Null mutations of NT-3 and Bax affect trigeminal ganglion cell number but not brainstem barrelette pattern formation.

Trigeminal ganglion (TG) neurons innervate the grid-like array of whisker follicles on the face of the mouse. Central TG axons project to the trigeminal (V) brainstem nuclear complex, including the nucleus principalis (PrV) and the spinal subnucleus interpolaris (SpVi), where they innervate barrelettes that are organized in a pattern that recapitulates the whisker pattern on the face. Neurotrophin-3 (NT-3) supports a population of TG cells that supply slowly adapting mechanoreceptors in the whisker pad. We examined mice at embryonic day 17 (E17) and on the day of birth (P0) with null mutations of NT-3, Bax, a proapoptotic gene associated with naturally occurring cell death, and Bax/NT-3 double knockout (KO) mutants to determine if: (1) the number of TG cells would be reduced; (2) eliminating the Bax gene would rescue the NT-3-dependent neurons; and (3) the central projections of the rescued axons in the Bax/NT-3 double KO mice would fail to develop the barrelette patterns in the PrV and SpVi subnuclei. In mice at E17, NT-3(-/-) mutants had 65% fewer TG neurons than found in age-matched wild-type (WT) mice, and at P0, the number was reduced by 55% (p < 0.001 for both). Bax null mutant mice at E17 had 132% of the WT number of TG cells (p < 0.001), although the numbers returned to WT levels by P0. Bax/NT-3 double KO mice at E17 had TG cell numbers equal to those seen in WT, but the double KO failed to retain WT TG neuron numbers in P0 mice (39% fewer cells; p < 0.001). In all cases of reduced experimental neuron numbers, and in the E17 Bax(-/-) mice with supernumerary cells, the barrelette patterns in the PrV and SpVi were normal. Only a slight qualitative reduction in overall barrelette field area and clarity of barrelettes were seen. These results suggest that NT-3 is not necessary for barrelette pattern formation in the brainstem.

A phase II study of raltitrexed and gemcitabine in patients with advanced pancreatic carcinoma.

Advanced adenocarcinoma of the pancreas has a very poor prognosis. The aim of this study was to assess the efficacy and tolerability of a combination of the chemotherapeutic agents gemcitabine and raltitrexed. Chemonaive patients with advanced adenocarcinoma of the pancreas were treated with a combination of raltitrexed (3.5 mg m(-2) on day 1 of a 21-day treatment cycle) and gemcitabine (800 mg m(-2) intravenously (i.v.) on days 1 and 8 of a 21-day cycle). Between April 2000 and February 2003, 27 patients were enrolled onto the study. The mean duration of treatment was 11 weeks. Four of 27 patients experienced at least one episode of grade 3 or 4 neutropenia. One patient with grade 4 neutropenia died due to sepsis. Four of 27 patients experienced grade 4 diarrhoea. There was one partial remission (4%) and 12 patients experienced disease stabilisation (44%). The 6-month and 1-year survival rates were 37 and 11%, respectively. Symptomatic benefit occurred in seven (26%) patients. We conclude that a combination of raltitrexed and gemcitabine, using the schedule and doses in this study, cannot be recommended for patients with advanced pancreatic cancer.

Preventing transmission of Sarcoptes scabiei var. suis from infested sows to nursing piglets by a prefarrowing treatment with doramectin injectable solution.

Studies were conducted at swine facilities in Illinois and North Carolina to evaluate the effect of treatment with doramectin injectable solution on transmission prevention of Sarcoptes scabiei var. suis from sows to nursing piglets. Approximately 42 days prefarrowing, 58 mange-free sows were experimentally infested with 200 S. scabiei in each ear. Seven to fourteen days prior to farrowing, 22 sows were given doramectin injectable intramuscularly at a dose of 300 microg/kg of body weight. A total of 21 sows served as untreated controls. Skin scrapings for mite counts and lesion scoring were performed on sows before treatment on day 21, and on either day 35 or 42. Each sow was observed on days 0, 7, 14, 21, 28, and 35 or 42 for the incidence of scratching/rubbing. Skin scrapings, lesion scoring, and observation of scratching/rubbing were performed on the piglets after weaning and at the end of the nursery stage. Geometric mean mite counts of the untreated sows were 0.70 and 0.26 on days 21 and 35 or 42, respectively, and 0.00 for doramectin-treated sows over the same time periods (P<0.05). Lesions scores and the incidence of scratching/rubbing were both higher in the untreated sows as compared to the doramectin-treated sows during the same time periods (P<0.05). Geometric mean mite counts of piglets farrowed by untreated sows were 0.50 and 0.60 after weaning and at the end of the nursery stage, respectively, and 0.00 for piglets from doramectin-treated sows over the same time periods (P>0.05). Lesion scores and the incidence of scratching/rubbing were both higher in piglets from untreated sows as compared to those piglets from doramectin-treated sows (P<0.05). Treating S. scabiei-infested sows with doramectin injectable solution before farrowing eliminated mite infestation and prevented the transmission of S. scabiei to piglets.

