Carpal tunnel syndrome: effect on Army dental personnel.

The purpose of this study was 2-fold: (1) to determine the prevalence of hand problems, in particular carpal tunnel syndrome (CTS), among Army dental personnel; and (2) to identify dental professionals at risk. A 12-page survey was mailed to all U.S. Army military and civilian dental personnel. Of the 6,320 surveys mailed, 80.9% were returned completed. An analysis was performed identifying the prevalence of hand problems and CTS and noting differences between civilian and military dental personnel. Of the 5,115 surveys analyzed, 44.8% indicated hand problems and 25.4% were determined to indicate a high probability of CTS. Of the 18 dental job specialties, dental therapy assistants and dental hygienists had the highest prevalence of CTS, 73% and 57%, respectively. Army dental personnel are at greater risk of developing CTS than the general public, especially civilian dental personnel, who were female, older, and employed longer.

Hypoxia induces hexokinase II gene expression in human lung cell line A549.

During adaptation to hypoxic and hyperoxic conditions, the genes involved in glucose metabolism are upregulated. To probe involvement of the transcription factor hypoxia-induced factor-1 (HIF-1) in hexokinase (HK) II expression in human pulmonary cells, A549 cells and small-airway epithelial cells (SAECs) were exposed to stimuli such as hypoxia, deferoxamine (DFO), and metal ions. The largest increase in HK-II (20-fold for mRNA and 2.5-fold for enzymatic activity) was observed in A549 cells when exposed to DFO. All stimuli selectively increased the 5.5-kb rather than 4-kb transcript in A549 cells. Cycloheximide and actinomycin D inhibited these responses. In addition, cells were transfected with luciferase reporter constructs driven by the full-length HK-II 5'-regulatory region (4.0 kb) or various deletions of that region. A549 cells transfected with the 4.0-kb construct and exposed to hypoxia or DFO increased their luciferase activity 7- and 10-fold, respectively, indicating that HK-II induction is, at least in part, due to increased gene transcription. Sixty percent of the inducible activity of the 4.0-kb construct was shown to reside within the proximal 0.5 kb. Additionally, cotransfection with a stable HIF-1 mutant and the 4.0-kb promoter construct resulted in increased luciferase activity under normoxic conditions. These results strongly suggest that HK-II is selectively regulated in pulmonary cells by a HIF-1-dependent mechanism.

African elephant sesquiterpenes.

GC-MS analysis of extracts from temporal gland secretions of an African elephant has revealed the presence of several farnesol-related sesquiterpenes. Among these are (E)-2, 3-dihydrofarnesol (3), a bumblebee pheromone not seen before in mammals, and a rare component of a Greek tobacco, drimane-8alpha, 11-diol (4), never observed before in an animal.

Structural basis for the specificity of ubiquitin C-terminal hydrolases.

The release of ubiquitin from attachment to other proteins and adducts is critical for ubiquitin biosynthesis, proteasomal degradation and other cellular processes. De-ubiquitination is accomplished in part by members of the UCH (ubiquitin C-terminal hydrolase) family of enzymes. We have determined the 2.25 A resolution crystal structure of the yeast UCH, Yuh1, in a complex with the inhibitor ubiquitin aldehyde (Ubal). The structure mimics the tetrahedral intermediate in the reaction pathway and explains the very high enzyme specificity. Comparison with a related, unliganded UCH structure indicates that ubiquitin binding is coupled to rearrangements which block the active-site cleft in the absence of authentic substrate. Remarkably, a 21-residue loop that becomes ordered upon binding Ubal lies directly over the active site. Efficiently processed substrates apparently pass through this loop, and constraints on the loop conformation probably function to control UCH specificity.

An external landmark for the anterior commissure.

OBJECTIVE: The ability to predict the level of the true vocal cords based on external landmarks is crucial to the success of many laryngeal surgical procedures. This study examines the reliability of one such landmark on the thyroid cartilage. METHODS: Twenty-four cadaver larynges were examined. A pin was placed through the landmark, best described as a small diamond shaped area of color change and surface depression along the anterior midline of each thyroid cartilage through which travels a very small unnamed artery. The endolaryngeal position of the pin was checked with a flexible nasopharyngoscope. RESULTS: In all 24 cadavers, the pin entered the larynx at the anterior commissure, just above or at the level of the true vocal cords. CONCLUSIONS: This external landmark reliably predicts the position of the true vocal cords. It serves as a useful adjunct to existing external landmarks used to direct thyroid cartilage cuts in laryngeal procedures.

