Projections of the vestibular nuclei to the thalamus in the rat: a Phaseolus vulgaris leucoagglutinin study

Injections of the anterograde axonal tracer Phaseolus vulgaris leucoagglutinin were made into individual nuclei of the vestibular nuclear complex of the rat to identify specific projections to the thalamus. The results showed that the superior vestibular nucleus and the medial vestibular nucleus, especially its rostral-to-middle parts, project to the lateral part of the parafascicular thalamic nucleus (corresponding to the centromedian nucleus in primates), the transitional zone between the ventrolateral thalamic nucleus (VL) and the ventral posterolateral thalamic nucleus (VPL) (the region considered to be the nucleus ventralis intermedius of Vogt [Vogt C. 1909. La myeloarchitecture du thalamus du cercopitheque. J Psychol Neurol 12:285-324.]), the lateral part of the centrolateral thalamic nucleus and the dorsal part of the caudal VL; the spinal vestibular nucleus projects to the lateral part of the parafascicular thalamic nucleus, the transitional zone between the VL and the VPL, the caudal part of the ventrobasal complex, and the suprageniculate thalamic nucleus. These results suggest that vestibular information is transmitted not only to the cerebral cortex (mainly area 2V and area 3a) but also to the striatum. They also suggest that vestibular activity may affect gaze control by means of vestibulothalamocortical pathway in addition to vestibulo-ocular and vestibulopremotoneuronal routes.

Problems in using age-stratum-specific reference rates for indirect standardization

Disease risk in a study cohort can be compared with that in a reference population using the method of indirect standardization, adjusting for a difference in age distribution between the cohort and reference population. The common epidemiological practice is to use categorical age, typically in the form of 5-year age strata, in the standardization. This article discusses problems that arise owing to the categorization of age, including biased estimation and incorrect statistical inference on relative risk parameters. The same problems further extend to more general analyses using Poisson regression. We illustrate the problems using a hypothetical example and propose a simple remedy using linear splines. A slightly more elaborate method and its computer program are given in the appendix.

Explaining community-level variance in group randomized trials

Between-community variance or community-by-time variance is one of the key factors driving the cost of conducting group randomized trials, which are often very expensive. We investigated empirically whether between-community variance could be reduced by controlling individual- and/or community-level covariates and identified these covariates from four large community-based group randomized trials or surveys: the Working Well Trial; Kaiser Adolescent Survey; Kaiser Adults Survey; and the Eating Patterns Study. We found that adjusting for covariates will often substantially reduce the between-community variance component. Therefore investigators could block the communities according to these covariates, or adjust for these covariates to improve the power of community trials. We found that the community-by-time variance components are always near zero in these data sets, especially for the surveys where a cohort was followed over time. The covariate adjustment had less impact on reducing the community-by-time variance for the cohort samples than for the cross-sectional samples. This suggests that blocking may not be necessary for the design of the group randomized trials where the change from baseline is of primary interest. The Working Well Trial data were used to illustrate this point.

A clinic-based mammography intervention targeting inner-city women

OBJECTIVE

The objective was to evaluate the effect of a clinic-based intervention program on mammography use by inner-city women.

DESIGN

A randomized controlled trial employing firm system methodology was conducted.

SETTING

The study setting was a general internal medicine clinic in the university-affiliated county hospital serving metropolitan Seattle.

PARTICIPANTS

Women aged 50 to 74 years with at least one routine clinic appointment (when they were due for mammography) during the study period were enrolled in the trial (n = 314).

INTERVENTIONS

The intervention program emphasized nursing involvement and included physician education, provider prompts, use of audiovisual and printed patient education materials, transportation assistance in the form of bus passes, preappointment telephone or postcard reminders, and rescheduling assistance. Control firm women received usual care.

