Fatty acids. part 42 The preparation and properties of methyl monomercaptostearates. some related thiols, and some methyl epithiostearates

Some saturated and unsaturated mercapto C₁₈ esters have been obtained for the first time. Such compounds are prepared from hydroxy esters via their mesyloxy derivatives by reaction with sodium hydrogen sulphide or with potassium thioacetate (followed by deacetylation) or from alkene esters by radical addition of thioacetic acid. The mercapto esters are readily identified by infrared, nuclear magnetic resonance, and mass spectroscopic procedures, preferably after acetylation or trifluoroacetylation.γ-Mesyloxy alkenes furnish tetrahydrothiophen rather than mercapto alkenes and methyl 9,12-epithiostearate was synthesised by an independent route from thiophen.     

Field evaluation of a model of photothermal flowering responses in a world lentil collection

A model to predict flowering time in diverse lentil genotypes grown under widely different photothermal conditions was developed in controlled environments. The present study evaluated that model with a world germ plasm collection of 369 accessions using two field environments in Syria and two in Pakistan. Photoperiod alone accounted for 69% of the variance in 1/f, the reciprocal of time (d) from sowing to flower. In contrast, temperature alone did not account for a significant proportion of variation in flowering time due to the exposure of plants to supra-optimal temperatures in the late-sown Syrian trial. With the model mean pre-flowering values of photoperiod and temperature combined additively to account for 90.3% of the variance of 1/f over accessions. The correlation of field-derived estimates of temperature sensitivity of accessions to glass-house-derived estimates was significant at P = 0.05, but the equivalent correlation for estimates of photoperiodic sensitivity was higher at P < 0.01. Flowering in the field was better measured as time from sowing to 50% plants in flower rather than time to first bloom or its node number. Dissemination of the lentil crop following domestication in West Asia to the lower latitudes such as Ethiopia and India has depended on selection for intrinsic earliness and reduced sensitivity to photoperiod. Movement from West Asia to the higher latitudes accompanied by spring sowing has resulted in a modest reduction in photoperiod sensitivity and an increase in temperature sensitivity.     

Are pre-hospital deaths from accidental injury preventable?

OBJECTIVE--To determine what proportion of pre-hospital deaths from accidental injury--deaths at the scene of the accident and those that occur before the person has reached hospital--are preventable. DESIGN--Retrospective study of all deaths from accidental injury that occurred between 1 January 1987 and 31 December 1990 and were reported to the coroner. SETTING--North Staffordshire. MAIN OUTCOME MEASURES--Injury severity score, probability of survival (probit analysis), and airway obstruction. RESULTS--There were 152 pre-hospital deaths from accidental injury (110 males and 42 females). In the same period there were 257 deaths in hospital from accidental injury (136 males and 121 females). The average age at death was 41.9 years for those who died before reaching hospital, and their average injury severity score was 29.3. In contrast, those who died in hospital were older and equally likely to be males or females. Important neurological injury occurred in 113 pre-hospital deaths, and evidence of airway obstruction in 59. Eighty six pre-hospital deaths were due to road traffic accidents, and 37 of these were occupants in cars. On the basis of the injury severity score and age, death was found to have been inevitable or highly likely in 92 cases. In the remaining 60 cases death had not been inevitable and airway obstruction was present in up to 51 patients with injuries that they might have survived. CONCLUSION--Death was potentially preventable in at least 39% of those who died from accidental injury before they reached hospital. Training in first aid should be available more widely, and particularly to motorists as many pre-hospital deaths that could be prevented are due to road accidents.     

