Does lower extremity fracture fixation technique influence neurologic outcomes in patients with traumatic brain injury? The EAST Brain vs. Bone multicenter trial

OBJECTIVE

This study aimed to determine whether lower extremity fracture fixation technique and timing (≤24 vs. >24 hours) impact neurologic outcomes in TBI patients.

METHODS

A prospective observational study was conducted across 30 trauma centers. Inclusion criteria were age 18 years and older, head Abbreviated Injury Scale (AIS) score of >2, and a diaphyseal femur or tibia fracture requiring external fixation (Ex-Fix), intramedullary nailing (IMN), or open reduction and internal fixation (ORIF). The analysis was conducted using analysis of variamce, Kruskal-Wallis, and multivariable regression models. Neurologic outcomes were measured by discharge Ranchos Los Amigos Revised Scale (RLAS-R).

RESULTS

Of the 520 patients enrolled, 358 underwent Ex-Fix, IMN, or ORIF as definitive management. Head AIS was similar among cohorts. The Ex-Fix group experienced more severe lower extremity injuries (AIS score, 4-5) compared with the IMN group (16% vs. 3%, p = 0.01) but not the ORIF group (16% vs. 6%, p = 0.1). Time to operative intervention varied between the cohorts with the longest time to intervention for the IMN group (median hours: Ex-Fix, 15 [8-24] vs. ORIF, 26 [12-85] vs. IMN, 31 [12-70]; p < 0.001). The discharge RLAS-R score distribution was similar across the groups. After adjusting for confounders, neither method nor timing of lower extremity fixation influenced the discharge RLAS-R. Instead, increasing age and head AIS score were associated with a lower discharge RLAS-R score (odds ratio [OR], 1.02; 95% confidence interval [CI], 1.002-1.03 and OR, 2.37; 95% CI, 1.75-3.22), and a higher Glasgow Coma Scale motor score on admission (OR, 0.84; 95% CI, 0.73-0.97) was associated with higher RLAS-R score at discharge.

CONCLUSION

Neurologic outcomes in TBI are impacted by severity of the head injury and not the fracture fixation technique or timing. Therefore, the strategy of definitive fixation of lower extremity fractures should be dictated by patient physiology and the anatomy of the injured extremity and not by the concern for worsening neurologic outcomes in TBI patients.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level III.

An Allosteric Transcription Factor DNA-Binding Electrochemical Biosensor for Progesterone

We describe an electrochemical strategy to transduce allosteric transcription factor (aTF) binding affinity to sense steroid hormones. Our approach utilizes square wave voltammetry to monitor changes in current output as a progesterone (PRG)-specific aTF (SRTF1) unbinds from the cognate DNA sequence in the presence of PRG. The sensor detects PRG in artificial urine samples with sufficient sensitivity suitable for clinical applications. Our results highlight the capability of using aTFs as the biorecognition elements to develop electrochemical point-of-care biosensors for the detection of small-molecule biomarkers and analytes.

Implementing the Mindfulness-Based Interventions; Teaching Assessment Criteria (MBI:TAC) in Mindfulness-Based Teacher Training

The Mindfulness-Based Interventions: Teaching Assessment Criteria (MBI:TAC) was originally developed as a tool to assess the teaching competence of mindfulness-based program (MBP) teachers. The tool was made freely available and has since been used by mindfulness-based teacher training organisations internationally. During this time the MBI:TAC has evolved in its usage, from an assessment tool to one which informally supports how MBP teachers are trained. In this article, we first examine the rationale for implementing the MBI:TAC in MBP teacher training; second, we offer practical guidance on ways of integrating the tool into teacher training pathways with awareness of its potential and possible pitfalls; and third, we offer guidance on using the tool as a framework for giving effective feedback to trainees on their teaching practice. Implementing the MBI:TAC in teacher training may support the quality and integrity of MBP teacher training, and thus ensure high quality MBP teachers graduating. In turn this may help avoid the 'implementation cliff' - that is, the quality of an intervention delivery is delivered in optimal conditions when it is being researched, and drops in quality when delivered in sub-optimal, 'real world' conditions.

Thought-Action Fusion in Individuals with a History of Recurrent Depression and Suicidal Depression: Findings from a Community Sample

Although suicidal ideation is one of the most consistent symptoms across recurrent episodes of depression, the mechanisms underpinning its maintenance are poorly understood. In order to develop effective treatments for suicidally depressed patients, understanding what maintains suicidal distress is critical. We hypothesised that Thought–Action Fusion (TAF), i.e., to assume that having a thought has real world consequences, originally described in Obsessive–Compulsive Disorder, might be a bias in recurrently suicidally depressed people. To assess this, we revised the original TAF scale, and assessed TAF in three samples: healthy controls, recurrently depressed individuals with no history of suicidality (D-NS) and individuals with a history of recurrent suicidal depression (D-S). Exploratory and confirmatory factor analyses indicated a three-factor solution of TAF: (1) TAF for uncontrollable events, (2) self-suicidal TAF for suicidal acts related to oneself, and (3) TAF for positive controllable events. Compared to healthy controls, the D-NS group reported significantly higher total TAF, TAF uncontrollable, and TAF self-suicidal subscales, whilst positive controllable TAF was lower compared to healthy controls. Both D-S and D-NS samples reported higher TAF for suicidal thought compared to healthy controls, i.e., believing that having suicidal thoughts means they will act on them, however in the context of low mood this became more pronounced for the D-S group. These findings suggest that targeting TAF both in suicidal and non-suicidal depression has merit.

