Familial apolipoprotein A-I and C-III deficiency, variant II

The biochemical, clinical, and genetic features were examined in the proband (homozygote) and heterozygotes (n = 17) affected with familial apolipoprotein A-I and C-III deficiency, variant II (previously described as apolipoprotein A-I absence). The proband was a 45-year-old white female with mild corneal opacification and significant three-vessel coronary artery disease (CAD), who died shortly after bypass surgery. Autopsy findings included significant atherosclerosis in the coronary and pulmonary arteries and the abdominal aorta as well as extracellular stromal lipid deposition in the cornea. No reticuloendothelial lipid deposits in the liver, bone marrow, or spleen were noted (unlike Tangier disease). Laboratory features included marked high density lipoprotein (HDL) deficiency and undetectable plasma apolipoproteins (apo) A-I and C-III. The percentage of plasma cholesterol in the unesterified form was normal at 30%. The activity and mass of lecithin:cholesterol acyltransferase (LCAT) were 42% and 36% of normal, respectively, and the cholesterol esterification rate was 43% of normal. Deficiencies of plasma vitamin E and essential fatty acid (linoleic, C18:2) were also noted. Evaluation of plasma lipoproteins and apolipoproteins in 37 kindred members revealed 17 heterozygotes with HDL cholesterol values below the 10th percentile of normal. Of these, all had apoA-I levels more than one standard deviation below the normal mean, and 37.5% had a similar decrease in apoC-III values. Mean (+/- SD) plasma HDL cholesterol, apoA-I, and apoC-III values (mg/dl) in heterozygotes were 54.0%, 62.4%, and 79.2% of normal, respectively. No evidence of CAD was observed in 10 heterozygotes 40 years of age or less; however, CAD was detected in 3 of 7 heterozygotes over 40 years of age, one of whom died at age 56 years of complications of myocardial infarction and stroke. The inheritance pattern in this kindred was autosomal codominant. ApoA-I isolated from a heterozygote had an isoelectric focusing pattern and amino acid composition similar to normal. Utilizing DNA isolated from two obligate heterozygotes, no abnormalities in the apoA-I or apoC-III genes were detected by Southern blot analysis utilizing specific probes following restriction enzyme digestion. The data indicate that familial apolipoprotein A-I and C-III deficiency, variant II, is similar to variant I (described by Norum et al. 1982. N. Engl. J. Med. 306: 1513-1519), but differs at the clinical level (lack of xanthomas), the biochemical level (lack of detectable apoA-I, lower apoA-II level), and at the gene level.(ABSTRACT TRUNCATED AT 400 WORDS)     

Where can switchgrass production be more profitable than corn and soybean? An integrated subfield assessment in Iowa,USA

Perennial bioenergy crops are considered an important feedstock for a growing bioeconomy. However, in the USA, production of biofuel from these dedicated, nonfood crops is lagging behind federal mandates and markets have yet to develop. Most studies on the economic potential of perennial biofuel crops have concluded that even high‐yielding bioenergy grasses are unprofitable compared to corn/soybeans, the prevailing crops in the United States Corn Belt. However, they did not account for opportunities precision agriculture presents to integrate perennials into agronomically and economically underperforming parts of corn/soybean fields. Using publicly available subfield data and market projections, we identified an upper bound to the areas in Iowa, United States, where the conversion from corn/soybean cropland to an herbaceous bioenergy crop, switchgrass, could be economically viable under different price, land tenancy, and yield scenarios. Assuming owned land, medium crop prices, and a biomass price of US$ 55 Mg^?1, we showed that 4.3% of corn/soybean cropland could break even when converted to switchgrass yielding up to 10.08 Mg ha^?1. The annualized change in net present value on each converted subfield patch ranged from just above US$ 0 ha^?1 to 692 ha^?1. In the three counties of highest economic opportunity, total annualized producer benefits from converting corn/soybean to switchgrass summed to US$ 2.6 million, 3.4 million, and 7.6 million, respectively. This is the first study to quantify an upper bound to the potential private economic benefits from targeted conversion of unfavorable corn/soybean cropland to switchgrass, leaving arable land already under perennial cover unchanged. Broadly, we conclude that areas with high within‐field yield variation provide highest economic opportunities for switchgrass conversion. Our results are relevant for policy design intended to improve the sustainability of agricultural production. While focused on Iowa, this approach is applicable to other intensively farmed regions globally with similar data availability.     

Carbon isotope variations in a plantation of Sitka spruce,and the effect of acid mist

Intra- and inter-tree variations in ¹³C/¹²C ratios were studied within a single clone plantation of 20-year-old Sitka spruce, some of which were treated with mist simulating acidic cloud water. For groups of trees of similar height and the same treatment, sampled at the same whorl height, ¹³C values for current year needles showed variations (1 SD) of between 0.2 and 0.7. The variations reflect the seasonally averaged influences, on intercellular CO₂ concentrations, of slight variations in the microhabitat within a group. For a typical intra-group variation of 0.4 one may be able to distinguish between groups whose mean intercellular CO₂ concentrations differ by only 8 ppm. Acid misting resulted in a lowering of ¹³C values by c. 0.7 (significant at the P0.05 level). This reflects higher intercellular CO₂ concentrations for acid misted trees, which can be interpreted in terms of their having assimilation rates c. 10% lower than those of control trees, and might explain the observed reduction in stem growth for acid-misted trees. Without careful attention to sampling strategy, however, these small inter-tree ¹³C variations can be easily masked by the much larger intra-tree variations with height. Large gradients of increasing needle ¹³C with height, of c. 0.5 m^-1, were observed in two untreated trees of different total height. The gradient was similar for both trees so, though ¹³C values of both trees were identical close to their leaders (–27), the taller tree displayed much lower values close to the ground (–31). The gradients are believed to reflect lower light levels close to the ground, rather than the accumulation of respired CO₂ in the atmosphere. The different height response of stems versus needles, reflected by an increase in ¹³C_stems–¹³C_needles with height (for cellulose), is discussed in terms of stem photosynthetic recapture of internally respired CO₂.     

