Loss of the Suv39h histone methyltransferases impairs mammalian heterochromatin and genome stability

Histone H3 lysine 9 methylation has been proposed to provide a major "switch" for the functional organization of chromosomal subdomains. Here, we show that the murine Suv39h histone methyltransferases (HMTases) govern H3-K9 methylation at pericentric heterochromatin and induce a specialized histone methylation pattern that differs from the broad H3-K9 methylation present at other chromosomal regions. Suv39h-deficient mice display severely impaired viability and chromosomal instabilities that are associated with an increased tumor risk and perturbed chromosome interactions during male meiosis. These in vivo data assign a crucial role for pericentric H3-K9 methylation in protecting genome stability, and define the Suv39h HMTases as important epigenetic regulators for mammalian development.

Rapid velocity-encoded cine imaging with turbo-BRISK

Velocity-encoded cine (VEC) imaging is potentially an important clinical diagnostic technique for cardiovascular diseases. Advances in gradient technology combined with segmentation approaches have made possible breathhold VEC imaging, allowing data to be obtained free of respiratory artifacts. However, when using conventional segmentation approaches, spatial and temporal resolutions are typically compromised to accommodate short breathhold times. Here we apply a sparse sampling technique, turbo-BRISK (i.e., segmented block regional interpolation scheme for k-space) to VEC imaging, allowing increased spatial and temporal resolution to be obtained in a short breathhold period. BRISK is a sparse sampling technique with interpolation used to generate unsampled data. BRISK was implemented to reduce the scan time by 70% compared with a conventional scan. Further, turbo-BRISK scans, using segmentation factors up to 5, reduce the scan time by up to 94%. Phantom and in vivo results are presented that demonstrate the accuracy of turbo-BRISK VEC imaging. In vitro validation is performed using conventional magnetic resonance VEC. Pulsatile centerline flow velocity measurements obtained with turbo-BRISK acquisitions were correlated with conventional magnetic resonance imaging measurements and achieved r values of 0.99 +/- 0.004 (mean +/- SD) with stroke volumes agreeing to within 4%. A potential limitation of BRISK is reduced accuracy for rapidly varying velocity profiles. We present low- and high-resolution data sets to illustrate the resolution dependence of this phenomenon and demonstrate that at conventional resolutions, turbo-BRISK can accurately represent rapid velocity changes. In vivo results indicate that centerline velocity waveforms in the descending aorta correlate well with conventional measurements with an average r value of 0.98 +/- 0.01.

A mathematical treatment of AIDS and condom use

In this paper we examine the impact of condom use on the sexual transmission of human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) amongst a homogeneously mixing male homosexual population. We first derive a multi-group SIR-type model of HIV/AIDS transmission where the homosexual population is split into subgroups according to frequency of condom use. Both susceptible and infected individuals can transfer between the different groups. We then discuss in detail an important special case of this model which includes two risk groups and perform an equilibrium and stability analysis for this special case. Our analysis shows that this model can exhibit unusual behaviour. As normal, if the basic reproduction number, R0, is greater than unity then there is a unique disease-free equilibrium which is locally unstable and a unique endemic equilibrium. However, when R0 is less than unity two endemic equilibrium solutions can also co-exist simultaneously with the disease-free solution which is locally stable. Numerical simulations using realistic parameter values confirm this and we find that in certain circumstances the disease-free solution and one of the endemic solutions are both locally asymptotically stable, while the other endemic solution is unstable. This unusual behaviour has important implications for control of the disease as reducing R0 to less than unity no longer guarantees eradication of the disease. For a restricted special case of this two-group model we show that there is only the disease-free equilibrium for R0 < or = 1 which is globally stable. For R0 > 1 the disease-free equilibrium is unstable and there is a unique endemic equilibrium which is locally stable. We then attempt to fit the model to HIV and AIDS incidence data from San Francisco, USA. The paper concludes with a brief discussion.

