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Biomedical subjects

S Siegel

Publications and source records attributed to S Siegel.

At least 19 recordsLinked to original sources
PubMed1995

Morphine-induced taste avoidance is attenuated with multiple conditioning trials.

Morphine has paradoxical effects in learning experiments. The drug can serve as a reinforcer in several situations; yet rats avoid tastes paired with morphine, much as they avoid tastes paired with an emetic drug such as lithium chloride (LiCl). The results of the present experiment indicate that, in contrast with LiCl-induced taste avoidance, the strength of morphine-induced avoidance is nonmonotonically related to the duration of training. Although taste avoidances produced by both drugs are readily established, the morphine-induced avoidance (unlike the LiCl-induced avoidance) weakens with continued flavor-drug pairings. These results, together with prior findings, suggest that there are distinctive features of morphine-induced taste avoidance.

Animals↗
PubMed1995

Tolerance to naloxone-induced suppression of intake: learning and cross-tolerance to cholecystokinin in rats.

Experiments were conducted to evaluate the contribution of conditioning to tolerance to the meal-suppressive effect of naloxone (Nx) in rats. The results indicated (a) Nx suppresses consumption in a dose-dependent manner; (b) tolerance to this suppression of intake is "contingent" (the rat must eat in conjunction with drug administration for tolerance to develop); (c) tolerance is displayed only in the context of environmental cues previously associated with Nx; (d) Nx-tolerant rats overeat when presented with cues previously associated with the drug; (e) Nx-tolerant rats display cross-tolerance to cholecystokinin. The results are consistent with C.X. Poulos and H. Cappell's (1991) "homeostatic" theory of tolerance, as well as with the results of other experiments indicating that conditioning contributes to tolerance to many effects of various drugs.

Animals↗
PubMed1995

An associative interpretation of the indirect McCollough effect.

Following an induction procedure in which a coloured grid is alternated with a square of a complementary colour, subjects report colour after-effects on both the grid orientation present during induction and the orthogonal non-induced grid orientation. The after-effect reported on the induced grid orientation is called the McCollough effect (ME). The after-effect reported on the non-induced grid orientation is called the indirect ME. There is evidence that the ME represents an instance of Pavlovian conditioning. The present results support a conditioning interpretation of the indirect ME and are inconsistent with interpretations of the indirect ME that attribute the phenomenon to special orthogonal coding mechanisms within the visual system.

Adult↗
PubMed1995

[Hereditary chronic pancreatitis. Report of a case].

Childhood hereditary pancreatitis is a rare entity of uncertain etiology, characterized by recurrent episodes of acute pancreatitis, abdominal pain and other unspecific symptoms. Among several therapeutic alternatives, pancreatojejunostomy is presently the treatment of choice. We report a 17 years old male with chronic hereditary pancreatitis that was treated with pancreatojejunostomy drainage.

Adolescent↗
PubMed1995

Learning and tolerance to the intake suppressive effect of cholecystokinin in rats.

Experiments were conducted to evaluate the contribution of conditioning to tolerance to the meal suppressive effect of cholecystokinin (CCK). The results indicate that (a) tolerance was contingent (the rat had to eat in conjunction with drug administration for tolerance to the meal suppressive effect to develop), (b) tolerance was displayed only in the context of environmental cues previously associated with CCK, (c) CCK-tolerant rats overate when presented with cues previously associated with the peptide, and (d) CCK tolerance displayed latent inhibition. The results are consistent with C.X. Poulos and H. Cappell's (1991) homeostatic theory of tolerance, as well as with the results of other experiments indicating that conditioning contributes to tolerance to many effects of a variety of drugs.

Animals↗
PubMed1994

Scanning and form-contingent color aftereffects.

G. K. Humphrey, A. M. Herbert, L. A. Symons, and S. Kara (1994) and J. Broerse and P. Grimbeek (1994) suggested that the form-contingent color aftereffect reported by S. Siegel, L. G. Allan, and T. Eissenberg (1992) would not be obtained if Ss were instructed to scan the induction and assessment forms. The authors present data from Ss who were instructed to scan the forms. These scanning Ss displayed aftereffects that were no different from those described earlier by Siegel et al. Scanning Ss do display spatiotopic contingent color aftereffects.

