The relationship between spinal and peripheral osteoarthritis and bone density measurements.

OBJECTIVE: To determine the influence of osteoarthritis (OA) on bone density measurements and whether OA at one site is associated with OA at other sites. METHODS: Nonrandomized, cross sectional observational study; secondary analysis of a general population database. Sixty-four subjects derived from a longitudinal study of long distance runners and community controls had a complete peripheral radiographic evaluation for osteoarthritic changes in hands, knees, and lumbar spine. Forty-four of these were studied in 1984 with quantitative computed tomography (QCT) of L1, and 54 were studied in 1988 with 153-Gd dual photon absorptiometry (DPA) in the spine and total body. Thirty-four subjects had all measurements done. RESULTS: Total body and lumbar spine DPA were positively correlated with radiological scores of OA in the spine and knees, with coefficients ranging between 0.467 to 0.530 (p < 0.001 in all cases). This correlation was principally associated with spinal spurs and knee sclerosis. Results of stepwise multiple linear regression modeling for QCT included age, spine sclerosis, knee sclerosis and knee spurs as the main predictors of bone mineral density (BMD). For DPA measurements, spine spur score was a useful regressor for all the models. Altogether, the percentage of variance accounted for by individual radiological OA variables was 27.4% for lumbar QCT, 27.3% for lumbar BMD, 7.3% for total spine BMD, and 45.2% for total body BMD. OA scores at different sites were not correlated, although repeated assessment at the same site showed very close correlation. CONCLUSIONS: All methods used to determine BMD showed a highly significant positive correlation between lumbar and knee radiological OA and bone mineral content both in the spine and the total body. Thus, our results support the hypothesis that OA is negatively correlated with osteopenia. OA, as seen in this population, was not a generalized condition, but rather, was site specific.

The effect of sodium chloride on solute potential and proline accumulation in soybean leaves.

Two cultivars of soybean (Glycine max [L.] Merr.) were grown in solution with up to 100 millimolar NaCl. Leaf solute potential was -1.1 to -1.2 megapascals in both cultivars without NaCl. At 100 millimolar NaCl leaf solute potential was -3.1 to -3.5 megapascals in Bragg and -1.7 megapascals in Ransom. The decrease in solute potential was essentially proportional to the concentration of NaCl. In both salt susceptible Bragg and salt semitolerant Ransom, leaf proline was no more than 0.4 micromole per gram fresh weight at or below 20 millimolar NaCl. At 40 and 60 millimolar NaCl, Bragg leaf proline levels were near 1.2 and 1.9 micromoles per gram fresh weight, respectively. Proline did not exceed 0.5 micromole per gram fresh weight in Ransom even at 100 millimolar NaCl. Proline accumulated in Bragg only after stress was severe enough to induce injury; therefore proline accumulation is not a sensitive indicator of salt stress in soybean plants.

A Guide to Establishing Water Potential of Aqueous Two-Phase Solutions (Polyethylene Glycol plus Dextran) by Amendment with Mannitol.

A practical guide to calculating the mannitol (MAN) amendment required to achieve the desired water potential (Psi) of polyethylene glycol/dextran (PEG/DEX) aqueous two-phase systems for protoplast purification is presented. The empirically generated equation Psi = 305[PEG'](2)[MAN] + 0.74[PEG'][MAN]T - 103[PEG'][MAN] + 5.6[PEG'](2)T - 623[PEG'](2) - 0.25[PEG']T + 12.7[PEG'] - 0.078[MAN]T - 22.75[MAN]accurately predicts experimental Psi (in bars). [PEG'] indicates the presence of DEX where [DEX] = [PEG]/(0.6-0.4[PEG]). The equation is applicable for these ranges: [PEG'] from 0.047 to 0.13 gram per gram H(2)O; [MAN] from 0 to 0.7 molal; T from 4.5 to 40 degrees C. Actual Psi should differ from derived Psi by no more than 8% for the least negative values to 4% for the most negative values. The Psi for solutions of MAN, of PEG, and of DEX were also determined. Equations to fit data for each were generated. Analyses indicated a significant synergistic effect on Psi when MAN is added to PEG/DEX and, at certain concentrations, between PEG and DEX.

