The impact of PTSD on associations between sex hormones and cardiovascular disease symptoms

Background: Women have twice the lifetime prevalence of posttraumatic stress disorder (PTSD) relative to men, and PTSD is a known risk factor for cardiovascular disease (CVD). Two sex hormones - estradiol and progesterone - have been found to impact both PTSD and CVD symptomatology, but the way in which sex hormones influence cardiovascular physiology among individuals with PTSD is not well understood.Objective: This study sought to clarify the association between sex hormones, PTSD, and CVD among trauma-exposed women.Method: Sixty-six trauma-exposed women (M age = 31.45, SD = 8.92) completed a clinical interview for PTSD and self-reported CVD symptoms; estradiol and progesterone were assayed from blood samples. The association between each sex hormone and CVD symptoms was analyzed, controlling for age, systolic blood pressure (BP), and diastolic BP.Results: Neither estradiol nor the PTSD-by-estradiol interaction was significantly associated with CVD symptoms. Higher progesterone and, relatedly, progesterone-to-estradiol ratio (PE ratio) were each significantly associated with greater CVD symptom severity, but only for individuals with lower relative PTSD severity.Conclusions: The findings indicate that PTSD moderates the relationship between progesterone and CVD symptoms, and further research is warranted to reconcile findings in existing literature regarding the direction of and mechanisms behind this relationship.

The assessment of cardiac risk in patients taking lamotrigine; a systematic review

OBJECTIVE

The Food and Drug Administration (FDA) warned about lamotrigine's arrhythmogenicity based on in vitro data. This systematic review investigates lamotrigine's effect on cardiac conduction and risk of sudden cardiac death (SCD) in individuals with and without cardiovascular disease.

METHODS

We searched Web of Science and PubMed from inception through August 2021. We included studies measuring electrocardiogram (ECG) changes, laboratory abnormalities, or SCD among patients taking lamotrigine. Studies examining sudden unexpected death in epilepsy were excluded for scope. Two reviewers assessed articles and extracted data. We used the Effective Public Healthcare Panacea Project tool to evaluate confidence in evidence.

RESULTS

Eight randomized controlled trials, 9 nonrandomized observational studies, and 24 case reports were identified, with >3054 total participants, >1606 of whom used lamotrigine. One randomized trial of older patients found an average QRS increase of 3.5 +/- 13.1 ms. Fifteen studies reported no changes in ECG parameters. Case reports documented QRS widening (13), Brugada syndrome (6), QTc prolongation (1) and SCD (2), though many ingested toxic quantities of lamotrigine and/or other medications.

CONCLUSIONS

Evidence is insufficient to support the breadth of the FDA warning concerning lamotrigine's cardiac risk. Lamotrigine at therapeutic doses may be associated with modest, non-dangerous QRS widening.

Polygenic loading for major depression is associated with specific medical comorbidity

Major depressive disorder frequently co-occurs with medical disorders, raising the possibility of shared genetic liability. Recent identification of 15 novel genetic loci associated with depression allows direct investigation of this question. In cohorts of individuals participating in biobanks at two academic medical centers, we calculated polygenic loading for risk loci reported to be associated with depression. We then examined the association between such loading and 50 groups of clinical diagnoses, or topics, drawn from these patients' electronic health records, determined using a novel application of latent Dirichilet allocation. Three topics showed experiment-wide association with the depression liability score; these included diagnostic groups representing greater prevalence of mood and anxiety disorders, greater prevalence of cardiac ischemia, and a decreased prevalence of heart failure. The latter two associations persisted even among individuals with no mood disorder diagnosis. This application of a novel method for grouping related diagnoses in biobanks indicate shared genetic risk for depression and cardiac disease, with a pattern suggesting greater ischemic risk and diminished heart failure risk.

The Positive Emotions after Acute Coronary Events behavioral health intervention: Design, rationale, and preliminary feasibility of a factorial design study

BACKGROUND

Positive psychological constructs, such as optimism, are associated with greater participation in cardiac health behaviors and improved cardiac outcomes. Positive psychology interventions, which target psychological well-being, may represent a promising approach to improving health behaviors in high-risk cardiac patients. However, no study has assessed whether a positive psychology intervention can promote physical activity following an acute coronary syndrome.

OBJECTIVE

In this article we will describe the methods of a novel factorial design study to aid the development of a positive psychology-based intervention for acute coronary syndrome patients and aim to provide preliminary feasibility data on study implementation.

