Impact of methodological choices in comparative effectiveness studies: application in natalizumab versus fingolimod comparison among patients with multiple sclerosis

Background

Natalizumab and fingolimod are used as high-efficacy treatments in relapsing–remitting multiple sclerosis. Several observational studies comparing these two drugs have shown variable results, using different methods to control treatment indication bias and manage censoring. The objective of this empirical study was to elucidate the impact of methods of causal inference on the results of comparative effectiveness studies.

Methods

Data from three observational multiple sclerosis registries (MSBase, the Danish MS Registry and French OFSEP registry) were combined. Four clinical outcomes were studied. Propensity scores were used to match or weigh the compared groups, allowing for estimating average treatment effect for treated or average treatment effect for the entire population. Analyses were conducted both in intention-to-treat and per-protocol frameworks. The impact of the positivity assumption was also assessed.

Results

Overall, 5,148 relapsing–remitting multiple sclerosis patients were included. In this well-powered sample, the 95% confidence intervals of the estimates overlapped widely. Propensity scores weighting and propensity scores matching procedures led to consistent results. Some differences were observed between average treatment effect for the entire population and average treatment effect for treated estimates. Intention-to-treat analyses were more conservative than per-protocol analyses. The most pronounced irregularities in outcomes and propensity scores were introduced by violation of the positivity assumption.

Conclusions

This applied study elucidates the influence of methodological decisions on the results of comparative effectiveness studies of treatments for multiple sclerosis. According to our results, there are no material differences between conclusions obtained with propensity scores matching or propensity scores weighting given that a study is sufficiently powered, models are correctly specified and positivity assumption is fulfilled.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01623-8.

Validation of diffuse correlation spectroscopy against 15O-water PET for regional cerebral blood flow measurement in neonatal piglets

Diffuse correlation spectroscopy (DCS) can non-invasively and continuously asses regional cerebral blood flow (rCBF) at the cot-side by measuring a blood flow index (BFI) in non-traditional units of cm2/s. We have validated DCS against positron emission tomography using 15O-labeled water (15O-water PET) in a piglet model allowing us to derive a conversion formula for BFI to rCBF in conventional units (ml/100g/min). Neonatal piglets were continuously monitored by the BabyLux device integrating DCS and time resolved near infrared spectroscopy (TRS) while acquiring 15O-water PET scans at baseline, after injection of acetazolamide and during induced hypoxic episodes. BFI by DCS was highly correlated with rCBF (R = 0.94, p < 0.001) by PET. A scaling factor of 0.89 (limits of agreement for individual measurement: 0.56, 1.39)×109× (ml/100g/min)/(cm2/s) was used to derive baseline rCBF from baseline BFI measurements of another group of piglets and of healthy newborn infants showing an agreement with expected values. These results pave the way towards non-invasive, cot-side absolute CBF measurements by DCS on neonates.

Hybrid PET/MRI imaging in healthy unsedated newborn infants with quantitative rCBF measurements using 15O-water PET

In this study, a new hybrid PET/MRI method for quantitative regional cerebral blood flow (rCBF) measurements in healthy newborn infants was assessed and the low values of rCBF in white matter previously obtained by arterial spin labeling (ASL) were tested. Four healthy full-term newborn subjects were scanned in a PET/MRI scanner during natural sleep after median intravenous injection of 14 MBq ¹⁵O-water. Regional CBF was quantified using a one-tissue-compartment model employing an image-derived input function (IDIF) from the left ventricle. PET rCBF showed the highest values in the thalami, mesencephalon and brain stem and the lowest in cortex and unmyelinated white matter. The average global CBF was 17.8 ml/100 g/min. The average frontal and occipital unmyelinated white matter CBF was 10.3 ml/100 g/min and average thalamic CBF 31.3 ml/100 g/min. The average white matter/thalamic ratio CBF was 0.36, significantly higher than previous ASL data. The rCBF ASL measurements were all unsuccessful primarily owing to subject movement. In this study, we demonstrated for the first time, a minimally invasive PET/MRI method using low activity ¹⁵O-water PET for quantitative rCBF assessment in unsedated healthy newborn infants and found a white/grey matter CBF ratio similar to that of the adult human brain.

IUGR decreases cardiomyocyte endowment and alters cardiac metabolism in a sex- and cause-of-IUGR-specific manner

Intrauterine growth restriction (IUGR) increases the risk of ischemic heart disease in adulthood. Studies in rats suggest cardiac vulnerability is more pronounced in males and in offspring that were exposed to hypoxia in utero. Therefore, we aimed to test the hypotheses that 1) IUGR adolescent males, but not females, have fewer cardiomyocytes and altered expression of cardiometabolic genes compared with controls; and 2) IUGR due to hypoxia has a greater effect on these parameters compared with IUGR due to nutrient restriction. IUGR was induced in guinea pigs by maternal hypoxia (MH; 10% O₂, n = 9) or maternal nutrient restriction (MNR; ~30% reduction in food intake, n = 9) in the second half of pregnancy and compared with control ( n = 11). At 120 days of age, postmortem was performed and the left ventricle perfusion fixed for stereological determination of cardiomyocyte number or snap frozen to determine the abundance of cardiometabolic genes and proteins by quantitative RT-PCR and Western blotting, respectively. MH reduced the number of cardiomyocytes in female ( P < 0.05), but not male or MNR, adolescent offspring. Furthermore, IUGR males had decreased expression of genes responsible for fatty acid activation in the sarcoplasm ( FACS) and transport into the mitochondria ( AMPK-a₂ and ACC; P < 0.05) and females exposed to MH had increased activation/phosphorylation of AMP-activated protein kinase-α ( P < 0.05). We postulate that the changes in cardiomyocyte endowment and cardiac gene expression observed in the present study are a direct result of in utero programming, as offspring at this age did not suffer from obesity, hypertension, or left ventricular hypertrophy.

SOX17 regulates cholangiocyte differentiation and acts as a tumor suppressor in cholangiocarcinoma

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) is a biliary malignancy linked to genetic and epigenetic abnormalities, such as hypermethylation of SOX17 promoter. Here, the role of SOX17 in cholangiocyte differentiation and cholangiocarcinogenesis was studied.

METHODS

SOX17 expression/function was evaluated along the differentiation of human induced pluripotent stem cells (iPSC) into cholangiocytes, in the dedifferentiation process of normal human cholangiocytes (NHC) in culture and in cholangiocarcinogenesis. Lentiviruses for SOX17 overexpression or knockdown were used. Gene expression and DNA methylation profiling were performed.

RESULTS

SOX17 expression is induced in the last stage of cholangiocyte differentiation from iPSC and regulates the acquisition of biliary markers. SOX17 becomes downregulated in NHC undergoing dedifferentiation; experimental SOX17 knockdown in differentiated NHC downregulated biliary markers and promoted baseline and Wnt-dependent proliferation. SOX17 expression is lower in human CCA than in healthy tissue, which correlates with worse survival after tumor resection. In CCA cells, SOX17 overexpression decreased their tumorigenic capacity in murine xenograft models, which was related to increased oxidative stress and apoptosis. In contrast, SOX17 overexpression in NHC did not affect their survival but inhibited their baseline proliferation. In CCA cells, SOX17 inhibited migration, anchorage-independent growth and Wnt/β-catenin-dependent proliferation, and restored the expression of biliary markers and primary cilium length. In human CCA, SOX17 promoter was found hypermethylated and its expression inversely correlates with the methylation grade. In NHC, Wnt3a decreased SOX17 expression in a DNMT-dependent manner, whereas in CCA, DNMT1 inhibition or silencing upregulated SOX17.

CONCLUSIONS

SOX17 regulates the differentiation and maintenance of the biliary phenotype and functions as a tumor suppressor for CCA, being a potential prognostic marker and a promising therapeutic target.

