Cytomegalovirus High-risk Kidney Transplant Recipients Show No Difference in Long-term Outcomes Following Preemptive Versus Prophylactic Management

BACKGROUND

Following kidney transplantation (KT), cytomegalovirus (CMV) infection remains an important challenge. Both prophylactic and preemptive antiviral protocols are used for CMV high-risk kidney recipients (donor seropositive/recipient seronegative; D+/R-). We performed a nationwide comparison of the 2 strategies in de novo D+/R- KT recipients accessing long-term outcomes.

METHODS

A nationwide retrospective study was conducted from 2007 to 2018, with follow-up until February 1, 2022. All adult D+/R- and R+ KT recipients were included. During the first 4 y, D+/R- recipients were managed preemptively, changing to 6 mo of valganciclovir prophylaxis from 2011. To adjust for the 2 time eras, de novo intermediate-risk (R+) recipients, who received preemptive CMV therapy throughout the study period, served as longitudinal controls for possible confounders.

RESULTS

A total of 2198 KT recipients (D+/R-, n = 428; R+, n = 1770) were included with a median follow-up of 9.4 (range, 3.1-15.1) y. As expected, a greater proportion experienced a CMV infection in the preemptive era compared with the prophylactic era and with a shorter time from KT to CMV infection ( P  < 0.001). However, there were no differences in long-term outcomes such as patient death (47/146 [32%] versus 57/282 [20%]; P  = 0.3), graft loss (64/146 [44%] versus 71/282 [25%]; P  = 0.5), or death censored graft loss (26/146 [18%] versus 26/282 [9%]; P  = 0.9) in the preemptive versus prophylactic era. Long-term outcomes in R+ recipients showed no signs of sequential era-related bias.

CONCLUSIONS

There were no significant differences in relevant long-term outcomes between preemptive and prophylactic CMV-preventive strategies in D+/R- kidney transplant recipients.

Diagnostic stewardship aiming at expectorated or induced sputum promotes microbial diagnosis in community-acquired pneumonia

Purpose

Studies on aetiology of community-acquired pneumonia (CAP) vary in terms of microbial sampling methods, anatomical locations, and laboratory analyses, since no gold standard exists. In this large, multicentre, retrospective, regional study from Norway, our primary objective was to report the results of a strategic diagnostic stewardship intervention, targeting diagnostic yield from lower respiratory tract sampling. The secondary objective was to report hospitalized CAP aetiology and the diagnostic yield of various anatomical sampling locations.

Methods

Medical records from cases diagnosed with hospitalized CAP were collected retrospectively from March throughout May for three consecutive years at six hospitals. Between year one and two, we launched a diagnostic stewardship intervention at the emergency room level for the university teaching hospital only. The intervention was multifaceted aiming at upscaling specimen collection and enhancing collection techniques. Year one at the interventional hospital and every year at the five other emergency hospitals were used for comparison.

Results

Of the 1280 included cases of hospitalized CAP, a microbiological diagnosis was established for 29.1% among 1128 blood cultures and 1444 respiratory tract specimens. Blood cultures were positive for a pathogenic respiratory tract microbe in 4.9% of samples, whereas upper and lower respiratory tract samples overall provided a probable microbiological diagnosis in 21.3% and 47.5%, respectively. Expectorated or induced sputum overall provided aetiology in 51.7% of the samples. At the interventional hospital, the number of expectorated or induced sputum samples were significantly increased, and diagnostic yield from expectorated or induced sputum was significantly enhanced from 41.2 to 62.0% after the intervention (p = 0.049). There was an over-representation of samples from the interventional hospital during the study period. Non-typeable Haemophilus influenza and Streptococcus pneumoniae accounted for 25.3% and 24.7% of microbiologically confirmed cases, respectively.

Conclusion

Expectorated or induced sputum outperformed other sampling methods in providing a reliable microbiological diagnosis for hospitalized CAP. A diagnostic stewardship intervention significantly improved diagnostic yield of lower respiratory tract sampling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07199-4.

Emergence and dissemination of antimicrobial resistance in Escherichia coli causing bloodstream infections in Norway in 2002-17: a nationwide, longitudinal, microbial population genomic study

BACKGROUND

The clonal diversity underpinning trends in multidrug resistant Escherichia coli causing bloodstream infections remains uncertain. We aimed to determine the contribution of individual clones to resistance over time, using large-scale genomics-based molecular epidemiology.

METHODS

This was a longitudinal, E coli population, genomic, cohort study that sampled isolates from 22 512 E coli bloodstream infections included in the Norwegian surveillance programme on resistant microbes (NORM) from 2002 to 2017. 15 of 22 laboratories were able to share their isolates, and the first 22·5% of isolates from each year were requested. We used whole genome sequencing to infer the population structure (PopPUNK), and we investigated the clade composition of the dominant multidrug resistant clonal complex (CC)131 using genetic markers previously reported for sequence type (ST)131, effective population size (BEAST), and presence of determinants of antimicrobial resistance (ARIBA, PointFinder, and ResFinder databases) over time. We compared these features between the 2002-10 and 2011-17 time periods. We also compared our results with those of a longitudinal study from the UK done between 2001 and 2011.