METHODS

The Positive Emotions after Acute Coronary Events III study is an optimization study (planned N = 128), subsumed within a larger multiphase optimization strategy iterative treatment development project. The goal of Positive Emotions after Acute Coronary Events III is to identify the ideal components of a positive psychology-based intervention to improve post-acute coronary syndrome physical activity. Using a 2 × 2 × 2 factorial design, Positive Emotions after Acute Coronary Events III aims to: (1) evaluate the relative merits of using positive psychology exercises alone or combined with motivational interviewing, (2) assess whether weekly or daily positive psychology exercise completion is optimal, and (3) determine the utility of booster sessions. The study's primary outcome measure is moderate-to-vigorous physical activity at 16 weeks, measured via accelerometer. Secondary outcome measures include psychological, functional, and adherence-related behavioral outcomes, along with metrics of feasibility and acceptability. For the primary study outcome, we will use a mixed-effects model with a random intercept (to account for repeated measures) to assess the main effects of each component (inclusion of motivational interviewing in the exercises, duration of the intervention, and inclusion of booster sessions) from a full factorial model controlling for baseline activity. Similar analyses will be performed on self-report measures and objectively-measured medication adherence over 16 weeks. We hypothesize that the combined positive psychology and motivational interviewing intervention, weekly exercises, and booster sessions will be associated with superior physical activity.

RESULTS

Thus far, 78 participants have enrolled, with 72% of all possible exercises fully completed by participants.

CONCLUSION

The Positive Emotions after Acute Coronary Events III study will help to determine the optimal content, intensity, and duration of a positive psychology intervention in post-acute coronary syndrome patients prior to testing in a randomized trial. This study is novel in its use of a factorial design within the multiphase optimization strategy framework to optimize a behavioral intervention and the use of a positive psychology intervention to promote physical activity in high-risk cardiac patients.

Rapid screening for major depression in post-myocardial infarction patients: an investigation using Beck Depression Inventory II items

OBJECTIVE

To determine the ability of three questions from the Beck Depression Inventory II (BDI-II) to detect major depressive disorder (MDD) in a cohort of patients hospitalised for acute myocardial infarction (MI).

DESIGN

Prospective observational study.

SETTING

Coronary care unit and cardiac step-down unit of an urban academic medical centre.

PATIENTS

131 post-MI patients within 72 h of symptom onset.

INTERVENTIONS

Patients were administered the BDI-II and participated in a structured diagnostic interview for MDD. Three individual BDI-II items (regarding sadness, loss of interest and loss of pleasure) were examined individually and in two-question combinations to determine their ability to screen for MDD.

MAIN OUTCOME MEASURES

Sensitivity, specificity, negative and positive predictive values and proportion of patients with MDD correctly identified.

RESULTS

The individual items and two-question combinations had good sensitivity (76-94%), specificity (70-88%) and negative predictive values (97-99%). Item 1 (sadness) performed the best of the individual items (48% with a positive response to the item had MDD; 3% with a negative response had MDD; over 80% of patients with MDD were correctly identified). A combination of questions about sadness and loss of interest performed best among the two-question combinations (37% with positive response had MDD v 1% with a negative response; 94% of patients with MDD were identified).

CONCLUSIONS

One to two questions regarding sadness and loss of interest serve as simple and effective screening tools for post-MI depression.

Facile C(sp(2))/OR bond cleavage by Ru or Os

Os(H)(3)ClL(2) (L = P(i)Pr(3) or P(t)Bu(2)Me) are shown to be useful "precursors" to "OsHClL(2)", which react with vinyl ethers to form first an eta(2)-olefin adduct and then isomerize to the carbenes, OsHCl[CMe(OR)]L(2). Subsequent R- and L-dependent reactions involve C(sp(2))-OR bond cleavage, to make either carbyne or vinylidene complexes. The mechanisms of these reactions are explored, and the thermodynamic disparity of Ru versus Os and the influence of the OR group and the spectator phosphine ligands are discussed based on DFT (B3PW91) calculations.

