TBX5 transcription factor regulates cell proliferation during cardiogenesis.

Mutations in human TBX5, a member of the T-box transcription factor gene family, cause congenital cardiac septation defects and isomerism in autosomal dominant Holt-Oram syndrome. To determine the cellular function of TBX5 in cardiogenesis, we overexpressed wild-type and mutant human TBX5 isoforms in vitro and in vivo. TBX5 inhibited cell proliferation of D17 canine osteosarcoma cells and MEQC quail cardiomyocyte-like cells in vitro. Mutagenesis of the 5' end of the T-box but not the 3' end of the T-box abolished this effect. Overexpression of TBX5 in embryonic chick hearts showed that TBX5 inhibits myocardial growth and trabeculation. TBX5 effects in vivo were abolished by Gly80Arg missense mutation of the 5' end of the T-box. PCNA analysis in transgenic chick hearts revealed that TBX5 overexpression does suppress embryonic cardiomyocyte proliferation in vivo. Inhibitory effects of TBX5 on cardiomyocyte proliferation include a noncell autonomous process in vitro and in vivo. TBX5 inhibited proliferation of both nontransgenic cells cocultured with transgenic cells in vitro and nontransgenic cardiomyocytes in transgenic chick hearts with mosaic expression of TBX5 in vivo. Immunohistochemical studies of human embryonic tissues, including hearts, also demonstrated that TBX5 expression is inversely related to cellular proliferation. We propose that TBX5 can act as a cellular arrest signal during vertebrate cardiogenesis and thereby participate in modulation of cardiac growth and development.

Identification and localization of TBX5 transcription factor during human cardiac morphogenesis.

Mutations in the TBX5 transcription factor gene cause human cardiac malformation in Holt-Oram syndrome. To identify and localize TBX5 during cardiac morphogenesis, we performed immunohistochemical studies of TBX5 protein cardiac expression during human embryogenesis. Specific antibody to human TBX5 was generated in rabbits with a TBX5 synthetic peptide and affinity purification of antiserum. Anti-TBX5 was used in immunohistochemical analyses of human cardiac tissue. In embryonic and adult heart, TBX5 is expressed throughout the epicardium and in cardiomyocyte nuclei in myocardium of all four cardiac chambers. Endocardial expression of TBX5 is only present in left ventricle. Asymmetric left-sided transmyocardial gradients of TBX5 protein expression were observed in embryonic but not adult hearts. Human cardiac expression of TBX5 protein correlates with the cardiac manifestations of Holt-Oram syndrome. TBX5 transmyocardial protein gradients may contribute to normal patterning of the human heart during embryogenesis.

Mutations in the protein kinase A R1alpha regulatory subunit cause familial cardiac myxomas and Carney complex.

Cardiac myxomas are benign mesenchymal tumors that can present as components of the human autosomal dominant disorder Carney complex. Syndromic cardiac myxomas are associated with spotty pigmentation of the skin and endocrinopathy. Our linkage analysis mapped a Carney complex gene defect to chromosome 17q24. We now demonstrate that the PRKAR1alpha gene encoding the R1alpha regulatory subunit of cAMP-dependent protein kinase A (PKA) maps to this chromosome 17q24 locus. Furthermore, we show that PRKAR1alpha frameshift mutations in three unrelated families result in haploinsufficiency of R1alpha and cause Carney complex. We did not detect any truncated R1alpha protein encoded by mutant PRKAR1alpha. Although cardiac tumorigenesis may require a second somatic mutation, DNA and protein analyses of an atrial myxoma resected from a Carney complex patient with a PRKAR1alpha deletion revealed that the myxoma cells retain both the wild-type and the mutant PRKAR1alpha alleles and that wild-type R1alpha protein is stably expressed. However, in this atrial myxoma, we did observe a reversal of the ratio of R1alpha to R2beta regulatory subunit protein, which may contribute to tumorigenesis. Further investigation will elucidate the cell-specific effects of PRKAR1alpha haploinsufficiency on PKA activity and the role of PKA in cardiac growth and differentiation.

