Discrimination of heterozygous carriage of ataxia-telangiectasia by the method of indirect immunofluorescent analysis

Qualitative differences of the stabilization of protein P53 were studied by methods of indirect immunofluorescence with the use of confocal microscopy in cells obtained from members of the family of a patient with ataxia-telangiectasia (AT)—the proband AT6SP and her blood relatives: the sister AT(S)6SP and the father AT(F)6SP—at different time periods after irradiation with various doses of ionizing radiation.     

Hydrolysis of substance p and neurotensin by converting enzyme and neutral endopeptidase

Angiotensin I converting enzyme (ACE) and neutral endopeptidase ("enkephalinase"; NEP), were purified to homogeneity from human kidney. NEP cleaved substance P (SP) at Gln6-Phe7,-Phe8, and Gly9-Leu10 and neurotensin (NT) at Pro10-Tyr11 and Tyr11-Ile12. NEP hydrolyzed 0.1 mM SP, NT and their C-terminal fragments at the following rates (mumol/min/mg): SP1-11 = 7.8, SP4-11 = 11.7, SP5-11 = 15.4, SP6-11 = 15.6, SP8-11 = 6.7, NT1-13 = 2.9, and NT8-13 = 4.0. Purified ACE rapidly inactivated SP as measured in bioassay. HPLC analysis showed that ACE cleaved SP at Phe8-Gly9 and Gly9-Leu10 to release C-terminal tri- and dipeptide (ratio = 4:1). The hydrolysis was Cl- dependent and inhibited by captopril. ACE released mainly C-terminal tripeptide from SP methyl ester, but only dipeptide from SP free acid. Modification of arginine residues in ACE with cyclohexanedione or butanedione similarly inhibited hydrolysis of SP, bradykinin and Bz-Gly-Phe-Arg (80-93%) indicating an active site arginine is required for hydrolysis of SP. ACE hydrolyzed NT at Tyr11-Ile12 to release Ile12-Leu13. SP, NT and their derivatives (0.1 mM) were cleaved by ACE at the following rates (mumol/min/mg): SP1-11 = 1.2, SP methyl ester = 0.7, SP free acid = 8.5, SP4-11 = 2.4, SP5-11 = 0.9, SP6-11 = 1.4, SP8-11 = 0, NT1-13 = 0.2, and NT8-13 = 1.3. Peptide substrates were used as inhibitors of ACE (substrate = FA-Phe-Gly-Gly) and NEP (substrate = Leu5-enkephalin).(ABSTRACT TRUNCATED AT 250 WORDS)     

Vasoactive effects of substance P on isolated rabbit pulmonary artery

The vasoactive properties of substance P (SP) were studied in isolated rabbit pulmonary artery (PA) segments in vitro. In the absence of active base-line tone, noncumulative administration of SP (10(-11) to 10(-4) M) produced dose-dependent increases in PA tension. The peak isometric tension (Tmax) with SP was similar to the Tmax response to epinephrine; however, the doses of the agonist producing a threshold contraction and 25% of Tmax (ED25) were significantly lower for SP. In the presence of active base-line tone, induced by epinephrine or 5-hydroxytryptamine, SP produced transient PA relaxation which was directly related to the magnitude of the precontracted PA tension. Blockade of neurotransmission with tetrodotoxin (1 microgram/ml) and antagonists to alpha 1-adrenergic and histamine receptor binding had no effect on the contractile response to SP. On the other hand, PA contraction to an ED50 dose of SP was 1) inhibited by a mean of 33 +/- 10% (SE) following pretreatment with the cholinesterase inhibitor, neostigmine (10(-6) M) and 2) augmented by 52 +/- 21% with the cholinergic antagonist, atropine (10(-4) M). The latter also completely blocked the relaxation response to SP in precontracted PA. Similarly, removal of the PA endothelium also abolished the relaxation response to SP. In contrast, SP-induced contraction was markedly inhibited by the cyclooxygenase inhibitor, meclofenamate (1 microgram/ml), as well as the SP antagonist, D-Pro2, D-Trp7,9-SP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of substance P on neurally mediated contraction of rabbit airway smooth muscle