Effect of Lewis acidity on the synthesis of RuHCl(CO)(phosphine)(2): subtle influence of steric and electronic effects among P(i)Pr(3), P(i)Pr(2)(3,5-(CF(3))(2)C(6)H(3)), and P(i)Pr(2)Me

To evaluate the influence of steric, electronic, and synthetic factors, the synthesis of RuHCl(CO)[P(i)Pr(2)(3,5-(CF(3))(2)C(6)H(3))](2) was carried out, and its Lewis acidity toward Cl- was compared to that of RuHCl(CO)(P(i)Pr(3))(2). In this synthesis, Na(2)CO(3) was shown to be a more effective base than NEt(3), because Na+ can better mask the nucleophilicity of the potential ligand Cl-. An X-ray structure determination of the hydride-free species RuCl(2)(CO)(P(i)Pr(2)Me)(2) shows it to be a dimer, and this solid-state structure persists in solution, but as several different isomers. The synthesis of RuHCl(CO)(P(i)Pr(2)Me)(3) shows that three of this smaller phosphine can crowd around Ru, but dynamic NMR spectra show one phosphine to be weakly bound. The rate of reaction of Me(3)SiC(triple bond)CH with this molecule is suppressed by added free P(i)Pr(2)Me, indicating phosphine dissociation to be a mechanistic component.

Synthesis and reactivity of silyl vinylketenes: a formal interrupted Dötz benzannulation with unexpected silyl migration

[reaction: see text]. An efficient method for the generation of silyl vinylketenes from the thermal reaction of Fischer carbene complexes with silyl-substituted phenylacetylenes is described. Although the silyl vinylketene products are highly stable, conditions have been identified to induce a benzannulation/silyl migration process, providing aromatic silyl ethers.

A comparison of the influences of alkoxide and thiolate ligands on the electronic structure and reactivity of molybdenum(3+) and tungsten(3+) complexes. preparation and structures of M(2)(O(T)Bu)(2)(S(t)Bu)(4), [Mo(S(t)Bu)(3)(NO)](2), and W(S(t)Bu)(3)(NO)(py)

M(2)(O(t)Bu)(6) compounds (M = Mo, W) react in hydrocarbon solvents with an excess of (t)BuSH to give M(2)(O(t)Bu)(2)(S(t)Bu)(4), red, air- and temperature-sensitive compounds. (1)H NMR studies reveal the equilibrium M(2)(O(t)Bu)(6) + 4(t)BuSH <==> M(2)(O(t)Bu)(2)(S(t)Bu)(4) + 4(t)BuOH proceeds to the right slowly at 22 degrees C. The intermediates M(2)(O(t)Bu)(4)(S(t)Bu)(2), M(2)(O(t)Bu)(3)(S(t)Bu)(3), and M(2)(O(t)Bu)(5)(S(t)Bu) have been detected. The equilibrium constants show the M-O(t)Bu bonds to be enthalpically favored over the M-S(t)Bu bonds. In contrast to the M(2)(O(t)Bu)(6) compounds, M(2)(O(t)Bu)(2)(S(t)Bu)(4) compounds are inert with respect to the addition of CO, CO(2), ethyne, (t)BuC triple bond CH, MeC triple bond N, and PhC triple bond N. Addition of an excess of (t)BuSH to a hydrocarbon solution of W(2)(O(t)Bu)(6)(mu-CO) leads to the rapid expulsion of CO and subsequent formation of W(2)(O(t)Bu)(2)(S(t)Bu)(4). Addition of an excess of (t)BuSH to hydrocarbon solutions of [Mo(O(t)Bu)(3)(NO)](2) and W(O(t)Bu)(3)(NO)(py) gives the structurally related compounds [Mo(S(t)Bu)(3)(NO)](2) and W(S(t)Bu)(3)(NO)(py), with linear M-N-O moieties and five-coordinate metal atoms. The values of nu(NO) are higher in the related thiolate compounds than in their alkoxide counterparts. The bonding in the model compounds M(2)(EH)(6), M(2)(OH)(2)(EH)(4), (HE)(3)M triple bond CMe, and W(EH)(3)(NO)(NH(3)) and the fragments M(EH)(3), where M = Mo or W and E = O or S, has been examined by DFT B3LYP calculations employing various basis sets including polarization functions for O and S and two different core potentials, LANL2 and relativistic CEP. BLYP calculations were done with ZORA relativistic terms using ADF 2000. The calculations, irrespective of the method used, indicate that the M-O bonds are more ionic than the M-S bonds and that E ppi to M dpi bonding is more important for E = O. The latter raises the M-M pi orbital energies by ca. 1 eV for M(2)(OH)(6) relative to M(2)(SH)(6). For M(EH)(3) fragments, the metal d(xz)(),d(yz)() orbitals are destabilized by OH ppi bonding, and in W(EH)(3)(NO)(NH(3)) the O ppi to M dpi donation enhances W dpi to NO pi* back-bonding. Estimates of the bond strengths for the M triple bond M in M(2)(EH)(6) compounds and M triple bond C in (EH)(3)M triple bond CMe have been obtained. The stronger pi donation of the alkoxide ligands is proposed to enhance back-bonding to the pi* orbitals of alkynes and nitriles and facilitate their reductive cleavage, a reaction that is not observed for their thiolate counterpart.

