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Biomedical subjects

K R Krishnan

Publications and source records attributed to K R Krishnan.

At least 55 records · Page 3Linked to original sources
PubMed1999

Disability in geriatric depression.

The authors examined impairment in self-maintenance skills and in instrumental activities of daily living (IADL) among 211 older patients with unipolar major depression. In regression models, self-maintenance impairment was associated with older age, less reported depressed mood, psychomotor retardation, and severe chronic medical illness. IADL deficit was associated with older age, greater severity of depression, less guilt, more apathy, weight loss, greater cognitive impairment, more severe chronic medical illness, less social interaction, lower subjective social support, and greater instrumental support. The authors conclude that efforts to remediate basic skills deficits in depressed older adults should focus on treating comorbid medical conditions; impaired IADL skills in geriatric depressed patients should improve with treatment of depression and medical illness. Clinicians should be aware that substantial IADL impairment may accompany mild cognitive impairment associated with depression in older patients.

Activities of Daily Living↗
PubMed1998

Magnetic-resonance morphometry in patients with major depression.

Magnetic-resonance morphometry performed on 72 patients with major depression compared with 38 control subjects replicated previously reported, statistically significant reductions in the volumes of the caudate (P < 0.03) and putamen (P < 0.05) in depressed patients. Borderline statistical significance was observed for whole-brain (P < 0.07) and frontal volume (P < 0.10) in a subsample of 32 patients matched on age and sex with 32 control subjects, whereas statistical significance was observed for the full sample (P < 0.007 and P < 0.03, respectively). Chronological age was related to volume of the frontal lobes (P < 0.0002), caudate (P < 0.0001), putamen (P < 0.008), thalamus (P < 0.002), cerebellum (P < 0.007), lateral ventricles (P < 0.0001), and ratios of [whole brain]/[whole brain + cerebrospinal fluid (CSF)] (P < 0.0001) and [frontal]/[frontal + CSF] (P < 0.0001). Age of first depressive episode was related to putamen volume after accounting for chronological age (R2= 0.16, P < 0.005), and a correlation of 0.26 (P < 0.04) was observed between caudate volume and global mental status. Results are in accord with previous reports of basal-ganglia abnormalities in depressed patients and support the role of subcortical structures in mediating affective disorder.

Adult↗
PubMed1998

Magnetic resonance imaging correlates of depression in early- and late-onset Alzheimer's disease.

BACKGROUND: Depressive symptoms are frequent complications of Alzheimer's disease (AD). We hypothesized that AD patients with depression would be more likely than nondepressed AD patients to show deep white-matter, subcortical gray-matter, and periventricular hyperintensities on magnetic resonance imaging (MRI). METHODS: In a retrospective study of 31 AD patients, depression was characterized by clinical diagnosis (DSM-III-R major depression, depressive symptoms, or no depression), a clinician-rated depression scale, and informant ratings of premorbid (before memory disorder) as well as current depression using the NEO Personality Inventory (NEO-PI), and related to qualitative and quantitative ratings of MRI hyperintensities. RESULTS: In contrast to reports in nondemented elderly patients, there was no relationship between clinical diagnosis of major depressive episode and hyperintensities; however, clinician-rated depressive symptoms were higher in subjects with large anterior hyperintensities. In the early-onset AD group only, MRI abnormalities were related to greater premorbid depression, and less increase in depression after the onset of dementia, as rated by informants on the NEO-PI. CONCLUSIONS: Results highlight the need to consider early- and late-onset AD separately when assessing relationships between personality and MRI abnormalities, and to consider premorbid personality style when drawing conclusions about the etiology of depressive features seen in AD.

Age of Onset↗
PubMed1998

Quantitative analysis of T2 signal intensities in Alzheimer's disease.

Hypointensities (focal areas of decreased signal intensity) have been reported on T2 weighted magnetic resonance images (MRI) in normal aging and in some neurological disease processes. Increased concentrations of iron have been suggested as one cause of these hypointensities. In Alzheimer's Disease, data suggests that there is both a disruption in iron metabolism as well as the presence of T2 hypointensities. We endeavored to determine if the decreased signal intensities could be quantitatively determined and, if so, in what regions, in an effort to establish a non-invasive biological marker and diagnostic aide. We performed a quantitative analysis of the T2 signal intensities in 13 MRIs from AD patients and 16 age- and sex-matched control subjects. We found that while there were statistically significant differences in the intensities of the putamen and red nucleus, these differences were small. We were unable to detect differences in intensities in a whole slice or the frontal lobe. To our knowledge this is the first quantitative comparison of MRI signal intensities in Alzheimer's Disease.

