Impact of a public cholesterol screening program

The National Cholesterol Education Program (NCEP) has endorsed physician case finding as the primary method to detect individuals with elevated cholesterol levels. Despite this recommendation, promotional and for-profit public screening programs have flourished. We surveyed participants of a mall-based cholesterol screening program 1 year after their screening. Sixty-four percent of those screened had not previously known their cholesterol levels. Those who were newly screened were less likely to benefit from this testing than the general public, since they were older (mean age, 55.3 years), more likely to be female (67.4%), and nonsmokers (88%). Screenees had excellent recall of their cholesterol level (mean absolute reporting error, 0.24 mmol/L [9 mg/dL]) and a good understanding of cholesterol as a coronary heart disease risk. Those with elevated cholesterol levels reported high distress from screening but no reduction in overall psychosocial well-being and an actual decrease in absenteeism. Only 53.7% of all who were advised to seek follow-up because of an elevated screening value had done so within the year following the screening program. However, of those with values greater than 6.2 mmol/L (240 mg/dL), 68% had sought follow-up. Many of those who participate in public screening programs have been previously tested, fall into low-benefit groups, or fail to comply with recommended follow-up. We therefore conclude that cholesterol screening programs of the type now commonly offered are unlikely to contribute greatly to the national efforts to further reduce coronary heart disease.

Genetic variability for esterase enzyme in Onobrychis species

Understanding polymorphism at the enzyme level is basic to its use in population and genetic studies. However, no such information is available on the variability among different sainfoin (Onobrychis) species. Therefore, our objective was to study the existence of genetic polymorphism for esterase in 17 Onobrychis species and three cultivars of O. viciifolia Scop. Three regions of banding were observed in all the materials tested, with the number of bands varying from 0 to 3, 3 to 14, and 1 to 2 bands in each of these zones, which have been designated EST1, EST2, and EST3 respectively. All the materials studied had unique banding patterns, the only common feature being that all of them, except one species, had isozyme 1. Identification was possible only for four species (O. iberica, O. kachetica, O. transcaucasica, and O. bieberstenii) and one cultivar ('Nova') based on the banding patterns. Large diversity was evident from the wide range of percent similarity values (0%-79%). Subsequent studies should be directed in using these isozyme banding patterns as markers to the desirable agronomic and quality traits of different germplasm lines.

Thermal Dependence of the Apparent K(m) of Glutathione Reductases from Three Plant Species

The thermal dependencies of the apparent K(m) of the glutathione reductases from spinach (Spinacia oleracea L.) corn (Zea mays L.), and cucumber (Cucumis sativus L.) were determined. The apparent K(m) of the enzymes were found to vary up to 9-fold between 12.5 and 45 degrees C. Values of the apparent K(m) in excess of 200% of the observed minimum are suggested to be detrimental to the normal function of the enzyme. We propose the term "thermal kinetic window" to describe to the range of temperatures over which the apparent K(m) of the glutathione reductase is within 200% of its minimum and suggest that it may be a useful indicator of the limits of thermal stress for a given species. The thermal kinetic windows determined in this study are: <16 degrees C for spinach, 23 to 32 degrees C for corn, and 35 to 41 degrees C for cucumber.

Variation among Species in the Temperature Dependence of the Reappearance of Variable Fluorescence following Illumination

The relationship between the thermal dependence of the reappearance of chlorophyll variable fluorescence following illumination and temperature dependence of the apparent Michaelis constant (K(m)) of NADH hydroxypyruvate reductase for NADH was investigated in cool and warm season plant species. Brancker SF-20 and SF-30 fluorometers were used to evaluate induced fluorescence transients from detached leaves of wheat (Triticum aestivum L. cv TAM-101), cotton (Gossypium hirsutum L. cv Paymaster 145), tomato (Lycopersicon esculentum cv Del Oro), bell pepper (Capsicum annuum L. cv California Wonder), and petunia (Petunia hybrida cv. Red Sail). Following an illumination period at 25 degrees C, the reappearance of variable fluorescence during a dark incubation was determined at 5 degrees C intervals from 15 degrees C to 45 degrees C. Variable fluorescence recovery was normally distributed with the maximum recovery observed at 20 degrees C in wheat, 30 degrees C in cotton, 20 degrees C to 25 degrees C in tomato, 30 to 35 degrees C in bell pepper and 25 degrees C in petunia. Comparison of the thermal response of fluorescence recovery with the temperature sensitivity of the apparent K(m) of hydroxypyruvate reductase for NADH showed that the range of temperatures providing fluorescence recovery corresponded with those temperatures providing the minimum apparent K(m) values (viz. the thermal kinetic window).

Chromosomal location of genes controlling heat shock proteins in hexaploid wheat

The low molecular weight heat shock protein (HSP) profiles of the hexaploid wheat cultivar "Chinese Spring" and its ditelosomic series were characterized by isoelectric focusing polyacrylamide gel electrophoresis of denatured in vivo radiolabeled proteins. Comparisons of the ditelosomics (DTs) to the euploid "Chinese Spring" enabled the assignment of genes controlling 9 of the 13 targeted HSPs to seven chromosome arms. There did not appear to be a genome-specific action in the regulation of expression of these HSPs. There did appear to be a higher frequency of controlling genes within homoeologous DT lines 3, 4 and 7. Significant variation in protein quantity was evident among the DT lines for some HSPs, while other HSPs were remarkably stable in their expression across all DTs examined. The results are useful in identifying specific DT lines for the investigation of HSP functions in hexaploid wheat.

