Motor difficulties from childhood to midlife: A 40-year cohort study

BACKGROUND

There are few studies of the persistence of childhood motor difficulties (MD) into adulthood.

AIMS

To investigate the association of childhood MD with motor skills and body mass index (BMI) in midlife.

METHODS AND PROCEDURES

We studied 324 adults aged 40 from a cohort born in 1971-1974. At age 9, they had undergone the Test of Motor Impairment, used to classify them into groups: childhood MD (cMD), borderline cMD (bcMD), or no cMD. At age 40, participants comprised 23 with cMD, 47 with bcMD, and 254 with no cMD. Participants completed motor tests of balance, manual dexterity, and visuomotor speed, followed by recording of their BMI.

OUTCOMES AND RESULTS

At age 40, the cMD group performed worse than the no-cMD group on all motor tests (p < .001-.008). The bcMD group had slower visuomotor speed than the no-cMD group (p = .025). The groups differed in BMI (p = .002). Having cMD was associated with obesity in midlife (p < .001). After adjusting for sex, childhood socioeconomic status, and BMI at age 9, both cMD and bcMD were associated with obesity in midlife (p = .015).

CONCLUSIONS AND IMPLICATIONS

Childhood MD are associated with poor motor skills, overweight, and obesity in midlife. This emphasises the importance of early intervention and follow-up when a child exhibits MD.

WHAT THIS PAPER ADDS

This prospective longitudinal study presents novel evidence that individuals with a history of comprehensively and objectively assessed childhood motor difficulties (MD) have worse motor skills and a higher risk of obesity in midlife than do those with no childhood MD. There is a growing literature on adults with developmental coordination disorder or a history of MD. There is, however, a scarcity of longitudinal studies of childhood MD that continue beyond early adulthood, into midlife. In a systematic search, we could identify only one longitudinal study of objectively measured childhood MD with a reassessment of motor skills in those same participants in adulthood, and no study with a reassessment after age 20. Furthermore, longitudinal studies of the association of comprehensively and objectively assessed childhood MD with BMI in midlife have been lacking.

No Clinically Relevant Memory Effects in Perinatal Hyperglycemia and Hypoglycemia: A 40-Year Follow-Up of a Small Cohort

Maternal diabetes mellitus in pregnancy is associated with impairments in memory functions of the offspring in childhood and adolescence but has not been studied in adulthood. The association of perinatal hypoglycemia with memory has not been studied in adulthood either. The combined sequelae of these two risk factors have not been directly compared. We studied general cognitive ability and memory functions in a prospective follow-up of a cohort born in 1971 to 1974. The sample included participants exposed to prenatal hyperglycemia (n = 24), perinatal hypoglycemia (n = 19), or both (n = 7). It also included controls with no early risks (n = 82). We assessed the participants' Intelligence quotient (IQ), working memory, and immediate and delayed recall of both verbal and visual material at the age of 40. We did not find significant differences in IQ or the memory tests between the groups. We did identify an interaction (p = 0.03) of the early risk with the type of digit span task: compared to the controls, the participants exposed to perinatal hypoglycemia had a larger difference between the forward digit span, a measure of attention, and the backward digit span, a measure of working memory processing (p = 0.022). The interaction remained significant when birth weight was controlled for (p = 0.026). Thus, in this small cohort, prenatal hyperglycemia, perinatal hypoglycemia, and their combination appeared relatively benign disorders. The association of these conditions with neurocognitive impairments in adulthood remains unconfirmed. The significance of the working memory difference needs to be verified with a larger sample.

Mortality in individuals with childhood ADHD or subthreshold symptoms - a prospective perinatal risk cohort study over 40 years

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is associated with negative life outcomes and recent studies have linked it to increased mortality. These studies have examined nationwide registers or clinic-referred samples and mostly included participants up until the age of 30. No studies have investigated mortality associated with subthreshold levels of ADHD symptoms. Our aim was to analyze mortality in a perinatal risk cohort of 46-year-old adults with childhood ADHD (cADHD) and milder childhood attention problems (including hyperactivity and inattention; cAP) compared with a group with similar birth risks but no or low levels of childhood ADHD symptoms (Non-cAP). Causes of death obtained from a national register were examined.

METHODS

Mortality was analyzed with Cox proportional hazard models for all-cause mortality, cause-specific mortality (natural and unnatural causes), and age-specific mortality (under and over age 30). All models were adjusted with gender. The total n in the study was 839 (cADHD n = 115; cAP n = 216; Non-cAP n = 508).

RESULTS

By the age of 46, 11 (9.6%) deaths occurred in the cADHD group, 7 (3.2%) in the cAP group, and 20 (3.9%) in the Non-cAP group. The cADHD group had the highest mortality risk (adjusted hazard ratio = 2.15; 95% CI 1.02, 4.54). Mortality was not elevated in the cAP group (adjusted hazard ratio = 0.72; 95% CI .30, 1.72). Mortality in the cADHD group was mainly attributed to unnatural causes of death (adjusted hazard ratio = 2.82; 95% CI 1.12, 7.12). The mortality risk in the cADHD group was sixfold before age 30 (adjusted hazard ratio = 6.20; 95% CI 1.78, 21.57).

