Cytokine reduction in the treatment of joint conditions

The destruction of joints caused by rheumatoid arthritis and osteoarthritis is characterized by an imbalance of enzyme catalysed cartilage breakdown and regeneration. A complex cytokine network perpetuates joint conditions by direct regulation of metalloproteases, by indirect recruitment of cells that secrete degradative enzymes, and by inhibition of reparative processes. The destructive action of cytokines such as interleukin-1, interleukin-6 and tumour necrosis factor-alpha can be modulated at multiple points associated either with cytokine production or with cytokine action. Potential agents for cytokine reduction include selective anti-cytokine antibodies, anticytokine receptor antibodies, cytokine receptor antagonist proteins, and soluble and chimeric cytokine receptor molecules. Pharmacologic regulation of IL-1 and TNFalpha remain primary targets for treatment of arthritis, and results of early clinical trials are promising. However, the results of long-term clinical trials will be required to support the value of anti-cytokine therapy in treatment of arthritis.     

Production and characterization of a monoclonal antibody able to discriminate galectin-1 from galectin-2 and galectin-3

Antisera raised against galectin-1 exhibit crossreactivities with other galectins or related molecules. In order to overcome this problem, a monoclonal antibody to human brain galectin-1 was obtained by selecting clones without reactivity toward galectin-3. This mAb specifically bound galectin-1 of various animal origins but neither galectin-2 nor galectin-3. Western-blotting analysis of soluble human brain extracts after 2D gel electrophoresis revealed only the two most acidic isoforms of galectin-1. The ability of this mAb to bind galectin-1/asialofetuin complexes indicates that its epitope is not localized in the carbohydrate recognition domain of galectin-1. This particularity induces with efficiency its monospecificity.      

Blue Light Overrides Repression of Asexual Sporulation by Mating Type Genes in the Basidiomycete Coprinus cinereus

Monokaryotic mycelia of the homobasidiomycete Coprinus cinereus form asexual spores (oidia) constitutively in abundant numbers. Mycelia with mutations in both mating type loci (Amut Bmut homokaryons) also produce copious oidia but only when exposed to blue light. We used such an Amut Bmut homokaryon to define environmental and inherent factors that influence the light-induced oidiation process. We show that the Amut function causes repression of oidiation in the dark and that light overrides this effect. Similarly, compatible genes from different haplotypes of the A mating type locus repress sporulation in the dark and not in the light. Compatible products of the B mating type locus reduce the outcome of light on A-mediated repression but the mutated B function present in the Amut Bmut homokaryons is not effective. In dikaryons, the coordinated regulation of asexual sporulation by compatible A and B mating type genes results in moderate oidia production in light. Copyright 1998 Academic Press.     

Regulation of iron uptake in Saccharomyces cerevisiae. The ferrireductase and Fe(II) transporter are regulated independently.

Iron is required for the growth of Saccharomyces cerevisiae. High concentrations of iron, however, are toxic, forcing this yeast to tightly regulate its concentration of intracellular free iron. We demonstrate that S. cerevisiae accumulates iron through the combined action of a plasma membrane ferrireductase and an Fe(II) transporter. This transporter is highly selective for Fe(II). Several other transition metals did not inhibit iron uptake when these metals were present at a concentration 100-fold higher than the Km (0.15 microM) for iron transport. Pt(II) inhibited ferrireductase activity but not the ability of cells to transport iron that was chemically reduced to Fe(II). Incubation of cells in a synthetic iron-limited media resulted in the induction of both ferrireductase and Fe(II) transporter activities. In complex media, Fe(II) transport activity was regulated in response to media iron concentration, while the activity of the ferrireductase was not. When stationary phase cells were inoculated into fresh media, ferrireductase activity increased independent of the iron content of the media; in contrast, transporter activity varied inversely with iron levels. These results demonstrate that the ferrireductase and Fe(II) transporter are separately regulated and that iron accumulation may be limited by changes in either activity.     

A new polymorphic site in the G6PD gene

Summary A polymorphic restriction site has been found in intron 11 of the gene for glucose-6-phosphate dehydrogenase (G6PD). This site is produced by a TC substitution 13 bp upstream of exon 12, producing an NlaIII restriction site. In various populations there was a strong association between a T at nt 1311 of the G6PD cDNA and the presence of the NlaIII restriction site. Among African Americans, however, the presence of a C at nt 1311 was sometimes associated with the presence of a polymorphic NlaIII site.     