FINDINGS

Of the 3500 isolates requested from the participating laboratories, 3397 (97·1%) were received, of which 3254 (95·8%) were successfully sequenced and included in the analysis. A significant increase in the number of multidrug resistant CC131 isolates from 71 (5·6%) of 1277 in 2002-10 to 207 (10·5%) of 1977 in 2011-17 (p<0·0001), was the largest clonal expansion. CC131 was the most common clone in extended-spectrum β-lactamase (ESBL)-positive isolates (75 [58·6%] of 128) and fluoroquinolone non-susceptible isolates (148 [39·2%] of 378). Within CC131, clade A increased in prevalence from 2002, whereas the global multidrug resistant clade C2 was not observed until 2007. Multiple de-novo acquisitions of both blaCTX-M ESBL-encoding genes in clades A and C1 and gain of phenotypic fluoroquinolone non-susceptibility across the clade A phylogeny were observed. We estimated that exponential increases in the effective population sizes of clades A, C1, and C2 occurred in the mid-2000s, and in clade B a decade earlier. The rate of increase in the estimated effective population size of clade A (Ne=3147) was nearly ten-times that of C2 (Ne=345), with clade A over-represented in Norwegian CC131 isolates (75 [27·0%] of 278) compared with the UK study (8 [5·4%] of 147 isolates).

INTERPRETATION

The early and sustained establishment of predominantly antimicrobial susceptible CC131 clade A isolates, relative to multidrug resistant clade C2 isolates, suggests that resistance is not necessary for clonal success. However, even in the low antibiotic use setting of Norway, resistance to important antimicrobial classes has rapidly been selected for in CC131 clade A isolates. This study shows the importance of genomic surveillance in uncovering the complex ecology underlying multidrug resistance dissemination and competition, which have implications for the design of strategies and interventions to control the spread of high-risk multidrug resistant clones.

FUNDING

Trond Mohn Foundation, European Research Council, Marie Skłodowska-Curie Actions, and the Wellcome Trust.

Thrombin Induces Thromboplastin Synthesis in Cultured Vascular Endothelial Cells

Cultured human umbilical vein endothelial cells responded to thrombin (10−2 – 10 NIH u/ml) with a 2-5 fold increase in thromboplastin activity. The maximum response was reached after 4 hr in serum-free medium. The effect of thrombin was fully inhibited by the presence of 50% (v/v) fetal calf serum or more in the medium, by preincubation of thrombin with hirudin or by treatment of thrombin with N-bromosuccinimide or phenylmethylsulfonyl fluoride. The thrombin-induced thromboplastin activity was inhibited by incubation of the cells with cycloheximide (2 μg/ml) or actinomycin D (2 μg/ml) showing that the response depended on de novo protein and RNA synthesis. It was also suppressed by exposure of the cells to two different phosphodiesterase inhibitors, 3-butyl-l-methyl-xanthine (5 · 10−4 M) and rac-4 (3-butoxy-4-methoxybenzyl)-2-imidazole (5 · 10−4 M), to the transmethylation inhibitors 3-deazaadenosine (10−5 M) and 1-homocysteine thiolactone (2 · 10−5 M) in combination and to the intracellular calcium antagonist 8-(N,N-diethylamino)-octyl 3,4,5,-tri-methoxybenzoate hydrochloride (8 · 10−5 M). Our results suggest that small amounts of thrombin can induce thromboplastin synthesis in endothelial cells in vitro and that this synthesis probably is regulated by the intracellular level of cAMP, by cytoplasmic Ca2+ and possibly also by transmethylation reactions.

Mecillinam against genital Chlamydia trachomatis infection: a small-scale proof-of-concept study shows a low cure rate

OBJECTIVES

Mecillinam is highly active in vitro against Chlamydia spp. We aimed to determine whether mecillinam should be evaluated further as treatment for genital Chlamydia trachomatis infection.

PATIENTS AND METHODS

The study was conducted at an open-access clinic for sexually transmitted infections in Oslo, Norway. We planned to include 50 patients. Participants were asymptomatic, heterosexual male patients with a first-void urine sample found to be positive for C. trachomatis by PCR. Treatment consisted of 400 mg of pivmecillinam hydrochloride three times a day for 7 days. A test-of-cure sample, a medication diary and a questionnaire were returned by the participants, and they were used to evaluate treatment outcome, compliance, risk of reinfection and theoretical percentage of time above MIC (t/MIC %). The study was registered in Eudra-CT (no. 2013-002379-179) and clinicaltrals.gov (NCT02083276).

