Lon degrades stable substrates slowly but with enhanced processivity, redefining the attributes of a successful AAA+ protease

Lon is a widely distributed AAA+ (ATPases associated with diverse cellular activities) protease known for degrading poorly folded and damaged proteins and is often classified as a weak protein unfoldase. Here, using a Lon-degron pair from Mesoplasma florum (MfLon and MfssrA, respectively), we perform ensemble and single-molecule experiments to elucidate the molecular mechanisms underpinning MfLon function. Notably, we find that MfLon unfolds and degrades stably folded substrates and that translocation of these unfolded polypeptides occurs with a ∼6-amino-acid step size. Moreover, the time required to hydrolyze one ATP corresponds to the dwell time between steps, indicating that one step occurs per ATP-hydrolysis-fueled "power stroke." Comparison of MfLon to related AAA+ enzymes now provides strong evidence that HCLR-clade enzymes function using a shared power-stroke mechanism and, surprisingly, that MfLon is more processive than ClpXP and ClpAP. We propose that ample unfoldase strength and substantial processivity are features that contribute to the Lon family's evolutionary success.

Molecular origins of reduced activity and binding commitment of processive cellulases and associated carbohydrate-binding proteins to cellulose III

Efficient enzymatic saccharification of cellulosic biomass into fermentable sugars can enable production of bioproducts like ethanol. Native crystalline cellulose, or cellulose I, is inefficiently processed via enzymatic hydrolysis but can be converted into the structurally distinct cellulose III allomorph that is processed via cellulase cocktails derived from Trichoderma reesei up to 20-fold faster. However, characterization of individual cellulases from T. reesei, like the processive exocellulase Cel7A, shows reduced binding and activity at low enzyme loadings toward cellulose III. To clarify this discrepancy, we monitored the single-molecule initial binding commitment and subsequent processive motility of Cel7A enzymes and associated carbohydrate-binding modules (CBMs) on cellulose using optical tweezers force spectroscopy. We confirmed a 48% lower initial binding commitment and 32% slower processive motility of Cel7A on cellulose III, which we hypothesized derives from reduced binding affinity of the Cel7A binding domain CBM1. Classical CBM–cellulose pull-down assays, depending on the adsorption model fitted, predicted between 1.2- and 7-fold reduction in CBM1 binding affinity for cellulose III. Force spectroscopy measurements of CBM1–cellulose interactions, along with molecular dynamics simulations, indicated that previous interpretations of classical binding assay results using multisite adsorption models may have complicated analysis, and instead suggest simpler single-site models should be used. These findings were corroborated by binding analysis of other type-A CBMs (CBM2a, CBM3a, CBM5, CBM10, and CBM64) on both cellulose allomorphs. Finally, we discuss how complementary analytical tools are critical to gain insight into the complex mechanisms of insoluble polysaccharides hydrolysis by cellulolytic enzymes and associated carbohydrate-binding proteins.

Switching and Torque Generation in Swarming E. coli

Escherichia coli swarm on semi-solid surfaces with the aid of flagella. It has been hypothesized that swarmer cells overcome the increased viscous drag near surfaces by developing higher flagellar thrust and by promoting surface wetness with the aid of a flagellar switch. The switch enables reversals between clockwise (CW) and counterclockwise (CCW) directions of rotation of the flagellar motor. Here, we measured the behavior of flagellar motors in swarmer cells. Results indicated that although the torque was similar to that in planktonic cells, the tendency to rotate CCW was higher in swarmer cells. This suggested that swarmers likely have a smaller pool of phosphorylated CheY. Results further indicated that the upregulation of the flagellin gene was not critical for flagellar thrust or swarming. Consistent with earlier reports, moisture added to the swarm surface restored swarming in a CCW-only mutant, but not in a FliG mutant that rotated motors CW-only (FliG^CW). Fluorescence assays revealed that FliG^CW cells grown on agar surfaces carried fewer flagella than planktonic FliG^CW cells. The surface-dependent reduction in flagella correlated with a reduction in the number of putative flagellar preassemblies. These results hint toward a possibility that the conformational dynamics of switch proteins play a role in the proper assembly of flagellar complexes and flagellar export, thereby aiding bacterial swarming.

Use of electron microscopy in core biopsy diagnosis of oncocytic renal tumors

The distinction between oncocytoma and chromophobe renal cell carcinoma, important clinically, may be challenging, especially as the tissue sample size decreases. Ancillary studies can be helpful, although subject to interpretation and sample variability. The aim of this study was to examine the value of electron microscopy in differentiating between oncocytoma and chromophobe renal cell carcinoma on formalin fixed paraffin embedded needle core biopsies. Twenty renal needle core biopsies were evaluated. Despite formalin fixation and paraffin embedding, the classic ultrastructural features of these neoplasms were retained, revealing 80% sensitivity and 100% specificity by initial work-up.

Bordetella bronchiseptica pneumonia in a kidney-pancreas transplant patient after exposure to recently vaccinated dogs

Bordetella bronchiseptica is an uncommon cause of respiratory infection in humans generally occurring in immunocompromised individuals exposed to infected animals. A 61-year-old female underwent a kidney-pancreas transplant 7 years before presentation. Postoperative immunosuppression was achieved with sirolimus and mycophenolate mofetil. The patient was doing well until she developed a small bowel obstruction secondary to adhesions. She underwent surgical adhesiolysis without complications. Two weeks postoperatively the patient developed pneumonia. She failed to respond to repeated courses of antibiotics, and thus, diagnostic bronchoscopy with bronchoalveolar lavage (BAL) was performed. BAL cultures grew B. bronchiseptica. Further investigation revealed that the patient's dogs had recently received a live-attenuated B. bronchiseptica intranasal vaccination. The patient recovered after 21 days of therapy with doxycycline based upon in vitro susceptibility testing. B. bronchiseptica is an uncommon but recognized human pathogen. It most commonly affects immunocompromised individuals. Here, we report a culture-proven case of B. bronchiseptica pneumonia in an immunocompromised host residing in a household with her dogs who had recently received live-attenuated, intranasal B. bronchiseptica vaccinations. As polymerase chain reaction testing was not performed comparing the isolated strain to the vaccination strain, the association is presumptive. This report expands the spectrum of immunocompromised hosts to include renal-pancreas transplant patients who have developed infection from B. bronchiseptica, while illustrating the risks associated with animal contacts and attenuated vaccines in the immunosuppressed population.