Heat shock protein synthesis and thermal tolerance in wheat

Plants respond to high temperature stress by the synthesis of an assortment of heat shock proteins that have been correlated with an acquired thermal tolerance to otherwise lethal temperatures. This study was conducted to determine whether genotypic differences in acquired thermal tolerance were associated with changes in the pattern of heat shock protein synthesis. The pattern of heat shock protein synthesis was analyzed by (35)S-methionine incorporation in wheat (Triticum aestivum L.) varieties exhibiting distinct levels of acquired thermal tolerance. Significant quantitative differences between the cultivars Mustang and Sturdy were observed in the HSP exhibiting apparent molecular weights of 16, 17, 22, 26, 33, and 42 Kilodaltons. Genotypic differences in the synthesis of the small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase were observed at 34 degrees C. Two-dimensional electrophoretic analysis revealed unique proteins (16, 17, and 26 kilodaltons) in the thermal tolerant variety Mustang that were absent in the more thermal sensitive variety Sturdy. These results provide a correlation between the synthesis of specific low molecular weight heat shock proteins and the degree of thermal tolerance expressed following exposure to elevated temperatures.

A clinician's guide to the office measurement of cholesterol

The office laboratory has the potential to be an ideal setting for cholesterol testing if accurate test results are achieved. This study describes the performance of three office chemistry analyzers (Abbott Vision, Boehringer-Mannheim Reflotron, and Kodak Ektachem DT60 Analyzer) in the measurement of cholesterol. The accuracy of these instruments was assessed by testing aliquots of 84 plasma specimens and comparing these results with values obtained in one of the National Heart, Lung, and Blood Institute's Lipid Research Clinic laboratories. To evaluate instrument precision, results from each of the three instruments were compared with the cholesterol standards recently released by the College of American Pathologists. When operated according to the manufacturers' recommended procedures, each of the three instruments demonstrated analytic capabilities that met the current accuracy and precision goals established by the National Cholesterol Education Program. Analytic issues that are pertinent to the clinician's role as both the office laboratory director and the test interpreter are reviewed.

Plant Morphological and Biochemical Responses to Field Water Deficits: III. Effect of Foliage Temperature on the Potential Activity of Glutathione Reductase

Activity of glutathione reductase has been related to stress tolerance; however, these enzyme assays are generally conducted at 25 degrees C. Foliage temperature varies greatly in the field in response to soil water availability and ambient conditions and this may affect enzyme response. This study was conducted to determine the effect of changing foliage temperature on glutathione reductase activity of wheat under field conditions. Wheat leaf glutathione reductase was purified and the temperature response of the enzyme was determined at 2.5 degrees C intervals between 12.5 and 45 degrees C. These data, in conjunction with continuous measurements of field-grown wheat foliage temperatures, were used to compare the temperature-related changes in potential glutathione reductase activities in water stressed and control plants. Assuming saturating substrate levels, the results indicate that early in the season the daily potential enzyme activity of the irrigated and stressed plants could never have reached the daily activity predicted from the 25 degrees C (room temperature) measurements. Later in the season, the daily potential activity of the irrigated plants was lower, and the daily potential activity of the stressed plants was higher, than the activities predicted from the 25 degrees C determinations. These results suggest that a better understanding of the regulation of plant metabolism will be obtained by linking continuous temperature measurements of plant foliage with enzyme responses to temperature.

Studies on genetic male-sterile soybeans : v. Effects of male-sterility on the function and glycerolipid composition of chloroplast thylakoids

Soybean (Glycine max L. Merr.) germplasm, isogenic except for loci controlling male sterility (ms(1)), was utilized to study the effects of reproductive development on certain aspects of photosynthesis. Plants were sampled at various times between flowering (77 days after transplanting) and maturity (147 days after transplanting). During that period photosynthetic rates declined more rapidly in the male-sterile genotypes than male-fertile genotypes; and after 105 days, the sterile genotypes maintained low but relatively constant carbon exchange rates. The decline of leaf photosynthesis in the male-sterile genotype occurred concomitantly with an inhibition of the photosynthetic electron transport chain associated with photosystem II. Changes in photosystem I activities, cytochrome f levels, and chlorophyll a/b ratios per se were not responsible for the decline in whole leaf photosynthesis. These conditions were independent of the source of nitrogen nutrition. Lipid analyses of the thylakoids revealed that a loss of phosphatidylglycerol was highly correlated with the inhibition of photosystem II activity. These results suggested a relation between the decline in leaf carbon exchange and the decline in photosynthetic electron transport activity.

