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Biomedical subjects

P M Woodward

Publications and source records attributed to P M Woodward.

At least 19 recordsLinked to original sources
PubMed2001

Prediction of the crystal structures of perovskites using the software program SPuDS.

The software program SPuDS has been developed to predict the crystal structures of perovskites, including those distorted by tilting of the octahedra. The user inputs the composition and SPuDS calculates the optimal structure in ten different Glazer tilt systems. This is performed by distorting the structure to minimize the global instability index, while maintaining rigid octahedra. The location of the A-site cation is chosen so as to maximize the symmetry of its coordination environment. In its current form SPuDS can handle up to four different A-site cations in the same structure, but only one octahedral ion. Structures predicted by SPuDS are compared with a number of previously determined structures to illustrate the accuracy of this approach. SPuDS is also used to examine the prospects for synthesizing new compounds in tilt systems with multiple A-site coordination geometries (a(+)a(+)a(+), a(0)b(+)b(+), a(0)b(-)c(+)).

Journal Article↗
PubMed1984

Anterior capsulotomy of dislocated lenses in Marchesani syndrome using a Nd:YAG laser.

A method of bilateral lens removal in a patient with Marchesani syndrome is described. The patient had nasally dislocated spherical lenses, shallow anterior chambers, brachymorphism, systolic heart murmur, and joint anomalies. Anterior capsulotomies were performed using a mode-locked Nd:YAG laser. The lenses were removed by irrigation-aspiration without complications.

Adult↗
PubMed1984

Anterior capsulotomy using a neodymium YAG laser.

The Neodymium YAG laser can be used to open the anterior capsule of the lens several hours to one day before extracapsular extraction surgery. Opening the capsule prior to cataract surgery allows hydration and spontaneous separation of the cortex from the capsule, simplifying the cataract operation. After the laser procedure, however, many patients develop inflammation and rise in intraocular pressure. The experience of the investigator with 42 consecutive cases in which an anterior capsulotomy was performed with the YAG laser prior to extracapsular cataract surgery is presented. This experience has resulted in an evolving regimen of prelaser medication which has drastically reduced the inflammation and pressure rise.

Cataract Extraction↗
PubMed1977

Accidental hypothermia and impaired temperature homoeostasis in the elderly.

A longitudinal study of the age-related decline in thermoregulatory capacity was made in 47 elderly people to try to identify those at risk from spontaneous hypothermia. During the winters of 1971-2 and 1975-6 environmental and body temperature profiles were obtained in the home, and thermoregulatory function was investigated by cooling and warming tests. Environmental temperature and socioeconomic conditions had not changed but the body core-shell temperature gradients were smaller in 1976, indicating progressive thermoregulatory impairment. People at risk of developing hypothermia also seem to have low resting peripheral blood flows, a nonconstrictor pattern of vasomotor response to cold, and a higher incidence of orthostatic hypotension.

Aged↗
PubMed1977

Somatomedin activity in synovial fluid.

Abnormalities of synovial fluid, as a lubricant and nutrient, may have relevance to the causation of certain articular diseases. The somatomedin activity in normal synovial fluid obtained from the knee joint of the ox has been studied and compared with the activity in serum from the same animal. The porcine costal cartilage bioassay of Van den Brande and Du Caju (1974) has been used with the isotopes 35S-sulphate and 3H-thymidine. The mean potency ratio of ox synovial fluid in terms of ox serum for 35S-sulphate incorporation was 0-28 (range 0-19-0-47) and for 3H-thymidine incorporation 0-35 (range 0-21-0-63). A significant correlation was found between the somatomedin activity (as measured by 35S-sulphate incorporation) and the total protein and albumin concentrations in the ox synovial fluids and the ox sera, but there was no significant relationship between the somatomedin potency ratios and the globulin concentrations. The possible relevance of these findings to injury and disease in synovial joint is discussed.

Albumins↗
PubMed1977

Perthes' disease. A study of radiological features.

A study is presented of the radiographs of 68 patients with unilateral Perthe's diseasemtwo types of Perthe's disease are identified: 'fragmenting' and 'non-fragmenting'. The two radiological types of the disease showed no significant differences in the age at diagnosis, the duration of symptoms before diagnosis and the duration of the disease. However, the radiologically-measureable results at healing, in terms of the epiphyseal, acetabular, acetabulum-head and comprehensive quotients were all very significantly worse when fragmentation had developed.

Age Factors↗
PubMed1973

Body temperatures in the elderly: a national study of physiological, social, and environmental conditions.

