Search PubMed⌕ Search

Biomedical subjects

S Hogg

Publications and source records attributed to S Hogg.

31 records · Page 2Linked to original sources
PubMed1994

Regional differences in rat benzodiazepine binding in response to novelty and cat odour.

Laboratory rats exhibit innate behavioural and corticosterone responses when exposed to cat odour. However, not all are responsive and differences in benzodiazepine receptor binding between responders and non-responders were explored. Rats were exposed to cat odour for 5 min and based on time spent sheltering were divided into responders (n = 21; mean +/- SEM = 244 +/- 8.2 sec) or non-responders (n = 20; 43.9 +/- 4.8 sec). Four days later, both groups were randomly allocated among 3 experimental conditions: home-cage, neutral or cat odour, and killed 30 min after exposure. [3H]flunitrazepam binding was performed at two ligand concentrations (2 and 10 nM); where significant differences in single point binding were found, Scatchard analysis was performed on pooled samples. In hippocampus and frontal cortex responders had significantly lower binding than non-responders. In hippocampus this was most apparent when the rats were exposed to the novel test situation, i.e. neutral odour and was due to a reduction in affinity (Kd = 0.4 and 1.2 nM non-responders and responders). In frontal cortex, differences were significant only following exposure to cat odour (Bmax = 2663 and 1501 fmol/mg protein in non-responders and responders). The changes in amygdala were not significant.

Amygdala↗
PubMed1994

Receptor binding in Japanese quail selected for long or short tonic immobility.

Japanese quail, selectively bred for long (LTI) and short (STI) tonic immobility (TI) responses, are thought to represent high and low fear groups, respectively. To study the neurochemical mechanisms underlying the behavioral distinctions, binding parameters were determined at the benzodiazepine, 5-HT1A, 5-HT3, alpha 2, and opioid receptor sites in the forebrains of the two lines. No differences were found in 5-HT1A, 5-HT3, alpha 2, mu- or kappa-opioid receptor binding between the lines. The KD for the binding of [3H]-flunitrazepam at the benzodiazepine receptor was significantly greater in the LTI than in the STI birds, indicating lower affinity for benzodiazepine ligands. The lines did not differ in benzodiazepine receptor number. Using [3H]-naltrindole, the LTI line was found to have fewer delta-opioid receptors than the STI line; the birds did not vary with respect to the affinity of these receptors. Thus, the selective breeding of the two lines has resulted in differences in benzodiazepine and delta-opioid binding, and these could produce differences in activity levels, fear, and pain responses, all of which could contribute to the tonic immobility response.

Animals↗
PubMed1994

Responders and nonresponders to cat odor do not differ in other tests of anxiety.

Laboratory-bred rats can be divided into those showing clear innate behavioral responses to the odor of a predator (a cat) and those showing no response. However, these two groups did not differ in their responses to a neutral odor, or in the social interaction or elevated plus-maze tests of anxiety. This suggests a distinction between phobic anxiety (generated by cat odor) and a generalized anxiety state (generated by novelty in the other tests). Trial 2 in the plus-maze generates a state of fear that is distinct from that generated on trial 1, and one suggested to reflect phobic anxiety. Although the groups of cat responders and nonresponders did not differ in their scores on trial 2 in the plus-maze, two clear groups of responders and nonresponders could be identified on this trial (but not on trial 1 or in the social interaction test). This suggests that it is possible to identify bimodal populations of rats in tests of both innate and acquired simple phobias.

Animals↗
PubMed1990

Validity and reproducibility of a screening examination for neurological abnormality in persons exposed to methylmercury.

The validity and reliability of methods of screening for neurologic abnormality were assessed as part of an investigation of an outbreak of methylmercury exposure in two northern Canadian communities. Four hundred and forty-five Cree Indians were examined by one of five neurologists in a complete neurologic examination and by a trained paramedical observer in a short screening examination which included a selection of tests from the complete examination. The screening examinations were recorded on videotape and those for 176 men were reviewed by the five neurologists and the paramedical observer 1 year after the field studies. The prevalence of abnormality assessed in the field screening examination was greater than that assessed during the complete neurologic examination, for neurologic features included in both examinations. However, agreement between examinations in identifying individuals with abnormality was poor with the sensitivity of the screening examination falling under 50% for half of the neurologic features examined. In contrast, specificity was over 80% for 14 of 18 features. Review of the videotapes revealed marked interobserver variation in the assessment of the prevalence of neurologic abnormality and poor agreement with the neurologic examinations in the identification of abnormality in individuals, with kappa less than 0.2 for most neurologic features. The levels of agreement between the neurologic examinations and the screening examinations conducted in the field and by videotape review suggest that neither screening examination provides equivalent information in the identification of the presence of abnormality to that obtained in the neurologic examination.