LAY SUMMARY

Understanding the molecular mechanisms involved in the pathogenesis of CCA is key in finding new valuable diagnostic and prognostic biomarkers, as well as therapeutic targets. This study provides evidence that SOX17 regulates the differentiation and maintenance of the biliary phenotype, and its downregulation promotes their tumorigenic transformation. SOX17 acts as a tumor suppressor in CCA and its genetic, molecular and/or pharmacological restoration may represent a new promising therapeutic strategy. Moreover, SOX17 expression correlates with the outcome of patients after tumor resection, being a potential prognostic biomarker.

Breaking up Prolonged Sitting does not Alter Postprandial Glycemia in Young, Normal-Weight Men and Women

A randomized, controlled, cross-over study was used to investigate the effects of breaking up prolonged sitting with low intensity physical activity on postprandial blood glucose concentrations in healthy, young, normal-weight adults. 14 men (n=6) and women (n=8) were assigned to 2.5 h of prolonged sitting (CON) and 2.5 h of prolonged sitting with 2-min bouts of walking every 20 min (LIPA). After ingesting a standardized test drink, capillary blood was sampled every 10 min to establish a postprandial blood glucose profile. Based on individual glucose responses, peak blood glucose, time-to-peak glucose, and incremental area under the glucose curve (iAUC) were determined. Paired sample t-tests were used to detect differences between trials. Peak blood glucose (p=0.55) and iAUC (CON: 252 mmol·L^-1·2.5 h^-1 [163-340]; LIPA: 214 mmol·L^-1·2.5 h^-1 [146-282]; p=0.45) were not different between trials. Also, time-to-peak glucose was not different between LIPA and CON (p=0.37). Taking advantage of high temporal resolution blood glucose profiles, we showed that breaking up prolonged sitting with low-intensity physical activity does not alter the postprandial blood glucose response in young, healthy, normal-weight adults. Our results indicate that postprandial glycemic control is maintained during prolonged sitting in young, healthy adults.

Myasthenia gravis and risks for comorbidity

Myasthenia gravis (MG) is an autoimmune disorder leading to skeletal muscle weakness and fatigability. MG subgroups are defined according to pathogenetic autoantibody (against acetylcholine receptor, muscle-specific tyrosine kinase or lipoprotein receptor-related protein 4), thymus pathology and clinical manifestations. MG patients have an increased risk for concordant autoimmune disease, in particular with early onset MG. Most common comorbidities are thyroid disease, systemic lupus erythematosus and rheumatoid arthritis. Cardiomyositis and subclinical heart dysfunction have been described in patients with thymoma MG and late onset MG but represent no major threat. A thymic lymphoepithelioma implies an increased risk for another cancer. Autoimmune MG represents no distinct cancer risk factor, although lymphomas and a few other cancer types have been reported with slightly increased frequency. Severe MG-related muscle weakness means a risk for respiratory failure and respiratory tract infection. Drug MG treatment can lead to side-effects. Thymectomy is regarded as a safe procedure both short and long term. Non-MG-related comorbidity represents a diagnostic and therapeutic challenge, especially in elderly patients. Diagnostic accuracy and optimal follow-up is necessary to identify and treat all types of coexisting disease in MG.

Total drug treatment and comorbidity in myasthenia gravis: a population-based cohort study

Background and purpose

Comorbidity in myasthenia gravis (MG) is important for diagnosis, treatment and prognosis. Disease complexity was assessed by examining total drug treatment, immune therapy and comorbidity in a complete national MG cohort.

Methods

All recipients of the MG-specific drug pyridostigmine 2004–2010 registered in the compulsory Norwegian Prescription Database who met the inclusion criteria were included. The pyridostigmine group was compared with the general Norwegian population.

Results

Myasthenia gravis patients received co-medication more often than the controls for nearly all groups of medication, including insulins (95% confidence interval 2.0–3.7), thyroid therapy (1.7–2.5), antidepressants (1.3–1.7), anti-infectives (1.2–1.4), lipid-modifying agents (1.1–1.4) and immunomodulating agents (6.8–8.8).

Conclusions

Myasthenia gravis patients are more often treated with non-MG prescription drugs than controls, reflecting frequent co-medication and comorbidity.

Input-output properties of the soleus stretch reflex in spastic stroke patients and healthy subjects during walking

The input-output properties of the soleus stretch reflex during walking and sitting were examined in 11 spastic stroke patients and 10 healthy subjects. In the early swing phase, the threshold of the input-output relation was significantly lower in the patient group - on average 108°/s compared to 309°/s in the control group (P=0.02). The slope of the input-output properties was unchanged in patients and in control subjects (P=0.39). In stroke patients we found a minor, but significant, difference in threshold with 108°/s in the early swing phase compared to 74°/s in sitting position at matched TA EMG activity (P=0.01). Furthermore, we found an unchanged slope of 0.25μVs/° during walking and 0.28μVs/° in the sitting position (P=0.21). In contrast, control subjects showed a large difference in the threshold in the early swing phase during walking (309°/s) compared with findings in the sitting position at a matched TA EMG activity (71°/s, P=0.004). The slope was unchanged during walking and when the subject was sitting (P=0.22). There was a significant correlation between clinical spasticity score and stretch reflex threshold in the early swing phase (P=-0.61, P=0.04) and between clinical spasticity score and the slope in the early swing phase (P=0.72, P=0.009). It is concluded that in the early swing phase, the markedly reduced soleus stretch reflex threshold was preventing the stroke patients from making fast dorsiflexion of the foot at the ankle joint and thereby impairing the walking speed.

Improving efficiency in stereology: a study applying the proportionator and the autodisector on virtual slides

Cell counting in stereology is time-consuming. The proportionator is a new stereological sampling method combining automatic image analysis and non-uniform sampling. The autodisector on virtual slides combines automatic generation of disector pairs with the use of digital images. The aim of the study was to investigate the time efficiency of the proportionator and the autodisector on virtual slides compared with traditional methods in a practical application, namely the estimation of osteoclast numbers in paws from mice with experimental arthritis and control mice. Tissue slides were scanned in a digital slide scanner and the autodisector was applied on the obtained virtual tissue slides. Every slide was partitioned into fields of view, and cells were counted in all of them. Based on the original exhaustive data set comprising 100% of fields of view and covering the total section area, a proportionator sampling and a systematic, uniform random sampling were simulated. We found that the proportionator was 50% to 90% more time efficient than systematic, uniform random sampling. The time efficiency of the autodisector on virtual slides was 60% to 100% better than the disector on tissue slides. We conclude that both the proportionator and the autodisector on virtual slides may improve efficiency of cell counting in stereology.

Molecular targeting of CSN5 in human hepatocellular carcinoma: a mechanism of therapeutic response

Development of targeted therapy for hepatocellular carcinoma (HCC) remains a major challenge. We have recently identified an elevated expression of the fifth subunit of COP9 signalosome (CSN5) in early HCC as compared to dysplastic stage. In the present study, we explored the possibility of CSN5 being a potential therapeutic target for HCC. Our results show that CSN5 knockdown by small interfering (si) RNA caused a strong induction of apoptosis and inhibition of cell cycle progression in HCC cells in vitro. The downregulation of CSN5 was sufficient to interfere with CSN function as evidenced by the accumulation of neddylated Cullin1 and changes in the protein levels of CSN controlled substrates SKP2, p53, p27 and NF-kB, albeit to a different degree depending on the HCC cell line, which could account for the CSN5 knockdown phenotype. The transcriptomic analysis of CSN5 knockdown signature showed that the anti-proliferative effect was driven by a common subset of molecular alterations including downregulation of CDK6 and ITGB1, which were functionally interconnected with key oncogenic regulators MYC and TGFβ1 involved in the control of proliferation, apoptotic cell death and HCC progression. Consistent with microarray analysis, western blotting revealed that CSN5 depletion increased phosphorylation of Smad 2/3, key mediators of TGFβ1 signaling, decreased the protein levels of ITGB1, CDK6, and cyclin D1 and caused reduced expression of anti-apoptotic Bcl-2 while elevating the levels of pro-apoptotic Bak. A chemically modified variant of CSN5 siRNA was then selected for in vivo application based on the growth inhibitory effect and minimal induction of unwanted immune response. Systemic delivery of the CSN5 3/8 variant by stable-nucleic-acid-lipid-particles (SNALP) significantly suppressed the tumor growth in Huh7-luc⁺ orthotopic xenograft model. Taken together, these results indicate that CSN5 plays a pivotal role in HCC pathogenesis and maybe an attractive molecular target for systemic HCC therapy.

