Organ donation from intensive care units in England.

OBJECTIVE--To audit all deaths in intensive care units (excepting coronary care only and neonatal intensive care units) in England to assess potential for organ procurement. DESIGN--An audit in which 14 regional health authorities and London special health authorities each designated a regional liaison officer to identify intensive care units and liaise with Department of Health and the Medical Research Council''s biostatistics unit in distribution, return, and checking of audit forms. Audit took place from 1 January to 31 March 1989 and will continue to 31 December 1990. SETTING--278 Intensive care units in England. PARTICIPANTS--Colleagues in intensive care units (doctors, nurses, coordinators, and others), who completed serially numbered audit forms for all patients who died in intensive care. RESULTS--The estimated number of deaths in intensive care units was 3085, and validated audit forms were received for 2853 deaths (92%). Brain stem death was a possible diagnosis in only 407 (14%) patients (about 1700 cases a year) and was confirmed in 282 (10%) patients (an estimated 1200 cases a year). Half the patients (95% confidence interval 45% to 57%) in whom brain stem death was confirmed became actual donors of solid organs. Tests for brain stem death were not performed in 106 (26%) of 407 patients with brain stem death as a possible diagnosis, and general medical contraindication to organ donation was recorded for 48 (17%) of 282 patients who fulfilled brain stem death criteria before cessation of heart beat. The criteria were fulfilled before cessation of heart beat and in the absence of any general medical contraindication to organ donation in 234 patients, 8% of those dying in intensive care (an estimated 1000 cases a year). Consent for organ donation was given in 152 (70%) of 218 cases (64% to 76%) when the possibility of organ donation was suggested to relatives. In only 14 out of 232 families (6%; 3% to 9%) was there no discussion of organ donation with relatives. Corneal suitability was recorded as "not known" in a high proportion (1271; 45%) of all deaths and intensive care units reported only 123 corneal donors (4% of all audited deaths). CONCLUSION--When brain stem death is a possible diagnosis tests should always be carried out for confirmation. Early referral to the transplant team or coordinator should occur in all cases of brain stem death to check contraindications to organ donation. There should be increased use of asystolic kidney donation, and patients should be routinely assessed for suitability for corneal donation. Finally, more publicity and education are necessary to promote consent.     

A deactivating conformational change induced by reduced nicotinamide-adenine dinucleotide phosphate in a Neurospora glutamate dehydrogenase.

Stopped-flow fluorescence techniques have been used to observe the formation of the binary comples of E-NADPH. At pH 7.5 there is a protein conformational change after the formation of the binary complex. This conformational change can be detected by a decrease in the fluorescence intensity of the complex at 350 nm and by an increase in its fluorescence intensity at 450 nm.     

Pressure regulation in the microcirculation.

The results of direct pressure measurements are described which demonstrate that pressures in a certain fraction of mesenteric capillaries remain remarkably constant during large changes in systemic pressure. The results of isogravimetric studies, reported in the literature, are also described which indicate that this phenomenon may also occur in the intestine. The question is raised whether capillary pressures may therefore be regulated. Pressures recorded from mesenteric arterioles and capillaries are shown which indicate that maintenance of a constant capillary pressure is primarily the consequence of the vascular architecture peculiar to this tissue, and is merely a secondary reflection of mechanisms associated with flow regulation. The results of direct pressure measurements recorded in the microcirculation of intestinal muscle are also shown. These data indicate that capillary pressures in innervated, denervated, and xylocaine-treated intestinal muscle change in direct proportion to variations in arterial pressure. It is concluded that capillary pressures in the intestinal muscle layers are therefore not regulated, so that the observation that capillary pressures may be maintained is probably a phenomenon unique to the mesentery. Pressures recorded from capillaries in the mucosal villi are also shown and compared to capillary pressures measured in the microvasculature of mesentery and intestinal muscle. When systemic pressure was normal (107 +/- 10 mm Hg), capillary pressure in the mesentery averaged 30 to 33 mm Hg; capillary pressures in the intestinal muscle averaged 22 to 24 mm Hg; and capillary pressures in the mucosal villi averaged 13 to 15 mm Hg. These data suggest that mesenteric capillaries are primarily a filtering network; intestinal muscle capillaries are normally in fluid balance; whereas at rest mucosal capillaries are primarily absorptive. These pressures, recorded from the three major regions of the rat intestine, were used to calculate a weighted average for the whole organ. The calculated value, based on assumed values for relative capillary densities, was 17 mm Hg. This result compares favorably with data from whole organ, isogravimetric studies, and may clarify some of the apparent discrepancies between previous isogravimetric and servopressure studies.     