Atypical and columnar cell lesions in breast needle biopsies for indeterminate microcalcifications: predictors of higher risk findings requiring surgical excision

Abstract #3004

Background: Columnar cell lesions (CCL) are frequently identified in biopsies performed for calcifications. The primary objective of this study is to identify histologic features of CCL in directional vacuum-assisted needle biopsies (DVAB) that could predict a higher risk lesion requiring excision.
 Design: From June 2002 to January 2008, we retrieved the materials for 88 DVABs and their subsequent segmental resections. We excluded carcinomas, intraductal papillomas, fibroadenomas, adenosis, or radial scars. Using World Health Organization criteria, CCLs were classified as CCL with no atypia (CCL-NA), CCL with cytologic atypia (CCL-CA; flat epithelial atypia), or architectural atypia/atypical ductal hyperplasia (CCL-ADH) in the background of CCL. In cases with atypia, the involved terminal duct lobular units/ducts (TDLUs) were quantified. Atypical cases were separated two groups as follows: minimal ADH (≤2 TDLU and minimal cytologic atypia) and extensive ADH/borderline DCIS (≥3 TDLU and/or significant cytologic atypia bordering on DCIS).Radiographs were evaluated to assess amount of calcifications removed. Biopsy results were correlated with the subsequent surgical excision results.
 Results: Eight of 88 biopsies were excluded because of overdiagnosis or because the lesions were not associated with microcalcifications. The remaining 80 biopsies included 5 cases of CCL-NA, 4 pure CCL-CA, 20 mixed CCL-CA + ADH and 51 pure CCL-ADH. Microcalcifications were identified in association with the targeted lesions. There were no higher risk findings in any of the resection specimens with CCL-NA and pure CCL-CA. Ten of the atypical lesions showed carcinoma on excision (9 DCIS and 1 invasive cancer). Twenty-five percent (9/36) extensive ADH/borderline DCIS showed carcinoma on excision. In contrast, only 2.5% (1/39) of minimal ADH cases showed carcinoma on excision. Radiologic review revealed residual abnormality in this one case.
 Conclusion: In summary, the extent of lobular involvement by atypia (CCL-CA or CCL-ADH) correlated with the presence or absence of higher risk lesions upon subsequent excision. These results suggest that additional surgery may not be necessary for CCL-CA or CCL-ADH that is limited to ≤ 2 foci provided sampling of the microcalcifications is adequate.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3004.

High-dose chemotherapy with autologous stem-cell support versus standard-dose chemotherapy: meta-analysis of individual patient data from 6 randomized metastatic breast cancer trials

Abstract #6113

Background: The role of high-dose chemotherapy (HDC) with autologous hematopoietic stem-cell transplantation for metastatic breast cancer has not been well defined. The statistical power of the available trials has limited precision for determining whether HDC has any benefit for this indication, or for any subset of patients.
 Methods: Individual patient data from the 6 known randomized trials were merged into a single database. The primary endpoint was overall survival (OS): time from randomization to death. The secondary endpoint was progression-free survival (PFS). Cox proportional hazards regression compared the effect of HDC vs standard-dose chemotherapy (SDC) on PFS and OS adjusted for age, trial and hormone receptor (HmR) status (positive if either estrogen (ER) or progesterone (PgR) receptor positive), and other variables. Among the subset analyses considered were by age, HmR status, number metastatic sites, and soft tissue metastases.
 Results: A total of 846 patients (433 HDC, 413 SDC) had median follow-up of 1.9 years. Median age was 47 years (range 23 to 65). Preliminary analyses show that after adjusting for age and trial, HDC significantly prolonged OS (hazard ratio (HR) 0.86; 95%CI 0.73-1.00; p=0.05) and PFS (HR 0.73; 95%CI 0.63-0.84; p<0.0001). Mean improvement (out to 8 yrs) was 4 months for both OS and PFS. Both age (p=0.023) and soft tissue disease (p=0.0025) had statistically significant interactions with treatment for OS, but neither remain significant after adjusting for multiple comparisons.
 Conclusions: HDC may have a modest benefit on OS that may be greater in patients younger than 50 years. However, we were not able to draw firm conclusions about age or other subset analyses.
 


Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6113.

Regulation of iNOS by the p44/42 mitogen-activated protein kinase pathway in human melanoma

Activating mutations of the genes for NRAS and BRAF, components of the p44/42 mitogen-activated protein kinase (MAPK) pathway, are common findings in melanoma. Recent evidence in several nonmelanoma cell systems supports the regulation of the inducible nitric oxide synthase (iNOS) gene by this pathway. On the basis of our data showing that melanoma iNOS expression predicts shortened patient survival, we formulated the hypothesis that activating mutations of NRAS or BRAF, which lead to constitutive activation of the p44/42 MAPK pathway, drive iNOS expression in human melanoma. In the present study, we have shown that inhibition of melanoma iNOS activity by S-methylisothiourea leads to decreased cell proliferation, confirming the importance of iNOS activity for melanoma cell growth. Regulation of melanoma iNOS expression by the p44/42 MAPK pathway was demonstrated by inhibition of the pathway by U0126, and by BRAF RNA interference. To explore this regulatory pathway in human tissue, 20 melanoma tumors were examined for NRAS and BRAF mutations, immunohistochemical evidence of ERK phosphorylation, and iNOS expression. A significant association was found among these three features. We conclude that in human melanoma, activating mutations of NRAS and BRAF drive constitutive iNOS expression and, implicitly, nitric oxide production, contributing to the poor survival of these patients.

Development of a Standardized Susceptibility Test forCampylobacterwith Quality-Control Ranges for Ciprofloxacin, Doxycycline, Erythromycin, Gentamicin, and Meropenem

A standardized agar dilution susceptibility testing method was developed for Campylobacter that consisted of testing on Mueller-Hinton medium supplemented with 5% defibrinated sheep blood in an atmosphere of 10% CO2, 5% O2, and 85% N2. Campylobacter jejuni ATCC 33560 was identified as a quality-control (QC) strain. Minimal inhibitory concentration (MIC) QC ranges were determined for two incubation time/temperature combinations: 36 degrees C for 48 hr and 42 degrees C for 24 hr. Quality-control ranges were determined for ciprofloxacin, doxycycline, erythromycin, gentamicin, and meropenem. For all antimicrobial agents tested at both temperatures, 95-100% of the QC MIC results fell within recommended QC ranges. Twenty-one Campylobacter clinical isolates, encompassing five species of Campylobacter (C. jejuni, C. coli, C. jejuni, subsp. doylei, C. fetus, and C. lari) were tested in conjunction with the C. jejuni QC strain. While C. jejuni and C. coli could be reliably tested under both test conditions, growth of C. jejuni subsp. doylei, C. fetus, and C. lari isolates was inconsistent when incubated at 42 degrees C. Therefore, it is recommended that these species only be tested at 36 degrees C.

Activity of faropenem and imipenem for ciprofloxacin-resistant bacteria

AIM

To determine whether an association exists between ciprofloxacin and faropenem resistance in bacteria including multiply drug-resistant isolates.

METHODS

The MICs were determined for 150 fluoroquinolone-resistant bacteria, plus 20 nalidixic acid-resistant strains of Salmonella enterica serovar Typhimurium.

RESULTS

Faropenem was very active against Escherichia coli and Streptococcus pneumoniae, but 5/31 Staphylococcus aureus and 2/26 Bacteroides fragilis required > or =16 mg/L for inhibition. Of 30 multiply drug-resistant isolates with a phenotype suggestive of enhanced efflux, only for one strain (a Bacteroides fragilis) was the faropenem MIC higher than that associated with the other isolates of the same species.