Myasthenia gravis requiring pyridostigmine treatment in a national population cohort

BACKGROUND

Pyridostigmine is the first drug of choice for patients with myasthenia gravis (MG). The drug is not prescribed regularly to any other patient groups. We aimed to determine the prevalence, incidence and gender-specific characteristics of patients with MG needing drug treatment in a well-defined population cohort.

METHODS

Data were retrieved from the Norwegian Prescription Database (NorPD) 2004-2007, containing information on all dispensed drugs in Norway. The study population comprised 677 recipients of pyridostigmine who met the following inclusion criteria (one or more): (i) More than one prescription 1 January 2004-31 December 2007, (ii) prescription from a specialist in neurology, (iii) prescription for MG being specified in NorPD.

RESULTS

A total of 435 (64%) women and 242 men were included; female:male ratio 1.8:1. Point prevalence (1 January 2008) of symptomatic MG was 131 per million; 92 for men, 170 for women. Seventy-four new users of pyridostigmine were registered in 2007 (42 women, 32 men), i.e. the incidence rate for 2007 being 16 per million; 14 for men, 18 for women. Mean age of incident cases was 59 years; 64 and 55 years, respectively. Prevalence and incidence were significantly higher in the age group ≥ 50 years than < 50 years (P < 0.001), and highest at 70-79 years. Prevalence and incidence did not differ in the five geographical health regions in Norway.

CONCLUSIONS

Reported prevalence and incidence are amongst the highest found in similar studies. This may be explained by optimal case identification, higher incidence of drug requiring MG amongst the elderly, and recurrences of previous MG.

The semi-automatic nucleator

The nucleator is a well-established manual stereological method of estimating mean cell volume from observations on random cell transects through reference points of the cells. In this paper, we present an automated version of the nucleator that uses automatic segmentation of the boundaries of the cell transects. An expert supervises the process. If the segmentation is judged to be satisfactory, an estimate of the cell volume is calculated automatically on the basis of the whole cell transect. In the remaining cases, the expert intervenes and uses the classical nucleator. The resulting estimator is called the semi-automatic nucleator. In this paper, we study the statistical properties of the semi-automatic nucleator. Formulae for the bias and mean square error are derived. The semi-automatic nucleator may have a small bias but will still in most cases be more efficient than the classical nucleator. Procedures for estimating bias and mean square error from a pilot study are provided. The application of the semi-automatic nucleator is illustrated in a study of somatostatin positive inhibitory interneurons which were genetically labelled with green fluorescent protein (GFP). The cells were sampled with an optical disector. The centre of mass in a central cell transect was used as reference point. It is found in this study that the number of cells needed for obtaining, for instance, a 5% precision of the estimate of mean cell volume is 150 and 189 for the semi-automatic and the classical nucleator, respectively. Taking into account that the time spent analysing one cell is shorter for the semi-automatic nucleator than for the classical nucleator, the semi-automatic nucleator is superior to the classical nucleator.

Power variations of wireless communication systems

The use of wireless digital communication devices like GSM, WCDMA, HSPA, DECT, and WiFi changes the exposure of electromagnetic waves toward the user. Concentrating on the power variations on a slow and fast time scale, these new systems are discussed. Experimental results for both uplink and downlink are included for a sample of systems. The spectrum of the power fluctuations is seen as a convenient and compact way of describing very complex system behavior. The results are of interest for scientific studies of epidemiology and biological effects, and for general electromagnetic compatibility (EMC) aspects.

Loss of miR-122 expression in liver cancer correlates with suppression of the hepatic phenotype and gain of metastatic properties

Growing evidence indicates that microRNAs have a significant role in tumor development and may constitute robust biomarkers for cancer diagnosis and prognosis. In this study, we evaluated the clinical and functional relevance of microRNA-122 (miR-122) expression in human hepatocellular carcinoma (HCC). We report that miR-122 is specifically repressed in a subset of primary tumors that are characterized by poor prognosis. We further show that the loss of miR-122 expression in tumor cells segregates with specific gene expression profiles linked to cancer progression, namely the suppression of hepatic phenotype and the acquisition of invasive properties. We identify liver-enriched transcription factors as central regulatory molecules in the gene networks associated with loss of miR-122, and provide evidence suggesting that miR-122 is under the transcriptional control of HNF1A, HNF3A and HNF3B. We further show that loss of miR-122 results in an increase of cell migration and invasion and that restoration of miR-122 reverses this phenotype. In conclusion, miR-122 is a marker of hepatocyte-specific differentiation and an important determinant in the control of cell migration and invasion. From a clinical point of view, our study emphasizes miR-122 as a diagnostic and prognostic marker for HCC progression.

Well-known quorum sensing inhibitors do not affect bacterial quorum sensing-regulated bean sprout spoilage

AIM

To investigate the potential of quorum sensing inhibitors (QSI) as food preservative agents in a food product, where bacterial spoilage is controlled by quorum sensing (QS).

METHODS AND RESULTS

The effects of well-known QSI were tested on spoilage phenotypes and on QS-regulated genes of a bean sprout spoiling bacterial isolate (Pectobacterium A2JM) in laboratory substrates and in a bean sprout model system. The acylated homoserine lactones (AHL) analogues PenS-AHL and HepS-AHL decreased the specific protease activity of Pectobacterium A2JM in broth but did not reduce the expression of a QS-regulated secretion protein, and were without effect on soft rot of bean sprouts. The QSI ProS-AHL, furanone C-30, patulin, penicillic acid and 4-nitropyridine-N-oxide did not have any effect on protease activity, on gene expression or bean sprout appearance at nongrowth inhibitory concentrations. Extracts from garlic and bean sprouts induced the QS system of Pectobacterium in bean sprouts and a broth system, respectively.

CONCLUSIONS

Among the several well-known QSI compounds, only PenS-AHL and HepS-AHL, inhibited QS-regulated protease activity of Pectobacterium A2JM in broth cultures, but had no effect on bean sprout spoilage.

SIGNIFICANCE AND IMPACT OF THE STUDY

The QSI compounds must be selected in the specific system in which they are to function and they cannot easily be transferred from one QS system to another.

Effects of social isolation and restraint on adrenocortical responses and hypoalgesia in loose-housed dairy cows1

Effects of social isolation or restraint, applied outside the home pen, on adrenocortical and nociceptive responses were examined in 28 loose-housed dairy cows. Treatments lasted 15 min and consisted of social isolation in novel surroundings or restraint by the head in a test pen. A control treatment was applied in the test pen as well. Each cow was exposed to all treatments in a balanced order, with 3 to 4 d between treatments. Compared with the control treatment, social isolation in novel surroundings led to increased plasma concentration of cortisol (P < 0.001) as well as to indications of hypoalgesia [posttreatment lack of decrease in latency to respond toward nociceptive laser stimulation, a tendency for decreased frequency of kicking in the pauses between laser stimulations (P = 0.06), and an increased proportion of leg moving (least possible active response) after treatment (P = 0.04)]. Indications of hypoalgesia were also observed after restraint (reduced kicking in response to laser stimulation, P = 0.04); however, the indications were to a lesser extent than after social isolation, and restraint treatment did not lead to increased plasma concentration of cortisol. For control and restraint treatment, an initial increase (P < 0.02) in plasma concentration of cortisol was found, suggesting effects of pretreatment factors such as handling. No correlations between adrenocortical and nociceptive responses toward social isolation were found. The results confirm earlier reports stating that nociceptive changes induced by environmental challenges can be shown in dairy cows, even when they are kept in groups and removed from the home pen during the study of stress responses. However, testing outside the home pen seemed to affect the nociceptive and adrenocortical responses, thereby suggesting that care should be taken to avoid effects of pretreatment situational factors.