MEASUREMENTS AND MAIN RESULTS

Mammography completion within 8 weeks of clinic visits was significantly higher among intervention (49%) than control (22%) firm women (p < .001). These effects persisted after adjustment for potential confounding by age, race, medical insurance coverage, and previous mammography experience at the hospital (odds ratio 3.5; 95% confidence interval 1.9, 6.5). The intervention effect was modified by type of insurance coverage as well as prior mammography history. Process evaluation indicated that bus passes and rescheduling efforts did not contribute to the observed increases in screening participation.

CONCLUSIONS

A clinic-based program incorporating physician education, provider prompts, patient education materials, and appointment reminders and emphasizing nursing involvement can facilitate adherence to breast cancer screening guidelines among inner-city women.

Can restrictions on reimbursement for anti-ulcer drugs decrease Medicaid pharmacy costs without increasing hospitalizations?

OBJECTIVE

To examine the impact of a policy restricting reimbursement for Medicaid anti-ulcer drugs on anti-ulcer drug use and peptic-related hospitalizations.

DATA SOURCES/STUDY SETTING

In addition to U.S. Census Bureau data, all of the following from Florida: Medicaid anti-ulcer drug claims data, 1989-1993; Medicaid eligibility data, 1989-1993; and acute care nonfederal hospital discharge abstract data (Medicaid and non-Medicaid), 1989-1993.

STUDY DESIGN

In this observational study, a Poisson multiple regression model was used to compare changes, after policy implementation, in Medicaid reimbursement for prescription anti-ulcer drugs as well as hospitalization rates between pre- and post-implementation periods in Medicaid versus non-Medicaid patients hospitalized with peptic ulcer disease.

PRINCIPAL FINDINGS

Following policy implementation, the rate of Medicaid reimbursement for anti-ulcer drugs decreased 33 percent (p < .001). No associated increase occurred in the rate of Medicaid peptic-related hospitalizations.

CONCLUSIONS

Florida's policy restricting Medicaid reimbursement for anti-ulcer drugs was associated with a substantial reduction in outpatient anti-ulcer drug utilization without any significant increase in the rate of hospitalization for peptic-related conditions.

Roles of Rho-associated kinase in cytokinesis; mutations in Rho-associated kinase phosphorylation sites impair cytokinetic segregation of glial filaments

Rho-associated kinase (Rho-kinase), which is activated by the small GTPase Rho, regulates formation of stress fibers and focal adhesions, myosin fiber organization, and neurite retraction through the phosphorylation of cytoskeletal proteins, including myosin light chain, the ERM family proteins (ezrin, radixin, and moesin) and adducin. Rho-kinase was found to phosphorylate a type III intermediate filament (IF) protein, glial fibrillary acidic protein (GFAP), exclusively at the cleavage furrow during cytokinesis. In the present study, we examined the roles of Rho-kinase in cytokinesis, in particular organization of glial filaments during cytokinesis. Expression of the dominant-negative form of Rho-kinase inhibited the cytokinesis of Xenopus embryo and mammalian cells, the result being production of multinuclei. We then constructed a series of mutant GFAPs, where Rho-kinase phosphorylation sites were variously mutated, and expressed them in type III IF-negative cells. The mutations induced impaired segregation of glial filament (GFAP filament) into postmitotic daughter cells. As a result, an unusually long bridge-like cytoplasmic structure formed between the unseparated daughter cells. Alteration of other sites, including the cdc2 kinase phosphorylation site, led to no remarkable defect in glial filament separation. These results suggest that Rho-kinase is essential not only for actomyosin regulation but also for segregation of glial filaments into daughter cells which in turn ensures correct cytokinetic processes.