Curved saccade trajectories: voluntary and reflexive saccades curve away from irrelevant distractors

In this study we examined the impact of irrelevant distractors upon trajectories of reflexive and voluntary saccades. Observers made saccades to visual targets above and below fixation as directed by target appearance (reflexive) or by a central directional cue (voluntary) in the presence of an irrelevant distractor stimulus (a cross) whose appearance was simultaneous with target onset. We recorded saccade latency, amplitude and the magnitude of saccade curvature relative to the direct route from the start-to-end of the saccade. Previous studies of saccades curvature have used distractors to provide information about the saccade task and, as a result, have only examined trajectories of voluntary saccades. However, we have shown that both reflexive and voluntary saccades curved away from irrelevant distractors. The effect of irrelevant distractors indicates that observers do not need to attend to distractors in a voluntary fashion for distractors to modify saccade trajectories. Furthermore, it highlights an important parallel in curvature of saccades and reach trajectories, namely that both curve away from irrelevant distractors. The second important observation was that reflexive, as well as voluntary, saccades curved away from distractors. This suggests that curvature is not solely a consequence of voluntary control. These results have been considered within the context of inhibition-based theories of curvature derived from studies of saccade and manual reach trajectories.

Interface design and cognitive style in learning an instructional computer simulation

An experimental design was used to investigate how cognitive style interacts with interface design to affect users' abilities to learn to use a computer simulation. Eighteen nursing students were assigned to two groups, based on their cognitive style, and asked to solve 3 physiologic problems using 3 interface designs: a strip-chart display, an integrated balloon display, and an etiologic display. Students were given up to 2 minutes to solve each problem by administering 6 different hypothetical drugs targeted at different aspects of the simulated hemodynamic system. A mixed-design analysis of variance was used to determine the effects of interface design and cognitive style on number of problems solved, time to initiate treatment, percentage of time system maintained within normal parameters, and number of drugs used. We found that the effects of cognitive style on performance were mediated by interface design and tended to decrease with practice.

Hemodynamic evaluation with TURBO BRISK--a rapid phase contrast angiography technique

Hemodynamic imaging by phase contrast angiography was significantly accelerated by selective interpolation and segmentation in k-space using TURBO BRISK. The method was tested in vitro on three independent flowfields, representative of human blood rheology: a straight tube simulating the descending aorta, a curved tube simulating the aortic arch and a two-chamber orifice flow model simulating valvular regurgitation. The results were compared to data obtained by Laser Doppler Velocimetry (LDV) and showed good agreement. For the straight tube, the flow velocity obtained by five TURBO BRISK methods with increasing segmentation factors and corresponding time savings showed good agreement with LDV. For the curved tube, the velocity showed good general agreement with some differences in the decelerating part of the cycle, and in the low-velocity secondary flow structures. The orifice flow evaluation, the most time consuming case, was performed by the control volume method. It showed good agreement with actual flows through the orifice. Data acquisitions for TURBO-4 BRISK could be performed in 20s for each velocity component. The method shows promise for breath-hold acquisitions in clinical applications, including calculation of blood flow volumes through diseased arteries, measurement of blood backflow volumes through dysfunctional heart valves to time valve replacement operations, and evaluation of arterial wall shear stress, an important factor in the genesis of atherosclerosis.

Ventilator-patient dyssynchrony induced by change in ventilation mode

Patient-ventilator interactions may be coordinated (synchronous) or uncoordinated (dyssynchronous). Ventilator-patient dyssynchrony increases the work of breathing by imposing a respiratory muscle workload. Respiratory centre output responds to feedback from respiratory muscle loading. Mismatching of respiratory centre output and mechanical assistance results in dyssynchrony. We describe a case of severe patient-ventilator dyssynchrony and hypothesize that dyssynchrony was induced by a change in mode of ventilation from pressure-cycled to volume-cycled ventilation, due to both ventilator settings and by the patient's own respiratory centre adaptation to mechanical ventilation. The causes, management and clinical implications of dyssynchrony are discussed.

Mother-to-child transmission of the human immunodeficiency virus in Texas

BACKGROUND

The Pediatric Spectrum of HIV Diseases (PSD) project has been collecting data on HIV-exposed children in Texas since 1989. These data have now been analyzed to describe mother-to-child transmission in Texas and to provide much needed information on the magnitude of the pediatric HIV epidemic in the state.