CONCLUSIONS

Childhood ADHD was associated with a twofold risk of premature death by the age of 46 in this prospective longitudinal cohort study. Our results corroborate previous findings and the morbidity of ADHD. Subthreshold levels of childhood ADHD symptoms were not linked to increased mortality. Our results suggest that mortality risk is higher in young than middle adulthood. Future studies should examine mortality associated with ADHD in different ages in adulthood to identify those in greatest risk of premature death.

No evidence for theta power as a marker of hypnotic state in highly hypnotizable subjects

EEG spectral-power density was analyzed in a group of nine highly hypnotizable subjects via ten frontal, central, parietal, and occipital electrodes under four conditions: 1) wake state, 2) neutral hypnosis, 3) hypnotic suggestion for altering perception of tones, and 4) post-hypnosis. Results indicate no theta-power changes between conditions, challenging previous findings that increased theta power is a marker of hypnosis. A decrease in gamma power under hypnotic suggestion and an almost significant decrease under neutral hypnosis were observed, compared to post-hypnosis. Anteroposterior power distribution remained stable over all conditions. The results are discussed and compared to earlier studies, which report heterogenous findings.

ADHD and subthreshold symptoms in childhood and life outcomes at 40 years in a prospective birth-risk cohort

We investigated ADHD symptoms and life outcomes in adulthood and their association with childhood ADHD and subthreshold symptoms in a prospectively followed cohort with perinatal risks. We identified participants with childhood ADHD (cADHD, n = 37), subthreshold symptoms defined as attention problems (cAP, n = 64), and no ADHD or cAP (Non-cAP, n = 217). We compared the groups and a control group with no perinatal risks (n = 64) on self-reported ADHD symptoms, executive dysfunction, and life outcomes in adulthood. At age 40, 21.6% of the cADHD, 6.3% of the cAP, 6.0% of the Non-cAP group, and 1.6% of the controls reached a screener cutoff for possible ADHD. The cADHD group had lower educational level, more ADHD symptoms and executive dysfunction, and higher rates of drug use than the other groups. Childhood ADHD associated with perinatal risks persists into midlife whereas childhood subthreshold ADHD symptoms in this cohort were not associated with negative outcomes in adulthood.

THE EFFECTS OF HYPNOSIS AND HYPNOTIC SUGGESTIONS ON THE MISMATCH NEGATIVITY IN HIGHLY HYPNOTIZABLE SUBJECTS

The neural mechanisms associated with hypnosis were investigated in a group of 9 high hypnotizable subjects by measuring the mismatch negativity (MMN) component of the auditory event-related potential (ERP). ERPs were recorded using a passive oddball paradigm to sinusoidal standard and deviant tone stimuli of 500 and 520 Hz, respectively, in four conditions: prehypnosis, neutral hypnosis, hypnotic suggestion for altering the tone perception, and posthypnotic conditions. Earlier studies have indicated that hypnosis and hypnotic suggestions might have an effect on MMN, but the results of our study contradict these results: No statistically significant differences were found between the conditions in the MMN amplitudes.

Temporal reprogramming of calcium signalling via crosstalk of gonadotrophin receptors that associate as functionally asymmetric heteromers

Signal crosstalk between distinct G protein-coupled receptors (GPCRs) is one mechanism that underlies pleiotropic signalling. Such crosstalk is also pertinent for GPCRs activated by gonadotrophic hormones; follicle-stimulating hormone (FSH) and luteinising hormone (LH), with specific relevance to female reproduction. Here, we demonstrate that gonadotrophin receptor crosstalk alters LH-induced Gαq/11-calcium profiles. LH-induced calcium signals in both heterologous and primary human granulosa cells were prolonged by FSHR coexpression via influx of extracellular calcium in a receptor specific manner. LHR/FSHR crosstalk involves Gαq/11 activation as a Gαq/11 inhibitor abolished calcium responses. Interestingly, the enhanced LH-mediated calcium signalling induced by FSHR co-expression was dependent on intracellular calcium store release and involved Gβγ. Biophysical analysis of receptor and Gαq interactions indicated that ligand-dependent association between LHR and Gαq was rearranged in the presence of FSHR, enabling FSHR to closely associate with Gαq following LHR activation. This suggests that crosstalk may occur via close associations as heteromers. Super-resolution imaging revealed that LHR and FSHR formed constitutive heteromers at the plasma membrane. Intriguingly, the ratio of LHR:FSHR in heterotetramers was specifically altered following LH treatment. We propose that functionally significant FSHR/LHR crosstalk reprograms LH-mediated calcium signalling at the interface of receptor-G protein via formation of asymmetric complexes.

