Engineering buffer layers to improve temperature resilience of magnetic tunnel junction sensors

Improving the thermal resilience of magnetic tunnel junctions (MTJs) broadens their applicability as sensing devices and is necessary to ensure their operation under harsh environments. In this work, we are address the impact of temperature on the degradation of the magnetic reference in field sensor stacks based on MgO-MTJs. Our study starts by simple MnIr/CoFe bilayers to gather enough insights into the role of critical morphological and magnetic parameters and their impact in the temperature dependent behavior. The exchange bias coupling field (Hex), coercive field (Hc), and blocking temperature (Tb) distribution are tuned, combining tailored growth conditions of the antiferromagnet and different buffer layer materials and stackings. This is achieved by a unique combination of ion beam deposition and magnetron sputtering, without vaccum break. Then, the work then extends beyond bilayers into more complex state-of-the-art MgO MTJ stacks as those employed in commercial sensing applications. We systematically address their characteristic fields, such as the width of the antiferromagnetic coupling plateau ΔH, and study their dependence on temperature. Although, [Ta/CuN] buffers showed higher key performance indications (e.g.Hex) at room temperature in both bilayers and MTJs, [Ta/Ru] buffers showed an overall wider ΔHup to 200 °C, more suitable to push high temperature operations. This result highlights the importance of properly design a suitable buffer layer system and addressing the complete MTJ behavior as function of temperature, to deliver the best stacking design with highest resilience to high temperature environments.

3D Printing of a Graphene-Modified Photopolymer Using Stereolithography for Biomedical Applications: A Study of the Polymerization Reaction

Additive manufacturing is gaining importance thanks to its multiple advantages. Stereolithography (SLA) shows the highest accuracy and the lowest anisotropy, which has facilitated the emergence of new applications as dentistry or tissue engineering. However, the availability of commercial photopolymers is still limited, and there is an increasing interest in developing resins with properties adapted for these new applications. The addition of graphene-based nanomaterials (GBN) may provide interesting advantages, such as improved mechanical properties and bioactivity. However, there is a lack of knowledge regarding the effect of GBNs on the polymerization reaction. A photopolymerizable acrylic resin has been used, and the effect of the addition of 0.1wt% of graphene (G); graphene oxide (GO) and graphite nanoplatelets (GoxNP) on printability and polymerization have been investigated. It was observed that the effect depended on GBN type, functionalization and structure (e.g., number of layers, size, and morphology) due to differences in the extent of dispersion and light absorbance. The obtained results showed that GO and GoxNP did not significantly affect the printability and quality of the final structure, whilst the application of G exhibited a negative effect in terms of printability due to a reduction in the polymerization degree. GO and GoxNP-loaded resins showed a great potential to be used for manufacturing structures by SLA.

Graphene Oxide and Graphene Reinforced PMMA Bone Cements: Evaluation of Thermal Properties and Biocompatibility

The incorporation of well-dispersed graphene oxide (GO) and graphene (G) has been demonstrated as a promising solution to improve the mechanical performance of polymethyl methacrylate (PMMA) bone cements in an attempt to enhance the long-term survival of the cemented orthopaedic implants. However, to move forward with the clinical application of graphene-based PMMA bone cements, it is necessary to ensure the incorporation of graphene-based powders do not negatively affect other fundamental properties (e.g., thermal properties and biocompatibility), which may compromise the clinical success of the implant. In this study, the effect of incorporating GO and G on thermal properties, biocompatibility, and antimicrobial activity of PMMA bone cement was investigated. Differential scanning calorimetry studies demonstrated that the extent of the polymerisation reaction, heat generation, thermal conductivity, or glass transition temperature were not significantly (p > 0.05) affected by the addition of the GO or G powders. The cell viability showed no significant difference (p > 0.05) in viability when MC3-T3 cells were exposed to the surface of G- or GO-PMMA bone cements in comparison to the control. In conclusion, this study demonstrated the incorporation of GO or G powder did not significantly influence the thermal properties or biocompatibility of PMMA bone cements, potentially allowing its clinical progression.