Hydraulic adjustment of maple saplings to canopy gap formation

The leaf-specific hydraulic conductivity (K _L) of plant stems can control leaf water supply. This property is influenced by variation in leaf/sapwood area ratio (A _L/A _S) and the specific hydraulic conductivity of xylem tissue (K _S). In environments with high atmospheric vapor pressure deficit (VPD), K _L may increase to support higher transpiration rates. We predicted that saplings of Acerrubrum and A.pensylvanicum grown in forest canopy gaps, under high light and VPD, would have higher K _L and lower A _L/A _S than similar sized saplings in the understory. Leaf-specific hydraulic conductivity and K _S increased with sapling size for both species. In A. rubrum, K _S did not differ between the two environments but lower A _L/A _S (P=0.05, ANCOVA) led to higher K _L for gap-grown saplings (P < 0.05, ANCOVA). In A. pensylvanicum, neither K _S, A _L/A _S, nor K_L differed between environments. In a second experiment, we examined the impact of sapling size on the water relations and carbon assimilation of A.pensylvanicum. Maximum stomatal conductance for A.pensylvanicum increased with K _L (r ²=0.75, P < 0.05). A hypothetical large A. pensylvanicum sapling (2 m tall) had 2.4 times higher K _L and 22 times greater daily carbon assimilation than a small (1 m tall) sapling. Size-related hydraulic limitations in A.pensylvanicum caused a 68% reduction in daily carbon assimilation in small saplings. Mid-day water potential increased with A.pensylvanicum sapling size (r ²=0.69, P < 0.05). Calculations indicated that small A.pensylvanicum saplings (low K _L) could not transpire at the rate of large saplings (high K _L) without reaching theoretical thresholds for xylem embolism induction. The coordination between K _L and stomatal conductance in saplings may prevent xylem water potential from reaching levels that cause embolism but also limits transpiration. The K _S of the xylem did not vary across environments, suggesting that altering biomass allocation is the primary mechanism of increasing K _L. However, the ability to alter aboveground biomass allocation in response to canopy gaps is species-specific. As a result of the increase in K _L and K _S with sapling size for both species, hydraulic limitation of water flux may impose a greater restriction on daily carbon assimilation for small saplings in the gap environment. Received: 18 February 1997 / Accepted: 23 June 1997     

Intraspecific variation in samara morphology and flight behavior in acer saccharinum (Aceraceae)

We studied intraspecific variation in samara morphology and flight behavior within and among parent trees of Acer saccharinum (silver maple), with a particular focus on the effect of samara shape. Samara mass, area, wing loading, and descent rate from a 4.5-m indoor balcony were measured for 50 undamaged mature samaras from each of six parents. We found significant differences among parental types for all morphological variables and descent rate. These differences yielded a 50% range in mean dispersal potential among the six parents. There was a strong linear correlation between descent rate and square root of wing loading when mean values were plotted for each of the six parental types. But there was considerable within-parent variation for all measured variables, including substantial nonallometric variation in wing loading caused in part by poor correlations between wing area and fruit weight. Parents also differed widely in the relationship between square root of wing loading and descent rate (linear r² = 0.150-0.788), with one parental type showing no significant relationship. Fruits from the same parent with similar values of the square root of wing loading showed as much as a 75-100% difference in descent rate. The usefulness of mass : area indices such as wing loading is limited by its exclusion of aerodynamically important factors such as mass distribution and wing shape, which in our case caused the six parents to behave aerodynamically almost as if they were six separate species.     

An anchored restriction-mapping approach applied to the genetic analysis of the Anopheles gambiae malaria vector complex 1

We introduce here a simple approach for rapidly determining restriction maps for a number of regions of a genome; this involves "anchoring" a map with a rare restriction site (in this case the seldom-cutting EagI) followed by partial digestion of a frequent-cutting enzyme (e.g., Sau 3A). We applied this technology to five species of the Anopheles gambiae complex. In a single Southern blot we obtained about a 15-kb restriction map each for the mtDNA, rRNA gene, and a scnDNA region for each of five species. Phylogenetic analyses of these regions yield trees at odds with the more traditional chromosome inversion-based trees. The value of the approach for systematic purposes is the ease with which several large, independent regions of the genome can be quickly assayed for molecular variation.      

Review: history of the amyloid fibril

Rudolph Virchow, in 1854, introduced and popularized the term amyloid to denote a macroscopic tissue abnormality that exhibited a positive iodine staining reaction. Subsequent light microscopic studies with polarizing optics demonstrated the inherent birefringence of amyloid deposits, a property that increased intensely after staining with Congo red dye. In 1959, electron microscopic examination of ultrathin sections of amyloidotic tissues revealed the presence of fibrils, indeterminate in length and, invariably, 80 to 100 A in width. Using the criteria of Congophilia and fibrillar morphology, 20 or more biochemically distinct forms of amyloid have been identified throughout the animal kingdom; each is specifically associated with a unique clinical syndrome. Fibrils, also 80 to 100 A in width, have been isolated from tissue homogenates using differential sedimentation or solubility. X-ray diffraction analysis revealed the fibrils to be ordered in the beta pleated sheet conformation, with the direction of the polypeptide backbone perpendicular to the fibril axis (cross beta structure). Because of the similar dimensions and tinctorial properties of the fibrils extracted from amyloid-laden tissues and amyloid fibrils in tissue sections, they have been assumed to be identical. However, the spatial relationship of proteoglycans and amyloid P component (AP), common to all forms of amyloid, to the putative protein only fibrils in tissues, has been unclear. Recently, it has been suggested that, in situ, amyloid fibrils are composed of proteoglycans and AP as well as amyloid proteins and thus resemble connective tissue microfibrils. Chemical and physical definition of the fibrils in tissues will be needed to relate the in vitro properties of amyloid protein fibrils to the pathogenesis of amyloid fibril formation in vivo.