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Biomedical subjects

B Bjorvatn

Publications and source records attributed to B Bjorvatn.

At least 19 recordsLinked to original sources
PubMed2005

Tx-discs--no effect against subjective health complaints: a randomised controlled study.

BACKGROUND: Dowsers claim unhealthy effects of 'earth rays', and the producer of TX-discs claims that these discs may shield a person from the influence of 'earth rays', thereby relieving most illness in the person shielded. OBJECTIVES: To compare the effects of the TX-disc versus a placebo disc in patients with longstanding muscular-skeletal complaints. SETTING: Self-recruited community living persons in the Bergen area, Western Norway. PATIENTS: 67 women and 13 men with longstanding muscular-skeletal complaints, recruited by advertisements in local newspapers. DESIGN: A randomised and double-blinded controlled trial with a 6 months follow-up period. MAIN OUTCOME MEASUREMENT: The Subjective Health Complaints (SHC) questionnaire. RESULTS: We found a substantial reduction on the mean SHC sub-scale scores of muscular-skeletal, pseudo-neurological, gastro-intestinal, and allergic complaints, mainly occurring from baseline to 6 weeks (28-45%, P < 0.05-0.001). There were however no statistically significant differences for these variables between the TX group and the placebo group at any time point. IMPLICATIONS: TX-discs used in accordance with the instructions had no clinically or statistically significant effect on muscular-skeletal pain, pseudo-neurological complaints, gastro-intestinal, or allergic complaints during this study.

Chronic Disease↗
PubMed2003

Rapid colorimetric method for testing susceptibility of Mycobacterium tuberculosis to isoniazid and rifampin in liquid cultures.

We have developed a rapid colorimetric method for testing the susceptibility of M. tuberculosis to isoniazid (INH) and rifampin (RIF) based on incorporation of nitrate in broth cultures containing growth supplements. The performance of this colorimetric nitrate reductase-based antibiotic susceptibility (CONRAS) test was compared with that of the radiometric BACTEC 460TB system in determining the susceptibilities of 74 M. tuberculosis strains to INH and RIF. By using the BACTEC 460TB system as the "gold standard," the sensitivity (i.e., the ability to detect true drug resistance) and specificity (i.e., the ability to detect true drug susceptibility) of the CONRAS test were 100 and 95% for INH and 94 and 100% for RIF, respectively. The repeatability of the CONRAS test was excellent (for INH, kappa = 1 and P < 0.001; for RIF, kappa = 0.88 and P < 0.001). For the majority of strains, results were obtained within 5 days. The CONRAS test is rapid, accurate, and inexpensive and is an adequate alternative, particularly for resource-poor countries.

Antitubercular Agents↗
PubMed2002

Effects of sleep deprivation on extracellular serotonin in hippocampus and frontal cortex of the rat.

Sleep deprivation improves the mood of depressed patients, but the exact mechanism behind this effect is unclear. An enhancement of serotonergic neurotransmission has been suggested. In this study, we used in vivo microdialysis to monitor extracellular serotonin in the hippocampus and the frontal cortex of rats during an 8 h sleep deprivation period. These brain regions were selected since both have been implicated in depression. The behavioral state of the animal was continuously monitored by polygraphic recordings during the experiment. Sleep deprivation produced a gradual decline in extracellular serotonin levels, both in the hippocampus and in the frontal cortex. In order to investigate whether the reduction in serotonin was due to other factors than sleep deprivation, i.e. time of day effect, another experiment was performed. Here animals were allowed to sleep during most of the recording period. This experiment showed the expected changes in extracellular serotonin levels: consistently higher levels in the awake, non-sleep deprived animals compared to during sleep, but no time of day effect. The reduction in extracellular serotonin during sleep deprivation may suggest that serotonin does not play a major role in the mood-elevating effect of sleep deprivation. However, since 5-HT levels are strongly behavioral state dependent, by eliminating sleep, there may be a net increase in serotonergic neurotransmission during the sleep deprivation period.

Animals↗
PubMed2001

[Periodic limb movements in sleep--can and should this condition be treated?].

BACKGROUND: Periodic limb movements in sleep (PLMS) may occur in up to 6% of the general population and is more common in the elderly. MATERIAL AND METHODS: Based on relevant literature and recent guidelines from the American Academy of Sleep Medicine, we present an overview of symptoms, diagnostic examinations and treatment of periodic limb movements in sleep, including its relation to restless legs. A short case history is also presented. RESULTS: Patients with periodic limb movements in sleep may or may not have other symptoms, such as insomnia and excessive daytime sleepiness. Polysomnography is necessary for the diagnosis. Only patients who meet specific diagnostic criteria should be treated pharmacologically. Our patient was examined by polysomnography and actigraphy before and during pharmacological treatment. INTERPRETATION: The concept and treatment of periodic limb movements in sleep is controversial.

