health related quality of life (EQ-5D; SF-36) was examined in the reference group. Among the 5306 patients admitted, 1663 were considered eligible (>24 hrs in the intensive care unit, and age >or= 18 yrs, and alive 6 months after discharge). At the 6 month measure 980 (59%) patients answered the questionnaire. Of these 739 (75%) also answered at 12 month, 595 (61%) at 24 month, and 478 (47%) answered at the 36 month measure. As reference group, a random sample (n = 6093) of people from the uptake area of the hospitals were used in which concurrent disease was assessed and adjusted for.

RESULTS

Only small improvements were recorded in health related quality of life up to 36 months after ICU admission. The majority of the reduction in health related quality of life after care in the ICU was related to the health related quality of life effects of pre-existing diseases. No significant effect on the long-term health related quality of life by any of the ICU-related factors was discernible.

CONCLUSIONS

A large proportion of the reduction in the health related quality of life after being in the ICU is attributable to pre-existing disease. The importance of the effect of pre-existing disease is further supported by the small, long term increment in the health related quality of life after treatment in the ICU. The reliability of the conclusions is supported by the size of the study populations and the long follow-up period.

Urea clearance: a new method to register local changes in blood flow in rat skeletal muscle based on microdialysis

SUMMARY

Increasing evidence suggests that local blood flow should be monitored during microdialysis (MD) as the recovery of analytes is affected by local blood flow. At present ethanol clearance is the standard technique for this purpose, but it is not functional at very low perfusion velocities. Here, we introduce a technique for MD whereby local tissue blood flow is recorded by the use of urea clearance (changes inflow/outflow concentration), in conjunction with measurements of tissue metabolism (glucose, lactate and puruvate). MD probes were inserted into the gracilis muscle of 15 rats and perfused with a medium containing urea (20 mmol l(-1)). Changes in muscle blood flow were made by addition of noradrenaline (5 microg ml(-1)) to the perfusion medium at two perfusion velocities (0.6 and 0.4 microl min(-1)). The clearance of urea from the perfusion medium was then calculated and examined in relation to the dose of noradrenaline and to the coexisting changes in extracellular metabolites. The results showed reproducible and dose-dependent changes in blood flow that were induced by noradrenaline. These were characterized by dose-dependent changes in the urea clearance as well as blood-flow-specific changes in the MD metabolic markers (reduction in glucose and increase in lactate). The sensitivity for blood flow changes as assessed by urea clearance (MD) was increased at 0.4 compared with the 0.6 microl min(-1) perfusion speed. The results indicate that inclusion of urea to the perfusion medium may be used to monitor changes in skeletal muscle blood flow at low perfusion velocities and in parallel assess metabolic variables with a high recovery (>90%).

Serotonin kinetics in patients with burn injuries: a comparison between the local and systemic responses measured by microdialysis-a pilot study

OBJECTIVES

To investigate serotonin (5HT) locally in burned and uninjured skin (intracutaneous) by microdialysis, and simultaneously record urinary and blood values in the same subjects. For comparison, serotonin values were also measured in skin of healthy controls.

DESIGN AND SETTING

An experimental study in burned patients with of more than 25% TBSA (total burn surface area) % in an 8-bed tertiary burns unit, serving about 3.5 million persons.

PATIENTS AND METHODS

Six subjects with a median TBSA% of 59% (range 33.5-90), and five healthy controls were examined by intracutaneous microdialysis of the skin.

RESULTS

5HT was increased in burned patients, compared with controls. This increase was tenfold in skin and was noted both in uninjured and burned skin. The highest values were recorded on day 1 (median 16.1nmol in uninjured and 9.5nmol in burned skin) and day 2 (15.6nmol in uninjured and 13.4nmol in burned skin). A rapid reduction was noted on day 3 (4.9nmol in uninjured and 3.8nmol in burned skin). The corresponding value for control subjects was 1.3nmol. The 5HT in blood was twice normal on day 2, and gradually reduced on days 3 and 4 (3189, 3035 and 2573nmol, respectively). Urinary 5HT concentrations were increased only on day 2 at 1755nmol and thereafter returned to the normal range on days 3 and 4 (1248 and 1344nmol, respectively).

CONCLUSIONS

We showed that microdialysis may be used in the critical care of burns, and local skin serotonin concentrations examined continuously for several days. The findings of significantly raised tissue serotonin concentrations, compared to that in blood and urine, suggests that serotonin may be important in local vascular control and formation of oedema.

