Showing papers by "Karolinska Institutet published in 1982"

Neuropeptide Y-a novel brain peptide with structural similarities to peptide YY and pancreatic polypeptide

Abstract: The C-terminal α-amide structure is a characteristic feature of many biologically active peptides1,2 Using a novel chemical method for the detection of peptide amides3, we have isolated two naturally occurring peptides, peptide HI (PHI) and peptide YY (PYY), from extracts of porcine intestine and have shown that these peptide amides represent previously unknown biologically active peptides4 PHI is structurally and biologically similar to vasoactive intestinal peptide (VIP)5 while PYY shows similarities to pancreatic polypeptide (PP)6 Preliminary studies indicated that PHI and PYY may both be present in brain as well as in intestine4 We report here the isolation from brain extracts of a peptide amide that was thought to be PYY However, we found that the peptide, while having distinct structural and biological similarities to both PYY and PP, is a previously uncharacterized peptide, which we designate neuropeptide Y (NPY)

Bleb formation in hepatocytes during drug metabolism is caused by disturbances in thiol and calcium ion homeostasis.

Abstract: A wide variety of toxic chemicals cause blebbing of the plasma membrane in isolated hepatocytes. These alterations in surface structure occur well before cell death. The formation of blebs appears to be directly related to changes in the concentration of extramitochondrial calcium ions. These changes probably reduce the ability of the hepatocyte cytoskeleton to maintain normal surface morphology. The concentration of soluble thiols, notably glutathione, appears to regulate the size of the extramitochondrial calcium ion pool. Disturbances in intracellular thiol and calcium ion homeostasis therefore seem to be responsible for the surface blebbing observed during toxic injury to isolated hepatocytes.

Pancreatic polypeptide family (APP, BPP, NPY and PYY) in relation to sympathetic vasoconstriction resistant to α-adrenoceptor blockade

Abstract: Electrical stimulation of the cat cervical sympathetic trunk caused submandibular salivary secretion and vasoconstriction simultaneously with a contraction of the nictitating membrane. Following α- and β-adrenoceptor blockade by phentolamine or phenoxybenzamine combined with propranolol, the salivary response and the nictitating membrane contraction upon sympathetic stimulation were almost abolished. A considerable vasoconstrictor response (up to 40% of control) however still remained in the submandibular gland. This yasoconstriction, which persisted after α-adrenoceptor blockade, was rather slow in onset and had a long duration without any poststimulatory hyperemia. Local intra-arterial infusions of noradrenaline caused submandibular vasoconstriction, salivary secretion and nictitating membrane contraction. The blood flow response to exogenous noradrenaline did, however, not mimic the effects of sympathetic nerve stimulation with regard to vascular escape. Whereas the vascular escape after nerve stimulation was followed by a prolonged vasoconstriction with a gradual decline, the escape after noradrenaline infusions was accompanied by a normalization of blood flow. Local intra-arterial infusions of pancreatic polypeptide (PP)-related peptides caused a slowly developing vasoconstriction with a long duration in the submandibular gland, but no salivary secretion or contraction of the nictitating membrane. The relative molar potencies as vasoconstrictory agents were about PYY: 1, neuropeptide Y (NPY): 5, avian and bovine pancreatic polypeptid 100. The vasoconstrictor effects of PP-related peptides were resistant to α-adrenoceptor blockade and present also in sympathectomized animals, suggesting a direct action on vascular smooth muscle. Combined local infusions of noradrenaline and NPY caused a vascular response in the submandibular salivary gland which was similar to that seen upon sympathetic nerve stimulation. PYY and NPY caused increase in systemic arterial blood pressure upon systemic administration which indicates general vasoconstrictor actions. This effect was accompanied by a transient bradycardia which was due to inhibition of sympathetic tone, since it was absent in animals treated with propranolol. In conclusion, the present findings illustrate the differential sensitivity to α-adrenoceptor antagonists of the submandibular vasoconstriction and salivation as well as smooth muscle contraction of the nictitating membrane induced by sympathetic nerve stimulation. This remaining vasoconstriction may be explained by release of a nonadrenergic, PP-related transmitter such as NPY which may be present together with noradrenaline in the vascular nerves. Release of an additional vasoconstrictory factor may also account for the finding that infusions of noradrenaline do not mimic the vascular effects of sympathetic nerve stimulation in vivo.