Mouse placental cells secrete soluble leptin receptor (sOB-R): cAMP inhibits sOB-R production

The aims of this study were to identify whether mouse placenta secretes soluble OB-R (sOB-R) and to find the regulating factor of OB-R expression. Total RNAs were extracted from placenta and decidua, and OB-R expression was assessed by Northern blot analysis. Decidua did not express OB-R mRNA. However, OB-R mRNA expression was detectable in the placenta on day 13 of pregnancy, and then it increased and reached a peak on day 17 of pregnancy. Mouse placental cells from day 12 of pregnancy were cultured and OB-R gene expression was assessed by Northern blot analysis. OB-R mRNA expression was detectable from the second day of culture and reached a peak on the third day of culture. To determine whether placental cells release sOB-R, supernatant of cultured placental cells was subjected to Western blot analysis. sOB-R was detected in the medium by the second day of culture and sOB-R release increased up to the fourth day of culture. Addition of leptin to the medium did not affect expression of OB-R mRNA. However, 8-bromo cAMP inhibited both steady-state levels of OB-R mRNA and the amount of sOB-R protein in the medium in a dose- and time-dependent manner. These results suggest that trophoblast cells differentiate, express, and release sOB-R both in vivo and in vitro and that cAMP is one of several potent regulators of sOB-R secretion by the mouse placenta.

Return to work following injury: the role of economic, social, and job-related factors

OBJECTIVES

This study examined factors influencing return to work (RTW) following severe fracture to a lower extremity.

METHODS

This prospective cohort study followed 312 individuals treated for a lower extremity fracture at 3 level-1 trauma centers. Kaplan-Meier estimates of the proportion of RTW were computed, and a Cox proportional hazards model was used to examine the contribution of multiple risk factors on RTW.

RESULTS

Cumulative proportions of RTW at 3, 6, 9, and 12 months post-injury were 0.26, 0.49, 0.60, and 0.72. After accounting for the extent of impairment, characteristics of the patient that correlated with higher rates of RTW included younger age, higher education, higher income, the presence of strong social support, and employment in a white-collar job that was not physically demanding. Receipt of disability compensation had a strong negative effect on RTW.

CONCLUSIONS

Despite relatively high rates of recovery, one quarter of persons with lower extremity fractures did not return to work by the end of 1 year. The analysis points to subgroups of individuals who are at high risk of delayed RTW, with implications for interventions at the patient, employer, and policy levels.

Real-time evaluation of the effectiveness of microwave coagulation therapy for hepatocellular carcinoma using color Doppler imaging

Percutaneous microwave coagulation therapy (PMCT) is a new technique for the treatment of hepatocellular carcinoma (HCC). However, it is difficult to distinguish those lesions in which necrosis has been induced from the viable residual lesions during the procedure, because the margin of the tumor becomes unclear during PMCT. We determined the area of necrotic lesions during the procedure using color Doppler imaging. PMCT was performed on 10 patients (17 lesions) with recurrent HCC. The electrode of the microwave delivery system was moved around the tumor and the surrounding area until color mosaic images disappeared from the entire area of the tumor. The areas in which necrotic tissue was indicated by color Doppler imaging were later confirmed by other modalities such as angiography or contrast-enhanced computed tomography. This leads us to believe that real-time, effective evaluation of PMCT is possible with color Doppler imaging.

Age-related changes in aortic sensitivity to noradrenaline and acetylcholine in rats

1. The purpose of the present study was to determine the relationship between plasma and tissue lipid levels and the effects of age on vascular responses to noradrenaline (NA) and acetylcholine (ACh). 2. Studies were performed in young and aged rats and the response of endothelium-intact and -denuded aortic rings to NA and to ACh was measured. The plasma concentration of cholesterol (total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL)) and 17 beta-oestradiol was determined, as was the aortic tissue content of phospholipids, cGMP and cholesterol (total, free and esterified). 3. Levels of all types of cholesterol in plasma and aorta increased with age; cholesterol levels in plasma correlated with those in the aorta; levels of phospholipid in the aorta did not increase with age but correlated with those of LDL cholesterol in plasma; levels of 17 beta-oestradiol did not change, but those of cGMP increased with age. 4. In endothelium-intact rings, the maximum tension developed by exposure to NA did not change, but the EC50 of NA increased with age and correlated with total cholesterol in the plasma and with the levels of all types of cholesterol in the aorta. In rings precontracted with NA, age decreased the maximum relaxation induced by ACh. The EC50 of ACh decreased with age and was inversely correlated with levels of cholesterol in the plasma and aorta. Treatment with NA increased cGMP levels in aged rats. Removal of the endothelium abolished the response to ACh and heightened the sensitivity to NA in young and aged rats. 5. Aortic endothelial cells seem to inhibit amine-induced contraction, while age-related changes in the levels of cholesterol in aortic tissue affect the sensitivity of the tissue to NA and ACh.