Magnetic tunnel junctions with integrated thermometers for magnetothermopower measurements

Magnetic tunnel junction (MTJ) micropillars were fabricated with integrated thermometers and a heater line (HL) for thermovoltage measurements. This novel thermometer configuration enabled a direct measurement of ΔT across the MTJ micropillar. The MTJ devices were patterned from a CoFeB/MgO/CoFeB stack, with a 1.2 nm to 1.6 nm MgO wedge across the wafer, resulting in resistance area products in the range of 0.7 kΩ · µm²  <  R  ×  A  <  55 kΩ · µm². This allowed the measurement of thermoelectric properties as a function of the tunnel barrier thickness. The thermometers showed a homogeneous heating behavior for all devices across the wafer. Combining the in-stack temperature measurements and finite element simulations the thermal profile across the MTJ structure and the thermopower were estimated with a noticeable improvement of the measurement accuracy. The studied MTJ structures showed tunneling magnetoresistance (TMR) ratios up to 125%, and tunneling magnetothermopower (TMTP) up to 35%.

Femtosecond control of electric currents in metallic ferromagnetic heterostructures

The idea to use not only the charge but also the spin of electrons in the operation of electronic devices has led to the development of spintronics, causing a revolution in how information is stored and processed. A novel advancement would be to develop ultrafast spintronics using femtosecond laser pulses. Employing terahertz (10(12) Hz) emission spectroscopy and exploiting the spin-orbit interaction, we demonstrate the optical generation of electric photocurrents in metallic ferromagnetic heterostructures at the femtosecond timescale. The direction of the photocurrent is controlled by the helicity of the circularly polarized light. These results open up new opportunities for realizing spintronics in the unprecedented terahertz regime and provide new insights in all-optical control of magnetism.

Mechanical and thermal behaviour of an acrylic bone cement modified with a triblock copolymer

The basic formulation of an acrylic bone cement has been modified by the addition of a block copolymer, Nanostrength(®) (NS), in order to augment the mechanical properties and particularly the fracture toughness of the bone cement. Two grades of NS at different levels of loading, between 1 and 10 wt.%, have been used. Mechanical tests were conducted to study the behaviour of the modified cements; specific tests measured the bend, compression and fracture toughness properties. The failure mode of the fracture test specimens was analysed using scanning electron microscopy (SEM). The effect of NS addition on the thermal properties was also determined, and the polymerisation reaction using differential scanning calorimetry. It was observed that the addition of NS produced an improvement in the fracture toughness and ductility of the cement, which could have a positive contribution by reducing the premature fracture of the cement mantle. The residual monomer content was reduced when the NS was added. However this also produced an increase in the maximum temperature and the heat delivered during the polymerisation of the cement.

[Influence of the physiological medium on the mechanical properties of bone cement: can current studies be extrapolated?]

PURPOSE

The use of bone cement is widespread in orthopaedic surgery. Most of the mechanical tests are performed in dry medium, making it difficult to extrapolate the results. The objective of this study is to assess if the mechanical properties of polymethylmethacrylate (PMMA), obtained in previous reports, are still present in a liquid medium.

MATERIAL AND METHOD

An experimental study was designed with antibiotic (vancomycin) loaded PMMA. Four groups were defined according to the medium (dry or liquid) and the pre-conditioning in liquid medium (one week or one month). Wear and flexural strength tests were performed according to ASTM and ISO standards. Volumetric wear, friction coefficient, tensile strength, and Young's modulus were analyzed. All samples were examined by scanning electron microscopy.

RESULTS

The samples tested in liquid medium showed lower wear and flexural strength values (P<.05). The kind of wear was modified from abrasive to adhesive in those samples studied in liquid medium. The samples with a pre-conditioning time showed lower values of wear (P<.05).

CONCLUSIONS

Caution is recommended when extrapolating the results of previous PMMA results. The different mechanical strength of the cement in a liquid medium, observed in saline medium, is much closer to the clinical situation.

Augmentation cystoplasty in children without preoperative mechanical bowel preparation

OBJECTIVE

To retrospectively assess early postoperative complications in augmentation cystoplasty without preoperative mechanical bowel preparation (MBP).

