Automated transfer and injection of hyperpolarized molecules with polarization measurement prior to in vivo NMR

Hyperpolarized magnetic resonance via dissolution dynamic nuclear polarization necessitates the transfer of the hyperpolarized molecules from the polarizer to the imager prior to in vivo measurements. This process leads to unavoidable losses in nuclear polarization, which are difficult to evaluate once the solution has been injected into an animal. We propose a method to measure the polarization of the hyperpolarized molecules inside the imager bore, 3 s following dissolution, at the time of the injection, using a precise quantification of the infusate concentration. This in situ quantification allows for distinguishing between signal modulations related to variations in the nuclear polarization at the time of the injection and signal modulations related to physiological processes such as tissue perfusion. In addition, our method includes a radical scavenging process that leads to a minor reduction in sample concentration and takes place within a couple of seconds following the dissolution in order to minimize the losses due to the presence of paramagnetic polarizing agent in the infusate. We showed that proton exchange between vitamin C, the scavenging molecule and the deuterated solvent shortens the long carboxyl ¹³C longitudinal relaxation time in [1‐¹³C]acetate. This additional source of dipolar relaxation can be avoided by using deuterated ascorbate. Overall, the method allows for a substantial gain in polarization and also leads to an extension of the time window available for in vivo measurements. Copyright © 2013 John Wiley & Sons, Ltd.     

Abnormal electrocardiogram in a patient with amyotrophic lateral sclerosis mimicking myocardial ischaemia

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that almost exclusively involves motor neurons although autonomic dysfunction has also been reported. We present an 84-year-old female with no documented history of heart disease, who was admitted with negative T waves in the electrocardiogram precordial leads mimicking myocardial ischaemia. No other abnormalities were shown in the rest of the cardiologic evaluation, suggesting autonomic nervous system dysfunction. A neurophysiological study demonstrated acute and chronic denervation in multiple muscles with normal nerve conduction studies, confirming ALS diagnosis. Previous studies have shown that subclinical sympathetic hyperfunction and parasympathetic hypofunction might result in cardiovascular dysfunction in ALS patients. It is important to detect disturbances of autonomic cardiac control because this dysfunction may influence survival and quality of life, leading to a decrease in life expectancy in ALS patients. This Case Report may support the impairment of cardiac autonomic control in patients with ALS.     

Differential effects of a unilateral hypothalamic lesion on ovulation and compensatory ovarian hypertrophy in hemiovariectomized adult rats

The effects were analysed of a unilateral lesion in the anterior or medial hypothalamus made on the day of oestrus on right or left hemicastrated rats. On the day of oestrus after two consecutive oestrous cycles of the same length, the ovulation rate in rats with lesions in the anterior left hypothalamus was lower than in control hemicastrated animals (5/16 vs 18/20; P less than 0.01), and normal in those rats with lesions in the right side (14/18). None of the animals with lesions in the left side of the anterior hypothalamus and with the left ovary in situ ovulated (0/7), but 5/9 with the right ovary in situ did ovulate (P less than 0.05). Lesions on either side of the medial hypothalamus did not modify ovulation rate. Compensatory ovulation was reduced in those animals with lesions in the right anterior hypothalamus and with the right ovary in situ. Lesions in either side of the medial hypothalamus reduced compensatory ovulation. Lesions in the right side of the anterior and medial hypothalamus increased compensatory ovarian hypertrophy in the left ovary and decreased it in the right ovary. Lesions in the left side of the anterior hypothalamus increased compensatory ovarian hypertrophy in the left ovary only, whereas lesions in the left side of the medial hypothalamus reduced compensatory ovarian hypertrophy in the right ovary. The results suggest that the information arising in each side of the anterior and medial hypothalamus plays different roles in the ipsi-and contralateral ovary, when either the left or the right ovary is absent.     

A hydrodynamic study of pleural drainage systems: some practical consequences

BACKGROUND: A pleural drainage system must be capable of efficiently evacuating the air or fluids from the pleural cavity so that adequate lung reexpansion can take place. The air flow and negative pressure of the system will depend on the particular design of each model. This experimental study analyzes the specifications and performance of the pleural drainage systems currently on the market. METHODS: Thirteen models of pleural drainage systems connected to wall suction were examined. The models were classified into the following three groups: dry systems; wet systems; and single-chamber systems. We determined the ambient air flow and the negative pressure generated according to the suction level. The components of each model are also described. RESULTS: Under normal conditions, dry (except for the Sentinel Seal; Sherwood Medical; Tullamore, Ireland), wet, and single-chamber systems reach similar air flow rates (17 to 30, 24 to 27, and 22 to 28 L/min, respectively). With higher wall suction levels, wet systems increase the air flow (26 to 49 L/min) but the negative pressure becomes unstable because of the water loss phenomenon, dry systems increase the air flow (29 to 50 L/min) without modifying the regulator pressure, and single-chamber systems also raise the air flow (45 to 51 L/min) but increase the negative pressure. When there is an air leak, dry systems (except for the Sentinel Seal) lose less negative pressure than the other systems. CONCLUSIONS: The functioning of these systems can be optimized only by applying a suitable wall suction level adjusted to each case. Although the three types of systems are capable of evacuating adequate air flow rates, the negative pressure and the capacity to maintain it in the presence of an air leak are different in each system. Being fitted with valves and not water compartments makes the dry systems the safest and the ideal for use when the patient has to be moved.     

Percutaneous endoscopic gastrostomy: high mortality rates in hospitalized patients

OBJECTIVE: Percutaneous endoscopic gastrostomy (PEG) is a widely used method for insertion of a gastrostomy tube in patients who are unable to eat but have a normally functioning gut. Complications have been described, especially in fragile, debilitated patients, and 30-day mortality rates of 4.1-26% have been reported. We assessed the outcome of PEG tube placement for inpatients and outpatients, based on morbidity, mortality, and long-term survival. METHODS: We reviewed the medical records of all patients who underwent PEG at our institution between January 1, 1995 and December 31, 1996. Four groups of patients were compared: Group 1, patients from nursing homes; Group 2, hospitalized patients; Group 3, hospitalized patients matched to Group 2 for diseases, except mental disorder, and not treated with PEG; and Group 4, the general hospital population matched for age. RESULTS: A total of 114 PEG tubes were inserted in 114 patients, 47 from Group 1, 67 from Group 2. Eighty-seven percent of patients in Group 1 underwent PEG because of dementia, versus 46% of Group 2 (p<0.001). The mortality rate was five times higher in Group 2 than in Group 3 (p<0.001). The 30-day mortality was seven times higher in Group 2 than in Group 1, twice that in Group 3, and five times higher than in Group 4 (p = 0.002 and p<0.001, respectively). When intention-to-treat analyses were applied to the data, 19/48 patients died (39.5%) in Group 1, and 60/83 (72.0%) died in Group 2, (p<0.001). CONCLUSIONS: Patients hospitalized with acute illness are at high risk for serious adverse events after PEG insertion and this procedure should be avoided.