Plant Morphological and Biochemical Responses to Field Water Deficits : II. Responses of Leaf Glycerolipid Composition in Cotton

The effects of water deficits on leaf glycerolipid composition were analyzed in two photoperiodic strains of field grown cotton (Gossypium kirsutum L.) that differ in sensitivity to drought. Leaves from plants grown under dryland conditions exhibited increased dry weight and specific leaf weight. The average midday leaf water potential in the dryland treatment decreased to -1.9 and -2.4 megapascals, respectively, for the T25 and T185 genotypes. Total leaf lipid content of plants exposed to dryland conditions was 5.9 and 7.5% of leaf dry weight for strain T25 and T185, respectively. The difference in leaf lipid content between these genotypes was caused by water deficits and was attributed to loss of both phospholipids and glycolipids in strain T25. There was no apparent loss of phospholipids due to water deficits in the T185 genotype; however, a significant loss of glycolipids was partially compensated by a 2-fold increase in triacylglycerol. No change in triacylglycerol was found between treatments in T25 leaves. Water deficit caused a significant decline in the relative degree of acylunsaturation in phospholipids and glycolipids from both genotypes; however, the double bond index for triacylglycerol increased in both genotypes. It is believed that the observed responses of leaf lipid composition to dryland conditions may be an additional criterion for characterization and selection of new drought-tolerant cotton genotypes.

Effect of Osmotic Stress on Ion Transport Processes and Phospholipid Composition of Wheat (Triticum aestivum L.) Mitochondria

The effect of osmotic stress on wheat (Triticum aestivum L.) mitochondrial activity and phospholipid composition was investigated. Preliminary growth measurements showed that osmotic stress (-0.25 or -0.5 megapascal external water potential) inhibited the rate of shoot dry matter accumulation while root dry matter accumulation was less sensitive. We have determined that differences in sensitivity to osmotic stress existed between tissues at the mitochondrial level. Mitochondria isolated from roots or shoots of stressed seedlings showed respiratory control and ADP/O ratios similar to control seedlings which indicates that stressed mitochondria were well coupled. However, under passive swelling conditions in a KCl reaction mixture, the rate and extent of valinomycin-induced swelling of shoot mitochondria were increased by osmotic stress while root mitochondria were largely unaffected. Active ion transport studies showed efflux transport by stressed-shoot mitochondria to be partially inhibited since mitochondrial contraction required the addition of N-ethylmaleimide or nigericin. Efflux ion transport by root mitochondria was not inhibited by osmotic stress which indicates that stress-induced changes in ion transport were largely limited to shoot mitochondria. Characterization of mitochondrial fatty acid and phospholipid composition showed an increase in the percentage of phosphatidylcholine in stressed shoot mitochondria compared to the control. Mitochondrial fatty acid composition was not markedly altered by stress. No significant changes in either the phospholipid or fatty acid composition of stressed root mitochondria were observed. Hence, these results suggest that a tissue-specific response to osmotic stress exists at the mitochondrial level.

Effects of water stress on the organic Acid and carbohydrate compositions of cotton plants

Two photoperiodic cotton (Gossypium hirsutum L.) strains (T185 and T466) which had been empirically selected because of poor performance and two strains (T25 and T256) selected because of enhanced performance under field water stress were evaluated for stress-induced changes in their organic acids and carbohydrates. Profiles and quantitation of organic acids and carbohydrates from aqueous extractions of cotton leaf tissue were determined by high performance liquid chromatography. In all cases, the water-stressed plants showed two to five times greater amounts of organic acids and carbohydrates over the values determined for the irrigated samples. Under stress, sucrose accumulation was observed in wilting strains (poor performers) probably related to rate of translocation out of the leaf. The most dramatic response to water stress was the accumulation of citric acid in strains T25 and T256 as compared to T185 and T466. Citric/malic acid ratios for both the irrigated and water-stressed samples of T25 and T256 were twice those of T185 and T466.

Thallium circumferential profiles in the detection of coronary artery disease--assessment by receiver operating characteristic curve analysis

Thallium uptake and redistribution in the myocardium was quantitated using circumferential activity profiles. The profiles were determined from images in the LAO 35, LAO 70 and anterior views, obtained after peak exercise and after 3-4 h redistribution. A retention curve was constructed from these profiles, displaying the redistribution profile as a fraction of the stress profile. Normal values were obtained from 21 normal patients and compared to the images from 68 patients suspected of having coronary artery disease (CAD). Of the latter, 20 had normal/non-significant CAD and 48 had 70% or greater stenosis of one or more vessels on coronary angiography. Several methodological variations were examined: calculation of the profiles using the peak or average counts around the ventricle, uniform or interpolative background subtraction, normalisation of the profiles to their peak or mean counts. Receiver operating characteristic (ROC) curves were generated for profiles calculated using these variations and compared with the ROC curves obtained by visual interpretation of both analogue and computer-enhanced images by two experienced observers. The uniform background subtraction method was found to be better than the interpolative method, and normalisation to the mean of each curve was preferable to normalisation to the peak. ROC curves using profiles calculated using the peak myocardial counts were identical to the ROC curves from profiles using the average counts, but the operating points on the two curves differed. Computer enhancement of the digital images resulted in increased sensitivity for CAD without loss of specificity when compared to the interpretation of the analogue images. The circumferential profiles were found to provide a further increase in sensitivity and were highly reproducible.(ABSTRACT TRUNCATED AT 250 WORDS)

