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Biomedical subjects

K Shulman

Publications and source records attributed to K Shulman.

At least 19 recordsLinked to original sources
PubMed1996

Expression of vascular permeability factor (VPF/VEGF) is altered in many glomerular diseases.

Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), is a potent enhancer of microvascular permeability and a selective endothelial cell growth factor. In normal human kidney, VPF/VEGF mRNA and protein are strongly expressed by visceral glomerular epithelial cells, and VPF/VEGF may be an important regulator of glomerular endothelial cell function. This study examined 47 renal biopsies from patients with a variety of glomerular diseases for expression of VPF/VEGF mRNA and protein by in situ hybridization and immunohisto-chemistry. In many glomerular diseases, VPF/VEGF-expressing cells were decreased in number or absent in areas of focal or global glomerular sclerosis. Decreased numbers of VPF/VEGF-expressing cells in glomeruli were also noted in amyloidosis, diabetes, crescentic glomerulonephritis, and diffuse endocapillary proliferative glomerulonephritis associated with systemic lupus erythematosus. Normally, release of VPF/ VEGF must be under strict control because it is some 50,000 times more potent than histamine as an inducer of microvascular permeability. Damage to visceral epithelial cells in a variety of glomerular diseases has the potential for releasing relatively large amounts of VPF/VEGF locally, leading to increased glomerular permeability. In addition, because VPF/ VEGF is also an endothelial growth factor, the loss of normal, controlled secretion of VPF/VEGF after damage to visceral epithelial cells could lead to important alterations in glomerular endothelial cell function.

Capillary Permeability↗
PubMed1995

Caregiving and dementia: predicting negative and positive outcomes for caregivers.

A sample of 118 caregivers, maintaining relatives with dementia at home, were interviewed and completed questionnaires at initial and follow-up assessment six months later. All dependents received a cognitive assessment. The results of LISREL analysis of the data supported a model of caregiving in which negative outcomes of burden and impaired health reduced positive outcomes of enjoyment of aspects of caregiving. Caregivers with larger social support networks were more satisfied with their support, reducing feelings of impaired health, although as caregiving became more difficult, satisfaction with support decreased. The retrospective perception of the premorbid relationship as more difficult lead to the appraisal of the patient's symptoms as presently being more extensive and increased burden. Women caregivers reported both greater feelings of burden and more aspects of caregiving as enjoyable.

Adaptation, Psychological↗
PubMed1991

UK survey of psychiatric services for the elderly: direction for developing services.

As an important step in health care planning for the elderly, a systematic descriptive study of ten psychogeriatric services was undertaken in the United Kingdom. A definite trend emerged of a reduction in the number of hospital beds as community services developed. Health authorities tended to establish a clinical base in general hospitals rather than in mental hospitals. The recent effect of the rapid growth of the private nursing home sector is also described. Some rough guidelines are provided for the basic resources needed to establish a comprehensive service including one assessment bed and one day place per 1,000 elderly persons; the number of long-stay beds depends on the number of places available in the private sector. While the Canadian health care system differs in some fundamental ways from that in the UK, the principles and guidelines derived from the UK experience may be applied to meet the psychiatric needs of the elderly in Canada.

Aged↗
PubMed1984

Issues in determining financial competence in the elderly.

With the ever-increasing numbers and relative proportion of elderly in the population, physicians are now frequently facing the difficult task of determining the financial competence of vulnerable individuals. The determination of financial competence in the elderly is still a very poorly defined issue. In this paper an attempt is made to clarify the existing law and the physician's legal obligations. The Mental Health Act, Powers of Attorney Act and Mental Incompetency Act, as they relate to a patient's financial competence, are reviewed. The difficulties in the clinical application of these laws are illustrated by two reports of patients referred to the geriatric psychiatry service of Sunnybrook Medical Centre, University of Toronto. Some general principles and practical guidelines are proposed to help physicians deal more effectively with this issue.

Aged↗
PubMed1984

Quantitative evaluation of cerebrospinal fluid shunt flow.

We describe a rigorous method for measuring the flow of cerebrospinal fluid (CSF) in shunt circuits implanted for the relief of obstructive hydrocephalus. Clearance of radioactivity for several calibrated flow rates was determined with a Harvard infusion pump by injecting the Rickham reservoir of a Rickham -Holter valve system with 100 microCi of Tc-99m as pertechnetate. The elliptical and the cylindrical Holter valves used as adjunct valves with the Rickham reservoir yielded two different regression lines when the clearances were plotted against flow rates. The experimental regression lines were used to determine the in vivo flow rates from clearances calculated after injecting the Rickham reservoirs of the patients. The unique clearance characteristics of the individual shunt systems available requires that calibration curves be derived for an entire system identical to one implanted in the patient being evaluated, rather than just the injected chamber. Excellent correlation between flow rates and the clinical findings supports the reliability of this method of quantification of CSF shunt flow, and the results are fully accepted by our neurosurgeons.

Adult↗
PubMed1982

An improved gravimetric measure of cerebral edema.

Significant errors are introduced into the measurement of brain tissue water by the specific gravity technique when the edema fluid contains protein. Protein adds to the tissue solids, increasing the density of the tissue, and masks the proportional increase of brain water. Existing equations relating measured specific gravity and tissue water are not applicable, and a new formula was developed that compensates for the protein component of edema and reduces the experimental error. The new method was applied to the measurement of tissue water in cat brain made edematous by direct infusion of fluids of known composition and volume to test the theory. This technique for improving the gravimetric assessment of brain edema is presented.

Animals↗
PubMed1980

Characterization of clinical CSF dynamics and neural axis compliance using the pressure-volume index: I. The normal pressure-volume index.