trkA modulation of developing somatosensory neurons in oro-facial tissues: tooth pulp fibers are absent in trkA knockout mice.

To investigate the nerve growth factor requirement of developing oro-facial somatosensory afferents, we have studied the survival of sensory fibers subserving nociception, mechanoreception or proprioception in receptor tyrosine kinase (trkA) knockout mice using immunohistochemistry. trkA receptor null mutant mice lack nerve fibers in tooth pulp, including sympathetic fibers, and showed only sparse innervation of the periodontal ligament. Ruffini endings were formed definitively in the periodontal ligament of the trkA knockout mice, although calcitonin gene-related peptide- and substance P-immunoreactive fibers were reduced in number or had disappeared completely. trkA gene deletion had also no obvious effect on the formation of Meissner corpuscles in the palate. In the vibrissal follicle, however, some mechanoreceptive afferents were sensitive for trkA gene deletion, confirming a previous report [Fundin et al. (1997) Dev. Biol. 190, 94-116]. Moreover, calretinin-positive fibers innervating longitudinal lanceolate endings were completely lost in trkA knockout mice, as were the calretinin-containing parent cells in the trigeminal ganglion.These results indicate that trkA is indispensable for developing nociceptive neurons innervating oral tissues, but not for developing mechanoreceptive neurons innervating oral tissues (Ruffini endings and Meissner corpuscles), and that calretinin-containing, trkA dependent neurons in the trigeminal ganglion normally participate in mechanoreception through longitudinal lanceolate endings of the vibrissal follicle.

The vestibular nuclei and vestibuloreticular connections in the mallard (Anas platyrhynchos L.). An anterograde and retrograde tracing study.

The vestibular apparatus provides information about the position and movements of the head. Craniocervical muscles position the head with respect to the upper part of the neck. Motoneurons innervating these muscles are located in the supraspinal nucleus and ventral horn of the rostral cervical cord. Premotor neurons of craniocervical muscles have been found in the medial two-thirds of the medullary reticular formation: the ventromedial part of the parvocellular reticular formation and the gigantocellular reticular formation. In the present study, projections from vestibular nuclei upon craniocervical premotor neurons were investigated using anterograde and retrograde tracers. Vestibulospinal fibers run bilaterally in the medial vestibulospinal tract and ipsilaterally in the lateral vestibulospinal tract. Vestibuloreticular projections are mainly ipsilateral, and originate from the n. vestibularis lateralis pars ventralis and pars dorsalis, and from the n. vestibularis descendens. Terminal labeling is found in the border zone between the parvocellular and gigantocellular reticular formation. These projections show that in addition to direct bilateral vestibulo-craniocervical projections an indirect vestibular pathway to craniocervical motor nuclei exists. The direct pathway probably is the neural substrate for the vestibulocollic reflex, whereas the vestibular projection upon the reticular formation might influence head orientation during various kinds of activities, such as pecking, preening and so on.

Proprioceptive afferents survive in the masseter muscle of trkC knockout mice.

