Physiological and foliar symptom response in the crowns of Prunus serotina, Fraxinus americana and Acer rubrum canopy trees to ambient ozone under forest conditions.

The crowns of five canopy dominant black cherry (Prunus serotina Ehrh.), five white ash (Fraxinus americana L.), and six red maple (Acer rubrum L.) trees on naturally differing environmental conditions were accessed with scaffold towers within a mixed hardwood forest stand in central Pennsylvania. Ambient ozone concentrations, meteorological parameters, leaf gas exchange and leaf water potential were measured at the sites during the growing seasons of 1998 and 1999. Visible ozone-induced foliar injury was assessed on leaves within the upper and lower crown branches of each tree. Ambient ozone exposures were sufficient to induce typical symptoms on cherry (0-5% total affected leaf area, LAA), whereas foliar injury was not observed on ash or maple. There was a positive correlation between increasing cumulative ozone uptake (U) and increasing percent of LAA for cherry grown under drier site conditions. The lower crown leaves of cherry showed more severe foliar injury than the upper crown leaves. No significant differences in predawn leaf water potential (psi(L)) were detected for all three species indicating no differing soil moisture conditions across the sites. Significant variation in stomatal conductance for water vapor (g(wv)) was found among species, soil moisture, time of day and sample date. When comparing cumulative ozone uptake and decreased photosynthetic activity (P(n)), red maple was the only species to show higher gas exchange under mesic vs. drier soil conditions (P < 0.05). The inconsistent differences in gas exchange response within the same crowns of ash and the uncoupling relationship between g(wv) and P(n) demonstrate the strong influence of heterogeneous environmental conditions within forest canopies.

Physiological and foliar injury responses of Prunus serotina, Fraxinus americana, and Acer rubrum seedlings to varying soil moisture and ozone.

Sixteen black cherry (Prunus serotina, Ehrh.), 10 white ash (Fraxinus americana, L.) and 10 red maple (Acer rubrum, L.) 1-year old seedlings were planted per plot in 1997 on a former nursery bed within 12 open-top chambers and six open plots. Seedlings were exposed to three different ozone scenarios (ambient air: 100% O3; non-filtered air: 98% ambient O3; charcoal-filtered air: 50% ambient O3) within each of two different water regimes (nine plots irrigated, nine plots non-irrigated) during three growing seasons. During the 1998 and 1999 growing season, leaf gas exchange, plant water relations, and foliar injury were measured. Climatic data,ambient- and chamber-ozone-concentrations were monitored. We found that seedlings grown under irrigated conditions had similar (in 1998) but significantly higher gas exchange rates (in 1999) than seedlings grown within non-irrigated plots among similar ozone exposures. Cherry and ash had similar ozone uptake but cherry developed more ozone-induced injury (< 34% affected leaf area, LAA) than ash (<5% LAA), while maple rarely showed foliar injury, indicating the species differed in ozone sensitivity. Significantly more severe injury on seedlings grown under irrigated conditions than seedlings grown under non-irrigated conditions demonstrated that soil moisture altered seedling responses to ambient ozone exposures.

Repeat chlamydia screening by mail, San Francisco.

OBJECTIVES: To assess the feasibility and acceptability of home screening for repeat chlamydial infection using urine test kits sent through the mail. METHODS: A letter offering home rescreening was mailed to 399 adults who previously tested positive for chlamydia. Kits were then mailed to anyone who did not actively decline. The home testing kits contained instructions on how to collect a urine specimen and return the specimen by mail. Specimens were tested with strand displacement amplification. A short survey asked individuals their level of concern about confidentiality, safety, and privacy of mail screening. RESULTS: Among the 313 potential test kit recipients, 22.4% responded. Response rates were highest among homosexual and bisexual men (38.6%), people 35 years or older (34.3%), and white people (34.6%). The overall positivity rate was 3.2% (2/63). In women 18-25 years old, the positivity was 13.3% (2/15). CONCLUSIONS: Home testing with mailed urine collection kits is feasible and an acceptable method to screen for recurrent chlamydial infection. Young women would probably benefit most because of their higher rates of reinfection and risk for sequelae.

Foliar injury, leaf gas exchange and biomass responses of black cherry (Prunus serotina Ehrh.) half-sibling families to ozone exposure.

