Some Studies on Crystal and Molecular Structure

The work which is described in this thesis is principally concerned with X-ray crystallography. Some other work, which Involved molecular orbital calculations, was also carried out and is described in Appendix I. Three compounds in all were studied by X-ray diffraction techniques, and the results of these investigations are summarised below. (1) Dimethylcertierocin: This compound, which has the formula CH3O.CO.(CH.CH)6.COOCH3, and which is the dimethyl ester of an acid isolated from a fungus, crystallises as yellow needles from chloroform. The crystals are triclinic, space goup C1 1 P 1 or C1 1 - P 1, and the unit cell dimensions are a = 9.06, b = 7.52, c = 6.07 A; alpha= 104.8, beta= 104.

LPMLE3 : a novel 1-D approach to study water flow in streambeds using heat as a tracer

We introduce LPMLE3, a new 1-D approach to quantify vertical water flow components at streambeds using temperature data collected in different depths. LPMLE3 solves the partial differential equation for coupled water flow and heat transport in the frequency domain. Unlike other 1-D approaches it does not assume a semi-infinite halfspace with the location of the lower boundary condition approaching infinity. Instead, it uses local upper and lower boundary conditions. As such, the streambed can be divided into finite subdomains bound at the top and bottom by a temperature-time series. Information from a third temperature sensor within each subdomain is then used for parameter estimation. LPMLE3 applies a low order local polynomial to separate periodic and transient parts (including the noise contributions) of a temperature-time series and calculates the frequency response of each subdomain to a known temperature input at the streambed top. A maximum-likelihood estimator is used to estimate the vertical component of water flow, thermal diffusivity, and their uncertainties for each streambed subdomain and provides information regarding model quality. We tested the method on synthetic temperature data generated with the numerical model STRIVE and demonstrate how the vertical flow component can be quantified for field data collected in a Belgian stream. We show that by using the results in additional analyses, nonvertical flow components could be identified and by making certain assumptions they could be quantified for each subdomain. LPMLE3 performed well on both simulated and field data and can be considered a valuable addition to the existing 1-D methods

Intrapulmonary Pharmacokinetics of First-line Anti-tuberculosis Drugs in Malawian Patients With Tuberculosis

BACKGROUND: Further work is required to understand the intrapulmonary pharmacokinetics of first-line anti-tuberculosis drugs. This study aimed to describe the plasma and intrapulmonary pharmacokinetics of rifampicin, isoniazid, pyrazinamide, and ethambutol, and explore relationships with clinical treatment outcomes in patients with pulmonary tuberculosis. METHODS: Malawian adults with a first presentation of microbiologically-confirmed pulmonary tuberculosis received standard 6-month first-line therapy. Plasma and intrapulmonary samples were collected 8 and 16 weeks into treatment and drug concentrations measured in plasma, lung/airway epithelial lining fluid, and alveolar cells. Population pharmacokinetic modelling generated estimates of drug exposure (Cmax and AUC) from individual-level post-hoc Bayesian estimates of plasma and intrapulmonary pharmacokinetics. RESULTS: One-hundred-and-fifty-seven patients (58% HIV co-infected) participated. Despite standard weight-based dosing, peak plasma concentrations of first-line drugs were below therapeutic drug monitoring targets. Rifampicin concentrations were low in all three compartments. Isoniazid, pyrazinamide, and ethambutol achieved higher concentrations in epithelial lining fluid and alveolar cells than plasma. Isoniazid and pyrazinamide concentrations were 14.6 (95% CI: 11.2-18.0) and 49.8-fold (95% CI: 34.2-65.3) higher in lining fluid than plasma respectively. Ethambutol concentrations were highest in alveolar cells (alveolar cells:plasma ratio 15.0, 95% CI 11.4-18.6). Plasma or intrapulmonary pharmacokinetics did not predict clinical treatment response. CONCLUSIONS: We report differential drug concentrations between plasma and the lung. While plasma concentrations were below therapeutic monitoring targets, accumulation of drugs at the site of disease may explain the success of the first-line regimen. The low rifampicin concentrations observed in all compartments lend strong support for ongoing clinical trials of high-dose rifampicin regimens

High intrapulmonary rifampicin and isoniazid concentrations are associated with rapid sputum bacillary clearance in patients with pulmonary tuberculosis

This work was supported by a Wellcome Trust Clinical PhD Fellowship [grant number 105392/B/14/Z to A.D.M. and L69AGB to JM]. ELC was supported by Wellcome [200901/Z/16/Z]. The Malawi-Liverpool-Wellcome Clinical Research Programme is supported by a strategic award from the Wellcome Trust [206545/Z/17/Z]. We also acknowledge infrastructural support for bioanalysis from the Liverpool Biomedical Research Centre funded by Liverpool Health Partners.Background Intrapulmonary pharmacokinetics may better explain response to tuberculosis (TB) treatment than plasma pharmacokinetics. We explored these relationships by modelling bacillary clearance in sputum in adult patients on first-line treatment in Malawi. Methods Bacillary elimination rates (BER) were estimated using linear mixed-effects modelling of serial time-to-positivity in mycobacterial growth indicator tubes for sputum collected during the intensive phase of treatment (weeks 0 to 8) for microbiologically confirmed TB. Population pharmacokinetic models used plasma and intrapulmonary drug levels at 8 and 16 weeks. Pharmacokinetic-pharmacodynamic relationships were investigated using individual-level measures of drug exposure (AUC and Cmax) for rifampicin, isoniazid, pyrazinamide, and ethambutol, in plasma, epithelial lining fluid, and alveolar cells as covariates in the bacillary elimination models. Results Among 157 participants (58% HIV co-infected), drug exposure in plasma or alveolar cells was not associated with sputum bacillary clearance. Higher peak concentrations (Cmax) or exposure (AUC) to rifampicin or isoniazid in epithelial lining fluid was associated with more rapid bacillary elimination and shorter time to sputum negativity. More extensive disease on baseline chest radiograph was associated with slower bacillary elimination. Clinical outcome was captured in 133 participants, with 15 (11%) unfavourable outcomes recorded (recurrent TB, failed treatment, or death). No relationship between BER and late clinical outcome was identified. Conclusions Greater intrapulmonary drug exposure to rifampicin or isoniazid in the epithelial lining fluid was associated with more rapid bacillary clearance. Higher doses of rifampicin and isoniazid may result in sustained high intrapulmonary drug exposure, rapid bacillary clearance, shorter treatment duration and better treatment outcomes.Publisher PDFPeer reviewe

