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Biomedical subjects

G J Williams

Publications and source records attributed to G J Williams.

At least 91 records · Page 5Linked to original sources
PubMed1980

Dopamine infusion for the treatment of myocardial dysfunction associated with a persistent transitional circulation.

Four infants with myocardial dysfunction associated with a persistent transitional circulation were given dopamine infusions in addition to standard treatment. The condition of each improved strikingly with rapid diminution in heart size as judged by chest x-ray. Dopamine has a place in the management of the sick infant with a persistent transitional circulation.

Dopamine↗
PubMed1980

Results of 24 hour ambulatory monitoring of electrocardiogram in 131 healthy boys aged 10 to 13 years.

Ambulatory monitoring of the electrocardiogram was performed in 131 healthy boys aged between 10 and 13 years for two consecutive periods of 24 hours. When awake the maximal heart rates ranged from 100 to 200 and the minimal from 45 to 80 beats per minute. During sleep maximal rates were 60 to 110 beats and minimal rates 30 to 70 beats per minute. Sinus arrhythmia was seen in every boy and in 36 (27.5%) no other changes were found. Sinuatrial block, Mobitz type I, was not seen. Sinuatrial block, Mobitz type II, occurred twice only. Complete sinuatrial block occurred in 8.4 per cent, never lasted more than one cycle, and was always followed by a junctional beat. First degree atrioventricular block occurred in 8.4 per cent and Mobitz type I atrioventricular block in 10.7 per cent. Premature beats were always single, atrial in 13 per cent, ventricular in 26 per cent, and except in two boys were never more than four in 24 hours. There were no episodes of ventricular or supraventricular tachycardia. Changes in P wave morphology were common and slow junctional rhythm occurred in 13 per cent during sleep.

Adolescent↗
PubMed1980

Changing muscle patterns in a segmental epidermal field.

The spatial rearrangements that take place during metamorphosis in the abdominal sternites and associated retractor muscles of the beetle Tenebrio molitor are described. This paper provides the descriptive background needed to consider whether a morphogenetic gradient is involved in specifying the position at which adult muscle attachments develop. (Experimental work in support of this gradient hypothesis is published in a companion paper.) The ventral abdominal retractor muscles are extensively remodelled at metamorphosis so that the adult muscles differ considerably in appearance from the larval muscles from which they are derived. In particular, there is a change in both the absolute and relative positions of the sites of muscle attachment. Rearrangement of muscles takes place during both the prepupal period and the pupal stage. It is achieved by means of two separate and temporally distinct mechanisms. Epidermal remodelling in the pre-pupal period results in the movement of attached retractor muscles (epidermokinetic muscle movement). In the pupal stage, however, the muscles move over the basal surface of the epidermis (myokinetic muscle movement). Myokinetic movements may be brought about by extension of myoblast processes from the metamorphosing muscles. These findings are considered in terms of Poyarkoff's theory that the pupa serves as an integumental mould, approximating the shape of the adult, within which certain adult muscles develop.

Animals↗
PubMed1980

A gradient of morphogenetic information involved in muscle patterning.

The results of grafts performed in the larva of the beetle Tenebrio molitor reveal that the position at which certain adult muscle attachments form is specified by a regulative, rather than a mosaic, mechanism. The results of grafts involving the rotation of squares of integument through 180 degrees or 90 degrees, or the antero-posterior transposition of two adjacent rectangles of integument, show that the site of muscle attachments in the antero-posterior axis of an abdominal sternite is specified by an epidermal segmental gradient of positional information. This gradient is presumed to be identical to the gradient which specifies cuticular patterns in this insect. There is a good correlation between the effect of grafts on adult muscle morphology and cuticular patterns.

Animals↗
PubMed1977

The Protein Data Bank. A computer-based archival file for macromolecular structures.

