Review: Somatic mutations in neurodegeneration.

Somatic mutations are postzygotic mutations which may lead to mosaicism, the presence of cells with genetic differences in an organism. Their role in cancer is well established, but detailed investigation in health and other diseases has only been recently possible. This has been empowered by the improvements of sequencing techniques, including single-cell sequencing, which can still be error-prone but is rapidly improving. Mosaicism appears relatively common in the human body, including the normal brain, probably arising in early development, but also potentially during ageing. In this review, we first discuss theoretical considerations and current evidence relevant to somatic mutations in the brain. We present a framework to explain how they may be integrated with current views on neurodegeneration, focusing mainly on sporadic late-onset neurodegenerative diseases (Parkinson's disease, Alzheimer's disease and amyotrophic lateral sclerosis). We review the relevant studies so far, with the first evidence emerging in Alzheimer's in particular. We also discuss the role of mosaicism in inherited neurodegenerative disorders, particularly somatic instability of tandem repeats. We summarize existing views and data to present a model whereby the time of origin and spatial distribution of relevant somatic mutations, combined with any additional risk factors, may partly determine the development and onset age of sporadic neurodegenerative diseases.

Four novel SPG3A/atlastin mutations identified in autosomal dominant hereditary spastic paraplegia kindreds with intra-familial variability in age of onset and complex phenotype.

Mutation of the atlastin gene (SPG3A) is responsible for approximately 10% of autosomal dominant hereditary spastic paraplegia (AD-HSP) cases. The goal of this study was to identify novel disease causing atlastin mutations. Atlastin nucleotide variations were detected by direct sequencing of all 14 exons in 70 autosomal dominant (AD), 16 single sibship and 14 sporadic spastic paraplegia patients. Six mis-sense mutations (four of which were novel) were identified in six unrelated AD-HSP kindreds in exons 4, 7 and 8 of the atlastin gene. One kindred with a novel mutation showed variability in clinical phenotype and age of onset. Mutations are predicted to decrease GTPase activity, cause morphological abnormalities of the endoplasmic reticulum and prevent maturation of the Golgi complex resulting in impaired vesicle trafficking. Our study significantly adds to the spectrum of mutations and clinical phenotype of SPG3A. We advocate that all spastin mutation negative AD-HSP kindreds should be screened for pathogenic atlastin mutations regardless of age of onset or phenotypic complexity.

Infecton: a 99mTc-ciprofloxacin radiopharmaceutical for the detection of bone infection.

OBJECTIVE: To evaluate Infecton scintigraphy, with technetium-99m-radiolabeled ciprofloxacin, as a means to detect bone infection, in comparison with other conventional scintigraphic and radiologic methods. METHODS: Forty-five patients with known or suspected bone infection underwent 50 scans with Infecton. Almost all were also subjected to a three-phase 99mTc-methylene diphosphonate bone scan and most of them to a 99mTc-human polyclonal immunoglobulin scan as well as to a gallium-67-citrate scan, plus computerized tomography or magnetic resonance imaging or both. Clinical laboratory criteria for the presence of osteomyelitis were based on the definitions of the Centers for Disease Control and Prevention. RESULTS: Staphylococcus aureus and Pseudomonas aeruginosa were the most frequently isolated pathogens. Based on the CDC clinical laboratory criteria as well as on conventional scan results, Infecton was characterized in 35 studies as 'true positive', in eight as 'true negative', in two as 'false positive', in one as 'false negative', and in four as 'indeterminate'. The sensitivity and specificity of Infecton scintigraphy were found to be 97.2% and 80%, respectively, with positive and negative predictive values of 94.6% and 88.9%. CONCLUSIONS: It is concluded that Infecton is a very sensitive and quite specific marker of bone infection, but care must be taken in cases of excessive new bone formation and primary bone tumors, where false-positive results may be obtained.

Screening of patients with hereditary spastic paraplegia reveals seven novel mutations in the SPG4 (Spastin) gene.