Isoforms of alanine aminotransferases in human tissues and serum--differential tissue expression using novel antibodies

Serum alanine aminotransferase (ALT) is used as a clinical marker of hepatotoxicity. Two forms of ALT have been identified, ALT1 and ALT2, encoded by separate genes. The cellular and tissue distribution of the different ALT proteins has not been characterized in humans, and their relative contribution to serum is unknown. Here, we describe the development of novel isoenzyme specific ALT1 and ALT2 antibodies and the expression of the enzymes in human cells and organs. In normal human tissue, high expression of ALT1 was found in liver, skeletal muscle and kidney and low levels in heart muscle and not detectable in pancreas. High ALT2 reactivity was detected in heart and skeletal muscle, while no ALT2 expression was found in liver or kidney. Using immunohistochemistry, strong ALT1 reactivity was found in hepatocytes, renaltubular epithelial cells and in salivary gland epithelial cells, while ALT2 was expressed in adrenal gland cortex, neuronal cell bodies, cardiac myocytes, skeletal muscle fibers and endocrine pancreas. Immunoprecipitation using ALT antibodies on normal human serums showed ALT1 to be mainly responsible for basal ALT activity. Together, the results points to a differential expression of ALT1 and ALT2 in human organs and substantiate a need for investigations regarding the possible impacts on ALT measurements.

Microdialysis shows metabolic effects in skin during fluid resuscitation in burn-injured patients

INTRODUCTION

Established fluid treatment formulas for burn injuries have been challenged as studies have shown the presence of tissue hypoxia during standard resuscitation. Such findings suggest monitoring at the tissue level. This study was performed in patients with major burn injuries to evaluate the microdialysis technique for the continuous assessment of skin metabolic changes during fluid resuscitation and up to four days postburn.

METHODS

We conducted an experimental study in patients with a burn injury, as represented by percentage of total body surface area burned (TBSA), of more than 25% in a university eight-bed burns intensive care unit serving about 3.5 million inhabitants. Six patients with a median TBSA percentage of 59% (range 33.5% to 90%) and nine healthy controls were examined by intracutaneous MD, in which recordings of glucose, pyruvate, lactate, glycerol, and urea were performed.

RESULTS

Blood glucose concentration peaked on day two at 9.8 mmol/l (6.8 to 14.0) (median and range) and gradually declined on days three and four, whereas skin glucose in MD continued to increase throughout the study period with maximum values on day four, 8.7 mmol/l (4.9 to 11.0). Controls had significantly lower skin glucose values compared with burn patients, 3.1 mmol/l (1.5 to 4.6) (p < 0.001). Lactate from burn patients was significantly higher than controls in both injured and uninjured skin (MD), 4.6 mmol/l (1.3 to 8.9) and 3.8 mmol/l (1.6 to 7.5), respectively (p < 0.01). The skin lactate/pyruvate ratio (MD) was significantly increased in burn patients on all days (p < 0.001). Skin glycerol (MD) was significantly increased at days three and four in burn patients compared with controls (p < 0.01).

CONCLUSION

Despite a strategy that fulfilled conventional goals for resuscitation, there were increased lactate/pyruvate ratios, indicative of local acidosis. A corresponding finding was not recorded systemically. We conclude that MD is a promising tool for depicting local metabolic processes that are not fully appreciated when examined systemically. Because the local response in glucose, lactate, and pyruvate metabolism seems to differ from that recorded systemically, this technique may offer a new method of monitoring organs.

Computed tomography--a possible aid in the diagnosis of smoke inhalation injury?

Inhalation injury is an important contributor to morbidity and mortality in burn victims and can trigger acute lung injury and acute respiratory distress syndrome (ARDS) (1-3). Early diagnosis and treatment of inhalation injury are important, but a major problem in planning treatment and evaluating the prognosis has been the lack of consensus about diagnostic criteria (4). Chest radiographs on admission are often non-specific (5, 6), but indicators include indoor fires, facial burns, bronchoscopic findings of soot in the airways, and detection of carbon monoxide or cyanide in the blood (7). Changes in the lungs may be detected by bronchoscopy with biopsy, xenon imaging, or measurement of pulmonary extracellular fluid (4, 5, 8). These methods have, however, been associated with low sensitivity and specificity, as exemplified by the 50% predictive value in the study of Masanes et al. (8). Computed tomographs (CTs) are better than normal chest radiographs in the detection of other pulmonary lesions such as pulmonary contusion (9, 10). The importance of CT scans in patients with ARDS has been reviewed recently (9), but unfortunately there has been no experience of CT in patients with smoke inhalation injury. To our knowledge, there are only two animal studies reporting that smoke inhalation injury can be detected by CT (4, 11); specific changes in human CT scans have not yet been described. Therefore, confronted with a patient with severe respiratory failure after a burn who from the history and physical examination showed the classic risk factors for inhalation injury, we decided to request a CT.