Transition Practice and Policy Compliance in Ohio: A Survey of Secondary Special Educators

In this article the authors examine: (a) statewide implementation of IDEA transition mandates and four other best practices in transition, and (b) factors correlated with their implementation. A survey of transition practices was administered at a statewide meeting for special education supervisors and administrators. Descriptive statistics were used to examine policy and practice implementation and a step-wise multiple regression was used to identify predictors. Respondents reported compliance with an average of 9 of 14 transition policy areas with most compliance found in the paperwork aspects of transition practice. The best predictors of IDEA transition policy compliance were found to be: (a) hours of transition training, and (b) the percentage of non-minority students. Federally funded outreach training was found to be the best predictor for other best practices in transition. The authors raise concerns that IDEA transition compliance efforts appear to be focused more on doing paperwork than on providing transition services. They recommend continued outreach efforts coupled with renewed advocacy regarding transition at the local level.

IDEA Transition Policy Compliance and Best Practice: Perceptions of Transition Stakeholders

This study used the Survey on Transition Policy Compliance and Best Practices to measure transition policy compliance and best practices at local education agencies (LEAs) and identify predictors of transition policy compliance and best practice. The study participants consisted of 186 persons involved in transition planning, including parents and guardians, educators, and adult service professionals. Respondents reported that their schools were generally complying with the transition requirements of the Individuals with Disabilities Education Act (IDEA) with the exception of the requirement to reconvene the Individualized Education Program (IEP) team if transition services could not be provided as planned. The strongest predictor of policy compliance and best practice in LEAs was the existence of a school-based interagency transition team. In addition, transition training proved to be a weaker predictor of best practice. The findings support the need for interagency team forming activities as part of transition training.

Compliance as a Function of Prior Compliance, Familiarization, Effort and Benefits: The Foot-in-the-Door Technique Extended

The current study examined: (a) “whether the foot-in-the-door technique would be effective under two levels (medium and high) of two variables (effort and benefit) associated with the second request; and (b) the role of familiarization as a mediator of the foot-in-the-door technique. The subjects, 180 persons selected from the telephone directory, were initially called by an experimenter who introduced himself as a member of a citizen's traffic organization. The subjects were either asked to answer a few short questions or were simply made familiar with the organization. Control subjects were not initially called. The experimenter called the subjects a second time two days later and asked them to comply either with a medium or large request. Half of the subjects received an argument depicting the high benefits that would accrue should the subject comply and the other half received a less strong argument. The results showed that the foot-in-the-door technique was effective under varying conditions of the second request and that under conditions of medium benefit, familiarization facilitated compliance. Under conditions of high benefit, however, familiarization inhibited compliance. The results were discussed in terms of reactance theory.

Informational Gain and Racial Effects in the Attribution of Attitudes

Attitude attribution was investigated defining corre spondent inference as informational gain. Varied were the race of the actor, the racial association and direction of an essay, and the constraint on the target. The degree of change from pre- essay to post-essay attributions was highly specific to the conditions of the experiment. Informational gain was highest when a black argued against affirmative action. However, subjects gained the least confidence in their attribution in this condition.

Serological survey for antibodies to Leptospira in dogs and raccoons in Washington State

A high number of reported canine leptospirosis cases occurred in Washington State from 2004 to 2006. This prompted a serosurvey of healthy dogs from around the state to determine the distribution of exposure risk and to provide insight into serovar epidemiology in the region. In addition, a convenience sample of sera from injured raccoons was also tested, and clinical serological data from the Washington Animal Disease Diagnostic Laboratory were examined. The proportion of dogs with an antibody titre (>or=1:100) to any serovar was 27/158 (17.1%, 95% CI 11.6-23.9), and that proportion among raccoons was 22/115 (19.1%, 95% CI 12.4-27.5) suggesting that the potential for exposure in Washington state is not uncommon. The most frequently detected serovars in healthy dogs were Autumnalis, Icterohemorrhagiae and Canicola, in clinical canine samples Autumnalis, Bratislava and Pomona were more frequent and in sick or injured raccoons Autumnalis, and Pomona were most frequently detected. Clinical canine serology demonstrated a late summer-fall seasonality that was consistent with other reports. An outbreak of canine leptospirosis occurred during 2004-2006 and was located primarily in western Washington counties, as were three reported human cases in 2005. Canine leptospirosis surveillance is an important tool for detecting human risk of exposure and may provide insights into which serovars are currently of clinical importance.

D matrix analysis of the Renner-Teller effect: An accurate three-state diabatization for NH2

Some time ago we published our first article on the Renner-Teller (RT) model to treat the electronic interaction for a triatomic molecule [J. Chem. Phys. 124, 081106 (2006)]. The main purpose of that Communication was to suggest considering the RT phenomenon as a topological effect, just like the Jahn-Teller phenomenon. However, whereas in the first publication we just summarized a few basic features to support that idea, here in the present article, we extend the topological approach and show that all the expected features that characterize a three (multi) state RT-type'3 system of a triatomic molecule can be studied and analyzed within the framework of that approach. This, among other things, enables us to employ the topological D matrix [Phys. Rev. A 62, 032506 (2000)] to determine, a priori, under what conditions a three-state system can be diabatized. The theoretical presentation is accompanied by a detailed numerical study as carried out for the HNH system. The D-matrix analysis shows that the two original electronic states 2A1 and 2B1 (evolving from the collinear degenerate Pi doublet), frequently used to study this Renner-Teller-type system, are insufficient for diabatization. This is true, in particular, for the stable ground-state configurations of the HNH molecule. However, by including just one additional electronic state--a B state (originating from a collinear Sigma state)--it is found that a rigorous, meaningful three-state diabatization can be carried out for large regions of configuration space, particularly for those, near the stable configuration of NH2. This opens the way for an accurate study of this important molecule even where the electronic angular momentum deviates significantly from an integer value.

