Bicuculline-sensitive potassium currents in rat medial preoptic neurons.
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Journal Article↗
Biomedical subjects
S Johansson
Publications and source records attributed to S Johansson.
One-year follow-up of newly diagnosed irritable bowel syndrome patients.
BACKGROUND: Irritable bowel syndrome is the most common functional gastrointestinal disorder seen by general physicians. METHODS: We followed up a population-based cohort of newly diagnosed irritable bowel syndrome patients aged 20-79 years, to examine patterns of treatment, comorbidity and healthcare utilization. We used the UK General Practice Research Database as the source population. Individuals with other gastrointestinal diseases, cancer and pregnant women were not included. There were 2956 patients in our final cohort. RESULTS: Irritable bowel syndrome patients were mainly young and middle-aged; only 12% were 60 years or older. The majority of patients were women (74%). There were no marked differences in terms of use of healthcare services or comorbidity status in the year before irritable bowel syndrome diagnosis as compared to the year after. Fourteen per cent of irritable bowel syndrome patients received no drug treatment at all. Among those treated, the first choice was an antispasmodic. Elderly patients (>60 years old) were more likely to receive drug treatment. Females had a slightly higher probability of being treated than men, except for the category of anti-diarrhoeal drugs. CONCLUSION: This study has shown that irritable bowel syndrome patients are mainly young and female. We also found that treatment pattern varied according to age and gender. Elderly patients and females were at a higher risk of receiving drug treatment.
Adult↗
Changes in airway dead space in response to methacholine provocation in normal subjects.
Measurements of bronchial hyper-responsiveness rely on sensitive techniques for measurement of bronchoconstriction, ideally based on tidal breathing. A potentially useful technique is measurement of airway dead space (VDaw), which reflects the volume of the conducting airways. The aim of this study was to evaluate measurements of VDaw with the single breath test for CO2 (SBT-CO2), compared to spirometric measurements, as a method of measuring bronchial response to methacholine challenge. Nineteen healthy adults were studied. Dosimetric methacholine challenge tests were performed on two study days. Forced expirations or the SBT-CO2 were used to assess the response. There were dose-dependent reductions in the spirometric measurements, with a 10 +/- 10% reduction from the baseline value of forced expiratory volume at the highest dose of methacholine. There was a dose-dependent reduction from the baseline value of VDaw by 19 +/- 9% at the highest dose. There was also a dose-dependent increase in the slope of the alveolar plateau of the SBT-CO2. This study provides support for measurement of VDaw as a means of evaluating bronchial responsiveness after methacholine challenge. In a group of healthy adults, this method shows a greater response but with similar dispersion as measurement of forced expiratory volume after methacholine challenge.
Adolescent↗
Neurosteroid modulation of synaptic and GABA-evoked currents in neurons from the rat medial preoptic nucleus.
The effects of the neurosteroid 3alpha-hydroxy-5alpha-pregnane-20-one (allopregnanolone) on synaptic and GABA-evoked currents in acutely dissociated neurons from the medial preoptic nucleus of rat were investigated by perforated-patch recordings under voltage-clamp conditions. The effect of 2.0 microM allopregnanolone on GABA-evoked currents depended strongly on the GABA concentration: the currents evoked by 100 microM GABA were markedly depressed and the desensitization was faster, but the decay after GABA application was prolonged. In contrast, the currents evoked by 1.0 microM GABA were markedly potentiated, the activation was faster, a prominent desensitization was induced, and the decay after GABA application was prolonged. In the absence of externally applied GABA, 2.0 microM allopregnanolone induced a slow current that could be attributed to Cl-. Allopregnanolone did not significantly affect the amplitude of spontaneous tetrodotoxin-insensitive (miniature) synaptic currents (mIPSCs) originating from synaptic terminals releasing GABA onto the dissociated neurons. However, the mIPSC decay phase was dramatically prolonged, with half-maximal effect at approximately 50 nM allopregnanolone. A qualitatively similar effect of allopregnanolone was seen when KCl was used to evoke synchronous GABA release. The frequency of mIPSCs was also affected, on average increased 3.5-fold, by 2.0 microM allopregnanolone, suggesting a presynaptic steroid action.
