Accurate, noninvasive continuous monitoring of cardiac output by whole-body electrical bioimpedance

STUDY OBJECTIVES: Cardiac output (CO) is measured but sparingly due to limitations in its measurement technique (ie, right-heart catheterization). Yet, in recent years it has been suggested that CO may be of value in the diagnosis, risk stratification, and treatment titration of cardiac patients, especially those with congestive heart failure (CHF). We examine the use of a new noninvasive, continuous whole-body bioimpedance system (NICaS; NI Medical; Hod-Hasharon, Israel) for measuring CO. The aim of the present study was to test the validity of this noninvasive cardiac output system/monitor (NICO) in a cohort of cardiac patients. DESIGN: Prospective, double-blind comparison of the NICO and thermodilution CO determinations. PATIENTS: We enrolled 122 patients in three different groups: during cardiac catheterization (n = 40); before, during, and after coronary bypass surgery (n = 51); and while being treated for acute congestive heart failure (CHF) exacerbation (n = 31). MEASUREMENTS AND INTERVENTION: In all patients, CO measurements were obtained by two independent blinded operators. CO was measured by both techniques three times, and an average was determined for each time point. CO was measured at one time point in patients undergoing coronary catheterization; before, during, and after bypass surgery in patients undergoing coronary bypass surgery; and before and during vasodilator treatment in patients treated for acute heart failure. RESULTS: Overall, 418 paired CO measurements were obtained. The overall correlation between the NICO cardiac index (CI) and the thermodilution CI was r = 0.886, with a small bias (0.0009 +/- 0.684 L) [mean +/- 2 SD], and this finding was consistent within each group of patients. Thermodilution readings were 15% higher than NICO when CI was < 1.5 L/min/m(2), and 5% lower than NICO when CI was > 3 L/min/m(2). The NICO has also accurately detected CI changes during coronary bypass operation and vasodilator administration for acute CHF. CONCLUSION: The results of the present study indicate that whole-body bioimpedance CO measurements obtained by the NICO are accurate in rapid, noninvasive measurement and the follow-up of CO in a wide range of cardiac clinical situations.     

Proximity of public elementary schools to major roads in Canadian urban areas

Objective

The objective of this study is to examine the relationship between residential exposure to fast-food entrées, using two measures of potential spatial access: proximity (distance to the nearest location) and coverage (number of different locations), and weekly consumption of fast-food meals.

Methods

Traditional fast-food restaurants and non-traditional fast-food outlets, such as convenience stores, supermarkets, and grocery stores, from the 2006 Brazos Valley Food Environment Project were linked with individual participants (n = 1409) who completed the nutrition module in the 2006 Brazos Valley Community Health Assessment.

Results

Increased age, poverty, increased distance to the nearest fast food, and increased number of different traditional fast-food restaurants, non-traditional fast-food outlets, or fast-food opportunities were associated with less frequent weekly consumption of fast-food meals. The interaction of gender and proximity (distance) or coverage (number) indicated that the association of proximity to or coverage of fast-food locations on fast-food consumption was greater among women and opposite of independent effects.

Conclusions

Results provide impetus for identifying and understanding the complex relationship between access to all fast-food opportunities, rather than to traditional fast-food restaurants alone, and fast-food consumption. The results indicate the importance of further examining the complex interaction of gender and distance in rural areas and particularly in fast-food consumption. Furthermore, this study emphasizes the need for health promotion and policy efforts to consider all sources of fast-food as part of promoting healthful food choices.     

Quality control of the latex-fixation test.

Standardization of the latex-fixation test for the detection of rheumatoid factor may be achieved by the preparation of a standard reference serum. A number of guidelines for the quality control of precision and sensitivity of the test are suggested. In the use of dilution procedures, a 0.1 log10 or a 0.05 log10 difference between tubes is employed. The end point is defined and titer expressed in terms of a final dilution represented by the amount of antigen-antibody added. For statistical purposes all serologic data are geometrically expressed. Commercial kits may be standardized in terms of minimum detectable units and normalized for titer and unit values to enable laboratories to compare results.     