Effect of clonal and serotype-specific properties on the invasive capacity of Streptococcus pneumoniae

The present study compares the molecular epidemiology of Streptococcus pneumoniae causing invasive disease and carriage, respectively, in one geographic area (Stockholm, Sweden) during a specific point in time (the year 1997). A total of 273 invasive isolates (257 from adults and 16 from children) obtained from the 2 major hospitals in Stockholm, as well as 246 nasopharyngeal isolates recovered from children attending 16 day-care centers in the Stockholm area, were analyzed by serotyping, molecular typing (by pulsed-field gel electrophoresis and multilocus sequence typing), and antibiotic susceptibility testing. Of the 34 different serotypes plus nontypeable strains identified in the present study, 12 were never found among the 246 colonizing isolates, whereas only 3 were never found among the 273 invasive isolates. The isolates formed 2 major classes: 1 class that was found mainly among invasive isolates (type 1, 4, 7F, and 9V isolates) and was clonally highly related and 1 class that caused invasive disease but was also common in carriage (including type 6A, 6B, 14, and 19F isolates) and was genetically more diverse. Clones were found that belonged to the same serotype but had different abilities to cause invasive disease. Also, isolates belonging to the same clone were found, although they had different capsules because of serotype switch, and were found to have the same disease potential. Hence, properties associated with a particular clonal type, in addition to capsular serotype, are likely to be important for the potential of pneumococci to cause invasive disease.

Clustering of enterococcal infections in a general intensive care unit

This is a retrospective study comparing patients' characteristics, antibiotic consumption and environmental contamination before the impact of a new regimen of intensified infection control measures in a general intensive care unit (ICU) at a university-affiliated tertiary-care teaching hospital. The new regimen consisted of (1) reorganization of patient rooms (2) improved hygienic measures including strict hygiene barrier nursing (3) more isolated patient care and (4) more restrictive use of antibiotics. The regimen was introduced after a cluster of enterococcal infections. All patients admitted to the ICU from 1 March 1995 to 28 february 1997 were included. A study period of 12 months after reorganization of the ward was compared with the 12 months immediately before it. The antibiotic consumption, the individual patient's severity of disease (APACHE score), and the extent of therapeutic interventions (TISS score) were recorded. Enterococci were typed biochemically, antibiograms were established and the relation between the isolates was investigated with pulsed-field gel electrophoresis. The bacteriological results and the patient data suggested a hospital-acquired spread as the cause of the ICU enterococcal outbreak. After implementation of the new regimen, we observed a reduction in the rate of enterococcal bloodstream infections from 3.1 to 1.8%. The consumption of antibiotics fell from 6.11 to 4.24 defined daily doses per patient. The introduction of strict hygiene and barrier nursing, more restrictive use of antibiotics, isolation of infected patients, thorough cleaning and disinfection of the unit was followed by an absence of enterococcal infection clustering and reduction in incidence of enterococcal bacteraemia. We were not able to determine whether the reduction in antibiotic consumption was due to the intervention programme.

Low frequency of plasma nerve-growth factor detection is associated with death of memory B lymphocytes in HIV-1 infection

Nerve growth factor (NGF) regulates B cell activation and differentiation and is an autocrine survival factor for memory B lymphocytes. We have reported recently that the number of memory B cells is reduced during HIV-1 infection. In this study we evaluated whether alteration in the NGF supply was involved in memory B cell loss in HIV-1-infected subjects. High rate of cell death in vitro was observed in memory B cells from HIV-1-infected individuals compared to uninfected donors (26.2 +/- 2.5%versus 7.9 +/- 1.4%, P < 0.001). The increased expression of Fas on memory B cells from infected subjects did not enhance the susceptibility of the cells to Fas-mediated apoptosis in vitro. The frequency of NGF detection in plasma from HIV-1-infected subjects was significantly lower than in healthy donors (33.6%versus 63.6%, P < 0.001). Also, the median plasma NGF in HIV-1-infected individuals was significantly lower than in uninfected controls (5 versus 14 pg/ml, respectively, P < 0.01). Interestingly, the plasma NGF level was correlated directly 1 to the percentage of memory B cells (P < 0.05). HIV-1-infected subjects with a low number of peripheral memory B cells had a reduced incidence of plasmatic NGF (7.4%) compared to patients with a normal level of memory B cells (37%, P < 0.01). Moreover, the addition of recombinant NGF (1 micro g/ml) to cultures of purified B cells reduced cell death of memory B cells from HIV-1-infected subjects from 24.04 +/- 3.0% to 17.4 +/- 1.3% (P < 0.01). HIV-1-infected individuals also carried higher levels of natural anti-NGF autoantibodies compared to uninfected subjects. In conclusion, we found that memory B cells from HIV-1-infected individuals are primed for cell death. Our study suggests an association between low frequency of plasma NGF detection and the increased cell death of memory B lymphocytes observed during HIV-1 infection. Low levels of NGF in plasma may be due to reduced supply or to NGF binding to natural anti-NGF autoantibodies.

