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Biomedical subjects

R J Ross

Publications and source records attributed to R J Ross.

At least 127 records · Page 7Linked to original sources
PubMed1985

Exaggerated orthostatic responsivity of plasma norepinephrine in depression.

An orthostatic challenge paradigm was used to assess noradrenergic regulation in depressive disorders. Plasma norepinephrine (NE) concentrations and concurrent blood pressure and pulse were measured at rest and after five minutes of standing in groups of bipolar (N = 22) and unipolar (N = 19) depressives and in 12 partially age-matched healthy female volunteers. Supine plasma NE levels were significantly lower in bipolar patients than in either unipolar depressives or normal volunteers. Following the orthostatic challenge, the fractional NE increase in both patient groups--particularly the bipolar group--was greatly exaggerated, exceeding that in the controls by approximately 100%. Nonetheless, the postural cardiovascular changes--elevations of diastolic blood pressure and heart rate--failed to distinguish the three subject groups. Noradrenergic dysregulation in depression thus is characterized by inefficient hyperreactivity to physiologic stress.

Adult↗
PubMed1985

The effect of clorgyline on noradrenergic function.

A low dosage of the specific MAO-A inhibitor clorgyline (5-10 mg/day) was administered chronically to 10 depressed patients. Peripheral noradrenergic activity, as assessed by measurements of the plasma norepinephrine (NE) concentration, heart rate, and blood pressure, was determined before and after drug treatment. The administration of a low dosage of clorgyline was associated with a decrement in peripheral presynaptic noradrenergic activity. Comparison with the results of similar studies of the effects of desmethylimipramine (DMI) suggests that antidepressant drugs with unrelated primary actions affect peripheral noradrenergic functions differently.

Adult↗
PubMed1985

Differences in lithium effects in depressed and healthy subjects.

To evaluate the neurotransmitter actions of lithium without the confounding biochemical abnormalities associated with affective disorders, Li was given to 12 hospitalized healthy young men. After a 600-mg loading dose, subjects were placed on "therapeutic" Li doses averaging 1225 +/- 300 mg for 1 wk, reaching steady-state plasma levels of 0.82 +/- 0.17 mEq/l. Cardiovascular function at rest and diastolic blood pressure and pulse on standing were not altered by Li. Average baseline plasma norepinephrine (NE) concentration in the supine position (1.07 +/- 0.50 pmol/ml) did not change after 1 wk of Li dosing (1.16 +/- 0.57 pmol/ml). There was similar variability, without mean change, in plasma NE increments after orthostatic challenge and in plasma 3-methoxy-4-hydroxyphenylglycol concentrations before and during Li dosing. Urine volume was stable throughout the week of drug dosing, during which daily NE excretion was constant. In contrast to earlier data obtained in patients with depression receiving Li, there were no Li-related decrements in average whole-body NE or dopamine turnover. Mean daily urinary excretion rates of serotonin and its major metabolite 5-hydroxyindoleacetic acid did not change throughout the study. Our and other studies suggest that Li has a corrective action in patients with depression and hypothesized neurotransmitter abnormalities, but Li does not affect individuals without affective disorders.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

The relationship between serum prolactin and immunocytochemical staining for prolactin in patients with pituitary macroadenomas.

We have studied the relationship between mean pretreatment levels of serum prolactin and the presence of positive immunohistochemical staining for prolactin in the pituitary tumours of 55 patients. Pretreatment serum prolactin was significantly higher in patients with tumours showing many prolactin immunostaining cells than in those with none (P less than 0.001). When the pretreatment serum prolactin exceeded 6000 mU/l, the tumours contained over 90% of prolactin positive cells; one patient was an exception who had received long-term high dose bromocriptine therapy, and her tumour showed only occasional cells with positive staining. When the pretreatment serum prolactin level was under 2500 mU/l, a tumour was found which showed either no cells or fewer than 1% of cells which stained for prolactin. There was no significant difference in pretreatment serum prolactin levels between 11 patients with craniopharyngiomas and 34 patients with pituitary macroadenomas showing no prolactin immunostaining. Seventy-one percent (32) of the 45 patients with craniopharyngiomas or tumours with negative immunostaining for prolactin, had raised pretreatment serum prolactin levels (above 360 mU/l) although this was usually only slightly elevated; the levels exceeded 2500 mU/l in six (13%) of them (two craniopharyngiomas, four pituitary tumours) but in none did the levels exceed 6000 mU/l. Four of the 55 pituitary tumours showed occasional cells (less than 1%) that stained positively for growth hormone. In none of the patients with these tumours was there evidence of acromegaly or pathologically elevated circulating growth hormone levels.

