Rescue of BDNF expression by the thalamic parafascicular nucleus with chronic treatment with the mGluR2/3 agonist LY379268 may contribute to the LY379268 rescue of enkephalinergic striatal projection neurons in R6/2 Huntington's disease mice

We have found that daily subcutaneous injection with a maximum tolerated dose of the mGluR2/3 agonist LY379268 (20 mg/kg) beginning at 4 weeks of age dramatically improves the motor, neuronal and neurochemical phenotype in R6/2 mice, a rapidly progressing transgenic model of Huntington's disease (HD). We also previously showed that the benefit of daily LY379268 in R6/2 mice was associated with increases in corticostriatal brain-derived neurotrophic factor (BDNF), and in particular was associated with a reduction in enkephalinergic striatal projection neuron loss. In the present study, we show that daily LY379268 also rescues expression of BDNF by neurons of the thalamic parafascicular nucleus in R6/2 mice, which projects prominently to the striatum, and this increase too is linked to the rescue of enkephalinergic striatal neurons. Thus, LY379268 may protect enkephalinergic striatal projection neurons from loss by boosting BDNF production and delivery via both the corticostriatal and thalamostriatal projection systems. These results suggest that chronic treatment with mGluR2/3 agonists may represent an approach for slowing enkephalinergic neuron loss in HD, and perhaps progression in general.

Embryoscopy and karyotype findings of repeated miscarriages in recurrent pregnancy loss and spontaneous pregnancy loss

PURPOSE

The aim of the study was to assess cytogenetic and embryoscopic characteristics in subsequent miscarriages of spontaneous pregnancy losses (SPL) and recurrent pregnancy losses (RPL).

METHODS

A retrospective cohort of 75 women was affected by repeated pregnancy loss. Of those, 34 had SPL, 24 primary RPL, and 17 secondary RPL. Ploidy status and morphology was analyzed by transcervical embryoscopic examination of the embryo and cytogenetic analysis of the chorionic villi in subsequent miscarriages.

RESULTS

Similar rates of recurrent ploidy status were observed between first and second miscarriage in SPL and RPL (82.4% recurrent ploidy status in SPL, p > 0.999; 73% recurrent ploidy status in RPL, p = 0.227). No difference was found regarding recurrent abnormal morphology between SPL and RPL (p = 0.092). However, secondary RPL resulted significantly more often in recurrent abnormal morphology compared to primary RPL (p = 0.004).

CONCLUSIONS

High rates of recurrent normal/abnormal karyotypes were observed in all groups with a majority of embryos presenting with recurrent abnormal morphology. Secondary RPL presented significantly more often with recurrent abnormal morphology compared to primary RPL. These findings offer prognostic information for the affected patient and might impact treatment choice.

Effect of early embryonic deletion of huntingtin from pyramidal neurons on the development and long-term survival of neurons in cerebral cortex and striatum

We evaluated the impact of early embryonic deletion of huntingtin (htt) from pyramidal neurons on cortical development, cortical neuron survival and motor behavior, using a cre-loxP strategy to inactivate the mouse htt gene (Hdh) in emx1-expressing cell lineages. Western blot confirmed substantial htt reduction in cerebral cortex of these Emx-htt^KO mice, with residual cortical htt in all likelihood restricted to cortical interneurons of the subpallial lineage and/or vascular endothelial cells. Despite the loss of htt early in development, cortical lamination was normal, as revealed by layer-specific markers. Cortical volume and neuron abundance were, however, significantly less than normal, and cortical neurons showed reduced brain-derived neurotrophic factor (BDNF) expression and reduced activation of BDNF signaling pathways. Nonetheless, cortical volume and neuron abundance did not show progressive age-related decline in Emx-htt^KO mice out to 24 months. Although striatal neurochemistry was normal, reductions in striatal volume and neuron abundance were seen in Emx-htt^KO mice, which were again not progressive. Weight maintenance was normal in Emx-htt^KO mice, but a slight rotarod deficit and persistent hyperactivity were observed throughout the lifespan. Our results show that embryonic deletion of htt from developing pallium does not substantially alter migration of cortical neurons to their correct laminar destinations, but does yield reduced cortical and striatal size and neuron numbers. The Emx-htt^KO mice were persistently hyperactive, possibly due to defects in corticostriatal development. Importantly, deletion of htt from cortical pyramidal neurons did not yield age-related progressive cortical or striatal pathology.

Abstract P1-09-10: Pathological complete response to neoadjuvant trastuzumab is dependent on HER2/CEP17 ratio in HER2-amplified early breast cancer

Purpose To evaluate whether pathological complete response to neoadjuvant trastuzumab is dependent on the level of HER2 amplification.

Patients and Methods 114 women with HER2-overexpressing early breast cancer who had received neo-adjuvant trastuzumab in the prospective ABCSG-24 and ABCSG-32 trials, and for whom the HER2/CEP17 ratio was available, were included in this analysis. The ratio was correlated with tumor response as measured by the three most commonly used definitions of pathological complete response: ypT0 ypN0, ypT0/is ypN0, and ypT0/is.

Results In trastuzumab-treated patients, ypT0 pN0 was achieved in 69.0% of patients with a HER2/CEP17 ratio of >6, but only in 30.4% of tumors with a ratio of ≤6 (p=0.001, Chi Square test). When pCR was defined by ypT0/is pN0 or by ypTis, 75.9% and 82.8% of tumors with a high ratio had a complete remission, while only 39.1%, and 38.3% with a low ratio achieved a pCR (p=0.002 and p<0.001, respectively). Logistic regression revealed that tumors with a higher HER2/CEP17 ratio had a significantly higher probability to achieve ypT0 ypN0 (OR: 5.08, 95% CI 1.86-13.90; p=0.002) than tumors with a low ratio, while none of the other clinicopathological parameters was predictive of pCR. The association between high HER2 amplification and pCR was almost exclusively confined to HR positive tumors (62.5% vs. 24.0%, 75.0% vs. 28.0%, and 87.5% vs. 28.0%, for ypT0 ypN0, ypT0/is ypN0, and ypT0/is; p=0.014, p=0.005, and p<0.001), and was largely absent in HR negative tumors.

Conclusion A HER2/CEP17 ratio of >6 in the pre-therapeutic tumor biopsy is associated with a significantly higher pCR rate particularly in HER2 / HR co-positive tumors, and can be used to predict outcome before neoadjuvant trastuzumab is initiated.

Citation Format: Singer CF, Tan YY, Fitzal F, Steger GG, Egle D, Reiner A, Rudas M, Gruber C, Bartsch R, Fridrik M, Seifert M, Exner R, Balic M, Bago-Horvath Z, Filipits M, Gnant M, For the Austrian Breast and Colorectal Cancer Study Group. Pathological complete response to neoadjuvant trastuzumab is dependent on HER2/CEP17 ratio in HER2-amplified early breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-09-10.