Atrial form and function: lessons from human molecular genetics.

Molecular genetic analyses of human hereditary disorders that affect cardiac atrial structure and function have recently identified several genes that regulate atrial morphogenesis. Mutations of the TBX5, NKX2.5, EVC, and PRKAR1 alpha genes all result in abnormalities of human atrial growth and development, and mutations in at least one gene results in familial atrial fibrillation and is as yet unidentified. Ongoing studies to find interactions between these transcription factors and intracellular signaling molecules and other as yet unknown genes are establishing critical pathways in human cardiogenesis. Human investigation and experimental animal models of heart development synergize to elucidate etiologies of common congenital heart disease.

Suicide and violence risk in law enforcement: practical guidelines for risk assessment, prevention, and intervention.

Research and anecdotal reports indicate that suicide and violence risk may be higher among members of law enforcement than those in other occupational categories. This article examines the phenomenon of suicide and violence risk within this population, and law enforcement cultural variables that may contribute to elevated risk. Suicide and violence risk factors and clues unique to law enforcement are described, as are intervention approaches which may be helpful to managing and reducing risk.

Excessive microtubules are not responsible for depressed force per cross-bridge in cardiac neural-crest-ablated embryonic chick hearts.

Ablation of the cardiac neural crest (CNCA) in embryonic chicks results in a high incidence of persistent truncus arteriosus, a congenital heart defect associated with decreased myocardial contractility. Using left ventricular trabeculae from chicks at embryonic day (ED) 15, we have previously shown that the twitch force of intact preparations is significantly reduced whereas the maximal calcium-activated force of skinned preparations is not significantly different in CNCA and sham-operated animals. We also previously found that the ventricular content of myosin, as well as of actin and tropomyosin, was nearly doubled in ED 15 hearts after CNCA. Since the number of cross-bridges is proportional to the myosin concentration, these data suggest that the force exerted per cross-bridge is decreased in CNCA hearts. We investigated the possibility that the decrease in force per cross-bridge is caused by inhibition of the contractile apparatus by excessive microtubules. To the contrary, we found that the total beta-tubulin content and the fraction of beta-tubulin polymerized in microtubules measured by Western blotting was the same in ventricular muscle strips from CNCA and sham-operated embryos. Furthermore, exposure to microtubule-destabilizing agents did not improve the force-producing capability of the contractile apparatus in CNCA embryos. We conclude that depression of force per cross-bridge in hearts from CNCA embryos is not due to an excess of microtubules.

An empirical study of the psychodynamics of suicide.

This paper presents results from an empirical study of four key psychodynamic concepts (self-directed aggression, object loss, ego functioning disturbance, pathological object relations) of suicidal behavior. The sample consists of hospitalized psychiatric patients following a suicide attempt (attempters: n = 52) and demographically similar hospitalized psychiatric patients with no history of suicidal behavior (controls: n = 47). The study was designed to ascertain whether attempters differed from matched psychiatric control patients on the four psychodynamic constructs hypothesized to be associated with suicide. It was predicted that attempters would manifest higher levels of depression and self-targeted anger, a more significant history of loss, less adaptive defenses, and more primitive object representations. Results strongly supported an object-relational view of suicidal behavior. In addition, support for the loss hypothesis was found in the identification of one specific constellation of losses. Namely, attempters were significantly more likely to report a history of childhood loss combined with a recent loss in adulthood than were their nonattempter counterparts. Limited support was provided for the other two hypotheses in differentiating suicidal from nonsuicidal severely ill psychiatric patients. This unexpected finding is examined and suggestions are made for the refinement and greater specification of psychodynamic theories regarding the etiology of suicidal behavior, with the aim of differentiating individuals prone to such action from those with similar psychopathology and dynamic issues who do not actually attempt suicide. Limitations of the study are discussed and implications of the findings for the theory and treatment of suicidal behavior are offered.

The role of the psychologist in crisis/hostage negotiations.