Evaluation of the water potentials of solutions of polyethylene glycol 8000 both in the absence and presence of other solutes.

Published and additional data for polyethylene glycol 8000 (PEG), formerly PEG 6000, solution water potentials (Psi) are compared. Actual bars Psi over the concentration range of 0 to 0.8 gram PEG per gram H(2)O and temperature (T) range of 5 to 40 degrees C are best predicted (probably within +/- 5%) by this equation: Psi = 1.29[PEG](2)T - 140[PEG](2) - 4.0[PEG]. Although transformable through division by [PEG] to virial equation form, results indicate that the coefficients are not virial. Mannitol (MAN) interacts with PEG to produce Psi significantly lower than additive. Vapor pressure osmometer (VPO) data for MAN-PEG synergism compared favorably with those from thermocouple hygrometry; and VPO data showing the interactions between PEG and four salts are presented. The synergism of MAN-PEG and of NaCl-PEG are related linearly to the concentration of solute added with PEG.

Correction of thermal gradient errors in stem thermocouple hygrometers.

Stem thermocouple hygrometers were subjected to transient and stable thermal gradients while in contact with reference solutions of NaCl. Both dew point and psychrometric voltages were directly related to zero offset voltages, the latter reflecting the size of the thermal gradient. Although slopes were affected by absolute temperature, they were not affected by water potential. One hygrometer required a correction of 1.75 bars water potential per microvolt of zero offset, a value that was constant from 20 to 30 C.

A miniature stem thermocouple hygrometer.

An unprotected chromel-constantan thermocouple was mounted in a cavity (4 x 2 x 1 mm) with rounded corners in a chrome-plated brass block (10 x 6 x 4 mm). When installed against a soybean (Glycine max [L.] Merr.) xylem face, sealed with caulking gum, and insulated with polyurethane foam and aluminum foil, even rapidly changing stem water potentials could be followed accurately. Temperature gradients can be a problem.

A model relating root permeability to flux and potentials: application to existing data from soybean and other plants.

A model that relates hydraulic permeability to water flux and to gradients in pressure potential and solute potential was tested using soybean (Glycine max) plants. Water flux was varied by additions of polyethylene glycol 6,000 around one portion of a divided root system and by changing the light intensity and CO(2) concentration around the plants. The data are compatible with the model only if the hydraulic permeability varies with flux; however, the data were insufficient for rigorous testing. Three sets of published data fit the model only if hydraulic permeability varies. Evidence originally presented as involving constant hydraulic permeability is shown, rather, to require variable hydraulic permeability.

The osmotic potential of polyethylene glycol 6000.

Osmotic potential (psi(s)) of aqueous solutions of polyethylene glycol 6000 (PEG-6000) was curvilinearly related to concentration. At given concentrations, psi(s) increased linearly with temperature. The effects of concentration and temperature on psi(s) of PEG-6000 solutions differ from those for most salts and sugars and apparently are related to structural changes in the PEG polymer. Measurements of psi(s) with thermocouple psychrometers are more negative than those with a vapor pressure osmometer, with the psychrometer probably giving the more nearly correct psi(s) for bulk solutions. An empirical equation permits calculation of psi(s) from known concentrations of PEG-6000 over a temperature range of 15 to 35 C. Viscometery and gravimetric analysis are convenient methods by which the concentrations of PEG-6000 solutions may be measured.

Further Comparisons between Carbowax 6000 and Mannitol as Suppressants of Cucumber Hypocotyl Elongation.

Stirring largely eliminated the greater effectiveness of Carbowax 6000 compared to mannitol in reducing cucumber (Cucumis sativus L.) hypocotyl section elongation. Stirring increased elongation in water but reduced elongation in growth regulator solution. Shrinkage of cells without plasmolysis in hypertonic Carbowax solutions indicates that Carbowax 6000 did not penetrate cell walls. Sections prevented from elongating during pretreatment exposure to saturated air grew as much as those not pretreated. Sections pretreated with isotonic Carbowax responded similarly, but sections pretreated with isotonic mannitol grew less.

Investigation of plant water relations with divided root systems of soybean.