Long wavelength optical control of glutamate receptor ion channels using a tetra-ortho-substituted azobenzene derivative

A tetra-ortho-chloro substituted azobenzene unit was incorporated into a photoswitchable tethered ligand for ionotropic glutamate receptors. This compound confers the modified protein with the unusual optical responses of the substituted azo scaffold permitting channel opening with yellow and red light and channel closing with blue light.

Generalization of adiposity genetic loci to US Hispanic women

BACKGROUND:

Obesity is a public health concern. Yet the identification of adiposity-related genetic variants among United States (US) Hispanics, which is the largest US minority group, remains largely unknown.

OBJECTIVE:

To interrogate an a priori list of 47 (32 overall body mass and 15 central adiposity) index single-nucleotide polymorphisms (SNPs) previously studied in individuals of European descent among 3494 US Hispanic women in the Women's Health Initiative SNP Health Association Resource (WHI SHARe).

DESIGN:

Cross-sectional analysis of measured body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) were inverse normally transformed after adjusting for age, smoking, center and global ancestry. WC and WHR models were also adjusted for BMI. Genotyping was performed using the Affymetrix 6.0 array. In the absence of an a priori selected SNP, a proxy was selected (r²⩾0.8 in CEU).

RESULTS:

Six BMI loci (TMEM18, NUDT3/HMGA1, FAIM2, FTO, MC4R and KCTD15) and two WC/WHR loci (VEGFA and ITPR2-SSPN) were nominally significant (P<0.05) at the index or proxy SNP in the corresponding BMI and WC/WHR models. To account for distinct linkage disequilibrium patterns in Hispanics and further assess generalization of genetic effects at each locus, we interrogated the evidence for association at the 47 surrounding loci within 1 Mb region of the index or proxy SNP. Three additional BMI loci (FANCL, TFAP2B and ETV5) and five WC/WHR loci (DNM3-PIGC, GRB14, ADAMTS9, LY86 and MSRA) displayed Bonferroni-corrected significant associations with BMI and WC/WHR. Conditional analyses of each index SNP (or its proxy) and the most significant SNP within the 1 Mb region supported the possible presence of index-independent signals at each of these eight loci as well as at KCTD15.

CONCLUSION:

This study provides evidence for the generalization of nine BMI and seven central adiposity loci in Hispanic women. This study expands the current knowledge of common adiposity-related genetic loci to Hispanic women.

BDNF may play a differential role in the protective effect of the mGluR2/3 agonist LY379268 on striatal projection neurons in R6/2 Huntington's disease mice

We have found that daily subcutaneous injection with a maximum tolerated dose (MTD) of the mGluR2/3 agonist LY379268 (20mg/kg) beginning at 4 weeks dramatically improves the phenotype in R6/2 mice. For example, we observed normalization of motor function in distance traveled, speed, the infrequency of pauses, and the ability to locomote in a straight line, and a rescue of a 15-20% striatal neuron loss at 10 weeks. As acute LY379268 treatment is known to increase cortical BDNF production, and BDNF is known to be beneficial for striatal neurons, we investigated if the benefit of daily LY379268 in R6/2 mice for striatal projection neurons was associated with increases in corticostriatal BDNF, with assessments done at 10 weeks of age after daily MTD treatment since the fourth week of life. We found that LY379268 increased BDNF expression in layer 5 neurons in motor cortex, which project to striatum, partly rescued a preferential loss of enkephalinergic striatal neurons, and enhanced substance P (SP) expression by SP striatal projection neurons. The enhanced survival of enkephalinergic striatal neurons was correlated with the cortical BDNF increase, but the enhanced SP expression by SP striatal neurons was not. Thus, LY379268 may protect the two main striatal projection neuron types by different mechanisms, enkephalinergic neurons by the trophic benefit of BDNF, and SP neurons by a mechanism not involving BDNF. The SP neuron benefit may perhaps instead involve the anti-excitotoxic action of mGluR2/3 receptor agonists.

The group 2 metabotropic glutamate receptor agonist LY379268 rescues neuronal, neurochemical and motor abnormalities in R6/2 Huntington's disease mice

Excitotoxic injury to striatum by dysfunctional cortical input or aberrant glutamate uptake may contribute to Huntington's disease (HD) pathogenesis. Since corticostriatal terminals possess mGluR2/3 autoreceptors, whose activation dampens glutamate release, we tested the ability of the mGluR2/3 agonist LY379268 to improve the phenotype in R6/2 HD mice with 120-125 CAG repeats. Daily subcutaneous injection of a maximum tolerated dose (MTD) of LY379268 (20mg/kg) had no evident adverse effects in WT mice, and diverse benefits in R6/2 mice, both in a cohort of mice tested behaviorally until the end of R6/2 lifespan and in a cohort sacrificed at 10weeks of age for blinded histological analysis. MTD LY379268 yielded a significant 11% increase in R6/2 survival, an improvement on rotarod, normalization and/or improvement in locomotor parameters measured in open field (activity, speed, acceleration, endurance, and gait), a rescue of a 15-20% cortical and striatal neuron loss, normalization of SP striatal neuron neurochemistry, and to a lesser extent enkephalinergic striatal neuron neurochemistry. Deficits were greater in male than female R6/2 mice, and drug benefit tended to be greater in males. The improvements in SP striatal neurons, which facilitate movement, are consistent with the improved movement in LY379268-treated R6/2 mice. Our data indicate that mGluR2/3 agonists may be particularly useful for ameliorating the morphological, neurochemical and motor defects observed in HD.

Open-label, randomised, parallel-group, multicentre study to evaluate the safety, tolerability and immunogenicity of an AS03(B)/oil-in-water emulsion-adjuvanted (AS03(B)) split-virion versus non-adjuvanted whole-virion H1N1 influenza vaccine in UK children 6 months to 12 years of age

OBJECTIVE

To evaluate the safety, tolerability and immunogenicity of an AS03(B)/oil-in-water emulsion-adjuvanted (AS03(B)) split-virion versus non-adjuvanted whole-virion H1N1 influenza vaccine in UK children aged 6 months to 12 years.

DESIGN

Multicentre, randomised, head-to-head, open-label trial.

SETTING

Five UK sites (Oxford, Bristol, Southampton, Exeter and London).

PARTICIPANTS

Children aged 6 months to < 13 years, for whom a parent or guardian had provided written informed consent and who were able to comply with study procedures, were eligible for inclusion.

