An emerging role for prdm family genes in dorsoventral patterning of the vertebrate nervous system

The embryonic vertebrate neural tube is divided along its dorsoventral (DV) axis into eleven molecularly discrete progenitor domains. Each of these domains gives rise to distinct neuronal cell types; the ventral-most six domains contribute to motor circuits, while the five dorsal domains contribute to sensory circuits. Following the initial neurogenesis step, these domains also generate glial cell types-either astrocytes or oligodendrocytes. This DV pattern is initiated by two morphogens-Sonic Hedgehog released from notochord and floor plate and Bone Morphogenetic Protein produced in the roof plate-that act in concentration gradients to induce expression of genes along the DV axis. Subsequently, these DV-restricted genes cooperate to define progenitor domains and to control neuronal cell fate specification and differentiation in each domain. Many genes involved in this process have been identified, but significant gaps remain in our understanding of the underlying genetic program. Here we review recent work identifying members of the Prdm gene family as novel regulators of DV patterning in the neural tube. Many Prdm proteins regulate transcription by controlling histone modifications (either via intrinsic histone methyltransferase activity, or by recruiting histone modifying enzymes). Prdm genes are expressed in spatially restricted domains along the DV axis of the neural tube and play important roles in the specification of progenitor domains, as well as in the subsequent differentiation of motor neurons and various types of interneurons. Strikingly, Prdm proteins appear to function by binding to, and modulating the activity of, other transcription factors (particularly bHLH proteins). The identity of key transcription factors in DV patterning of the neural tube has been elucidated previously (e.g. the nkx, bHLH and pax families), but it now appears that an additional family is also required and that it acts in a potentially novel manner

prdm12b specifies the p1 progenitor domain and reveals a role for V1 interneurons in swim movements

AbstractProper functioning of the vertebrate central nervous system requires the precise positioning of many neuronal cell types. This positioning is established during early embryogenesis when gene regulatory networks pattern the neural tube along its anteroposterior and dorsoventral axes. Dorsoventral patterning of the embryonic neural tube gives rise to multiple progenitor cell domains that go on to differentiate unique classes of neurons and glia. While the genetic program is reasonably well understood for some lineages, such as ventrally derived motor neurons and glia, other lineages are much less characterized. Here we show that prdm12b, a member of the PR domain containing-family of transcriptional regulators, is expressed in the p1 progenitor domain of the zebrafish neural tube in response to Sonic Hedgehog signaling. We find that disruption of prdm12b function leads to dorsal expansion of nkx6.1 expression and loss of p1-derived eng1b-expressing V1 interneurons, while the adjacent p0 and p2 domains are unaffected. We also demonstrate that prdm12b-deficient fish exhibit an abnormal touch-evoked escape response with excessive body contractions and a prolonged response time, as well as an inability to coordinate swimming movements, thereby revealing a functional role for V1 interneurons in locomotor circuits. We conclude that prdm12b is required for V1 interneuron specification and that these neurons control swimming movements in zebrafish

Targeted germ line disruptions reveal general and species-specific roles for paralog group 1 hox genes in zebrafish

BACKGROUND: The developing vertebrate hindbrain is transiently segmented into rhombomeres by a process requiring Hox activity. Hox genes control specification of rhombomere fates, as well as the stereotypic differentiation of rhombomere-specific neuronal populations. Accordingly, germ line disruption of the paralog group 1 (PG1) Hox genes Hoxa1 and Hoxb1 causes defects in hindbrain segmentation and neuron formation in mice. However, antisense-mediated interference with zebrafish hoxb1a and hoxb1b (analogous to murine Hoxb1 and Hoxa1, respectively) produces phenotypes that are qualitatively and quantitatively distinct from those observed in the mouse. This suggests that PG1 Hox genes may have species-specific functions, or that anti-sense mediated interference may not completely inactivate Hox function in zebrafish. RESULTS: Using zinc finger and TALEN technologies, we disrupted hoxb1a and hoxb1b in the zebrafish germ line to establish mutant lines for each gene. We find that zebrafish hoxb1a germ line mutants have a more severe phenotype than reported for Hoxb1a antisense treatment. This phenotype is similar to that observed in Hoxb1 knock out mice, suggesting that Hoxb1/hoxb1a have the same function in both species. Zebrafish hoxb1b germ line mutants also have a more severe phenotype than reported for hoxb1b antisense treatment (e.g. in the effect on Mauthner neuron differentiation), but this phenotype differs from that observed in Hoxa1 knock out mice (e.g. in the specification of rhombomere 5 (r5) and r6), suggesting that Hoxa1/hoxb1b have species-specific activities. We also demonstrate that Hoxb1b regulates nucleosome organization at the hoxb1a promoter and that retinoic acid acts independently of hoxb1b to activate hoxb1a expression. CONCLUSIONS: We generated several novel germ line mutants for zebrafish hoxb1a and hoxb1b. Our analyses indicate that Hoxb1 and hoxb1a have comparable functions in zebrafish and mouse, suggesting a conserved function for these genes. In contrast, while Hoxa1 and hoxb1b share functions in the formation of r3 and r4, they differ with regards to r5 and r6, where Hoxa1 appears to control formation of r5, but not r6, in the mouse, whereas hoxb1b regulates formation of r6, but not r5, in zebrafish. Lastly, our data reveal independent regulation of hoxb1a expression by retinoic acid and Hoxb1b in zebrafish