Over the past three decades, there has been a noted increase in hostage and barricade incidents involving perpetrators with a variety of emotional, economic, and political motives. A hostage incident may be defined as an incident in which (a) perpetrator(s) hold(s) one or more persons against their will in a location known to police. A barricade incident, on the other hand, is an incident without hostages in which a perpetrator is barricaded, also in a location known to police and refusing to surrender. Approximately 25 years ago, a theory of crisis/hostage negotiations was developed which has been continuously refined in field applications. This article will define the goal of crisis/hostage negotiation, review the history of hostage taking from biblical times to the present, review the utilization of psychologists and other mental health consultants by police crisis/hostage negotiation teams, and discuss the four roles and related functions of psychologists on crisis/hostage negotiation teams.

Neural crest is involved in development of abnormal myocardial function.

Around 85% of embryos homozygous for the splotch (Sp2H) allele (Sp2H/Sp2H), a Pax3 mutation, develop persistent truncus arteriosus (PTA), a defect related to the cardiac neural crest. These embryos die by 14.5 days post coitum. In an investigation of the cause of lethality in these embryos, we used digital video imaging microscopy to examine beating embryonic hearts in situ at 13.5 dpc. The hearts of Sp2H/Sp2H embryos with PTA clearly showed poor function when compared with normal litter mates. Contractile force was examined in detergent-skinned ventricular muscle strips from Sp2H/Sp2H embryos at ages 12.5 and 13.5 dpc. There was no significant difference in the maximum force or in myosin content between Sp2H/Sp2H and control groups, indicating no significant dysfunction of the contractile apparatus in hearts from Sp2H/Sp2H embryos. Ca2+ transients were examined in enzymatically-dissociated ventricular myocytes and were significantly reduced in defective hearts, indicating that reduced cardiac function in Sp2H/Sp2H embryos with PTA was due to impaired excitation-contraction (EC) coupling. Ca2+ currents were examined using the perforated patch clamp technique. The magnitude of the Ca2+ current was found to be reduced by approximately 3.2-fold in Sp2H/Sp2H hearts with PTA compared to normal. Since the sarcoplasmic reticulum is sparse or absent in the embryonic heart, the impaired EC coupling was due to the reduction in Ca2+ current. These observations suggest that neural crest abnormalities result in a defect in EC coupling, causing depressed myocardial function and death in utero from cardiac failure. Interestingly, Sp2H/Sp2H hearts without PTA had normal EC coupling. These results indicated that impaired EC coupling was secondary to the Pax3 mutation. The findings in this report indicate an important role for the neural crest in the development of normal myocardial function, and represent the first demonstration of impaired excitation-contraction coupling in a genetically-defined embryonic mammalian model of a cardiac structural defect.

Effect of cardiac neural crest ablation on contractile force and calcium uptake and release in chick heart.

Cardiac neural crest ablation (CNCA) in the chick embryo at stages 8-10 results in reduced contractility of the heart that can be observed as early as stage 14. We found that intact trabeculae from embryonic day (E) 15 experimental animals after CNCA display an approximately 50% decrease in twitch force relative to sham-operated E15 control animals. In control and CNCA trabeculae skinned in Triton X-100 and bathed in our standard solutions, neither maximum Ca(2+)-activated force nor Ca2+ sensitivity of the contractile apparatus was significantly different. CNCA resulted in a marked reduction in the magnitude of the Ca2+ transient in trabeculae, estimated using fura 2 acetoxymethyl ester. CNCA had no effect on the half-time of Ca2+ loading by the sarcoplasmic reticulum (SR) of saponin skinned trabeculae at fixed Ca2+. However, it slightly reduced the Ca2+ sensitivity of Ca2+ uptake by the SR. Its most dramatic effect was to essentially abolish Ca(2+)-induced Ca2+ release from the SR. These effects on Ca2+ metabolism explain, in part, the decrease in the intracellular Ca2+ transient and myocardial contractility observed with CNCA.

An empirical study of the psychodynamics of suicide: a preliminary report.

