Acquired tracheomalacia--a case report

Divalproex sodium is an effective drug for the treatment of migraine. Most adverse drug events are transient and not of great clinical concern. Although rare, well-documented examples of liver toxicity have been reported in children under 2 years of age on polypharmacy. Additional cases occur in children under 10 who are receiving polypharmacy, particularly those who have intractable seizures and degenerative central nervous system disease. Clinicians who treat migraineurs with divalproex sodium do not need to be overly preoccupied with monitoring of drug levels and liver function tests. The most valuable test is clinical observation of the patient.     

ATP-Dependent human erythrocyte glutathione-conjugate transporter. I. Purification, photoaffinity labeling, and kinetic characteristics of ATPase activity

Dinitrophenyl S-glutathione (DNP-SG) ATPase is a 38 kDa membrane protein expressed in erythrocytes and other tissues. Although stimulation of ATP hydrolysis catalyzed by DNP-SG ATPase has been demonstrated in the presence of several structurally unrelated amphiphilic ions, structural and functional properties of this protein have not been well-defined. In the present study, we have developed an improved protocol for the purification of DNP-SG ATPase and investigated its kinetic and substrate-binding properties. The purification procedure was based on highly specific elution of the 38 kDa protein from DNP-SG affinity resin in the presence of ATP. The protein could not be eluted using either ADP or adenosine-5'-[beta,gamma-methylene]triphosphate (methylene-ATP), a nonhydrolyzable analogue of ATP. Doxorubicin (DOX), a weakly basic anthracycline chemotherapy agent, was found to be the preferred activator for stimulation of ATP hydrolysis by the enzyme. ATP binding to the enzyme was demonstrated using 8-azido-ATP photoaffinity labeling and binding of trinitrophenyl (TNP)-ATP, a fluorescent analogue of ATP. The photoaffinity labeling of DNP-SG ATPase (38 kDa) was saturable with respect to 8-azido ATP (Kd = 2 microM), indicating that the enzyme was capable of specific and saturable binding to ATP. DNP-SG binding was evident from the purification procedure itself and was also demonstrable by quenching of tryptophan fluorescence. Results of quenching of tryptophan fluorescence as well as radioactive isotope-binding studies indicated that DOX was bound to the purified protein as well.     

Performance of isolated rat hearts perfused with helium- or nitrogen-containing, gas-saturated solutions

Effects of helium on the isolated perfused rat heart were studied employing the Langendorff technique. The perfusate consisted of Krebs-Henseleit solution saturated with one of three gas mixtures: 1) 95% O2-5% CO2, 2) 50% O2-45% He-5% CO2, and 3) 50% o2-45% N2-5% CO2. Contractile indices measured revealed the performance of hearts with the helium mixture to be equivalent to those perfused with the 95% O2-5% CO2 mixture. Those perfused with the nitrogen gas mixture exhibited contractile activity lower than that in the other two groups. It was concluded that helium exerts a direct effect on the coronary vasculature of the isolated rat heart by reducing its resistance to flow. A greater oxygen delivery to hearts perfused with the He-saturated solution compared to the N2-perfused hearts may account for the difference in performance.     

Suppression of natural killer cell activity in mouse spleen lymphocytes by several dopamine receptor antagonists

Glomerular diseases are associated with changes in glomerular membrane permeability properties that alter filtration rate of plasma water and barrier function of the capillary wall. To estimate intrinsic permeability properties that regulate transmembrane transport of water and macromolecules, theoretical analysis of renal clearance of tracer molecules can be used. The development of adequate theoretical models is required to achieve sufficient accuracy to simulate complicated biological processes. Current research in this area is aimed at improving and validating the presently available models in order to characterize the nature of permeability changes associated with pathological conditions. This is a key step in understanding the pathophysiological nature of glomerular diseases and in the development of effective treatments.     

Truncating the putative membrane association region circumvents the difficulty of expressing hepatitis C virus protein E1 in Escherichia coli

The putative E1 of hepatitis C virus (HCV) was expressed in Escherichia coli using a glutathione-S-transferase (GST) fusion protein system. The full length E1 protein is difficult to express. A series of E1 DNA fragments was generated and used for expression vector construction. Fusion proteins containing the E1 C-terminal region could not be expressed. When this region was truncated, the fusion proteins were synthesized to high levels. The possibility of this C-terminal region hampering the production of fusion protein was further explored. A construct with this segment directly fused to the C-terminus of GST indeed generated no detectable recombinant protein. According to the predicted structure of E1, this region may have membrane-associating properties. The expression results suggest a general approach to facilitate the production of viral membrane proteins in prokaryotes. Furthermore, these recombinant E1 proteins generated as antigens were used for Western blotting with sera from HCV-infected individuals. It was found that E1 is antigenic during HCV natural infection.