Toward astrophysical turbulence in the laboratory.

Turbulence is a ubiquitous phenomenon in space and astrophysical plasmas, driving a cascade of energy from large to small scales and strongly influencing the plasma heating resulting from the dissipation of the turbulence. Modern theories of plasma turbulence are based on the fundamental concept that the turbulent cascade of energy is caused by the nonlinear interaction between counterpropagating Alfvén waves, yet this interaction has never been observationally or experimentally verified. We present here the first experimental measurement in a laboratory plasma of the nonlinear interaction between counterpropagating Alfvén waves, the fundamental building block of astrophysical plasma turbulence. This measurement establishes a firm basis for the application of theoretical ideas developed in idealized models to turbulence in realistic space and astrophysical plasma systems.

Abnormal lymphocyte profiles and leukotriene B4 status in a patient with Crohn's disease and severe periodontitis.

THIS CASE REPORT DESCRIBES clinical and laboratory findings for a 60-year-old woman with recently diagnosed Crohn's disease and severe generalized periodontitis. Comparison of dental radiographs taken in 1975, in 1983, and at the time of our evaluation in 1986 revealed dramatic progression of alveolar bone loss over that period. Standard laboratory blood tests did not reveal any remarkable significant leukocyte abnormalities, but flow cytometric analysis of lymphocytes revealed a paucity of B cells stained with anti-light chain antibodies, and an increased proportion of T lymphocytes which were dully-stained with anti-CD5 monoclonal antibody. B cell function as determined by in vitro proliferative responsiveness to anti-IgM antibody was only about 50% of that observed with cells from two healthy normal subjects. Serum leukotriene B4 (LTB4) was elevated to 150% of normal values, in spite of the fact that the patient was taking a systemic anti-inflammatory drug which is known to reduce LTB4 levels. The microbial flora was highly mixed and included several putative periodontopathic bacteria. Therapy consisted of oral hygiene instruction, scaling and root planing, mucoperiosteal-flap curettage, extracoronal splinting, and selective extraction of three teeth. The periodontal status improved markedly with therapy. Possible relationships between the patient's immunological status, her Crohn's disease, and the severe periodontal breakdown are discussed.

Transsphenoidal microsurgery for selective removal of functional pituitary microadenomas.

The transphenoidal approach to the pituitary gland is emerging as the safest and most efficacious procedure for the management of pituitary tumors. With the aid of the microscope large tumors producing visual symptoms can be removed and microadenomata producing only signs and symptoms of endocrinopathies can be safely and adequately approached. The procedure is described in this report. The results of its use in 29 patients with selected illustrative case reports are described.

Peripheral nerve injury from implantation of chronic stimulating electrodes for pain control.

Complications of implantable stimulating electrodes for pain control are becoming recognized. We present two cases of peripheral nerve injury related to placement of peripheral nerve stimulating electrodes and discuss the relevant literature.

Experience with dorsal column stimulation for relief of chronic intractable pain: 1968-1973.

Dorsal column stimulators (DCS) have been implanted in 130 patients with various chronic pain syndromes at the University of California, San Francisco, between 1969 and 1973. Preoperative psychiatric evaluation and percutaneous dorsal column stimulation testing were of value in rejecting those patients most likely to have unsatisfactory long-term results with DCS. Best results occurred in patients with phantom limb or peripheral nerve pain and worst results in patients with paraplegic pain, documented arachnoiditis, pancreatitis and arthritis. The need is stressed for careful preoperative selection and for close, prolonged postoperative care in a situation permitting access to multidisciplinary facilities for patient care.

Phantom limb pain. Treatment with dorsal column stimulation.

Good to excellent relief of phantom pain is reported in 5 of 6 patients by the use of dorsal column stimulation. Follow-up periods are 7 to 25 months. One failure occurred despite excellent pain relief; this patient could not tolerate application of the DCS apparatus to his chest wall. The authors review the physiology involved and some less successful series reported by others.