Factors Influencing Objective and Subjective Prospective Memory Measures in Traumatic Brain Injury.

OBJECTIVE: To accurately assess prospective memory (PM) functioning in patients who sustained a traumatic brain injury (TBI), it is important to use both subjective (questionnaires) and objective (tests) measures. However, which factors have the most significant effect on each PM measure remains unknown. This observational study aims to verify whether TBI severity or psychological status has the most influence on patients' objective and subjective PM measures. METHOD: Fifteen healthy control (HC) participants (n = 15), 19 patients with a mild TBI (n = 19) and 30 patients with a moderate-to-severe TBI (n = 30) were recruited during the post-acute phase. For almost every participant, a relative was also recruited (n = 62). The Test écologique de mémoire prospective (TEMP), an objective computerized PM measure consisting of naturalistic stimuli, was administered to all participants along with anxiety (BAI) and depression inventories (BDI). Participants and their relatives also completed a questionnaire, the comprehensive assessment of PM (CAPM), a subjective PM measure assessing everyday failures. RESULTS: Results on the objective PM measure were predicted by TBI severity, while psychological symptoms (BAI and BDI) predicted scores on the subjective PM measure. In addition, relatives in the moderate-to-severe TBI group reported more PM failures on the subjective measure and their perception was significantly correlated with results on the objective PM measure, which was not the case for the other two groups of relatives. CONCLUSIONS: Objective PM measures are related to TBI severity and appear more robust against the influence of psychological factors than subjective PM measures.

Testing detectability, attractivity, hedonic specificity, extractability, and robustness of colostrum odor-Toward an olfactory bioassay for human neonates.

Human milk odor is attractive and appetitive for human newborns. Here, we studied behavioral and heart-rate (HR) responses of 2-day-old neonates to the odor of human colostrum. To evaluate detection in two conditions of stimulus delivery, we first presented the odor of total colostrum against water. Second, the hedonic specificity of total colostrum odor was tested against vanilla odor. Third, we delivered only the fresh effluvium of colostrum separated from the colostrum matrix; the stability of this colostrum effluvium was then tested after deep congelation; finally, after sorptive extraction of fresh colostrum headspace, we assessed the activity of colostrum volatiles eluting from the gas chromatograph (GC). Regardless of the stimulus-delivery method, neonates displayed attraction reactions (HR decrease) as well as appetitive oral responses to the odor of total colostrum but not to vanilla odor. The effluvium separated from the fresh colostrum matrix remained appetitive but appeared labile under deep freezing. Finally, volatiles from fresh colostrum effluvium remained behaviorally active after GC elution, although at lower magnitude. In sum, fresh colostrum effluvium and its eluate elicited a consistent increase in newborns' oral activity (relative to water or vanilla), and they induced shallow HR decrease. Newborns' appetitive oral behavior was the most reproducible response criterion to the effluvium of colostrum. In conclusion, a set of unidentified volatile compounds from human colostrum is robust enough after extraction from the original matrix and chromatographic processing to continue eliciting appetitive responses in neonates, thus opening new directions to isolate and assay specific volatile molecules of colostrum.

Building Families' Capacities: Community Forums with Parents and Occupational Therapists.

Background. Parents of a child considered to have special needs are at greater risk of stress and exhaustion. Although many occupational therapy interventions can help these children, they often require significant time and energy from families. Purpose. To document the perspectives of parents and occupational therapists regarding ways to offer services that help build families' capacities without overloading them. Method. A qualitative descriptive design guided online community forums with 41 parents and occupational therapists in Quebec, Canada. Findings. Nine key principles to build the capacities of families without overburdening them were identified. These include being sensitive to possible negative impacts of services, avoiding overwhelming the family with information or recommendations, taking the needed time, highlighting the positive, and offering flexible conditions for services. Implications. Our findings help identify how capacity-building rehabilitation services can be offered to families to optimize positive outcomes and minimize harms.

The negative influence of chronic alcohol abuse on acute cognitive recovery after a traumatic brain injury.