CONCLUSIONS

Faropenem was in general as active as imipenem. There was no association between resistance to ciprofloxacin and faropenem or imipenem resistance.

Accumulation of 10 fluoroquinolones by wild-type or efflux mutant Streptococcus pneumoniae

A method for measuring fluoroquinolone accumulation by Streptococcus pneumoniae was rigorously examined. The accumulation of ciprofloxacin, clinafloxacin, gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin, norfloxacin, ofloxacin, sitafloxacin, and trovafloxacin in the presence and absence of either carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) or reserpine was determined for two wild-type fluoroquinolone-susceptible capsulated S. pneumoniae strains (M3 and M4) and the noncapsulated strain R6. Two efflux mutants, R6N (which overexpresses PmrA) and a mutant of M4, M22 (no expression of PmrA), were also examined. Essentially, the fluoroquinolones fell into two groups. (i) One group consisting of ciprofloxacin, grepafloxacin, and norfloxacin accumulated to 72 to 92 ng/mg (dry weight) of cells in all strains. (ii) The remainder of the agents accumulated to 3 to 30 ng/mg (dry weight) of cells. With a decrease in hydrophobicity, there was a decrease in the concentration accumulated. With an increase in the molecular weight of the free form of each agent, there was also a decrease in the concentration accumulated. The strains differed in their responses to reserpine and CCCP. For the three fluoroquinolone-susceptible strains, only reserpine had a significant effect upon accumulation of moxifloxacin and clinafloxacin by M3 and showed no effect for the other agents and strains. For M3 and M4, CCCP enhanced the concentration of ciprofloxacin and norfloxacin accumulated, whereas for R6, the effect was only statistically significant for ofloxacin. Efflux mutant M22 accumulated less ciprofloxacin, gatifloxacin, and ofloxacin than M4 did. M22 accumulated more norfloxacin than M4 did. Reserpine and CCCP had variable effects as for the other strains. Differences in the accumulation of fluoroquinolones by R6 and R6N were highly dependent upon growth phase, and only for norfloxacin was there a significant difference between two strains.

An optimized system for studies of EPO-dependent murine pro-erythroblast development

OBJECTIVE

Objectives were to develop new means to isolate useful numbers of primary progenitor cells and to quantitatively assay the stepwise maturation of erythroblasts.

METHODS

Approaches involved dosing mice with thiamphenicol (TAP) to yield staged cohorts of pro-erythroid cells; optimizing conditions for their EPO-dependent in vitro growth and survival; developing assays for CFU-E maturation; analyzing stage-specific transcript expression; and expressing a heterologous, erythroid-specific tag (EE372) in transgenic mice.

RESULTS

Per TAP-treated mouse, 3 x 10(7) highly EPO-responsive erythroid progenitor cells were generated that represented up to 30% of total splenocytes and showed strict dependence on EPO for survival, growth, and immediate response gene expression. In this developing cohort, a tightly programmed sequence of gene expression was observed, and maximal expression of c-kit, EPO receptor, and beta-globin transcripts occurred at 72, 96, and 120 hours post-TAP withdrawal, respectively. Also, the newly discovered erythroid-specific dual-specificity kinase, DYRK3, was revealed to be expressed at a late CFU-E stage. In vitro, these progenitor cells matured stepwise from high FALS Ter119- cells (24-hour culture) to high FALS Ter119+ cells (24-36 hours) to low FALS Ter119+ maturing erythroblasts (40-48 hours) and sharp differences in their morphologies were observed. Finally, a MACS-based procedure for the purification of erythroid progenitor cells from TAP-treated EE372 transgenic mice also was developed.

CONCLUSIONS

A comprehensive new system for isolating large numbers of primary murine erythroid progenitor cells and quantitatively monitoring their development is established that should serve well in investigations of endogenous and pharmacological regulators of red blood cell development.

Urban-rural differences in a memory disorders clinical population

OBJECTIVES

To compare patient characteristics and family perceptions of patient function at one urban and one rural memory disorders clinic.

DESIGN

Secondary, cross-sectional data analyses of an extant clinical database.

SETTING/PARTICIPANTS

First time visits (n = 956) at two memory disorders clinics.

MEASUREMENTS

Patient and family-member demographics and assessment results for the Mini-Mental State Examination (MMSE), instrumental activities of daily living (IADLs), activities of daily living (ADLs), the Memory Change and Personality Change components of the Blessed Dementia Rating Scale, and the Revised Memory and Behavior Problems Checklist.

RESULTS

In both clinics, patients and family members were more likely female. The typical urban clinic patient was significantly more likely to be living in a facility and more educated than the typical rural patient. Urban and rural patients did not show significant differences in age- and education-adjusted MMSE scores or raw ADL/IADL ratings, but the urban family members reported more memory problems, twice as many personality changes, more-frequent behavior problems, and more adverse reactions to problems.

CONCLUSION

Physicians who practice in both urban and rural areas can anticipate differences between patients, and their families, who seek a diagnosis of memory disorders. Our most important finding is that despite similarities in reported functional abilities, urban families appear to be more sensitive to and more distressed by patients' cognitive and behavioral symptoms than rural families. These differences may reflect different underlying needs, and should be explored in further research.

Effective antigen-specific immunotherapy in the marmoset model of multiple sclerosis

Mature T cells initially respond to Ag by activation and expansion, but high and repeated doses of Ag cause programmed cell death and can suppress T cell-mediated diseases in rodents. We evaluated repeated systemic Ag administration in a marmoset model of experimental allergic encephalomyelitis that closely resembles the human disease multiple sclerosis. We found that treatment with MP4, a chimeric, recombinant polypeptide containing human myelin basic protein and human proteolipid protein epitopes, prevented clinical symptoms and did not exacerbate disease. CNS lesions were also reduced as assessed in vivo by magnetic resonance imaging. Thus, specific Ag-directed therapy can be effective and nontoxic in primates.

Diversity in medical school: perceptions of first-year students at four southeastern U.S. medical schools

PURPOSE

To assess students' perceptions of the extent of diversity in their classes, the role of diversity in their first-year curriculum, and their predictions of the amount of diversity in their future patient populations.

METHOD

In 1998, students at four southeastern U.S. medical schools that had distinct demographics and differing institutional missions completed a questionnaire on diversity at the end of the first year. In the instrument, diversity was defined according to nine population characteristics: age, sex, race, ethnic background, physical disability, religious affiliation, sexual orientation, socioeconomic status, and rural background (growing up in a community of less than 5,000). Responses were compared according to students' institution, sex, and race.

RESULTS

Questionnaires were returned by 349 of 474 students (74%). Students at the school with the most diverse first-year class placed the greatest value on the contributions of diversity to the learning environment. Women students placed more value on the inclusion of diversity issues in the curriculum than did men students, and they placed greater value on understanding diversity issues in their future medical practices than did men. Compared with Asian American, Hispanic, and white students, African American students were the least likely to think that the curriculum contained adequate information about diversity.