The neuromodulatory action of substance P (SP) was investigated in isolated rabbit tracheal smooth muscle (TSM) segments contracted with electrical field stimulation (ES). The tissues were placed in organ baths containing modified Krebs-Ringer solution and stimulated at a constant voltage (8 V; 24.5 mA) and pulse duration (2 ms) with ES frequencies ranging from 1 to 100 Hz. In the presence of SP, there occurred a dose-dependent augmentation of the TSM contractile response to any given ES, with the maximal effect of SP obtained at a dose of 10(-7) M. Accordingly, with the administration of 10(-7) M SP, the ES frequency-response relationship was altered so that 1) the mean (+/- SE) maximal tension (Tmax) induced by ES significantly increased (P less than 0.02) from a base-line value of 273 +/- 53 to 402 +/- 45 g/g TSM; and 2) the mean (+/- SE) log ES frequency producing 50% of Tmax (ES50) significantly decreased from a base-line value of 1.278 +/- 0.069 to 1.102 +/- 0.070 Hz (P less than 0.01). In contrast to these effects on ES-induced contraction, SP administration did not affect the TSM contractile response to administered methacholine chloride (10(-8) to 10(-3) M). On the other hand, the effects of SP on ES-induced contraction were independently blocked by the cholinergic antagonist, atropine (10(-6) M); the neurotoxin, tetrodotoxin (10(-6) g/ml); and the SP antagonist, D-Arg1,D-Pro2,D-Trp7,9,Leu11-SP (10(-5) M).(ABSTRACT TRUNCATED AT 250 WORDS)     

Photoperiodic regulation of body mass, food intake, hibernation, and reproduction in intact and castrated male European hamsters,Cricetus cricetus

A group of sexually active male European hamsters were raised either in short-photoperiod conditions (SP; LD 8:16) or in long-photoperiod conditions (LP; LD 16:8) from their capture at the end of the hibernation period. Another group of hamsters was castrated in April and gonadectomized animals were maintained in SP and cold (7 degrees C) or in a succession of SP and LP plus cold. Another group, castrated in May or in September and raised in LP conditions, was transferred in September to SP conditions and cold. 1. Normal hamsters raised in continuous SP or LP apparently did not show signs of rhythmic behavior, except possibly in gonadal activity. 2. Body weight increased continuously, plasma testosterone levels oscillated between 1.5 and 2.5 ng/ml, and animals raised in SP and in cold did not enter hibernation. 3. Similar results were also found in castrated animals kept in SP conditions and cold. 4. The sequence LP-SP induced a decrease in food intake and body weight and a decrease in plasma testosterone levels and triggered entry into hibernation in both intact and castrated animals. 5. After 6 months continuously in SP and with exposure to cold spontaneous recrudescence in food intake and body weight occurred and hibernation ended in both intact and castrated animals. 6. In normal animals a spontaneous increase in plasma testosterone levels was observed. 7. In both normal and gonadectomized animals the phase of refractoriness could be broken by exposure to LP conditions. 8. The critical photoperiod lies between 15 and 15.5 h. These results demonstrate that the European hamster is a photoperiodic species.(ABSTRACT TRUNCATED AT 250 WORDS)     

ATP: a mediator for HCl-induced TRPV1 activation in esophageal mucosa

In esophageal mucosa, HCl causes TRPV1-mediated release of calcitonin gene-related peptide (CGRP) and substance P (SP) from submucosal neurons and of platelet-activating factor (PAF) from epithelial cells. CGRP and SP release was unaffected by PAF antagonists but reduced by the purinergic antagonist suramin. ATP caused CGRP and SP release from esophageal mucosa, confirming a role of ATP in the release. The human esophageal epithelial cell line HET-1A was used to identify epithelial cells as the site of ATP release. HCl caused ATP release from HET-1A, which was reduced by the TRPV1 antagonist 5-iodoresiniferatoxin. Real-time PCR demonstrated the presence of mRNA for several P2X and P2Y purinergic receptors in epithelial cells. HCl also increased activity of lyso-PAF acetyl-CoA transferase (lyso-PAF AT), the enzyme responsible for production of PAF. The increase was blocked by suramin. ATP caused a similar increase, confirming ATP as a mediator for the TRPV1-induced increase in enzyme activity. Repeated exposure of HET-1A cells to HCl over 2 days caused upregulation of mRNA and protein expression for lyso-PAF AT. Suramin blocked this response. Repeated exposure to ATP caused a similar mRNA increase, confirming ATP as a mediator for upregulation of the enzyme. Thus, HCl-induced activation of TRPV1 causes ATP release from esophageal epithelial cells that causes release of CGRP and SP from esophageal submucosal neurons and activation of lyso-PAF AT, the enzyme responsible for the production of PAF in epithelial cells. Repeated application of HCl or of ATP causes upregulation of lyso-PAF AT in epithelial cells.     