Adult↗
PubMed2001

Sleep and waking following microdialysis perfusion of the selective 5-HT1A receptor antagonist p-MPPI into the dorsal raphe nucleus in the freely moving rat.

The aim of this study was to examine the involvement of the dorsal raphe nucleus (DRN) presynaptic serotonergic 5-HT1A autoreceptors on sleep and waking parameters, in particular rapid eye movement (REM) sleep. In a previous study, the systemic administration of the selective 5-HT1A receptor antagonist p-MPPI reduced REM sleep in a dose-dependent manner suggesting a blockade of the 5-HT1A autoreceptors. In the present study, a blockade by microdialysis perfusion of 10 microM and 100 microM of p-MPPI for 7 h into the DRN in freely behaving rats influenced vigilance state only to a small extent. The administration of 10 microM of p-MPPI induced a reduction of total REM sleep mainly due to a suppression of REM sleep during the third 2 h period of the recording of sleep and waking. Perfusion of 100 microM of p-MPPI decreased total transition type sleep (TRANS) but the effect on REM sleep did not reach significance. There was no change in waking or slow wave sleep (SWS) following any of the doses. The data suggest that 5-HT1A receptor-mediated mechanisms in the DRN may be only moderately important in the serotonergic modulation of REM sleep.

Aminopyridines↗
PubMed2001

Polymorphism of the virulence regulon and allelic variations of the sic gene among the emm1 isolates of group A Streptococcus from western Norway.

With the objective of finding genetic markers of invasiveness, 43 isolates of group A streptococcus, isolated in western Norway and from both severe invasive disease and superficial infections, were studied initially by restriction fragment length polymorphism of the virulence regulon (virR -RFLP). Polymorphism that seemed to be related to the severity of infection was observed within the emm1 sequence type, which included 11 invasive and seven non-invasive isolates. These emm1 isolates were further investigated by restriction mapping of the virR and sequence analysis of a polymorphic region, which revealed the presence of a hypervariable sic gene. Of the nine distinct sic alleles, seven were found in single isolates, of which only two were from patients with invasive disease. The other two alleles were shared among nine invasive and two non-invasive isolates. The presence of only two sic allotypes in nine of the 11 invasive isolates, as compared to a different allele in each of the five non-invasive, contemporary isolates supports the hypothesis that selection of the sic variants occurs at mucosal surfaces and implicates mainly two clones among the invasive emm1 isolates.

Alleles↗
PubMed2001

The selective 5-HT(1A) receptor antagonist p-MPPI antagonizes sleep--waking and behavioural effects of 8-OH-DPAT in rats.

Systemic administration of the selective 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin HBr (8-OH-DPAT) increases waking and reduces slow wave sleep (SWS) and rapid eye movement (REM) sleep in the freely moving rat. The selective 5-HT(1A) antagonist 4-(2'-methoxy-phenyl)-1-[2'-(n-2"-pyridinyl)-p-iodobenzamido]-ethyl-piperazine (p-MPPI) induces a dose-related decrease in REM sleep. The present study examined p-MPPI's potential as an antagonist of the sleep and waking responses elicited by 8-OH-DPAT. Also, the experiments explored the ability of p-MPPI to block behavioural reactions of the 5-HT syndrome induced by 8-OH-DPAT, and whether p-MPPI induced any behavioural effects of its own. This study demonstrated that pre-treatment with p-MPPI (5 mg/kg intraperitoneal (i.p.)) 30 min before 8-OH-DPAT (0.375 mg/kg subcutaneously (s.c.)) reduced the effect of 8-OH-DPAT on waking and REM sleep. Also, p-MPPI (5 and 10 mg/kg i.p.) reduced the effect of 8-OH-DPAT on locomotion and partially or completely antagonized hindlimb abduction and flat body posture. No overt behavioural change was produced by p-MPPI alone. Thus, p-MPPI behaved as a true 5-HT(1A) antagonist.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2001

Rapid diagnosis of tuberculosis by detection of mycobacterial lipoarabinomannan in urine.