METHODS

We examined trends in the numbers of perinatally exposed children and perinatally acquired cases of HIV in the Texas PSD cohort. We calculated transmission rates and relative risks for 656 children born from January, 1995, to July, 1998, that received all or part of the ACTG 076 regimen.

RESULTS

Only a small proportion (38%) of pairs of an HIV-infected mother and her HIV-exposed child received the full AIDS Clinical Trial Group 076 (ACTG 076) regimen; only 73% of the mothers received at least some prenatal care. In recent years, however, the numbers of perinatally exposed children and perinatally acquired cases of HIV have decreased in Texas. Univariate analyses showed that a reduction in the vertical transmission of HIV was associated with receipt of a full ACTG 076 regimen, receipt of a partial ACTG 076 regimen and residence in Dallas County.

CONCLUSIONS

Findings identify a gap in meeting the health care needs of pregnant HIV-infected women and suggest missed opportunities to prevent mother-to-child transmission of HIV. At the same time this study confirms progress in prevention efforts to reduce mother-to-child transmission of HIV in Texas.

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

Validation of rapid velocity encoded cine imaging of a dynamically complex flow field using turbo block regional interpolation scheme for k space

Block regional interpolation scheme for k space (BRISK) is a sparse sampling approach to allow rapid magnetic resonance imaging of dynamic events. Rapid velocity encoded cine (VEC) imaging with Turbo BRISK is potentially an important clinical diagnostic technique for cardiovascular diseases. Previously we applied BRISK and Turbo BRISK to imaging pulsatile flow in a straight tube. To evaluate the capabilities of Turbo BRISK imaging in more complex dynamic flow fields such as might exist in the human vasculature, an in vitro curved tube model, similar in geometry to the aortic arch, was fabricated and imaged under pulsatile flow conditions. Velocity maps were obtained using conventional VEC and Turbo BRISK (turbo factors 1 through 5). Comparison of the flow fields obtained with each higher order turbo factor showed excellent agreement with conventional VEC with minimal loss of information. Similarly, flow maps showed good agreement with the profiles from a laser Doppler velocimetry model. Turbo-5 BRISK, for example, allowed a 94% savings in imaging time, reducing the conventional imaging time from over 8 min to a near breath-hold imaging period of 31 s. Turbo BRISK shows excellent promise toward the development of a clinical tool to evaluate complex dynamic intravascular flow fields.

Cardiac MR spectroscopy in the new millennium

Spectroscopy is close to becoming an integral part of the clinical MR examination to achieve a complete morphological, functional, and metabolic evaluation of the human heart. 31P-NMR spectroscopy is used to noninvasively assess human myocardial energy metabolism. Abnormalities in the phosphocreatine (PCr) to ATP ratio are observed in ischemic heart disease, heart failure, transplanted hearts, and hypertrophic cardiomyopathy. NMR spectroscopy 31P spectra obtained at rest, during exercise or pharmacological stress allow the observation of the earliest metabolic responses of myocardial ischemia. 1 spectroscopy can evaluate the concentration of intracellular creatine and myocardial lipids as a means of evaluating myocardial viability. The increase in total 23Na in ischemic tissue provides information about the extent and location of viable tissue. Higher magnetic fields, gradient strength, and technological advances in pulse sequence and localization will result in better spatial and temporal resolution improving the clinical utility of the technique.

Mouse staufen genes are expressed in germ cells during oogenesis and spermatogenesis

The Drosophila melanogaster staufen gene encodes an RNA binding protein (Dm Stau) required for the localization and translational repression of mRNAs within the Drosophila oocyte. In mammals translational repression is important for normal spermatogenesis in males and storage of mRNAs in the oocytes of females. In the present study we identified two mouse cDNA expressed sequence tags (ESTs), encoding proteins with significant homology to Dm Stau and used these firstly to screen a mouse kidney cDNA library and secondly to determine whether staufen mRNAs are expressed in the ovaries and testes of mice and rats. Sequence analysis of the cDNAs revealed that they originated from two different genes. Using Northern blots of RNAs from kidneys, ovaries and testes, both cDNAs hybridized to mRNA species of approximately 3 kb in all three tissues. On sections of mouse ovaries, staufen mRNA was localized specifically to oocytes. On sections of mouse testes, staufen mRNA was expressed in spermatocytes found in seminiferous tubules at stages VI-XII of the spermatogenic cycle. In conclusion, we have shown that the mammalian homologues of Dm stau are expressed in germ cells in both male and female mice, consistent with a role for these RNA binding proteins in mammalian gametogenesis.