Open pollinated families of black cherry seedlings were studied to determine genotypic differences in foliar ozone injury and leaf gas exchange in 1994 and growth response following three growing seasons. An O(3)-sensitive half-sibling family (R-12) and an O(3)-tolerant half-sibling family (MO-7) planted in natural soil were studied along with generic nursery stock (NS) seedlings. Ozone exposure treatments were provided through open top chambers and consisted of 50, 75, and 97% of ambient ozone, and open plots from May 9 to August 26, 1994. Ambient ozone concentrations reached an hourly peak of 88 ppb with 7-hour averages ranging from 39 to 46 ppb. Seedlings in the 50 and 75% of ambient chambers were never exposed to greater than 80 ppb O(3). Visible foliar ozone injury (stipple) was significantly higher for R-12 seedlings than MO-7 seedlings and increased with increasing ozone exposures. For the chamber treatments averaged over all families, there was no significant difference in stomatal conductance and net photosynthetic rates, but there was a significant decrease in root biomass, and a significant decrease in root/shoot ratio between the 50 and 97% of ambient chambers. Stomatal conductance and net photosynthetic rates were significantly different between families with R-12 seedlings generally greater than MO-7 seedlings. The R-12 seedlings had a 7.5 mmol m(-2) increase in ozone uptake compared to MO-7, and at the same cumulative O(3) exposure R-12 exhibited 40.9% stippled leaf area, whereas MO-7 had 9.2% stippled leaf area. Significant differences were observed in stem volume growth and total final biomass between the open-top chambers and open plots. Although R-12 had the most severe foliar ozone injury, this family had significantly greater stem volume growth and total final biomass than MO-7 and NS seedlings. Root:shoot ratio was not significantly different between MO-7 and R-12 seedlings.

Foliar response of black cherry (Prunus serotina) clones to ambient ozone exposure in central Pennsylvania.

During late summer of 1996 and 1997 we examined ozone-induced foliar injury in a plantation of 111 black cherry trees (ramets) comprising 15 clones originating from wild ortets growing in the Allegheny National Forest, Pennsylvania, and the Monongahela National Forest, West Virginia. The experimental plantation was a clonal seed orchard in Centre County, Pennsylvania, started in 1971 using ortet buds grafted onto seedling rootstocks of mixed origin. Clones differed significantly in severity of foliar injury symptoms (F=31.83, p<0.001). One clone (R-12) had significantly more foliar injury with >50% leaf area affected than other clones during both years. In contrast, clone R-14, which is from the same area in northcentral Pennsylvania as R-12, exhibited significantly less injury (LAA<6%). Although ambient O(3) concentrations were similar in both years, foliar injury was significantly greater (15.7%) in 1996 than in 1997 (9.9%). This is probably explained by lower stomatal conductance in 1997 caused by drier and hotter weather patterns in June and July of that year. Despite very different weather patterns and overall levels of injury in 1996 and 1997, mean clonal injury was significantly correlated between both years of assessment (r=0.92, p<0.001). Within tree crowns, foliage in lower and inner crown positions was significantly more injured than foliage in upper and exterior crown positions. There was no evidence of geographically based population differences in sensitivity to foliar O(3) injury. On the contrary, results demonstrate that wild genotypes of proximal geographic origin may differ greatly in sensitivity.

Light environment alters ozone uptake per net photosynthetic rate in black cherry trees.

Foliar ozone uptake rates of different-sized black cherry (Prunus serotina Ehrh.) trees were compared within a deciduous forest and adjacent openings in north-central Pennsylvania during one growing season. Study trees included open-grown seedlings and saplings, forest understory seedlings and saplings, and sunlit and shaded portions of mature canopy tree crowns. Instantaneous ozone uptake rates were highest in high-light environments primarily because of higher stomatal conductances. Low ozone uptake rates of seedlings and saplings in the forest understory could be attributed partially to lower average ambient ozone concentrations compared to the canopy and open environments. Among the tree size and light combinations tested, ozone uptake rates were highest in open-grown seedlings and lowest in forest-grown seedlings. Despite lower ozone uptake rates of foliage in shaded environments, ozone uptake per net photosynthesis of foliage in shaded environments was significantly higher than that of foliage in sunlit environments because of weaker coupling between net photosynthesis and stomatal conductance in shaded environments. The potential for greater ozone injury in shaded environments as a result of greater ozone uptake per net photosynthesis is consistent with previous reports of greater ozone injury in shaded foliage than in sunlit foliage.

Size-mediated foliar response to ozone in black cherry trees.

Local ozone concentration and visible foliar injury were measured over the 1994 growing season on open-grown black cherry (Prunus serotina Ehrh.) trees of varying size (age) within forest stands and adjacent openings at a site in north-central Pennsylvania. Relationships were determined between visible ozone injury and ozone exposure, as well as calculated between injury and ozone uptake expressed as the product of stomatal conductance and ozone concentration. In addition, simultaneous measurements of visible symptoms and leaf gas exchange were also conducted to determine the correlation between visible and physiological injury and ozone exposure. By September, the amount of leaf area affected by visible foliar ozone injury was greatest for seedlings (46%), followed by canopy trees (20%) and saplings (15%). A large amount of variability in foliar ozone symptom expression was observed among trees within a size class. Sum40 and Sum60 (ozone concentration > 40 and > 60 nl liter(-1)) cumulative exposure statistics were the most meaningful indices for interpretation of foliar injury response. Seedlings were apparently more sensitive to ozone injury than larger trees because their higher rates of stomatal conductance resulted in higher rates of ozone uptake. Seedlings also had higher rates of early leaf abscission than larger trees with an average of nearly 30% of the leaves on a shoot abscised by 1 September compared to approximately 5% for larger trees. However, per unit ozone uptake into the leaf, larger trees exhibited larger amounts of foliar injury. The amount of visible foliar injury was negatively correlated (r(2) = 0.82) with net photosynthetic rates, but was not related to stomatal conductance. Net photosynthesis and stomatal conductance thus became uncoupled at high levels of visible foliar injury.

