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Biomedical subjects

M Pollay

Publications and source records attributed to M Pollay.

At least 37 records · Page 2Linked to original sources
PubMed1985

Quantitative anatomy of the thoracolumbar epidural space.

Quantitative measurements of the epidural space between T-7 and L-4 were made in the sagittal and coronal planes utilizing x-ray films made after the injection of iodized oil into the epidural space in the low thoracic and upper lumbar areas. These data reveal a 1-mm ventral epidural space and a 2-mm lateral epidural space, with a sawtooth shape to the dorsal epidural space measuring between 1.1 and 2.9 mm at the rostral lamina and between 3.8 and 6.5 mm at the caudal lamina. Additionally, five patients with chronic pain were studied by computed tomography of T-8 to T-12, with confirmation of the sawtooth shape of the dorsal epidural space. Computed tomography showed the measurements of the epidural space at the rostral lamina to vary between 1.3 and 1.6 mm and those at the caudal lamina/interlaminar space to range from 6.9 to 9.1 mm.

Epidural Space↗
PubMed1984

Intraventricular pneumocephalus secondary to subcutaneous emphysema: a case report.

Intraventricular tension pneumocephalus is an unusual complication of surgically treated hydrocephalus. This is a life-threatening complication requiring prompt diagnosis and treatment. A case is presented wherein tension pneumocephalus developed as a result of cervicocranial subcutaneous emphysema in the presence of a ventriculoperitoneal shunt.

Brain Diseases↗
PubMed1983

Neuropsychological functioning in children with shunted uncomplicated hydrocephalus.

A neuropsychological battery was given to a CT-defined group of children shunted for uncomplicated hydrocephalus with estimated normal range IQs. When no other brain anomalies were present, verbal IQ estimates were inferior to age and sex matched controls, but still in the normal range. In the presence of average academic performance and normal range IQ, impairment of neuropsychological functioning in verbal and nonverbal memory, fine motor speed, and visuospatial problem solving was observed. Successful neurosurgical management of hydrocephalus is not necessarily equated with achieving normal neuropsychological functioning.

Cerebrospinal Fluid Shunts↗
PubMed1983

Effect of mannitol and furosemide on blood-brain osmotic gradient and intracranial pressure.

The effect of mannitol (1.0 gm/kg) and furosemide (0.7 mg/kg), alone and in combination, on the blood-brain extracellular fluid and cerebrospinal fluid (CSF) osmotic gradient, elevated intracranial pressure (ICP), CSF and serum osmolality, and urine output was studied in 26 mongrel dogs. Mannitol and furosemide, when used together, produced a greater (62.4% versus 56.6%) and more sustained (5 hours versus 2 hours) fall in ICP than mannitol alone. This correlated with a prolongation of the reversal of the blood-brain osmotic gradient (-3.4 to + 38.5 mOsm/kg) and a rate of urine formation 15 times control values. There was a transient but not significant fall in serum Na+ with the combined treatment, but the arterial pressure did not vary from pretreatment levels. The results from this present study suggest that the distal loop diuretics in a dose of less than 1.0 mg/kg act synergistically with mannitol by causing preferential excretion of water over solute in the renal distal tubule, and thereby sustaining the osmotic gradient initially established by the mannitol infusion. It is possible, but unlikely in the doses used, that the additive effect of furosemide on reducing ICP in the presence of mannitol is due to interference with CSF formation or Na+ and H2O movement across the blood-brain barrier.

Animals↗
PubMed1983

Early management and decision making for the treatment of myelomeningocele.

A program for early selection and treatment of the infant with myelomeningocele was developed at the University of Oklahoma Health Sciences Center in 1977. Over a 5-year period, 69 babies were evaluated, 36 babies were recommended for early vigorous treatment. Of the 33 babies for whom only supportive care was recommended, five were initially treated at the parents' request, two underwent delayed vigorous treatment, one was subsequently treated by "crisis management," one moved and did not return for follow-up, and 24 received only supportive care. All 24 babies died between 1 to 189 days of age (mean 37 days). The involvement of several physicians and paramedical support personnel is considered essential for this approach of early selection and treatment. Continued support and regular follow-up is necessary for any baby who receives only supportive care. Parents retain legal custody. Although ethical concerns make any approach difficult, the method presented is considered to be the best alternative available at this time.

Child, Preschool↗
PubMed1980

Starvation-induced changes in transport of ketone bodies across the blood-brain barrier.