OBJECTIVE: Cognitive recovery after a traumatic brain injury (TBI) may be negatively affected by a prior alcohol use disorder (AUD). This study aims to compare the cognitive recovery of patients who had comorbid TBI and AUD relative to TBI alone and investigate the influence of blood alcohol level (BAL) at hospital admission on this recovery. METHOD: The sample consisted of 42 patients who had sustained a TBI (mild or moderate) and had an AUD diagnosis (TBI+AUD), and 42 patients who had sustained a TBI alone (TBI). The Brief Cognitive Exam in Traumatology (EXACT), designed to evaluate cognitive functions in the acute phase of TBI was administered (± 2 weeks post-injury). RESULTS: After controlling for BAL at admission, the TBI+AUD group had a lower EXACT total score compared to the TBI group. The negative influence of age on the results was more pronounced in the TBI+AUD group. The number of intoxicated patients at admission was also higher in this group, although there was no correlation between BAL at admission and cognitive outcome. CONCLUSION: The presence of an AUD diagnosis seems to exert a greater negative influence on cognitive recovery following a mild/moderate TBI than BAL at admission, especially in older patients.

Comparative Investigation of Conventional and Innovative Headspace Extraction Methods to Explore the Volatile Content of Human Milk.

The odor of human milk induces search-like movements and oral activation in newborns, which increases their chances of taking advantage of milk intake and benefits. However, the underlying volatile fraction of human milk remains understudied. This study aimed to devise a simple method to extract a wide range of volatile compounds from small-volume human milk samples. Headspace solid phase micro-extraction (HS-SPME) with a Car/PDMS fiber and dynamic headspace extraction (D-HS) with a Tenax or a trilayer sorbent were tested because of their selective affinity for volatiles. Then, innovative variations of these methods were developed to combine their respective advantages in a one-step extraction: Static headspace with multiple SPME fibers (S-HS-MultiSPME), Dynamic headspace with multiple SPME fibers (D-HS-MultiSPME) and dynamic headspace with multiple SPME fibers and Tenax (D-HS-MultiSPME/Tenax). The extracts were analyzed by gas chromatography coupled with mass spectrometric and flame ionization detection. The relative performances of these methods were compared based on qualitative and semi-quantitative analyses of the chromatograms. The D-HS technique showed good sensitivity for most compounds, whereas HS-SPME favored the extraction of acids. The D-HS-MultiSPME/Tenax identified more than 60 compounds from human milk (some for the first time) and evidence of individual singularities. This method that can be applied to volatilome analysis of any biological fluid should further our understanding of human milk odor.

Cognitive profiles in the acute phase of traumatic brain injury according to injury severity.

Although several studies have documented the chronic phase of traumatic brain injury (TBI), few verified the nature and severity of cognitive impairments during the acute phase. Among the studies carried out during the acute phase, instrumental functions were rarely examined compared to attention, memory, and executive functions. This study aimed to compare the nature and intensity of cognitive problems in the acute phase according to TBI severity and age. It was hypothesized that cognitive impairments would increase in line with TBI severity and age, and that instrumental functions would be less affected in victims of mild or moderate TBI than in those with severe TBI. The Brief Cognitive Exam in Traumatology (EXACT), a new and reliable test specifically designed and validated to briefly assess global cognitive functioning during the acute phase, was administered to 319 mild to severe TBI victims (aged 16 to 96 years), within three months post-accident. The EXACT evaluates five domains: Language, Instrumental functions (other than language), Attention and working memory, Episodic memory, and Executive functions and behavioral regulation. Results confirmed the negative influence of TBI severity and age on global cognitive functioning. Also, compared to victims with a mild or moderate TBI, a higher proportion of those with a severe TBI presented impaired instrumental functions (calculation, praxis, and gnosis). Thus, during the acute phase, the nature and severity of cognitive impairments vary according to TBI severity.

Farnesylation and lipid unsaturation are critical for the membrane binding of the C-terminal segment of G-Protein Receptor Kinase 1.

Many proteins are modified by the covalent addition of different types of lipids, such as myristoylation, palmitoylation and prenylation. Lipidation is expected to promote membrane association of proteins. Visual phototransduction involves many lipid-modified proteins. The G-Protein-coupled receptor of rod photoreceptors, rhodopsin, is inactivated by G-Protein-coupled Receptor Kinase 1 (GRK1). The C-terminus of GRK1 is farnesylated and its truncation has been shown to result in a very high decrease of its enzymatic activity, most likely because of the loss of its membrane localization. Little information is available on the membrane binding of GRK1 as well as of most prenylated proteins. Measurements of the membrane binding of the non-farnesylated and farnesylated C-terminal segment of GRK1 were thus performed using lipids typical of those found in rod outer segment disk membranes. Their random coil secondary structure was determined using circular dichroism and infrared spectroscopy. The non-farnesylated C-terminal segment of GRK1 has no surface activity. In contrast, the farnesylated C-terminal segment of GRK1 shows a particularly strong binding to lipid monolayers bearing at least one unsaturated fatty acyl chain. No binding is observed in the presence of monolayers of saturated phospholipids, in agreement with the low affinity of farnesylated Ras proteins for lipids in the liquid-ordered state. Altogether, these data demonstrate that the farnesyl group of the C-terminal segment of GRK1 is mandatory for its membrane binding, which is favored by particular lipids or lipid mixtures. This information will also be useful for the understanding of the membrane binding of other prenylated proteins.

