Enhanced upper respiratory tract airflow and head fanning reduce brain temperature in brain-injured, mechanically ventilated patients: a randomized, crossover, factorial trial

BACKGROUND

Heat loss from the upper airways and through the skull are physiological mechanisms of brain cooling which have not been fully explored clinically.

METHODS

This randomized, crossover, factorial trial in 12 brain-injured, orally intubated patients investigated the effect of enhanced nasal airflow (high flow unhumidified air with 20 p.p.m. nitric oxide gas) and bilateral head fanning on frontal lobe brain temperature and selective brain cooling. After a 30 min baseline, each patient received the four possible combinations of the interventions--airflow, fanning, both together, no intervention--in randomized order. Each combination was delivered for 30 min and followed by a 30 min washout, the last 5 min of which provided the baseline for the next intervention.

RESULTS

The difference in mean brain temperature over the last 5 min of the preceding washout minus the mean over the last 5 min of intervention, was 0.15 degrees C with nasal airflow (P=0.001, 95% CI 0.06-0.23 degrees C) and 0.26 degrees C with head fanning (P<0.001, 95% CI 0.17-0.34 degrees C). The estimate of the combined effect of airflow and fanning on brain temperature was 0.41 degrees C. Selective brain cooling did not occur.

CONCLUSION

Physiologically, this study demonstrates that heat loss through the upper airways and through the skull can reduce parenchymal brain temperature in brain-injured humans and the onset of temperature reduction is rapid. Clinically, in ischaemic stroke, a temperature decrease of 0.27 degrees C may reduce the relative risk of poor outcome by 10-20%. Head fanning may have the potential to achieve a temperature decrease of this order.

The influence of endurance and resistance exercise on muscle capillarization in the elderly: a review

AIM

Ageing is one of many factors altering skeletal muscle. Conflicting results from previous studies guided this review to identify what has been found to date regarding microvascular adaptations in skeletal muscle as the result of ageing or inactivity, and endurance or resistance training interventions. Additionally, this review attempts to identify the variety of parameters for determining capillarization and discuss why these might be contributing to the conflicting results.

METHODS

Electronic database searches were conducted for full-length articles using relevant keywords related to ageing, muscle capillarization and exercise in all fields. Cross-sectional, longitudinal, training and review papers were included. Several studies on younger subject adaptation were also included for comparison.

RESULTS

Ageing and inactivity both result in regressive structural and functional changes to skeletal muscle capillarization. The rate and magnitude of decline is still unknown. Endurance training can positively effect structural changes to capillarity. There is conflicting evidence regarding the effects of resistance training. Training intensity may be an important factor. Biopsy sampling, histological staining and several measurement protocols may be providing inaccurate estimations of capillarity.

CONCLUSION

Part of the difficulty in determining the nature of these relationships has been the inconsistency in research conducted regarding age groups and controlling for past and present activity patterns. Further difficulties comparing across studies arise due to the variety of methods and parameters used to sample and analyse muscle tissue. Standardizing methodology will allow future research to yield more consistent results.

Regulators of G protein signaling 6 and 7. Purification of complexes with gbeta5 and assessment of their effects on g protein-mediated signaling pathways

Regulators of G protein signaling (RGS) proteins that contain DEP (disheveled, EGL-10, pleckstrin) and GGL (G protein gamma subunit-like) domains form a subfamily that includes the mammalian RGS proteins RGS6, RGS7, RGS9, and RGS11. We describe the cloning of RGS6 cDNA, the specificity of interaction of RGS6 and RGS7 with G protein beta subunits, and certain biochemical properties of RGS6/beta5 and RGS7/beta5 complexes. After expression in Sf9 cells, complexes of both RGS6 and RGS7 with the Gbeta5 subunit (but not Gbetas 1-4) are found in the cytosol. When purified, these complexes are similar to RGS11/beta5 in that they act as GTPase-activating proteins specifically toward Galpha(o). Unlike conventional G(betagamma) complexes, RGS6/beta5 and RGS7/beta5 do not form heterotrimeric complexes with either Galpha(o)-GDP or Galpha(q)-GDP. Neither RGS6/beta5 nor RGS7/beta5 altered the activity of adenylyl cyclases types I, II, or V, nor were they able to activate either phospholipase C-beta1 or -beta2. However, the RGS/beta5 complexes inhibited beta(1)gamma(2)-mediated activation of phospholipase C-beta2. RGS/beta5 complexes may contribute to the selectivity of signal transduction initiated by receptors coupled to G(i) and G(o) by binding to phospholipase C and stimulating the GTPase activity of Galpha(o).