Adult with Middle Interhemispheric Variant of Holoprosencephaly: Neuropsychological, Clinical, and Radiological Findings

OBJECTIVE

The middle interhemispheric variant of holoprosencephaly (MIHV) is a mild, rare variant of holoprosencephaly. Only a few cases of children with MIHV have been reported. Here we report in detail an adult case.

METHOD

The patient is a female in her 30s. The patient underwent an extensive neuropsychological examination, a neurological examination and a magnetic resonance imaging.

RESULTS

Neuroradiologically, the patient had a typical finding of MIHV, with the absence of the central corpus callosum and union of posterior frontal and anterior parietal gyri. In neuropsychological examination, the patient had average or above average performance in verbal comprehension, naming, reading and writing, and below average performance in perceptual reasoning, visuospatial abilities, processing speed and memory. Also difficulties in mathematical abilities, psychomotor skills, and executive functions were found. No gross neurological involvement was noted. She was diagnosed with atypical depression, post-traumatic stress disorder and a dissociative disorder in early adulthood. Despite cognitive deficits, she was able to achieve a tertiary level education.

CONCLUSIONS

This is the first adult case of MIHV described in detail. Our case emphasizes the possibility of a missed diagnosis of marked brain malformations in patients with craniofacial abnormalities. More cases and prospective follow-up studies are needed to understand the evolvement of both neuropsychological and psychiatric symptoms in these patients.

The impact of hypnotic suggestions on reaction times in continuous performance test in adults with ADHD and healthy controls

Attention is one of the key factors in both hypnotic processes and patients with ADHD. In addition, the brain areas associated with hypnosis and ADHD overlap in many respects. However, the use of hypnosis in ADHD patients has still received only minor attention in research. The main purpose of the present work was to investigate whether hypnosis and hypnotic suggestions influence the performance of adult ADHD (n = 27) and control participants (n = 31) in the continuous performance test (CPT). The hypnotic susceptibility of the participants was measured by the Harvard Group Scale of Hypnotic Susceptibility (HGSHS:A) and the attentional task was a three minute long auditory version of the CPT. The CPT task was administered four times: before hypnosis (CPT1), after a hypnotic induction (CPT2), after suggestions about speed and accuracy (CPT3), and after the termination of hypnosis (CPT4). The susceptibility of the groups measured by HGSHS:A did not differ. There was a statistically significant decrease in reaction times in both ADHD and control groups between CPT2 and CPT3. The differences between CPT1 and CPT2, even though non-significant, were different in the two groups: in the ADHD group reaction times decreased whereas in the control group they increased. Both groups made very few errors in the short CPT. This study indicates that hypnotic suggestions have an effect on reaction times in the sustained attention task both in adult ADHD patients and control subjects. The theoretical and clinical implications are discussed.

Attrition in a 30-year follow-up of a perinatal birth risk cohort: factors change with age

Background. Attrition is a major cause of potential bias in longitudinal studies and clinical trials. Attrition rate above 20% raises concern of the reliability of the results. Few studies have looked at the factors behind attrition in follow-ups spanning decades. Methods. We analyzed attrition and associated factors of a 30-year follow-up cohort of subjects who were born with perinatal risks for neurodevelopmental disorders. Attrition rates were calculated at different stages of follow-up and differences between responders and non-responders were tested. To find combinations of variables influencing attrition and investigate their relative importance at birth, 5, 9, 16 and 30 years of follow-up we used the random forest classification. Results. Initial loss of potential participants was 13%. Attrition was 16% at five, 24% at nine, 35% at 16 and 46% at 30 years. The only group difference that emerged between responders and non-responders was in socioeconomic status (SES). The variables identified by random forest classification analysis were classified into Birth related, Development related and SES related. Variables from all these categories contributed to attrition, but SES related variables were less important than birth and development associated variables. Classification accuracy ranged between 0.74 and 0.96 depending on age. Discussion. Lower SES is linked to attrition in many studies. Our results point to the importance of the growth and development related factors in a longitudinal study. Parents' decisions to participate depend on the characteristics of the child. The same association was also seen when the child, now grown up, decided to participate at 30 years. In addition, birth related medical variables are associated with the attrition still at the age of 30. Our results using a data mining approach suggest that attrition in longitudinal studies is influenced by complex interactions of a multitude of variables, which are not necessarily evident using other multivariate techniques.