Color Perception↗
PubMed1994

Subcutaneous sumatriptan in a clinical setting: the first 100 consecutive patients with acute migraine in a tertiary care center.

The first 100 consecutive patients at our center receiving subcutaneous sumatriptan (6 mg) were evaluated over a total of 455 migraine attacks. Parameters included overall efficacy, average time to relief, recurrence rate, average time to recurrence, adverse events, comparison to previous abortive agents, and subjective global ratings. Overall efficacy (defined as headache severity reduction from severe or moderate to mild or none) was 84%. Average time to relief was 40 minutes. Nine percent failed to respond at all. Recurrence rate was 46.5% with 36% of patients having no recurrence. Fourteen percent of patients reported 100% recurrence (minimum 3 attacks; average 5.4 attacks). Time to recurrence varied widely, but averaged 9.1 hours. Eighty-one percent rated the drug better or much better than previous abortive medications in terms of sumatriptan's ability to abort the attack. Seventy-seven percent reported some adverse event (generally mild and transient) with 23% reporting no adverse events. Sixty-nine percent reported a global rating of Good to Excellent and 31% rated Poor or Fair. The rate of recurrence and average time to recurrence were the most significant factors affecting the global ratings. These parameters were further evaluated with respect to a variety of subgroups: 1) migraine alone 2) migraine with co-existent tension-type headache 3) drug-induced headache (analgesic rebound headache) 4) posttraumatic headache 5) preventive versus no preventive medication 6) presence or absence of adverse events 7) presence or absence of recurrence and 8) average duration of migraine with no medication.

Acute Disease↗
PubMed1994

Intraoperative beta probe: a device for detecting tissue labeled with positron or electron emitting isotopes during surgery.

An intraoperative beta probe was designed, built, and tested for detection of radio-labeled malignant tissues that has the advantage of being selectively sensitive to beta while insensitive to gamma radiation. Since beta radiation (electrons or positrons) has a short range in tissue, this probe is ideal for detecting tracers in tumors at the surface of the surgical field. This probe contains a plastic scintillation detector sensitive to beta rays and to a lesser degree some background gamma rays. A second detector counts spurious gamma rays and allows for their subtraction from the activity measured by the first detector. Sensitivity of the dual probe for I-131 and F-18 was measured to be 108 counts/s/kBq (4000 counts/s/microCi). The dual-detector probe faithfully measured the 10:1 "tumor" to background ratio of radioactivity concentrations in a simulated environment of a tumor in the presence of intense background 511 keV photons. In another phantom experiment, simulating abdominal tumor deposits with various realistic I-131 radioactive concentrations, the probe was able to accurately identify tumors of approximately 50 mg with a tumor/normal radioactivity concentration of 3/1 in 10 s.

Abdominal Neoplasms↗
PubMed1993

Establishment and characterization of a human mixed-lineage, T-lymphoid/myeloid cell line (USP-91).

We report the establishment of a novel cell line from a pediatric patient with recurrent non-Hodgkin's lymphoma. This cell line, termed USP-91, showed both T-lymphoid cell as well as myeloid (ie, nonlymphoid) cell characteristics using a comprehensive multiparameter approach. The initial growth of this cell line was dependent on the presence of the murine stromal cell line, 14F1.1. Subsequently, a phenotypically stable, stroma-independent cell line was established. Although the recurrent biopsy material and the derivative cell line, USP-91, were clonally-derived from T-lineage lymphoid cells, as evidenced by the same rearrangement of the T-cell receptor-beta locus, USP-91 coexpressed both the T-cell antigens CD7, CD3, and CD4, and the myeloid antigens CD13, CD33, CD11b, and CD34. The myeloid features of USP-91 were most consistent with monocytic differentiation as these cells expressed alpha-napthol acetate esterase, lysozyme, alpha-1-antitrypsin, alpha-1-antichymotrypsin, as well as the cell surface receptor for macrophage colony-stimulating factor. In addition, incubation in the presence of phorbol esters induced USP-91 to exhibit morphologic and functional properties of mature mononuclear phagocytes. The expression of this bilineage phenotype suggests that USP-91 represents the malignant transformation of a progenitor cell capable of either myelomonocytic or T-lymphoid differentiation.