Quadriceps muscle strength and dynamic stability in elderly persons

Several measures of dynamic stability during two functional activities correlated to quadriceps femoris muscle strength. A total of 34 disabled elders (aged 60-88) living in the Boston area consented to maximum isometric quadriceps muscle strength testing, chair rise and gait analysis. During chair rise, quadriceps strength significantly correlated with maximum upper body vertical linear momentum, r=0.53, P<0.005, anterior posterior linear momentum, r=0. 38, P<0.05, and the time to complete the chair rise, r=-0.48, P<0.05, n=29. Stride length and gait velocity correlated (r=0.56, P<0.001 and r=0.51, P<0.002, n=34) with quadriceps muscle strength. The maximum range of whole body anteroposterior (A/P) linear momentum during gait also correlated with quadriceps strength (r=0.47, P=0. 004, n=31). Dynamic stability during chair rise and gait, at preferred speed, correlates directly with quadriceps femoris muscle strength in functionally limited elderly individuals. In our sample, elders performed one of three movement strategies to arise from a chair, and quadriceps strength did not statistically differ between the chair rise strategy groups. However, persons with the greatest quadriceps strength values were more stable regardless of which chair rise strategy they performed. Our data indicate that clinicians should not suggest that patients use compensatory momentum inducing locomotor strategies unless the patient has sufficient strength to control these induced forces.

Exercise--it's never too late: the strong-for-life program

OBJECTIVES

This investigation determined whether an in-home resistance training program achieved health benefits in older adults with disabilities.

METHODS

A randomized controlled trial compared the effects of assigning 215 older persons to either a home-based resistance exercise training group or a waiting list control group. Assessments were conducted at baseline and at 3 and 6 months following randomization. The program consisted of videotaped exercise routines performed with elastic bands of varying thickness.

RESULTS

High rates of exercise adherence were achieved, with 89% of the recommended exercise sessions performed over 6 months. Relative to controls, subjects who participated in the program achieved statistically significant lower extremity strength improvements of 6% to 12%, a 20% improvement in tandem gait, and a 15% to 18% reduction in physical and overall disability at the 6-month follow-up. No adverse health effects were encountered.

CONCLUSIONS

These findings provide important evidence that home-based resistance exercise programs designed for older persons with disabilities hold promise as an effective public health strategy.

Reliability of clinical balance outcome measures in the elderly

BACKGROUND AND PURPOSE

Simple, practical and reliable clinical balance outcome measures are needed to assess baseline status and response to treatment in older people. The reliability of the clinical measures used in this testing protocol had not been determined for this population. This study assessed the inter-rater reliability of three commonly used clinical measures of balance: one leg standing, tandem gait and functional reach.

METHOD

Two samples of older people were used: (1) non-disabled and (2) disabled community dwellers. All testing was performed in a single session by two trained examiners according to a standardized protocol. Intra-class correlations were calculated comparing the means of each clinical balance test for Examiner 1 with Examiner 2.

RESULTS

Reliability coefficients were 0.75 for one leg standing, 0.73 for functional reach, and 0.31 for tandem gait for the non-disabled sample. Reliability coefficients were 0.85 for one leg standing, 0.79 for functional reach, and 0.62 for tandem gait for the disabled sample.

CONCLUSIONS

These findings for the one leg standing and functional reach testing protocols in disabled and non-disabled older people can be used as outcome measures. Further study should be directed towards improving the reliability of the tandem gait test for use with older people.

To knot or not to knot? Examination of 16S ribosomal RNA models

The presence of topological knots in large RNA structures is highly unlikely given that 1) no RNA structures determined thus far contain topological knots, 2) secondary structure maps for most RNA molecules are knot free, 3) there are no known RNA topoisomerases, and 4) it is difficult to imagine how knots could be formed specifically and uniquely during transcription. Since native RNA structures probably lack topological knots, models of these RNA molecules should be free of knots as well. Therefore, we have examined four existing models for the 30S ribosomal subunit to determine if any of the three domains of the 16S rRNA molecule is knotted. We found that all but one model had at least one knotted domain. We conclude that models of large RNA molecules should be examined for knotting before publication.