RESULTS

The study was discontinued after including 20 patients, due to a high failure rate. Only two of the 17 participants who delivered a test-of-cure sample were cured. Three participants reported condomless sex before the follow-up sample. When the average or most favourable pharmacokinetics (PK)/pharmacodynamics (PD) reported from other studies were applied in a theoretical model, the estimated t/MIC % was above 50% for all of the 15 participants returning a medication diary. Using the least favourable PK/PD, no participant had t/MIC % of >36%. The mean dose interval was 8 h 36 min (standard deviation 3 h 12 min).

CONCLUSIONS

A low cure rate combined with uncertainty about intracellular availability and attained t/MIC % makes mecillinam an unattractive candidate for further evaluation as treatment for genital C. trachomatis infection.

Assessing reproductive and endocrine parameters in male largescale suckers (Catostomus macrocheilus) along a contaminant gradient in the lower Columbia River, USA

Persistent organochlorine pollutants such as polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p'-DDE), and polybrominated diphenyl ethers (PBDEs) are stable, bioaccumulative, and widely found in the environment, wildlife, and the human population. To explore the hypothesis that reproduction in male fish is associated with environmental exposures in the lower Columbia River (LCR), reproductive and endocrine parameters were studied in male resident, non-anadromous largescale sucker (Catostomus macrocheilus) (LSS) in the same habitats as anadromous salmonids having conservation status. Testes, thyroid tissue and plasma collected in 2010 from Longview (LV), Columbia City (CC), and Skamania (SK; reference) were studied. Sperm morphologies and thyrocyte heights were measured by light microscopy, sperm motilities by computer-assisted sperm motion analysis, sperm adenosine triphosphate (ATP) with luciferase, and plasma vitellogenin (VTG), thyroxine (T4), and triiodothyronine (T3) by immunoassay. Sperm apoptosis, viability, mitochondrial membrane potential, nuclear DNA fragmentation, and reproductive stage were measured by flow cytometry. Sperm quality parameters (except counts) and VTG were significantly different among sites, with correlations between VTG and 7 sperm parameters. Thyrocyte heights, T4, T3, gonadosomatic index and Fulton's condition factor differed among sites, but not significantly. Sperm quality was significantly lower and VTG higher where liver contaminants and water estrogen equivalents were highest (LV site). Total PCBs (specifically PCB-138, -146, -151, -170, -174, -177, -180, -183, -187, -194, and -206) and total PBDEs (specifically BDE-47, -100, -153, and -154) were negatively correlated with sperm motility. PCB-206 and BDE-154 were positively correlated with DNA fragmentation, and pentachloroanisole and VTG were positively correlated with sperm apoptosis and negatively correlated with ATP. BDE-99 was positively correlated with sperm counts and motility; T4 was negatively correlated with counts and positively correlated with motility, thus indicating possible androgenic mechanisms and thyroid endocrine disruption. Male LSS proved to be an informative model for studying reproductive and endocrine biomarkers in the LCR.

A Shigella sonnei outbreak traced to imported basil – the importance of good typing tools and produce traceability systems, Norway, 2011

Binary file ES_Abstracts_Final_ECDC.txt matches

Large IncHI2-plasmids encode extended-spectrum β-lactamases (ESBLs) in Enterobacter spp. bloodstream isolates, and support ESBL-transfer to Escherichia coli

We investigated the prevalence of extended-spectrum β-lactamases (ESBLs) in Enterobacter spp. bloodstream isolates from 19 hospital laboratories in Norway during 2011. A total of 62/230 (27%) isolates were resistant to third-generation cephalosporins and four (1.7%) were ESBL-positive; blaCTX -M-15 (n = 3) and blaSHV -12 (n = 1). This is comparable to the prevalence of ESBLs in clinical isolates of Escherichia coli and Klebsiella pneumoniae in Norway during the same period. All ESBL-positive isolates were multidrug resistant (MDR) and harboured plasmid-mediated quinolone resistance. Three isolates supported transfer of large IncHI2-plasmids harbouring ESBL- and MDR-encoding genes to E. coli recipients by in vitro conjugation.

Automated identification and susceptibility determination directly from blood cultures facilitates early targeted antibiotic therapy

BACKGROUND

The increasing prevalence of antibiotic resistance is challenging established empirical treatments, making early identification and susceptibility determination more important. To avoid time-consuming overnight cultures, a previously published method for the rapid identification and susceptibility testing of blood cultures was instituted at Molde Hospital. The time saved compared to the standard method, and how often the results could have led to a change in the empirical antibiotic treatment compared to Gram stain from cultures, were evaluated.

MATERIAL AND METHODS

All positive blood cultures with Gram-negative bacilli obtained between March and December 2010 were included in the study (n = 69). Accuracy and turn-around times were compared to those of the standard methods. The empirical antibiotic treatment was recorded when consulting the clinician about the results.