Aged↗
PubMed1998

Metabolic brain mapping in Alzheimer's disease using proton magnetic resonance spectroscopy.

Alzheimer's disease (AD) is a progressive disorder associated with disruption of neuronal function and neuronal loss. N-acetylaspartate (NAA) is a marker of neuronal content and can be assessed using proton (1H) magnetic resonance spectroscopy (MRS). We utilized 1H-MRS (two-dimensional chemical-shift imaging) to assess amplitudes and areas of NAA, as well as choline moieties (Cho), creatine (Cr) and myo-inositol (mI), in 15 AD patients compared with 14 control subjects. Voxels were classified as predominantly cortical gray matter (CGM), subcortical gray matter (SGM), or white matter (WM). Compared with control subjects, AD patients exhibited decreased NAA/Cho and NAA/Cr amplitudes, whereas an increase was observed in Cho/Cr and in amplitude ratios involving mI. Area ratios were significant in the same direction for NAA/Cho, NAA/Cr, mI/Cr and mI/NAA. No significant effects of tissue type were observed; however, significant group x tissue type interactions were noted for Cho/Cr and mI/Cr amplitudes. Our study confirms that 1H-MRS can identify distinct physicochemical alterations in AD patients, reflecting membrane changes and diminished neuronal function. These alterations can be used as longitudinal markers for the disease.

Aged↗
PubMed1998

Structural neuroimaging and mood disorders: recent findings, implications for classification, and future directions.

Neuroimaging is playing an increasing role in research of affective disorders, with investigators examining both volumetric changes of specific brain structures and vascular changes within white and gray matter. Recent studies have attempted to make clinical correlations between neuroimaging changes in unipolar and bipolar mood disorders. In this review, we focus particularly on those changes that are clinically meaningful. We conclude that there is enough evidence to begin to evaluate inclusion of neuroimaging findings in our mood disorder classification system. To this end, we propose two new mood disorder subtypes, vascular depression and vascular mania. Directions for future research in neuroimaging are then discussed.

Bipolar Disorder↗
PubMed1998

Six-month outcomes for MRI-related vascular depression.

The purpose of this paper is to estimate the relative probabilities of 6-month recovery from an index episode of major depression for subjects with and without MRI-confirmed vascular brain changes. In this cohort study, 57 depressed subjects from the Duke University Mental Health Clinical Research Center (MHCRC) for Depression in Late Life who presented with MRI-related vascular and non-vascular depression were followed for 6 months, and the rates of recovery in the two risk groups were compared. Overall, the recovery rate in this sample was 57.9%. Subjects with MRI-related vascular depression demonstrated outcomes similar to subjects with non-vascular depression (crude RR = 0.67 [0.32, 1.43]). There was a trend that demonstrated that MRI-related vascular depression placed elderly subjects and subjects with first onset of depression after age 40 at increased risk of non-recovery. The study demonstrates overall no significant difference in course between patients with and without vascular depression. It also suggests that patients with vascular depression may have a different course depending on their age and age of onset of the disease.

Adult↗
PubMed1998

Depression and social support in elderly patients with cardiac disease.

BACKGROUND: Depression is common among patients with cardiac disease. A number of psychosocial factors may affect the relationship between physical health and depression. There is evidence from the psychiatric literature suggesting that negative life events and social support are important factors in the development and outcome of depression. It is unknown if these factors are important in the context of depression in medically ill patients. Thus it is important to examine the relationship among social support, negative life events, and the presence of depression in elderly patients with cardiac disease. METHODS: Patients with coronary artery disease were assessed with the Duke Depression Evaluation Schedule for the Elderly. This includes the mood and anxiety disorder section of the Diagnostic Interview Schedule modified for Diagnostic and Statistical Manual of Mental Disorders diagnoses, life events, and multidimensional assessment of social support. Two hypotheses were tested: (1) the number of concurrent negative life events will be higher in patients with coronary artery disease with major depression than those without depression, and (2) social support will be less in patients with major depression than in those without. RESULTS: Presence of major depression was associated with increased negative life events and lowered subjective social support after accounting for age, sex, and race. CONCLUSIONS: The finding that subjective social support and negative life events are related to major depression suggests that even in the context of medical illness, social factors are still important in the development of major depression.