Female↗
PubMed1988

Measurement of the clinical status of patients with breast cancer: evidence for the validity of self assessment with linear analogue scales.

We have assessed the validity of a method of measurement for describing the clinical status of patients with breast cancer. One hundred and nine patients with breast cancer assigned numerical values to their own state of health using linear analogue scales. We have shown previously that this method of measurement is reliable and corresponds well with other methods of assessment. Validity was assessed in this study by examining the ability of measurements to distinguish between groups of patients who differed either in the presence of metastatic disease or in the treatments they were receiving. All patients completed the same set of 29 linear analogue scales that enquired about the severity of health related problems and symptoms. In general, patients with metastatic disease were clearly distinguished from patients without metastases by their scores on items related to physical function. Patients receiving chemotherapy were distinguished from those not receiving chemotherapy by their scores on treatment related toxicities. Measures of psychological and social health were similar in patients receiving chemotherapy regardless of disease status. These results provide further support for the validity of measurement of clinical status with linear analogue scales scored by patients.

Breast Neoplasms↗
PubMed1986

Factor V in human vascular endothelium and in endothelial cells in culture.

Human blood vessels and human umbilical vein endothelial cells in culture were examined for the presence and synthesis of factor V. Factor V antigen was detected on the luminal surface of blood vessels washed with buffers containing calcium but was absent from segments of the same vessels perfused with buffers containing EDTA. Very low levels of endogenous factor V antigen were found in endothelial cells in culture but these cells did not synthesise factor V in sufficient quantities to be detected by the present methods. Factor V activity was not detected in any of the present cell preparations.

Adult↗
PubMed1986

The relationship between von Willebrand factor antigen and fibronectin in human plasma, endothelial cells and fibroblasts in culture.

The distribution of von Willebrand factor antigen (vWFAg) and fibronectin (Fn) in endothelial cells and in fibroblasts in culture was examined using immunohistological methods. Extracellular matrices were studied after removal of cells by mild hypotonic lysis. Co-distribution of these antigens was also examined after culture of fibroblasts in the presence of endothelial cell conditioned medium or of exogenous vWFAg. The presence of intracellular vWFAg and its association with extracellular Fn in confluent endothelial cells was confirmed. Furthermore, both antigens were detected in matrices from fibroblasts grown in the presence of human plasma and endothelial cell medium. vWFAg was not found, however, in the absence of endothelial cell conditioned medium or in experiments using human serum in place of plasma. Cross-linking of vWFAg was examined using quantitative and qualitative electrophoretic methods. Levels of vWFAg in serum from patients with severe Haemophilia A were approximately 50% of those found in the corresponding plasma. Furthermore, vWFAg was reduced to similar levels in serum from normal blood to which heparin was added. The lowest levels of vWFAg were found in the presence of sufficient heparin to totally inhibit the formation of fibrin. In contrast, levels of Fn remained unchanged in these circumstances. The results did not support the view that vWFAg was cross-linked to Fn in plasma by thrombin-activated factor XIII. In addition, immunoelectrophoresis of cultured endothelial cell products did not demonstrate cross-linking of vWFAg to Fn. The data are consistent with the concept that deposition of vWFAg on the subendothelium is dependent on viable endothelial cells or on another product of these cells.

Blood Coagulation↗
PubMed1986

Measurement of serum DNA binding in chronic active hepatitis and systemic lupus erythematosus using the Farr assay.

Antibodies to double-stranded DNA (dsDNA), generally regarded as highly specific for systemic lupus erythematosus (SLE), have also been reported in chronic active hepatitis (CAH). Using the Farr assay and E. coli DNA, fractionated by benzoylated-naphthoylated-DEAE cellulose chromatography into dsDNA and dsDNA containing single-stranded regions, we compared the serum DNA binding of CAH and SLE patients. Although CAH sera were found to have dsDNA binding significantly above the normal control group such binding was of low level and we could find no evidence of markedly elevated dsDNA binding in CAH. However 12 of the 20 CAH sera studied did bind preferentially to dsDNA containing single-stranded regions suggesting the presence of anti-single-stranded DNA antibodies. We conclude that the description of elevated anti-dsDNA antibodies, as measured by the Farr assay, in CAH is due to the interaction of anti-single-stranded DNA antibodies or other serum components with single-stranded DNA contaminating dsDNA preparations.

