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Biomedical subjects

C Stein

Publications and source records attributed to C Stein.

At least 73 records · Page 4Linked to original sources
PubMed1997

Immune cell-derived beta-endorphin. Production, release, and control of inflammatory pain in rats.

Localized inflammation of a rat's hindpaw elicits an accumulation of beta-endorphin-(END) containing immune cells. We investigated the production, release, and antinociceptive effects of lymphocyte-derived END in relation to cell trafficking. In normal animals, END and proopiomelanocortin mRNA were less abundant in circulating lymphocytes than in those residing in lymph nodes (LN), suggesting that a finite cell population produces END and homes to LN. Inflammation increased proopiomelanocortin mRNA in cells from noninflamed and inflamed LN. However, END content was increased only in inflamed paw tissue and noninflamed LN-immune cells. Accordingly, corticotropin-releasing factor and IL-1beta released significantly more END from noninflamed than from inflamed LN-immune cells. This secretion was receptor specific, calcium dependent, and mimicked by potassium, consistent with vesicular release. Finally, both agents, injected into the inflamed paw, induced analgesia which was blocked by the co-administration of antiserum against END. Together, these findings suggest that END-producing lymphocytes home to inflamed tissue where they secrete END to reduce pain. Afterwards they migrate to the regional LN, depleted of the peptide. Consistent with this notion, immunofluorescence studies of cell suspensions revealed that END is contained predominantly within memory-type T cells. Thus, the immune system is important for the control of inflammatory pain. This has implications for the understanding of pain in immunosuppressed conditions like cancer or AIDS.

Analysis of Variance↗
PubMed1997

Corticotropin-releasing factor in antinociception and inflammation.

Corticotropin-releasing factor (CRF) plays a major role at the level of the hypothalamus and pituitary to control the body's response mechanisms to stressful stimuli. The recent discovery of CRF outside the central nervous system suggests that CRF may well play a similar role in peripheral tissues, most likely in a paracrine manner. While its effects in many other peripheral tissues is not known yet, CRF and its receptors are upregulated in inflammatory pain states pointing to a key role under these circumstances. Indeed, locally expressed CRF seems to act on CRF receptors on immune cells which have migrated into the area of the inflamed tissue, and induce the release of opioid peptides synthesized within these immune cells. These opioids subsequently act on peripheral opioid receptors located on peripheral sensory nerves to inhibit the transmission of painful stimuli. CRF may also affect the inflammatory response; however, these data are still controversial. The peripheral paracrine effects of CRF may be similar to those of hypothalamic CRF, i.e., to counterbalance local stressful events, such as inflammation and pain, so that they do not threaten the homeostasis of the body. Interestingly, CRF-like peptides have been identified not only in mammalians, but also in species such as the frog (Stenzel-Poore et al., 1992, Mol. Endocrinol. 6, 1716) and the teleost fish (Okawara et al., 1988, Proc. Natl. Acad. Sci. USA 85, 8439) indicating that this is a peptide that has been conserved over a long period (200 million years) across species (Lederis et al., 1990, Prog. Clin. Biol. Res. 342, 467) and that the release of ACTH-like peptides by peptides of the CRF family may represent an ancestral type of stress response (Ottaviani et al., 1992, Gen. Comp. Endocrinol. 87, 354; Tran et al., 1990, Gen. Comp. Endocrinol. 78, 351).

Analgesia↗
PubMed1997

Both Epstein-Barr viral nuclear antigen 2 (EBNA2) and activated Notch1 transactivate genes by interacting with the cellular protein RBP-J kappa.

The Epstein-Barr viral nuclear antigen 2 (EBNA2) plays a key role during establishment and maintenance of B cell immortalization after Epstein-Barr virus (EBV) infection. EBNA2 acts as a transactivator of cellular and viral genes. We studied two EBNA2 regulated viral promoters (TP1 promoter and LMP/TP2 promoter) in detail to learn more about the molecular mechanisms of EBNA2-mediated transactivation. In both promoters we could identify at least one binding site for the cellular repressor protein RBP-J kappa. EBNA2 is tethered to the EBNA2 responsive promoter elements by interaction with this cellular protein. Although necessary, the binding of RBP-J kappa is not sufficient for EBNA2-mediated transactivation. At least two further cellular proteins, which are different in the studied promoters are important for efficient transactivation. The identification of RBP-J kappa as central mediator of EBNA2 transactivation suggested an interference of EBNA2 with the highly conserved Notch receptor signal transduction pathway. We could show that an activated form of the Notch receptor can transactivate a reporter construct containing a hexamer of the two RBP-J kappa binding sites of the TP1 promoter supporting the idea that EBNA2 acts as a functional equivalent of an activated Notch receptor.

