Exploring the utility of whole‐exome sequencing as a diagnostic tool in a child with atypical episodic muscle weakness

The advent of whole‐exome next‐generation sequencing (WES) has been pivotal for the molecular characterization of Mendelian disease; however, the clinical applicability of WES has remained relatively unexplored. We describe our exploration of WES as a diagnostic tool in a 3½‐year old female patient with a 2‐year history of episodic muscle weakness and paroxysmal dystonia who presented following a previous extensive but unrevealing diagnostic work‐up. WES was performed on the proband and her two parents. Parental exome data was used to filter potential de novo genomic events in the proband and suspected variants were confirmed using di‐deoxy sequencing. WES revealed a de novo non‐synonymous mutation in exon 21 of the calcium channel gene CACNA1S that has been previously reported in a single patient as a rare cause of atypical hypokalemic periodic paralysis. This was unexpected, as the proband's original differential diagnosis had included hypokalemic periodic paralysis, but clinical and laboratory features were equivocal, and standard clinical molecular testing for hypokalemic periodic paralysis and related disorders was negative. This report highlights the potential diagnostic utility of WES in clinical practice, with implications for the approach to similar diagnostic dilemmas in the future.     

Accuracy of commercially available processing algorithms for planar radionuclide ventriculography using data for a dynamic left ventricular phantom

BACKGROUND: Automatic and semi-automatic algorithms to calculate ejection fraction (EF) from planar radionuclide ventriculography (PRV) have been used for many years in nuclear medicine. Validation of these algorithms is scarce and often performed on outdated versions of the software. Nevertheless, clinical trials where PRV is being used as the 'gold standard' for EF are numerous. Because of the importance attributed to the EF calculated by these programs, the accuracy of the resulting EF was assessed with a dynamic left ventricular physical phantom. METHODS: A dynamic left ventricular phantom was used to simulate 21 combinations of various ejection fractions (7-66%) and end diastolic volumes (27-290 ml). For each combination, a planar radionuclide ventriculograph was acquired, converted to an interfile format and transferred into processing stations with 10 different contemporaneously available commercial algorithms. The gold standard was the 'real' EF of the phantom, derived from the exact volume of the ventricle in end diastolic and end systolic position. Correlation and Bland-Altman analysis was performed between the real EF and the calculated EF. RESULTS: The correlation for all data was excellent (r=0.98), the mean difference was very acceptable (0.98%). Nevertheless, Bland-Altman analysis showed a significant trend in the difference between real and calculated EF, with a growing underestimation for higher ranges of EF, due to an overestimation of background in larger volumes compared to smaller ones. CONCLUSION: The determination of EF from PRV, calculated with commercially available algorithms, correlates closely to the real EF of a dynamic left ventricular phantom. This phantom can be used in the development and validation of algorithms for PRV studies, in software audits and in quality assurance procedures.     

Common bile duct calculi: updated experience with dissolution with methyl tertiary butyl ether

The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control.     

Widespread Castleman disease: CT and US findings

The widespread form of Castleman disease is a rare condition that has been recognized only recently as a disease with an aggressive, often malignant course. The authors present computed tomographic (CT) findings in six patients with this condition and ultrasound (US) findings in four of the six. CT demonstrated splenomegaly and retroperitoneal lymphadenopathy in all six patients. In one patient, CT also showed additional widespread mesenteric and peripancreatic lymphadenopathy, a large mesenteric mass adherent to the descending colon in another, and mediastinal lymphadenopathy in a third. Three patients had peripheral axillary or inguinal lymphadenopathy. Enlarged lymph nodes were 1-4 cm in diameter, and none displayed contrast enhancement on CT scans obtained with drip infusion of contrast media. On US scans, the nodes were poorly echogenic in all four cases. In no case was focal liver or splenic infiltration seen on either CT or US scans.     

Nitrate administration increases blood flow in dysfunctional but viable myocardium, leading to improved assessment of myocardial viability: A PET study.

SPECT with 99mTc-labeled agents is better able to detect viability after nitrate administration. Nitrates induce vasodilation and may increase blood flow to severely hypoperfused but viable myocardium, thereby enhancing tracer delivery and improving the detection of viability. Quantitative data on the changes in blood flow are lacking in SPECT but can be provided by PET. The aim of the present study was to use PET to evaluate whether nitrate administration increases blood flow to chronically dysfunctional but viable myocardium. METHODS: 13N-Ammonia PET was used to quantitatively assess blood flow, and 18F-FDG PET was used as the gold standard to detect viable myocardium. Twenty-five patients with chronic ischemic left ventricular dysfunction underwent 13N-ammonia PET at rest and after nitrate administration. RESULTS: A significant increase in nitrate-enhanced blood flow was observed in viable segments (from 0.55 +/- 0.15 to 0.68 +/- 0.24 mL/min/g, P < 0.05). No statistically significant change in blood flow was observed in nonviable segments (0.60 +/- 0.20 vs. 0.55 +/- 0.18 mL/min/g). A ratio of at least 1.1 for nitrate-enhanced flow to resting flow allowed optimal detection of viable myocardium, yielding a sensitivity of 82% with a specificity of 100%. CONCLUSION: 13N-Ammonia PET showed a significant increase in nitrate-enhanced blood flow in viable myocardium, whereas blood flow remained unchanged after nitrate administration in nonviable myocardium. Nitrate use during myocardial perfusion imaging will lead to improved assessment of myocardial viability.     

