Nutrients cause grassland biomass to outpace herbivory.

Human activities are transforming grassland biomass via changing climate, elemental nutrients, and herbivory. Theory predicts that food-limited herbivores will consume any additional biomass stimulated by nutrient inputs ('consumer-controlled'). Alternatively, nutrient supply is predicted to increase biomass where herbivores alter community composition or are limited by factors other than food ('resource-controlled'). Using an experiment replicated in 58 grasslands spanning six continents, we show that nutrient addition and vertebrate herbivore exclusion each caused sustained increases in aboveground live biomass over a decade, but consumer control was weak. However, at sites with high vertebrate grazing intensity or domestic livestock, herbivores consumed the additional fertilization-induced biomass, supporting the consumer-controlled prediction. Herbivores most effectively reduced the additional live biomass at sites with low precipitation or high ambient soil nitrogen. Overall, these experimental results suggest that grassland biomass will outstrip wild herbivore control as human activities increase elemental nutrient supply, with widespread consequences for grazing and fire risk.

Conserving evolutionary history does not result in greater diversity over geological time scales.

Alternative prioritization strategies have been proposed to safeguard biodiversity over macroevolutionary time scales. The first prioritizes the most distantly related species-maximizing phylogenetic diversity (PD)-in the hopes of capturing at least some lineages that will successfully diversify into the future. The second prioritizes lineages that are currently speciating, in the hopes that successful lineages will continue to generate species into the future. These contrasting schemes also map onto contrasting predictions about the role of slow diversifiers in the production of biodiversity over palaeontological time scales. We consider the performance of the two schemes across 10 dated species-level palaeo-phylogenetic trees ranging from Foraminifera to dinosaurs. We find that prioritizing PD for conservation generally led to fewer subsequent lineages, while prioritizing diversifiers led to modestly more subsequent diversity, compared with random sets of lineages. Importantly for conservation, the tree shape when decisions are made cannot predict which scheme will be most successful. These patterns are inconsistent with the notion that long-lived lineages are the source of new species. While there may be sound reasons for prioritizing PD for conservation, long-term species production might not be one of them.

The value of clonality in the diagnosis and follow-up of patients with cutaneous T-cell infiltrates.

The diagnosis of early stages of cutaneous T-cell lymphoma (CTCL) is often difficult, especially for lesions that are at the borderline between reactive and neoplastic skin T-cell infiltrates. T-cell monoclonality in these lesions is considered by some to be an important prognostic factor of neoplastic evolution, whereas others claim that clonality can also be found in benign skin infiltrates and is therefore of limited diagnostic value. To address this controversy, the authors analyzed retrospectively eight patients with lymphocytic skin lesions who progressed to CTCL, and three patients with recurrent T-cell lymphocytic infiltrates who had not developed CTCL. From a total of 65 biopsies of eight progressing patients, 32 were diagnosed as histologically malignant and 33 were diagnosed as benign or borderline. The authors found clonality by either polymerase chain reaction or Southern blot analysis in 88% of malignant and in 79% of nonmalignant lesions. None of the 37 biopsies of non-progressing patients was clonal. These results indicate strongly that the presence of monoclonality in T-cell skin infiltrates is related closely to the risk of developing CTCL. The value of clonality as a marker of malignancy is supported by the absence of T-cell clonal populations in all infiltrates from patients who had not progressed to lymphoma.

Expression and cytokine regulation of glucocorticoid receptors in Kaposi's sarcoma.