Membrane binding properties of the C-terminal segment of retinol dehydrogenase 8.

Light absorption by rhodopsin leads to the release of all-trans retinal (ATRal) in the lipid phase of photoreceptor disc membranes. Retinol dehydrogenase 8 (RDH8) then reduces ATRal into all-trans retinol, which is the first step of the visual cycle. The membrane binding of RDH8 has been postulated to be mediated by one or more palmitoylated cysteines located in its C-terminus. Different peptide variants of the C-terminus of RDH8 were thus used to obtain information on the mechanism of membrane binding of this enzyme. Steady-state and time-resolved fluorescence measurements were performed using short and long C-terminal segments of bovine RDH8, comprising one or two tryptophan residues. The data demonstrate that the amphipathic alpha helical structure of the first portion of the C-terminus of RDH8 strongly contributes to its membrane binding, which is also favored by palmitoylation of at least one of the cysteines located in the last portion of the C-terminus.

Clinical validation of time reduction strategy in continuous step-and-shoot mode during SPECT acquisition.

BACKGROUND: The SwiftScan solution (General Electric Healthcare) combines a new low-energy high-resolution sensitivity collimator and a tomographic step-and-shoot continuous (SSC) mode acquisition. The purpose of this study is to determine whether SSC mode can be used in clinical practice with shorter examination times, while preserving image quality and ensuring accurate semi-quantification. Twenty bone scan and 10 lung scan studies were randomly selected over a period of 2 months. Three sets of image datasets were produced: step-and-shoot (SS) acquisition, simulated 25% count reduction using the Poisson resampling method (SimSS), and SimSS continuous acquisition (SimSSC), where SimSS was summed with counts acquired during detector head rotation. Visual assessment (5-point Likert scale, 2 readers) and semi-quantitative evaluation (50 focal uptake from 10 bone studies), assessed by SUVmean, coefficient of variation (COV), and contrast-to-noise ratio (CNR), were performed using t test and Bland-Altman analysis. RESULTS: Intra-reader agreement was substantial for reader 1 (k = 0.71) and for reader 2 (k = 0.61). Inter-reader agreement was substantial for SS set (k = 0.93) and moderate for SimSSC (k = 0.52). Bland-Altman analysis showed a good interchangeability of SS and SimSSC SUV values. The mean CNR between SS and SimSSC was not significantly different: 42.9 ± 43.7 [23.7-62.1] vs. 43.1 ± 46 [22.9-63.3] (p = 0.46), respectively. COV values, assessing noise level, did not deviate significantly between SS and SimSSC: 0.20 ± 0.08 [0.18-0.23] vs. 0.21 ± 0.08, [0.18-0.23] (p = 0.15), respectively, whereas a significant difference was demonstrated between SS and SimSS: 0.20 ± 0.08 [0.18-0.23] vs. 0.23 ± 0.09 [0.20-0.25] (p < 0.0001), respectively. CONCLUSIONS: SSC mode acquisition decreases examination time by approximately 25% in bone and lung SPECT/CT studies compared to SS mode (~ 2 min per single-bed SPECT), without compromising image quality and signal quantification. This SPECT sensitivity improvement also offers the prospect of more comfortable exams, with less motion artifacts, especially in painful or dyspneic patients.

Structural information and membrane binding of truncated RGS9-1 Anchor Protein and its C-terminal hydrophobic segment.

