Use of Eculizumab in Pediatric Patients with High-Risk Transplantation-Associated Thrombotic Microangiopathy: Outcomes and Risk Factors Associated with Response and Survival. A Retrospective Study on Behalf of the Spanish Group for Hematopoietic Transplantation and Cellular Therapy (GETH-TC)

Transplantation-associated thrombotic microangiopathy (TA-TMA) is associated with high morbidity and mortality. Although survival has improved significantly with the introduction of eculizumab, the need for improvement remains, especially in high-risk patients. This study aimed to describe the results obtained with eculizumab in a pediatric cohort with the attempt to define which risk factors could determine the response to treatment. We designed a national multicenter retrospective study of children treated with eculizumab for high-risk TA-TMA. The study cohort comprised 29 patients who had undergone a first (n = 28) or second (n = 1) allogeneic hematopoietic stem cell transplantation (HSCT) for malignant (n = 17) or nonmalignant (n = 12) disease. The median time from HSCT to TA-TMA diagnosis was 154 days (interquartile range [IQR], 103 to 263 days). Eleven patients (38%) who were initially diagnosed with low- to intermediate-risk TA-TMA progressed to high-risk TA-TMA (hrTA-TMA), within a median time of 4 days (IQR, 1 to 33 days). SC5b-9 was increased in 90% of 20 patients in whom it was measured. Renal (n = 12), pulmonary (n = 1), and intestinal (n = 1) biopsy confirmed the diagnosis in 12 of 14 patients (85%). Seventeen patients (58%) had extrarenal involvement with serositis (n = 13; 44,8%), pulmonary (n = 12; 41,4%), gastrointestinal (n = 8; 27.6%), cardiovascular (n = 7; 24.1%), or central nervous system (CNS) (n = 2; 6.9%) involvement. The median time from hrTA-TMA diagnosis to the initiation of eculizumab was 7 days (IQR, 1 to 8 days). Overall, 19 patients (65.5%) responded to eculizumab, of whom 17 (58.6%) achieved a complete response and 2 (6.9%) achieved a partial response. The remaining 10 patients (34.5%) did not show any of response. The overall response rate to eculizumab for TA-TMA was 27.59% (95% confidence interval [CI], 14.87% to 47.66%) at 1 month, 55.17% (95% CI, 38.43% to 73.48%) at 3 months, and 62.07% (95% CI, 45.10% to 79.13%) at 6 months after eculizumab initiation. In multivariate analysis, the pulmonary involvement decreased the probability of response (hazard ratio [HR], .18; P = .0298). The 1-year overall survival (OS) was 55.2% (95% CI, 35.6% to 71.0%) for the whole cohort and 83.3% (95% CI, 56.7% to 94.3%) for patients who responded to eculizumab. Pulmonary involvement (HR, 14.93; P = .0043) and CNS involvement (HR, 8.63; P = .0497) were associated with a statistically significant decrease in survival. We found that patients diagnosed with hrTA-TMA with pulmonary involvement had a poor response to eculizumab, and that patients with pulmonary and CNS involvement had significantly decreased survival. Given these results, we hypothesize that providing eculizumab therapy at an early stage of the disease before organ damage is established might significantly improve the response and, consequently, survival.

Engineered tRNAs suppress nonsense mutations in cells and in vivo

Nonsense mutations are the underlying cause of approximately 11% of all inherited genetic diseases1. Nonsense mutations convert a sense codon that is decoded by tRNA into a premature termination codon (PTC), resulting in an abrupt termination of translation. One strategy to suppress nonsense mutations is to use natural tRNAs with altered anticodons to base-pair to the newly emerged PTC and promote translation2-7. However, tRNA-based gene therapy has not yielded an optimal combination of clinical efficacy and safety and there is presently no treatment for individuals with nonsense mutations. Here we introduce a strategy based on altering native tRNAs into  efficient suppressor tRNAs (sup-tRNAs) by individually fine-tuning their sequence to the physico-chemical properties of the amino acid that they carry. Intravenous and intratracheal lipid nanoparticle (LNP) administration of sup-tRNA in mice restored the production of functional proteins with nonsense mutations. LNP-sup-tRNA formulations caused no discernible readthrough at endogenous native stop codons, as determined by ribosome profiling. At clinically important PTCs in the cystic fibrosis transmembrane conductance regulator gene (CFTR), the sup-tRNAs re-established expression and function in cell systems and patient-derived nasal epithelia and restored airway volume homeostasis. These results provide a framework for the development of tRNA-based therapies with a high molecular safety profile and high efficacy in targeted PTC suppression.

