Evaluation and implications of mitral regurgitation using cMRI in patients with hypertrophic cardiomyopathy

OBJECTIVE

Mitral regurgitation (MR) represents an important feature in patients with hypertrophic cardiomyopathy (HCM) due to left ventricular outflow tract (LVOT) obstruction and mitral valve systolic anterior motion (SAM). Mitral valve anatomical variants associated with HCM also contribute to the severity of MR. The aim of this study is to evaluate MR severity and its correlation with different parameters in patients with HCM using cardiac magnetic resonance imaging (cMRI).

PATIENTS AND METHODS

130 patients with HCM underwent cMRI. Parameters assessed for the quantification of MR severity were mitral regurgitation volume (MRV) and mitral regurgitation fraction (MRF). cMRI was also used to characterize LV function, left atrium volume (LAV) index, filling pressures and structural abnormalities associated with HCM, all in correlation to MR.

RESULTS

Patients with HCM had mild (26.9%), moderate (52.3%) or severe (20.7%) MR. Most relevant parameters related to MR severity were MRV and MRF; other parameters with strong correlation with MR were LAV index and E/E' ratio, both increasing with its severity. Patients with LVOT obstruction had more severe MR (70.3%), 79% of them due to SAM. LV ejection fraction (LVEF) increased proportionally with the severity of MR, while LV strain (LAS) was inversely correlated with it. Independent predictors for quantifying the severity of MR, after the adjustment for covariates, were MRV, MRF, SAM, LAV index and E/E'.

CONCLUSIONS

cMRI can accurately assess MR in patients with HCM, especially by using novel indicators, MRV and MRF respectively, along with LAV index and E/E' ratio. Severe MR, due to SAM, is more frequent in the obstructive form of HCM (HOCM). Also, the severity of MR is significantly associated with significantly associated with MRV, MRF, LAV index and E/E' ratio.

Left ventricular longitudinal contraction impacts the left atrial appendage function and the occurrence of thromboembolic events in patients with atrial fibrillation

Introduction

Previous research has revealed a relationship between left ventricular (LV) function and incidence of stroke in atrial fibrillation (AF) but the mechanism remains unknown.

Purpose

Given that the left atrial appendage (LAA) is located in the vicinity of the LV base we hypothesized that the LV longitudinal contraction has an impact on the LAA function, LAA thrombus (LAAT) formation, and occurrence of ischemic stroke (Figure 1A). The aim of this study was to investigate this phenomenon using transesophageal echocardiography (TEE).

Material and methods

We included in our study 105 consecutive patients (age 59±11; 55 men) undergoing TEE-guided cardioversion for AF. LV longitudinal function was assessed using the mitral annulus plane systolic excursion (MAPSE). LAA function was evaluated using the LAA emptying velocity (LAAEV) and LAA ejection fraction (LAAEF) (Figure 1B). The presence LAAT and spontaneous echo contrast (SEC) were evaluated as well.

Results

Our patients had a median CHADS2vasc score = 3 (IQR 2–4), LVEF=50±11%, and MAPSE=7.3±1.7mm. MAPSE showed a positive significant correlation with both LAAEV (r=0.34; p<0.01) and LAAEF (r=0.23; p<0.05) (Figure 2). LVEF correlated significantly with LAAEV (r=0.42, p<0.01), and LAA area (r=−0.34; p<0.05), respectively. Additionally, patients who exhibited SEC had significantly lower LAAEF as well as LAAEV when compared with patients without SEC: 31±12% vs 38±12% P=0.022 and 35±18cm/s vs 49±21cm/s P=0.005. Patients who displayed both SEC and LAAT had wider LAA neck when compared to the rest of the group (21.46±3.96mm vs. 18.23±3.78mm; P=0.021). Logistic regression analysis revealed that MAPSE independently predicted the occurrence of ischemic stroke both in univariate and multivariate models that also included the CHADSvasc2 score.

Conclusions

LV longitudinal contraction appears to influence LAA function. This relationship could potentially have an impact on occurrence of thromboembolic events in patients with atrial fibrillation.

Funding Acknowledgement

Type of funding sources: None.

A state of the art review of isochoric cryopreservation and cryoprotectants

There is a developing enthusiasm for discovering new methods, cryoprotectants, systems and devices for cells, tissues, and organ preservation in medicine, in sub-zero temperature conditions and a growing interest in developing more efficient and economical methods for long-term preservation of food in a frozen state. Most of the preservation protocols currently used in medicine and food preservation involve the use of atmospheric pressure, and temperatures lower than normal body temperature in medicine, or lower than room temperature in the food industry. In this state of the art review, we analyzed the results of a new preservation method that uses an isochoric system. We aimed to offer a clear overview of the potential of this new technology. Firstly, to study the origins of isochoric preservation, we searched using the WoS Database. A search with the world "isochoric" returned 488 results. A more specific search of the term isochoric freezing returned 94 results. From these searches, we selected the 12 most relevant articles and discuss them here in detail. We present an overall characterization and criticism of the current use and potential of this new preservation method that can be used in the medicine and food industry. The main findings indicate encouraging results for the tested biological matter, including for the preservation of food products (e.g. cherries, spinach, potatoes), biological organisms (e.g. Caenorhabditis elegans, Escherichia coli, Listeria, Salmonella typhimurium), organs (e.g. rat hearts), tissues (e.g., tilapia fish filets) or cells (e.g., mammalian cells, pancreatic cells). Accordingly, we conclude that the isochoric system holds huge potential as a new technique in the field of preservation. doi.org/10.54680/fr22410110112.

