LARP4 is an RNA-binding protein that binds nuclear-encoded mitochondrial mRNAs to promote mitochondrial function

Mitochondria-associated RNA-binding proteins (RBPs) have emerged as key contributors to mitochondrial biogenesis and homeostasis. With few examples known, we set out to identify RBPs that regulate nuclear-encoded mitochondrial mRNAs (NEMmRNAs). Our systematic analysis of RNA targets of 150 RBPs identified RBPs with a preference for binding NEMmRNAs, including LARP4, a La RBP family member. We show that LARP4's targets are particularly enriched in mRNAs that encode respiratory chain complex proteins (RCCPs) and mitochondrial ribosome proteins (MRPs) across multiple human cell lines. Through quantitative proteomics, we demonstrate that depletion of LARP4 leads to a significant reduction in RCCP and MRP protein levels. Furthermore, we show that LARP4 depletion reduces mitochondrial function, and that LARP4 re-expression rescues this phenotype. Our findings shed light on a novel function for LARP4 as an RBP that binds to and positively regulates NEMmRNAs to promote mitochondrial respiratory function.

Structural variants drive context-dependent oncogene activation in cancer

Higher-order chromatin structure is important for the regulation of genes by distal regulatory sequences^1,2. Structural variants (SVs) that alter three-dimensional (3D) genome organization can lead to enhancer-promoter rewiring and human disease, particularly in the context of cancer³. However, only a small minority of SVs are associated with altered gene expression^4,5, and it remains unclear why certain SVs lead to changes in distal gene expression and others do not. To address these questions, we used a combination of genomic profiling and genome engineering to identify sites of recurrent changes in 3D genome structure in cancer and determine the effects of specific rearrangements on oncogene activation. By analysing Hi-C data from 92 cancer cell lines and patient samples, we identified loci affected by recurrent alterations to 3D genome structure, including oncogenes such as MYC, TERT and CCND1. By using CRISPR-Cas9 genome engineering to generate de novo SVs, we show that oncogene activity can be predicted by using 'activity-by-contact' models that consider partner region chromatin contacts and enhancer activity. However, activity-by-contact models are only predictive of specific subsets of genes in the genome, suggesting that different classes of genes engage in distinct modes of regulation by distal regulatory elements. These results indicate that SVs that alter 3D genome organization are widespread in cancer genomes and begin to illustrate predictive rules for the consequences of SVs on oncogene activation.

Modelling end-pumped passively Q-switched Nd-doped crystal lasers: manifestation by a Nd:YVO4/Cr4+:YAG system with a concave-convex resonator

A theoretical model for the passively Q-switched (PQS) operation which includes the spatial overlapping between the pump and lasing modes under the thermal lensing effect is developed to give a transcendental equation that can directly determine the critical parameters such as pulse energy, pulse repetition rate, and pulse width for the PQS performance. More importantly, an analytical function which gives the approximate solution for the transcendental equation as well as a specific critical criterion for good PQS operation are derived for practical analyses and design. A Nd:YVO₄/Cr⁴⁺:YAG system with a concave-convex resonator which can achieve fairly stable PQS pulse trains even at a high pump level is further exploited to manifest the proposed spatially dependent model. The good agreement between the experimental results and the theoretical predictions is verified to show the feasibility of the proposed model for designing high-power PQS lasers with high accuracy.

Exploiting concave-convex linear resonators to design end-pumped solid-state lasers with flexible cavity lengths: Application for exploring the self-mode-locked operation

The characteristics of a convex-concave linear resonator under the thermal lensing effect are theoretically analyzed to find an analytical model for designing end-pumped solid-state lasers with flexible cavity lengths. By exploiting the design model, the power scaling for continuous-wave operation under strong thermal lensing can be easily achieved in the proposed resonator with different cavity lengths. Furthermore, the proposed resonator is applied to explore the exclusive influence of cavity length on the self-mode-locked (SML) operation. It is discovered that the lasing longitudinal modes will split into multiple groups in optical spectrum to lead to a multi-pulse mode-locked temporal state when the cavity length increases. Finally, a theoretical model is derived to reconstruct the experimental results of SML operation to deduce a simple relationship between the group number of lasing modes and the cavity length.

Monolithic dual-polarization self-mode-locked Nd:YAG 946-nm lasers: controlling beat frequency and observation of temporal chaos

The self-mode-locked (SML) operation at 946 nm can be achieved with a monolithic Nd:YAG crystal when the pump power is above the threshold of the multiple-longitudinal-mode generation. The SML output is further found to include two orthogonal polarization components with a beat frequency coming from the birefringence effect in the laser crystal. The beat frequency can be widely adjusted in the range of 5-220 MHz by controlling the cooling temperature. The present experiment also confirms the theoretical prediction that the two-mode operation generally exhibits the chaotic dynamics when the frequency difference is sufficiently close to the relaxation frequency.

Synchronized self-mode-locked 1061-nm and 1064-nm monolithic Nd:YAG laser at cryogenic temperatures with two orthogonally polarized emissions: generation of 670 GHz beating

A dual-wavelength self-mode-locked monolithic Nd:YAG laser at 1061 and 1064 nm is realized at cryogenic temperatures. At an incident pump power of 5.5 W, the total output power can reach 2.5 W and the mode-locked pulse width is 29 ps at a pulse repetition rate of 7.75 GHz. The synchronization of the dual-wavelength emissions leads to a beat frequency of 670 GHz in the individual mode-locked pulse. It is further discovered that the laser output consists of two orthogonally polarized components with a central frequency difference of 127 MHz. The central frequency difference between two orthogonal polarizations mainly arises from the external mechanical stress introduced by the copper holder for the laser crystal.