Animals↗
Integrin subunits (beta)1C-1 and (beta)1C-2 expressed in GD25T cells are retained and degraded intracellularly rather than localised to the cell surface.
We have previously identified the integrin (beta)1C-2 and characterised the distribution of (beta)1C-1 and (beta)1C-2 transcripts in various cell lines and normal cells. In this study we have investigated the expression of the two (beta)1C-variants in integrin (beta)1 deficient mouse GD25T cells. After stable transfection of the GD25T cells with cDNAs coding for (beta)1A, (beta)1C-1 and (beta)1C-2, the cell surface expression of the (beta)1C-1 and (beta)1C-2 variants was found to be very low while the (beta)1A variant was expressed at high levels. Northern blot analysis showed that the level of (beta)1-transcript in the (beta)1C-1 and (beta)1C-2 clones was equal or higher than in the (beta)1A clones. Metabolic labelling and deglycosylation by endoglycosidase H treatment clearly demonstrated that the majority of the (beta)1C-1 and (beta)1C-2 chains did not become maturely glycosylated, nor did they dimerize with (alpha) subunits. After 20 hours of chase, the labelled (beta)1C-1 and (beta)1C-2 chains had been gradually degraded, whereas immature (beta)1A was converted into the maturely glycosylated form during the same period of time. Immunostaining showed intracellular (beta)1 localisation in the (beta)1C-1 and (beta)1C-2 expressing clones, while in the (beta)1A expressing clones the (beta)1 chains were mainly localised to focal adhesion sites and along fibronectin fibres. Taken together, we have shown that expression of both integrin (beta)1C-1 and (beta)1C-2 in GD25T cells result in very low cell surface expression compared with the normal (beta)1A isoform. Instead, both (beta)1C-1 and (beta)1C-2 chains remain in the endoplasmic reticulum until they are intracellularly degraded.
Animals↗
Relaxed versus activated stump muscles during casting for trans-tibial prostheses.
In prosthetic practice, the question often arises as to whether the hand cast should be made from a contracted or from a non-contracted amputation stump. To elucidate this question, the authors have performed a study to quantify the volume difference between these 2 conditions, and to relate the differences to prosthetic fitting. Sixteen (16) trans-tibial amputees participated in the study. All of them were fitted with an ICEROSS silicone socket. Electromyographic studies, with electrodes attached to the anterior tibial and medial gastrocnemius muscles, were carried out to determine muscle contraction levels. Volume determinations were made with the CAPOD laser scanning system. Measurements were performed with and without the silicone liner on the stump. Without a silicone liner, the volume of the stump increased by 5.8% (SD=5.3) as the muscles contracted. This increase was statistically significant. With the liner donned the volume increased 3.5% (SD=3.3). This increase was also statistically significant. The volume of the prosthetic socket was also compared with the stump volume with a silicone liner on. For the relaxed stump, the difference was 1.8% (SD=10.1), and for the contracted stump -1.7% (SD=11.3). Neither difference was statistically significant. The importance of these volume changes and how they influence stiffness of the coupling between the stump and the socket are discussed. It is concluded, that the observed difference in volume between a contracted and a non-contracted stump are large enough to be considered by the prosthetist in his decision on how to make a hand cast.
Aged↗
[A new risk pattern of coronary disease is alarming. Increased body weight threatens the positive trend].
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Adult↗
Identification of beta1C-2, a novel variant of the integrin beta1 subunit generated by utilization of an alternative splice acceptor site in exon C.