Hereditary spastic paraplegia (HSP) is a heterogeneous condition characterised in its pure form by progressive lower limb spasticity. Mutations in SPG4 (encoding spastin) may be responsible for up to 40% of autosomal dominant (AD) cases. A cohort of 41 mostly pure HSP patients from Britain and Austria, 30 of whom displayed AD inheritance, was screened for mutations in SPG4 by single strand conformation polymorphism (SSCP) analysis followed by sequencing of samples with mobility shifts. We identified eight SPG4 mutations in pure AD HSP patients, seven of which were novel: one missense mutation within the AAA cassette (1633G>T), two splice site mutations (1130-1G>T, 1853+2T>A) and four frameshift mutations (190_208dup19, 1259_1260delGT, 1702_1705delGAAG, 1845delG). A novel duplication in intron 11 (1538+42_45dupTATA) was also detected. We report the HUGO-approved nomenclature of these mutations as well. Furthermore, we detected a silent change (1004G>A; P293P), previously reported as a mutation, which was also present in controls. The frequency of SPG4 mutations detected in pure AD HSP was 33.3%, suggesting that screening of such patients for SPG4 mutations is worthwhile. Most patients will have unique mutations. Screening of SPG4 in apparently isolated cases of HSP may be of less value.

A large family with hereditary spastic paraparesis due to a frame shift mutation of the spastin (SPG4) gene: association with multiple sclerosis in two affected siblings and epilepsy in other affected family members.

Hereditary spastic paraparesis (HSP) is a clinically and genetically heterogeneous neurodegenerative disorder characterised by progressive lower limb spasticity and weakness. Some forms have been associated with white matter lesions and complex phenotypes. This study was prompted by the diagnosis of multiple sclerosis (MS) in two sisters from a large pedigree with hereditary spastic paraparesis. Twelve affected members of the extended family were examined (MRI and EEG were carried out and evoked potentials measured in five), and historical information was obtained from six affected deceased persons. The inherited disease phenotype was confirmed as autosomal dominant hereditary spastic paraparesis associated with epilepsy in four affected persons. None of the extended family had evidence of MS. Genetic analysis of the family has shown linkage to chromosome 2p and sequencing of the spastin gene has identified a 1406delT frameshift mutation in exon 10. This kindred demonstrates the clinical heterogeneity of HSP associated with spastin mutations. The possible relevance of the concurrence of HSP and MS in the sib pair is discussed.

Differences in effective dose estimation from dose-area product and entrance surface dose measurements in intravenous urography.

In this study, measurements of dose-area product (DAP) and entrance surface dose (ESD) were carried out in a sample of 25 adult patients who underwent intravenous urography (IVU). These measured quantities were used to estimate the effective dose E from the IVU examination, a quantity closely correlated to radiation risk. Estimating E involves the use of conversion coefficients that have been determined for specific X-ray views in a mathematical phantom. These are obtained under conditions which are not usually met in clinical practice. As a result, the E estimates using the two different measurable quantities can be quite different. Analysis of the calculation procedure suggests that the E estimate using the DAP measurements, in addition to being more practical, could be more accurate than using ESD measurements, as DAP is sensitive to the X-ray field size settings. Furthermore, it is shown that in the absence of the appropriate equipment, a reliable E estimate can be obtained from the ESD calculated using the exposure data for each X-ray view.

The diagnostic X-ray protection characteristics of Panelcrete, Aquapanel, Betopan and Gypsoplak Superboard.

Panelcrete, Aquapanel and Betopan are cement-based building materials with uses similar to those of gypsum wallboard, whose properties as a diagnostic X-ray shielding material have been extensively studied. The X-ray attenuation characteristics of these cement-based boards as well as those of a gypsum wallboard, Gypsoplak Superboard, are investigated for broad beam geometry conditions and for tube potentials of 50 kVp, 70 kVp, 100 kVp, 125 kVp and 140 kVp. Comparisons between these materials as well as with published data for gypsum wallboard are made. An example of their use as secondary barriers is given. Furthermore, it is confirmed that when building materials are considered for diagnostic X-ray shielding, calculations based on data for similar materials and corrected for density differences can be used only as an approximation.

Image quality assessment and radiation doses in intraoral radiography.

