Cardiologic problems in the post acute ventilated patient

Chronically critically ill patients who develop acute respiratory failure commonly have complicating cardiac pathology that may or may not be evident at initial evaluation. The acute coronary syndromes should be excluded in all patients presenting with respiratory failure. Cardiac rhythm disturbances are common and should be actively investigated and treated in all critically ill patients. Heart failure is common in the chronically critically ill patient but usually responds to early diagnosis and prompt treatment. Finally, cardiogenic shock carries a poor prognosis in most patient subsets except when it is caused by cardiac tamponade. The intensivist must be vigilant for cardiac pathology complicating the recovery of patients with acute respiratory illness and initiate the search for correctable problems that may precipitate further episodes of respiratory insufficiency.

Regulation of medical devices in radiology: current standards and future opportunities

Today's radiology community depends heavily on cutting-edge diagnostic and therapeutic medical devices to serve patients. These products are regulated by the U.S. Food and Drug Administration (FDA) under a system that grants marketing approval for only those indications for which the safety and effectiveness have been established. Although this complex system is the result of a societal decision to ensure device safety and effectiveness, it has the potential to delay product marketing and impede innovation. Medical device regulation recently has undergone major changes with the enactment of the Food and Drug Administration Modernization Act of 1997 (FDAMA), legislation that is intended to increase system efficiency while retaining the requirement of safety and effectiveness. However, many of the envisioned improvements cannot occur without cooperative interaction between stakeholders in the device development process, including the FDA and the clinical medicine community. The radiology field must continue to build on its strong history of productive dialogue with the FDA to transform the legislative vision of FDAMA into regulatory reality. Such action will ensure timely access to the new device technologies that are necessary for the growth of our specialty and the effective care of our patients.

A role for the peroxin Pex8p in Pex20p-dependent thiolase import into peroxisomes of the yeast Yarrowia lipolytica

Peroxins are proteins required for peroxisome assembly. The cytosolic peroxin Pex20p binds directly to the beta-oxidation enzyme thiolase and is necessary for its dimerization and peroxisomal targeting. The intraperoxisomal peroxin Pex8p has a role in the import of peroxisomal matrix proteins, including thiolase. We report the results of yeast two-hybrid analyses with various peroxins of the yeast Yarrowia lipolytica and characterize more fully the interaction between Pex8p and Pex20p. Coimmunoprecipitation showed that Pex8p and Pex20p form a complex, while in vitro binding studies demonstrated that the interaction between Pex8p and Pex20p is specific, direct, and autonomous. Pex8p fractionates with peroxisomes in cells of a PEX20 disruption strain, indicating that Pex20p is not necessary for the targeting of Pex8p to peroxisomes. In cells of a PEX8 disruption strain, thiolase is mostly cytosolic, while Pex20p and a small amount of thiolase associate with peroxisomes, suggesting the involvement of Pex8p in the import of thiolase after docking of the Pex20p-thiolase complex to the membrane. In the absence of Pex8p, peroxisomal thiolase and Pex20p are protected from the action of externally added protease. This finding, together with the fact that Pex8p is intraperoxisomal, suggests that Pex20p may accompany thiolase into peroxisomes during import.

Heart failure etiology affects peripheral vascular endothelial function after cardiac transplantation

OBJECTIVES

The goal of this study was to examine the effect of heart failure etiology on peripheral vascular endothelial function in cardiac transplant recipients.

BACKGROUND

Peripheral vascular endothelial dysfunction occurs in patients with heart failure of either ischemic or nonischemic etiology. The effect of heart failure etiology on peripheral endothelial function after cardiac transplantation is unknown.

METHODS

Using brachial artery ultrasound, endothelium-dependent, flow-mediated dilation (FMD) was assessed in patients with heart failure with either nonischemic cardiomyopathy (n = 10) or ischemic cardiomyopathy (n = 7), cardiac transplant recipients with prior nonischemic cardiomyopathy (n = 10) or prior ischemic cardiomyopathy (n = 10) and normal controls (n = 10).

RESULTS

Patients with heart failure with either ischemic cardiomyopathy or nonischemic cardiomyopathy had impaired FMD (3.6 +/- 1.0% and 5.1 +/- 1.2%, respectively, p = NS) compared with normal subjects (13.9 +/- 1.3%, p < 0.01 compared with either heart failure group). In transplant recipients with antecedent nonischemic cardiomyopathy, FMD was markedly higher than that of heart failure patients with nonischemic cardiomyopathy (13.0 +/- 2.4%, p < 0.001) and similar to that of normal subjects (p = NS). However, FMD remained impaired in transplant recipients with prior ischemic cardiomyopathy (5.5 +/- 1.5%, p = 0.001 compared with normal, p = 0.002 vs. transplant recipients with previous nonischemic cardiomyopathy).