RESULTS

Correct identification was obtained in 66/69 (95.7%) of the isolates. Correct susceptibility determination was obtained in 758/759 (99.9%) of the tests. Oral reports to the clinician were given on average 11 h 22 min earlier for identification, and 10 h 51 min earlier for susceptibility determination, compared to the standard methods. With optimal handling we could have managed 17 h 26 min and 16 h 14 min, respectively. In 14/69 cases the empirical treatment included no effective or appropriate antibiotics. 7 of these 14 would not have been changed to working antibiotic treatment based on Gram stain alone.

CONCLUSION

The rapid method was found to be accurate and showed the potential for the initiation of effective antibiotic treatment more than 16 h earlier for 10% of the patients in this small sample.

Low prevalence of Mycoplasma genitalium in patients examined for Chlamydia trachomatis

BACKGROUND

There is increasing interest in Mycoplasma genitalium as a sexually transmissible pathogen. The clinical picture resembles that of Chlamydia trachomatis infection, but the natural course has not yet been well defined. There are no guidelines regarding who should be examined for M. genitalium. Most of the prevalence studies have been carried out in patients attending clinics for sexually transmissible diseases. We have examined the prevalence in samples sent from general practice requesting analysis for C. trachomatis.

MATERIAL AND METHOD

During the period October 1 to December 31 2010, all samples sent to Molde Hospital, Norway, that queried C. trachomatis were examined also for M. genitalum. Both agents were examined using real time PCR. The PCR for C. trachomatis was performed using a CE labelled and IVD approved method from Roche. The PCR for M. genitalium was performed using an in-house method where the target gene is GAP.

RESULT

A total of 950 patients were examined (Men n=225, women n=725). The prevalences of M. genitalium and C. trachomatis were 2.0 % and 10.0 % respectively (men 4.0 % and 15.1 %, women 1.4 % and 8.4 %).

CONCLUSION

Because of the low prevalence, we recommend selection of patients for examination for M. genitalium. The difference in prevalence between the sexes can reflect different indications for sample taking.

Nonlinear dynamical law governs magnetic field induced changes in lymphoid phenotype

The results of many different types of animal and human studies dealing with the biological effects of exposure to low frequency electromagnetic fields (EMFs) have consistently been both positive and negative. We addressed the question of why this pattern had occurred so commonly in biological studies involving exposure to EMFs and hypothesized that it stemmed from the prevalent use of a linear model to characterize what are inherently nonlinear input-output relationships. The hypothesis was tested by analyzing biological data using a novel statistical procedure that could be adjusted to detect either nonlinear or linear effects. The reliability of the procedure was established using positive and negative controls and by comparison with the results obtained from sampling a known nonlinear system. In four independent experiments, male and female mice were exposed continuously to 0.1 or 0.5 mT, 60 Hz, for 175 days, and the effect on 20 immune parameters was measured using flow cytometry and functional assays. In each experiment, EMF exposure resulted in statistically significant changes in lymphoid phenotype when and only when the response of the animals to the fields was analyzed as if it were governed by nonlinear laws. Our results suggest that the pattern of inconsistency in the EMF bioeffects studies is an artifact resulting from an incorrect choice of the conceptual model for the relation between the field and the biological effect it causally determines.

Nonlinear determinism in the immune system. In vivo influence of electromagnetic fields on different functions of murine lymphocyte subpopulations

Animal studies of the effects of low-frequency electromagnetic fields (EMFs) on the immune system appear inconsistent, and recent evidence indicates that inconspicuous experimental problems are not responsible. We hypothesized that the inconsistencies resulted from use of linear methods and models to study inherently nonlinear input-output relationships. Using a novel analytical method, we found that exposure of mice to 5 G, 60 Hz, for 1-105 days in 6 independent experiments consistently affected a broad panel of immune variables when and only when the reaction of the immune system was modeled to allow the possibility of nonlinearity in the relationship between the field and the immune variables. It was possible to mimic the pattern observed in the immune data by sampling from a known chaotic system, suggesting the possibility that the observed pattern was the result of intrinsic nonlinear regulatory mechanisms in the immune system. Overall, the results suggested that lymphoid sub-populations were vulnerable to the physiological consequences of EMF transduction, that it may never be possible to predict specific changes in particular immune-system variables, and that the underlying behavior of the immune system (that which occurs in the absence of specific inputs) may be governed by laws that manifest extreme sensitivity to prior states.

[Populational research of gastric cancer in digestive symptomatic patients, from 1996 to 2000]

BACKGROUND

Gastric cancer is the first cause of death due to malignant tumors in Chile. Its mortality rates have stabilized in the last two decades and its prognosis is closely associated to the degree of tumor invasion at the moment of surgery.

AIM

To study the frequency of gastric cancer among symptomatic patients subjected to an upper gastrointestinal endoscopy at a secondary care health center.

PATIENTS AND METHODS

All upper gastrointestinal endoscopies performed to patients derived from public primary care clinics were recorded.