MATERIAL AND METHODS

Between May 1987 and May 2006, 162 cystoplasties were performed in 158 children. The segments used were: sigmoid colon (81.5%), ileum (13%), and ileocecum (5.5%). The mean age was 8.65 years (range 2.1-22.7 years). No preoperative MBP of any kind was used in any of the patients and all of them received antibiotics preoperatively and postoperatively.

RESULTS

No intraoperative complications related to the procedure were reported. The mean hospital stay was 9.48 days (range 4-30 days). The mean time to intake of oral fluids was 94.77 h (range 48-288 h). Postoperative complications occurred in 9.87%: urinary fistula was the most common (2.4%); only 3 patients presented wound infection (1.85%); 5 patients required reoperative surgery (hemoperitoneum, patch necrosis and 3 cases of urinary peritonitis); 1 patient presented an intra-abdominal abscess that resolved with antibiotic treatment.

CONCLUSIONS

Preoperative MBP can be omitted in children that require augmentation cystoplasty without an increased risk of infectious or anastomotic complications. Further prospective, randomized clinical trials should be carried out in order to validate our findings in the pediatric population.

[Botulinic toxin type A in the treatment of children with neurogenic bladder]

INTRODUCTION. Botulinum toxin A (BoNTA) is an alternative in children with neurogenic bladder refractory to anticholinergics. OBJECTIVE. To evaluate the initial effects of BoNTA in neurogenic bladders. PATIENTS AND METHODS 12 patients (9 myelomeningoceles, 1 tethered cord, 1 medullary astrocytoma, 1 Ewing's sarcoma) were studied. The pretreatment evaluation included: voiding diary, incontinence score, renovesical ultrasound, cystourethrography and urodynamic parameters. Patients received 300 UI of BoNTA via detrusor injections. They were re-evaluated at months 1, 3 and 6. After the third control, if improvement was confirmed, patients were injected again. Otherwise, surgery was indicated.

RESULTS

After the initial injection, 50% of patients achieved complete continence and 20% remained with minimal leaks. The mean maximum bladder capacity increased from 264 +/- 117 ml to 324 +/- 170 ml (P = 0.322). The mean detrusor pressure decreased from 46 +/- 17 cm H2O to 42 +/- 14 cm H2O (P=0.596). The mean bladder compliance increased from 7.6 +/- 5.9 ml/cm H2O to 10.4 +/- 6.4 ml/cm H2O (P = 0.290). The reflex voiding contractions disappeared in 2 patients; 8 presented trabeculae. Ten patients were reinjected and two underwent surgery.

CONCLUSION

70% urinary continence was achieved after the initial injection. No significant urodynamic changes were observed. A longer follow-up with subsequent injections is needed.

Control of magnetization reversal by combining shape and magnetocrystalline anisotropy in epitaxial Fe planar nanowires

This work presents an analysis of the in-plane magnetization reversal mechanisms of Fe nanowires, with widths from 100 nm to 1 microm, fabricated in epitaxial Au(001)/Fe(001)/MgO(001) thin films by means of focused ion and electron beam lithographies, with either positive or negative resist. The experimental results show that the switching mechanisms and hysteresis are almost exclusively functions of the dimensions of the wires and of the Fe intrinsic properties, with minor influence of the specific fabrication route employed upon optimization of nanostructure parameters in terms of crystallinity and morphology, and well defined and reproducible geometry. The reversal processes evolve from wall pinning at low angles between the applied field and the axis of the wires to basically uniform magnetization rotation at high angles. This behaviour can be described in terms of single spin configurations, thus ruling out the formation of multidomain structures even at high angles. The ability to achieve these high quality and well controlled nanowires allowed us to develop an analytical model, based on uniform magnetization configurations considering just the intrinsic Fe properties and the shape and dimensions of the wires. This simple approach provides a very good qualitative and quantitative agreement with the experimental results, thus evidencing the relatively small role of other extrinsic factors in the magnetization processes.

