Pulmonary alveolar proteinosis complicated by cerebral abscess: report of a case.
Explore the source record for details and available documents.
Brain Abscess↗
Biomedical subjects
D A Walker
Publications and source records attributed to D A Walker.
Necrotizing granulomatous splenitis complicating leukemia in childhood.
Two children are described with acute leukemia in remission who both developed a swinging pyrexia and pathologically identical splenic necrotizing granulomata. No organisms were seen in, or isolated from, either spleen. After splenectomy, systemic symptoms persisted and did not resolve until steroids were given. The etiology of this syndrome remains unknown.
Antineoplastic Combined Chemotherapy Protocols↗
The relationship between light scattering and chlorophyll a fluorescence during oscillations in photosynthetic carbon assimilation.
Light scattering, which can be taken as an indicator of the transthylakoid proton gradient, and the 518-nm rise, which can be regarded as a measure of the transthylakoid membrane potential, have been followed during oscillations in chlorophyll a fluorescence, which are known to be associated with corresponding changes in photosynthetic carbon assimilation. Both components oscillated in a manner which was broadly reciprocal to chlorophyll a fluorescence. However, there was a phase shift such that the light-scattering change usually anticipated fluorescence and often also the 518-nm shift. It is concluded that the proton motive force rises and falls slightly in advance of rises and falls in carbon assimilation. The relationship of these changes to a possible underlying mechanism is discussed.
Carbon↗
The role of serum tumour markers to aid the selection of lung cancer patients for surgery and the assessment of prognosis.
We have measured the following ten serum proteins in a sample of 290 patients presenting with possible lung cancer: carcinoembryonic antigen (CEA), alpha 1-acid glycoprotein (AGP), C-reactive protein (CRP), ferritin (FER), prealbumin (PAB), third component of complement (C3), immunoglobin E (IgE), alpha 2-pregnancy-associated glycoprotein (PAG), beta 2-microglobulin (beta 2-m) and retinol binding protein (RBP). It is found that, with the exception of PAG, C3 and IgE, there are significant differences between protein concentrations in the subsequently diagnosed cancer and non-cancer patients. However, protein concentrations in the cancer patients who were suitable for surgery do not differ significantly from the concentrations in inoperable patients. The prognostic significance of the proteins in the inoperable and operable cancer patients is also envisaged. In the operable group C3 appears to be useful, whilst AGP and RBP are prognostic indicators in the inoperable group.
Blood Proteins↗
Effects of polyethylene-glycol-induced osmotic stress on transpiration and photosynthesis in pinto bean leaf discs.
A new leaf disc chamber allows measurements of chlorophyll fluorescence and CO(2) and H(2)O vapor exchanges during infusion of solution into the cut edge of the disc. Polyethylene glycol (molecular weight, 6000) was used to apply a mild external osmotic stress to the leaf disc within this chamber. This stress rapidly caused a temporary increase in transpiration. This increase was reversed (5-6 minutes later) and after 20 to 25 min, the stomates nearly completely closed. Internal CO(2) (calculated) and leaf temperature followed the transpiration measurements. However, chlorophyll fluorescence (small rise) followed internal CO(2) (small rise). This complete sequence of events resembles those caused by exposure of leaves to certain air pollutants which have been seen to cause such a transient increase followed by a decrease in stomatal closure.
Journal Article↗
Influence of glycerate on photosynthesis by wheat chloroplasts.
Glycerate was found to effect photosynthetic O2 evolution in wheat chloroplasts by its conversion to triose phosphate and by influencing the rate of photosynthesis through the reductive pentose phosphate pathway. In the absence of bicarbonate, the photosynthetic O2 evolution with glycerate was low (10 to 25 mumol mg chlorophyll-1 h-1), and only about 15% of the rate of bicarbonate-dependent O2 evolution under optimum conditions. This corresponds to a rate of glycerate conversion to triose phosphate of 20 to 50 mumol mg chlorophyll-1 h-1, which appears sufficient to accommodate flux through the glycolate pathway in vivo. Pi was required for this glycerate-dependent O2 evolution; rates remained relatively constant between 0.1 and 40 mM Pi, and proceeded with little lag upon illumination (less than 0.5 min). Evidence for O2 evolution due to glycerate conversion to triose phosphate could be conclusively demonstrated by addition of glycolaldehyde, an inhibitor of the regenerative phase of photosynthesis, which prevents CO2 fixation. The effect of glycerate on photosynthesis in the presence of bicarbonate was determined by measuring both photosynthetic O2 evolution and 14CO2 fixation at varying Pi concentrations. Low concentrations of glycerate (micro- to millimolar levels) prevented inhibition of photosynthesis by Pi. With 1 mM bicarbonate and pH 8.2, which is favorable for glycolate synthesis, maximum rates of photosynthesis were obtained at low Pi (25 microM), whereas strong inhibition of photosynthesis occurred at only 0.2 mM Pi. Addition of glycerate relieved the inhibition of photosynthesis by Pi, indicating the possible importance of glycerate metabolism in the chloroplast under photorespiratory conditions. The initiation of photosynthesis by glycerate at inhibitory Pi levels occurred with little reduction in the ratio of CO2 fixed/O2 evolved, and the main effect of glycerate was on carbon assimilation. While the basis for the beneficial effect of glycerate on CO2 assimilation under moderate to high Pi levels is uncertain, it may increase the concentration of 3-phosphoglycerate (PGA) in the chloroplast, and thus make conditions more favorable for induction of photosynthesis and reduction of PGA to triose phosphate.