The permeability of the blood brain barrier (BBB) to beta-hydroxybutyrate (beta-HB) was computed in fed and starved (five days) rats by the simultaneous measurement of cerebral blood flow (diffusible indicator method-123I-iodoantipyrine) and brain uptake of 14C-beta-HB (relative to a 3H2O reference). The results from the present study demonstrate that the movement of beta-HB across the BBB in rat is by a carrier-mediated process. During starvation, total movement (carrier-mediated and diffusionary) of this ketone body into brain was observed to be enhanced because of an increase in the diffusionary loss across the cerebral capillary. The calculated transport kinetics also suggest that the beta-HB molecule has a greater affinity for the transport (mediator) protein during starvation, although the maximal rate of uptake by brain due to a carrier processes mediated Vmax is decreased either because there is a smaller quantity of the mediating molecule or because there is trans inhibition by a high cellular concentration of beta-HB or some analog.

Animals↗
PubMed1980

Blood-brain barrier restoration following cold injury.

Cerebral blood flow (CBF), 113mIndium-DPTA, and 14C-glucose extraction were measured simultaneously in rat brain from 2 to 58 days following a thermal insult. In the early stage of a cold induced lesion (2 days), the blood-brain barrier (BBB) was disrupted with resulting leakage and diffusionary loss of both glucose and indium-DPTA. The adjacent, nonnecrotic brain showed similar but more subtle changes. In both areas, CBF was markedly reduced. CBF and augmented loss of glucose and Indium-DPTA continued in the epicenter of the lesion for up to 58 days postinjury while the BBB function in the brain areas surrounding the lesion returned toward normal. These findings were consistent with observation of disruption of BBB activity and of immature brain capillaries during the reparative period.

Animals↗
PubMed1980

Blood-brain barrier: a definition of normal and altered function.

The anatomical component of the blood-brain barrier (BBB) has been shown to be the cerebral capillary. These capillary endothelial cells are connected by continuous tight intercellular junctions and under normal conditions do not demonstrate transendothelial channels or pinocytotic vesicles. The rate that substances penetrate the BBB is related to molecular size, lipid solubility, and the presence of a specific carrier-mediated transport system. This latter mechanism for transendothelial passage is utilized for the movement of a wide variety of biologically important compounds such as sugars, amino acids, and organic acids. In certain pathological conditions, the permeability of the BBB is altered so that normally excluded plasma proteins and fluid enter the brain extracellular space, with the subsequent development of cerebral edema. In other abnormal conditions, alterations in the specialized transport systems operating across the cerebral capillary result in adverse changes in cerebral and neurotransmitter metabolism. An understanding of the unique properties of the BBB and of the changes that occur in pathological conditions has allowed the development of rational therapeutic strategies for a wide variety of diseases of the central nervous system.

Aging↗
PubMed1979

Simultaneous measurement of regional blood flow and glucose extraction in rat brain.

A method has been described which allows the measurement of cerebral blood flow (CBF) and solute transport across cerebral capillary wall in the same regional sample of rat brain. An inert diffusible indicator (iodoantipyrine) was used to measure a blood flow, in mixed gray and white matter, or approx. 1.0 ml/min/g. Using 3H2O as a reference molecule, the flux of [14C]D-glucose into brain was determined at blood glucose concentration levels between 0.1 and 60 mM. In all discrete areas of brain sampled, a consistent Vmax of 1.92 micromol/min/g and a Km of 8.35 mM was found. Glucose extraction by brain was inversely related to CBF, while a direct relationship was noted for glucose clearance.

Animals↗
PubMed1976

Regional transport of phenylalanine across the blood-brain barrier.

In adult rats, using the single-pass brain uptake technique with a tritiated water standard, L-phenylalanine was shown to enter brain across the blood-brain barrier (BBB) by both a saturable and diffusionary process. A kinetic analysis of the data revealed a Michaelis constant (Ka) of 0.42 mM and a Vmax of 35 nmoles g-1 min-1. The saturable component of L-phenylalanine transport was adversely affected by dinitrophenol or or low sodium concentration in the intracarotid injection solution. Intravascular ouabain did not affect transport and only partial inhibition was observed with 1.5 mM L-leucine. It appears that there is no reginonal difference in the capacity of the BBB to move L-phenylalanine from blood to brain. This process is directly or indirectly coupled to sodium movement and is partially dependent on cellular energy.

Animals↗
PubMed1976

Movement of glycine across the blood-brain barrier of the rabbit.

The single pass clearance of glycine from the cerebral capillary bed was measured in the rabbit with the indicator diffusion method. It was shown that glycine was extracted to the same degree as fructose (ca..07). The concentration of glycine injected into the carotid artery was varied some 700-fold without significantly affecting the clearance of this amino acid in transit through the brain. Cross inhibition of the unidirectional movement of glycine was not demonstrable. These present results and most previous studies suggest that this putative neurotransmitter does not cross the blood-brain barrier by a carrier mediated process.

Animals↗