Search PubMed⌕ Search

Biomedical subjects

L R Nelson

Publications and source records attributed to L R Nelson.

71 records · Page 4Linked to original sources
PubMed1978

Numerical grading of clinical neurological status after serious head injury.

A scheme to quantitate the clinical neurological status of the seriously head-injured patient has been devised. The neurological parameters used to quantify the degree of injury are based on neurological functions which have previously been accepted as indicators of the severity of the head injury. A numerical value is assigned to each parameter with emphasis on defining the level of consciousness. The accrued point total of each examination represents the neurological status of the patient at that time. Mean values and standard error from the means are determined from repeated examinations during a single 24 hour period, and are plotted against days after injury. From this graph a line which represents the rate of clinical recovery is determined by least squares analysis. General intensive care nurses were trained to score patients independently; their determinations were found to be in statistical agreement with scores derived from examinations by the attending physicians. The data presented highlight the effects of hypoxaemia in impeding the rate of neurological recovery from a serious head injury. This simple clinical analytical scheme for the quantitative assessment of patients with head injury permits evaluation of the efficacy of various modes of therapy in altering the rate of recovery.

Adult↗
PubMed1977

Second order auditory pathways in the chimpanzee.

Substantial portions of the dorsal, and almost the entire posteroventral and anteroventral (Av) cochlear nuclei were aspirated unilaterally in a chimpanzee. Axonal degeneration was studied by the Fink-Heimer method. The greatest amount of degeneration was followed medially from the region of Av into the lateral part of the trapezoid body. Degeneration also coursed around the superior surface of the restiform body and was traced into the dorsal and intermediate acoustic striae. Within the superior olivary complex, degeneration was distributed to: the ipsilateral lateral superior olive; laterally and medially oriented dendrites of the ipsilateral and contralateral medial superior olivary nuclei respectively (some perisomatic degeneration also was present bilaterally); the contralateral medial trapezoid nucleus; retro-olivary and preolivary cell groups bilaterally. Abundant degeneration passed into the contralateral lateral lemniscus and was distributed largely to its ventral nucleus. The contralateral central nucleus of the inferior colliculus was a major site of termination of ascending second order auditory fibers. The caudal tip of the ipsilateral ventral nucleus of the lateral lemniscus received abundant degeneration, but this diminished rostrally. The ipsilateral inferior colliculus contained a moderate amount of degeneration. A fair number of degenerated second order auditory fibers ascended in the contralateral brachium of the inferior colliculus and were distributed both to the principle and magnocellular divisions of the medial geniculate body. This pathway appears to represent a phylogenetic advance in the brain of the great ape.

Animals↗
PubMed1976

Incorporation of tritiated leucine by axotomized rubral neurons.

Fourteen kittens, 7--10 weeks of age, were injected with [3H]leucine 0.5--24 h before sacrifice 1--30 days after unilateral high cervical rubrospinal tractotomy. Histoautoradiographs of the red nuclei were prepared and counterstained with thionin. Axon reaction, evident histologically 24 h after surgery, was manifested by central chromatolysis or diffuse cytoplasmic chromophobia. Partial reversion toward a normal cytologic appearance was apparent 10--30 days postoperatively. Nucleolar and nuclear shrinkage and cytoplasmic atrophy were conspicuous accompaniments of axon reaction in rubral neurons. Expressed per cell the radioactivity of axotomized rubral nerve cells was consistently less than controls in animals surviving operation from 5 to 30 days. The data indicate that axon reaction in red nucleus is regressive in character and early associated with diminished protein synthesis. The frequently regressive nature of axon reaction in intrinsic neurons, such as those of red nucleus, probably is important in accounting for failure of regeneration of many mammalian CNS fiber tracts after injury.

Animals↗
PubMed1976

The effects of temperature and inhibitors on HCO3-stimulated swelling and ion uptake of monkey cerebral cortex.

In the presence of high concentrations of K+, additions of HCO3- as low as 0.35 mM caused a 23% increase in swelling, and concomitant increases in the chloride content of incubating monkey cerebrocortical slices. The uptake of chloride was accompanied by increased uptake of sodium and was highly temperature dependent, showing a marked activation at approximately 30 degrees C. A similar temperature activation was also found for a Mg2+-dependent, HCO3-stimulated ATPase activity in monkey cerebral cortex, consistent with a possible role for this enzyme in the K+ and HCO3-dependent swelling process and its associated ion movements. K+-dependent, HCO3-stimulated cerebrocortical tissue swelling with uptake of Na+ and Cl- was inhibited by acetazolamide indicating that carbonic anhydrase was also involved. The addition of ouabain also inhibited swelling and K+ and Cl- uptake at low concentrations, but led to increased swelling at higher concentrations ( greater than 10 mum). A similar biphasic effect on swelling was also seen following addition of ethacrynic acid.