Visual phototransduction takes place in photoreceptor cells. Light absorption by rhodopsin leads to the activation of transducin as a result of the exchange of its GDP for GTP. The GTP-bound ⍺-subunit of transducin then activates phosphodiesterase (PDE), which in turn hydrolyzes cGMP leading to photoreceptor hyperpolarization. Photoreceptors return to the dark state upon inactivation of these proteins. In particular, PDE is inactivated by the protein complex R9AP/RGS9-1/Gß5. R9AP (RGS9-1 anchor protein) is responsible for the membrane anchoring of this protein complex to photoreceptor outer segment disk membranes most likely by the combined involvement of its C-terminal hydrophobic domain as well as other types of interactions. This study thus aimed to gather information on the structure and membrane binding of the C-terminal hydrophobic segment of R9AP as well as of truncated R9AP (without its C-terminal domain, R9AP∆TM). Circular dichroism and infrared spectroscopic measurements revealed that the secondary structure of R9AP∆TM mainly includes ⍺-helical structural elements. Moreover, intrinsic fluorescence measurements of native R9AP∆TM and individual mutants lacking one tryptophan demonstrated that W79 is more buried than W173 but that they are both located in a hydrophobic environment. This method also revealed that membrane binding of R9AP∆TM does not involve regions near its tryptophan residues, while infrared spectroscopy validated its binding to lipid vesicles. Additional fluorescence measurements showed that the C-terminal segment of R9AP is membrane embedded. Maximum insertion pressure and synergy data using Langmuir monolayers suggest that interactions with specific phospholipids could be involved in the membrane binding of R9AP∆TM.

Correction to: Train-the-Trainers in hand hygiene: a standardized approach to guide education in infection prevention and control.

The original article [1] contained a misspelling in author, Fernando Bellissimo-Rodrigues's name which has since been corrected.

Comparison between the enzymatic activity, structure and substrate binding of mouse and human lecithin retinol acyltransferase.

Lecithin retinol acyltransferase (LRAT) is involved in the visual cycle where it catalyzes the formation of all-trans retinyl ester. The mouse animal model has been widely used to study LRAT. Primary sequence alignment shows 80% identity and 90% similarity between human and mouse LRAT. However, human LRAT has a proline at position 173 (hLRAT (P173)) while an arginine can be found at this position for the mouse protein (mLRAT (R173)). Moreover, residue 173 is important for the human protein since a substitution mutation of this residue to a leucine (P173L-hLRAT) caused night blindness in a patient. The present study was thus undertaken to determine whether mouse and human LRAT have a similar enzymatic activity, structure and substrate binding affinity using a truncated form of LRAT (tLRAT). The enzymatic activity and binding affinity to the substrate, all-trans retinol, of mtLRAT (R173) were found to be 2.7- and 3.9-fold lower, respectively, than that of htLRAT (P173). Moreover, the enzymatic activity of P173L-htLRAT is 6.3-fold lower compared to that of htLRAT (P173). Furthermore, a significant difference was observed between the intrinsic fluorescence emission as well as between the circular dichroism spectra of mtLRAT (R173) and htLRAT (P173). In addition, mtLRAT proteins are less thermostable than htLRAT proteins, which suggests that structural differences exist between the mouse and human proteins. Altogether, these data strongly suggest that the much lower catalytic activity of mtLRAT (R173) compared to that of htLRAT (P173) mostly results from differences between their structure, predominantly revealed by their dissimilar thermal stability, as well as their efficiency to bind all-trans retinol. Therefore, conclusions regarding the behavior of human LRAT based on measurements performed with mouse LRAT must be made with caution. Also, the much lower enzymatic activity of P173L-htLRAT compared to that of htLRAT (P173) might explain the night blindness of a patient carrying this mutation.

Scenario-based simulation training for the WHO hand hygiene self-assessment framework.

The WHO SAVE LIVES: Clean Your Hands global hand hygiene campaign, launched in 2009 and celebrated annually on the 5th of May, features specific calls to action seeking to increase engagement from stakeholders' collaborations in hand hygiene improvement. WHO calls on everyone to be inspired by the global movement towards universal health coverage (UHC). Infection prevention and control (IPC), including hand hygiene, is critical to achieve UHC as it has a direct impact on quality of care and patient safety across all levels of the health services. In the framework of UHC, the theme for 5 May 2019 is "Clean care for all - it's in your hands". In this context, the WHO has launched a global survey to assess the current level of progress of IPC programmes and hand hygiene activities in healthcare facilities (HCFs) worldwide. This involved the creation of two tools for healthcare facilities: the WHO Infection Prevention and Control Assessment Framework (IPCAF) and the WHO Hand Hygiene Self-Assessment Framework (HHSAF). The objective of this paper is to provide case scenario-based simulation for IPC specialists to simulate and fully assimilate the correct completion of the HHSAF framework in a standardized format. The three case scenarios have been tested and are proposed for the reader to assess the HHSAF of different HCFs in a variety of contexts, even in low-resouce settings. They were designed for simulation training purposes to achieve standardization and interactive learning. These scenarios are meant to be used by professionals in charge of implementing a hand hygiene improvement strategy within their HCF, as well as for simulation and standardized training purposes prior to completing and submitting data for the 2019 WHO Global Survey. Additionally, information provided by the use of the HHSAF can easily be translated into action plans to support the implementation and improvement related to specific indicators of hand hygiene promotion. We invite all HCFs to participate in the 2019 WHO global survey and monitor the level of progress of their IPC programme and hand hygiene activities.