The re-emergence of space medicine as a distinct discipline

Space Medicine is a discipline whose scope will encompass primary and advanced medical care amidst the environmental constraints of space. At one time, there was a Department of Space Medicine associated with the U.S. Air Force School of Aviation Medicine. Until 1993, an academic, university-based training program dedicated to space medicine did not exist. This paper reviews the history of space medicine in the United States. It presents the current conceptions of space medicine, and postulates the need for space medicine to mature as a distinct discipline.

Interrelationships among disablement concepts

BACKGROUND

Understanding interrelationships among disablement concepts is critical to the design of future disability treatment and prevention interventions.

METHODS

This study uses cross-sectional data to examine the relationships among physiologic impairments, functional limitations, and disability in a moderately disabled sample of 207 community-dwelling older adults.

RESULTS

As hypothesized, the data revealed statistically significant curvilinear relationships of upper and lower extremity strength and balance with mobility in this older sample. Multivariate analyses further clarified the hypothesized causal mechanism among the disablement concepts by demonstrating that most of the association of muscle strength and balance with disability was through the intermediary role of mobility limitations.

CONCLUSIONS

The findings from this study highlight the value of clinical trials that focus on prevention or treatment of mobility limitations as a means of preventing disability; our findings underscore the need for future research that examines the effects of other variables believed to influence disablement in late life.

Zinc-dependent dimers observed in crystals of human endostatin

The crystal structure of human endostatin reveals a zinc-binding site. Atomic absorption spectroscopy indicates that zinc is a constituent of both human and murine endostatin in solution. The human endostatin zinc site is formed by three histidines at the N terminus, residues 1, 3, and, 11, and an aspartic acid at residue 76. The N-terminal loop ordered around the zinc makes a dimeric contact in human endostatin crystals. The location of the zinc site at the amino terminus, immediately adjacent to the precursor cleavage site, suggests the possibility that the zinc may be involved in activation of the antiangiogenic activity following cleavage from the inactive collagen XVIII precursor or in the cleavage process itself.

Home-based resistance training: predictors of participation and adherence

This study identified factors associated with exercise participation and adherence in a sample of 102 sedentary, functionally limited, community-dwelling adults aged 60 to 94 years who participated in a home-based resistance training program. Stepwise regression analyses revealed that baseline physical factors (i.e., higher levels of mobility, weaker muscle strength, and fewer numbers of new medical conditions) were associated with higher rates of participation in the home program. Positive attitudes and a sense of control toward exercise, lower levels of confusion and depressive moods, and the development of fewer new medical problems during the program were related to higher levels of adherence to the program. Findings revealed that although physical health variables were the primary indicators of an older person's overall participation in the program, it was the psychological factors that were most important to adherence to this home-based program.

Acetabular pressures during hip arthritis exercises

OBJECTIVE

To examine in vivo maximum acetabular contact pressures during gait and hip arthritis exercises recommended by clinicians and the Arthritis Foundation.

METHODS

Acetabular contact pressure data were collected for 2.5 years, at 3-4-month intervals, from an instrumented endoprosthesis implanted in an 84-year-old male who had sustained a left hip fracture. Maximum pressure data were compared for each activity.

RESULTS

Mean pressures ranged from 9.0 +/- 2.3 megapascals (MPa) during maximum isometric hip abduction, 9.0 +/- 0.8 MPa during standing right hip abduction, and 8.9 +/- 2.8 MPa during standing left hip abduction to 1.2 +/- 0.3 MPa during quiet standing. Free-speed gait pressure averaged 5.6 +/- 0.9 MPa. The maximum mean pressure during side-lying hip abduction and straight leg raise at 30 degrees/second were less than the same activities at 60 degrees/second.

CONCLUSIONS

These in vivo hip pressure measurements challenge traditional protocols for patients with hip osteoarthritis and provide quantitative data as a framework for designing exercise programs. Maximum isometric hip exercise and standing exercise generated much higher hip pressures, and are therefore probably more stressful to acetabular cartilage, than gait or stationary cycling. Clinicians must consider exercise velocity because of its direct correlation with hip contact pressure. Walking generated lower pressure than most activities studied and, given its other benefits, is therefore probably beneficial for patients with hip osteoarthritis.