DNA-Binding Proteins↗
PubMed1997

Antinociceptive effects of dynorphin peptides in a model of inflammatory pain.

Dynorphin A (DYN) peptides, administered into the central nervous system, have produced inconsistent analgesic actions in tests using thermal stimuli. This study examined antinociceptive effects of intravenous and intraplantar DYN-(2-17) against noxious pressure in rats with Freund's adjuvant-induced unilateral hindpaw inflammation. The effects of DYN-(2-17) were compared to those of the opioid agonists morphine. (D-Ala2,N-Methyl-Phe4,Gly-ol5)-enkephalin (DAMGO) and DYN-(1-17). Intravenous DYN-(2-17) (0.188-10 mg/kg) produced dose-dependent elevations of paw pressure thresholds in inflamed and in non-inflamed paws. These effects were similar in magnitude to those of subcutaneous morphine (2 mg/kg), at doses of 0.375-1.5 mg/kg they were significantly greater on the inflamed (right) than on the non-inflamed (left) paw, and they were not reversible by intravenous naloxone (1-10 mg/kg). Intraplantar Dyn-(2-17)(0.001-0.3 mg) was ineffective, whereas both intraplantar DYN-(1-17)(0.15-0.3 mg) and DAMGO (0.008-0.016 mg) produced dose-dependent and naloxone-reversible elevations of paw pressure thresholds. The intraplantar injection of both Dyn peptides produced a transient increase in the volume of non-inflamed paws. These findings suggest that intravenous DYN-(2-17) produces possibly centrally mediated, non-opioid antinociceptive effects against noxious pressure. At certain doses these effects are more potent in inflamed than in non-inflamed paws. In contrast to the opioid peptides DYN-(1-17) and DAMGO, DYN-(2-17) does not appear to have no peripheral antinociceptive actions.

Analgesics↗
PubMed1997

Fetal growth and insulin resistance in adult life: role of skeletal muscle morphology.

1. Thinness at birth is associated with insulin resistance in adult life and an apparent delay in activation of glycolysis/glycogenolysis in exercising skeletal muscle. As developmental abnormalities of skeletal muscle histology or metabolism may explain this association we examined muscle histology, biochemistry and blood flow in a group of 27 adult women whose birth details were known. 2. Subjects were examined by near-infrared spectroscopy to determine forearm muscle oxygen supply, and by muscle biopsy and forearm plethysmography. Those with a ponderal index at birth < 23 kg/m3 were insulin resistant (assessed by the short insulin-tolerance test-mean rate constants for glucose disappearance = 4.14 compared with 4.83%/min, P = 0.045) and had significantly more rapid muscle reoxygenation than the remainder of the subjects (13 compared with 22 s, P = 0.004). 3. Thinness at birth did not influence muscle capillary density, muscle glycogen content, glycogen synthase activity, citrate synthase activity or resting forearm blood flow. 4. Insulin resistance seen after fetal malnutrition was not associated with abnormal muscle histology, resting muscle blood flow, mitochondrial volume or glycogen content. 5. The increase in muscle reoxygenation rate in adult subjects who were thin at birth could occur to promote oxidative ATP synthesis in compensation for the delay in activation of glycolysis/glycogenolysis. It suggests altered regulation rather than structure of the muscle microcirculation. These changes appear to antedate the structural and biochemical changes seen in muscle from patients with established diabetes.

Embryonic and Fetal Development↗
PubMed1996

Local upregulation of corticotropin-releasing hormone and interleukin-1 receptors in rats with painful hindlimb inflammation.

