Hypothermia protects brain function in acute carbon monoxide poisoning

The role of body temperature in the morbidity and mortality resulting from acute severe carbon monoxide (CO) poisoning (2400 ppm CO, 90 min) was investigated using an unanesthetized animal model. Modified Levine prepared female rats (left common carotid artery and jugular cannulated) displayed a lower rate of recovery period (4 hr) re-warming, and an increased mortality rate and behaviorally-assessed neurologic index (NI) compared to normal rats. This indicated their greater susceptibility to CO hypoxia, although the degree of CO-induced hypothermia was the same in both groups. The whole-body cooling of Levine rats to a similar extent prior to CO exposure increased somewhat the post-CO re-warming rate, and marginally decreased NI and mortality during CO exposure (in-CO). In contrast, maintenance of constant body temperature by external heating during CO exposure resulted in a negative post-CO re-warming rate and sharply increased NI and in-CO mortality. Normal euthermic rats were much less severely affected by CO. The results suggest that hypothermia, whether CO-induced or produced by prior cooling, provides measurable protection of brain function during acute severe CO poisoning, and that maintenance of body temperature increases in-CO mortality and interferes with ability to thermoregulate and increases NI in survivors.     

Zinc, copper, manganese, and iron balance of parenterally fed very low birth weight preterm infants receiving a trace element supplement

To evaluate a pediatric trace element supplement (Ped-El, Pharmacia) 18 metabolic balance studies were completed in 13 infants (mean birth weight 909 +/- 67 g, x +/- SEM; mean gestational age 27.2 +/- 1 weeks) who received total parenteral nutrition. The supplement supplied 40 micrograms/kg/day of zinc resulting in negative retention of 226 micrograms/kg/day. Copper infused at 20 micrograms/kg/day led to a positive retention of 8 micrograms/kg/day and an increase in serum Cu (p less than 0.05) not related to Cu intakes. Manganese infused at 40 micrograms/kg/day was nearly all retained (88 +/- 16% retention). Iron infused at 120 micrograms/kg/day led to a positive retention of 93 micrograms/kg/day. Although plasma ferritin and percent transferrin saturation were elevated, only plasma Fe values were correlated with Fe intake. This trace element supplement does not appear suitable for very low birth weight preterm infants.     

Shoulder instability: impact of glenohumeral arthrotomography on treatment

We used arthrotomography to study the glenoid labrum in 114 patients. Sixty-nine of the patients had anatomic instability of the shoulder (including recurrent dislocation and subluxation of the shoulder), and 45 patients had functional instability of the shoulder (denoted by chronic pain, clicking of the joint, and the sensation that an unstable condition exists without the objective signs of it). Labral tears were revealed arthrotomographically in 86% of the patients with anatomic instability, while only 40% of the patients with functional instability had labral abnormalities, and these were primarily of minor severity. Fifty-six patients (44 of whom had anatomic instability; 12, functional instability) required surgery. The surgical findings were correlated with the arthrotomographic findings, and no false-positive results were revealed. However, arthrotomography demonstrated only part of the pathologic condition of two patients. These results confirm that there is a strong correlation between labral pathologic conditions and anatomic instability of the shoulder. Arthrotomographic studies have a great impact on the selection of therapy in cases of both anatomic and functional instability of the shoulder.     

Cardiovascular, metabolic and neurologic effects of carbon monoxide and cyanide in the rat.

Levine-prepared, female Sprague-Dawley rats were used to investigate the effects of carbon monoxide (CO) and cyanide (CN) on heart rate, blood pressure, hematocrit, body temperature, blood glucose, lactate, and neurologic function. Rats were exposed to either 2400 ppm CO, 1500 ppm CO, 4 mg/kg NaCN, or both 1500 ppm CO and 4 mg/kg NaCN for 90 min, followed by 4 h of room air recovery. Following exposure to 2400 ppm CO, rats exhibited a significant bradycardia which normalized by 2 h of recovery. All groups exhibited an initial hypotension which was either maintained or exaggerated during exposure in all but the rats exposed to CN, and which returned to pre-exposure values by 90 min. All groups experienced a significant hypothermia during the exposure period, with those in the 1500 ppm CO or the CN returning to initial values over the recovery period. The only significant change in hematocrit was due to 2400 ppm CO (4.1% increase). During exposure, all groups experienced an initial surge in glucose concentration which was maintained in all but rats exposed to 2400 ppm CO. The greatest hyperglycemic response resulted from the combination of CO and CN, whereas 2400 ppm CO produced the smallest. CN alone produced no significant rise in lactate concentration. However, lactate concentration in all other groups was significantly elevated during the exposure period, returning to initial values by 4 h of recovery. Lactate concentrations and neurologic deficit in rats exposed to 1500 ppm CO, when added to those rats treated with CN, closely approximated the lactate and neurologic deficit of the combination treatment. Neurologic deficit was greatest in rats exposed to 2400 ppm CO. While in most cases the responses of the rats to CO and CN differed whether the substances were administered alone or in combination, a synergistic relationship is not suggested. An additive or less than additive relationship is more likely.     

Bremsstrahlung imaging using the gamma camera: factors affecting attenuation.

Quantitative imaging of bremsstrahlung from pure beta emitters is proposed as a means for in vivo management of antibody therapy. The method involves the use of high-energy collimation, an empirically selected broad photon energy window to enhance detector sensitivity, and a Wiener restoration filter to compensate for system blur. The measured and filtered data were obtained for an idealized scattering medium and isolated spherical sources. An effective linear attenuation coefficient of about 0.13 cm-1 was determined from the raw image data of 32P. A coefficient of 0.14 cm-1 was determined after the images were restored using the Wiener filter. The measured attenuation was not significantly dependent on the size of the region of interest or the size of the source. Its variation was within the experimental error of measurement (+/- 5%). The measured sensitivity (6 x 10(-6) cps/Bq) was sufficient for imaging therapy doses of 32P or 90Y.     

Glutamate receptors in striatum and substantia nigra: Effects of medial forebrain bundle lesions

We examined NMDA-sensitive [³H]glutamate, [³H]AMPA, [³H]kainate and metabotropic-sensitive [³H]glutamate binding sites in neostriatum and substantia nigra pars reticulata (SNr) in rats after unilateral 6-hydroxydopamine lesions of the medial forebrain bundle. One week after the lesion, NMDA, AMPA, kainate and metabotropic receptors were decreased in the ipsilateral neostriatum, whereas at three months NMDA receptors were increased while AMPA, kainate and metabotropic receptors were not changed. In the SNr at one week, only AMPA and metabotropic receptors were significantly decreased whereas three months after the lesion NMDA, AMPA and kainate binding sites were decreased. The early decrease of excitatory amino acid receptors in the striatum is likely to reflect degeneration of dopaminergic fibers, suggesting that specific subpopulations of excitatory amino acid binding sites are located on dopaminergic terminals.     

CAG repeat number governs the development rate of pathology in Huntington's disease

We compared the number of CAG repeats, the age at death, and the severity of neuropathology in 89 Huntington's disease brains. We found a linear correlation between the CAG repeat number and the quotient of the degree of atrophy in the striatum (the brain region most severely affected in Huntington's disease) divided by age at death, with an intercept at 35.5 repeats. The largest CAG repeat length, therefore, at which no pathology is expected to develop is 35.5. These results imply that striatal damage in Huntington's disease is almost entirely a lineaar function of the length of the polyglutamine stretch beyond 35.5 glutamines multiplied by the age of the patient. Thus, it is predicted that the pathological process develops linearly from birth. Analysis of other measures of striatal function could test this hypothesis and might determine when treatment for CAG repeat diseases should start.