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Biomedical subjects

A B Butler

Publications and source records attributed to A B Butler.

At least 55 records · Page 3Linked to original sources
PubMed1980

An ultrastructural study of the normal synaptic organization of the optic tectum and the degenerating tectal afferents from retina, telencephalon, and contralateral tectum in a teleost, Holocentrus rufus.

The ultrastructure of the optic tectum in the squirrel fish, Holocentrus rufus, has been studied and the normal synaptic organization is described. Synaptic terminals were classified into eight types (S1-S6, F1, F2) by their morphology and synaptic relations. The distribution pattern for each type of terminal was determined by counting the relative number of terminals in each layer. Most S1 terminals are localized in Stratum marginale (SM), whereas S2 terminals are most common in Stratum fibrtosum et griseum superficiale (SFGS). S3, S4, S5, F1, and F2 terminals are limited mainly to SFGS and Stratum griseum centrale (SGC). S6 terminals are most frequently seen in SGC and Stratum griseum periventriculare (SPV). In order to determine the origins of the various types of synaptic terminals in the optic tectum, the telencephalon, eye, and optic tectum were removed unilaterally and areas of resultant degeneration examined. Electron microscopic observations show that nearly all S2 terminals in SFGS of the contralateral optic tectum degenerate after eye enucleation, whereas some S4 terminals in SFGS and SGC exhibit degenerative changes after removal of the ipsilateral telencephalon. Unilateral ablation of the optic tectum was associated with degenerative changes in occasional S5 terminals within SGC of contralateral optic tectum. All experiments resulted in some increased electron density of S3 and F terminals, some of which were identified as F2 terminals. The possible origins of S1 and S6 terminals, which were not altered in the present experiments, are discussed.

Afferent Pathways↗
PubMed1980

Projections of the optic tectum in the longnose gar, Lepisosteus osseus.

Efferent projections of the optic tectum were studied with the anterograde degeneration method in the longnose gar. Ascending projections were found bilaterally to 3 pretectal nuclei -- the superficial pretectal nucleus, nucleus pretectalis centralis and nucleus pretectalis profundus -- and to a number of targets which lie further rostrally -- the central posterior nucleus, dorsal posterior nucleus, accessory optic nucleus, nucleus ventralis lateralis, nucleus of the ventral optic tract, rostral part of the preglomerular complex, suprachiasmatic nucleus, anterior thalamic nucleus, nucleus ventralis medialis, nucleus intermedius, nucleus prethalamicus and rostral entopeduncular nucleus. Projections of the tectum reach the contralateral side via the supraoptic decussation and are less dense contralaterally than ipsilaterally. Descending projections resulting from tectal lesions include: (1) a tectal commissural pathway to the core of the torus longitudinalis bilaterally and the contralateral tectum and torus semicircularis; and (2) a pathway leaving the tectum laterally from which fibers terminate in the ipsilateral torus semicircularis, an area lateral to the nucleus of the medial longitudinal fasciculus, lateral tegmental nucleus, nucleus latealis valvulae, nucleus isthmi and the reticular formation. A component of this bundle decussates at the level of the lateral tegmental nucleus to project to the contralateral reticular formation. On the basis of comparisons of these findings with the pattern of retinal projections in gars and other data, it is argued that the nuclei previously called the lateral geniculate and rotundus in fish are not the homologues of the nuclei of those names in land vertebrates but are rather pretectal cell groups. The overall organization of both retinal and tectal projections in gars is strikingly similar to that in land vertebrates; at present, the best candidate for a rotundal homologue is the dorsal posterior nucleus.

Animals↗
PubMed1980

Algorithm-directed triage of pediatric patients. A prospective study.

An Army corpsman used physician-written triage algorithms to rate the urgency of the chief complaints of 2,000 pediatric outpatients. His ratings agreed with subsequent ratings by physicians in 84% of cases. The corpsman assigned a higher care urgency classification in 15% of cases and a lower classification in only 1.2% of cases. No danger to patients resulted from the algorithm-directed screening. Use of a "nonprofessional" as a triage agent spares the pediatrician, pediatric nurse practitioner, and nurse for providing health care. With increasing use of acute care facilities by patients without appointments, physician-written algorithms allow triage agents who lack formal medical training to determine safely the need for care of patients.

Allied Health Personnel↗
PubMed1980

Language-induced seizure. A case of cortical origin.

After anastomosis of the superficial temporal to the middle cerebral artery, partial motor seizures referable to the left inferior motor strip and Broca's area developed in a 48-year-old man. These seizures were readily induced by attempts to speak, to read silently or aloud, and to write. The seizures were not induced by simple movements of the ocular, facial, jaw, throat, and extremity muscles, primary sensory stimuli, or higher intellectual function such as calculation. The patient had nonfluent dysphasia, but he had no comprehension disorder. A clear focal onset of electrographic seizures was recorded maximally at the left temporal region on reading aloud and at the left central area on writing. The cerebral evoked potentials were mildly abnormal on the affected hemisphere. This case shows cortical onset of language-induced seizure.

Action Potentials↗
PubMed1980

Donor artery changes following anastamosis.

By arteriographic study the authors find there is marked enlargement in diameter of the donor artery and a significant increase in blood flow following superficial temporal-middle cerebral anastamosis.

Cerebral Angiography↗
PubMed1979

Interlaminar connections of tree shrew visual cortex.