Opioid peptides derived from immune cells produce analgesia by activating opioid receptors on peripheral sensory nerves in inflammation. Corticotropin-releasing hormone (CRH) and interleukin-1 beta (IL-1 beta) can release these opioids. Here we show that both corticotropin-releasing hormone and interleukin-1 beta elicit receptor-specific antinociception in inflamed paws of rats by an opioid-mediated mechanism. Autoradiographic studies demonstrate 125I-CRH and 125I-IL-1 beta binding sites on immune cells in lymph nodes and inflamed paws. This binding is of high affinity and displaceable by the respective unlabeled agonist and antagonist ligands but not by opioid or adrenergic compounds. 125I-CRH and 125I-IL-1 beta binding sites are absent on nerves and in non-inflamed subcutaneous tissue but their number is greatly enhanced in inflamed paws and lymph nodes. This upregulation of binding sites for the opioid-releasing agents corticotropin-releasing hormone and interleukin-1 beta likely represents part of the body's local response to combat inflammatory pain.

Animals↗
PubMed1996

No tolerance to peripheral morphine analgesia in presence of opioid expression in inflamed synovia.

Pain treatment with centrally acting opiates is limited by tolerance. Tolerance is a decreasing effect of a drug with prolonged administration of that drug or of a related (e.g., endogenous) compound acting at the same receptor. This is often associated with a downregulation of receptors. In peripheral inflamed tissue, both locally expressed opioid peptides and morphine can produce powerful analgesia mediated by similar populations of opioid receptors. We hypothesized that the chronic presence of endogenous opioids in inflamed joints might convey downregulation of peripheral opioid receptors and tolerance to the analgesic effects of intraarticular morphine. We assessed these effects after arthroscopic surgery in patients with and without histologically verified synovial cellular infiltration, and we examined synovial opioid peptides and opioid receptors by immunocytochemistry and autoradiography, respectively. We found that, despite an abundance of opioid-containing cells in pronounced synovitis, morphine is at least as effective as in patients without such cellular infiltrations, and there is no major downregulation of peripheral opioid receptors. Thus, opioids expressed in inflamed tissue do not produce tolerance to peripheral morphine analgesia. Tolerance may be less pronounced for peripherally than for centrally acting opioids, which provides a promising perspective for the treatment of chronic pain in arthritis and other inflammatory conditions.

Adolescent↗
PubMed1996

Expression of corticotropin-releasing factor in inflamed tissue is required for intrinsic peripheral opioid analgesia.

Immune cell-derived opioid peptides can activate opioid receptors on peripheral sensory nerves to inhibit inflammatory pain. The intrinsic mechanisms triggering this neuroimmune interaction are unknown. This study investigates the involvement of endogenous corticotropin-releasing factor (CRF) and interleukin-1beta (IL-1). A specific stress paradigm, cold water swim (CWS), produces potent opioid receptor-specific antinociception in inflamed paws of rats. This effect is dose-dependently attenuated by intraplantar but not by intravenous alpha-helical CRF. IL-1 receptor antagonist is ineffective. Similarly, local injection of antiserum against CRF, but not to IL-1, dose-dependently reverses this effect. Intravenous anti-CRF is only inhibitory at 10(4)-fold higher concentrations and intravenous CRF does not produce analgesia. Pretreatment of inflamed paws with an 18-mer 3'-3'-end inverted CRF-antisense oligodeoxynucleotide abolishes CWS-induced antinociception. The same treatment significantly reduces the amount of CRF extracted from inflamed paws and the number of CRF-immunostained cells without affecting gross inflammatory signs. A mismatch oligodeoxynucleotide alters neither the CWS effect nor CRF immunoreactivity. These findings identify locally expressed CRF as the predominant agent to trigger opioid release within inflamed tissue. Endogenous IL-1, circulating CRF or antiinflammatory effects, are not involved. Thus, an intact immune system plays an essential role in pain control, which is important for the understanding of pain in immunosuppressed patients with cancer or AIDS.

Analgesics, Opioid↗
PubMed1996

Fetal growth and insulin resistance in adult life: relationship between glycogen synthase activity in adult skeletal muscle and birthweight.

