New syndrome: a digito-reno-cerebral syndrome.
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Abnormalities, Multiple↗
Biomedical subjects
B Gustafsson
Publications and source records attributed to B Gustafsson.
Rapid detection of Vibrio cholerae O:1 by motility inhibition and immunofluorescence with monoclonal antibodies.
Monoclonal antibodies against the group and type specific antigens of Vibrio cholerae O:1 lipopolysaccharide were used for the rapid detection of Vibrio cholerae strains by motility inhibition and immunofluorescence. Motility inhibition of live Vibrio cholerae O:1 was obtained with group specific monoclonal antibodies. Monoclonal antibodies against the type specific antigens B (Ogawa) and C (Inaba) inhibited motility of strains of homologous serotypes only. Indirect immunofluorescence of heatfixed bacteria with monoclonal antibodies and fluorescein-isothiocyanate conjugated rabbit anti-mouse immunoglobulin was also shown to be suitable for the rapid detection of Vibrio cholerae O:1. Both tests were highly specific and no cross-reactions were observed with strains of non-O:1 vibrios, Escherichia coli or Salmonella spp. tested. However, a weak fluorescence of some Ogawa strains was observed when high concentrations of Inaba specific monoclonal antibodies were used.
Animals↗
Catabolism of premercapturic acid pathway metabolites of naphthalene to naphthols and methylthio-containing metabolites in rats.
[14C]Naphthalene was given orally to rats with cannulated bile ducts and to germ-free rats. Bile and urine from the cannulated rats and urine from the germ-free rats contained no radioactive 1,2-dihydro-1-hydroxy-2-methylthionaphthalene and only trace amounts of radioactive naphthols or naphthol conjugates. Urine of control rats contained 4.6% of the 14C dose as naphthols and/or naphthol glucuronides. Appreciable quantities of 1- and 2-naphthol (7-20% of dose) and 1,2-dihydro-1-hydroxy-2-methylthionaphthalene (1-35% of dose) were in urine from rats dosed orally or intracecally with 1,2-dihydro-1-hydroxy-2-S-cysteinylnaphthalene and 1,2-dihydro-1-hydroxy-2-S-(N-acetyl)cysteinylnaphthalene. Apparently, in vivo, naphthols and methylthio-containing metabolites of naphthalene are formed during enterohepatic circulation of 1,2-dihydro-1-hydroxy-2-S-cysteinylnaphthalene and 1,2-dihydro-1-hydroxy-2-S-(N-acetyl)cysteinylnaphthalene in a process dependent upon intestinal microflora. A possible pathway for the formation of naphthols is aromatization of the precursor compounds by elimination of the appropriate substituent group from these metabolites. This discovery of the essential role of the intestinal microflora in the formation of naphthols from naphthalene indicates the existence of a novel pathway for hydroxylation of aromatic systems and challenges the current concept of the in vivo relevance of the in vitro production of naphthols from naphthalene 1,2-oxide.
Acetylcysteine↗
The effect of D2343 in transmurally stimulated rabbit isthmus muscle.
In in vitro experiments spirally cut isthmic preparations from oestrogenized rabbits have been contracted by transmural stimulation. The beta 2-agonistic and alpha 1-antagonistic drug D2343 (for chemical structure, see fig. 1 in Olsson et al. 1984) inhibits the evoked contractions in a concentration related fashion with 50% effect at 9.6 X 10(-6) mol/l. The alpha 1-antagonist prazosin has an inhibiting action in the same concentration range (EC50 = 14.0 X 10(-6) mol/l). To inhibit the contractile response to the same degree by the beta 2-agonist terbutaline the concentration has to be greater than 10(-3) mol/l. From received results the beta (beta 2)-adrenoceptor mediated effects seem to be of minor importance compared to the alpha (alpha 1)-receptor dominance in the isthmus muscle during oestrus.
Adrenergic alpha-Antagonists↗
On long-lasting potentiation in the hippocampus: a proposed mechanism for its dependence on coincident pre- and postsynaptic activity.