Potential canopy influences on the isotopic composition of nitrogen and sulphur in atmospheric deposition

Isotopic studies of nitrogen and sulphur inputs to plant/soil systems commonly rely on limited published data for the ¹⁵N/¹⁴N and ³⁴S/³²S ratios of nitrate, ammonium and sulphate in rainfall. For systems with well-developed plant canopies, however, inputs of these ions from dry deposition or particulates may be more important than rainfall. The manner in which isotopic fractionation between ions and gases may lead to dry deposition and particulates having ¹⁵N/¹⁴N or ³⁴S/³²S ratios different from those of rainfall is considered. Data for rainfall and throughfall in coniferous plantations are then discussed, and suggest that: (1) in line with expectations, nitrate washed from the canopy has ¹⁵N/¹⁴N ratios higher than those in rainfall; (2) the ¹⁵N/¹⁴N ratios of ammonium washed from the canopy are variable, with high ratios being found for canopies of higher pH in conditions of elevated ambient ammonia gas concentrations; and (3) in accord with expectations and previous work, ³⁴S/³²S ratios of sulphate washed from the canopy are not substantially different from those in rainfall. The study suggests that if atmospheric inputs are relevant to isotopic studies of the sources of nitrogen for canopied systems, then confident interpretation will require analysis of these inputs. Received: 3 March 1996 / Accepted: 28 September 1996     

Adverse effects of tempol on hidrosaline balance in rats with acute sodium overload

We studied the effects of tempol, an oxygen radical scavenger, on hydrosaline balance in rats with acute sodium overload. Male rats with free access to water were injected with isotonic (control group) or hypertonic saline solution (0.80 mol/l NaCl) either alone (Na group) or with tempol (Na-T group). Hydrosaline balance was determined during a 90 min experimental period. Protein expressions of aquaporin 1 (AQP1), aquaporin 2 (AQP2), angiotensin II (Ang II) and endothelial nitric oxide synthase (eNOS) were measured in renal tissue. Water intake, creatinine clearance, diuresis and natriuresis increased in the Na group. Under conditions of sodium overload, tempol increased plasma sodium and protein levels and increased diuresis, natriuresis and sodium excretion. Tempol also decreased water intake without affecting creatinine clearance. AQP1 and eNOS were increased and Ang II decreased in the renal cortex of the Na group, whereas AQP2 was increased in the renal medulla. Nonglycosylated AQP1 and eNOS were increased further in the renal cortex of the Na-T group, whereas AQP2 was decreased in the renal medulla and was localized mainly in the cell membrane. Moreover, p47-phox immunostaining was increased in the hypothalamus of Na group, and this increase was prevented by tempol. Our findings suggest that tempol causes hypernatremia after acute sodium overload by inhibiting the thirst mechanism and facilitating diuresis, despite increasing renal eNOS expression and natriuresis.     

Glucocorticoid induction of plasminogen activator and plasminogen activator-inhibitor messenger RNA in rat hepatoma cells

HTC rat hepatoma cells synthesize and secrete both tissue-type plasminogen activator (tPA) and type 1 plasminogen activator-inhibitor (PAI-1). Incubation with the synthetic glucocorticoid dexamethasone causes a rapid decrease in tPA activity which is secondary to a 5-fold increase in PAI-1 antigen and activity. Paradoxically, dexamethasone increases tPA antigen by 50%. We have analyzed HTC cell RNA by Northern and slot blot analysis, using as probes radiolabeled human PAI-1 and rat tPA cDNAs. HTC cells have a single species of PAI-1 mRNA of approximately 3.2 kilobases, which is increased 4-fold upon incubation with dexamethasone. Maximal induction occurs after 8-10 h of incubation. Half-maximal induction occurs at 5 nM dexamethasone. Dexamethasone also transiently increases the 2.8 kilobase tPA mRNA. The protein synthesis inhibitor cycloheximide does not affect accumulation of PAI-1 mRNA and does not block its induction by dexamethasone. In contrast, cycloheximide alone causes an increase in tPA mRNA, and in combination with dexamethasone, no further increase is observed. Induction of both mRNAs is prevented by actinomycin D. We conclude that the dexamethasone-induced increase in HTC cell PAI-1 activity and antigen is the result of a direct effect on accumulation of PAI-1 mRNA.     

Salmonella Survival on Pecans as Influenced by Processing and Storage Conditions

Survival of Salmonella senftenberg 775W, S. anatum, and S. typhimurium during exposure to currently practiced, as well as abusive, pecan processing and storage conditions was studied. Thermal treatments normally carried out during the processing of pecans are inadequate to consistently destory salmonellae in highly contaminated inshell nuts. Pecan nut packing tissue was toxic to salmonellae, thus affording some protection against high initial contamination and subsequent survival of the organisms. Examinations of inoculated inshell pecans stored at -18, -7, 5, and 21 C for up to 32 weeks revealed that the extent of survival was inversely correlated to the storage temperature. S. senftenberg 775W and S. anatum were not detectable on inshell nuts after 16 weeks of storage at 21 C. Little decrease in viable population of the three species was noted on inoculated pecan halves stored at -18, -7, and 5 C for 32 weeks. Due to organoleptic quality deterioration in pecan nutmeats at elevated temperatures, sterilization methods other than thermal treatment appear to be required for the elimination of viable salmonellae from pecan nuts.