Train-the-Trainers in hand hygiene: a standardized approach to guide education in infection prevention and control.

BACKGROUND: Harmonization in hand hygiene training for infection prevention and control (IPC) professionals is lacking. We describe a standardized approach to training, using a "Train-the-Trainers" (TTT) concept for IPC professionals and assess its impact on hand hygiene knowledge in six countries. METHODS: We developed a three-day simulation-based TTT course based on the World Health Organization (WHO) Multimodal Hand Hygiene Improvement Strategy. To evaluate its impact, we have performed a pre-and post-course knowledge questionnaire. The Wilcoxon signed-rank test was used to compare the results before and after training. RESULTS: Between June 2016 and January 2018 we conducted seven TTT courses in six countries: Iran, Malaysia, Mexico, South Africa, Spain and Thailand. A total of 305 IPC professionals completed the programme. Participants included nurses (n = 196; 64.2%), physicians (n = 53; 17.3%) and other health professionals (n = 56; 18.3%). In total, participants from more than 20 countries were trained. A significant (p < 0.05) improvement in knowledge between the pre- and post-TTT training phases was observed in all countries. Puebla (Mexico) had the highest improvement (22.3%; p < 0.001), followed by Malaysia (21.2%; p < 0.001), Jalisco (Mexico; 20.2%; p < 0.001), Thailand (18.8%; p < 0.001), South Africa (18.3%; p < 0.001), Iran (17.5%; p < 0.001) and Spain (9.7%; p = 0.047). Spain had the highest overall test scores, while Thailand had the lowest pre- and post-scores. Positive aspects reported included: unique learning environment, sharing experiences, hands-on practices on a secure environment and networking among IPC professionals. Sustainability was assessed through follow-up evaluations conducted in three original TTT course sites in Mexico (Jalisco and Puebla) and in Spain: improvement was sustained in the last follow-up phase when assessed 5 months, 1 year and 2 years after the first TTT course, respectively. CONCLUSIONS: The TTT in hand hygiene model proved to be effective in enhancing participant's knowledge, sharing experiences and networking. IPC professionals can use this reference training method worldwide to further disseminate knowledge to other health care workers.

Promoting and sustaining a historical and global effort to prevent sepsis: the 2018 World Health Organization SAVE LIVES: Clean Your Hands campaign.

Sepsis is estimated to affect more than 30 million patients with potentially five million deaths every year worldwide. Prevention of sepsis, as well as early recognition, diagnosis and treatment, can't be overlooked to mitigate this global public health threat. World Health Organization (WHO) promotes hand hygiene in health care through its annual global campaign, SAVE LIVES: Clean Your Hands campaign on 5 May every year. The 2018 campaign targets sepsis with the overall theme "It's in your hands; prevent sepsis in health care".

[Multiresistant bacteria : practical aspects for doctors working in ambulatory practice]. / Bactéries multirésistantes : aspects pratiques pour le médecin en cabinet médical.

Although preventive measures against the transmission of multidrug-resistant organisms (MDROs) are well established and protocolized in hospital settings, their implementation in private ambulatory practice are rarely addressed. Despite what is sometimes communicated, the risk of transmission of this type of bacteria outside of a hospital environment is real. Standard precautions are the key to minimizing this risk. In a number of situations in the ambulatory setting, MDRO screening (nasal or rectal) is needed and recommended. A system of communication among healthcare professionals concerning patients known to be carriers of MDROs should also be one of the strategies aimed at reducing the spread of these threatening bacteria throughout the health system.

Alors qu'en milieu hospitalier des mesures de prévention contre la transmission des bactéries multirésistantes (BMR) sont bien établies et protocolisées, les éléments à mettre en place en cabinet médical sont rarement abordés. Malgré ce qui est parfois véhiculé, le risque de transmission de ce type de germe en milieu extrahospitalier est réel. Les précautions standard sont la clé pour réduire au maximum ce risque. Dans un certain nombre de situations, un dépistage de BMR dans les selles ou par frottis muco-cutané en ambulatoire sera justifié et fortement encouragé. La promotion d'un système de communication du portage connu de BMR entre les professionnels devrait également faire partie des stratégies qui auront un impact sur la réduction de la propagation de ces bactéries menaçantes dans l'ensemble du réseau de la santé.