Coupling between magnetic and optical properties of stable Au-Fe solid solution nanoparticles

Au-Fe nanoparticles constitute one of the simplest prototypes of a multifunctional nanomaterial that can exhibit both magnetic and optical (plasmonic) properties. This solid solution, not feasible in the bulk phase diagram in thermal equilibrium, can be formed as a nanostructure by out-of-equilibrium processes. Here, the novel magnetic, optical and magneto-optical properties of ion-implanted Au-Fe solid solution nanoparticles dispersed in a SiO(2) matrix are investigated and correlated. The surface plasmon resonance of the Au-Fe nanoparticles with almost equicomposition is strongly damped when compared to pure Au and to Au-rich Au-Fe nanoparticles. In all cases, the Au atoms are magnetically polarized, as measured by x-ray magnetic circular dichroism, and ferromagnetically coupled with Fe atoms. Although the chemical stability of Au-Fe nanoparticles is larger than that of Fe nanoparticles, both the magnetic moment per Fe atom and the order temperature are smaller. These results suggest that electronic and magnetic properties are more influenced by the hybridization of the electronic bands in the Au-Fe solid solution than by size effects. On the other hand, the magneto-optical transitions allowed in the vis-nIR spectral regions are very similar. In addition, we also observe, after studying the properties of thermally treated samples, that the Au-Fe alloy is stabilized, not by surface effects, but by the combination of the out-of-equilibrium nature of the ion implantation technique and by changes in the properties due to size effects.

Climate change and the emergence of Vibrio vulnificus disease in Israel

In 1996, a major unexplained outbreak of systemic Vibrio vulnificus infection erupted among Israeli fish market workers. The origins of this emergent infectious disease have not been fully understood. A possible link between climate change and disease emergence is being investigated. Meteorological service data from 1981, the earliest detection and reporting of V. vulnificus for the time in Israel, to 1998 for two stations located within the main inland fish farm industry were analyzed. The 1996-1998 summers were identified as the hottest ever recorded in Israel in the previous 40 years. Time series of monthly minimum, maximum, and mean temperatures showed significant increase in the summer temperatures along the 18 years. The highest minimum temperature value was recorded in summer 1996. Lag correlation analysis revealed significant correlations between temperature values and hospital admission dates. The eruption appeared 25-30 days after the extreme heat conditions in summer 1996, at a lag of 3 weeks in summer 1997 while the results for 1998 were at a lag of less than a week. Higher significant results were detected for the daily minimum temperatures in summer 1996 compatible with the disease eruption. These findings suggest that high water temperature might have impacted the ecology of our study area and caused the emergence of the disease, as an effect of global climate change.

Multifunctional roles of lactoferrin: a critical overview

Lactoferrin (LF) is a member of the transferrin family that is expressed and secreted by glandular epithelial cells and is found in the secondary granules of neutrophils. Originally viewed as an iron-binding protein in milk, with bacteriostatic properties, it is becoming increasingly evident that LF is a multifunctional protein to which several physiological roles have been attributed. These include regulation of iron homeostasis, host defense against a broad range of microbial infections, anti-inflammatory activity, regulation of cellular growth and differentiation and protection against cancer development and metastasis. While iron binding is likely central to some of the biological roles of LF, other activities, including specific interactions with mammalian receptors and microbial components, also contribute to the pleoitropic functional nature of this protein. In this article, recent advances in the understanding of these functions at the cellular and molecular level are discussed.

Breathing patterns in term infants delivered by caesarean section

AIM

To compare the breathing patterns of infants born by elective caesarean section to those infants delivered by caesarean section after a failed trial of labour.

METHODS

Healthy term infants born by caesarean section were studied. The study group (n = 13) had no trial of labour, whereas infants in the control group (n = 13) failed a trial of labour. Polysomnographic study was performed at 36 h of age. Heart and respiratory rate, type and duration of apnoeas, arterial oxygen saturation and lower limb movements were analysed.

RESULTS

Term infants born by elective caesarean section had a shorter duration of pregnancy and weighed less. Their heart rate was faster, they had more mixed apnoeas, and during quiet sleep they had more central apnoeas of longer duration.

CONCLUSION

Cardiorespiratory patterns in infants delivered by elective caesarean section are different from those delivered by caesarean section after a failed trial of labour.