RESULTS

In the study period, 4,145 endoscopies were done to 818 men and 2,128 women. Seventy one percent of patients were aged over 40 years of age. Fifty one carcinomas and one lymphoma were detected. Of these, 10 tumors were incipient. Thirty one patients were operated on and in 22 a total gastrectomy was performed. One patient, that required an esophageal resection, died.

CONCLUSIONS

Gastric cancer was detected in 1.2% of symptomatic adult patients subjected to an upper gastrointestinal endoscopy.

Coincident nonlinear changes in the endocrine and immune systems due to low-frequency magnetic fields

OBJECTIVE

The characteristic biological effects of low-frequency electromagnetic fields (EMFs) appear to be functional changes in the central nervous, endocrine and immune systems. For unapparent reasons, however, the results of similar studies have often differed markedly from one another. We recognized that it had generally been assumed, in the studies, that EMF effects would exhibit a dose-effect relationship, which is a basic property of linear systems. Prompted by recent developments in the theory on nonlinear systems, we hypothesized that there was a nonlinear relationship between EMFs and the effects they produced in the endocrine and immune systems.

METHODS

We developed a novel analytical method that could be used to distinguish between linear and nonlinear effects, and we employed it to examine the effect of EMFs on the endocrine and immune systems.

RESULTS

Mice exposed to 5 G, 60 Hz for 1-175 days in 7 independent experiments reliably exhibited changes in serum corticosterone and lymphoid phenotype when the data were analyzed while allowing that the field exposure and the resulting effects could be nonlinearly related. When the analysis was restricted to linear relationships, no effects due to the field were found.

CONCLUSIONS

The results indicated that transduction of EMFs resulted in changes in both the endocrine and immune systems, and that the laws governing the changes in each system were not the type that govern conventional dose-effect relationships. Evidence based on mathematical modeling was found suggesting that the coincident changes could have been causally related.

Witnessing-condition heterogeneity and witnesses' versus investigators' confidence in the accuracy of witnesses' identification decisions

Undergraduate participants were tested in 144 pairs, with one member of each pair randomly assigned to a "witness" role and the other to an "investigator" role. Each witness viewed a target person on video under good or poor witnessing conditions and was then interviewed by an investigator, who administered a photo line up and rated his or her confidence in the witness. Witnesses also (separately) rated their own confidence. Investigators discriminated between accurate and inaccurate witnesses, but did so less well than witnesses' own confidence ratings and were biased toward accepting witnesses' decisions. Moreover, investigators' confidence made no unique contribution to the prediction of witnesses' accuracy. Witnesses' confidence and accuracy were affected in the same direction by witnessing conditions, and there was a substantial confidence-accuracy correlation when data were collapsed across witnessing conditions. Confidence can be strongly indicative of accuracy when witnessing conditions vary widely, and witnesses' confidence may be a better indicator than investigators'.

Nonlinear response of the immune system to power-frequency magnetic fields

Studies of the effects of power-frequency electromagnetic fields (EMFs) on the immune and other body systems produced positive and negative results, and this pattern was usually interpreted to indicate the absence of real effects. However, if the biological effects of EMFs were governed by nonlinear laws, deterministic responses to fields could occur that were both real and inconsistent, thereby leading to both types of results. The hypothesis of real inconsistent effects due to EMFs was tested by exposing mice to 1 G, 60 Hz for 1-105 days and observing the effect on 20 immune parameters, using flow cytometry and functional assays. The data were evaluated by means of a novel statistical procedure that avoided averaging away oppositely directed changes in different animals, which we perceived to be the problem in some of the earlier EMF studies. The reliability of the procedure was shown using appropriate controls. In three independent experiments involving exposure for 21 or more days, the field altered lymphoid phenotype even though the changes in individual immune parameters were inconsistent. When the data were evaluated using traditional linear statistical methods, no significant difference in any immune parameter was found. We were able to mimic the results by sampling from known chaotic systems, suggesting that deterministic chaos could explain the effect of fields on the immune system. We conclude that exposure to power-frequency fields produced changes in the immune system that were both real and inconsistent.

[Practical approach to otitis media with methicillin-resistant yellow Staphylococci]

Methicillin-resistant Staphylococcus aureus (MRSA) are multiresistant bacteria, known to cause nosocomial infections. We present a report on a two and a half year-old, recently adopted, child, who suffered from otitis media with discharge. The child was treated with penicillin in Norway without success. Culture revealed methicillin-resistant S aureus. Methicillin-resistant S aureus were also found in the noses of the adoptive parents. After a second unsuccessful course of antibiotics the child was admitted to the Ear, nose, and throat department and was subsequently treated with intravenous vancomycin, mastoidectomy and eradication of the nasal methicillin-resistant S aureus carriage. The admittance to the Ear, nose, and throat department was carefully planned. All departments concerned were thoroughly briefed. The patient was given vancomycin intravenously for 18 days, partly as an out-patient. Subsequent control cultures from the patient and the adoptive parents have all been negative. No one dealing with the patient has been infected. The case illustrates the importance of thorough planning and co-operation between different departments.

