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Biomedical subjects

W Su

Publications and source records attributed to W Su.

At least 91 records · Page 5Linked to original sources
PubMed1998

Pharmacological characterization of endomorphin-1 and endomorphin-2 in mouse brain.

The recently isolated peptides endomorphin-1 and endomorphin-2 have been suggested to be the endogenous ligands for the mu receptor. In traditional opioid receptor binding assays in mouse brain homogenates, both endomorphin-1 and endomorphin-2 competed both mu1 and mu2 receptor sites quite potently. Neither compound had appreciable affinity for either delta or kappa1 receptors, confirming an earlier report. However, the two endomorphins displayed reasonable affinities for kappa3 binding sites, with Ki values between 20 and 30 nM. Both endomorphins competed 3H-[D-Ala2, MePhe4,Gly(ol)5] enkephalin binding to MOR-1 receptors expressed in CHO cells with high affinity. In mouse brain homogenates 125I-endomorphin-1 and 125I-endomorphin-2 binding was selectively competed by mu ligands. 125I-Endomorphin-1 and 125I-endomorphin-2 also labeled MOR-1 receptors expressed in CHO cells with high affinity. Autoradiography of the two 125I-labeled endomorphins demonstrated regional patterns in the brain similar to those previously observed for mu drugs. Pharmacologically, the endomorphins were potent analgesics. Although they were equipotent supraspinally, endomorphin-1 was more potent spinally. Endomorphin analgesia was effectively blocked by naloxone, as well as the mu-selective antagonists beta-funaltrexamine and naloxonazine. In CXBK mice, which are insensitive to supraspinal morphine, neither endomorphin was active, consistent with a mu mechanism of action. Finally, the endomorphins inhibited gastrointestinal transit. In conclusion, these results support the mu selectivity of these agents.

Analgesics, Opioid↗
PubMed1998

Selection of EPS-deficient mutants (Exo-) from Rhizobiun huakuii 107 by region-directed Tn5 mutagenesis.

pJB-B5 was a recombinant plasmid of pRK415 containing the 5.9 kb B5 fragment from exoR'-11. After pJB-B5 was mutagenized by MT614 (mal::Tn5), 10 plasmids TN1-1, TN1-12, TN2-2, TN2-3, TN3-1, TN4-1, TN9-1, TN10-1, TN13-1, and TN14-1 with different Tn5 insertions in the B5 fragment were constructed. By conjugation of TN1-1, etc., into Rhizobium huakuii 107 containing the P-group plasmid pPH1JI which is incompatible with pRK415, and simultaneous selection for Rifr (conferred by strain 107), Gm(r) (conferred by pPH1JI), and Nmr (retention of Tn5), R. huakuii 107 transconjugant yields a strain in which Tn5 has recombined into the R. huakuii 107 genome. Three EPS-deficient (Exo-) mutants 107 (TN2-2), 107 (TN10-1), and 107 (TN13-1) were isolated and their inserted Tn5 was certified as the result of a double homologous recombinant event by Southern hybridization analysis. This result showed the Tn5 region-directed mutagenesis is an efficient way to select Exo- mutant in R. huakuii.

DNA Transposable Elements↗
PubMed1997

Analysis of organic and inorganic selenium anions by ion chromatography-inductively coupled plasma atomic emission spectroscopy.

We report analysis of both inorganic and amino acid forms of selenium by ion chromatography with inductively coupled plasma atomic emission spectroscopic detection. Three chromatographic systems are compared; effects of representative sample matrices on the separations are investigated. We are unable to resolve selenate and seleno-cystine using the Dionex AS4A column. Elution of seleno-cystine and seleno-cysteine is strongly suppressed in samples of bacterial cell extract matrix analyzed with the Dionex AS10 column; this interference is not observed with the Dionex AS11 column. Synthetic sea water sample matrix has little effect on analytical results. Quantitation parameters are reported.

Amino Acids↗
PubMed1997

Mapping of the residues involved in a proposed beta-strand located in the ferric enterobactin receptor FepA using site-directed spin-labeling.