Aged↗
PubMed1998

Psychoneuroendocrinology and brain imaging in depression.

In the past three decades, psychoneuroendocrinologic investigations have generated a great volume of information, particularly in the field of affective disorders, which has formed the basis for designing studies with newer tools such as anatomic and functional imaging. In this article, the authors focus on endocrine imaging in psychiatry and attempt to relate morphometric findings to physiologic neuroendocrine dysfunction in depression.

Anorexia Nervosa↗
PubMed1998

Effect of intermittent urethral catheterization and oxybutynin bladder instillation on urinary continence status and quality of life in a selected group of spinal cord injury patients with neuropathic bladder dysfunction.

OBJECTIVES: A comparative assessment of (i) urinary continence status, (ii) quality of life, and (iii) sexuality in spinal cord injury patients prior to, and during intermittent catheterization with adjunctive intravesical oxybutynin therapy (Cystin: manufactured by Leiras Oy. Helsinki, Finland). SETTING: A hospital, and community-based study of selected adult, male, spinal cord injury patients registered with the Regional Spinal Injuries Centre, Southport. PATIENTS: Seven patients (mean age: 44.3 years) suffering from neuropathic bladder due to suprasacral spinal cord lesion of traumatic aetiology, and well settled in the community in the north-west of England were the subjects of this study. Before commencing the intermittent catheterization regime, these patients were on penile sheath drainage. INTERVENTION: Intermittent urethral catheterization was performed with sterile, single-use Nelaton catheters 5-6 times a day with intravesical instillation of oxybutynin 5 mg in 30 ml. 1-3 times a day for periods ranging from 14 to 30 months. OUTCOME MEASURES: Assessment of urinary continence, sexuality, and quality of life was made (i) at the outset before any intervention, (ii) during intermittent catheterization regime, and (iii) when the patients were using the oxybutynin bladder instillation along with intermittent catheterization. RESULTS: Initially all the seven patients were constantly wearing penile sheaths and leg bags. When these patients performed intermittent catheterization 5-6 times in 24 h, they attempted to discard the penile sheath during the day but they were experiencing mild to moderate urine leak between catheterization. They were compelled to wear penile sheaths during night. Subsequently, five patients took oxybutynin by mouth, but developed an unacceptable degree of side-effects necessitating discontinuation of the medication. Following commencement of intravesical oxybutynin therapy, all of them were able to discard the penile sheaths and leg bags during the day as well as during the night. However, on waking-up after a full night's sleep, three patients found dampness of their undergarments 1-2 times per week. None of the patients experienced side-effects attributable either to the intermittent catheterization procedure, or to the intravesical oxybutynin therapy. The number of episodes of urinary infection requiring antibiotic therapy was 0.08/patient/month. All the seven patients noticed a remarkable improvement in the quality of life because they had achieved a high degree of continence. All the seven patients commented on the improved sense of their own sexuality which was attributed to (i) absence of incontinence episodes, (ii) improved self-image, and (iii) not wearing penile sheaths and leg bags. CONCLUSION: These seven spinal cord injury patients achieved socially acceptable continence with improved quality of life, and enhanced sexuality with the intermittent urethral catheterization regime and intravesical oxybutynin therapy.

Adult↗
PubMed1998

p75 nerve growth factor receptor in the vesical urothelium of patients with neuropathic bladder: an immunohistochemical study.