The Protein Data Bank is a computer-based archival file for macromolecular structures. The Bank stores in a uniform format atomic co-ordinates and partial bond connectivities, as derived from crystallographic studies. Text included in each data entry gives pertinent information for the structure at hand (e.g. species from which the molecule has been obtained, resolution of diffraction data, literature citations and specifications of secondary structure). In addition to atomic co-ordinates and connectivities, the Protein Data Bank stores structure factors and phases, although these latter data are not placed in any uniform format. Input of data to the Bank and general maintenance functions are carried out at Brookhaven National Laboratory. All data stored in the Bank are available on magnetic tape for public distribution, from Brookhaven (to laboratories in the Americas), Tokyo (Japan), and Cambridge (Europe and worldwide). A master file is maintained at Brookhaven and duplicate copies are stored in Cambridge and Tokyo. In the future, it is hoped to expand the scope of the Protein Data Bank to make available co-ordinates for standard structural types (e.g. alpha-helix, RNA double-stranded helix) and representative computer programs of utility in the study and interpretation of macromolecular structures.

Computers↗
PubMed1977

Effects of temperature on the hill reaction and photophosphorylation in isolated cactus chloroplasts.

Chloroplasts isolated from Opuntia polyacantha Haw. (Cactaceae) are capable of noncyclic electron transport and ATP synthesis. Hill reaction rates, measured by O(2) evolution or by ferricyanide reduction, increase with increasing temperature to approximately 40 C. The temperature optimum of NADP reduction is 42 C while the optimum for noncyclic photophosphorylation is 35 C. NADP-linked phosphorylation exhibits a higher coupling ratio (P/e(2)) than ferricyanide-linked photophosphorylation. The temperature optima for photochemical energy production correlate with photosynthetic properties of Crassulacean acid metabolism (CAM) plants and are discussed in relation to the operation of CAM at high tissue temperature.

Journal Article↗
PubMed1977

The vectorcardiographic estimation of left ventricular filling pressure following acute myocardial infarction.

High gain vectorcardiograms, in the "timed" mode, have been recorded in 50 patients hospitalized with noncardiac complaints, and in 32 previously well patients following acute myocardial infarction. The terminal component of the atrial vector loop has been analysed in the horizontal, frontal and sagittal planes in all the cases. A technique is described by which the three variables, magnitude, direction and depolarization time of the terminal atrial vector in each plane can be summated to give a numerical value for the total displacement of left atrial activity. This figure is referred to as the "total vector value". In the 32 postinfarction patients the "P-terminal force" was also measured from lead V1 of the scalar electrocardiogram. In these patients both the total vector value and the "P-terminal force" was correlated with the pulmonary diastolic pressure, as an indirect assessment of left ventricular filling pressure. In the immediate postinfarction period the correlation between the total vector value and the pulmonary diastolic pressure was good (r = 0.92), but that between the "P-terminal force" and the pulmonary diastolic pressure was poor (r = 0.11). Alterations in atrial electrical activity recorded by either method correlated poorly with changes in the pulmonary arterial pressure occurring more than 36 h after acute infarction. The "total vector value" provides an accurate noninvasive method for the detection of a rise in the left ventricular enddiastolic pressure within the first 36 h following an acute myocardial infarction. It is superior in this respect to the "P-terminal force" measured from the standard scalar electrocardiogram.

Adult↗
PubMed1976

Mucocutaneous lymph node syndrome with coronary artery aneurysm.

A white North American girl with clinical features of the mucocutaneous lymph node syndrome had a myocardial infarct and angiographic evidence of a coronary artery aneurysm and mitral regurgitation. The mucocutaneous lymph node syndrome has been extensively diagnosed in Japan in recent years. It appears to be a distinct entity, although not precisely separated from polyarteritis nodosa in childhood. The condition may be more common than previously realized.

Aneurysm↗
PubMed1975

A simplified technique for the production of experimental aortic regurgitation.

A simple and effective method for the production of aortic incompetence in dogs is described. The instrument used in the procedure can be made easily and is robust. Controlled rupture of one or more of the three aortic valve cusps can be achieved without thoracotomy. There was no immediate operative mortality in the study and the time required to complete the procedure averaged 30 min. No evidence of healing of the cusp rupture could be found at necropsy even in dogs sacrificed 480 days after operation.

Animals↗