Bicarbonates↗
Haemophilia and T lymphocyte subsets.
Number of circulating lymphocytes and T cell subsets were assessed in 13 boys with severe haemophilia and 12 age matched controls. There was no significant difference between the two groups. This conflicts with previous findings in adults where lymphopenia and changes in T cell subpopulations have been found frequently.
Antibodies, Monoclonal↗
Pseudo-AIDS.
Explore the source record for details and available documents.
Acquired Immunodeficiency Syndrome↗
Regulation of photosynthetic carbon metabolism. The effect of inorganic phosphate on stromal sedoheptulose-1,7-bisphosphatase.
The activation and steady-state kinetics of wheat chloroplast sedoheptulose-1,7-bisphosphatase at several concentrations of inorganic phosphate are examined. Inorganic phosphate competitively inhibits substrate binding to both the active and inactive forms of the enzyme and reduces the rate of enzyme activation. Modulation of the apparent Km of sedoheptulose-1,7-bisphosphatase and fructose-1,6-bisphosphatase for their substrates by inorganic phosphate is discussed in terms of the control of intermediate pool sizes in the reductive pentose phosphate pathway and of the flux of fixed carbon towards starch synthesis or export from the chloroplast.
Carbon↗
Adenine nucleotide status, phosphoglycerate reduction and photosynthetic phosphorylation in a reconstituted chloroplast system.
The concentrations of ADP and ATP were measured during illumination of a reconstituted chloroplast system to which NADP(+), 3-phosphoglycerate and ribose 5-phosphate were successively added. Their effects on photosynthetic oxygen evolution and on the concentrations of ATP and ADP are discussed in terms of the regulation of photosynthetic carbon assimilation.
Adenosine Diphosphate↗
The role of transmembrane solute flux in regulation of CO2 fixation in chloroplasts.
Explore the source record for details and available documents.
Biological Transport↗
Measurement of CO(2) and H(2)O Vapor Exchange in Spinach Leaf Discs : Effects of Orthophosphate.
A leaf chamber has been designed which allows the measurement of both CO(2) and water vapor exchange in Spinacia oleracea leaf discs. The center of the disc lies within a cylindrical gas chamber and its margins are enclosed within a cavity through which water or various metabolites can be pumped. In saturating light and normal atmospheres, the leaf discs have a relatively low resistance to H(2)O vapor transfer (r(w) = 1.87 seconds per centimeter) and can support high rates of photosynthesis for several hours. The abaxial surface of a disc had a higher resistance to water vapor transfer (r(w) = 3.22 seconds per centimeter) than the adaxial (r(w) = 2.45 seconds per centimeter) despite having a higher stomatal frequency (abaxial, 105/square millimeter; adaxial, 58/square millimeter). In 2% O(2), the discs required an internal concentration of CO(2) of 115 microliters per liter to support one-half of the maximal velocity of apparent photosynthesis (average value, 66 milligrams CO(2) per square decimeter per hour). In 20% O(2), the comparable values are 156 microliters per liter and 56 milligrams CO(2) per square decimeter per hour. In air, apparent photosynthesis saturated at intensities (750 microeinsteins per square meter per second) well below that of daylight but, when the internal CO(2) was raised to 700 to 900 microliters per liter, photosynthesis was not saturated even at daylight intensities (2025 microeinsteins per square meter per second). The distribution of Prussian blue crystals, formed after ferrocyanide feeding, showed that water entered the disc via the vasculature. When 25-minute pulses of orthophosphate were provided in the feeding solution, there were concentration-dependent increases in both r(w) and r(m) leading to inhibition of photosynthesis. The orthophosphate-dependent inhibitions were reversible.
Journal Article↗
Effects of mannose on photosynthetic gas exchange in spinach leaf discs.