Origin of lignans in mammals and identification of a precursor from plants

Abstract: Lignans are a class of compounds with a dibenzylbutane skeleton1 which until recently had only been found in higher plants2,3. The first lignans to be identified in humans and animals were trans-2,3-bis(3-hydroxybenzyl)-γ-butyrolactone (enterolactone)4–6 and 2,3-bis(3-hydroxybenzyl)butane-1,4-diol (enterodiol)4,5. These structures differ from those of plant lignans by having aromatic rings substituted only in the meta position. Enterolactone and enterodiol are excreted in the urine and bile, predominantly as glucuronide conjugates7,8, and intestinal microflora is required for their formation8,9. It is not known, however, whether they are synthesized de novo by microorganisms or are formed from dietary precursors. We report here evidence that these mammalian lignans are formed by microbial action on precursor lignans which are present as dietary constituents of plant origin. Precursors are found in seeds of different species, being particularly abundant in linseed. From this source, 2,3-bis(3-methoxy-4-hydroxybenzyl)butane-1,4-diol (secoisolariciresinol) has been identified as a glycoside.

Adverse effects of extradural and intrathecal opiates: report of a nationwide survey in sweden

Abstract: The Swedish Society of Anaesthetists conducted a nationwide retrospective survey of clinical experience with extradural and intrathecal opiates. Special interest was focused on the frequency and type of ventilatory depression. The questionnaire was answered by 84 of 93 departments (90%). Up to May 1981 extradural morphine had been given to approximately 6000-9150 patients, extradural pethidine to 220-450 and intrathecal morphine to 90-150 patients. Ventilatory depression requiring treatment with naloxone was reported in 23 patients treated with extradural morphine (0.25-0.40%) and in six given intrathecal morphine (4-7%). In 22 patients the administration of extradural morphine was considered as a major contributory factor for the occurrence of ventilatory depression. Only two of these 22 patients experienced ventilatory depression later than 6 h after the last dose of opiates (S.C., i.m., i.v. or extradural). Patients aged 70 yr or more, those receiving thoracic extradural puncture and those with reduced ventilatory capacity seemed to be overrepresented.

The identification of the weak oestrogen equol [7-hydroxy-3-(4′-hydroxyphenyl)chroman] in human urine

Abstract: The identification (by gas chromatography–mass spectrometry and n.m.r.) for the first time of the weak oestrogen equol [7-hydroxy-3-(4′-hydroxyphenyl)chroman] in human urine is described. Preliminary results of its quantitative excretion in urine are reported and the potential significance of the occurrence of this compound is discussed.

Intracellular recordings from cochlear outer hair cells

Abstract: Intracellular recordings were made from outer hair cells in the third turn of the guinea pig cochlea, and the electrical characteristics of the cells were compared to those of inner hair cells, supporting cells, and extracellular spaces from the same recording region. Outer hair cells have higher membrane potentials than do inner hair cells, but they produce smaller a-c receptor potentials. The frequency response characteristics of both types of hair cells are probably not significantly different. In the frequency region where tuning is optimal, both cell types produce depolarizing d-c receptor potentials, but outer hair cells also generate hyperpolarizing responses at low frequencies.

Changes in onset of blood lactate accumulation (OBLA) and muscle enzymes after training at OBLA

Abstract: Eight well-trained middle and long distance male runners added to their regular training program a weekly 20-min treadmill run at a velocity calculated to elicit a blood lactate concentration of 4 mmol X 1-1. VO2 max, the running velocity eliciting 4 mmol X 1-1 blood lactate (VOBLA), and the activities of citrate synthase (CS), phosphofructokinase (PFK), lactate dehydrogenase (LDH) and LDH isozymes in the M. vastus lateralis were determined before and after 14 weeks of this training. Significant increases were observed in VOBLA and the relative fraction of heart-specific LDH, while the activity of PFK and the ratio of PFK/CS decreased after training. The change in VOBLA was negatively correlated to the mean rate of blood lactate accumulation during the last 15 min of the treadmill training runs, and positively correlated to the percentage of slow twitch fibers in the M. vastus lateralis. The data support the hypothesis that a steady state training intensity which approximates VOBLA will increase VOBLA, and will result in measureable local metabolic adaptations in the active skeletal muscles of well-trained runners without a significant change in maximal aerobic power. Muscle fiber type composition may be an indicator of the "trainability" of the musculature.

Increase in vascular permeability induced by leukotriene B4 and the role of polymorphonuclear leukocytes.

