Coxsackievirus A21 binds to decay-accelerating factor but requires intercellular adhesion molecule 1 for cell entry.

It is becoming increasingly apparent that many viruses employ multiple receptor molecules in their cell entry mechanisms. The human enterovirus coxsackievirus A21 (CAV21) has been reported to bind to the N-terminal domain of intercellular adhesion molecule 1 (ICAM-1) and undergo limited replication in ICAM-1-expressing murine L cells. In this study, we show that in addition to binding to ICAM-1, CAV21 binds to the first short consensus repeat (SCR) of decay-accelerating factor (DAF). Dual antibody blockade using both anti-ICAM-1 (domain 1) and anti-DAF (SCR1) monoclonal antibodies (MAbs) is required to completely abolish binding and replication of high-titered CAV21. However, the binding of CAV21 to DAF, unlike that to ICAM-1, does not initiate a productive cell infection. The capacity of an anti-DAF (SCR3) MAb to block CAV21 infection but not binding, coupled with immunoprecipitation data from chemical cross-linking studies, indicates that DAF and ICAM-1 are closely associated on the cell surface. It is therefore suggested that DAF may function as a low-affinity attachment receptor either enhancing viral presentation or providing a viral sequestration site for subsequent high-affinity binding to ICAM-1.     

Chemistry and microbial activity of forest and pasture riparian-zone soils along three Pacific Northwest streams

Throughout the United States, agricultural practices are responsible for large quantities of nutrients entering lakes and streams. Previous studies have shown that forested riparian areas can filter nutrients from surface runoff and groundwater that may potentially contaminate lakes and streams. This study examined seasonal differences in soil chemistry and soil microorganisms in paired mixed-forest riparian and pasture systems, the aim being to gain understanding of the sequestering of N and P. The forest soils retained higher levels of organic C and N, mineralizable N, extractable P, and fungal biomass, and had higher respiration rates than pasture soils. These findings suggest that forested riparian zones have a greater capacity than pasture soils to sequester C and retain nutrients. In past studies, fungal biomass has been shown to be less than bacterial biomass in grassland soils, but in this study, fungal biomass was greater than bacterial biomass throughout the year in both forest and pasture soils.     

Cross-Linking of Fibronectin to C-Terminal Fragments of the Fibrinogen α-Chain by Factor XIIIa

Fibronectin binds specifically to fibrin and is covalently cross-linked to the fibrin α chain by activated factor XIII (XIIIa). This reaction is important for wound healing. Here we investigate XIIIa-catalyzed cross-linking of fibronectin and some of its fragments to a recombinant fragment representing the COOH-terminal 30kDa of the fibrin α chain (αC30K:His 368–Val 610). Only fibronectin and those fragments containing an intact NH₂-terminus were able to form cross-linked complexes. As many as 10 of the 17 lysines in αC30K can serve as amine donors in this reaction. Analysis of the rate of XIIIa-catalyzed cross-linking of fibronectin NH₂-terminal peptides and fragments with αC30K revealed that the presence of the first type I “finger” module accelerates the cross-linking reaction; addition of fingers 2–5 had no further effect.     

Two Cases of Cryptococcal Meningitis,one Treated with 5-Fluorocytosine

Cryptococcal meningitis occurred in two patients in the North of England. One, an elderly woman who was ill for 12 months with an obscure indolent meningitis until use of steroid drugs resulted in an acute exacerbation during which cryptococci were isolated, was treated successfully with amphotericin B. The other, a student from New Guinea with subacute meningitis, could not tolerate amphotericin B but responded to two courses of oral treatment with 5-fluorocytosine 100–200 mg./kg./ day without any appreciable side-effects. Further trials of this drug in the treatment of cryptococcosis are recommended.     

Reversible unfolding of an isolated heparin and DNA binding fragment, the first type III module from fibronectin.

Several fragments containing all or part of the first type III homology unit of fibronectin were isolated and their folding properties examined by fluorescence spectroscopy and differential scanning calorimetry. Each fragment exhibits a reversible unfolding transition when heated or titrated with guanidinium chloride. This indicates that an isolated type III module can fold independently in the absence of neighboring modules. A comparison of the specific enthalpies of unfolding of these fragments with those of well-studied globular proteins suggests that this type III unit is composed of a stable core flanked by less compact or unstructured regions. Comparison of the heparin-binding properties of these fragments revealed that removal of 12 amino acids from the amino terminus of the largest one (Ile-585 to Val-675) increased its affinity for immobilized heparin such that it now binds at physiological ionic strength.     

Phosphatase activity ofPenicillium citrinum submerged batch cultures and its relationship to fungal activity

Acid and alkaline phosphatase activities were evaluated using batch fermenter cultues ofPenicillium citrinum, an organism used in studies of fungal functioning in soil. Fungal activity was assessed by monitoring rates of O₂ utilization, glucose utilization, dry weight changes over time, and lengths of FDA-stained hyphae. At low growth rates (7 g dry wt increases·h^–1·ml^–1) and low culture activity, phosphatase activity at both pH 8.5 and 5.5 tended to decrease with culture age, with the exception that phosphatase activity at pH 8.5 peaked during early stationary phase. At higher growth rates (25 g dry wt increase·h^–1·ml^–1) and high culture activity, phosphatase activity tended to remain constant throughout the course of the experiment. The relationship between phosphatase activity and other measures of fungal activity was consistent only at low growth rates for acid phosphatase. These results suggest that phosphatase measurements will be of limited utility in assessing activity, except at low growth rates.     

Hypophosphataemic osteomalacia in patients receiving haemodialysis.

Four patients had symptomless osteomalacia at the time of starting regular haemodialysis. After 21-40 months they became hypophosphataemic and developed disabling skeletal symptoms. In each case an exacerbation of histological osteomalacia was shown. Symptoms improved after measures designed to raise serum inorganic phosphate concentrations or vitamin D administration, or both. Patients undergoing maintenance haemodialysis should have their serum phosphate and alkaline phosphatase levels monitored every month. Predialysis phosphate levels below 1 mmol/1 (3 mg/100 ml) and rising serum alkaline phosphatase concentrations are danger signals. If the diagnosis is confirmed early aggressive treatment should be started.