Efficiency and spectrum enhancement in a tapered free-electron laser amplifier.

We report the first experimental characterization of efficiency and spectrum enhancement in a laser-seeded free-electron laser using a tapered undulator. Output and spectra in the fundamental and third harmonic were measured versus distance for uniform and tapered undulators. With a 4% field taper over 3 m, a 300% (50%) increase in the fundamental (third harmonic) output was observed. A significant improvement in the spectra with the elimination of sidebands was observed using a tapered undulator. The experiment is in good agreement with predictions using the MEDUSA simulation code.

Feeding dicyandiamide (DCD) to cattle: An effective method to reduce N2O emissions from urine patches in a heavy-textured soil under temperate climatic conditions.

Nitrate (NO3-) leaching and nitrous oxide (N2O) emission from urine patches in grazed pastures are key sources of water and air pollution, respectively. Broadcast spraying of the nitrification inhibitor dicyandiamide (DCD) has been shown to reduce these losses, but it is expensive. As an alternative, it had been demonstrated that feeding DCD to cattle (after manual mixing with supplementary feeds) was a practical, effective and cheaper method to deliver high DCD rates within urine patches. This two-year study carried out on simulated urine patches in three application seasons (spring, summer, autumn) explored the efficacy of DCD feeding to cattle to reduce N losses from grazed pasture soil in a heavy-textured soil under temperate climatic conditions. In each application season, DCD fed to cows, then excreted with urine and applied at a rate of 30kgDCDha-1 (treatment U+DCD30-f) was as effective as powdered DCD mixed with normal urine and applied at the same rate (treatment U+DCD30) at reducing cumulative N2O-N emissions and the N2O-N emission factor (EF3, expressed as % of N applied). Increasing DCD loading within urine patches from 10 to 30kgDCDha-1 improved efficacy by significantly reducing the EF3 from 34% to 64%, which highlights that under local conditions, 10kgDCDha-1 (the recommended rate for commercial use in New Zealand) was not the optimum DCD rate to curb N2O emissions. The modelling of EF3 in this study also suggests that N mitigation should be given more attention when soil moisture is going to be high, which can be predicted with short-term weather forecasting. DCD feeding, for instance in autumn when cows are not lactating and the risk of N losses is high, could then be reduced by focusing mainly on those forecasted wet periods.

Inverse relationship between systemic resistance of plants to microorganisms and to insect herbivory.

Pre-inoculation of plants with a pathogen that induces necrosis leads to the development of systemic acquired resistance (SAR) to subsequent pathogen attack [1]. The phenylpropanoid-derived compound salicylic acid (SA) is necessary for the full expression of both local resistance and SAR [2] [3]. A separate signaling pathway involving jasmonic acid (JA) is involved in systemic responses to wounding and insect herbivory [4] [5]. There is evidence both supporting and opposing the idea of cross-protection against microbial pathogens and insect herbivores [6] [7]. This is a controversial area because pharmacological experiments point to negative cross-talk between responses to systemic pathogens and responses to wounding [8] [9] [10], although this has not been demonstrated functionally in vivo. Here, we report that reducing phenylpropanoid biosynthesis by silencing the expression of phenylalanine ammonialyase (PAL) reduces SAR to tobacco mosaic virus (TMV), whereas overexpression of PAL enhances SAR. Tobacco plants with reduced SAR exhibited more effective grazing-induced systemic resistance to larvae of Heliothis virescens, but larval resistance was reduced in plants with elevated phenylpropanoid levels. Furthermore, genetic modification of components involved in phenylpropanoid synthesis revealed an inverse relationship between SA and JA levels. These results demonstrate phenylpropanoid-mediated cross-talk in vivo between microbially induced and herbivore-induced pathways of systemic resistance.

Nonlinear cross-phase modulation with intense single-cycle terahertz pulses.