Peripheral innervation patterns of proprioceptive afferents from dorsal root ganglia and the mesencephalic trigeminal nucleus were assessed in trkC-deficient mice using immunohistochemistry for protein gene product 9.5 and parvalbumin. In trkC knockout mice, spinal proprioceptive afferents were completely absent in the limb skeletal muscles, M. biceps femoris and M. gastrocnemius, as previously reported. In these same animals, however, proprioceptive afferents from mesencephalic trigeminal nucleus innervated masseter muscles and formed primary endings of muscle spindles. Three wild-type mice averaged 35.7 spindle profiles (range: 31-41), six heterozygotes averaged 32.3 spindles (range: 27-41), and four homozygotes averaged 32.8 spindles (range: 26-42). Parvalbumin and Nissl staining of the brain stem showed approximately 50% surviving mesencephalic trigeminal sensory neurons in trkC-deficient mice. TrkC-/- mice (n = 5) had 309.4 +/- 15.9 mesencephalic trigeminal sensory cells versus 616.5 +/- 26.3 the sensory cells in trkC+/+ mice (n = 4). These data indicate that while mesencephalic trigeminal sensory neurons are significantly reduced in number by trkC deletion, they are not completely absent. Furthermore, unlike their spinal counterparts, trigeminal proprioceptive afferents survive and give rise to stretch receptor complexes in masseter muscles of trkC knockout mice. This indicates that spinal and mesencephalic trigeminal proprioceptive afferents have different neurotrophin-supporting system during survival and differentiation. It is likely that one or more other neurotrophin receptors expressed in mesencephalic trigeminal proprioceptive neurons of trkC knockout mice compensate for the lack of normal neurotrophin-3 signaling through trkC.

Persistent efficacy of doramectin and ivermectin against experimental infestations of Sarcoptes scabiei var. suis in swine.

Two studies were performed to compare the persistent efficacy of doramectin and ivermectin in swine experimentally infested with Sarcoptes scabiei var. suis. In the Study 1, 84 pigs were treated with doramectin, ivermectin, or saline solution on Day 0. Pigs were then challenged with mites on Days 0, 7, 14, 21, 28, 35, or 42. Weekly evaluations were performed for 5 weeks following challenge with mites. Weekly evaluations included physical examination for clinical signs of sarcoptic mange and collection of skin scrapings for determination of mite counts. In the Study 2, 80 pigs were treated with doramectin, ivermectin, or saline solution on Day 0, and challenged with mites on Days 3, 6, 9, 12, 15, 18, 21, 24, or 27. Weekly evaluations were performed for 6 weeks after challenge exposure. All negative-control (saline-treated) animals in both studies developed evidence of mite infestation. In the Study 1, doramectin prevented mite infestations 7 days longer than ivermectin. Results from the Study 2 indicated that the persistent efficacy of doramectin was 18 days on the basis of mite recovery. This was twice as long as the persistent efficacy of ivermectin, which was 9 days on the basis of mite recovery.

Sensory representation in the cerebellum and control circuits of motion.

The role of the cerebellum in motion and posture control as deduced from the behaviorial effects of lesions has long been known. Subsequent recording and tracing studies in mammals yielded a cerebellar sensory representation featuring 'animalculi', not unlike those seen in the cerebral cortex. This image of cerebellar representation had to be revised with the demonstration of the 'fractured somatotopy' in somatosensory projections (Welker, 1987). A point in case is the trigeminal representation in the mammalian cerebellum, which still lacks a functional explanation. While a fractured somatotopy--if present--has yet to be demonstrated in birds, the topographical details of the trigeminal representation appear to vary considerably between and within both classes. This undoubtedly reflects the variety of functions trigeminocerebellar links subserve in the two classes, but is also indicative of species-specific cerebellar output variation. In this context the importance of cerebellar afferent topography for cerebellar function is discussed.

Immunologic cross-reactivity among various strains of Sarcoptes scabiei.

Varieties of Sarcoptes scabiei from different hosts are highly host specific but they are morphologically indistinguishable. The purpose of this study was to investigate the immunologic cross-reactivity among several varieties of scabies mites using serum from a human scabies patient and from several other species of infested hosts. Homologous and heterologous crossed-immunoelectrophoretic (CIE) analysis of extracts prepared from var. canis (dog) and var. suis (pig) mites yielded very similar antigen profiles. Serum from a human patient infested with var. hominis had circulating IgE that bound to antigens present in extracts prepared from each animal mite variety. Antigen homology was further confirmed by fused peaks on tandem CIE. Additionally, sodium dodecyl sulfate polyacrylamide gel electrophoresis/immunoblot analysis showed that the 2 extracts contained proteins that bound antibody in serum from a var. suis-infested pig, a var. canis-infested dog, var. canis-infested rabbits, and a var. hominis-infested human. The results of this study clearly indicate that different varieties of scabies mites, though host specific, introduce some immunologically cross-reactive molecules into the host. However, each serum from the 4 scabies-infested hosts also contained antibody that was specific for proteins in extract from only 1 variety of mite. These data indicated that each variety of scabies introduced some unique molecules into the host, each strain produced some similar molecules, or both, but different hosts responded immunologically to different sets of these.