Increased cortical excitability after selective REM sleep deprivation in healthy humans: a transcranial magnetic stimulation study

REM sleep has antiepileptogenic properties whereas, its loss is known to have a proconvulsive role. However, the mechanisms underlying the proepileptogenic effects of REM sleep deprivation are yet not fully understood. The aim of our study was to evaluate the effects of selective REM sleep deprivation (SRD) on cortical excitability in healthy subjects by means of transcranial magnetic stimulation (TMS)

Intentional and automatic measures of specific-category effect in the semantic impairment of patients with Alzheimer's disease

The breakdown of semantic knowledge relative to living and non-living categories was studied in patients with Alzheimer's disease (AD). The same living and non-living items were used in a semantic battery and in a semantic priming paradigm exploring automatic access to the semantic system. Although AD patients showed a semantic deficit on the intentional semantic battery, they demonstrated normal semantic facilitation on the priming task. In the AD group as a whole, the semantic impairment did not preferentially affect the living category either in the intentional or automatic condition. Instead, a prevalent deficit for the living category was found in three AD patients (14% of the group) on the intentional semantic tasks, but not on the automatic one. These findings support the view that the category effect may not be a generalised phenomenon in AD but may be restricted to a limited number of patients. The intentional/automatic dissociation of the semantic breakdown demonstrated by AD patients is discussed in relation to different theories regarding the organisation of semantic memory

Sentinel-lymph-node-based management or routine axillary clearance? Three-year outcomes of the RACS Sentinel Node Biopsy versus Axillary Clearance (SNAC) 1 trial

Purpose We sought to determine whether the benefits of sentinel-node-based management (SNBM) over routine axillary clearance (RAC) at 1 year persisted to 3 years of follow-up. Methods 1088 women with clinically node negative breast cancer were randomly assigned to SNBM versus RAC. Upper limb volume, symptoms and function were assessed at 1, 6, 12, 24 and 36 months after surgery objectively with upper limb measurements by clinicians, and subjectively by patients’ using validated self-rating scales. Results Upper limb volume increased in both groups over the first 2 years and differed between the two groups all time points beyond 1 month (P<0.02), but then plateaued. Upper limb swelling was no worse in women who had axillary clearance as two-stage procedure than in women assigned RAC as a one-stage procedure. Upper limb volume had increased 15% or more in 6.0% at 6 months and 17.6% at 3 years in those assigned RAC versus 4.2% and 11.9% in those assigned SNBM. Reductions in upper limb movement were also greater with RAC than SNBM over 6 months, but improved and were similar in the two groups from 1 to 3 years. Subjective ratings of upper limb swelling, symptoms, dysfunction, and disability over 3 years were worse in the RAC group. Upper limb swelling at 3 years was rated severe by few women (1.1%), but moderate by 9.4% in the RAC group and 2.5% in the SNBM group (P<0.001). Conclusions The benefits of SNBM over RAC persist 3 years after surgery.Royal Australasian College of Surgeon

The cost effectiveness of bevacizumab when added to capecitabine, with or without mitomycin-C, in first line treatment of metastatic colorectal cancer: results from the Australasian phase III MAX study