Continuous cultivation of Trypanosoma brucei blood stream forms in a medium containing a low concentration of serum protein without feeder cell layers

Blood stream forms (BSF) of Trypanosoma brucei brucei GUT at 3.1 were propagated in vitro in the absence of feeder layer cells at 37 C, using a modified Iscove's medium (HMI-18). The medium was supplemented with 0.05 mM bathocuproine sulfonate, 1.5 mM L-cysteine, 1 mM hypoxanthine, 0.2 mM 2-mercaptoethanol, 1 mM sodium pyruvate. 0.16 mM thymidine, and 20% (v/v) Serum Plus (SP) (Hazleton Biologics, Lenexa, Kansas). The latter contained a low level of serum proteins (13 micrograms/ml). Each primary culture was initiated by placing 3.5-4 x 10(6) BSFs isolated from infected mice in a flask containing 5 ml of the medium (HMI-9) supplemented with 10% fetal bovine serum (FBS) and 10% SP. The cultures were maintained by replacing the medium every 24 hr for 5-7 days. During this period, many BSFs died. However, from day 4 onward, long slender BSFs increased in number. On days 5-7, trypanosome suspensions were pooled and cell debris was removed by means of diethylaminoethyl cellulose (DE52) column chromatography. Blood stream forms then were collected by centrifugation, resuspended in fresh medium at 7-9 x 10(5)/ml, and transferred to new flasks. Subcultures were maintained by readjusting the BSF density to 7-9 x 10(5)/ml every 24 hr. Concentrations of FBS were reduced gradually at 5-7-day intervals by alternating the amounts of FBS and SP in HMI-9 with 5% FBS and 15% SP, with 2% FBS and 18% SP, and finally with 20% SP (HMI-18). By this method, 2-3 x 10(6) VSFs/ml were obtained consistently every 24 hr. for more than 80 days.(ABSTRACT TRUNCATED AT 250 WORDS)     

Design of chimeric peptide ligands to galanin receptors and substance P receptors.

Several chimeric peptides were synthesized and found to be high-affinity ligands for both galanin and substance P receptors in membranes from the rat hypothalamus. The peptide galantide, composed of the N-terminal part of galanin and C-terminal part of substance P (SP), galanin-(1-12)-Pro-SP-(5-11) amide, which is the first galanin antagonist to be reported, recognizes two classes of galanin binding sites (KD(1) less than 0.1 nM and KD(2) approximately 6 nM) in the rat hypothalamus, while it appears to bind to a single population of SP receptors (KD approximately 40 nM). The chimeric peptide has higher affinity towards galanin receptors than the endogenous peptide galanin-(1-29) (KD approximately 1 nM) or its N-terminal fragment galanin-(1-13) (KD approximately 1 microM), which constitutes the N-terminus of the chimeric peptide. Galantide has also higher affinity for the SP receptors than the C-terminal SP fragment-(4-11) amide (KD = 0.4 microM), which constitutes its C-terminal portion. Substitution of amino acid residues, which is of importance for recognition of galanin by galanin receptors, such as [Trp2], in the galanin portion of the chimeric peptide or substitution of ([Phe7] or [Met11]-amide) in the SP portion of chimeric peptide both cause significant loss in affinity of the analogs of galantide for both the galanin- and the SP-receptors. These results suggest that the high affinity of the chimeric peptide, galantide, may in part be accounted for by simultaneous recognition/binding to both receptors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tachykinin Systems in the Spinal Cord and Basal Ganglia: Influence of Neonatal Capsaicin Treatment or Dopaminergic Intervention on Levels of Peptides, Substance P–Encoding mRNAs, and Substance P Receptor mRNA