Postnatal development of mouse "whisker" thalamus: ventroposterior medial nucleus (VPM), barreloids, and their thalamocortical relay neurons.

We followed developmental changes in "barreloid" thalamocortical relay cell (TCR) dendritic arbors between postnatal day 5 (P5; birth = P0) and adulthood. Single neurons in 150- to 250-microns coronal or oblique slices through the somatosensory thalamus in mice of different postnatal ages were injected with lucifer yellow (LY) under direct visualization. Filled cells in the ventroposterior medial nucleus (VPM) were imaged with a confocal microscope, and rendered and analyzed on a computer workstation with special-purpose software. The whisker representation in the thalamus, as revealed by the pattern of barreloids, was demonstrated by oblique illumination of the slices and/or later cytochrome oxidase (CO) staining. VPM cross-sectional area trebles from P5 to adulthood. Barreloids (single-whisker representations) are well delineated in unstained sections until P10-P11; thereafter, barreloids can only be recognized with difficulty with the CO stain. Thalamocortical relay cell (TCR) somal volumes increase rapidly in the first 2 weeks. The number of primary dendrites does not change, nor does the length of the primary dendritic segments, from P5 to adulthood; however, distal dendritic segments elongate and increase in number. Dendritic arbors are confined on P5 to single barreloids; in adults they extend to adjacent barreloids. The postnatal transformation of dendritic arbors by process growth to adjacent barreloids is mainly completed by P18. A change in the developmental role of these cells, from instructing whisker pattern formation to integrating sensory information from more than one whisker, thus occurs after the whisker pattern in the barrel cortex is established. It coincides with the age at which animals are known to begin exploratory whisking behaviors. The mechanism appears to be by growth and remodeling of distal dendrites rather than by oriented growth and regression, as has been reported for stellate cells in cortical whisker barrels.

Developmental transformation of dendritic arbors in mouse whisker thalamus.

Neurons in slices though the somatosensory thalamus of postnatal day 6 and adult mice were injected with Lucifer yellow. Dendritic arbors on postnatal day 6 are confined to single barreloids (single whisker representations); in adults they are seven times longer, extending beyond their barreloid to adjacent barreloids. The postnatal transformation of dendritic arbors by total process growth and extension to adjacent barreloids suggests a developmental change in the role of these cells from instructing whisker pattern formation to integrating sensory information from more than one whisker.

Prevalence of protozoan infections in darkling beetles from poultry houses in North Carolina.

A study was conducted from November 1990 to February 1992 on the prevalence of protozoan infections in the darkling beetle, Alphitobius diaperinus (Coleoptera, Tenebrionidae), from turkey and broiler houses in the southeastern, northeastern, and central Piedmont regions of North Carolina. Darkling beetles were commonly infected with the eugregarine Gregarina alphitobii, an undescribed species of Gregarina (Eugregarinorida, Gregarinidae) and the neogregarine Farinocystis tribolii (Neogregarinorida, Lipotrophidae). Both eugregarine and neogregarine parasites were present throughout the sampling period. A decreasing trend in percentage infection by eugregarines in darkling beetles from broiler houses was observed through time while percentage infection in turkey houses showed a variable trend. Percentage neogregarine infection exhibited a variable trend with a significant difference in the overall rate of infection in the two types of production houses. Neogregarine infection was higher in the broiler houses than in the turkey houses. Both adult and larval stages of the beetle were infected with the gregarines with higher levels of infection observed in the larval stages. Mixed infections with both types of gregarines were highest in the smallest larvae.

Lucifer Yellow staining in fixed brain slices: optimal methods and compatibility with somatotopic markers in neonatal brain.