Blood pressure, cardiac structure and severity of obstructive sleep apnea in a sleep clinic population

OBJECTIVES

We investigated whether the severity of obstructive sleep apnea (OSA) predicts blood pressure or cardiac left ventricular thickness in a clinical population of OSA patients, if adjustments are made for age, gender, use of antihypertensive agents, smoking, body mass index, history of coronary artery disease, hypercholesterolemia and circulating C-peptide concentrations.

DESIGN

Relationships in this cross-sectional study were investigated with correlation analysis and multiple regression procedures.

PATIENTS AND METHODS

Apnea-hypopnea index (AHI, polysomnography) and office systolic and diastolic blood pressures (SBP and DBP) were measured in 81 subjects referred to a university hospital sleep laboratory. Ambulatory blood pressures were recorded during one 24 h cycle. Left ventricular (LV) muscle size was quantified as two-dimensionally directed M-mode-derived end-diastolic thickness of interventricular septum and posterior chamber wall.

RESULTS

After adjustment for separate or the entire set of covariates, AHI predicted office SBP and DBP as well as daytime ambulatory DBP and night-time ambulatory SBP and DBP, but not daytime ambulatory SBP. In contrast, associations between AHI and LV muscle thickness reflected complex inter-relationships with confounding variables. Smoking and age suppressed, whereas body mass index (BMI) and hypertension inflated the relationship between OSA severity and LV muscle thickness in this study.

CONCLUSIONS

AHI is an independent predictor of several measures of blood pressure. OSA severity and LV muscle thickness appear to be primarily linked via increased blood pressure.

A mouse model for adenovirus gene delivery

The cellular attachment receptor for adenovirus (Ad), Coxsackie adenovirus receptor (CAR), required for delivery of Ad into primary cells, is not present on all cell types, thus restricting Ad-gene delivery systems. To circumvent this constrain, a transgenic mouse has been generated that expresses a truncated human CAR in all tissues analyzed. These mice allowed efficient in vitro infections at low multiplicities into lymphoid, myeloid, and endothelial cells. Furthermore, in vivo administration of Ad-vectors results in infection of macrophages, lymphocytes, and endothelial cells. In addition, tail vein injection resulted in targeting of virus into previously inaccessible areas, such as the lung and the capillaries of the brain. The CAR transgenic mice will be useful for rapid functional genomic analysis in vivo, for testing the efficacy of gene therapy procedures or as a source of easily transducible cells.

Antimicrobial susceptibility patterns of enterococci in intensive care units in Sweden evaluated by different MIC breakpoint systems

Three hundred and twenty-two (322) clinical isolates were collected from patients admitted to intensive care units (ICUs) at eight Swedish hospitals between December 1996 and December 1998. Of the isolates, 244 (76%) were Enterococcus faecalis, 74 (23%) were Enterococcus faecium and four (1%) were other Enterococcus spp. MICs of ampicillin, imipenem, meropenem, piperacillin/tazobactam, ciprofloxacin, trovafloxacin, clinafloxacin, gentamicin, streptomycin, vancomycin, teicoplanin, quinupristin/dalfopristin, linezolid and evernimicin were determined by Etest. Susceptible and resistant isolates were defined according to the species-related MIC breakpoints of the British Society for Antimicrobial Chemotherapy (BSAC), the National Committee for Clinical Laboratory Standards (NCCLS) and the Swedish Reference Group for Antibiotics (SRGA). Tentative breakpoints were applied for new/experimental antibiotics. Multidrug resistance among enterococci in ICUs is not uncommon in Sweden, particularly among E. faecium, and includes ampicillin resistance and concomitant resistance to fluoroquinolones. Almost 20% of E. faecalis isolates showed high-level resistance to gentamicin and concomitant resistance to fluoroquinolones. Vancomycin-resistant enterococci were only found sporadically. Among the new antimicrobial agents, linezolid and evernimicin showed the best activity against all enterococcal isolates. There was good concordance between the BSAC, NCCLS and SRGA breakpoints in detecting resistance. When applying the SRGA breakpoints for susceptibility, isolates were more frequently interpreted as intermediate. This might indicate earlier detection of emerging resistance using the SRGA breakpoint when the native population is considered susceptible, but with the risk that isolates belonging to the native susceptible population will be incorrectly interpreted as intermediate.

Impairment of vascular endothelial function and left ventricular filling : association with the severity of apnea-induced hypoxemia during sleep

STUDY OBJECTIVE

To investigate whether a dose-effect relationship exists between the severity of obstructive sleep apnea (OSA) and subclinical indicators of myocardial or vascular dysfunction.

DESIGN

Cross-sectional study using correlation analysis.

PARTICIPANTS

Twenty subjects referred to our sleep laboratory for screening or therapy of OSA but without regular medication and without known cardiovascular disease.

MEASUREMENTS

Severity of OSA was quantified by polysomnography. Moreover, nocturnal excretion of norepinephrine was determined. Left ventricular (LV) myocardial function was assessed with Doppler echocardiography. Using ultrasonographic measurements, endothelium-dependent and endothelium-independent conduit artery dilation were measured as flow-mediated and glyceryltrinitrate-induced changes in brachial artery diameter.