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Animals↗
A synaptic potential following single volleys in the hippocampal CA1 region possibly involved in the induction of long-lasting potentiation.
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2-Amino-5-phosphonovalerate↗
Facilitation of hippocampal long-lasting potentiation by GABA antagonists.
Long-lasting potentiation (LLP) of synaptic transmission in the CAI region of the hippocampal slice preparation has been examined. The effects of reduced postsynaptic inhibition given by application of gamma-aminobutyric acid (GABA) antagonists (mainly picrotoxin) on the generation of LLP were investigated. It was first demonstrated that picrotoxin had little effect on excitatory synaptic transmission itself as judged by the rising phase of the field EPSP. Moreover, there were largely no actions on short-lasting synaptic effects such as paired pulse facilitation and frequency potentiation. On the other hand, following drug application, much fewer afferent volleys were needed to generate a given amount of LLP. Long-lasting potentiation could be produced by trains containing as few as 2-5 impulses, trains that normally give rise to only short-lasting effects. There was no apparent difference in the maximal amount of LLP that could be produced for a given input, suggesting that the GABA antagonists do not operate by enhancing the capacity for LLP production but by facilitating its induction. As in normal solution, the LLP in the presence of the drugs was confined to the tetanized pathway. Tetanization in the treated slices was associated with enhanced somatic firing as well as an increase of the negative extracellular potential recorded in the dendritic layer. It is proposed that part of this increased negativity represents current through synaptically opened N-methyl-D-aspartate (NMDA) receptor channels. Furthermore, it is suggested that the facilitated induction of LLP in the presence of GABA antagonists is related to a facilitated activation of these NMDA receptor channels which is secondary to the higher levels of dendritic depolarization attained during tetanization under conditions of reduced postsynaptic inhibition.
Afferent Pathways↗
Functional development of the visual system in normal and protein deprived rats. III: Recordings from adult optic nerve in vitro.
A persistent increase in the latencies of the visual evoked response recorded from the cortical surface of protein deprived adult rats was described recently (Sjöström et al. 1984). The morphological correlate to this alteration is unknown. Previous studies on malnourished rats have shown a reduction of axonal diameters and in the number of myelin lamellae in relation to axonal circumference, and hence the possibility of a decrease in fibre conduction velocity must be considered. In parallel study, we have established that changes in diameters and myelination of optic nerve fibres similar to those previously reported in malnourished rats are present in adult protein deprived (PD) rats (Conradi et al. 1985). In the present paper, recordings of optic nerves in vitro from adult normal (C) and protein deprived (PD) rats are described. The compound action potentials were very similar in the two groups. Three positive peaks were easily defined, probably corresponding to three functional groups of optic nerve fibers. No significant differences in amplitudes or conduction velocities for the three peaks were found between the C and PD rats. It is concluded that the increased latencies of the evoked response are not caused by a decrease in conduction velocity.
Animals↗
Immunological characterization of Vibrio cholerae O:1 lipopolysaccharide, O-side chain, and core with monoclonal antibodies.
Lipopolysaccharide (LPS) was extracted from Vibrio cholerae O:1 strains of the serotypes Ogawa, Inaba, and Hikojima and delipidated by mild-acid hydrolysis. Two polysaccharide fragments with the molecular weights of approximately 9,000 and 900, respectively, were isolated by gel permeation chromatography. The LPS preparations and the polysaccharide fragments were studied in enzyme-linked immunosorbent assay inhibition, rocket immunoelectrophoresis, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by electroblotting with monoclonal antibodies directed against the group-specific antigen A, the type-specific antigens B (Ogawa) and C (Inaba), and the core region. Antigen A was demonstrated in all LPS preparations and all 9,000-molecular-weight fragments tested. The type-specific antigens B and C were demonstrated in LPSs and 9,000-molecular-weight fragments from Ogawa and Inaba, respectively. Furthermore, antigens B and C were both demonstrated in LPSs and 9,000-molecular-weight fragments from two of four Hikojima strains tested. Core antigen was demonstrated in the LPS and in the 9,000- and 900-molecular-weight fragments. The results indicate that the 9,000-molecular-weight fragment represents the complete polysaccharide chain, including group- and type-specific antigens as well as core antigens, whereas the 900-molecular-weight fragment constitutes the main part of the core region.