Physical therapy utilization by patients with acute low back pain

BACKGROUND AND PURPOSE

The purposes of this study were (1) to describe the demographic and clinical characteristics of a group of patients with acute low back pain (LBP), (2) to describe those patients who were being treated by physical therapists, and (3) to analyze their use of physical therapy services.

SUBJECTS

The study sample consisted of 1,580 patients with acute LBP who were treated by 208 practitioners in North Carolina. The initial providers were primary care physicians, chiropractors, orthopedic surgeons, and primary care providers at a health maintenance organization.

METHODS

A telephone interview was conducted after the initial office visit to assess demographics and medical history, health care services utilization, and functional status. Follow-up telephone interviews were also conducted 2, 4, 8, 12, and 24 weeks later.

RESULTS

One hundred ninety-nine (12.6%) of the subjects reported that they saw a physical therapist either by any provider referral or by direct access. Therapeutic exercise was the most commonly reported treatment procedure. Post-high-school education, receipt of Workers' Compensation, prior physical therapy for LBP, LBP and pain below the knee in one or both legs, and a higher baseline Roland-Morris Questionnaire score were associated with being treated by physical therapists.

CONCLUSION AND DISCUSSION

In this study, physical therapists were utilized in the treatment of patients with greater severity of LBP. The findings demonstrate the importance of controlling for baseline characteristics when comparing outcomes of LBP when treated by different types of providers.

Physical examination during space flight

OBJECTIVE

To develop techniques for conducting a physical examination in microgravity and to describe and document the physiologic changes noted with use of a modified basic physical examination.

DESIGN

On the basis of data gathered from physical examinations on KC-135 flights, three physical variables were assessed serially in astronauts during two shuttle missions (of 8- and 10-day duration, respectively). Preflight, in-flight, and postflight examinations were conducted by trained physician-astronauts or flight surgeons, who used this modified examination.

MATERIAL AND METHODS

Five male and two female crewmembers participated in the "hands-on" physical examination of all physiologic systems except the genitourinary system. Level of edema, intensity of bowel sounds, and peripheral reflexes were assessed and graded.

RESULTS

This investigation identified unique elements of a physical examination performed during space flight that will assist in the development of standard methods for conducting examinations of astronauts in weightlessness. In addition, demonstrable changes induced by microgravity were noted in most physiologic systems examined.

CONCLUSION

The data support the hypothesis that the microgravity examination differs from that conducted on earth or in a 1g environment. In addition, alterations in the physiologic response can be detected with use of hands-on technique. These data are invaluable in the development of optimal medical care for humans in space.

A home-based exercise program for nondisabled older adults

OBJECTIVES

This paper describes a videotaped, home-based, strength training program, titled Strong-for-Life and reports on its effectiveness in improving muscle strength, psychological well-being, and health status in a sample of older persons.

DESIGN AND SETTING

We enrolled 102 nondisabled, community-dwelling older people aged 66 to 87, identified from the Medicare beneficiary list, into a randomized, controlled trial.

MEASUREMENTS

Effectiveness was based on change in isokinetic upper and lower extremity muscle strength, psychologic well-being, and health status.

RESULTS

Results revealed several statistically significant short-term benefits after 12 to 15 weeks of exercise, especially for men. Younger older adults demonstrated a 10% improvement in knee extensor strength relative to control subjects. Older male exercisers achieved significant differences relative to controls in perceived anger, tension, and overall social functioning. Male exercisers, in general, achieved significant improvement in perceived vigor. Women did not report psychological benefits following participation in the program.

CONCLUSION

Study results reveal that the Strong for Life program, designed to be widely disseminated to the nondisabled older population, has many short-term positive benefits.