Single-molecule magnets: preparation and properties of mixed-carboxylate complexes

Methods are reported for the preparation of mixed-carboxylate versions of the [Mn(12)O(12)(O(2)CR)(16)(H(2)O)(4)] family of single-molecule magnets (SMMs). [Mn(12)O(12)(O(2)CCHCl(2))(8)(O(2)CCH(2)Bu(t))(8)(H(2)O)(3)] (5) and [Mn(12)O(12)(O(2)CHCl(2))(8)(O(2)CEt)(8)(H(2)O)(3)] (6) have been obtained from the 1:1 reaction of the corresponding homocarboxylate species. Complex 5.CH(2)Cl(2).H(2)O crystallizes in the triclinic space group P1 with, at -165 degrees C, a = 15.762(1), b = 16.246(1), c = 23.822(1) A, alpha = 103.92(1), beta = 104.50(1), gamma = 94.23(1) degrees, Z = 2, and V = 5674(2) A(3). Complex 6.CH(2)Cl(2) crystallizes in the triclinic space group P1 with, at -158 degrees C, a = 13.4635(3), b = 13.5162(3), c = 23.2609(5) A, alpha = 84.9796(6), beta = 89.0063(8), gamma = 86.2375(6) degrees, Z = 2, and V = 4207.3(3) A(3). Complexes 5 and 6 both contain a [Mn(12)O(12)] core with the CHCl(2)CO(2-) ligands ordered in the axial positions and the RCO(2-) ligands (R = CH(2)Bu(t) (5) or Et (6)) in equatorial positions. There is, thus, a preference for the CHCl(2)CO(2-) to occupy the sites lying on the Mn(III) Jahn-Teller axes, and this is rationalized on the basis of the relative basicities of the carboxylate groups. Direct current magnetic susceptibility studies in a 10.0 kG field in the 2.00-300 K range indicate a large ground-state spin, and fitting of magnetization data collected in the 10.0-70.0 kG field and 1.80-4.00 K temperature range gave S = 10, g = 1.89, and D = -0.65 K for 5, and S = 10, g = 1.83, and D = -0.60 K for 6. These values are typical of [Mn(12)O(12)(O(2)CR)(16)(H(2)O)(4)] complexes. Alternating current susceptibility studies show the out-of-phase susceptibility (chi(M)' ') signals characteristic of the slow relaxation in the millisecond time scale of single-molecule magnets. Arrhenius plots obtained from chi(M)' ' versus T data gave effective barriers to relaxation (U(eff)) of 71 and 72 K for 5 and 6, respectively. (1)H NMR spectra in CD(2)Cl(2) show that 5 and 6 are the main species present on dissolution, but there is evidence for some ligand distribution between axial and equatorial sites, by intra- and/or intermolecular exchange processes.

Behavioral disturbances in geropsychiatric inpatients across dementia types

The objective of this study was to compare differences in behavioral, psychiatric, and cognitive status among geropsychiatric inpatients with Alzheimer's, vascular, alcohol-induced, and mixed dementia. Participants included 150 patients with dementia consecutively admitted to an acute geropsychiatric inpatient unit. Measures included the Mini-Mental State Examination, Cohen-Mansfield Agitation Inventory, Cumulative Illness Rating Scale, Basic and Independent Activities of Daily Living, Positive and Negative Syndrome Scale for Schizophrenia, and the Initiation/Perseveration subscale of the Dementia Rating Scale. No significant differences existed in the character or severity of agitation among patients with Alzheimer's, vascular, alcohol-related and mixed dementia. Interestingly, patients with vascular dementia compared to patients with other dementias admitted for behavioral disturbances were less cognitively impaired and more medically burdened.