Developing dendritic trees often acquire their mature form by selective pruning and reorientation relative to anatomical boundaries, such as cortical 'barrel' walls. Whether similar constraints are imposed on the developing dendrites of subcortical somatosensory neurons is not clear, although it is known that the cells in trigeminal nucleus principalis (PrV) of adult rats have polarized trees. In attempting to resolve this issue we adopted and subsequently optimized a strategy of intracellular injection of Lucifer Yellow into PrV neurons and cerebellar granule cells in slices of fixed brain. Postinjectionally, immunohistochemical staining produced a stabilized image of the Lucifer Yellow injected cells and created the opportunity to apply also an antiserum to J1-tenascin in order to detect whisker-related compartmental boundaries in the neonatal PrV. In 6-day-old rats, most PrV dendrites are polarized and they do not cross tenascin-stained, whisker-related, patch borders. Notable exceptions are dendrites from the minority of PrV cells that have large somata and are responsive to multiple whiskers.

The visual forebrain and eating in pigeons (Columba livia).

The contribution of forebrain structures to the control of visually guided eating behaviors was studied using a technique for reversible 'visual decerebration'. The procedure is based upon the fact that structures in the thalamus and telencephalon receive their visual inputs primarily from the contralateral eye. When the eye contralateral to the ablated hemisphere is occluded, the remaining eye has unilateral access to these structures. When the eye ipsilateral to the ablated hemisphere is occluded, the bird is functionally decerebrate; i.e., visual processing by the remaining eye is restricted to structures caudal to the forebrain. The performance of normal and hemispherectomized subjects under binocular and monocular (unilateral, decerebrate) viewing conditions was compared on tests of ingestive efficiency, identification, conditioned peck localization, and grasping. In normal subjects, differences between right and left eye were not significant on any of these tasks. In hemispherectomized subjects, monocular performance on the first three tasks depended critically upon which eye was occluded. In the decerebrate condition (i.e., when the eye opposite the ablated hemisphere was used) performance on the identification, ingestive efficiency and peck localization tasks was significantly degraded, but grasping was unimpaired. We conclude that the brain structures critical for the visuomotor control of grasping lie caudal to the forebrain.

Organization of the cerebellum in the pigeon (Columba livia): I. Corticonuclear and corticovestibular connections.

The projections of the cerebellar cortex upon the cerebellar nuclei and the vestibular complex of the pigeon have been delineated using WGA-HRP as an anterograde and retrograde tracer. Injections into individual cortical lobules (II-IXa) produce a pattern of ipsilateral terminal labeling of both the cerebellar and vestibular nuclei. The pattern of corticonuclear projections indicates both a rostrocaudal and a mediolateral organization with respect to the lobules and is consistent with a division of the cerebellar nuclei into a medial (CbM) and a lateral (CbL) nucleus. The retrograde experiments indicate that these nuclei receive projections, respectively, from Purkinje cells within medial (A) and lateral (C) longitudinal zones, which alternate with longitudinal zones (B, E) projecting upon the vestibular complex. Purkinje cells in (vestibulocerebellar) lobules IXb-X show only limited projections upon the cerebellar nuclei, but do project extensively upon the cerebellovestibular process (PCV), as well as upon the medial, superior, and descending vestibular nuclei. As the injection site shifts from medial to lateral, there is a corresponding shift in focus of the projection within PCV from areas bordering CbM to those abutting CbL. The topographic organization of corticovestibular projections is less clear-cut than those of the corticonuclear projections. Lobules II-X project upon the lateral vestibular nucleus (anterior lobe) or the dorsolateral vestibular nucleus (posterior lobe). These projections originate from either side of the lateral (C) zone. Projections originating from the medialmost (B) zone are interrupted in lobules VI and VII. The anterior and posterior portions of the lateralmost (E) zone overlap along lobules VI and VII. In addition, the E zone of the anterior lobe is the source of projections upon the medial, the descending, and the superior vestibular nuclei. Projections from the auricle and adjacent lateral unfoliated cortex (F zone) focus upon the infracerebellar nucleus, the medial tangential nucleus, and the medial division of the superior vestibular nucleus. The data suggest that the cerebellar cortex of the pigeon, like that of mammals, may be subdivided into a mediolaterally oriented series of longitudinal zones, with Purkinje cells in each zone projecting ipsilaterally to specific cerebellar nuclei or vestibular regions. For cortical regions exclusive of the auricle and lateral unfoliated cortex, three such zones (A, B, and C) are defined that are comparable in their efferent targets with the A, B, and C zones of mammals. There does not appear to be a D zone in the pigeon. The results are discussed in relation to comparative data on amphibians, reptiles, and mammals.

Organization of the cerebellum in the pigeon (Columba livia): II. Projections of the cerebellar nuclei.