The intracortical projections of neurons in layers II and upper III of tree shrew visual cortex were studied after terminal lesions in the supragranular layers of area 17. Examination for terminal degeneration was made using ultrastructural techniques. The majority of degenerating terminals were found in layers V and, to a lesser extent, VI, and were presynaptic to neural profiles in the following distribution: 80.5% on spines of small to medium size dendrites, 19% on dendrite shafts, and less than 1% on neuronal perikarya. Degenerating axons coursed in vertical bundles through layers III, IV, V and VI. These findings are similar to those previously described in rat visual cortex.

Animals↗
PubMed1979

Clearance of macromolecular and particulate substances from the cerebrospinal fluid system of the rat.

Arachnoid villi in the intracranial dural sinuses constitute the principal sites for absorption of proteins and particulates from the cerebrospinal fluid (CSF) system. Although arachnoid villi in the rat are morphologically less complex than those found in other mammals, their resistance to CSF outflow, as assessed by a graded series of contstant flow manometric infusions, is similar to that found in other species. Moreover, inulin and polystyrene beads, when infused into the spinal subarachnoid space of rats, are rapidly cleared from the CSF system into intracranial dural sinuses. Inulin appeared in sinus blood 3 minutes after onset of infusion and reached concentrations 26 times greater than those found in the systemic circulation; particulate matter in the form of 0.5 micrometer polystyrene beads showed similar efflux characteristics. Hence, the CSF system of the rat is functionally similar to that found in other mammalian species, with arachnoid villi constituting a major efflux route for clearance of macromolecular and particulate substances.

Absorption↗
PubMed1979

Primary cerebellar nocardiosis. Report of two cases.

The authors describe two cases of primary cerebellar nocardiosis. Confinement of Nocardia abscesses to a localized, accessible portion of the central nervous system should favor surgical cure of this aggressive and often fatal disease. In our two cases multilocularity, tenuous encapsulation, and proximity to the brain stem prevented complete primary excision. Nevertheless, the infections were effectively treated by intensive postoperative antibiotic therapy and, in one case, a second operation to excise the residual abscess. The need for the latter was suggested by the results of sequential computerized tomographic brain scans that were used to monitor the response to antibiotic therapy. In the absence of any apparent extracranial focus of infection and any overt condition that might impair immunological competence, nocardiosis is likely to be omitted from the preoperative differential diagnosis of a posterior fossa space-occupying lesion.

Adult↗
PubMed1978

Regulation of intracranial pressure in rat, dog, and man.

Intracranial resistance and compliance were assessed in the cerebrospinal fluid system of rat, dog, and man by means of low-volume, short-duration infusions of artificial CSF into the subarachnoid space. A family of pressure/time response curves was obtained for each species: at low flow rates, steady-state pressure elevations were associated with normal neurological function; at high flow rates, rapid linear pressure elevations were associated with marked neurological dysfunction. From these curves a mathematical model was developed which describes transport and pressure-dependent valvelike characteristics of the CSF outflow resistance. This resistance shows a progressive phylogenetic change in rat, dog, and man which increasingly enhances the species' abilities to vent fluid from the intracranial cavity into the venous circulation. Arachnoid villi appear to be the major structures modulating sustained, nonlethal elevations of intracranial pressure.

Animals↗
PubMed1978

Intracranial pressure regulation: a comparative model of cerebrospinal fluid systems.

A comparative model of the cerebrospinal fluid (CSF) system in rat, dog and man was derived from manometric data using low volume, short duration infusions into the subarchanoid space in order to describe the mechanisms governing intracranial pressure dynamics. The mathematical model indicates that steady-state elevations of intracranial pressure are regulated primarily by a nonlinear, pressure dependent outflow resistance to CSF reabsorption. While the form of the resistance relationship is similar for the three species tested, differences in the magnitude of CSF outflow parameters are apparent. Model stimulation on a digital computer suggests that parameter changes within the resistance relationship can have a profound effect on the intracranial pressure. In contrast, intracranial compliance acts only to buffer transient changes in volume prior to the establishment of steady-state CSF pressures.

Animals↗
PubMed1977

Interlaminer connections of rat visual cortex: an ultrastructural study.

Thermal lesions were made in layers I, II, and upper par of layer III of rat visual cortex. The distribution of degenerating axons and axon terminals in layers IV, V, and VI was studied using electron microscopic techniques. Following supragranular thermal lesions, the majority of degenerating axon terminals were found in layer V, with extension into the adjacent part of layer VI. Neural profiles postsynaptic to degenerating axon terminals were found in these layers in the following distribution: 81.7% on spines of small to medium size dendrites; 18.2% on dendrite shafts; and less than 1% on neuronal perikarya. Few degenerating terminals were found on or near apical dendrites. Degenerating terminals were identified on shafts of stellate-type dendrites found in upper part of layer V. Degenerating axons oriented parallel to the cortical surface were found most often in deep layer IV and upper layer V. Degenerating axons were also seen in axon bundles coursing vertically through layer IV. Approximately 10% of the terminals within a grid square have undergone degeneration; no clustering of degenerating terminals was found in vertical or transverse sections through layers V and VI. We suggest that most axon terminals arising from pyramidal neurons in layers II and upper III synapse with spines and shafts of dendrite branches originating from pyramidal neurons in layer V and perhaps VI.

Animals↗