OBJECTIVE: The purpose of this study was to investigate 2 very important aspects of dental radiographic image quality, exposure time settings and film processing, and to assess their relation to radiation dose. STUDY DESIGN: Radiographic images of a dental image quality test tool were obtained in 108 dental practices. Image quality and film processing were evaluated both subjectively and objectively by comparing films developed by the dentists with films developed under optimum conditions. The data consisted of measured values of optical density, which were used to obtain image contrast, and scores of image quality and film processing, which were based on criteria set by 2 independent oral radiologists. Entrance surface dose was also measured for the technique used at each dental practice. RESULTS: The results indicate a great variability of exposure time settings used by the dentists for imaging the phantom. Film processing was inadequate in most of the practices, which resulted in poor image quality and increased patient radiation doses. The mean entrance surface dose for imaging the phantom was 3.8 mGy. CONCLUSION: Intraoral imaging techniques and film processing must be standardized to improve image quality and further reduce patient radiation doses.

Diagnostic value of anti-alpha FP antibody levels in a metastatic germ cell tumor of unknown primary site.

BACKGROUND: A 21 year old man with a metastatic germ cell tumor of unknown primary not responding to chemotherapy was scheduled to have a blind bilateral orchiectomy to eradicate the possible primary site although palpation and ultrasonography of the testicles had always been normal. METHOD: The patient underwent a radioimmunoscintigraphy with Anti-alpha FP antibody scan (AFP-Scan). RESULTS: On the basis of the scintigraphic results the patient underwent a left orchiectomy and additionally removal of the lymph node metastases. Histology revealed the presence of an in situ carcinoma in the left testis and a mixed tumor present in the abdominal lymph node metastases. Fluorescent in situ hybridization on tumor cells did not show any abnormalities related to chromosome 12, a finding connected with the somatic type of germ cell tumors. CONCLUSION: Anti-alpha FP antibody scan was helpful in detecting the primary site and saving the life of the patient without resulting in hypogonadism.

Patient doses from barium meal and barium enema examinations and potential for reduction through proper set-up of equipment.

Patient doses for barium meal and barium enema examinations, performed at two Greek hospitals, were measured using a dose-area product meter. The results were analysed to obtain the contributions of fluoroscopy and radiography to the dose as well as a number of other dose related parameters for each examination. The doses observed are within the range of values reported by other authors and comply with the dose reference levels (DRLs), proposed from relevant surveys in the UK and The Netherlands. However, comparison between the two hospitals revealed significant differences in the contributions to dose from the various parts of the examinations. To determine the reasons for these differences, measurements of dose related parameters were made using a Plexiglas phantom and standard clinical X-ray machine settings. Factors contributing to increased dose delivery were determined and recommendations have been made concerning ways in which doses might be reduced in each hospital, without degradation of the diagnostic quality of these examinations.

Body composition assessment by dual-energy x-ray absorptiometry: comparison of prone and supine measurements.

The aim of the study was to assess whether changes in the interposition of body compartments affect the results of body composition measurements by dual-energy x-ray absorptiometry (DEXA) in the fan-beam mode. Thirty healthy subjects underwent two sequential measurements: the first was performed in the supine position as described by the manufacturer, and the second in the prone position. Estimates of body composition were compared between the two measurements. Mean body weight did not differ between measurements ([mean+/-SD] supine vprone, 68.561+/-12.461 v 68.589+/-12.469 kg). Mean bone mineral content (BMC) was lower in the prone position versus the supine position. When the head was excluded, this difference reached statistical significance (supine v prone, 1,738+/-361 v 1,688+/-360 g, P=.0001). The mean fat tissue mass (FTM) was lower and lean tissue mass (LTM) higher in the prone measurements. When the head was excluded, the mean FTM difference between the two measurements became greater (FTM supine v prone, 25.129+/-10.445 v 24.030+/-10.388 kg, P=.0001; LTM supine v prone, 37.309+/-9.357 v 38.246+/-9.150 kg, P=.0001). It is concluded that the positioning of the patient on the examination table affects DEXA body composition measurements by the fan-beam mode. This could imply a lack of accuracy of the method, which may be due to subtle changes in regional tissue depth and fat distribution caused by patient repositioning.