Abstract: Leukotriene B4 (LTB4), a metabolite of arachidonic acid, is known to be a potent chemotactic and chemokinetic substance. We have used the hamster cheek pouch microcirculation model to study the effect of LTB4 on vascular permeability and the involvement of neutrophil granulocytes in this response. Intravascular fluorescein-labeled dextran (mol wt 150,000) was used as a tracer of macromolecular permeability. Topical application of LTB4 (150 nM-5 microM) to the hamster cheek pouch resulted in an immediate increase in adhering leukocytes in postcapillary venules and later venules. Leukocyte accumulation was reversible, but continued longer the higher the dose of LTB4 used. Subsequently, a dose-dependent increase in vascular permeability was seen at post-capillary and larger venules, with a maximum 10-20 min after application; the maximum occurred later the higher the dose of LTB4. Depletion of neutrophil granulocytes by pretreatment of the animals with antineutrophil serum obtained from immunized rabbits significantly decreased the permeability response to LTB4, whereas the response to histamine was unaffected. These results suggest that neutrophil granulocytes play a role in LTB4-mediated permeability increase. LTB4 may be of importance both for the leukocyte accumulation and for the edema formation seen in inflammatory reactions.

Mechanism of T cell activation: role and functional relationship of HLA-DR antigens and interleukins.

Abstract: The recognition that supernatants of mitogen activated (Morgan et al. 1976, Gillis & Smith 1977) or mixed leukocyte cultures (Ryser et al. 1978) contain a T .• cell growth factor (TCGF, now termed InterIeukin-2, Aarden et al. 1979) that i supports the continuous growth and proliferation of human and murine T cells has allowed both the expansion of T lymphocyte populations and the cloning of cells belonging to functionally disparate subpopuiations. Numerous studies have shown that antigen-specific or non-specific murine fl|: and human cytotoxic, suppressor as well as helper T lymphocytes can be maintained in a state of continuous proliferation in vitro when cultured in medium containing Interleukin-2 (11-2) (Gillis & Smith 1977, Alvarez et al. 1978, Kurn i cke t a l . 1979, von Boehmer et al. 1981, Bach et al. 1981, Glasebrook e ta l . 1981, Schreier et al. 1980, Watson 1979, Apte et al. 1981, Kurnick e t a l . 1981, Fathman & Kimoto 1981, Sarmiento et al. 1980, Sredni & Schwartz 1981). Several research groups have shown that 11-2 does not support growth of nonJj\" ^ activated T lymphocytes. Thus, it has been postulated that a T cell population must be \"activated\" both to become sensitive to 11-2 and to produce this growth factor in order to proliferate (for review see Moller 1980). Due to the welldocumented macrophage requirement for mitogen induced II-2 production (Smith et al. 1980) and the observation that Interleukin-1 (Il-l , previously ,, I • referred to as lymphocyte activating factor or L A F (Aarden 1979)) is a . j' macrophage product (Gery et al. 1972, Mizel et al. 1978), it has been hypothesized that II-1 may be an essential signal required by 11-2 producer T cells (Smith et al. 1979, 1980, Farrar et al. 1980, Larsson et al. 1980). Although the involvement of II-1 in the production of II-2 by ligand-stimulated T cells appears unquestionable, the precise mechanism by which II-1 functions in this capacity

Dopamine Synaptic Mechanisms Reflected in Studies Combining Behavioural Recordings and Brain Dialysis

Abstract: By using a new technique of brain dialysis, it has been possible to recover endogenously released dopamine and aminoacids in awake as well as anaesthetized rats. By combining dialysis experiments with behavioural recordings we have studied the relationship between neurotransmission and behaviour. The results indicate that changes in receptor sensitivity may take place in direct response to changes in transmitter release. Studies with rotational behaviour strongly suggest the existence of dopamine receptor sites preferentially stimulated by apomorphine or pergolide and preferentially inhibited by cis-flupenthixol and sulpiride respectively. These receptor sites seem to relate differently to cholinergic and GABA-ergic mechanisms. Finally we describe the surprising finding that methylxanthines induce rotational behaviour in a way very similar to known dopamine agonists.

