iMPI: portable human-sized magnetic particle imaging scanner for real-time endovascular interventions

Minimally invasive endovascular interventions have become an important tool for the treatment of cardiovascular diseases such as ischemic heart disease, peripheral artery disease, and stroke. X-ray fluoroscopy and digital subtraction angiography are used to precisely guide these procedures, but they are associated with radiation exposure for patients and clinical staff. Magnetic Particle Imaging (MPI) is an emerging imaging technology using time-varying magnetic fields combined with magnetic nanoparticle tracers for fast and highly sensitive imaging. In recent years, basic experiments have shown that MPI has great potential for cardiovascular applications. However, commercially available MPI scanners were too large and expensive and had a small field of view (FOV) designed for rodents, which limited further translational research. The first human-sized MPI scanner designed specifically for brain imaging showed promising results but had limitations in gradient strength, acquisition time and portability. Here, we present a portable interventional MPI (iMPI) system dedicated for real-time endovascular interventions free of ionizing radiation. It uses a novel field generator approach with a very large FOV and an application-oriented open design enabling hybrid approaches with conventional X-ray-based angiography. The feasibility of a real-time iMPI-guided percutaneous transluminal angioplasty (PTA) is shown in a realistic dynamic human-sized leg model.

Spin echo formation in muscle tissue

Determination of the spin echo signal evolution and of transverse relaxation rates is of high importance for microstructural modeling of muscle tissue in magnetic resonance imaging. So far, numerically exact solutions for the NMR signal dynamics in muscle tissue models have been reported only for the gradient echo free induction decay, with spin echo problems usually solved by approximate methods. In this work, we modeled the spin echo signal numerically exact by discretizing the radial dimension of the Bloch-Torrey equation and expanding the angular dependency in terms of even Chebyshev polynomials. This allows us to express the time dependence of the local magnetization as a closed-form matrix expression. Using this method, we were able to accurately capture the spin echo local and total magnetization dynamics. The obtained transverse relaxation rates showed a high concordance with random walker and finite-element simulations. We could demonstrate that in cases of smaller diffusion coefficients, the commonly used strong collision approximation significantly underestimates the true value considerably. Instead, the limiting behavior in this regime is correctly described either by the full solution or by the slow diffusion approximation. Experimentally measured transverse relaxation rates of a mouse limb muscle showed an angular dependence in accordance with the theoretical prediction.

Measurement of the Spectral Shape of the β-Decay of ^{137}Xe to the Ground State of ^{137}Cs in EXO-200 and Comparison with Theory

We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden nonunique β-decay transition ^{137}Xe(7/2^{-})→^{137}Cs(7/2^{+}). The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultralow background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal to background ratio of more than 99 to 1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden nonunique β-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.

Search for Neutrinoless Double-β Decay with the Complete EXO-200 Dataset

A search for neutrinoless double-β decay (0νββ) in ^{136}Xe is performed with the full EXO-200 dataset using a deep neural network to discriminate between 0νββ and background events. Relative to previous analyses, the signal detection efficiency has been raised from 80.8% to 96.4±3.0%, and the energy resolution of the detector at the Q value of ^{136}Xe 0νββ has been improved from σ/E=1.23% to 1.15±0.02% with the upgraded detector. Accounting for the new data, the median 90% confidence level 0νββ half-life sensitivity for this analysis is 5.0×10^{25}  yr with a total ^{136}Xe exposure of 234.1 kg yr. No statistically significant evidence for 0νββ is observed, leading to a lower limit on the 0νββ half-life of 3.5×10^{25}  yr at the 90% confidence level.

Cognition errors in the treatment course of patients with anastomotic failure after colorectal resection

Background

Cognitive errors have a considerable effect on procedural outcome. They play a major role in situational judgement and decision making, especially during cognitively demanding tasks. As such they need to be considered an important factor in medical and surgical procedures. However, whereas cognitive diagnostic errors are well known, as of yet the occurrence of errors due to cognitive heuristics may have been downplayed, underestimated, or simply been ignored during the course of surgical treatment.

Methods

All colorectal resections with anastomosis in 2015 and 2016 (n = 230) were prospectively screened for anastomotic failure (n = 17/230). During structured Morbidity and Mortality Conferences (MMC) all anastomotic failures were analyzed for both tactical and technical decisions in the pre- and intraoperative setting with potential meaning for the postoperative course, based on the London Protocol. In order to demonstrate the significance of cognitive errors in surgical procedures a structured interview with the individual surgeon was conducted including the video and photo documentation of the individual surgical procedure. The interviews were coded by independent coders who were instructed to identify defined cognitive errors. Inter-coder agreement was calculated using Krippendorff’s alpha.

Results

In 12/17 patients with anastomotic failure after colorectal surgery tactical or technical decisions with potential negative influence on anastomotic healing or the postoperative course were assessed during MMC. In 8/12 procedures a structured interview could be conducted with the operating surgeon. In 7/8 procedures cognitive errors could be identified. In particular we found Anchoring (n = 1), Availability Bias (n = 1), Commission Bias (n = 1), Overconfidence Bias (n = 1), Omission Bias (n = 2) and Sunk Costs (n = 1).

Conclusion

Cognitive errors seem to play an important role during surgical therapy of patients with anastomotic failure after colorectal resection. Consequently, we suggest cognitive errors should attract more interest in research as well as attention in clinical practice.

