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R J Kosinski

Publications and source records attributed to R J Kosinski.

14 recordsLinked to original sources
PubMed1989

Survey of noncortical afferent projections to the basilar pontine nuclei: a retrograde tracing study in the rat.

The retrograde transport of the conjugate wheat germ agglutinin-horseradish peroxidase (WGA-HRP) was used in the rat to identify the cell bodies of origin for all subcortical projections to the basilar pontine nuclei (BPN). A parapharyngeal surgical approach was used to allow the injection micropipette to enter the BPN from the ventral aspect of the brainstem and thus avoid any potential for false-positive labeling due to transection and injury-filling of axonal systems located dorsal to the basilar pontine gray. A surprisingly large number of BPN afferent cell groups were identified in the present study. Included were labeled somata in the lumbar spinal cord and a large variety of nuclei in the medulla, pons, and midbrain, as well as labeled cells in diencephalic and telencephalic nuclei such as the zona incerta, ventral lateral geniculate, hypothalamus, amygdala, nucleus basalis of Meynert, and the horizontal nucleus of the diagonal band of Broca. Quite a number of cell groups known to project directly to the cerebellum also exhibited labeled somata in the present study. To explore the possibility that such neurons were labeled because their axons were transected and injury-filled as they coursed through the BPN injection site to enter the cerebellum via the brachium pontis, a series of rats received complete, bilateral lesions of the brachium pontis followed 30-60 minutes later with multiple, diffuse injections of WGA-HRP (12-16 placements per animal) throughout the cerebellar cortex. In another series of animals, the massive cerebellar WGA-HRP injections were not preceded by brachium pontis lesions. In the latter cases, each of the cell groups in question that were known to project directly to the cerebellum exhibited labeled somata. However, when the cerebellar HRP injections were preceded by brachium pontis lesions, each of the cell groups in question continued to exhibit labeled somata in numbers comparable to that observed in the nonlesion cases. This implies that such neurons project to the BPN and the cerebellar cortex and that the axons of these particular neurons do not project to the cerebellum via the brachium pontis.

Afferent Pathways↗
PubMed1989

Collateral branches of cerebellopontine axons reach the thalamus, superior colliculus, or inferior olive: a double-fluorescence and combined fluorescence-horseradish peroxidase study in the rat.

Retrograde double-labeling methods that used two different fluorescent dyes or a fluorescent dye in combination with wheat germ agglutinin horseradish peroxidase were used in the rat to study the collateralization of cerebellopontine fibers to the thalamus, the superior colliculus, or the inferior olive. In cases with combined basilar pontine nuclei and thalamus injections, double-labeled neurons were located in the rostral part of the lateral cerebellar nucleus as well as within the interpositus anterior and interpositus posterior nuclei. These cells are medium to large in size and multipolar-shaped. A much smaller number of double-labeled cells was observed in the combined basilar pontine nuclei and superior colliculus injections. In these cases most of the double-labeled cells were intermediate- to large-sized and either bipolar- or multipolar-shaped. Such neurons were distributed throughout the rostrocaudal extent of the lateral cerebellar nucleus, with only a few double-labeled cells located in the interpositus anterior and posterior nuclei. Finally, in the cases with combined basilar pontine nuclei and inferior olive injections, double-labeled cells were located in interpositus anterior and posterior nuclei and the medial portion of the lateral cerebellar nucleus. The double-labeled cells were relatively small in size and most were spindle-shaped. No double-labeled cells were observed in the medial cerebellar nucleus in any of the three injection combinations. Based upon the observation of double-labeled neurons in the deep cerebellar nuclei in each of the three injection combinations involving the basilar pontine nuclei, we conclude that cerebellar projections to the basilar pons arise in part as collaterals of axons that project to the thalamus, superior colliculus, or the inferior olive.

Animals↗
PubMed1988

A double retrograde fluorescent tracing analysis of dorsal column nuclear projections to the basilar pontine nuclei, thalamus, and superior colliculus in the rat.

Injections of the fluorescent dyes Nuclear yellow and True blue were used to determine that the dorsal column nuclei project in collateral fashion to the basilar pontine nuclei (BPN) and the ventral posterolateral nucleus of the thalamus or the BPN and the superior colliculus. Results indicated that relatively few dorsal column nuclear cells project to both the basilar pons and the superior colliculus. In contrast, many dorsal column nuclear cells that project to the BPN also give rise to collateral projections to the thalamus. Thus it is suggested that the latter dorsal column-BPN connections might at least represent in part the anatomical substrate for the electrophysiological demonstration that cerebellar granule cells can be activated at relatively short latency by peripheral tactile receptor stimulation.