Generation of orthogonally polarized self-mode-locked Nd:YAG lasers with tunable beat frequencies from the thermally induced birefringence

The simultaneous self-mode-locking of two orthogonally polarized states in a Nd:YAG laser is demonstrated by using a short linear cavity. A total output power of 3.8 W can be obtained at an incident pump power of 8.2 W. The beat frequency Δfc between two orthogonally polarized mode-locked components is observed and measured precisely. It is found that the beat frequency increases linearly with an increase in the absorbed pump power. The origin of the beat frequency can be utterly manifested by considering the thermally induced birefringence in the Nd:YAG crystal. The present result offers a promising approach to generate orthogonally polarized mode-locked lasers with tunable beat frequency.

Analysis of the optimal temperature for the cryogenic monolithic Nd:YAG laser at 946-nm

The optimal temperature for the cryogenic monolithic Nd:YAG laser at 946-nm is theoretically and experimentally analyzed. It is clear that decreasing temperature can considerably eliminate the thermal population at the lower laser level to enhance the quantum efficiency. However, the narrowing of the absorption bandwidth for the gain medium leads to a reduction of the effective absorption efficiency as the temperature is decreased. Consequently, an optimal temperature for the maximum output power is found to be in the range of approximately 120 K to 140 K. It is experimentally verified that employing a pump source with a narrower emission spectrum linewidth contributes a more efficient output for the cryogenic laser.

Cryogenically monolithic self-Raman lasers: observation of single-longitudinal-mode operation

A cryogenically monolithic Nd:YVO4 self-Raman laser is experimentally explored and theoretically analyzed. The variation of the stimulated Raman scattering (SRS) threshold on the temperature is found to be nonlinear because the reduction of thermal lensing enlarges the cavity mode size. In spite of the nonlinear variation of the SRS threshold on the temperature, the overall SRS output power can be efficiently increased from 0.78 to 1.36 W for temperature decreasing from 285 to 80 K at an absorbed power of 17.2 W. More interestingly, the single-longitudinal-mode operation is experimentally achieved when temperature is lower than 125 K.

24-W cryogenically cooled Nd:YAG monolithic 946-nm laser with a slope efficiency >70

A high-power efficient monolithic Nd:YAG 946-nm laser is demonstrated at the cryogenic temperature. By exploring the absorption and the fluorescence spectra of the Nd:YAG crystal, it reveals the fact that the absorption bandwidth at 808 nm is narrowing and the fluorescence intensity at 1061 nm is significant enhanced when the temperature is decreased. The temperature dependence of the lasing threshold at 946 nm is found to display a minimum value near a temperature of 170 K. At an incident pump power of 34.5 W, the local heating leads the optimum temperature to be approximately 120 K and the maximum output power can reach 24.4 W with the conversion efficiency of 71% as well as the slope efficiency up to 75%.

An energy adjustable linearly polarized passively Q-switched bulk laser with a wedged diffusion-bonded Nd:YAG/Cr⁴⁺:YAG crystal

An energy adjustable passively Q-switched laser is demonstrated with a composite Nd:YAG/Cr⁴⁺:YAG crystal by applying a wedged interface inside the crystal. The theoretical model of the monolithic laser resonator is explored to show the energy adjustable feature with different initial transmissions of the saturable absorber at the horizontal axis. By adjusting the pump beam location across the Nd:YAG crystal, the output pulse energy can be flexibly changed from 10.9 μJ to 17.6 μJ while maintaining the same output efficiency. The polarization state of the laser output is found to be along with the polarization of the C-mount pump diode. Finally, the behavior of the multi-transverse-mode oscillation is also discussed for eliminating the instability of the pulse train.

Nd:YLF laser at cryogenic temperature with orthogonally polarized simultaneous emission at 1047 nm and 1053 nm

A Nd:YLF laser at cryogenic temperature is demonstrated for the first time with orthogonally polarized simultaneous emission at 1047 nm and 1053 nm. By exploring the temperature dependence of the fluorescence and the absorption spectra from the Nd:YLF crystal, the feasibility of simultaneous emission at low temperature is achieved. Due to the local heating from the pump absorption, the optimal temperature with respect to the pump power for balancing output powers of simultaneous emission is thoroughly explored. At the optimal temperature of 138 K, the total output power of the simultaneous emission can reach 3.1 W at an incident pump power of 7.9 W, corresponding to the optical to optical slope efficiency up to 43%.

High-repetition-rate quasi-CW side-pumped mJ eye-safe laser with a monolithic KTP crystal for intracavity optical parametric oscillator

We demonstrate a high-repetition-rate millijoule passively Q-switched eye-safe Nd:YVO(4) laser pumped by a quasi-CW diode stack. A theoretical analysis has been explored for the design criteria of generating TEM(n,0) mode in the diode-stack directly side-pumping configuration. We successfully generate TEM(n,0) modes at 1064 nm by adjusting the gain medium with respected to the laser axis. We further observe the spatial cleaning ability for generating an nearly TEM(0,0) mode output at 1573 nm with a monolithic OPO cavity. At the repetition rate up to 200 Hz, the output pulse energy reaches 1.21 mJ with the threshold pump energy of 17.9 mJ.

Influence of output coupling on the performance of a passively Q-switched Nd:YAG laser with intracavity optical parametric oscillator

A singly-resonant intracavity optical parametric oscillator (OPO), pumped by a passively Q-switched Nd:YAG laser, is systematically investigated by means of a series of the output mirrors with various reflectivities for the fundamental wavelength at 1064 nm. Experimental results reveal that the output mirror with partial reflectivity instead of high reflection at 1064 nm not only is practicable to avoid the optical coatings damaged, but also enhances the dual-wavelength output efficiency for the OPO signal and fundamental laser waves. The overall optical-to-optical conversion efficiency is enhanced from 6.4% to 8.2% for the reflectivity decreasing from 99.8% to 90%.