Adult↗
PubMed1986

Time course of the binding of platinum to subfractions of the kidney cytosol in the cisplatin-treated rat.

In male rats treated with cis-dichlorodiammine platinum II (cisplatin, 5 mg/kg, s.c.), the accumulation of Pt in the kidneys occurred in two phases. Total renal Pt content peaked after 15 min and decreased rapidly, then increased to a second peak after 48 hr and thereafter decreased slowly during the next 6 days. Sephadex G-50 chromatography showed that in the kidney cytosol Pt was located in three subfractions; a high molecular weight (HMW) fraction (relative elution volume, Vr = 0.9-1.2), a heterogeneous low molecular weight (LMW) Pt-binding fraction (Vr = 1.2-2.2) and a LMW complex fraction (Vr = 2.2-2.7). Initially, most of the Pt was located in the HMW- and LMW complex fractions and the initial loss of Pt from the cytosol occurred from the latter fraction. In contrast, during the second phase much of the additional Pt accumulated in the LMW Pt-binding fraction, the Pt content of which paralleled that in the whole kidney. It is suggested that the LMW Pt-binding fraction may play a significant role in the accumulation and retention of Pt and may provide a site of detoxification during the second phase of influx of Pt into the kidneys.

Animals↗
PubMedDate not supplied

Contrasting behavioural effects of 8-OH DPAT in the dorsal raphé nucleus and ventral hippocampus.

Administration of the 5-HT1A receptor agonist (+-)-8-Hydroxy-dipropylaminotetralin (8-OH DPAT, 50 ng) into the dorsal raphé nucleus (DRN) increased social interaction but did not change the motor activity of rats tested in high light, thus indicating an anxiolytic response. This effect was blocked by coadministration of the 5-HT1A antagonist, tertatolol (3 micrograms). In contrast, 8-OH DPAT (50 and 100 ng) was without effect on social interaction when administered to the DRN projection area in the ventral hippocampus, but did change locomotor activity. The effects depended on the light level and dose: thus when the rats were tested in low light, 50 ng increased locomotor activity, but in high light a decrease was found with 100 ng and also an induction of wet dog-shakes. Thus, our results support the importance of the somatodendritic autoreceptors in the DRN in alleviating anxiety, whereas the post-synaptic receptors in the ventral hippocampus play no role. They do, however, mediate changes in activity and the 5-HT syndrome.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMedDate not supplied

Alterations in core body temperature, locomotor activity, and corticosterone following acute and repeated social defeat of male NMRI mice.

Repeated social defeat of male NMRI mice, coupled with the stress of continuously living opposite a dominant animal, induces a citalopram-reversible increase in anxiety. The experiments reported in the present paper were performed in an attempt to further validate this paradigm by studying the effects of acute and repeated social defeat on corticosterone and the circadian rhythms of core body temperature and locomotor activity, measured by telemetry. Acute social defeat induced a large (controls: 37.14+/-0.29 degrees C; subordinates: 39.79+/-0.33 degrees C) increase in core body temperature and corticosterone (controls: 30.14+/-2.70 ng/ml; subordinates: 89.62+/-9.25 ng/ml). Repeated social defeat (24 defeats) induced a chronic elevation in core body temperature across 24-h (controls: 36.62+/-0.04 degrees C; subordinates: 37.11+/-0.16 degrees C) in subordinate animals and a very large increase in corticosterone (controls: 28.60+/-1.27 ng/ml; subordinates: 441.52+/-8.86 ng/ml). These results illustrate that the chronic social defeat procedure described in this paper induces a state of chronic stress in the subordinate animals. Further studies are warranted to ascertain if the chronic hyperthermia and increases in corticosterone observed in the subordinate animals could be attenuated by chronic antidepressant treatment, thus further extending the predictive validity of this model.

Animals↗
PubMedDate not supplied

Analysis of task demands in apraxia.

Several task demands were examined in a battery of praxis tests: the movement system (limb versus axial), input modality (command versus imitation), movement complexity (single gestures versus a sequence of gestures), type of limb gesture (transitive versus intransitive), and the representational nature of the gestures. Performance accuracy for a group of left hemisphere patients was significantly lower than for two other groups of patients with either right hemisphere damage or no brain damage on all gestures. The right hemisphere patients were significantly different from the normals only for the most complex gestures involving a three movement sequence. Within the left hemisphere group performance to command was not different from imitation. Representational and nonrepresentational gestures were not different, and axial gestures was not different from the limb gestures. The transitive and complex gestures were not different but were both performed less accurately than the intransitive gestures. The implications of these findings for understanding apraxia were discussed.

Analysis of Variance↗