Blood pressure regulation determined by ambulatory blood pressure profiles in children and adolescents with type 1 diabetes mellitus: Impact on diabetic complications

BACKGROUND

The combination of high blood pressure and hyperglycemia contributes to the development of diabetic complications. Ambulatory monitoring of blood pressure (ABPM) is seen as standard to assess blood pressure (BP) regulation.

OBJECTIVE

We evaluated 24-hour BP regulation in 3529 children with type 1 diabetes, representing 5.6% of the patients <20 years of age documented in the DPV registry, and studied the influence of BP parameters including pulse pressure (PP) and blood pressure variability (BPV) on microalbuminuria (MA) and diabetic retinopathy (DR).

RESULTS

BP was increased in this selected cohort of children with diabetes compared to healthy German controls (standard deviation score (SDS) day: systolic BP (SBP) +0.06, mean arterial pressure (MAP) +0.08, PP +0.3; night: SBP +0.6, diastolic BP +0.6, MAP +0.8), while daytime diastolic BP (SDS -0.2) and dipping of SBP and MAP were reduced (SBP -1.1 SDS, MAP 12.4% vs 19.4%), PP showed reverse dipping (-0.7 SDS). Children with microvascular complications had by +0.1 to +0.75 SDS higher BP parameters, except of nocturnal PP in MA and diurnal and nocturnal PP in DR. Reverse dipping of PP was more pronounced in the children with MA (-5.1% vs -0.8%) and DR (-2.6% vs -1.0%). BP alteration was stronger in girls and increased with age.

CONCLUSION

There is an early and close link between 24-hour blood pressure regulation and the development of diabetic complications not only for systolic, diastolic, and mean arterial BP but also for the derived BP parameter PP and BPV in our selected patients.

AMKL chimeric transcription factors are potent inducers of leukemia

Acute megakaryoblastic leukemia in patients without Down syndrome is a rare malignancy with a poor prognosis. RNA sequencing of fourteen pediatric cases previously identified novel fusion transcripts that are predicted to be pathological including CBFA2T3-GLIS2, GATA2-HOXA9, MN1-FLI and NIPBL-HOXB9. In contrast to CBFA2T3-GLIS2, which is insufficient to induce leukemia, we demonstrate that the introduction of GATA2-HOXA9, MN1-FLI1 or NIPBL-HOXB9 into murine bone marrow induces overt disease in syngeneic transplant models. With the exception of MN1, full penetrance was not achieved through the introduction of fusion partner genes alone, suggesting that the chimeric transcripts possess a unique gain-of-function phenotype. Leukemias were found to exhibit elements of the megakaryocyte erythroid progenitor gene expression program, as well as unique leukemia-specific signatures that contribute to transformation. Comprehensive genomic analyses of resultant murine tumors revealed few cooperating mutations confirming the strength of the fusion genes and their role as pathological drivers. These models are critical for both the understanding of the biology of disease as well as providing a tool for the identification of effective therapeutic agents in preclinical studies.

Graph theory in brain-to-brain connectivity: A simulation study and an application to an EEG hyperscanning experiment

Hyperscanning consists in the simultaneous recording of hemodynamic or neuroelectrical signals from two or more subjects acting in a social context. Well-established methodologies for connectivity estimation have already been adapted to hyperscanning purposes. The extension of graph theory approach to multi-subjects case is still a challenging issue. In the present work we aim to test the ability of the currently used graph theory global indices in describing the properties of a network given by two interacting subjects. The testing was conducted first on surrogate brain-to-brain networks reproducing typical social scenarios and then on real EEG hyperscanning data recorded during a Joint Action task. The results of the simulation study highlighted the ability of all the investigated indexes in modulating their values according to the level of interaction between subjects. However, only global efficiency and path length indexes demonstrated to be sensitive to an asymmetry in the communication between the two subjects. Such results were, then, confirmed by the application on real EEG data. Global efficiency modulated, in fact, their values according to the inter-brain density, assuming higher values in the social condition with respect to the non-social condition.

First in vivo traveling wave magnetic particle imaging of a beating mouse heart

Magnetic particle imaging (MPI) is a non-invasive imaging modality for direct detection of superparamagnetic iron-oxide nanoparticles based on the nonlinear magnetization response of magnetic materials to alternating magnetic fields. This highly sensitive and rapid method allows both a quantitative and a qualitative analysis of the measured signal. Since the first publication of MPI in 2005 several different scanner concepts have been presented and in 2009 the first in vivo imaging results of a beating mouse heart were shown. However, since the field of view (FOV) of the first MPI-scanner only covers a small region several approaches and hardware enhancements were presented to overcome this issue and could increase the FOV on cost of acquisition speed. In 2014 an alternative scanner concept, the traveling wave MPI (TWMPI), was presented, which allows scanning an entire mouse-sized volume at once. In this paper the first in vivo imaging results using the TWMPI system are presented. By optimizing the trajectory the temporal resolution is sufficiently high to resolve the dynamic of a beating mouse heart.