Short cognitive behavioral therapy and cognitive training for adults with ADHD - a randomized controlled pilot study

In clinical practice, a growing need exists for effective non-pharmacological treatments of adult attention-deficit/hyperactivity disorder (ADHD). Here, we present the results of a pilot study of 10 adults with ADHD participating in short-term individual cognitive- behavioral therapy (CBT), 9 adults participating in cognitive training (CT), and 10 controls. Self-report questionnaires, independent evaluations, and computerized neurocognitive testing were collected before and after the treatments to evaluate change. There were distinctive pre-hypotheses regarding the treatments, and therefore the statistical comparisons were conducted in pairs: CBT vs control, CT vs control, and CBT vs CT. In a combined ADHD symptom score based on self-reports, 6 participants in CBT, 2 in CT and 2 controls improved. Using independent evaluations, improvement was found in 7 of the CBT participants, 2 of CT participants and 3 controls. There was no treatment-related improvement in cognitive performance. Thus, in the CBT group, some encouraging improvement was seen, although not as clearly as in previous research with longer interventions. In the CT group, there was improvement in the trained tasks but no generalization of the improvement to the tasks of the neurocognitive testing, the self- report questionnaires, or the independent evaluations. These preliminary results warrant further studies with more participants and with more elaborate cognitive testing.

Cognitive-behaviorally-oriented group rehabilitation of adults with ADHD: results of a 6-month follow-up

OBJECTIVE

Recently, novel psychological treatments for adult ADHD have been reported with promising results. However, studies about long-term treatment effects are scanty. The authors study effects of cognitive-behaviorally-oriented group rehabilitation during a 6-month follow-up.

METHOD

Participating in the rehabilitation were 29 adults, of whom 25 were reached 3 and 6 months later. ADHD and other psychiatric symptoms were assessed with self-ratings (Brown ADD Scale for Adults, Symptom Check List-90 [SCL-90], 16 ADHD-related items of SCL-90, Beck Depression Inventory). Participants from the pretreatment period served as their own controls.

RESULTS

Participants having improvement in ADHD symptoms during treatment (n = 11) maintained most of the benefit during follow-up. They also had a decrease in other psychiatric symptoms, but this did not fully persist through the follow-up. Of all participants, 72% found their overall situation improved as compared to the pretreatment situation.

CONCLUSION

Results suggest that cognitive-behaviorally-oriented group rehabilitation of ADHD adults might have long-term benefits.

Adults with ADHD benefit from cognitive-behaviorally oriented group rehabilitation: a study of 29 participants

OBJECTIVE

In clinical practice, a growing need exists for effective nonpharmacological treatments of adult ADHD. The authors present results from a cognitive-behaviorally oriented psychological group rehabilitation for adult ADHD.

METHOD

A total of 29 adults with ADHD participated. Rehabilitation consisted of 10 or 11 weekly sessions. Participants were assessed with self-ratings (checklist for ADHD based on the Diagnostic and Statistical Manual of Mental Disorders , Beck Depression Inventory II, Symptom Check List-90 [SCL-90], Brown ADD Scale for Adults [BADDS]), and the ratings of their significant others (BADDS) 3 months prior to treatment, at the beginning of treatment, and at the end of treatment. Also, the Wender Utah Rating Scale questionnaire was completed prior to rehabilitation.

RESULTS

Rehabilitation resulted in reduced self-reported symptoms in 16 ADHD-related items of SCL-90, BADDS total score, and BADDS subdomains of activation and affect.

CONCLUSION

Results suggest that cognitive-behavioral group rehabilitation can be suitable in treating adult ADHD.

The interaction between concrete pavement and corrosion-induced copper runoff from buildings

Changes in chemical speciation of copper and the capacity of concrete pavement to retain copper in runoff water from external buildings have been investigated at urban field conditions, and in parallel laboratory experiments simulating outdoor scenarios. The research study showed the concrete surface to form a copper rich surface layer ( approximately 50 microm thick) upon exposure, and a high capacity to significantly reduce the bioavailable fraction of released copper (20-95%). The retention capacity of copper varied between 5 and 20% during single runoff events in the laboratory, and between 10 and 40% of the total copper release during single natural runoff events. The capacity to retain and reduce the bioavailable fraction of non-retained copper increased with increasing wetness of the concrete surfaces, increasing pH of the runoff water and decreasing flow rates. Bioassay testing with bacterial and yeast bioreporters showed the bioavailable fraction of non-retained copper to be significantly lower than the total copper concentration in the runoff water, between 22 and 40% for bacteria and between 8 and 31% for yeast. The application of generated data to simulate a fictive outdoor scenario, suggests a significant reduction of bioavailable and total copper to background values during environmental entry as a result of dilution, and the interaction with solid surfaces, organic matter and complexing agents already in the drainage system.