INTRODUCTION: Nerve growth factor (NGF), apart from its role as a growth factor, appears to be involved in neuroimmune interactions and in tissue inflammation. Low-affinity nerve growth factor receptor (p75 NGFR), if demonstrated in the urothelium, could provide the means for (1) NGF-mediated modulation of the urothelial response to inflammation; (2) NGF-mediated autocrine/paracrine regulation of urothelial proliferation; and (3) p75 NGFR-mediated induction of apoptosis. OBJECTIVES: To investigate the presence of p75 NGFR in the vesical urothelium of patients with neuropathic bladder by immunohistochemical methods. SETTING: A hospital-based study of consecutive, unselected, adult patients of either sex with neuropathic bladder, undergoing procedure on the urinary tract in a Regional Spinal Injuries Centre located in the north-west of England. INTERVENTION: Cold cup biopsies were taken from the trigone of the neuropathic urinary bladder of 26 patients with neuropathic bladder. Immunohistochemical studies were performed using antiNGF-receptor human monoclonal antibody which reacts with the low affinity receptor (p75 NGFR). RESULTS: Both neural and epithelial structures showed positive immunostaining for p75 NGFR. The basal layer of the transitional epithelium showed strongly positive immunostaining for p75 NGFR in all the 26 cases. The luminal layer of transitional epithelium showed varying degree of positive immunostaining in 12 patients. The nerve fibres showed positive immunostaining for p75 NGFR. In many cases, the positively-stained nerve fibres were coursing very close to the basal layer of the urothelium almost entering the urothelium; however, no NGFR-positive intra-epithelial terminals could be seen. The positively-stained single nerve fibres and positively-stained thicker nerve bundles were seen in abundance in the submucosa but they were present in a sparse manner in the muscularis layer. CONCLUSION: The presence of p75 NGFR was demonstrated in the urothelium of neuropathic bladder of all the 26 patients with neuropathic bladder. This observation may have potential therapeutic implications.

Adult↗
PubMed1998

A review of the readmissions of patients with tetraplegia to the Regional Spinal Injuries Centre, Southport, United Kingdom, between January 1994 and December 1995.

Patients with chronic tetraplegia are prone to develop unique clinical problems which require readmission to specialised centres where the health professionals are trained specifically to diagnose, and treat the diseases afflicting this group of patients. An appraisal of the readmission pattern of tetraplegic patients will provide the necessary data for planning allocation of beds for treatment of chronic tetraplegic patients. Hospital records of patients with tetraplegia readmitted to the Regional Spinal Injuries Centre, Southport, UK between 1 January 1994 and 31 December 1995 were analyzed to find out the number of tetraplegic patients who required readmission, reasons for readmission, duration of hospital stay, and mortality among patients readmitted. During the 2-year period, 155 tetraplegic patients were readmitted and 44 of them (28.4%) required more than one readmission (total readmission episodes: 221); these patients occupied 4.5 beds which is equivalent to 11.5% of the total bed capacity of the spinal unit. Among the reasons for the readmissions, evaluation and care of urinary tract disorders topped the list with 96 readmission episodes (43.43%) involving 70 patients; the median hospital stay was 3 days, and 18 patients (26%) required more than one readmission during this period. One hospital bed was occupied by the tetraplegic patients requiring treatment/evaluation of urinary tract disorders. Assessment and treatment of cardio-respiratory diseases was the second most common reason for readmission with 51 readmission episodes pertaining to 27 patients having a median hospital stay of 6 days; 13 patients (48%) were readmitted more than once within this 2-year period. Treatment of cardio-respiratory diseases in chronic tetraplegic patients required 1.2 hospital beds yearly. Only five tetraplegic patients were readmitted for treatment of pressure sore(s); however they had a prolonged hospital stay (median duration: 101 days). Social reasons accounted for 13 readmission episodes concerning nine patients who stayed in the hospital for varying periods (median: 6.5 days; mean: 35 days). Four tetraplegic patients readmitted with acute chest infection expired. An 81 year-old tetraplegic died of myocardial infarction. Urinary sepsis, renal insufficiency, respiratory failure and intra-cerebral haemorrhage accounted for the demise of a 41 year-old tetraplegic patient following surgical removal of a large, impacted stone at the pelviureteric junction. A tetraplegic patient who was admitted with haematuria subsequently underwent cystectomy for squamous cell carcinoma of the urinary bladder; he developed secondaries and expired 5 months later. As more patients with high cervical spinal cord injury survive the initial period of trauma, and as the life expectancy of tetraplegic patients increases, it is likely that greater numbers of tetraplegic patients will be requiring readmission to spinal injuries centre. Although it may be possible to prevent some of the complications of spinal cord injury and hence the need for a readmission, progress in medicine and rehabilitation technology will create additional demands for readmissions of chronic tetraplegic patients in order to implement the newer therapeutic strategies. Thus a change in the pattern of readmission of chronic tetraplegic patients is likely to be the future trend and this should be taken into account while making plans for providing the optimum care to chronic tetraplegic patients.

Adult↗
PubMed1998

Long-term survival in spinal cord injury: a fifty year investigation.