Dentin Dysplasia in Notum Knockout Mice

Secreted WNT proteins control cell differentiation and proliferation in many tissues, and NOTUM is a secreted enzyme that modulates WNT morphogens by removing a palmitoleoylate moiety that is essential for their activity. To better understand the role this enzyme in development, the authors produced NOTUM-deficient mice by targeted insertional disruption of the Notum gene. The authors discovered a critical role for NOTUM in dentin morphogenesis suggesting that increased WNT activity can disrupt odontoblast differentiation and orientation in both incisor and molar teeth. Although molars in Notum-/- mice had normal-shaped crowns and normal mantle dentin, the defective crown dentin resulted in enamel prone to fracture during mastication and made teeth more susceptible to endodontal inflammation and necrosis. The dentin dysplasia and short roots contributed to tooth hypermobility and to the spread of periodontal inflammation, which often progressed to periapical abscess formation. The additional incidental finding of renal agenesis in some Notum -/- mice indicated that NOTUM also has a role in kidney development, with undiagnosed bilateral renal agenesis most likely responsible for the observed decreased perinatal viability of Notum-/- mice. The findings support a significant role for NOTUM in modulating WNT signaling pathways that have pleiotropic effects on tooth and kidney development.

GREMLIN 2 Mutations and Dental Anomalies

Isolated or nonsyndromic tooth agenesis or hypodontia is the most common human malformation. It has been associated with mutations in MSX1, PAX9, EDA, AXIN2, EDAR, EDARADD, and WNT10A. GREMLIN 2 (GREM2) is a strong bone morphogenetic protein (BMP) antagonist that is known to regulate BMPs in embryogenesis and tissue development. Bmp4 has been shown to have a role in tooth development. Grem2(-/-) mice have small, malformed maxillary and mandibular incisors, indicating that Grem2 has important roles in normal tooth development. Here, we demonstrate for the first time that GREM2 mutations are associated with human malformations, which include isolated tooth agenesis, microdontia, short tooth roots, taurodontism, sparse and slow-growing hair, and dry and itchy skin. We sequenced WNT10A, WNT10B, MSX1, EDA, EDAR, EDARADD, AXIN2, and PAX9 in all 7 patients to rule out the effects of other ectodermal dysplasias and other tooth-related genes and did not find mutations in any of them. GREM2 mutations exhibit variable expressivity even within the same families. The inheritance is autosomal dominant with incomplete penetrance. The expression of Grem2 during the early development of mouse teeth and hair follicles and the evaluation of the likely effects of the mutations on the protein structure substantiate these new findings.

Nephronophthisis and retinal degeneration in tmem218-/- mice: a novel mouse model for Senior-Løken syndrome?

Mice deficient in TMEM218 (Tmem218(-/-) ) were generated as part of an effort to identify and validate pharmaceutically tractable targets for drug development through large-scale phenotypic screening of knockout mice. Routine diagnostics, expression analysis, histopathology, and electroretinogram analyses completed on Tmem218(-/-) mice identified a previously unknown role for TMEM218 in the development and function of the kidney and eye. The major observed phenotypes in Tmem218(-/-) mice were progressive cystic kidney disease and retinal degeneration. The renal lesions were characterized by diffuse renal cyst development with tubulointerstitial nephropathy and disruption of tubular basement membranes in essentially normal-sized kidneys. The retinal lesions were characterized by slow-onset loss of photoreceptors, which resulted in reduced electroretinogram responses. These renal and retinal lesions are most similar to those associated with nephronophthisis (NPHP) and retinitis pigmentosa in humans. At least 10% of NPHP cases present with extrarenal conditions, which most often include retinal degeneration. Senior-Løken syndrome is characterized by the concurrent development of autosomal recessive NPHP and retinitis pigmentosa. Since mutations in the known NPHP genes collectively account for only about 30% of NPHP cases, it is possible that TMEM218 could be involved in the development of similar ciliopathies in humans. In reviewing all other reported mouse models of NPHP, we suggest that Tmem218(-/-) mice could provide a useful model for elucidating the pathogenesis of cilia-associated disease in both the kidney and the retina, as well as in developing and testing novel therapeutic strategies for Senior-Løken syndrome.

Malformation of Incisor Teeth in Grem2-/- Mice

GREMLIN 2 ( GREM2)—formerly, protein related to Dan and cerberus ( PRDC)—is a potent antagonist of the bone morphogenetic proteins 2 and 4, but little else in known about its functions. We found that Grem2-/- mice developed small deformed mandibular and maxillary incisors, indicating that GREMLIN2 is required for normal tooth morphogenesis. Although DEXA scans suggested that bone mineral density might be increased in Grem2-/- mice, histology did not reveal any evident bone phenotype. Grem2-/- mice did not display any other notable phenotypes evaluated in a high-throughput screening process that encompassed a range of immunologic, metabolic, ophthalmic, and behavioral parameters. Our findings indicate that Grem2 can be added to the growing list of genes that affect tooth development in mice.

Investigating the neural basis of cooperative joint action. An EEG hyperscanning study

The aim of the present study is to investigate the neurophysiological basis of the cognitive functions underlying the execution of joint actions, by means of the recent technique called hyperscanning. Neuroelectrical hyperscanning is based on the simultaneous recording of brain activity from multiple subjects and includes the analysis of the functional relation between the brain activity of all the interacting individuals. We recorded simultaneous high density electroencephalography (hdEEG) from 16 pairs of subjects involved in a computerized joint action paradigm, with controlled levels of cooperation. Results of cortical connectivity analysis returned significant differences, in terms of inter-brain functional causal links, between the condition of cooperative joint action and a condition in which the subjects were told they were interacting with a PC, while actually interacting with another human subject. Such differences, described by selected brain connectivity indices, point toward an integration between the two subjects' brain activity in the cooperative condition, with respect to control conditions.