Policy framework for building integrated care for TB patients in Romania: setting up the scene

Problem

Romania put many efforts for TB control, but despite a constant decreasing trend since almost two decades, TB remained a public health concern, due to the notification rate (highest in EU), the number of resistant cases and the mortality. A national strategy for TB control has been issues for 2015-2020, but its implementation was fragmentary.

Description of the Problem

Benefiting for a series of programs financed by the Global Fund to Fight AIDS, Tuberculosis and Malaria, Romania performed a detailed analysis of the national context, on four pillars (governance and accountability, service delivery, organizational capacity, resources). Quantitative data collected through routine systems were combined to interviews with key informers and focus groups with medical staff, patients and NGOs active in supporting key vulnerable population.

Results

A national framework for strengthening the implementation of the strategy was set up under a Tailored to Transition Global Fund Grant. This framework put together the policy and the technical levels and the civil society sector. Main interventions aimed to strengthen the governance, to improve the procurement and supply mechanism, to develop the ambulatory patient-centered model of care and to create tools for improving the access of key vulnerable population to basic integrated medical and social services.

Lessons

Translating the good practice models developed by the NGO sector to permanent (governmental) structures was difficult due to more rigorous legislative framework for public systems.

Key messages

Multisectoral approach is essential for building integrated care for TB patients. Integration of services should focus not only to complex medical needs, but also to the social ones.

Shape transitions between and within Zr isotopes

The Zirconium isotopes across the N=56,58 neutron sub­shell closures have been of special interest since years, sparked by the near doubly-magic features of 96Zr and the subsequent rapid onset of collectivity with a deformed ground-state structure already in 100Zr. Recent state-of-the-art shell model approaches did not only correctly describe this shape-phase transition in the Zr isotopic chain, but alsothe coexistence of non-collective structures and pronounced collectivity especially in 96,98Zr. Theisotope 98Zr is located on the transition from spherical to deformed ground state structures. We summarize recent experimental work to obtain the B(E2) excitation strengths of the first 2+ state of98Zr, including a new experiment employing the recoil-distance Doppler-shift method following a two-neutron transfer reaction.

Stacking fault related luminescence in GaN nanorods

Optical and structural properties are presented for GaN nanorods (NRs) grown in the [0001] direction on Si(111) substrates by direct-current reactive magnetron sputter epitaxy. Transmission electron microscopy (TEM) reveals clusters of dense stacking faults (SFs) regularly distributed along the c-axis. A strong emission line at ∼3.42 eV associated with the basal-plane SFs has been observed in luminescence spectra. The optical signature of SFs is stable up to room temperatures with the activation energy of ∼20 meV. Temperature-dependent time-resolved photoluminescence properties suggest that the recombination mechanism of the 3.42 eV emission can be understood in terms of multiple quantum wells self-organized along the growth axis of NRs.

Modulation of Creutzfeldt-Jakob disease prion propagation by the A224V mutation

OBJECTIVE

Mutations in the gene encoding the prion protein (PrP) are responsible for approximately 10 to 15% of cases of prion disease in humans, including Creutzfeldt-Jakob disease (CJD). Here, we report on the discovery of a previously unreported C-terminal PrP mutation (A224V) in a CJD patient exhibiting a disease similar to the rare VV1 subtype of sporadic (s) CJD and investigate the role of this mutation in prion replication and transmission.

METHODS

We generated transgenic (Tg) mice expressing human PrP with the V129 polymorphism and A224V mutation, denoted Tg(HuPrP,V129,A224V) mice, and inoculated them with different subtypes of sCJD prions.

RESULTS

Transmission of sCJD VV2 or MV2 prions was accelerated in Tg(HuPrP,V129,A224V) mice, compared to Tg(HuPrP,V129) mice, with incubation periods of ∼110 and ∼210 days, respectively. In contrast, sCJD MM1 prions resulted in longer incubation periods in Tg(HuPrP,V129,A224V) mice, compared to Tg(HuPrP,V129) mice (∼320 vs. ∼210 days). Prion strain fidelity was maintained in Tg(HuPrP,V129,A224V) mice inoculated with sCJD VV2 or MM1 prions, despite the altered replication kinetics.

INTERPRETATION

Our results suggest that A224V is a risk factor for prion disease and modulates the transmission behavior of CJD prions in a strain-specific manner, arguing that residues near the C-terminus of PrP are important for controlling the kinetics of prion replication.

Case report of fetal lingual tumor - perinatal care and neonatal surgical intervention

Fetal tumors are rare and can be difficult to diagnose in utero. In this presentation, we report an infantile hemangiopericytoma of the tongue, and also review the clinical characteristics, imaging appearances, perinatal differential diagnosis, and potential treatments of this tumors. Prenatal diagnosis of lingual fetal tumors with two-dimensional (2D) ultrasound presents a challenge to sonographers and perinatologists because these lesions are rare, usually develop in the third trimester of pregnancy and need a multidisciplinary approach. We describe an lingual tumor and moderate polyhydramnios which were prenatally detected at 31 weeks of gestation with two- dimensional ultrasound. The application of the surface mode of three-dimensional ultrasound improved the visualization of this tumor. Fetal Magnetic resonance imaging was performed to help in prenatal differential diagnostic. The option of prenatal cytology gained by amniocentesis should also be considered. To our knowledge there are no prenatal reports of similar cases. However, in our experience every information provided during the pregnancy, a correct and early diagnose of fetal condition helps to cope with the demands of perinatal management and to explain to the parents and neonatologists the findings of the case.