Compact high-pulse-energy passively Q-switched Nd:YLF laser with an ultra-low-magnification unstable resonator: application for efficient optical parametric oscillator

We exploit an ultra-low-magnification unstable resonator to develop a high-pulse-energy side-pumped passively Q-switched Nd:YLF/Cr⁴⁺:YAG laser with improving beam quality. A wedged laser crystal is employed in the cavity to control the emissions at 1047 nm and 1053 nm independently through the cavity alignment. The pulse energies at 1047 nm and 1053 nm are found to be 19 mJ and 23 mJ, respectively. The peak powers for both wavelengths are higher than 2 MW. Furthermore, the developed Nd:YLF lasers are employed to pump a monolithic optical parametric oscillator for confirming the applicability in nonlinear wavelength conversions.

CXCR4 activation maintains a stem cell population in tamoxifen-resistant breast cancer cells through AhR signalling

Background:

Tamoxifen is commonly used for breast cancer therapy. However, tamoxifen resistance is an important clinical problem. Continuous treatment with conventional therapy may contribute to cancer progression in recurring cancers through the accumulation of drug-resistant cancer progenitors.

Methods:

To investigate signalling mechanisms important for the maintenance and viability of drug-resistant cancer progenitors, we used microarray analysis, PCR array for genes involved in cancer drug resistance and metabolism, flow cytometry, soft agar colony formation assay, in vivo tumourigenicity assay and immunohistochemical analysis using tamoxifen-sensitive and tamoxifen-resistant breast cancer MCF7 cells.

Results:

Downregulation of CXCR4 signalling by small molecule antagonist AMD3100 specifically inhibits growth of progenitor cell population in MCF7(TAM-R) cells both in vitro and in vivo. Microarray analysis revealed aryl hydrocarbon receptor (AhR) signalling as one of the top networks that is differentially regulated in MCF7(TAM-R) and MCF7 xenograft tumours treated with AMD3100. Further, small molecule antagonists of AhR signalling specifically inhibit the progenitor population in MCF7(TAM-R) cells and growth of MCF7(TAM-R) xenografts in vivo.

Conclusion:

The chemokine receptor CXCR4 maintains a cancer progenitor population in tamoxifen-resistant MCF7 cells through AhR signalling and could be a putative target for the treatment of tamoxifen-resistant breast cancers.

Microsatellite DNA markers indicate three genetic lineages in East Asian indigenous goat populations

The genetic differentiation and phylogenetic relationships of 18 indigenous goat populations from seven East Asian countries were analysed based on data obtained from 26 microsatellite DNA markers. The mean number of alleles (MNA) per population ranged from 2.5 to 7.6, with an average of 5.8. Genetic variability estimated from MNA and heterozygosity (H(E) and H(O) ) were relatively low in coastal and island populations. A heterozygous deficiency within populations (F(IS) = 0.054, P < 0.001) and total inbreeding (F(IT) = 0.181, P < 0.01) were observed, and genetic differentiation in the populations (F(ST) ) was 13.4%. The results of Bayesian model-based clustering and a neighbour-joining tree based on Nei's genetic distance showed that Asian goat populations could be subdivided into at least the following three genetic clusters: East Asian, Southeast Asian and Mongolian. These results are in close accordance with conventional morphological and geographical classifications and migration history.

Orthogonally polarized dual-wavelength Nd:LuVO4 laser at 1086 nm and 1089 nm

A comparison between the fluorescence spectra of the Nd-doped vanadate crystals (Nd:YVO4, Nd:GdVO4, Nd:LuVO4) for the 4F3/2 → 4I11/2 transition is studied. We numerically analyze the condition of gain-to-loss balance via an uncoated intracavity etalon to achieve the dual-wavelength operation. We further experimentally demonstrate the orthogonally polarized dual-wavelength laser with a single Nd:LuVO4 crystal. The simultaneous dual-wavelength Nd:LuVO4 laser at 1085.7 nm in σ polarization and 1088.5 nm in π polarization is realized. At an incident pump power of 12 W, the average output power obtained at 1085.7 nm and 1088.5 nm is 0.4 W and 1.7 W, respectively.

Muscle control associated with isometric contraction in different joint positions

The purpose of this study was to investigate the dependence of the surface EMG and varied internal effort due to different joint positions, and its muscle control strategies. Ten healthy subjects performed a fixed level (40% MVC measured in the neutral position) of isometric dorsiflexion and plantarflexion contraction in the ankle neutral, dorsiflexion, and plantarflexion positions. Quantitative EMG analyses with feature extraction in the time, frequency domain, as well as time-varying spectrum were employed to estimate recruitment pattern, code rating, and recruitment stationarity of activated motor units. Both RMS and median frequency of the tibial anterior (TA) and gastrocnemius (GS) were strongly dependent on foot position (p < .001). Dominant firing rate of the TA muscle during the effort related isometric contraction was significant different with respect to ankle position (p < .05). Irrespective of ankle position, the regression slope of median frequency across time was not different from zero for both TA and GS muscles (p > .05). Identical torque exertion in different ankle positions called for considerable changes of control strategies of motor units. Possible mechanisms could be augmented excitatory central afferents and release of inhibition from Golgi tendon organs in compensation for biomechanical disadvantage in shorter muscle length.

A double-blind, placebo-controlled, multicenter study of Cerebrolysin for Alzheimer's disease

OBJECTIVE

To assess the efficacy and safety of Cerebrolysin over 4 weeks in patients with probable Alzheimer's disease (AD).

DESIGN

A 4-week randomized, double-blind, placebo-controlled, multicenter clinical trial. An unequal (Cerebrolysin:placebo = 2:1) randomization was used to assign more patients to the treatment group.