Suprarenal mycotic aneurysm exclusion using a stent with a partial autologous covering

PURPOSE

To report a combined endovascular and open technique to manage a suprarenal mycotic aortic aneurysm using a stent-graft partially covered with a section of autologous artery.

METHODS AND RESULTS

A 50-year-old was hospitalized for staphylococcal septicemia and severe back pain. A previously diagnosed 3-cm abdominal aortic aneurysm was found to have expanded 2 cm in 3 weeks. Aortography documented some periaortic thickening and 2 mycotic aneurysms, one posterior at the level of the superior mesenteric artery and the second at the aortic bifurcation. After intensive antibiotic therapy, an endovascular approach to exclude the suprarenal mycotic aneurysm was undertaken in tandem with surgical excision of the infrarenal aneurysm. The harvested right common iliac artery was used to partially cover a Palmaz stent, which was deployed under direct vision just above the renal artery ostia so that the covered portion of the stent excluded the aneurysm. A right axillofemoral bypass with a femorofemoral bypass completed the revascularization. Postoperatively, the patient developed renal failure, ischemic colitis necessitating a left hemicolectomy, and paraplegia. Although the patient is paralyzed, the aneurysm remains excluded with patent visceral vessels at 12 months following surgery. No organisms were grown from excised aortic tissue, and no signs of recurrent infection have been seen.

CONCLUSIONS

Stent-graft repair may be able to lessen the invasiveness and reduce the morbidity associated with treatment of mycotic aortic aneurysms.

Violence risk prediction. Clinical and actuarial measures and the role of the Psychopathy Checklist

BACKGROUND

Violence risk prediction is a priority issue for clinicians working with mentally disordered offenders.

AIMS

To review the current status of violence risk prediction research.

METHOD

Literature search (Medline). Key words: violence, risk prediction, mental disorder.

RESULTS

Systematic/structured risk assessment approaches may enhance the accuracy of clinical prediction of violent outcomes. Data on the predictive validity of available clinical risk assessment tools are based largely on American and North American studies and further validation is required in British samples. The Psychopathy Checklist appears to be a key predictor of violent recidivism in a variety of settings.

CONCLUSIONS

Violence risk prediction is an inexact science and as such will continue to provoke debate. Clinicians clearly need to be able to demonstrate the rationale behind their decisions on violence risk and much can be learned from recent developments in research on violence risk prediction.

Regulation of protein kinase Ctheta function during T cell activation by Lck-mediated tyrosine phosphorylation

Protein kinase C theta (PKCtheta) is a novel Ca(2+)-independent PKC isoform, which is selectively expressed in skeletal muscle and hematopoietic cells, especially T cells. In T cells, it colocalizes with the T cell antigen receptor (TCR).CD3 complex in antigen-stimulated T cells and is involved in the transcriptional activation of the interleukin-2 gene. In the present study, we report that PKCtheta is tyrosine phosphorylated in Jurkat T cells upon TCR.CD3 activation. The Src family protein-tyrosine kinase, Lck, was critical in TCR-induced tyrosine phosphorylation of PKCtheta. Lck phosphorylated and was associated with the regulatory domain of PKCtheta both in vitro and in intact cells. This association was constitutive, but it was enhanced by T cell activation, with both Src-homology 2 and Src-homology 3 domains of Lck contributing to it. Tyrosine 90 (Tyr-90) in the regulatory domain of PKCtheta was identified as the major phosphorylation site by Lck. A constitutively active mutant of PKCtheta (A148E) could enhance proliferation of Jurkat T cells and synergized with ionomycin to induce nuclear factor of T cells activity. However, mutation of Tyr-90 into phenylalanine markedly reduced (or abolished) these activities. These results suggest that Lck plays an important role in tyrosine phosphorylation of PKCtheta, which may in turn modulate the physiological functions of PKCtheta during TCR-induced T cell activation.