Role of 2-5A-dependent RNase-L in senescence and longevity

Senescence is a permanent growth arrest that restricts the lifespan of primary cells in culture, and represents an in vitro model for aging. Senescence functions as a tumor suppressor mechanism that can be induced independent of replicative crisis by diverse stress stimuli. RNase-L mediates antiproliferative activities and functions as a tumor suppressor in prostate cancer, therefore, we examined a role for RNase-L in cellular senescence and aging. Ectopic expression of RNase-L induced a senescent morphology, a decrease in DNA synthesis, an increase in senescence-associated beta-galactosidase activity, and accelerated replicative senescence. In contrast, senescence was retarded in RNase-L-null fibroblasts compared with wild-type fibroblasts. Activation of endogenous RNase-L by 2-5A transfection induced distinct senescent and apoptotic responses in parental and Simian virus 40-transformed WI38 fibroblasts, respectively, demonstrating cell type specific differences in the antiproliferative response to RNase-L activation. Replicative senescence is a model for in vivo aging; therefore, genetic disruption of senescence effectors may impact lifespan. RNase-L-/- mice survived 31.7% (P<0.0001) longer than strain-matched RNase-L+/+ mice providing evidence for a physiological role for RNase-L in aging. These findings identify a novel role for RNase-L in senescence that may contribute to its tumor suppressive function and to the enhanced longevity of RNase-L-/- mice.

The interferon regulated ubiquitin-like protein, ISG15, in tumorigenesis: friend or foe?

The interferon-stimulated gene, 15 kDa (ISG15) is an interferon regulated gene that is induced as a primary response to diverse microbial and cell stress stimuli, and encodes the founding member of the ubiquitin-like protein family. ISG15 post-translationally modifies proteins via a pathway parallel to, and partially overlapping with, that of ubiquitin. In addition, ISG15 is released from cells to mediate extracellular cytokine-like activities. Although the biological activities of ISG15 have yet to be fully elucidated, it is clear that ISG15 has the capacity to modulate diverse cellular and physiologic functions. Consistent with this view, alterations in the ISG15 pathway have been identified in human tumors and in tumor cell lines. Here we review evidence of a role for ISG15 as an endogenous tumor suppressor that, when dysregulated in malignant cells, can be subverted to promote oncogenesis.

Stage-associated overexpression of the ubiquitin-like protein, ISG15, in bladder cancer

Bladder cancer is among the most prevalent malignancies, and is characterised by frequent tumour recurrences and localised inflammation, which may promote tissue invasion and metastasis. Microarray analysis was used to compare gene expression in normal bladder urothelium with that in tumours at different stages of progression. The innate immune response gene, interferon-stimulated gene 15 kDa (ISG15, GIP2), was highly expressed at all stages of bladder cancer as compared to normal urothelium. Western blotting revealed a tumour-associated expression of ISG15 protein. ISG15 exhibited a stage-associated expression, with significantly (P<0.05) higher levels of ISG15 protein in muscle-invasive T2-T4 tumours, compared with normal urothelium. Although ISG15 is involved in the primary immune response, ISG15 expression did not correlate with bladder inflammation. However, immunohistochemical staining revealed expression of ISG15 protein in both cancer cells and stromal immune cells. Interestingly, a significant fraction of ISG15 protein was localised to the nuclei of tumour cells, whereas no nuclear ISG15 staining was observed in ISG15-positive stromal cells. Taken together, our findings identify ISG15 as a novel component of bladder cancer-associated gene expression.

The effects of dry period versus continuous lactation on metabolic status and performance in periparturient cows

It has been argued that dairy cows with a high genetic milk production potential can maintain high milk production even with total omission of the dry period. Further, when omitting the dry period, cows are believed to experience fewer metabolic changes during the transition from late gestation to early lactation compared with cows having a traditional dry period. The performance and metabolic response to omission of the dry period for cows with an expected peak milk yield higher than 45 kg/d were studied in 28 Holstein dairy cows. The cows were followed in late gestation and in the subsequent 5 wk of early lactation. Fourteen cows were milked through late gestation (CM) and another 14 dairy cows underwent a 7-wk dry period (DRY). In the early lactation period, the cows had the same dry matter (DM) intake but cows in the CM group had a 22% reduction in milk yield compared with the cows in the DRY group. At calving, the experimental groups had the same average body weight and body condition score and there were no significant differences in body weight and body condition score changes in early lactation. However, the cows in the CM group compared with the cows in the DRY group had a higher plasma concentration of glucose and insulin and a lower plasma concentration of nonesterified fatty acids and beta-hydroxybutyrate in the following 5 wk of early lactation. Furthermore, the cows in the CM group had lower liver triacylglycerol concentration and higher liver glycogen concentration in the following early lactation. It is concluded that, even in dairy cows with an expected peak milk yield above 45 kg/d, omission of the dry period results in a relatively high reduction in milk yield in the following early lactation. Furthermore, these cows are in less metabolic imbalance in the following early lactation.

Mammary cell turnover and enzyme activity in dairy cows: effects of milking frequency and diet energy density

The aim of the study was to investigate the effects of diet energy density and milking frequency on mammary cell turnover and synthetic capacity in dairy cows. Experiment 1 used 20 dairy cows. From d 4 to wk 16 postpartum, the cows were fed either a low-energy density or a high-energy density diet. From d 4 through wk 8, half of the cows in each group were milked 3 times (3x) or 2 times (2x) daily. From wk 9 to 16, all cows were milked 2 times daily. Mammary biopsies were obtained at wk 8 and 16 postpartum. In experiment 2, udders of 18 individual cows were milked diagonally 2x and 4x, and biopsies were obtained after 7 d. In experiment 1, cows on the low-energy density diet yielded 17 and 24% less milk during wk 3 to 8 and wk 11 to 16 postpartum, respectively. Furthermore, at 8 wk postpartum, mammary enzyme activities tended to be lower and mammary cell proliferation was lower in cows on the low-energy density diet. Three times daily milking during the first 8 wk postpartum resulted in 11% higher milk yield. Mammary cell turnover or enzyme activities were not significantly affected at 8 wk. The 3x milking for 8 wk resulted only in a transient carryover effect on milk yield and neither cell turnover nor enzyme activities were significantly affected at 16 wk postpartum. In experiment 2, mammary cell turnover and enzyme activity were unaffected after 7 d of 4x milking although milk yield increased by 18%. We conclude that nutrient restriction affects mammary cell turnover and possible enzyme activity, and that tuning of negative feedback loops in response to filling of the gland may be the dominating effects of changes in milking frequency.