CONCLUSIONS

The results indicate that perceptions of diversity were influenced by the students' own demographic characteristics and those of their medical school. The more diverse the class, the more comfortable the students were with diversity and the more they valued its contribution to their medical education.

Physicians and clergy as facilitators of formal services for older adults

Researchers have sought to understand the determinants of the use of in-home and community-based services in order to better serve the needs of older adults. One component frequently included in formal service utilization models is the role of individuals who exert an influence on the service use process. An analysis of in-depth interviews conducted with 115 older adults revealed the important facilitating role that physicians and religious leaders play in encouraging the use of these services. The sample, which included African-American and white adults age 65+ from rural and urban environments, described various ways in which these "facilitators" influence the use of formal services. These ways include: (1) supplying instrumental support either by "ordering" a particular program for or linking the elder with the program and (2) providing informational and affective support, including advising or recommending the use of a program, conveying necessary background on formal services, and legitimizing the use of formal services. Regardless of personal characteristics (such as ethnicity and residence), a majority of elders in the sample recognized the important role played by physicians, and clergy. The acknowledgement of the role played by these facilitators should be viewed as an opportunity for physicians and clergy to enhance the knowledge and appropriate use of needed formal services for elders. In addition, these findings have policy implications for the current provision of aging services.

Artifacts and the visualization of fetal distal extremities using three-dimensional ultrasound

OBJECTIVES

To demonstrate that acoustic shadowing in 3D US may give rise to artifacts simulating limb defects and provide a solution to eliminate its occurrence.

METHODS

Twenty second trimester fetuses (gestational age 15-24 weeks) were scanned with three-dimensional ultrasound (3D US) using a sagittal acquisition plane. Fetal tibia/fibula and radius/ulna pairs were assessed for completeness of imaging. A further 20 fetuses (gestational age 20-26 weeks) were scanned in both axial and sagittal planes and the results compared to verify clear visualization of both bones.

RESULTS

Shadowing from adjacent structures produced an apparent limb defect in 55% of the first 20 fetuses imaged only sagittally (18% of limb pairs). Acquiring data from more than one orientation avoided this artifact.

CONCLUSIONS

The 3D US is subject to the same artifacts as two-dimensional (2D US) in terms of acoustic shadowing, although their presentation may be different. Awareness of this fact is essential for correct interpretation of 3D US studies. Three-dimensional scanning protocols should be modified to ensure that fetal structures are adequately visualized by acquiring volume data in more than one acquisition orientation.

Effect of external dead volume on performance while wearing a respirator

Respirator dead volume accumulates exhaled carbon dioxide and returns it to the respiratory system during subsequent inhalations. Because inhaled carbon dioxide is known to be a powerful respiratory stimulant and psychoactive gas, respirator dead volume would be expected to influence performance times while respirators are worn during work. This experiment was performed at intense levels of treadmill walking (80-85% VO2max) to demonstrate maximum sensitivity to respiratory stress. Six dead volume conditions (representing a range of 280 to 1,160 mL) were imposed on the subjects. Results show linear decreases in performance times and breathing apparatus comfort with increasing dead volumes. For each 350 mL of external dead volume, a 19% decrease of performance time and an 18% decrease in breathing apparatus comfort can be expected.

Addition of eicosapentaenoic acid to gamma-linolenic acid-supplemented diets prevents serum arachidonic acid accumulation in humans

Previous studies reveal that supplementation of human diets with gamma-linolenic acid (GLA) reduces the generation of lipid mediators of inflammation and attenuates clinical symptoms of chronic inflammatory disorders such as rheumatoid arthritis. However, we have shown that supplementation with this same fatty acid also causes a marked increase in serum arachidonate (AA) levels, a potentially harmful side effect. The objective of this study was to design a supplementation strategy that maintained the capacity of GLA to reduce lipid mediators without causing elevations in serum AA levels. Initial in vitro studies utilizing HEP-G2 liver cells revealed that addition of eicosapentaenoic acid (EPA) blocked Delta-5-desaturase activity, the terminal enzymatic step in AA synthesis. To test the in vivo effects of a GLA and EPA combination in humans, adult volunteers consuming controlled diets supplemented these diets with 3.0 g/d of GLA and EPA. This supplementation strategy significantly increased serum levels of EPA, but did not increase AA levels. EPA and the elongation product of GLA, dihomo-gamma-linolenic acid (DGLA) levels in neutrophil glycerolipids increased significantly during the 3-wk supplementation period. Neutrophils isolated from volunteers fed diets supplemented with GLA and EPA released similar quantities of AA, but synthesized significantly lower quantities of leukotrienes compared with their neutrophils before supplementation. This study revealed that a GLA and EPA supplement combination may be utilized to reduce the synthesis of proinflammatory AA metabolites, and importantly, not induce potentially harmful increases in serum AA levels.

Acquired thermotolerance and expression of the HSP100/ClpB genes of lima bean

Acquired thermotolerance (AT) is the ability of cells to survive a normally lethal temperature treatment as a consequence of pretreatment at an elevated but sublethal temperature. In yeast and cyanobacteria, the expression of the HSP100/ClpB protein is required for the AT response. To determine whether the HSP100/ClpB protein is associated with this response in lima bean (Phaseolus lunatus), we have cloned an HSP100/ClpB homolog and assessed expression of the two gene copies under heat stress conditions, which induce AT. Transcription of the cytoplasmically localized HSP100/ClpB protein genes is stringently controlled by heat stress in both of the laboratory and field heat stress conditions. From a heat-induced cDNA library, we identified a clone of a putative chloroplast-targeted (cp) HSP100/ClpB protein gene sequence. The cp HSP100/ClpB protein genes are constitutively expressed, but transcript levels increase post-heat stress in laboratory heat stress experiments. In field conditions the genes for the cp HSP100/ClpB are constitutively expressed. Although we were unable to correlate differences in the timing of AT response with the expression or genetic structure of the HSP100/ClpB genes in heat-tolerant or -sensitive varieties of lima bean, we clearly demonstrate the association of expression of HSP100/ClpB proteins with heat response in this species.

Purchasing over-the-counter medications: the influence of age and familiarity

This study examines the influence of age and type of over-the-counter (OTC) medications on decision-making processes leading to the selection of OTC medications. Manipulating type of OTC medication served as a way of examining subjects' familiarity with the decision domain. Thirty-six younger and thirty-six older adults answered questions regarding their OTC medication purchases, and completed a decision task in which they searched four computerized displays of product label information in order to select an antacid, a cold medication, a laxative, and a pain reliever. In general, older adults were slower to review information, more likely to have used OTC medications, and more organized in their searches for information. Specific to pair relievers, older and younger adults demonstrated similar information use and time to decision, and older adults specifically tailored the organization of their information searches when choosing pain relievers. Clearly, older adults selectively use product information on OTC medication packages, given adequate time to process information. Manufacturers' efforts directed at improving information availability should benefit older adults' decision processes.