Allergic sensitization and microbial load--a comparison between Finland and Russian Karelia

Epidemiological data have indicated that some infections are associated with a low risk of allergic diseases, thus supporting the idea (hygiene hypothesis) that the microbial load is an important environmental factor conferring protection against the development of allergies. We set out to test the hygiene hypothesis in a unique epidemiological setting in two socio-economically and culturally markedly different, although genetically related, populations living in geographically adjacent areas. The study cohorts included 266 schoolchildren from the Karelian Republic in Russia and 266 schoolchildren from Finland. The levels of total IgE and allergen-specific IgE for birch, cat and egg albumen were measured. Microbial antibodies were analysed against enteroviruses (coxsackievirus B4), hepatitis A virus, Helicobacter pylori and Toxoplasma gondii. Although total IgE level was higher in Russian Karelian children compared to their Finnish peers, the prevalence of allergen-specific IgE was lower among Russian Karelian children. The prevalence of microbial antibodies was, in turn, significantly more frequent in the Karelian children, reflecting the conspicuous difference in socio-economic background factors. Microbial infections were associated with lower risk of allergic sensitization in Russian Karelian children, enterovirus showing the strongest protective effect in a multivariate model. The present findings support the idea that exposure to certain infections, particularly in childhood, may protect from the development of atopy. Enterovirus infections represent a new candidate to the list of markers of such a protective environment. However, possible causal relationship needs to be confirmed in further studies.

Luminescent yeast cells entrapped in hydrogels for estrogenic endocrine disrupting chemical biodetection

In the construction of luminescent yeast cell based fibre-optic biosensors, we demonstrate a novel approach for estrogenic endocrine disrupting chemical (EDC) biodetection by entrapping genetically modified Saccharomyces cerevisiae cells, containing the estrogen receptor alpha-mediated expression of the luc reporter gene, in hydrogel matrices based on calcium alginate or PVA. In order to insure a significant signal, an optimal immobilization ratio of 1:2 alginate 3% (w/v): 5 x 10(6) [cells/ml], respectively, was used with the highest 17-beta-estradiol (beta-E2) induction factor after 2.5 h of incubation with 10[nM] beta-E2. It was shown that biocompatible alginate beads, 4.27-4.55 x 10(5) [CFU/bead], which were characterized by a detection limit of 0.08[microg l(-1)] and an EC50 of 0.64[microg l(-1)] for beta-E2, retained their viability for luminescence measurements after 1 month of storage at -80 degrees C slow freeze condition, and thus repeated cell cultivations were not required. The assay reproducibility for each tested EDC, represented by the coefficients of variation (CV), ranged from 4.35 to 18.47%. An alternative immobilization method, based on a room temperature partial drying of polyvinyl alcohol (PVA) solution (LentiKat Liquid) and cell suspension mix, was investigated with only a slightly lower detection limit for beta-E2 than that reported with alginate beads. Alginate yeast based hydrogels may also be applicable to the analysis of environmental water samples since the trend of detected estrogenic activities with alginate beads roughly correlated with LC-MS-MS analytical results.

Genetic and environmental factors in the immunopathogenesis of atopy: interaction of Helicobacter pylori infection and IL4 genetics

BACKGROUND

Both genetic and environmental factors, e.g. early childhood infections, have a role in the pathogenesis of atopic diseases.

OBJECTIVE

To examine simultaneously the strength and possible interactions of two known such factors, IL4 genetics and Helicobacter pylori infection, on the risk of atopy and asthma.

METHODS

Gene polymorphism analyses and skin prick tests (SPT) were determined in 245 adult asthmatics and 405 nonasthmatic controls of population-based case-control study. SPTs were used as an indicator of atopy. H. pylori infection was verified by detecting anti-H. pylori IgG antibodies in sera.

RESULTS

A significant negative association was seen between the presence H. pylori antibodies and SPT positivity (> or =1 positive reactions) in both asthmatics and controls (p = 0.002 and p = 0.025, respectively) but the effect of IL-4 polymorphism (SNP -590C/T) was nonsignificant in both groups (p = 0.071 and p = 0.072, respectively). However, IL4 genetics had an effect on susceptibility to H. pylori: asthmatics carrying the IL4 -590 allele T had a diminished risk to be H. pylori infected (OR 0.485 95%CI 0.287-0.819). This effect was not seen in controls. Logistic regression analysis indicated that H. pylori and IL4 effects on atopy risk are not interdependent.

CONCLUSIONS

This study showed that the effect of H. pylori infection on atopy risk is stronger than that of IL4 genetics. There is no interaction between these factors on the pathogenesis of atopy suggesting that these factors have distinct immunopathogenetic mechanisms. However, the genetic effect may modify the role of infective agents by effecting on susceptibility to disease.

IL-10 gene polymorphism and herpesvirus infections

Genetics has an important role in resistance to various infections and it also may modify the clinical picture of an infectious disease. Here, we briefly review our recent data demonstrating that the polymorphism of the IL-10 gene is associated with resistance to some common herpesviruses and, additionally, that this same gene is involved in the regulation of the severity of the infection and in the reactivation process.

