Conversion of a human low-density lipoprotein receptor ligandbinding repeat to a virus receptor: Identification of residues important for ligand specificity

The amino-terminal region of the low-density lipoprotein receptor (LDLR) contains seven imperfect repeats of a cysteine-rich, roughly 40-aa module (LDL-A module) that are critical for apolipoprotein binding. LDL-A modules are found in numerous cell-surface and secreted proteins and are believed to mediate extracellular protein–protein interactions. The cellular receptor for subgroup A Rous sarcoma virus (RSV) contains a single LDL-A module that binds the RSV envelope protein and allows viral infection. To define residues in an LDL-A module responsible for ligand recognition, we used a gain of function assay by using a chimeric protein in which the LDL-A module of Tva was replaced with a highly homologous module from human LDLR (LDL-A4) and determined whether this chimera or mutants produced in it could mediate RSV infection. LDL-A4 does not function as an RSV receptor; however, systematic replacement of the nonconserved residues of the LDL-A4 module in the chimeric protein with the corresponding residues from Tva identified three residues sufficient to alter ligand specificity and convert LDL-A4 to an efficient viral receptor. Mutations of the corresponding residues in the Tva LDL-A module decreased both envelope binding and viral receptor function, confirming the importance of these residues in ligand recognition by this module. Analysis of the hLDL-A5 structure demonstrates that these three residues are clustered at one end of the LDL-A module. These results demonstrate that using a single LDL-A module in a gain of function assay is a useful model to investigate ligand recognition by this module.     

Managing the upper extremity amputee: a protocol for success.

Since the beginning of Operation Enduring Freedom and Operation Iraqi Freedom, over 541 clients with major limb amputations have been seen in the Military Healthcare System. As a result of the nature and severity of injuries and the prevalence of concomitant injuries seen in this population, amputee care has become a specialized type of rehabilitative care at Walter Reed and Brooke Army Medical Centers. To streamline and accommodate the needs of clients with upper extremity limb loss, a five-phased upper extremity amputee protocol of care was developed. The five phases of the protocol include acute management; preprosthetic training; basic prosthetic training; advanced prosthetic training; and discharge planning. For the readers ease, these phases will be presented in the following categories: acute care, subacute care, and long-term rehabilitation needs. Furthermore, this article seeks to offer insight into the ideal treatment of an individual with upper extremity limb loss based on experience and collective expertise of the authoring therapists.     

Modifying the Baricity of Local Anesthetics for Spinal Anesthesia by Temperature Adjustment: Model Calculations

Background: Although local anesthetics (LAs) are hyperbaric at room temperature, density drops within minutes after administration into the subarachnoid space. LAs become hypobaric and therefore may cranially ascend during spinal anesthesia in an uncontrolled manner. The authors hypothesized that temperature and density of LA solutions have a nonlinear relation that may be described by a polynomial equation, and that conversion of this equation may provide the temperature at which individual LAs are isobaric.

Methods: Density of cerebrospinal fluid was measured using a vibrating tube densitometer. Temperature-dependent density data were obtained from all LAs commonly used for spinal anesthesia, at least in triplicate at 5[degrees], 20[degrees], 30[degrees], and 37[degrees]C. The hypothesis was tested by fitting the obtained data into polynomial mathematical models allowing calculations of substance-specific isobaric temperatures.

Results: Cerebrospinal fluid at 37[degrees]C had a density of 1.000646 +/- 0.000086 g/ml. Three groups of local anesthetics with similar temperature (T, [degrees]C)-dependent density ([rho]) characteristics were identified: articaine and mepivacaine, [rho]1(T) = 1.008-5.36 E-06 T2 (heavy LAs, isobaric at body temperature); L-bupivacaine, [rho]2(T) = 1.007-5.46 E-06 T2 (intermediate LA, less hypobaric than saline); bupivacaine, ropivacaine, prilocaine, and lidocaine, [rho]3(T) = 1.0063-5.0 E-06 T2 (light LAs, more hypobaric than saline). Isobaric temperatures ([degrees]C) were as follows: 5 mg/ml bupivacaine, 35.1; 5 mg/ml L-bupivacaine, 37.0; 5 mg/ml ropivacaine, 35.1; 20 mg/ml articaine, 39.4.     

Sensitivity and stability of LiF thermoluminescence dosimeters

Three different batches of LiF TLD-100 rods were subjected to investigation of their radiation sensitivity and the stability of the sensitivity after subsequent cycles of irradiation readouts. An old batch (circular rods from 1985), R85, showed an initial sensitivity of approximately 720 (nC/Gy). A new batch of circular rods (R0059) had an initial sensitivity more than a factor of 2.5 higher than the old batch. A batch of square rods (S3720) had an even higher sensitivity; a factor of almost 4 higher than batch R85. Both batches of circular rods showed a statistically significant change in sensitivity with increasing cycles of irradiations and readouts. No significant change was observed for the batch S3720. Batch R85 showed an increasing sensitivity with increasing number of cycles, and a small reduction in the width of the sensitivity distribution within the batch. However, the newer batch (R0059), showed a marked decrease in sensitivity and a doubling of the broadening of the sensitivity distribution after 10 cycles. No significant change in the sensitivity distribution within the S3720 batch was observed after 10 cycles.     

Behavioral evidence for dopaminergic supersensitivity following chronic treatment with methadone or chlorpromazine in the guinea pig

This study demonstrated the enhancement, as a consequence of prior chronic drug treatment, of two behaviors (stereotyped oral behaviors and open field locomotion) which are thought to depend primarily on the striatel dopamine system. Following a 5-week treatment with methadone (MD), chlorpromazine (CPZ), or saline, the dopamine agonist methamphetamine (MA) elicited more intense stereotypies in the MD and CPZ animals. After chronic treatment with MD, the MA-elicited stereotypies were reduced by an acute dose of MD. Stereotyped oral behaviors elicited by a stressful stimulus (foot shock) were enhanced in the MD animals both during and following chronic drug treatment. MA-elicited open field locomotion, measured 2 weeks following termination of chronic drug treatment, was enhanced in the MD and CPZ animals.