Carbon isotopic composition of legumes with photosynthetic stems from mediterranean and desert habitats

The carbon isotopic compositions of leaves and stems of woody legumes growing in coastal mediterranean and inland desert sites in California were compared. The overall goal was to determine what factors were most associated with the carbon isotope composition of photosynthetic stems in these habitats. The carbon isotope signature (d13C) of photosynthetic stems was less negative than that of leaves on the same plants by an average of 1.51 ± 0.42 ;pp. The d13C of bark (cortical chlorenchyma and epidermis) was more negative than that of wood (vascular tissue and pith) from the same plant for all species studied on all dates. Desert woody legumes had a higher d13C (less negative) and a lower intercellular CO2 concentration (Ci ) (for both photosynthetic tissues) than that of woody legumes from mediterranean climate sites. Differences in the d13C of stems among sites could be entirely accounted for by differences among site air temperatures. Thus, the d13C composition of stems did not indicate a difference in whole-plant integrated water use efficiency (WUE) among sites. In contrast, stems on all plants had a lower stem Ci and a higher d13C than leaves on the same plant, indicating that photosynthetic stems improve long-term, whole-plant water use efficiency in a diversity of species.

Is there a typical VDT patient? A demographic analysis

BACKGROUND

The use of video display terminals (VDT) in the workplace is growing rapidly. Visual problems associated with computer use are increasing apace. Recognizing and addressing these needs are vital tasks for the optometric practitioner. This paper examines the demographics, prevalence of symptoms, and other work- and vision-related factors among VDT workers. Understanding the characteristics of a typical patient can aid in developing effective treatment protocols.

METHODS

Twenty-two optometrists collected data from 324 patients who work on VDT screens for a minimum of 2 hours per day. A questionnaire was used to collect the data. Along with reporting the patients' dry manifest refraction results, the survey instrument also included a self-report of experienced symptoms.

RESULTS

The prototypical patient, based on the total subject population, is a 38-year old, mildly myopic female who uses the computer screen about 5 hours per day. Average total VDT work experience is about 5 years. Most of the patients use full-color screens and sit between 21 and 22 inches away from the screen. A variety of visual symptoms is reported, with eyestrain (65 percent) and headaches (42 percent) being the most common complaints.

CONCLUSIONS

Between 75 percent (results of this study) and 88 percent (reported by NIOSH) of patients who use a VDT regularly are likely to be symptomatic. This study has helped to identify the "typical" VDT user and the symptoms this user is most likely to report. The next step is to develop a diagnostic and treatment protocol by which optometrists can prescribe for and potentially prevent these computer-related vision problems.

Growth inhibition of a colonic adenocarcinoma cell line (HT29) by T cells specific for mutant p21 ras

Mutations at codons 12, 13 or 61 of the ras proto-oncogenes are found in adenocarcinomas of the colon and rectum. Mutated ras encode tumor-specific proteins, and can elicit CD4+ HLA-class-II-restricted T cell responses both in mouse and man. The function of such T cells is, however, unclear. In a model system, we investigated whether HLA-class-II restricted CD4+ T cells, specific for a particular peptide derived from mutant p21 ras (Gln61-->Leu), might inhibit the growth of a colonic cancer cell line, when it was cultured in the presence of the corresponding peptide. We found in this case that the growth of the colonic adenocarcinoma cell line HT29, when also induced to express HLA class II molecules by interferon gamma treatment, was inhibited. The inhibition was peptide-specific and required the presence of HLA-DQ8 molecules on the target cell. However, HLA-DQ8-expressing HT29 cells functioned poorly as antigen-presenting cells and could only induce a weak proliferative T cell response in the presence of interleukin-2. The results suggest that colonic cancer cells expressing peptides derived from mutant p21 ras protein in a complex with HLA class II molecules may be a target for tumor-specific T cells. The results also indicate, however, that an initiation of the immune response will require "professional" antigen-presenting cells.

[Haemophilus influenzae B meningitis and Waterhouse-Friderichsen syndrome in a 5-month-old infant]

A five months old infant with Waterhouse-Friderichsen syndrome related to Haemophilus influenzae type b meningitis is reported. In spite of treatment with IV fluids, antibiotics and dopamine, he died eight hours after admission. Necropsy findings included bilateral adrenal bleeding compatible with the Waterhouse-Friderichsen syndrome. This is the younger infant reported with this diagnosis in association with Haemophilus influenzae in Chile.