A novel pathophysiological-based panel of biomarkers for the diagnosis of nonalcoholic steatohepatitis

Non-invasive biochemical markers are useful to distinguish between nonalcoholic steatohepatitis (NASH) and simple steatosis. The aim of this study was to test the diagnostic value of a panel of biomarkers derived from the pathophysiological events involved in the development of NASH. A total of 79 patients: 20 not-NASH and 59 NASH were included in the study. Definitive NASH was defined according to Kleiner's classification. In all subjects, parameters of the metabolic syndrome, insulin resistance (HOMA-IR), adiponectin, interleukin-6 (IL-6) and total cytokeratin-18 (M65 antigen) were determined. Univariate and multivariate analysis were used to identify independent predictors of NASH. In multivariate analysis three markers were independently predictors of NASH: adiponectin, IL-6 and M65 levels. In decreasing order, the independent predictors of NASH (NAS≥5) were M65 with an AUROC of 0.791, IL-6 with an AUROC of 0.727 and adiponectin with an AUROC of 0.709. The combination of two biomarkers yelded an AUROC of 0.828 for M65 and IL-6, 0.841 for adiponectin and M65 and 0.852 for adiponectin and IL-6. The best value was obtained by triple combination: adiponectin, M65 and IL-6 with and AUROC of 0.903, Sp=85.7% (PPV=94.2%) and Se=84.5% (NPV=66.7%). In conclusion, a novel pathophysiological - based panel of biomarkers combining total CK-18, IL-6 and adiponectin may be useful to predict NASH.

Conserved properties of human and bovine prion strains on transmission to guinea pigs

The first transmissions of human prion diseases to rodents used guinea pigs (Gps, Cavia porcellus). Later, transgenic mice expressing human or chimeric human/mouse PrP replaced Gps, but the small size of the mouse limits some investigations. To investigate the fidelity of strain-specific prion transmission to Gps, we inoculated 'type 1' and 'type 2' prion strains into Gps, and we measured the incubation times and determined the strain-specified size of the unglycosylated, protease-resistant (r) PrP(Sc) fragment. Prions passaged once in Gps from cases of sporadic (s) Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker (GSS) disease caused by the P102L mutation were used, as well as human prions from a variant (v) CJD case, bovine prions from bovine spongiform encephalopathy (BSE) and mouse-passaged scrapie prions. Variant CJD and BSE prions transmitted to all the inoculated Gps with incubation times of 367 ± 4 and 436 ± 28 days, respectively. On second passage in Gps, vCJD and BSE prions caused disease in 287 ± 4 and 310 ± 4 days, whereas sCJD and GSS prions transmitted in 237 ± 4 and 279 ± 19 days, respectively. Although hamster Sc237 prions transmitted to two of three Gps after 574 and 792 days, mouse-passaged RML and 301V prion strains, the latter derived from BSE prions, failed to transmit disease to Gps. Those Gps inoculated with vCJD or BSE prions exhibited 'type 2' unglycosylated, rPrP(Sc) (19 kDa), whereas those receiving sCJD or GSS prions displayed 'type 1' prions (21 kDa), as determined by western blotting. Such strain-specific properties were maintained in Gps as well as mice expressing a chimeric human/mouse transgene. Gps may prove particularly useful in further studies of novel human prions such as those causing vCJD.

[Intestinal stromal tumor with large unique hepatic metastasis--diagnostic difficulties]

The digestive tract mesenchymal neoplasms were viewed modified radically once it was discovered that gastrointestinal stromal tumors (GIST), the most frequent non-epithelial digestive tumors, constitute a distinctive group of tumors originating in the interstitial cells of Cajal, cells which normally express the CD117 antigen. The discovery of GIST's origin and understanding of the molecular mechanisms underlying the development of such tumors have led to important progress concerning their diagnosis and treatment. Thus, tumoral expression of c-KIT (CD117) is presently considered to be the most specific criterion for the diagnosis of GIST, and targeted molecular therapy using thyrosin-kinase inhibitors (imatinib) has encouraging results even in the case of locally advanced or metastatic tumors. This is the case of a 47 year old man who accused nonspecific abdominal symptomatology due to a large epigastric tumor which, postoperatively, proved to be the metastasis of a stromal enteral tumor.