The structure of unliganded reverse transcriptase from the human immunodeficiency virus type 1

The crystal structure of the reverse transcriptase (RT) from the type 1 human immunodeficiency virus has been determined at 3.2-A resolution. Comparison with complexes between RT and the polymerase inhibitor Nevirapine [Kohlstaedt, L.A., Wang, J., Friedman, J.M., Rice, P.A. & Steitz, T.A. (1992) Science 256, 1783-1790] and between RT and an oligonucleotide [Jacobo-Molina, A., Ding, J., Nanni, R., Clark, A. D., Lu, X., Tantillo, C., Williams, R. L., Kamer, G., Ferris, A. L., Clark, P., Hizi, A., Hughes, S. H. & Arnold, E. (1993) Proc. Natl. Acad. Sci. USA 90, 6320-6324] reveals changes associated with ligand binding. The enzyme is a heterodimer (p66/p51), with domains labeled "fingers," "thumb," "palm," and "connection" in both subunits, and a ribonuclease H domain in the larger subunit only. The most striking difference between RT and both complex structures is the change in orientation of the p66 thumb (approximately 33 degrees rotation). Smaller shifts relative to the core of the molecule were also found in other domains, including the p66 fingers and palm, which contain the polymerase active site. Within the polymerase catalytic region itself, there are no rearrangements between RT and the RT/DNA complex. In RT/Nevirapine, the drug binds in the p66 palm near the polymerase active site, a region that is well-packed hydrophobic core in the unliganded enzyme. Room for the drug is provided by movement of a small beta-sheet within the palm domain of the Nevirapine complex. The rearrangement within the palm and thumb, as well as domain shifts relative to the enzyme core, may prevent correct placement of the oligonucleotide substrate when the drug is bound.

Expression of human M2 muscarinic receptors in Sf9 cells: characterisation and reconstitution with G-proteins

The gene for the human m2 muscarinic receptor was expressed in Sf9 cells using the baculovirus expression system. As assessed by [3H]NMS binding, Sf9 cells expressed receptor at levels of 3.3 pmoles/mg protein. The receptor was identified on western blots using an anti-muscarinic receptor antibody and was shown to have the pharmacological characteristics of an m2 muscarinic receptor. Membranes from Sf9 cells were examined to identify endogenous G-proteins by immuno-blotting and by ADP-ribosylation, indicating the presence of Gq, and a pertussis-toxin substrate which was not recognised by antibodies raised against the alpha-subunits of Gi1, Gi2, Gi3 or Go. Gsalpha was not detected, neither were there any cholera toxin substrates in Sf9 membranes. Sf9 membranes expressing m2 receptors did not show carbachol-stimulated GTPgammaS binding to endogenous G-proteins; however, when membranes were reconstituted with a mixture of purified Gi and Go, a maximum 8-fold stimulation of GTPgammaS binding was observed in response to carbachol that could be reduced by atropine. These data show that the human muscarinic m2 receptor expressed in Sf9 cells is functional.

Activation of Gi protein by peptide structures of the muscarinic M2 receptor second intracellular loop

The muscarinic M2 receptor that normally couples via Gi to inhibit adenylyl cyclase was made to couple to Gs by exchange of its third intracellular loop for the comparable domain of the beta 2-adrenoceptor. In HeLa cells transfected with the recombinant M2 beta i-3 cDNA, the chimaeric receptor showed carbachol-mediated activation of adenylyl cyclase (EC50 = 73 nM) that was blocked by atropine, but not by propranolol. The chimaeric receptor was shown to mediate a carbachol-stimulated, Bordetella pertussis toxin-sensitive GTPase activity in membranes of transfected HeLa cells. Interestingly, stimulation of adenylyl cyclase by carbachol was 2-fold higher in transfected cells that had been pretreated with pertussis toxin. These data suggested that the M2 beta i-3 receptor was able to couple to both Gi and Gs, and that the ability to recognise and stimulate Gi did not involve the third cytoplasmic loop of M2. We investigated peptide elements taken from the second intracellular loop of the M2 receptor for their ability to mediate activation of Gi and found that a nine amino acid peptide representing the C-terminal sequence, VKRTTKMAG-NH2 (V9G), was capable of inhibiting forskolin-stimulated adenylyl cyclase by up to 18% and could stimulate high affinity GTPase activity of rat brain membranes by 32%. Further, V9G was shown to cause a doubling of the initial rate of [35S]GTP gamma S binding to purified bovine brain Gi/Go in reconstituted phospholipid vesicles. These data identify a domain on the second intracellular loop of the muscarinic M2 receptor that is involved in the selection of a pertussis toxin-sensitive G protein.