Adenoma↗
PubMed1985

Alteration of pituitary-thyroid function in patients with chronic renal failure treated by haemodialysis or continuous ambulatory peritoneal dialysis.

Pituitary-thyroid function was investigated in 60 patients with chronic renal failure and 18 normal subjects. Serum triiodothyronine and free thyroxine levels were lower in patients treated by either haemodialysis or continuous ambulatory peritoneal dialysis compared with the normal subjects. Serum thyroxine and free thyroxine index were significantly lower in the haemodialysis-treated patients than in the normal subjects. There were no differences in serum thyroxine and free thyroxine index between the continuous ambulatory peritoneal dialysis-treated and normal groups. Serum thyrotrophin was not raised in any of the groups but the serum thyrotrophin response to thyrotrophin-releasing hormone was blunted in both groups of patients. Basal serum prolactin and growth hormone were raised in both groups of patients but there was no significant difference between them. This study confirmed that pituitary-thyroid function is abnormal in patients receiving haemodialysis and established that a similar pattern of abnormalities occurs in patients undergoing continuous ambulatory peritoneal dialysis.

Adult↗
PubMed1984

The effect of desmethylimipramine on the metabolism of norepinephrine.

Eleven normal volunteers were given an acute and two chronic doses of desipramine (DMI). The plasma norepinephrine (NE), 3-methoxy-4-hydroxyphenylglycol (MHPG), and dihydroxyphenylglycol (DHPG) concentrations were measured before and during drug administration. DMI reduced plasma concentrations of MHPG by 13% and DHPG by 17%. After two weeks of drug administration, the MHPG/NE ratio was reduced, and there was a significant negative correlation with the concurrent drug concentration. These results suggest that DMI: (1) reduces the turnover of NE; and (2) diminishes the oxidative deamination of NE. In addition, the drug concentration response relationship indicates that the effects of uptake inhibition may not be maximal until concentrations in the apparent therapeutic range are achieved.

Adult↗
PubMed1984

The effects of desmethylimipramine on cognitive function in healthy subjects.

The cognitive effects of the specific norepinephrine (NE) uptake inhibitor desmethylimipramine (DMI) were examined in normal subjects. Although there were no differences in performance on drug compared to placebo treatment, there was an improvement in cognition 1 week after the drug had been discontinued. On DMI, there was evidence for increased noradrenergic activity, which was uncorrelated with measures of learning and memory. An improvement in mood during drug withdrawal was uncorrelated with the cognitive enhancement. It was concluded that the discontinuation of DMI, a drug which primarily affects NE uptake, improves several measures of learning and memory. Drug effects on cognition may be most pronounced during the withdrawal period.

Adult↗
PubMed1984

Rapidly cycling bipolar disorder and multiple sclerosis.

The authors describe two patients with rapidly cycling bipolar disorder who were found to have multiple sclerosis. They suggest that multiple sclerosis be considered in the differential diagnosis of patients who have affective disorders and minor neurological complaints.

Adult↗
PubMed1984

Public relations for pastoral counseling centers.

Outlines a public relations program in terms of setting objectives, developing programs, and evaluating effectiveness. Details an example of a PR campaign for a Samaritan Center. Notes ways in which a well-planned PR program can increase a pastoral counseling center's effectiveness and visibility.

Colorado↗
PubMed1984

Reduction of norepinephrine turnover by serotonergic drug in man.

Zimelidine (ZIM), a relatively specific serotonin reuptake inhibitor, was administered to 12 hospitalized healthy young male volunteers. Chronic but not acute ZIM caused a modest (23%) but significant elevation of plasma norepinephrine (NE) measured in the standing but not in the supine position. The 24-hr urinary excretion of NE itself was unchanged on chronic drug, whereas "whole-body" NE turnover was reduced by 1 week of ZIM, as evidenced by lowered excretion rates (both individually and summed with NE) of the metabolites 3-methoxy-4-hydroxyphenylglycol (MHPG), normetanephrine (NM), and vanillylmandelic acid. Lack of effect of ZIM on the NM/MHPG excretion ratio (which is increased by desipramine) indicated that ZIM and its major metabolite, horzimelidine (NZIM) are not acting by NE reuptake blockade. These data are consistent with modulating serotonergic influence on the noradrenergic system. Reduction of NE turnover and increasing the efficiency of the NE neurotransmission may be a common pathway of all clinically effective antidepressant treatments.