Communication using a telephone while wearing a respirator

Respirators have been found to degrade communication effectiveness when wearers speak face-to-face. However, little is known about communication effectiveness when using the telephone and wearing a respirator. Eleven pairs of subjects were asked to pronounce and identify words chosen from Modified Rhyme Test lists. Each word appeared on a computer screen in one room and the speaker said the word into the telephone. The listener in another room identified the word and typed it into a computer linked with the first. Subjects wore U.S. Army M40 full-facepiece air-purifying respirators with hoods. Three different speech diaphragm arrangements and two hood materials were tested. Results show that accuracy suffered by about 10% when respirators and hoods were worn compared with the control condition. Word identification speed was one-third to one-half of the control (no respirator or hood) condition depending on specific equipment worn.

Venous air embolism from central venous catheterization: a need for increased physician awareness

OBJECTIVES

To report a series of patients with clinically diagnosed venous air embolism (VAE) and major sequelae as a complication of the use of central venous catheters (CVCs), to survey health care professionals' practices regarding CVCs, and to implement an educational intervention for optimizing approaches to CVC insertion and removal.

SETTING

Tertiary care, university-based 806-bed medical center.

INTERVENTIONS

We surveyed 140 physicians and 53 critical care nurses to appraise their awareness of the proper management and complications of CVCs. We then designed, delivered, and measured the effects of a multidisciplinary educational intervention given to 106 incoming house officers.

MEASUREMENTS AND MAIN RESULTS

Although most physicians (127, 91%) chose the Trendelenburg position for CVC insertion, only 42 physicians (30%) reported concern for VAE. On CVC removal, only 36 physicians (26%) cited concern for VAE. Some physicians (13, 9%) reported elevating the head of the bed during CVC removal, possibly increasing the risk of VAE. Awareness of VAE or its prevention did not correlate with the level of physician training, experience, or specialty. After the educational intervention, concern for and awareness of proper methods of prevention of VAE improved (p < .001). At 6-month follow-up, reported use of the Trendelenburg position continued, but concern cited for VAE had returned to baseline.

CONCLUSIONS

There is inadequate awareness of VAE as a complication of CVC use. Focused instruction can improve appreciation of this potentially fatal complication and knowledge of its prevention, but the effect declines rapidly. To achieve a more sustained improvement, a more intensive, hands-on, periodic educational program will likely be necessary, as well as reinforcement through enhanced supervision of CVC insertion and removal practices.

Role of arachidonyl triglycerides within lipid bodies in eicosanoid formation by human polymorphonuclear cells

Increasing evidence suggests that the subcellular and glycerolipid localization of esterified arachidonic acid (AA) is a key factor in regulating its availability to lipases. The goal of the current study was to determine the potential of AA stored in triglycerides (TG) to serve as a substrate for lipases and 5-lipoxygenase during neutrophil (polymorphonuclear leukocytes, PMN) activation. PMN containing high concentrations of AA in TG were generated by culturing PMN in vitro with high concentrations of exogenous AA (eAA) for 12 h. Cellular AA increased 2- and 4-fold in PMNs incubated with 5 and 20 microM AA, respectively, and this increase was almost exclusively observed in neutral lipids (NL). Further analysis revealed that 88% of the AA in the NL fraction was associated with TG. Subsequent experiments were designed to determine whether this AA in TG could be mobilized and metabolized to eicosanoids during cell activation. TG pools of AA were increased as previously described and then PMN were stimulated with ionophore, A23187. In contrast to the 43-fold increase in TG AA after eAA loading (20 microM), free AA increased by only 1.9-fold after cell stimulation. Similarly, leukotriene (LT)B(4) production increased only 2-fold after loading TG with large quantities of AA. The magnitude of increase in free AA released and in LTB(4) formation was similar to the magnitude of increase in AA mass in phospholipase (PL), suggesting that PL, and not TG, served as the source of released AA and subsequent product generation. To confirm that AA in TG did not serve as a source for eicosanoid production, cellular pools of AA were differentially labeled with [(14)C]AA and [(3)H]AA, and the [(3)H]AA-to-[(14)C]AA ratio of LTB(4) and 20-hydroxyl LTB(4) produced during cell stimulation was measured. The [(3)H]AA/[(14)C]AA ratios of LTs were markedly different from the ratios in TG, thus providing further evidence that AA pools in TG are not a major source of AA for LT generation.

Effect of carbon dioxide on testing of susceptibilities of respiratory tract pathogens to macrolide and azalide antimicrobial agents

The in vitro activities of erythromycin, azithromycin, and clarithromycin against 178 clinical isolates from the lower respiratory tract of patients with chronic obstructive pulmonary disease were determined by an agar dilution method. The plates were incubated in air alone or in 5% carbon dioxide. The MICs measured in air alone were lower for most isolates than those measured in 5% carbon dioxide, illustrating the "pH effect" of incubation in carbon dioxide. Testing of isolates in 5% carbon dioxide on pH-adjusted medium (pH 8.4) resulted in MICs of one or two doubling dilutions lower than those obtained on agar with a neutral pH. A bioassay of the three agents incubated in air and in 5% carbon dioxide resulted in a significant loss of activity of all three agents in the carbon dioxide-enriched atmosphere. However, this loss-of-activity effect was significantly reduced when the bioassay medium was adjusted to pH 8.4 prior to incubation in 5% carbon dioxide.

Effect of respirator inspiratory resistance level on constant load treadmill work performance

Respirator inspiratory resistance can affect performance times, especially when the experiment is optimized to elicit respiratory stress. Twelve subjects performed on a treadmill at constant speeds and grades chosen to result in performance times of 5-15 min. Six levels of inspiratory resistance were used, ranging from 0.78 to 7.64 cm H2O.sec/L. The results showed that performance times decrease linearly with resistance level, and no threshold resistance value is apparent. Inspiratory resistance also induces hypoventilation, with lower minute volumes and lower oxygen consumption values at higher resistances. These trends are also linear. From these results, there is no value for inspiratory resistance that can be given as a design goal. Other parameters such as weight and space may dictate filter resistance values, and these, in turn, will lead to determined performance degradations.

Interactions with colleagues and their effects on the satisfaction of rural primary care physicians

Physician work satisfaction is related to several aspects of practice organization, including work group or colleagues, job content, work hours, and future opportunities. Practice location is an important determinant of practice organization and personal life satisfaction. This study compared the professional satisfaction of physicians in rural and urban settings to determine how practice setting, practice type, work hours, and interactions with colleagues influenced satisfaction. Surveys focusing on professional satisfaction were mailed to community-based, primary care physicians in Kentucky. Overall, physicians were satisfied with their practices, with physicians in larger communities being more satisfied than those from smaller communities. Professional satisfaction was associated with practice location, practice type, number of years since graduation from medical school, number of colleagues identified, and the quality of professional interactions with colleagues. The study concluded that collegial support for physicians is important in creating work environments that promote professional satisfaction.

