Characterisation and determination of indole alkaloids in frog-skin secretions by electrospray ionisation ion trap mass spectrometry

The characterisation of selected indole alkaloids in a quadrupole ion trap mass spectrometer is presented. Fragmentation profiles for tryptamine, 5-hydroxytryptamine (5-HT), N'-methyl 5-hydroxytryptamine (N'-methyl 5-HT), N',N'-dimethyl 5-hydroxytryptamine (bufotenine), N',N',N'-trimethyl 5-hydroxytryptamine (5-HTQ), and N',N'-dimethyl 5-methoxytryptamine (5-MeODMT) are presented with proposed structures given for each product ion observed. Such MS(n) experiments can be used to differentiate the isobaric molecular ions of the compounds 5-HTQ (M(+)) and 5-MeODMT (MH(+)). The quantitative determination of certain indole alkaloids in the skin secretions of the Australian Golden Bell frog, Litoria aurea, by LC/ESI-ion trap MS is also presented. The concentrations of 5-HT, N'-methyl 5-HT and 5-HTQ were found to be 2.68, 0.26 and 0.54 microg per mg of skin secretion, respectively.     

The chemistry of 2'' ,3''-seconucleosides II. Reactions and biological properties of 2'',3''-secopyrimidine ribonucleosides

Reaction of 2',3'-secouridine with acetone gave the 3',5'-$\text{O}$-isopropylidene derivative (1) which upon treatment with mesylchloride gave the 2'-$\text{O}$-mesyl compound (2). Replacement of the mesyl group of 2 with halide could be effected by reaction with a metal halide in DMF. The 3',5'-$\text{O}$-isopropylidene group was removed simultaneously to give a 2'-halogeno-2'-deoxy-2',3'-secouridine. 2',3'-Dichloro-2',3'-dideoxy-2',3'-secouridine upon treatment with base gave 6($\text{R}$)-chloromethyl-2($\text{R}$)-(uracil-1-yl)-1,4-dioxane in addition to O²,2'-anhydro-3'-chloro-3'-deoxy-2',3'-secouridine, as previously reported. 2',3'-Dichloro-2',3'-dideoxy-5'-0-trityl-2',3'-secouridine was converted to 2',3'-dichloro-2',3'-dideoxy-2',3'-secocytidine (16) $\text{via}$ a triazole derivative. Compound 16 was unstable and appeared to form O²,2'-anhydro-3'-chloro-3'-deoxy-2,3'-secocytidine upon standing at room temperature. 5-Vinyl- and 5-($\text{E}$) (2-bromovinyl) uridine dialdehydes have been made, as well as a number of other 5-substituted 2',3'-secouridine derivatives. None of the compounds obtained showed significant activity against a number of virus strains or tumor cell lines, except for 5-($\text{E}$)(2-bromovinyl) uridine dialdehyde, which was inhibitory to the growth of human lymphoblast (Raji, Namalva) cells at a concentration of 28 μ/ml.     

Direct detection of ion pairs by fluorescence enhancement

Sensor 1 signals the simultaneous presence of sodium and phosphate with an increased fluorescence signal in the manner of a photoionic AND logic gate.     

Extending the Entropy Stability Measure for Manpower Planning

In manpower planning, it is essential to be able to monitor stability of the length-of-service structure of the staff. Such a stability index is provided by the formula for entropy of a continuous distribution, evaluated for length of service. This measure improves on the previous discrete version by removing the necessity of introducing arbitrary tenure classes, thus facilitating inter-company comparisons. It is closely related to the entropy formula used in demography, and manpower planners may therefore avail themselves of results already used by demographers.     

Application of electrospray mass spectrometry in the detection and determination of Remazol textile dyes.

The electrospray (ES) behaviour of selected Remazol textile dyes, their hydrolysis products and the latters' reaction, following elution from a strong anion-exchange cartridge, with 30% concentrated HCl in MeOH, is studied and applied to the direct analysis of dye containing effluent. For unambiguous identification and determination of these textile dyes in effluents, it is necessary to resort to ES utilising MS-MS and MS3. Further, a tabular review of recent applications of HPLC-ES-MS and, to a lesser extent, CE-ES-MS with reference to drug and pesticide analysis is presented.     