Prion proteins with pathogenic and protective mutations show similar structure and dynamics

Conformational change in the prion protein (PrP) is thought to be responsible for a group of rare but fatal neurodegenerative diseases of humans and other animals, including Creutzfeldt-Jakob disease and bovine spongiform encephalopathy. However, little is known about the mechanism by which normal cellular PrPs initiate and propagate the conformational change. Here, we studied backbone dynamics of the inherited pathogenic mutants (P101L and H186R), protective mutants (Q167R and Q218K), and wild-type mouse PrP(89-230) at pH 5.5 and 3.5. Mutations result in minor chemical shift changes around the mutation sites except that H186R induces large chemical shift changes at distal regions. At lower pH values, the C-terminal half of the second helix is significantly disordered for the wild-type and all mutant proteins, while other parts of the protein are essentially unaffected. This destabilization is accompanied by protonation of the partially exposed histidine H186 in the second helix of the wild-type protein. This region in the mutant protein H186R is disordered even at pH 5.5. The wild-type and mutant proteins have similar microsecond conformational exchange near the two beta-strands and have similar nanosecond internal motions in several regions including the C-terminal half of the second helix, but only wild type and P101L have extensive nanosecond internal motions throughout the helices. These motions mostly disappear at lower pH. Our findings raise the possibility that the pathogenic or dominant negative mutations exert their effects on some non-native intermediate form such as PrP* after conversion of cellular PrP (PrP(C)) into the pathogenic isoform PrP(Sc) has been initiated; additionally, formation of PrP(Sc) might begin within the C-terminal folded region rather than in the disordered N-terminal region.

Cryo-immunogold electron microscopy for prions: toward identification of a conversion site

Prion diseases are caused by accumulation of an abnormally folded isoform (PrP(Sc)) of the cellular prion protein (PrP(C)). The subcellular distribution of PrP(Sc) and the site of its formation in brain are still unclear. We performed quantitative cryo-immunogold electron microscopy on hippocampal sections from mice infected with the Rocky Mountain Laboratory strain of prions. Two antibodies were used: R2, which recognizes both PrP(C) and PrP(Sc); and F4-31, which only detects PrP(C) in undenatured sections. At a late subclinical stage of prion infection, both PrP(C) and PrP(Sc) were detected principally on neuronal plasma membranes and on vesicles resembling early endocytic or recycling vesicles in the neuropil. The R2 labeling was approximately six times higher in the infected than the uninfected hippocampus and gold clusters were only evident in infected tissue. The biggest increase in labeling density (24-fold) was found on the early/recycling endosome-like vesicles of small-diameter neurites, suggesting these as possible sites of conversion. Trypsin digestion of infected hippocampal sections resulted in a reduction in R2 labeling of >85%, which suggests that a high proportion of PrP(Sc) may be oligomeric, protease-sensitive PrP(Sc).

Human prions and plasma lipoproteins

Prions are composed solely of an alternatively folded isoform of the prion protein (PrP), designated PrP(Sc). The polyoxometalate phosphotungstic acid has been used to separate PrP(Sc) from its precursor PrP(C) by selective precipitation; notably, native PrP(Sc) has not been solubilized by using nondenaturing detergents. Because of the similarities between PrP(Sc) and lipoproteins with respect to hydrophobicity and formation of phosphotungstic acid complexes, we asked whether these molecules are bound to each other in blood. Here we report that prions from the brains of patients with sporadic Creutzfeldt-Jakob disease (CJD) bind to very low-density (VLDL) and low-density (LDL) lipoproteins but not to high-density lipoproteins (HDL) or other plasma components, as demonstrated both by affinity assay and electron microscopy. Immunoassays demonstrated that apolipoprotein B (apoB), which is the major protein component of VLDL and LDL, bound PrP(Sc) through a highly cooperative process. Approximately 50% of the PrP(Sc) bound to LDL particles was released after exposure to 4 M guanidine hydrochloride at 80 degrees C for 20 min. The apparent binding constants of native human (Hu) PrP(Sc) or denatured recombinant HuPrP(90-231) for apoB and LDL ranged from 28 to 212 pM. Whether detection of PrP(Sc) in VLDL and LDL particles can be adapted into an antemortem diagnostic test for prions in the blood of humans, livestock, and free-ranging cervids remains to be determined.

Search for a prion-specific nucleic acid

Diversity of prion strains was attributed to an elusive nucleic acid, yet a search spanning nearly two decades has failed to identify a prion-specific polynucleotide. In our search for a prion-specific nucleic acid, we analyzed nucleic acids in purified fractions from the brains of Syrian hamsters infected with Sc237 prions. Purification of Sc237 prions removed nucleic acids larger than 50 nucleotides as measured by return refocusing electrophoresis (RRGE). To determine the size of the largest polynucleotide present in purified fractions at an abundance of one molecule per infectious (ID50) unit, we measured prions present after inoculation. In order to account for the rapid clearance of prions after intracerebral inoculation, we determined the number of PrP(Sc) molecules and ID50 units of prions that were retained in brain. Factoring in clearance after inoculation, we estimate that the largest polynucleotide present in our purified fractions at one molecule per ID50 unit is approximately 25 nucleotides in length. In the same fractions, there were approximately 3,000 protease-resistant PrP(Sc) molecules per ID50 unit after accounting for clearance of PrP(Sc) following inoculation. We compared the resistance of Sc237 and 139H prions to inactivation by UV irradiation at 254 nm. Irradiation of homogenates and microsomes diminished prion infectivity by a factor of approximately 1,000 but did not alter the strain-specified properties of the Sc237 and 139H prions. The data reported here combined with the production of synthetic prions argue that the 25-mer polynucleotides found in purified prion preparations are likely to be host encoded and of variable sequence; additionally, these 25-mers are unlikely to be prion specific.

