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Biomedical subjects

K R Krishnan

Publications and source records attributed to K R Krishnan.

At least 19 recordsLinked to original sources
PubMed1992

Adrenal gland enlargement in major depression. A computed tomographic study.

To determine whether the well-documented hyperactivity of the hypothalamic-pituitary-adrenal axis in depressed patients includes adrenal gland hypertrophy, adrenal gland size was evaluated by computed tomography. Assessments consisted of (1) global ratings by two radiologists ignorant of the diagnostic identity of the subjects and (2) calculation of adrenal volume. Of the 38 patients with major depression, 12 were rated as exhibiting adrenal hypertrophy. Adrenal volumes in the depressed patients were significantly increased when compared with those of normal controls. Adrenal gland size was not correlated with dexamethasone suppression test results, patient age, duration of the depressive episode, or depression severity. These results are concordant with the hypothesis that chronic corticotropin hypersecretion in depression results in adrenocortical hypertrophy. Adrenal gland enlargement may be a measure of cumulative lifetime depression.

Adrenal Glands↗
PubMed1992

Magnetic resonance imaging of the caudate nuclei in depression. Preliminary observations.

A role of the caudate nucleus in depression has been suggested from relevant clinical conditions, such as patients with Huntington's disease or caudate infarcts, as well as animal studies. Correlations of caudate nucleus disease with depressive symptoms have been limited to autopsy studies and cases of gross pathological disorder, such as large infarcts. We used serial axial high-field magnetic resonance images and an unbiased stereological technique to estimate the volumes of the caudate nuclei in 50 patients who met DSM-III criteria for major depression (23 men, 48.3 +/- 17 years old) in comparison with 50 age- and gender-matched normal controls free of major neurological and psychiatric disorders. Depressed patients had smaller caudate nucleus volumes (5.2 +/- 1.6 cm3) compared with controls (6.2 +/- 1.7 cm3). Right and left caudate nucleus volumes were smaller in depressed patients compared with controls. Age was negatively correlated with caudate nucleus volumes in depressed patients as well as in controls. Caudate nucleus volumes in depressed patients were inversely correlated with the bicaudate and bifrontal indices. These results may be the first demonstration of diminished caudate nucleus volumes in depression and suggest a role for the caudate nucleus in the pathogenesis of major depression.

Age Factors↗
PubMed1992

Magnetic resonance in patients with affective illness.

Magnetic resonance imaging is presently being utilized to understand the neuropathology of affective disorders. Present research has demonstrated brain changes in affective disorders that correlate with neuroendocrine findings and are similar to changes noted in normal aging.

Humans↗
PubMed1992

In vivo assessment of pituitary volume with magnetic resonance imaging and systematic stereology: relationship to dexamethasone suppression test results in patients.

The relationship between dexamethasone suppression test (DST) results and in vivo pituitary volume was studied in 24 psychiatric inpatients. The principles of systematic stereology were used to measure pituitary volume from 3-mm contiguous sagittal spin-echo magnetic resonance (MR) images of the brain. There was no correlation between pituitary volume and 3 p.m. or 10 p.m. postdexamethasone (post-DEX) plasma cortisol concentrations. However, when multiple regression analysis was performed to relate pituitary volume to gender, age, and post-DEX plasma cortisol concentrations, there was a significant relationship between pituitary volume and age, gender, and 10 p.m. post-DEX cortisol plasma concentration. This is the first study to demonstrate a method that directly measures, rather than estimates, in vivo pituitary volume. Furthermore, it suggests that activation of the hypothalamic-pituitary-adrenal axis in psychiatric patients, as manifested by elevated post-DEX cortisol concentrations, may influence pituitary volume.

Adult↗
PubMed1992

RU486 in depression.

RU486 is a synthetic glucocorticoid antagonist. The authors used RU486 to examine the hypothesis that the elevated plasma cortisol and ACTH in patients is due to suprahypophyseal stimulation of the anterior pituitary. Seven patients and matched controls were studied before and after the administration of RU486. RU486 produced an increase in HPA activity in depressed patients. Thus providing support for the hypothesis that there is increased suprahypophyseal stimulation of the anterior pituitary.

Adrenocorticotropic Hormone↗
PubMed1992

An investigation of the relationship between environmental factors and job satisfaction in intensive nursing, with particular reference to spinal trauma.

The literature concerning the effects of stress on health service professionals has increased rapidly over the past 10 years (eg Holland et al, Koran et al, Stone et al). The potential sources of such stresses are briefly reviewed and the involvement of the working environment as a source of stress is highlighted. The present investigation has examined the experience of 3 groups of nurses, working in spinal injuries, head injuries, and general medicine, using a standardised questionnaire devised by Moos. Significant differences were found between the 3 nurse groups on 3 subscales of the test (autonomy, innovation, and comfort), and the implications of the findings are discussed.

Adult↗
PubMed1992

Mortality, morbidity, and psychosocial outcomes of persons spinal cord injured more than 20 years ago.