Renner-Teller nonadiabatic coupling terms: Anab-initiostudy of the HNH molecule

In this Communication we present the first theoretical/numerical treatment of nonadiabatic coupling terms (NACT) that originate from the Renner-Teller (RT) model, namely, those that follow from the splitting of an electronic level of a linear molecule when it becomes bent. These two newly formed states are characterized by different symmetries and are designated as A and B. Our main findings: (1) The RT NACTs are quantized as long as they are calculated close enough to collinear configuration of the molecule (in this case HNH). Their value is tau = 1 (the Jahn-Teller values in similar situations, are tau = (1/2)). (2) Calculation of RT NACTs at bent configurations (i.e., at a distance from the linear axis) yield decreased values, sometimes by more than 50%. This last finding implies that in strongly bent configurations the two-state Hilbert subspace (formed by the above mentioned A and B states) is affected by upper states, most likely via Jahn-Teller conical intersections. (3) This study has also important practical implications. The fact that the RT NACTs decrease in (strongly) bent situations implies that analyzing spectroscopic data employing only the two Pi-states may not be sufficient in order to achieve the required accuracy.

Protein partners of the BRCA1 tumor suppressor

The primary amino acid sequence of BRCA1 offers few clues about the mechanism by which it suppresses tumor formation in normal breast and ovarian tissues. In an effort to unravel its biological functions, investigators have sought to identify the proteins that interact with BRCA1 in vivo. These efforts have already uncovered two interacting proteins: the BRCA1-associated RING domain (BARD1) protein, a novel polypeptide that bears a striking structural resemblance to BRCA1, and hRAD51, a human homolog of the bacterial recA gene product. As proliferating cells enter S phase of the cell cycle, the BRCA1, hRAD51, and BARD1 polypeptides aggregate in discrete nuclear domains, commonly described as "BRCA1 nuclear dots''. However, when S phase cells sustain DNA damage, the dots are mobilized such that BRCA1 and its associated proteins relocate to sites of replicating DNA. Thus, as a participant in the cellular response to DNA damage, BRCA1 may suppress tumor formation by preserving the integrity of genomic DNA.

Effect of DNA damage on a BRCA1 complex

The tumour-suppressor protein BRCA1 mediates its biological functions by interacting with cellular factors such as the CtIP polypeptide, a substrate for the ATM (for 'ataxia telangiectasia mutated') protein kinase. Li et al. report that the BRCA1-CtIP interaction is disrupted by ionizing radiation and by other genotoxic stresses that induce phosphorylation of CtIP by ATM kinase, and that this dissociation of the BRCA1-CtIP complex in turn modulates the transcription of DNA-damage-response genes. We have shown that the BRCA1-binding domain of CtIP (amino-acid residues 133-369) is distal to the sites that are phosphorylated by ATM kinase (residues S664 and S745). We now show that the BRCA1-CtIP complex is stable in irradiated cells, and that the phosphorylated isoforms of CtIP that are induced by ionizing radiation still interact in vivo with BRCA1. We conclude that disruption of the BRCA1-CtIP complex cannot account for induction of DNA-damage-response genes in the way proposed by Li et al.

Inactivation of human SRBC, located within the 11p15.5-p15.4 tumor suppressor region, in breast and lung cancers

A cDNA clone encoding human SRBC [serum deprivation response factor (sdr)-related gene product that binds to c-kinase] was isolated in a yeast two-hybrid screening, with amino acids 1-304 of BRCA1 as the probe. The human SRBC gene (hSRBC) was mapped to chromosome region 11p15.5-p15.4, close to marker D11S1323, at which frequent loss of heterozygosity (LOH) has been observed in sporadic breast, lung, ovarian, and other types of adult cancers as well as childhood tumors. hSRBC-coding region mutations including frame shift and truncation mutations were detected in a few ovarian and lung cancer cell lines. More significantly, the expression of hSRBC protein was down-regulated in a large fraction [30 (70%) of 43] of breast, lung, and ovarian cancer cell lines, whereas strong expression of hSRBC protein was detected in normal mammary and lung epithelial cells. The down-regulation of hSRBC expression in cancer cells was associated with hypermethylation of CpG dinucleotides in its promoter region, and 3 (60%) of 5 primary breast tumors and 11 (79%) of 14 primary lung tumors were also found to be hypermethylated. Treatment of breast cancer MCF7 cells with 5'azacytidine and Trichostatin A resulted in expression of hSRBC, confirming DNA methylation as the mode of inactivation. Our results suggest that epigenetic or mutational inactivation of hSRBC may contribute to the pathogenesis of several types of human cancers, marking hSRBC as a candidate tumor suppressor gene.

A novel solid-phase approach to 2,4-diaminothiazoles

A novel solid-phase synthesis of a 2,4-diaminothiazole library starting from a polymer-bound thiouronium salt is described. The synthetic strategy involves formation of polymer-bound thioureido-thiourea intermediates [5] which by treatment with alpha-bromo-ketones [6] undergoes S-alkylation, followed by a base-catalyzed intramolecular-ring closure/cleavage to give 2,4-diaminothiazoles [8]. This strategy tolerates a wide range of functionality and protecting groups. The novel feature of our method is a polymer-supported auto-scavenging strategy (PSAS), which provides a clean, high-yielding, and traceless synthesis to 2,4-diaminothiazoles.