Plant morphological and biochemical responses to field water deficits: I. Responses of glutathione reductase activity and paraquat sensitivity

The effects of water deficits on plant morphology and biochemistry were analyzed in two photoperiodic strains of field-grown cotton (Gossypium hirsutum L.). Plants grown under dryland conditions exhibited a 40 to 85% decrease in leaf number, leaf area index, leaf size, plant height, and total weight per plant. Gross photosynthesis decreased from 0.81 to 0.47 milligram CO(2) fixed per meter per second and the average midday water, osmotic, and turgor potentials decreased to -2.1, -2.4, and 0.3 megapascals, respectively.There was a progressive increase in glutathione reductase activity and in the cellular antioxidant system in the leaves of stressed plants compared to the irrigated controls. The stress-induced increases in enzyme activity occurred at all canopy positions analyzed.Irrigation of the dryland plots following severe water stress resulted in a 50% increase in leaf area per gram fresh weight in newly expanded leaves of both strains over the leaves which had expanded under the dryland conditions. Paraquat resistance (a relative measure of the cellular antioxidant system) decreased in the strain T25 following irrigation. Glutathione reductase activities remained elevated in the T25 and T185 leaves which were expanded fully prior to irrigation and in the leaves which expanded following the irrigation treatment.

A combined procedure for 99mTc aerosol ventilation and perfusion imaging

For several years, radioaerosols have been successfully used to provide detailed images of regional ventilation to aid in the differential diagnosis of pulmonary embolism. It has been widely advocated that the ventilation images should follow the perfusion scan and that the amount of aerosol deposited in the patient's lungs should be three times greater than the perfusion dose. We employed an alternative approach which avoided the deposition of an unpredictable amount of aerosol in individual patients. The aerosol study was performed first, and the activity of the microspheres used for the perfusion images was then tailored to the actual amount of aerosol which the patient had retained. This allowed a microsphere/aerosol activity ratio of 10:1 to be readily achieved, thus successfully masking the ventilation pattern by the perfusion activity. The faster biological clearance of 99mTc-DTPA aerosol from the lung fields, as compared to 99mTc-sulphur-colloid aerosol, allowed higher initial activities to be deposited in the lungs, thus enabling a high-resolution collimator to be used. When the perfusion study was delayed by 1 h (one effective half-life for the 99mTc-DTPA aerosol), it was not necessary to increase the perfusion activity required to mask the ventilation image.

Accumulation of heat shock proteins in field-grown cotton

Cotton (Gossypium hirsutum L.) plants grown under field water deficits exhibited an 80 to 85% reduction in leaf area index, plant height, and dry matter accumulation compared with irrigated controls. Midday photosynthetic rates of dryland plants decreased 2-fold, and canopy temperatures increased to 40 degrees C at 80 days after planting compared with canopy temperatures of 30 degrees C for irrigated plants. Leaves from dryland plants which had exhibited canopy temperatures of 40 degrees C for several weeks accumulated stainable levels of polypeptides with apparent molecular weights of 100, 94, 89, 75, 60, 58, 37, and 21 kilodaltons. These polypeptides did not accumulate in leaves from irrigated plants.Addition of [(35)S]methionine to leaves of growth chamber-grown cotton plants and subsequent incubation at 40 degrees C for 3 hours radiolabeled polypeptides with molecular weights similar to those that accumulate in dryland cotton leaves. These data suggest that the proteins which accumulate in water-stressed cotton leaves at elevated temperatures (40 degrees C) are heat shock proteins and that these proteins can accumulate to substantial levels in field-stressed plants.

Effect of water stress on the chloroplast antioxidant system: I. Alterations in glutathione reductase activity

The effect of water stress on glutathione reductase and catalase activities was evaluated in leaf blades of field-grown winter wheat (Triticum aestivum L.). Wheat was sown at two seeding rates under both irrigated and dryland conditions. Flag leaves from dryland plants sown at 60 kilograms/hectare showed no change in either glutathione reductase or catalase activities per unit leaf area, while leaves from the basal portion of the canopy exhibited a 273% increase in glutathione reductase activity and a 60% increase in catalase activity. Glutathione reductase activity in dryland plants sown at 120 kilograms/hectare increased 25% in flag leaves and 225% in basal leaves. No change in catalase activity was observed in either flag or basal leaves from these same plants. The increase in glutathione reductase activity in response to water stress was observed when activity was expressed on either a per unit leaf area, protein, or chlorophyll basis. No change in catalase activity was detected when enzyme activity was expressed on a protein basis.

