Biomedical subjects

E Chiang

Publications and source records attributed to E Chiang.

16 recordsLinked to original sources

PubMed1998

The role of prior pain experience and expectancy in psychologically and physically induced pain.

Cognitive theories regarding symptom formation suggest that environmental factors such as warnings of impending pain and earlier experiences with pain can lead to a cognitive schema in which pain is selectively monitored. This study evaluated the role of prior experience with pain in the development of expectancy induced somatoform pain. Subjects from two experimental groups were connected to a sham stimulator and told to expect a headache. One of these groups, the physical stimulation first group, was exposed to pain induction by ice water and by pressure prior to the sham stimulation. A second group, the sham stimulation first group, received the sham stimulation followed by the cold water and pressure pain induction techniques. Subjects in the physical stimulation first group showed significant increases in their pain reports as settings on the sham stimulator were increased. Significant increases were not noted in the sham stimulation first group. The two groups did not differ in the number of subjects reporting pain or the mean maximal pain reported during the sham stimulation. Duration of cold water tolerance and the time until the analgesic threshold level for cold water were significantly shorter in subjects who had the sham stimulation first. This study suggests that prior pain can influence the reactivity to external suggestion for pain but does not increase the frequency of pain reports. It does suggest that the selective monitoring induced during the sham stimulation may influence later pain behaviours as was seen during the cold water tolerance testing.

Adult↗

PubMed1997

Alternative peptide binding motifs of Qa-2 class Ib molecules define rules for binding of self and nonself peptides.

Studies of naturally processed peptides eluted from membrane-bound and soluble isoforms of murine class Ib Qa-2 molecules determined several features of these ligands, such as the conserved nonameric length and the preferred usage of specific residues at four to six of nine peptide positions. The structural information derived from these studies proved insufficient to distinguish between two interpretations: 1) that Qa-2 are peptide receptors of higher stringency than ordinary class I molecules, and 2) that Qa-2 molecules, like classical class I Ags, bind diverse arrays of peptides. We have addressed this issue by a systematic analysis of peptide residues involved in the binding of membrane-bound Qa-2 molecule, MQ9b. The optimal binding of synthetic peptides in vitro occurs at neutral pH. Two dominant anchors are required for peptide binding to MQ9b: His at position 7 and a hydrophobic residue, Leu, Ile, or Phe, at position 9. In addition, one or two auxiliary anchors participate in binding. The identity and the position of the auxiliary anchors differ from peptide to peptide, suggesting that the binding motifs defined from pool sequencing are composed of many superimposed alternative motifs present in individual peptides. The number of anchors used by Qa-2 peptides is similar to that found in ligands of classical class I Ags. Consequently, the Qa-2 are predicted to bind large repertoires of self and nonself peptides. In support of this interpretation we demonstrate that MQ9b binds strongly 5 of 17 motif-positive, pathogen-derived synthetic peptides.

Animals↗

PubMed1996

A national survey of physicians' behaviors regarding sexual contact with patients.

To determine the prevalence of sexual contact between physicians and patients, we mailed a survey to a nationwide, randomized sample of 1,600 physicians, including internists, family medicine physicians, obstetrician-gynecologists, and ophthalmologists. The response rate was 52% (n = 787). Of all respondents, 4.5% reported having dated a patient and 3.4% reported having had sexual (genital-genital, oral-genital, or anal-genital) contact with a patient. Physicians older than 50 years and unmarried physicians were significantly more likely to have dated patients. No differences in dating or sexual contact according to specialty or gender were found. Physicians who reported having had sexual contact with a patient were less likely to report negative consequences of the contact than physicians who had personal knowledge of sexual contact by other physicians. These results have implications for educational interventions for physicians.

Adult↗

PubMed1995

Peptide mimetics of thyrotropin-releasing hormone based on a cyclohexane framework: design, synthesis, and cognition-enhancing properties.

The design and synthesis of peptide mimetics of thyrotropin-releasing hormone (TRH) in which the peptide backbone is entirely replaced by a cyclohexane framework are described. The cis-1,3,5-trisubstituted ring was expected to permit key pharmacophoric groups to adopt conformations consistent with proposed bioactive conformations of the peptide. Compounds were synthesized by a stereoselective synthesis starting from L-glutamic acid. In a behavioral model of cognition in which TRH is active, the mimetics are potent, active compounds, exhibiting oral activity. One analog (26, (1S,3R,5(2S),5S)-5-[[5-oxo-1-(phenylmethyl)-2-pyrrolidinyl]-methyl]-5- [(1H-imidazol-5-yl)methyl]cyclohexaneacetamide) was radiolabeled for binding studies and evaluated in other binding assays and pharmacological tests. Competition binding of 26 vs [3H]MeTRH to rat brain slices suggests a two-site model for ligand binding with IC50's of 1 microM and 3 mM. Direct binding of [3H]-26 shows a biphasic curve with IC50's of 80 and 49 microM, respectively. Further studies would be needed to establish a link between the novel binding site(s) and the behavioral activity of 26 and TRH analogs.

Amino Acid Sequence↗

PubMed1994

National survey on physicians' attitudes toward social and sexual contact with patients.