Animals↗
PubMed1993

Construction and initial characterization of a mouse-human chimeric anti-TNF antibody.

Tumor necrosis factor-alpha (TNF) has been implicated in the pathogenesis of a variety of human diseases including septic shock, cachexia, graft-versus-host disease and several autoimmune diseases. Monoclonal antibodies directed against TNF provide an attractive mode of therapeutic intervention in these diseases. We have generated a murine monoclonal antibody (A2) with high affinity and specificity for recombinant and natural human TNF. To increase its therapeutic usefulness, we used genetic engineering techniques to replace the murine constant regions with human counterparts while retaining the murine antigen binding regions. The resulting mouse-human chimeric antibody should have reduced immunogenicity and improved pharmacokinetics in humans. Molecular analysis of light chain genomic clones derived from the murine hybridoma suggests that two different alleles of the same variable region gene have rearranged independently and coexist in the same hybridoma cell. The chimeric A2 antibody (cA2) exhibits better binding and neutralizing characteristics than the murine A2 which was shown to contain a mixture of two kappa light chains. The properties of cA2 suggest that it will have advantages over existing murine anti-TNF antibodies for clinical use.

Animals↗
PubMed1993

McCollough effects as conditioned responses: reply to Dodwell and Humphrey.

P. C. Dodwell and G. K. Humphrey (1990) criticized the Pavlovian conditioning analysis of the McCollough effect, claiming that it was conceptually flawed and that it did not assign the McCollough effect any useful function. In this article, it is suggested that the error-correction interpretation that Dodwell and Humphrey proposed as an ostensible alternative to the conditioning interpretation can be subsumed by the conditioning interpretation. Furthermore, the conditioning interpretation does ascribe a useful function to the McCollough effect.

Attention↗
PubMed1993

Long-term follow-up of patients treated with COMP or LSA2L2 therapy for childhood non-Hodgkin's lymphoma: a report of CCG-551 from the Childrens Cancer Group.

PURPOSE: We analyzed the long-term results of a Childrens Cancer Group (CCG) randomized study comparing cyclophosphamide, vincristine, methotrexate, and prednisone (COMP) versus LSA2L2 as treatment for childhood non-Hodgkin's lymphoma. The initial results were previously reported (N Engl J Med 308:559, 1983). PATIENTS AND METHODS: A total of 429 patients are reported here, 68 with localized disease and 361 with disseminated disease. The distribution of disseminated-disease patients by histologic type was 164 lymphoblastic, 60 large-cell, and 137 undifferentiated lymphomas. Median follow-up duration of surviving patients is 8 years. RESULTS: Event-free survival (EFS) of patients with localized disease was 84% at 5 years. No differences were seen between the two treatment regimens. Results for patients with disseminated disease was dependent on histologic subtype: patients with lymphoblastic lymphoma did better when treated with LSA2L2 (5-year EFS of 64% v 35% for COMP); COMP produced better results for patients with undifferentiated lymphoma (5-year EFS of 50% v 29% for LSA2L2). Results for large-cell lymphoma patients were similar (5-year EFS of 52% for COMP v 43% for LSA2L2). Five percent of patients died of treatment-related complications while on therapy (primarily infections). Only four deaths without progression have been observed off-therapy (two from restrictive lung disease, one from an acute asthma attack, one from colon cancer). Patient survival rates after recurrence were poor. CONCLUSION: Treatment success can be expected in 84% of pediatric patients with localized non-Hodgkin's lymphoma. For patients with disseminated disease, treatment success can be expected in 64% of those with lymphoblastic and 50% of those with undifferentiated or large-cell disease. To date, late adverse events are rare.

Adolescent↗