Demonstration of flow and platelet dependency in a ferric chloride-induced model of thrombosis

Further to characterize the processes involved in the FeCl3-induced thrombosis model, we determined the effect of aspirin, heparin, hirudin, trans-4-(aminomethyl) cyclohexane carboxylic acid (AMCHA), thrombocytopenia, and flow modifications on time to occlusion (TTO) and thrombus weight (TW) in the rat carotid artery. Aspirin, from 3 to 100 mg/kg, showed no dose-response relation for either TTO or TW and did not significantly affect ex vivo platelet aggregation. Heparin, at doses that significantly increased the activated partial thromboplastin time (APTT), dose-dependently increased the TTO of animals that showed an occlusion during the monitoring period and also reduced the TW. Hirudin required constant infusion to prevent occlusion and reduce the TW, when the APTT was also significantly increased. AMCHA did not affect the TW but reduced the TTO. Animals made thrombocytopenic by the use of antiplatelet serum did not occlude during the monitoring period, and the TW was significantly reduced. Changes in flow showed that the TTO was not affected, but the TW showed an inverse correlation with average flow. The results obtained for platelet depletion and flow modifications expand on previous findings with this model and support the physiological relevance of the model.

Improvement in screening for sexually transmitted infections in HIV-positive patients following implementation of a nurse-led clinic

The objective of this study was to assess changes in the uptake of sexually transmitted infection (STI) screening resulting from implementation of a specific STI clinic for HIV-positive patients. An audit of STI screening in HIV-positive patients was undertaken before and after the establishment of the clinic. Significant increases in the number of patients having a sexual health discussion and annual health screen were seen. High rates of positive results were found in all patient groups. National guidelines recommend regular STI screening for all HIV-positive patients. A specific clinic for HIV-positive patients is feasible and acceptable and may result in an increase in uptake of STI screening.

Hybrid Organic-Inorganic Rotaxanes, Including a Hetero-Hybrid [3]Rotaxane Featuring Two Distinct Heterometallic Rings and a Molecular Shuttle

[2] and [3] hybrid rotaxanes are reported based on {Ti₇ M} rings (M is a trivalent metal such as Fe^III or Ga^III ). NMR studies show that [2]rotaxanes can act as molecular shuttles, while EPR studies of [3]rotaxanes show weak interactions between the paramagnetic components of the supramolecular assemblies.

Conformational Flexibility of Hybrid [3]- and [4]-Rotaxanes

The synthesis, structures, and properties of [4]- and [3]-rotaxane complexes are reported where [2]-rotaxanes, formed from heterometallic {Cr₇Ni} rings, are bound to a fluoride-centered {CrNi₂} triangle. The compounds have been characterized by single-crystal X-ray diffraction and have the formulas [CrNi₂(F)(O₂C^tBu)₆]{(BH)[Cr₇NiF₈(O₂C^tBu)₁₆]}₃ (3) and [CrNi₂(F)(O₂C^tBu)₆(THF)]{(BH)[Cr₇NiF₈(O₂C^tBu)₁₆]}₂ (4), where B = py-CH₂CH₂NHCH₂C₆H₄SCH₃. The [4]-rotaxane 3 is an isosceles triangle of three [2]-rotaxanes bound to the central triangle while the [3]-rotaxane 4 contains only two [2]-rotaxanes bound to the central triangle. Studies of the behavior of 3 and 4 in solution by small-angle X-ray scattering and atomistic molecular dynamic simulations show that the structure of 3 is similar to that found in the crystal but that 4 has a different conformation to the crystal. Continuous wave and pulsed electron paramagnetic resonance spectroscopy was used to study the structures present and demonstrate that in frozen solutions (at 5 K) 4 forms more extended molecules than 3 and with a wider range of conformations.