The Influence of Cannabinoids on Drosophila Behaviors, Longevity, and Traumatic Injury Responses of the Adult Nervous System

Introduction: The legalization of cannabis products has increased their usage in the United States. Among the ∼500 active compounds, this is especially true for cannabidiol (CBD)-based products, which are being used to treat a range of ailments. Research is ongoing regarding the safety, therapeutic potential, and molecular mechanism of cannabinoids. Drosophila (fruit flies) are widely used to model a range of factors that impact neural aging, stress responses, and longevity. Materials and Methods: Adult wild-type Drosophila melanogaster cohorts (w1118/+) were treated with different Δ9-tetrahydrocannabinol (THC) and CBD dosages and examined for neural protective properties using established neural aging and trauma models. The therapeutic potential of each compound was assessed using circadian and locomotor behavioral assays and longevity profiles. Changes to NF-κB pathway activation were assessed by measuring expression levels of downstream targets using quantitative real-time polymerase chain reaction analysis of neural cDNAs. Results: Flies exposed to different CBD or THC dosages showed minimal effects to sleep and circadian-based behaviors or the age-dependent decline in locomotion. The 2-week CBD (3 μM) treatment did significantly enhance longevity. Flies exposed to different CBD and THC dosages were also examined under stress conditions, using the Drosophila mild traumatic brain injury (mTBI) model (10×). Pretreatment with either compound did not alter baseline expression of key inflammatory markers (NF-κB targets), but did reduce neural mRNA profiles at a key 4-h time point following mTBI exposure. Locomotor responses were also significantly improved 1 and 2 weeks following mTBI. After mTBI (10×) exposure, the 48-h mortality rate improved for CBD (3 μM)-treated flies, as were global average longevity profiles for other CBD doses tested. While not significant, THC (0.1 μM)-treated flies show a net positive impact on acute mortality and longevity profiles following mTBI (10×) exposure. Conclusions: This study shows that the CBD and THC dosages examined had at most a modest impact on basal neural function, while demonstrating that CBD treatments had significant neural protective properties for flies following exposure to traumatic injury.

Zebrafish models of acute leukemias: Current models and future directions

Acute myeloid leukemias (AML) and acute lymphoid leukemias (ALL) are heterogenous diseases encompassing a wide array of genetic mutations with both loss and gain of function phenotypes. Ultimately, these both result in the clonal overgrowth of blast cells in the bone marrow, peripheral blood, and other tissues. As a consequence of this, normal hematopoietic stem cell function is severely hampered. Technologies allowing for the early detection of genetic alterations and understanding of these varied molecular pathologies have helped to advance our treatment regimens toward personalized targeted therapies. In spite of this, both AML and ALL continue to be a major cause of morbidity and mortality worldwide, in part because molecular therapies for the plethora of genetic abnormalities have not been developed. This underscores the current need for better model systems for therapy development. This article reviews the current zebrafish models of AML and ALL and discusses how novel gene editing tools can be implemented to generate better models of acute leukemias. This article is categorized under: Adult Stem Cells, Tissue Renewal, and Regeneration > Stem Cells and Disease Technologies > Perturbing Genes and Generating Modified Animals.

Treatment with Bacterial Biologics Promotes Healthy Aging and Traumatic Brain Injury Responses in Adult Drosophila, Modeling the Gut-Brain Axis and Inflammation Responses

Drosophila are widely used to study neural development, immunity, and inflammatory pathways and processes associated with the gut-brain axis. Here, we examine the response of adult Drosophila given an inactive bacteriologic (IAB; proprietary lysate preparation of Lactobacillus bulgaricus, ReseT®) and a probiotic (Lactobacillus rhamnosus, LGG). In vitro, the IAB activates a subset of conserved Toll-like receptor (TLR) and nucleotide-binding, oligomerization domain-containing protein (NOD) receptors in human cells, and oral administration slowed the age-related decline of adult Drosophila locomotor behaviors. On average, IAB-treated flies lived significantly longer (+23%) and had lower neural aggregate profiles. Different IAB dosages also improved locomotor function and longevity profiles after traumatic brain injury (TBI) exposure. Mechanistically, short-term IAB and LGG treatment altered baseline nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κβ) signaling profiles in neural and abdominal tissues. Overall, at select dosages, IAB and LGG exposure has a positive impact on Drosophila longevity, neural aging, and mild traumatic brain injury (TBI)-related responses, with IAB showing greater benefit. This includes severe TBI (sTBI) responses, where IAB treatment was protective and LGG increased acute mortality profiles. This work shows that Drosophila are an effective model for testing bacterial-based biologics, that IAB and probiotic treatments promote neuronal health and influence inflammatory pathways in neural and immune tissues. Therefore, targeted IAB treatments are a novel strategy to promote the appropriate function of the gut-brain axis.