INTERVENTIONS

A tocopherol/oil-in-water emulsion-adjuvanted (AS03(B)) egg culture-derived split-virion H1N1 vaccine and a non-adjuvanted cell culture-derived whole-virion vaccine, given as a two-dose schedule, 21 days apart, were compared. Participants were grouped into those aged 6 months to < 3 years (younger group) and 3 years to < 13 years of age (older group) and were randomised by study investigators (1 : 1 ratio) to receive one of the two vaccines. Vaccines were administered by intramuscular injection (deltoid or anterior-lateral thigh, depending on age and muscle bulk). Local reactions and systemic symptoms were collected for 1 week post immunisation, and serum was collected at baseline and after the second dose. To assess safety and tolerability, parents or guardians recorded the following information in diary cards from days 0-7 post vaccination: axillary temperature, injection site reactions, solicited and unsolicited systemic symptoms, and medications.

MAIN OUTCOME MEASURE

Comparison between vaccines of the percentage of participants demonstrating seroconversion by microneutralisation assay.

RESULTS

Among 937 children receiving vaccine, per-protocol seroconversion rates were higher after the AS03(B)-adjuvanted vaccine than after the whole-virion vaccine (98.2% vs 80.1% in children < 3 years, 99.1% vs 95.9% among those aged 3-12 years), as were severe local reactions (3.6% vs 0.0% in those under 5 years, 7.8% vs 1.1% in those aged 5-12 years), irritability in children < 5 years (46.7% vs 32.0%), and muscle pain in older children (28.9% vs 13.2%). The second dose of the adjuvanted vaccine was more reactogenic than the first, especially for fever > 38.0°C in those under 5 years of age (8.9% vs 22.4%).

CONCLUSION

The adjuvanted vaccine, although reactogenic, was more immunogenic, especially in younger children, indicating the potential for improved immunogenicity of influenza vaccines in this age group.

TRIAL REGISTRATION NUMBER

ISRCTN89141709.

Bayesian methods for meta-analysis of causal relationships estimated using genetic instrumental variables

Genetic markers can be used as instrumental variables, in an analogous way to randomization in a clinical trial, to estimate the causal relationship between a phenotype and an outcome variable. Our purpose is to extend the existing methods for such Mendelian randomization studies to the context of multiple genetic markers measured in multiple studies, based on the analysis of individual participant data. First, for a single genetic marker in one study, we show that the usual ratio of coefficients approach can be reformulated as a regression with heterogeneous error in the explanatory variable. This can be implemented using a Bayesian approach, which is next extended to include multiple genetic markers. We then propose a hierarchical model for undertaking a meta-analysis of multiple studies, in which it is not necessary that the same genetic markers are measured in each study. This provides an overall estimate of the causal relationship between the phenotype and the outcome, and an assessment of its heterogeneity across studies. As an example, we estimate the causal relationship of blood concentrations of C-reactive protein on fibrinogen levels using data from 11 studies. These methods provide a flexible framework for efficient estimation of causal relationships derived from multiple studies. Issues discussed include weak instrument bias, analysis of binary outcome data such as disease risk, missing genetic data, and the use of haplotypes.

Safety and immunogenicity of AS03B adjuvanted split virion versus non-adjuvanted whole virion H1N1 influenza vaccine in UK children aged 6 months-12 years: open label, randomised, parallel group, multicentre study

OBJECTIVES

To compare the safety, reactogenicity, and immunogenicity of an adjuvanted split virion H1N1 vaccine and a non-adjuvanted whole virion vaccine used in the pandemic immunisation programme in the United Kingdom.

DESIGN

Open label, randomised, parallel group, phase II study.

SETTING

Five UK centres (Oxford, Southampton, Bristol, Exeter, and London).

PARTICIPANTS

Children aged 6 months to less than 13 years for whom a parent or guardian had provided written informed consent and who were able to comply with study procedures were eligible. Those with laboratory confirmed pandemic H1N1 influenza or clinically diagnosed disease meriting antiviral treatment, allergy to egg or any other vaccine components, or coagulation defects, or who were severely immunocompromised or had recently received blood products were excluded. Children were grouped by age: 6 months-<3 years (younger group) and 3-<13 years (older group). Recruitment was by media advertising and direct mailing. Recruitment visits were attended by 949 participants, of whom 943 were enrolled and 937 included in the per protocol analysis.

INTERVENTIONS

Participants were randomised 1:1 to receive AS03(B) (tocopherol based oil in water emulsion) adjuvanted split virion vaccine derived from egg culture or non-adjuvanted whole virion vaccine derived from cell culture. Both were given as two doses 21 days apart. Reactogenicity data were collected for one week after immunisation by diary card. Serum samples were collected at baseline and after the second dose.

MAIN OUTCOME MEASURES

Primary reactogenicity end points were frequency and severity of fever, tenderness, swelling, and erythema after vaccination. Immunogenicity was measured by microneutralisation and haemagglutination inhibition assays. The primary immunogenicity objective was a comparison between vaccines of the percentage of participants showing seroconversion by the microneutralisation assay (fourfold rise to a titre of >or=1:40 from before vaccination to three weeks after the second dose).

RESULTS

Seroconversion rates were higher after the adjuvanted split virion vaccine than after the whole virion vaccine, most notably in the youngest children (163 of 166 participants with paired serum samples (98.2%, 95% confidence interval 94.8% to 99.6%) v 157 of 196 (80.1%, 73.8% to 85.5%), P<0.001) in children under 3 years and 226 of 228 (99.1%, 96.9% to 99.9%) v 95.9%, 92.4% to 98.1%, P=0.03) in those over 3 years). The adjuvanted split virion vaccine was more reactogenic than the whole virion vaccine, with more frequent systemic reactions and severe local reactions in children aged over 5 years after dose one (13 (7.2%, 3.9% to 12%) v 2 (1.1%, 0.1% to 3.9%), P<0.001) and dose two (15 (8.5%, 4.8% to 13.7%) v 2 (1.1%, 0.1% to 4.1%), P<0.002) and after dose two in those under 5 years (15 (5.9%, 3.3% to 9.6%) v 0 (0.0%, 0% to 1.4%), P<0.001). Dose two of the adjuvanted split virion vaccine was more reactogenic than dose one, especially for fever >or=38 masculineC in those aged under 5 (24 (8.9%, 5.8% to 12.9%) v 57 (22.4%, 17.5% to 28.1%), P<0.001).

CONCLUSIONS

In this first direct comparison of an AS03(B) adjuvanted split virion versus whole virion non-adjuvanted H1N1 vaccine, the adjuvanted vaccine, while more reactogenic, was more immunogenic and, importantly, achieved high seroconversion rates in children aged less than 3 years. This indicates the potential for improved immunogenicity of influenza vaccines in this age group.

TRIAL REGISTRATION

Clinical trials.gov NCT00980850; ISRCTN89141709.