Background: Based on the clinical data, bevacizumab has been approved in Australia and globally for the treatment of advanced colorectal cancer. However, limited evidence exists for its cost-effectiveness. The purpose of this study was to evaluate the cost effectiveness of adding bevacizumab to capecitabine monotherapy in patients with metastatic colorectal cancer, using data from the prospective economic evaluation conducted alongside the MAX trial. Methods: Individual patient level data on resource use and progression free survival were prospectively collected in the phase III MAX trial. Resource use data were collected for the period between randomisation and disease progression, and unit costs were assigned from the perspective of the Australian health care funder. Effectiveness was measured in quality adjusted progression free survival years, with utility scores obtained from both the community valued EQ-5D questionnaire and the patient valued UBQ-C questionnaire. Progression free survival was used as a secondary effectiveness measure. Results: The addition of bevacizumab to capecitabine monotherapy cost approximately $192,156 (95$135,619 to $326,894) per quality adjusted progression free survival year gained when using publicly listed pharmaceutical prices and utility values from the EQ-5D questionnaire. This decreased to$149,455 (95% CI, $100,356 to$245,910) when values from the UBQ-C questionnaire were applied. The incremental cost per progression free survival year was $145,059 (95$106,703 to $233,225). Conclusions: Bevacizumab was not found to be cost effective at its listed price, based on results from the MAX trial.Roche Products Pty Lt

The cost effectiveness of bevacizumab when added to capecitabine, with or without mitomycin-C, in first line treatment of metastatic colorectal cancer: results from the Australasian phase III MAX study

Background: Based on the clinical data, bevacizumab has been approved in Australia and globally for the treatment of advanced colorectal cancer. However, limited evidence exists for its cost-effectiveness. The purpose of this study was to evaluate the cost effectiveness of adding bevacizumab to capecitabine monotherapy in patients with metastatic colorectal cancer, using data from the prospective economic evaluation conducted alongside the MAX trial. Methods: Individual patient level data on resource use and progression free survival were prospectively collected in the phase III MAX trial. Resource use data were collected for the period between randomisation and disease progression, and unit costs were assigned from the perspective of the Australian health care funder. Effectiveness was measured in quality adjusted progression free survival years, with utility scores obtained from both the community valued EQ-5D questionnaire and the patient valued UBQ-C questionnaire. Progression free survival was used as a secondary effectiveness measure. Results: The addition of bevacizumab to capecitabine monotherapy cost approximately $192,156 (95$135,619 to $326,894) per quality adjusted progression free survival year gained when using publicly listed pharmaceutical prices and utility values from the EQ-5D questionnaire. This decreased to$149,455 (95% CI, $100,356 to$245,910) when values from the UBQ-C questionnaire were applied. The incremental cost per progression free survival year was $145,059 (95$106,703 to $233,225). Conclusions: Bevacizumab was not found to be cost effective at its listed price, based on results from the MAX trial.Roche Products Pty Lt

Changes in genotoxic stress response, ribogenesis and PAP (3’-phosphoadenosine 5’-phosphate) levels are associated with loss of desiccation tolerance in overprimed Medicago truncatula seeds

Re‐establishment of desiccation tolerance is essential for the survival of germinated seeds facing water deficit in the soil. The molecular and ultrastructural features of desiccation tolerance maintenance and loss within the nuclear compartment are not fully resolved. In the present study, the impact of desiccation‐induced genotoxic stress on nucleolar ultrastructure and ribogenesis was explored along the rehydration−dehydration cycle applied in standard seed vigorization protocols. Primed and overprimed Medicago truncatula seeds, obtained through hydropriming followed by desiccation (dry‐back), were analysed. In contrast to desiccation‐tolerant primed seeds, overprimed seeds enter irreversible germination and do not survive dry‐back. Reactive oxygen species, DNA damage and expression profiles of antioxidant/DNA Damage Response genes were measured, as main hallmarks of the seed response to desiccation stress. Nuclear ultrastructural features were also investigated. Overprimed seeds subjected to dry‐back revealed altered rRNA accumulation profiles and up‐regulation of genes involved in ribogenesis control. The signal molecule PAP (3′‐phosphoadenosine 5′‐phosphate) accumulated during dry‐back only in primed seeds, as a distinctive feature of desiccation tolerance. The presented results show the molecular and ultrastructural landscapes of the seed desiccation response, including substantial changes in nuclear organization