Afferent Pathways↗
PubMed1988

A review of recent observations concerning the synaptic organization of the basilar pontine nuclei.

Ultrastructural studies are described that have identified in the basilar pontine nuclei (BPN), the synaptic boutons formed by the corticopontine, cerebellopontine, tectopontine, and dorsal column nuclei-pontine afferent projection systems. In addition, immunocytochemical studies visualized neuronal somata, dendrites, and synaptic boutons that contain immunoreactivity for GABA or the synthesizing enzyme glutamic acid decarboxylase (GAD). Based upon differences in the mode of degeneration and postsynaptic locus of degenerative synaptic boutons in the BPN, it is suggested that two types of cortical neurons and three classes of deep cerebellar nuclear cells project to the BPN. For similar reasons, it appears that two types of neurons in the dorsal column nuclei project to the BPN while only one type of afferent synaptic bouton takes origin from the superior colliculus. Furthermore it appears that the population of BPN neurons projecting to the paramedian lobule receives convergent inputs from the cutaneous periphery and the corresponding region of sensorimotor cortex. Studies employing GAD immunohistochemistry indicate that GABA-ergic neurons and axon terminals are present in the BPN and thus support the suggestion that a local inhibitory interneuron is present within the BPN. Taken together these observations suggest that basilar pontine neurons might play a more active role in the integration of various types of information destined for the cerebellar cortex than has previously been recognized.

Animals↗
PubMed1988

Convergence of cortico- and cuneopontine projections onto components of the pontocerebellar system in the rat: an anatomical and electrophysiological study.

Previous studies in the rat have demonstrated that corresponding peripheral tactile and somatosensory cortical inputs converge within the granule cell layer of various cerebellar lobules and further that descending corticopontine projections from the forelimb sensory cortex (FLSCx) partially overlap with the projection zones of ascending basilar pontine afferents from nucleus cuneatus (NC). The present study employed anatomical and electrophysiological procedures to determine whether cortical and dorsal column nuclear afferent projections converge on pontine neurons that, in turn, provide mossy fiber input to the granule cell layer of the paramedian lobule (PML), i.e., that portion of the rodent cerebellum shown to receive forelimb peripheral inputs. The combination of the orthograde and retrograde axonal transport of horseradish peroxidase (HRP) conjugated to wheat germ agglutinin (WGA) was used light microscopically to demonstrate that orthogradely labeled projections from injections of the FLSCx and NC converged with ponto-paramedian projection neurons that were retrogradely labeled from injections of the PML. These studies were also repeated in conjunction with ablations of either the FLSCx or NC which resulted in the ultrastructural identification of degenerating, as well as WGA-HRP labeled axonal boutons of these pontine afferent projections thus confirming that such projections actually formed synaptic contacts with the retrogradely labeled pontoparamedian projection neurons. Single unit recording analyses of neurons in the ventromedial region of the basilar pons following combined electrical stimulation of various regions of the sensorimotor cortex and the contralateral body surface indicated that approximately 40% of all cells recorded responded to electrical stimulation of corresponding regions of the cortex and periphery, particularly the FLSCx and the forepaw. Natural cutaneous stimuli applied to the forepaw that also elicited responses in these same groups of basilar pontine neurons and were associated with relatively small receptive fields. Taken together, these observations indicate that the previously observed convergence of peripheral and somatosensory cortical inputs within the granule cell layer of the cerebellar cortex may be at least partially organized at the level of the basilar pons.

Action Potentials↗
PubMed1987

Remodeling of dorsal column nuclear efferents to the basilar pontine gray after cortical ablations in newborn rats.

In view of previous reports documenting corticopontine remodeling in response to neonatal cerebral cortical lesions, we examined possible alterations of ascending pontine afferents from the dorsal column nuclei after the same types of neonatal lesion. Two anterograde tracing techniques, autoradiography and the Fink-Heimer silver degeneration method, were combined to facilitate a topographic analysis. The distribution patterns of cuneo- and gracilopontine terminations appeared expanded in response to neonatal sensorimotor cortical lesions, as compared to non-lesioned animals.