Electron paramagnetic resonance (EPR) site-directed spin-labeling (SDSL) has been used to characterize a proposed transmembrane beta-strand of the Escherichia coli ferric enterobactin receptor, FepA. Each of nine consecutive residues was mutated to cysteine and subsequently labeled with the sulfhydryl-specific spin-label methanethiosulfonate (MTSL) and the purified protein reconstituted into liposomes. Continuous wave (CW) power saturation methods were used to determine exposure of the nitroxide side chains to a series of paramagnetic relaxation agents, including nickel acetylacetonate (NiAA), nickel ethylenediaminediacetate (NiEDDA), chromium oxalate (CROX), and molecular oxygen. The spin-label attached to Q245C, L247C, L249C, A251C, and Y253C had higher collision frequencies with molecular oxygen than with polar relaxation agents, indicating that these sites are exposed to the hydrophobic phase of the lipid bilayer. MTSL bound to residues S246C, E248C, E250C, and G252C had higher collision rates with the polar agents than with oxygen, suggesting that these sites are exposed to the aqueous channel. The alternating periodicity observed with the polar relaxation agents, NiAA and NiEDDA, and in opposite phase with oxygen, is consistent with beta-sheet structure. Depth measurements, based on the reciprocal concentration gradients of NiEDDA and O2 across the bilayer and calibrated for our system with phosphatidylcholine spin-labels, indicated that L249C was nearest the center of the bilayer and that Q245C and Y253C were located just below the bilayer surface in opposite leaflets of the membrane. Thus, we conclude that this approach, through mapping of individual residues, has the capability of defining beta-sheet secondary structure.

Amino Acid Sequence↗
PubMed1997

Biotinylated dextran amine and biocytin hydrochloride are useful tracers for the study of retinal projections in the frog.

Anatomical study of the topographic organization of retinal projections requires a tracer capable of resolving fine morphological detail and permitting analysis of the projection from either the whole retina or selected areas. To obtain a permanent record of the experiments and to have access to ultrastructural data, it is preferable for the tracer to be compatible with both brightfield microscopy and electron microscopy. Biotinylated dextran amine and biocytin hydrochloride, as employed in the present experiments, meet these needs exceptionally well for anterograde tracing studies on the frog visual system. Both tracers labeled axons and terminal arbors more prominently than comparable material studied by the widely used methods of anterograde fiber-filling with horseradish peroxidase or cobalt. When used to trace the projections from small sectors of retina, the finest unmyelinated fibers in layers A, C and E of the frog optic tectum and their synaptic boutons were made readily visible by the new tracers.

Animals↗
PubMed1997

A compartment-based, asymmetric representation of the retina in an induced projection to the olfactory cortex.

Displacing the optic nerve into the telencephalon in adult Rana pipiens induces a projection to olfactory cortex. We have examined the topographic organization of this projection anatomically by injecting a mixture of biotin dextran (BDA) with 3H-amino acids into the affected eye immediately after making cuts across defined sectors of the nerve fiber layer to trace the complementary patterns of anterograde migration of BDA and 3H label in the cut and intact retinal axons, respectively. Fibers from the temporal side of the optic disc terminated in an oblique band along the posterior two-thirds or more of the ectopic projection field. In contrast, fibers arising in the nasal retina terminated in a parallel strip occupying the anterior one-third or less of the field. Varying the location of the cuts within each hemiretina did not reveal any further organization along the nasotemporal or dorsoventral axes of the retina. The retinal location of the cells involved in this projection was further studied with injections of wheat germ agglutinin conjugated to horseradish peroxidase into the olfactory cortex. Ganglion cells labeled by retrograde transport were found throughout the retina, but they were much more numerous on the temporal side, having a mean spatial density 3.7-7.4 times greater in the temporal hemiretina, whereas the overall ganglion cell density (labeled plus unlabeled) was roughly the same in the two halves of the retina. These data provide an example of a permanent projection in which the overall representation of the retina, though nontopological, is polarized in one axis (nasotemporal) and, therefore, compartmentally organized.

Animals↗
PubMed1997

Antisense mapping DOR-1 in mice: further support for delta receptor subtypes.

In contrast to the pharmacological studies implicating delta-opioid receptor subtypes, cloning studies have identified only a single cDNA encoding a delta receptor, DOR-1. Antisense studies have established the importance of DOR-1 in delta analgesia in mice. Antisense mapping extends this approach to include oligodeoxynucleotides which are targeted against each of the exons of the gene. Five different antisense oligodeoxynucleotides based upon the three DOR-1 exons all block both spinal and supraspinal analgesic actions of the delta2 ligand [D-Ala2,Glu4]deltorphin, consistent with the suggestion that DOR-1 encodes the delta2 receptor. At the spinal level, [D-Pen2,D-Pen5]enkephalin (DPDPE) acts also acts through delta2 receptors and all the antisense probes block spinal DPDPE analgesia. However, supraspinally only the two antisense probes targeting exon 3 block DPDPE analgesia. The remaining three antisense probes based upon exons 1 and 2 are inactive. Thus, the delta receptors responsible for spinal and supraspinal DPDPE analgesia can be discriminated at the molecular level by antisense mapping.

Analgesia↗
PubMed1997

Combined radiofrequency ablation-cooling catheter for reversible cryothermal mapping and ablation.