The Arabidopsis B3 domain protein VERNALIZATION1 is involved in processes essential for development with structural and mutational studies revealing its DNA binding surface

The B3 DNA-binding domain is a plant-specific domain found throughout the plant kingdom from the alga Chlamydomonas to grasses and flowering plants. Over 100 B3 domain-containing proteins are found in the model plant Arabidopsis thaliana, and one of these is critical for accelerating flowering in response to prolonged cold treatment, an epigenetic process called vernalization. Despite the specific phenotype of genetic vrn1 mutants, the VERNALIZATION1 (VRN1) protein localizes throughout the nucleus and shows sequence-nonspecific binding in vitro. In this work, we used a dominant repressor tag that overcomes genetic redundancy to show that VRN1 is involved in processes beyond vernalization that are essential for Arabidopsis development. To understand its sequence-nonspecific binding, we crystallized VRN1(208-341) and solved its crystal structure to 1.6 angstrom resolution using selenium/single-wavelength anomalous diffraction methods. The crystallized construct comprises the second VRN1 B3 domain and a preceding region conserved among VRN1 orthologs but absent in other B3 domains. We established the DNA-binding face using NMR and then mutated positively charged residues on this surface with a series of 16 Ala and Glu substitutions, ensuring that the protein fold was not disturbed using heteronuclear single quantum correlation NMR spectra. The triple mutant R249E/R289E/R296E was almost completely incapable of DNA binding in vitro. Thus, we have revealed that although VRN1 is sequence-nonspecific in DNA binding, it has a defined DNA-binding surface

Laparoscopic versus open colorectal surgery in the acute setting (LaCeS trial): a multicentre randomized feasibility trial

AbstractBackgroundApproximately 30,000 people per annum undergo major, emergency abdominal, gastrointestinal surgery, of which 36% (~10,800) are carried out for emergency colorectal pathology. Approximately 14% of all patients requiring emergency surgery undergo laparoscopic surgery. AimsThe aims of the LaCeS feasibility trial (Laparoscopic versus Open Colorectal Surgery in the Acute Setting) were to assess the feasibility, safety and acceptability of performing a large-scale definitive phase III randomised controlled trial with a comparison of emergency laparoscopic with open surgery for acute colorectal pathology. MethodsLaCeS was designed as a prospective, multicentre, single blind, parallel group, pragmatic, randomised controlled feasibility trial with an integrated qualitative study. Randomisation was performed centrally with patients being randomised on a 1:1 basis between laparoscopic or open surgery. ResultsA total of 64 patients were recruited across 5 centres. The overall average steady state recruitment rate was 1.2 patients/month. Baseline compliance for clinical and HrQoL data was 99.8% and 93.8% respectively. The conversion rate from laparoscopic to open surgery was 39.4% (95% CI 22.9% – 57.9%). The 30 day post-operative complication rate was 27.3% (95% CI 13.3- 45.5) in the laparoscopic arm and 41.9% (95% CI 24.6 – 60.9) in the open arm. DiscussionThe LaCeS feasibility trial has demonstrated that it is possible to evaluate laparoscopic surgery in the emergency colorectal setting within the context of a randomised controlled trial. LaCeS has demonstrated that it is possible to recruit to a surgical trial in the emergency setting, with good compliance to trial procedures and processes, and overall acceptability by patients and clinicians. The safety data obtained for laparoscopic emergency colorectal surgery indicate an acceptable safety profile, particularly when considering it to that observed in the open arm.Trial Registration ISRCTN15681041 https://doi.org/10.1186/ISRCTN15681041.Funding body: National Institute of Health Research – Research for Patient Benefi

Trade blocs and trade wars during the interwar period

What precisely were the causes and consequences of the trade wars in the 1930s? Were there perhaps deeper forces at work in reorienting global trade prior to the outbreak of World War II? And what lessons may this particular historical episode provide for the present day? To answer these questions, we distinguish between long‐run secular trends in the period from 1920 to 1939 related to the formation of trade blocs and short‐run disruptions associated with the trade wars of the 1930s. We argue that the trade wars mainly served to intensify pre‐existing efforts toward the formation of trade blocs which dated from at least 1920. More speculatively, we argue that the trade wars of the present day may serve a similar purpose as those in the 1930s, that is, the intensification of China‐ and US‐centric trade blocs