Evidence for a neurotrophic role of noradrenaline neurons in the postnatal development of rat cerebral cortex

Abstract: The effects of neonatal administration of the catecholamine neurotoxin 6-hydroxydopamine (6-OHDA; 1–4 doses of 100 mg/kg body weight s.c.) on the postnatal development of pyramidal neurons in several cortical regions of the rat was studied using a Golgi-Cox neuronal impregnation technique. Rats were sacrificed in the adult stage (eight weeks) and the following regions were studied: anterior frontal cortex, posterior frontal cortex (including motor cortex), anterior parietal cortex (including sensory cortex), posterior parieto-occipital cortex and cingulate cortex. Significant alterations were seen in animals which received four doses of 6-OHDA. These alterations can be summarized as follows: (1) a decreased length and branching of basolateral dendrites of pyramidal cells, with loss of dendritic spines, which were found in both the internal pyrimidal layer (layer V) and the external pyramidal layer (layer III), most abundantly in the frontal cortex and cingulate cortex; (2) an increased number of pyramidal cells of layer V with premature apical dendritic termination in layer III rather than the usual termination in layers I and II. This was most abundant in the cingulate cortex; (3) occasional disorientation of pyramidal cell apical dendrites away from the normal vertical plane by 15 or more degrees, seen in frontal, parietal and cingulate cortex; (4) an increased number of pyramidal cells with rounded somatic contours, found in frontal, anterior parietal and cingulate cortex. These phenomena were occasionally seen in normal cortex, but were significantly increased in their occurrence after four doses of 6-OHDA. Such alterations were not significant in rats treated with one or three doses of 6-OHDA. The extent and severity of morphological alterations correlate with reductions in endogenous noradrenaline (NA) in cerebral cortex, which was found to average 50% of control levels after one dose of 6-OHDA, an 80% reduction after three doses, and a 97–98% reduction after four doses, suggesting that the NA denervation must be almost complete to result in readily detectable significant morphological changes in the development of cortical pyramidal cells. No consistent changes in endogenous dopamine (DA) levels were observed, except for an increase in the cingulate cortex. The anatomical alterations in pyramidal cells described in the present study suggest that NA neurons which project into the cerebral cortex have a neurotrophic role in the postnatal development of cortex.

Lumbar back muscle activity in relation to trunk movements during locomotion in man

Abstract: The function of lumbar back muscles was studied by relating their activity patterns to trunk movements in 7 healthy adult males during normal walking (1.0-2.5 m/s) and running (2.0-7.0 m/s) on a treadmill. The movements of the trunk in the sagittal and frontal planes were recorded with a Selspot optoelectronic system using infrared light emitting diodes as markers. The electromyographic (EMG) activity from the two main portions of the lumbar erector spinae muscles (Multifidus and Longissimus) was recorded bilaterally with intramuscular wire electrodes. The angular displacements of the trunk showed regular oscillations, but their shape, magnitude and relation to the step cycle were different in the two planes (sagittal and frontal) and varied with speed and mode of progression. The EMG pattern in both muscles showed a bilateral cocontraction with two main bursts of activity per step cycle starting just before each foot was placed on the ground. Relating the EMG to the movements of the trunk indicated that the main function of the lumbar erector spinae muscles is to restrict excessive trunk movements. During walking this restricting action is most evident for movements in the frontal plane, whereas in running the lumbar back muscles mainly control the movements in the sagittal plane.

Vasoactive intestinal polypeptide enhances muscarinic ligand binding in cat submandibular salivary gland.

Abstract: The salivary secretion from the cat submandibular salivary gland induced by parasympathetic nerve stimulation is considered to be due to release of acetylcholine (ACh) which binds to muscarinic receptors and activates secretory elements1. Recent evidence suggests that cholinergic neurones in the cat submandibular gland contain and release another neurotransmitter candidate, vasoactive intestinal polypeptide (VIP)2,3. Although VIP per se does not induce salivary secretion, it potentiates the secretion induced by ACh infusions2,3. The present study offers a possible explanation for this potentiation by showing that VIP in physiologically relevant concentrations enhances the binding of muscarinic cholinergic ligands in the cat submandibular gland.

Cyclosporin A--usefulness, risks and mechanism of action.

