Evaluating the use of a portable ultrasound machine to quantify intima-media thickness and flow-mediated dilation: agreement between measurements from two ultrasound machines

Flow-mediated dilation (FMD) and common carotid intima-media thickness (CIMT) are intermediate endpoints for cardiovascular disease. The purpose of this study was to determine whether a portable ultrasound machine was capable of valid measurements of FMD and CIMT compared with a clinic-based machine under similar conditions. Vascular images were taken on 23 apparently healthy young adults with the portable type and clinic type instruments. The analyses revealed a high level of agreement between the two machines for measurements of mean [corrected] CIMT (mean difference [MD] = -0.025 mm, limits of agreement [LOA] = -0.080, 0.029 mm), maximum [corrected] CIMT (MD = 0.001 mm, LOA = -0.065, 0.065 mm) and FMD measures of brachial diameter (baseline MD = 0.199 mm, LOA = -0.210, 0.608 mm, maximum MD = 0.218 mm, LOA = -0.162, 0.597 mm). Reasonable agreement was found for %FMD measurements (MD = 0.27%, LOA = -4.91, 5.44%). The within-machine coefficient of variation results for mean [corrected] CIMT (5.0%), maximum [corrected] CIMT (4.3%), baseline (6.3%) and maximum (5.4%) brachial diameter and %FMD (30.1%) were comparable with normal within-subject variation. We conclude that the portable ultrasound machine can provide measurements of FMD and CIMT that are highly comparable with measurements obtained from a clinic-based machine under similar clinical conditions.     

Syndrome X in 8-y-old Australian children: stronger associations with current body fatness than with infant size or growth

OBJECTIVE: Syndrome X (clustering of insulin resistance, dyslipidaemia and hypertension) in adults with central obesity has been suggested to be a consequence of poor foetal development. We investigated clustering of syndrome X factors in a sample of 8-y-old Australian children, and whether the clusters were associated with size at birth and childhood obesity. DESIGN: Longitudinal, 1997 follow-up of children enrolled as singleton-born neonates in 1989. SUBJECTS: A total of 298 healthy Australian children (208 boys, 90 girls, age range 7.4-8.9 y). MEASUREMENTS: Anthropometry at birth and at 4 weeks. In 1997, at 8 y of age: fasting insulin and glucose, total and HDL-cholesterol, triglycerides and blood pressure. RESULTS: Adverse levels of insulin and glucose, cholesterol and triglycerides co-existed more often than expected by chance (P<0.01). Three factors were identified in factor analysis: one loading on systolic and diastolic blood pressure ('blood pressure'); a second loading on insulin and glucose ('insulin resistance'); and a third loading negatively on HDL-cholesterol and positively on triglycerides ('dyslipidaemia'). The blood pressure factor was correlated with fatness at age 8 y (eg fat mass estimated from skin folds, r=0.11) and, after adjustment for current size, with birth weight (r=-0.15). Fat mass was also correlated with both 'insulin resistance' (r=0.24) and 'dyslipidaemia' (r=0.19). The increase in 'insulin resistance' (P=0.03) and 'dyslipidaemia' (P<0.01) per category of fat mass was greatest for subjects with higher-than-median subscapular-to-triceps ratio of skin folds. Neither 'insulin resistance' nor 'dyslipidaemia' was associated with anthropometry at birth. CONCLUSIONS: The Syndrome X risk variables clustered among children who had a tendency to deposit fat on the trunk. There was no evidence in this sample that infant size predicts development of the insulin resistance or dyslipidaemic components of the syndrome by age 8.     

From the Cover: Imaging intracellular pH in a reef coral and symbiotic anemone

The challenges corals and symbiotic cnidarians face from global environmental change brings new urgency to understanding fundamental elements of their physiology. Intracellular pH (pHi) influences almost all aspects of cellular physiology but has never been described in anthozoans or symbiotic cnidarians, despite its pivotal role in carbon concentration for photosynthesis and calcification. Using confocal microscopy and the pH sensitive probe carboxy SNARF-1, we mapped pHi in short-term light and dark-incubated cells of the reef coral Stylophora pistillata and the symbiotic anemone Anemonia viridis. In all cells isolated from both species, pHi was markedly lower than the surrounding seawater pH of 8.1. In cells that contained symbiotic algae, mean values of pHi were significantly higher in light treated cells than dark treated cells (7.41 ± 0.22 versus 7.13 ± 0.24 for S. pistillata; and 7.29 ± 0.15 versus 7.01 ± 0.27 for A. viridis). In contrast, there was no significant difference in pHi in light and dark treated cells without algal symbionts. Close inspection of the interface between host cytoplasm and algal symbionts revealed a distinct area of lower pH adjacent to the symbionts in both light and dark treated cells, possibly associated with the symbiosome membrane complex. These findings are significant developments for the elucidation of models of inorganic carbon transport for photosynthesis and calcification and also provide a cell imaging procedure for future investigations into how pHi and other fundamental intracellular parameters in corals respond to changes in the external environment such as reductions in seawater pH.     