Targeting molecular quantum memory with embedded error correction

The implementation of a quantum computer requires both to protect information from environmental noise and to implement quantum operations efficiently. Achieving this by a fully fault-tolerant platform, in which quantum gates are implemented within quantum-error corrected units, poses stringent requirements on the coherence and control of such hardware. A more feasible architecture could consist of connected memories, that support error-correction by enhancing coherence, and processing units, that ensure fast manipulations. We present here a supramolecular {Cr7Ni}-Cu system which could form the elementary unit of this platform, where the electronic spin 1/2 of {Cr7Ni} provides the processor and the naturally isolated nuclear spin 3/2 of the Cu ion is used to encode a logical unit with embedded quantum error-correction. We demonstrate by realistic simulations that microwave pulses allow us to rapidly implement gates on the processor and to swap information between the processor and the quantum memory. By combining the storage into the Cu nuclear spin with quantum error correction, information can be protected for times much longer than the processor coherence.

No virus replication in domestic cats fed with RHDV-infected rabbit livers

Previous studies have shown that feral cats (Felis catus) from rabbit haemorrhagic disease (RHD) epidemic areas in New Zealand had antibodies against RHD Virus (RHDV) and RHDV RNA was identified by nested RT-PCR from one seropositive feral cat liver. To assess whether RHDV replicates and produces clinical consequences in cats following the consumption of RHDV-infected rabbit, a challenge trial was conducted by feeding cats RHDV-infected rabbit livers. Antibodies against RHDV were detected by immunoassay from sera of cats collected 10 days after the consumption of RHDV-infected livers. Animals fed four times with RHDV-infected livers, had higher antibody titres than animals fed only once. RHDV RNA was detected by nested RT-PCR from mesenteric lymph nodes, tonsil, spleen and liver of cats fed with RHDV-infected livers. RHDV anti-genomic RNA was also detected by nested RT-PCR from mesenteric lymph nodes collected from one animal 2 days after the fourth feed. RHDV was detected by antigen ELISA from cat faeces 1-2 days after the consumption of RHDV-infected livers. Even though a large amount of RHDV has been used, cats did not show any signs of disease. Although abortive RHDV replication could not be ruled out, active RHDV replication was not demonstrated.

Structural Characterization of Lithium and Sodium Bulky Bis(silyl)amide Complexes

Alkali metal amides are vital reagents in synthetic chemistry and the bis(silyl)amide {N(SiMe₃)₂} (N′′) is one of the most widely-utilized examples. Given that N′′ has provided landmark complexes, we have investigated synthetic routes to lithium and sodium bis(silyl)amides with increased steric bulk to analyse the effects of R-group substitution on structural features. To perform this study, the bulky bis(silyl)amines {HN(Si^tBuMe₂)(SiMe₃)}, {HN(SiⁱPr₃)(SiMe₃)}, {HN(Si^tBuMe₂)₂}, {HN(SiⁱPr₃)(Si^tBuMe₂)} and {HN(SiⁱPr₃)₂} (1) were prepared by literature procedures as colourless oils; on one occasion crystals of 1 were obtained. These were treated separately with ⁿBuLi to afford the respective lithium bis(silyl)amides [Li{μ-N(Si^tBuMe₂)(SiMe₃)}]₂ (2), [Li{μ-N(SiⁱPr₃)(SiMe₃)}]₂ (3), [Li{N(Si^tBuMe₂)₂}{μ-N(Si^tBuMe₂)₂}Li(THF)] (4), [Li{N(SiⁱPr₃)(Si^tBuMe₂)}(DME)] (6) and [Li{N(SiⁱPr₃)₂}(THF)] (7) following workup and recrystallization. On one occasion during the synthesis of 4 several crystals of the ‘ate’ complex [Li₂{μ-N(Si^tBuMe₂)₂}(μ-ⁿBu)]₂ (5) formed and a trace amount of [Li{N(SiⁱPr₃)₂}(THF)₂] (8) was identified during the recrystallization of 7. The reaction of {HN(Si^tBuMe₂)₂} with NaH in the presence of 2 mol % of NaO^tBu gave crystals of [Na{μ-N(Si^tBuMe₂)₂}(THF)]₂ (9-THF), whilst [Na{N(SiⁱPr₃)₂}(C₇H₈)] (10) was prepared by deprotonation of 1 with ⁿBuNa. The solid-state structures of 1⁻10 were determined by single crystal X-ray crystallography, whilst 2⁻4, 7, 9 and 10 were additionally characterized by NMR and FTIR spectroscopy and elemental microanalysis.