Autotransplantation of a premolar to the maxillary anterior region in young children - how long should the donor root be? A case report

Autotransplantation of premolars to anterior region after incisor loss due to trauma is accepted as the best restoration procedure with very long follow-ups. There are two main protocols: Premolars with only two thirds of the root or premolars with complete root development. Premolars with two thirds of the root completed remain vital and show complete pulp obliteration while premolars with closed apex require root canal treatment. The problem arises when the child is very young and the root of the donor premolar is developed for only one third. This case report describes the outcome of an autotransplantation of a lower first premolar with only a third of developed root to the anterior region. The donor tooth was extracted with his follicle and placed instead of tooth No. 21. For the first month esthetics was restored with a glass-fibers ribbon attached to tooth No. 11 and composite material. After a month, the crown erupted and was reshaped to mimic an incisor with composite. Orthodontic movement was performed after 5 mo, in order to alleviate the gingival contour. The final restoration was performed after 15 mo. Follow up showed full root development with normal mobility, continuous periodontal ligament and complete pulp obliteration. A multidisciplinary approach and meticulous preparation are necessary for a positive result in autotransplantation of premolars with only a third of root development to the anterior region and this case report show that this method can be performed in very young children.     

Antibacterial Properties and Mode of Action of a Short Acyl-Lysyl Oligomer

We investigated the potency, selectivity, and mode of action of the oligo-acyl-lysine (OAK) NC₁₂-2β₁₂, which was recently suggested to represent the shortest OAK sequence that retains nonhemolytic antibacterial properties. A growth inhibition assay against a panel of 48 bacterial strains confirmed that NC₁₂-2β₁₂ exerted potent activity against gram-positive bacteria while exhibiting negligible hemolysis up to at least 100 times the MIC. Interestingly, NC₁₂-2β₁₂ demonstrated a bacteriostatic mode of action, unlike previously described OAKs that were bactericidal and essentially active against gram-negative bacteria only. The results of various experiments with binding to model phospholipid membranes correlated well with those of the cytotoxicity experiments and provided a plausible explanation for the observed activity profile. Thus, surface plasmon resonance experiments performed with model bilayers revealed high binding affinity to a membrane composition that mimicked the plasma membrane of staphylococci (global affinity constant [K_app], 3.7 × 10⁶ M⁻¹) and significantly lower affinities to mimics of Escherichia coli or red blood cell cytoplasmic membranes. Additional insertion isotherms and epifluorescence microscopy experiments performed with model Langmuir monolayers mimicking the outer leaflet of plasma membranes demonstrated the preferential insertion of NC₁₂-2β₁₂ into highly anionic membranes. Finally, we provide mechanistic studies in support of the view that the bacteriostatic effect resulted from a relatively slow process of plasma membrane permeabilization involving discrete leakage of small solutes, such as intracellular ATP. Collectively, the data point to short OAKs as a potential source for new antibacterial compounds that can selectively affect the growth of gram-positive bacteria while circumventing potential adverse effects linked to lytic compounds.The widespread resistance of bacteria to conventional antibiotics continues to stimulate the search for alternative antimicrobials, such as the host defense antimicrobial peptides (AMPs). AMPs can demonstrate a broad spectrum of activities, including antibiotic activity against both gram-positive and gram-negative bacteria and antiviral and antifungal activities, as well as chemotactic activity and the ability to stimulate chemokine production (23). While the precise mechanism of action needs to be better understood, a multitude of observations suggest more than one mode of action (8, 60). These include abrupt disruption of the cell membrane, which is often concomitant with rapid depolarization of the transmembrane potential (30, 58), as well as intracellular targets, including inhibition of enzymatic activities (2, 10, 37) and biosynthesis (6, 27, 41, 53). Such a multitarget mode of action might significantly overcome various drug resistance mechanisms, which renders AMPs attractive in a variety of antimicrobial applications (21). Nevertheless, various drawbacks, including high susceptibility to