Antibodies, Monoclonal↗
Metabolism of leukotriene C4 in rats and humans.
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Adult↗
Influence of post-synaptic properties on the time course of synaptic potentials in different types of cat lumbar alpha-motoneurons.
Shape indices of excitatory post-synaptic potentials (EPSPs) have been calculated on compartmental models assembled using average properties obtained from two motoneuron groups classified as fast and slow, on the basis of rheobase current and input conductance. The calculated EPSP time courses differed considerably between the two models, the rise-time and half-width being more prolonged in the slow model. With a conductance change distributed uniformly among compartments 3-6 in a 10-compartment model, the resulting shape indices in the slow and fast model, respectively, were quite similar to the apparent average values previously observed experimentally for composite Ia EPSPs in types S (slow) and F (fast) motoneurons. The results of the calculations suggest that differences in EPSP shape indices observed between F and S motoneurons arise from systematic differences in motoneuron postsynaptic properties (specific membrane resistivity and dendritic geometry) rather than differences in dendritic location of synaptic input. The results also suggest that changes in EPSP time course, following section of the motor axon, may similarly be related to changes in motorneuron postsynaptic properties.
Animals↗
A possible correlate of the postsynaptic condition for long-lasting potentiation in the guinea pig hippocampus in vitro.
Picrotoxin and 2-amino-5-phosphonovalerate (APV) have previously been reported to influence the production of long-lasting potentiation in the hippocampus (facilitation and depression, respectively). We have examined how these drugs modify the postsynaptic responses to tetanic afferent activation used to elicit long-lasting potentiation. The experiments were performed in the CA1 area of transverse hippocampal slices maintained in vitro. A slow extracellular dendritic negativity-interpreted as a sign of a dendritic depolarizing process-was enhanced by picrotoxin and depressed by APV. This dendritic potential may represent a postsynaptic event involved in the production of long-lasting potentiation.
2-Amino-5-phosphonovalerate↗
Afterhyperpolarization in neurones of the red nucleus.
Afterhyperpolarization (AHP) following single or short trains of spikes in rubrospinal neurones (RN neurones) of the cat has been studied with intracellular recording techniques. The AHP amplitude was potential dependent; it increased with depolarization and decreased with hyperpolarization and had an extrapolated reversal potential about 20 mV below resting membrane potential. The AHP was associated with an increase in the membrane conductance and it was concluded that the AHP is primarily caused by an increase in membrane conductance to potassium ions. The time course of the conductance change underlying the AHP was measured with short current pulses and calculated from the AHP voltage. The AHP following a single spike was conditioned at different interspike intervals by a preceding spike (or several spikes). In many RN neurones the AHP (conductance) following a spike added approximately linear to that generated by a preceding spike. In most cells, however, the AHP following a spike was instead depressed by a preceding spike. The summation of AHPs increased progressively, while the depression appeared to be already maximal with one preceding spike. The depression was then approximately constant for interspike intervals less than the AHP duration. It will be shown in a following paper that these properties of the AHP are reflected in the behaviour of the repetitive discharge evoked by constant current pulses in the same neurones.
Action Potentials↗
Blood levels of progesterone and 15-Keto-13, 14-dihydro prostaglandin F(2alpha) during the estrous cycle of oxytocin-treated cows.