Advances in the use of computerized gas chromatography-mass spectrometry and high-performance liquid chromatography with rapid scanning detection for clinical diagnosis

A multi-component analytical system designed for the diagnosis of metabolic disorders is described. The urinary components are separated by a variety of chromatographic techniques, including automated amino acid analysis, high-performance liquid chromatography with diode-array detection and gas chromatography-mass spectrometry with a computerized mass spectral library search for identification of organic acids. The complete system can be used to diagnose over 100 different metabolic diseases. The usefulness of the chromatographic system is exemplified by the pre- and postnatal diagnosis of glutaric aciduria type I, the diagnosis of lysinuric protein intolerance and of alkaptonuria. Drugs and diet may cause interfering metabolites, as exemplified by glycofurol, used as a solvent for intravenous drugs, and saccharin. It is predicted that chromatography and mass spectrometry will continue to be important diagnostic tools for many years ahead.

Thrombin induces thromboplastin synthesis in cultured vascular endothelial cells

Cultured human umbilical vein endothelial cells responded to thrombin (10(-2) - 10 NIH u/ml) with a 2-5 fold increase in thromboplastin activity. The maximum response was reached after 4 hr in serum-free medium. The effect of thrombin was fully inhibited by the presence of 50% (v/v) fetal calf serum or more in the medium, by preincubation of thrombin with hirudin or by treatment of thrombin with N-bromosuccinimide or phenylmethylsulfonyl fluoride. The thrombin-induced thromboplastin activity was inhibited by incubation of the cells with cycloheximide (2 micrograms/ml) or actinomycin D (2 micrograms/ml) showing that the response depended on de novo protein and RNA synthesis. It was also suppressed by exposure of the cells to two different phosphodiesterase inhibitors, 3-butyl-1-methyl-xanthine (5 X 10(-4) M) and rac-4 (3-butoxy-4-methoxybenzyl)-2-imidazole (5 X 10(-4) M), to the transmethylation inhibitors 3-deazaadenosine (10(-5) M) and 1-homocysteine thiolactone (2 X 10(-5) M) in combination and to the intracellular calcium antagonist 8-(N,N-diethylamino)-octyl 3,4,5,-tri-methoxybenzoate hydrochloride (8 X 10(-5) M). Our results suggest that small amounts of thrombin can induce thromboplastin synthesis in endothelial cells in vitro and that this synthesis probably is regulated by the intracellular level of cAMP, by cytoplasmic Ca2+ and possibly also by transmethylation reactions.

The effect of thrombin on fibronectin in cultured human endothelial cells

Cultures of human endothelial cells (EC) incubated for periods up to 24 h with highly purified thrombin (2 NIH u/ml) contained considerably less cell-associated fibronectin fibrils than corresponding controls. The loss of fibronectin fibrils was evident after 4 h and was accompanied by a 2-3 fold increase in the concentration of fibronectin in the incubation medium. Hirudin inhibited the effects of thrombin. Thrombin also induced characteristic shape changes of EC. These shape changes were reversible within a 4-6 h period and could not be reinvoked by new additions of thrombin. Thus, structural refractoriness to thrombin coincided temporally with a period when EC-associated fibronectin fibrils were markedly reduced.

Effect of high-density lipoproteins on cholesterol efflux and esterification in lipid-enriched human skin fibroblasts

The ability of high-density lipoprotein (HDL) to reduce the cholesterol content was studied in cultured fibroblasts enriched with cholesterol esters. Incubation of cholesterol-enriched cells with HDL in a final concentration of 1 g protein/l for 24 h reduced the total and esterified cholesterol content by 23% as compared with control fibroblasts incubated with albumin. Similar cholesterol efflux was obtained with HDL isolated from lecithin:cholesterol acyltransferase (LCAT)-deficient plasma. The HDL3 subfraction isolated by rate-zonal ultracentrifugation contained the major part of the cholesterol-depleting effect. HDL or HDL3 decreased CoA:cholesterol acyltransferase (ACAT) activity to 5% of the level found in control fibroblasts within 8 h of incubation. These findings suggest that ACAT activity is sensitive to a pool of intracellular cholesterol, which can be mobilized by the addition of HDL to the culture medium, and that ACAT activity is a useful measure of cholesterol efflux from cultured fibroblasts.

Actin pools and actin microfilament organization in cultured human endothelial cells after exposure to thrombin

Human umbilical vein endothelial cells (HUVEC) in primary confluent cultures lost their normal polygonal shape and assumed a 'contracted' appearance as judged by phase contrast microscopy when exposed to highly purified bovine thrombin (2 N.I.H. u/ml). Total actin in thrombin-exposed cells did not differ from that of control cells, as measured by the deoxyribonuclease I inhibition assay. However, the monomeric actin pool (unpolymerized actin) in thrombin-treated HUVEC was c. 15% smaller (P less than 0.01) than in control HUVEC (in which it represented approximately 50% of total actin). Transmission electron microscopy showed that thrombin-stimulated HUVEC contained more and thicker bundles of filamentous actin than control cells. Polymerization of actin and reorganization of actin microfilaments may contribute to the shape changes of HUVEC induced by thrombin.