Evolutionary and dispersal history of Eurasian house mice Mus musculus clarified by more extensive geographic sampling of mitochondrial DNA

We examined the sequence variation of mitochondrial DNA control region and cytochrome b gene of the house mouse (Mus musculus sensu lato) drawn from ca. 200 localities, with 286 new samples drawn primarily from previously unsampled portions of their Eurasian distribution and with the objective of further clarifying evolutionary episodes of this species before and after the onset of human-mediated long-distance dispersals. Phylogenetic analysis of the expanded data detected five equally distinct clades, with geographic ranges of northern Eurasia (musculus, MUS), India and Southeast Asia (castaneus, CAS), Nepal (unspecified, NEP), western Europe (domesticus, DOM) and Yemen (gentilulus). Our results confirm previous suggestions of Southwestern Asia as the likely place of origin of M. musculus and the region of Iran, Afghanistan, Pakistan, and northern India, specifically as the ancestral homeland of CAS. The divergence of the subspecies lineages and of internal sublineage differentiation within CAS were estimated to be 0.37-0.47 and 0.14-0.23 million years ago (mya), respectively, assuming a split of M. musculus and Mus spretus at 1.7 mya. Of the four CAS sublineages detected, only one extends to eastern parts of India, Southeast Asia, Indonesia, Philippines, South China, Northeast China, Primorye, Sakhalin and Japan, implying a dramatic range expansion of CAS out of its homeland during an evolutionary short time, perhaps associated with the spread of agricultural practices. Multiple and non-coincident eastward dispersal events of MUS sublineages to distant geographic areas, such as northern China, Russia and Korea, are inferred, with the possibility of several different routes.

Search for neutrinoless double-beta decay in 136Xe with EXO-200

We report on a search for neutrinoless double-beta decay of 136Xe with EXO-200. No signal is observed for an exposure of 32.5 kg yr, with a background of ∼1.5×10(-3)  kg(-1) yr(-1)  keV(-1) in the ±1σ region of interest. This sets a lower limit on the half-life of the neutrinoless double-beta decay T(1/2)(0νββ)(136Xe)>1.6×10(25)  yr (90% C.L.), corresponding to effective Majorana masses of less than 140-380 meV, depending on the matrix element calculation.

Amelogenesis imperfecta and other biomineralization defects in Fam20a and Fam20c null mice

The FAM20 family of secreted proteins consists of three members (FAM20A, FAM20B, and FAM20C) recently linked to developmental disorders suggesting roles for FAM20 proteins in modulating biomineralization processes. The authors report here findings in knockout mice having null mutations affecting each of the three FAM20 proteins. Both Fam20a and Fam20c null mice survived to adulthood and showed biomineralization defects. Fam20b (-/-) embryos showed severe stunting and increased mortality at E13.5, although early lethality precluded detailed investigations. Physiologic calcification or biomineralization of extracellular matrices is a normal process in the development and functioning of various tissues (eg, bones and teeth). The lesions that developed in teeth, bones, or blood vessels after functional deletion of either Fam20a or Fam20c support a significant role for their encoded proteins in modulating biomineralization processes. Severe amelogenesis imperfecta (AI) was present in both Fam20a and Fam20c null mice. In addition, Fam20a (-/-) mice developed disseminated calcifications of muscular arteries and intrapulmonary calcifications, similar to those of fetuin-A deficient mice, although they were normocalcemic and normophosphatemic, with normal dentin and bone. Fam20a gene expression was detected in ameloblasts, odontoblasts, and the parathyroid gland, with local and systemic effects suggesting both local and/or systemic effects for FAM20A. In contrast, Fam20c (-/-) mice lacked ectopic calcifications but were severely hypophosphatemic and developed notable lesions in both dentin and bone to accompany the AI. The bone and dentin lesions, plus the marked hypophosphatemia and elevated serum alkaline phosphatase and FGF23 levels, are indicative of autosomal recessive hypophosphatemic rickets/osteomalacia in Fam20c (-/-) mice.

Cryptogenic Organizing Pneumonia in Tomm5–/– Mice

Almost all mitochondrial proteins are encoded in the nuclear DNA and synthesized in the cytosol as pre-proteins. There is a protein translocase located in the mitochondrial outer membrane that transports mitochondrial pre-proteins into mitochondria. The central component of this translocase of the outer mitochondrial membrane (TOMM) complex is TOMM40, and TOMM5 is one of three small subunits associated with TOMM40. Translocase of outer mitochondrial membrane 5 homolog ( Tomm5–/–) knockout mice demonstrated an unexpected lung-specific phenotype characterized by widespread intra-alveolar fibrosis. Although TOMM5-deficient mice tested normal in a very broad range of phenotyping assays, they displayed histopathological lesions in the lung that were consistent with those reported in humans with cryptogenic organizing pneumonia (COP), which is also known as bronchiolitis obliterans organizing pneumonia (BOOP). The lesions had a patchy distribution in the lung and were characterized by the presence of intraluminal fibrogenic buds consisting of fibroblasts and myofibroblasts embedded in a loose connective tissue matrix that occupied the lumina of alveoli and alveolar ducts, with preservation of underlying alveolar architecture. In addition to macrophages, which were numerous in affected and surrounding alveoli, eosinophils comprised the most common and widespread inflammatory cell. Taken together, the findings in Tomm5–/– mice provide yet another example of the value of histopathology as a baseline assay in high-throughput phenotyping systems.