We have demonstrated nonlinear cross-phase modulation in electro-optic crystals using intense, single-cycle terahertz (THz) radiation. Individual THz pulses, generated by coherent transition radiation emitted by subpicosecond electron bunches, have peak energies of up to 100 microJ per pulse. The time-dependent electric field of the intense THz pulses induces cross-phase modulation in electro-optic crystals through the Pockels effect, leading to spectral shifting, broadening, and modulation of copropagating laser pulses. The observed THz-induced cross-phase modulation agrees well with a time-dependent phase-shift model.

Amplification of ssb-1 mutant single-stranded DNA-binding protein in Escherichia coli.

The ssb-1 gene encoding a mutant Escherichia coli single-stranded DNA-binding protein has been cloned into plasmid pACYC184. The amount of overproduction of the cloned ssb-1 gene is dependent upon its orientation in the plasmid. In the less efficient orientation, 25-fold more mutant protein is produced than in strains carrying only one (chromosomal) copy of the gene; the other orientation results in more than 60-fold overproduction of this protein. Analysis of the effects of overproduction of the ssb-1 encoded protein has shown that most of the deficiencies associated with the ssb-1 mutation when present in single gene copy, including temperature-sensitive conditional lethality and deficiencies in amplified synthesis of RecA protein and ultraviolet light-promoted induction of prophage lambda +, are reversed by increased production of ssb-1 mutant protein. These results provide evidence in vivo that SSB protein plays an active role in recA-dependent processes. Homogenotization of a nearby genetic locus (uvrA) was identified in the cloning of the ssb-1 mutant gene. This observation has implications in the analysis of uvrA- mutant strains and will provide a means of transferring ssb- mutations from plasmids to the chromosome. On a broader scale, the observation may provide the basis of a general strategy to transfer mutations between plasmids and chromosomes.

The provision of physical activity to hospitalized elderly patients.

Physical activity has been recognized as an important aspect of patient care for nearly 50 years. Yet, deconditioning and functional decline of hospitalized elderly patients continue to be reported. Such outcomes suggest that a good system for providing activity in hospitals is lacking. In this retrospective study we assessed the provision of physical activity to 500 elderly patients (100 in each of five hospitals) during the first 7 days of hospitalization. No activity order was in effect on 13% of the 3500 patient days reviewed. When activity was ordered, patient activity was different from the activity permitted by the physician orders on 41% of the days. Patients who remained in bed or in a chair rarely received physical therapy, never had physician orders for exercises, and never performed exercises with the nurses. These findings demonstrate that the current practices for the provision of physical activity in hospitals are ineffective.

Estrogen receptors in the human prostate, seminal vesicle, epididymis, testis, and genital skin: a marker for estrogen-responsive tissues?

In an effort to identify those human male sex accessory tissues that may be under the physiological influence of estrogen, cytosolic and nuclear estrogen receptors were measured with two ligand systems that used either [3H]R2858 [moxesterol(11 beta-methoxy-17-ethynyl-1,3,5,(10)-estratriene-3,17 beta-diol)] or [3H]estradiol plus 1 microM dihydrotestosterone with diethylstilbestrol to correct for nonspecific binding. In seminal vesicles, high affinity binding was identified in cytosol (6 of 7 determinations) and nuclear extract (4 of 7 determinations); in the epididymis, high affinity binding was also present in the cytosol (10 of 12 determinations) and nuclear extract (10 of 11 determinations). In contrast, no high affinity binding was demonstrated in cytosol from the testis (0 of 5 determinations) or genital skin (0 of 7 determinations), and only low levels of nuclear receptor (80 fmol/g tissue) were present in the testis (3 of 5 determinations) and genital skin (1 of 7 determinations). In nonhyperplastic prostatic tissue, high affinity binding was present [in the cytosol of periurethral zone tissue (3 of 7 determinations) and nuclear extract (1 of 7 determinations), in cytosol of peripheral zone tissue (7 of 8 determinations) and nuclear extract (4 of 7 determinations), and in prostatic carcinoma cytosol (5 of 12 determinations) and nuclear extract (10 of 13 determinations)]. In contrast, no high affinity binding was present in either cytosol or nuclear extract from benign hyperplastic prostatic tissue. The finding of estrogen receptors in the human epididymis, seminal vesicle, and prostatic carcinoma suggests that estrogen, in addition to androgen, may act in the physiological regulation of these organs. However, the direct role of estrogen in the induction and maintenance of benign prostatic hyperplasia remains to be defined.