To determine the attitudes of physicians toward social and sexual contact with patients, we mailed a self-report survey to a nationwide randomized sample including general practitioners, internists, obstetrician-gynecologists, and ophthalmologists. The 777 physicians who responded specified whether or not behavior such as hugging, dating, and sexual contact with their own patients may be appropriate. Less than 1% of all respondents thought that sexual contact with patients was appropriate during patient consultations. Three percent of internists and obstetrician-gynecologists considered sexual contact with patients appropriate when concurrent with treatment but outside of patient consultation, as compared with 9% of general practitioners and 12% of ophthalmologists (X2 = 17.8, df = 3, P < .001). Nearly 50% of general practitioners and more than 50% of all other physicians thought that sexual contact might be appropriate after termination of treatment of a patient. These findings may facilitate professional discussion on standards for social and sexual contact with patients.

Adult↗

PubMed1992

Electrophoresis underestimates the concentration of polyclonal immunoglobulins in serum.

The concentration of gamma-migrating immunoglobulins in blood serum was measured in 200 healthy blood donors by two methods, nephelometry and electrophoresis. Nephelometric values were calculated as IgG + IgM + 1/2 IgA because immunoglobulin G (IgG) and immunoglobulin M (IgM) migrate entirely within the gamma region and immunoglobulin A (IgA) is split between the gamma and beta regions. Electrophoretic values were calculated as % gamma x total protein. Gels were scanned with two different densitometers, providing two sets of electrophoretic data. In each case, the correlation between nephelometry and electrophoresis was very good (r = 0.94 and r = 0.96). However, electrophoresis consistently gave lower results than nephelometry (mean = 2.3 g/L and 4.8 g/L lower, respectively). The disparity between these methods was greater as the concentration of immunoglobulins increased. It is concluded that (1) electrophoresis gives a relative but not absolute value of immunoglobulin concentration in serum; (2) nephelometric and electrophoretic values cannot be used interchangeably; and (3) reference ranges for electrophoresis must take into account the densitometer used.

Adolescent↗

PubMed1992

Structure activity of C-terminal modified analogs of Ac-CCK-7.

Previous work indicates that both the C-terminal phenylalanine amide and the tryptophan moieties of cholecystokinin (CCK) are critical pharmacophores for interaction with either the A or B receptor subtypes. We have examined a series of analogs of Ac-CCK-7 [Ac-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe33-NH2] (2) in which the phenyl ring of the C-terminal Phe-NH2 has been modified. Compounds were assessed in binding assays using homogenated rat pancreatic membranes and bovine striatum as the source of CCK-A and CCK-B receptors respectively and for anorectic activity after intraperitoneal administration to rats. Substitution of a number of cycloalkyl or bicyclic aryl moieties for the phenyl ring of phenylalanine33 including cyclopentyl (20), cyclohexyl (21), cyclooctyl (23), 2-(5,6,7,8-tetrahydro)naphthyl (26), 2-naphthyl (27), and 1-naphthyl (29) led to analogs with 10-70 times the anorectic potency of 2. The anorectic activity of 21 was blocked by the specific CCK-A receptor antagonist MK-329. Other bulky aliphatic groups in place of the phenylalanine33 aromatic ring such as isopropyl, 2-adamantyl and cyclohexylmethyl gave derivatives similar to 2 in potency. While most of the new compounds were comparable to CCK in binding assays, 23, 26, 27 and 29 were exceptionally potent with IC50s 10(-11)-10(-14) M in the pancreas. Compounds 23 and 29 were further evaluated for their ability to stimulate amylase secretion and found to have potencies similar to that of CCK. The dissociation between potency in the binding and amylase secretion assays suggests that they may interact with a high affinity binding site which is not coupled to amylase secretion. We conclude that CCK receptors possess a generous hydrophobic pocket capable of accommodating large alkyl groups in place of the side chain of phenylalanine33 and that the pharmacological profile of CCK analogs can be tailored by appropriate exploitation of this finding.

Amino Acid Sequence↗

PubMed1985

Respiratory dyskinesia: review and case reports.

Respiratory dyskinesia, the respiratory manifestations of tardive dyskinesia, has been recognized recently by several investigators. The literature is reviewed, two new cases are described, and possible directions for future research are discussed. It was concluded that respiratory dyskinesia is infrequently recognized clinically; more importantly, it may be easily mistaken for other medical disorders.

Adult↗

PubMed1983

Sensitivity to values of the rate constants in a neurochemical metabolic model.

Equations were derived for the instantaneous relative sensitivities of reaction rates (controllability indices) and metabolite concentrations (response indices) to perturbations in the values of rate constants and were used to analyze the behavior of a model of in vivo glutamate metabolism in rat brain. Controllabilities of reversible reactions were found to increase as the values of the corresponding rate constants (i.e., the rate of approach to equilibrium) increased. Response indices generally declined with the metabolic distance between the metabolite and the rate constant, but they were unexpectedly high for reversible reactions with high controllabilities. The transient response of a given metabolite is most sensitive to reactions involving metabolites which are changing most rapidly relative to their respective pool sizes. Rapidly reversible reactions are most important for communication between metabolite pools.

Animals↗

PubMed1982