Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Krypton”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,459 records · Page 81Linked to original sources
PubMed1989

Evaluation of oesophageal transit in patients with minor peptic oesophagitis.

Fifty-one adult patients with complaints suggesting peptic oesophagitis were submitted within the same week to a radionuclide swallow test (OT), an endoscopy and a manometry in order to evaluate the incidence of oesophageal peristaltic abnormalities in patients with only minor peptic oesophagitis. In all patients with normal endoscopy, OT did not show any transit abnormality. In the patients with slight (Stage I) or moderate (Stage II) oesophagitis, OT was abnormal in 60% of the cases. The results were at least as good as those obtained by means of manometry and suggest that OT is an accurate method for the detection of slight impairment of oesophageal contractility.

Adult↗
PubMed1991

Oesophageal involvement in rheumatoid arthritis patients: a study with oesophageal radionuclide transit using 81Krm.

Rheumatoid arthritis (RA) is an inflammatory disease affecting mainly the joints. In addition, signs of systemic disease are likely to be present although they are not always clinically evident. Oesophageal motility dysfunction, present in 75% of progressive systemic sclerosis patients, was also reported in various other connective tissue diseases. The present study involved 32 rheumatic patients devoid of any gastrointestinal complaints or diseases: 16 RA, nine Raynaud's syndrome and seven mild osteoarthritis as controls. Oesophageal transit was assessed by using 81Krm radionuclide scan, a sensitive and non-invasive technique. Diffusing lung capacity for carbon monoxide (DLCO) was performed as evidence of subclinical systemic involvement. Abnormal oesophageal transit was observed in 5/16 RA (31%). Two of them were subsequently discarded due to the presence of asymptomatic goiter and asymptomatic gastrointestinal reflux leaving 3/14 RA for analysis. They all had extra-articular features (EAF) (pericarditis, nodules) and two of them had diminished DLCO. Two with Raynaud's syndrome had abnormal oesophageal transit but none of the controls had abnormal oesophageal transit. Upper gastrointestinal dysfunction after exclusion of symptomatic patients appears thus to be not very frequent in RA, even when a sensitive technique is used. Radionuclide transit scanning of the oesophagus is not a more useful method than others in detecting early EAF in RA.

Adult↗
PubMed1992

Dosimetry assessment of 81Krm peripheral venous infusion studies.

Calculation of S factors for 81Krm for a full range of target organs from each source organ relevant in 81Krm peripheral venous infusion imaging has been performed. Typical equilibrium activities in the source organs have been measured using quantitative planar gamma camera imaging for a generator with a mean activity at imaging time of 468 MBq eluted at 10 ml min-1. Based on the above measurements and assuming a 10 min infusion period, the mean effective dose equivalent for 81Krm infusion imaging in the assessment of right heart function in adults was found to be 0.365 mSv.

Humans↗
PubMed1993

Right ventricular function at rest and during submaximal exercise assessed by 81Krm equilibrium ventriculography in normal subjects.

81Krm equilibrium ventriculography was used to study right ventricular function in 37 healthy male volunteers. 'Anatomical' lung subtraction using 99Tcm lung perfusion scintigraphy was compared with conventional background correction in the calculation of resting right ventricular ejection fraction (RVEF). Resting RVEF was significantly greater following 'anatomical' lung subtraction than that using background correction (0.59 +/- 0.06 versus 0.55 +/- 0.05). The exercise response of the normal right ventricle was defined in 23 subjects during exercise. Right ventricular ejection fraction showed a progressive increase during graded submaximal exercise (0.55 +/- 0.05 at rest, 0.60 +/- 0.05 at 50 W and 0.66 +/- 0.05 at 100 W). Right heart 81Krm equilibrium ventriculography is well suited to the evaluation of right ventricular function at rest and during exercise. The absolute value of RVEF will however be dependent upon the method of image analysis.

Adult↗
PubMed1993

The limitations of posterior view ventilation scanning in the diagnosis of pulmonary embolism.

In the diagnosis of pulmonary embolism some centres using 133Xe for comparison with multiple view 99Tcm perfusion images perform only single-breath posterior view ventilation scans. The purpose of this study was to test the reliability of the posterior view ventilation scan in the detection of lobar and segmental defects in ventilation. Occluding balloon catheters were placed in lobar and segmental bronchi during fibreoptic bronchoscopy to produce defects of known anatomical location and size in normal volunteers. Subjects breathed 81Krm/air during the occlusions and images were acquired in the posterior, posterior/oblique and lateral projections. The posterior view images were classified by three experienced nuclear medicine physicians as normal or abnormal. If abnormal, the observers were asked to state which lobe or segment was involved. Segmental defects were missed in 28% of scan readings. Segmental defects were detected but incorrectly sited in 50% of readings and correctly sited in only 22% of readings. The posterior view scan with a defect involving the entire lingula was judged to be normal by all observers. Defects involving the right and left lower lobes were underestimated. We conclude that ventilation scanning techniques that assess the distribution of ventilation in the posterior view alone are unreliable in the detection of segmental and lobar defects, and are likely to increase the false positive rate in the diagnosis of pulmonary embolism.