A new splice variant of the human integrin subunit beta1 has been identified and designated beta1C-2. It differs from the previously reported beta1C (in this report designated beta1C-1) by 18 nucleotides, and is generated by splicing from exon 6 to an alternative splice acceptor site within exon C, causing an in-frame deletion of six amino acids of the cytoplasmic region of beta1C-1. The beta1C-2 mRNA is present in several human cell lines and tissues at low levels, similarly to beta1C-1. In peripheral T-lymphocytes, beta1C-2 is the selectively expressed isoform. Neither beta1C-1 nor beta1C-2 mRNA could be detected in mouse tissues, and Southern hybridization of a mouse genomic beta1 clone with a human exon-C-specific probe failed to identify a corresponding mouse exon. The antisense orientation of exon C is highly homologous to an Alu element. Since Alu elements are restricted to primates, the beta1C-1 and beta1C-2 variants of the integrin subunit beta1 are specific for these species. The protein coded for by the beta1C-2 cDNA can be expressed and localized to the surface of beta1 deficient mouse cells. However, while stable transformed clones expressing high levels of the beta1A were commonly found, the beta1C-1 and beta1C-2 expressing clones expressed barely detectable amounts of the beta1 protein. Hence, high levels of beta1C-2 may be incompatible with cell proliferation, as previously suggested for beta1C-1.
Alternative Splicing↗
Heterogeneous presynaptic Ca2+ channel types triggering GABA release onto medial preoptic neurons from rat.
1. Voltage-dependent Ca2+ channels triggering GABA release onto neurons from the medial preoptic nucleus of rat were investigated. Acutely dissociated neurons with adherent functional synaptic terminals were investigated by tight-seal whole-cell recordings from the postsynaptic cells. 2. Spontaneous current events similar to miniature postsynaptic currents were recorded. They were blocked by bicuculline (100 microM), showed a roughly unimodal amplitude distribution and a reversal potential consistent with a Cl- current, and were therefore attributed to GABAA receptors activated by synaptically released GABA. 3. Application of 140 mM KCl, expected to depolarize presynaptic terminals, evoked currents that were ascribed to a more massive release of GABA. The KCl-induced synaptic currents were abolished in Ca2+-free solutions and showed a roughly hyperbolic relation to external Ca2+ concentration with half-saturation at 0.15 mM. They further depended on the concentration of applied KCl in a way expected for high-threshold Ca2+ channels. 4. The KCl-evoked synaptic currents were completely blocked by 200 microM Cd2+, but only partially blocked by 200 microM Ni2+. The KCl-evoked synaptic currents were insensitive to the L-type Ca2+ channel blocker nifedipine (10 microM). However, the synaptic currents were sensitive to either 1 microM omega-conotoxin GVIA, 25 nM omega-agatoxin IVA or 1 microM omega-conotoxin MVIIC. 6. It was concluded that, in many presynaptic terminals, the Ca2+ influx triggering GABA release onto medial preoptic neurons is mainly mediated by one predominant type of high- threshold Ca2+ channel that may be either of N-, P- or Q-type. 7. It was further concluded that terminals with similar predominant channel types often were clustered on the same postsynaptic cell.
Animals↗
Calcium spikes and calcium currents in neurons from the medial preoptic nucleus of rat.
Ca2+ spikes, their contribution to firing patterns, and the underlying Ca2+ currents in neurons of the medial preoptic nucleus of rat were investigated by tight-seal whole-cell recordings in a slice preparation. Two different types of spikes were recorded: Low-threshold spikes were generated from membrane potentials <-75 mV. High-threshold spikes were recorded when K+ currents were reduced, and were readily evoked from membrane potentials near -40 mV. Both types of spikes were blocked by substitution of Co2+ for Ca2+ in the external medium, but were insensitive to 2.0 microM TTX. Under voltage-clamp conditions, two main types of Ca2+ currents were characterized: low-threshold currents that activated at membrane potentials >-60 mV, and high-threshold currents that activated at potentials >-30 mV. The low-threshold current and the low-threshold spike were more sensitive to block by external Ni2+ than to block by Cd2+, whereas the high-threshold current and the high-threshold spike were more sensitive to block by external Cd2+ than to block by Ni2+. Significant fractions of the high-threshold currents were blocked by 10 microM nifedipine, 1.0 microM omega-conotoxin GVIA, 50 nM omega-agatoxin IVA and 1.0 microM omega-conotoxin MVIIC, suggesting the presence of L-, N-, P- and Q-type Ca2+ channels. There were also a high-threshold current component insensitive to the above mentioned toxins. It is proposed that the low-threshold current serves as a trigger for short bursts of fast spikes from hyperpolarized levels, whereas the high-threshold current is involved in the Cd2+-sensitive burst firing seen in relatively depolarized neurons.