Nonbioluminescent strains of Photobacterium phosphoreum produce the cell-to-cell communication signal N-(3-Hydroxyoctanoyl)homoserine lactone

Bioluminescence is a common phenotype in marine bacteria, such as Vibrio and Photobacterium species, and can be quorum regulated by N-acylated homoserine lactones (AHLs). We extracted a molecule that induced a bacterial AHL monitor (Agrobacterium tumefaciens NT1 [pZLR4]) from packed cod fillets, which spoil due to growth of Photobacterium phosphoreum. Interestingly, AHLs were produced by 13 nonbioluminescent strains of P. phosphoreum isolated from the product. Of 177 strains of P. phosphoreum (including 18 isolates from this study), none of 74 bioluminescent strains elicited a reaction in the AHL monitor, whereas 48 of 103 nonbioluminescent strains did produce AHLs. AHLs were also detected in Aeromonas spp., but not in Shewanella strains. Thin-layer chromatographic profiles of cod extracts and P. phosphoreum culture supernatants identified a molecule similar in relative mobility (Rf value) and shape to N-(3-hydroxyoctanoyl)homoserine lactone, and the presence of this molecule in culture supernatants from a nonbioluminescent strain of P. phosphoreum was confirmed by high-performance liquid chromatography-positive electrospray high-resolution mass spectrometry. Bioluminescence (in a non-AHL-producing strain of P. phosphoreum) was strongly up-regulated during growth, whereas AHL production in a nonbioluminescent strain of P. phosphoreum appeared constitutive. AHLs apparently did not influence bioluminescence, as the addition of neither synthetic AHLs nor supernatants delayed or reduced this phenotype in luminescent strains of P. phosphoreum. The phenotypes of nonbioluminescent P. phosphoreum strains regulated by AHLs remains to be elucidated.

Effects of diet energy density and milking frequency in early lactation on tumor necrosis factor-alpha responsiveness in dairy cows

A whole blood stimulation assay (WBA) with Escherichia coli lipopolysaccharide (LPS) and an enzyme-linked immunosorbent assay (ELISA) were established to measure the production of tumor necrosis factor-alpha (TNF-alpha) in bovine plasma. The assays were used to study the effect of time around parturition, and diet energy density, and milking frequency on TNF-alpha responsiveness of dairy cows in early lactation. Forty cows were included in a 2 x 2 factorial block design. One factor was high (H) versus low (L) diet energy density and the other factor was two versus three daily milkings. Blood samples were collected in weeks -3, -1, 2, 3, 5, 9, and 13 around parturition, and investigated for the TNF-alpha production ex vivo and CD14+ monocytes. The TNF-alpha response, CD14+ monocyte number, and CD14 expression level on monocytes were significantly increased in the weeks close to parturition. However, dips of varying sizes were observed for the measured parameters in week 3 after calving. Diet and milking frequency had no effect on the TNF-alpha response ex vivo or CD14 expression level on monocytes, but cows fed diet H had significantly higher numbers of CD14+ monocytes than cows fed diet L. The WBA with LPS was a fast reliable method for repeated measurements of TNF-alpha responsiveness in cattle. Previous findings of increased TNF-alpha responses in periparturient cows were confirmed, whereas diet energy concentration and milking frequency had no effect on the TNF-alpha responsiveness in early lactation.

Effect of energy density in the diet and milking frequency on plasma metabolites and hormones in early lactation dairy cows

The effects of energy density in the diet [low = 0.86 SFU/kg dry matter (DM) or high = 1.06 SFU/kg DM] and daily milking frequency (two or three times) in early lactation on plasma concentrations of metabolites and hormones were evaluated in 40 Holstein dairy cows arranged in a 2 x 2 factorial block design. The four treatment combinations were L2, L3, H2 and H3, and the experimental period comprised the first 8 weeks of lactation. Plasma glucose, insulin and insulin-like growth factor (IGF)-I concentrations were on average 8 (3.43 versus 3.19 mmol/l), 114 (41.6 versus 19.4 pmol/l) and 60% (91.9 versus 57.4 ng/ml) higher, whereas beta-hydroxybutyrate (BOHB), plasma urea nitrogen (PUN) and growth hormone (GH) concentrations were on average 18 (0.73 versus 0.89 mmol/l), 14 (7.18 versus 8.35 mmol/l), and 63% (1.0 versus 2.6 ng/ml) lower for cows fed diet H than for cows fed diet L. Cows milked three times daily had a 6% (3.20 versus 3.42 mmol/l) lower plasma glucose concentration and a 19% (0.88 versus 0.74 mmol/l) higher plasma concentration of BOHB compared with cows milked two times daily. Plasma non-esterified fatty acid (NEFA) concentration was not affected by either treatment. Overall, it is concluded that increasing the daily milking frequency creates a higher metabolic imbalance in early lactation. Cows in early lactation will benefit from receiving a high energy density diet and thereby avoid a too high metabolic imbalance when mobilizing body tissue in support of milk production.

Characterisation of the quadriceps stretch reflex during the transition from swing to stance phase of human walking

The main objective of this study was to characterize the stretch reflex response of the human thigh muscles to an unexpected knee flexion at the transition from stance to swing during walking. Eleven healthy subjects walked on a treadmill at their preferred speed. Reliable and constant knee flexions (6-12 degrees amplitude, 230-350 degrees /s velocity, 220 ms duration) were applied during the late swing and early stance phase of human walking by rotating the knee joint with a specifically designed portable stretch apparatus affixed to the left knee. Responses from rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), medial hamstrings (MH) and medial gastrocnemius (GM) were recorded via bipolar surface electromyograms (EMG). The onset of the response in the RF, VL and VM, remained stable and independent of the time in the step cycle when the stretch was applied. Across all subjects the response onset (mean +/- SD) occurred at 23+/-1, 24+/-1 and 23+/-1 ms for RF, VL and VM, respectively. The duration of the initial response was 90-110 ms, at which time the EMG signal returned towards baseline levels. Three reflex response windows, labelled the short latency reflex (SLR), the medium latency reflex (MLR) and the late latency reflex response (LLR), were analysed. The medium and late reflex responses of all knee extensors increased significantly ( p=0.008) as the gait cycle progressed from swing to stance. This was not related to the background EMG activity. In contrast, during standing at extensor EMG levels similar to those attained during walking the reflex responses were dependent on background EMG. During walking, LLR amplitudes expressed as a function of the background activity were on average two to three times greater than SLR and MLR reflex amplitudes. Distinct differences in SLR and LLR amplitude were observed for RF, VL and VM but not in the MLR amplitude. This may be related to the different pathways mediating the SLR, MLR and LLR components of the stretch response. As for the knee extensor antagonists, they exhibited a response to the stretch of the quadriceps at latencies short enough to be monosynaptic. This is in agreement with the suggestion by Eccles and Lundberg (1958) that there may be functional excitatory connections between the knee extensors and flexors in mammals.

Combined ACTH and glucocorticoid treatment improves survival and organ maturation in premature newborn calves

Glucocorticoids play an important role in prenatal organ maturation in many species. In humans, maternal treatment with synthetic glucocorticoids improves neonatal adaptation of prematurely born infants. In cows, pre-term calf survival is improved following a single maternal glucocorticoid administration. We hypothesized that stimulation of endogenous cortisol secretion by adrenocorticotropin (ACTH) treatment combined with maternal dexamethasone treatment, would be even more efficient in stimulating organ maturation in the prematurely delivered calf. Three groups of premature calves were delivered by caesarian section at 90% of gestation length from dams which were either untreated or injected with dexamethasone before delivery, combined with either prenatal or postnatal ACTH treatment to the calf. During the first 24h after birth, thermoregulation, blood chemistry, liver values and organ weights were recorded. In the untreated calves, survival was significantly correlated with blood oxygenation, sodium and calcium levels at the moment of birth. There were marked maturational effects of the treatments on body temperature regulation, blood acid-base status, oxygenation, glucose, insulin, IGF-1 levels, weight of the heart, liver, gastrointestinal tract and thymus weight. For many of the measured metabolic, endocrine and organ weight parameters, the intrauterine ACTH treatment was associated with improved values relative to the postnatal ACTH treatment, which appeared to have no immediate effect on calf viability. In conclusion, the premature calf delivered by caesarian section at 90% of gestation length showed blood chemistry, metabolic, endocrine and organ growth characteristics that indicated severe prematurity. However, the maturation of organ function in newborn premature calves following maternal glucocorticoid injections was further enhanced if is was preceded by intra-fetal injections of ACTH.