Observation of two-neutrino double-beta decay in 136Xe with the EXO-200 detector

We report the observation of two-neutrino double-beta decay in (136)Xe with T(1/2) = 2.11 ± 0.04(stat) ± 0.21(syst) × 10(21) yr. This second-order process, predicted by the standard model, has been observed for several nuclei but not for (136)Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.

Congenital Hydrocephalus in Genetically Engineered Mice

There is evidence that genetic factors play a role in the complex multifactorial pathogenesis of hydrocephalus. Identification of the genes involved in the development of this neurologic disorder in animal models may elucidate factors responsible for the excessive accumulation of cerebrospinal fluid in hydrocephalic humans. The authors report here a brief summary of findings from 12 lines of genetically engineered mice that presented with autosomal recessive congenital hydrocephalus. This study illustrates the value of knockout mice in identifying genetic factors involved in the development of congenital hydrocephalus. Findings suggest that dysfunctional motile cilia represent the underlying pathogenetic mechanism in 8 of the 12 lines ( Ulk4, Nme5, Nme7, Kif27, Stk36, Dpcd, Ak7, and Ak8). The likely underlying cause in the remaining 4 lines ( RIKEN 4930444A02, Celsr2, Mboat7, and transgenic FZD3) was not determined, but it is possible that some of these could also have ciliary defects. For example, the cerebellar malformations observed in RIKEN 4930444A02 knockout mice show similarities to a number of developmental disorders, such as Joubert, Meckel-Gruber, and Bardet-Biedl syndromes, which involve mutations in cilia-related genes. Even though the direct relevance of mouse models to hydrocephalus in humans remains uncertain, the high prevalence of familial patterns of inheritance for congenital hydrocephalus in humans suggests that identification of genes responsible for development of hydrocephalus in mice may lead to the identification of homologous modifier genes and susceptibility alleles in humans. Also, characterization of mouse models can enhance understanding of important cell signaling and developmental pathways involved in the pathogenesis of hydrocephalus.

Cardiomyopathy in α-Kinase 3 (ALPK3)–Deficient Mice

Cardiomyopathy developed in mice deficient for α-kinase 3 (ALPK3), a nuclear kinase previously implicated in the differentiation of cardiomyocytes. Alpk3–/– mice were produced according to normal Mendelian ratios and appeared normal except for a nonprogressive cardiomyopathy that had features of both hypertrophic and dilated forms of cardiomyopathy. Cardiac hypertrophy in Alpk3–/– mice was characterized by increased thickness of both left and right ventricular (LV and RV) walls and by markedly increased heart weight and increased heart weight/body weight and heart weight/tibia length ratios. Magnetic resonance imaging studies confirmed the increased thickness in both septal and LV free walls at end-diastole, although there was no significant change in LV wall thickness at end-systole. Myocardial hypertrophy was the predominant feature in Alpk3–/– mice, but several changes more typically associated with dilated cardiomyopathy included a marked increase in end-diastolic and end-systolic LV volume, as well as reduced cardiac output, stroke volume, and ejection fractions, suggesting LV chamber dilation. Magnetic resonance imaging showed a 50% reduction in both septal and free wall LV contractility in Alpk3–/– mice. Interstitial fibrosis and inflammation were notably absent in Alpk3–/– mice; however, light and electron microscopy revealed altered cardiomyocyte architecture, characterized by reduced numbers of abnormal intercalated discs being associated with mild disarray of myofibrils. These lesions could account for the impaired contractility of the myofibrillar apparatus and contribute to the pathogenesis of cardiomyopathy in Alpk3–/– mice.

Pathology of congenital generalized lipodystrophy in Agpat2-/- mice

Congenital generalized lipodystrophy (CGL) comprises a heterogeneous group of rare diseases associated with partial or total loss of adipose tissue. Of these, autosomal recessive Berardinelli-Seip congenital lipodystrophy (BSCL) is characterized by the absence of metabolically active subcutaneous and visceral adipose tissues. Metabolic abnormalities associated with lipodystrophy include insulin resistance, hypertriglyceridemia, hepatic steatosis, and diabetes. One form of BSCL has been linked to genetic mutations affecting the lipid biosynthetic enzyme 1-acyl-sn-glycerol 3-phosphate O-acyltransferase 2 (AGPAT2), which is highly expressed in adipose tissue. Precisely how AGPAT2 deficiency causes lipodystrophy remains unresolved, but possible mechanisms include impaired lipogenesis (triglyceride synthesis and storage), blocked adipogenesis (differentiation of preadipocytes to adipocytes), or apoptosis/necrosis of adipocytes. Agpat2(-/-) mice share important pathophysiologic features of CGL previously reported in humans. However, the small white adipose tissue (WAT) depots consisting largely of amoeboid adipocytes with microvesiculated basophilic cytoplasm showed that adipogenesis with deficient lipogenesis was present in all usual locations. Although well-defined lobules of brown adipose tissue (BAT) were present, massive necrosis resulted in early ablation of BAT. Although necrotic or apoptotic adipocytes were not detected in WAT of 10-day-old Agpat2(-/-), the absence of adipocytes in aged mice indicates that these cells must undergo necrosis/apoptosis at some point. Another significant finding in aged lipodystrophic mice was massive pancreatic islet hypertrophy in the face of chronic hyperglycemia, which suggests that glucotoxicity is insufficient by itself to cause β-cell loss and that adipocyte-derived factors help regulate total β-cell mass.