Assessment and understanding of pain in patients with dementia

The literature on pain in dementia patients is reviewed. A summary of methods for assessment of pain in demented elderly persons and an examination of studies that used such methods are included. In addition, literature theorizing a decrease in affective pain in this population is discussed; management of pain in such patients is not discussed extensively. Research reveals 3 major findings: (a) a moderate decrease in pain occurs in cognitively impaired elderly persons, (b) communicative dementia patients' reports of pain tend to be as valid as those of cognitively intact patients, and (c) assessment scales developed thus far for noncommunicative patients require improvement in accuracy and facility. Many questions about pain in dementia patients remain, and the continued development of valid pain assessment techniques is a necessity.

Unsaturated Ru(0) species with a constrained bis-phosphine ligand: [Ru(CO)2(tBu2PCH2CH2PtBu2)]2. Comparison to [Ru(CO)2(PtBu2Me)2]

The synthesis of Ru(C2H4)(CO)2(dtbpe) (dtbpe = tBu2PC2H4PtBu2), then green [Ru(CO)2(dtbpe)]n is described. In solution, n = 1, while in the solid state, n = 2; the dimer has two carbonyl bridges. DFTPW91, MP2, and CCSD(T) calculations show that the potential energy surface for bending one carbonyl out of the RuP2C(O) plane is essentially flat. Ru(CO)2(dtbpe) reacts rapidly in benzene solution to oxidatively add the H-E bond of H2, HCl, HCCR (R = H, Ph), [HOEt2]BF4, and HSiEt3. The H-C bond of C6HF5 oxidatively adds at 80 degrees C. CO adds, as does the C=C bond of H2C=CHX (X = H, F, Me). The following do not add: N2, THF, acetone, H3COH, and H2O.

A new class of electron-rich unsaturated molecules: Ru2HnX4-n(PiPr3)4, X = anion

Synthesis, spectroscopic, and X-ray structural characterization of Ru2HnCl4-nL4 (n = 2, 3) and Ru2H2F2L4 (L = PiPr3) are reported. The structure of Ru2HCl3L4 is also reported. These are dinuclear species containing two five-coordinate, approximately square-pyramidal metal atoms. Halides, not hydrides, preferentially occupy bridging sites, and the RuXL2 terminal moiety shows limited fluxionality, but hydrides do not migrate between metals. The limited steric protection provided by PiPr3 is evident from the dimerization observed and from the fact that all these structures have rather small [symbol: see text]P-Ru-P (approximately 105 degrees). Also reported are RuHXL2 species with X = acetylacetonate, phenoxide, O3SCH3, and O3SCF3. Several examples of coordinated olefin to complexed carbene conversions are used to test the influence of anion X on reactivity.

Dimolybdenum bis((S,S,S)-triisopropanolaminate(3-)): a blue compound with an unusual Mo-Mo triple bond

Mo2(OtBu)6 and Mo2(NMe2)6 each react with (S,S,S)-triisopropanolamine (2 equiv) in benzene to yield dimolybdenum bis((S,S,S)-isopropanolaminate(3-)), Mo2[(OC-(S)-HMeCH2)3N]2 (M identical to M), as a blue crystalline solid. Cell parameters at -160 degrees C: a = 17.389(6) A, b = 10.843(3) A, c = 10.463(3) A, beta = 125.28(1) degrees, Z = 2 in space group C2. The molecular structure involves an Mo2 unit inside an O6N2 distorted cubic box. The Mo2 axis is disordered about three positions with occupancy factors of ca. 45%, 45%, and 10%. Despite this disorder, the molecular structure is shown to contain a central Mo identical to Mo unit of distance 2.15(3) A coordinated to two triolate ligands which each have two chelating arms and one that spans the Mo identical to Mo bond. The local Mo2O6N2 moiety has approximate C2h symmetry, and the Mo-N distances are long, 2.4 A. The 1H and 13C(1H) NMR spectra recorded in benzene-d6 are consistent with the geometry found in the solid-state structure. The blue color arises from weak absorptions, epsilon approximately 150 dm3 mol-1 cm-1, at 580 and 450 nm in the visible region of the electronic absorption spectrum. Raman spectra recorded in KCl reveal pronounced resonance effects with excitation wavelengths of 488.0, 514.5, and 568.2 nm, particularly for the 322 cm-1 band, which can probably be assigned to nu(Mo identical to Mo). The electronic structure of this compound is investigated by B3LYP DFT calculations, and a comparison is made with the more typical ethane-like (D3d) Mo2(OR)6 compounds is presented. The distortion imposed on the molecule by the triisopropanolaminate(3-) ligands removes the degeneracy of the M-M pi molecular orbitals. The HOMO and SHOMO are both M-M pi and M-O sigma* in character, while the LUMO is M-M pi* and the SLUMO is predominantly M-O sigma* with metal sp character. The calculated singlet-singlet transition energies are compared with those implicit in the observed electronic spectrum.