SETTINGS

University medical centers and community geriatric hospitals in Korea.

PARTICIPANTS

Fifty-three men and women at least 50 years of age admitted to hospitals with mild to moderate AD and otherwise in good health.

INTERVENTION

The treatment group (n = 34) received Cerebrolysin (30 mL Cerebrolysin in 100 mL physiologic saline IV) once a day from Monday to Friday for 4 weeks. The control group (n = 19) received placebo.

MEASUREMENTS

Primary outcome measures were the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) and the Clinical Global Impression of Severity/ Change (CGIS/C). Secondary outcome measures included Mini-Mental State Examination (MMSE), Geriatric Depression Scale (GDS), Katz Index of Activities of Daily Living (ADL), and Lawton Instrumental Activities of Daily Living (IADL) Scale.

RESULTS

After 4 weeks of treatment, Cerebrolysin-treated patients demonstrated significant improvements in the ADAS-Cog (P = .02), CGIS/C (P = .01), and MMSE (P = .04) compared with placebo-treated patients. Among Cerebrolysin-treated patients, 82%, 62%, and 44% were rated improved on ADAS-Cog, CGIS/C, and MMSE, respectively, compared with 31.6%, 22%, and 17% of placebo-treated patients, respectively. However, there were no significant improvements in the Cerebrolysin group compared with the placebo group on the GDS, ADL, and IADL. There were no dropouts in either groups, with 100% compliance to Cerebrolysin and placebo. Only one patient reported a febrile sensation, which was transient and mild in severity.

CONCLUSIONS

This study indicates that Cerebrolysin is a safe drug that improves the cognitive deficits and global function in patients with mild to moderate AD. Long-term efficacy and safety of Cerebrolysin in Alzheimer's patients should be evaluated in the future.

Ligand-dependent interactions of coactivators steroid receptor coactivator-1 and peroxisome proliferator-activated receptor binding protein with nuclear hormone receptors can be imaged in live cells and are required for transcription

Members of the nuclear receptor superfamily are thought to activate transcription by recruitment of one or more recently identified coactivator complexes. Here we demonstrate that both peroxisome proliferator-activated receptor binding protein (PBP) and steroid receptor coactivator-1 (SRC-1) are required for ligand-dependent transcription of transiently transfected and chromosomally integrated reporter genes by the estrogen receptor (ER) and retinoic acid receptor (RAR). To examine ligand-dependent interactions between nuclear receptors and specific coactivators in living cells, these proteins were tagged with cyan (CFP) and yellow (YFP) mutants of the green fluorescent protein. Fluorescence resonance energy transfer (FRET) from the CFP to the YFP indicated interaction between the receptor and coactivator. CFP fusions to RAR or its ligand-binding domain exhibited rapid ligand-dependent FRET to YFP-tagged nuclear receptor interaction domains of the coactivators SRC-1 and PBP. The ER-ligand-binding domain, unlike RAR, also exhibited some basal interaction with coactivators in unstimulated cells that was abolished by the receptor antagonists tamoxifen or ICI182,780. Inhibition of FRET by tamoxifen but not ICI182,780 could be reversed by estradiol, whereas estradiol-enhanced FRET could not be inhibited by either antagonist, indicating that ligand effects can show varying degrees of hysteresis. These findings suggest that ligand-dependent transcriptional activities of the RAR and ER require concurrent or sequential recruitment of SRC-1 and PBP-containing coactivator complexes.

A genetically encoded, fluorescent indicator for cyclic AMP in living cells

Cyclic AMP controls several signalling cascades within cells, and changes in the amounts of this second messenger have an essential role in many cellular events. Here we describe a new methodology for monitoring the fluctuations of cAMP in living cells. By tagging the cAMP effector protein kinase A with two suitable green fluorescent protein mutants, we have generated a probe in which the fluorescence resonance energy transfer between the two fluorescent moieties is dependent on the levels of cAMP. This new methodology opens the way to the elucidation of the biochemistry of cAMP in vivo.

Rectal leiomyosarcoma diagnosed by endoscopic ultrasonography

A 67 year-old man was admitted to the Tainan Municipal Hospital due to a protruding mass, usually noted during defecation. Digital examination revealed a single, smooth, large mass over the rectum, occupying almost the entire lumen. Colonoscopy, barium enema, and computed tomography (CT) demonstrated a submucosal tumor of the rectum. Endoscopic ultrasound (EUS) study showed that the tumor originated from the muscle layer. Based on the size, margin and echogenicity of the mass, a malignant neoplasm, probably leiomyosarcoma, was diagnosed. Post-operative histologic examination confirmed that the resected tumor was leiomyosarcoma. Existing ancillary procedures like colonoscopy, abdominal CT, magnetic resonance image (MRI), and barium enema are neither reliable nor accurate in locating which layer the lesion originates. Colonoscopic biopsy is disappointing since submucosal tumor is usually inaccessible. EUS study can provide us with a more distinct image with regards to tumor origin, size, margin and echogenicity. This report emphasizes the important role of EUS in the pre-operative diagnosis of submucosal tumors of the rectum. Furthermore, this tool can aid the surgeons whether wide excision or an abdomino-perineal resection should be performed.

Cyclic and linear oligocarbamate ligands for human thrombin

Several classes of compounds have been tested as potential inhibitors of the serine protease thrombin, an important regulator of blood coagulation cascades. We describe here the discovery of a new class of thrombin inhibitors based on an unnatural carbamate biopolymer. Oligocarbamate thrombin inhibitors were identified through the screening of diverse cyclic trimer, cyclic tetramer, and linear tetramer libraries using the one bead, one peptide method. Whereas the cyclic trimer oligocarbamate ligands bound thrombin with modest affinity, a cyclic tetramer oligocarbamate inhibited thrombin with an apparent Ki of 31 nM. Linear oligocarbamate tetramers bound thrombin with inhibition constants in the 100-nM range. These nonpeptidic, oligomeric molecules may provide the basis for further drug development and studies of thrombin ligand interactions.