The T cell oncogene Tal2 is necessary for normal development of the mouse brain

Transcription factors are commonly involved in leukemia by activation through chromosomal translocations and normally function in cell type(s) that differ from that of the tumor. TAL2 is a member of a basic helix-loop-helix gene family specifically involved in T cell leukemogenesis. Null mutations of Tal2 have been made in mice to determine its function during development. Tal2 null mutant mice show no obvious defects of hematopoiesis. During embryogenesis, Tal2 expression is restricted to the developing midbrain, dorsal diencephalon, and rostroventral diencephalic/telencephalic boundary, partly along presumptive developing fiber tracts. The null mutant mice are viable at birth but growth become progressively retarded and they do not survive to reproductive age. Tal2-deficient mice show a distinct dysgenesis of the midbrain tectum. Due to loss of superficial gray and optical layers, the superior colliculus is reduced in size and the inferior colliculus is abnormally rounded and protruding. Death is most likely due to progressive hydrocephalus which appears to be caused by obstruction of the foramen of Monro (the connection between the ventricles of the forebrain). Thus, in addition to its oncogenicity when ectopically expressed, Tal2 normally plays a pivotal role in brain development and without this gene, mice cannot survive to maturity.

Abnormal expression of BRCA1 and BRCA1-interactive DNA-repair proteins in breast carcinomas

Breast cancer is one of the most common malignancies among women. The molecular mechanisms involved in breast carcinogenesis, however, remain to be elucidated. Although somatic mutation of BRCA1 is rare, BRCA1 protein expression is reduced in about 30% of sporadic breast carcinomas (Yoshikawa et al., Clin. Cancer Res., 5:1249-1261, 1999), indicating its possible involvement even in sporadic breast carcinogenesis. Among the BRCA1-interactive proteins are hRAD51 (a human homologue of Escherichia coli rec A protein), BARD1 (BRCA1-associated RING domain 1) and p53, all of which are involved in DNA repair. We have analyzed the expression patterns of the hRAD51, BARD1 and p53 proteins in five breast cancer cell lines, including a BRCA1-deficient cell line, and in 179 breast cancer tissue samples from Japanese women, including 113 sporadic, 47 hereditary (i.e., BRCA1 status unknown), and 19 BRCA1-associated cases. Of the 179 breast carcinomas, fifty-four (30%) exhibited reduced hRAD51 expression, and sixty-two (35%) exhibited p53 overexpression. On the other hand, reduced expression level of BARD1, and of hMSH2 and hMLH1, which are components of DNA mismatch-repair pathway and are involved in colorectal carcinogenesis, was observed respectively in only 10 (6%), 8 (5%) and 3 (2%) cases. The overall frequency of sporadic breast carcinomas with abnormal expression of either BRCA1 or the BRCA1-interactive proteins was 67% (76/113). These results indicate that there may be an important role for the BRCA1-associated DNA-repair pathway, not only in BRCA1-associated breast carcinomas, but also in sporadic breast carcinomas.

Nuclear localization and cell cycle-specific expression of CtIP, a protein that associates with the BRCA1 tumor suppressor

The BRCA1 tumor suppressor has been implicated in a diverse spectrum of cellular processes, including transcriptional regulation, DNA repair, and cell cycle checkpoint control. CtIP was recently identified as a protein that associates with BRCA1 and two other nuclear factors, CtBP1 and Rb1. To understand the functions of CtIP, we have evaluated its biological properties with respect to those of BRCA1. Our results show that CtIP, like its associated factors, is predominantly a nuclear protein. A subset of the endogenous pool of CtIP polypeptides exists in a protein complex that includes both BRCA1 and the BRCA1-associated RING domain protein (BARD1). At the protein level, CtIP expression varies with cell cycle progression in a pattern identical to that of BRCA1. Thus, the steady-state levels of CtIP polypeptides, which remain low in resting cells and G(1) cycling cells, increase dramatically as dividing cells traverse the G(1)/S boundary. In contrast to BRCA1, however, the G(1)/S induction of CtIP expression is mediated primarily by post-transcriptional mechanisms. Finally, the interaction between CtIP and BRCA1 is shown to be stable in the face of genotoxic stress elicited by treatment with UV light, adriamycin, or hydrogen peroxide. Together, these results indicate that CtIP can potentially modulate the functions ascribed to BRCA1 in transcriptional regulation, DNA repair, and/or cell cycle checkpoint control.

Conservation of function and primary structure in the BRCA1-associated RING domain (BARD1) protein

The BRCA1 gene encodes a tumor suppressor that has been implicated in hereditary forms of breast and ovarian cancer. During S phase of the cell cycle, BRCA1 polypeptides are found in discrete nuclear bodies ('BRCA1 nuclear dots') together with HsRad51, a human homolog of the E. coli recA protein, and BARD1, a protein that interacts with BRCA1 to form a stable heterodimer. BARD1 is structurally similar to BRCA1 in that both molecules harbor an amino-terminal RING domain and two carboxy-terminal BRCT domains. Here we describe the amino acid sequence and expression pattern of murine Bard1. A comparison of the mouse and human sequences reveals that the recognizable protein motifs of BARD1 are well conserved, including the RING domain, the three tandem ankyrin repeats, and, to a lesser extent, the two BRCT domains. However, the remaining sequences of BARD1 display a markedly lower degree of phylogenetic conservation, comparable to those reported for BRCA1 and BRCA2. Moreover, murine Bard1 retains the ability to associate in vivo with BRCA1, and its expression pattern in adult mice mirrors that of Brca1, with elevated levels of RNA transcripts found in the testes and spleen. These data suggest that BRCA1 and BARD1 have co-evolved to participate in a common pathway of tumor suppression.