Separation Procedure and Partial Characterization of Two NAD(P)H Dehydrogenases from Cauliflower Mitochondria

A procedure was developed to separate and partially purify two NAD(P)H dehydrogenases from the inner membrane of cauliflower (Brassica oleracea L.) mitochondria. The procedure used Triton X-100 extraction followed by (NH(4))(2)SO(4) precipitation and gel filtration (Sepharose G-200 column) chromatography. The first dehydrogenase fraction (which eluted in the column void volume) was specific for NADH, was stimulated by KCl addition, and was inhibited by acidic pH, sulfhydryl reagents, and elevated temperature. This fraction contained two major polypeptides with molecular weights of about 57,600 and 32,600 daltons. The fraction exhibited electron paramagnetic resonance (EPR) signals associated with a reduced (ferredoxin-type) iron-sulfur center.A second dehydrogenase fraction was eluted from the column after removal of the first dehydrogenase. This fraction oxidized NADH and NADPH, was stable at high temperatures, and had a broad pH optima that ranged from 6.0 to 7.8. Although it was relatively insensitive to additions of monovalent and divalent cations, its activity was sensitive to incubation with sulfhydryl reagents. The second dehydrogenase fraction contained five major polypeptides and lacked the iron-sulfur protein EPR signals shown by the first dehydrogenase fraction.The dehydrogenase fractions represent three potential sites of entry to mitochondrial electron transport; two sites for NADH and a third site for NADPH.

Studies on Genetic Male-Sterile Soybeans : III. The Initiation of Monocarpic Senescence

Soybean (Glycine max [L.] Merr.) germplasm, isogenic except for loci controlling male-sterility (ms(1)) and nodulation (rj(1)) was utilized to investigate the effects of reproductive tissue development and nitrogen source on the initiation of monocarpic senescence. The experimental genotypes (Ms(1)Rj(1), Ms(1)rj(1), ms(1)Rj(1), and ms(1)rj(1), were selected from a cross between N69-2774 and N59-5259, and were inbred to the F(5) generation. Green-house-grown plants were collected during the period of flowering (77 days after transplanting) until maturity (147 days after transplanting). Leaf tissues from the respective genotypes were analyzed at the various harvest dates for RNA, phenolic, and chlorophyll concentrations; acid protease activity; polypeptide banding patterns of chloroplast thylakoids; and chloroplastic ultrastructure.Regardless of nitrogen source, total chlorophyll concentrations declined between 77 and 119 days after transplanting, resulting in a 40% loss of chlorophyll per square centimeter in all genotypes. Leaf chlorophyll levels continued to decline at a constant rate in male-fertile genotypes, but remained at a constant level (26 micrograms chlorophyll per square centimeter) in male-sterile genotypes, for the remainder of the study. With increased leaf age, a gradual disruption of thylakoid structures was observed, particularly in chloroplasts from the male-fertile genotypes. Chloroplasts from the male-sterile genotypes appeared to lose starch grains but increased their number of chloroplastic lipid bodies with leaf aging. These data suggest that monocarpic senescence in soybeans was initiated at or before flowering. Although reproductive tissue development probably augmented the process, the response attributed to seed formation was not apparent until the mid-pod fill stage (119 days after transplanting). All genotypes had similar changes in other cellular components that are recognized as indicators of plant senescence regardless of whether the plants produced seed.

Surface-polaritonlike waves guided by thin, lossy metal films

Surface-plasmon polaritons guided by thin, lossy metallic films bounded by dissimilar dielectric media are investigated. New solutions to the dispersion relation are found, representing waves that are leaky (radiative) in one of the dielectrics. The new waves are interpreted in terms of the coupling of a damped surface plasmon at one interface with continuum modes at the other. Their excitation by end-fire coupling techniques is suggested.

Biochemical Changes that Occur during Senescence of Wheat Leaves : I. Basis for the Reduction of Photosynthesis

Changes in activities of photosynthetic enzymes and photochemical processes were followed with aging of vegetative and flag leaves of wheat (Triticum aestivum L. cv Roy). Activities of stromal enzymes began to decline prior to photochemical activities. In general, total soluble protein and the activities of ribulose-1,5-bisphosphate carboxylase and NADP-triose-phosphate dehydrogenase declined in parallel and at an earlier age than leaf chlorophyll (Chl), leaf photosynthesis, and photosynthetic electron transport activity. Leaves appeared to lose whole chloroplasts as opposed to a general degradation of all chloroplasts based on three lines of evidence: (a) electron transport activity calculated on an area basis declined much earlier than the same data expressed on a Chl basis; (b) Chl content per chloroplast was similar for mature and senescent tissue; and (c) the absorbance at 550 nanometers (light scattering) per unit of Chl remained essentially constant until the end of senescence. Chloroplasts did, however, undergo some modifications before they were lost (e.g. loss of stromal enzyme activities), but the reduction in leaf photosynthesis was apparently caused by a loss of whole chloroplasts.

Succinate dehydrogenase : a partial purification from mung bean hypocotyls and soybean cotyledons

A procedure was developed for the partial purification of succinate dehydrogenase from mung bean (Vigna radiata L.) hypocotyls and soybean (Glycine max [L] Merr. v. Ransom) cotyledons. The procedure utilized a Triton X-100 extraction followed by ammonium sulfate precipitation. The final fraction was enriched in two polypeptides with approximate molecular weights of 67,000 and 30,000 daltons, exhibited a pH optima of 7.0 to 7.5, contained a b-type cytochrome, and exhibited the characteristic ferredoxin-type and high potential iron-sulfur protein-type electron paramagnetic resonance signals reported for the iron-sulfur centers of mammalian succinate dehydrogenase. Inhibition constants of 1.15 and 24.6 micromolar for oxaloacetate and malonate, respectively, were obtained.