Synthetic furanones inhibit quorum-sensing and enhance bacterial clearance in Pseudomonas aeruginosa lung infection in mice

INTRODUCTION

Antibiotics are used to treat bacterial infections by killing the bacteria or inhibiting their growth, but resistance to antibiotics can develop readily. The discovery that bacterial quorum-sensing regulates bacterial virulence as well as the formation of biofilms opens up new ways to control certain bacterial infections. Furanone compounds capable of inhibiting bacterial quorum-sensing systems have been isolated from the marine macro alga Delisea pulchra.

OBJECTIVES

Two synthetic furanones were tested for their ability to attenuate bacterial virulence in the mouse models of chronic lung infection by targeting bacterial quorum-sensing without directly killing bacteria or inhibiting their growth.

METHODS

Study I. Mice with Escherichia coli MT102 [luxR-PluxI-gfp(ASV)] lung infection were injected intravenously with N-acyl homoserine lactones with or without furanones to test the interference of furanones with quorum-sensing. Study II. Mice with lung infection by Pseudomonas aeruginosa PAO1 [dsred, lasR-PlasB-gfp(ASV)] were injected intravenously with furanones to evaluate their inhibiting effects on quorum-sensing. Study III. Mice with P. aeruginosa PAO1 lung infection were treated with different doses of furanones to evaluate the therapeutic effects of furanones on the lung infection.

RESULTS

Furanones successfully interfered with N-acyl homoserine lactone and suppressed bacterial quorum-sensing in lungs, which resulted in decreases in expression of green fluorescent protein. Furanones accelerated lung bacterial clearance, and reduced the severity of lung pathology. In a lethal P. aeruginosa lung infection, treatment with furanone significantly prolonged the survival time of the mice.

CONCLUSION

Synthetic furanone compounds inhibited bacterial quorum-sensing in P. aeruginosa and exhibited favourable therapeutic effects on P. aeruginosa lung infection.

Antibiotic and biosurfactant properties of cyclic lipopeptides produced by fluorescent Pseudomonas spp. from the sugar beet rhizosphere

Cyclic lipopeptides (CLPs) with antibiotic and biosurfactant properties are produced by a number of soil bacteria, including fluorescent Pseudomonas spp. To provide new and efficient strains for the biological control of root-pathogenic fungi in agricultural crops, we isolated approximately 600 fluorescent Pseudomonas spp. from two different agricultural soils by using three different growth media. CLP production was observed in a large proportion of the strains (approximately 60%) inhabiting the sandy soil, compared to a low proportion (approximately 6%) in the loamy soil. Chemical structure analysis revealed that all CLPs could be clustered into two major groups, each consisting of four subgroups. The two major groups varied primarily in the number of amino acids in the cyclic peptide moiety, while each of the subgroups could be differentiated by substitutions of specific amino acids in the peptide moiety. Production of specific CLPs could be affiliated with Pseudomonas fluorescens strain groups belonging to biotype I, V, or VI. In vitro analysis using both purified CLPs and whole-cell P. fluorescens preparations demonstrated that all CLPs exhibited strong biosurfactant properties and that some also had antibiotic properties towards root-pathogenic microfungi. The CLP-producing P. fluorescens strains provide a useful resource for selection of biological control agents, whether a single strain or a consortium of strains was used to maximize the synergistic effect of multiple antagonistic traits in the inoculum.

Effect of energy density in the diet and milking frequency on hepatic long chain fatty acid oxidation in early lactating dairy cows

The objective of this study was to examine the effects of diet energy density (high versus low) and increased milk yield, induced by increased milking frequency (two versus three times daily), on the hepatic status of triacylglycerol (TAG) and glycogen content and hepatic long chain fatty acid (LCFA) oxidation capacity in early lactation in a 2 x 2 factorial design. Forty multiparous Danish-Holstein dairy cows were used from 8 weeks before to 8 weeks after calving. Liver biopsies and blood samples were taken in weeks -2, 2, and 7 from calving. The cows fed the high energy density diet, compared with the cows fed the low energy density diet, had an 18 and 28% higher milk production and net energy intake, respectively. Milk yield was increased by 10% when the cows were milked three times compared with twice daily. Complete (CO2 production) and incomplete (ketone body production) LCFA oxidation capacity in the liver were 35 and 32% higher, respectively, and liver TAG content was 48% lower for the cows fed the high energy density diet compared with the low energy density diet. Overall there was no effect of milking frequency on liver parameters. However, a significant interaction between diet and milking frequency showed that the cows milked three times daily and fed the low energy density diet had the lowest liver LCFA oxidation (CO2 and ketone body) capacity. Furthermore, these cows had the numerically highest liver TAG content. The results for liver LCFA metabolism are discussed in relation to the plasma concentration of metabolites and insulin. In conclusion, cows in early lactation given a high energy density diet will, in general, have a lower risk of high TAG infiltration in the liver.

Effects of hyperinsulinaemia under euglycaemic condition on liver fat metabolism in dairy cows in early and mid-lactation

The objective was to examine the effects of insulin under euglycaemic conditions on liver long chain fatty acids (LCFA) metabolism with special focus on the aetiology of hepatic lipidosis in early lactation. A 4-day hyperinsulinaemic-euglycaemic clamp (clamp) was conducted on four dairy cows starting in weeks 4 and 17 postpartum. Insulin was infused continuously (1 microg/kg BW per h) and a 50% glucose solution was infused to maintain euglycaemia. Liver biopsies were taken 6 days before, the last day of, and 5 days after the clamp, and blood samples were taken in the same period. In the liver tissue, the relative triglyceride content decreased (P < 0.01) and the glycogen content increased (P < 0.0001) in response to the clamp. Hepatic in vitro palmitate oxidation capacity was lowest during the clamp period and could be explained by a significant decrease in incomplete oxidation (ketogenesis) (P < 0.04) and a tendency to a decreased complete oxidation of palmitate (P < 0.10). Plasma non-esterified fatty acids concentration was decreased during the clamp in early lactation (P < 0.05) but there was no effect on the mid-lactation clamp. The present study shows that increased insulin under euglycaemic conditions seems to depress hepatic LCFA oxidation capacity. However, in terms of preventing hepatic lipidosis, the anti-lipolytic effect of insulin on adipose tissue, which results in decreased mobilization of and hence hepatic load with LCFA, appears more important.

Effects of a four-day hyperinsulinemic-euglycemic clamp in early and mid-lactation dairy cows on plasma concentrations of metabolites, hormones, and binding proteins

The effects of insulin, using a 4 d hyperinsulinemic-euglycemic clamp, on plasma concentrations of hormone, metabolites, and binding proteins were evaluated in four Holstein dairy cows during wk 4 and 17 of lactation. Insulin was infused at 1 microg/kg/hr for 96 hr during the clamp period. Compared with the pre-clamp period, plasma insulin concentrations increased 7-fold and 4-fold during the clamp periods in early and mid-lactation, respectively. The total amount of glucose infused was higher (P < 0.05) during the clamp in early lactation. The clamp decreased plasma concentrations of non-esterified fatty acids (P < 0.001) during early lactation while differences in mid-lactation were minor. The clamp also decreased plasma concentration of beta-hydroxybutyrate (P < 0.001), plasma urea nitrogen (P < 0.001), and true protein (P < 0.01) although the patterns of decline differed between early and mid-lactation. Growth hormone (GH) concentrations decreased (P < 0.001) and insulin-like growth factor-1 (IGF-1) increased (P < 0.01) during the clamp period suggesting a direct effect of insulin on the un-coupling of the GH/IGF-1 axis. Levels of IGF binding protein-2 (IGFBP-2) decreased (P < 0.01) during the clamp period. The relative proportion of IGFBP-2 decreased (P < 0.001) and that of IGFBP-3 increased (P < 0.001) during the clamp period. There were no interactions between the clamp period and stage of lactation on GH, IGF-1, or IGFBPs. Overall, most plasma variables measured were affected in the same way during the two clamps, but the pattern of change often varied with stage of lactation.