Functional domains of the BRCA1 and BRCA2 proteins

The BRCA1 and BRCA2 genes encode large unrelated proteins that presumably function as tumor suppressors in normal epithelial cells of the breast. However, the primary amino acid sequences of these proteins provide few insights into the mechanisms by which BRCA1 and BRCA2 inhibit tumor development. Nevertheless, recent studies have uncovered many similarities in the biological properties of BRCA1 and BRCA2, raising the prospect that these proteins may function in a common pathway of tumor suppression and that inactivation of either gene may represent an equivalent step in the development of breast cancer. Several lines of evidence now suggest a role for BRCA1 and BRCA2 in the cellular response to DNA damage, possibly by virtue of their relationship with proteins required for the recombinational repair of double-strand DNA breaks. Accordingly, the loss of BRCA1 or BRCA2 function might accelerate tumor development by allowing cells to accumulate DNA lesions that are potentially oncogenic.

Visual recovery after phacoemulsification using topical anesthesia

PURPOSE

To assess the speed of visual function recovery after phacoemulsification using topical anesthesia.

SETTING

Department of Ophthalmology, Royal United Hospital, Bath, United Kingdom.

METHODS

Twenty consecutive patients having routine sutureless clear corneal phacoemulsification with implantation of a Staar foldable intraocular lens were recruited in a prospective study. Visual acuity was assessed using a LogMAR chart and contrast sensitivity using a Pelli-Robson chart 1, 2, 4, and 16 hours postoperatively. A final examination and refraction were performed at 1 week.

RESULTS

Although return of visual acuity was slow during the first 2 hours, the mean LogMAR acuity had improved to 0.425 (Snellen equivalent 6/15) by 4 hours and 0.165 (Snellen equivalent of 6/9.5) by 16 hours. There was no postoperative ptosis or diplopia.

CONCLUSION

The absence of diplopia and rapid return of visual function with a mean acuity of 6/15 by 4 hours suggest that early patient discharge is relatively safe.

The C-terminal (BRCT) domains of BRCA1 interact in vivo with CtIP, a protein implicated in the CtBP pathway of transcriptional repression

The BRCA1 tumor suppressor encodes a polypeptide with two recognizable protein motifs: a RING domain near the N terminus and two tandem BRCT domains at the C terminus. Studies of tumor-associated mutations indicate that the RING and BRCT sequences are required for BRCA1-mediated tumor suppression. In addition, recent work has shown that BRCA1 is a potent regulator of RNA transcription and that the BRCT domains are also essential for this activity. Therefore, we used the Sos recruitment system to screen for proteins that bind this critical region of BRCA1. Our results show that the BRCT domains interact in vivo with CtIP, a protein originally identified on the basis of its association with the CtBP transcriptional co-repressor. This finding suggests that BRCA1 regulates gene expression, at least in part, by modulating CtBP-mediated transcriptional repression. Moreover, the in vivo interaction between BRCA1 and CtIP is completely ablated by each of three independent tumor-associated mutations affecting the BRCT motifs of BRCA1. These results indicate that the BRCA1-CtIP interaction may be required for tumor suppression by BRCA1.

Identification of substrates and regulators of the mitogen-activated protein kinase ERK5 using chimeric protein kinases

Extracellular signal-regulated protein kinase 5 (ERK5) is a recently discovered orphan mitogen-activated protein kinase for which no substrates or strong activators have been described. Two ERK5 chimeras were created as a novel approach to discover its substrates and upstream regulators. One chimeric protein contained the N-terminal domain of the ERK5 catalytic core (subdomains I-IV) and the C-terminal domain of the ERK2 catalytic core (subdomains V-XI). This chimera was highly responsive to stimuli that regulate ERK2 in vitro and in cells. A second chimeric protein consisted of the N-terminal domain of ERK2 (subdomains I-IV) and the C-terminal domain of the ERK5 catalytic core (subdomains V-XI). This chimera was activated in bacteria by coexpression with a constitutively active mutant of MEK1. Using the activated chimera, we identified three in vitro substrates of ERK5. Assaying ERK5 activity in immune complexes with one of these substrates, c-Myc, we determined that the ERK5 catalytic domain is activated by V12 H-Ras and to a lesser extent by phorbol ester but not by constitutively active mutants of Raf-1. Thus, ERK5 is a target of a novel Ras effector pathway that may communicate with c-Myc.

Mutations in the BRCA1-associated RING domain (BARD1) gene in primary breast, ovarian and uterine cancers

Germline alterations of BRCA1 result in susceptibility to breast and ovarian cancer. The protein encoded by BRCA1 interacts in vivo with the BRCA1-associated RING domain (BARD1) protein. Accordingly, BARD1 is likely to be a critical factor in BRCA1-mediated tumor suppression and may also serve as a target for tumorigenic lesions in some human cancers. We have now determined the genomic structure of BARD1 and performed a mutational analysis of 58 ovarian tumors, 50 breast tumors and 60 uterine tumors. Seven polymorphisms were detected within the 2.34 kb coding sequence of BARD1 . Somatically acquired missense mutations were observed in one breast carcinoma and one endometrial tumor; in at least one of these cases, tumor formation was accompanied by loss of the wild-type BARD1 allele, following the paradigm for known tumor suppressor genes. In addition, a germline alteration of BARD1 was identified in a clear cell ovarian tumor (Gln564His); again, loss of the wild-type BARD1 allele was observed in the malignant cells of this patient. The Gln564His patient was also diagnosed with two other primary cancers: a synchronous lobular breast carcinoma and a stage IA clear cell endometrioid cancer confined to an endometrial polyp 6 years earlier. These findings suggest an occasional role for BARD1 mutations in the development of sporadic and hereditary tumors.