Diagnosis of human prion disease

With the discovery of the prion protein (PrP), immunodiagnostic procedures were applied to diagnose Creutzfeldt-Jakob disease (CJD). Before development of the conformation-dependent immunoassay (CDI), all immunoassays for the disease-causing PrP isoform (PrPSc) used limited proteolysis to digest the precursor cellular PrP (PrPC). Because the CDI is the only immunoassay that measures both the protease-resistant and protease-sensitive forms of PrPSc, we used the CDI to diagnose human prion disease. The CDI gave a positive signal for PrPSc in all 10-24 brain regions (100%) examined from 28 CJD patients. A subset of 18 brain regions from 8 patients with sporadic CJD (sCJD) was examined by histology, immunohistochemistry (IHC), and the CDI. Three of the 18 regions (17%) were consistently positive by histology and 4 of 18 (22%) by IHC for the 8 sCJD patients. In contrast, the CDI was positive in all 18 regions (100%) for all 8 sCJD patients. In both gray and white matter, approximately 90% of the total PrPSc was protease-sensitive and, thus, would have been degraded by procedures using proteases to eliminate PrPC. Our findings argue that the CDI should be used to establish or rule out the diagnosis of prion disease when a small number of samples is available as is the case with brain biopsy. Moreover, IHC should not be used as the standard against which all other immunodiagnostic techniques are compared because an immunoassay, such as the CDI, is substantially more sensitive.

Tumeur mélanocytaire méningée primitive de grade intermédiaire : confrontation radio-pathologique

A case of primary meningeal intermediate grade melanocytic neoplasm involving the right C2 nerve root is presented. MRI findings may suggest this rare entity, especially when an extra-axial lesion is located in the posterior fossa or cervical spinal canal and demonstrates shortening of both T1 and T2. Eventually, definitive diagnosis relies on histology which demonstrates spindle-shaped melanocytic cells that are Fontana stained and positive for HMB:45 antigen. Cellularity, pleomorphism, mitotic rate, proliferation index and invasiveness are useful criteria to distinguish among the spectrum of primary melanocytic tumors of the central nervous system ranging from melanocytoma to malignant melanoma.

Immunoglobulins in urine of hamsters with scrapie

In the prion diseases, a prolonged, asymptomatic incubation period precedes the onset of neurologic dysfunction. At present, a noninvasive test is not available for the presymptomatic diagnosis of prion disease, and thus the report of a test for prions using urine has been of great interest (Shaked, G. M., Shaked, Y., Kariv-Inbal, Z., Halimi, M., Avraham, I., and Gabizon, R. (2001) J. Biol. Chem. 276, 31479-31482). Using Western immunoblots with the anti-prion protein (PrP) 3F4 monoclonal antibody and an anti-mouse IgG secondary antibody, a protease-resistant PrP was reported in the urine of Syrian hamsters and humans with prion disease. Here we have demonstrated that this purportedly "protease-resistant PrP" band in the urine of diseased hamsters is detectable using the anti-mouse IgG secondary antibody in the absence of the 3F4 monoclonal antibody. Mass spectrometric analysis identified an immunoglobulin light chain in the band but found no PrP peptides. No similar band was found in the urine of uninfected hamsters or in brain homogenates from normal or prion-infected hamsters. Moreover, the band in the urine of infected hamsters was not detected using two chimeric human-mouse recombinant anti-PrP antibody fragments followed by an anti-human IgG secondary antibody. Our results indicate that the band detected under previously published conditions is due to the cross-reactivity of the anti-mouse IgG antibody with IgG light chains and possibly heavy chain fragments in urine, but not with PrP.

[Management of childhood obesity]

The prevalence of obesity is currently increasing in children and young adolescents in France, and affects about 10 to 14% of them. Therapeutic objectives should aim to improve, on the long-term, the weight/body mass index curve. Restrictive diet and weight loss should not be the primary target. The focus has to be on a balanced healthy diet, tailored to children growth, associated with a regular physical activity. Children weight management should be within the usual life conditions, taking into account familial and social environmental conditions, through a multidisciplinary team approach as those implemented in our paediatric medical centre. The objectives, management steps and current results of our therapeutic educational project are described.

Conformation of PrP(C) on the cell surface as probed by antibodies

We have investigated the conformation of Syrian hamster PrP(C) on the surface of transfected CHO cells by performing cross-competition experiments between a set of nine monoclonal antibody fragments (Fab) directed to defined epitopes throughout the protein. No competition was observed between antibodies recognizing epitopes located within the unstructured N-terminal portion of PrP(C) and those recognizing epitopes located within the ordered C-terminal half of the molecule. However, competition was observed between antibodies recognizing overlapping epitopes and between antibodies recognizing epitopes lying adjacent to one another in the PrP sequence. Titrating the reactivity of each Fab against cell-surface PrP(C) revealed a clear heterogeneity in the accessibility of different specific epitopes. Fab D18, recognizing sequence incorporating the first alpha-helix of PrP(C), bound the largest fraction of the cell-surface PrP population. In contrast, Fab E123, binding an epitope at the extreme N terminus of PrP, and Fab 13A5, binding an epitope in the central region of PrP, were able to recognize fewer than half the number of PrP(C) molecules bound by Fab D18. The pattern of antibody reactivity we observed may, in part, result from N-terminal truncation of a proportion of PrP(C) molecules found at the cell surface. However, truncation cannot account for the marked disparity between exposure of the Fab D18 and 13A5 epitopes, which lie adjacent in the PrP sequence. The relative inaccessibility of the 13A5 epitope likely reflects either PrP(C)-PrP(C) interaction, interaction between PrP(C) and other constituents on the cell membrane, or the existence of PrP(C) subspecies with distinct conformations.