Incidence of immunoglobulin G antibodies to Chlamydia pneumoniae in acute myocardial infarction patients

BACKGROUND

Recent studies have suggested a possible association between Chlamydia pneumoniae infection and coronary heart disease.

OBJECTIVES

To determine titers of antibodies to C. pneumoniae in patients with acute myocardial infarction compared with titers in several control groups.

METHODS

This prospective case-control study investigated 209 individuals. We assessed the serum IgG antibody titers to C. pneumoniae in 57 consecutive patients admitted with AMI to our intensive coronary care unit during a 4 month period. A serum sample was drawn upon admission and after 6 weeks. Results were compared with those of four control groups: a) patients admitted with community-acquired pneumonia (n = 18), b) patients with community-acquired urinary tract infection (n = 42), c) patients with angiographically normal coronary artery disease (n = 44), and d) patients with stable coronary artery disease (n = 48). Serum immunoglobulin G antibody titers to C. pneumoniae were determined using standard micro-immunofluorescence technology.

RESULTS

Of 57 patients with AMI, 32 (56%) had a high IgG titer to C. pneumoniae (> or = 1:256) on the initial test, which remained unchanged (62%) after 6 weeks. The percentage of patients with high titers was significantly lower in the control groups: 5 of 18 patients (28%) in the pneumonia group (P < 0.01), 11 of 42 (26%) in the urinary tract infection group (P < 0.01), 11 of 44 (25%) with normal coronary arteries (P < 0.01), and 17 of 48 (35%) with stable chronic ischemic heart disease (P < 0.05).

CONCLUSION

The detection of high titers of IgG antibodies to C. pneumonia in many patients with AMI, compared to control groups, suggests that chronic Chlamydia pneumoniae infection plays a role in the pathogenesis of atherosclerosis and acute ischemic events.

Interaction between smoking and the Sstl polymorphism of the apo C-III gene determines plasma lipid response to diet

BACKGROUND

It has recently been demonstrated that the lipid profile of smokers improves if they follow a Mediterranean diet.

AIM

To establish whether the Sstl polymorphism of the apo C-III gene interacts with smoking and determines the lipid response to diet in healthy subjects.

METHODS AND RESULTS

Fifty-nine volunteers (18 smokers: 8 with the S1S1 genotype, and 10 with the S2 allele; 41 non-smokers: 29 with the S1S1 genotype and 12 with the S1S2 genotype) consecutively followed three different diets: a diet enriched in saturated fatty acids (SFA) (38% fat, 20% SFA) followed by a randomised, cross-over period during which they ate a diet enriched in carbohydrates (NCEP-1) (30% fat, 10% SFA, 55% carbohydrates) and a diet enriched in monounsaturated fatty acids (MUFA) (8% fat, 22% MUFA). Cholesterol, triacylglycerol, LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) levels were measured at the end of each dietary period. The smokers carrying the S1S1 genotype were not influenced by any of the diets, but the atherogenic ratio decreased in the carriers of the S2 allele when they changed from the diet rich in SFA to a diet rich in olive oil or carbohydrates (p < 0.039). No significant difference was observed when the non-smoking carriers of the S2 allele changed from one diet to another, but there was a decrease in the LDL-C/HDL-C ratio when the subjects with the S1S1 genotype changed from the saturated diet to either of the other diets (p < 0.001).

CONCLUSIONS

Smoking interacts with the apo CM polymorphism and determines the level of lipid response to dietary changes.

The apolipoprotein A-IV-360His polymorphism determines the dietary fat clearance in normal subjects