Thallium-201 for detection of myocardial viability: comparison of early postexercise reinjection and imaging with 4 and 18-24 hours redistribution imaging.

To evaluate the efficacy of an early 201Tl reinjection and imaging protocol for reducing the need for conventional 4-hour or optimal 24-hour redistribution imaging (RI) and detecting of myocardial viability, we compared the results of early postexercise Tl reinjection and imaging with those of 4- and 24-hour RI in 74 consecutive patients aged 55 +/- 9 years (mean +/- SD) who were assessed for myocardial ischemia. One millicurie of Tl was injected promptly after completion of the initial postexercise imaging (PEX) and three additional sets of images were acquired 1, 4 and 18-24 h later. A total of 2,368 segments were evaluated. On PEX, 390 (17%) segments showed defects, of which 287 (74%) showed enhanced Tl uptake at 1-hour RI; 89 (23%) did not change and 14 (4%) showed reverse redistribution. Of the 103 persistent defects, only 27 (7%) showed further fill-in of Tl; 62 (16%) segments showed reverse redistribution at 4-hour RI while at 18- to 24-hour RI 17 (4%) and 47 (12%) segments showed further fill-in of Tl and reverse redistribution, respectively. Finally, after analysis of 4- and 18- to 24-hour RI, the diagnosis changed from myocardial necrosis to ischemia in only 2 (3%) patients. In conclusion, these results suggest that by eliminating the need for an additional delayed set of images for detection of myocardial viability, this protocol reduces the total investigation procedure, is more convenient for the patient, increases patient turnover and expedites the decision-making process.

Strontium-89 chloride in the treatment of bone metastases from breast cancer.

Sixty-four patients with painful metastatic breast cancer in bone were treated with 2 MBq/kg of strontium-89 chloride as a single intravenous injection. Patients were followed with records of medication, hematology parameters, serial bone and Sr-89 bremsstrahlung images and with a point pain score scale (10-0). The response was assessed during a 6-month period of follow-up. Fifty-two of 64 patients (81%) showed at least a moderate improvement. Eighteen out of the 52 responders showed a dramatic decrease in bone pain (35%), 21 (40%) presented a satisfactory response and in 13 cases (25%) the response was moderate. Only 12 patients (19%) from the whole group did not feel any improvement on pain palliation. A statistically significant decrease of pretreatment levels of platelets and leukocyte counts was observed after 4-6 weeks of therapy in 50 (70%) patients. Although most patients showed no change in their bone scans after 3 months of treatment, an obvious improvement was observed in 3 of them. Furthermore no additional painful metastases on their bone scintigraphic images were observed. The selective strontium-89 local uptake in metastatic sites was also confirmed directly by bremsstrahlung scans which were absolutely comparable to the respective 99mTc bone scans. Precautions have been taken against Sr-89 contamination from the patients' blood or excretions.

Thyroid function in postmenopausal women with breast cancer on tamoxifen.

In 42 postmenopausal women with breast cancer, aged 48-85 years (mean age 62.4 years) serum thyroid hormone concentrations were measured before and after 6 months of tamoxifen therapy (20 mg daily). In particular triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4), thyroxine-binding globulin (TBG) and thyroid-stimulating hormone (TSH) concentrations before and 30 minutes after thyrotrophin-releasing hormone (TRH) administration (200 microg i.v.) were measured before and 6 months after tamoxifen therapy. T3 and T4 concentrations increased significantly (p<0.001 and p<0.05, respectively) whereas FT3 and FT4 remained unchanged (p>0.05), TBG increased significantly (p<0.001) and basal TSH concentrations as well as TSH response to TRH injection increased significantly (p<0.05) after tamoxifen therapy. It is concluded that tamoxifen administration changes thyroid hormone concentrations. However free thyroid hormone levels remain unchanged and the patients remain euthyroid after long-term tamoxifen therapy.

Early postexercise thallium-201 reinjection after sublingual nitroglycerin augmentation: effects on detection of myocardial ischemia and/or viability.