Group II muscle afferents probably contribute to the medium latency soleus stretch reflex during walking in humans

1. The objective of this study was to determine which afferents contribute to the medium latency response of the soleus stretch reflex resulting from an unexpected perturbation during human walking. 2. Fourteen healthy subjects walked on a treadmill at approximately 3.5 km h(-1) with the left ankle attached to a portable stretching device. The soleus stretch reflex was elicited by applying small amplitude (approximately 8 deg) dorsiflexion perturbations 200 ms after heel contact. 3. Short and medium latency responses were observed with latencies of 55 +/- 5 and 78 +/- 6 ms, respectively. The short latency response was velocity sensitive (P < 0.001), while the medium latency response was not (P = 0.725). 4. Nerve cooling increased the delay of the medium latency component to a greater extent than that of the short latency component (P < 0.005). 5. Ischaemia strongly decreased the short latency component (P = 0.004), whereas the medium latency component was unchanged (P = 0.437). 6. Two hours after the ingestion of tizanidine, an alpha(2)-adrenergic receptor agonist known to selectively depress the transmission in the group II afferent pathway, the medium latency reflex was strongly depressed (P = 0.007), whereas the short latency component was unchanged (P = 0.653). 7. An ankle block with lidocaine hydrochloride was performed to suppress the cutaneous afferents of the foot and ankle. Neither the short (P = 0.453) nor medium (P = 0.310) latency reflexes were changed. 8. Our results support the hypothesis that, during walking the medium latency component of the stretch reflex resulting from an unexpected perturbation is contributed to by group II muscle afferents.

Effects of temperature and oxygen availability on circulating catecholamines in the toad Bufo marinus

The release of catecholamines during hypoxia has received limited attention in amphibians and the adrenergic regulation of cardio-pulmonary functions is, therefore, not well understood at the organismic level. To describe the changes in plasma catecholamine concentrations, we exposed toads (Bufo marinus) to different levels of hypoxia at two temperatures (15 and 25 degrees C). In addition, blood oxygen binding properties were determined in vitro at 15 and 25 degrees C at two different pH values. Hypoxia elicited a significant increase in plasma catecholamines (adrenaline and noradrenaline) at both temperatures, in spite of a respiratory alkalosis. At 15 degrees C, the increase was from 2.6+/-1.0 in normoxia to 4.8+/-1.4 ng ml(-1) at an inspired oxygen fraction of 0.05. At 25 degrees C, the hypoxic release of catecholamines was significantly higher (maximum levels of 44.8+/-11.6 ng ml(-1)). Plasma noradrenaline concentration was elevated at the most severe hypoxic levels, suggestive of an adrenal release. The arterial oxygen threshold for catecholamine release were approximately 1.0 mmol O(2) l(-1) blood or a PaO(2) of 30 mmHg. The P(50) values at 15 degrees C were 23.5+/-0.7 and 28.9+/-1.0 mmHg at pH 7.98+/-0.01 and 7.62+/-0.02, respectively, and increased to 36.5+/-0.6 and 43.0+/-1.1 mmHg at pH 8.04+/-0.04 and 7.67+/-0.05, respectively, at 25 degrees C. The oxygen equilibrium curves were linear when transformed to Hill-plots and Hills n (the haemoglobin subunit co-operativity) ranged between 2.24 and 2.75. The in vitro blood O(2) binding properties corresponded well with in vivo data.

Transcranial magnetic stimulation and stretch reflexes in the tibialis anterior muscle during human walking

Stretch of the ankle dorsiflexors was applied at different times of the walking cycle in 17 human subjects. When the stretch was applied in the swing phase, only small and variable reflex responses were observed in the active tibialis anterior (TA) muscle. Two of the reflex responses that could be distinguished had latencies which were comparable with the early (M1) and late (M3)components of the three reflex responses (M1, M2 and M3) observed during tonic dorsiflexion in sitting subjects. In the stance phase a single very large response was consistently observed in the inactive TA muscle. The peak of this response had the same latency as the peak of M3, but in the majority of subjects the onset latency was shorter than that of M3. The TA reflex response in the stance phase was abolished by ischaemia of the lower leg at the same time as the soleus H-reflex, suggesting that large muscle afferents were involved in the generation of the response. Motor-evoked potentials (MEPs) elicited in the TA by transcranial magnetic stimulation (TMS) were strongly facilitated corresponding to the peak of the stretch response in the stance phase and the late reflex response in the swing phase. A similar facilitation was not observed corresponding to the earlier responses in the swing phase and the initial part of the response in stance. Prior stretch did not facilitate MEPs evoked by transcranial electrical stimulation in the swing phase of walking. However, in the stance phase MEPs elicited by strong electrical stimulation were facilitated by prior stretch to the same extent as the MEPs evoked by TMS. The large responses to stretch seen in the stance phase are consistent with the idea that stretch reflexes are mainly involved in securing the stability of the supporting leg during walking. It is suggested that a transcortical reflex pathway may be partly involved in the generation of the TA stretch responses during walking.

gfp-based N-acyl homoserine-lactone sensor systems for detection of bacterial communication

In order to perform single-cell analysis and online studies of N-acyl homoserine lactone (AHL)-mediated communication among bacteria, components of the Vibrio fischeri quorum sensor encoded by luxR-P(luxI) have been fused to modified versions of gfpmut3* genes encoding unstable green fluorescent proteins. Bacterial strains harboring this green fluorescent sensor detected a broad spectrum of AHL molecules and were capable of sensing the presence of 5 nM N-3-oxohexanoyl-L-homoserine lactone in the surroundings. In combination with epifluorescent microscopy, the sensitivity of the sensor enabled AHL detection at the single-cell level and allowed for real-time measurements of fluctuations in AHL concentrations. This green fluorescent AHL sensor provides a state-of-the-art tool for studies of communication between the individuals present in mixed bacterial communities.

Development and dynamics of Pseudomonas sp. biofilms

Pseudomonas sp. strain B13 and Pseudomonas putida OUS82 were genetically tagged with the green fluorescent protein and the Discosoma sp. red fluorescent protein, and the development and dynamics occurring in flow chamber-grown two-colored monospecies or mixed-species biofilms were investigated by the use of confocal scanning laser microscopy. Separate red or green fluorescent microcolonies were formed initially, suggesting that the initial small microcolonies were formed simply by growth of substratum attached cells and not by cell aggregation. Red fluorescent microcolonies containing a few green fluorescent cells and green fluorescent microcolonies containing a few red fluorescent cells were frequently observed in both monospecies and two-species biofilms, suggesting that the bacteria moved between the microcolonies. Rapid movement of P. putida OUS82 bacteria inside microcolonies was observed before a transition from compact microcolonies to loose irregularly shaped protruding structures occurred. Experiments involving a nonflagellated P. putida OUS82 mutant suggested that the movements between and inside microcolonies were flagellum driven. The results are discussed in relation to the prevailing hypothesis that biofilm bacteria are in a physiological state different from planktonic bacteria.

Evidence for transcortical reflex pathways in the lower limb of man

The existence of transcortical reflex pathways in the control of distal arm and hand muscles in man is now widely accepted. Much more controversy exists regarding a possible contribution of such reflexes to the control of leg muscles. It is often assumed that transcortical reflex pathways play no, or only a minor, role in the control of leg muscles. Transcortical reflex pathways according to this view are reserved for the control of the distal upper limb and are seen in close relation to the evolution of the primate hand. Here we review data, which provide evidence that transcortical reflexes do exist for lower limb muscles and may play a significant role in the control of at least some of these muscles. This evidence is based on animal research, recent experiments combining transcranial magnetic stimulation with peripheral electrical and mechanical stimulation in healthy subjects and neurological patients. We propose that afferent activity from muscle and skin may play a role in the regulation of bipedal gait through transcortical pathways.