CAG repeat lengths > or =335 attenuate the phenotype in the R6/2 Huntington's disease transgenic mouse

With spontaneous elongation of the CAG repeat in the R6/2 transgene to > or =335, resulting in a transgene protein too large for passive entry into nuclei via the nuclear pore, we observed an abrupt increase in lifespan to >20 weeks, compared to the 12 weeks common in R6/2 mice with 150 repeats. In the > or =335 CAG mice, large ubiquitinated aggregates of mutant protein were common in neuronal dendrites and perikaryal cytoplasm, but intranuclear aggregates were small and infrequent. Message and protein for the > or =335 CAG transgene were reduced to one-third that in 150 CAG R6/2 mice. Neurological and neurochemical abnormalities were delayed in onset and less severe than in 150 CAG R6/2 mice. These findings suggest that polyQ length and pathogenicity in Huntington's disease may not be linearly related, and pathogenicity may be less severe with extreme repeats. Both diminished mutant protein and reduced nuclear entry may contribute to phenotype attenuation.

Towards a unification of hierarchical reference theory and self-consistent Ornstein-Zernike approximation: analysis of exactly solvable mean-spherical and generalized mean-spherical models

The hierarchical reference theory (HRT) and the self-consistent Ornstein-Zernike approximation (SCOZA) are two liquid state theories that both furnish a largely satisfactory description of the critical region as well as the phase coexistence and equation of state in general. Furthermore, there are a number of similarities that suggest the possibility of a unification of both theories. Earlier in this respect we have studied consistency between the internal energy and free energy routes. As a next step toward this goal we here consider consistency with the compressibility route too, but we restrict explicit evaluations to a model whose exact solution is known showing that a unification works in that case. The model in question is the mean spherical model (MSM) which we here extend to a generalized MSM. For this case, we show that the correct solutions can be recovered from suitable boundary conditions through either SCOZA or HRT alone as well as by the combined theory. Furthermore, the relation between the HRT-SCOZA equations and those of SCOZA and HRT becomes transparent.

Differential localization of the GluR1 and GluR2 subunits of the AMPA-type glutamate receptor among striatal neuron types in rats

Differences among the various striatal projection neuron and interneuron types in cortical input, function, and vulnerability to degenerative insults may be related to differences among them in AMPA-type glutamate receptor abundance and subunit configuration. We therefore used immunolabeling to assess the frequency and abundance of GluR1 and GluR2, the most common AMPA subunits in striatum, in the main striatal neuron types. All neurons projecting to the external pallidum (GPe), internal pallidum (GPi) or substantia nigra, as identified by retrograde labeling, possessed perikaryal GluR2, while GluR1 was more common in striato-GPe than striato-GPi perikarya. The frequency and intensity of immunostaining indicated the rank order of their perikaryal GluR1:GluR2 ratio to be striato-GPe>striatonigral>striato-GPi. Ultrastructural studies suggested a differential localization of GluR1 and GluR2 to striatal projection neuron dendritic spines as well, with GluR1 seemingly more common in striato-GPe spines and GluR2 more common in striato-GPi and/or striatonigral spines. Comparisons among projection neurons and interneurons revealed GluR1 to be most common and abundant in parvalbuminergic interneurons, and GluR2 most common and abundant in projection neurons, with the rank order for the GluR1:GluR2 ratio being parvalbuminergic interneurons>calretinergic interneurons>cholinergic interneurons>projection neurons>somatostatinergic interneurons. Striosomal projection neurons had a higher GluR1:GluR2 ratio than did matrix projection neurons. The abundance of both GluR1 and GluR2 in striatal parvalbuminergic interneurons and projection neurons is consistent with their prominent cortical input and susceptibility to excitotoxic insult, while differences in GluR1:GluR2 ratio among projection neurons are likely to yield differences in Ca(2+) permeability, desensitization, and single channel current, which may contribute to differences among them in plasticity, synaptic integration, and excitotoxic vulnerability. The apparent association of the GluR1 subunit with synaptic plasticity, in particular, suggests striato-GPe neuron spines as a particular site of corticostriatal synaptic plasticity, presumably associated with motor learning.

Self-consistent Ornstein-Zernike approximation for molecules with soft cores

The self-consistent Ornstein-Zernike approximation (SCOZA) is an accurate liquid state theory. So far it has been tied to interactions composed of hard core repulsion and long-range attraction, whereas real molecules have soft core repulsion at short distances. In the present work, this is taken into account through the introduction of an effective hard core with a diameter that depends upon temperature only. It is found that the contribution to the configurational internal energy due to the repulsive reference fluid is of prime importance and must be included in the thermodynamic self-consistency requirement on which SCOZA is based. An approximate but accurate evaluation of this contribution relies on the virial theorem to gauge the amplitude of the pair distribution function close to the molecular surface. Finally, the SCOZA equation is transformed by which the problem is reformulated in terms of the usual SCOZA with fixed hard core reference system and temperature-dependent interaction.

Single-cell RT-PCR, in situ hybridization histochemical, and immunohistochemical studies of substance P and enkephalin co-occurrence in striatal projection neurons in rats

Single-cell RT-PCR studies in 3-4-week-old rats have raised the possibility that as many as 20% of striatal projection neurons may be a unique type that contains both substance P (SP) and enkephalin (ENK). We used single-cell RT-PCR, retrograde labeling, in situ hybridization histochemistry, and immunolabeling to characterize the abundance of this cell type, its projection target(s), and any developmental changes in its frequency. We found by RT-PCR that 11% of neurons containing either SP or ENK contained both in 4-week-old rats, while in 4-month-old rats SP/ENK colocalization was only 3%. SP-only neurons tended to co-contain dynorphin and ENK-only neurons neurotensin, while SP/ENK neurons tended to contain dynorphin. Single-cell RT-PCR showed SP/ENK co-occurrence in 4-week-old rats to be no more common among striatal neurons retrogradely labeled from the substantia nigra than among those retrogradely labeled from globus pallidus. Double-label in situ hybridization showed SP/ENK perikarya to be scattered throughout striatum, making up 8% of neurons containing either SP or ENK at 4 weeks, but only 4% at 4 months. Immunolabeling showed that presumptive striatal terminals in globus pallidus externus, globus pallidus internus and substantia nigra pars reticulata that colocalized SP and ENK were scarce. Terminals colocalizing SP and ENK were, however, abundant in the substantia nigra pars compacta. Thus, SP-only and ENK-only neurons make up the vast majority of striatal projection neurons in rats, the frequency of SP/ENK colocalizing striatal neurons is low in adult rats (3-4%), and SP/ENK colocalizing neurons primarily project to SNc but do not appear to be confined to striosomes.

Early post-traumatic osteoarthritis-like changes in human articular cartilage following rupture of the anterior cruciate ligament

OBJECTIVE

Injury to the anterior cruciate ligament (ACL) frequently leads to post-traumatic osteoarthritis (OA). In this study we determined whether early degenerative changes characteristic of idiopathic OA are induced in articular cartilage following ACL injury.

