Functional relationships between leaves and stem across canopy layers in two contrasting clones of Populus nigra L.

Populus nigra L. represents a model system for plant biology and has a productive interest in breeding for short rotation forestry. The growth potential and adaptive capacity of this species are well characterized, but the canopy effect is poorly investigated. We analyzed morphological and functional leaf traits across a multilayer canopy profile in two contrasting clones of this species, 58-861 and Poli, respectively from northern and southern Italy, grown in field plantation. The results revealed how the variation of leaf functional traits was structured within the canopy. The two clones showed differences in leaf morphology and water use efficiency, but organized a similar functional canopy structure along a vertical profile, related to a gradient of light radiation. An acropetal enrichment gradient of carbon stable isotope was found both in leaves and stem wood across a vertical canopy profile and a tight correlation was found between carbon stable isotopes of leaves and of the respective stem section. Such a functional relationship indicates that substrates for stem growth were sourced from leaf assimilates of the closest canopy layer. These results characterize the physiology of black poplar under micro-environmental conditions at intra-canopy scale and contribute to clarify the canopy effect in young trees.

Study of short-term plasticity in two contrasting genotypes of Populus nigra L.

Species like black poplar characterized by an indeterminate growth, can acclimate to the changing environmental conditions during the seasons through a modification of morphological and physiological features. The acclimation results fundamental for the increasing evapo-transpirative demand and water availability. In this perspective, each generation of leaf becomes an indicator of physiologic performance, determining the short-term plasticity (acclimation) of a genotype to different environmental conditions. The main objective of this work is to analyse the physiological adjustment by morphological and physiological features of leaves in two contrasting genotypes of Populus nigra L., growing in a common environment. The mesic genotype 58-861 (Northern Italy) reacts to the increasing dry conditions keeping constantly higher values of δ(13)C while the xeric genotype Poli (Southern Italy) shows lower values, despite no significant differences in the gas exchanges. Morphological and stomatal leaf traits were the main drivers of the different behaviour in the two genotypes to face the "temporal" environment, but different from the provenance. In particular the results, especially in the development phases, demonstrate how phenotypic plasticity is evident at seasonal scale, playing a role for the success of an indeterminate-growing species. They could also be generalized for similar experiments and could support further investigation about short-term plasticity.

Lung volume reduction surgery in lieu of pneumonectomy in an infant with severe unilateral pulmonary interstitial emphysema.

A male infant with a prenatal diagnosis (at 20 weeks' gestation) of cystic adenomatoid malformation was delivered after 38 weeks' gestation (birth weight, 3 kg) and admitted to the neonatal intensive care unit. During the first few days of life, he developed mild respiratory distress; a chest radiograph and computed tomography scan showed multiple cystic areas in the left lower lobe with hyperinflation and herniation of the upper lobe across the midline. At 3 weeks of age, a left lower lobectomy was performed for presumed cystic malformation. To our surprise the pathology reports revealed pulmonary interstitial emphysema. The postoperative chest radiograph was unchanged, and mechanical ventilation was necessary and required progressively increasing ventilatory settings to provide adequate support. High-frequency oscillatory ventilation and selective right bronchus intubation failed to improve lung function. After 3 weeks, a left thoracotomy was repeated and lung volume reduction was performed with removal of 50' of the peripheral hyperinflated parenchyma. Postoperative recovery was rapid; the child was weaned from the ventilator after 3 days and discharged after 3 weeks. Follow-up chest X-rays showed a normally expanded right lung with mediastinal structures back to midline and a small left lung. Favorable results persisted at 3 years of follow-up. This first and successful experience with lung volume reduction in a neonate suggests that infants who need removal of a large portion of lung parenchyma to achieve adequate ventilation and gas exchange, lung volume reduction surgery should be considered as an alternative to pneumonectomy.

Leaf area dynamics in a closed poplar plantation under free-air carbon dioxide enrichment.

Three Populus genotypes (P. alba L. (Clone 2AS-11), P. nigra L. (Clone Jean Pourtet) and P. x euramericana (Clone I-214)) growing in a managed, high-density forest plantation were exposed to free-air CO(2) enrichment (FACE) at CO(2) concentrations expected to occur in the future (550 ppm). Leaf area index (optical LAI), measured with a fish-eye-type plant canopy analyzer, was not significantly affected by FACE after canopy closure in the second growing season. However, when stands of similar size were compared, optical LAI and number of main stem leaves were reduced by FACE. Allometric relationships, which were established to scale-up leaf area to the stand level (allometric LAI), did not differ between the FACE and control plots. Allometric LAI increased in response to FACE, as a result of increased tree dimensions and increased individual leaf size. We postulate that, although FACE increased allometric LAI, FACE had no effect on optical LAI after canopy closure, because FACE caused increased shading and competition resulting in enhanced leaf fall or leaf turnover. Specific leaf area (SLA) was unaffected by FACE. Allometric relationships and relative responses to atmospheric CO(2) enrichment were genotype-dependent.