Mortality, morbidity, health, functional, and psychosocial outcomes were examined in 834 individuals with long term spinal cord injuries. All were treated at one of two British spinal injury centres: the National Spinal Injuries Centre at Stoke Mandeville Hospital or the Regional Spinal Injuries Centre in Southport; all were 20 or more years post injury. Using life table techniques, median survival time was determined for the overall sample (32 years), and for various subgroups based on level and completeness of injury and age at injury. With the number of renal deaths decreasing over time, the cause of death patterns in the study group as it aged began to approximate those of the general population. Morbidity patterns were found to be associated with age, years post injury, or a combination of these factors, depending upon the particular medical complication examined. A current medical examination of 282 of the survivors revealed significant declines in functional abilities associated with the aging process. Declines with age also were found in measures of handicap and life satisfaction, but three quarters of those interviewed reported generally good health and rated their current quality of life as either good or excellent.

Adaptation, Psychological↗
PubMed1992

Perceptual deprivation in the acute phase of spinal injury rehabilitation.

Patients in intensive care units are often reported to experience psychological disturbances which may be attributable to a number of well-researched causes. However, it is suggested that the total lack of proprioceptive and motor feedback after spinal trauma may be a significant factor in the genesis of these disturbances which are unique to this group of patients. All cases admitted to the Regional Spinal Injuries Centre in Southport from January 1987 through December 1990 were assessed (n = 187) and the conditions surrounding the occurrence of behavioural disturbances (n = 23, 12.3%) established. The level of interaction with relatives and significant others was established for all acute admissions, and low frequency was found to correlate significantly with the development of perceptual deprivation experiences. The effects of inadequate somatosensory input, lesion level, increasing age, and visitor variability for spinal patients is discussed and an algorithm presented to highlight the potential factors associated with aetiology and treatment of the problem. The implications of these findings for the future management of acute spinal trauma are discussed.

Adult↗
PubMed1991

Magnetic resonance findings in patients with early-onset Alzheimer's disease.

The magnetic resonance scans of 22 patients with early-onset Alzheimer's disease (AD) were compared to 16 age-matched neurologically normal controls for the presence of white matter subcortical hyperintensities (SCH) and periventricular hyperintensities (PVH). Patients with AD were significantly more likely to have evidence of PVH (p less than 0.01) than age-matched controls. There was no significant difference between the two groups in either the frequency of SCH or the size of the largest lesion. Within the AD group, there was no difference demonstrated in the location of the SCH, either in the anterior-posterior plane or between the two hemispheres. Patients with AD more frequently demonstrated ventriculomegaly (p less than 0.001) and sulcal widening (p less than 0.05) compared with controls. This study suggests that the SCH seen in early-onset AD patients on MRI are related more to the aging process than to the AD process and that the increased frequency of PVH may have a relationship to the disease process.

Aged↗
PubMed1991

Platelet [3H]-imipramine binding and leukoencephalopathy in geriatric depression.

We examined the relationship between platelet [3H]-imipramine binding and leukoencephalopathy as assessed by 1.5 Tesla Magnetic Resonance Imaging (MRI) in 21 elderly depressed patients who satisfied DSM-III criteria for major depression. Both drug-free platelet [3H]-imipramine binding and brain MRI studies were obtained during the same episode of depression. Our findings show a significant inverse relationship between frequency of subcortical hyperintensity (SCH) and the number (Bmax) of platelet [3H]-imipramine binding sites. Patients with Bmax less than 850 fmol/mg protein had significantly larger SCH compared with patients with a higher Bmax. These data provide further support to the potential use of platelet [3H]-imipramine binding studies and brain MR imaging as diagnostic adjuncts in geriatric depression and suggest, moreover, that these two biological markers may be linked in geriatric patients with depression.

Aged↗
PubMed1991

Fast feedback regulation of ACTH by cortisol.

1. Fast feedback regulation of ACTH by cortisol has not been well studied in humans. The authors studied the existence and characteristics of fast feedback regulation in normal humans. 2. Hydrocortisone hemisuccinate was infused at two different rates: 6 mg/hour and 12 mg/hour for two hours. 3. The studies did not demonstrate the existence of fast feedback regulation of basal ACTH concentration by cortisol in man. Further, the response was variable and the rate sensitive character was difficult to demonstrate.

Adrenocorticotropic Hormone↗
PubMed1991

Magnetic resonance imaging in biological psychiatry.

1. Although clinicians have been quick to adopt magnetic resonance imaging (MRI) in the search for brain pathology in psychiatric disorders, the clinical utility of MRI is only now being well defined. 2. Numerous past computerized tomography or post-mortem tissue reports in patients with schizophrenia, affective disorders, dementia, autism, and many other psychiatric illnesses have suggested neuroanatomical substrates for these disorders. However, these techniques have several limitations. 3. The advent of MRI has allowed a high resolution method for examining the brain in vivo. It is important for psychiatrists to know the clinical utility, and the advantages/disadvantages of MR compared with CT. 4. In this article, the authors review the relevant MR literature with some illustrative cases where MRI provided clinically useful information. Recent advances in MRI technology that will have future applications in psychiatry are also discussed.

Aged↗