Single-molecule magnets: a new class of tetranuclear manganese magnets

The preparation, X-ray structure, and detailed physical characterization are presented for a new type of single-molecule magnet [Mn4(O2CMe)2(pdmH)6](ClO4)2 (1). Complex 1.2MeCN.Et2O crystallizes in the triclinic space group P1, with cell dimensions at 130 K of a = 11.914(3) A, b = 15.347(4) A, c = 9.660(3) A, alpha = 104.58(1) degree, beta = 93.42(1) degree, gamma = 106.06(1) degree, and Z = 1. The cation lies on an inversion center and consists of a planar Mn4 rhombus that is mixed-valent, MnIII2MnII2. The pdmH- ligands (pdmH2 is pyridine-2,6-dimethanol) function as either bidentate or tridentate ligands. The bridging between Mn atoms is established by either a deprotonated oxygen atom of a pdmH- ligand or an acetate ligand. The solvated complex readily loses all acetonitrile and ether solvate molecules to give complex 1, which with time becomes hydrated to give 1.2.5H2O. Direct current and alternating current magnetic susceptibility data are given for 1 and 1.2.5H2O and indicate that the desolvated complex has a S = 8 ground state, whereas the hydrated 1.2.5H2O has a S = 9 ground state. Ferromagnetic interactions between MnIII-MnII and MnIII-MnIII pairs result in parallel spin alignments of the S = 5/2 MnII and S = 2 MnIII ions. High-frequency EPR spectra were run for complex 1.2.5H2O at frequencies of 218, 328, and 436 GHz in the 4.5-30 K range. A magnetic-field-oriented polycrystallite sample was employed. Fine structure is clearly seen in this parallel-field EPR spectrum. The transition fields were least-squares-fit to give g = 1.99, D = -0.451 K, and B4 degrees = 2.94 x 10(-5) K for the S = 9 ground state of 1.2.5H2O. A molecule with a large-spin ground state with D < 0 can function as a single-molecule magnet, as detected by techniques such as ac magnetic susceptibility. Out-of-phase ac signals (chi'' M) were seen for complexes 1 and 1.2.5H2O to show that these complexes are single-molecule magnets. A sample of 1 was studied by ac susceptibility in the 0.4-6.4 K range with the ac field oscillating at frequencies in the 1.1-1000 Hz range. A single peak in chi'' M vs temperature plots was seen for each frequency; the temperature of the chi'' M peak varies from 2.03 K at 995 Hz to 1.16 K at 1.1 Hz. Magnetization relaxation rates were evaluated in this way. An Arrhenius plot gave an activation energy of 17.3 K, which, as expected, is less than the 22.4 K value calculated for the thermodynamic barrier for magnetization direction reversal for an S = 8 complex with D = -0.35 K. The 1.2.5H2O complex with an S = 9 ground state has its chi'' M peaks at higher temperatures.

Structural distortions in mer-M(H)3(NO)L2 (M = Ru, Os) and their influence on intramolecular fluxionality and quantum exchange coupling

Molecules of the type mer-M(H)3(NO)L2 [M = Ru (1), Os (2); L = PR3] are characterized on the basis of 1H NMR T1min values and IR spectra as pseudo-octahedral trihydrides significantly distorted by compression of the cis H-M-H angles to approximately 75 degrees. The distortion, uncharacteristic of six-coordinate d6 complexes, is rationalized with DFT (B3LYP) calculations as being driven by increased H-to-M sigma donation and by the exceptional pi-accepting ability of linear NO+. In both 1 and 2, hydrides undergo intramolecular site exchange with delta HHH++(1) = 10-11 kcal/mol and delta HHH++(2) = 16-20 kcal/mol, depending on L, whereas for mer-Ru(H)3(NO)(PtBu2Me)2 (1b), moderate exchange couplings (up to 77 Hz) are featured in the low-temperature 1H NMR spectra, in addition to chemical exchange. On the basis of experimental and theoretical results, a dihydrogen intermediate is suggested to mediate hydride site exchange in 1. The cis H-M-H distortion shortens the tunneling path for the exchanging hydrides in 1, thereby increasing the tunneling rate; diminishes the "conflict" between trans hydrides in the mer geometry; and decreases the nucleophilicity of the hydrides. The generality of the observed structural distortion and its dependence on the ligand environment in late transition metal tri- and dihydrides are discussed. A less reducing metal center is generally characterized by greater distortion.