There is an urgent need for improved tools for laboratory diagnosis of active tuberculosis (TB). Here, we describe two methods, a catch-up ELISA and a dipstick test based on the detection in urine of lipoarabinomannan (LAM). LAM is a major and specific glycolipid component of the outer mycobacterial cell wall. Preliminary experiments showed that LAM is excreted in the urine of mice injected intraperitoneally with a crude cell wall preparation of Mycobacterium tuberculosis. Both methods were highly sensitive, detecting LAM at concentrations of 1 ng/ml and 5 pg/ml, respectively. Of 15 patients with active TB, all showed intermediate to high levels of LAM in their urine (absorbance values from 0.3 to 1.2, mean 0.74). Only one sample showed an absorbance value below the chosen cut off value of 0.4. All but one of the urine samples from 26 healthy nursing workers exhibited OD value below 0.4 cut off. These methods may prove valuable for rapid and simple diagnosis of TB in particular in developing countries lacking biosafety level 3 (BSL3) facilities.

Agglutination Tests↗
PubMed2001

Diagnostic evaluation of urinary lipoarabinomannan at an Ethiopian tuberculosis centre.

Direct capture enzyme-linked immunosorbent assay (ELISA) for lipoarabinomannan (LAM) was performed on urine samples from 200 tuberculosis (TB) patients and 800 non-TB patients routinely diagnosed among consecutive suspects in an Ethiopian TB centre. 50 healthy Ethiopians, 50 healthy individuals and 100 non-TB patients from Norway served as controls. Of the TB patients, 139 (69.5%) were positive for acid-fast bacilli (AFB). In the remaining cases the diagnosis was based on suggestive clinical findings. All Ethiopian non-TB patients were AFB negative and showed no clinical evidence of TB. In the Ethiopian groups, 148 (74%) of the TB patients, 105 (13.1%) of the non-TB patients and 5 (10%) of the healthy controls were positive by the LAM-ELISA. 113 (81.3%) of AFB positives and 35 (57.4%) of AFB-negative TB patients had positive LAM-ELISA. In the Norwegian groups all were LAM negative. The sensitivity and specificity of the LAM-ELISA for TB patients versus Ethiopian non-TB patients were 74% and 86.9%, respectively; the positive and negative predictive values were 58.5% and 93.0%. This study suggests that detection of LAM in the urine of TB patients may improve case finding and that diagnostic tests based on this principle may serve as valuable supplemental tools in TB control.

Adolescent↗
PubMed2000

Venlafaxine and its interaction with WAY 100635: effects on serotonergic unit activity and behavior in cats.

The therapeutic efficacy of antidepressant drugs that inhibit the reuptake of serotonin (5-hydroxytryptamine, 5-HT) may be enhanced by blocking their indirect activation of 5-HT(1A) autoreceptors, which mediate feedback inhibition of serotonergic neuronal activity. In this study, we examined the effects of venlafaxine, a dual 5-HT/noradrenaline reuptake inhibitor, alone and in combination with the selective 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohexanecarboxamide (WAY 100635), on the single-unit activity of serotonergic dorsal raphe neurons and concurrent behavior in freely moving cats. Systemic administration of venlafaxine (0.05-1.0 mg/kg, i.v.) produced a dose-dependent decrease in firing rate (ED(50)=0.19 mg/kg), with virtually complete inhibition of neuronal discharge at the highest dose tested. The subsequent administration of WAY 100635 (0.1 mg/kg, i.v.) rapidly reversed the neuronal suppression produced by venlafaxine and significantly elevated the firing rate above baseline levels. The overshoot in neuronal activity was associated with the onset of an adverse behavioral reaction resembling the 5-HT syndrome resulting from excessive levels of brain 5-HT. The intensity of this reaction paralleled the degree of neuronal restoration induced by WAY 100635, suggesting a causal relationship. Such behavioral responses were either not observed previously, or of a low intensity, when WAY 100635 was combined with selective 5-HT reuptake inhibitors. Overall, these results suggest that the risk of inducing adverse effects, such as the 5-HT syndrome, may be higher with dual 5-HT/noradrenaline reuptake inhibitors than with selective 5-HT reuptake inhibitors, when these agents are combined with a potent 5-HT(1A) autoreceptor antagonist. Possible mechanisms that might account for these differences in drug interaction are discussed.

Aminopyridines↗
PubMed2000

[Chronic sleep problems--possible to treat?].