CONCLUSIONS

Peripheral vascular endothelial function is normal in cardiac transplant recipients with antecedent nonischemic cardiomyopathy, but remains impaired in those with prior ischemic cardiomyopathy. In contrast, endothelial function is uniformly abnormal for patients with heart failure, regardless of etiology. These findings indicate that cardiac transplantation corrects peripheral endothelial function for patients without ischemic heart disease, but not in those with prior atherosclerotic coronary disease.

The osmolyte xylitol reduces the salt concentration of airway surface liquid and may enhance bacterial killing

The thin layer of airway surface liquid (ASL) contains antimicrobial substances that kill the small numbers of bacteria that are constantly being deposited in the lungs. An increase in ASL salt concentration inhibits the activity of airway antimicrobial factors and may partially explain the pathogenesis of cystic fibrosis (CF). We tested the hypothesis that an osmolyte with a low transepithelial permeability may lower the ASL salt concentration, thereby enhancing innate immunity. We found that the five-carbon sugar xylitol has a low transepithelial permeability, is poorly metabolized by several bacteria, and can lower the ASL salt concentration in both CF and non-CF airway epithelia in vitro. Furthermore, in a double-blind, randomized, crossover study, xylitol sprayed for 4 days into each nostril of normal volunteers significantly decreased the number of nasal coagulase-negative Staphylococcus compared with saline control. Xylitol may be of value in decreasing ASL salt concentration and enhancing the innate antimicrobial defense at the airway surface.

Regulation of peroxisome size and number by fatty acid beta -oxidation in the yeast yarrowia lipolytica

The Yarrowia lipolytica MFE2 gene encodes peroxisomal beta-oxidation multifunctional enzyme type 2 (MFE2). MFE2 is peroxisomal in a wild-type strain but is cytosolic in a strain lacking the peroxisomal targeting signal-1 (PTS1) receptor. MFE2 has a PTS1, Ala-Lys-Leu, that is essential for targeting to peroxisomes. MFE2 lacking a PTS1 can apparently oligomerize with full-length MFE2 to enable targetting to peroxisomes. Peroxisomes of an oleic acid-induced MFE2 deletion strain, mfe2-KO, are larger and more abundant than those of the wild-type strain. Under growth conditions not requiring peroxisomes, peroxisomes of mfe2-KO are larger but less abundant than those of the wild-type strain, suggesting a role for MFE2 in the regulation of peroxisome size and number. A nonfunctional version of MFE2 did not restore normal peroxisome morphology to mfe2-KO cells, indicating that their phenotype is not due to the absence of MFE2. mfe2-KO cells contain higher amounts of beta-oxidation enzymes than do wild-type cells. We also show that increasing the level of the beta-oxidation enzyme thiolase results in enlarged peroxisomes. Our results implicate peroxisomal beta-oxidation in the control of peroxisome size and number in yeast.

Effects of losartan and captopril on left ventricular volumes in elderly patients with heart failure: results of the ELITE ventricular function substudy

BACKGROUND

The mechanism by which angiotensin-converting enzyme inhibitors reduce mortality rates and disease progression in patients with heart failure is likely mediated in part through prevention of adverse ventricular remodeling. This study examined the effects of the angiotensin-converting enzyme inhibitor captopril and the angiotensin II type 1 receptor antagonist losartan on ventricular volumes and function in elderly patients with heart failure and reduced left ventricular ejection fraction (< or =40%).

METHODS

Patients underwent radionuclide ventriculograms (RVG) at baseline and were randomized to either captopril (n = 16) or losartan (n = 13). After 48 weeks, another RVG was obtained. Therapy was then withdrawn for at least 5 days, and the RVG was repeated while the patient was not receiving the drug.

RESULTS

At 48 weeks both captopril and losartan significantly reduced left ventricular (LV) end-diastolic volume index (135 +/- 26 to 128 +/- 23 mL/m(2) for losartan, P <.05 vs baseline; 142 +/- 25 to 131 +/- 20 mL/m(2) for captopril, P <.01; mean (SD). Captopril also reduced LV end-systolic volume index (98 +/- 24 to 89 +/- 21 mL/m(2), P <.01 vs. baseline), whereas a nonsignificant trend was observed for the losartan group (97 +/- 23 to 90 +/- 16 mL/m(2), P = not significant). The between-group differences in the changes in LV volumes were not statistically significant. After drug withdrawal, LV end-diastolic volume index remained significantly lower than baseline in the captopril group (P <.01).

CONCLUSIONS

Both captopril and losartan prevent LV dilation, representing adverse ventricular remodeling, previously seen with placebo treatment. Reverse remodeling was observed in the captopril group. On the basis of these results, the relative effects on LV remodeling do not provide a rationale for a survival benefit of losartan over captopril.

An investigation of the effect of 2 sedation regimens on patient mood state following upper extremity surgery using local anesthesia

Sedation techniques for patients undergoing minor outpatient surgery frequently include a variety of intravenous agents. The present study was designed to look for differential effects of 2 different sedation regimens on perioperative mood states. Twenty-two patients undergoing upper extremity surgery using local anesthesia were randomized to receive either propofol or midazolam intravenously for intraoperative sedation. Subjects were asked to complete a Profile of Mood States survey before and after surgery. The results of this survey were examined for differences in mood between the 2 groups that may be attributable to differences in drug effect. No significant differences were identified between propofol or midazolam regarding their effect on patient mood. Patients in both groups experienced a reduction in perioperative anxiety.