Tetranuclear manganese carboxylate complexes with a trigonal pyramidal metal topology via controlled potential electrolysis

Controlled potential electrolysis (CPE) procedures are described that provide access to complexes with a [Mn4(mu 3-O)3(mu 3-O2CR)]6+ core (3MnIII,MnIV) and a trigonal pyramidal metal topology, starting from species containing the [Mn4(mu 3-O)2]8+ core (4MnIII). [Mn4O2(O2CMe)6(py)2(dbm)2] (6): triclinic, P1, a = 10.868(3) A, b = 13.864(3) A, c = 10.625(3) A, alpha = 108.62(1) degrees, beta = 118.98(1) degrees, gamma = 89.34(2) degrees, V = 1307 A3, Z = 1, T = -131 degrees C, R (Rw) = 3.24 (3.70)%. [Mn4O2(O2CPh)6(py)(dbm)2] (8): monoclinic, P2(1)/c, a = 14.743(6) A, b = 15.536(8) A, c = 30.006(13) A, beta = 102.79(1) degrees, V = 6702 A3, Z = 4, T = -155 degrees C, R (Rw) = 4.32 (4.44)%. Both 6 and 8 contain a [Mn4O2]8+ core; 8 only has one py group, the fourth MnIII site being five-coordinate. (NBun4)[Mn4O2(O2CPh)7(dbm)2] (10) is available from two related procedures. CPE of 10 at 0.65 V vs ferocene in MeCN leads to precipitation of [Mn4O3(O2CPh)4(dbm)3] (11); similarly, CPE of 6 at 0.84 V in MeCN/CH2Cl2 (3:1 v/v) gives [Mn4O3(O2CMe)4(dbm)3] (12). Complex 11: monoclinic, P2(1)/n, a = 15.161(3) A, b = 21.577(4) A, c = 22.683(5) A, beta = 108.04(3) degrees, V = 7056 A3, Z = 4, T = -100 degrees C, R (wR2) = 8.63 (21.80)%. Complex 12: monoclinic, P2(1)/n, a = 13.549(2) A, b = 22.338(4) A, c = 16.618(2) A, beta = 103.74(1) degrees, V = 4885 A3, Z = 4, T = -171 degrees C, R (Rw) = 4.63 (4.45)%. Both 11 and 12 contain a [Mn4(mu 3-O)3(mu-O2CR)] core with a Mn4 trigonal pyramid (MnIV at the apex) and the RCO2- bridging the MnIII3 base. However, in 11, the carboxylate is eta 2,mu 3 with one O atom terminal to one MnIII and the other O atom bridging the other two MnIII ions, whereas in 12 the carboxylate is eta 1,mu 3, a single O atom bridging three MnIII ions. Variable-temperature, solid-state magnetic susceptibility studies on 11 and 12 show that, for both complexes, there are antiferromagnetic exchange interactions between MnIII/MnIV pairs, and ferromagnetic interactions between MnIII/MnIII pairs. In both cases, the resultant ground states of the complex is S = 9/2, confirmed by magnetization vs field studies in the 2.00-30.0 K and 0.50-50 kG temperature and field ranges, respectively.

Non-quassinoid constituents from the twigs and thorns of Castela polyandra

The structures of two new constituents, a beta-glycoside (1) and a steroid (2), isolated from the twigs and thorns of Castela polyandra, were established by a combination of spectroscopic and single-crystal X-ray analysis.

Quassinoids from the twigs and thorns of Castela polyandra

The structures of six new C20 quassinoids and one new C19 quassinoid, all isolated from the twigs and thorns of Castela polyandra, were established by a combination of spectroscopic and single-crystal X-ray analysis. Five known quassinoids and one known sterol were also identified.

