Role of modern radiological investigations in obstructive uropathy.

Obstructive uropathy in its various forms accounts for much of the work load in urological units and general hospitals. Until recently, laboratory tests and excretion urography were the only procedures available for its assessment. The past few years have seen the development and refinement of ultrasound, examination by computer tomography, nuclear medicine, antegrade pyelography, and perfusion pressure flow studies. This paper examines the particular qualities of these modern procedures and their role in the clinical assessment of the obstructed urinary tract.     

Laboratory and radiological investigations in general practice. I-Type requested and rate of use.

The use that 30 general practitioners in four group practices made of open access laboratory and radiological facilities was studied for one year. We were particularly interested in whether general practitioners hoped to exclude rather than confirm abnormality when requesting investigations. All but two of the general practitioners studied used investigations to exclude abnormality to a greater extent than to confirm it. The rate at which the practices investigated patients and the number of investigations requested were appreciably different and were different for individual general practitioners, part time general practitioners requesting more investigations than trainees and full time general practitioners. Haematological investigations accounted for over 30% of requests for investigations in all but one practice, biochemical investigations being requested as often as bacteriological investigations in two of the four practices. The ratio of expected to unexpected results varied among general practitioners; no general practitioner had more unexpected results and the range of ratios was similar for full time and part time general practitioners and for trainees. The proportion of patients with abnormalities uncovered by each practice increased disproportionately as the use of investigations increased, supporting a higher rather than lower rate of investigation among general practitioners. Compared with the results of other studies the use of the radiological facilities available was low. X ray examinations of the skeleton were requested more than chest and contrast media examinations by three of the four practices. Most x ray examinations were used to exclude rather than confirm abnormality by all the practices, with over 85% of results confirming the general practitioner''s initial diagnosis.     

Electromyographic investigations in torticollis.

In 13 patients with torticollis, the electromyographic (EMG) activity in the neck muscles at rest was investigated before, during and after stimulation of the H1 bundle (in horizontal torticollis) and inner part of oral ventral nucleus (in the rotatory form), as well as after coagulation. Three EMG types of torticollis-spasmodic, myoclonic and mixed - could be differentiated. During the 8-, 25- and 50-Hz stimulations, a diminution in the amplitude and frequency of muscle potentials, followed by electric silence, was most often obtained; in general, the electric silence was preceded by a rhythmic activity of grouped potentials. Following coagulation, no spontaneous EMG activity was any longer recorded in the neck muscles, in the majority of the cases.     

Effectiveness of out-of-hours biochemistry investigations.

A survey was carried out of doctors who used their out-of-hours biochemistry service to find out why requests for investigations were made, how often the results altered patient management, and whether they could define areas where investigations were unproductive. Of 107 questionnaires distributed, 147 (88%) were completed. In 86% the requests were for diagnosis or immediate patient management and in 35% the results actually altered management. Senior clinical staff were more efficient than their juniors in instigating biochemical investigations that proved to be effective. In no instance where the clinical staff predicted that it was unlikely that the results would alter management was management altered. It is suggested that joint reviews of case notes by junior and senior clinical staff would prove to be the most appropriate way to increase the effectiveness and efficiency of clinical investigation.     

Structural investigations on DNA-protamine complexes.

Protamine·DNA complexes in film and in solution have been investigated by means of infrared linear dichroism, ultraviolet circular dichroism, and laser Raman spectroscopy. At high relative humidity and in solution both infrared linear dichroism and ultraviolet circular dichroism indicate the presence of a modified B form of DNA (designated as B* in our other papers^27,28,46). This modified B form is characterized by a change of the orientation of the \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{OPO} $\end{document} bisector angle by about 4° with respect to the helical axis when compared to the B form of DNA. At decreasing relative humidities the same modified B form is maintained and no structural transitions B → A (or B → C) normally occurring in free DNA were observed. The absence of the A form in these complexes was also confirmed by laser Raman scattering studies of protamine·DNA complexes. On the basis of these results, a model of the protamine·DNA complex is proposed, which suggests that the presence of apolar amino-acid residues, and probably the folding of the polypeptide chain, is responsible for preventing the B-to-A transition; this occurs either by protecting the high-humidity modified B form against dehydration or by steric interference of this protein probably located in one of the DNA grooves.     

Physico-chemical limitations in experimental investigations.

An element or compound in a natural water system is usually distributed between a variety of physico-chemical forms, both dissolved and particulate. The distribution is determined by the properties of the ion or molecule in question and by a number of major variables, including ionic strength, the nature and concentrations of major dissolved elements, particulate matter and organic complexing material, pH and the electron activity (pE); it may thus vary widely between different environments. The design of experiments to study sublethal effects of pollutants in sea water ideally requires that the test medium is closely matched to the environment for which information is needed, with respect to the ranges of concentration and activity, and the chemical speciation, of the pollutant and of any other constituents which may influence its effects. This in turn requires either that the pollutant can be added in the appropriate forms, implying a knowledge of the existing speciation, or that the added material rapidly exchanges with the forms already present. The implications of these requirements are most apparent for those pollutants that show complex chemical behaviour in sea water. This account concentrates on metals of toxicological significance. Consideration of particulate associations, redox speciation, and complex formation in the dissolved state with inorganic and organic ligands, suggests that physicochemical factors limit the usefulness, in terms of environmental predictions, of experimental studies of biological effects of metals, both inherently and through inadequate knowledge of environmental speciation and the mechanisms and rates of interconversion between species. Of particular importance are non-equilibrium features in speciation, such as the presence of thermodynamically unstable oxidation states and of kinetically non-labile associations. Interpretation of the nature of these associations is complicated by the presence of colloidal and organic macromolecular material in dissolved fractions as conventionally defined. While the chemical behaviour of some substances in sea water is considerably less complicated than that of the trace metals, there is a need with all types of pollutants for greater attention to physico-chemical factors in both the design and interpretation of experiments to investigate biological effects.