Changes of neonatal mortality rate between 'pre' and 'post' surfactant period

The objective of this study was to determine how the neonatal mortality rate has changed since surfactant (S) therapy was introduced in our Neonatal Intensive Care Unit (NICU), and to evaluate the efficacy of surfactant therapy in respiratory distress syndrome (RDS) patients. Incidences of risk babies such as outborns, prematurity, low birth weight infants and RDS, and neonatal mortality rates were compared between 'pre' (control, 1988 to 1991, n=4,861) and 'post' S period (study, 1993 to 1996, n=5,430). In RDS patients of 'post' S period, neonatal mortality rate was compared between S-treated and non-treated patients, and chest X-ray and ventilatory parameters were compared between pre- and post-72 hr of surfactant treatment. Surfactant therapy showed short term effects, judging by the decrease of early neonatal deaths and improvement of chest X-ray and ventilatory parameters in RDS patients. The overall neonatal mortality rate had a tendency to decrease in spite of increased incidences of risk babies in 'post' S period but it was less than expected. The reasons were thought to be that we had a high proportion of risk babies, and there was some bias in patient selection for surfactant therapy and its use. In conclusion, with the active prevention of risk baby delivery and appropriate use of surfactant, better results could be expected.

The association between chronic illness and functional change among participants in a comprehensive geriatric assessment program

OBJECTIVE

To examine the association between chronic illness and functional status change during a 3-year period in older people enrolled in an in-home comprehensive geriatric assessment (CGA) and preventive care program.

DESIGN

Secondary analysis of data from a longitudinal cohort study.

SETTING

Santa Monica, California.

PARTICIPANTS

Two hundred two community-dwelling older persons (mean age at baseline was 81 years, 70% were women, and 72% reported good health) randomized to the intervention group in a trial of in-home comprehensive geriatric assessment and preventive care.

MEASUREMENTS

We studied 13 common chronic illnesses/conditions determined clinically from an annual comprehensive evaluation by gerontologic nurse practitioners (GNPs) in consultation with study geriatricians. These target conditions included hypertension, osteoarthritis, coronary artery disease, obesity, undernutrition, urinary incontinence, sleep disorders, falls, gait/balance disorders, hearing and vision deficits, depression, and unsafe home environment. The dependent variable was functional change as measured by instrumental activities of daily living (IADL) and basic activities of daily living (BADL) assessed at baseline and annually for 3 years by independent research personnel. Potential confounding variables, including comorbid conditions and other subject characteristics, were controlled for in the analyses.

RESULTS

Although functional status was similar at baseline, the presence of certain target conditions in this sample was associated significantly with functional decline in IADL and BADL during the 3-year period. Four conditions (gait/balance disorders, depression, unsafe home environment, and coronary artery disease) were associated with significant declines in IADL, and four conditions (gait/balance disorders, depression, hypertension, and urinary incontinence) were associated with significant declines in BADL. Conversely, subjects with obesity had no significant change in IADL or BADL throughout the study period and had less decline in IADL compared with nonobese subjects.

CONCLUSIONS

Certain chronic conditions, particularly gait/balance disorders and depression, are associated with significant decline in functional status in older persons who receive CGA. These findings may help identify older persons at risk for greatest functional decline despite participation in CGA and may also suggest the need for more effective intervention strategies in these individuals.

Detecting balance deficits in frequent fallers using clinical and quantitative evaluation tools

OBJECTIVE

This investigation sought to determine whether older idiopathic frequent fallers could be distinguished from healthy older adults on the basis of balance and movement coordination tests. A secondary objective was to determine the relationships among clinical balance test scores, balance performance data obtained by accelerometry, and quantitative motor coordination tests.

DESIGN

Two group comparison designs.

SETTING

A motor control research laboratory in a university setting.

PARTICIPANTS

The 16 subjects recruited for this study included eight healthy older subjects and eight age-matched idiopathic fallers.

MEASUREMENTS

Each participant's balance performance was assessed by accelerometry, as well as by coordination and clinical tests. Accelerometry scores, obtained by 1g accelerometers placed at the hip and on the head, were made with eyes open or closed, either standing on the floor or on a wedge of compliant foam. Clinical balance scores were obtained using variants of Romberg's test and the functional reach test. Motor coordination tests obtained included the heel-to-toe transition and rapid stepping tests.

MAIN RESULTS

Statistically significant differences were obtained between groups for all accelerometry variables except root mean square. All accelerometry variables were successful in discriminating between head and hip sites. Moreover, the amplitude of sway obtained from accelerometry data identified significant differences among the four test conditions. The Romberg test, using right leg alone with eyes open, showed a significant difference between fallers and healthy older subjects. Walking velocity was significantly faster for normal older subjects than for fallers (1.10 m/sec vs 0.80 m/sec). No significant between-group differences were obtained using the functional reach test. Coordination skills yielded significant between-group differences using the rapid stepping test but no significant differences between groups with the heel-toe transition test.

CONCLUSION

Accelerometry is an inexpensive and clinically useful technique that can distinguish between healthy older people and idiopathic frequent fallers. In conjunction with clinical procedures and commercially available tests to assess motor coordination, these techniques can identify older individuals susceptible to frequent falls.