Predicting Ozone Uptake from Meteorological and Environmental Variables.

Predictions of foliar ozone uptake rates of seedling and canopy black cherry trees (Prunus serotina Ehrh.) were made using concurrent measurements of ambient ozone concentration and other environmental and meteorological data during two growing seasons in north-central Pennsylvania.

Systematic variation in xylem hydraulic capacity within the crown of white ash (Fraxinus americana).

A 7-m tall white ash tree (Fraxinus americana Marsh.) was dissected, and hydraulic parameters of the xylem were determined by inducing a steady-state flow of water through the stem segments and monitoring volume and velocity flow rates. Leaf-specific conductivity (LSC) was highest in the main stem and lowest in some of the leaf-bearing lateral shoots. The LSC was higher in the main stem than in branches and higher in primary than in secondary branch axes. Terminal leaf-bearing shoots were larger and had a significantly greater mean LSC than subjacent lateral shoots. A significant reduction in LSC was associated with the transition between 1- and 2-year-old growth. In branches of the same age, there was a close correspondence among LSC, branch position and branch size. The average LSC of leaf-bearing shoots from south-facing branches was 43% greater than that of shoots from north-facing branches. Within-crown variation in LSC was associated with variation in velocity flow rate (V). By contrast, the ratio of potentially functional xylem area to supported leaf area (A(pf)/A(l)) was relatively stable throughout the crown. Stratification of stems by Strahler order accounted for approximately 70% of the total variation in LSC. These results suggest that (1) there exists a systematic pattern of variation in LSC distribution within the crown of white ash, (2) within-crown variability in LSC is primarily the result of variation in mean vessel diameter, and (3) there is a physiological linkage between LSC and crown morphology that is maintained through a positive feedback mechanism during branch ontogeny.

Physiology, morphology, and ozone uptake of leaves of black cherry seedlings, saplings, and canopy trees.

Patterns of ozone uptake were related to physiological, morphological, and phenological characteristics of different-sized black cherry trees (Prunus serotina Ehrh.) at a site in central Pennsylvania. Calculated ozone uptake differed among open-grown seedlings, forest gap saplings, and canopy trees and between leaves in the upper and lower crown of saplings and canopy trees. On an instantaneous basis, seedling leaves had the greatest ozone uptake rates of all tree size classes due to greater stomatal conductance and higher concentrations of ozone in their local environment. A pattern of higher stomatal conductance of seedlings was consistent with higher incident photosynthetically-active radiation, stomatal density, and predawn xylem water potentials for seedlings relative to larger trees. However, seedlings displayed an indeterminate pattern of shoot growth, with the majority of their leaves produced after shoot growth had ceased for canopy and sapling trees. Full leaf expansion occurred by mid-June for sapling and canopy trees. Because many of their leaves were exposed to ozone for only part of the growing season, seedlings had a lower relative exposure over the course of the growing season, and subsequently lower cumulative uptake, of ozone than canopy trees and a level of uptake similar to upper canopy leaves of saplings. Visible injury symptoms were not always correlated with patterns in ozone uptake. Visible symptoms were more apparent on seedling leaves in concurrence with their high instantaneous uptake rates. However, visible injury was more prevalent on leaves in the lower versus upper crown of canopy trees and saplings, even though lower crown leaves had less ozone uptake. Lower crown leaves may be more sensitive to ozone per unit uptake than upper crown leaves because of their morphology. In addition, the lower net carbon uptake of lower crown leaves may limit repair and anti-oxidant defense processes.

Variation in seedling hydraulic architecture as a function of species and environment.

Northern red oak (Quercus rubra L.) and yellow-poplar (Liriodendron tulipifera L.) were grown for two years in full sunlight (unshaded) or 20% of full sunlight (shaded) under either well-watered or drought conditions. There was a close association between evaporative flux (in situ) and leaf-specific conductivity (LSC) in stem segments of both species. Shaded, drought-stressed seedlings of both species had significantly reduced leaf area, evaporative flux, volume flow rate in xylem, flow velocity, potentially functional xylem area, and LSC than unshaded, well-watered seedlings. Reductions in LSC associated with drought or shade were similar for both species; and within a treatment, both species had similar LSC. Species differed in the manner of LSC adjustment to drought and shade. Reductions in leaf area associated with drought or shade were accompanied primarily by reductions in potentially functional xylem area for L. tulipifera, and by reductions in flow velocity for Q. rubra. These results suggest (1) the existence of a homeostatic balance between evaporative flux and LSC, (2) that species with widely different growth patterns and xylem anatomies may develop similar LSC within the same environment, and (3) a possible hydraulic basis for differences in habitat between ring- and diffuse-porous species.