The aim of the study was to test whether the synthesis of substance P (SP) and that of its receptor (also known as NK1 receptor) are coordinately regulated after chronic pharmacologic intervention in two neural systems, the spinal cord and basal ganglia. In one set of experiments, capsaicin was administered subcutaneously during the early postnatal period (day 3 after birth) to induce degeneration of afferent sensory neurons in the spinal cord. In the other set of experiments, interruption of dopaminergic transmission was achieved by two methods: (a) The neurotoxin 6-hydroxydopamine was used to denervate dopaminergic neurons during the early postnatal period, and (b) haloperidol was used in adult animals to block dopaminergic transmission by receptor blockade. The spinal cord, striatum, or both were used for the quantification of tachykinin [SP and neurokinin A (NKA)] and opioid peptides [[Met5]-enkephalin (ME) and dynorphin A (1-8) (DYN)] by radioimmunoassays. The abundance of total SP-encoding preprotachykinin (PPT) mRNA and SP receptor (SPR) mRNA in spinal cord (C5 to T1 segments), striatum, or microdissected substantia nigra was determined by northern blot or solution hybridization analysis. Amines and their acid metabolites were quantified by HPLC. Capsaicin administration (subcutaneously) during the early postnatal period increased latency in a hot-plate test, decreased SP and NKA levels, increased levels of PPT mRNAs, and did not affect SPR mRNA levels in the spinal cord. Intraspinal SP systems may attempt to compensate for the loss of afferent SP input, whereas spinal cord receptor mRNA levels do not appear to be altered.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rapid release of substance P and LH-RH from synaptosomes prepared from the medial basal hypothalamus and substantia nigra

We investigated Ca2+-dependent, depolarization-induced release of substance P (SP) and LH-RH from medial basal hypothalamic (MBH) and substantia nigra (SN) synaptosomes prepared from male rat brain. Depolarization of MBH synaptosomes evoked significant release of SP from 10.0 +/- 0.1 (5 mM K+) to 28.0 +/- 2.4 (75 mM K+) pg released/10 seconds. Fractional release was 1.0% and 2.7% respectively. In contrast, LH-RH was not released by depolarization of MBH synaptosomes: 11.6 +/- 0.9 (5 mM K+) to 11.0 +/- 0.7 (75 mM K+) pg released/10 seconds. Fractional release was 1.1 and 1.0% respectively. Depolarization-induced LH-RH release also did not occur in the presence of 10(-4) or 10(-6) M norepinephrine, 10(-7) M 12-O-tetradecanoylphorbol-13-acetate (TPA, PMA), 10(-5) M forskolin or in female rats. The inability of depolarizing concentrations of K+ to stimulate LH-RH release in physiological buffers remains an enigma. Significant depolarization-induced SP release was seen from MBH and SN synaptosomes at 20, 15, 10, 5 and only 1 second of release. Despite comparable basal release of SP from MBH and SN synaptosomes, the rate and magnitude of evoked release were much more pronounced in SN synaptosomes. The initial rate (0-1 second) of SP release was 4.5-fold greater from SN than from MBH synaptosomes [krel = 0.027(-1) (SN), krel = 0.006(-1) (MBH)]. The magnitude of SP release from SN synaptosomes was 2- to 3-fold greater at any given time interval compared with release from MBH synaptosomes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synthesis and biological activity of substance P analogues

The synthesis of the hexapeptide [Glu6]SP6-11 and its glycosylated analogue at the Glu6 gamma-carboxyl position by solution procedures according to several strategies is discussed. The biological activity of SP, [Glu6]SP6-11 (VI) and [Glu(beta-D-Glcp)6]SP6-11 (VIII) have been determined and compared to SP by the GPI and RVD assays. The introduction of a beta-D-glucopyranosyl moiety at the sixth position of the [Glu6]SP6-11 did not affect to a great extent the in vitro activity pattern of the parent hexapeptide.     