Development of Kaposi's sarcoma (KS) after glucocorticoid therapy has been observed in a variety of clinical states including human immunodeficiency virus-1 infection and recent in vitro studies provided evidence for a direct stimulation effect of glucocorticoid hormones on KS cell proliferation. The importance of glucocorticoids in KS pathogenesis is further highlighted by the finding that glucocorticoids synergize with cytokines to promote acquired immune deficiency syndrome (AIDS)-associated KS (AIDS-KS) growth. Furthermore, cytokine effects were abrogated by the glucocorticoid antagonist RU-486. As glucocorticoid action is mediated through activation of their intracellular cognate receptors, we hypothesized that enhanced responsiveness of AIDS-KS cells to glucocorticoids may be due to elevated glucocorticoid receptor (GR) content. Indeed, high expression of GRs in AIDS-KS tumor biopsies was detected both at the level of mRNA and protein. Quantitative measurements of GRs in these specimens by a sensitive immunoassay showed that GR content was significantly elevated in the tumor tissue (4663 fmol/mg protein) compared with the uninvolved skin of the same patients (2777 fmol/mg protein), both of which were markedly above the normal skin of healthy donors (893 fmol/mg protein). Immunocytochemical analysis confirmed the presence of GRs in the cytoplasm and the nucleus of KS cells. Interestingly, four major KS cytokines, namely interleukin-1beta, interleukin-6, tumor necrosis factor-alpha, and oncostatin M, all of which are known autocrine growth factors for AIDS-KS cells, significantly increased the expression of functional GRs in cultured AIDS-KS cells. The latter result may explain, at least in part, the synergistic effect of glucocorticoid and oncostatin M on AIDS-KS cell proliferation. Thus, the high levels of GR expression in AIDS-KS and the up-regulation of GRs by KS-growth-promoting factors may confer enhanced and sustained sensitivity to the stimulatory effects of glucocorticoids. The data presented also provide molecular bases for therapeutic interventions targeting GRs in this disease.

[Fibrofolliculoma. Treatment with copper vapor laser]. / Le fibrofolliculome. Traitement par laser à vapeur de cuivre.

There are many clinical presentations to fibrofolliculoma, described by Birt, Hogg and Dubé: the solitary and multiple forms, with or without other skin tumors, could also be markers of intestinal polyposis. Little is known of its pathogenesis. A case of multiple fibrofolliculoma of the face and neck is described. A new therapeutic approach by copper vapour laser is proposed.

Colon cancer in seven siblings.

In a case-control study of cancer of the colon it was found that 96 out of 332 (29%) cases had a positive family history of cancer of the colon (2 cases and more) as compared with 19 out of 473 (4%) controls. 3 colon cancer cases reported that 6 of their respective relatives were also affected with the same cancer. We were able to do a complete follow-up study of one family where 7 out of 12 sibling (P < 0.05) had confirmed pathological diagnoses of cancer of the colon. The mean age at diagnosis among these familial colon cancer cases was 64 years (60 years for females and 73 years for males) and all tumours were located in the caecum or right colon (a common characteristic of colon cancer in this family). There was no history of familial adenomatous polyposis in this family. It is unlikely that the significantly high proportion of familial colon cancer found could be due to chance. This suggests that both environmental and genetic factors play an important role in the aetiology of colon cancer.

Family aggregation of cancer of the prostate in Quebec: the tip of the iceberg.

Cancer of the prostate is one of the most common cancers among males in North America. Although some causative factors have been suggested by several surveys, the etiology of this common cancer is poorly understood. In a case-control study of prostatic cancer in Greater Montreal, 21 of 140 patients with prostatic cancer (15.0%) gave a positive family history of the same cancer, as compared with two cases among 101 (2.0%) population-based controls. This indicates about an eightfold difference in occurrence of cancer of the prostate among first-degree family members of the case group with an odds ratio (OR) of 8.7 and 95% CI, 2.00-38.17. In this report we present the pedigrees of three families (two cases and one control) with four pathologically confirmed cases of cancer of the prostate in each family. This data suggest that a familial predisposition to prostatic cancer may become apparent in later decades of life. In these family aggregations, in addition to the genetic factors, environmental factors may also play an important role in the etiology of the same cancer among family members.

A man with isochromosome Xq Klinefelter syndrome with lack of height increase and normal androgenization.

We report on a patient with Klinefelter syndrome (KS) and the homogeneous aneuploidy 47,Xi(Xq)Y, or male trisomy Xq. He had many characteristics of classical KS: small testes, azoospermia, elevated FSH and LH, average intelligence, and normal androgenization, but his stature was not increased, compared with his father's and brothers'. The i(Xq), found in all cells analyzed, was late-replicating, monocentric, and also asymmetric for the RBG-banding of the two arms, indicating a different chronology of DNA synthesis in each arm. When indicated, in the seven previously reported cases, the level of plasma testosterone was always subnormal; it was normal (650 ng/100 ml) in our patient, who had normal masculinization. Thus the level of testosterone among patients with KS is not necessarily lower with an extra Xq. Furthermore, the sharp contrast in the height of KS patients with or without an i(Xq) is striking. It appears definitely possible to associate the isochromosome Xq Klinefelter syndrome with a lack of height increase.