Preliminary results from a study of psychodynamic constructs are presented based on data from inpatients following a suicide attempt. The study examines the association between four psychodynamic constructs, severity of suicidal intent, and severity of depressive symptomatology in a sample of hospitalized suicide attempters. Higher levels of suicidal intent were associated with less differentiated self and object representations and less emotional investment in relationships. More severe depressive symptoms in suicide attempters were correlated with more self-targeted anger, less eternally directed anger, higher levels of shame and guilt, more affectively negative views of relationships, greater use of maladaptive and self-sacrificing defenses, and more impaired reality testing. These findings offer some preliminary empirical support for the validity of psychodynamic theories of suicidal behavior.

Inhibition of human internal mammary artery contractions. An in vitro study of vasodilators.

The internal mammary artery is currently the preferred conduit for myocardial revascularization; however, perioperative vasospasm of the internal mammary artery may limit its use as a bypass graft. The ability of various vasodilators to inhibit internal mammary artery contraction was investigated with the use of discarded segments of human internal mammary artery not used in coronary artery bypass grafting. Ring segments of human internal mammary arteries were suspended on strain gauges in muscle baths containing 37 degrees C Krebs solution for measurement of isometric tension in vitro. Arterial contraction was stimulated by elevating the extracellular potassium concentration to 70 mmol/L or by exposure to a 10 mumol/L concentration of norepinephrine, and inhibition of contraction by vasodilators was measured. The order of potency to inhibit potassium-induced contraction was as follows: nifedipine > verapamil > nitroprusside > papaverine. At maximal effective doses, nifedipine, verapamil, and papaverine almost completely inhibited potassium-induced contraction, whereas nitroprusside inhibited contraction by only 55%. When norepinephrine was used to contract the arteries, a biphasic relaxation curve was seen with nifedipine, but not with other vasodilator drugs. The order of potency to inhibit norepinephrine-induced contraction was as follows: nifedipine > nitroprusside > verapamil > papaverine. Maximal inhibition of norepinephrine contraction by these vasodilators ranged from 68% to 95%. Nitroglycerin, isoproterenol, and adenosine produced little or no inhibition of internal mammary artery contraction caused by potassium or norepinephrine. Although nifedipine was the most potent vasodilator, papaverine produced the greatest maximal inhibition of both potassium- and norepinephrine-induced contraction of human internal mammary artery.

Emergency coronary artery bypass surgery for failed percutaneous coronary angioplasty. A 10-year experience.

Six hundred ninety-nine patients have required emergency coronary artery bypass after failed elective percutaneous coronary angioplasty during the decade September 1980 through December 1990. This represents 4% of 9860 patients having 12,146 elective percutaneous coronary angioplasty procedures during this interval. Emergency coronary artery bypass was required for acute refractory myocardial ischemia in 82%. Hospital mortality rate for all patients was 3.1%; 3.7% in patients with refractory myocardial ischemia but 0.8% in patients without refractory myocardial ischemia, p = 0.08. Postprocedural Q-wave myocardial infarctions were observed in 21% versus 2.4%, p less than 0.0001, and intra-aortic balloon pumping was required in 19% with versus 0.8% without refractory myocardial ischemia, p less than 0.0001. Multivessel disease, p = 0.004, age older than 65 years, p = 0.005, and refractory myocardial ischemia, p = 0.08, interacted to produce the highest risk of in-hospital death. Follow-up shows that there have been 28 additional late deaths, including 23 of cardiac causes for a 91% survival at 5 years. Freedom from both late death and Q-wave myocardial infarction at 5 years was 61%. In the group going to emergency coronary artery bypass with refractory myocardial ischemia, the late cardiac survival was 90%, and in those without ischemia, 92% at 5 years, p = not significant. The MI--free survival in the group with refractory ischemia, however, was 56% versus 83% in the group without ischemia, p less than 0.0001. Multivariate analysis showed the highest late event rates for patients with Q-wave myocardial infarction at the initial emergency coronary artery bypass, age older than 65 years, angina class III or IV, and prior coronary bypass surgery. In spite of a continuing high incidence of early acute myocardial infarction and an increasing operative mortality rate (7%) in the latest 3 years cohort of patients, excellent late survival and low subsequent cardiac event rates demonstrate the lasting effectiveness of prompt, successful emergency coronary bypass surgery for failed percutaneous coronary angioplasty.