Dressing the part

Wound care after cutaneous surgery can play an integral role in wound healing. Wound care regimens have changed dramatically over the last 35 years as the physiology of wound healing has become better understood. Foremost is the improvement in wound healing achieved by keeping the wound occluded and moist. This observation has led to an explosion of a whole new category of occlusive dressings at the surgeon's disposal in healing postoperative wounds. These dressings have numerous applications as discussed previously. Generally, for acute surgical wounds, occlusive dressings are most useful for split-thickness wounds, such as graft donor sites and after dermabrasion, chemical peel, or laser treatment, and full-thickness wounds allowed to heal by secondary intention. Occlusive dressings may have greater benefit for the treatment of chronic ulcers of varying etiologies. The different categories of dressings share the common disadvantage of being relatively expensive. For routine sutured wounds, the authors prefer the readily available and inexpensive Telfa-type dressing combined with a topical antibiotic ointment. Topical antiseptics are useful for reducing bacterial counts on intact skin in preparation for surgery. Povidone-iodine (Betadine) and chlorhexidine gluconate (Hibiclens) have emerged as the two agents of choice. However, antiseptics have been shown to be toxic to healing tissue, and should not be used on open wounds. In contrast, topical antibiotic ointments are safe to use on open wounds, effective in preventing wound infections, and promote wound healing by maintaining a moist wound environment. The authors prefer the combination antibiotic ointment Polysporin for routine postoperative wound care. Antibiotic prophylaxis in dermatologic surgery to prevent wound infection is appropriate in certain cases. Surgery performed on grossly contaminated or infected skin requires a full 7 to 10 day course of antibiotics. Procedures in anatomic areas considered contaminated as well as in clean areas with significant environmental or patient risk factors may benefit from antibiotic prophylaxis. The choice of antibiotics should be based on the organism most likely to cause wound infection at the particular surgical site. Evidence supports giving a single preoperative dose 1 hour before surgery with a second dose possible 6 hours later if the procedure is prolonged or delayed. The risk of bacterial endocarditis after dermatologic surgery is not known. Antibiotics are indicated for any procedure on obviously infected skin, but are not routinely required for very minor procedures, such as small biopsies, on intact skin. Antibiotic prophylaxis may be prudent for those patients classified as high risk by the (AHA). The antibiotic chosen should again cover the organism most likely to cause infection. One dose can be given 1 hour before surgery and repeated 6 hours postoperatively. Finally, wound healing can be greatly impacted by what the patient does or does not do after leaving the office. Therefore, wound care instructions should be clear, detailed, and provided in both oral and written form. Information should also be provided about what to expect as the wound heals.

Novel biopolymers for drug discovery

The solid phase synthesis and generation of libraries of "unnatural biopolymers" is described. These polymers are characterized by novel backbones and building blocks, the properties of which may modify their pharmacological and folding properties.

An unnatural biopolymer

A highly efficient method has been developed for the solid-phase synthesis of an "unnatural biopolymer" consisting of chiral aminocarbonate monomers linked via a carbamate backbone. Oligocarbamates were synthesized from N-protected p-nitrophenyl carbonate monomers, substituted with a variety of side chains, with greater than 99 percent overall coupling efficiencies per step. A spatially defined library of oligocarbamates was generated by using photochemical methods and screened for binding affinity to a monoclonal antibody. A number of high-affinity ligands were then synthesized and analyzed in solution with respect to their inhibition concentration values, water/octanol partitioning coefficients, and proteolytic stability. These and other unnatural polymers may provide new frameworks for drug development and for testing theories of protein and peptide folding and structure.

Dietary arginine requirement of young rainbow trout (Oncorhynchus mykiss)

1. Two growth trials were conducted with young rainbow trout (Oncorhynchus mykiss) to determine the dietary arginine requirement under conditions of rapid weight gain at 15 degrees C. 2. The growth requirement does not exceed 4.2 g arginine/16 g dietary nitrogen and, thus, is much lower than the value of 6.0 g arginine/16 g dietary nitrogen presently listed by the NRC for Chinook salmon and widely applied to all Salmonids. 3. Comparison of the present results with the arginine requirement of the chick reveals remarkable similarity despite the phylogenetic distance between the two species, and demonstrates the need to re-evaluate, as anomalously high, the presently-accepted value for Chinook salmon.

Methionine intake in rainbow trout (Oncorhynchus mykiss), relationship to cataract formation and the metabolism of methionine

Young rainbow trout were given diets containing graded levels of methionine for 16 wk. Analysis of the weight gain and food efficiency data showed the methionine requirement to be not more than 0.76% of the diet (1.9% of dietary protein). Activities of regulatory enzymes of the transulfuration pathway, methionine adenosyltransferase and cystathionine synthase in trout liver were not altered by changes in methionine intake. Concentrations of free serine in liver and plasma of the trout were high at low levels of methionine intake but fell as dietary methionine increased. This implied decreased flux through cystathionine synthase at low methionine intakes. Large increases in liver and plasma taurine occurred at high methionine intakes, implying enhanced transulfuration activity. Liver ornithine decarboxylase activity was reduced at the lowest level of dietary methionine used but the activity of S-adenosylmethionine decarboxylase was unchanged. Eye lenses of the trout given these diets were examined by a scanning lens monitor. Analysis of focal length variability with this equipment demonstrated that, if abnormality of the lens is to be avoided, a higher concentration of dietary methionine (0.96% or 0.6% methionine + 0.36% cystine) is needed than that required to maximize growth.