Role of tryptophan 54 in the binding of E. coli single-stranded DNA-binding protein to single-stranded polynucleotides.

Fluorescence and optical detection of triplet state magnetic resonance spectroscopy have been employed to study the complexes formed by single-stranded polynucleotides with both E. coli single-stranded DNA-binding protein and an E. coli ssb gene product in which Trp-54 is replaced by phenylalanine using site specific oligonucleotide mutagenesis. Our results strongly suggest the involvement of Trp-54 in stabilizing the protein-nucleic acid complexes via stacking interactions of the aromatic residue with the nucleotide bases.

Fournier gangrene associated with Crohn disease.

A 17-year-old boy presented with Fournier gangrene associated with previously undiagnosed Crohn ileocolitis. Fournier gangrene was managed by débridement, broad-spectrum antibiotics, and hyperbaric oxygen. A diverting ileostomy was performed before skin grafting and scrotal reconstruction. Microscopy of a full-layer surgical sample from the terminal ileum revealed granulomas with multinucleated histiocytes, consistent with Crohn disease. Crohn disease was treated with mesalamine, metronidazole, 6-mercaptopurine, and infliximab. The patient was discharged on hospital day 32. At 6-month follow-up, reconstruction of his scrotum had completely healed. Ostomy output was normal.

Cross-talk between the signal pathways for pathogen-induced systemic acquired resistance and grazing-induced insect resistance.

Reducing phenylpropanoid biosynthesis in transgenic tobacco compromises systemic acquired resistance (SAR) to tobacco mosaic virus, while increasing phenylpropanoid biosynthesis enhances SAR. Surprisingly, transgenic tobacco plants compromised in SAR exhibit more effective grazing-induced systemic resistance to larvae of Heliothis virescens, whereas induced insect resistance is compromised in transgenic plants with elevated phenylpropanoid levels. Levels of the phenylpropanoid-derived signal salicylic acid are directly correlated with overall phenylpropanoid biosynthesis in this series of transgenic plants. Moreover, while pathogen-induced SAR is almost completely compromised in salicylic acid-deficient plants expressing the bacterial nahG salicylate hydroxylase gene, these plants show enhanced grazing-induced insect resistance compared to wild-type. Hence, suppression of grazing-induced insect resistance is mediated at least in part by salicylic acid and likely reflects salicylic acid inhibition of the synthesis and action of the wound signal jasmonic acid. We propose that the dual functions of salicylic acid contribute to a signal poise which constrains constitutive expression of disease and insect resistance mechanisms, and reciprocally switches their selective activation.

Lack of an association between insulin-like growth factor-I and body composition, muscle strength, physical performance or self-reported mobility among older persons with functional limitations.