One-step measurement of firefly luciferase activity in yeast

Firefly luciferase is often used as a sensitive genetic reporter in various cell types. The pitfall in yeast, however, has been the need to break down the rigid cells in order to measure the enzyme activity. In this study we have removed the peroxisomal targeting codons from the Photinus pyralis luciferase gene (luc) and shown that in the yeast Saccharomyces cerevisiae this modified luciferase gives high levels of light emission that is easy to measure from intact living cells. Furthermore, cells with the modified luciferase grew essentially faster than those with the wild-type luciferase, indicating that peroxisomal targeting of a foreign enzyme puts some constraints to cellular viability. As a model system we used two different reporter constructs. In the first, expression of the luciferase gene is under control of CUP1-promoter, a well known yeast promoter that is inducible by copper ions. In the second, luciferase activity is dependent on activation of the human oestrogen receptor and its interaction with oestrogen-responsive elements incorporated in a yeast promoter. The luciferase activity measurement could be done on a 96-well plate by simple addition of the substrate, D-luciferin, at a moderately acidic pH of 5.0. The ease of use of the non-peroxisomal luciferase makes it an interesting alternative for reporter genes that are conventionally used in yeast, such as lacZ.

Detection of organomercurials with sensor bacteria

Mercury and its organic compounds, especially methylmercury, are hazardous compounds that concentrate in biota via biomagnification and cause severe neurological disorders in animals. In this paper, a recombinant whole-cell bacterial sensor for the detection of the organic compounds of mercury was constructed. The sensor carries firefly luciferase gene as a reporter under the control of the mercury-inducible regulatory part of broad spectrum mer operon from pDU1358. In addition, a gene-encoding organomercurial lyase (an enzyme necessary for cleavage of the mercury-carbon bond) was coexpressed in the sensor strain. The sensitivity of the sensor was evaluated on some environmentally important organomercurial compounds. The lowest detectable concentrations were 0.2 nM (50 ng/L), 1 nM (0.34 microg/L), and 10 microM (2.3 mg/L) for methylmercury chloride, phenylmercury acetate, and dimethylmercury, respectively. The sensor responded also to inorganic mercury and, therefore, using the sensor described here together with sensor bacteria responding only to inorganic mercury, it should be possible to characterize the mercury contamination, for example, in environmental samples.

Susceptibility to primary Epstein-Barr virus infection is associated with interleukin-10 gene promoter polymorphism

In total, 116 children were investigated to determine whether the interleukin (IL)-10 polymorphism influences the age at primary Epstein-Barr virus (EBV) infection. The promoter of IL-10 is polymorphic, with 3 known single base substitutions (G/A at -1082, C/T at -819, and C/A at -592), which form 3 haplotypes: GCC, ACC, and ATA. This study found that carriage of the ATA haplotype protects against early EBV infection. The presence of the ATA haplotype was associated with EBV seronegativity (odds ratio, 2.6; 95% confidence interval, 1.04-6.7; P=.04), when controlled by age. To examine the effect of haplotypes on IL-10 production, IL-10 plasma levels were measured in 50 newborns and 400 adults and were correlated with the IL-10 haplotype. The IL-10 levels were significantly higher in the ATA carriers than in the noncarriers. These data suggest that the IL-10 ATA haplotype confers protection against primary EBV infection and that the effect is mediated by high IL-10 levels.

Construction and Use of Broad Host Range Mercury and Arsenite Sensor Plasmids in the Soil Bacterium Pseudomonas fluorescens OS8

We have generated new sensors for the specific detection and studies of bioavailability of metals by engineering Pseudomonas fluorescens with reporter gene systems. One broad host range mercury (pTPT11) and two arsenite (pTPT21 and pTPT31) sensor plasmids that express metal presence by luminescence phenotype were constructed and transferred into Escherichia coli DH5a and Pseudomonas fluorescens OS8. The maximal induction was reached after 2 h of incubation in metal solutions at room temperature (22 degrees C). In optimized conditions the half maximal velocity of reaction was achieved at acidic pH using a d-luciferin substrate concentration that was nearly sixfold lower for P. fluorescens OS8 than for E. coli DH5a. When using a luciferin concentration (150 mM) that was optimal for E. coli the luminescence declined rapidly in the case of Pseudomonas, for which the substrate level 25 mM gave a stable reading between about 20 min and 3 h. The ability of the strain OS8 to quantitatively detect specific heavy metals in spiked soil and soil extracts is as good, or even better in being a real-time reporter system, than that of a traditional chemical analysis. The Pseudomonas strain used is an isolate from pine rhizosphere in oil and heavy metal contaminated soil. It is also a good humus soil colonizer and is therefore a good candidate for measuring soil heavy metal bioavailability.

A group-specific microbiological test for the detection of tetracycline residues in raw milk

The potentiality of using a luminescent Escherichia coli strain for the specific detection of tetracycline residues in raw bovine milk was investigated. The sensor cells contain a reporter plasmid carrying the bacterial luciferase operon of Photorhabdus luminescens under the control of the tetracycline responsive control region from transposon Tn10. Incubation of the cells with the sample containing tetracyclines increases the light emission of the sensor cells. The most sensitive tetracycline detection was achieved in 120 min and by using CDTA as a chelating agent in the assay. Heat-treatment of milk before the assay decreased the variations in background luminescence signals and in tetracycline-induced luminescence between different milk samples. The detection limits for tetracycline, oxytetracycline, chlortetracycline, doxycycline, methacycline, demeclocycline, and minocycline were between 2 and 35 ng/mL. Nontetracycline antibiotics did not significantly interfere with the detection of tetracyclines.

