Presyncope during progressive hypovolaemia simulated by lower body negative pressure is not prevented by high-dose naloxone

STUDY OBJECTIVE: We set the hypothesis that follow-up surveys of occupational asthma (OA) could now show better improvement in the asthmatic condition because of a more prolonged interval since removal from exposure than in previously reported studies. PATIENTS/METHODS: Ninety-nine subjects with OA were assessed and were separated into two groups according to the duration of cessation of exposure: (1) group removed for > or = 5 years: 48 subjects studied 8.9+/-2.2 years after cessation of exposure; (2) group removed for <5 years: 51 subjects with OA, comparable in terms of history and functional results at time of diagnosis, with a time lapse from last exposure of 3.1+/-1.2 years. On the follow-up visit, questionnaires including information on the current and previous use of inhaled steroids, spirometry, and methacholine tests were administered and results were compared with those obtained at the time of diagnosis. RESULTS: At the follow-up visit, no significant changes in spirometry were observed in the two groups. However, a significant improvement in provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) from a mean value of 1.5 to 3.7 mg/mL was documented (p<0.001). The proportion of subjects having normal PC20 at the follow-up visit was significantly higher in the group removed from exposure for >5 years than in the group removed for < or = 5 years (16/33 vs 8/42; p=0.01). Stepwise logistic regression showed that follow-up PC20 could be predicted from baseline PC20 (p<0.001, odds ratio [OR]=4.1, 95% confidence interval [CI]=1.8 to 9.1), duration of exposure (p=0.04, OR=0.9, 95% CI=0.8 to 1.0), the interval since removal from exposure (p=0.002, OR=1.7, 95% CI=1.2 to 2.5), and the type of agent; subjects with OA due to high-molecular-weight agent showed a less favorable outcome (p=0.04, OR=0.2, 95% CI=0.03 to 1.0). Current and past treatments with inhaled steroids were not significant predictors. CONCLUSION: Results obtained in the group of this study removed for >5 years show better prognostic figures than those reported in most previous studies. Comparison with the group removed for a shorter interval and the stepwise logistic regression analysis suggest that the longer duration of the interval from cessation of exposure appears to be a factor determining this difference.     

7 T renal MRI: challenges and promises

The progression to 7 Tesla (7 T) magnetic resonance imaging (MRI) yields promises of substantial increase in signal-to-noise (SNR) ratio. This increase can be traded off to increase image spatial resolution or to decrease acquisition time. However, renal 7 T MRI remains challenging due to inhomogeneity of the radiofrequency field and due to specific absorption rate (SAR) constraints. A number of studies has been published in the field of renal 7 T imaging. While the focus initially was on anatomic imaging and renal MR angiography, later studies have explored renal functional imaging. Although anatomic imaging remains somewhat limited by inhomogeneous excitation and SAR constraints, functional imaging results are promising. The increased SNR at 7 T has been particularly advantageous for blood oxygen level-dependent and arterial spin labelling MRI, as well as sodium MR imaging, thanks to changes in field-strength-dependent magnetic properties. Here, we provide an overview of the currently available literature on renal 7 T MRI. In addition, we provide a brief overview of challenges and opportunities in renal 7 T MR imaging.     

Validation of multiparametric MRI by histopathology after nephrectomy: a case study

Magnetic Resonance Materials in Physics, Biology and Medicine - Renal multiparametric MRI (mpMRI) is a promising tool to monitor renal allograft health to enable timely treatment of chronic...     

Left ventricular geometric patterns in end‐stage kidney disease: Determinants and course over time

Introduction : While concentric left ventricular hypertrophy (cLVH) predominates in non–dialysis‐dependent chronic kidney disease (CKD), eccentric left ventricular hypertrophy (eLVH) is most prevalent in dialysis‐dependent CKD stage 5 (CKD5D). In these patients, the risk of sudden death is 5× higher than in individuals with cLVH. Currently, it is unknown which factors determine left ventricular (LV) geometry and how it changes over time in CKD5D. Methods : Data from participants of the CONvective TRAnsport Study who underwent serial transthoracic echocardiography were used. Based on left ventricular mass (LVM) and relative wall thickness (RWT), 4 types of left ventricular geometry were distinguished: normal, concentric remodeling, eLVH, and cLVH. Determinants of eLVH were assessed with logistic regression. Left ventricular geometry of patients who died and survived were compared. Long‐term changes in RWT and LVM were evaluated with a linear mixed model. Findings : Three hundred twenty‐two patients (63.1 ± 13.3 years) were included. At baseline, LVH was present in 71% (cLVH: 27%; eLVH: 44%). Prior cardiovascular disease (CVD) was positively associated with eLVH and ß‐blocker use inversely. None of the putative volume parameters showed any relationship with eLVH. Although eLVH was most prevalent in non‐survivors, the distribution of left ventricular geometry did not vary over time. Discussion : The finding that previous CVD was positively associated with eLVH may result from the permanent high cardiac output and the strong tendency for aortic valve calcification in this group of long‐term hemodialysis patients, who suffer generally also from chronic anemia and various other metabolic derangements. No association was found between eLVH and parameters of fluid balance. The distribution of left ventricular geometry did not alter over time. The assumption that LV geometry worsens over time in susceptible individuals, who then suffer from a high risk of dying, may explain these findings.     

