Biomedical subjects

J J Alarcón

Publications and source records attributed to J J Alarcón.

4 recordsLinked to original sources

PubMed2007

Daily sap flow and maximum daily trunk shrinkage measurements for diagnosing water stress in early maturing peach trees during the post-harvest period.

We compared the sensitivity of two continuously recorded plant-based water stress indicators (sap flow, SF, and maximum daily trunk shrinkage, MDS) to detect changes in the water status of 4-year-old early maturing peach trees (Prunus persica (L.) Batsch cv. Flordastar grafted on GF-677 peach rootstock) during a cycle of deficit irrigation and recovery. The feasibility of obtaining SF and MDS reference equations for use in irrigation scheduling during the post-harvest period was also studied in trees irrigated in excess of crop water requirements. We found that MDS was a more sensitive and reliable detector of changes in plant water status than SF, making it a more precise tool for irrigation scheduling. Baseline relationships between SF or MDS and the climatic variables (air temperature, vapor pressure deficit (VPD) and crop reference evapotranspiration (ETo)) were established, despite some scatter in the data. Among the climatic variables, SF correlated more closely with ETo, whereas MDS correlated more closely with mean daily air temperature (T (m)). The fits of the regressions between MDS and ETo, midday air temperature and T (m) for individual periods were better than those obtained in the overall regressions, confirming that daily stem diameter variations must be considered not only in the context of plant water status but also in the context of plant carbon status.

Circadian Rhythm↗

PubMed2006

Subcellular effects of drought stress in Rosmarinus officinalis.

The use of Rosmarinus officinalis, and other wild plant species, in the Mediterranean area is an interesting solution in order to avoid the desertification and rapid soil erosion, because of their good resistance to environmental conditions. Previous articles have described experiments designed to determine the impact of water stress at the plant level in this species, but more knowledge is required at the subcellular and ultrastructural levels. An anatomic and ultrastructural study of the leaves was conducted on Rosmarinus officinalis plants growing under different water treatments. In the leaves of water-stressed plants, the leaf water potential and turgor decreased, and leaf osmotic potential became more negative with respect to control plants. The anatomic investigations showed that both the mesophyll intercellular spaces and the epidermal cell size were reduced significantly under the more intense drought stress conditions. At the subcellular level, chloroplasts accumulated plastoglobuli and lipid bodies, and cuticle thickness was increased under water stress. In our experiment, the anatomic and ultrastructural modifications of Rosmarinus officinalis could be considered an additional adaptation to drought stress together with physiological and biochemical modifications as antioxidant accumulation.

Acclimatization↗

PubMed1995

Localized right upper lobe edema.

One of the lesser known atypical forms of radiographic presentation of pulmonary edema is the isolated or predominant affection of the upper right lobe in patients with mitral valve insufficiency. As a possible cause of this distribution, it has been established that the regurgitation jet during the ventricular systole may be directed selectively toward the orifice of the right upper lobe vein, locally accentuating the forces responsible for edema formation. There are few cases with these characteristics in the literature reviewed. We present an additional three cases, concluding that localized pulmonary edema secondary to mitral insufficiency should be suspected in the presence of any type of airspace consolidation in the right upper lobe, with or without associated affection of the middle lobe, in patients with a history of mitral valve insufficiency, especially when there are radiologic signs of left heart failure.

Adult↗

PubMed1992

Intracranial tuberculosis in AIDS: CT and MRI findings.

CT and MRI findings in 35 patients with the acquired immune deficiency syndrome (AIDS) and proven intracranial tuberculosis (TB) are presented. Over 90% of the patients were intravenous drug abusers and in two-thirds TB was the first manifestation of AIDS. CT was normal in one quarter, the most frequent findings being hydrocephalus (51%) and meningeal enhancement (41%), commonly seen together (31.5%). Meningeal enhancement was seen in 48% of the CT studies with intravenous contrast medium and in 3 cases studied with MRI and i.v. gadolinium DTPA, in 2 of which CT was negative. Parenchymal involvement was found in 37% of cases; MRI was more sensitive than CT for its detection. One quarter of the patients had ischaemic lesions, mainly in the basal ganglia. We confirm the usefulness of CT and the superiority of MRI in the diagnosis of intracranial TB and in differential diagnosis from other conditions likely to be found in these patients.

Acquired Immunodeficiency Syndrome↗