Decorating polymer beads with 1014 inorganic-organic [2]rotaxanes as shown by spin counting

Polymer beads have been used as the core of magnetic particles for around twenty years. Here we report studies to attach polymetallic complexes to polymer beads for the first time, producing beads of around 115 microns diameter that are attached to 10¹⁴ hybrid inorganic-organic [2]rotaxanes. The bead is then formally a [10¹⁴] rotaxane. The number of complexes attached is counted by EPR spectroscopy after including TEMPO radicals within the thread of the hybrid [2]rotaxanes.

Synthesis and cytotoxic activity of thiazolyl indolequinones

A number of thiazolyl indolequinones have been prepared and evaluated for their antitumor properties. The compounds were synthesized from the appropriate indole, building up the thiazole ring using the Hantzsch reaction. Cytotoxic activity was determined in the human breast cancer SKBr3 cell line. Selected compounds were also studied in human lung carcinoma A549 and PV9 cell lines. In addition, some compounds were evaluated for their possible bioreductive action by determining their cytotoxicity towards V79 Chinese hamster lung fibroblasts in air and under anaerobic (hypoxic) conditions.

Gold(i) bridged dimeric and trimeric heterometallic {Cr7Ni}-based qubit systems and their characterization

Gold(i) bridged dimeric and trimeric structures of a ground state spin S = 1/2 heterometallic {Cr₇Ni} wheel have been prepared and studied by continuous wave (CW) and pulsed wave EPR spectrometry. The {Cr₇Ni} relaxation time constants (T₁ and T_m) show rates matching well with previous observations. Four pulse Double Electron Resonance (DEER) studies suggest presence of more than one conformations. Small Angle X-ray Scattering (SAXS) in conjunction with Molecular Dynamic (MD) Simulations were performed to look at the possible conformations in solution. In line with DEER results, simulation data further indicated more flexible molecular geometry in solution than the one in solid state.

Control and Transferability of Magnetic Interactions in Supramolecular Structures: Trimers of {Cr7 Ni} Antiferromagnetic Rings

A synthetic strategy is demonstrated to prepare two distinct trimers of antiferromagnetically coupled {Cr7 Ni} rings, substantially varying the magnetic interactions between the spin centres. The interactions were studied using multi-frequency cw EPR: in a trimer linked via non-covalent H-bonding interactions no measurable interaction between rings was seen, while in a trimer linked via iso-nicotinate groups isotropic and anisotropic exchange interactions of +0.42 and -0.8 GHz, respectively, were observed. The latter are the same as those for a simpler hetero-dimer system, showing how the spin-spin interactions can be built in a predictable and modular manner in these systems.

Two- and Three-Spin Hybrid Inorganic-Organic [2]Rotaxanes Containing Metallated Salen Groups

Mono- and bis-salen functionalised [2]rotaxanes have been synthesised from the esterification of [2]rotaxanes containing phenol-terminated threads (salen=N,N'-bis(salicylidene)ethylenediamine). The [2]rotaxanes have general formula [RH][Cr7NiF8(O2CtBu)16], where [RH]+ is a thread with a central secondary ammonium site that templates a [Cr7NiF8(O2CtBu)16]- ring. The threads are terminated at one or both ends by carboxylic acid functionalised salen groups. The {M(salen)} groups can be free-base [M=(H+)2] or metallated [M=Cu2+, Ni2+, (VO)2+]. The [2]rotaxanes have been characterised by single crystal XRD and solid- and solution-state EPR spectroscopy. Where two paramagnetic M ions are involved [M=Cu2+ and/or (VO)2+] the [2]rotaxanes contain three electron spin S=1 / 2 ${{ 1/2 }}$ centres, since the {Cr7Ni} ring has an S=1 / 2 ${{ 1/2 }}$ ground state which is well isolated at low temperatures. These three-spin [2]rotaxanes have been characterised in solution by pulsed dipolar EPR spectroscopies (DEER, also known as PELDOR, and RIDME). The M⋅⋅⋅M and M⋅⋅⋅{Cr7Ni} interactions measured are consistent with dipolar interactions and also with the distances from single crystal XRD. The authors declare no competing financial interest.