Structural studies of the scrapie prion protein by electron crystallography

Because the insolubility of the scrapie prion protein (PrP(Sc)) has frustrated structural studies by x-ray crystallography or NMR spectroscopy, we used electron crystallography to characterize the structure of two infectious variants of the prion protein. Isomorphous two-dimensional crystals of the N-terminally truncated PrP(Sc) (PrP 27-30) and a miniprion (PrP(Sc)106) were identified by negative stain electron microscopy. Image processing allowed the extraction of limited structural information to 7 A resolution. By comparing projection maps of PrP 27-30 and PrP(Sc)106, we visualized the 36-residue internal deletion of the miniprion and localized the N-linked sugars. The dimensions of the monomer and the locations of the deleted segment and sugars were used as constraints in the construction of models for PrP(Sc). Only models featuring parallel beta-helices as the key element could satisfy the constraints. These low-resolution projection maps and models have implications for understanding prion propagation and the pathogenesis of neurodegeneration.

Immobilized prion protein undergoes spontaneous rearrangement to a conformation having features in common with the infectious form

It is hypothesized that infectious prions are generated as the cellular form of the prion protein (PrP(C)) undergoes pronounced conformational change under the direction of an infectious PrP(Sc) template. Conversion to the infectious conformer is particularly associated with major structural rearrangement in the central portion of the protein (residues 90-120), which has an extended flexible structure in the PrP(C) isoform. Using a panel of recombinant antibodies reactive with different parts of PrP, we show that equivalent major structural rearrangements occur spontaneously in this region of PrP immobilized on a surface. In contrast, regions more towards the termini of the protein remain relatively unaltered. The rearrangements occur even under conditions where individual PrP molecules should not contact one another. The propensity of specific unstructured regions of PrP to spontaneously undergo large and potentially deleterious conformational changes may have important implications for prion biology.

Evolution of GH secretion in urine during an in-patient slimming course in obese children

OBJECTIVE

To estimate the change in GH excretion in urine (GH-U) during a slimming course, and if increased, to assess the components of the course related to the increase in obese children.

DESIGN

Observational follow-up study of patients admitted for primary obesity to an in-patient slimming course lasting at least 10 weeks.

SUBJECTS

48 complete observations out of 54 consecutive pre-pubertal patients admitted to a paediatric centre for treatment of primary obesity (BMI greater than the 90th percentile of the national reference curves).

MEASUREMENTS

GH excretion in urine by immunoradiometric assay, at entry and after 10 weeks, various anthropometric measurements, nutritional intake and departure from the prescribed diet, time spent in physical activity, sleep duration.

RESULTS

A mean decrease of 0.90 standard deviations for BMI was accompanied by a 34% increase of GH-U. Time spent in physical activity was the only component of the course found to be related to the magnitude of GH-U increase.

CONCLUSION

The results of this observational study confirm that GH-U is increased after a slimming course in children, and suggest that physical activity is a major contributor to the restoration of normal GH-U levels.

Dual energy X-ray absorptiometry of the hand and wrist--a possible technique to assess skeletal maturation: methodology and data in normal youths

Ninety five normal Caucasian subjects (51F, 44M) aged from 2 to 25 y were measured at the hand and wrist level with a small DXA system (pDEXA) in order to obtain the normal values of the bone mineral content (BMC), density (BMD) and projected area (A) of carpal (c) and metacarpal (m) bones. BMDc ranged from 0.065 +/- 0.007 g/cm2 to 0.365 +/- 0.035 g/cm2 in females and 0.425 +/- 0.040 g/cm2 in males. It presented a sharp change of increase rate at 15.5 and 17 y of age in girls and boys, respectively. Ac presented the same kind of evolution as BMDc, but had a larger value dispersion. The second metacarpal bone had the highest BMCm value in 85% of females and 90% of males. The sum of BMCmi or Ami values (i = 1-5) and the projected mean density of the 5 metacarpal bones was well correlated with BMCc, Ac and BMDc, respectively (r > 0.90). A volumetric mineral density, dmi, calculated for each of these bones, approximated to a cylinder, was correlated with age (r > 0.85).

Nonclassical adrenal hyperplasia due to 21-hydroxylase-deficiency: does genotyping predict the clinical manifestation?

8 patients of 7 families with nonclassical adrenal hyperplasia (NCAH) were analysed for defects of the 21-hydroxylase-B-gene. As the defects were small or rare, complete molecular genetic diagnostic up to sequencing of this gene was necessary to detect the genotype, which then was associated with the phenotype. However, mutations in 4 alleles from 3 families are still undetectable. Thus, correct prenatal diagnosis in NCAH-families without index patient remains difficult.

Evaluation of the Elbs Persulfate Oxidation Reaction for the Preparation of Aryloxyphenoxypropionate Herbicides

A new, simple method for the preparation of several 4-( aryloxy )phenols (2a-d) and alkyl 2-(4-hydroxyphenoxy)propionates (3a,b) is described. These compounds are key precursors for the synthesis of important aryloxyphenoxypropionate herbicides (1a-d). The method uses the Elbs persulfate oxidation to convert phenol into 4-hydroxyphenyl sulfate (5). The free hydroxy group is then reacted with various aryl halides and alkyl 2-halopropionates. Mild hydrolysis of the sulfate group with boiling acetic acid then gives the products (2a-d) and (3a,b), generally in modest to good yield.