Influence of Monoglycerides on the Gelatinization and Enzymatic Breakdown of Wheat and Cassava Starch

The influence of monoglycerides on the flocculation and gelatinization of suspensions of wheat starch and cassava starch was studied. The sedimentation volumes of native and gelatinized starch with and without added monoglycerides were measured and the quantity of bound monoglycerides was determined. The sediments were examined by scanning electron microscopy and the rate of enzymatic breakdown by α-amylase was determined.     

Cold stress provokes sympathoinhibitory presyncope in healthy subjects and hemodialysis patients with low cardiac output

BACKGROUND: Sudden hypotension in progressive hypovolemia or during hemodialysis is attributed to sudden inhibition of sympathetic activity. Critical ventricular underfilling seems responsible for this paradox, but it is unknown why the transition from sympathoactivation accompanying hypovolemia to sympathoinhibition is so abrupt. We studied whether brief fluctuation of sympathetic activity induced by cold pressor test (CPT) evokes sympathoinhibition if applied during low cardiac output. METHODS AND RESULTS: Fourteen healthy subjects underwent CPT, lower-body negative pressure (LBNP; -45 mm Hg for 60 minutes), or the combination thereof. CPT alone caused vasoconstriction and increased muscle sympathetic nerve activity, followed by uneventful relaxation. When applied during reduced cardiac output, tachycardia, and vasoconstriction induced by prior LBNP for 6 minutes, CPT again caused vasoconstriction, now followed by acute hypotension in 10 subjects, and was associated with vasorelaxation, relative bradycardia, and fall in muscle sympathetic nerve activity. Eight subjects also experienced acute LBNP-induced hypotension in the absence of CPT, but not until 17 +/- 6 minutes of LBNP. We also performed CPT before and in the final phase of hemodialysis in 8 patients. Before dialysis, the patients tolerated CPT uneventfully, but during hemodialysis, CPT provoked acute hypotension in 5 cases, showing similar withdrawal of vasoconstriction. CONCLUSIONS: This is the first study showing that brief cold stress, tolerated well in normal circulatory conditions, can provoke sudden sympathoinhibition and hypotension when applied during decreased cardiac output induced by LBNP or hemodialysis. We suggest that during conditions of a decreased cardiac output, subtle sympathetic relaxation such as follows cold stress triggers self-enhancing relaxation that cannot be controlled.     

No change in automatic function tests during uncomplicated haemodialysis

The curricula of tertiary nursing courses usually involve a number of complementary strands. These include biological sciences, social sciences, behavioural sciences, other support subjects and clinical units. These different strands each, to some extent, present the nursing student with a dilemma as they may present entirely different models of the body. Explorations of this dilemma show that students are also being presented with different models of illness and different conceptions of appropriate health care response to illness. The question is then raised as to which of these approaches most accurately reflects the realities of nursing practice.     

Interaction of Monoglycerides with Starches

In bread-making practice, the emulsifier glycerolmonostearate (GMS) is commonly used as an improving agent, though the mechanism of its action is not fully elucidated. Most of earlier studies have been made on starches in molecular solution. The present investigation deals with interactions of the emulsifier (in fact a mixture of glycerolmonostearate and -palmitate) and starches in suspension, at temperatures ranging from 30–90°C. The quantity of monoglycerides bound by the starch was determined by sampling the reaction vessel at time intervals and re-extracting the monoglycerides that were left free in the suspension. Quantitative determination was achieved with the aid of gas-chromatography. It was found that at 30 °C, part of the monoglycerides is irreversibly bound by the starch granules; during gelatinization, the quantity of emulsifier bound shows a considerable increase to reach, at 90 °C, an equilibrium at a higher level. Probably, the monoglyceride molecules penetrate into the swollen starch granules to form an insoluble complex with amylose. Various starches included in the study showed essentially similar behaviour, but were quantitatively different in their capacity to bind monoglyceride. At 30 °C, wheat starch binds a greater part of added monoglycerides than does cassava starch; at 90 °C the situation is the reverse.