Characterization of Chloroplasts Isolated from Triazine-Susceptible and Triazine-Resistant Biotypes of Brassica campestris L

Chloroplasts isolated from triazine-susceptible and triazine-resistant biotypes of Brassica campestris L. were analyzed for lipid composition, ultrastructure, and relative quantum requirements of photosynthesis. In general, phospholipids, but not glycolipids in chloroplasts from the triazine-resistant biotype had a higher linolenic acid concentration and lower levels of oleic and linoleic fatty acids, than chloroplasts from triazine-susceptible plants. Chloroplasts from the triazine-resistant biotype had a 1.6-fold higher concentration of t-Delta3-hexadecenoic acid with a concomitantly lower palmitic acid concentration in phosphatidylglycerol. Phosphatidylglycerol previously has been hypothesized to be a boundary lipid for photosystem II. Chloroplasts from the triazine-resistant biotype had a lower chlorophyll a/b ratio and exhibited increased grana stacking. Light-saturation curves revealed that the relative quantum requirement for whole chain electron transport at limiting light intensities was lower for the susceptible biotype than for the triazine-resistant biotype. Although the level of the chlorophyll a/b light-harvesting complex associated with photosystem II was greater in resistant biotypes, the increased levels of the light-harvesting complex did not increase the photosynthetic efficiency enough to overcome the rate limitation that is inherited concomitantly with the modification of the Striazine binding site.

Rectification and enhancement of three severely distorted images of Jupiter's north polar region

A number of high-resolution images of Jupiter's northern hemisphere were received from the imaging photo-polarimeter (IPP) aboard Pioneer 11 in 1974. Erratic scanning of the IPP caused severe distortions in three scientifically important images, which until now have never been satisfactorily restored. We report new rectification and enhancement techniques, implemented on up-to-date image processing hardware, yielding images of sufficient quality to enable full scientific exploitation of the photometric data.

Diagnosis of old anterior myocardial infarction in emphysema with poor R wave progression in anterior chest leads

The electrocardiograms of patients with emphysema may suggest associated old anterior myocardial infarction. Sixteen patients with the physiological characteristics of emphysema were studied, who also showed poor R wave progression in the anterior chest leads, so that RV3 was less than or equal to 4 mm. A thallium-201 cardiac scan consistent with previous anterior (septal) myocardial infarction was present in seven patients. In these patients there was no significant increase in RV3 amplitude when recorded one interspace below the conventional site. In the nine patients with a thallium-201 cardiac scan negative for old anterior myocardial infarction, RV3 amplitude increased from 2.2 +/- 0.4 mm to 6.4 +/- 1.2 mm. Patients with or without associated old anterior myocardial infarction could be better diagnosed by consideration of RV3 amplitude as recorded from one interspace lower, as compared with conventional electrode placement. All five patients with RV3 (lower interspace) less than 2 mm had associated anterior infarction, and all seven patients with RV3 (lower interspace) greater than 3 mm did not. This simple manoeuvre is recommended in patients with emphysema and an electrocardiogram suggestive of old anterior myocardial infarction.

Comparison of bending losses in integrated optical circuits

We present measured losses in waveguide sections that are caused by connecting two parallel noncollinear straight waveguides and compare the results with theory. Two different offset transitions are considered, one composed of a straight section with sharp corner bends and the other exhibiting a smooth S-shaped transition. These two types of transitions are compared with each other to determine when each has the lowest loss. In general, sharp corner bends are preferred for small offsets, whereas larger offsets exhibit lower loss with the S-bend design. The experimental results were measured for 3-microm-wide Ti-diffused LiNbO 3 single-mode waveguides.

A developmental study of photosystem I peripheral chlorophyll proteins

An isolated "native" photosystem I (PSI complex) contains three spectral populations of chlorophyll a antennae (Mullet, Burke, Arntzen 1980 Plant Physiol 65: 814-822). It was hypothesized that nearly one-half of these antennae ( approximately 45 Chl/P(700)) are associated with polypeptides of 21,500 to 24,500 daltons. The present study utilizes two developmental systems to verify this association.Chloroplasts were isolated from a Chl b-less barley mutant and from partially-developed cucumber cotyledons (greened under intermittent illumination [ImL] chloroplasts) and were compared to control chloroplasts isolated from wild-type barley and mature cucumber. Both the mutant and ImL chloroplasts exhibited a long wavelength fluorescence maximum at 724 nanometers at 77 K as compared to 735 to 738 nanometers emission maximum in the respective controls. Both the mutant and ImL chloroplasts were deficient in polypeptides of 21,500 to 24,500 daltons which were present in control membranes and in PSI fractions isolated from control membranes. In light-induced maturation of the ImL cucumbers, the synthesis of polypeptides in the 21,500 to 24,500 molecular weight range paralleled the appearance of PSI Chl species fluorescing at long wavelength ( approximately 735 nm).The PSI spectral properties of the control membranes were retained in isolated PSI particles containing 100 to 120 Chl/P(700) (PSI-110). Detergent extraction of PSI-110 removed polypeptides of 21,500 to 24,500 daltons plus approximately 45 Chl/P(700). The antennae-depleted PSI particle mimics PSI properties exhibited by incompletely differentiated mutant or ImL chloroplasts.