Tectal projections to the parvicellular reticular formation and the upper cervical spinal cord in the rat, with special reference to axon collateral innervation

After Phaseolus vulgaris leucoagglutinin injection into the lateral part of the superior colliculus (SC) in the rat, labeled fibers and axon terminals in the lower brainstem were distributed not only in the medial reticular formation but also in the lateral tegmental field including the parvicellular reticular formation (RFp). More caudally, in the upper cervical spinal cord labeled fibers with bouton-like varicosities were distributed mainly in laminae V, VII and VIII, with relatively sparse distribution in lamina IX. These labeled axons were found bilaterally with a clear-cut contralateral dominance. After combined injections of rhodamine-dextranamine, Fluoro-ruby (FR) into the RFp and Fluoro-gold (FG) into the upper cervical spinal cord on the same side, SC neurons labeled with FR were intermingled with those labeled with FG in the lateral part of the SC contralateral to the injection sites. In the stratum griseum intermediale, some of them were double-labeled with both tracers. Our results suggest that SC neurons innervating both the RFp and the cervical spinal cord may be involved in the coordination of head and mouth movements.

Developmental appearance of oligodendrocytes in the embryonic chick retina

The axons of the optic nerve layer are known to be myelinated by oligodendrocytes in the chick retina. The development of the retinal oligodendrocytes has been studied immunohistochemically with antibodies against oligodendrocyte lineage: monoclonal antibodies O4 and O1, and an antibody against myelin basic protein. O4 positive (O4+) cells were first detected in the retina on the tenth day of incubation (embryonic day (E)10, stage 36). The labeled cells were located in the optic nerve layer close to the optic fissure. Most were unipolar in shape, extending a leading process with a growth cone toward the periphery of the retina. By E12, unipolar O4+ cells had spread to the middle of the retina. Many O4+ cells close to the optic fissure showed radial arrangement with extension of processes toward the inner limiting membrane. O1+ oligodendrocytes were first observed in the E14 retina positioned just above (interiorly to) retinal ganglion cells. These labeled cells extended fine processes in the optic nerve layer. Limited numbers of myelin basic protein-positive cells were present by E16 and located interiorly to the retinal ganglion cells. In addition to the oligodendrocyte in the optic nerve layer, a limited number of O4+ cells were observed in the inner nuclear layer by E14, and they became O1+ by E18. Furthermore, explant culture experiments showed E10 to be the youngest stage at which the retina contained oligodendrocyte precursors. An intraventricular inj ection of fluorescent dye 1,1',dioctadecyl-3,3,3',3-tetramethylindocarbocyanine perchlorate (DiI) at E6 yielded O4+/DiI+ cells in the retina at E10, which provided direct evidence to support migration of oligodendrocyte precursor into the retina. The present results demonstrated the sequential appearance of the cells of oligodendrocyte lineage and the detailed morphology of the developing oligodendrocytes in the retina. These morphologic features strongly suggested that retinal oligodendrocytes were derived from the optic nerve and spread by migration through the optic nerve layer.