Qualitative detection of tetracycline residues in milk with a luminescence-based microbial method: the effect of milk composition and assay performance in relation to an immunoassay and a microbial inhibition assay

Performance of Tet-Lux, a newly developed microbiological test for the detection of tetracycline residues in raw milk, based on tetracycline-controlled luminescence activation of the test bacteria, was evaluated in bovine milks with variable amounts of somatic cells, bacteria, fat, protein, and natural inhibitory compounds. The sensitivity of Tet-Lux was also compared to a commercially available tetracycline immunoassay (Snap, Idexx Laboratories Inc.) and to a microbial inhibition test (Delvotest SP, Gist-Brogades). There were slight differences in the luminescence signals between different milk samples, but no single factor could be pointed out to be responsible for them. There appeared to be a modest inverse relationship between luminescence and increasing fat and protein content. The amount of somatic cells, bacteria, and the natural inhibitors lysozyme and lactoferrin did not affect the luminescence response. The test fulfilled the sensitivity requirement specified by the European Union (maximum residue limit 100 ng/ml for tetracyclines). The Tet-Lux test was clearly more sensitive to all tetracyclines tested (oxytetracycline, tetracycline, chlortetracycline, doxycycline, demeclocycline, methacycline, minocycline) than Delvotest SP, and for five tetracyclines out of seven more sensitive than Snap. The test provides a fast, simple, and robust microbial method for the qualitative detection of tetracycline residues in milk.

Measurement of firefly luciferase reporter gene activity from cells and lysates using Escherichia coli arsenite and mercury sensors

The structural gene encoding firefly luciferase from Photinus pyralis is a widely used reporter both in traditional monitoring of gene expression and in bacterial sensors. Its activity can be detected from living cells (in vivo) without disruption or from cell-free lysate (in vitro). We compared the two measurement methods by using an overall toxicity detecting strain Escherichia coli MC1061(pCSS810), a mercury-sensing strain E. coli MC1061(pTOO11), and two new arsenic sensor strains MC1061(pTOO31) and AW3110(pTOO31) which were constructed for this study. Plasmid pTOO31 was constructed by inserting the ars promoter and the arsR gene from plasmid R773 to control firefly luciferase gene expression. Both in vivo and in vitro methods correlated well with the strains tested [correlation coefficients R = 0.99484 and 0.99834] and gave highly comparable results with standard solutions of arsenite or mercury ions and from six environmental water samples spiked with the ions. Use of the in vivo method resulted in lower variation between replicates of the same sample (CVs ranging from 3.9 to 7.2%) and also between different samples (from 8.6 to 25.9%) compared to the in vitro method (CVs ranging from 8.6 to 17.8% for replicates and from 13.1 to 36.3% for different samples).

Luminescent bacterial sensor for cadmium and lead

A sensor plasmid was constructed by inserting the regulation unit from the cadA determinant of plasmid pI258 to control the expression of firefly luciferase. The resulting sensor plasmid pTOO24 is capable of replicating in Gram-positive and Gram-negative bacteria. The expression of the reporter gene as a function of added extracellular heavy metals was studied in Staphylococcus aureus strain RN4220 and Bacillus subtilis strain BR151. Strain RN4220(pTOO24) mainly responded to cadmium, lead and antimony, the lowest detectable concentrations being 10 nM, 33 nM and 1 nM respectively. Strain BR151(pTOO24) responded to cadmium, antimony, zinc and tin at concentrations starting from 3.3 nM, 33 nM, 1 microM, and 100 microM, respectively. The luminescence ratios between induced and uninduced cells, the induction coefficients, of strains RN4220(pTOO24) and BR151(pTOO24) were 23-50 and about 5, respectively. These results were obtained with only 2-3 h incubation times. Freeze-drying of the sensor strains had only moderate effects on the performance with respect to sensitivity or induction coefficients.

Determination of complement-mediated killing of bacteria by viability staining and bioluminescence

Complement-mediated killing of bacteria was monitored by flow cytometric, luminometric, and conventional plate counting methods. A flow cytometric determination of bacterial viability was carried out by using dual staining with a LIVE/DEAD BacLight bacterial viability kit. In addition to the viable cell population, several other populations emerged in the fluorescence histogram, and there was a dramatic decrease in the total cell count in the light-scattering histogram in the course of the complement reaction. To permit luminometric measurements, Bacillus subtilis and Escherichia coli were made bioluminescent by expressing an insect luciferase gene. Addition of substrate after the complement reaction resulted in bioluminescence, the level of which was a measure of the viable cell population. All three methods gave essentially the same killing rate, suggesting that the bacteriolytic activity of serum complement can be measured rapidly and conveniently by using viability stains or bioluminescence. In principle, any bacterial strain can be used for viability staining and flow cytometric analysis. For the bioluminescence measurements genetically engineered bacteria are needed, but the advantage is that it is possible to screen automatically a large number of samples.