Drought adaptations and responses in five genotypes of Fraxinus pennsylvanica Marsh.: photosynthesis, water relations and leaf morphology.

Genotypic variation in photosynthesis and plant water relations during drought, and in leaf and seedling morphology were examined in greenhouse-grown Fraxinus pennsylvanica Marsh. (green ash) from five populations located along an east-west transect from New York State to South Dakota. During a 17-day drought, South Dakota seedlings, from the most xeric habitat, maintained the highest net photosynthesis and leaf conductance, and New York seedlings, from the most mesic habitat, exhibited the lowest net photosynthesis and leaf conductance. All populations except New York adjusted osmotically during the 17-day drought, by the end of which New York seedlings had the highest osmotic potentials at full and zero turgor. Tissue elasticity increased in New York seedlings, but decreased in Nebraska seedlings during the drought. Leaves of South Dakota seedlings were the most xerophytic. They were smaller in area and greater in thickness and specific mass than leaves of other sources. Leaves of New York seedlings were thinner than those of the other genotypes and among the largest. Seedlings from South Dakota were smaller than those of the other populations.

Effect of telephone follow-up on medication compliance.

This study compared the effectiveness, in improving patient compliance with a 10-14 day course of antibiotic therapy, of the following two strategies: (1) a follow-up telephone call and (2) written instructions and oral consultation by a pharmacist. The 82 study patients were randomly assigned to four groups: 1--control; 2--call-back; 3--written and oral consultation; and 4--written and oral consultation plus a call-back. The follow-up telephone call was made on the fourth or fifth day of the prescription course. The need to take the medication as directed and until completion was explained and reinforced. Any problems with the medication were determined. Compliance was assessed on the ninth or tenth day of therapy by a patient dosage unit count, and the patient's knowledge of the medication regimen was evaluated by a structured interview. The mean compliance was 76.6% for the control group, 86.6% for Group 2, 87.5% for Group 3, and 85.4% for Group 4. The compliance in the control group was significantly less than for each of the study groups (p = 0.0295), but the three study groups were not significantly different (p less than 0.05). Patients receiving written and oral consultation had significantly greater knowledge about side effects and what to do if they missed doses (p less than 0.002). After follow-up telephone call was equal to, but did not enhance, written and oral consultation in improving patient compliance.

Physician attitudes toward pharmacists counseling patients on adverse drug reactions.

The attitudes of physicians in a university teaching hospital toward pharmacist counseling of patients regarding adverse reactions to prescribed medications were studied. A questionnaire mailed to 120 physicians in each of the three groups affiliated with the Medical College of Virginia Hospitals (teaching faculty, house staff, and community practitioners with attending privileges) listed 56 potential adverse reactions associated with commonly prescribed medications in 13 therapeutic categories. For each physician group, half of the questionnaires pertained to inpatient and half to outpatient situations. The physicians were asked whether their patients should be informed about the possible reactions and, if so, if the physician alone, the pharmacist alone, or both should do the counseling. When "pharmacists only" and "both" data were combined for the 199 responses, over 50% of the respondents accepted pharmacists as patient counselors for all listed reactions except the three pertaining to antipsychotic agents. Class of medication significantly influenced attitude (p less than 0.05), with pharmacist participation in counseling being most acceptable for reactions involving anticoagulants, antibiotics, and analgesics, and least acceptable for those involving antipsychotics, cardiac glycosides, and antianxiety agents. Acceptability also was influenced by physician type (p less than 0.05), being lowest among community physicians, and was slightly higher in outpatient versus inpatient situations (p less than 0.05). The study indicates that physicians will accept pharmacist counseling with respect to adverse drug reactions, especially on a partnership basis.

Survey of departments of health about PKU screening programs.

Mailed questionnaires were used to examine the success of PKU (phenylketonuria) screening programs that were operated by departments of health and to examine differences between these programs. Of 55 departments, 44 were returned and 42 departments reported they had a PKU detection program. Thirty-eight respondents considered the PKU detection program to be effective, and 31 respondents indicated that the entire program cost $60,000 or less per year. The answers and comments on the questionnaires showed a generally positive view of the effectiveness about the value of the treatment program in general were also positive. However, a few departments indicated that more clinical evidence and experience were needed to fully evaluate the overall merits of PKU detection and screening programs.