Adult↗
PubMed1983

Boxers--computed tomography, EEG, and neurological evaluation.

During the last three years, 40 ex-boxers were examined to determine the effects of boxing in regard to their neurological status and the computed tomographic (CT) appearance of the brain. Thirty-eight of these patients had a CT scan of the brain, and 24 had a complete neurological examination including an EEG. The results demonstrate a significant relationship between the number of bouts fought and CT changes indicating cerebral atrophy. Positive neurological findings were not significantly correlated with the number of bouts. Electroencephalographic abnormalities were significantly correlated with the number of bouts fought. Computed tomography and EEG of the brain should be considered as part of a regular neurological examination for active boxers and, if possible, before and after each match, to detect not only the effects of acute life-threatening brain trauma such as subdural hematomas and brain hemorrhages, but the more subtle and debilitating long-term changes of cerebral atrophy.

Adolescent↗
PubMed1983

Effects of desmethylimipramine on plasma norepinephrine, pulse, and blood pressure.

We followed the effects of a tricyclic antidepressant selective for norepinephrine (NE) uptake inhibition, desmethylimipramine (DMI), on blood pressure, heart rate, and plasma NE level in healthy subjects. After a single oral dose of 100 mg DMI, supine systolic and diastolic blood pressure and supine and upright heart rate rose, and there was an increment in heart rate with standing. After long-term low doses of the drug (mean daily dosage 67.5 mg), the upright level and increment with standing in plasma NE also rose. Supine NE levels also rose after the long-term higher dose (mean daily dosage 125 mg). No differences in any measures were detected between the short- and the two long-term dose levels of DMI. Our findings suggest that NE uptake inhibition induces physiologic elevation of NE concentration in the sympathetic neuroeffector region. A similar effect at synapses in the CNS might be involved in the mechanism of antidepressant action.

Adult↗
PubMed1982

Effects of benzodiazepines on single unit activity in the substantia nigra pars reticulata.

Intravenous administration of two benzodiazepines, flurazepam and diazepam, had an inhibitory effect on the firing rates of neurons of the substantia nigra pars reticulata, a brain region with an identified GABAergic innervation. Diazepam was more potent than flurazepam. Bicuculline and picrotoxin, two drugs which block GABAergic transmission, and caffeine and theophylline, two methylxanthines which inhibit benzodiazepine binding, all reversed the inhibition produced by diazepam. The action of theophylline was less consistent than that of caffeine. Similarly, Ro 15-1788, an imidazodiazepine which putatively functions as a specific benzodiazepine antagonist, reversed the diazepam-induced inhibition. These findings are consistent with previous reports which suggest that the benzodiazepines may act through a GABAergic mechanism. In a separate group of experiments, caffeine or Ro 15-1788 was administered alone. While caffeine excited all reticulata, generally had little excitatory effect. These results suggest: 1) that cells of the substantia nigra pars reticulata may not receive a substantial, tonic inhibition mediated by an endogenous benzodiazepine-like substance; and 2) that the methylxanthines may increase reticulata cell firing, at least in part, through mechanisms unrelated to the blockade of benzodiazepine receptors.

Animals↗
PubMed1982

Magnetic fields associated with a nuclear magnetic resonance medical imaging system.

Measurements were made of magnetic and electric field levels in and around a nuclear magnetic resonance imaging system undergoing a clinical trial. Magnetic field levels ranged from 0.04 tesla (T) in the imaging volume down to about 0.0006 T at the end of the patient table. The peak radio-frequency magnetic field level was 15 amperes per meter (A/m) in the imaging volume, while the rms value was 4.6 A/m. The specific absorption rate resulting from the radio-frequency magnetic field was calculated to be no more than 0.017 watts per kilogram (W/kg). The radio-frequency electric field was detectable only within a few centimeters of the coil assembly, and does not significantly contribute to the specific absorption rate. These exposure levels were much lower than existing guidelines for clinical NMR procedures.

Clinical Trials as Topic↗
PubMed1982

Site location and requirements for the installation of a nuclear magnetic resonance scanning unit.

The installation of a nuclear magnetic resonance unit in any diagnostic facility involves certain location and environmental requirements. Based on our experience with the FONAR QED 80 system, we have delineated the major factors which must be considered when planning for such an installation. The major requirements are location and space. Suggested layouts for the suite and the control room are included. Certain environmental specifications will vary depending on the location of the facility and the type of unit installed.

Air Conditioning↗