Recombinant luminescent bacteria for measuring bioavailable arsenite and antimonite

Luminescent bacterial strains for the measurement of bioavailable arsenite and antimony were constructed. The expression of firefly luciferase was controlled by the regulatory unit of the ars operon of Staphylococcus aureus plasmid pI258 in recombinant plasmid pTOO21, with S. aureus RN4220, Bacillus subtilis BR151, and Escherichia coli MC1061 as host strains. Strain RN4220(pTOO21) was found to be the most sensitive for metal detection responding to arsenite, antimonite, and cadmium, the lowest detectable concentrations being 100, 33, and 330 nM, respectively. Strains BR151(pTOO21) and MC1061(pTOO21) responded to arsenite, arsenate, antimonite, and cadmium, the lowest detectable concentrations being 3.3 and 330 microM and 330 and 330 nM with BR151(pTOO21), respectively, and 3.3, 33, 3.3, and 33 microM with MC1061(pTOO21), respectively. In the absence of the mentioned ions, the expression of luciferase was repressed and only a small amount of background light was emitted. Other ions did not notably interfere with the measurement in any of the strains tested. Freeze-drying of the cells did not decrease the sensitivity of the detection of arsenite; however, the induction coefficients were somewhat lower.

Kinetic measurement of the membranolytic activity of serum complement using bioluminescent bacteria

A method for studying the kinetics of serum complement activity is presented. The assay utilises Escherichia coli and Bacillus subtilis cells which have been made bioluminescent by expressing an insect luciferase gene from Pyrophorus plagiophthalamus. The diffusion of the luciferase enzyme substrate through the cell membranes is very slow, and therefore a change in membrane permeability is seen as a change of the in vivo luminescence of the cells. Treatment of the bacteria with human serum resulted in a bell-shaped curve of in vivo luminescence since this procedure facilitates passage of the substrate to the cytoplasm. The time point of maximum light emission was dependent on serum dilution. In vivo luminescence also proved to be a good indicator of the viability of bacterial cells. Using C1q deficient serum, or following treatment of normal serum with EGTA and Mg2+ it was possible to separate the membranolytic activities of alternative and classical pathways.

Use of controlled luciferase expression to monitor chemicals affecting protein synthesis

In this article, we present a new bioluminescent test system for the screening of chemical compounds with an inhibitory effect on protein synthesis. The test is based on the measurement of real-time in vivo light production by Escherichia coli strains expressing different luciferase genes. The eukaryotic lucGR gene from Pyrophorus plagiophthalamus was found to be the best of three types of luciferase genes tested. Chemicals with known inhibitory effects on protein synthesis were used as test chemicals together with some general toxicants. The incubation of a test chemical with cells was performed either prior to or after the induction of protein synthesis, and the difference in the results of the two methods distinguishes the possible influence on protein synthesis from direct metabolic inhibition. Using lyophilized bacteria, the test is performed in less than an hour without any bacterial cultivation, which makes the test suitable for rapid and sensitive screening of chemicals or environmental samples. Compared with the standardized 50% inhibitory concentration calculation method of the bioluminescent cytotoxicity test, the more direct approach of calculation developed in this study proved to be more convenient than and as reliable as the standard method.

Real-time measurement of cell permeabilization with low-molecular-weight membranolytic agents

A new method for studying the action of membranolytic agents by simple measurement of light emitted from cells is described. It is based on the expression of the click beetle (Pyrophorus plagiophthalamus) luciferase gene (lucGR) in Escherichia coli, Bacillus subtilis and Spodoptera frugiperda cells in order to make them bioluminescent. The diffusion of the substrate for luciferase enzyme through the cell membranes is very low at physiological pH, and therefore a change in membrane permeability is seen as a change of in-vivo luminescence of cells. The cells used in this study represent different membrane structures, and thus allow a comparison of the reactions of the different membranes towards membranolytic agents in a real-time measurement. The dose-response data correlated well with target cell viable count. In addition, the time course of light emission as a consequence of permeabilizing compound is dose-dependent. The action of the compounds on prokaryotic and eukaryotic cells was found to be highly dependent on the permeabilizer used.

Nitric oxide donor-mediated killing of bioluminescent Escherichia coli

The antimicrobial activities of two nitric oxide-releasing compounds against Escherichia coli were investigated by using recombinant E. coli cloned with a luciferase gene from Pyrophorus plagiophthalamus. Since luciferase uses intracellular ATP to generate visible light which can be measured from living cells in real time, we wanted to compare the extent to which cell viability parallels light emission. Results from luminescence measurements and CFU counts were in good agreement, and the decrease in light emission was shown to provide a rapid and more sensitive indication of cytotoxicity.