The aims of this study were to examine long-term survival in a population-based sample of spinal cord injury (SCI) survivors in Great Britain, identify risk factors contributing to deaths and explore trends in cause of death over the decades following SCI. Current survival status was successfully identified in 92.3% of the study sample. Standardised mortality ratios (SMRs) were calculated and compared with a similar USA study. Relative risk ratio analysis showed that higher mortality risk was associated with higher neurologic level and completeness of spinal cord injury, older age at injury and earlier year of injury. For the entire fifty year time period, the leading cause of death was related to the respiratory system; urinary deaths ranked second followed by heart disease related deaths, but patterns in causes of death changed over time. In the early decades of injury, urinary deaths ranked first, heart disease deaths second and respiratory deaths third. In the last two decades of injury, respiratory deaths ranked first, heart related deaths were second, injury related deaths ranked third and urinary deaths fourth. This study also raises the question of examining alternative neurological groupings for future mortality risk analysis.

Adolescent↗
PubMed1998

Recurrent bilateral renal calculi in a tetraplegic patient.

An 18-year-old male developed C-5 complete tetraplegia following a motor-cycle accident in May 1975. The neuropathic bladder was managed by an indwelling urethral catheter. He developed recurrent episodes of urinary infection with Proteus species. In September 1975, an X-ray of the abdomen revealed small calculi in both the kidneys. In July 1976, he underwent transurethral resection of the bladder neck and division of the external urethral sphincter; subsequently, he was put on a penile sheath drainage. He continued to suffer from repeated episodes of urinary tract infection with Proteus, Providencia, and Pseudomonas species, and he was treated with antibiotics. In 1980, intravenous urography (IVU) showed two large stones in the left kidney with marked caliectasis. The IVU performed in 1984 showed an increase in the size of the calculi in the left kidney which was grossly hydronephrotic. There were clusters of small calculi in the right kidney. The left renal calculi were treated by percutaneous lithotripsy in two sessions. In 1988, an X-ray of the abdomen revealed staghorn calculus in the right kidney and recurrence of stones in the left kidney. The staghorn calculus in the right kidney was treated by percutaneous nephrostolithotomy in two sessions. In 1991, he was admitted with acute urinary infection. IVU showed a stone in the pelviureteric junction with no excretion of contrast in the left kidney. Percutaneous nephrostomy drainage was established followed by left percutaneous nephrostolithotomy. In 1992, he was found to retain large amount of urine in the bladder; subsequently, his mother was taught to perform regular intermittent catheterisations. In 1995, he was admitted with acute urine infection. Abdominal X-ray revealed recurrence of large stones in both kidneys. With multiple sessions of Extracorporeal Shockwave Lithotripsy (ESWL), about 80% clearance was achieved on the left side. Right staghorn renal stone awaits treatment. This case shows that recurrent urinary infection in spinal cord injury patients is a predisposing factor for renal lithiasis. These patients require annual urological evaluation. Urinary tract calculi, if detected, should be dealt with promptly to prevent renal damage due to urinary obstruction and urosepsis. Renal calculi can be treated effectively and safely by ESWL in spinal cord injury patients, thus avoiding the need for an invasive procedure. It is essential to achieve low-pressure, adequate emptying of the urinary bladder in patients with spinal cord injury in order to prevent recurrent urinary infection and its sequelae. Social issues involved in the care of a tetraplegic patient play a vital role in the implementation of ideal medical treatment and need to be addressed promptly to avoid any compromise in the quality of medical care.

Adolescent↗
PubMed1998

Neuroanatomic localization of magnetic resonance imaging signal hyperintensities in geriatric depression.

BACKGROUND AND PURPOSE: Increased frequency and severity of signal hyperintensities have been regularly reported in elderly depressed patients compared with normal subjects, however, greater neuroanatomic localization of lesions has been limited. METHODS: T2-weighted MRI scans in elderly depressed patients (n = 35) and normal comparison subjects (n = 31) were assessed for signal hyperintensities in lateralized discrete brain regions. RESULTS: Logistic regression revealed that left frontal deep white matter (P<.005) and left putaminal (P<.04) hyperintensities significantly predicted depressive group assignment. CONCLUSIONS: Findings suggest that greater neuroanatomic localization of hyperintensities than heretofore appreciated may relate to late-life depression.

Aged↗