An augmented CO2 chemoreflex and overactive orexin system are linked with hypertension in young and adult spontaneously hypertensive rats.

KEY POINTS: Activation of central chemoreceptors by CO2 increases sympathetic nerve activity (SNA), arterial blood pressure (ABP) and breathing. These effects are exaggerated in spontaneously hypertensive rats (SHRs), resulting in an augmented CO2 chemoreflex that affects both breathing and ABP. The augmented CO2 chemoreflex and the high ABP are measureable in young SHRs (postnatal day 30-58) and become greater in adult SHRs. Blockade of orexin receptors can normalize the augmented CO2 chemoreflex and the high ABP in young SHRs and normalize the augmented CO2 chemoreflex and significantly lower the high ABP in adult SHRs. In the hypothalamus, SHRs have more orexin neurons, and a greater proportion of them increase their activity with CO2 . The orexin system is overactive in SHRs and contributes to the augmented CO2 chemoreflex and hypertension. Modulation of the orexin system may be beneficial in the treatment of neurogenic hypertension. ABSTRACT: Activation of central chemoreceptors by CO2 increases arterial blood pressure (ABP), sympathetic nerve activity and breathing. In spontaneously hypertensive rats (SHRs), high ABP is associated with enhanced sympathetic nerve activity and peripheral chemoreflexes. We hypothesized that an augmented CO2 chemoreflex and overactive orexin system are linked with high ABP in both young (postnatal day 30-58) and adult SHRs (4-6 months). Our main findings are as follows. (i) An augmented CO2 chemoreflex and higher ABP in SHRs are measureable at a young age and increase in adulthood. In wakefulness, the ventilatory response to normoxic hypercapnia is higher in young SHRs (mean ± SEM: 179 ± 11% increase) than in age-matched normotensive Wistar-Kyoto rats (114 ± 9% increase), but lower than in adult SHRs (226 ± 10% increase; P < 0.05). The resting ABP is higher in young SHRs (122 ± 5 mmHg) than in age-matched Wistar-Kyoto rats (99 ± 5 mmHg), but lower than in adult SHRs (152 ± 4 mmHg; P < 0.05). (ii) Spontaneously hypertensive rats have more orexin neurons and more CO2 -activated orexin neurons in the hypothalamus. (iii) Antagonism of orexin receptors with a dual orexin receptor antagonist, almorexant, normalizes the augmented CO2 chemoreflex in young and adult SHRs and the high ABP in young SHRs and significantly lowers ABP in adult SHRs. (iv) Attenuation of peripheral chemoreflexes by hyperoxia does not abolish the augmented CO2 chemoreflex (breathing and ABP) in SHRs, which indicates an important role for the central chemoreflex. We suggest that an overactive orexin system may play an important role in the augmented central CO2 chemoreflex and in the development of hypertension in SHRs.

A complex regulatory network coordinating cell cycles during C. elegans development is revealed by a genome-wide RNAi screen.

The development and homeostasis of multicellular animals requires precise coordination of cell division and differentiation. We performed a genome-wide RNA interference screen in Caenorhabditis elegans to reveal the components of a regulatory network that promotes developmentally programmed cell-cycle quiescence. The 107 identified genes are predicted to constitute regulatory networks that are conserved among higher animals because almost half of the genes are represented by clear human orthologs. Using a series of mutant backgrounds to assess their genetic activities, the RNA interference clones displaying similar properties were clustered to establish potential regulatory relationships within the network. This approach uncovered four distinct genetic pathways controlling cell-cycle entry during intestinal organogenesis. The enhanced phenotypes observed for animals carrying compound mutations attest to the collaboration between distinct mechanisms to ensure strict developmental regulation of cell cycles. Moreover, we characterized ubc-25, a gene encoding an E2 ubiquitin-conjugating enzyme whose human ortholog, UBE2Q2, is deregulated in several cancers. Our genetic analyses suggested that ubc-25 acts in a linear pathway with cul-1/Cul1, in parallel to pathways employing cki-1/p27 and lin-35/pRb to promote cell-cycle quiescence. Further investigation of the potential regulatory mechanism demonstrated that ubc-25 activity negatively regulates CYE-1/cyclin E protein abundance in vivo. Together, our results show that the ubc-25-mediated pathway acts within a complex network that integrates the actions of multiple molecular mechanisms to control cell cycles during development.