Chlorophyll proteins of photosystem I

Data are presented which suggest the existence of a light-harvesting pigment-protein complex which is functionally and structurally associated with photosystem I (PSI) reaction centers. These observations are based on techniques which allow isolation of PSI using minimal concentrations of Triton X-100. Properties of density and self aggregation allowed purification of a "native" PSI complex.The isolated PSI particles appear as 106 A spherical subunits when viewed by freeze fracture microscopy. When incorporated into phosphatidyl choline vesicles, the particles lose self-aggregation properties and disperse uniformly within the lipid membrane.The isolated PSI preparation contains 100 +/- 10 chlorophylls/P(700) (Chl a/b ratio greater than 18); this represents a recovery of 27% of the original chloroplast membrane Chl. These particles were enriched in Chl a forms absorbing at 701 to 710 nm. Chl fluorescence at room temperature exhibited a maximum at 690 nm with a pronounced shoulder at 710 nm. At 77 K, peak fluorescence emission was at 736 nm; in the presence of dithionite an additional fluorescence maximum at 695 nm was obtained at 77 K. This dual fluorescence emission peak for the PSI particles is evidence for at least two Chl populations within the PSI membrane subunit. The fluorescence emission observed at 695 nm was identified as arising from the core of PSI which contains 40 Chl/P(700) (PSI-40). This core complex, derived from native PSI particles, was enriched in Chl a absorbing at 680 and 690 nm and fluorescing with maximal emission at 694 nm at 77 K. PSI particles consisting of the PSI core complex plus 20 to 25 Chl antennae (65 Chl/P(700)) could also be derived from native PSI complexes. These preparations were enriched in Chl a forms absorbing at 697 nm and exhibited a 77 K fluorescence emission maximum at 722 nm.A comparison of native PSI particles which contain 110 Chl/P(700) (PSI-110) and PSI particles containing 65 Chl/P(700) (PSI-65) provides evidence for the existence of a peripheral Chl-protein complex tightly associated in the native PSI complex. The native PSI subunits contain polypeptides of 22,500 to 24,500 daltons which are not found in the PSI-65 or PSI-40 subfractions. It is suggested that these polypeptides function to bind 40 to 45 Chl per structural complex, including the Chl which emits fluorescence at 736 nm.A model for the organization of Chl forms is presented in which the native PSI membrane subunit consists of a reaction center core complex plus two regions of associated light-harvesting antennae. The presence of energy "sinks" within the antennae is discussed.

Imaging Photopolarimeter on Pioneer Saturn

An imaging photopolarimeter aboard Pioneer 11, including a 2.5-centimeter telescope, was used for 2 weeks continuously in August and September 1979 for imaging, photometry, and polarimetry observations of Saturn, its rings, and Titan. A new ring of optical depth < 2 x 10(-3) was discovered at 2.33 Saturn radii and is provisionally named the F ring; it is separated from the A ring by the provisionally named Pioneer division. A division between the B and C rings, a gap near the center of the Cassini division, and detail in the A, B, and C rings have been seen; the nomenclature of divisions and gaps is redefined. The width of the Encke gap is 876 +/- 35 kilometers. The intensity profile and colors are given for the light transmitted by the rings. A mean particle size less, similar 15 meters is indicated; this estimate is model-dependent. The D ring was not seen in any viewing geometry and its existence is doubtful. A satellite, 1979 S 1, was found at 2.53 +/- 0.01 Saturn radii; the same object was observed approximately 16 hours later by other experiments on Pioneer 11. The equatorial radius of Saturn is 60,000 +/- 500 kilometers, and the ratio of the polar to the equatorial radius is 0.912 +/- 0.006. A sample of polarimetric data is compared with models of the vertical structure of Saturn's atmosphere. The variation of the polarization from the center of the disk to the limb in blue light at 88 degrees phase indicates that the density of cloud particles decreases as a function of altitude with a scale height about one-fourth that of the gas. The pressure level at which an optical depth of 1 is reached in the clouds depends on the single-scattering polarizing properties of the clouds; a value similar to that found for the Jovian clouds yields an optical depth of 1 at about 750 millibars.

Analysis of the Light-harvesting Pigment-Protein Complex of Wild Type and a Chlorophyll-b-less Mutant of Barley

we have compared chloroplast lamellae isolated from a chlorophyll-b-less mutant and wild type barley (Hordeum vulgare). The results demonstrate that: (a) one of the two major polypeptides comprising the lightharvesting complex (LHC) is present in the chlorophyll-b-less mutant; (b) higher cation concentrations are required to maintain grana stacks in the mutant; and (c) cation effects on excitation energy distribution are present in the chlorophyll-b-less mutant but are reduced in amount and are dependent on higher concentrations of cations.We interpret these data to support the concept that the LHC mediates cation-induced grana stacking and cation regulation of excitation energy distribution between photosystems I and Ii in chloroplast lamellae. A partial LHC complement in the mutant alters the quantitative cation requirement for both phenomena, but not the over-all qualitative response.