METHODS

A small sample of femoral articular cartilage was removed at surgery, as part of ACL reconstruction, from a total of 50 patients with ACL injuries. Of these, 28 underwent surgery less than 1 year post-injury. Control cartilages were obtained from the same site from 21 persons at autopsy. All cartilages were examined for molecular changes. The content of type II collagen, its cleavage by collagenases and its denaturation were determined by immunoassay. The total content of glycosaminoglycan (GAG), which is principally aggrecan, was measured colorimetrically. Data were expressed per unit DNA (GAG and collagen content) or as a percentage of total collagen cleaved or denatured. Other cartilages from the same site (8 controls, 12 less than 1 year and 8 more than 1 year post-injury) were frozen sectioned and examined histologically to determine by Mankin grading cartilage degeneration.

RESULTS

Histological analyses revealed that control subjects exhibited staining for proteoglycan, which was reduced in some patients following ACL rupture. Degeneration of the articular surface was sometimes observed 1 year after ACL rupture. Although the Mankin grade increased with time after rupture these changes were not significant. Immunoassays, however, revealed an increase in GAG content within 1 year which was maintained after 1 year although no longer significant. No changes in total type II collagen content were observed during the period of study. However, there were significant increases in the denaturation and cleavage of type II collagen less than and more than 1 year post-ACL rupture. Total type II collagen content was directly correlated with GAG content in all three groups, with the significance being weakest at more than 1 year. After 1 year an inverse correlation was observed between total type II collagen content and collagen cleavage as well as denaturation.

CONCLUSIONS

These observations reveal that joint instability resulting from ACL injury rapidly results in degenerative changes characteristic of those seen in idiopathic OA at arthroplasty and in experimental OA following ACL surgery. These changes may contribute to the development of post-traumatic OA that is commonly observed following ACL injury. The observations support and extend conclusions from other studies on human and animal articular cartilage and synovial fluids post-ACL injury that have revealed a rapid onset of damage to type II collagen and an initial increase in proteoglycan content characteristic of experimental OA post-ACL injury. This study provides direct evidence for the rapid development of degenerative changes characteristic of OA following ACL injury.

Towards a unification of the hierarchical reference theory and the self-consistent Ornstein-Zernike approximation

The hierarchical reference theory and the self-consistent Ornstein-Zernike approximation are two liquid state theories that both furnish a largely satisfactory description of the critical region as well as phase coexistence and the equation of state in general. Furthermore, there are a number of similarities that suggest the possibility of a unification of both theories. As a first step towards this goal, we consider the problem of combining the lowest order gamma expansion result for the incorporation of a Fourier component of the interaction with the requirement of consistency between internal and free energies, leaving aside the compressibility relation. For simplicity, we restrict ourselves to a simplified lattice gas that is expected to display the same qualitative behavior as more elaborate models. It turns out that the analytically tractable mean spherical approximation is a solution to this problem, as are several of its generalizations. Analysis of the characteristic equations shows the potential for a practical scheme and yields necessary conditions that any closure to the Ornstein-Zernike relation must fulfill for the consistency problem to be well posed and to have a unique differentiable solution. These criteria are expected to remain valid for more general discrete and continuous systems, even if consistency with the compressibility route is also enforced where possible explicit solutions will require numerical evaluations.

A new avian brain nomenclature: Why, how and what

Many of the assumptions of homology on which the standard nomenclature for the cell groups and fiber tracts of the avian brain have been based are in error, and consequently that terminology promotes misunderstanding of the functional organization of avian brain and its evolutionary relationship to mammalian brain. Recognizing this problem, a number of avian brain researchers began an effort to revise the terminology, which culminated in the Avian Brain Nomenclature Forum, held at Duke University from 18 to 20 July 2002. In the new terminology approved at this Forum, the flawed conception that the telencephalon of birds consists nearly entirely of a hypertrophied basal ganglia has been purged, and the actual parts of the basal ganglia and its brainstem afferent cell groups given names reflecting their now-evident mammalian homologues. The pallial telencephalic regions that were erroneously named to reflect presumed homology to mammalian basal ganglia were renamed as parts of pallium, using prefixes in most cases that retained established abbreviations (for continuity with the replaced nomenclature). The new nomenclature should lead to better communication among neuroscientists, especially between avian brain specialists and those not specialized in avian neurobiology. More information is available at the Avian Brain Nomenclature Exchange website ().

Increased calbindin-D28k immunoreactivity in striatal projection neurons of R6/2 Huntington's disease transgenic mice

Striatal degeneration in Huntington's disease (HD) is associated with increases in perikaryal calbindin immunolabeling in yet-surviving striatal projection neurons. Since similar increases have also been observed in surviving striatal projection neurons after intrastriatal injection of the excitotoxin quinolinic acid, the increased calbindin in HD striatum has been interpreted to suggest an excitotoxic process in HD. We used immunolabeling to assess if calbindin is elevated in striatal projection neurons of R6/2 HD transgenic mice. These mice bear exon 1 of the human huntingtin gene with 144 CAG repeats and show some of the neuropathological signs (e.g., neuronal intranuclear inclusions) and clinical traits (e.g., wasting prior to early death) of HD. We found an increased frequency of calbindin-immunoreactive neuronal perikarya in the striatum of 6- and 12-week-old R6/2 mice compared to wild-type controls. This increase was most notable in the normally calbindin-poor dorsolateral striatum. We found no significant changes in the total area of striatum occupied by the calbindin-negative striosomes and no consistent changes in striatal calbindin mRNA. The increase in calbindin in R6/2 striatal neurons was thus limited to the matrix compartment, and it may be triggered by increased Ca2+ entry due to the demonstrated heightened NMDA sensitivity of these neurons. The data further support the similarity of R6/2 mice to HD, and are consistent with the occurrence of an excitotoxic process in striatum in both.

Anatomical and functional evidence for progressive age-related decline in parasympathetic control of choroidal blood flow in pigeons

The choroid receives extensive parasympathetic innervation, which in birds arises largely from the ciliary ganglion (CG). Since age-related changes in parasympathetic regulation of choroidal blood flow (ChBF) could contribute to age-related retinal decline, we used anatomical and functional methods to determine if ChBF control by the CG shows age-related decline in pigeons. The efficacy of the choroidal vasodilatory response to activation of the CG preganglionic input from the medial subdivision of the nucleus of Edinger-Westphal (EWM) was assessed using laser Doppler flowmetry (LDF). The EWM receives bisynaptic retinal input, and electrical stimulation of EWM or light stimulation of the retina in young animals produces dramatic choroidal vasodilation. Transcleral LDF was therefore used to measure both basal ChBF and the increases in ChBF elicited by electrical stimulation of EWM or by retinal illumination in 0.5-18 year old pigeons. Fixed cryostat sections of the eye from 0.5 to 22 year old pigeons were immunolabeled for the 3A10 neurofilament-associated antigen to determine if intrachoroidal nerve fibers arising from CG exhibited age-related loss. We focused on superior choroid, since it is the primary target for CG nerve fibers. There was a marked age-related loss in the ChBF vasodilatory response elicited by either EWM stimulation or retinal illumination, as was also true for basal ChBF. A progressive decrease in choroidal nerve fibers of CG origin, to 17% of youthful abundance by 22 years of age, was also observed. The evoked ChBF increase, and basal ChBF, achieved 50% of their age-related decline between the ages of 3 and 4 years, while half the loss in CG innervation of choroid was later, occurring by 10 years. Age-related loss of choroidal nerve fibers occurs in parallel with but more slowly than the reduction in basal ChBF and the choroidal vasodilation that can be elicited via natural (light) or electrical activation of the central neural input to CG choroidal neurons. The prominent age-related decline in parasympathetic control of ChBF early in the pigeon life span could contribute to the age-related retinal decline observed in pigeons.