The projections of the deep cerebellar nuclei in the pigeon have been delineated using autoradiographic and histochemical (WGA-HRP) tracing techniques. A medial (CbM) and lateral (CbL) cerebellar nucleus are recognized and CbM may be further partitioned into internal, intermediate, and intercalate divisions. As in mammals, most extracerebellar projections of CbM travel in the fasciculus uncinatus (FU); the rest travel with those of CbL in the brachium conjunctivum (BC). In the pigeon, both of these pathways are bilaterally but primarily contralaterally projecting systems. FU is a predominantly descending tract, with terminations within (1) the vestibular complex, (2) a column of contiguous medial reticular nuclei from pontine to caudal medullary levels; (3) the plexus of Horsley portion of the parvicellular reticular formation, continuing through the nucleus centralis medullae oblongatae, pars dorsalis, into intermediate layer VII of the cervical spinal cord, down to cervical segment 8-9; (4) the lateral reticular nucleus and the paragigantocellular reticular nucleus; (5) the dorsal lamella of the inferior olive. Rostrally FU terminals are found in the locus ceruleus and dorsal subcerulean nucleus. Minimal FU projections are also seen to the motor trigeminal nucleus and the subnucleus oralis of the descending trigeminal system. A small projection from the intercalate division of CbM travels in BC and projects upon the midbrain central grey, the intercollicular nucleus, the lateral tectal periventricular grey, the stratum cellulare externum and, sparsely, upon the dorsolateral thalamus. The bulk of BC originates from the lateral cerebellar nucleus and consists of a massive ascending and a small descending branch. The ascending system projects upon the red nucleus and the dorsally adjacent interstitial nucleus of Cajal and midbrain central grey, the prerubral fields continuing into the stratum cellulare externum, the nucleus intercalatus thalami, the ventrolateral thalamic nucleus, the medial spiriform nucleus, the nucleus principalis precommissuralis, the nucleus of the basal optic root, the nucleus geniculatus lateralis pars ventralis, the dorsolateral thalamus, including the dorsal intermediate posterior, and the dorsolateral intermediate and anterior nuclei. BC also contains axons from the infracerebellar nucleus, which projects upon the trochlear and the oculomotor nuclei. The descending branch of BC distributes to the papilioform nucleus, the medial pontine nucleus, the gigantocellular and paramedian reticular nuclei, and, minimally, the rostral portions of the medial column and ventral lamella of the inferior olive. Taken in conjunction with data on amphibia and reptiles the present findings suggest that the fundamental ground plan of vertebrate cerebellar organization involves a medial and lateral cerebellar nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

Organization of the cerebellum in the pigeon (Columba livia): III. Corticovestibular connections with eye and neck premotor areas.

The connections of the cerebellar cortex with vestibular premotor neurons of the oculomotor and collimotor systems in the pigeon were delineated in experiments using WGA-HRP as an anterograde and retrograde tracer. Putative premotor neuron pools were identified by injections into the oculomotor (mIII) and trochlear nuclei (mIV) and into the most rostral portion of the cervical neck motor nucleus, nucleus supraspinalis (SSp). The retrograde data indicate that ipsilateral projections upon oculomotor neurons arise from the medial portions of the superior (VeS) and tangential (Ta) nuclei. Contralateral projections originate from the infracerebellar nucleus, the interstitial vestibular region including the main (lateral) portion of the tangential nucleus, and from the descending and medial vestibular nuclei (VeD, VeM). These projections were confirmed in anterograde studies that also defined the connections of these vestibular premotor regions with specific subnuclear divisions of the pigeon's "oculomotor" nuclei (mIII, mIV, mVI). The organization of projections from the vestibular nuclei to the pigeon's extraocular motoneurons is similar to that reported in mammals. Projections upon neck premotor neurons arise primarily from neurons in the interstitial region of the vestibular nuclear complex. After injections in SSp, retrogradely labeled neurons were found, contralaterally, in the lateral part of the tangential and superior vestibular nuclei and in the dorsolateral vestibular nucleus (VDL). Ipsilateral labeling was seen in the medial interstitial region (VeM, VeD, and medial Ta). These projections were confirmed in anterograde experiments. With the exception of VDL, vestibular nuclei projecting to neck motoneurons also project to extraocular motoneurons. Thus the infracerebellar nucleus projects exclusively, and the superior vestibular nucleus predominantly, upon oculomotor (mIII, mIV) nuclei; VDL projects predominantly upon the neck motor nucleus, whereas the interstitial vestibular regions (medial Ta, rostral VeD, intermediate VeM) project upon both collimotor and oculomotor neurons. The pattern of retrograde labeling seen in the cerebellar cortex after injections into vestibular premotor nuclei was used to define the projections of specific cerebellar cortical zones upon vestibular eye and neck premotor neurons. Corticovestibular projections upon these regions arise from the auricle and lateral unfoliated cortex, the posterior lobe components of cortical zones B and E, and from the vestibulocerebellum. Each of these cortical zones projects upon components of the vestibular nuclear complex, which are premotor to either oculomotor nuclei or collimotor nuclei. The hodological findings are related to the functional organization of the oculomotor and collimotor systems in the pigeon and compared with the mammalian data.