A comparison of regularly administered sustained release oral morphine with intramuscular morphine for control of postoperative pain

We studied the efficacy and side effect profile of regularly administered, oral sustained-release morphine sulfate tablets (MST) and IM morphine in patients undergoing total hip arthroplasty under lumbar spinal anesthesia. Patients in Group I received MST 20 mg 12 hourly and a placebo IM injection 6 hourly regularly. Group II patients received an oral placebo 12 hourly and morphine sulfate 10 mg IM 6 hourly regularly. Rescue analgesia was provided with regular diclofenac suppositories and patient-controlled analgesia. Pain scores assessed by using visual analog scale and verbal pain scoring at rest and with movement were low in both groups, with no statistical difference between groups. Mean patient-controlled analgesia morphine consumption during the 48-h study was 16.7 mg in the IM group and 25.9 mg in the MST group. The difference between the groups was significant at 36 h postoperatively (0.03). Side effects of sedation and respiratory depression were not problematic in either group, with a maximal sedation score of 2 occurring once in a patient in Group II. Nausea and vomiting occurred more often in Group II, but this was not statistically significant, with a mean nausea/vomiting score for Group II of 1.7. We conclude that oral, sustained-release morphine is an attractive alternative to IM opiates in patients undergoing body surface surgery under regional anesthesia.

IMPLICATIONS

Each postoperative analgesic has its own limitations for route of administration, dosage, and potential side effects. Using the oral route for drug administration seems more attractive than other methods but may not be suitable in all postoperative patients. We studied the efficacy and side effect profile of sustained-release, oral morphine compared with standard IM morphine for the treatment of pain after hip replacement surgery. We concluded that use of the oral preparation is a suitable alternative to the IM route in this population undergoing surgery under spinal anesthesia.

Aorto-left renal vein fistula: is there a place for endovascular management?

PURPOSE

To describe the endovascular treatment of an aorto-left renal vein fistula.

METHODS AND RESULTS

A 77-year-old man with multiple comorbidities presented with low back pain, hematuria, cyanosis, and a pulsatile abdominal mass. Imaging confirmed a 7-cm abdominal aortic aneurysm with a contained rupture into the left renal vein. Owing to the patient's high surgical risk, a Talent Endoluminal Stent-Graft was implanted to satisfactorily exclude the aneurysm. Hemodynamic stability and normal renal function were restored; however, continued perfusion of the sac prompted an attempt to percutaneously repair the renal vein defect. This effort failed, so open laparotomy was necessary.

CONCLUSIONS

Although total endovascular management was not successful in this case, the initial use of a minimally invasive approach allowed the patient's clinical status to improve and lower the risk of subsequent surgery.

Protein kinase C activation inhibits tyrosine phosphorylation of Cbl and its recruitment of Src homology 2 domain-containing proteins

One of the major proteins that is rapidly tyrosine phosphorylated upon stimulation of the TCR/CD3 complex is the 120-kDa product of the c-cbl protooncogene (Cbl). Upon activation, tyrosine-phosphorylated Cbl interacts with the Src homology 2 (SH2) domains of several signaling proteins, e.g., phosphatidylinositol 3-kinase (PI3-K) and CrkL. In the present study, we report that pretreatment of Jurkat T cells with PMA reduced the anti-CD3-induced tyrosine phosphorylation of Cbl and, consequently, its activation-dependent association with PI3-K and CrkL. A specific protein kinase C (PKC) inhibitor (GF-109203X) reversed the effect of PMA on tyrosine phosphorylation of Cbl and restored the activation-dependent association of Cbl with PI3-K and CrkL. We also provide evidence that PKCalpha and PKCtheta can physically associate with Cbl and are able to phosphorylate it in vitro and in vivo. Furthermore, a serine-rich motif at the C terminus of Cbl, which is critical for PMA-induced 14-3-3 binding, is also phosphorylated by PKCalpha and PKCtheta in vitro. These results suggest that, by regulating tyrosine and serine phosphorylation of Cbl, PKC is able to control the association of Cbl with signaling intermediates, such as SH2 domain-containing proteins and 14-3-3 proteins, which may consequently result in the modulation of its function.