RESULTS

Worsening nocturnal hypoxemia, measured as nocturnal oxygen saturation nadir or percentage of sleep time spent in hypoxemia (< 90% hemoglobin oxygen saturation), predicted increased interventricular septum thickness (corrected for age and body mass index), prolonged isovolumetric relaxation time, decreased ratio between peak early and late mitral flow velocities, as well as reduced endothelium-dependent dilatory capacity of the brachial artery (all relationships corrected for cofactor age and with p < 0.05) were observed. Associations between these cardiovascular function markers and nocturnal excretion of norepinephrine followed the same trend, but relations with interventricular septum thickness and flow-mediated artery dilation missed significance (p = 0.064 and p = 0.061, respectively). LV posterior wall thickness, measures of LV systolic function, early mitral flow deceleration time, and endothelium-independent artery dilation were not significantly related to the degree of nocturnal hypoxemia or norepinephrine excretion. None of the correlations with apnea-hypopnea index were statistically significant.

CONCLUSIONS

The severity of apnea-related hypoxemia is associated with a gradual deterioration of LV diastolic function as well as large-artery endothelial function.

Mumps virus neutralizing antibodies do not protect against reinfection with a heterologous mumps virus genotype

In April 1999, a previously healthy 22-year-old woman was taken ill with fever and bilateral swelling of the parotid glands. A chronic course of disease extending from April to December was found with swelling of the parotid glands, fatigue, low grade fever, episodes of tachycardia and nightswetting. Mumps virus RNA of genotype A character based on the SH (small hydrophobic) protein gene classification was demonstrated in three serum samples collected during the course of clinical disease. Different criteria for reinfection were fulfilled including demonstration of IgG antibodies by ELISA in a preinfection serum sample. The preinfection serum sample of the patient was able to efficiently neutralize the infectivity of a heterologous genotype D strain but was unable to neutralize the homologous genotype A virus. The findings in the present study may offer an explanation of a mechanism behind previously observed vaccine failures and the occurrence of reinfection with heterologous mumps virus strains.

Anti-inflammatory activity of IVIG mediated through the inhibitory Fc receptor

The molecular basis for the anti-inflammatory property of intravenous gamma globulin (IVIG) was investigated in a murine model of immune thrombocytopenia. Administration of clinically protective doses of intact antibody or monomeric Fc fragments to wild-type or Fcgamma receptor-humanized mice prevented platelet consumption triggered by a pathogenic autoantibody. The inhibitory Fc receptor, FcgammaRIIB, was required for protection, because disruption either by genetic deletion or with a blocking monoclonal antibody reversed the therapeutic effect of IVIG. Protection was associated with the ability of IVIG administration to induce surface expression of FcgammaRIIB on splenic macrophages. Modulation of inhibitory signaling is thus a potent therapeutic strategy for attenuating autoantibody-triggered inflammatory diseases.

The lymphoid-specific cofactor OBF-1 is essential for the expression of a V(H) promoter/HS1,2 enhancer-linked transgene in late B cell development

Mice deficient for the lymphoid-specific cofactor OBF-1 display reduced levels of IgG, IgA and IgE. To examine whether the lowered immunoglobulin expression is linked to reduced activity of IgH cis-regulatory elements, OBF-1(-/-) mice were crossed with mice expressing transgenes driven by a V(H) or beta-globin promoter linked to the HS1,2 enhancer. Here we show that OBF-1 is essential for the induced expression of a V(H) promoter-linked transgene, in contrast to a beta-globin promoter-dependent transgene, in LPS/IL-4 or CD40-stimulated splenic B cells. Furthermore, impaired transgene expression is observed in OBF-1(-/-) peritoneal B cells. This deficiency may be linked to OBF-1, as peritoneal cells from normal mice express OBF-1 protein constitutively. Our data link OBF-1 to IgH gene expression in late B lymphoid development.

Serum homocysteine concentration as an indicator of survival in patients with acute coronary syndromes

BACKGROUND

Circulating homocysteine levels are predictive of survival in patients with stable coronary artery disease. The prognostic value of serum homocysteine levels, obtained in the acute phase in patients with myocardial infarction or unstable angina, is unknown.

OBJECTIVES

To test the hypothesis that circulating homocysteine levels, obtained during the first 24 hours following hospital admission in patients with acute coronary syndromes, are predictive of long-term mortality.

METHODS

To test this hypothesis we performed a prospective inception cohort study at a teaching hospital in Gothenburg, Sweden. A total of 579 patients (179 women and 400 men; median age, 67 years) were included (Q-wave myocardial infarction in 163 patients, non-Q-wave myocardial infarction in 210 patients, unstable angina pectoris in 206 patients).