Action Potentials↗
Fractionation Protocol for the Isolation of Polypeptides from Plant Biomass
A fractionation protocol for the isolation of a highly purified polypeptide fraction from plant biomass is described. The procedure dereplicates ubiquitous substance classes known to interfere with bioassays often used in natural product-based drug discovery programs. The protocol involves pre-extraction with dichloromethane, extraction with ethanol (50%), removal of tannins with polyamide, removal of low-molecular-weight components with size-exclusion chromatography over Sephadex G-10, and final removal of salts and polysaccharides with solid-phase extraction using reversed-phase cartridges. The method has been applied to the aerial parts of Viola arvensis, resulting in the isolation of a peptide fraction that on further separation yielded a novel 29-residue macrocyclic polypeptide named varv peptide A, cyclo(-TCVGGTCNTPGCSCSWPVCTRNGLPVCGE-).
Journal Article↗
Effects of ongoing smoking on the development of radiation-induced pneumonitis in breast cancer and oesophagus cancer patients.
PURPOSE: To investigate the influence of smoking on the development of radiation-induced pneumonitis in patients treated for breast and oesophagus cancer. MATERIALS AND METHODS: This is a retrospective study on 405 females diagnosed with primary unilateral breast cancer stages 1 and 2 and 201 oesophagus carcinoma patients. The possibilities in Sweden to obtain detailed information from different medical records were used to collect data on smoking habits, radiation treatment and spontaneously reported pneumonitis. Radiation-induced pneumonitis was defined as a combination of roentgenographic infiltrate in the lung field involving an irradiated area on the chest X-ray and clinical symptoms such as non-productive cough and dyspnoea. RESULTS: Six breast cancer patients had spontaneously reported pneumonitis. Five of them were non-smokers (P = 0.182) and the other was a former smoker. Eight of the oesophagus cancer patients had spontaneously reported radiation-induced clinical pneumonitis and they were all non-smokers (P = 0.022), except one, who was a pipe smoker. None of the patients who were cigarette smokers were recorded as developing clinical pneumonitis after irradiation. CONCLUSION: These data could support the previous clinical observations and experimental studies that smoking depresses the frequency of radiation-induced pneumonitis. The present study as well as earlier observations could justify further studies concerning the possibility of an interaction of smoking with cancer treatment, both from the view of therapeutic failures and reduced adverse effects.
Aged↗
The response of Dunning R3327 prostatic adenocarcinoma to IL-2, histamine and radiation.
A syngeneic, androgen-sensitive Dunning R3327 rat prostatic adenocarcinoma was transplanted bilaterally in the flanks of male Copenhagen Fisher rats. Approximately 3 months after implantation, when the tumours had a median volume of 150 mm3, one group of rats was treated with histamine alone (4 mg kg(-1) subcutaneously on week days), another group with human recombinant interleukin 2 (IL-2) alone (425 IU kg(-1) continuous infusion) and a third group with both histamine and IL-2 during 6 weeks. Tumours on one flank were irradiated (6 Gy once daily for 3 days to a total dose of 18 Gy) beginning 1 week after the onset of treatment with histamine and/or IL-2. The contralateral tumour served as the intra-animal control. The tumour volumes were determined weekly. The growth curves showed that all three drug treatments were effective in delaying growth, but when used individually did not cause tumour shrinkage. Radiation was the most effective single agent, but when used alone the shrinkage did not occur until 2 weeks after irradiation. When combined with the drugs, more rapid and extensive growth delay and/or shrinkage was seen. The growth curves showed clear differences between the different treatments. The combination of the three agents was the most effective of all. The most striking difference between radiation alone and radiation plus biotherapy was the time at which a tumour response was detectable. Thus, active biotherapy alone and especially in a combination with histamine and radiotherapy warrants further investigation as a potential therapeutic approach to prostate cancer.