Evaluation of scanning resolution,detector choice and detector orientation to be used for accurate and time-efficient commissioning of a 6MV clinical linear accelerator

The present study is aimed at exploring different scanning parameters, detectors and their orientations for time-efficient and accurate commissioning of a 6 MV clinical linear accelerator (LINAC). Beam profiles and percentage depth dose (PDD) curves were measured with a PTW dosimetry diode, a PTW Semiflex and a PinPoint ion chamber in different orientations. To acquire beam data, equidistant (step size of 0.5 mm, 1 mm, 2 mm and 3 mm) and fanline (step size of 2–0.5 mm, 2–1 mm, 3–0.5 mm and 3-1 mm) scanning modes were employed and data measurement time was recorded. Scan time per measurement point was also varied (0.2 s, 0.5 s and 1.0 s) to investigate its effect on the accuracy and acquisition time of beam data. Accuracy of the measured data was analyzed on the basis of the variation between measured data and data modeled by a treatment planning system. Beam profiles (particularly in penumbra region) were found to be sensitive to variation in scanning resolution and showed an improved accuracy with decrease in step size, while PDD curves were affected negligibly. The accuracy of beam data obtained with the PTW dosimetry diode and the PinPoint ion chamber was higher than those obtained with the PTW Semiflex ion chamber for small fields (2?×?2 cm² and 3?×?3 cm²). However, the response of the PTW diode and the PinPoint ion chamber was significantly indifferent in these fields. Furthermore, axial orientation of the PTW Semiflex ion chamber improved accuracy of profiles and PDDs as compared to radial orientation, while such a difference was not significant for the PinPoint ion chamber. It is concluded that a scan time of 0.2 s/point with a fanline scanning resolution of 2–1 mm for beam profiles and 3 mm for PDDs are most favorable in terms of accuracy and time efficiency. For small fields (2?×?2 cm² and 3?×?3 cm²), a PinPoint ion chamber in radial orientation or a dosimetry diode in axial orientation are recommended for both beam profiles and PDDs. If a PinPoint ion chamber and a PTW dosimetry diode are not available, a Semiflex ion chamber in axial orientation may be used for small fields.

     

Measurement of serum gentamycin levels by rapid tests

Gentamicin is a very useful antimicrobial agent for the treatment of serious infections caused by gram-negative bacteria. However, it's low therapeutic index and potential ototoxic and nephrotoxic side effects necessitate frequent determinations of serum concentration to assist in maintaining therapeutic levels and avoiding toxic levels. Two bioassays and a latex agglutination inhibition card (LAIC) test were evaluated to determine gentamicin levels in nearly 100 patient sera. Results were compared with a radioimmunoassay (RIA). Two bioassays, the Bio-Monitor and the GentaSak, gave correlation coefficients of 0.987 and 0.982, respectively. The correlation coefficient for the LAIC test was 0.987. All three tests compared well with RIA in accurately detecting gentamicin levels in patient as well as simulated sera. The LAIC test, however, was more rapid, giving results within half an hour whereas bioassays required 6–8 hours for completion. The LAIC test was also found to be more economical. It provides a suitable alternative to RIA procedures in small laboratories and for performing stat tests since batching is not necessary.     

Simple and sensitive high-performance liquid chromatographic method for the determination of diltiazem and six of its metabolites in human plasma

A sensitive, specific and reproducible high-performance liquid chromatographic technique is described for the simultaneous determination in human plasma of diltiazem (DZ) and six of its primary and secondary metabolites which are products of N- and O-demethylation, deacetylation and N-oxidation. The method involves addition of excess KHCO₃ to 1 ml of plasma, followed by extraction with 4 ml of ethyl acetate. The organic layer was extracted with 0.01 M HCl and the aqueous layer was dried under nitrogen and then reconstituted with 0.002 M HCl. DZ and its metabolites were free from interference and were baseline-separated. Calibration curves were linear in the concentration range studied (5–500 ng/ml for all the species). The lower limit of quantification of the assay was 5 ng/ml for DZ and the metabolites. Inter-day and intra-day coefficients of variation were less than 10%. The applicability of this procedure is shown by evaluating the kinetics of DZ and its metabolites in three patients receiving chronic DZ therapy. N-Demethyldiltiazem, deacetyldiltiazem and N-demethyldeacetyldiltiazem were found to be the major metabolites, as previously described. Deacetyldiltiazem N-oxide was found in two of the patients. The other two known but unreported metabolites in human, O-demethyldeacetyldiltiazem and N,O-didemethyldeacetyldiltiazem, were found in the plasma of all three patients.