Determinant spreading associated with demyelination in a nonhuman primate model of multiple sclerosis

Definition of the immune process that causes demyelination in multiple sclerosis is essential to determine the feasibility of Ag-directed immunotherapy. Using the nonhuman primate, Callithrix jacchus jacchus (common marmoset), we show that immunization with myelin basic protein and proteolipid protein determinants results in clinical disease with significant demyelination. Demyelination was associated with spreading to myelin oligodendrocyte glycoprotein (MOG) determinants that generated anti-MOG serum Abs and Ig deposition in central nervous system white matter lesions. These data associate intermolecular "determinant spreading" with clinical autoimmune disease in primates and raise important issues for the pathogenesis and treatment of multiple sclerosis.

Radiographic assessment of hyperinflation: correlation with objective chest radiographic measurements and mechanical ventilator parameters

BACKGROUND

Pulmonary barotrauma is a potentially fatal complication of positive pressure ventilation. We previously found that barotrauma occurred in patients with radiographic hyperinflation, but few objective data define the relationships among hyperinflation, objective chest radiograph (CXR) measurements, ventilator parameters, and development of barotrauma.

OBJECTIVES

We sought (1) to assess the relationships among hyperinflation, objective CXR findings, mechanical ventilator parameters, and development of barotrauma. (2) To compare radiographic hyperinflation, ventilator parameters, and incidence of barotrauma in a current group of ICU patients with historical control subjects.

SETTING

Medical and surgical ICU patients in a university hospital.

DESIGN

Prospective blinded observational study; comparison of current series with historical control subjects.

METHODS

One hundred two prospectively enrolled mechanically ventilated medical and surgical ICU patients each received portable supine CXRs that were reviewed independently by three radiologists who made objective measurements and subjectively determined the likelihood of hyperinflation. Ventilator parameters were recorded at the bedside at the time each CXR was obtained. CXR measurements and ventilator parameters were then related to the development of barotrauma during the course of ventilation and compared with findings of a prospective study at our institution 1 year earlier.

RESULTS

Radiographically recognizable hyperinflation occurred in 18 of 102 mechanically ventilated ICU patients (18%) and correlated with lung length (24.7 vs 19.8 cm; p<0.05) and the anterior rib number that intersects the hemidiaphragm (5.4 vs 4.7; p<0.05). Patients with hyperinflation were ventilated at higher tidal volume per kilogram (VT/kg) (11.0 vs 9.4; p=0.0081), but peak airway pressure, plateau pressure, and positive end-expiratory pressure were similar. There were significant decreases in VT (810 vs 739 mL; p=0.015) and VT/kg (11.0 vs 10.1 mL/kg; p<0.001) in these mechanically ventilated ICU patients in comparison to hospital control subjects evaluated during the previous year. Paralleling these changes was a decrease in the frequency of CXR hyperinflation (p=0.003) and the incidence of ventilator-associated barotrauma (6.5% vs 0.98%; p=0.048).

CONCLUSIONS

Ventilation at higher VT/kg is associated with a higher incidence of CXR hyperinflation. Radiographic hyperinflation is associated with lung length > or =24.7 cm and visualization of the sixth anterior rib. Patients with hyperinflation may be at greater risk for developing barotrauma or volutrauma. Ventilatory strategies utilizing lower volumes are associated with a lower incidence of such trauma in the current sample as compared with historical control subjects.

Dietary supplementation with gamma-linolenic acid alters fatty acid content and eicosanoid production in healthy humans

To understand the in vivo metabolism of dietary gamma-linolenic acid (GLA), we supplemented the diets of 29 volunteers with GLA in doses of 1.5-6.0 g/d. Twenty-four subjects ate controlled eucaloric diets consisting of 25% fat; the remaining subjects maintained their typical Western diets. GLA and dihomo-gamma-linolenic acid (DGLA) increased in serum lipids of subjects supplemented with 3.0 and 6.0 g/d; serum arachidonic acid increased in all subjects. GLA supplementation with 3.0 and 6.0 g/d also resulted in an enrichment of DGLA in neutrophil phospholipids but no change in GLA or AA levels. Before supplementation, DGLA was associated primarily with phosphatidylethanolamine (PE) of neutrophil glycerolipids, and DGLA increased significantly in PE and neutral lipids after GLA supplementation. Extending the supplementation to 12 wk did not consistently change the magnitude of increase in either serum or neutrophil lipids in subjects receiving 3.0 g/d. After GLA supplementation, A23187-stimulated neutrophils released significantly more DGLA, but AA release did not change. Neutrophils obtained from subjects after 3 wk of supplementation with 3.0 g/d GLA synthesized less leukotriene B4 (P < 0.05) and platelet-activating factor. Together, these data reveal that DGLA, the elongase product of GLA, but not AA accumulates in neutrophil glycerolipids after GLA supplementation. The increase in DGLA relative to AA within inflammatory cells such as the neutrophil may attenuate the biosynthesis of AA metabolites and may represent a mechanism by which dietary GLA exerts an anti-inflammatory effect.

The effect of a rolling admission policy on a medical school's selection of applicants

PURPOSE

As the University of Kentucky College of Medicine (UKCM) employs a rolling admission policy, this study was designed to determine (1) whether the month during which applicants were considered by the UKCM admission committee was associated with admission status, (2) whether applicants considered early in the process differed in selected academic and noncognitive pre-admission characteristics in comparison with later applicants, and (3) what the importance of the month of the applicant's consideration was relative to other predictors of admission to UKCM.

METHOD

The application files and admission committee's minutes regarding 302 applicants who received interviews during the 1993-94 application cycle were examined. Data reviewed included each applicant's gender, age, geographic origin, undergraduate science and non-science grade-point averages, and Medical College Admission Test scores; the date of consideration by the committee; interviewers' ratings; the initial motion on the applicant; and the final admission status.

RESULTS

The findings indicate that the applicants considered earlier were significantly more likely to gain admission. However, upon assigning the applicants to three groups according to the month of consideration, no difference in academic qualifications was found. Regression analyses revealed that despite the effect of time of consideration, noncognitive characteristics related to UKCM's mission also predicted admission decisions.

CONCLUSION

This study provides useful information to admission committees reviewing the effect of a rolling admission policy, as well as to applicants and premedical advisors, who should be aware of the potential importance of submitting applications in a timely manner.

A comparison of specialty choices, residency training, and practice locations of early-decision and regular-admission graduates

PURPOSE

Early-decision (ED) medical school applicants express a clear preference for attending a particular medical school. The present study assessed whether ED graduates would demonstrate similar geographic preferences in their choices of undergraduate institutions and selections of in-state residency sites and practice locations.

METHOD

The study was conducted at the University of Kentucky College of Medicine. Uniform academic and nonacademic criteria were used to evaluate the applications of ED and regular-admission students who matriculated from 1974-75 to 1984-85. The student variables assessed were class year, gender, age, county of residence, and undergraduate college, as well as undergraduate science and cumulative grade-point averages (GPAs) and Medical College Admission Test (MCAT) scores. Specialty choice and locations of residency programs were obtained from the medical school's commencement programs. Specialty types and practice locations were obtained from practicing physician records maintained by the alumni office.