Screening for ‘window‐period’ acute HIV infection among pregnant women in rural South Africa

Objectives

The aim of this study was to evaluate the HIV‐1 RNA pooled nucleic acid amplification testing (NAAT) strategy to screen pregnant women in the ‘window period’ of acute HIV infection (AHI) in rural South Africa.

Methods

In 2007 and 2008, 750 consecutive pregnant women on their first antenatal care visit to a primary health care clinic were tested anonymously for HIV infection. HIV‐1 RNA pooled NAAT was performed on HIV antibody‐negative samples. All positive pools were tested individually and positive samples were classified as incident cases to calculate HIV incidence.

Results

The overall HIV prevalence was 37.3% [95% confidence interval (CI) 34.3–41.3]. Of the 467 HIV antibody‐negative samples, four (0.9%) were HIV‐1 RNA‐positive. The mean viral load in the four samples was 386 260 HIV‐1 RNA copies/mL (range 64 200–1 228 130). The HIV incidence was 11.2% per year (95% CI 0.3–22.1) and all women with AHI were ≤21 years of age.

Conclusions

Identifying AHI in pregnancy is important for health interventions to reduce perinatal and heterosexual transmission of HIV, and to estimate HIV incidence for epidemiological surveillance.     

Infection of Nippostrongylus brasiliensis induces development of mucosal-type but not connective tissue-type mast cells in genetically mast cell-deficient Ws/Ws rats

Ws/Ws rats have a small deletion at the tyrosine kinase domain of the c- kit gene and are deficient in both mucosal mast cells (MMC) and connective tissue-type mast cells (CTMC). The role of the c-kit receptor in the development of MMC and CTMC was investigated by infecting Ws/Ws and control +/+ rats with Nippostrongylus brasiliensis (NB), which induces T-cell-dependent mast cell proliferation. Although mast cells did not develop in the skin of Ws/Ws rats, a significant number of mast cells developed in the jejunum after NB infection. These mast cells had the MMC protease phenotype (rat mast cell protease [RMCP] I-/II+) and lacked heparin because they were not stained with berberine sulfate. Globule leukocytes were also detected in the mucosal epithelium of these rats. However, the number of MMC and the serum concentration of RMCP II in NB-infected Ws/Ws rats were only 13% and 7% of those of NB-infected +/+ rats, respectively. A small number of mast cells also developed in the lung, liver, and mesenteric lymph nodes of Ws/Ws rats after NB infection. Although mast cells in these tissues had the MMC phenotype throughout the observation period, the increased mast cells in the lung and liver of +/+ rats acquired a CTMC-like phenotype and were RMCP I+/II+, berberine sulfate+, and formalin resistant. These results indicate that the need for the stimulus through the c-kit receptor appears to be greater in the development of CTMC in the skin as well as for CTMC-like mast cells in the lung and liver than for the development of MMC.     

Magnetic resonance angiography

Pulse sequences that permit selective detection of moving spins in a magnetic resonance image have been developed. Experiments were performed by the authors to produce projected angiographic data without the use of contrast agents, with the intensity of each image pixel determined by the macroscopic velocity of the detected spins. With this method, suppression of nonmoving spins is essentially complete, yielding a high dynamic range in signal intensity for detected vessels. Selective detection of moving spins is not dependent on pulsatile flow. Consequently, not only arterial structures, but also venous structures can easily be visualized. High-resolution angiographic images can be obtained by combining the flow experiment with surface coil techniques.     

Recently published papers: Tracheostomy: why rather than when? Obesity: does it matter? And stroke: diagnosis,thrombosis and prognosis

Three studies explore the case for tracheostomies in the intensive care unit (ICU). Tracheostomies appear to have no effect on ICU survival, according to a prospective observational cohort study that used a propensity score. In obese patients, surgical tracheostomies were associated with an increased risk of complications, although these patients appeared to have a lower mortality in the ICU. A third study failed to show that tracheostomies reduced sedation requirements. MRI appears to be the investigation of choice for the diagnosis of acute stroke and thrombolysis is a safe and effective treatment for acute ischaemic strokes. Virtually all patients with a stroke may benefit from ongoing care in a stroke unit.