The distribution and cellular localization of glutamic acid decarboxylase-65 (GAD65) mRNA in the forebrain and midbrain of domestic chick

The distribution and cellular localization of GAD65 mRNA in the forebrain and midbrain of domestic chick were examined by in situ hybridization histochemistry with (35)[S]-UTP labeled cRNA probes, using film and emulsion autoradiography. Film autoradiograms showed intense GAD65 labeling in many structures of the basal telencephalon, such as the medial and lateral striatum, the septum, the olfactory tubercle, the lateral bed nucleus of the stria terminalis, and the intrapeduncular nucleus, while the pallial telencephalon showed only a low level of labeling. Emulsion-coated sections revealed that GAD65 mRNA-containing neurons were at least six times more abundant in striatum than pallium, with only a uniformly scattered subpopulation labeled in pallium, and that the vast majority of the large scattered projection neurons of globus pallidus were heavily labeled for GAD65. Prominent labeling was also evident in the nucleus taeniae and subpallial amygdala, but not in the arcopallium in film autoradiograms. Within the diencephalon, the hypothalamus was more GAD65-rich than the thalamus. Additional subtelencephalic cell groups showing prominent labeling included the thalamic reticular nucleus and ventral lateral geniculate nucleus of the diencephalon, the nucleus pretectalis, subpretectalis and spiriformis lateralis of the pretectum, and the magnocellular isthmic nucleus of the optic lobe. Tectal layers 9-10 were also rich in GAD65. These results further clarify GABAergic circuits of the avian forebrain and midbrain, and show them to closely resemble those in mammals.

Differential loss of striatal projection systems in Huntington's disease: a quantitative immunohistochemical study

Prior studies suggest differences exist among striatal projection neuron types in their vulnerability to Huntington's disease (HD). In the present study, we immunolabeled the fibers and terminals of the four main types of striatal projection neuron in their target areas for substance P, enkephalin, or glutamic acid decarboxylase (GAD), and used computer-assisted image analysis to quantify the abundance of immunolabeled terminals in a large sample of HD cases ranging from grade 0 to grade 4 [J. Neuropathol. Exp. Neurol. 44 (1985) 559], normalized to labeling in control human brains. Our goal was to characterize the relative rates of loss of the two striatopallidal projection systems (to the internal versus the external pallidal segments) and the two striatonigral projections systems (to pars compacta versus pars reticulata). The findings for GAD and the two neuropeptides were similar--the striatal projection to the external pallidal segment was the most vulnerable, showing substantial loss by grade 1. Loss of fibers in both subdivisions of the substantia nigra was also already great by grade 1. By contrast, the loss in the striatal projection system to the internal segment of globus pallidus proceeded more gradually. By grade 4 of HD, however, profound loss in all projection systems was apparent. These findings support the notion that the striatal neurons preferentially projecting to the internal pallidal segment are, in fact, less vulnerable in HD than are the other striatal projection neuron types.

Discrepancies in current practice of pathological evaluation of sentinel lymph nodes in breast cancer. Results of a questionnaire based survey by the European Working Group for Breast Screening Pathology

AIMS

To evaluate aspects of the current practice of sentinel lymph node (SLN) pathology in breast cancer via a questionnaire based survey, to recognise major issues that the European guidelines for mammography screening should address in the next revision.

METHODS

A questionnaire was circulated by mail or electronically by the authors in their respective countries. Replies from pathology units dealing with SLN specimens were evaluated further.

RESULTS

Of the 382 respondents, 240 European pathology units were dealing with SLN specimens. Sixty per cent of these units carried out intraoperative assessment, most commonly consisting of frozen sections. Most units slice larger SLNs into pieces and only 12% assess these slices on a single haematoxylin and eosin (HE) stained slide. Seventy one per cent of the units routinely use immunohistochemistry in all cases negative by HE. The terms micrometastasis, submicrometastasis, and isolated tumour cells (ITCs) are used in 93%, 22%, and 71% of units, respectively, but have a rather heterogeneous interpretation. Molecular SLN staging was reported by only 10 units (4%). Most institutions have their own guidelines for SLN processing, but some countries also have well recognised national guidelines.

CONCLUSIONS

Pathological examination of SLNs throughout Europe varies considerably and is not standardised. The European guidelines should focus on standardising examination. They should recommend techniques that identify metastases > 2 mm as a minimum standard. Uniform reporting of additional findings may also be important, because micrometastases and ITCs may in the future be shown to have clinical relevance.

Consistency of staining and reporting of oestrogen receptor immunocytochemistry within the European Union—an inter-laboratory study

To assess the variability of oestrogen receptor (ER) testing using immunocytochemistry, centrally stained and unstained slides from breast cancers were circulated to the members of the European Working Group for Breast Screening Pathology, who were asked to report on both slides. The results showed that there was almost complete concordance among readers (kappa=0.95) in ER-negative tumours on the stained slide and excellent concordance among readers (kappa=0.82) on the slides stained in each individual laboratory. Tumours showing strong positivity were reasonably well assessed (kappa=0.57 and 0.4, respectively), but there was less concordance in tumours with moderate and low levels of ER, especially when these were heterogeneous in their staining. Because of the variation, the Working Group recommends that laboratories performing these stains should take part in a external quality assurance scheme for immunocytochemistry, should include a tumour with low ER levels as a weak positive control and should audit the percentage positive tumours in their laboratory against the accepted norms annually. The Quick score method of receptor assessment may also have too many categories for good concordance, and grouping of these into fewer categories may remove some of the variation among laboratories.