Histopathological and neurological features of Atg4b knockout mice

This investigation found that genetic inactivation of mouse Atg4b, 1 of the 4 mammalian homologs of the autophagy-related gene Atg4, resulted in amorphous globular bodies in the neuropil of the deep cerebellar nuclei and adjacent vestibular nuclei but nowhere else in the brain or other tissues. The spheroid-like bodies in the deep cerebellar and vestibular nuclei showed heterogeneous composition, reactivity with anti-ubiquitin antibody, and staining characteristics of proteinaceous material. Atg4b-deficient (Atg4b (-/-)) mice also showed a mild but measurable impairment of motor performance on the Rotarod. Atg4b (-/-) mice produced by breeding heterozygous parents were produced at a slightly lower than expected ratio to heterozygous and wild-type siblings but showed no other clear abnormalities in a battery of screening tests. These findings appear to be different than those reported for inactivation of other Atg4 homologs, suggesting that these homologs have tissue-specific functions beyond redundancy.

An alternative splicing variant in Clcn7-/- mice prevents osteopetrosis but not neural and retinal degeneration

The ubiquitously expressed chloride channel 7 (CLCN7) is present within the ruffled border of osteoclasts. Mutations in the CLCN7 gene in humans (homologous to murine Clcn7) are responsible for several types of osteopetrosis in humans, and deficiencies in CLCN7 can present with retinal degeneration and a neuronal storage disease. A previously reported Clcn7(-/-) mouse showed diffuse osteopetrosis accompanied by severe retinal and neuronal degeneration. In contrast, the authors produced a novel Clcn7(-/-) mutant where mice did not develop osteopetrosis but still developed lethal neural and retinal degeneration. In these mice, there was a rapid progressive loss of the outer nuclear layer and photoreceptor layers of the retina. Laminar degeneration and necrosis of neurons in layers IV and V of the cerebral cortex and in the CA2/CA3 regions of the hippocampus were associated with intraneuronal accumulations of autofluorescent granules (periodic acid-Schiff positive). The extensive reactive gliosis was always associated with the accumulation of intraneuronal cytoplasmic material. The authors found, through quantitative real time polymerase chain reaction analyses, that an alternate Clcn7 transcript (previously identified only in bone marrow) showed minimal expression in the brain and eye but moderate expression in bone, which correlates with rescue of the osteopetrotic phenotype in the face of continued retinal and neuronal degeneration. Findings in this knockout mouse model prove that osteopetrotic compression of the brain is not responsible for neuronal and retinal degeneration in CLCN7-deficient mice; rather, they suggest that neurotoxicity is most likely due to lysosomal dysfunction as a result of the functional lack of this chloride channel in the central nervous system and eye.

Tubulin tyrosine ligase-like 1 deficiency results in chronic rhinosinusitis and abnormal development of spermatid flagella in mice

Tubulin tyrosine ligase-like 1 (TTLL1) protein is a member of the tubulin tyrosine ligase superfamily of proteins that are involved in the posttranslational polyglutamylation of tubulin in axonemal microtubules within cilia and flagella. To investigate the physiological role of TTLL1, the authors generated mice with a gene trap mutation in the Ttll1 gene that provide confirmation in a mammalian model that polyglutamylation plays an important role in some ciliary and flagellar functions. For the first time, mice homozygous for the Ttll1 mutation exhibited accumulations of exudates in the nasal passages and sinuses, rhinosinusitis, otitis media, and male infertility. In homozygous mutant male mice, abnormal sperm morphology and function were characterized by shortened or absent flagella and immotility. Although homozygous mutant males were infertile, the females were fertile. These findings are consistent with a diagnosis of primary ciliary dyskinesia (PCD) resulting from ciliary dysfunction. They indicate that Ttll1 is essential for normal motility of respiratory cilia and the biogenesis and function of sperm flagella but that the defect does not result in the hydrocephalus or laterality defects often seen in other forms of PCD. The absence of early-onset lethal hydrocephalus in Ttll1-mutant mice may enable studies to evaluate the long-term effects of PCD in the respiratory system of mice. Although no mutations in the orthologous gene have been linked with PCD in humans, investigating the role of TTLL1 and polyglutamylation of tubulin in cilia and flagella should advance an understanding of the biogenesis and function of these organelles in mammals and have potential diagnostic and therapeutic applications.

