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Abstract The metabolic consequences of long-term carbohydrate depletion have been well documented in many sink organs but not extensively in fruit. Therefore, in the present study the response to sugar limitation in tomato fruit (Lycopersicon esculentum Mill.) was investigated at two developmental stages; during the cell division and cell expansion phases. First, the response in excised fruit cultured in vitro was characterized. Sugar depletion caused an arrest of growth and an exhaustion of carbon reserves. The proteins that were degraded and the nitrogen released was transiently stored as asparagine and glutamine in both developmental stages and also as γ -aminobutyric acid (GABA) in expanding fruit. Fruit at the cell division stage appeared to be more sensitive to sugar limitation. The response to sugar depletion was then characterized in fruit from plants submitted to extended darkness. In planta , the effects of sugar-limitation were similar to those described in vitro but much more attenuated, especially in expanding fruit, which still accumulated dry matter. The expression of cell cycle genes, sugar- and nitrogen-related genes was reduced by darkness. Only asparagine synthetase gene expression was induced in both dark-treated fruit. Together the present data revealed that the effects of the carbon limitation are more pronounced in the youngest fruits as it is probably controlled by the relative sink strength of the fruit. [ABSTRACT FROM AUTHOR]

The contribution of the starch and soluble carbohydrate pools to the diurnal variations of leaf mass per unit area (LMA) has been investigated in tomato leaves. A glasshouse experiment was carried out with plants pruned to two or five fruits per truss. Leaflets were sampled at sunrise. noon and sunset at different positions within the leaf (basal or terminal), and on different sympods along the stem. Carbohydrate contents and LMA were significantly higher in the terminal than in the basal leaflets, except at sunrise. During the day, differences in starch accumulation between terminal and basal leaflets increased with leaf height on the plant. Among sympods, the soluble carbohydrate content of the terminal leaflets did not vary significantly, whereas at 13.00 h the LMA was minimum in the middle of the plant and maximum at the top, and the leaf starch content significantly increased half-way up the plant. The plant fruit load had only small and non-significant effects on the LMA and carbohydrate contents. The response of LMA and carbohydrate contents to changing source activity was observed under controlled climatic conditions. The starch pool of fully expanded leaves was rapidly tilled and emptied under increasing and decreasing source activity. In young expanding leaves, this pool was hardly filled during daylight. On average the soluble carbohydrates did not contribute significantly to the diurnal variations in LMA, whereas fluctuations in starch explained c. 70%, and 44% of these variations in the upper and lower leaves, respectively. The results are discussed with respect to the modelling of LMA at the level of individual tomato leaves or sympods. [ABSTRACT FROM AUTHOR]

The article presents a letter to the editor about acinar cell carcinoma of the pancreas.

We report a retrospective immunohistochemical study on bone marrow biopsies of 43 patients with different types of lymphomas showing unusual intrasinusoidal infiltration. Most of these patients presented with splenomegaly (74.4%) and peripheral lymphocytosis (83%). In 20/43 patients, lymphoid infiltrates were not detectable on haematoxylin-eosin sections. After immunohistochemistry on bone marrow biopsies and blood and bone marrow smear examinations, the following diagnoses were made: splenic marginal zone lymphoma with villous lymphocytes (SLVL) in 24 patients, large granular lymphocyte (LGL) leukaemia in 14 patients, hepatosplenic T-cell lymphoma in two patients, anaplastic large cell lymphoma in two patients and intravascular large B-cell lymphoma in one patient. In the presence of intrasinusoidal infiltrates of small lymphocytes, a B-cell phenotype (CD20+, CD76/DBA44+/-) was associated with splenic marginal zone lymphoma whereas intrasinusoidal CD3/CD45RA-positive T-cell infiltrates were strongly suggestive of LGL leukaemia. Intrasinusoidal bone marrow infiltration appears to be a common feature of distinct lymphoma subtypes. Immunohistochemical analysis is essential to detect intrasinusoidal medullary infiltrates (which may be minimal) and should be systematically performed in patients with splenomegaly and peripheral lymphocytosis.

The reasons why some patients with multiple myeloma (MM) do not develop severe bone loss, or even develop sclerotic bone lesions, remain unclear. In order to answer this question at the cellular and tissue level, we evaluated the histological bone condition of 10 patients with MM who never developed lytic bone lesions during the course of their disease (including two patients with sclerotic MM). Myeloma-induced bone changes in the close vicinity of myeloma cells were evaluated by quantitative histology (bone histomorphometry). All 10 patients presented a significantly increased osteoblastic activity. This was associated with an increased bone resorption in seven of the 10 cases. Three patients had a pure osteoblastic presentation. These features were the reverse of the pattern observed in seven patients with lytic bone lesions: increased bone resorption with decreased bone formation. Almost all of these 10 patients showing excessive osteoblastic activity had increased serum bone gla protein levels, a specific marker of bone formation. Finally, 90% of these patients were lambda MM (70% of them were IgG lambda MM), an immunoglobulin subtype previously associated with the sclerotic MM variants. In conclusion, a subset of patients with MM never develop severe bone loss because of the stimulation of osteoblastic activity. These patients belong to the same family as osteosclerotic MM, presenting more frequently the IgG type and lambda subtype.

Multiple myeloma (MM) is characterized by the presence of lytic bone lesion and frequent hypercalcaemia. These are due to an excessive osteoclastic resorption in association with a low bone formation, as demonstrated by bone histomorphometry. Conversely, B-cell malignancies other than MM are rarely associated with lytic bone lesion and/or hypercalcaemia. In this study we have analysed quantitative bone histology in 65 patients with B-cell malignancies other than MM at diagnosis: chronic lymphocytic leukaemia (CLL, n = 20), non-Hodgkin's lymphoma (NHL, n = 25), Waldenström's disease (WD, n = 14), hairy cell leukaemia (HCL, n = 6). Fifty patients presented no clinical evidence of increased bone resorption, including no lytic bone lesions radiologically detectable and/or no hypercalcaemia. 80% of these patients (40/50) had increased bone resorption parameter using quantitative bone histology, including 19/29 (65.5%) patients with CLL or WD and 21/21 (100%) patients with NHL or HCL (P less than 0.01). As a control group, seven patients lacking bone marrow involvement on bone sample presented no excessive bone resorption. However, eight patients presented lytic bone lesions and/or hypercalcaemia. All of these patients had increased resorption parameters with high numbers of osteoclasts per surface trabecular bone (mean = 35.3), as opposed to the patients lacking lytic bone lesions and/or hypercalcaemia (mean = 6.6, n = 28) and to normal individuals (mean +/- SD = 3.8 +/- 1.7 and 6.3 +/- 2.6, respectively before and after 60 years). In all the cases, excessive histologic bone resorption was mediated by mononuclear small osteoclasts (mean osteoclast length +/- SD = 27.3 +/- 4.1 as compared to normal range = 35.0 +/- 1.0, P less than 0.001). In different in vitro models, these small mononuclear osteoclasts are considered as progenitors. These data suggest an abnormal osteoclast differentiation in B-cell malignancies other than MM, probably due to differences in the production of local factors acting on bone remodelling.

We describe a rheumatoid arthritis patient who was found to have chronic T cell lymphocytosis and neutropenia. She had an increased number of lymphocytes in the peripheral blood, bone marrow, and liver, and the expanded lymphocyte subset consisted of large granular lymphocytes with a homogeneous phenotype. Of the previously described patients with these large granular lymphocytes, almost one-fourth have had rheumatoid arthritis.