Effect of sensory stimuli on single unit activity in the posterior hypothalamus.
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Biomedical subjects
Publications and source records attributed to S Feldman.
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Varicella-zoster virus (VZV) is a cause of serious pneumonias in immunosuppressed patients. Although there are reports of residual lung changes in adults following VZV pneumonia, no previous studies of lung function in children following this infection have been done. We studied 11 patients (median age 11 years) who had had VZV pneumonia 1 to 16 years previously. All patients had a primary diagnosis of acute lymphocytic leukemia. Pneumonia was mild in most of the patients: Three had only radiographic evidence of pneumonia and required no supplemental oxygen, and seven required an FiO2 less than or equal to 0.4 for intervals for up to 11 days. One patient had severe pneumonia and required major ventilatory support. Three patients (27%) had significant restrictive defects on follow-up, with total lung capacity 62-69% predicted; and a fourth was abnormal at 1 month follow-up but normal at 16 months. No obstructive defects were noted, although RV/TLC ratios were elevated in three patients and volume of isoflow increased in three. Single breath diffusing capacity was reduced in two patients, but gas exchange was normal in all. No residual radiographic changes were present except in the patient who had severe pneumonia and increased lung markings at 2 months follow-up. All three patients with restrictive changes had other infections before or following VZV, including Pneumocystis carinii pneumonia in two and recurrent, nonspecific pneumonias in the third. We conclude that VZV pneumonia had minimal residual effects on lung function in children with leukemia.
A method for automatic generation of specific FORTRAN programs to control physiological experiments with a computer was developed. The general real-time software package is built into a high level language (MAB = MAcro Basic). From this package, the scientist can automatically generate for him/herself specific programs for controlling his own experiments by a simple procedure. The generated programs contain only the relevant code, adjusted dimensions of arrays, names of parameters, and formatting for printing of tables and graphics for the particular experiment. Therefore, the resulting program is efficient both in terms of memory utilization and in execution time.
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With the purpose of correlating neuroendocrine and neurophysiological data, the effects of stimulating brain areas which have been shown to be involved in the mediation of adrenocortical reponses, i.e. pontine reticular formation (PRF), mammillary peduncle (MP), medial forebrain bundle (MFB), and the suprachiasmatic nucleus (SCN), were studied on unit activity in the mediobasal hypothalamus in the rat. About half of the units recorded responded significantly to one of these modalities by a change in the rate of firing, the MP producing mainly inhibition and SCN facilitation and changes also occurred in the post-stimulus histograms. There was a convergence of different modalities on the same hypothalamic unit. No changes occurred in the time-interval histograms. Stimulating the mediobasal hypothalamus activated synaptically units in the PRF, MP, and MFB but none of them were activated antidromically. The present data demonstrate electrophysiological connections between extrahypothalamic regions participating in adrenocortical regulation and the hypophysiotropic area of the hypothalamus.
In view of the demonstrated role of light and of the suprachiasmatic nucleus (SCN) in the maintenance of circadian rhythms related to endocrine functions and as the mediobasal hypothalamus (MBH) controls neuroendocrine activity, the effects of light and MBH stimulation on the electrical activity of SCN neurons were studied in rats. Out of 253 cells studied in the SCN, 32 cells were antidromically activated, while 65 cells responded orthodromically to MBH stimulation. In another series of experiments out of 95 suprachiasmatic neurons, 11 were antidromically activated by MBH stimulation and 18 different SCN cells responded to continuous light. The present data, which demonstrate photic responses in suprachiasmatic neurons and direct projections from the SCN to MBH, are discussed in view of the current knowledge on the role of the retinohypothalamic tract and the SCN in the control of circadian rhythms.
In view of the role of extrahypothalamic influences on the hypothalamic regulatory activity, the effects of anterior, anterolateral or posterolateral hypothalamic deafferentations and bilateral medial forebrain bundle (MFB) lesions on the spontaneous single cell activity of neurons in the mediobasal hypothalamus (MBH) were studied in rats under urethane anesthesia. While the deafferentation and particularly the anterior cuts reduced the average rates, MFB lesions increased the rate of firing of MBH neurons, and revealed cyclic activity. These data indicate that normally anterior afferents have mainly a facilitatory, while the MFB projections to the MBH have an inhibitory effect on the spontaneous activity. The possible relation of these alterations to neuroendocrine changes are discussed.
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The pharmacokinetics of diatrizoate contrast media were determined following low- (0.7 g I/kg) and high- (1.5 g I/kg) dose intravenous administration. The higher dose of contrast media produced plasma concentrations of iodine which remained approximately twice as high as conventional doses for one hour following infusion. This finding may explain the improved CT images obtained after infusion of higher doses of iodine contrast media. There was no significant long-term change in plasma osmolality noted in venous blood after either dose.
Unilateral macular infarction occurred in a 23-year-old black man with sickle cell hemoglobinopathy (SS), who was already receiving oxygen and hydration treatment for a painful crisis. Visual acuity of 20/200-1 in the affected eye did not improve with 36 hours of "conservative" treatment. Fifteen hours after an exchange transfusion, however, visual acuity started to improve. By 36 hours after transfusion, a visual acuity of 20/40 was achieved, with the gradual return over 8 weeks to 20/20. This case provides strong circumstantial support for the effectiveness of exchange transfusion in sickling maculopathy.