Spontaneous acute tumor lysis syndrome as a cause of early deaths in short-term carcinogenicity studies using p53 +/- mice

Acute tumor lysis syndrome (ATLS) is a potentially lethal condition precipitated by the massive release of intracellular components such as nucleic acids, potassium, and phosphorus, following a rapid and widespread lysis of tumor cells. Herein, the authors describe the high incidence and characteristic histopathologic lesions of acute ATLS in p53-deficient mice used in 2 short-term carcinogenicity studies. ATLS was a frequent cause of early death in p53 (+/-) mice in these studies and was consistently associated with the presence of disseminated lymphoma and leukemia. Although a heavy tumor burden and leukemia were present in all affected mice, the absence of ATLS in other mice with equally severe lymphoma and leukemia indicates that these tumor burdens are necessary but insufficient to cause ATLS in mice. The hallmark histopathologic findings of ATLS in mice are the disseminated microemboli composed of nuclear and cytoplasmic debris derived from lysed tumor cells. The mechanical obstruction of capillary beds by these microemboli appeared to be the proximate cause of the early deaths of mice in these studies. Microemboli may contribute to the pathogenesis of acute renal failure and other clinical signs associated with ATLS in other species. Recognition of ATLS in laboratory animals is critical in studies intended to evaluate the efficacy and/or toxicity of anticancer treatments, where early deaths due to ATLS might otherwise be attributed to test article toxicity. Further studies on the role of microemboli in the pathogenesis of ATLS may elucidate pathogenetic mechanisms and lead to improved approaches to clinical management and treatment of this potentially lethal condition.

Situs inversus in Dpcd/Poll-/-, Nme7-/- , and Pkd1l1-/- mice

Situs inversus (SI) is a congenital condition characterized by left-right transposition of thoracic and visceral organs and associated vasculature. The usual asymmetrical positioning of organs is established early in development in a transient structure called the embryonic node. The 2-cilia hypothesis proposes that 2 kinds of primary cilia in the embryonic node determine left-right asymmetry: motile cilia that generate a leftward fluid flow, and immotile mechanosensory cilia that respond to the flow. Here, we describe 3 mouse SI models that provide support for the 2-cilia hypothesis. In addition to having SI, Dpcd/Poll(-/-) mice (for: deleted in a mouse model of primary ciliary dyskinesia) and Nme7(-/-) mice (for: nonmetastatic cells 7) had lesions consistent with deficient ciliary motility: Hydrocephalus, sinusitis, and male infertility developed in Dpcd/Poll(-/-) mice, whereas hydrocephalus and excessive nasal exudates were seen in Nme7(-/-) mice. In contrast, the absence of respiratory tract lesions, hydrocephalus, and male infertility in Pkd1l1(-/-) mice (for: polycystic kidney disease 1 like 1) suggested that dysfunction of motile cilia was not involved in the development of SI in this line. Moreover, the gene Pkd1l1 has considerable sequence similarity with Pkd1 (for: polycystic kidney disease 1), which encodes a protein (polycystin-1) that is essential for the mechanosensory function of immotile primary cilia in the kidney. The markedly reduced viability of Pkd1l1(-/-) mice is somewhat surprising given the absence of any detected abnormalities (other than SI) in surviving Pkd1l1(-/-) mice subjected to a comprehensive battery of phenotype-screening exams. However, the heart and great vessels of Pkd1l1(-/-) mice were not examined, and it is possible that the decreased viability of Pkd1l1(-/-) mice is due to undiagnosed cardiovascular defects associated with heterotaxy.

[A new procedure for the estimation of physical fitness of patients during clinical rehabilitation using the 6-minutes walk test]

AIMS OF THE INVESTIGATION: The repetition of the 6-minutes walk test (6 MWT) in older patients is frequently performed in order to document the maximal walking distance, although it is not recommended in any guidelines on exercise tests and although there is common consent to save clinical resources in terms of time and staff. Therefore, we have examined whether and to what extent the repetition of the walk tests helps patients to get more familiar with this kind of exercise test. Thus the acquired physiological data should reliably describe the physical fitness of the patients at the beginning and at the end of their clinical rehabilitation.

METHODS

35 patients performed their walk tests before and after 3 - 4 weeks of clinical rehabilitation. Each test has been repeated after one hour of recovery. The patients were instructed to walk during 6 minutes as fast as possible. They were equipped with a mobile pulse oximeter for recording oxygen saturation and heart rate. The distance, S, and the heart rate, fc, were measured. Measurements were performed every 30 seconds and recorded. The efficiency, E (E = S/6/fc), was calculated as the ratio of distance per minute and the mean heart rate during the test.

RESULTS

In the first test the patients walked 416 +/- 63 m at a heart rate of 104.7 +/- 15.7 beats/min, in the first repeated test 454 +/- 71 m at a heart of 106.3 +/- 17.4 beats/min. In the second test, after clinical therapy, they walked 438 +/- 58 m at a heart rate of 106.3 +/- 17.4 beats/min, in the second repeated test 473 +/- 56 m at 108.6 +/- 13.2/min. The difference of the walking distances of the tests at the entrance were found to be 38.4 +/- 26.2 m (+ 9.3 +/- 6.2%), at the end of clinical rehabilitation 35 +/- 26 m (+ 8.4 +/- 6.4%). Both differences are found to be independent from the distance of the first test. They are not significantly different. The efficiency was not significantly different in the initial and final test (0.673 +/- 0.129 and 0.689 +/- 0.085 m/beat, respectively). The difference in efficiency, when repeating the tests at the beginning, was: 0.053 +/- 0.062 m/beat; at the end of the rehabilitation: 0.042 +/- 0.047 m/beat. They are found to be similar.

CONCLUSIONS

The distances the patients walked in the repeated tests at the entrance and at the end of their clinical rehabilitation were, besides the calculated efficiency, E, significantly increased. However, the increases in distance and efficiency are identical on both occasions, therefore the repetition delivers no further information. The test should be performed without repetitions in clinical routine investigations. The patient's performance in the second walk test with an unchanged distance at a lower heart rate reveals an improved physical fitness. This is solely described by an increase of efficiency, E. Therefore the introduction of E is a suitable measure of the quantified effect of exercise training, even if the patient is not cooperative during the tests. E is proved to be a suitable estimation for the assessment of physical fitness as a benefit of clinical rehabilitation.