Phylogenetic relationships among Fagopyrum species revealed by the nucleotide sequences of the ITS region of the nuclear rRNA gene

The DNA sequences of the internal transcribed spacer (ITS) region of the rRNA gene were determined in 20 taxa of 12 species of Fagopyrum. By comparing the sequence data and constructing phylogenetic trees, the phylogenetic relationships among the Fagopyrum species were established. The sequences of ITS (ITS1 and ITS2) were about 3-7 times more variable than those of the 5.8S subunit of the rRNA gene. The classification of Fagopyrum species based on the DNA sequences of the rRNA gene almost coincides with the classification based on morphology, allozyme variability, and nucleotide sequences of the rbcL-accD region of the chloroplast DNA. A close relationship of F. lineare with the F. statice-F. leptopodum clade was suggested and this was strongly supported by a 68-bp gap in ITS1 found in these three species. A tetraploid F. cymosum from Kathi, India, has two distinct rRNA genes probably on homoeologous chromosomes, and was distinguished from the clade of other diploid/tetraploid F. cymosum with a high bootstrap value. This strengthened the hypothesis of the polyphyletic origin of the tetraploid F. cymosum.

Interspecific relationships in Fagopyrum (Polygonaceae) revealed by the nucleotide sequences of the rbcL and accD genes and their intergenic region

DNA sequences of the rbcL and accD 5' coding regions and their intergenic region (IGR) were determined in 20 taxa of 12 species of Fagopyrum. By comparing the sequence data and constructing phylogenetic trees, phylogenetic relationships among Fagopyrum species were investigated. The accD 5' coding region and the IGR have evolved about five times faster than the rcbL coding region; hence the phylogenetic trees based on the data of the accD 5' coding region, the IGR, and these data combined, had higher resolution than the trees based on rcbL alone. The classification of Fagopyrum based on the DNA sequences was almost perfectly consistent with the classification by Ohnishi and Matsuoka (1996, Genes & Genetic Systems 71: 383-390). New facts and minor differences are (1) polyploidization in F. cymosum might have occurred more than once, (2) F. lineare may not be a sister species of F. leptopodum, and (3) F. pleioramosum rather than F. capillatum may be a sister species of F. gracilipes.

Variation in mammographic breast density by time in menstrual cycle among women aged 40-49 years

BACKGROUND

Mammography is less effective for women aged 40-49 years than for older women, which has led to a call for research to improve the performance of screening mammography for younger women. One factor that may influence the performance of mammography is breast density. Younger women have greater mammographic breast density on average, and increased breast density increases the likelihood of false-negative and false-positive mammograms. We investigated whether breast density varies according to time in a woman's menstrual cycle.

METHODS

Premenopausal women aged 40-49 years who were not on exogenous hormones and who had a screening mammogram at a large health maintenance organization during 1996 were studied (n = 2591). Time in the menstrual cycle was based on the woman's self-reported last menstrual bleeding and usual cycle length.

RESULTS

A smaller proportion of women had "extremely dense" breasts during the follicular phase of their menstrual cycle (24% for week 1 and 23% for week 2) than during the luteal phase (28% for both weeks 3 and 4) (two-sided P = .04 for the difference in breast density between the phases, adjusted for body mass index). The relationship was stronger for women whose body mass index was less than or equal to the median (two-sided P<.01), the group who have the greatest breast density.

CONCLUSIONS/IMPLICATIONS

These findings are consistent with previous evidence suggesting that scheduling a woman's mammogram during the follicular phase (first and second week) of her menstrual cycle instead of during the luteal phase (third and fourth week) may improve the accuracy of mammography for premenopausal women in their forties. Breast tissue is less radiographically dense in the follicular phase than in the luteal phase.

