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S Warren

Publications and source records attributed to S Warren.

At least 55 records · Page 3Linked to original sources
PubMed1993

Ultrastructure of the macaque ciliary ganglion.

The primate ciliary ganglion is an obligatory relay in the pathways that control the lens and pupil for the near response and the light reflex, two functions which have been the target of increasing inquiry in behavioural physiology paradigms. This investigation provides a comprehensive description of the ultrastructure of the ciliary ganglion in the rhesus monkey (Macaca mulatta). The results indicate that the ciliary ganglion contains a heterogeneous population of neurons in terms of somatic size, cytoplasmic contents and somatodendritic distribution of terminals. Variations in the clear and dense-cored vesicle content of the synaptic profiles present in the ganglion suggest that the synaptic inputs are also heterogeneous and may mediate separate functions. Several characteristic ultrastructural features of the macaque ciliary ganglion are noteworthy. Despite the large size of the neuronal somata, most cells do not exhibit contacts directly onto the somatic membrane. However, the few somata that do receive direct input often display several axosomatic contacts. The vast majority of synaptic interactions occur in the perisomatic neuropil, where the postsynaptic elements consist of simple and complex somatic appendages, as well as dendrites with their appendages. There is little neuropil independent of these immediately perisomatic regions. In some cases, axonal terminals form the central element of complex glomeruli, in which they are presynaptic to numerous spine-like profiles. In other cases, axon terminals and their postsynaptic targets are found within shallow depressions in the somatic membrane or, occasionally, deeply embedded within the borders of the postganglionic neuron. The somata and all the non-myelinated neuronal elements are surrounded by interdigitating, electron-dense processes of satellite cells. These glial cells are sometimes found in shallow recesses, or deeply embedded within the borders of the neuronal somata. The complexity of the ultrastructure of the ciliary ganglion in the macaque suggests that this ganglion may not be a simple relay in the parasympathetic outflow to the eye, but may instead be the site of neuronal processing of the preganglionic input.

Animals↗
PubMed1993

Prevalence, incidence, and characteristics of multiple sclerosis in Westlock County, Alberta, Canada.

We report a prevalence study of multiple sclerosis (MS) in the town of Westlock and surrounding county of Westlock, in Alberta, Canada. The prevalence rate for clinically definite MS on January 1, 1991, was 200/100,000. The average annual incidence rates for patients living in the area at onset were 1.91/100,000 for 1950-1959, 2.85/100,000 for 1960-1969, 3.82/100,000 for 1970-1979, and 7.26/100,000 for 1980-1989. Forty-eight percent of the patients were relapsing-remitting. Sixty percent were still walking without assistance. The female-to-male ratio was 1.4:1. Mean current age was 47, age at onset 30, and duration of illness 18 years. The majority of patients (40%) experienced multiple symptom onset. Forty percent were of single ethnic origin (primarily British); the remainder were predominantly north European combinations. Twenty-four percent of patients reported another MS relative, six first-degree and one second-degree relative.

Adult↗
PubMed1993

The role of iron in the cytotoxicity of tumor necrosis factor.

The effect of iron on the cytotoxicity of tumour necrosis factor-alpha (TNF, cachectin) was examined in L929 cells, which are killed by TNF at low concentrations. In L929 cells, the addition of iron (FeNTA) either prior to or concurrent with the addition of TNF markedly augmented the cytotoxicity of TNF over a wide range of TNF concentrations. Iron alone was not cytotoxic to the cells and did not inhibit protein synthesis. The iron chelator deferoxamine was able to protect against TNF cytotoxicity in L929 cells. Iron chelators also protected L929 cells from the cytotoxicity of TNF plus cycloheximide, suggesting that iron plays a role in this mode of TNF killing as well. TNF did not induce the synthesis of ferritin heavy chain in L929 cells. These experiments demonstrate that cellular iron status affects the ability of TNF to kill sensitive target cells.

Animals↗
PubMed1993

Monte Carlo fluorescence verification of experimental results for the combined ultrasonic and spectroscopic imaging of coronary artery disease.

A system is being tested that combines fluorescence spectroscopy and intravascular ultrasound to image both chemical composition and structure of arterial tissue in vitro. In this system, distances obtained from A-mode ultrasound will be used to compensate for decreases in fluorescence intensity due to the detector-sample separation distance r. For concentrated rhodamine, a fluorescent dye, compensation has been experimentally achieved assuming fluorescence is emitted isotropically and decreases as 1/r2. For dilute rhodamine and human arterial tissue, however, compensation must be achieved with different models, since light penetration into the sample is more significant. Using optical properties consistent with those of the aforementioned samples, experimental results are successfully simulated with a Monte Carlo model for tissue fluorescence. Angular profiles are presented that demonstrate the quantitative difference between the fluorescence of these mediums. The profiles support the hypothesis that, although fluorescence is emitted isotropically within tissue, the angular distribution of light exiting the tissue is not isotropic due to reabsorption events.