Spectroscopic characterization of conformational differences between PrPC and PrPSc: an alpha-helix to beta-sheet transition

Although no chemical modifications have been found to distinguish the cellular prion protein PrPC from its infectious analogue PrPSc, spectroscopic methods such as Fourier transform infrared (FTIR) spectroscopy reveal a major conformational difference. PrPC is rich in alpha-helix but is devoid of beta-sheet, whereas PrPSc is high in beta-sheet. N-terminal truncation of PrPSc by limited proteolysis does not destroy infectivity but it increases the beta-sheet content and shifts the FTIR absorption to lower frequencies, typical of the cross beta-pleated sheets of amyloids. Thus the formation of PrPSc from PrPC involves a conformational transition in which one or more alpha-helical regions of the protein is converted to beta-sheet. This transition is mimicked by synthetic peptides, allowing predictions of domains of PrP involved in prion diseases.

Conversion of alpha-helices into beta-sheets features in the formation of the scrapie prion proteins

Prions are composed largely, if not entirely, of prion protein (PrPSc in the case of scrapie). Although the formation of PrPSc from the cellular prion protein (PrPC) is a post-translational process, no candidate chemical modification was identified, suggesting that a conformational change features in PrPSc synthesis. To assess this possibility, we purified both PrPC and PrPSc by using nondenaturing procedures and determined the secondary structure of each. Fourier-transform infrared (FTIR) spectroscopy demonstrated that PrPC has a high alpha-helix content (42%) and no beta-sheet (3%), findings that were confirmed by circular dichroism measurements. In contrast, the beta-sheet content of PrPSc was 43% and the alpha-helix 30% as measured by FTIR. As determined in earlier studies, N-terminally truncated PrPSc derived by limited proteolysis, designated PrP 27-30, has an even higher beta-sheet content (54%) and a lower alpha-helix content (21%). Neither PrPC nor PrPSc formed aggregates detectable by electron microscopy, while PrP 27-30 polymerized into rod-shaped amyloids. While the foregoing findings argue that the conversion of alpha-helices into beta-sheets underlies the formation of PrPSc, we cannot eliminate the possibility that an undetected chemical modification of a small fraction of PrPSc initiates this process. Since PrPSc seems to be the only component of the "infectious" prion particle, it is likely that this conformational transition is a fundamental event in the propagation of prions.

Ablation of the prion protein (PrP) gene in mice prevents scrapie and facilitates production of anti-PrP antibodies

Mice, homozygous for prion protein (PrP) gene ablation (Prn-p0/0), develop normally and remain well > 500 days after inoculation with murine scrapie prions. In contrast, wild-type mice developed scrapie < 165 days after inoculation and most Prn-p0/+ mice, heterozygous for disruption of the PrP gene, exhibited signs of central nervous system dysfunction between 400 and 465 days after inoculation. In situ immunoblots showed widespread deposition of scrapie PrP (PrPSc) in the brains of both wild-type Prn-p+/+ and Prn-p0/+ mice, while neither cellular PrP (PrPC) nor PrPSc was detected in the brains of Prn-p0/0 mice. In contrast to Prn-p+/+ and Prn-p0/+ mice, Prn-p0/0 mice failed to propagate prion infectivity as measured by bioassays. Syrian hamster (SHa) PrP transgenes rendered Prn-p0/0 mice susceptible to prions containing SHaPrPSc. Immunization of Prn-p0/0 mice with purified, infectious mouse or SHa prions dispersed in Freund's adjuvant produced antisera that bound mouse, SHa, and human PrP on Western blots. Presumably, the lack of PrPC expression in Prn-p0/0 mice prevents them from becoming tolerant to the immunogen. The resistance of Prn-p0/0 mice to developing scrapie after inoculation with murine prions supports the hypothesis that PrPSc is essential for both transmission and pathogenesis of the prion diseases.

Attempts to restore scrapie prion infectivity after exposure to protein denaturants

A wealth of experimental evidence argues that infectious prions are composed largely, if not entirely, of the scrapie isoform of the prion protein. We attempted to restore scrapie infectivity after exposure to protein denaturants including urea, chaotropic salts, and SDS. None of the procedures restored infectivity. Dialysis to remove slowly chaotropic ions and urea failed to restore scrapie infectivity. Attempts to create monomers of the scrapie isoform of the prion protein under nondenaturing conditions using a wide variety of detergents have been unsuccessful, to date, except for one report claiming that scrapie infectivity could be recovered from 12% polyacrylamide gels after SDS/PAGE [Brown, P., Liberski, P. P., Wolff, A. & Gajdusek, D. C. (1990) Proc. Natl. Acad. Sci. USA 87, 7240-7244]. We found that < 0.001% of the infectious prion titer could be recovered from the region of a polyacrylamide gel where the denatured proteinase K-resistant core of the scrapie isoform of the prion protein and other 30-kDa proteins migrate. We conclude that under the denaturing conditions used for SDS/PAGE, the scrapie isoform of the prion protein is denatured and little or no renaturation occurs upon injection of fractions eluted from gels into animals for bioassays.