Apolipoprotein IV (apo A-IV) has been related to fat absorption and to the activation of some of the enzymes involved in lipid metabolism. Several polymorphic sites within the gene locus for apo A-IV have been detected. Previous studies have shown that the A-IV-2 isoform produces a different plasma lipid response after the consumption of diets with different fat and cholesterol content. The present study was designed to evaluate whether the apo A-IV 360His polymorphism could explain, at least in part, the interindividual variability observed during postprandial lipemia. Fifty-one healthy male volunteers (42 homozygous for the apo A-IV 360Gln allele (Gln/Gln) and nine carriers of the A-IV-360His allele), homozygous for the apo E3 allele, were subjected to a vitamin A-fat load test consisting of 1 g of fat/kg body weight and 60000 IU of vitamin A. Blood was drawn at time 0 and every hour for 11 h. Plasma cholesterol (C), triacylglycerol (TG), and C, TG, apo B-100, apo B-48, apo A-IV and retinyl palmitate (RP) were determined in lipoprotein fractions. Data of postprandial lipemia revealed that subjects with the apo A-IV 360His allele had significantly greater postprandial levels in small triacylglycerol rich lipoproteins (TRL)-C (P<0.02), small TRL-TG (P<0.01) and large TRL-TG (P<0.05) than apo A-IV 360Gln/Gln subjects. In conclusion, the modifications observed in postprandial lipoprotein metabolism in subjects with the A-IV 360His allele could be involved in the different low density lipoprotein (LDL)-C responses observed in these subjects following a diet rich in cholesterol and saturated fats.

[Mediterranean diet improves low density lipoprotein susceptibility to oxidative modifications]

Most experts, specially from Anglo-Saxon countries, recommend a low fat diet in order to prevent cardiovascular diseases. However, mortality rate by ischemic cardiopathy is low in Mediterranean countries, probably because of the consumption of a Mediterranean diet, with a high level of monounsaturated fats provided by the olive oil. We have conducted this study in order to investigate the possible influence of this kind of diet on the oxidation of LDL in vitro, the key element for the development of atherosclerosis.

PATIENTS AND METHODS

41 healthy male subjects were submitted to three consecutive 4-week diets. The first was a saturated fat-rich diet (SAT diet, 38% fat, 20% saturated). This was followed by a low fat diet (NCEP-I, 28% fat, 10% saturated) and after that a Mediterranean diet (38% fat, 22% monounsaturated fat). Plasma levels of total cholesterol, LDL-c, HDL-c, triglycerides, apolipoproteins A-I and B, -tocopherol, and the in vitro susceptibility to oxidation of LDL particles. Both hypolipidemic diets produced a significant decrease in total cholesterol, LDL-c, and apo-B plasma levels. However, it was only the NCEP-I diet that revealed a decrease in the HDL-c. The shift from a saturated fat-rich diet, or a diet rich in carbohydrates, to a Mediterranean diet increased the resistance of LDL particles to oxidation increasing the lag time period (p < 0.038), and decreasing (p < 0.001) the progression rate of the curve of oxidation of LDL. Our results point out two positive consequences of the consumption of a Mediterranean diet by healthy young males, compared with the low fat diet recommended by most Anglo-Saxon experts. On the one hand, the Mediterranean diet increases HDL-c plasma levels, and on the other hand, it decreases the susceptibility of LDL to oxidation. This is why the Mediterranean diet must be recommended in order to prevent cardiovascular diseases.

The effect of apolipoprotein B xbaI polymorphism on plasma lipid response to dietary fat

BACKGROUND AND AIMS

Lipid response to dietary fat and cholesterol is, to a large extent, genetically controlled. Apolipoprotein B (apo B) plays a dominant role in cholesterol homeostasis. Several polymorphic sites within or adjacent to the gene locus for apo B have been detected. The X+ allele of the XbaI restriction fragment polymorphism of the apo B gene has been found to be associated with higher serum cholesterol and/or triglyceride levels. In order to study the influence of this mutation on the plasma lipid response in diets of varying fat content, 72 healthy male subjects were studied, 21 X- X- (X-) and 51 X+ (X+ X- or X+ X+).

