Cerebrovascular regulation in the postural orthostatic tachycardia syndrome (POTS).

Patients with the postural orthostatic tachycardia syndrome (POTS) have symptoms of orthostatic intolerance despite having a normal orthostatic blood pressure (BP), which suggests some impairment of cerebrovascular regulation. Cerebrovascular autoregulation refers to the maintenance of normal cerebral blood flow in spite of changing BP. Mechanisms of autoregulation include myogenic, metabolic and neurogenic vasoregulation.

Hypocapnia and cerebral hypoperfusion in orthostatic intolerance.

Background And Purpose: Orthostatic and other stresses trigger tachycardia associated with symptoms of tremulousness, shortness of breath, dizziness, blurred vision, and, often, syncope. It has been suggested that paradoxical cerebral vasoconstriction during head-up tilt might be present in patients with orthostatic intolerance. We chose to study middle cerebral artery (MCA) blood flow velocity (BFV) and cerebral vasoregulation during tilt in patients with orthostatic intolerance (OI).

A rapid novel derivatization of amphetamine and methamphetamine using 2,2,2-trichloroethyl chloroformate for gas chromatography electron ionization and chemical ionization mass spectrometric analysis.

Amphetamine and methamphetamine are commonly abused central nervous system stimulants. We describe a rapid new derivatization of amphetamine and methamphetamine using 2,2,2-trichloroethyl chloroformate for gas chromatography-mass spectrometric analysis. Amphetamine and methamphetamine, along with N-propyl amphetamine (internal standard), were extracted from urine using 1-chlorobutane.

Autoregulation of cerebral blood flow in orthostatic hypotension.

Background And Purpose: We sought to evaluate cerebral autoregulation in patients with orthostatic hypotension (OH).

Methods: We studied 21 patients (aged 52 to 78 years) with neurogenic OH during 80 degrees head-up tilt. Blood flow velocities (BFV) from the middle cerebral artery were continuously monitored with transcranial Doppler sonography, as were heart rate, blood pressure (BP), cardiac output, stroke volume, CO2, total peripheral resistance, and cerebrovascular resistance.

Spontaneous oxidation of methionine: effect on the quantification of plasma methionine levels.

Plasma methionine (Met), methionine sulfoxide (MSO), and total Met concentrations were determined by reversed-phase chromatography and fluorescence detection after automated precolumn derivatization with an o-phthalic aldehyde mercaptoethanol reagent. Addition of pure, MSO-free L-Met to plasma samples resulted in the anticipated linear increase in plasma Met concentrations, but simultaneously effected a dose-dependent, linear increase in MSO levels. In contrast, the addition of pure L-MSO to plasma samples rendered linear calibration curves for MSO, while the Met concentration remained constant.

Vasculitis confined to peripheral nerves.

The clinical, electrophysiological and pathological features and prognosis of 25 patients with vasculitis selectively affecting the peripheral nervous system were evaluated. Although most patients had a history of mononeuritis multiplex or an asymmetrical neuropathy six out of 25 had a symmetrical neuropathy, both clinically and on neurophysiological testing, by the time of presentation. There were no signs of accompanying systemic vasculitis in any of the patients and serological abnormalities were limited to an elevated erythrocyte sedimentation rate (ESR) in nine out of 21 patients and low titre anti-nuclear antibodies in four out of 20 patients.

Intraneural activated T cells cause focal breakdown of the blood-nerve barrier.

Experiments were conducted to investigate the effect of activated T cells on the blood-nerve barrier (BNB) in experimental allergic neuritis (EAN). T cells reactive to the P2 component of myelin (P2 T cells) and known to cause EAN were injected into the sciatic nerve of Lewis rats. Animals were then given daily intraperitoneal (i.

Activated T cells of nonneural specificity open the blood-nerve barrier to circulating antibody.

Recent studies from our laboratory and by other investigators have shown that autoreactive CD4+ cells specific for peripheral nerve P2 protein have a powerful effect on blood-nerve barrier permeability. In this study we injected CD4+ T cells reactive to a nonneural antigen (ovalbumin) systemically and achieved their accumulation in the tibial nerve of Lewis rats by previous intraneural injection of ovalbumin. Selected rats were given systemic demyelinating antibody (antigalactocerebroside) to provide an indicator of changes in the permeability of the blood-nerve barrier, and the animals were monitored by sequential neurophysiological studies and histology.

Synergy between antibody and P2-reactive T cells in experimental allergic neuritis.

Studies were conducted in experimental allergic neuritis (EAN) to evaluate the possible interaction of cellular and humoral immune mechanisms in the demyelinating process. EAN was induced in Lewis rats by passive transfer of T cells reactive to P2 myelin protein or by active immunisation with whole myelin. Animals were then given systemic antimyelin antibody or control serum and assessed clinically, electrophysiologically and with semiquantitative histological studies.

Preliminary experience with the Hutson-Russell loop cutaneous choledochojejunostomy.

In 1984, the use of a choledochojejunocutaneous fistula was described to allow balloon dilation of benign biliary strictures. Later, the use of the technique to obtain repeated access to the biliary tree in a larger series of patients was reported. The experience provided a foundation for the application of the technique in nine patients at Wilford Hall United States Air Force Medical Center.

Comparison of balloon angioplasty and laser thermal angioplasty in the treatment of femoropopliteal atherosclerotic disease: initial results of a prospective randomized trial. Work in progress.

The authors recently initiated a prospective randomized trial in which results of standard balloon angioplasty were compared with those of laser thermal angioplasty in the treatment of patients with symptoms of femoropopliteal occlusive disease. The data regarding their initial technical success are reported herein. Twenty-five patients with moderate to severe claudication have thus far undergone 27 procedures.

Lymphoceles: percutaneous treatment with povidone-iodine sclerosis.

Although percutaneous procedures have gained a degree of acceptance for treatment of lymphoceles, success rates for aspiration and drainage have been less than optimal. The authors investigated transcatheter sclerosis of pelvic lymphoceles with povidone-iodine as a method to increase the success rate of percutaneous management. Eight patients with a total of nine pelvic lymphoceles were treated with this method.

A multidisciplinary approach to reducing morbidity and operative blood loss during resection of carotid body tumor.

Seven carotid body tumors in six patients were successfully managed using a multimodality approach that included the vascular surgeon, head and neck surgeon and angiographer. Five tumors were managed with preoperative subselective embolization of tumor vessels. Two required vascular reconstruction.