Cell cycle-dependent colocalization of BARD1 and BRCA1 proteins in discrete nuclear domains

Germ-line mutations of the BRCA1 gene predispose women to early-onset breast and ovarian cancer by compromising the gene's presumptive function as a tumor suppressor. Although the biochemical properties of BRCA1 polypeptides are not understood, their expression pattern and subcellular localization suggest a role in cell-cycle regulation. When resting cells are induced to proliferate, the steady-state levels of BRCA1 increase in late G1 and reach a maximum during S phase. Moreover, in S phase cells, BRCA1 polypeptides are hyperphosphorylated and accumulate into discrete subnuclear foci termed "BRCA1 nuclear dots." BRCA1 associates in vivo with a structurally related protein termed BARD1. Here we show that the steady-state levels of BARD1, unlike those of BRCA1, remain relatively constant during cell cycle progression. However, immunostaining revealed that BARD1 resides within BRCA1 nuclear dots during S phase of the cell cycle, but not during the G1 phase. Nevertheless, BARD1 polypeptides are found exclusively in the nuclear fractions of both G1- and S-phase cells. Therefore, progression to S phase is accompanied by the aggregation of nuclear BARD1 polypeptides into BRCA1 nuclear dots. This cell cycle-dependent colocalization of BARD1 and BRCA1 indicates a role for BARD1 in BRCA1-mediated tumor suppression.

Effect of acetylsalicylic acid on pulmonary gas exchange in patients with severe pneumonia: a pilot study

BACKGROUND

It has been hypothesized that local release of prostacyclin in acute pneumonia may ablate hypoxic pulmonary vasoconstriction, thus contributing to the impairment of pulmonary gas exchange in these patients. Inhibition of cyclooxygenase pathway could prevent this phenomenon by reducing the release of these metabolites.

METHODS

A study was designed to assess the effect of I.V. acetylsalicylic acid (ASA) (2 g) on pulmonary gas exchange in seven patients (age, 64+/-11 [mean+/-SD] years) with unilateral severe pneumonia (PaO2/fraction of inspired oxygen, 168+/-67) needing mechanical ventilation. Respiratory gases, pulmonary and systemic hemodynamics, and ventilation-perfusion (VA/Q) distributions were studied before and 15 and 60 min after the infusion of ASA.

RESULTS

At baseline, the amount of shunt (VA/Q ratios <0.005) was 28+/-17% of cardiac output, blood flow to areas with low VA/Q ratios (<0.1, excluding shunt) was 8+/-7%, and the dispersion of pulmonary blood flow distribution (second moment, log SD Q) was 1.45+/-0.49 (normal range, 0.3 to 0.6). Sixty minutes after the infusion of ASA, we observed a mild reduction of the amount of shunt, from 28+/-17% to 23.5+/-13% (p<0.05) without changes in arterial oxygenation. This was associated with a significant increase in mean pulmonary artery pressure (from 21.9+/-3.6 to 24.4+/-5.1 and 23.9+/-5.3 mm Hg, p<0.025 and p=0.1) and pulmonary vascular resistance (from 1.4+/-0.9 to 1.8+/-0.8 and 1.8+/-1.3 mm Hg x min x L(-1) , p<0.002 and p=0.11) 15 and 60 min after ASA, respectively. The ASA plasma levels were within the normal therapeutic range (120+/-7 microg/mL, 15 min, and 113+/-11 microg/mL, 60 min after ASA infusion).

CONCLUSIONS

Although there was a modest improvement in intrapulmonary shunt, our results suggest that perfusion of ASA in this small sample of patients with severe pneumonia appears to be of little benefit as complementary treatment for severe hypoxemia.

Identification of a RING protein that can interact in vivo with the BRCA1 gene product

The hereditary breast and ovarian cancer gene, BRCA1, encodes a large polypeptide that contains the cysteine-rich RING motif, a zinc-binding domain found in a variety of regulatory proteins. Here we describe a novel protein that interacts in vivo with the N-terminal region of BRCA1. This BRCA1-associated RING domain (BARD1) protein contains an N-terminal RING motif, three tandem ankyrin repeats, and a C-terminal sequence with significant homology to the phylogenetically conserved BRCT domains that lie near the C terminus of BRCA1. The BARD1/BRCA1 interaction is disrupted by BRCA1 missense mutations that segregate with breast cancer susceptibility, indicating that BARD1 may be involved in mediating tumour suppression by BRCA1.

Mutation of position 52 in ERK2 creates a nonproductive binding mode for adenosine 5'-triphosphate

Among the protein kinases, an absolutely conserved lysine in subdomain II is required for high catalytic activity. This lysine is known to interact with the substrate ATP, but otherwise its role is not well understood. We have used biochemical and structural methods to investigate the function of this lysine (K52) in phosphoryl transfer reactions catalyzed by the MAP kinase ERK2. The kinetic properties of activated wild-type ERK2 and K52 mutants were examined using the oncoprotein TAL2, myelin basic protein, and a designed synthetic peptide as substrates. The catalytic activities of K52R and K52A ERK2 were lower than that of wild-type ERK2, primarily as a consequence of reductions in kcat. Further, there was little difference in Km for ATP, but the Km,app for peptide substrate was higher for the K52 mutants. The three-dimensional structure of unphosphorylated K52R ERK2 in the absence and presence of bound ATP was determined and compared with the structure of unphosphorylated wild-type ERK2. ATP adopted a well-defined but distinct binding mode in K52R ERK2 compared to the binding mode in the wild-type enzyme. The structural and kinetic data show that mutation of K52 created a nonproductive binding mode for ATP and suggest that K52 is essential for orienting ATP for catalysis.