Mechanism of phosphatidylinositol-specific phospholipase C: a unified view of the mechanism of catalysis.

The mechanism of phosphatidylinositol-specific phospholipase C (PI-PLC) has been suggested to resemble that of ribonuclease A. The goal of this work is to rigorously evaluate the mechanism of PI-PLC from Bacillus thuringiensis by examining the functional and structural roles of His-32 and His-82, along with the two nearby residues Asp-274 and Asp-33 (which form a hydrogen bond with His-32 and His-82, respectively), using site-directed mutagenesis. In all, twelve mutants were constructed, which, except D274E, showed little structural perturbation on the basis of 1D NMR and 2D NOESY analyses. The H32A, H32N, H32Q, H82A, H82N, H82Q, H82D, and D274A mutants showed a 10(4)-10(5)-fold decrease in specific activity toward phosphatidylinositol; the D274N, D33A, and D33N mutants retained 0. 1-1% activity, whereas the D274E mutant retained 13% activity. Steady-state kinetic analysis of mutants using (2R)-1, 2-dipalmitoyloxypropane-3-(thiophospho-1d-myo-inositol) (DPsPI) as a substrate generally agreed well with the specific activity toward phosphatidylinositol. The results suggest a mechanism in which His-32 functions as a general base to abstract the proton from 2-OH and facilitates the attack of the deprotonated 2-oxygen on the phosphorus atom. This general base function is augmented by the carboxylate group of Asp-274 which forms a diad with His-32. The H82A and D33A mutants showed an unusually high activity with substrates featuring low pKa leaving groups, such as DPsPI and p-nitrophenyl inositol phosphate (NPIPs). These results suggest that His-82 functions as the general acid with assistance from Asp-33, facilitating the departure of the leaving group by protonation of the glycerol O3 oxygen. The Bronsted coefficients obtained for the WT and the D33N mutant indicate a high degree of proton transfer to the leaving group and further underscore the "helper" function of Asp-33. The complete mechanism also includes activation of the phosphate group toward nucleophilic attack by a hydrogen bond between Arg-69 and a nonbridging oxygen atom. The overall mechanism can be described as "complex" general acid-general base since three elements are required for efficient catalysis.

Quality of life following acoustic neuroma surgery.

In the treatment of acoustic neuroma, operative results have improved greatly during recent years, with high rates of functional cranial nerve preservation. Because of this, it has become more important to consider issues of patient satisfaction and quality of life (QOL) following treatment for these lesions. The authors have developed a novel questionnaire designed to measure QOL in patients with acoustic neuromas, and they administered it to 50 consecutive patients at least 6 months after acoustic neuroma surgery. Overall QOL was judged to be good but with definite minor difficulties, including some problems with hearing, facial nerve function, headache, tinnitus, dizziness, activity level, enjoyment of life, and emotional well-being. No significant differences were found between age groups and different operative approaches, and only minor differences were found in relation to tumor size. Patients with intracanalicular tumors fared no better than those with cerebellopontine angle tumors. Analysis of the data suggests an overall good outcome from acoustic neuroma surgery; however, when discussing the possible effects on postoperative QOL, even the potential minor problems should not be minimized, especially in patients undergoing operation for small or intracanalicular tumors.

Midline mandibular osteotomy: an analysis of functional outcomes.

Although the oncologic validity and perioperative complications of midline mandibular osteotomy are well described, little attention has been directed toward the long-term functional problems that may be associated with its use. Thirty-one patients who had undergone this procedure were examined to assess postoperative sensation, temporomandibular joint (TMJ) function, occlusion, and cosmesis. The majority (27 of 31) patients had some sequelae but these were minor in nature. Twenty of 31 patients had abnormal sensation, 24 of 31 noted a changed occlusion, and 15 of 31 had signs or symptoms of TMJ myofascial pain. Although patients should be advised of the potential for functional problems with this procedure, they can be reassured that these are likely to be relatively minor in significance. If technically feasible and if an exact restoration of occlusion is a priority, a prefabricated lingual splint should be used.

Phosphatidylinositol-specific phospholipase C: kinetic and stereochemical evidence for an interaction between arginine-69 and the phosphate group of phosphatidylinositol.