A strength training program for postmenopausal women: a pilot study

This pilot study examined a specific exercise program designed for skeletal muscle strengthening in postmenopausal women. The program consisted of patterns of movement using diagonal and spiral patterns, superimposed on a progressive weight-bearing sequence from prone lying to standing. Progressive resistance was provided with the use of progressively thicker elastic straps. Eighteen of an initial 22 healthy volunteer women aged 50 to 64 years completed 8 weekly hour-long group exercise sessions supplemented with twice weekly sessions at home to pilot test the program's safety, acceptability, and effectiveness in changing muscle strength. A physical therapist conducted baseline and final quadriceps, hamstrings, and grip strength assessments using a portable isokinetic dynamometer. Participants achieved a 21% increase in quadriceps (p < or = .001), 9% increase in hamstrings (p < or = .07), and a 14% increase in grip strength (p < or = .002). A positive dose-response relationship was observed between strength gains and compliance with the program. This approach to strength training in postmenopausal women is feasible and effective in increasing muscle strength. It has considerable promise and deserves further testing and evaluation.

Fitting the treatment to the problem: deciding where to refer substance abusers

The average physician sees a broad spectrum of substance-abusing patients whose illness levels may range from mild to severe. Considering the number and nature of substance abuse treatment options available, choosing the most appropriate treatment for any given patient may be confusing. This article provides workable guidelines for physicians based on a patient placement manual developed by the American Society of Addiction Medicine.

Reliability of eccentric isokinetic knee flexion and extension measurements

This study assessed the test-retest reliability of knee isokinetic eccentric muscle performance in subjects with and without a history of tibio-femoral pathology. Nineteen adults were tested at 60 degrees/sec and 180 degrees/sec on three occasions using a standardized protocol that incorporates a same-session learning phase. Results revealed moderate to excellent reliability for average peak torque test-retest ICC (2,1) = .58 to .96, total work ICC = .63 to .93, and power ICC = .67 to .93. Joint angle at peak torque was unreliable (ICC = .01 to .69) for both muscle groups at both angular velocities. Knee flexion reliability was higher than extension reliability at both 60 degrees/sec and 180 degrees/sec. Subjects with tibio-femoral pathologies had ICC values lower than the healthy subjects. Reliable eccentric isokinetic measurements can be obtained for average peak torque, total work, and power. Clinicians should not assume the same degree of reliability in testing patients as in testing healthy subjects.

Reliability of dynamic and isometric testing of shoulder external and internal rotators

Advances in isokinetic technology allow the physical therapist to assess concentric, eccentric, and isometric muscle performance at the shoulder in various positions. Research is limited, however, on the reliability of isokinetic measurements. The purposes of this study were: 1) to determine the test-retest reliability of concentric, eccentric, and isometric muscle performance measurements of shoulder external and internal rotation in the scapular plane test position and 2) to compare this reliability between the involved and uninvolved limb of subjects with a history of unilateral shoulder pathology. Fourteen males and 10 females (17-58 years) were tested on two occasions at 1-week intervals with the Biodex isokinetic dynamometer. Peak torque, total work, and average power were recorded for concentric tests at angular velocities of 60 and 120 degrees/sec and for eccentric tests at 60 degrees/sec. Maximum average isometric torque was recorded in two positions. Means, standard deviations, and mean differences between sessions with 95% confidence intervals were calculated. Intraclass correlation coefficients (ICCs) were used to determine test-retest reliability. Isometric tests were generally most reliable (ICC = .81-.93), followed by concentric (ICC = .60-.95) and eccentric tests (ICC = .44-.92). Isokinetic and isometric reliability were usually higher for involved than uninvolved shoulders. The implication of these findings is that there appears to be greater variability with eccentric than concentric or isometric testing of shoulder rotation. Factors that possibly contributed to variability are discussed. Clinicians should recognize potential sources of testing error when obtaining isokinetic measurements for use in clinical decision-making. Further refinement of isokinetic testing protocols at the shoulder is recommended.

Isolation of the leucine aminopeptidase gene from Aeromonas proteolytica. Evidence for an enzyme precursor

The leucine aminopeptidase of Aeromonas proteolytica (EC 3.4.11.10) is a monomeric metalloenzyme having the capacity to bind two Zn2+ atoms in the active site. Structural information of this relatively small aminopeptidase that could illuminate the catalytic mechanism of the metal ions is lacking; hence, we have obtained sequences from the purified enzyme, cloned the corresponding gene, and expressed the recombinant protein in Escherichia coli. The deduced primary amino acid sequence of this secreted protease suggests a potential signal peptide at the NH2 terminus. Expression of the recombinant and native proteins in E. coli and in extracts of culture media of A. proteolytica indicates that the aminopeptidase is secreted as an active and thermosensitive 43-kDa protein that is rapidly transformed to thermostable forms of 30 and 32 kDa. Comparison of the deduced amino acid sequence of the A. proteolytica leucine aminopeptidase with other Zn(2+)-binding metalloenzymes failed to show homologies to the consensus binding sequence His-Glu-X-X-His for the metal ion.