Protein dimerization between Lmo2 (Rbtn2) and Tal1 alters thymocyte development and potentiates T cell tumorigenesis in transgenic mice

The LMO2 and TAL1 genes were first identified via chromosomal translocations and later found to encode proteins that interact during normal erythroid development. Some T cell leukaemia patients have chromosomal abnormalities involving both genes, implying that LMO2 and TAL1 act synergistically to promote tumorigenesis after their inappropriate co-expression. To test this hypothesis, transgenic mice were made which co-express Lmo2 and Tal1 genes in T cells. Dimers of Lmo2 and Tal1 proteins were formed in thymocytes of double but not single transgenic mice. Furthermore, thymuses of double transgenic mice were almost completely populated by immature T cells from birth, and these mice develop T cell tumours approximately 3 months earlier than those with only the Lmo2 transgene. Thus interaction between these two proteins can alter T cell development and potentiate tumorigenesis. The data also provide formal proof that TAL1 is an oncogene, apparently acting as a tumour promoter in this system.

Characterization and genomic mapping of a novel leader peptide associated with the human VH4-21 (VH4-34) gene segment

The human IgVH locus is located on chromosome 14, band q32 and spans approximately 1 mb. Within this locus are approximately 120 VH gene segments that are subdivided into six to seven families based on sequence homology of their coding regions. VH4-21 (VH4-34) is a member of the VH4 family, a family that contains 10 to 15 members. It is expressed in a variety of circumstances including early fetal development, the autoantibody repertoire, and in a highly restricted manner in antibodies that recognize alloantigens on the surface of human red blood cells. Most interesting, however, is the expression of this gene segment in T cells as a semi-germline transcript in conjunction with a nontraditional VH leader peptide. This nonhydrophobic leader sequence, termed "Et" for exon in T cells, has previously been shown to reside within the VH locus. Using YAC and P1 clones, we have identified two copies of this exon, both of which are located in the region of the locus that contains VH4-24 (VH4-34). Characterization of the two exons suggests that they arose by duplication, as flanking DNA is almost identical over a distance of > 5 kb. Preliminary data suggests they are both located > 20 kb upstream of VH4-21 (VH4-34).

Does activation of the TAL1 gene occur in a majority of patients with T-cell acute lymphoblastic leukemia? A pediatric oncology group study

Almost 25% of patients with T-cell acute lymphoblastic leukemia (T-ALL) have tumor-specific rearrangements of the TAL1 gene. Although TAL1 expression has not been observed in normal lymphocytes, TAL1 gene products are readily detected in leukemic cells that harbor a rearranged TAL1 allele. Hence, it has been proposed that ectopic expression of TAL1 promotes the development of T-ALL. In this report, we show that TAL1 is expressed in the leukemic cells of most patients with T-ALL, including many that do not display an apparent TAL1 gene alteration. A polymorphic dinucleotide repeat in the transcribed sequences of TAL1 was used to determine the allele specificity of TAL1 transcription in primary T-ALL cells. Monoallelic expression of TAL1 was observed in the leukemic cells of all patients (8 of 8) bearing a TAL1 gene rearrangement. In the leukemic cells of patients without detectable TAL1 rearrangements, TAL1 transcription occurred in either a monoallelic (3 of 7 patients) or a biallelic (4 of 7 patients) fashion. Thus, TAL1 activation in these patients may result from subtle alterations in cis-acting regulatory sequences (affecting expression of a single TAL1 allele) or changes in trans-acting factors that control TAL1 transcription (affecting expression of both TAL1 alleles).

Coordinate expression and developmental role of Id2 protein and TAL1/E2A heterodimer in erythroid progenitor differentiation

The Id proteins and basic helix-loop-helix (bHLH) proteins play major roles in specifying cell fate decisions in diverse biologic settings. A potential role for Id and TAL1/E2A bHLH genes in hematopoiesis has been suggested by studies on immortalized cell lines. However, it is uncertain whether these observations reflect normal hematopoiesis. We have investigated the expression pattern of Id2 and TAL1/E2A genes in liquid suspension culture of purified hematopoietic progenitor cell (HPCs) undergoing erythroid or granulopoietic differentiation in the first culture week and maturation to terminal cells in the second week. In quiescent, freshly purified HPCs, Id2 mRNA is detected by reverse transcriptase-polymerase chain reaction (RT-PCR), whereas TAL1 and E2A mRNAs are not. At the onset of erythroid differentiation, Id2 mRNA is downregulated, while E2A and TAL1 mRNAs are concomitantly upregulated: their expression is further increased at erythroblast level. Conversely, Id2 is not downmodulated in granulopoietic culture, except for a late decline at day 10 to 12, while TAL1 and E2A are only transiently induced in the first week of granulopoietic differentiation. The expression pattern of the TAL1/E2A heterodimer, as evaluated by mobility shift assay, is consistent with RT-PCR results (except for lower levels of the heterodimer in late erythroid maturation). TAL1 protein level, analyzed by Western blot, shows a pattern consistent with gelshift results. Functional experiments were performed on purified HPCs treated with phosphorothioate antisense oligodeoxynucleotides to Id2 or TAL1 mRNA. The results are strictly consistent with the expression studies: anti-Id2 oligomer (alpha-Id2) causes a significant dose-dependent increase of erythroid colony formation, whereas alpha-TAL1 induces a selective dose-related inhibitory effect on erythroid colonies, as compared with untreated or scrambled oligomer-treated control HPCs. Finally, murine and human glutathione-S-transferase (GST)-Id2 polypeptides compete the TAL1/E2A-specific DNA binding activity when added to the nuclear extracts derived from erythroid culture cells, thus indicating biochemical and suggesting functional interaction of Id2 with the TAL1/E2A complex. These novel observations indicate a coordinate expression and function of an inhibitory Id protein (Id2) and a stimulatory bHLH/bHLH heterodimer (TAL1/E2A) in normal erythroid differentiation.