Growth retardation during fetal life is associated with insulin insensitivity and an increased prevalence of impaired glucose tolerance in adult life. Because insulin-mediated stimulation of glycogen synthase may be an important rate-limiting step for insulin action at the cellular level, we have sought to determine whether impaired activation of muscle glycogen synthase is linked with early growth retardation. Postprandial glycogen synthase activity was therefore measured in muscle biopsies from a group of 27 women with normal glucose tolerance aged around 50 who were born in Preston, Lancashire, whose birthweight and body size at birth were recorded. Glycogen synthase activity measured at 0.1 mmol 1(-1) glucose-6-phosphate correlated with insulin sensitivity as measured by a short insulin tolerance test (r = 0.42, p < 0.05) and the waist to hip ratio (r = -0.48, p < 0.01), but not body mass index, body fat percentage or age. Within the group of women with normal glucose tolerance there was no relationship between intra-uterine growth as evidenced by birthweight or body size at birth and the response to insulin of skeletal muscle glycogen synthase in adult life. Thus we found no evidence for a direct link between fetal growth and insulin sensitivity in this pathway.

Biopsy↗
PubMed1996

A prospective outcome study of patients with clot in an ulcer and the effect of irrigation.

BACKGROUND: The proper management of patients with clots in an ulcer base has not been clearly defined by prospective studies. Variable prevalence and rebleeding rates may be explained by differing degrees of vigor used to clear the clot, as removal may reveal other stigmata. We prospectively assessed the natural histories of patients with clots after vigorous irrigation, employing a management strategy of endoscopic therapy for patients with high-risk stigmata and observation of those with clots resistant to washing or low-risk findings. METHODS: Forty-six patients with upper gastrointestinal bleeding found to have a clot in an ulcer had irrigation with a 3.2 mm bipolar probe for up to 5 minutes. Stigmata after washing were recorded; endoscopic therapy was given for active bleeding that persisted > or = 5 min or for nonbleeding visible vessels. Patients were observed in the hospital for > or = 3 days. RESULTS: Findings revealed after irrigation were adherent clot, 26 (57%); clean base, 1 (2%); flat spot, 5 (11%); nonbleeding visible vessel, 7 (13%); oozing, 6 (13%); and spurting, 1 (2%). Two of the 26 (8%) with adherent clots after washing rebled; endoscopic therapy resulted in no further bleeding. One of the 14 (7%) with active bleeding or visible vessels treated with hemostatic therapy rebled; repeat endoscopic therapy resulted in no further bleeding. No deaths occurred. CONCLUSIONS: Irrigation appears to be useful in patients with upper gastrointestinal bleeding who have ulcers with clots. The endoscopic findings present after washing can be used to dictate the appropriate management at initial endoscopy. Application of hemostatic therapy in patients with active bleeding or nonbleeding visible vessels and observation of patients with other stigmata, including clots resistant to washing, resulted in an excellent outcome.

Blood Coagulation↗
PubMed1996

The influence of size or number of biopsies on rapid urease test results: a prospective evaluation.

BACKGROUND: The optimal number or size of endoscopic biopsies for use in rapid urease testing has not been established. Postulating that increasing the amount of tissue sampled would improve diagnostic yield and hasten development of a positive test, we compared urease testing with one regular biopsy, two regular biopsies, and one "jumbo" forceps biopsy. METHODS: One hundred fifty patients undergoing endoscopy had three sets of prepyloric biopsies placed in a CLOtest: one regular forceps biopsy, two regular forceps biopsy, and one large-channel jumbo forceps biopsy. Biopsies were then taken for two independent histologic examinations. Disagreements were resolved by another examiner. RESULTS: Eighty-nine patients (59%) had Helicobacter pylori infection by histology; interobserver agreement was 90% with kappa = 0.78. The mean time to a positive test was 5.3 +/- 0.9 hours for one regular biopsy, 3.2 +/- 0.7 hours for two regular biopsies, and 3.8 +/- 0.8 hours for one jumbo biopsy (p < 0.01 for two regular, one jumbo vs. one regular biopsy). Compared to one regular biopsy, the urease test was positive at least 30 minutes earlier in 56% of the patients with two regular biopsies and 54% with one jumbo biopsy. Sensitivities for one regular versus two regular biopsies were 1 hour, 19% versus 33% (p = 0.059); 2 hours, 38% versus 49% (p = 0.17); 3 hours, 48% versus 60% (p = 0.18); and 24 hours, 75% versus 79% (p > 0.20). CONCLUSIONS: Doubling the amount of tissue in the CLOtest hastens the development of a positive test by approximately 1 1/2 to 2 hours; tests become positive at least 30 minutes earlier in over 50% of the patients. Low cost, ease, and excellent specificity make the rapid urease test a valuable diagnostic tool. Nevertheless, if used as a "rapid" diagnostic test (read within 3 hours of biopsy), it is associated with a false negative rate of approximately 40%.