MAIN OUTCOME MEASURE

All-cause mortality.

RESULTS

During a median follow-up of 628 days, 65 patients died. The serum homocysteine level (mean [SD]) was significantly lower in long-term survivors (n = 514) than in nonsurvivors (n=65) (12.3 [7.0] vs 14.3 [5.9] pmol/L; P=.003). The relative risk (all-cause mortality) for patients with homocysteine levels in the upper quartile was 2.4 (95% confidence interval, 1.5-4.0) compared with that of patients in the 3 lower quartiles. After adjustment for relevant confounders, the relative risk estimate remained significant (relative risk= 1.69; 95% confidence interval, 1.02-2.80). In a stepwise model the homocysteine level provided prognostic information additional to that of patient age, diabetes mellitus, and diuretic usage prior to hospital admission (P=.03).

CONCLUSION

The serum homocysteine level on hospital admission is an independent predictor of long-term survival in patients with acute coronary syndromes.

[Familial hemophagocytic lymphohistiocytosis: diagnosis, treatment and pathophysiological mechanisms]

Familial hemophagocytic lymphohistiocytosis (FHL) is an invariably fatal disease typically seen in infancy and early childhood, with a median survival without therapy of two months. It is characterized by prolonged fever, hepatosplenomegaly, cytopenia, and deficient NK-cell activity and T-cell cytotoxic capacity. Severe neurological symptoms as well as coagulation disorders and abnormalities in liver function and lipid status may also develop. Since the mid 1980's there has been a remarkable increase in our understanding of this disease. In a large-scale international collaborative effort mediated through the Histiocyte Society, diagnostic criteria and an international treatment protocol (HLH-94) based on immunochemotherapy and BMT have been developed. A large proportion of affected children can now be cured and, moreover, successful chemotherapy in utero of FHL has been achieved. It has been shown that the symptoms and signs are mediated through a pronounced hypercytokinemia. Previous suggestions that FHL may be caused by a deficiency in apoptosis were recently confirmed when perforin gene defects were described, which may well explain the disastrous lymphohistiocytic accumulation and subsequent T-cell activation.

Differential expression of cyclooxygenase 2 in human colorectal cancer

BACKGROUND

Experimental, clinical, and epidemiological studies have implicated mitogenic metabolites of arachidonic acid such as prostaglandin E(2) (PGE(2)) in colorectal carcinogenesis. Recently, cyclooxygenase 2 (COX-2) which catalyses the conversion of arachidonic acid to PGE(2), has displayed increased levels in human colorectal cancer.

AIMS

To evaluate whether there is differential COX-2 expression from different locations (caecum, ascending, transverse, descending, or sigmoid colon, and rectum) in human colorectal cancer.

METHODS

Protein levels of COX-2 were determined by western blot analysis in tumours and adjacent normal mucosa of 39 patients with colorectal cancer.

RESULTS

There was a notable overexpression of COX-2 protein in tumours located in the rectum (p<0.001) compared with other locations in the colon. Rectal tumours revealed elevated COX-2 protein levels in 18/20 cases compared with 4/19 colonic cases. No association between enhanced COX-2 protein expression in tumour tissue and Dukes's stages was found.

CONCLUSIONS

Results suggest that the differential COX-2 expression may be due to differences in gene regulatory factors affecting COX-2 expression and/or reflect secondary changes in tumour progression which may have clinical implications.

Multicenter quality assessment of PCR methods for detection of enteroviruses

We conducted a multicenter evaluation of commercial and in-house PCR methods for the detection of enteroviruses. Three coded panels of test and control RNA samples, artificial clinical specimens, and representative enterovirus serotypes were used to assess amplification methods, RNA extraction methods, and reactivities with different enterovirus serotypes. Despite several differences between PCR methods, there was good agreement, although some variation in sensitivity was observed. Most PCR methods were able to detect enterovirus RNA derived from 0.01 50% tissue culture infective dose (TCID50) and were able to detect at least 1 TCID50 of enterovirus in cerebrospinal fluid, stool, or throat swab specimens. Most were also able to detect a wide range of enterovirus serotypes, although serotypic identification was not possible. Some laboratories experienced false-positive results due to PCR contamination, which appeared to result mainly from cross-contamination of specimens during RNA extraction. Provided that this problem is overcome, these PCR methods will prove to be a sensitive and rapid alternative to cell culture for the diagnosis of enterovirus infection.