Biodistribution and dosimetry study of 123I-rh-annexin V in mice and humans

This study reports on the optimization of the labelling procedure of clinical grade 123I-rh-annexin V and on the investigation of the biodistribution and dosimetry of 123I-rh-annexin V, a tracer proposed for the study of apoptosis in mice and humans. Research grade 123I-rh-annexin V was prepared as described previously, whereas clinical grade 123I-rh-annexin V was prepared according to a modified IodoGen method. NMRI mice, 3-4 weeks of age, received research grade 123I-rh-annexin V (74.0+/-3.7 kBq/mouse) by intravenous (i.v.) injection and killed at preset time points. Afterwards, the collected organs, blood, urine and faeces were counted for radioactivity and determined as %ID/g tissue or %ID over time. Secondly, six volunteers with normal liver and kidney function underwent whole-body scans up to 21 h after i.v. injection of clinical grade 123I-rh-annexin V (345+/-38 MBq). Time-activity curves were generated for the organs of interest, e.g., thyroid, heart, liver, kidneys and whole body, by fitting the organ specific geometric mean counts, obtained from region of interest analysis of acquired images in humans. The MIRD formulation was applied to calculate the absorbed radiation doses for various organs. Clinical grade 123I-rh-annexin V was obtained in radiochemical yields of 87.0+/-6.5% and radiochemical purities >98%. In mice, research grade 123I-rh-annexin V accumulated primarily in liver, kidney, stomach and lung tissue, limiting its usefulness for imaging of ongoing apoptosis in the abdominal and thoracic region. Clearance was predominantly urinary. In humans, acquired images with the clinical grade radioligand showed low lung uptake, resulting in good imaging conditions for the thoracic region. On the other hand, delayed imaging of the abdominal region was impeded due to extensive bowel activity. The highest absorbed doses were received by the thyroid, the kidneys, the heart wall, the liver and bone surfaces. The average effective dose of 123I-rh-annexin V was estimated to be 0.02 mSv.MBq-1. The amount of 123I-rh-annexin V required for in vivo imaging, results in an acceptable effective dose to the patient.     

In vivo evaluation of [123I]-4-iodo-N-(4-(4-(2-methoxyphenyl)-piperazin-1-yl)butyl)-benzamide: a potential sigma receptor ligand for SPECT studies

In this study, in vivo evaluation in mice and rabbits of [123I]-4-iodo-N-(4-(4-(2-methoxyphenyl)-piperazin-1-yl)butyl)-benzamide ([123I]-BPB), a potential radioligand for visualisation of the sigma receptor by single photon emission computed tomography (SPECT), is reported. The compound possesses appropriate lipophilicity (log P=2.2) and binds sigma-1 and sigma-2 receptors (pKi=6.51 and 6.79, respectively). In mice, this new radioiodinated tracer exhibited high brain uptake (4.99% ID/g tissue at 10 min postinjection) and saturable binding (3.06% ID/g tissue at 10 min postinjection) as determined by pretreatment with unlabeled [123I]-BPB. A metabolite study demonstrated no (less than 5%) labeled metabolites in the brain. In rabbits, regional brain distribution was investigated and the tracer displayed high, homogeneous central nervous system uptake. Selectivity was assessed by competition experiments with known sigma ligands. Metabolite analysis showed no (less than 8%) labeled metabolites in the rabbit brain. In conclusion, our findings indicate that [123I]-BPB is not a suitable tracer for visualisation of D3 receptors while its potential for sigma receptor imaging is severely hampered by its affinity for dopamine receptors.     

In vivo apoptosis detection with radioiodinated Annexin V in LoVo tumour-bearing mice following Tipifarnib (Zarnestra, R115777) farnesyltransferase inhibitor therapy

In this paper, the use of (123)I-Annexin V for the detection of farnesyltransferase inhibitor (FTI)-induced apoptosis in tumour-bearing athymic mice is described. In vitro binding assays on LoVo cells show time- and dosage-dependent (125)I-Annexin V binding upon treatment with Tipifarnib (Zarnestra, R115777), a selective and potent FTI. In vivo experiments using planar gamma scintigraphy on LoVo inoculated mice show a 40% increased (123)I-Annexin V uptake 8 h after a single oral administration of 100 mg/kg Tipifarnib in 20% beta-cyclodextrin in 0.1 M HCl, as well as after 3 days of twice daily treatments with the same dose. Ex vivo TUNEL assays, detecting end-stage apoptotic cells, correlate significantly with both in vitro and in vivo results. The percentage of necrosis is also increased by Tipifarnib treatment, but is too low to interfere with the (123)I-Annexin V uptake. It can be concluded that (123)I-Annexin V can be used to monitor Tipifarnib-induced apoptosis in LoVo xenograft tumours in athymic mice. Future applications might include the early prediction of FTI response and the selection of FTI-sensitive patients very shortly after treatment initiation. Subsequently, such patients would greatly benefit from a noninvasive and fast therapy evaluation.     

Normal and stenotic renal arteries: experimental balloon-expandable intraluminal stenting

Elastic recoil of the vessel wall is a common cause of failure of percutaneous transluminal angioplasty in renal arteries. To oppose such recoil, balloon-expandable metal stents were implanted in artificially stenotic renal arteries in pigs and normal renal arteries in dogs and pigs. The stents were then examined angiographically and histologically at regular intervals. All stents were completely covered with endothelialized neointima in 3 weeks. There was no difference in intimal thickness between the stenotic and nonstenotic renal arteries. A large stent diameter and a large open or nonmetal surface may cause less intimal hyperplasia, but nonturbulent, fast arterial flow is probably the most important factor in ensuring long-term patency of the vessel.