Templating metallocycles with a macrocycle: synthesis, structures and magnetic studies of {Cr11M2} complexes

Addition of 1,4,8,11-tetrazacyclotetradecane (cyclam) to a reaction that produces octametallic rings when simpler amines are used, produces {Cr₁₁M₂} "pretzels" (M = Zn^II or Cu^II) where the cyclam coordinates to the M^II ion which then sits at the centre of a twelve-metal macrocycle. Magnetic studies were fitted using the finite-temperature Lanczos method (FTLM), and the results demonstrate that exchange interactions are transferable from previous exchange-coupled Cr^III rings.

A ring of rotaxanes: studies of a large paramagnetic assembly in solution

Here we report the synthesis and structural characterization of four [7]rotaxanes formed by coordinating hybrid inorganic-organic [2]rotaxanes to a central {Ni12} core. X-ray single crystal diffraction demonstrate that [7]rotaxanes are formed, with a range of conformations in the crystal. Small angle X-ray scattering supported by molecular dynamic simulations demonstrates that the large molecules are stable in solution and also show that the conformers present in solution are not those found in the crystal. Pulsed EPR spectroscopy show that phase memory times for the {Cr7Ni} rings, which have been proposed as qubits, are reduced but not dramatically by the presence of the {Ni12} cage.

One-, two- and three-dimensional interlocked polymers based on hybrid inorganic-organic rotaxanes

We report three new polymers, based on mechanically interlocked inorganic-organic rotaxanes. They are made in very mild conditions and involve pyrimidine head groups binding to copper(ii) linking units. A two-dimensional 6,3 net and a three-dimensional 10,3b net are found depending on the solvent used in the reaction.

Weak Exchange Interactions in Multispin Systems: EPR Studies of Metalloporphyrins Decorated with {Cr7Ni} Rings

Both metalloporphyrins and heterometallic {Cr7Ni} rings are of significant research interest due to their proposed roles in quantum information processing devices. In this study, we present a series of complexes in which [Cr7NiF3(Etglu)(O2CtBu)15] (N-EtgluH5 = N-ethyl-d-glucamine) heterometallic rings are coordinated to metalloporphyrin linkers: the symmetric [M(TPyP)] for M = Cu2+, VO2+, and H2TPyP = 5,10,15,20-tetra(4-pyridyl)porphyrin; and the asymmetric [{VO}(TrPPyP)] for H2(TrPPyP) = 5,10,15-(triphenyl)-20-(4-pyridyl)porphyrin. The magnetic interactions present in these complexes are unraveled using the continuous wave (CW) electron paramagnetic resonance (EPR) technique. The nature of the coupling between the {Cr7Ni} rings and the central metalloporphyrin is assessed by numerical simulations of CW EPR spectra and determined to be on the order of 0.01 cm-1, larger than the dipolar ones and suitable for individual spin addressability in multiqubit architectures.

Structural characterisation and dynamics of a paramagnetic {Cr12Ni3} seahorse in non-crystalline phases

The complex [{Ni(cyclen)}2Cr12NiF18(O2CtBu)24] (where cyclen = 1,4,7,10-tetrazacyclododecane) crystallises as a fifteen-metal chain that is shaped like a seahorse. Given this is one of the longest finite, paramagnetic chains found, we were intrigued whether this unusual structure is induced during crystal growth or also maintained in other phases. We report electron paramagnetic resonance spectroscopy, small angle X-ray scattering and atomistic molecular dynamics simulations, demonstrating that the S-structure from crystal is stable in powder and solution. Using ion mobility mass spectrometry (IM-MS), we revealed the coexistence of S-shaped structures and a closed isomeric assembly in the gas phase. Collision-induced dissociation mass spectrometry studies monitored by IM-MS show the rearrangement of the cyclic seahorse to the S-shaped conformation, as well as the dissociation to a cyclic, seven-metal complex.