Soft tissue sarcoma after treatment for breast cancer--a Swedish population-based study

The aim was to quantify the risk of post-treatment sarcoma in breast cancer patients. All 122,991 women with a breast cancer from 1958 to 1992 in the Swedish Cancer Register were followed up for soft tissue sarcomas and 116 were found, giving a standardised incidence ratio of 1.9 (95% CI 1.5-2.2). The absolute risk was 1.3 per 10(4) person-years. The sarcomas were located in the breast region or on the ipsilateral arm in 63% (67/106). There were 40 angiosarcomas and 76 sarcomas of other types. In a case-control study, angiosarcoma correlated significantly with lymphoedema of the arm, odds ratio (OR) 9.5 (95% CI 3.2-28.0), but no correlation with radiotherapy was observed. For other types of sarcoma there was a correlation with the integral dose. The dose-response relationship indicated that the risk increased linearly with the integral dose to 150-200 J and stabilised at higher energies. The OR was 2.4 (95% CI 1.4-4.2) for an energy of 50 J, approximately corresponding to the radiation of the breast after breast-conserving surgery. Thus, only oedema of the arm correlated with angiosarcoma, but for other types of sarcoma the integral dose of radiotherapy was a predictor of the risk.

Gene expression of cyclooxygenase-2, group II and cytosolic phospholipase A2 in human colorectal cancer

The development of intestinal tumours in the Min mouse is influenced by Moml locus, where the group II phospholipase A2 (PLA2-II) gene has been suggested as the candidate gene. Since no causative genetic alterations have been identified in PLA2-II in human colorectal tumours, we tested whether PLA2-II or the cytosolic isoform cPLA2, are dysregulated in human colorectal carcinogenesis. By means of RT-PCR, the expression of these genes and cyclooxygenase-2 (COX-2), which is upregulated in colorectal tumours, were examined. No changes in gene expression of PLA2-II were found in 44 tumours compared to normal mucosa. cPLA2 and COX-2 were upregulated; however, no correlation in expression was found between these genes. Thus, the supply of arachidonic acid provided by PLA2-II/cPLA2 seems not to be the rate limiting step in PGE2 (a prostaglandin/mitogen) formation via COX-2 and PLA2-II plays a minor or no role in human colorectal carcinogenesis.

Calculation of absorbed dose distributions from dynamic wedges

In radiotherapy with photon beams, the use of dynamic wedges, which are obtained by the movement of one of the jaws, offers an increasing flexibility relative to the traditional use of metal wedges. But it is a disadvantage for the measurement of absorbed dose distributions, because the absorbed dose at each measurement point can only be obtained after a complete movement of the jaw. Consequently, for radiotherapy planning, an algorithm should be available that does not require measurements for any specific dynamically wedged beam, but is based on only a modest number of measurements. In this paper, an algorithm for the calculation of the dose distribution from dynamic wedges is described. This algorithm uses the convolution of pencil beam kernels with a non-uniform field function. These pencil beam kernels are derived from empirical data resulting from measurements of the open beam only.

Dose accuracy check of the 3D electron beam algorithm in a treatment planning system

The accuracy of the recently implemented three-dimensional electron beam dose calculating algorithm in CADPLAN version 2.62 manufactured by Varian Dosetek was investigated. The algorithm uses a generalized Gaussian pencil beam model and the dose distributions are calculated as the sum of three weighted Gaussians. To use the calculating program in an optimum way, one needs to know the dose calculation accuracy of the algorithm as well as its limitations. This investigation includes comparisons of measured relative dose distributions with calculated dose distributions and also comparisons of measured and calculated monitor units. The geometries tested were quadratic fields, irregularly shaped fields, oblique fields, irregularly shaped phantom surfaces and internal heterogeneities and were most often irradiated with 8 and 20 MeV electrons. The results indicate that the algorithm is well suited for clinical three-dimensional dose planning. Some deviations occurred but they were most often within the limits of international criteria of acceptability.

Apoptosis of CD4+ and CD19+ cells during human immunodeficiency virus type 1 infection--correlation with clinical progression, viral load, and loss of humoral immunity

Enhanced rates of programmed cell death (apoptosis) have been detected in T cells and B cells from human immunodeficiency virus type 1 (HIV-1)-infected individuals. To evaluate the possible relevance of this event to HIV pathogenesis and disease progression, apoptosis in CD4+ T lymphocytes and CD19+ B lymphocytes, viral load, and neutralizing antibody titers were assayed in HIV-1-infected slow progressors and progressors. A correlation was found between progressive disease and apoptosis of CD4+ T cells. The extent of apoptosis in CD4+ cells was similar in slow progressors and seronegative control subjects. By contrast, we found elevated levels of B-cell apoptosis in all HIV-1-infected individuals compared with seronegative control subjects, with a tendency toward increased levels of apoptosis with progressive disease. Apoptosis in CD4+ T cells and CD19+ B cells correlated with viral RNA levels in plasma. Furthermore, higher rates of B-cell apoptosis were observed in individuals with poor neutralizing activity against a panel of six clinical HIV-1 isolates. From these results we conclude that the extent of apoptosis in cultured CD4+ cells and CD19+ cells appears to parallel the decline in CD4 cell counts in infected individuals. The finding of a relation between apoptosis in B cells and poor neutralizing capacity suggests that apoptosis may be related to loss of immune function. A role for apoptosis in the pathogenesis of AIDS is also supported by the strong correlation between viral load and rates of apoptosis in CD4+ T cells.