METHODS AND RESULTS

These subjects followed three consecutive 28-day diet periods: one rich in saturated fats (SAT diet; 38% fat, 20% saturated); a National Cholesterol Education Program type I diet (NCEP-I diet) (28% fats, < 10% saturated); and a third monounsaturated (MUFA diet) (38% fats, 22% monounsaturated). The different genotypes can be observed to have significant effects on total and LDL cholesterol concentrations (P < 0.017). X+ individuals had higher levels of total and LDL cholesterol after the consumption of a SAT diet (P < 0.012; P < 0.006, respectively), NCEP diet (P < 0.060; P < 0.054, respectively) and MUFA diet (P < 0.022; P < 0.042, respectively) in comparison with X- individuals. A significant interaction between genotypes and dietary effects was observed for diet-induced changes in plasma triglycerides (P < 0.032). Significant decreases in the absolute values of triglyceride concentrations (-0.18 mmol L(-1), P < 0.024) were noted in the X- subjects after the high intake of a MUFA diet, while no significant differences were observed in the X+ individuals (0.006 mmol L(-1), P < 0.858).

CONCLUSIONS

Our results suggest that the total triglyceride response to diet is influenced by the apo B XbaI polymorphism.

Low-fat and high-monounsaturated fatty acid diets decrease plasma cholesterol ester transfer protein concentrations in young, healthy, normolipemic men

BACKGROUND

Cholesterol ester transfer protein (CETP) mediates the transfer of cholesteryl esters from HDL to apolipoprotein (apo) B-containing lipoproteins. The possible atherogenic role of this protein is controversial. Diet may influence plasma CETP concentrations.

OBJECTIVE

The objective was to determine whether the changes in plasma lipids observed after consumption of 2 lipid-lowering diets are associated with changes in plasma CETP concentrations.

DESIGN

: We studied 41 healthy, normolipidemic men over 3 consecutive 4-wk dietary periods: a saturated fatty acid-rich diet (SFA diet: 38% fat, 20% saturated fat), a National Cholesterol Education Program Step I diet (NCEP Step I diet: 28% fat, 10% saturated fat), and a monounsaturated fatty acid-rich diet (MUFA diet: 38% fat, 22% monounsaturated fat). Cholesterol content (27.5 mg/MJ) was kept constant during the 3 periods. Plasma concentrations of total, LDL, and HDL cholesterol; triacylglycerol; apo A-I and B; and CETP were measured at the end of each dietary period.

RESULTS

Compared with the SFA diet, both lipid-lowering diets significantly decreased plasma total and LDL cholesterol, apo B, and CETP. Only the NCEP Step I diet lowered plasma HDL cholesterol. Positive, significant correlations were found between plasma CETP and total (r = 0.3868, P < 0.0001) and LDL (r = 0.4454, P < 0.0001) cholesterol and also between changes in CETP concentrations and those of total (r = 0.4543, P < 0.0001) and LDL (r = 0.4554, P < 0.0001) cholesterol.

CONCLUSIONS

The isoenergetic substitution of a high-saturated fatty acid diet with an NCEP Step I or a high-monounsaturated fatty acid diet decreases plasma CETP concentrations.

[Monitoring patients on mechanical ventilation]

The clinical situation of a patient with acute respiratory failure, indicates the level of care and mechanical ventilatory support required. The aims of mechanical ventilation are to correct hypoventilation, improve oxygenation and oxygen transport and reduce the work of breathing. Nursing care of patients under mechanical ventilation varies according to their state and the ventilation mode. When establishing a care plan, nurses identify the objectives, which will be useful to measure the interventions. These interventions include aspects related to monitoring and indicate whether or not the objectives are met. In this article the items that allow monitoring of a patient under mechanical ventilation grouped into general monitoring and respiratory monitoring are reviewed.

Ten-year follow-up study of hepatitis B virus infection and vaccination status in hospital employees