RESULTS

Of the 1,243 matriculants, 193 (15.5%) gained admission to the school through the ED plan. The ED graduates were significantly more likely to have completed their undergraduate studies at the University of Kentucky than at other public or private schools, in state or out of state, and had significantly higher GPAs and MCAT scores. As a group, the ED graduates were somewhat (though not significantly) more likely than the regular-admission graduates to remain in state for their residencies and practice in state.

CONCLUSION

The authors suggest that medical schools should work closely with their undergraduate admission offices to attract academically outstanding high school students. Such students are likely to stay in state for the eight-year span of their undergraduate and medical educations and may have a greater tendency to practice in state.

Individual differences in the voluntary use of a memory aid during decision making

To characterize selective uses of external memory aids, 42 younger and 38 older adults made decisions and then completed individual difference measures. Experimental manipulation of the availability of a memory aid allowed examination of the effects of having a memory aid available as opposed to the spontaneous use of that aid. Use of the memory aid resulted in longer decision times, more requests for information, and less rechecking of already viewed information. Younger and older adults with high abstraction scores and older adults with high vocabulary scores were more likely to use the aid. Patterns of use differed in that younger adults used the aid in the middle of their information gathering and older adults used the aid toward the end. Making a memory aid available for use during decision making affected decision-making processes of older adults; use of the aid was associated with greater crystallized and fluid intelligence.

Effect on the duration of mechanical ventilation of identifying patients capable of breathing spontaneously

BACKGROUND

Prompt recognition of the reversal of respiratory failure may permit earlier discontinuation of mechanical ventilation, without harm to the patient.

METHODS

We conducted a randomized, controlled trial in 300 adult patients receiving mechanical ventilation in medical and coronary intensive care units. In the intervention group, patients underwent daily screening of respiratory function by physicians, respiratory therapists, and nurses to identify those possibly capable of breathing spontaneously; successful tests were followed by two-hour trials of spontaneous breathing in those who met the criteria. Physicians were notified when their patients successfully completed the trials of spontaneous breathing. The control subjects had daily screening but no other interventions. In both groups, all clinical decisions, including the decision to discontinue mechanical ventilation, were made by the attending physicians.

RESULTS

Although the 149 patients randomly assigned to the intervention group had more severe disease, they received mechanical ventilation for a median of 4.5 days, as compared with 6 days in the 151 patients in the control group (P=0.003). The median interval between the time a patient met the screening criteria and the discontinuation of mechanical ventilation was one day in the intervention group and three days in the control group (P<0.001). Complications -- removal of the breathing tube by the patient, reintubation, tracheostomy, and mechanical ventilation for more than 21 days -- occurred in 20 percent of the intervention group and 41 percent of the control group (P=0.001). The number of days of intensive care and hospital care was similar in the two groups. Total costs for the intensive care unit were lower in the intervention group (median, $15,740, vs. $20,890 in the controls, P=0.03); hospital costs were lower, though not significantly so (median, $26,229 and $29,048, respectively; P=0.3).

CONCLUSIONS

Daily screening of the respiratory function of adults receiving mechanical ventilation, followed by trials of spontaneous breathing in appropriate patients and notification of their physicians when the trials were successful, can reduce the duration of mechanical ventilation and the cost of intensive care and is associated with fewer complications than usual care.

Chest X-ray changes in air space disease are associated with parameters of mechanical ventilation in ICU patients

To assess relationships between parameters of mechanical ventilation (MV) and portable chest X-ray (CXR) measurements of lung length (LL) and severity of air space disease, a prospective, randomized, blinded comparison of 102 adults in a university hospital was performed. Each patient received two portable, supine CXRs on different MV breaths within 5 min of one another. Ventilator parameters were recorded. All 204 CXRs were randomly assorted and read independently by three radiologists. Air space disease was considered more severe with pressure support ventilation (PSV) breaths than with intermittent mandatory ventilation (IMV) breaths (p = 0.0003), and its extent correlated inversely with static compliance (p = 0.0001, r = -0.40). Among patients having CXRs on both IMV and PSV breaths, 15 of 67 (22%) had their overall degree of air space disease read differently by one category (mild, moderate, or severe). Increases in LL between the two CXRs were associated with increasing peak (p = 0.0038) or mean (p = 0.0065) airway pressure, tidal volume (VT) (p = 0.022), and VT per kilogram (p = 0.006). We conclude that lung volume changes during MV, typically not noted nor controlled for during portable chest radiography, may substantially alter the interpretation of air space disease and LL. Physicians monitoring intensive care unit (ICU) patients with daily CXRs should be aware of the variables influencing interpretation of portable CXRs of ICU patients.

Geographic origin and its impact on practice location in Kentucky

This study examined which medical students from the University of Kentucky College of Medicine are most likely to return to their geographic origins to practice medicine and the frequency with which this occurs. This study is based on statistical analysis of longitudinal data (1974-1985). The database includes 1243 matriculants for whom residency data were available. Follow-up data were available for 1093 physicians-in-practice. Results indicate that a significant percentage of matriculants return to their in-state district of origin to practice. Significant predictors of practice location included gender, undergraduate institution, and residence at admission. However, these factors explained only 8% of the variance in physician practice location. Expanding the model to include location of residency program and specialty choice contributed an additional 14% of the variance. Admissions officers seeking to improve the ratio of graduates practicing in rural areas should devise new measures to assess applicant's attraction to positive aspects of rural medical practice or small town life.

Compliance with the screening mammography program of British Columbia: will she return?

OBJECTIVE

To identify factors associated with compliance in the Screening Mammography Program of British Columbia (SMPBC).

METHOD

Factors associated with rescreening within 18 months (annual compliers) and between 18 to 36 months later (late compliers) were identified in a cohort of SMPBC screenees using a self-administered questionnaire.

RESULTS

Fewer than half of women initially screened within the SMPBC were annual compliers, nearly 40% not returning by 3 years. In women age 50+ years, annual compliers tended to have no prior mammography, no prior breast pain, a physician referral to SMPBC, and a normal initial SMPBC mammogram. Late compliers also tended to have no prior mammography, a physician referral, and a normal initial SMPBC mammogram.

CONCLUSIONS

Several modifiable factors associated with compliance were identified: a physician referral to the program and possibly subsequent referral back to the program after workup for an abnormal mammogram.