Epidemiological studies show that approximately 10% of the population suffer from chronic insomnia. Insomnia can be classified as primary (without any obvious cause) or secondary to other disorders. Non-pharmacological treatment (i.e. sleep restriction, stimulus control treatment) is recommended in chronic primary insomnia, but this kind of treatment is unknown to most Norwegian health-care providers. This paper presents data from such treatment at a sleep disorders centre in Bergen, Norway. Twenty-two patients (10 men, 12 women; mean age 40 years) with chronic primary insomnia were included in the study. They had on average had insomnia for nine years. They went through a structured behavioural treatment regime with sleep restriction and stimulus control as the main components. Median number of consultations was five. The patients completed sleep diaries every week, from two weeks before the treatment started. Weekly averages obtained from the sleep diaries before and after behavioural treatment were statistically evaluated. Total wake time (summation of sleep-onset latency, wake after sleep onset and early morning awakening) was reduced by two hours. Sleep efficiency (total sleep time divided by time in bed) increased significantly from 65% to 86%. Total sleep time and subjective sleep quality also improved. The use of hypnotic medication was significantly reduced. The results indicate that this non-pharmacological treatment is effective in chronic primary insomnia, also in a Norwegian population. There was no control group in this study, and it should be interpreted with caution. However, randomized controlled trials from other countries document the efficacy of sleep restriction and stimulus control treatment in chronic insomnia.

Adult↗
PubMed2000

Molecular characterization and allelic distribution of the phage-mediated hyaluronidase genes hylP and hylP2 among group A streptococci from western Norway.

Forty-two isolates of group A streptococcus from patients with invasive and non-invasive diseases in western Norway, belonging to the emm sequence types emml, emm3, emm6, emm22, emm28, emm75 and emm78 were screened by PCR for the phage-mediated hyaluronidase genes hylP and hylP2. The amplified genes were characterized by nucleotide sequencing and/or by PCR-RFLP, with the objective of looking for possible associations between alleles of these two genes and invasiveness. The hylP was amplified from all isolates and two main alleles were found hylP-emm3 in all emm3 isolates and hylP-emm6A in all emm6 isolates, the latter possibly generated by an intergenic recombination between hylP and hylP2. The isolates of the other sequence types had either of these two alleles, or both. Only 27 isolates gave amplicons of the appropriate size with the primers targeting hylP2. Sequencing of these amplicons showed two main types: one was similar to the published hylP2 and the other (hylP-emm6B) was probably a variant of hylP. PCR-RFLP revealed the presence of both hylP-emm6B and hylP2 in at least six of the emm6 isolates. The alleles of both hylP and hylP2 seemed to have emm sequence type preferences. No association between invasiveness and specific phage-mediated hyaluronidase genes/alleles or the production of extracellular hyaluronidase was observed.

Alleles↗
PubMed2000

Sleep-wake effects following the selective 5-HT(1A) receptor antagonist p-MPPI in the freely moving rat.

The 5-HT(1A) receptors appear to play an important role in the serotonergic modulation of sleep and waking. Both presynaptic somatodendritic 5-HT(1A) autoreceptors and postsynaptic 5-HT(1A) heteroreceptors may be involved. The present study addressed the question of whether the selective 5-HT(1A) receptor antagonist 4-(2'-methoxy-phenyl)-1-[2'-(n-2"-pyridinyl)-p-iodobenzamido]-ethy l-p iperazine (p-MPPI) affected sleep and waking and whether such an effect would be dose-related. Polygraphic recording of sleep and waking in freely moving rats was employed following control injection and three doses of p-MPPI (1, 5 and 10 mg/kg i.p. in a balanced order design. Waking was increased and deep slow wave sleep decreased, while rapid eye movement (REM) sleep was suppressed over the first 6 h following injection, compared to after control injection. REM sleep was also suppressed following 10 mg/kg i.p. of p-MPPI as compared to following 1 mg/kg i.p. of p-MPPI. The interpretation of the effects is complex and the effects are not easily compatible with a simple model for serotonergic sleep-waking modulation. However, the REM sleep reduction probably reflects p-MPPIs ability to block the presynaptic 5-HT(1A) autoreceptors, increasing the firing activity in the serotonergic neurones and possibly inhibiting serotonin sensitive REM sleep active neurones.

Aminopyridines↗
PubMed2000

Serotonin and the sleep/wake cycle: special emphasis on microdialysis studies.