Administration, Inhalation↗
PubMed2000

Post-synchronization of dynamic images of periodically moving organs.

The motion of periodically moving organs can be studied by acquisition of dynamic image series. When time is short, it is necessary either to find a sync signal to sum synchronous images in real time or to acquire a regular time series and to synchronize a posteriori. Dynamic acquisitions were performed (gastric and lung studies). The activity in each pixel of the moving organ can be expressed as h(t)=a0 + a1 cos(omegao0t - phi). The time-activity curve u(t) over a region of interest (ROI) of the considered organ was computed. When the ROI is well chosen, the power spectrum of u(t) exhibits a sharp peak near the characteristic frequency of the periodic motion. The DC component, amplitude and phase in each pixel can be then estimated by minimizing the following function: J=sigma[h(t) - g(t)]2, where g(t) is a noisy measurement of h(t). It is then easy to reconstruct an a posteriori gated time series by computing h(t) for various times over a single period. This approach was successful in characterizing lung and gastric motions. Dynamic series were acquired as for gastric emptying studies. The characteristic frequency of antral motility was easily and unambiguously estimated and DC, amplitude and phase images were computed. Dynamic pulmonary functional imaging was performed with 81Krm. The characteristic frequency was also easily estimated from the time-activity curve power spectrum using a ROI drawn over the lower part of the lungs. The DC, amplitude and phase images were then computed from the dynamic series and the characteristic frequency. In conclusion, a posteriori gating of dynamic series of periodically moving organs can be achieved in a simple fashion. This approach overcomes the difficulty of direct analysis of time-activity curves and provides amplitude and phase images.

Algorithms↗
PubMed2025

Experimental Test of Evolutionary Safety of a CRISPR-Cas9 Gene-Drive Element.

CRISPR-Cas9 gene drives (CCGDs) are powerful tools for genetic control of wild populations, with applications from disease eradication to species conservation. However, Cas9 alone and in a complex with gRNA can cause double-stranded DNA breaks at off-target sites, which could increase the mutational load and lead to unintended loss-of-heterozygosity (LOH) events. These undesired effects raise potential concerns about the long-term evolutionary safety of CCGDs, but the magnitude of these effects is unknown. To measure how the presence of a CCGD or a Cas9 alone in the genome affects the rates of LOH events and de novo mutations, we carried out a mutation accumulation experiment in yeast Saccharomyces cerevisiae. We found no detectable effects on the genome-wide rates of mutations or LOH events. Our power calculations suggest that CCGD or Cas9 affect these rates by less than 30%, which is much less than natural variation for these traits in yeast. A more detailed examination shows that CCGD or Cas9 may alter the lengths and genomic distributions of LOH events, but the statistical support for these effects is weak. Thus, our results demonstrate that CCGDs impose at most a weak additional mutational burden in the yeast model. Although mutagenic effects of gene drives need to be further evaluated in other systems, our results add credence to the proposition that the evolutionary risks posed by well designed gene drives are likely acceptable.

Journal Article↗
PubMed2001

Many-body interaction effects on the low-k structure of liquid Kr.

Neutron diffraction measurements and theoretical calculations of the structure factor S(k) of liquid Kr are extended to small k values (k<4 nm(-1)). The results show that many-body interaction contributions have an increasing effect on S(k) as k-->0, reaching at least 40% of the measured intensity. Both the phase diagram and the low-k structural data of dense Kr turn out to be closely reproduced by the hierarchical reference theory if additional many-body forces are taken into account by an augmented strength of the Axilrod-Teller triple-dipole potential. The experimental density derivative of S(k) is also used for a very sensitive test of the theories and interaction models considered here.

Krypton↗
PubMed1977

Determination of splenic blood flow by inhalation of radioactive rare gases.

We have evaluated the 133Xenon inhalation method for the determination of splenic blood flow. In twenty-two healthy persons the blood flow was on average 109 +/- 4 mg/100 g X min, which is equivalent to a total blood flow of about 170 ml/min. In patients with chronic fatty liver hepatitis specific blood flow was reduced (81 +/- 10 ml/100 g X min) as it was in patients with cirrhotic liver without splenomegaly (75 +/- 2 ml/100 g X min). With increasing weight of the spleen, the total blood flow rises, although specific blood flow is low. Our results obtained by the 133Xenon inhalation method are similar to results obtained by others using intraarterial injection of tracer gas. The advantages of the inhalation method as a non-traumatic method are: (1) the stress for the patient is very small; (2) blood flow measurements can be repeated within short periods of time. We consider for the present the 133Xenon inhalation method to be the method of choice for the determination of the splenic blood flow.

Adult↗