When mannose is provided in the transpiration stream to spinach (Spinacia oleracea) leaf discs, a series of specific and nonspecific changes occur in CO(2) and H(2)O vapor exchange as a function of feeding time. The initial increases in apparent photosynthesis and transpiration are nonspecific effects due to osmotic changes leading to passive stomatal opening. The mannose-specific effects are: (a) time-dependent changes in the CO(2) concentration required for saturation; (b) complex kinetics of the inhibition of CO(2) assimilation dependent on CO(2) and O(2) concentrations and the duration of feeding (high CO(2) and low O(2) lead to rapid inhibitions of photosynthesis); (c) elimination of the capacity of 2% O(2) to stimulate photosynthesis; and (d) oscillations in the CO(2) exchange rate following transitions from 20% to 2% O(2). The mannose-specific effects are reversible by orthophosphate. The mannose-dependent changes in gas exchange are attributed to altered [ATP]/[ADP] ratios.
Journal Article↗
Modulation of NADP-Malate Dehydrogenase Activity in Maize Mesophyll Chloroplasts.
When intact mesophyll chloroplasts of Zea mays var Kelvedon Glory were illuminated, activation of NADP-malate dehydrogenase occurred. Activity declined rapidly on darkening. Light activation of the enzyme was very much greater in the presence of pyruvate ( approximately 10- to 20-fold) than with the electron acceptors 3-phosphoglycerate or oxaloacetate present ( approximately 2-fold). Following preillumination in the presence of pyruvate, addition of 3-phosphoglycerate, oxaloacetate, or nitrite substantially diminished the activity of NADP-malate dehydrogenase. In these circumstances, with pyruvate and 3-phosphoglycerate present, activity could be restored by the addition of nigericin or dihydroxyacetone phosphate. Nigericin also restored activity with both oxaloacetate and pyruvate present. The effect of nitrite was more marked in the presence of low concentrations of DCMU.These observations are discussed in terms of the dependence of enzyme activity upon the redox state of ferredoxin and electron carriers; the redox state of the latter was estimated by analysis of the DCMU-induced relaxation kinetics of chlorophyll fluorescence quenching in the presence of different substrates.
Journal Article↗
Simultaneous measurement of oxygen evolution and chlorophyll fluorescence from leaf pieces.
An apparatus is described which permits the simultaneous measurement of O(2) evolution and chlorophyll a fluorescence from illuminated discs or pieces of green leaves. O(2) is measured in the gas phase in a temperature-controlled chamber of approximately 5-milliliter capacity. Calibration is effected by injection of air through vents. Response time is approximately 1.5 seconds for O(2), and full scale deflection, in normal operating mode, is approximately 10 micromoles O(2). The apparatus may also be used to monitor fluorescence alone, in an open mode, in which gas is passed continuously through the chamber.
Journal Article↗
Simultaneous measurement of oscillations in oxygen evolution and chlorophyll a fluorescence in leaf pieces.
In spinach (Spinacia oleracea) and barley (Hordeum vulgare) leaves, chlorophyll a fluorescence and O(2) evolution have been measured simultaneously following re-illumination after a dark interval or when steady state photosynthesis has been perturbed by changes in the gas phase. In high CO(2) concentrations, both O(2) and fluorescence can display marked dampening oscillations that are antiparallel but slightly out of phase (a rise or fall in fluorescence anticipating a corresponding fall or rise in O(2) by about 10 to 15 seconds). Infrared gas analysis measurements showed that CO(2) uptake behaved like O(2) evolution both in the period of oscillation (about 1 minute) and in its relation to fluorescence. In the steady state, oscillations were initiated by increases in CO(2) or by increases or decreases in O(2). Oscillations in O(2) or CO(2) did not occur without associated oscillations in fluorescence and the latter were a sensitive indicator of the former. The relationship between such oscillations in photosynthetic carbon assimilation and chlorophyl a fluorescence is discussed in the context of the effect of ATP or NADPH consumption on known quenching mechanisms.
Journal Article↗
Huntington's chorea in South Wales: mutation, fertility, and genetic fitness.
A study of mutation, biological fitness, and patterns of family building in Huntington's chorea has been carried out, based on a previously reported population study of the disorder in South Wales. No unequivocal new mutation was identified among 101 kindreds containing 418 affected persons, which supports the extreme rarity of mutation in this disorder. Increased values of fertility and fitness were found, both in relation to unaffected relatives and to the general population of the area. The proportion of unmarried persons and pattern of family building was comparable in affected and unaffected subjects, and no correlation with age at onset or mode of clinical presentation could be found.
Adult↗