Several areas in the brainstem and forebrain are important for the modulation and expression of the sleep/wake cycle. Even if the first observations of biochemical events in relation to sleep were made only 40 years ago, it is now well established that several neurotransmitters, neuropeptides, and neurohormones are involved in the modulation of the sleep/wake cycle. Serotonin has been known for many years to play a role in the modulation of sleep, however, it is still very controversial how and where serotonin may operate this modulation. Early studies suggested that serotonin is necessary to obtain and maintain behavioral sleep (permissive role on sleep). However, more recent microdialysis experiments provide evidence that the level of serotonin during W is higher in most cortical and subcortical areas receiving serotonergic projections. In this view the level of extracellular serotonin would be consistent with the pattern of discharge of the DRN serotonergic neurons which show the highest firing rate during W, followed by a decrease in slow wave sleep and by virtual electrical silence during REM sleep. This suggests that during waking serotonin may complement the action of noradrenaline and acetylcholine in promoting cortical responsiveness and participate to the inhibition of REM-sleep effector neurons in the brainstem (inhibitory role on REM sleep). The apparent inconsistency between an inhibitory and a facilitatory role played by serotonin on sleep has at least two possible explanations. On the one hand serotonergic modulation on the sleep/wake cycle takes place through a multitude of post-synaptic receptors which mediate different or even opposite responses; on the other hand the achievement of a behavioral state depends on the complex interaction between the serotonergic and other neurotransmitter systems. The main aim of this commentary is to review the role of brain serotonin in relation to the sleep/wake cycle. In particular we highlight the importance of microdialysis for on-line monitoring of the level of serotonin in different areas of the brain across the sleep/wake cycle.

Animals↗
PubMed2000

Distribution and sequence variations of selected virulence genes among group A streptococcal isolates from western Norway.

In order to compare the distribution of selected virulence genes among group A streptococci recovered from invasive disease and superficial infections, 42 isolates were screened for mga, speB, speA, ssa and ska, by PCR. The isolates were predominantly of the sequence types emm1, emm3 and emm6, but also included a few of the types emm22, emm28, emm75 and emm78. The phage-mediated speA seemed to be prevalent in emm types 1 and 3, and its distribution was not related to disease severity. The other genes were present in all isolates. The mga, speB and speA were further studied by sequence analysis. Although allotypic associations with invasiveness were not found, allelic specificity to the emm sequence type was observed. In addition, the mga sequences indicated two lineages, related to opacity factor production. A possible recombination between these two main divergent mga genes was observed in isolates of the types emm22 and emm75. A logical nomenclature of the alleles of mga and speB is suggested.

Alleles↗
PubMed2000

Emm gene polymorphism among temporally clustered group A streptococcal isolates in western Norway.

Nineteen group A streptococcal isolates obtained in western Norway from patients with invasive disease during a period of high morbidity and mortality were examined for clonality and emm gene polymorphism. These isolates belonged to the prevalent serotypes during the outbreak, namely T1, T3 or T6. Restriction fragment length polymorphism and sequencing of the emm genes were used to compare these isolates with 14 isolates of the same serotype but from non-invasive infections. The restriction analysis did not identify specific invasive clones. The emm genes in three of the four T3 isolates from invasive disease had nucleotide substitutions inducing a charge difference in the N-terminal part of the M protein. The 4 T6 isolates had a longer emm amplicon when compared to 15 isolates from superficial infections and also showed nucleotide substitutions that could induce conformational changes in the hypervariable end of the M protein. Restriction analysis of the emm amplicon of the T6 isolates in order to estimate the number of A- and C-repeats is described. The emm gene sequence served as an epidemiological marker within the serotypes T3 and T6, but the significance of the emm polymorphism displayed by the isolates from invasive disease is uncertain at this stage.

Antigens, Bacterial↗
PubMed1999

Pindolol increases extracellular 5-HT while inhibiting serotonergic neuronal activity.

The effects of pindolol, a beta-adrenoceptor blocker/putative 5-hydroxytryptamine (5-HT)1A/1B antagonist, on both the single-unit activity of serotonergic neurons in the dorsal raphe nucleus (DRN) and extracellular 5-HT levels in the caudate nucleus, were examined in freely moving cats. Administration of (+)-pindolol (1 and 10 mg/kg, s.c.) decreased neuronal activity and increased 5-HT levels in a dose- and time-dependent manner. The subsequent administration of WAY-100635 [N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cycloh exanecarboxamide] (0.2 mg/kg, s.c.), a selective 5-HT1A receptor antagonist, blocked pindolol-induced neuronal suppression and potentiated 5-HT output. These results indicate that pindolol may be acting at the level of the nerve terminal to increase 5-HT.

Animals↗