Effects of sarcoptic mange on lactating swine and growing pigs.

The impact of Sarcoptic mange on sows and on performance of their offspring from birth to slaughter was determined. Sows naturally infested with Sarcoptic mange were paired, mated to the same boar, and assigned randomly to treated or control farrowing groups. Treated sows received ivermectin s.c. at 300 micrograms/kg body weight; control sows received the vehicle s.c. Sow performance was evaluated via sow feed consumption, litter size, litter birth weights, litter weaning weights and piglet death loss from birth to weaning. Seven replicates (farrowing groups), each with six sow pairs, were included in the trial. Offspring from treated and control sows, 35 head/group, were fed to slaughter weights. Untreated sows had litters that weighed 4.14 kg less than ivermectin-treated sow litters at 21 d (P less than .07). Treated sows consumed 1.95 kg less feed per weaned piglet and .13 kg less feed per kilogram of weaned piglet (P less than .05). Piglets from treated sows were 5.79 kg/head heavier at slaughter (P less than .05) and had a .05 kg/d superior average daily gain (P less than .05).

Projections of the parabrachial nucleus in the pigeon (Columba livia).

The ascending and descending projections of the parabrachial nuclear complex in the pigeon have been charted with autoradiographic and histochemical (WGA-HRP) techniques. The ascending projections originate from a group of subnuclei surrounding various components of the brachium conjunctivum, namely, the superficial lateral, dorsolateral, dorsomedial, and ventromedial subnuclei. The projections are predominantly ipsilateral and travel in the quintofrontal tract. They are primarily to the medial and lateral hypothalamus (including the periventricular nucleus and the strata cellulare internum and externum), certain dorsal thalamic nuclei, the nucleus of the pallial commissure, the bed nucleus of the stria terminalis, the ventral paleostriatum, the olfactory tubercle, the nucleus accumbens, and a dorsolateral nucleus of the posterior archistriatum. There are weaker or more diffuse projections to the rostral locus coeruleus (cell group A8), the compact portion of the pedunculopontine tegmental nucleus, the central grey and intercollicular region, the ventral area of Tsai, the medial spiriform nucleus, the nucleus subrotundus, the anterior preoptic area, and the diagonal band of Broca. The parabrachial subnuclei have partially differential projections to these targets, some of which also receive projections from the nucleus of the solitary tract (Arends, Wild, and Zeigler: J. Comp. Neurol. 278:405-429, '88). Most of the targets, particularly those in the basal forebrain (viz., the periventricular nucleus and the strata cellulare internum and externum of the hypothalamus, the bed nucleus of the stria terminalis, and its lateral extension into the ventral paleostriatum, which may be comparable with the substantia innominata), have reciprocal connections with the parabrachial and solitary tract subnuclei and therefore may be said to compose parts of a "visceral forebrain system" analogous to that described in the rat (Van der Kooy et al: J. Comp. Neurol. 224:1-24, '84). The descending projections to the lower brainstem arise in large part from a ventrolateral subnucleus that may be comparable with the Kölliker-Fuse nucleus of mammals. They are mainly to the ventrolateral medulla, nucleus ambiguus, and massively to the hypoglossal nucleus, particularly its tracheosyringeal portion. These projections are therefore likely to be importantly involved in the control of vocalization and respiration (Wild and Arends: Brain Res. 407:191-194, '87). Some of these results have been presented in abstract form (Wild, Arends, and Zeigler: Soc. Neurosci. Abst. 13:308, '87).