OBJECTIVE: The hypothesis that decreased growth hormone (GH) secretion contributes to the functional decline that occurs with aging is far from substantiated. There have been few studies addressing the distribution and correlates of IGF-I, an indicator of GH activity, in nonclinical populations. As part of a growth hormone intervention trial, we examined the cross-sectional relations between IGF-I levels and multiple measures of physical function, body composition, and strength in a group of older men and women exhibiting mild to moderate reductions in measured physical performance. METHODS: Using a variety of advertising techniques, 155 older subjects were recruited from a metropolitan area to participate in a growth hormone and exercise intervention study. At baseline, all subjects had blood drawn for IGF-I and underwent testing of body composition using dual X-ray absorptiometry, muscle strength using isokinetic dynamometry, and functional assessment using timed performance measures and self-report. Associations between levels of IGF-I, body composition, strength, and physical function were assessed after dividing men and women separately into tertiles of IGF-I as well as treating IGF-I as a continuous variable. RESULTS: Men had higher IGF-I levels than women, and a significant inverse correlation was observed between age and IGF-I in men (r=-0.29, P=.009). There were no clear trends for associations between tertiles of IGF-I, and any of the variables tested. Linear regression models with IGF-I treated as a continuous measure were not associated significantly with any of the measures of physical function, body composition, or strength (all P > 0.05). CONCLUSIONS: In conclusion, although IGF-I levels declined with age in men, these data did not demonstrate an association between IGF-I and measures of muscle strength, body composition, or physical functioning. These findings support the growing body of evidence that IGF-I levels may not be an indicator of growth hormone activity in older persons.

Unsuspected intraperitoneal perforation of the urinary bladder as an iatrogenic disorder.

Perforation of the urinary bladder associated with long-term indwelling catheter drainage is a rare and lethal iatrogenic disorder. Moreover, bladder perforation can occur in a variety of surgical settings. We report here several unusual situations: one in which a fibroid uterus probably played a role in pressure necrosis of a bladder with an indwelling catheter, one in which carcinoma of the prostate and faulty catheter drainage was present, and one in which pelvic radiation therapy was followed by bladder perforation. These three cases illustrate the clinical acumen required to recognize intraperitoneal perforation. The variety of presentations is suggested by the fact that one case was diagnosed preoperatively by cystogram, one was unexpectedly found at laparotomy for acute peritonitis, and one was discovered only at autopsy. One of the patients was diabetic, two had been treated for miliary tuberculosis, and all had a history of long-term urinary bladder catheterization. Bladder perforation can be prevented by several alternative methods of chronic bladder drainage. The diagnosis of the problem requires a high degree of clinical suspicion, aided by definitive cystograms. The treatment is surgical, including prompt repair of the perforation and drainage of the bladder.

Retrograde method for percutaneous access to kidney.

A technique is described for gaining percutaneous access to the kidney by puncturing from inside out using a retrograde catheter and a sharpened stainless steel stylet. The method allows precise placement of a percutaneous tract in the nondilated upper urinary tract.

Use of magnetic resonance imaging scanning in adrenocortical carcinoma with vena caval involvement.

We report on 2 cases of an adrenocortical carcinoma with vena caval involvement. Preoperative evaluation included a magnetic resonance imaging (MRI) scan confirming the presence of vena caval involvement. Extremely precise detail of the vena caval tumor thrombus was very helpful in preparing for the surgical extirpation. MRI detail far outweighed what was seen on the computed tomography scan and venacavogram. The MRI scan correlated exactly with what was found surgically. Although MRI scanning has been used to evaluate renal tumors with vena caval extension, few cases have been reported with similar adrenal tumors.

Abnormalities of ejaculation.

The normal physiologic processes of emission and ejaculation require coordination of neurophysiologic, anatomic, and, in certain cases, psychological phenomena. Disruption of any component, from the embryologic development of the müllerian duct through the medications used for nonrelated systemic disease, can alter the efficient function of ejaculation. Evaluation of the urologic patient who has any of a number of abnormal ejaculatory states requires an understanding of the many possible mechanisms of failure. The majority of these men need evaluation because of a possible male-factor infertile marriage. The potential for improvement is significant, given the development of improved techniques to stimulate ejaculation and the promise shown by extracorporeal fertilization techniques such as in vitro fertilization and gamete intrafallopian tube transfer. These patients deserve complete assessment and optimization of any factors that will enable them to achieve their goal of procreation.

The management of drug induced gingival hyperplasia in mentally retarded patients with hemophilia: a report of two cases.