Soybean (Glycine max) was grown with root systems divided between adjacent cartons containing nutrient solution or soil. By adding polyethylene glycol (Carbowax 6000) to reduce solute potential or withholding water to reduce soil matric potential until water absorption from that side stopped, the root xylem water potential could be ascertained. Carbowax appeared to increase root resistance. An imbalance technique is described with which soil moisture contents of adjacent containers were followed individually. The patterns of water absorption obtained following repeated additions of water or addition of CaCl(2) solutions to one side indicated soil hydraulic conductivity became limiting at a soil water potential of -2 bars. A high concentration of CaCl(2) added to one side greatly reduced transpiration and produced severe plant injury. With part of the root system developing in nutrient solution, growth of roots into and water absorption from soil were slow; however, reduction of solute potential in the solution side greatly increased water absorption from the soil side.

The Expression of Interionic Relationships in Pinus elliottii.

The effects of factorial combinations of N, P and Mg on some of the interrelationships among nutrient ions as they occurred in seedlings of slash pine were investigated. In similar studies, true interactions have not always been differentiated from apparent interactions, the result of comparing foliage concentrations in plants with widely divergent growth rates. To prevent this, nutrient solutions were formulated to produce conditions ranging only from slight deficiency through luxury consumption. This relatively narrow range of nutrition allowed actual interactions to be separated from those changes in foliage concentration that are primarily a result of large differences in growth.The needles were analyzed for total and soluble N and total P, K, Ca, Mg and Na. Each level of each nutrient variable had a significant effect on the concentration of 1 or more dissimilar elements. The familiar depressive effect of N on foliar P was observed; however this relationship was shown to be primarily the result of growth dilution rather than anion antagonism. Increased Mg did antagonistically reduce the uptake of Ca and, generally, K. Increments of P not required for growth stimulated uptake of N, Ca, Mg and K. No relationship was found between Mg supply and P accumulation.

Photosynthesis, Transpiration, Leaf Temperature, and Stomatal Activity of Cotton Plants under Varying Water Potentials.

Cotton plants, Gossypium hirsutum L. were grown in a growth room under incident radiation levels of 65, 35, and 17 Langleys per hour to determine the effects of vapor pressure deficits (VPD's) of 2, 9, and 17 mm Hg at high soil water potential, and the effects of decreasing soil water potential and reirrigation on transpiration, leaf temperature, stomatal activity, photosynthesis, and respiration at a VPD of 9 mm Hg.Transpiration was positively correlated with radiation level, air VPD and soil water potential. Reirrigation following stress led to slow recovery, which may be related to root damage occurring during stress. Leaf water potential decreased with, but not as fast as, soil water potential.Leaf temperature was usually positively correlated with light intensity and negatively correlated with transpiration, air VPD, and soil water. At high soil water, leaf temperatures ranged from a fraction of 1 to a few degrees above ambient, except at medium and low light and a VPD of 19 mm Hg when they were slightly below ambient, probably because of increased transpirational cooling. During low soil water leaf temperatures as high as 3.4 degrees above ambient were recorded. Reirrigation reduced leaf temperature before appreciably increasing transpiration. The upper leaf surface tended to be warmer than the lower at the beginning of the day and when soil water was adequate; otherwise there was little difference or the lower surface was warmer. This pattern seemed to reflect transpiration cooling and leaf position effects.Although stomata were more numerous in the lower than the upper epidermis, most of the time a greater percentage of the upper were open. With sufficient soil water present, stomata opened with light and closed with darkness. Fewer stomata opened under low than high light intensity and under even moderate, as compared with high soil water. It required several days following reirrigation for stomata to regain original activity levels.Apparent photosynthesis of cotton leaves occasionally oscillated with variable amplitude and frequency. When soil water was adequate, photosynthesis was nearly proportional to light intensity, with some indication of higher rates at higher VPD's. As soil water decreased, photosynthesis first increased and then markedly decreased. Following reirrigation, photosynthesis rapidly recovered.Respiration was slowed moderately by decreasing soil water but increased before watering. Respiration slowed with increasing leaf age only on leaves that were previously under high light intensity.