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Biomedical subjects

E Walker

Publications and source records attributed to E Walker.

At least 163 records · Page 9Linked to original sources
PubMed1987

Plasminogen activator in normal subjects after exercise and venous occlusion: t-PA circulates as complexes with C1-inhibitor and PAI-1.

Exercise to exhaustion was associated with the appearance in plasma of plasminogen activator (PA) in several mol wt forms, as identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with zymography. A number of active bands, all immunologically identified as tissue-type PA (t-PA), were observed. The major form had an apparent mol wt of approximately 60,000 and is due to free t-PA. The other strong bands had apparent mol wts of approximately 110,000 and 180,000. The 110,000 band, also present in pre-exercise samples, represents t-PA complexed with its major inhibitor (PAI-1), and the 180,000 band is due to t-PA complexed with C1 inhibitor. The released forms of t-PA were cleared rapidly after cessation of exercise at exhaustion. Urokinase-type PA (u-PA) activity was also identified in pre- and postexercise samples at an apparent mol wt of approximately 50,000. This is consistent with its being free u-PA; no complexed forms of u-PA were observed. Qualitatively similar changes in plasma PA were observed after venous occlusion. Small quantities of plasmin were generated after strenuous exercise, as observed by detection of plasmin-alpha 2-antiplasmin complex by two-dimensional immunoelectrophoresis in three of five subjects. This complex was cleared rapidly after cessation of exercise. Plasmin-alpha 2-antiplasmin complex was not detected in any of the subjects after venous occlusion.

Fibrinolysin↗
PubMed1986

Facial discrimination and emotional recognition in schizophrenia and affective disorders.

Current research demonstrates that patients with schizophrenia display deficits in a broad range of interpersonal skills. To investigate the ability of patients with schizophrenia and major depression and normal controls to process facial stimuli, four tasks were constructed from 21 photographs of faces representing standardized poses of fundamental emotions. Two tasks were designed to investigate facial identity matching independent of emotion expressed, and two tasks were designed to test emotion recognition and emotion labeling, respectively. Results indicate that while depressed patients differed from controls only on the emotion-labeling task, those with schizophrenia showed deficits on all four tasks when compared with controls and did worse than patients with depression on the emotion tasks. The findings suggest that patients with schizophrenia are impaired on a broader range of facial perception skills than those with depression, when compared with controls.

Adult↗
PubMed1986

Increased expression of the epidermal growth factor receptor on human colon carcinoma cells.

Epidermal growth factor (EGF) is a small polypeptide hormone that promotes the growth of cells in culture and elicits the differentiation of epithelial tissues in vivo. The effect of EGF is mediated by a transmembrane receptor that is expressed in increased amounts on some tumor cells. We have used a monoclonal antibody to the EGF receptor to detect increased expression of the receptor on human colon carcinoma cells. All eight of the moderately well-differentiated colon carcinoma cell lines tested and several frozen colon carcinoma tissue sections showed increased expression of the EGF receptor, while five poorly differentiated colon carcinoma cell lines and normal colon tissue sections did not. Increased expression of the EGF receptor on moderately well-differentiated colon carcinoma cells but not on poorly differentiated colon carcinoma cells was also demonstrated by western transfer and iodine 125-labeled EGF binding assays. Increased expression of the EGF receptor on moderately well-differentiated colon carcinoma cells seems to be a useful marker for the differentiation of human colon carcinoma cells. In addition, it might provide a site for adjuvant hormonal therapy or immunotherapy.

Antibodies, Monoclonal↗
PubMed1986

The toxicity of niridazole in rat embryos in vitro.

The antischistosomal drug niridazole (NDZ) was found to be teratogenic in a concentration-dependent manner from 10 to 50 micrograms/ml (47-233 microM) in rat embryos cultured from day 10 to day 11. A striking malformation consisting of axial asymmetry in which the right side of the embryo showed severe necrosis was the predominant malformation. The drug showed significantly greater dysmorphogenic activity at low (5%) compared to high (20%) oxygen tensions in cultures. Coincubation of embryos and NDZ with an exogenous source of metabolic enzymes and cofactors (NADPH) failed to modify teratogenicity. Inclusion of CO in the culture atmosphere significantly reduced the malformation incidence as did preincubation of the drug with S-9 and cofactors in medium with low O2 tension. Treatment of gravida with NDZ up to and including the maternal-lethal dose failed to result in observable malformations despite the use of several routes of exposure. These data lead us to hypothesize that rat embryos are capable of performing the reductive activation of NDZ in a fashion analogous to the schistosome but that reductive extraembryonic metabolism may result in teratogenic bioinactivation.

Animals↗
PubMed1986

Symptoms associated with suicidal behavior in childhood and adolescence.

In adulthood, depression is often accompanied by suicidal ideation or behavior. As a result, depression in adults is generally viewed as a sign of risk for suicide. However, according to a number of researchers, suicidal behavior in children and adolescents differs markedly from that in adulthood. Differences have been noted in frequency, gender distribution, and associated symptoms. This study examined age and gender differences in symptoms accompanying suicidal gestures and ideation in black children, aged 11-18, referred for psychiatric treatment. Results indicated that a difference exists in the types of symptoms associated with suicidal ideation as opposed to suicidal acts, and that these differences vary, depending on the age and gender of the child. Moreover, the findings indicate that depressed mood and other "internalized" symptoms are more common among disturbed children who manifest suicidal behavior than among those who do not.

Adolescent↗
PubMed1986

Attentional performance in positive- and negative-symptom schizophrenia.