Two large-scale surveys of body temperatures in elderly people living at home were carried out in the winter of 1972. Most of the homes visited were cold with room temperatures below the minimum recommended by the Department of Health. Deep body temperatures below 35.5 degrees C were found in 10% of those studied, and the difference between the skin temperature and the core temperature was also reduced in this group. Such individuals are at risk of developing hypothermia since they show evidence of some degree of thermoregulatory failure. Further research is needed, but meanwhile there are practical measures that could be taken to reduce the risk of hypothermia in the elderly.

Age Factors↗
PubMed1973

Problem of the old and the cold.

A pilot winter study of body temperatures using new measuring techniques was tested on 72 volunteers aged 65 or more living in Portsmouth. The body temperatures were related to their environmental temperature and living conditions. No case of serious hypothermia was found, but the study confirms that elderly people have lower body temperatures and suggests that the coldest individuals tended to be the least aware of discomfort from the cold; this may well place them "at risk" for developing hypothermia.

Aged↗
PubMed1971

The British reference preparation for influenza virus haemagglutinin.

The two methods for measuring the haemagglutinin content of an influenza virus suspension are the haemagglutinating (HA) and chick cell agglutinating (CCA) techniques and both measure the same biological activity. With the establishment of an international reference preparation for influenza virus haemagglutinin (type A), however, it seems logical to express the haemagglutinin content of influenza vaccines in international units. Accordingly a collaborative study was arranged in order to obtain agreement on the number of units to be assigned to a British reference preparation for influenza haemagglutinin. It was agreed that the preparation contains 190 i.u. per ampoule and 1 i.u. is contained in 0.0622 mg. of the dried material.

Animals↗
PubMed1970

A collaborative study of heparins from different sources.

Until about 10 years ago heparin was prepared from ox lungs and was regarded as a homogeneous polymer (of a sulfated mucopolysaccharide) with a relatively constant biological activity of about 100 IU/mg. The mucus and mucosa of the intestine of hog, sheep and ox have now become the main industrial source of bulk starting material. Preparations from this new source have much higher specific biological activity and have been shown to consist of mixtures of components with a number of different chemical and physical characteristics. It had been variously reported that preparations of heparins from the 2 sources gave significantly different estimates when bioassayed by the 2 different pharmacopoeial assay methods which are in wide use. If this is in fact the case these discrepancies could cause trouble in commerce, national control and clinical usage.This paper describes an international collaborative study to investigate this and other problems in the assay of heparin. In this study preparations of heparin made from the intestinal mucosa of each of 3 species (hog, sheep and ox) were biossayed with the International Standard for Heparin (from ox lung) established in 1958. Two of these preparations were national standards.The results showed differences between the estimated relative potencies of heparins of lung and mucosal origin, but they were not so consistent as to necessitate a separate international standard for each, although the imprecision of the assays may have concealed significant heterogeneity arising from real differences between the preparations. A further problem brought to light in this study was that, with the 2 pharmacopoeial assay methods in wide use, simple replicate assays using the same substrate gave estimates so precise that an analysis of variance on them was meaningless, whereas estimates between laboratories or with different substrate batches could vary by as much as 40%-50%.It is suggested that estimates of the biological activity of heparin preparations should be based on several independent assays using different batches of substrate.The biological assay methods currently used were devised some 15-20 years ago and, in the light of modern knowledge of mechanisms of blood clotting, are regarded as unsatisfactory in a number of respects. It is hoped that research into the mechanism of action of heparin will lead to improved methods of assay.

Animals↗
PubMed1967

The international reference preparation of gramicidin.

The National Institute for Medical Research, London, was requested by the WHO Expert Committee on Biological Standardization to establish an International Reference Preparation of Gramicidin. This preparation was needed to standardize preparations of gramicidin containing predominantly gramicidin A, B and C, for which purpose the International Reference Preparation of Gramicidin S cannot be used. A batch of 100 g of crystalline gramicidin obtained in 1963 was distributed into ampoules in 55 mg amounts and dried in vacuo; the ampoules were then filled with dried nitrogen and sealed. The proposed international reference preparation was assayed biologically against the Master Standard of Gramicidin of the US Food and Drug Administration in 7 laboratories in 6 countries by turbidimetric methods.Significant curvature of the dose-response lines was found for most assays; no single transformation improved the linearity of assays from all laboratories. Although significant heterogeneity of potencies was obtained in 5 laboratories the mean potency ratios for all laboratories only varied over a range of 5% to 6%. The composition of the material is 7% gramicidin B, 50% gramicidin A and 25% gramicidin C; preparations of gramicidin containing appreciably higher concentrations of gramicidin B can be expected to give invalid assays against the international reference preparation.The material has been established as the International Reference Preparation of Gramicidin with a defined potency of 1000 IU/mg. The International Unit of Gramicidin is defined as the activity of 0.001 mg of the International Reference Preparation of Gramicidin.

Tyrothricin↗