Scrapie prion rod formation in vitro requires both detergent extraction and limited proteolysis

Scrapie prion infectivity can be enriched from hamster brain homogenates by using limited proteolysis and detergent extraction. Purified fractions contain both scrapie infectivity and the protein PrP 27-30, which is aggregated in the form of prion rods. During purification, PrP 27-30 is produced from a larger membrane protein, PrPSc, by limited proteolysis with proteinase K. Brain homogenates from scrapie-infected hamsters do not contain prion rods prior to exposure to detergents and proteases. To determine whether both detergent extraction and limited proteolysis are required for the formation of prion rods, microsomal membranes were prepared from infected brains in the presence of protease inhibitors. The isolated membranes were then detergent extracted as well as protease digested to evaluate the effects of these treatments on the formation of prion rods. Neither detergent (2% Sarkosyl) extraction nor limited proteinase K digestion of scrapie microsomes produced recognizable prion amyloid rods. Only after combining detergent extraction with limited proteolysis were numerous prion rods observed. Rod formation was influenced by the protease concentration, the specificity of the protease, and the duration of digestion. Rod formation also depended upon the detergent; some combinations of protease and detergent did not produce prion amyloid rods. Similar results were obtained with purified PrPSc fractions prepared by repeated detergent extractions in the presence of protease inhibitors. These fractions contained amorphous structures but not rods; however, prion rods were produced upon conversion of PrPSc to PrP 27-30 by limited proteolysis. We conclude that the formation of prion amyloid rods in vitro requires both detergent extraction and limited proteolysis. In vivo, amyloid filaments found in the brains of animals with scrapie resemble prion rods in their width and their labeling with prion protein (PrP) antisera; however, filaments are typically longer than rods. Whether limited proteolysis and some process equivalent to detergent extraction are required for amyloid filament formation in vivo remains to be established.

Investigations on the presence of antibodies to papova viruses in patients with different forms of cancer and in other categories of patients or apparently healthy subjects. Note I. Neutralizing antibodies to SV-40 in the cerebrospinal fluid of patients with brain tumors and chronic neurological diseases

Neutralizing antibodies to SV-40 were detected in cerebrospinal fluid samples from 16 out of 43 patients with brain tumors and in 6 out of 20 patients with different nonmalignant chronic neurological diseases. The patients' age excluded the correlation with a vaccine-associated or occupational contact with SV-40. The results ascertain the occurrence of SV-40 or of an antigenically related virus in the population of Romania.

Investigations on the presence of antibodies to papova viruses in patients with different forms of cancer and in other categories of patients or apparently healthy subjects. Note II. Hemagglutination-inhibiting serum antibodies to BK virus

Hemagglutination-inhibiting serum antibodies to BK virus (BKV were detected in patients with different forms of cancer and in blood donors (positivity percentages: 67.04 and 57.78, respectively). No such antibodies were found in a group of children 1 to 14 years of age. The data point to the presence of a latent human infection with BKV in the population of Romania.

Investigations on the presence of antibodies to papova viruses in patients with different forms of cancer and in other categories of patients or apparently healthy subjects. Note III. Hemagglutination-inhibiting serum antibodies to polyoma virus

Hemagglutination-inhibiting antibodies to polyoma virus could be detected in sera from apparently healthy subjects, patients with nonmalignant respiratory diseases and patients with different forms of cancer. The positivity percentages (12.97, 12.92 and 16.36, respectively) and the titers recorded were lower than in the case of BK virus. The results obtained suggest a slight antigenic relationship between polyoma and BK virus.

The diagnostic value of interpleural lymph node biopsy

The authors examined biopsies of the interpleural lymph nodes harvested by mediastinoscopy and hilloscopy in 162 patients (133 males and 29 females). The diagnostic efficiency is very high in sarcoidosis, silicosis and in Hodgkin's disease. In sarcoidosis biopsy is able to indicate the evolutive stage of the disease. In malignant lymphogranulomatosis all the observations belonged to type II of nodular sclerosis. In bronchial carcinoma interpleural lymph node biopsy may be practised with diagnostic purposes or in order to check up operability.

Hemorrhagic fever with renal syndrome: report of 11 observations

Based on the observation of 11 patients (10 males and 1 female), the occurrence of hemorrhagic fever with renal syndrome in two new geographic areas of Romania is reported. Two patients died within several hours after admission. The other nine recovered gradually. In four patients hemodialysis was necessary. A complete recovery of renal functions one year after onset could be proved in four patients. The clinical, laboratory, morphopathological (necroptic and bioptic), epidemiologic and evolutive characteristics of the disease, especially the main features supporting the diagnosis of hemorrhagic fever with renal syndrome, are discussed.

Immunoblastic lymphadenopathy with centrofollicular PAS-positive inclusions

The authors describe the clinical and histopathologic picture of immunoblastic lymphadenomegaly in a 66-year-old patient with allergic antecedents. The condition of the patient ameliorated following cortisone and antibiotic therapy, but adenomegalia relapsed after several months. PAS-positive granular inclusions were found in the macrophage cells in the germinative centres of the follicles, showing the aspect of a blockade with nuclear significance.

Anatomo-pathologic observations on epidemic nephropathy

Two cases of necropsy and 5 cases of renal biopuncture were studied on the occassion of an epidemic of "hemorrhagic fever with renal syndrome" identified in mountainous areas of Transylvania. The prevalent pathogenic process was capillary toxicosis which injured the renal tubules and vessels. The severity of the disease was determined by the phenomena of tubular failure, by the hemorrhagic syndrome and shock.