Dietary excesses of leucine influence growth and body composition of rainbow trout

This study examined the hypothesis that a diet containing excess leucine may promote protein deposition in the body of rainbow trout. Diets were formulated with wheat germ meal and crystalline amino acids as major nitrogen sources. In Experiment 1, diets containing 1.1, 1.5, 2.2, 2.7, 3.5, 4.5, 6.0 and 6.5% leucine in wheat germ meal-crystalline amino acid diets were fed to fingerling rainbow trout. Diets containing up to 6.5% leucine did not inhibit weight gain or food intake. Body protein concentration tended to decrease as dietary leucine increased. In Experiment 2, fish were fed similar diets containing 3.3, 6.2, 9.2 and 13.4% leucine. After 10-11 wk of feeding, gross lesions including scoliosis, deformed opercula, scale deformities, scale loss, spongiosis of epidermal cells and scale regeneration were observed in 20% of the fish fed diets containing 13.4% leucine. High dietary leucine did not depress plasma valine or isoleucine concentrations. Therefore, the gross lesions could be attributed to a toxic effect of excess dietary leucine. Polyamine concentrations, which were used as a metabolic indicator for growth, were not significantly different in the tissues of fish receiving different treatments, thus supporting the hypothesis that increasing dietary leucine did not increase body protein deposition.

Escherichia coli aspartate carbamoyltransferase: the probing of crystal structure analysis via site-specific mutagenesis

Crystal structures are known for aspartate carbamoyltransferase (ATCase) in the T and R states, with and without the allosteric activator adenosine triphosphate (ATP) or inhibitor cytidine triphosphate (CTP). Visual inspection of X-ray crystal structures does not provide all of the information necessary for the determination of structure--function relationships in protein molecules. This problem is compounded because the crystalline states of the molecule may introduce effects due to crystal packing, restricted flexibility and less than optimum enzymatic conditions. Therefore, alternative techniques are required to test mechanisms conjectured from three-dimensional crystal structures of proteins. The technique of site-specific mutagenesis allows the researcher to test structure--function models based on three-dimensional structures and to obtain further insight into characteristics of the enzyme. Site-specific mutagenesis has been used to probe residues believed to be critical in the structure and function of ATCase. Selection of residues to be mutated has depended extensively on three-dimensional crystal structures of the enzyme. To date, 48 site-specific mutations at 37 different amino acid sites have been published. Although a total of 118 mutants at 58 different sites has been communicated to our laboratory, only published mutants will be considered in this review. In this paper, we compile for the first time, review, and analyze the site-specific mutants of ATCase. Site-specific mutagenesis of proteins has become a powerful technique in modern-day molecular biology, especially in studying a molecule as large as aspartate carbamoyltransferase. In this review, the role of site-specific mutagenesis of ATCase is discussed and improvements in the analysis are suggested.

The distribution of zinc and copper in plasma, erythrocytes and erythrocyte membranes of rainbow trout (Salmo gairdneri)

1. The zinc and copper concentration of plasma was determined in rainbow trout, lake trout, walleye and whitefish. 2. These fish had mean plasma zinc concentrations ranging from 9.3 to 15.1 ppm and copper concentrations from 0.6 to 1.3 ppm. 3. In rainbow trout, the concentration of zinc and copper is greater in the erythrocyte membrane than in the total erythrocyte. 4. Ultrafilterable plasma zinc and copper concentration in rainbow trout was determined to be 0.03 and 0.019 ppm, respectively. 5. Dialysis of rainbow trout plasma against 20 mM EDTA results in removal of 99% of the zinc and 88% of the copper from plasma proteins.

The biological activity of 25-hydroxycholecalciferol and 1,25--dihydroxycholecalciferol for rainbow trout (Salmo gairdneri)

Dietary 25-hydroxycholecalciferol (25-hydroxycholecalciferol (25-OH-D3) and 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] showed vitamin D activity in rainbow trout. However, inclusion of dietary cholecalciferol (vitamin D3 or D3), ergocalciferol (vitamin D2 or D2), 25-OH-D3 or 1,25-(OH)2D3 did not result in the presence of detectable levels of vitamin D or 25-OH-D in the blood plasma of the fish. Fish fed the diet devoid of vitamin D over an extended period of time showed symptoms of a droopy-tail or "lordosis-like" syndrome that appeared to be related to muscle weakness since x-ray examination indicated no abnormality in vertebral development. The requirement for vitamin D as cholecalciferol was in excess of 1600 IU/kg diet and may be as high as, or higher than 2400 IU/kg diet.

Relative biopotency of dietary ergocalciferol and cholecalciferol and the role of and requirement for vitamin D in rainbow trout (Salmo gairdneri)

A growth assay was conducted for six consecutive 28-day periods by using triplicate groups of 110 rainbow trout with an average initial body weight of 3.0 g. Ergocalciferol (vitamin D2 or D2) and cholecalciferol (vitamin D3 or D3) were included to provide levels of 200, 400 and 800 iu/kg in a semipurified casein, gelatin diet. Further treatments with 0 vitamin D and 1600 IU/kg of D3 were also included. The resulting growth curves were significant for parallelism. Statistical analysis showed that D3 was 3.27 times as potent as D2 (limits 2.33 to 4.58). The dietary requirement for D3 was found to be in excess of 800 iu/kg of diet. Vitamin D-deficient fish showed no change in bone ash but exhibited clinical manifestations of tetany with no hypocalcemia. A complete absence of tetany was seen only in the groups fed 800 and 1600 IU of D3 per kilogram. None of the levels of D2 used were sufficient to completely alleviate symptoms of this disorder. These studies of rainbow trout provide evidence that vitamin D is required for the normal functioning of white muscle without altering the calcium content of the plasma or epaxial musculature.