Comparative pathology of murine mucolipidosis types II and IIIC

UDP-GlcNAc: lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase) is an alpha(2)beta(2)gamma(2) hexameric enzyme that catalyzes the first step in the synthesis of the mannose 6-phosphate targeting signal on lysosomal hydrolases. In humans, mutations in the gene encoding the alpha/beta subunit precursor give rise to mucolipidosis II (MLII), whereas mutations in the gene encoding the gamma subunit cause the less severe mucolipidosis IIIC (MLIIIC). In this study we describe the phenotypic, histologic, and serum lysosomal enzyme abnormalities in knockout mice lacking the gamma subunit and compare these findings to those of mice lacking the alpha/beta subunits and humans with MLII and MLIIIC. We found that both lines of mutant mice had elevated levels of serum lysosomal enzymes and cytoplasmic alterations in secretory cells of several exocrine glands; however, lesions in gamma-subunit deficient (Gnptg(-/-)) mice were milder and more restricted in distribution than in alpha/beta-subunit deficient (Gnptab(-/-)) mice. We found that onset, extent, and severity of lesions that developed in these two different knockouts correlated with measured lysosomal enzyme activity; with a more rapid, widespread, and severe storage disease phenotype developing in Gnptab(-/-) mice. In contrast to mice deficient in the alpha/beta subunits, the mice lacking the gamma subunits were of normal size, lacked cartilage defects, and did not develop retinal degeneration. The milder disease in the gamma-subunit deficient mice correlated with residual synthesis of the mannose 6-phosphate recognition marker. Of significance, neither strain of mutant mice developed cytoplasmic vacuolar inclusions in fibrocytes or mesenchymal cells (I-cells), the characteristic lesion associated with the prominent skeletal and connective tissue abnormalities in humans with MLII and MLIII. Instead, the predominant lesions in both lines of mice were found in the secretory epithelial cells of several exocrine glands, including the pancreas, and the parotid, submandibular salivary, nasal, lacrimal, bulbourethral, and gastric glands. The absence of retinal and chondrocyte lesions in Gnptg(-/-) mice might be attributed to residual beta-glucuronidase activity. We conclude that mice lacking either alpha/beta or gamma subunits displayed clinical and pathologic features that differed substantially from those reported in humans having mutations in orthologous genes.

Ectonucleoside triphosphate diphosphohydrolase type 5 (Entpd5)-deficient mice develop progressive hepatopathy, hepatocellular tumors, and spermatogenic arrest

Ectonucleoside triphosphate diphosphohydrolase type 5 (ENTPD5, also CD39L4) is a soluble enzyme that hydrolyzes purine nucleoside diphosphates. Genetic inactivation of ENTPD5 in mice (Entpd5(-/-)) resulted in 2 major histopathologic lesions: hepatopathy and aspermia. The hepatopathy was progressive and characterized by centrilobular hepatocyte hypertrophy, oval cell proliferation, bile staining of Kupffer cells, and hepatocyte degeneration with increasing incidence and severity of degenerative lesions, development of multiple foci of cellular alteration, and hepatocellular neoplasia with age. Greatly increased proliferation of hepatocytes in young adult as well as aged Entpd5(-/-) mice was demonstrated by Ki67 immunohistochemistry and 5'-bromo-3'-deoxyuridine incorporation. Of 15 Entpd5(-/-) mice between 44 and 69 weeks of age, all showed foci of cellular alteration in the liver, and at least 6 of 15 developed hepatocellular carcinoma (HCC), hepatocellular adenoma, or both. Significantly, none of these lesions were observed in 13 wild-type Entpd5(+/+) littermates. These findings, combined with the historically low incidence (about 5%) of HCC in mice up to 2 years of age with the same genetic background, strongly suggest that loss of Entpd5 promotes hepatocellular neoplasia in mice. In humans, ENTPD5 has been found to be identical to the PCPH proto-oncogene, and dysregulation of this gene has been demonstrated in some human cancers. This mouse model could contribute to the understanding of the influence of ENTPD5/PCPH on cellular proliferation and neoplasia.

Testis size, sperm characteristics and testosterone concentrations in four species of shrews (Mammalia, Soricidae)

The aim of this study was to establish and compare the sperm characteristics in four shrew species in the context of the sperm competition hypothesis. As expected, the large relative testis size in promiscuous species was associated with a high number of cauda epididymal spermatozoa and a high concentration of circulating testosterone. In addition, in Sorex and Neomys, species with high intensity of sperm competition, the spermatozoa stored in cauda epididymis were characterized by high percentage of progressive motility whereas in Crocidura and Suncus, the cauda epididymal spermatozoa were motile but with very low percentage of progressive motility. This capability is achieved only following the passage through the vas gland, a specialized region for sperm storage located along the vas deferens in these shrew species. The hypothesis that sperm competition is positively correlated with spermatozoa length could not be confirmed. In Crocidura and Suncus, the total sperm length is increased by the large sperm head due to a big acrosome. This trait, specific to the subfamily Crocidurinae, may results from a selective pressure independent of the context of sperm competition, related to a specific, but as yet unclear role, for the acrosome during the fertilization.