Two tasks designed to measure selective attention were administered to schizophrenics, patients with bipolar disorder, and normal subjects. Schizophrenics were divided into three subgroups: positive-, negative-, and mixed-symptom patients. Positive-symptom schizophrenics showed significant deficits on a digit-span task when compared to normal subjects. Furthermore, the positive group was the only one to show a significant performance decrement in the distraction condition of the digit-span task. There were no significant group differences in performance on a dichotic listening test. The results of the present study are contrary to the hypothesis that selective attention deficits are characteristic of negative-symptom schizophrenia. Instead, the findings suggest that positive symptoms are associated with greater susceptibility to distraction.

Adult↗
PubMed1986

Positive and negative symptoms in schizophrenia: attentional performance correlates.

Attentional impairment has been hypothesized to be associated with negative symptoms in schizophrenia. The present study examined the relation between attentional performance and positive and negative symptoms in both schizophrenic and manic patients. The results showed that deficits on the distraction conditions of a digit-span task were greatest in positive-symptom schizophrenics. Regression analyses revealed that only certain positive symptoms were related to digit-span scores; specifically, ratings of positive-thought disorder were inversely associated with performance for both schizophrenics and manics. The findings are discussed in light of their implications for conceptualizing the symptom categories and their laboratory correlates.

Attention↗
PubMed1986

Symptom correlates of vulnerability to backward masking in schizophrenia.

The authors used the backward-masking procedure to investigate visual information processing in schizophrenic and bipolar patients, determining the critical interstimulus interval at which the masked target could be identified for each subject. Multiple regression analysis revealed that a negative symptom rating was a significant predictor of this interval among schizophrenic patients: greater negative symptoms were associated with longer intervals. Positive symptom ratings were not predictive of performance. Symptom ratings did not predict performance of bipolar patients. Group comparisons revealed that schizophrenic patients who had mixed positive and negative symptoms had significantly longer intervals than normal control subjects did. These results have implications for theories of information processing in schizophrenia.

Adult↗
PubMed1985

The thermodynamics of bovine and porcine insulin and proinsulin association determined by concentration difference spectroscopy.

Difference spectroscopy was used to determine the equilibrium constants and thermodynamic parameters for the monomer-dimer association of bovine and porcine insulin and bovine proinsulin at pH 2.0 and 7.0. At pH 2 delta G degree 25, delta S degree, and delta H degree for dimerization of bovine insulin were found to be -6.6 kcal/mol, -18 cal/mol-deg, and -12 kcal/mol, respectively. Porcine insulin behaved similarly to bovine insulin in its dimerization properties in that delta G degree 25, delta S degree, and delta H degree were found to be -6.8 kcal/mol, -14 cal/mol-deg, and -11 kcal/mol, respectively. At pH 7 delta G degree 25, delta S degree, and delta H degree for dimerization of bovine insulin were found to be -7.2 kcal/mol, -16 cal/mol/deg, and -12 kcal/mol, respectively. At pH 7.0 delta G degree 25, delta S degree, and delta H degree for dimerization of porcine insulin were -6.7 kcal/mol, -11.6 cal/mol-deg, and -10 kcal/mol, respectively. The similarity in the thermodynamic parameters of both insulin species at the different pH's suggests that there are minimal structural changes at the monomer-monomer contact site over this pH range. The dimerization of both insulin species is under enthalpic control. This may suggest that the formation of the insulin dimer is not driven by hydrophobic bonding but, rather, is driven by the formation between subunits of four hydrogen bonds in an apolar environment. At pH 2 delta G degree 25, delta S degree, and delta H degree for dimerization of bovine proinsulin were found to be -5.3 kcal/mol, -26 cal/mol-deg, and -13 kcal/mol, respectively. At pH 7 delta G degree 25, delta S degree, and delta H degree for dimerization of proinsulin were -5.9 kcal/mol, -4.2 cal/mol-deg, and -7.2 kcal/mol, respectively. Although the presence of the C-peptide on proinsulin does not drastically affect the overall free energy change of dimer formation (as compared to insulin), the other thermodynamic parameters are rather drastically altered. This may be because of electrostatic interactions of groups on the C-peptide with groups on the B-chain which are near the subunit contact site in the insulin dimer.

Animals↗
PubMed1985

Semantic priming effects for stimuli presented to the right and left visual fields.

Studies that have addressed the possibility of hemispheric differences in semantic priming effects have yielded contradictory results. This paper reports the findings of two experiments intended to shed greater light on the issue of hemispheric differences in semantic priming. Experiment 1 used a hemiretinal paradigm and examined manual response latency and response accuracy to four types of word pairs; categorically related, syntactically related, unrelated, and pairs containing a nonword member. Experiment 2 examined the effects of unrecognized, disambiguating flank words on verbal responses to a centrally presented homograph. Experiment 1 yielded no significant visual field differences in magnitude of priming effects when response latency served as the dependent measure, although categorical relatedness facilitated response accuracy for left but not right visual field stimuli. In experiment 2, the disambiguating words had a significant effect on meaning interpretation of the homographs that was independent of visual field of presentation. Taken together, the results of these studies are interpreted as indicating that semantic aspects of linguistic input are automatically processed and can influence the content and latency of subsequent responses, whether presented to the left or right visual field.

Adolescent↗
PubMed1985

A Scottish case of nephropathy due to Hantaan virus infection.

An illness characterised by acute renal failure, fever, conjunctivitis and a macular erythematous centrifugal rash is described in a Scot who had not recently travelled abroad. There was serological evidence that the illness was due to Hantaan or a closely related virus.

Acute Kidney Injury↗