Metabolism of gammalinolenic acid in human neutrophils

Gammalinolenic acid (GLA), when provided as a dietary supplement, has been reported to improve clinical symptoms of several inflammatory disorders. The goal of the current study was to examine the metabolism of GLA and its relationship to arachidonic acid (AA) in the human neutrophil. Initial studies indicated that neutrophils provided GLA in vitro rapidly elongate it (by two carbons) to dihomogammalinolenic acid (DGLA). The bulk of this newly formed DGLA is incorporated into neutral lipids and specifically triacylglycerides. Neutrophils from volunteers supplemented with GLA as borage oil also had elevated quantities of DGLA but not GLA, when compared with neutrophils from volunteers not consuming the GLA supplement. To determine whether DGLA could be mobilized from cellular glycerolipids, neutrophils were stimulated with ionophore A23187 and fatty acid levels were determined. DGLA and AA were both released during stimulation, and the quantities of DGLA mobilized increased threefold after in vitro GLA supplementation. Exogenously provided DGLA was converted to one major metabolite during cell stimulation; this product migrated on reverse-phase HPLC with the 15-lipoxygenase product, 15-hydroxy-eicosa-trienoic acid (15-HETre). Both 15-HETre and DGLA (provided exogenously) inhibited the formation of leukotriene B4, (LTB4) and 20-hydroxy-leukotriene B4 (20-OH-LTB4). The IC50 for 15-HETre inhibition of both LTR, and 20-OH-LTB4 in A23187-stimulated neutrophils was 5 microM. This inhibition could be reversed by removing the compounds from the cells. Taken together, these data reveal that there are enzymes within the human neutrophil that metabolize GLA or its elongation product DGLA, and that the metabolism of GLA and AA may interact at a number of critical junctures.

Metabolism of gammalinolenic acid in human neutrophils

Gammalinolenic acid (GLA), when provided as a dietary supplement, has been reported to improve clinical symptoms of several inflammatory disorders. The goal of the current study was to examine the metabolism of GLA and its relationship to arachidonic acid (AA) in the human neutrophil. Initial studies indicated that neutrophils provided GLA in vitro rapidly elongate it (by two carbons) to dihomogammalinolenic acid (DGLA). The bulk of this newly formed DGLA is incorporated into neutral lipids and specifically triacylglycerides. Neutrophils from volunteers supplemented with GLA as borage oil also had elevated quantities of DGLA but not GLA, when compared with neutrophils from volunteers not consuming the GLA supplement. To determine whether DGLA could be mobilized from cellular glycerolipids, neutrophils were stimulated with ionophore A23187 and fatty acid levels were determined. DGLA and AA were both released during stimulation, and the quantities of DGLA mobilized increased threefold after in vitro GLA supplementation. Exogenously provided DGLA was converted to one major metabolite during cell stimulation; this product migrated on reverse-phase HPLC with the 15-lipoxygenase product, 15-hydroxy-eicosa-trienoic acid (15-HETre). Both 15-HETre and DGLA (provided exogenously) inhibited the formation of leukotriene B4, (LTB4) and 20-hydroxy-leukotriene B4 (20-OH-LTB4). The IC50 for 15-HETre inhibition of both LTR, and 20-OH-LTB4 in A23187-stimulated neutrophils was 5 microM. This inhibition could be reversed by removing the compounds from the cells. Taken together, these data reveal that there are enzymes within the human neutrophil that metabolize GLA or its elongation product DGLA, and that the metabolism of GLA and AA may interact at a number of critical junctures.

Thoracobiliary fistula

Thoracobiliary communications in the form of either pleurobiliary or bronchobiliary fistulas are reported complications of many diseases. A strong suspicion in the appropriate clinical setting is necessary to recognize this problem. Bilioptysis is the sine qua non of a bronchobiliary fistula. Diagnostic imaging studies are useful to identify the communication and to delineate its location. Although surgery is the optimal intervention, percutaneous drainage and intravenous antimicrobial therapy may offer the best therapeutic option in patients with metastatic cancer and limited physiologic reserve. We report a unique case of bronchobiliary fistula complicating a uterine leiomyosarcoma with hepatic metastases. Long-term palliation was achieved with percutaneous drainage and appropriate fluid and electrolyte replacement therapy.

Respiratory rehabilitation, exercise capacity and quality of life in chronic airways disease in old age

Respiratory rehabilitation improves exercise capacity and quality of life in younger patients but is untried in the aged. We aimed to: (a) assess repeatability of the 6-minute walk test, factors affecting it and its relation to quality of life in elderly patients with chronic obstructive airways disease (COAD); (b) assess compliance of such patients with an intensive respiratory rehabilitation protocol; (c) pilot the assessment of the effect of respiratory rehabilitation on the 6-minute walk test in these patients. Seventeen subjects with stable, symptomatic COAD were recruited, 15 (six men), 70-89 (mean 76) years, completed the study. Mean (standard deviation) 1-second forced expiratory volume (FEV1) = 49 (5)% predicted. Six-minute walk tests were repeated single-blind, 2-10 days apart. Quality of life was measured using Guyatt respiratory questionnaire. Patients underwent 12 weeks incremental respiratory rehabilitation (x4/day step-ups, unweighed arm raises, inflating balloons). Baseline 6-minute walk was repeatable and was correlated with the log Guyatt dyspnoea score (r = 0.65, p = 0.006). In multiple regression neither age nor FEV1 predicted walk distance: body mass index, maximal expiratory mouth pressure; calorie intake. Mean (SEM) 6-minute walk distance after-rehabilitation was greater than baseline (p = 0.003). Elderly patients with COAD tolerate intensive respiratory rehabilitation and a controlled, blinded study is needed.

Work hardening: evidence for success of a program

The effectiveness of a work hardening program in facilitating gains in physical strength and return to work in 40 chronic low back-pain clients was assessed. Statistically significant gains in physical strength were found. Also, 27 of the 32 clients reached by follow-up telephone calls returned to work full time.

In vivo study of indomethacin in bronchiectasis: effect on neutrophil function and lung secretion

Bronchiectasis is associated with sputum containing high levels of the proteolytic enzyme elastase, which is thought to be involved in the pathogenesis of the disease. Agents which inhibit neutrophil function and interfere with neutrophil elastase release may have a beneficial effect on the development and progression of such diseases. We have studied the effects of the nonsteroidal anti-inflammatory agent indomethacin on neutrophil function in nine patients with clinically stable bronchiectasis. All patients remained clinically stable during the study. We observed a significant reduction in peripheral neutrophil chemotaxis to 10 nmol.L-1 N-formyl-methionyl-leucyl-phenylalanine (FMLP) from a mean of 19.86 (SEM 1.35) to 8.46 (0.68) cells.field-1 after 4 weeks of therapy. There was also a significant reduction in fibronectin degradation both by resting and FMLP-stimulated neutrophils, from a mean of 1.90 (0.19) micrograms x 3 x 10(5) cells at the start of therapy to 0.87 (0.08) micrograms after 4 weeks, and from 3.17 (0.35) micrograms to 1.48 (0.05) micrograms, respectively. There was no effect on spontaneous or stimulated superoxide anion generation by neutrophils. Despite the marked changes in peripheral neutrophil function, no adverse effect was observed on viable bacterial load in the bronchial secretions. In addition, there was no difference in sputum albumin, elastase or myeloperoxidase levels, and only minor changes in the chemotactic activity of the sputum. These results suggest that nonsteroidal anti-inflammatory agents have a major effect on peripheral neutrophil function but do not appear to have an adverse effect on bacterial colonization of the airways.