The variability of patterns of sexual dimorphism in the hominoid skull.

Univariate and multivariate statistical analyses are applied to a number of cranial dimensions and angles from living hominoids in order to investigate the patterns of sexual dimorphism in these groups. Clear differences in patterns of cranial sexual dimorphisms are demonstrated not only between genera but also within a single species (Homo). These differences overlay the common finding of a sexual size difference in all groups. The results imply that caution is required in using the sexual dimorphisms of living hominoids as models for those anticipated in fossils.

Isoflurane and cerebrospinal fluid pressure--a study in neurosurgical patients undergoing intracranial shunt procedures.

The effect of isoflurane 1.0% and 1.5% with nitrous oxide on ventricular cerebrospinal fluid pressure was studied in 17 patients who underwent intracranial shunt procedures. Isoflurane at both concentrations caused significant increases in cerebrospinal fluid pressure during normocapnic ventilation, but these could be prevented by simultaneous hyperventilation or by the prior induction of hypocapnia. Decreases in mean arterial pressure occurred also, and resulted in a significant reduction in cerebral perfusion pressure in normocapnic patients.

Isoflurane: its use to induce hypotension in neurosurgical patients.

The use of isoflurane to induce arterial hypotension was studied in 40 adults undergoing neurosurgery. In 70% of patients, isoflurane, up to 2.0% (inspired), decreased mean arterial pressure (MAP) to the desired level for surgery; for the remainder, a higher concentration (3.0-4.0%) was required. Tachycardia, which could be slowed by labetalol, occurred in 13 patients (32%); the incidence was significantly higher in those who had not received an opiate either as premedication or intra-operatively. No post-operative complications attributable to hypotension were seen. It is concluded that isoflurane is a safe and effective agent for the induction of hypotension in neurosurgical operations.

Measurement of biological shape: a general method applied to mouse vertebrae.

A method is described for recording and analysing the projected shape of mouse vertebrae. The image of the shape is captured by a television camera, cleaned, digitized and subjected to mathematical analysis. A visual representation is obtained by reconstructing the shape in polar coordinates about its centre of area. Further statistical analysis of the whole shape is performed after a Fourier transform. This allows the shape to be represented by and reconstructed from 15 numbers. The method does not rely on homologous points or expert opinion and allows mean shapes to be constructed. It successfully distinguished between 92% of the test data, T1 and T2 vertebrae from two strains of mice.

Optimal radiography of the acutely injured shoulder.

Over ten months, 172 radiographic examinations were performed on acutely injured shoulders, using three views: a) true AP in external rotation b) orthogonal views: 1) supine axial 2) erect 60 degree anterior oblique of all the examinations, 43 were abnormal with a variety of fractures and dislocations. We found the AP view almost twice as effective in detecting any abnormality. Realizing the need for orthogonal views in all shoulder trauma, the axial and anterior oblique were directly compared. Our data indicate that each orthogonal view is of equal value in assessing anterior dislocations and all other injuries. However, the axial projection is a much more difficult study to achieve technically in the acutely injured patient. Thus an examination of the injured shoulder should include two views: an AP in external rotation and a 60 degree anterior oblique. If an axial view can be obtained, it should be added.

Factors determining direct arterial pressure and its variability in hypertensive man.

Intra-arterial pressure was recorded continuously in 26 patients with uncomplicated essential hypertension under standardized conditions. Recordings were analyzed beat by beat to obtain mean pressures and variability, expressed as the standard deviation of the frequency histogram. The major factors influencing variability were the level of pressure and the intensity of physical activity; systolic variability increased with progressive impairment of sino-aortic baroreflexes. Diastolic pressure increased with the level of sympathetic activity as reflected by plasma norepinephrine levels. After allowance for the decrease of plasma renin activity (PRA) with age, direct relationships were observed between PRA (log values) and the level of pressure and systolic variability; plasma angiotensin II values did not correlate. Systolic variability increased with the systolic response to cold but was unrelated to the response to dynamic or isometric exercise. Variability also tended to increase with obesity and was unrelated to age, sex, or race.

The pharmacokinetics of diclofenac sodium following intravenous and oral administration.

The pharmacokinetics of diclofenac were examined following single rapid intravenous injection and also following single oral doses to healthy female volunteers. After intravenous injection plasma levels of diclofenac fell rapidly and were below the limits of detection at 5.5 h postdosing. Individual drug profiles were described by a triexponential function and mean half-lives of the three exponential phases were 0.05, 0.26 and 1.1 h. After oral doses of enteric-coated tablets, the lag time between dosing and the appearance of drug in plasma varied between 1.0 and 4.5 h. However once drug absorption had commenced similar plasma drug profiles were obtained in different individuals. Peak plasma diclofenac levels ranged from 1.4 to 3.0 microgram . ml-1. The mean terminal drug half-life in plasma was 1.8 h after oral doses. This value was not significantly greater than the value of 1.1 h following intravenous doses. Fifty percent of orally dosed diclofenac did not reach the systemic circulation due, predominantly, to first-pass metabolism.

Application of network analysis to the study of the branching patterns of dendritic fields.

The technique of network analysis has been used to define the connectivity and growth of networks generated by monochotomous, dichotomous, and trichotomous branching. The number of distinct topologic branching patterns exhibited by networks with a given number of pendant arcs is defined mathematically; when all types are represented, a complete pendant arc series is formed. The frequency of occurrence of topologic types in these series is unique for a given hypothesis of growth. The growth of the small dendritic arrays such as the basal dendritic fields of neocortical pyramids may be studied by comparing the actual frequency of topologic types with those computed according to given hypotheses. For larger dendritic networks such as those of Purkinje cells in the cerebellum it is only practicable to use the topologic types formed by the peripheral parts of the tree as a basis for comparison. Individual dendritic segments can be ordered sequentially to define their hierarchical arrangement; the frequency of orders in a given network always forms an inverse geometric series. The ratio between orders is called the "bifurcation ratio," and the relationship in a given large series between adjacent orders becomes stabilized to a fixed or "established" bifurcation ratio at the periphery of the tree only. This "established ratio" characterizes the pattern of growth of the network. In the proximal part of the tree the ratio between adjacent orders is unstable and accounts for the variability of the overall bifurcation ratio exhibited by different networks with the same fundamental growth pattern and for the deviation of the overall from the established bifurcation ratio. For a given size of network the overall bifurcation ratio may be similar regardless of the mode of growth. It is concluded that the precise definition of branching structures afforded by network analysis makes this technique well suited for the study of the connectivity, growth, and morphology of dendritic trees.

Thrombolytic therapy in haemolytic--uraemic syndrome.

The treatment of five children with the haemolytic-uraemic syndrome using streptokinase is described to illustrate the difficulties and limitations of thrombolytic therapy in this disease. This experience is germane to the design of multicentre clinical trials.A multivariate analysis relating clinical outcome to the data obtained at the time of admission was also carried out for 31 children with the disease treated in four centres. The results suggest that this technique may help to identify those patients likely to have a fatal outcome. An expanded form of this type of analysis should be incorporated in future clinical trials.