Isolation, purification, and characterization of a collagen-associated serpin, caspin, produced by murine colon adenocarcinoma cells

A 45-kDa serpin secreted by a murine colon adenocarcinoma cell line, colon26, was isolated, purified, and characterized. It was found to bind specifically to type I collagen with high affinity and to type III collagen with lower affinity. Immunohistochemical studies of murine embryonic tissues showed a specific distribution of this collagen-associated serpin, named caspin, in relation to the formation of bone, cartilage, teeth, and basement membrane. The expression of caspin in high and low lung metastatic subclones of colon26 cell lines was inversely correlated with their metastatic capacity: low lung metastatic cells secreted higher amounts of caspin than their high lung metastatic counterparts. Caspin also demonstrated high homology with human pigment epithelium-derived factor/early population doubling level cDNA-1, which reportedly induces neuronal differentiation of human retinoblastoma cells and is expressed in association with G0 growth arrest. These findings suggest that caspin/pigment epithelium-derived factor/early population doubling level cDNA-1 is a novel factor that might play a crucial role in embryogenesis and tumor metastasis through binding to the extracellular matrix.

Patient empowerment and feedback did not decrease pain in seriously ill hospitalized adults

We tested a nurse clinician-mediated intervention to relieve pain in a group of seriously ill hospitalized adults using a randomized controlled trial at five tertiary care academic centers in the US. The study included 4804 patients admitted between January 1992 and January 1994 with one or more of nine high mortality diagnoses; 2652 were allocated to the intervention and 2152 to usual care. Specially-trained nurse clinicians assessed patients' pain, educated them and their families about pain control, empowered patients to expect pain relief, informed patients' nurses and physicians about level of pain and suggested or used other pain management resources. Patients' pain was determined from hospital interviews with patients and surrogates. Pain 2 and 6 months later or after death and satisfaction with its control at all time periods were also assessed. All analyses were adjusted for baseline risk of being in pain and propensity to be in the intervention group. Overall, 50.9% of patients reported some pain. After adjustment for other variables associated with pain, comparing the intervention to the control group, there was not a statistically significant difference in level of pain (OR for higher levels of pain 1.15; CI 1.00-1.32) or satisfaction with control of pain during the hospitalization (OR for higher levels of pain 1.12; CI 0.91-1.39), 2 or 6 months after discharge, or during the last 3 days of life. A multifaceted intervention using information, empowerment, advocacy, counseling and feedback was ineffective in ameliorating pain in seriously ill patients. Control of pain in these patients remains an important problem. More intensive pain treatment strategies addressing the needs of seriously ill hospitalized adults must be evaluated.

Nigral axon terminals are in contact with parvicellular reticular neurons which project to the motor trigeminal nucleus in the rat

We examined whether in the rat the descending fibers from the substantia nigra pars reticulata (SNr) were in contact with premotor neurons projecting to the motor trigeminal nucleus (Vm), using a combined anterograde and retrograde tracing technique. After ipsilateral injections of cholera toxin B subunit (CTb) into the Vm and biotinylated dextranamine (BDA) into the SNr, numerous CTb-labeled neurons were distributed bilaterally with slightly ipsilateral dominance in the parvicellular reticular formation (RFp), where many BDA-labeled axons with bouton-like varicosities were found bilaterally with a clear-cut ipsilateral dominance. The overlapping distribution of these labeled axons and neurons was more prominent in the rostral RFp than in the caudal RFp. Within the neuropil of the RFp, some of the BDA-labeled axons made synapses with the somata and proximal dendrites of CTb-labeled neurons. Thus, the present study demonstrated the existence of an indirect pathway from the SNr to the Vm, relayed by the RFp.

Filopodia and growth cones in the vertically migrating granule cells of the postnatal mouse cerebellum