proteolysis, toxicity, and high manufacturing costs, complicate the application of AMPs in systemic routes of administration and encourage de novo and rational design of novel compounds with improved properties.The peptidomimetic approach has emerged in recent years as a powerful means for overcoming the inherent limitations of peptide physical characteristics, where the therapeutic potential can be improved by increasing selectivity and bioavailability (9, 40, 45, 49, 52). Peptidomimetic strategies consisting of peptide backbone modifications and incorporation of unnatural amino acids, aromatic rings (25), and amino fatty acids (43, 44) have been proposed as novel building blocks to improve potency by enhancing binding affinity to membranes and to reduce susceptibility to inactivation by serum proteases (39). Oligo-acyl-lysines (OAKs) are among the simpler AMP-mimetic designs, in which the two most important characteristics for AMP activity, hydrophobicity and charge, are represented as tandem repeats of amide-linked fatty acids and lysines (15, 42-44, 46, 48). This design was shown to overcome the limitations of conventional AMPs with respect to in vivo efficacy and toxicity (43-45). Two types of OAKs have been presented so far, each composed of acyl-lysyl (α_n) or lysyl-acyl-lysyl (β_n) subunits, where n defines the acyl length (43). In previous studies, the α-OAKs C₁₂K-7α₈ (44) and C₁₂K-5α₈ (46) showed potent antibacterial activity against most gram-negative strains tested, both in vitro and in vivo. Furthermore, the OAKs were shown to induce bacterial death by damaging the cytoplasmic membrane or by inhibiting DNA expression, respectively. Shorter OAK sequences also displayed potent antiplasmodial activity (42) but were too hemolytic to be considered for systemic applications.To study the structure-activity relationships in OAKs, we recently used a rapid screening assay to test >100 OAK sequences for their hemolytic activities against human red blood cells (RBCs) and antibacterial activities against Escherichia coli and Staphylococcus aureus as representatives of gram-negative and gram-positive bacteria, respectively. The structure-activity relationships that emerged indicated that the self-assembly properties of excessively hydrophobic OAKs are responsible for poor antibacterial properties and for high hemolytic activity (43). Moreover, the study suggested that the minimal requirements for potent and selective antibacterial activity are embedded in the sequence aminolauryl-[lysyl-aminolauryl-lysyl]₂ (designated NC₁₂-2β₁₂), the structure of which is depicted in Fig. ​Fig.1a.1a. Here, we tested this premise and further characterized the antimicrobial properties of NC₁₂-2β₁₂ to shed new light on the mechanism of action.Open in a separate windowFIG. 1.Biophysical characteristics of NC₁₂-2β₁₂. (a) OAK molecular structure (mass, 1,121.7 g/mol). (b and c) Effects of ionic strength and pH on antimicrobial activity, as assessed against two strains of S. aureus: ATCC 29213 (squares) and ATCC 25923 (triangles). (d) Dose-dependent hemolytic activity of NC₁₂-2β₁₂ (stars) and C₁₆-K-β₁₂ (circles) as determined by measuring the absorbances of the supernatants (at 470 nm) after 1 h of incubation with RBCs (10%; 37°C) in PBS. (e) Dose-dependent light-scattering intensities of PBS solutions of NC₁₂-2β₁₂ (stars) and C₁₆-K-β₁₂ (circles). The error bars indicate standard deviations calculated from at least three independent experiments performed in duplicate. Lack of standard deviations indicates consistency.     

Prenatal diagnosis of chylothorax]

Chylothorax is defined as the presence of lymph in the pleural space. Congenital chylothorax is one of the most frequent causes of fetal pleural effusion. It may be primary or secondary. Careful assessment of the etiology and of possible associated anomalies is required. Main complications are pulmonary hypoplasia, hydrops fetalis and the risk of premature delivery. Management is still a mater of controversy, the diagnosis of fetal pulmonary hypoplasia being difficult in utero. Factors such as gestational age, evolution of pleural effusion on two weeks, signs of seriousness (hydrops fetalis), and pulmonary expansion after pleural puncture may help the physician to choose between abstention, pleural tapping or long-term in utero drainage. Post natal treatment consists of pleural drainage and assisted ventilation in cases of respiratory distress, correction of metabolic and immune disorders and exclusive parenteral nutrition. Once chylothorax is resolved, formula feeding without long-chain triglycerides is allowed. If pleural effusion persists despite a well conducted treatment, albumin infusion and diuretics may be used before considering surgical treatment.