A comparison of the effects of substance P and shorter analogues on the synaptosomal ATPases activities in the rat brain

The influence in vitro of SP and C-terminal fragments of analogues SP(5-11) (pyroGlu5, Tyr8); SP(6-11) (pyroGlu6, Tyr8); SP(6-11) (pyroGlu6, D-Phe7); SP(6-11) (pyroGlu6, D-Phe8) on the (Ca, Mg) and (Na, K) ATPases activities from synaptosomal membranes of cerebral cortex and hippocampus of rat brain were compared. The data obtained in this study indicate the following: 1. Substance P stimulates the activities of (Na, K) and (Ca, Mg) ATPases more effectively in synaptosomal membranes from hippocampus than cerebral cortex. 2. Heptapeptide SP(5-11) (pyroGlu5, Tyr8) causes a more distinct increase of (Ca, Mg) ATPase activity in cortical synaptosomal membranes than SP does. 3. The change of L-Phe conformation to D in position 7 in hexapeptide induces reduction of enzymes activities in hippocampus. 4. Especially important for the maintenance of biological activity of drugs is the replacement of Gln5 with pyroGlu6 and conformation of Phe residues. 5. SP and shorter analogues of fragments SP C-terminal SP regulate the active cation transport in synaptosomal membranes of cerebral cortex and hippocampus.     

DECOMPOSITION DYNAMICS OF SPARTINA ALTERNIFLORA AND SPARTINA PATENS IN A NEW JERSEY SALT MARSH

Decomposition dynamics of two salt marsh species, Spartina alterniflora tall (SAT) form and Spartina patens (SP), were investigated at Mud Cove, near Manahawkin, Ocean County, New Jersey. Decomposition rates were determined monthly over 371 days by measuring the amount of material lost from plastic net litter bags. Litter bags containing SP material were placed in both SP and SAT vegetation zones; litter bags containing SAT material were also placed in both of these zones. The material was analyzed for ash content, total carbon, Kjeldahl nitrogen, caloric content, fat, and crude fiber. Final weight loss values were as follows: SAT in SAT zone 72.4%, SP in SAT zone 56.9%, SAT in SP zone 46.7%, and SP in SP zone 26.4%. When SAT and SP material were placed in the same location (SAT or SP sites), the SAT material decomposed at a greater rate. If the same vegetation type (SAT or SP) were placed in both SAT and SP locations, the material at the SAT location decomposed at a greater rate than similar material in the SP location. The results indicate that while environmental characteristics (e.g., flooding) at a site influence the rate at which these two species will decompose, Spartina patens is inherently more resistant to decomposition.     

Photoaffinity labeling the substance P receptor using a derivative of substance P containing p-benzoylphenylalanine.

A novel photoreactive substance P (SP) analogue has been synthesized by solid-phase peptide synthesis methodology to incorporate the amino acid p-benzoyl-L-phenylalanine [L-Phe(pBz)] in place of the Phe8 residue of SP. [Phe8(pBz)]SP was equipotent with SP in competing for SP binding sites on rat submaxillary gland membranes and had potent sialagogic activity in vivo. In the absence of light, the 125I-labeled Bolton-Hunter conjugate of [Phe8(pBz)]SP bound in a saturable and reversible manner to an apparently homogeneous class of binding sites (Bmax = 0.2 pmol/mg of membrane protein) with an affinity KD = 0.4 nM. The binding of 125I-[Phe8(pBz)]SP was inhibited competitively by various tachykinin peptides and analogues with the appropriate specificity for SP/NK-1 receptors. Upon photolysis, up to 70% of the specifically bound 125I-[Phe8(pBz)]SP underwent covalent linkage to two polypeptides of Mr = 53,000 and 46,000, identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Quantitative analysis of the inhibitory effects of SP and related peptides on 125I-[Phe8(pBz)]SP photoincorporation indicated that the binding sites of the two photolabeled polypeptides have the same peptide specificity, namely, that typical of NK-1-type SP receptors. In addition, the labeling of the two polypeptides was equally sensitive to inhibition by guanyl-5'-yl imidodiphosphate, a nonhydrolyzable analogue of GTP. Further information on the relationship between the two labeled SP binding sites was provided by enzymatic digestion studies: the Mr = 46,000 polypeptide contains N-linked carbohydrates and is derived most likely from the higher molecular weight species by proteolytic nicking.(ABSTRACT TRUNCATED AT 250 WORDS)     

Interaction of a substance P agonist and of substance P antagonists with lipid membranes. A thermodynamic analysis.