The details of the morphology of vertically migrating granule cells were examined semiquantitatively in the postnatal mouse cerebellum by a Golgi method, with special reference to the growth cone-related structures such as filopodia and lamellipodia. The first sign of inward migration was extension of short, vertical filopodium-like processes from the sides of the perikarya of tangentially oriented granule cells, followed by a change of orientation of cell bodies to the vertical axis showing a T-shaped morphology. The T-shaped migratory cells formed sprouted filopodia (side spikes) from their vertical leading processes and perikarya at right angles to the vertical axis. More than three-quarters of the migratory cells extended the side spikes. The presence of such side spikes was confirmed with laser scanning confocal microscopy of granule cells labeled with 1,1', dioctadecyl-3,3,3',3-tetramethylindocarbocyanine perchlorate and also with transmission electron microscopy (TEM). In addition, about one-fourth of migratory cells extended lamellipodia of web-like forms along the stem or at the tip of the leading process, some of which showed a typical growth cone. Several morphological variations of vertical granule cells were also observed. Furthermore, TEM observation confirmed that side spikes from migratory cells made direct contact with parallel fibers. The present results suggest that, during vertical migration, growth cone-related structures of the leading processes of granule cells adhere to and probably recognize tangentially oriented parallel fibers. Therefore, the mechanisms of the vertical guidance and migration of granule cells in the cerebellar cortex seem to be multiple, involving not only parallel contact guidance by the Bergmann glia fibers but also perpendicular contact guidance by the parallel fibers. These parallel and perpendicular geometric cues surrounding the granule cells seem to have produced the varying morphology of vertically migrating granule cells.

Evaluation of the AMPLICOR CMV test for direct detection of cytomegalovirus in plasma specimens

We evaluated the AMPLICOR CMV test (PCR) for the direct detection of cytomegalovirus in plasma. Sixty-eight specimens were involved for the comparison between the AMPLICOR test and the antigenemia assay. The sensitivities, specificities, and positive and negative predictive values were 97.1, 100, 100, and 97.1%, respectively, for the AMPLICOR test and 79.4, 100, 100, and 82.9%, respectively, for the antigenemia assay.

Enhancement of neurite outgrowth by the soluble form of human L1 (neural cell adhesion molecule)

L1, a neural cell adhesion molecule, is involved in neurite outgrowth, migration and fasciculation. Although L1 is a membrane glycoprotein expressed on neural cells, the soluble form of L1 is generated in vivo by proteolysis. In the present study, a stable transfectant of Chinese hamster ovary (CHO) cells secreting human L1 without cytoplasmic and membrane spanning domains was generated, and the function of the secreted L1 was examined. Explants from embryonic chick brain stem were cultured on a substrate coated with polyethylenimine (PEI) alone, on substrate-bound L1 or in medium containing soluble L1. The neurites induced by L1, both the substrate-bound form and the soluble form, were 2-3 times longer than those cultured on PEI. The ability of the soluble L1 to induce neurite formation was slightly greater than that of the substrate L1. The present results demonstrated that neurite outgrowth was induced not only by substrate-bound L1 but also by soluble L1. Soluble L1 could be a pharmaceutical candidate for the promotion of nerve regeneration.

Organization of the nigro-tecto-bulbar pathway to the parvicellular reticular formation: a light- and electron-microscopic study in the rat

We examined a nigro-tecto-bulbar pathway to the parvicellular reticular formation (RFp), where many premotor neurons for orofacial motor nuclei are known to be distributed, by using a combined anterograde and retrograde tracing method. After contralateral injections of biotinylated dextranamine (BDA) into the dorsolateral part of the substantia nigra (SNr) and cholera toxin B subunit (CTb) into the RFp, overlapping distributions of BDA-labeled terminals and CTb-labeled neuronal cell bodies were found in the lateralmost part of the superior colliculus (SC) ipsilateral or contralateral to the site of BDA injection or CTb injection, respectively. After contralateral injections of BDA into the SNr and horseradish peroxidase conjugated to wheat germ agglutinin (WGA-HRP) injection into the RFp, ipsilateral labeled axon terminals with BDA were found to make symmetrical synaptic contacts with the somata and dendrites of contralateral labeled neurons with WGA-HRP in the lateralmost part of the SC. Furthermore, we demonstrated that BDA-labeled axon terminals were immunoreactive for GABA, by using the anterograde tracing method combined with immunohistochemistry for GABA. Thus, GABA-like immunoreactive fibers originating from the dorsolateral part of the SNr make monosynaptic contacts with the tectal neurons sending their axons to the RFp.