BACKGROUND: Thallium-201 (201Tl) reinjection after conventional redistribution imaging is a standard procedure, resulting in enhanced 201Tl redistribution which is compatible with viable myocardium. Although this method significantly improves identification of viable myocardium, it increases the investigation time by approximately 1 h. Thus, this technique is suboptimal from the standpoint of patient convenience, since its routine performance may be impractical in a high-volume nuclear medicine laboratory. HYPOTHESIS: This study was undertaken to evaluate the efficacy of an early 201Tl reinjection and imaging protocol in combination with sublingual nitroglycerin, to detect myocardial ischemia and/or viability, and to reduce the need for conventional (4 h) redistribution imaging. MATERIALS AND METHODS: In this study, 62 consecutive coronary patients, referred for the detection of possible myocardial ischemia and/or viability, were involved (mean age 55 years, range 41-70). Of those, 50 had previous angina attacks, with 42 having a history of previous myocardial infarction; 10 patients had coronary artery bypass grafting; and the remaining 2 had atypical chest pain. Immediately after the completion of the initial postexer-cise imaging, 0.3 mg sublingual nitroglycerin followed by the reinjection of 1 m Ci of 201Tl were administered, and two further sets of images were acquired 1 h and 4 h later. RESULTS: In each set of images, a total of 496 segments were analyzed. On postexercise imaging, 305 (61%) segments demonstrated defects of which 198 (65%) showed enhanced thallium uptake, 97 (32%) did not change, and 10 (3%) showed reverse redistribution on 1 h reinjection imaging (IRI). Of the 97 persistent defects, only 17 (6%) showed fill-in of 201Tl on 4 h redistribution imaging (CRI), while 12 (4%) segments showed reverse redistribution. On the other hand, after analyzing the 62 patients of the 1 h IRI, 17 (27%) remained unchanged while in only 1 patient (6%) of 17 the diagnosis changed from myocardial necrosis to ischemia after analysis of the 4 h CRI. CONCLUSION: These results indicate that early postexercise reinjection of 201Tl in combination with sublingual nitroglycerin followed by 1 h image acquisition may prove useful for a comprehensive and convenient assessment of myocardial ischemia and/or viability.

Body composition changes in chronic hemodialysis patients before and after hemodialysis as assessed by dual-energy x-ray absorptiometry.

The aim of this study was to investigate the effect of hemodialysis on body composition assessment by dual-energy x-ray absorptiometry (DEXA). Seventeen patients with chronic renal failure who were on a regular hemodialysis schedule were studied. Body weight and body composition were assessed immediately before and approximately 1 hour after a typical hemodialysis session. Body weight was assessed by means of an electronic balance. Body composition measurements were made by DEXA. Whole-body and subtotal (head and neck excluded) analysis assessed the following parameters: body weight, bone mineral density (BMD), bone mineral content (BMC), and fat (FTM) and lean (LTM) tissue mass. BMC, FTM, and LTM were estimated separately for the trunk, arms, and legs. The mean body weight reduction after hemodialysis was 2.8 +/- 1.1 kg (mean +/- SD). Concerning whole-body analysis, no change was observed in mean BMC and FTM after hemodialysis. On the contrary, a significant reduction was observed in mean body weight as assessed by DEXA (before hemodialysis, 65.0 +/- 11.4 kg; after, 62.2 +/- 10.9 kg, P = .0003), as well as in mean LTM (before hemodialysis, 42.7 +/- 9.4 kg; after, 39.7 +/- 9.0 kg, P = .0003). Similar results were obtained from subtotal and regional analysis. Body weight changes as measured by the electronic balance exhibited a strong positive correlation with the changes in both body weight and LTM as assessed by DEXA (r = .989, standard error of the estimate [SEE] = 0.167 kg and r = .941, SEE = 0.382 kg, respectively, P < .0001). It is concluded that gravimetric changes induced by hemodialysis are highly correlated with LTM changes and are not associated with changes in BMC or FTM estimated by DEXA.

Energy intake and monounsaturated fat in relation to bone mineral density among women and men in Greece.