Adenocarcinoma↗
Interaction between 3 alpha-hydroxy-5 alpha-pregnan-20-one and carbachol in the control of neuronal excitability in hippocampal slices of female rats in defined phases of the oestrus.
The effects of 3 alpha-hydroxy-5 alpha-pregnan-20-one (allopregnanolone) and carbachol on CA1 and dentate gyrus action potentials were studied in hippocampus slices in premature, follicular and luteal phase rats. A 0.5 nL droplet of allopregnanolone (12.5 mumol L-1), carbachol (5 mumol L-1) or a mixed solution of 12.5 mumol L-1 allopregnanolone and 5 mumol L-1 carbachol was applied locally onto the stratum oriens-pyramidale or granular layer. The amplitude of CA1 population spike (POPSP) was reduced by allopregnanolone (-38 +/- 3%) and carbachol (-21 +/- 4%) in the luteal phase slices. The mixture of allopregnanolone and carbachol doubled this inhibition (-77 +/- 6%). The inhibition caused by allopregnanolone and the mixture of allopregnanolone and carbachol in CA1 was significantly larger in the luteal phase than in the follicular phase (P = 0.02 and 0.0002). In the granular layer of the dentate gyrus, these inhibitions showed no significant difference between the phases. Neither in CA1 nor in the dentate gyrus did the carbachol inhibition differ between the phases. Perfusion with 5-10 mumol L-1 carbachol caused an increasing inhibition of the POPSP during the first few minutes. Thereafter the inhibition gradually diminished and was replaced by a facilitation. The local allopregnanolone inhibition was enhanced by simultaneous carbachol perfusion. Picrotoxin (100 mumol L-1) substantially reduced the allopregnanolone but not the carbachol inhibition. Atropine (10 mumol L-1) blocked the carbachol response, but not the allopregnanolone inhibition. Perfusion with a mixed solution of picrotoxin and atropine reduced, but did not block, the inhibition caused by local application of allopregnanolone or by the mixture of allopregnanolone and carbachol. Our data suggest that neuroprogestine modulators of the GABAA-receptor-mediated inhibition may play a significant role in the control of the cholinergic excitation in the hippocampus.
Action Potentials↗
Comparison of mortality from peptic ulcer bleed between patients with or without peptic ulcer antecedents.
We studied mortality related to peptic ulcer bleed in a well defined cohort of patients in the month after the episode of peptic ulcer bleed. Our objective was to assess the contribution of peptic ulcer antecedents and other predictive factors on the risk of dying. The study cohort comprised 1,020 patients hospitalized for an episode of peptic ulcer bleed between January 1991 and March 1994 and identified in the General Practice Research Database in the United Kingdom. Six hundred twenty-three patients had no prior episode of peptic ulcer disease, and 384 had peptic ulcer antecedents; for 13 patients, information was not available. Forty-five patients died (mortality rate = 4.4 per 100 person-months; 95% confidence interval = 3.3-5.9) within 1 month of the peptic ulcer bleed. Patients with no peptic ulcer antecedent faced a greater risk of dying than patients with antecedents (relative risk = 3.0; 95% confidence interval = 1.2-7.1). Elderly patients, those undergoing surgery, and current users of acid-suppressing drugs or nonsteroidal antiinflammatory drugs all had an increased mortality risk. Patients presenting with their first-ever episode of peptic ulcer bleed have a higher case fatality rate than those with previous episodes of peptic ulcer.