A new substrate analogue, (2R)-1,2-dipalmitoyloxypropanethiophospho-1-D-myo-inositol (DPsPI), has been used in a new, continuous assay for phosphatidylinositol-specific phospholipase C (PI-PLC). DPsPI is superior to other substrate analogs that have been used for assaying PI-PLC since it is synthesized as a pure diastereomer and maintains both acyl chains of the natural substrate, dipalmitoylphosphatidylinositol (DPPI). The assay that has been developed using this new analogue has allowed us to elucidate detailed kinetic data so far lacking in the field. In addition, several mutants of PI-PLC were constructed and assayed. The results show that Arg-69 is essential for catalysis, since mutations at this position led to a 10(3)- 10(4)-fold decrease in activity with respect that of to the wild-type (WT) enzyme. An alanine mutant of Asp-67, a residue also found at the active site, displays activity similar to that of WT. We have also used nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy to analyze the structural integrity and conformational stability of the mutants. The results show that the overall global conformation of the enzyme is not perturbed by the mutants. The 15N-1H HSQC NMR spectrum of WT PI-PLC is also reported at 600 MHz. The stereoselectivity of the reaction toward the stereoisomers of another analogue, 1,2-dipalmitoyl-sn-glycero-3-thiophospho-1-myo-inositol (DPPsI), was used to probe whether Arg-69 interacts with the phosphate moiety of the substrate. We have calculated that the WT enzyme shows a stereoselectivity ratio of 160000:1 in favor of the Rp isomer versus the Sp isomer. The R69K mutant displayed a significant 10(4)-fold relaxation of stereoselectivity. Our data support the role of Arg-69 in stabilizing the negative charge on the pentacoordinate phosphate in the transition state during catalysis.

Transactivation of the major capsid protein gene of herpes simplex virus type 1 requires a cellular transcription factor.

The purpose of this investigation was to identify and characterize the regulatory elements involved in the transcriptional activation of the beta gamma (leaky-late or gamma 1) genes of herpes simplex virus type 1 (HSV-1) by using the major capsid protein (VP5 or ICP5) gene as model. Gel mobility shift assays with nuclear extracts from uninfected and infected HeLa cells enabled us to identify two major protein-DNA complexes involving the VP5 promoter. The mobilities of these two complexes remained unaltered, and no unique complexes were observed when infected cell nuclear extracts were used. DNase I and orthophenanthroline-Cu+ footprint analyses revealed that the two complexes involve a single binding site, GGCCATCTTGAA, located between -64 and -75 bp relative to the VP5 cap site. To determine the function of this leaky-late binding site (LBS) in VP5 gene activation, we tested the effect of mutations in this region by using transient expression of a cis-linked chloramphenicol acetyltransferase gene. Deletion of the above sequence resulted in a seven- to eightfold reduction in the level of transactivation of the chloramphenicol acetyltransferase gene by superinfection with HSV-1 or by cotransfection of HSV-1 immediate-early genes. From these results, we conclude that the LBS sequence and a cellular factor(s) are involved in the transactivation of the VP5 gene. A search of published gene sequences revealed that sequences related to the LBS exist in a number of other HSV-1, cytomegalovirus, retrovirus, and cellular promoters. Sequence homologies of binding sites and results of unpublished competition binding studies suggest that this leaky-late binding factor may be related to, or the same as, a ubiquitous cellular transcriptional factor called YY1 or common factor-1 (also known as NF-E1, delta, and UCRBP).

Biosynthetic human EGF accelerates healing of Neodecadron-treated primate corneas.

Topical administration of biosynthetic human epidermal growth factor (h-EGF), given in combination with an antibiotic and synthetic steroid (Neodecadron) accelerated the rate of corneal epithelial regeneration and significantly increased the strength of full-thickness stromal incisions in primates. The regenerated epithelial cells of EGF-Neodecadron-treated corneas appeared normal on histologic examination and showed no evidence of hypertrophy or hyperplasia. The EGF-Neodecadron-treated stromal incisions were characterized by new collagen formation and a smaller epithelial cell plug than Neodecadron-treated control corneas. These results suggest that biosynthetic h-EGF, which lacks the immunologic potential of nonhuman proteins, may be effective in accelerating healing of corneal epithelial defects and stromal incisions in patients whose healing is suppressed by treatment with steroids.