We sought to determine the incidence of infection with hepatitis B virus (HBV) amongst hospital employees over a 10-year period and to assess the extent and efficacy of vaccination against HBV in this population. In 1984 a cohort of 301 hospital employees was tested for hepatitis B surface antibody (anti HBs), hepatitis B core antibody (anti HBc), and hepatitis B surface antigen (HBsAg). Ten years later, 160 (53%) of these workers remained at the hospital and were re-tested. In addition, they were tested for hepatitis C virus antibody (anti HCV). Records of the hospital vaccination program were inspected to determine the rate and effectiveness of vaccination in these workers. Over the ten year period two of the 160 retested workers (1.25%) had sero-converted to anti HBc positive, yielding an incidence density of 0.27 cases per 100 person-years exposed in unvaccinated workers. While the overall seroprevalence of anti HBc did not change significantly between 1984 (81/301, 27%) and 1994 (39/160, 24%), it was much greater than that of the general population (10%). A significantly greater percentage of Jews of Sephardi ancestry (22/65, 34%) were positive for anti HBc than those of Ashkenazi ancestry (15/90, 17%, P < 0.05). In addition, doctors were found to be less likely to be anti HBc positive than nurses (4% vs. 25%, respectively, P < 0.01). Two cases of anti HCV positivity were discovered yielding a prevalence of 1.25% in the 1994 cohort as compared to 0.15% in the population of healthy blood donors. Of the 93 employees of the 1994 cohort eligible for vaccination (i.e., anti HBc-negative and employed in an occupation involving potential exposure to HBV), 53 (57%) had received vaccination and showed protective antibody titers (anti HBs > or = 10 i.u./ml). 17/52 workers with documented vaccinations (33%) did not have detectable antibody levels one to eight years after vaccination. In conclusion, the seroprevalence of anti HBc and anti HCV is significantly higher in this cohort of hospital employees than in the general population. The relatively low vaccination rate among at-risk personnel emphasizes the need for more effective vaccination programs.

[Numerical analysis of western blot digitalized images. The case of HIV]

The present work explores the use of image digitalization of western blot (WB) aiming to extract more information about the humoral immune response of human immunodeficiency virus (HIV) infected individuals, and to analyze obtained data in a multivariate manner. The digitalization and analysis of WB images was performed on 115 sera. Images were analyzed either qualitatively: dendogram and principal component analysis (PCA) or quantitatively: PCA of the total bands, taking either the antigens, which belong to the virus, or only those which do not. Results show the feasibility of mechanical diagnosis of a large number of WB images. The dendogram and the qualitative PCA satisfactorily separated white images, images with less than four bands, and images with more complex patterns. Quantitative analysis, which keeps more information, separated the images of negative, undetermined and positive diagnosis quite precisely. It was also found that the positive images with complex patterns of antigen recognition correlate better with asymptomatic individuals. Image analysis also revealed various other bands in WB which do not seem to correspond to viral proteins and could represent autoantigens or crossed antigens between HIV and humans which may cause autoimmunity. Digital analysis of WB images is thus demonstrated to be of great usefulness in the diagnosis and of potential great interest in following the evolution and exploring the pathogenesis of AIDS.

Cytomegalovirus infection and disease in the Jerusalem area

We studied the epidemiology of cytomegalovirus (CMV) infection in women and neonates in the Jerusalem area. During the 6-month period from January to June 1982, we recorded the presence of antibody to CMV in pregnant and parturient Jewish and Arab women from West and East Jerusalem, respectively, in 18- to 22-year-old female students at a religious college, in female university students, in 18- to 22-year-old student nurses, and in the nursing staff of the Neonatal Intensive Care Unit in our hospital. In the 18- to 22-year-old age-group, the religious college students not working in a medical setting had the lowest rate of seropositivity. No difference in the rate of CMV infection was found between Jewish and Arab parturient women. In five cases of congenital CMV infection, representing different clinical aspects of the disease, a comparative study of diagnostic procedures for congenital CMV infection was performed.

Surveillance of congenital rubella and the immunity status to rubella in the Jerusalem area

A retrospective study on the incidence of congenital rubella (CR) in the past 10 years in the Jerusalem area was conducted. After the 1972 epidemic, which resulted in 48 cases of congenital rubella, few sporadic cases of CR appeared each year, and in the 1978-79 period the number of CR cases was relatively small. Immunity to rubella in different categories of population (children 3 months to 18 years, college students, nurses in pediatric, newborn and intensive care units, student nurses, and women of childbearing age) was determined by hemolysis in gel (HIG) and hemagglutination inhibition (HI) methods. Susceptibility was defined as an absence of antibody at a dilution of 1:16 in HI, and hemolysis of less than 7 mm in the HIG test. Compared with previous studies on the incidence of antibodies to rubella in women of childbearing age, a mild decrease in the percentage of sero-negative women was found.