The molecular characteristics of the neuropeptide substance P (SP), its agonist [Sar9,Met-(O2)11]SP, and three of its antagonists [D-Arg1,D-Pro2,D-Trp7,9,Leu11]SP, [D-Arg1,D-Trp7,9,Leu11]SP, and [D-Pro2,D-Trp7,9]SP were investigated at the air/water interface and when bound to lipid monolayers and bilayers. Measurement of the Gibbs adsorption isotherm showed that the surface areas of SP and its agonist (240 +/- 5 A2 at biologically relevant concentrations) were distinctly larger than those of the antagonists (138 +/- 5 A2) [Seelig, A. (1990) Biochim. Biophys. Acta 1030, 111-118]. The surface activity of the peptides increased in the order [Sar9,Met(O2)11]SP less than SP less than [D-Pro2,D-Trp7,9]SP less than [D-Arg1,D-Trp7,9,Leu11]SP = [D-Arg1,D- Pro2,D-Trp7,9,Leu11]SP and correlated with the respective binding affinities to lipid membranes. The agonist did not insert into neutral and negatively charged bilayers or into densely packed lipid monolayers (at surface pressures greater than 31 mN/m). In contrast, the three antagonists gave rise to a strong binding both to neutral and to charged lipid monolayers and bilayers. The degree of binding was evaluated from the area increase of lipid monolayers upon peptide insertion, and the binding isotherms were analyzed in terms of the Gouy-Chapman theory. At the monolayer-bilayer equivalence pressure of approximately 32 mN/m, the binding can be described by a surface partition equilibrium with binding constants of (4.5 +/- 0.1) x 10(3) M-1 for [D-Pro2,D-Trp7,9]SP and (1.3 +/- 0.1) x 10(4) M-1 for both [D-Arg1,D-Trp7,9,Leu11]SP and [D-Arg1,D-Pro2,D-Trp7,9,Leu11]SP for pure palmitoyloleoylphosphatidylcholine (POPC) membranes.(ABSTRACT TRUNCATED AT 250 WORDS)     

An audit of liquid‐based cervical cytology screening samples (ThinPrep and SurePath) reported as glandular neoplasia

S. A. Thiryayi, J. Marshall and D. N. Rana
An audit of liquid‐based cervical cytology screening samples (ThinPrep and SurePath) reported as glandular neoplasia Objectives: The aims of this study were to assess the number of cases diagnosed as glandular neoplasia (national report code 6) of cervical (6A) and non‐cervical (6B) types on ThinPrep (TP) and SurePath (SP) liquid‐based cytology (LBC) samples and to calculate the positive predictive value (PPV) of these diagnoses for significant glandular and/or squamous pathology for local audit and as a contribution to national data on glandular neoplasia. Methods: A computerized search identified all screening LBC samples reported as glandular neoplasia during the 24‐month period from January 2006 to December 2007. Corresponding histology samples were identified, with a minimum follow‐up period of 6 months for each case. Results: A total of 70 samples, representing 70 patients, were reported as glandular neoplasia, 39 TP (55.7%) and 31 SP (44.3%), with 46 samples (31 TP, 15 SP) reported as 6A and 24 samples (eight TP, 16 SP) as 6B. PPV of glandular neoplasia was calculated for a biopsy diagnosis of cervical glandular intraepithelial neoplasia/adenocarcinoma and/or cervical intraepithelial neoplasia (CIN) 2 or worse. The PPV of 6A was 100% for both TP and SP. The PPV of 6B for adenocarcinoma was 62.5% for TP and 66.7% for SP. The combined PPV for 6A + 6B was 92.3% for TP, 83.3% for SP and 88.4% combined. The overall pick‐up rates for the two methods were significantly different (TP 0.031%, SP 0.052%; P = 0.014). Histology showed only CIN3 with endocervical crypt involvement in nine TP cases and one SP case.     