Introduction to wavelet-based compression of medical images

Medical image compression can significantly enhance the performance of picture archiving and communication systems and may be considered an enabling technology for telemedicine. The wavelet transform is a powerful mathematical tool with many unique qualities that are useful for image compression and processing applications. Although wavelet concepts can be traced back to 1910, the mathematics of wavelets have only recently been formalized. By exploiting spatial and spectral information redundancy in images, wavelet-based methods offer significantly better results for compressing medical images than do compression algorithms based on Fourier methods, such as the discrete cosine transform used by the Joint Photographic Experts Group. Furthermore, wavelet-based compression does not suffer from blocking artifacts, and the restored image quality is generally superior at higher compression rates.

Conformational effects on retinoid receptor selectivity. 1. Effect of 9-double bond geometry on retinoid X receptor activity

A major challenge is the development of retinoids with selective biological activities. Recently, studies on retinoid response mechanisms indicate that retinoids activate two classes of nuclear receptor proteins, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). Here, we analyze the activity of a series of (E)- and (Z)-stilbenecarboxylic acids for gene transcriptional activation of the RARs and RXR-alpha to determine the optimum pharmacophore for receptor activation. The data obtained indicate that RAR and RXR response pathways can be separated by using the appropriate ligand. The conformations of (Z)-4-[2-(5-,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)prop en-1-yl]benzoic acid (Z)-4-[1-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2- naphthalenyl)propen-2-yl]benzoic acid were examined by experimental and theoretical methods to establish the appropriate conformation of the latter that specifically activated the retinoid RXR. A palladium(0)-catalyzed aryl bromide-arylboronic acid coupling under nonanhydrous conditions was used to construct a biaryl bond in the conformationally restricted retinoid 2'- (5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthaleny)biphenyl-4-c arboxylic acid, which had RXR activity.

Crystal Structure of a Silyl Cation with No Coordination to Anion and Distant Coordination to Solvent

The crystal structure of a stable silyl cation, triethylsilylium, in the form of its tetrakis (pentafluorophenyl)borate salt [Et(3)Si(+) (C(6)F(5))(4)B(-)] (Et, ethyl) shows no coordination between cation and anion. The closest silicon-fluorine distance is greater than 4 angstroms. A toluene solvent molecule is close enough to cause some deviations from planarity at the silicon, but the silicon-toluene distance is well beyond the sum of the silicon and carbon covalent radii. The toluene molecule is essentially planar and undistorted, as expected if little or no positive charge has been transferred from silicon to toluene.

The molecular structure of indium oxine

The radiopharmaceutical use of [111In]oxine for radiolabeling of blood products has recently met with FDA approval. The molecular structure of tris(8-quinolinolato) indium(III), "indium oxine", was determined by x-ray crystallography using a single yellow crystal grown from ethanol solution. The structural study reveals an asymmetric pseudo-octahedral N3O3 metal coordination sphere with meridional stereochemistry. This asymmetry is not detected in solution by proton NMR spectroscopy at room temperature; however, at -90 degrees C spectroscopic changes suggest slowing of a fluxional process. The molecule unexpectedly crystallized with a molecule of ethanol hydrogen-bonded to an oxygen atom of one of the oxine ligands, suggesting that hydrogen-bonding will play a role in the solvation of this complex in protic solvents.

Gallium-68 1,1,1-tris (5-methoxysalicylaldiminomethyl) ethane: a potential tracer for evaluation of regional myocardial blood flow

Reaction of tris(acetylacetonato)gallium(III) with 1,1,1-tris(5-methoxysalicladiminomethyl)ethane, H3[(5-MeOsal)3 TAME], affords a neutral six-coordinate complex, Ga[5-MeOsal)3 TAME], for which the x-ray crystal structure is reported. The 67Ga and 68Ga complexes of H3[(5-MeOsal)3 TAME] and the bis(salicylaldimine) of triethylenetetramine were prepared and characterized by paper chromatography and electrophoresis. The biodistribution of lipophilic 68Ga[(5-MeOsal)3 TAME] was determined following intravenous injection in rats. Myocardial images obtained by positron emission tomography from three dogs injected with 68Ga[(5-MeOsal)3 TAME] show a correlation between 68Ga uptake and regional myocardial blood flow. Single-pass coronary extraction studies in open-chest dogs indicate that 68Ga[(5-MeOsal)3 TAME] behaves neither as a freely diffusible tracer nor as a microsphere analog.