Two cases of hemophilia in severely mentally retarded patients with drug-induced gingival hyperplasia are presented. The method of management in each case is described. A conservative approach is recommended in which tissue removals and only selected extractions are performed. It is also suggested that the sequela of dilantin hyperplasia be considered when dilantin is used in patients with hemophilia or severely mentally retarded patients whose oral hygiene may be difficult to maintain. If feasible, as in the first case reported, discontinuance of the drug should be considered. In case 2 the patient is presently being weaned from dilantin therapy. It should be understood that the authors are concerned with the immediate clinical management of drug-induced gingival hyperplasia in mentally-retarded patients with hemophilia. Although this method of management has proved successful in the hands of the authors, we do not have data to show that it is the best form of treatment for these patients.

Primary Kaposi's sarcoma of an intraparotid lymph node with AIDS.

A case of Kaposi's sarcoma of an intraparotid lymph node in a patient with previously undiagnosed AIDS is presented. In patients at risk for AIDS who present with undiagnosed head and neck tumors, the diagnosis of epidemic Kaposi's sarcoma should be considered. Although transmission of AIDS to health care workers is exceedingly rare, proper precautions should be exercised when working with these patients.

The mutagenicity of electrocautery smoke.

Careful analysis of electrocautery smoke produced during breast surgery has found organic compounds that are unidentifiable with current analytical techniques. The purpose of this study was to determine the potential mutagenicity of the smoke produced by the electrocautery knife during reduction mammaplasty. Multiple air samples were collected in the operating room during two reduction mammaplasty procedures. Airborne smoke particles were tested for mutagenic potential in both tester strains of Salmonella typhimurium (TA98 and TA100) using the standard Salmonella microsomal test (Ames test). All testing was performed by the Hazard Evaluations and Technical Assistance Branch of the National Institute of Occupational Safety and Health. The smoke produced with the electrocautery knife during reduction mammaplasty was found to be mutagenic to the TA98 strain. The Ames test, an established technique for evaluating the mutagenicity of a substance, was convincingly positive for the smoke collected during the breast surgery. Whether the smoke represents a serious health risk to operating room personnel is not known. Development of techniques to limit electrocautery smoke exposure in the operating room appears to be needed, and surgeons should attempt to minimize their exposure.

Salvage of jeopardized total-knee prosthesis: the role of the gastrocnemius muscle flap.

Total-knee arthroplasty has provided many patients with excellent long-term functional results. However, exposure of a total-knee replacement usually eventuates in failure. The relatively superficial location of the prosthesis, the need for early active motion, previous surgical incisions, and a variety of systemic factors may militate against early wound healing. Restoration of well-vascularized soft-tissue cover can salvage an otherwise disastrous situation. The authors recommend early operative intervention upon observation of wound breakdown, devitalized skin edges, or significant subcutaneous infection leading to necrotic overlying skin. The operative procedure found to salvage the majority of prostheses consists of adequate debridement, antibiotic irrigation (of the joint, if exposed), and coverage with a well-vascularized muscle flap, preferably the medial gastrocnemius muscle. The operative technique and ultimate long-term outcome are reviewed based on experience with 10 consecutive patients presenting with a jeopardized knee prosthesis. Follow-up ranged from 1 to 6 years. Representative case histories are presented.

A 6-year experience with immediate reconstruction after mastectomy for cancer.

A 6-year retrospective review is presented of 185 patients who underwent immediate reconstruction of the breast at the same operation as mastectomy for carcinoma. The patients were treated at two institutions under similar protocols of patient selection, surgical technique, and postoperative care. A detailed evaluation is presented from both the oncologic and surgical points of view. The data support the conclusion that immediate reconstruction of the breast does not alter survival or cancer recurrence rates and does not interfere with the treatment of primary or secondary disease. A low incidence of significant surgical complications is also detailed. Combined with previous reports answering psychological concerns about this mode and timing of reconstruction, this review offers significant reassurance about the overall safety of immediate reconstruction. The authors therefore recommend immediate reconstruction of the breast as a safe treatment option for the woman facing mastectomy.