Adult↗
PubMed1996

Randomized comparison of ligation versus ligation plus sclerotherapy in patients with bleeding esophageal varices.

BACKGROUND & AIMS: Combining endoscopic sclerotherapy with ligation has been proposed to hasten variceal eradication. A randomized trial was performed comparing combination ligation plus sclerotherapy with ligation alone in patients with major bleeding from esophageal varices. METHODS: Forty-one patients were randomly assigned to receive ligation or ligation plus 1 mL 1.5% tetradecyl injected just above each band. Treatment was repeated weekly until varices were eradicated. Repeat endoscopy was performed for rebleeding and every 3 months after eradication. RESULTS: No significant differences were found between combined therapy and ligation in rebleeding (29% vs. 30%), blood transfused (3.1 +/- 1.1 vs. 2.0 +/- 0.8 U), hospital days (9.3 +/- 2.1 vs. 7.5 +/- 1.2), complications (29% vs. 10%), or deaths (14% vs. 15%) during a mean follow-up period of 28 weeks. Combined therapy required significantly more sessions to achieve eradication (4.9 +/- 0.6 vs. 2.7 +/- 0.4) and greater time per treatment session (18.3 +/- 1.7 vs. 13.3 +/- 0.5 minutes). CONCLUSIONS: Combined ligation plus sclerotherapy does not reduce the number of treatment sessions required for variceal eradication as compared with ligation alone. Combined therapy lengthens the time required for treatment without improving efficacy or decreasing complications. Thus, combined ligation and sclerotherapy should not be used to treat patients with bleeding esophageal varices.

Adult↗
PubMed1996

Prospective evaluation of the macrolide antibiotic dirithromycin for the treatment of Helicobacter pylori.

BACKGROUND: Macrolide antibiotics are active in vitro and in vivo against Helicobacter pylori. We assessed a newer macrolide, dirithromycin, for the treatment of H. pylori in two separate studies. METHODS: Volunteers with H. pylori infection (by 13C-urea breath test) were randomly assigned to 2-week treatment regimens. Study 1: dirithromycin 500 mg q.d.s., dirithromycin 500 mg q.d.s. plus omeprazole 40 mg q.d.s., or dirithromycin 500 mg q.d.s. plus metronidazole 500 mg t.d.s. Study 2: dirithromycin 500 mg q.d.s. plus omeprazole 20 mg b.d., dirithromycin 1000 mg q.d.s. plus omeprazole 20 mg b.d., or amoxycillin 500 mg q.d.s. plus omepirazole 20 mg b.d. Four weeks after the completion of therapy a repeat 13C-urea breath test was done to assess for cure. RESULTS: No patient taking dirithromycin alone (n = 6) or in combination with omeprazole (n = 26) achieved cure of their infection. Eradication of H. pylori was seen in one of seven patients taking dirithromycin plus metronidazole. Five of 10 patients taking omeprazole-amoxycillin dual therapy had their H. pylori infection cured (P = 0.0007 vs. patients taking dirithromycin plus omeprazole). Eleven (47%) of 32 patients taking dirithromycin alone or combined with omeprazole reported side-effects, but only two (6%) stopped therapy prematurely as a result of side-effects. CONCLUSION: No subject taking dirithromycin alone or in combination with omeprazole had their H. pylori infection cured. Dirithromycin, in the regimen used, shows little promise in the treatment of patients with H. pylori infection.

Adult↗