Enkephalinergic striatal projection neurons become less affected by quinolinic acid than substance P-containing striatal projection neurons as rats age

While the excitotoxic vulnerability of striatal neurons is known to be greater in juvenile than adult animals, it is uncertain if striatal neuron types decline differentially in their vulnerability with age. To examine this issue, we unilaterally injected quinolinic acid (QA), an N-methyl-d-aspartate (NMDA) receptor agonist, into the striatum of juvenile and adult rats, and used in situ hybridization histochemistry with oligonucleotide probes for preproenkephalin and preprotachykinin mRNA to label surviving enkephalinergic (ENK) and substance P-containing (SP) neurons in adjacent sections through the injection center. The results confirmed that the region of severe damage is greater in young than adult animals, but revealed that at the very center of the QA injection, labeled neuron abundance was lower in adult than juvenile striatum. In juvenile rats, the vulnerability of the ENK neurons at all distances from the injection center was the same as that of the SP neurons. By contrast, in adult rats, the ENK neuron survival was greater than the SP neuron survival at all distances beyond the lesion center. The SP neuron survival outside the injection center in the adult rats was similar to that in juvenile rats, while the ENK neuron survival beyond the injection center was better in adult than juvenile rats. These data indicate that there is an age-dependent decrease in the vulnerability of ENK but not SP striatal projection neurons to QA-mediated injury in rats. The results also raise the possibility that, if an excitotoxic process is involved in HD pathogenesis, a differential age-related decline in the sensitivity of striatal projection neuron types to this process may contribute to the more uniform striatal neuron loss in juvenile-onset Huntington's disease (HD) and the more differential loss in adult-onset HD.

Evidence that urocortin is absent from neurons of the Edinger-Westphal nucleus in pigeons

The Edinger-Westphal nucleus (EWN) is a central preganglionic parasympathetic cell group that gives rise to cholinergic input to the ciliary ganglion, thereby regulating several neurovegetative ocular functions. Recently, the supposed presence of the neuropeptide urocortin (UCN) has been reported in EWN neurons in rodent brain. The purpose of the present study was to examine the distribution of UCN in avian brain and to investigate by immunohistochemical analysis the possible use of this substance as an EWN marker in a non-mammalian class of vertebrates. Brain tissue of pigeons was incubated with a specific antibody against UCN and the results showed labeling of many small neurons, forming a double wing in the dorsal mesodiencephalic transition area. Their size and shape, however, differed from those of EWN neurons, and they were preferentially located rostral to the EWN. Double-label experiments employing an antibody against the enzyme choline acetyltransferase (ChAT) showed that UCN is not localized to the cholinergic cells of the EWN and confirmed the rostral distributionof UCN never overlapping the ChAT+ EWN cells. Taken together, these results suggest that, at least in pigeons, the UCN+ population does not belong to the traditionally defined EWN.

Embryoscopic and cytogenetic analysis of 233 missed abortions: factors involved in the pathogenesis of developmental defects of early failed pregnancies

BACKGROUND

While chromosomal abnormalities are often the cause of missed abortions, other defects could be involved, which might be screened for by transcervical embryoscopy.

METHODS

A total of 272 patients with missed abortion underwent transcervical embryoscopy prior to dilatation and curettage, together with cytogenetic analysis of chorionic villi, using either standard G-banding cytogenetic techniques or comparative genomic hybridization in combination with flow cytometry analysis.

RESULTS

Visualization of the embryo or early fetus (12 cases) was successful in 233 patients, and karyotyping in 221. Among 233 examined cases, 33 had normal external features, 71 were classified as growth-disorganized and 129 had either isolated or multiple defects, including holoprosencephaly, anencephaly, encephalocele, spina bifida, microcephaly, facial dysplasia, limb reduction defect, cleft hand, syndactyly, pseudosyndactly, polydactyly, various forms of cleft lip and an amniotic adhesion. Of the 165 cases with an abnormal karyotype, there were 46 grossly disorganized embryos, 98 multiple defects, six single defects and 15 morphologically normal cases. Of the 56 cases with a normal karyotype, there were 20 grossly disorganized embryos, 16 multiple defects, four single defects and 16 morphologically normal cases.

CONCLUSIONS

A total of 75% of the cases with missed abortion had an abnormal karyotype, 18% had a morphological defect with a normal karyotype, while no embryonic or chromosomal abnormality could be diagnosed in 7% of the cases. Correlation of morphological and cytogenetic findings in spontaneous abortion specimens could provide valuable information for genetic counselling and prenatal care in future pregnancies in couples with a history of repeated pregnancy loss.

Pathological work-up of sentinel lymph nodes in breast cancer. Review of current data to be considered for the formulation of guidelines

Controversies and inconsistencies regarding the pathological work-up of sentinel lymph nodes (SNs) led the European Working Group for Breast Screening Pathology (EWGBSP) to review published data and current evidence that can promote the formulation of European guidelines for the pathological work-up of SNs. After an evaluation of the accuracy of SN biopsy as a staging procedure, the yields of different sectioning methods and the immunohistochemical detection of metastatic cells are reviewed. Currently published data do not allow the significance of micrometastases or isolated tumour cells to be established, but it is suggested that approximately 18% of the cases may be associated with further nodal (non-SN) metastases, i.e. approximately 2% of all patients initially staged by SN biopsy. The methods for the intraoperative and molecular assessment of SNs are also surveyed.

Choroidal blood flow in pigeons compensates for decreases in arterial blood pressure

While it had once been thought that choroidal blood flow (ChBF) does not compensate for changes in perfusion pressure, recent studies have shown that ChBF in rabbits and humans does compensate for changes in arterial blood pressure (ABP) and thereby remains relatively stable within a physiological range of ABPs. In this study, we sought to determine if ChBF in birds can compensate for decreases in ABP, either spontaneously occuring or caused by blood withdrawal. ChBF was continuously monitored using laser Doppler flowmetry in anesthetized pigeons, and at the same time ABP was measured via the brachial artery. In studies of spontaneous fluctuation in ABP, ChBF and ABP were analyzed at regular intervals over a 2-3 hr period, while for blood withdrawal studies, blood was transiently withdrawn via the brachial artery. In both paradigms, ChBF remained near baseline over an ABP range from basal (about 90 mmHg) to about 55 mmHg, followed ABP nearly linearly below 50 mmHg, and showed no compensation below 40 mmHg. The blood withdrawal studies further showed that the compensation was more rapid with small acute declines in ABP than with larger declines. These findings reveal that ChBF in pigeons, as in rabbits and humans, compensates for declines in ABP so as to remain relatively stable within a physiological range of ABPs. Given the phylogenetic distance between humans and rabbits on one hand and birds on the other, these results suggest that choroidal compensation for ABP declines may be a common ocular mechanism among warm-blooded vertebrates.

Transcervical fetoscopic diagnosis of structural defects in four first-trimester monochorionic twin intrauterine deaths

OBJECTIVE

While chromosomal abnormalities are often the cause of early failed pregnancies, other mechanisms could be involved in monochorionic twin intrauterine deaths, that might be screened for careful morphological analysis.

METHODS

Transcervical fetoscopy prior to instrumental evacuation of the uterus was performed in four first-trimester monochorionic twin intrauterine deaths.