Animals↗
PubMed1986

Origin and ultrastructural identification of dorsal column nuclear synaptic terminals in the basilar pontine gray of rats.

The ultrastructural characteristics of HRP-WGA-labeled or degenerating axon terminals arising from neurons in the dorsal column nuclei (DCN) were identified within the contralateral basilar pontine nuclei (BPN) following unilateral HRP-WGA injections or ablations of the DCN. The cells of origin of these projections were also identified through the application of the retrograde tracer HRP-WGA. Two groups of degenerating DCN-pontine terminals were identified. Both formed asymmetrical synaptic contacts with dendritic shafts and/or dendritic appendages of pontine neurons. One group of degenerating terminals contained small, round synaptic vesicles, while the other exhibited a mixture of dense core and pleomorphic vesicles. The former group, which clearly represented the majority of degenerating terminals observed, was interpreted to progress from an early filamentous form of degeneration to a later electron-dense variety and to originate from dorsally located DCN cells distributed primarily at the level of and just caudal to the area postrema. Other DCN-labeled neurons were more ventrally located and were postulated to give rise to those degenerative boutons that contained a mixture of dense core and pleomorphic-shaped vesicles. The present study also identified the cells of origin of two additional projections to the basilar pons: one from cells in the external cuneate nucleus and another from neurons of the medullary reticular formation.

Animals↗
PubMed1986

A comparative topographical analysis of dorsal column nuclear and cerebral cortical projections to the basilar pontine gray in rats.

The somatotopic distribution of dorsal column nuclear projections within the basilar pontine gray was examined in relation to the massive corticopontine projection system that emanates most heavily from motor and somatosensory cortex. The distribution patterns of these two systems were compared by combining autoradiographic and degeneration axonal tracing methods within individual animals. Stereotaxic injections of tritiated leucine (50 microCi/microliter) and lesions by aspiration were made in animals under ketamine hydrochloride anesthesia. The forelimb cortical injections (0.1-0.3 microliter) were centered in either sensory or motor cortical regions as determined by intracortical microstimulation and multiunit recording techniques. Because sensory and motor hindlimb cortical areas overlap extensively in the rat, hindlimb cortical injections (0.1-0.3 microliter) were limited to a single hindlimb sensorimotor cortical region. The corresponding contralateral dorsal column nucleus, cuneatus or gracilis, was then aspirated. A somatotopic distribution of fore- and hindlimb corticopontine fibers were found in discrete regions of the ipsilateral pontine gray. Hindlimb sensorimotor corticopontine fibers distributed caudal to forelimb projections. Similarly, pontine afferents from the dorsal column nuclei terminated somatotopically in the caudal half of the contralateral pontine gray in that gracilopontine fibers distributed caudal to cuneopontine fibers. Within individual animals, partially overlapping terminations were seen from nucleus cuneatus and the forelimb sensory cortical area as well as from nucleus gracilis and the hindlimb sensorimotor cortical area. No overlap existed in the pontine terminations from nucleus cuneatus and the forelimb motor cortical area.

Animals↗
PubMed1986

Certain basilar pontine afferent systems are GABA-ergic: combined HRP and immunocytochemical studies in the rat.

Injection of the tracer substance wheat germ agglutinin-horseradish peroxidase (WGA-HRP) directly into the basilar pontine nuclei using a ventral surgical approach resulted in the labeling of somata in many areas both rostral and caudal to the basilar pons. Certain of the sections that had been reacted for HRP were also incubated in antiserum prepared against glutamic acid decarboxylase (GAD) and processed according to routine peroxidase anti-peroxidase immunocytochemical procedures. Neuronal somata exhibiting both HRP and GAD reaction products were considered to represent GABA-ergic neurons that provide axonal projections to the basilar pontine nuclei. Such double-labeled neurons were observed within the zona incerta, anterior pretectal nucleus, lateral cerebellar nucleus, perirubral area, and the pontine and medullary reticular formation.

Afferent Pathways↗
PubMed1984

Topography of spinal, dorsal column nuclear, and spinal trigeminal projections to the pontine gray in rats.

