The contribution of reoxygenation to ischemic brain damage

This study examined the hypothesis that the level of postischemic reperfusion affects the severity of the resulting neuronal necrosis. In rats, tissue PO2% was monitored as an index of flow (reoxygenation) at four cortical sites by chronically implanted platinum electrodes. Twenty minutes of total global cerebral ischemia was followed by 30 min of reoxygenation. The level of reoxygenation was controlled to maintain the PO2 nearly constant at one or more of the cortical electrodes. Tissue from within 400 microns of each of 19 electrode sites among seven rats was evaluated histologically. There was a positive correlation between reoxygenation level and severity of neuronal damage. Perineuronal lucent halo formation, probably representing astrocyte foot process swelling, was negatively correlated with reoxygenation level. This study demonstrates that ischemic neuronal damage was aggravated by increased reoxygenation but that perineuronal swelling, as evidenced by halo formation, was somewhat ameliorated.     

Humoral and cellular immunity following severe head injury: review and current investigations.

Infection is a common and serious complication of severe head injury. Immunocompetence in 25 severely head injured patients was investigated by measuring: (1) delayed-type hypersensitivity (DTH) skin test responses to common antigens; (2) phytohaemagglutinin (PHA) stimulated peripheral blood lymphocyte (PBL): blastogenesis, phenotype expression, and lymphokine production; (3) lymphokine-activated killer (LAK) cytotoxicity, antibody dependent cellular cytotoxicity (ADCC) and natural killer (NK) cytotoxicity; and (4) immunoglobulin and complement levels. The incidence of anergy to DTH skin testing was 100%. There was a decrease in PHA stimulated: PBL blastogenesis (p = 0.002), T-cell expression (p = 0.018), helper T-cell expression (p less than 0.001), interleukin-2 receptor expression (p less than 0.001), interleukin-2 production (p = 0.035) and gamma-interferon production (p less than 0.001). LAK cytotoxicity was depressed following incubation with IL-2 (p less than 0.001). There was no significant decrease in immunoglobulin levels and all acute phase reactants tested increased. The results of this study indicate that the cellular arm of immune response, including lymphocyte activation and cytokine production, is suppressed following severe head injury. The lack of enhancement in LAK cytotoxicity following incubation of PBLs with interleukin-2 suggests that factors other than decreased interleukin-2 production, such as the inherent lymphocyte dysfunction, other soluble mediators or suppressor cells, may be responsible for the reduction in cellular immunity observed following severe head injury.     

Lithium treatment of chronic hair pulling

Ten patients with chronic hair pulling received trials of lithium carbonate of 2 to 14 months' duration. Eight patients demonstrated decreased hair pulling and mild to marked hair regrowth. Three responders experienced increased hair pulling subsequent to discontinuation of lithium treatment. Lithium's effect on hair pulling may be related to its observed benefits in treating aggressivity, impulsivity, and mood instability.     

Cytochrome P-45011 beta in rat brain

The presence of cytochrome P-45011 beta in rat brain was studied by immunohistochemistry using polyclonal rabbit antibodies raised against purified bovine adrenocortical P-45011 beta, which is involved in the steroid 11 beta-hydroxylation and glucocorticoid formation. The results showed that cytochrome P-45011 beta immunoreactivity is selectively localized to the tracts of myelinated fibers throughout the brain. The specificity of immunohistochemical stainings with P-45011 beta antibodies was established by control tests including nonimmune rabbit immunoglobulin Gs and P-45011 beta antibodies absorbed with purified antigen. Western immunoblots of homogenates from different brain areas with P-45011 beta antibodies, together with biochemical enzymatic assays for cytochrome P-45011 beta monooxygenase activity in these homogenates, confirmed the selective localization of this enzyme observed with immunohistochemistry. Cytochrome P-45011 beta and 11 beta-hydroxylase activity were detected in a homogenate from the cortical white matter (brain area rich in myelinated fibers) as in that from the rat adrenal, but were not detectable in a homogenate from the cerebral cortex (brain area poor in myelinated fibers). Furthermore, quantitation of the P-45011 beta bands on the immunoblots by the areal density revealed that the cortical white matter contains approximately 1.4 pmol of cytochrome P-45011 beta/mg of tissue protein, the value of which was about one sixth of the corresponding value estimated in the rat adrenal. This relatively high content of cytochrome P-45011 beta was also reflected in a relatively high level of 11 beta-hydroxylase activity measured in a homogenate of this brain area by biochemical enzymatic assays using [4-14C]-11-deoxycorticosterone.(ABSTRACT TRUNCATED AT 250 WORDS)     

The innervation of the levator veli palatini muscle by the glossopharyngeal nerve

We developed a novel method which enables bloodless exposure of the levator veli palatini muscle in rat in order to investigate the physiological properties of this muscle. The levator veli palatini muscle which is innervated by a branch of the glossopharyngeal nerve showed rhythmic spontaneous movement in rats. Cutting the branch supplying LVP of the glossopharyngeal nerve caused cessation of the spontaneous movement of the levator veli palatini muscle. The spontaneous discharges of the glossopharyngeal nerve were synchronized with those of the phrenic nerve. A mixture of 95% oxygen and 5% room air influenced the efferent discharges from the branch of the glossopharyngeal nerve supplying the levator veli palatini muscle. These findings indicate that the motor nerve supply to the levator veli palatini muscle is the glossopharyngeal nerve, and the levator veli palatini muscle is related to the respiratory system, in particular with inspiration in rats.     

Atrial natriuretic factor--its possible role in the pathogenesis and therapy of arterial hypertension

Using radioimmunoassay the authors investigated the plasma concentration of the immunoreactive atrial natriuretic factor (IR-ANF) and its content in the atria of 4-, 8-, 12-, 16-, and 20-weeks-old spontaneously hypertensive rats (SHR), and compared the results with data obtained in normotensive Wistar-Kyoto rats of the same age. With hypertension accelerating in SHR between the 8th and the 20th weeks of life, IR-ANF content in the atrium gradually decreased, and the plasma IR-ANF concentration increased. The decline in IR-ANF was due to its decrease primarily in the left atrium. Long-term (6-day) administration of synthetic ANF to SHR with fully developed hypertension led to normalization of BP. The results do not support the hypothesis that arterial hypertension in SHR is induced by a primary deficiency of ANF. The changes in IR-ANF in the atria and plasma occur rather as an adaptive and regulatory response to increasing BP. Prolonged administration of ANF to SHR had a hypotensive effect. Therapeutic application of ANF in man depends on the development of oral and long-acting analogues.