Six non-lactating Holstein cows were injected with 230 iu oxytocin subcutaneously twice daily from days 2 through 6 of the cycle. Controls (n=6) were given saline injections using the same schedule. Blood samples were collected at frequent intervals before and after each saline or oxytocin injection. Progesterone and 15-Keto-13, 14-dihydro prostaglandin F(2alpha) (PGFM), the major metabolite of prostaglandin F(2alpha), were analysed by radio-immunoassay. Oxytocin injections significantly increased plasma prostaglandin concentrations on days 2 and 3 when compared with the controls. In two oxytocin-treated cows, the cycle was shortened to 10 and 12 days. Estrus was preceded by a PGF(2alpha) release very similar to that preceding spontaneous estrus. Two of the oxytocin-treated cows showed estrus on day 21 and 22 preceded by luteolytic release of PGF(2alpha). Two oxytocin-treated cows developed cystic corpora lutea and had not shown heat when the ovaries were removed four weeks later. All oxytocin-treated cows showed a slower progesterone increase through day 8 than the controls. The study shows that endocrine events preceding cycle alterations in oxytocin-treated cows involve release of PGF(2alpha) and lowered levels of progesterone.
Journal Article↗
The effects in myometrial preparations of D2343, a beta 2-adrenoceptor agonist possessing alpha 1-receptor blocking qualities.
D2343 is a compound with about the same beta 2-adrenoceptor-agonist effect as terbutaline and exhibiting in addition an alpha 1-receptor inhibitory activity. D2343 has been compared to the beta 2-agonist terbutaline on oestrogenized uterine preparations from rat and rabbit (in vitro and in vivo) and in myometrial strips from homo. Generally, D2343 has shown an ability to relax the uterine muscles to the same degree as terbutaline or even more, especially when the two drugs were compared in vitro in preparations from rabbit and rat.
Adrenergic alpha-Antagonists↗
Influence of stretch-evoked synaptic potentials on firing probability of cat spinal motoneurones.
Shapes of post-synaptic potentials (p.s.p.s) in cat motoneurones were compared with the time course of correlated changes in firing probability during repetitive firing. Excitatory and inhibitory post-synaptic potentials (e.p.s.p.s. and i.p.s.p.s) were evoked by brief triangular stretches of the triceps surae-plantaris muscles. Depolarizing current was injected through the recording micro-electrode to evoke repetitive firing and the post-stimulus time histogram of motoneurone spikes was obtained. E.p.s.p.s (n = 80) of different sizes (30-1040 microV) and rise times (1.1-8.2 ms) were investigated in fifty-nine motoneurones. The majority of the e.p.s.p.s were recorded in triceps surae-plantaris motoneurones with high levels of synaptic noise (estimated peak-to-peak fluctuations of 1.5-3.5 mV). This noise was generated by keeping the triceps surae-plantaris muscles stretched to a near maximal degree. The remaining e.p.s.p.s were recorded in motoneurones to other hind-limb muscles with a low level of synaptic noise. The height of the primary peak of the correlogram with respect to base-line firing rate increased in proportion to both amplitude and rising slope of the e.p.s.p.s. Using normalization procedures or using e.p.s.p.s of constant amplitude but different slopes and vice versa, the relative peak height increased with e.p.s.p. peak derivative with a slope of around 6/mV per millisecond and with e.p.s.p peak amplitude with a slope of about 1/mV. The shape of the correlogram (peak and trough) seemed well described by a linear combination of the shape of the e.p.s.p. derivative and that of the e.p.s.p. itself. The relative e.p.s.p. contribution (e.p.s.p.:e.p.s.p. derivative ratio) varied with e.p.s.p. amplitude and noise level, being largest (mostly 0.25-1.0) for small e.p.s.p.s (100-300 microV) in high levels of synaptic noise and smaller (0-0.25) for larger e.p.s.p.s and for e.p.s.p.s in a low noise background. In conformity with the above finding, a leaky integration of the correlograms gave time courses that in most cases closely resembled the shape of the e.p.s.p.s. The time constant of the leaky circuit (= inverse value of e.p.s.p.:e.p.s.p. derivative ratio) varied with e.p.s.p. amplitude and noise level in the same manner as obtained by direct fitting of e.p.s.p. and e.p.s.p. derivative shape to correlogram shape. Stretch-evoked i.p.s.p.s (n = 10) of small amplitude (90-360 microV as measured close to firing level) were investigated in pre-tibial flexor motoneurones with low levels of synaptic noise. These i.p.s.p.s generated correlogram troughs closely resembling, albeit somewhat wider than, the shape of the i.p.s.p. derivatives.(ABSTRACT TRUNCATED AT 400 WORDS)
Action Potentials↗
On re-excitation of feline motoneurones: its mechanism and consequences.