SEP topographies elicited by innocuous and noxious sural nerve stimulation. II. Effects of stimulus intensity on topographic pattern and amplitude

The effects of innocuous and noxious sural nerve stimulation on the SEP scalp topography were examined in 15 human subjects. This analysis focused on the 6 stable periods (i.e., consecutive time points where the topography did not change) that were identified in the companion paper (Dowman 1994). Stable period 1 (SP1: 58–90 msec post stimulus), SP4 (178–222 msec) and SP5 (223–277 msec) showed amplitude-stimulus intensity relationships that are similar to those of neurons involved in the sensory-discriminative aspects of innocuous somatosensation. The SP1 topographic pattern showed little or no change across the innocuous and noxious stimulus levels, which together with the amplitude data suggests that SP1 is largely generated by neurons involved in innocuous somatosensation. The SP4 topographic pattern did not change appreciably across the innocuous and noxious stimulus levels, but its aplitude decreased with increasing noxious stimulation. These data suggest that SP4 is generated by neurons involved in innocuous somatosensation and that noxious inputs inhibit these cells. There were differences in the SP5 topographic patterns evoked at the innocuous and the noxious stimulus levels, which suggest SP5 also receives a contribution from neurons involved in noxious somatosensation. SP3 (135–157 msec) and SP6 (282–339 msec) are probably generated by neurons involved in noxious somatosensation. The topographic patterns of both were different at innocuous and noxious levels. SP3's amplitude-stimulus intensity function suggests that it is generated by neurons that respond to noxious inputs in a non-graded fashion. The amplitude and offset latency of SP6 increased with increasing noxious stimulation, which suggests that SP6 is generated by neurons that respond to noxious inputs in a graded fashion.     

心房钠泵因子对颈动脉窦压力感受器反射的易化作用

Effects of atriopeptin II (APII) on the carotid sinus baroreflex in anesthetized rats and on the sinus nerve afferent activity in the anesthetized rabbits were investigated. The results were as follows: (1) By perfusing the isolated left carotid sinus with APII (1 microgram/ml) in anesthetized rats (n = 10), the threshold pressure (TP) of the carotid baroreflex did not show any change, while the equilibrium pressure (EP), the saturation pressure (SP) and the operating range (OR) were decreased from 101 +/- 2.8 to 95 +/- 2.0 mmHg (P less than 0.05), 202 +/- 5.2 to 168 +/- 6.1 mmHg (P less than 0.001) and 128 +/- 5.5 to 93 +/- 6.3 mmHg (P less than 0.001), respectively. The function curve of the baroreflex was shifted to the left and downward with a peak slope (PS) increased during perfusing with APII. In contrast, by perfusing the carotid sinus with sodium nitroprusside (NP, 0.5 micrograms/ml), TP and EP remained unchanged, whereas SP and OR were increased from 188 +/- 6.4 to 218 +/- 6.0 mmHg (n = 6, P less than 0.01) and from 107 +/- 6.9 to 132 +/- 7.6 mmHg (P less than 0.05), respectively. The function curve of the baroreflex and its PS were not affected by NP. The sinus nerve afferent activity was quite stable with the perfusion of carotid sinus at constant intrasinus pressure (ISP) in the rabbits (n = 6) and increased during the elevation of ISP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Replacement of phe(8) in substance P by tyr (Tyr(8)-SP) alters the conformation of the peptide in DMSO, water, and lipid bilayers.

The conformation of [Tyr(8)]SP (Y8SP) in dimethylsulfoxide (DMSO), water, and dipalmitoyl phosphatidylcholine (DPPC) bilayers has been investigated by two-dimensional nmr and molecular dynamics simulations. Molecular modeling of the conformation of Y8SP by incorporating nuclear Overhauser effects as distance restraints shows wide differences in its conformation in the three media. In DMSO, the main structural features are gamma-bends along with a nonspecific bend around Gln(6)-Phe(7)-Tyr(8). The random coil structure seen in water is transformed into a beta-turn around the segment Gln(5)-Gln(6)-Phe(7)-Tyr(8) when Y8SP is incorporated into DPPC bilayers. The lower biological activity of Y8SP compared to the native peptide (SP) has been attributed to the absence of any helix like structure at the central residues, a feature shown to be an important prerequisite for SP and SP agonists to bind to the neurokinin 1 tachykinin receptor.