Adult↗
Mouse myoblasts can fuse and form a normal sarcomere in the absence of beta1 integrin expression.
Antibody perturbation experiments suggested that migration, terminal differentiation and fusion of myoblasts are dependent on beta1 integrin expression. In addition, several studies have postulated that beta1 integrins have a role in the formation of sarcomeres. In the present report we have analysed skeletal myogenesis in wild-type/beta1-null chimeric mice and beta1-null embryoid bodies. Trunk and limbs of beta1-null chimeric mice contained muscle tissue composed of normal and beta1-null myoblasts indicating that all myotomic sublineages can form, migrate to their peripheral targets and fuse in the absence of beta1 integrin expression. Pure populations of beta1-null myoblasts and satellite cells isolated from beta1-null chimeric embryos and chimeric newborn mice, respectively, were able to differentiate in vitro and to fuse into multinucleated myotubes. Quantitative and qualitative comparisons between normal and beta1-null myoblasts revealed no apparent difference in their capacity to terminally differentiate and fuse. Furthermore, beta1-null myotubes developed sarcomeres which were indistinguishable from wild-type controls. When normal and beta1-null ES cells were differentiated into embryoid bodies, they contained fully differentiated myotubes with normal sarcomeres and normal deposition of costameric components. However, formation of beta1-null myotubes was delayed and was less efficient in beta1-null embryoid bodies than in wild-type controls. High expression of alphav integrin subunit at the tips of normal as well as beta1-null myotubes indicated that the lack of beta1 integrins did not result in a significant redistribution of alphav-containing receptors.
Animals↗
Mutational analysis of the potential phosphorylation sites in the cytoplasmic domain of integrin beta1A. Requirement for threonines 788-789 in receptor activation.
To investigate the role of the potential phosphorylation sites in the cytoplasmic domain of integrin beta1A, point mutated variants of the protein were stably expressed in the beta1-deficient cell line GD25. Mutants T777A, Y783F, S785A, and Y795F were fully active in promoting cell adhesion, de novo formation of focal contacts, formation of fibronectin fibrils, and activation of focal adhesion kinase. Thus, phosphorylation of these residues is not required for several basic functions of integrin beta1A. On the other hand, the TT788-9AA mutant, was defective in mediating cell attachment and did not contribute to fibronectin fibril formation. The conformation of the extracellular domain was shifted towards an inactive state as measured by binding of the monoclonal antibody 9EG7. Antibody induced clustering of beta1ATT788-9AA demonstrated that the mutant cytoplasmic part was functional in mediating activation of focal adhesion kinase. Therefore, we conclude that threonines 788-789, which are conserved among most integrin beta subunits, are of critical importance for integrin function due to effects on the extracellular conformation of the receptor.
Amino Acid Sequence↗
Accuracy and precision of volumetric determinations using two commercial CAD systems for prosthetics: a technical note.
The aim of this study was to evaluate the validity and reliability of volume determinations using the commercially available Seattle ShapeMaker CAD/CAM system for production of prosthetic sockets and to compare it with the commercially available CAPOD system. We used three types of reference objects for volumetric determinations: steel tubes, plaster of Paris casts, and residual limb models. Three different sizes were examined for each type of object. Volume measurements with the two CAD/CAM systems were compared with measurements obtained by water filling, water immersion, or mathematical calculation (tubes only). We found an inconsistent systematic error of less than 3.1% for ShapeMaker and no systematic error for CAPOD. Random errors, represented by the coefficient of variation, were below 1.3% for the ShapeMaker and, in most cases, below 0.4% for the CAPOD. Theoretical changes in volume of 2.6% and 0.8% are possible to detect with these CAD/CAM systems. In our opinion, both systems have sufficient precision for routine clinical use in prosthetics and orthotics. However, in our study, the ShapeMaker committed larger random and systematic errors than CAPOD. This means that, according to our study, CAPOD offers the best possibility to determine and detect small changes in residual limb volume as a function of time.
Artificial Limbs↗