Structural specificity of sugar transport at the blood-nerve barrier.

The major component of D-glucose transfer across the membranous sites of the blood-nerve barrier (BNB) occurs via a facilitative mechanism at a rate greater than twice the rate of D-glucose metabolism by nerve. To characterize further properties of monosaccharide transport at the BNB, unidirectional transfer constant (K) values were determined in vivo in tibial nerve of anesthetized rats for radiolabeled mannitol, L-glucose, and a series of D-glucose analogs. K values(X 10(-4) mls-1 g-1) equaled 4.

A compartmental analysis of solute transfer and exchange across blood-nerve barrier.

A three-compartment model was derived to analyze solute exchange among plasma, peripheral nerve epineurium, and endoneurium. The model was fit to measured tibial-nerve epineurial and endoneurial contents of [14C]sucrose after intravenous bolus injection of tracer in pentobarbital sodium-anesthetized rats. The transfer constant (K) for tracer at epineurial vessels approximated 1.

Sciatic nerve blood flow response to carbon dioxide.

Sciatic nerve blood flow (NBF) during hypercarbia was examined in unanesthetized decerebrate rats by means of laser Doppler flowmetry (LDF). During inspiration of gas mixtures containing no CO2, followed by either 5, 10 or 20% CO2, arterial pCO2 increased by 13, 18 and 68 mm Hg, respectively. Blood pressure (BP) and the LDF signal, which were measured continuously, increased for 30-40 s following the start of inhalation of CO2 and then decreased.

Permeability changes in blood-retinal barrier of galactosemic rats are prevented by aldose reductase inhibitors.

Permeability-surface-area products (PA) for sucrose at the blood-retinal barrier (BRB) were determined with quantitative in vivo techniques and compared in control rats, rats fed a 50% galactosemic diet, and rats fed a diet containing both galactose and the aldose reductase inhibitor sorbinil. The mean PA +/- SE for controls was 0.656 x 10(-5) +/- 0.

Assessment of the permeability of the blood-retinal barrier in hypertensive rats.

We assessed the permeability surface area products at the blood-retinal barrier and blood-brain barrier to sucrose (molecular weight, 340) and microperoxidase (molecular weight, 2000) following acute hypertension induced by metaraminol in Wistar-Kyoto rats (controls) and during chronic hypertension in spontaneously hypertensive rats. In acute hypertension, the permeability surface area product for sucrose was increased at the blood-retinal barrier and at the blood-brain barrier over control values (p less than 0.02), and the vessels became leaky to microperoxidase.

Quantitative assessment of the permeability of the rat blood-retinal barrier to small water-soluble non-electrolytes.

1. The passive permeability of the blood-retinal barrier (b.r.

Transfer of nonelectrolytes from blood into peripheral nerve endoneurium.

Permeability-surface area (PA) products were determined for the transfer of seven nonelectrolytes across the blood-nerve barrier (BNB) of rat tibial nerve using a quantitative in vivo injection technique. PA values at the BNB for slowly penetrating nonelectrolytes such as urea, mannitol, L-glucose, and sucrose differed by less than threefold from values at the blood-brain barrier in the same animals. Permeability coefficients for transfer across the BNB were calculated assuming both endoneurial capillaries and perineurium contribute to solute flux into endoneurium.

Altered blood-nerve barrier permeability to small molecules in experimental diabetes mellitus.

Permeability-surface area products (PA) were determined with a quantitative in vivo injection technique at the blood-nerve barrier of tibial nerve, and at the blood-brain barrier, in control and streptozotocin-induced diabetic rats. The PA product for [14C]mannitol at the blood-nerve barrier was increased by 100% in diabetic animals, 3.12 +/- 0.

Calcium in rat peripheral nerve during chronic alterations in plasma calcium.

The calcium content in desheathed tibial nerve was compared to that in cerebellum in rats fed diets containing either 0.01% (low), 0.67% (control) or 3.

The pathophysiology of penicillamine-induced myasthenia gravis.

The temporal course and pathophysiology of penicillamine-induced myasthenia gravis were studied in detail in a typical case. Our results suggest that this disorder and idiopathic autoimmune myasthenia gravis share the same essential pathophysiological features, including the presence of anti-acetylcholine receptor (AChR) antibody, serum-induced blockade of AChRs, antibody-mediated accelerated degradation of AChRs, and a resultant quantitative reduction in available junctional AChRs. An initial severe reduction in junctional AChRs was reversed and the patient recovered, both within 8 months of stopping penicillamine.

Distribution of adrenergic innervation of blood vessels in peripheral nerve.

The distribution of adrenergic innervation of microvessels in the extrafascicular and endoneurial compartments of rat tibial nerve was examined with glyoxylic acid-induced and formaldehyde-induced histofluorescence methods. Periarterial and arteriolar adrenergic nerves were present in the epineurium-perineurium suggesting that blood flow in the extrafascicular connective tissue is under neurogenic influence. In contrast, blood vessels in the nerve endoneurium were not associated with histofluorescent nerve fibers.

Facilitated transport of glucose from blood into peripheral nerve.

D-Glucose is the major substrate for energy metabolism in peripheral nerve. The mechanism of transfer of glucose across the blood-nerve barrier is unclarified. In this study an in situ perfusion technique was utilized, in anesthetized rats, to examine monosaccharide transport from blood into peripheral nerve.

Chronic demyelinating polyneuropathy in systemic lupus erythematosus.

Mononeuritis multiplex and acute demyelinating polyneuropathy (Guillain-Barré syndrome) are well known in systemic lupus erythematosus (SLE). Chronic acquired demyelinating polyneuropathy has been reported rarely in SLE. Two young women had monophasic progressive weakness, areflexia, elevated CSF protein, and slow nerve conduction velocities as the first manifestation of SLE.

Atypical CT findings in bacterial meningoencephalitis.

Computed tomography has become a valuable imaging modality in the evaluation and management of most intracerebral infections. We report two cases of intracranial infections with atypical CT findings, and attempt to correlate these findings with the pathophysiology.

Hereditary neuropathy with upper motor-neuron, visual pathway, and autonomic disorders.

A 42-year-old man had progressive distal weakness and muscle atrophy, stocking-type sensory loss, upper motor-neuron and visual pathway lesions, and dysautonomia. Electrodiagnostic tests revealed a generalized sensorimotor peripheral neuropathy that largely involved axons. Low recumbent and upright norepinephrine levels implied a peripheral autonomic defect.

In vitro effects of amphotericin B on growth and ultrastructure of the amoeboflagellates Naegleria gruberi and Naegleria fowleri.

In vitro effects of the polyene antibiotic amphotericin B (AmB) on growth, viability, and ultrastructure of amoeboflagellates of the genus Naegleria were examined. The strains studied were the nonpathogenic Naegleria gruberi EG(B) and the Carter and TY strains of the pathogenic Naegleria fowleri. AmB was amoebicidal at all concentrations used (0.