RESULTS

We present fetoscopic and cytogenetic findings in four cases of monochorionic twin intrauterine deaths. In the first, generalized abnormal embryonic development observed in both twins was a manifestation of trisomy 20. The second (thoracophagus) and third (acardius) pair of twins had anomalies peculiar to multiple gestations. The fourth pair of twins was remarkable because of the concordance for the observed limb-reduction defects.

CONCLUSION

Malformations of first-trimester monochorionic twin intrauterine deaths might cover a wide spectrum of etiologies from abnormal chromosomes and single gene defects to rare duplication anomalies. Their detection by careful morphological analysis and the identification of a specific mechanism provides valuable information for genetic counseling and prenatal investigation in a future pregnancy.

Differential changes in striatal projection neurons in R6/2 transgenic mice for Huntington's disease

In early adult-onset Huntington's disease (HD), enkephalinergic striatopallidal projection neurons show preferential loss, reduced preproenkephalin (PPE) expression in surviving striatopallidal neurons, and loss of fibers in their projection target area. We examined PPE and PPT (preprotachykinin) gene expression in striatal projection neurons and in striatal projection fibers immunoreactive for the PPE product enkephalin (ENK) and the PPT product substance P (SP) in a transgenic HD model, the R6/2 mouse, to see if changes occur in these neuron types similar to those seen in early adult-onset HD. The results show that PPE mRNA level, the number of striatal neurons expressing PPE, and the staining intensity of fibers immunoreactive for ENK in the pallidum were all decreased. By contrast, the SP-containing striatal projection systems to the pallidum and substantia nigra were relatively normal in R6/2 mice. The selective reduction in striatal PPE in R6/2 mice is reminiscent of adult-onset HD, but the preservation of the striatonigral projection system is not. Thus, R6/2 mice do not strictly mimic adult-onset HD in their striatal pathology.

Excessive degradation of type II collagen in articular cartilage in equine osteochondrosis

Articular osteochondrosis (OCD) occurs in both man and animals. The etiology remains to be determined. Studies of OCD lesions in animals may provide clues as to its pathogenesis. The aim of our study was to determine whether there was evidence for increased degradation namely proteoglycan (PG) release and type II collagen cleavage in articular cartilage harvested from OCD lesions. We examined ex vivo explants at post-mortem from equine OCD lesions and macroscopically normal site and age matched cartilage. These were cultured over a 10 day period in serum-free medium. Type II collagen cleavage was measured in articular cartilage and media using an Elisa assay to detect the COL2-3/4C(short) epitope, which is generated on cleavage of the triple helix of type II collagen by collagenases. PG release was measured by a dye-binding assay. Cumulative release of PG and COL2-3/4C(short) and their contents in cartilage at the end of the culture period were determined. In OCD lesions there was a significant increase in type II collagen cleavage by collagenase but no evidence for increase of PG degradation. These findings point to a selective increase in type II collagen cleavage by collagenases, in OCD lesions of the kind observed in osteoarthritis. Further work is needed to determine whether changes represent primary or secondary events in the pathogenesis of OCD.

The differential vulnerability of striatal projection neurons in 3-nitropropionic acid-treated rats does not match that typical of adult-onset Huntington's disease

In adult-onset Huntington's disease (HD), striatal projection neurons are much more vulnerable than striatal interneurons, but even striatal projection neurons show differences in their vulnerability, with the striatal projection neurons projecting to the internal segment of the globus pallidus being the least vulnerable. Previous studies have shown that systemic chronic treatment with 3-nitropropionic acid (3NP), an inhibitor of succinate dehydrogenase, induces the preferential loss of striatal projection neurons over striatal interneurons that is characteristic of HD, which has been taken to support the hypothesis that the pathogenic defect in HD may involve impaired energy metabolism. We sought to determine whether the patterns of survival for striatal projection neurons in 4-month-old rats after chronic systemic 3NP treatment also resemble those in adult-onset HD. We assessed the projection neuron survival using neuropeptide immunolabeling of striatal efferent fibers in striatal target areas and quantified the degree of fiber loss in the striatal target areas using computer-assisted image analysis. We found that 3NP produced relatively equal loss of striatal fibers and terminals in the globus pallidus, substantia nigra, and entopeduncular nucleus, indicating a nondifferential vulnerability of striatal projection neurons to 3NP-induced impairment in energy metabolism. The results suggest that the 3NP rat model does not fully mimic adult-onset HD pathogenesis.

Physiology and morphology of intratelencephalically projecting corticostriatal-type neurons in pigeons as revealed by intracellular recording and cell filling

Much of the Wulst and dorsal ventricular ridge (DVR) in birds, which together make up the part of the avian telencephalon functionally resembling mammalian cerebral cortex, projects to the striatum. Those connections arise from neurons projecting additionally to the brainstem as well as from neurons projecting only within the telencephalon. As part of an effort to further characterize corticostriatal-type projection neurons in birds, we recorded intracellularly from neurons of the outer DVR, identified neurons projecting to the striatum by antidromic stimulation from the ipsilateral rostromedial striatum or subsequently by their axonal projection, characterized these neurons physiologically and then filled them with biocytin. As neurons in the outer DVR only project within telencephalon, neurons within it projecting to the striatum are of the intratelencephalically projecting (IT) type. Our studies suggest that: (1) the membrane potentials of avian IT-type neurons fluctuate between two preferred subthreshold values, and action potentials occur only in the 'up' state, (2) avian IT-type neurons show a time-dependent inward rectification in response to hyperpolarization and regular firing in response to constant current injection, (3) the conduction velocity of avian IT-type neurons is slow (about 0.2 m/s), (4) avian IT-type neurons possess radially disposed densely spiny dendrites but no apical dendrite, (5) avian IT-type neurons have local and distant collateral projections within the DVR, and (6) individual avian IT-type neurons give rise to an extensive terminal field within the striatum. Aside from the shape of their dendritic tree, IT-type neurons in birds closely resemble IT-type corticostriatal neurons in mammals in these various aspects, although it is presently uncertain whether this neuron type has been inherited in common by birds and mammals from stem amniotes.

Design of a retroviral-mediated ecdysone-inducible system and its application to the expression profiling of the PTEN tumor suppressor

We have engineered the ecdysone-inducible mammalian expression system for general retroviral delivery to cultured mammalian cells. We inducibly expressed PTEN in the glioblastoma cell line, U87MG, lacking this gene. Because nearly all cells are recruited on induction, we find both up- and down-regulated genes by cDNA microarray analysis. The changes we see are similar to those observed after treatment with LY294002, an inhibitor of phosphatidylinositol 3-OH kinase, fully consistent with the model that PTEN antagonizes phosphatidylinositol 3-OH kinase. Both treatments result in suppressed expression of the transforming growth factor (TGF)-beta gene and the genes of the cholesterol biosynthesis pathway. Our results illustrate the power of using a fully inducible expression system in conjunction with cDNA microarray analysis for exploring gene function.