Participant, Employer, and Rehabilitation Resources in Supported Employment: A Collaborative Support Approach

Employer participation and natural supports are recent topics in the supported employment literature. This article traces the potential role of employers in the development and implementation of supports while describing the experience of the authors with employer assistance in supported employment programs. Ecological principles are applied to issues of support provision, and a collaborative approach is suggested in which active employer participation on a case by case basis can inform the support development process. Service delivery and marketing issues are outlined to sensitize the reader to implications of an ecological approach to support provision.

The MAP kinase phosphorylation site of TAL1 occurs within a transcriptional activation domain

Alteration of the TAL1 gene is the most common genetic lesion found in patients with T cell acute lymphoblastic leukemia. TAL1 encodes a basic helix-loop-helix transcription factor that is phosphorylated on serine residue 122 by the mitogen-activated protein (MAP) kinase ERK1. Here we show that the amino-terminal sequences of TAL1 (residues 1-166) function in vivo as a transcriptional activation domain. Mutation of serine residue 122 reduces the potency of the transactivation domain by more than half. The data suggest that the amino-terminal transactivation domain of TAL1 is positively regulated by S122 phosphorylation and that the functional properties of TAL1 can be influenced by signal transduction pathways that involve the MAP kinases.

Specific in vivo association between the bHLH and LIM proteins implicated in human T cell leukemia

The protein products of proto-oncogenes implicated in T cell acute lymphoblastic leukemia include two distinct families of presumptive transcription factors. RBTN1 and RBTN2 encode highly related proteins that possess cysteine-rich LIM motifs. TAL1, TAL2 and LYL1 encode a unique subgroup of basic helix-loop-helix (bHLH) proteins that share exceptional homology in their bHLH sequences. We have found that RBTN1 and RBTN2 have the ability to interact with each of the leukemogenic bHLH proteins (TAL1, TAL2 and LYL1). These interactions occur in vivo and appear to be mediated by sequences within the LIM and bHLH domains. The LIM-bHLH interactions are highly specific in that RBTN1 and RBTN2 will associate with TAL1, TAL2 and LYL1, but not with other bHLH proteins, including E12, E47, Id1, NHLH1, AP4, MAX, MYC and MyoD1. Moreover, RBTN1 and RBTN2 can interact with TAL1 polypeptides that exist in assembled bHLH heterodimers (e.g. TAL1-E47), suggesting that the RBTN proteins can influence the functional properties of TAL1. Finally, we have identified a subset of leukemia patients that harbor tumor-specific rearrangements of both their RBTN2 and TAL1 genes. Thus, the activated alleles of these genes may promote leukemia cooperatively, perhaps as a result of bHLH-LIM interactions between their protein products.

The LIM protein RBTN2 and the basic helix-loop-helix protein TAL1 are present in a complex in erythroid cells

Chromosomal translocations in T-cell acute leukemias can activate genes encoding putative transcription factors such as the LIM proteins RBTN1 and RBTN2 and the DNA-binding basic helix-loop-helix transcription factor TAL1 associated with T-cell acute lymphocytic leukemia. While not expressed in normal T cells, RBTN2 and TAL1 are coexpressed in erythroid cells and are both important for erythroid differentiation. We demonstrate, using anti-RBTN2 and anti-TAL1 antisera, that the LIM protein RBTN2 is not phosphorylated and is complexed with the TAL1 phosphoprotein in the nucleus of erythroid cells. A complex containing both RBTN1 and TAL1 also occurs in a T-cell acute leukemia cell line. Since both RBTN2 and TAL1 are crucial for normal erythropoiesis, these data have important implications for transcription networks therein. Further, since both proteins can be involved in leukemogenesis, these data provide a direct link between proteins activated by chromosomal translocations in T-cell acute leukemia.

Positive and negative transcriptional control by the TAL1 helix-loop-helix protein

Tumor-specific activation of the TAL1 gene is the most common genetic defect associated with T-cell acute lymphoblastic leukemia. The TAL1 gene products possess a basic helix-loop-helix (bHLH) motif, a protein-dimerization and DNA-binding domain found in several transcription factors. TAL1 polypeptides interact, in vitro and in vivo, with class A bHLH proteins (e.g., E47) to form heterodimers with sequence-specific DNA-binding activity. In this study, we show that TAL1 can regulate the transcription of an artificial reporter gene that contains binding sites for bHLH heterodimers involving TAL1. Transcription of the reporter is strongly induced by E47-E47 homodimers and moderately induced by TAL1-E47 heterodimers. Thus, in a cellular environment that allows formation of E47-E47 homodimers (e.g., in the absence of Id regulatory proteins) TAL1 can repress transcription by recruiting E47 into bHLH complexes with less transcriptional activity (i.e., TAL1-E47 heterodimers). However, in other settings TAL1 can activate transcription because TAL1-E47 heterodimers are more resistant to negative regulation by Id proteins. Hence, TAL1 can potentially regulate transcription in either a positive or negative fashion.