Several studies using a variety of animals have reported conflicting evidence concerning the distribution, laterally, and indeed the presence of ascending projections to the pontine nuclei. In an attempt to clarify this issue, projections to the pontine nuclei from the spinal cord, dorsal column nuclei, and spinal trigeminal nucleus were investigated with anterograde methods, i.e., the Fink-Heimer technique and/or autoradiography, in Long-Evans black-hooded rats. Results revealed that dorsal column nuclear projections to the contralateral pontine gray terminate predominantly in two regions--one in the caudal aspect of the medial pontine subdivision and another overlapping the ventral and lateral subdivisions. Within the medial and ventral lateral nuclear regions, fibers from nucleus cuneatus primarily terminated more rostrally to afferents from the nucleus gracilis. Spinal trigeminal projections terminated most heavily within the contralateral pontine gray at midpontine levels. Similar to the dorsal column nuclear projections, trigeminal afferents were observed in the medial and ventrolateral subdivisions, although these terminations were rostral and dorsal to areas receiving cuneatus input. Additional projections from the spinal trigeminal nuclei to the contralateral ventral peduncular nucleus were also observed. In comparison to the above-mentioned pontine afferents, both high cervical and midthoracic spinal cord lesions produced a similar pattern of axonal degeneration in the ipsilateral pontine gray which overlapped substantially with gracilis inputs. The observed topographic distribution pattern of ascending afferents to pontine gray confirm and extend previous findings which in general have only briefly described these pathways.

Afferent Pathways↗
PubMed1980

A FORTRAN program for the optimization of radiotherapy treatment planning using the complication probability factor (CPF).

The complication probability factor (CPF) is an objective function, based directly on radiobiological principles and clinical data, for the optimization of radiotherapy treatment planning; it measures the likelihood that a given radiation dose distribution will lead to serious complications in the patient as a result of damage to healthy tissue. A computerized search can be made for that treatment plan which delivers an acceptable tumoricidal dose, yet minimizes the CPF as averaged over the total volume of healthy tissue irradiated. The CPF FORTRAN program, run on a PDP 11/55 in conjunction with a commercially available radiotherapy treatment planning package, is described in detail.

Computers↗
PubMed1980

Antigenic variation in trypanosomes: a computer analysis of variant order.

African trypanosomes can undergo antigenic variation and evade the host immune response. Whether the antigenic variants arise in an ordered sequence or randomly has been in dispute but has not been statistically tested. The coefficient of concordance (W), a statistic designed to detect similarities between sequences of objects, was applied to the literature data. The tendency towards a reproducible order of variants was strong, although in several of the studies the number of experimental animals was so low that no conclusions could be drawn. A computer model was used to determine whether this degree of order could arise with random generation of variants followed by selection. The model simulated a trypanosome clone with 90 possible variants, widely differing variant-specific growth rates, random variant origin and variant eradication by an anamnestic host immune response. Parameters varied were maximum parasitaemia, growth rate differential between 'fast' and 'slow' variants, and parasitologist ability to detect minor variants. Random generation and selection by growth rate alone could not produce the degree of variant orderliness reported in the literature. However, experiments with larger numbers of host animals and direct investigation of variant growth rates and competitive interactions are necessary before the random generation-selection hypothesis can be proven or disproven.

Analysis of Variance↗
PubMed1979

Sampling culturable heterotrophs from microcosms: a statistical analysis.

The contributions of different sources of error in sampling mixed and unmixed bacterial microcosms were evaluated by using analysis of variance. Culturable heterotrophic bacteria from a turbid freshwater impoundment were sampled from 9-liter tanks that were unagitated or mixed with magnetic stirrers or pumps and from dilution bottles that were unagitated or agitated with a mechanical shaker. Axenic cultures of Enterobacter aerogenes were also sampled from manually shaken test tubes. In both agitated and unagitated tanks and in unagitated dilution bottles, dilutions made from the same sampling pipette were significantly different, showing a clumping of bacteria on the scale of millimeters. Also, microcosms within a single experiment differed from one another by a large margin. Dilution mean squares and tank or bottle mean squares were homogeneous for all types of tanks and unagitated bottles, indicating that the gentle mixing provided by pumps and stir bars did not reduce either millimeter scale or intermicrocosm variability over what prevailed in unagitated microcosms. By contrast, the vigorously shaken bottles and test tubes showed no millimeter scale variability. Intermicrocosm variability was undetectable in test tubes and two orders of magnitude less in shaken bottles than in unshaken bottles. When these facts are coupled with the inherent statistical advantage of replicating large rather than small experimental units, it is concluded that sampling error in the enumeration of aquatic bacteria in microcosms will be reduced by using numerous, small, violently agitated microcosms with a minimum of subsampling per microcosm.

Analysis of Variance↗