Aorta↗
PubMed1992

Simulation of motion on the skin. V. Effect of stimulus temporal frequency on the representation of moving bar patterns in primary somatosensory cortex of monkeys.

1. To assess the mechanisms used by cortical neurons to sense motion across the skin, we applied pulsatile stimuli to a series of adjacent positions on the glabrous skin of the hand using a computer-controlled OPTACON stimulator. We describe responses of 129 single neurons in primary somatosensory cortex of alert monkeys to a horizontal bar pattern that was displaced proximally or distally in 1.2-mm steps at 10-, 20-, and 40-ms intervals (100, 50, and 25 Hz, respectively). These frequencies span the range in which apparent motion is transformed perceptually in humans from a smooth uninterrupted sweep into a series of distinct pulses that are resolved as separate events. The experiments are thus designed to decipher the neural correlates distinguishing continuous motion from discrete taps. 2. Cortical receptive fields mapped with moving bar patterns spanned 5-24 rows on the tactile array (16.2 +/- 5.4, mean +/- SD). Over 40% of the fields encompassed 18 or more rows (greater than or equal to 21.6 mm), allowing these neurons to integrate spatial information from an entire image displayed on the OPTACON. Cortical receptive fields are considerably larger than those of mechanoreceptors mapped with the same moving bar patterns (4.2 +/- 2.3 rows, mean +/- SD), reflecting convergent inputs in subcortical and cortical relays. Responses were either relatively uniform across the field or strongest at the initial point of entry, depending on the frequency of stimulation. A sharply defined field center was absent from most of the cells recorded in this study. 3. Temporal frequency of stimulation appears to be a major determinant of cortical firing patterns. Low-frequency stimuli are more effective in activating cortical neurons, producing more spikes per sweep and greater phase-locking to individual stimuli than do high frequencies. The total spike output of cortical neurons is proportional to the pulse interval over the range 10-40 ms, increasing linearly by an average of 5.9 spikes/10-ms increase in pulse period. Peak firing rates and modulation amplitude are also highest when pulses are presented at long intervals, falling significantly as the stimulation frequency rises. The reduction in firing at high pulse rates is apparently due to central mechanisms, as both rapidly adapting and Pacinian corpuscle afferents display nearly constant spike outputs and uniform sensitivity within the field when tested with identical bar patterns. Central networks thus behave as low-pass filters, reducing cortical responses to rapidly applied sequential stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1992

Prevalence of multiple sclerosis in Barrhead County, Alberta, Canada.

A prevalence study of multiple sclerosis (MS) was carried out in the town of Barrhead and surrounding county of Barrhead, in Alberta, Canada. The prevalence rate for clinically probable/definite multiple sclerosis on January 1, 1990 was 196/100,000. The average annual incidence rates for patients living in the area at onset were 1.31/100,000 for 1950-59, 4.97/100,000 for 1960-69, 3.77/100,000 for 1970-79, and 4.22/100,000 for 1980-89. Fifty percent of the patients were relapsing-remitting. Sixty percent were still walking without assistance. The female-to-male ratio was 1:1. Mean current age, age at onset and duration of illness were 49, 27 and 22 years respectively. The majority of patients (40%) experienced multiple symptom onset. Fifty percent were of single ethnic origin (either British or German); the rest were predominantly North European combinations. Forty percent of patients reported another MS relative. MS had affected the work status of 60% of the patients, 15% of whom were confined to an extended care centre.

Adult↗
PubMed1991

Decreased seasonal mesor of platelet 3H-imipramine binding in depression.

Seasonal cycles of platelet 3H-imipramine binding were compared in 49 endogenous unipolar depressed patients and 20 normal volunteers. A significant sinusoidal component was detected in the Bmax of binding in both patients and controls with similar amplitudes and seasonal peaks. However, the yearly average (mesor) of the patient group was significantly lower (20.0%) than that of the normal controls. The results support earlier claims of a diminished platelet binding in endogenous depression and indicate that this decrease was still evident in the presence of a 48.2% (controls) to 65.8% (patients) seasonal variation. Control Bmax values were normally distributed about a best-fit mean (cosinor fit). In contrast, patient values appeared to be bimodally distributed with one mode that was similar to controls and one mode that was substantially lower. In general, psychiatric symptoms failed to distinguish between patients with high and low platelet binding and no correlation was found between Bmax and severity of illness (HAM-D).

Adolescent↗
PubMed1991

Emotional stress and coping in multiple sclerosis (MS) exacerbations.