Using phase-type models to cost stroke patient care across health,social and community services

Stroke disease places a heavy burden on society, incurring long periods of time in hospital and community care, and associated costs. Also stroke is a highly complex disease with diverse outcomes and multiple strategies for therapy and care. Previously a modeling framework has been developed which clusters patients into classes with respect to their length of stay (LOS) in hospital. Phase-type models were then used to describe patient flows for each cluster. Also multiple outcomes, such as discharge to normal residence, nursing home, or death can be permitted. We here add costs to this model and obtain the Moment Generating Function for the total cost of a system consisting of multiple transient phase-type classes with multiple absorbing states. This system represents different classes of patients in different hospital and community services states. Based on stroke patients’ data from the Belfast City Hospital, various scenarios are explored with a focus on comparing the cost of thrombolysis treatment under different regimes. The overall modeling framework characterizes the behavior of stroke patient populations, with a focus on integrated system-wide costing and planning, encompassing hospital and community services. Within this general framework we have developed models which take account of patient heterogeneity and multiple care options. Such complex strategies depend crucially on developing a deep engagement with the health care professionals and underpinning the models with detailed patient-specific data.     

Where to treat the older patient? Can Markov models help us better understand the relationship between hospital and community care?

We have previously used Markov models to describe movements of patients between hospital states; these may be actual or virtual and described by a phase-type distribution. Here we extend this approach to a Markov reward model for a healthcare system with Poisson admissions and an absorbing state, typically death. The distribution of costs is evaluated for any time and expressions derived for the mean and variances of costs. The average cost at any time is then determined for two scenarios: the Therapeutic and Prosthetic models, respectively. This example is used to illustrate the idea that keeping acute patients longer in hospital to ensure fitness for discharge, may reduce costs by decreasing the number of patients that become long-stay. In addition we develop a Markov Reward Model for a healthcare system including states, where the patient is in hospital, and states, where the patient is in the community. In each case, the length of stay is described by a phase-type distribution, thus enabling the representation of durations and costs in each phase within a Markov framework. The model can be used to determine costs for the entire system thus facilitating a systems approach to the planning of healthcare and a holistic approach to costing. Such models help us to assess the complex relationship between hospital and community care.     

Actin localisation and the effect of cytochalasin D on the osmotic tolerance of cauda epididymidal kangaroo spermatozoa

This study examined the hypothesis that filamentous actin associated with the complex cytoskeleton of the kangaroo sperm head and tail may be contributing to lack of plasma membrane plasticity and a consequent loss of membrane integrity during cryopreservation. In the first study, the distribution of G and F actin within Eastern Grey Kangaroo (EGK, Macropus giganteus) cauda epididymidal spermatozoa was successfully detected using DNAse-FITC and a monoclonal F-actin antibody (ab205, Abcam), respectively. G-actin staining was most intense in the acrosome but was also observed with less intensity over the nucleus and mid-piece. F-actin was located in the sperm nucleus but was not discernable in the acrosome or sperm tail. To investigate whether cytochalasin D (a known F-actin depolymerising agent) was capable of improving the osmotic tolerance of EGK cauda epididymal spermatozoa, sperm were incubated in hypo-osmotic media (61 and 104 mOsm) containing a range of cytochalasin D concentrations (0-200 microM). Cytochalasin D had no beneficial effect on plasma membrane integrity of sperm incubated in hypo-osmotic media. However, when EGK cauda epididymidal sperm were incubated in isosmotic media, there was a progressive loss of sperm motility with increasing cytochalasin D concentration. The results of this study indicated that the F-actin distribution in cauda epididymidal spermatozoa of the EGK was surprisingly different from that of the Tammar Wallaby (M. eugenii) and that cytochalasin-D does not appear to improve the tolerance of EGK cauda epididymidal sperm to osmotically induced injury.     

Heuristic charge assignment for deconvolution of electrospray ionization mass spectra

We propose a new algorithm for deconvolution of electrospray ionization mass spectra based on direct assignment of charge to the measured signal at each mass-to-charge ratio (m/z). We investigate two heuristics for charge assignment: the entropy-based heuristic is adapted from a deconvolution algorithm by Reinhold and Reinhold;10 the multiplicative-correlation heuristic is adapted from the multiplicative-correlation deconvolution algorithm of Hagen and Monnig.6 The entropy-based heuristic is insensitive to overestimates of z(max), the maximum ion charge. We test the deconvolution algorithm on two single-component samples: the measured spectrum of human beta-endorphin has two prominent and one very weak line whereas myoglobin has a well-developed quasi-gaussian envelope of 17 peaks. In both cases, the deconvolution algorithm gives a clean deconvoluted spectrum with one dominant peak and very few artefacts. The relative heights of the peaks due to the parent molecules in the deconvoluted spectrum of a mixture of two peptides, which are expected to ionize with equal efficiency, give an accurate measure of their relative concentration in the sample.