BACKGROUND: Several variables have been established as risk factors for osteoporosis: it is more common among women and the gender difference increases with age and with years since menopause. Estrogens, androgens, physical activity, and body mass index have been previously shown to be positively associated with bone mineral density and inversely with risk for fractures. METHODS: To assess the effect on bone mineral content of energy-generating nutrients, healthy men (n = 36) and women (n = 118) ages 25-69 years were interviewed among visitors and staff of the University of Athens Department of Medical Physics. Bone mineral density (BMD) was measured by single photon absorptiometry. RESULTS: Demographic and lifestyle variables were not significantly related to BMD in this study, although the patterns were consistent with those previously reported by other investigators. Total energy intake, which also reflects energy expenditure through physical activity, was positively associated with BMD among both men (P = 0.003) and women (P = 0.04). After adjustment for nonnutritional variables and energy intake, monounsaturated fat, which in the Greek population is mostly derived from olive oil, was associated with BMD. The association was positive among both men (P = 0.01) and women (P = 0.03). There was evidence for an inverse association between carbohydrate intake and BMD, but the association was significant only with respect to mono- and disaccharides. CONCLUSIONS: In this population, consumption of monounsaturated fat and physical activity were predictive of bone mineral density, but larger studies are needed.

Sex hormones in postmenopausal women with breast cancer on tamoxifen.

In 42 postmenopausal women with breast cancer aged 48-85 (mean age 62.4) years, the blood sex hormone levels were measured before and after 6 months of tamoxifen administration (20 mg daily). Follicle-stimulating hormone and luteinizing hormone levels decreased after tamoxifen administration (p < 0.001), but remained in the postmenopausal range, oestradiol levels increased (p < 0.05), sex hormone binding globulin levels increased (p < 0.001), testosterone levels remained stable (p > 0.1), free testosterone levels decreased (p < 0.001), delta4-androstenedione, 17-hydroxyprogesterone, and dehydroepiandrosterone sulfate levels remained unchanged (p > 0.1), and basal prolactin levels and their response to thyrotrophin-releasing hormone injection decreased significantly (p < 0.001) after tamoxifen therapy. It is concluded that tamoxifen has many and diverse effects on sex hormone levels, and its adverse effects do not affect the biological status of the patient, except perhaps for oestradiol, that increases in some cases, whose possible effect must be studied.

Immunolocalization of transitional cell carcinoma of the bladder with intravesically administered technetium-99m labelled HMFG1 monoclonal antibody.

The aim of this study was the immunolocalization of transitional cell carcinoma of the bladder with a radiolabelled murine tumour-associated monoclonal antibody and the measurement of the absolute uptake of the antibody by the tumour. Fourteen patients with transitional cell carcinoma of the bladder received 3-6 mCi (111-222 MBq) of technetium-99m labelled HMFG1 monoclonal antibody intravesically and one patient, 2 mCi (74 MBq) of iodine-131 labelled 11.4.1, which is a non-tumour-specific monoclonal antibody. Four of the 15 patients were evaluated with single-photon emission tomography (SPET) 1 1/2 to 2 h post administration. All patients underwent transurethral resection of the bladder tumour within 12-20 h following intravesical administration of the radiolabelled antibody. The radioactivity of biopsy specimens from normal urothelium and tumour areas were counted in a gamma counter. The mean uptake of the radiolabelled antibodies from normal and tumour sites was expressed as a percentage of the administered dose per kilogram of tissue. Conventional histology and immunohistochemistry using HMFG1 monoclonal antibody were performed on paraffin sections of the biopsy specimens. Although our results are preliminary, it can be concluded that: (a) bladder tumours are well imaged by SPET when using 99mTc-HMFG1; (b) intravesically administered radiolabelled antibody remains on the bladder tissue and does not escape into the systemic circulation; (c) the wide range of tumour uptake values (0%-9.3% administered dose/kg) observed probably can be attributed to heterogeneity of the antigenic expression of the tumour; (d) values of 99mTc-HMFG1 monoclonal antibody uptake by the tumour do not justify future attempts at radioimmunotherapy.