Acetazolamide↗
PubMed1975

Ultrastructure of axonal reaction in red nucleus of cat.

Described here are ultrastructural changes in neurons of feline red nucleus exhibiting axon reaction after unilateral rubropsinal tratotomy at the C-2 level and surviving 2 to 65 days. Ultrastructural alterations included neurofilamentous hyperplasia; proliferation of smooth ER; temporary disappearance of organized granular ER with partial substitution by haphazardly arranged, broad cisternal profiles; loss of rosette ribosomes and occurrence of single ribonucleoprotein granules or an intercisternal amorphous density; increased numbers of subsurface cisterns and allied structures, often disposed in stacks; vesiculation and vacuolation of Golgi cisternae; prevalence of autophagic bodies derived in part from Golgi complexes; probable mitochondrial hyperplasia and various qualitative changes in these organelles; an increase in lipofuscin. Dendritic changes paralleled those of perikarya save that proliferation of subsurface cisterns and autophagic bodies was absent. Abnormalities of myelinated axons and boutons occurred and may have originated from retrograde degeneration of cortical neurons induced by lateral funiculotomy. Some perikarya were devoid of axosomatic boutons. Ultrastructural changes varied with the length of postoperative survival and were, at least partly, reversible. Chromatolysis was detectable light microscopically before ultrastructural abnormality appeared. The bearing of transneuronal mechanisms on axon reaction of central neurons and the protective effect of section of axons beyond the site of origin of collaterals are discussed.

Animals↗
PubMed1975

Occlusion of carotid-cavernous fistula with a balloon catheter.

Occlusion of a carotid-cavernous fistula with a balloon catheter appears to be easier and perhaps safer than the widely used trapping procedure. Two cases successfully treated using this technique are reported along with a discussion of the advantages, disadvantages, and possible future improvements in technique.

Adult↗
PubMedDate not supplied

Apparent involvement of opioid peptides in stress-induced enhancement of tumor growth.

Exposure to stress has been associated with alterations in both immune function and tumor development in man and laboratory animals. In the present study, we investigated the effect of a particular type of inescapable footshock stress, known to cause an opioid mediated form of analgesia, on survival time of female Fischer 344 rats injected with a mammary ascites tumor. Rats subjected to inescapable footshock manifested an enhanced tumor growth indicated by a decreased survival time and decreased percent survival. This tumor enhancing effect of stress was prevented by the opiate antagonist, naltrexone, suggesting a role for endogenous opioid peptides in this process. In the absence of stress, naltrexone did not affect tumor growth.

Adenocarcinoma↗
PubMedDate not supplied

Prenatal ethanol and ontogeny of pituitary-adrenal responses to ethanol and morphine.

The development of pituitary-adrenal activity was examined in the offspring of rat dams fed a 5.0% w/v ethanol-containing liquid diet or pair-fed an isocaloric diet, as a nutritional control, from day 8 of gestation to parturition. Serum corticosterone responses of the pups to challenges with ethanol (1.5 g/kg) or morphine (3.0 mg/kg) were determined at 5, 7, 10, 12 and 18 days of age. The pituitary-adrenal axis of normal neonates was activated by the drugs at each age, with a characteristic biphasic developmental pattern in which a trough occurred at day 7. The overall pattern was unaffected by prenatal ethanol exposure or pair-feeding. However, both prenatal treatments intensified the trough. Already on day 5 and also on day 7, corticosterone responses of both the ethanol-exposed and pair-fed offspring to ethanol were significantly lower than responses of normal pups. Additionally, on day 7, ethanol-exposed offspring had significantly lower responses to ethanol than pair-fed offspring and significantly lower responses to morphine than normal pups. Thus, both the prenatal ethanol and pair-feeding treatments suppressed pituitary-adrenal responsiveness of 5 and 7 day-old neonates to the drug challenges. This is in marked contrast to our previous findings for adult prenatally ethanol-exposed offspring whose pituitary-adrenal responses to the same drugs, as well as to other stressors, are consistently enhanced in comparison to pair-fed derived rats, whose responses in adulthood no longer differ from normals.

Animals↗
PubMedDate not supplied

Prenatal exposure to ethanol potentiates morphine-induced hypothermia in adult rats.

We have shown that adult rats, exposed to ethanol in utero, are hypersensitive to the analgesic and pituitary-adrenal activating effects of morphine. In the present experiment, two other responses to morphine, hyperthermia and hypothermia, were examined. Compared to controls, adult rats prenatally exposed to ethanol showed a potentiated hypothermic response to 10 and 30 mg/kg morphine. Hyperthermia elicited by low doses of morphine (1.25-5.0 mg/kg) was not affected by prenatal exposure to ethanol. These results extend our observations suggesting that exposure to ethanol in utero produces long-lasting perturbations in opioid systems. That hyperthermia is not affected, however, indicates that these changes are apparently not ubiquitous.

Animals↗