The pressure-volume index (PVI) technique was used to measure neural axis compliance, cerebrospinal fluid (CSF) formation (If), and CSF absorption (Ro) in 23 children and 7 adults, all free from intracranial masses, who were undergoing diagnostic or therapeutic procedures. Using bolus manipulation of CSF, If was 0.36 +/- 0.08 ml/min and Ro was 2.8 +/- 0.8 mm Hg/ml/min in both adults and children. PVI, as a measure of neural axis compliance or volume buffering capacity, was 25.9 +/- 3.7 ml for the adults. Measured PVI in the children varied from 8.2 to 30.1 ml but correlated well (r = 0.93) with predicted PVI based on estimates of intracranial and spinal volumes obtained from external measurements. This study provides normal reference data in humans for assessing CSF hydrodynamics and neural axis compliance using the PVI technique in pathological settings.

Adolescent↗
PubMed1980

Bipolar affective disorder in old age.

In a retrospective study of 67 elderly bipolar patients the first manic attack occurred at about age 60, often after a long period from the time of the first affective episode, after which further depressive episodes occurred. This calls into question Perris' criteria for unipolar diagnosis. Among the men, a preponderance of cerebral-organic disorders was found. The evidence for sub-classification of bipolar disorders into secondary or symptomatic manias is discussed. The recurrent nature of the illness in old age stresses the need for further evaluation of lithium prophylaxis.

Age Factors↗
PubMed1980

Biomechanics of brain edema and effects on local cerebral blood flow.

Brain edema represents a disturbance of the volume equilibrium which, in the early stages of formation, must be compensated for by a reduction in other fluid and blood compartments. When this compensation is inadequate, tissue pressure and intracranial pressure increase, the magnitude of which depends on the compliance of the tissue. Tissue pressure gradients develop within the same hemisphere and between hemispheres, but these pressure gradients are transient and dissipate within a few hours after injury. The rate of dissipation is proportional to the product of hydraulic tissue resistance and compliance. These tissue pressure gradients are small in magnitude, less than 15 mm Hg; however, studies with an infusion model of edema in animals show that they are more than sufficient to propel fluid through the parenchyma by a process of bulk flow. The distention caused by the fluid increases the conductance and compliance of the tissue. This biomechanical response favors the dissipation of pressure gradients, and as a result hydrostatic gradients can be sustained only with a continued leakage of fluid from the site of injury. Without a continued extravasation of fluid, equilibration of the tissue pressure to the level of the ICP occurs rapidly. For this reason, the role of hydrostatic gradients in the resorption process may be limited. The development of an infusion model allows more rigid control and simulates the edematous process. Ultrastructural studies of the infusion model have shown that the tissue changes are similar to those reported for vasogenic edema, with the exception that in the infusion model the blood-brain barrier remains intact in the vicinity of the lesion and is not compromised by the mechanical distention of the ECS. The response of the cerebrovasculature to the infusion edema is in contrast to the usual reduction of flow seen after cryogenic injury. The CBF remains constant despite increased tissue water, as confirmed by gravimetric technique. The CO2 reactivity of the vessels in the area of edema is reduced, but the autoregulation to changes in perfusion pressure remains intact. When arterial pressure is raised beyond the limit of autoregulation, the pressure increase of CBF in the edematous area is less than the rise of CBF in normal tissue and suggests a "false autoregulation" caused by an increased tissue pressure. The differences in both the intracranial pressure and CBF response between these two models suggests that other factors must be operative. The cryogenic injury is indeed a traumatic injury to the brain and cannot be simply characterized by the increase in brain tissue water. In some animals a vasomotor paralysis disrupting the vascular compartmental volume and leading to a rapid rise in ICP with eventual reduction of CPP and CBF may explain these differences. Release of vasoactive substances into the ECS is an exciting hypothesis and is an area of investigation ideally suited to the infusion edema process where chemical composition of the fluid can be easily controlled.

Animals↗
PubMed1979

Pulmonary shunt as a prognostic indicator in head injury.

Severe head injury may cause momentary respiratory arrest. Resultant hypoxia would increase cerebral edema and adversely affect the quality of survival. This study examines the effect of hypoxemia on outcome. Pulmonary shunt was calculated as a convenient measurement of respiratory insufficiency in 86 severely head-injured patients who underwent surgery. All samples were taken shortly after induction into anesthesia when controlled ventilation with high inspired-oxygen concentration had been established. In 39 patients who improved, mean pulmonary shunt was 8.9%. Twelve patients who survived with deficit showed a mean shunt of 13.6%, and in 35 patients who died, the mean initial shunt was 15.6%. No significant correlation was found between abnormal chest x-ray findings or the occurrence of hypertension and shunt percentage. The American Society of Anesthesiologists at-risk classification correlated grossly with the outcome. Early pulmonary shunt is a prognostic indicator in severe head injury and should be used in conjunction with the Glasgow Coma Scale in assessing outcome. Despite an apparently adequate respiratory pattern, all patients with severe head injury must be assumed to be hypoxic until proven otherwise. While hypoxemia may prove to be refractory in overwhelming injury, patients who score low on the Glasgow Coma Scale but who have relatively normal oxygen exchange may still survive with little deficit.

Adolescent↗
PubMed1979

Precocious puberty of cerebral origin.

Eighty-two cases of precocious puberty of cerebral origin were reviewed. All shared as a common factor the distortion, compression, or destruction of diencephalic structures. Attempts were made to parallel basic research findings with those derived from human pathology, hoping to gain further insight into the physiopathology of precocious puberty of cerebral origin.

Astrocytoma↗