Subjective and external assessments of quality of life in schizophrenia: relationship to insight

OBJECTIVE

This study assessed the manner in which insight influenced schizophrenic patients' evaluation of their objective life conditions and the concurrent validity between patients' and clinicians' assessments of patients' global quality of life.

METHOD

Forty out-patients who fulfilled DSM-III-R criteria for schizophrenia were independently interviewed using the Lancashire Quality of Life Profile and the Standard of Living Interview. Insight was assessed using a self-report questionnaire, the Insight Scale.

RESULTS

For insightful patients there was a significant but modest correlation between objective and subjective indicators of quality of life. Likewise, a significant correlation between subjective and external evaluations of global quality of life was limited to those individuals who had good insight.

CONCLUSION

Diminished insight may limit the usefulness of the self-report methodology for assessing quality of life for some individuals with schizophrenia.

Dobutamine stress echocardiography in women with chest pain. Pilot phase data from the National Heart, Lung and Blood Institute Women's Ischemia Syndrome Evaluation (WISE)

OBJECTIVES

The aim of this project was to assess the utility of dobutamine stress echocardiography (DSE) for evaluation of women with suspected ischemic heart disease.

BACKGROUND

Most investigations addressing efficacy of diagnosis and treatment of coronary artery disease (CAD) have been performed in predominantly male populations. As part of the Women's Ischemia Syndrome Evaluation (WISE) study, DSE was assessed in women participating at the University of Florida clinical site.

METHODS

Women with chest pain or other symptoms suggestive of myocardial ischemia and clinically indicated coronary angiography were eligible for the WISE study. Enrolled subjects underwent DSE using a modified protocol. Coronary stenosis was assessed by core laboratory quantitative coronary angiography (QCA).

RESULTS

The 92 women studied ranged in age from 34 to 82 years (mean 57.5). All women had > or = 1 major risk for CAD, and most (89, 97%) had > or = 2 risk factors. In 78 women (85%), left ventricular wall motion was normal at baseline and during peak infusion. The remaining 14 women had wall motion abnormalities during DSE. By QCA, 25 women (27%) had > or = 50% coronary stenosis, including 10 with single-vessel obstruction. Dobutamine stress echocardiography was abnormal in 10 of these 25 women, yielding overall sensitivity of 40%, and 60% for multivessel stenosis. Exclusion of women with inadequate heart rate response yielded overall sensitivity of 50%, and 81.8% for multivessel stenosis. Dobutamine stress echocardiography was normal in 54 of the 67 women with < 50% coronary narrowing, specificity 80.6%.

CONCLUSIONS

Dobutamine stress echocardiography reliably detects multivessel stenosis in women with suspected CAD. However, DSE is usually negative in women with single-vessel stenosis, and in the larger subset without coronary stenosis. Ongoing protocols of the WISE study are expected to improve diagnostic accuracy in women with single-vessel disease, as well as provide important data in the substantial number of women with chest pain but without epicardial coronary artery stenosis.

The efficiency of acute care bed utilization in Newfoundland and Labrador

Hospital efficiency is closely related to utilization levels and length of stay. This study determined whether inappropriate bed utilization in Newfoundland was related to inefficiency or inadequate access to alternative services. It also compared Canadian Institute for Health information (CIHI) data to our survey to determine whether they provide comparable information for monitoring efficiency. Inappropriate acute care days were identified using a modified Appropriateness Evaluation Protocol. Average length of stay (ALOS) by service for each of the province's acute care institutions was also reviewed from 1993-94 to 1995-96 using the CIHI database. Hospital admissions were Inappropriate in 14.2 percent of 2,007 cases. Of the 14,194 days of care, 22.8 percent were inappropriate, with most (16.4 percent) being avoidable with better use of existing resources. Of the inappropriate days, 49.2 percent related to physicians' functions. The provincial ALOS fell from 5.70 days in 1993-94 to 5.39 days in 1995-96, but remains 10.5 percent above the national average.