The flavivirus envelope protein E: isolation of a soluble form from tick-borne encephalitis virus and its crystallization

By the use of limited trypsin digestion of purified virions, we generated a membrane anchor-free and crystallizable form of the tick-borne encephalitis virus envelope glycoprotein E. It retained its reactivity with a panel of monoclonal antibodies, and only subtle structural differences from the native protein E were recognized. Treatment with the bifunctional cross-linker dimethylsuberimidate resulted in the formation of a dimer. Crystallization experiments yielded hexagonal rod-shaped crystals suitable for X-ray diffraction analysis.

A randomized, double-blind trial of prostaglandin E2 gel for cervical ripening and meta-analysis

The ability of prostaglandin E2 to prepare the unripe cervix before an indicated labor induction is controversial. We therefore tested 100 pregnant women in a randomized, double-blind trial with intracervical prostaglandin E2 gel, 0.5 mg. The 53 women who received the placebo gel had an outcome similar to that of the 47 women who received the prostaglandin E2 gel. The mean change in cervical score, mean application-to-delivery interval, incidence of uncomplicated spontaneous labor, incidence of cesarean delivery for a failed induction, and the overall cesarean section rate were not significantly different for the two groups. A meta-analysis, incorporating 18 studies of 1811 patients who received a single application of at least 5 mg prostaglandin E2 gel intravaginally or 0.5 mg intracervically, demonstrated no significant decrease in the overall cesarean delivery rate (p = 0.85). We conclude that the use of single-dose intracervical prostaglandin E2 gel for cervical ripening has little effect on labor induction. Moreover, the use of single-dose intracervical or intravaginal prostaglandin E2 gel does not alter the incidence of cesarean delivery, even when large numbers of patients are analyzed by combining the results of similar reports.

HIV-1 protease: mutagenesis of asparagine 88 indicates a domain required for dimer formation

Considerable interest exists in the HIV-1 protease for biochemical studies as a potential therapeutic target of acquired immunodeficiency syndrome. We have produced the retroviral enzyme in E. coli from a synthetic gene encoding the protease that was constructed by assembling six overlapping and complementary oligonucleotides into the vector pKK223-3. When expressed in E. coli, the recombinant protease was able to correctly process the HIV-1 core protein p24 from a beta-galactosidase-gag fusion protein and to use a heptapeptide as a substrate for proteolytic cleavage. A single base pair mutation was identified in a recombinant that resulted in the substitution of lysine for asparagine at position 88 and a significant loss of enzyme activity. Through site-directed mutagenesis, the Asn88 was changed to five other residues representative of all classes of amino acids. The correlation between enzyme activity and amino acid substitution suggests that the protease domain surrounding position 88 affects the protein's potential for forming an active homodimeric protein and hence, indicates a biochemical interaction that could be inhibited by novel antiviral compounds.

A model of orthopaedic dysfunction for clinical decision making in physical therapy practice

This model serves as a framework for the critical analysis of current practice concepts. The analysis obtained from using this model should be integrated with other physiological systems of the body during examination and treatment processes. Currently used as a basis for graduate study in orthopaedic physical therapy, the model helps students identify fundamental research questions, compare various examination and treatment philosophies, and comprehend generic treatment goals and strategies.

Peripheral placental separation: a review

Marginal placental bleeding is a distinct entity, marked (usually) by minor degrees of vaginal bleeding and significantly associated with premature labor and premature rupture of the membranes. Pathologically it is characterized by an adherent marginal placental hematoma, which shows varying degrees of film deposition and leukocytic infiltration depending on the age of the clot. Marginal placental bleeding may occur only once or be repeated many times. It usually is not fatal to mother or fetus per se. The chief clinical significance of the marginal placental bleed is its tendency to be confused with placenta previa. The perinatal mortality associated with perpheral placental separation is largely that of prematurity.