Practical implementation of enhanced dynamic wedge in the CadPlan treatment planning system

The Varian CadPlan algorithm for computation of relative dose distributions and monitor unit calculations for Enhanced Dynamic Wedge (EDW) fields is based on a combination of open field beam data and Segmented Treatment data Tables. Calculation of dose by the pencil beam convolution model uses scatter kernels and boundary kernels to create the distribution. The principles of the pencil beam convolution model is presented. Comparison of measured and calculated monitor units and relative dose distributions showed good agreement and the deviations are within international accepted tolerans. Test results indicate that the EDW model works satisfactorily for all energies and wedge angles.

Effects of codon usage and vector-host combinations on the expression of spinach plastocyanin in Escherichia coli

Spinach plastocyanin has been expressed in Escherichia coli and exported to the periplasmic space. The effects of codon usage, expression system, growth length, and temperature on expression levels in LB medium were investigated. A stretch of codons, rare in E. coli, was identified and replaced with highly expressed codons, increasing the yield by at least 20%. Plastocyanin was more efficiently expressed under the T7 promoter than under the lac promoter. Maximum yields were obtained at 37 degrees C when growing the cells for 16 h after induction. The optimized expression system produced 38 mg holoprotein per liter culture. In this system it was also possible to express plastocyanin in minimal medium, at a yield of 10 mg per liter. N-terminal sequencing and mass spectrometry showed that plastocyanin was correctly processed. The expressed plastocyanin was purified to homogeneity, as shown by an A278/A597 ratio of 1.0, and together with amino acid analysis and the determination of oxidized and total copper contents, both the absorption coefficients for epsilon 278 and for epsilon 597 were determined to be 4700 M-1 cm-1.

Chicken parathyroid hormone gene expression in response to gastrin, omeprazole, ergocalciferol, and restricted food intake

Treatment with omeprazole, a long-acting proton pump inhibitor of acid secretion, induces hypergastrinemia. In chickens, omeprazole induces growth not only of the acid-producing mucosa (probably reflecting the trophic action of gastrin), but also of the parathyroid glands (hypertrophy + hyperplasia), while suppressing bone density and body weight gain without affecting blood calcium. The first part of the present study was concerned with the effect of omeprazole, ergocalciferol (vitamin D2), and restricted food intake on the gene expression of parathyroid hormone (PTH) in the parathyroid glands of the chicken. Chickens were treated with omeprazole (400 micromol/kg/day, I.M.), food restriction, omeprazole + food restriction, ergocalciferol (250 000 IU/kg/day, S.C.), or ergocalciferol + omeprazole for 5 weeks. The weight gain of the chickens was monitored, and the weights of the parathyroid glands and femurs were determined at sacrifice. PTH mRNA in the parathyroid glands was analyzed by Northern blot. The second part of the study examined the effect of 3 weeks of continuous gastrin infusion (chicken gastrin 20-36, 5 nmol/kg/hour, S.C.) on the expression of PTH mRNA in the parathyroid glands. Omeprazole reduced the body weight and femur density (ash weight per volume) while greatly increasing the weight of the parathyroid glands and the PTH gene expression. Food restriction alone and ergocalciferol alone (at a dose that raised blood Ca2+) were without effect, but food restriction greatly enhanced the omeprazole-evoked increase in parathyroid gland weight and PTH gene expression. Gastrin increased the weight of the parathyroid glands and reproduced the effect of omeprazole on PTH gene expression. Hence, it seems likely that the effect of omeprazole reflects the ensuing hypergastrinemia.

Progressive B cell apoptosis and expression of Fas ligand during human immunodeficiency virus type 1 infection

HIV-1 infection causes functional defects in T cells. It also leads to a progressive reduction in numbers of such cells and both CD4+ and CD8+ cells have been reported to undergo apoptosis in culture. A corresponding reduction in B cells has not been described, but these cells are also functionally altered, with reports of polyclonal activation and hyporesponsiveness to antigenic and mitogenic stimuli. Here we investigated B cells from HIV-1-seropositive individuals and found that these cells, which are not the target for virus infection, died of apoptosis on culturing. We could also confirm previous findings that CD4+ cells from HIV-1-infected individuals undergo apoptosis in culture. Apoptosis of both B cells and CD4+ cells correlated inversely with CD4 cell counts. B cells from HIV-1-infected individuals were found to express Fas ligand, and the expression of this protein correlated with the levels of apoptosis in the same cells. Non-B cells, on the other hand, expressed increased levels of Fas but low levels of Fas ligand. These results are in line with suggestions that the Fas/Fas ligand pathway may trigger the increased levels of apoptosis observed in cells from HIV-1-infected individuals.