Integration of metabolism and intake regulation: a review focusing on periparturient animals

There has been great interest in dry matter intake regulation in lactating dairy cattle to enhance performance and improve animal health and welfare. Predicting voluntary dry matter intake (VDMI) is complex and influenced by numerous factors relating to the diet, management, housing, environment and the animal. The objective of this review is to identify and discuss important metabolic factors involved in the regulation of VDMI and their integration with metabolism. We have described the adaptations of intake and metabolism and discussed mechanisms of intake regulation. Furthermore we have reviewed selected metabolic signals involved in intake regulation. A substantial dip in VDMI is initiated in late pregnancy and continues into early lactation. This dip has traditionally been interpreted as caused by physical constraints, but this role is most likely overemphasized. The dip in intake coincides with changes in reproductive status, fat mass, and metabolic changes in support of lactation, and we have described metabolic signals that may play an equally important role in intake regulation. These signals include nutrients, metabolites, reproductive hormones, stress hormones, leptin, insulin, gut peptides, cytokines, and neuropeptides such as neuropeptide Y, galanin, and corticotrophin-releasing factor. The involvement of these signals in the periparturient dip in intake is discussed, and evidence supporting the integration of the regulation of intake and metabolism is presented. Still, much research is needed to clarify the complex regulation of VDMI in lactating dairy cows, particularly in the periparturient animal.

[Treatment of severe acute disseminated encephalomyelitis with intravenous immunoglobulin]

A three year-old boy with severe acute disseminated encephalomyelitis (ADEM) responding dramatically to treatment with intravenous immunoglobulin (IVIG) 1 g/kg/day is described. Initial treatment with intravenous methylprednisolone 2 mg/kg/day had failed. This and two earlier case reports indicate that IVIG might be efficient in the treatment of ADEM, and we believe that its use should be considered, at least in cases of severe ADEM with insufficient treatment effect of steroids. A synergistic effect of treatment with steroids and IVIG in ADEM is possible.

[Acute disseminated encephalomyelitis in children]

Acute disseminated encephalomyelitis (ADEM) is a demyelinating autoimmune inflammatory disease of the central nervous system. It is most often seen in children a few days to several weeks after certain infections or vaccinations. Clinically, ADEM can hardly be distinguished from primary viral encephalitis. The diagnosis is most frequently established on the basis of characteristic findings on MRI of the brain. Mostly the disease seems to be self-limiting, but in untreated patients the mortality rate may be as high as 20% and the risk of permanent neurological deficits 10-33%. Treatment with glucocorticoids seems to be effective in the majority of patients and should at least be started in all patients with an affected level of consciousness. Treatment with intravenous immunoglobulin has recently been given in a few patients with apparent success.

Major role for sensory feedback in soleus EMG activity in the stance phase of walking in man

1. Sensory feedback plays a major role in the regulation of the spinal neural locomotor circuitry in cats. The present study investigated whether sensory feedback also plays an important role during walking in 20 healthy human subjects, by arresting or unloading the ankle extensors 6 deg for 210 ms in the stance phase of gait. 2. During the stance phase of walking, unloading of the ankle extensors significantly (P < 0.05) reduced the soleus activity by 50 % in early and mid-stance at an average onset latency of 64 ms. 3. The onset and amplitude of the decrease in soleus activity produced by the unloading were unchanged when the common peroneal nerve, which innervates the ankle dorsiflexors, was reversibly blocked by local injection of lidocaine (n = 3). This demonstrated that the effect could not be caused by a peripherally mediated reciprocal inhibition from afferents in the antagonist nerves. 4. The onset and amplitude of the decrease in soleus activity produced by the unloading were also unchanged when ischaemia was induced in the leg by inflating a cuff placed around the thigh. At the same time, the group Ia-mediated short latency stretch reflex was completely abolished. This demonstrated that group Ia afferents were probably not responsible for the decrease of soleus activity produced by the unloading. 5. The findings demonstrate that afferent feedback from ankle extensors is of significant importance for the activation of these muscles in the stance phase of human walking. Group II and/or group Ib afferents are suggested to constitute an important part of this sensory feedback.

The influence of experimental muscle pain on the human soleus stretch reflex during sitting and walking

OBJECTIVES

The stretch reflex is functionally important during human locomotion. Muscle pain has been found to increase the stretch reflex amplitude during sitting, possibly due to an altered fusimotor drive. To further study the importance of altered fusimotor activity due to muscle pain we investigated the combined effect of muscle pain and motor task on the soleus stretch reflex.

METHODS

Stretch reflexes were elicited before, during and after experimentally induced muscle pain in soleus (i.m. infusion of 6% saline) in 3 experiments: (1) in the relaxed soleus muscle and before, during and after an isometric ramp contraction (500 ms, 0-10 Nm), (2) at 3 different time periods during walking, and (3) at matched pain intensity and soleus activity during sitting and walking.

RESULTS

Infusion of hypertonic saline into the soleus muscle caused a significant facilitated stretch reflex in the relaxed muscle (P<0.01), but not during walking or during sitting and walking at matched soleus EMG and matched pain levels. The infusion of isotonic saline (non-painful) did not cause any changes (P = 0.75).

CONCLUSIONS

The main findings of the present study were that experimental muscle pain facilitated the stretch reflex during pain in the relaxed muscle, but caused no changes in stretch reflex amplitude during sitting and walking at higher "functional" background EMG levels.

Metabolites of [(14)C]-5-(2-ethyl-2H-tetrazol-5-yl)-1-methyl-1,2,3, 6-tetrahydropyridine in mice, rats, dogs, and humans

The M1 muscarine agonist, 5-(2-ethyl-2H-tetrazol-5-yl)-1-methyl-1,2, 3,6-tetrahydropyridine (Lu 25-109), is extensively metabolized in mice, rats, dogs, and humans. The metabolite profile after an oral dose of [(14)C]Lu 25-109 was determined in plasma and in urine. Lu 25-109 was metabolized by N-demethylation (Lu 25-077), N-oxidation (Lu 32-181), and N-deethylation (Lu 31-126). In addition, combined N-demethylation and N-deethylation (Lu 31-190), and formation of a pyridine derivative took place (Lu 31-102). Lu 25-109 was also oxidized to pyridinium (Lu 29-297), 3-hydroxy-pyridinium (Lu 35-080), N-deethyl-2-pyridone (Lu 35-026), and a glucuronide of a 4, 6-dihydroxy-pyridinium ("m/z 398") compounds. A glucuronide of a dihydroxylated dihydro-pyridine compound ("m/z 400") was isolated from human urine, but not fully identified. In vitro studies were undertaken to elucidate the order of formation of the metabolites. In human plasma, the concentrations of Lu 25-109 and the pharmacologically active N-demethyl metabolite (Lu 25-077) were small compared with the N-oxide (Lu 32-181) and the N-deethyl-2-pyridone (Lu 35-026) at the first sample time (0.75 h). The N-deethyl metabolite (Lu 31-126) was the major component in human plasma between 3 and 10 h postdose. The major human metabolites in urine (Lu 32-181, Lu 35-026, and Lu 31-126) and the minor metabolites (Lu 25-077, Lu 35-080, Lu 31-190, and Lu 29-297) were all present in urine from rats, dogs, and mice, whereas m/z 398 was present in only mice and humans, and Lu 31-102 in only rats. The minor human metabolite m/z 400 was not detected in mice, rats, or dogs.