Inhibition of the thromboplastin response of endothelial cells in vitro

Confluent monolayers of human umbilical vein endothelial cells in culture responded with a 5-fold increase in thromboplastin (tissue factor) synthesis when exposed to 12-O-tetradecanoyl-phorbol-13-acetate (TPA) (50 ng/ml) or endotoxin (ETX) (25 micrograms/ml) for 16 hr. This induced thromboplastin synthesis was markedly inhibited by exposure of the cells to two different phosphodiesterase inhibitors, methylisobutylxanthine (MIX) and rac-4(3-butoxy-4-methoxybenzyl)-2-imidazole idinone (RO-20-1724) and to the transmethylation inhibitors 3-deazaadenosine (DZA) and 1-homocysteine thiolactone (Hcy) in combination. It was slightly (TPA) or not at all (ETX) inhibited upon exposure of the cells to the intracellular calcium antagonist 8-(N,N-diethylamino)-octyl 3,4, 5-trimethoxybenzoate hydrochloride (TMB-8). However, in the presence of MIX TMB-8 had a moderate additional inhibitory effect on TPA-induced thromboplastin response. The thromboplastin response of endothelial cells in vitro thus probably depends on transmethylation events for its full expression. It is also strongly modulated by the intracellular level of cAMP.

Thrombin-induced shape changes of cultured endothelial cells: metabolic and functional observations

Cultured human umbilical vein endothelial cells (EC) incubated in the presence of 2-deoxy-D-glucose (20 mmol/l) or at 4 degrees C lost their ability to undergo shape changes when exposed to thrombin (1 N.I.H. u/ml). Drugs blocking Ca++-flux (verapamil and nifedipin), microfilament disrupting agents (cytochalasin B and D) and microtubule disrupting agents (colchicine and colcemid) did not prevent thrombin-induced shape changes. None of the agents tested inhibited the accelerated thrombin-induced 51Cr-release from the cells. Pretreatment of EC with thrombin did not influence their ability to mediate clot retraction.

LDL-induced cytotoxicity and its inhibition by anti-oxidant treatment in cultured human endothelial cells and fibroblasts

Low density lipoproteins (LDL) isolated by ultracentrifugation induce cytotoxic changes in cultured human endothelial cells (EC) and fibroblasts if the ratio between LDL cholesterol and the final protein concentration of the culture medium exceeds 0.10-0.12 mmol/g protein. In order to investigate if reactive oxygen species could contribute to the cytotoxicity, LDL were prepared in the presence of the antioxidants butylated hydroxytoluene (BHT) or superoxide dismutase (SOD), while routinely prepared LDL from the same donors served as control (N-LDL). A radiochromium release assay was used to evaluate cellular injury. BHT treatment of the LDL fraction virtually abolished LDL-induced cytotoxicity in cultured human EC and fibroblasts. SOD-LDL offered partial protection against LDL cytotoxicity. A positive correlation between the cytotoxicity of the various fractions and their content of malondialdehyde (MDA) further supports our conclusion that lipid peroxides in the LDL fractions mediate the cytotoxic effect on cultured cells.

Injury to cultured human fibroblasts induced by low density lipoproteins: potentiating and protective factors

Low density lipoproteins (LDL) injured cultured fibroblasts provided a certain ratio existed between lipoproteins and infranatant proteins. The mechanism of action appeared similar to the mechanism whereby LDL injure endothelial cells in culture. Enrichment of normal fibroblasts with cholesterol esters by pretreatment with chloroquine and LDL potentiated injury inflicted by subsequent LDL exposure. Pretreatment with chloroquine alone offered partial protection against LDL-induced damage while indomethacin and sulphinpyrazone added prior to or together with LDL had no effect.

Synthesis of sterols and proteins in liver biopsies from obese patients subjected to gastric or jejunoileal bypass operations

Incorporation of 14C-acetate into digitonin-precipitable sterols and of 3H-leucine into proteins was examined in per- or post-operative liver biopsies from morbidly obese patients subjected to either gastric or jejunoileal bypass operations. Biopsies obtained from non-obese patients without liver disease served as controls. Incorporation of precursors into sterols and proteins in peroperative biopsies from obese patients (mean weight, 131 kg) did not differ from that of control subjects (mean weight, 64 kg). However, biopsies obtained from eight patients 11-53 months after jejunoileal bypass (mean weight loss, 32% of initial weight) showed an eightfold increased 14C incorporation into sterols, whereas incorporation of 3H-leucine into proteins did not differ from that of the control group. The results in postoperative biopsies (3-12 months) from 9 patients subjected to gastric bypass (mean weight loss, 25% of initial weight) did not differ significantly from those in 15 controls. The markedly stimulated biosynthesis of sterols in patients with jejunoileal bypass might reflect increased faecal excretion of cholesterol and bile acids, causing reduced feedback control mediated by bile acids and cholesterol.