Abstract: Very little new happened in the field of immunosuppression after the discovery of azathioprine in the early 'sixties (Schwarz et al. 1959). Admittedly, there has been the introduction of heterologous antilymphocyte serum (Starzl et al. 1967), which to some extent has become a part of the regular therapeutic regimen in organ transplantation. Other than that, very little that could stop an immune response has been brought forward by the immunologists during these two past decades. Nevertheless, the understanding of immune functions has advanced a great deal during that same period, although in terms of immunosuppression the transplant surgeons were left with the old, but not so effective combination of steroids, azathoprine and somewhat later anti-lymphocyte serum (that, indeed, they still use). But a new drug is rapidly invading the market. That is cyclosporin A (CyA), which is the scope of this review. Although it was detected nearly 10 years ago (Borel 1976), it is still new as it is presently being scrutinized in clinical trials in man and is thus not commonly in use yet. In most countries it has as yet only been used for very limited purposes. The attraction of this compound is multifold, but one feature is that, unlike all other immunosuppressants, tentative mechanisms of action for it have been brought forward based on interpretable experimental data. This is, we think, why a review of the present state of knowledge on cyclosporin A is warranted. The drug has already been admirably analyzed in these reviews (Calne 1979), but much relevant information on it has accumulated since then.

Inhibition of in vitro granulopoiesis by autologous allogeneic human NK cells.

Abstract: This study demonstrates the ability of human NK cells to inhibit in vitro granulopoiesis of autologous and allogeneic BM cells. NK lytic activity and GM-CFC inhibition was present among nonstimulated lymphocytes from healthy donors and could be increased by treatment of PBL with IFN. Both the cytotoxic NK cells and the GM-CFC inhibitory cells could be enriched for among nonadherent, low-density cells. High-density cells were not cytotoxic, only inhibitory to a small extent, and could become neither cytotoxic nor more inhibitory after IFN treatment. In contrast, low-density cells showed an increased cytotoxic and GM-CFC inhibitory capacity after IFN treatment. The NK mediated GM-CFC inhibition was dependent on cell contact with BM cells, increased with longer preincubation times, and was most efficient against 7-day GM-CFC as compared with 14 day GM-CFC progenitors. In conclusion, these data provide new information about the human NK cell as a potent inhibitor of in vitro granulopoiesis and also as a possible regulator of hematopoiesis in vivo.

Leukotriene C4 affects pulmonary and cardiovascular dynamics in monkey.

Abstract: Leukotriene C4 (LTC4) and its metabolites LTD4 and LTE4 (Fig. 1) have been identified as the major active constituents of slow-reacting substance of anaphylaxis (SRS-A)1–3. Leukotrienes C4, D4 and E4 have rapidly gained recognition as bronchoconstrictors of hitherto unsurpassed potency in the guinea pig in vivo and in vitro4–7 as well as acting as oedema-forming substances in guinea pig3,5,7 and hamster8. Here we report that LTC4 is also a prominent bronchoconstrictor in the monkey; it increases transpulmonary pressure in the anaesthetized animal, mainly by decreasing pulmonary dynamic compliance, and it contracts isolated tracheal spiral tissue. Furthermore, LTC4 causes transient pulmonary and systemic hypertension, followed by a prolonged hypotensive period associated with decreased cardiac output, haemoconcentration and reduction in the number of circulating leukocytes. These in vivo findings in a primate imply that leukotrienes may also cause important alterations of cardiovascular and pulmonary function in man.

Somatotopic organization of vibrissae afferents in the trigeminal sensory nuclei of the rat studied by transganglionic transport of HRP.

Abstract: Transganglionic transport of horseradish peroxidase (HRP) has been used to study the cell bodies and central projections of neurons innervating the vibrissae in the rat. These can be grouped into five horizontal rows and one posterior vertical row. Twenty-four to 48 hours after the nerves innervating different vibrissae were exposed to HRP, the trigeminal ganglia, brainstem, and upper cervical spinal cord were fixed by perfusion and serial sections were processed according to the tetramethylbenzidine technique. The results revealed a tendency for somatotopic organization in the trigeminal ganglion of cell bodies innervating the different vibrissae. Corresponding termination areas in the trigeminal sensory nuclei showed a detailed pattern of organization replicating the peripheral organization of the vibrissae. In all trigeminal sensory nuclei the horizontal rows are represented in an inverted fashion from dorsal to ventral, i.e., the most dorsal row is represented most ventrally. In addition, the more anterior a vibrissa is located, the deeper is it represented in the rostral nonlaminated nuclei. The situation is reversed in the laminated nucleus caudalis. The posterior vertical row is represented most superficially in the rostral nonlaminated nuclei, but most deeply in the laminated nucleus caudalis. In nucleus caudalis there are also rostrocaudal differences in the representation of different vibrissae. Thus, the posterior vibrissae in a horizontal row have their main representations more caudally than the anterior vibrissae. The posterior vertical row has its main representation most caudally, in the C1 segment.