Carotid artery approach as an alternative to femoral access for balloon dilation of aortic valve stenosis in neonates and infants.

PURPOSE: to evaluate the efficacy of a right common carotid artery cutdown as alternative access in neonates and small infants requiring a balloon dilation of aortic valve stenosis. In infants, the femoral approach is limited by difficulties in advancing the catheter across the valve and by the risk of femoral artery injuries. METHODS: from January 1997 to July 2000, 16 infants at our department underwent balloon dilation through a carotid artery cutdown. Infant weight ranged from 2670 to 6450 g; mean weight 3967 g, and age ranged from 1 to 157 days, mean age 42,8 days. Fifteen of 16 infants had aortic valve stenosis; the remaining infant presented with a aortic coartation relapse. RESULTS: In 15 infants an adequate dilation of the valve was obtained with no complications. In only one infant an arterial intimal disconnection was caused by inadequate choice of surgical instruments. At the end of the procedure, the carotid arteries were reconstructed with interrupted 7-0 prolene stitches. There were no neurological sequaelae observed. All infants were followed-up and examined by echocolordoppler ultrasound: all carotid arteries were open with no significant stenosis. CONCLUSION: Our experience confirms that the carotid access proposed in 1973 by Azzolina et al is a valid and safe alternative to the usual percutaneous femoral access. In particular it could be useful in neonates and infants were the size of femoral vessels could facilitate important and dangerous complications.

[Values of white blood cell count in the diagnosis of acute appendicitis]. / Utilità della leucometria nella diagnosi di appendicite acuta.

BACKGROUND: The diagnosis of acute appendicitis remains a critical challenge for paediatric surgeons. White Blood Cell (WBC) count, once considered a basic exam, is still routinely performed in most institutions, despite its lack of accuracy. Aim of this study is to assess the additional value of WBC count in the diagnosis of acute appendicitis. METHODS: We retrospectively reviewed the charts of children who underwent appendectomy for acute appendicitis in the last two years at our institution. In the patients treated in 1999 (Group A), WBC count was assessed routinely after admission. The surgeons relied on leukocytosis as well as on clinical findings and on ultrasound abdominal scan for the diagnosis of acute appendicitis. In the patients treated in 2000 (Group B), blood cell count was not tested or deliberately ignored by the surgeons. RESULTS: There were 65 children in Group A and 70 in Group B; the two groups of patients were similar in terms of gender (p = 0.989) and age (p = 0.758). Criteria for operation were similar in the two groups (p = 0.222). No differences were found in the number of perforated (p = 0.989) and normal (p = 0.217) appendixes in the two groups as well as in the duration of hospital stay after surgery (p = 0.849). CONCLUSIONS: WBC count at admission has no proven additional value in the diagnosis of acute appendicitis and can be omitted without modifying diagnostic pathway and without affecting diagnostic accuracy.

Residual B-cell function in insulin-dependent (type I) diabetics with and without retinopathy.

In order to evaluate if residual B-cell function is a protecting factor against the development of diabetic retinopathy in type I diabetics we measured C-peptide levels before and after glucagon stimulation (1 mg i.v.) in 74 type I diabetics. In all patients retinopathy was assessed by fluorescein angiography and retinal lesions were classified as: grade 0, normal; grade 1, background retinopathy; grade 2, proliferative retinopathy. We then correlated the degree of retinopathy to sex, age, duration of diabetes, smoking, percentage of ideal body weight, systolic and diastolic blood pressure, serum cholesterol, triglycerides, creatinine and C-peptide by means of multiple linear regression analysis. Twenty-three out of 74 type I diabetics had retinopathy. In all 7 subjects with proliferative retinopathy duration of diabetes exceeded 10 years. There was significant correlation between retinopathy and duration of diabetes (r = 0.373, p less than 0.001). No correlation was found between retinopathy and all the other variables, in particular between retinopathy and basal C-peptide or C-peptide increment (delta). An inverse correlation was found between the increment of C-peptide and duration of diabetes (r = -0.404, p less than 0.01). Our data show that residual B-cell function cannot be considered a protecting factor against the development of diabetic retinopathy.

Axial and radial water flow in the trunks of oak trees: a quantitative and qualitative analysis.

Axial water flow in the trunks of mature oak trees (Quercus petraea (Matt.) Liebl. and Q. robur L.) was studied by four independent techniques: water absorption from a cut trunk, sap flowmeters, heat pulse velocity (HPV) and thermoimaging. Estimation of the total water flow with sap flowmeters, HPV and water absorption yielded comparable results. We concluded from dye colorations, thermograms and axial profiles of sap flow and heat pulse velocity that, in intact trunks, most of the flow occurred in the current-year ring, where early-wood vessels in the outermost ring were still functional. Nevertheless, there was significant flow in the older rings of the xylem. Total water flow through the trunk was only slightly reduced when air embolisms were artificially induced in early-wood vessels, probably because there was little change in hydraulic conductance in the root-leaf sap pathway. Embolization of the current-year vessels reactivated transport in the older rings.