Identity and synthesis of prostaglandins in the lone star tick, Amblyomma americanum (L.), as assessed by radio-immunoassay and gas chromatography/mass spectrometry.

High concentrations of PGE(2) and PGF(2alpha) were identified by radio-immunoassay (RIA) and/or gas chromatography/mass spectrometry (GC/MS) in the hemolymph, salivary glands and saliva of the lone star tick Amblyomma americanum (L.). Binding studies indicated that PGE(2) was free and not bound to any proteins in the hemolymph. A small amount of 6-keto-PGF(1alpha) (breakdown product of PGI(2); prostacyclin) was also found in the salivary glands but not in the hemolymph or saliva. Neither PGD(2) nor PGA(2)/B(2) was detected in any tick material investigated. Although PGE(2) was found in the gut contents, only small amounts of label crossed the gut into the hemolymph during artificial feeding with labeled PGE(2), indicating that the high amounts of PGE(2) in hemolymph and salivary glands are not sequestered from the host blood meal. Isolated salivary glands and salivary gland homogenates demonstrated robust synthesis of PGE(2) at high concentrations of exogenous arachidonic acid. Synthesis by the salivary glands was monitored by measuring increasing PGE(2) with increasing arachidonic acid by RIA, GC/MS and labeled PGE(2) in the presence of labeled arachidonic acid. Synthesis was inhibited in a dose-dependent manner by indomethacin indicating that the cyclooxygenase synthesizing prostaglandins in ticks shares similarities to the enzyme found in mammals.     

Experience in the application of Java Technologies in telemedicine

Java language has been demonstrated to be an effective tool in supporting medical image viewing in Russia. This evaluation was completed by obtaining a maximum of 20 images, depending on the client's computer workstation from one patient using a commercially available computer tomography (CT) scanner. The images were compared against standard CT images that were viewed at the site of capture. There was no appreciable difference. The client side is a lightweight component that provides an intuitive interface for end users. Each image is loaded in its own thread and the user can begin work after the first image has been loaded. This feature is especially useful on slow connection speed, 9.6 Kbps for example. The server side, which is implemented by the Java Servlet Engine works more effective than common gateway interface (CGI) programs do. Advantages of the Java Technology place this program on the next level of application development. This paper presents a unique application of Java in telemedicine.     

Analysis of lipids in the salivary glands of Amblyomma americanum (L.): Detection of a high level of arachidonic acid

Analysis of lipids in salivary glands of the lone star tick, Amblyomma americanum, demonstrated that arachidonic acid (20:4, n-6) comprises 8% of all fatty acids identified by gas chromatography. The occurrence of arachidonic acid and other C₂₀ polyunsaturated fatty acids in tick salivary glands was confirmed by gas chromatography-mass spectrometry. Arachidonate is located entirely in the phospholipid fraction and is associated exclusively with phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Salivary glands stored and frozen for several months had a similar lipid composition as freshly dissected salivary glands, with the exception of a small amount of free arachidonic acid and an increase in lysophosphatidylcholine. Incubation of salivary gland homogenates with snake venom phospholipase A₂ showed that most saturated fatty acids are esterified in the sn-1 position of PC and PE, with the unsaturated fatty acids in the sn-2 position. Approximately 75% of arachidonic acid is in the sn-2 position of PC and PE, adding support to the hypothesis that arachidonic acid is released into the cytoplasm after activation of a phospholipase A₂ for subsequent metabolism to prostaglandins and/or other eicosanoids. © 1993 Wiley-Liss, Inc.     

Location of the gene specifying hexose phosphate transport (uhp) on the chromosome of Escherichia coli.

The uhp gene, which specifies the uptake of hexose phosphates, and several other genes in the vicinity of minute 81 on the E. coli linkage map have been located by phage-mediated transductions. The order found is mtl-gpsA-pyre-gltc-uhp-tna-dnaa. Alleles specifying the Uhp- and Uhp+ characters were separated from that specifying constitutivity of hexose phosphate uptake (Uhpc). Although cotransduction frequencies between gltC and uhp as high as 90%, and between uhp and tna as high as 80%, were observed, these frequencies were unusually strongly dependent on which marker was selected. This may be due to the proximity of the uhp region to the point of origin of chromosome replication.     

A dopamine sensitive adenylate cyclase in the salivary glands of Amblyomma americanum (L.)

1. Enzyme activity, basal or dopamine-stimulated (10 microM), was linear with time to 25 min and with protein concentration to 0.8 mg protein/ml of final assay volume. Activity was maximal between pH 7.0 and 7.5. 2. Mg2+ maximally stimulated basal or dopamine-sensitive adenylate cyclase activity at about 4 mM. 3. Adenylate cyclase had a Km of 0.042 mM for ATP and maximum velocities for basal and dopamine-stimulated activity of 107 and 179 pmol cyclic AMP formed/mg protein per min, respectively. 4. Half-maximal stimulation of the enzyme occurred at about 4.2 x 10(-7) M dopamine with the threshold being less than 10(-9) M. Dopamine increased the Vmax but had no effect on the Km of ATP. 5. Eighty-five to 90% of the adenylate cyclase activity was found in the particulate fraction. 6. Calcium ion produced a marked inhibition of adenylate cyclase activity above 0.04 mM and half-maximal inhibition occurred near 0.1-0.2 mM.     

On the origins of esterases

Comparisons among the primary sequences of five cloned eukaryotic esterases reveal two distinct lineages, neither bearing any significant overall sequence similarity to the functionally related serine protease multigene family. We have not eliminated the possibility that the esterases may have residual conformational similarities to the serine proteases. However, our profile analysis and analyses of the predicted conformations of the esterases reveal little similarity to the serine proteases. Four of the esterase proteins share 27%-53% overall sequence similarity and evidence of a catalytic mechanism involving the same Arg- Asp-Ser or His-Asp-Ser charge relay. We propose that these four esterases, three of them cholinesterases, form part of a multigene family essentially separate from the serine proteases.