Reversible cryothermal mapping of cardiac arrhythmias has been performed intraoperatively. However, a steerable cooling catheter for reversible mapping has not yet been developed. We therefore developed and tested a cooling system consisting of a -15 degrees C hypertonic saline reservoir and a 7F steerable catheter also capable of radiofrequency (RF) ablation. Using excised ovine hearts placed in a 37 degrees C circulating saline bath, we measured the temperatures at depths of 0 mm, 1 mm, and 2 mm. The temperature after 90 seconds of cooling was 16.5 +/- 2.1 degrees C at 0 mm compared to 23.9 +/- 4.1 degrees C at 1 mm and 31.1 +/- 3.9 degrees C at 2 mm depth (p < 0.01). These data suggest that a 7F steerable combined RF ablation-cooling catheter may achieve temperatures suitable for mapping arrhythmias such as atrial tachycardias and right ventricular outflow tract tachycardias. Further enhancements to achieve lower temperatures at depth may be needed to reversibly map other arrhythmias such as left ventricular tachycardias.

Animals↗
PubMed1997

Analysis of wild-type and mutant plant nitrate reductase expressed in the methylotrophic yeast Pichia pastoris.

Recombinant Arabidopsis thaliana NADH:nitrate reductase (NR; EC 1.6.6.1) was produced in the methylotrophic yeast Pichia pastoris and purified to near-electrophoretic homogeneity. Purified enzyme had the spectral and kinetic properties typical of highly purified NR from natural plant sources. Site-directed mutagenesis altering several key residues and regions was carried out, and the mutant enzyme forms were expressed in P. pastoris. When the invariant cysteine residue, cysteine-191, in the molybdo-pterin region of the A. thaliana NIA2 protein was replaced with serine or alanine, the NR protein was still produced but was inactive, showing that this residue is essential for enzyme activity. Deletions or substitutions of the conserved N terminus of NR retained activity and the ability to be inactivated in vitro when incubated with ATP. Enzyme with a histidine sequence appended to the N terminus was still active and was easily purified using metal-chelate affinity chromatography. These results demonstrate that P. pastoris is a useful and reliable system for producing recombinant holo-NR from plants.

Arabidopsis↗
PubMed1997

Antisense mapping of MOR-1 in rats: distinguishing between morphine and morphine-6beta-glucuronide antinociception.

In an effort to correlate the recently cloned MOR-1 receptor with the pharmacological actions of morphine and morphine-6beta-glucuronide (M6G), we have used an antisense paradigm. Rats were injected intracerebroventricularly (i.c.v.) with antisense oligodeoxynucleotides on days 1, 3 and 5 and tested for analgesia on day 6 after administration of morphine or M6G i.c.v. or after microinjection of morphine directly into either the periaqueductal gray or the locus coeruleus. When given i.c.v., the antisense oligodeoxynucleotide targeting the 5'-untranslated region of exon 1 significantly decreased the analgesic actions of morphine administered i.c.v. or microinjected directly into the periaqueductal gray or locus coeruleus, with the most profound inhibition occurring in the periaqueductal gray. Thus, antisense oligodeoxynucleotides administered into the lateral ventricle can diffuse into the brainstem and interfere with morphine actions. A mismatch antisense oligodeoxynucleotide with the same base composition in which the sequence of four bases was changed was inactive. This same exon 1 antisense oligodeoxynucleotide, which was active against morphine analgesia, failed to block M6G analgesia. In contrast, antisense sequences from exons 2 and 3 decreased M6G, and not morphine, analgesia. The antisense oligodeoxynucleotide against exon 4 slightly decreased both morphine and M6G antinociception. These results confirm the antisense mapping studies on exons 1, 2 and 3 of MOR-1 in mice, which implied the presence of a novel mu receptor subtype responsible for M6G analgesia that may represent a splice variant of MOR-1. Unlike in mice, the probe against exon 4 had a small effect on M6G analgesia.

Analgesia↗
PubMed1996

Planet Within a Planet: Rotation of the Inner Core of Earth

The time dependence of the orientation of Earth's inner core relative to the mantle was determined using a recently discovered 10-degree tilt in the axis of symmetry of the inner core's seismic-velocity anisotropy. Two methods of analyzing travel-time variations for rays traversing the inner core, on the basis of 29 years of data from the International Seismological Centre (1964-1992), reveal that the inner core appears to rotate about 3 degrees per year faster than the mantle. An anomalous variation in inner-core orientation from 1969 to 1973 coincides in time with a sudden change ("jerk") in the geomagnetic field.