Measuring the quality of life in patients with venous ulcers

PURPOSE

This prospective study aimed to validate a newly designed specific measure of quality of life for patients with venous ulcers.

METHODS

The study was set in a London teaching hospital and surrounding community clinics. Items for the questionnaire were selected by means of patient interviews, a literature review, and expert opinion. The questionnaire and the Short Form 36-item (SF-36) Health Survey were given to a prospective consecutive cohort of 98 patients with proven venous ulcers that were diagnosed by means of clinical and color duplex examination. Fifty-eight of the patients were women (60%), and the median age of patients was 76 years. The questionnaire was assessed for reliability, validity, and responsiveness.

RESULTS

The ulcer-specific questionnaire showed good reliability, as assessed by means of the internal consistency (Cronbach alpha = 0.93) and test-retest analysis (r = 0.84). Factor analysis identified four important health factors: social function, domestic activities, cosmesis, and emotional status. Validity was demonstrated by means of a high correlation with all eight domains of the SF-36 general health measure (r > 0.55, P <.001). Responsiveness was demonstrated by means of a significant reduction in the score on the ulcer questionnaire as ulcers healed at 6 and 11 weeks (P <.05).

CONCLUSION

Good evidence exists that a clinically derived measure for patients with venous ulcers has validity to measure the quality of life.

Evidence that auxin promotes gibberellin A1 biosynthesis in pea

In shoots of the garden pea, the bioactive gibberellin (GA1) is synthesised from GA20, and the enzyme which catalyses this step (a GA 3-oxidase -- PsGA3ox1) is encoded by Mendel's LE gene. It has been reported previously that decapitation of the shoot (excision of the apical bud) dramatically reduces the conversion of [3H]GA20 to [3H]GA1 in stems, and here we show that endogenous GA1 and PsGA3ox1 transcript levels are similarly reduced. We show also that these effects of decapitation are completely reversed by application of the auxin indole-3-acetic acid (IAA) to the 'stump' of decapitated plants. Gibberellin A20 is also converted to an inactive product, GA29, and this step is catalysed by a GA 2-oxidase, PsGA2ox1. In contrast to PsGA3ox1, PsGA2ox1 transcript levels were increased by decapitation and reduced by IAA application. Decapitation and IAA treatment did not markedly affect the level of GA1 precursors. It is suggested that in intact pea plants, auxin from the apical bud moves into the elongating internodes where it (directly or indirectly) maintains PsGA3ox1 transcript levels and, consequently, GA1 biosynthesis.

A randomized study of the safety and antiretroviral activity of hydroxyurea combined with didanosine in persons infected with human immunodeficiency virus type 1. American Foundation for AIDS Research Community-Based Clinical Trials Network

This randomized open-label trial of human immunodeficiency virus type 1-infected persons compared safety and efficacy for 38 patients receiving hydroxyurea/didanosine combination therapy with findings in 42 persons given didanosine monotherapy for 12 weeks, followed by 12 weeks of hydroxyurea/didanosine combination therapy for all patients. Week 12 on-treatment group comparisons showed a mean decrease in virus load between hydroxyurea/didanosine versus didanosine groups of -0.93 versus -0.74 log10 copies/mL (P=.20); a higher percentage of the hydroxyurea/didanosine group below the assay's detection limit (500 copies/mL), 29% versus 7% (P=.017); and median change in CD4 cells for the hydroxyurea/didanosine versus didanosine group of 0 versus 43 cells/mm3 (P=.045), although median change in CD4 percentage was similar (0.9% vs. 1.2%, P=.64). Week 24 virus load reductions and CD4 cell changes were similar in both groups. Intent-to-treat and on-treatment analyses showed similar results. The hydroxyurea/didanosine combination was well tolerated.

Venous ulcer healing by four-layer compression bandaging is not influenced by the pattern of venous incompetence

BACKGROUND

Previous studies have related deep venous incompetence to reduced venous ulcer healing rates. The aim of this study was to determine the relationship between the pattern of venous incompetence and ulcer healing.

METHODS

A total of 198 legs with venous ulceration were investigated with colour venous duplex imaging to determine the presence and site of venous incompetence. All were treated initially with the four-layer bandage technique.

RESULTS

At 6 months, 74 per cent of the venous ulcers had healed using the four-layer bandage technique. There was no significant correlation between the pattern of incompetence and the healing rate of the ulcer. Previous deep vein thrombosis (DVT), increased size of the ulcer and previous episodes of ulceration were associated with a poor healing rate.

CONCLUSION

The four-layer bandage technique achieved an ulcer healing rate of 74 per cent after 6 months, irrespective of the pattern of venous incompetence. Patients with a large ulcer, previous DVT or previous episodes of ulceration had delayed healing, supporting the previous literature.