Effect of oxidized fish oil, DL-alpha-tocopheryl acetate and ethoxyquin supplementation on the vitamin E nutrition of rainbow trout (Salmo gairdneri) fed practical diets

A factorial experiment was conducted using two degrees of oxidation of the 7.5% supplemental fish oil (peroxide values of 5 and 120 meq/kg oil), two levels of supplemental DL-apha-tocopheryl acetate (0 and 33 mg/kg diet) and two levels of ethoxyquin (0 and 125 mg/kg diet) supplementation. Dietary thiobarbituric acid number, weight percentage of polyunsaturated fatty acids and omega-three fatty acids in the total fatty acids were significantly (P less than 0.05) different between diets with fresh and highly oxidized oil. Dietary RRR-alpha-tocopherol was significantly (P less than 0.05) reduced by the addition of highly oxidized oil after 24 weeks storage of the feed while supplemental DL-alpha-tocopheryl acetate level was not changed. Fish fed the various diets showed no differences in growth, feed:gain ratio, carcass composition or plasma glutathione peroxidase activity. The mortality, percent red cells hemolyzed by hydrogen peroxide, plasma and liver RRR-alpha-tocopherol concentrations were significantly (P less than 0.05) affected by the addition of highly oxidized oil or DL-alpha-tocopheryl acetate but not by ethoxyquin except that mortality was reduced by supplementary ethoxyquin. The results of this study suggested that no vitamin E or ethoxyquin supplementation was needed to prevent a deficiency of vitamin E in rainbow trout fed a practical diet containing 7.5% of a good quality herring oil for 24 weeks.

Influence of dietary biotin level on growth, metabolism and pathology of rainbow trout

Supplementation of a dry diet containing herring and soybean meals with D biotin had no effect on the feed comsumption, growth or mortality of rainbow trout in a 28 week experiment. In a second experiment two series of diets were used: practical, based upon herring and soybean meals, and purified, based upon casein and gelatin. The basal levels of biotin in the two series of diets were: 0.51 and 0 mg/kg, respectively. There were four treatment groups in each of the two diet series: the practical diets were either supplemented with 0.5 mg D biotin/kg or 10% of either raw or heated egg white was added to the diet. The purified diets were supplemented with graded levels of D biotin (0, 0.25 0.5, or 1.0 mg/kg). Raw egg white (1%) was added to the biotin unsupplemented diet. Feeding these diets to rainbow trout for 24 weeks showed that both the practical diet containing egg white, and the unsupplemented, purified diet were biotin deficient, all the other diets contained adequate amounts of biotin to support growth and prevent mortality. Neither supplementation of the practical diet nor adding more than 0.25 mg D biotin/kg to the purified diet resulted in any improvement in growth however the biotin levels in the livers were greater for the fish which had received the higher levels of dietary biotin, but these increased levels of biotin did not influence the activity of acetyl CoA carboxylase. The biotin deficient fish were anorexic, and exhibited degeneration of the gills: shortening and thickening of the lamellae and hypertrophy and hyperplasia of the heterogenous epithelial cells of the lamellae.

Influence of level and type of dietary protein, and of level of feeding on feed utilization by rainbow trout

In the first experiment, diets with 40%, 50% and 60% protein containing herring and soybean meals, and diets with 50% and 60% protein containing herring and soybean protein concentrates were fed at 100%, 85% and 70% of the ad libitum intake. Both increasing the protein level and using the concentrated protein sources resulted in lower gains, and in increases in the amounts of digestible protein and energy consumed for the deposition of protein and energy in the fish carcasses. This difference between the herring and soybean meals, and protein concentrates was not due to differences between their digestibilities. Restriction of feed intake reduced gain, but within these lower levels of gain, the 50% and 60% protein diets have higher final body weights than the 40% protein diet. Restriction of feed intake resulted in carcasses with higher protein and lower fat contents. In the second experiment, two series of diets containing either 40%, 35%, 30% or 25% protein from both herring and soybean meals, or 35%, 30% and 25% protein from herring meal were fed. Reducing the protein level below 40% resulted in lower final body weights, higher feed: gain ratios and carcasses with more protein and less fat. Comparisons of the isonitrogenous pairs of diets showed no differences in final body weights, feed: gain ratios and carcass composition. Reducing the protein level in the diet reduced the amount of protein consumed per unit protein level in the diet reduced the amount of protein consumed per unit protein deposition, but increased the amount of gross energy per unit energy deposited in the carcass.

Amino acid composition of digesta taken from swine receiving diets containing soybean or rapeseed meals as sole source of protein

The usefulness of amino acid digestibility measurements as indices of availability can be evaluated by comparing the amino acid composition of distal ileal digesta (where absorption is believed to be complete) with that in the rectum. Two semipurified diets containing either soybean or rapeseed oil meals were each fed to four castrated male pigs of 60 kg liveweight. The pigs were sacrified and samples of digesta were removed from the stomach, duodenum, jejunum, ileum, cecum, colon, and rectum. The concentrations of nitrogen and the proportions of 14 amino acids in the samples were studied. Digesta taken from the duodenum contained the greatest concentration of nitrogen; the nitrogen concentration decreased through the small intestine, and then remained constant through the large intestine. Comparing the ileal and rectal digesta, there were no significant differences in the proportions of valine, arginine, serine, tyrosine, threonine, phenylalanine, and aspartic acid for both diets. This was also true for lysine for the soybean meal diet and for methionine and alanine for the rapeseed meal diet, so that for these amino acids, digestibility should be a good estimate of availability. However, there were lower proportions of leucine plus glycine, proline, and glutamic acid in the rectal than in the ileal contents for both diets, and for lysine in the rapeseed meal diet, suggesting that digestibility values would overestimate availability. In contrast, there were higher proportions of isoleu-cine in the rectal than in the ileal contents for both diets, and of methionine and alanine for the soybean meal diet, suggesting that digestibilities would underestimate the availabilities of these amino acids.Partition of the digesta and the water-soluble digestion marker (polyethylene glycol) in the stomach precluded reliable quantitation of digesta flows through the ileum, but the experiment suggests that such quantitative measures would provide a basis for more valid estimates of amino acid availabilities than measurements of the amounts of amino acids voided in the feces.