The role of violence in decisions about hospitalization from the psychiatric emergency room.

OBJECTIVE: The authors evaluated the relationship between violent behavior and decision making about hospitalization from the psychiatric emergency room. METHOD: The medical charts of 321 patients evaluated in an urban psychiatric emergency room during a 4-week period were reviewed retrospectively. Violent behavior was defined as physical attacks on persons or fear-inducing behavior before or during the evaluation in the emergency room; and its value in predicting hospitalization decisions was assessed with logistic regression analyses that also included 12 demographic, clinical, and contextual variables. RESULTS: A model predicting hospitalization decisions was developed and cross-validated. Although violent patients were more likely to be hospitalized than nonviolent patients, clinical variables such as diagnosis and overall severity of psychiatric impairment were more important than violent behavior in predicting hospitalization decisions. CONCLUSIONS: Despite legal pressures to focus on overt behaviors such as violence as a basis for liability prevention and civil commitment, clinicians in this study did not allocate inpatient resources to preventively detain persons unlikely to benefit from treatment. Rather, they hospitalized the most severely disturbed patients, with diagnoses such as schizophrenic and manic disorders for which a widely accepted therapeutic armamentarium exists. The results are consistent with clinical recommendations that in the evaluation of the violent patient, attention needs to be given to the underlying disorder, since violent behavior itself can result from diverse causes only some of which require inpatient psychiatric treatment.

Influence of short hamstring muscles on the pelvis and lumbar spine in standing and during the toe-touch test.

This study examined the influence of short hamstring muscles of healthy men on: (1) the angles of pelvic inclination and the lumbar curve in standing, and (2) the flexion range of motion of the pelvis and lumbar spine during the toe-touch test. Surface markers over bony landmarks and photography were used to examine ten men without short hamstrings and ten men with short hamstrings while standing and after assuming the toe-touch position for two repeated trials. ANOVAS showed no significant differences between groups for the angles of pelvic inclination and lumbar curve in standing. During the toe-touch test, the mean flexion range of motion of the pelvis on the thigh was less for the men with short hamstrings (52°; SD, 9°) than for the men without short hamstrings (72°; SD, 4°) (P < 0.001), but the lumbar flexion range of motion was not significantly different.

Cardioplegia for transplantation: failure of extracellular solution compared with Stanford or UW solution.

Crystalloid cardioplegia with an extracellular fluid formulation is widely used for donor heart protection. A survey of 109 transplant programs yielded 62 replies with 42% of respondents using variations of extracellular solution and 45% using the dextrose and mannitol-based Stanford solution. These two commonly used clinical solutions and University of Wisconsin (UW) solution, which has had success in clinical hepatic and renal transplantation, were compared in a canine model of cardiac transplantation. After antegrade hypothermic cardioplegic arrest, the experimental hearts were excised and stored at 4 degrees C for 6 hours (n = 29). An oxygenated, blood-primed isolated heart preparation was used for reperfusion. After a rest of 45 minutes, cardiac output was increased against constant afterload until a left atrial pressure of 15 mm Hg was reached. The maximum cardiac performance measured by cardiac index, minute work, and stroke work was highly significantly better with Stanford or UW solution protection than with the extracellular solutions (p less than 0.0001). Assuming a cardiac index of 50 mL.kg-1.min-1 is necessary for successful separation from cardiopulmonary bypass, only 1 of 14 extracellular and 15 of 15 Stanford and UW animals would have survived (p less than 0.0001). This study strongly suggests that extracellular cardioplegia is inferior for cardiac transplantation and that programs using this solution should reevaluate their method of myocardial protection for donor hearts.