Synthesis and characterization of heterometallic rings templated through alkylammonium or imidazolium cations

We report the synthesis and structural characterization of a series of heterometallic rings templated via alkylammonium or imidazolium cations. The template and preference of each metal's coordination geometry can control the structure of heterometallic compounds, leading to octa-, nona-, deca-, dodeca-, and tetradeca-metallic rings. The compounds were characterized by single-crystal X-ray diffraction, elemental analysis, magnetometry, and EPR measurements. Magnetic measurements show that the exchange coupling between metal centres is antiferromagnetic. EPR spectroscopy shows that the spectra of {Cr7Zn} and {Cr9Zn} have S = 3/2 ground states, while the spectra of {Cr12Zn2} and {Cr8Zn} are consistent with S = 1 and 2 excited states. The EPR spectra of {(ImidH)-Cr6Zn2}, {(1-MeImH)-Cr8Zn2}, and {(1,2-diMeImH)-Cr8Zn2} include a combination of linkage isomers. The results on these related compounds allow us to examine the transferability of magnetic parameters between compounds.

Correction: Synthesis and characterization of heterometallic rings templated through alkylammonium or imidazolium cations

Correction for 'Synthesis and characterization of heterometallic rings templated through alkylammonium or imidazolium cations' by Rajeh Alotaibi et al., Dalton Trans., 2023, 52, 7473-7481, https://doi.org/10.1039/D3DT00982C.

OPC-28326, a selective femoral vasodilator, is an alpha2C-adrenoceptor-selective antagonist

OPC-28326 has been reported to selectively increase femoral blood flow in open-chest dogs and autoperfused canine femoral artery preparations. Preliminary data indicated that OPC-28326 has a high affinity at the alpha2-adrenoceptor. In the present study, we tested OPC-28326 in isoflurane anesthetized rats at a dose of 3 mg/kg of body weight, given intraduodenally. OPC-28326 significantly increased femoral blood flow, by 44.7 +/- 13.8%, 45 min after drug administration, whereas carotid blood flow increased by only 3.6 +/- 5.5% (n = 6). Chinese hamster ovary cell lines overexpressing rat alpha2D-, alpha2B-, or alpha2C-adrenoceptor were established. These cells also coexpress luciferase, driven by cAMP elevation. In radioligand binding assays using cell membrane preparations, OPC-28326 dose dependently competed with [3H]RX821002 binding, with calculated K(i) values of 3840 +/- 887, 633 +/- 46, and 13.7 +/- 1.9 nM on alpha2D-, alpha2B-, and alpha2C-adrenoceptor, respectively. A similar affinity and rank order of potency were also found for OPC-28326 on the alpha2-subtypes using epinephrine as agonist in luciferase assays. No agonistic effect of OPC-28326 was detected on any of the alpha2-adrenoceptors. Finally, in situ hybridization performed on skeletal muscle tissue sections collected from rat hind limb (musculus gastrocnemius) demonstrated a high level expression of alpha2C in the vascular tissues. Thus, the abundance of alpha2C in the skeletal muscle may account for the selective effect of OPC-28326 in increasing femoral blood flow.

The Synthesis and Characterisation of a Molecular Sea-Serpent: Studies of a {Cr24 Cu7 } Chain

A finite chain of thirty-one paramagnetic centers is reported, synthesized by reaction of hydrated chromium fluoride, copper carbonate and pivalic acid in the presence of 1,4,7,10-tetrazacyclododecane (cyclen). Magnetic studies show predominantly anti-ferromagnetic exchange leading to a high density of low-lying spin states and large saturation field.

Characterizing X-Ray and Solution State Conformations for a Model Qubit System: {Cr7Ni} Ring Rotaxanes on a Mixed Metal Triangle

The synthesis of a series of [4]rotaxanes, each consisting of three [2]rotaxanes joined via a central {CrNi2} triangular linker, is reported. The resultant four [4]rotaxanes were characterized by single crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy. Orientation-selective 4-pulse double electron-electron resonance (DEER) measurements between the three {Cr7Ni} rings incorporated in each [4]rotaxane reveal that each system is conformationally fluxional in solution, with the most abundant conformations found to differ significantly from the crystal structure geometry for each compound. The degree of similarity between conformations is evaluated using a novel application of the earth mover's distance analysis.