Mother-offspring conflict and interference at mother's mating inMacaca fascicularis

Theory suggests that it is in the interest of an infant to garner more care than its mother is selected to provide and that a rival sibling would curtail care from the mother. Thus delayed conception in the mother would be of advantage to the infant. One method of achieving this result would be to interfere with the mother's potential matings. To test this theory, the conflict between mothers and their infants in relation to maximizing inclusive fitness has been studied inMacaca fascicularis and infant interference has been observed. Focal animal samples were taken on 8 mothers and their 13 infants. Interactions analyzed were those between the mother and (1) an adult male, (2) her infant, (3) an adult female, (4) her infant and an adult male, (5) her infant and an adult female. Only explicit behaviours were analyzed. The infant's interference was found to be significantly related to its mother's mating, and this produced a deterring effect on the male. Infants did not interfere with any female's matings other than those of their mother. The interference was related to the number of mother-male contacts. In mothers that did subsequently conceive, infant interference at mating increased up to the mother's conception date and decreased thereafter. By contrast to the infants direct method, mothers approached the conflict indirectly. There were significantly more contacts and mounts with males in their infant's absence, they reacted negatively to their infant only when it had interfered, they were more lenient in the presence of an adult female than with an adult male, and they avoided their infant's presence at mother-male contacts. No significant sex bias in interference or the number of contacts with mother-male pairs has been found. There are indications of a sibship pattern of interference.     

Studies on human pregnancy-associated plasma protein A. Purification by affinity chromatography and structural comparisons with alpha 2-macroglobulin.

Pregnancy-associated plasma protein-A (PAPP-A) has been purified by a combination of methods including antibody-affinity chromatography. The resultant protein, obtained in 16% yield from maternal serum, appeared as a single major component on non-denaturing polyacrylamide and SDS/polyacrylamide gel electrophoresis. The protein showed a single component when analysed by isoelectric focusing under denaturing conditions in the presence and absence of reduction and had a pI of 4.34 and 4.42 respectively. These pI values were indistinguishable from those of alpha 2-macroglobulin (alpha 2M). The molecular weight of the PAPP-A polypeptide as shown by SDS/polyacrylamide-gel electrophoresis was 187000, with a minor component of mol.wt. 82500 that was attributed to proteolysis. Since native PAPP-A had a molecular weight on gel chromatography very similar to that of alpha 2M (620000--820000), it was concluded that PAPP-A was a homotetramer. In the absence of reduction, a high-molecular-weight (420000) protomer of PAPP-A was found. It was deduced that PAPP-A, like alpha 2M, is a dinner, whose protomers are composed of disulphide-linked polypeptide chains. It was found that the molecular weight of the PAPP-A polypeptide exceeded that of alpha 2M by 3.3%, but that the total carbohydrate content of PAPP-A exceeded that of alpha 2M by 10% and that its neutral carbohydrate content exceeded that of alpha 2M by between 7.4 and 9.0%. The significance of the estimated molecular weights of alpha 2M (181000) and its major tryptic fragments is discussed in the light of published values. A tryptic fragment alpha 2M (82500 mol.wt.) was apparently the same size as the major tryptic fragment of PAPP-A.     

Isolation of Living Endothelial Cells by Gelatin-Film Stripping of Vascular Walls

The few available techniques for the isolation of fresh endothelial cells yield harvests heavily contaminated with other cells. A procedure which we have found to be both selective and compatible with viability entails the use of gelatin-coated slides to separate the endothelial surface. When the gelatin has set and the vessel is peeled off, about 7680% of the endothelial cells remain on the slide; of these, less than 10% are other cell types. That the procedure is compatible with survival may be demonstrated by culturability of the harvested cells.     

A comparison of accessibility of ribosomal proteins on free and membrane-bound ribosomes: the ribosomal proteins potentially involved in ribosome-membrane binding

The relative accessibility of rat liver ribosomal proteins to reductive methylation was examined using membrane-bound and free ribosomes. Comparisons indicated that 12-13 large ribosomal proteins are masked by ribosomal association with membranes. These consisted of L8, L10, L17, L26-28, L31 and L36, and probably also include L4, L5, L7 and L29. These proteins seem to surround a region centered about L3 and may partly define a ribosomal channel through which the nascent peptide emerges. Approx. 10-20% of the large ribosomal subunit surface area is shielded by the membrane.