Histochemical Evidence for the Occurrence of Oligomycin-sensitive Plasmalemma ATPase in Corn Roots

A cytochemical study has been made on the localization of ATPase activity in corn (Zea mays L.) roots. Light microscopy shows washing for 4 hours to increase the general ATPase activity in the peripheral layers of the root cortex; oligomycin and N,N-dicyclohexylcarbodiimide inhibit this activity, oligomycin being more effective. Ultrastructural studies of ATPase location show oligomycin treatment to inhibit both mitochondrial and plasmalemma ATPase, but only in the epidermis and outer cortex. Studies with lipid-soluble dyes indicate that oligomycin might not penetrate very deeply into root tissue in the time span of these experiments. It is suggested that the strong inhibition of ion absorption by oligomycin without a corresponding decline in ATP content is probably due to inhibition of ion absorption in the peripheral cell layers, thus limiting the supply of ion for symplastic transport to the uninhibited tissues.

Auxin Has No Effect on Modification of External pH by Soybean Hypocotyl Cells

The cellular adjustment of the pH of the external environment of soybean (Glycine max) hypocotyl elongating cells, frequently assumed to be hydrogen ion secretion when the pH is lowered, is unaffected by auxin. These elongating cells actively adjust the external hydrogen ion concentration (from any pH in the range of 4-8) to pH 5.4 + 0.2. This pH adjustment occurs in a medium which does not contain potassium. Growth-optimum auxin concentrations have no effect on cellular pH adjustment of the external medium, whether added at the beginning of the experiment or after the equilibrium pH is attained. The pH adjustment by the cells occurs rapidly and in spite of the presence of a cuticle.

Cytochemical demonstration of malate synthase and glycolate oxidase in microbodies of cucumber cotyledons

The cytochemical localizations of malate synthase (glyoxysomal marker) and glycolate oxidase (peroxisomal marker) have been examined in cotyledon segments and sucrose-gradient fractions from germinated cucumber (Cucumis sativus L.) seedlings. The seedlings were grown in the dark for 4 days, transferred to 4 hours of continuous light, then returned to the dark for 24 hours. Under these conditions, high specific activities for both glyoxysomal and peroxisomal enzymes are maintained in cotyledon homogenates and microbody-enriched fractions. Electron cytochemistry of the marker enzymes reveals that all or virtually all the microbodies observed in cotyledonary cells and sucrose-gradient fractions contain both enzymes. The staining in gradient fractions was determined from scoring a minimum of 600 photographed microbodies for each enzyme. After correcting for the number of particles stained for catalase reactivity (representing true microbodies), 94 and 97% of the microbodies were found stained for malate synthase and glycolate oxidase activity, respectively.The results from these studies provide pertinent information toward understanding the succession from glyoxysomal to peroxisomal metabolism in cotyledons of fatty seedlings. The coexistence of two separate microbody types functioning at different stages of development apparently is not the case. The localizations of both marker enzymes within one microbody type strongly suggest that the metabolic transition involves a change in enzyme complement within an ongoing population of microbodies.

Cytochemical localization of malate synthase in glyoxysomes

Cytochemical staining techniques for microbodies (peroxisomes) are limited at present to the enzymes catalase and alpha-hydroxy acid oxidase, and neither technique can distinguish glyoxysomes from other microbodies. Described here is a procedure using ferricyanide for the cytochemical demonstration by light and electron microscopy of malate synthase activity in glyoxysomes of cotyledons from fat-storing cucumber and sunflower seedlings. Malate synthase, a key enzyme of the glyoxylate cycle, catalyzes the condensation of acetyl CoA with glyoxylate to form malate and release free coenzyme A. Localization of the enzyme activity is based on the reduction by free CoA of ferricyanide to ferrocyanide, and the visualization of the latter as an insoluble, electron-opaque deposit of copper ferrocyanide (Hatchett's brown). The conditions and optimal concentrations for the cytochemical reaction mixture were determined in preliminary studies using a colorimetric assay developed to measure disappearance of ferricyanide at 420 nm. Ultrastructural observation of treated tissue reveals electron-opaque material deposited uniformly throughout the matrix portion of the glyoxysomes, with little background deposition elsewhere in the cell. The reaction product is easily visualized in plastic sections by phase microscopy without poststaining. Although the method has been applied thus far only to cotyledons of fat-storing seedlings, it is anticipated that the technique will be useful in localizing and studying glyoxylate cycle activity in a variety of tissues from both plants and animals.

Propagation constants of resonant waves on homogeneous, isotropic slab waveguides

A general graphical study of the complex valued propagation constants, defining the various types of TE waves that are resonant on optical thin-film (slab) waveguides, is presented. The dielectric constants of both the slab and its surroundings are allowed to take on all possible complex values. The corresponding waves are classified into two general types: surface waves, with conductive losses only; and leaky waves, with both conductive and radiative losses.