Conditions required for re-excitation of lumbosacral motoneurones, i.e. for double impulses in the motor axons associated with a single soma-dendritic action potential, were examined in cats anaesthetized with pentobarbitone and paralysed with gallamine triethiodide. Simultaneous recording from a motoneurone (intracellular, and in some experiments also extracellular), and from its axon in a ventral root, was used to assess the relations between the soma and the double axonal action potentials. Action potentials (greater than 70 mV) evoked by brief depolarizing current pulses applied intracellularly were never observed to cause re-excitation. Re-excitation could, however, be regularly induced by procedures which increased the delay between the initial segment and soma-dendritic components of these potentials. Re-excitation could be evoked (i) when brief hyperpolarizing pulses were applied before the onset of the soma-dendritic spikes, (ii) when the depolarizing pulses were applied on a background of long hyperpolarizing pulses or (iii) when two action potentials were evoked in a quick succession (by two brief depolarizing pulses). No relationship was found between the presence of re-excitation of motor axons and the presence of the delayed depolarization which follows the soma-dendritic spikes. Neither re-excitation nor delayed depolarization were found to be dependent upon re-excitation of the initial segment. These observations are thus at variance with previous suggestions that the initial segment spikes induce the re-excitation of motor axons and that the initial segment spikes cause the delayed depolarization following soma-dendritic spikes. Since re-excitation of a motor axon occurred without any signs of a second initial segment spike, it is concluded that it is initiated at the level of the axon, most likely at the first node of Ranvier. Re-excitation of motor axons was also observed during repetitive firing induced by intracellular current injection. However, it occurred then only occasionally, and only under strong depolarizing drive. It is thus not expected to be a common phenomenon under natural conditions of repetitive firing.
Action Potentials↗
Relations among passive electrical properties of lumbar alpha-motoneurones of the cat.
The relations among passive membrane properties have been examined in cat motoneurones utilizing exclusively electrophysiological techniques. A significant relation was found to exist between the input resistance and the membrane time constant. The estimated electrotonic length showed no evident tendency to vary with input resistance but did show a tendency to decrease with increasing time constant. Detailed analysis of this trend suggests, however, that a variation in dendritic geometry is likely to exist among cat motoneurones, such that the dendritic trees of motoneurones projecting to fast-twitch muscle units are relatively more expansive than those of motoneurones projecting to slow-twitch units. Utilizing an expression derived from the Rall neurone model, the total capacitance of the equivalent cylinder corresponding to a motoneurone has been estimated. With the assumption of a constant and uniform specific capacitance of 1 mu F/cm2, the resulting values have been used as estimates of cell surface area. These estimates agree well with morphologically obtained measurements from cat motoneurones reported by others. Both membrane time constant (and thus likely specific membrane resistivity) and electrotonic length showed little tendency to vary with surface area. However, after-hyperpolarization (a.h.p.) duration showed some tendency to vary such that cells with brief a.h.p. duration were, on average, larger than those with longer a.h.p. durations. Apart from motoneurones with the lowest values, axonal conduction velocity was only weakly related to variations in estimated surface area. Input resistance and membrane time constant were found to vary systematically with the a.h.p. duration. Analysis suggested that the major part of the increase in input resistance with a.h.p. duration was related to an increase in membrane resistivity and a variation in dendritic geometry rather than to differences in surface area among the motoneurones. The possible effects of imperfect electrode seals have been considered. According to an analysis of a passive membrane model, soma leaks caused by impalement injury will result in underestimates of input resistance and time constant and over-estimates of electrotonic length and total capacitance. Assuming a non-injured resting potential of -80 mV, a comparison of membrane potentials predicted by various relative leaks (leak conductance/input conductance) with those actually observed suggests that the magnitude of these errors in the present material will not unduly affect the presented results.+4
Animals↗