Journal Article↗
PubMed1996

Comparison of energy intakes determined by food records and doubly labeled water in women participating in a dietary-intervention trial.

The accuracy of estimates of usual energy intake derived from food records in participants of a long-term dietary-intervention trial was studied in a subset of 29 women aged 48.7+/-5.0 y and weighing 61.9+/-6.5 kg. This sample was similar to the population in the whole trial (n=715), from which it was selected in terms of age, weight, body mass index (BMI), and reported energy and fat intakes. During the validation study, reported energy intake was derived from 7 consecutive days of food records, and total energy expenditure was measured by the doubly labeled water method over 13 d. Reported energy intake (6.98+/-1.58 MJ/d) was significantly lower than energy expenditure (9.00+/-2.08MJ/d) and represented 79.8+/-17.6% of expenditure. The correlation between reported energy intake and expenditure was 0.46 (P=0.01, 95% CI: 0.15, 0.71). Body weight, BMI, height, length of time in the dietary trial, and percentage of energy from fat and carbohydrate were not significantly associated with the accuracy of reporting. These results indicate that energy intake derived from food records is an imprecise measure that substantially underestimates energy intake in middle-aged women participating in a long-term dietary-intervention trial.

Adult↗
PubMed1996

Identification in vitro of a post-translational regulatory site in the hinge 1 region of Arabidopsis nitrate reductase.

Nitrate reductase (NR) is rapidly inactivated by phosphorylation of serine residues in response to loss of light or reduction in CO2 levels. To identify sites within NR protein that play a role in this post-translational regulation, a heterologous expression system and an in vitro inactivation assay for Arabidopsis NR were developed. Protein extracts containing NR kinases and inhibitor proteins were prepared from an NR-defective mutant that had lesions in both the NIA1 and NIA2 NR genes of Arabidopsis. Active NR protein was produced in a Pichia pastoris expression system. Incubation of these two preparations resulted in a Mg-ATP-dependent inactivation of NR that was reversed with EDTA. Mutant forms of NR were constructed, produced in P. pastoris, and tested in the in vitro inactivation assay. Six conserved serine residues in the hinge 1 region of NR, which separates the molybdenum cofactor and heme domains, were specifically targeted for mutagenesis because they are located in a potential regulatory region identified as a target for NR kinases in spinach. A change in Ser-534 to aspartate was found to block NR inactivation; changes in the other five serines had no effect. The aspartate that replaced Ser-534 did not appear to mimic a phosphorylated serine but simply prevented the NR from being inactivated. These results identify Ser-534, located in the hinge 1 of NR and conserved among higher plants NRs, as an essential site for post-translational regulation in vitro.

Amino Acid Sequence↗
PubMed1996

Determinants of weight loss following ileogastrostomy.

To examine the factors associated with weight loss following ileogastrostomy, (i) energy expenditure, (ii) body composition and (iii) urinary and fecal energy losses were examined in 11 morbidly obese subjects (36 +/- 3 y, 43.7 +/- 0.9 kg/m2 BMI, 47.0 +/- 1.3% body fat (BF) (mean +/- SEM) prior to and after this surgical procedure. Respiratory gas exchange analysis was used to measure changes in basal energy expenditure (BEE) and thermic effect of food (TEF). Total energy expenditure (TEE) was determined by doubly labeled water (DLW) method over 14 d during 6-8 weeks after surgery. Body composition was assessed using isotope dilution space (IDS) method. Illegastrostomy did not significantly influence BEE levels but TEF declined following surgery (p = 0.001). There was a significant decline (p < 0.0001) in fat-free mass (FFM) and fat mass (FM). Weight loss was closely associated with TEE (r = 0.719, p = 0.019, n = 10), and fecal energy content (r = 0.808, p = 0.052, n = 6) but not with urinary energy loss (r = 0.011, p = 0.983, n = 6). The results indicate that ileogastrostomy blunts TEF levels and both FFM and FM declined following surgery. Total energy expenditure and fecal energy losses appear to be important determinants in the extent of weight loss following ileogastrostomy.

Adult↗
PubMed1996

Research into analgesia by inhaling analgesic.

This article deals with analgesia by inhaling analgesic. According to Chinese medical theories, TCM analgesics were chosen from the literature and folk prescriptions screened and proved by analgesic tests on animals. A reasonable prescription was made up and the drug inhaled. Its analgesic effect was superior to that of dolantin injection (3 mg/kg body weight, intraperitoneal injection). Clinical trials showed its analgesic effect in 3-10 minutes and it lasted for more than 2 hours in over 70% of the cases for a total effective rate of 94.6%. The drug is absorbed quickly and acts directly on the nerve center. Its use is not addictive.

Administration, Inhalation↗