Ninety-five pairs of MS patients in exacerbation and remission were compared on emotional stress in the previous three months. Patients in exacerbation scored higher on emotional disturbance and intensity of stressful events than patients in remission, but lower on frequency of compensating uplifts. There was also a tendency for more patients in exacerbation than remission to favour emotion-focused coping techniques over problem-solving or social support. Whether patients building to an exacerbation over-react to various events or unresolved emotional stress precipitates exacerbations, MS patients might benefit from counselling in stress reduction techniques.

Adaptation, Psychological↗
PubMed1991

Influence of medical history on assessment of at-risk infants.

The influence of knowledge of their medical history on the assessment of at-risk infants was examined. Two at-risk infants, one with a high-risk medical history and one with a low-risk history, were assessed and videotaped using the Movement Assessment of Infants. 41 physical therapists were randomly assigned to assess the videotaped examinations in four groups with different knowledge of the infants' histories (high-risk infant with actual or low-risk history; low-risk infant with actual or high-risk history). The clinical significance of the difference in total risk scores between knowledge conditions of a high-risk history and a low-risk history was greater for the low-risk infant. The higher mean total risk score for the low-risk infant assessed with a high-risk history suggests that false positive results could occur which may alter parents' perceptions and interactions with the infants and consequently influence their development.

Asphyxia Neonatorum↗
PubMed1991

Risk factors by onset age in multiple sclerosis.

Some investigators have suggested that there are different forms of multiple sclerosis (MS) based on onset age, and that each has a different etiology. 173 Canadian MS patients were matched to controls on age, gender, race and risk zone prior to age 15. Data were collected on: age at onset, gender, initial symptom, disability level, residence history and family background. Three onset age subgroups (early, intermediate and late) were derived. Matched-pair logistic regression analysis indicated that rural residence, use of well water and an MS family history distinguished between patients and controls overall, but showed no significant interaction with onset age. A family history of diabetes distinguished between patients and controls with evidence of age interaction, in that this risk factor decreased in importance as onset age increased.

Adolescent↗
PubMed1991

Pulmonary phaeohyphomycosis due to Xylohypha bantiana.

We encountered a rare case of pulmonary phaeohyphomycosis due to Xylohypha bantiana documented by culture. This dematiaceous (darkly pigmented) fungus is primarily neurotropic. It usually produces phaeohyphomycosis of the central nervous system but may also involve the skin and subcutaneous tissues. The patient, a 49-year-old woman with a history of steroid-treated inflammatory bowel disease, was found to have a lung nodule consisting of granulomas that contained dark hyphal fragments that stained positively with the argentaffin reaction. Surgical excision was curative and appears to be the treatment of choice.

Adrenal Cortex Hormones↗
PubMed1989

Self-reported depressive symptomatology, mood ratings, and treatment outcome in sleep disorders patients.

Based on self-rating questionnaire evaluation of symptoms of major affective disorder, 67% of patients who presented to a major sleep disorders center reported an episode of depression within the previous 5 years, and 26% described themselves as depressed at presentation. Furthermore, patients with sleep apnea, narcolepsy, or sleep-related periodic leg movements all averaged high rates of self-reported depressive symptomatology, which suggests that sleep disorders should be considered in the differential diagnosis of affective disorders, and vice versa. Change scores on the Profile of Mood States were obtained for four subgroups of patients who were undergoing conventional treatment. Significant improvement in scores was observed in obstructive sleep apneics treated surgically and in patients with sleep-related periodic leg movements placed on clonazepam, but not in narcoleptics placed on a stimulant or in insomniacs with chronic use of sedative-hypnotic drugs who were withdrawn from sleep medications. Differential improvement in POMS scores after treatment for different sleep disorders could mean that the relationship to mood disturbance differs for different sleep disorders.

Adolescent↗
PubMed1989

Changes in platelet 3H-imipramine binding with chronic imipramine treatment are not state-dependent.

One month of imipramine treatment increased both the Kd and Bmax of platelet 3H-imipramine binding in 11 endogenous unipolar depressed patients. Continued treatment (13 weeks) of 5 patients subsequently lowered the Bmax values of 2 patients who had initially shown the largest increases, so that binding was no longer significantly elevated after 13 weeks. The observed changes in Kd but not in Bmax, could be explained by the carryover of tightly bound drug to the binding assay, although neither of the measures were correlated with plasma imipramine levels. Posttreatment Bmax (4 weeks) values were inversely related to plasma cortisol levels, although a weak but positive correlation was found before treatment. No significant change was found in plasma cortisol with treatment. Clinical responses were not related to cortisol or Bmax changes, although optimal improvement was associated with extreme values (high and low) of pretreatment Bmax. The present results, obtained with imipramine, and similar results obtained after nortriptyline and electroconvulsive shock by others, suggest that at least some antidepressants may induce transient changes in the Bmax of platelet binding that are independent of affective state.

Adolescent↗