Discovery of cyclic guanidine-linked sulfonamides as inhibitors of LMTK3 kinase

Lemur tyrosine kinase 3 (LMTK3) is oncogenic in various cancers. In breast cancer, LMTK3 phosphorylates and modulates the activity of estrogen receptor-α (ERα) and is essential for the growth of ER-positive cells. LMTK3 is highly expressed in ER-negative breast cancer cells, where it promotes invasion via integrin β1. LMTK3 abundance and/or high nuclear expression have been linked to shorter disease free and overall survival time in a variety of cancers, supporting LMTK3 as a potential target for anticancer drug development. We sought to identify small molecule inhibitors of LMTK3 with the ultimate goal to pharmacologically validate this kinase as a novel target in cancer. We used a homogeneous time resolve fluorescence (HTRF) assay to screen a collection of mixture-based combinatorial chemical libraries containing over 18 million compounds. We identified several cyclic guanidine-linked sulfonamides with sub-micromolar activity and evaluated their binding mode using a 3D homology model of the LMTK3 K_D.

[Infectious myositis]

Infectious myositis is a rare condition that can be caused by bacteria, viruses, parasites or fungi. Muscle pain or weakness are symptoms shared by all type of myositis. Diagnosis is made on clinical presentation: fever and poor general state is found in bacterial myositis, diffuse muscle pain with flu-like symptoms in viral causes, eosinophilia and a tropical travel history can be related to parasitic etiology, and immunocompromising condition suggests fungal infection. Rhabdomyolysis, leukocytosis and elevated C-reactive protein are common. Imaging (computed tomography or magnetic resonance imaging) can be useful to detect which muscle is affected. The causative organism can be identified on blood cultures, skeletal muscle biopsy, serology or any other pathogen specific test. Treatment depends on the causative organism. Open surgical or imaging-guided drainage is usually necessary in bacterial myositis.

Halogen-like properties of the Al13 cluster mimicking astatine

Astatine-211 is considered to be one of the most promising alpha-emitters in targeted alpha therapy (TAT). However, its development has been hindered by its not so well understood chemistry. Hence, any attempt to understanding it better is imperative. Here, we show through DFT calculations that the neutral endohedral Al13 cluster follows a reactivity pattern very similar to At, more than any other halogen. The halogen and alkali bonding with Al13 and At presented a strong similarity in their charge transfer processes. Moreover, upon the interchange of At with Al13, we found a stable configuration of the compound corresponding to the astatination of aryliodonium salts, which have been considered as possible precursors for the synthesis of 211At-labeled tracers. Our results provide promising proof of concept that the Al13 cluster mimics the behaviour of At and might help in better understanding its chemistry and in streamlining the chemical processes of radiolabeling biomolecules.

Using Drosophila as an integrated model to study mild repetitive traumatic brain injury

Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. In addition, there has been a growing appreciation that even repetitive, milder forms of TBI (mTBI) can have long-term deleterious consequences to neural tissues. Hampering our understanding of genetic and environmental factors that influence the cellular and molecular responses to injury has been the limited availability of effective genetic model systems that could be used to identify the key genes and pathways that modulate both the acute and long-term responses to TBI. Here we report the development of a severe and mild-repetitive TBI model using Drosophila. Using this system, key features that are typically found in mammalian TBI models were also identified in flies, including the activation of inflammatory and autophagy responses, increased Tau phosphorylation and neuronal defects that impair sleep-related behaviors. This novel injury paradigm demonstrates the utility of Drosophila as an effective tool to validate genetic and environmental factors that influence the whole animal response to trauma and to identify prospective therapies needed for the treatment of TBI.

Reexamination of the origin of the pseudo Jahn–Teller puckering instability in silicene

The pseudo Jahn–Teller puckering instability in the basic ring unit of silicene is due to the coupling of its ground state with two excited states through the puckering mode.

Varicella zoster central nervous system vasculitis after allogeneic hematopoietic stem cell transplant successfully treated with cyclophosphamide

We report the first case of varicella zoster central nervous system vasculitis, to our knowledge, which responded to intravenous pulses of cyclophosphamide in an immunocompromised child with severe and progressive disease, without sequelae.

Persistent genomic instability in peripheral blood lymphocytes from Hodgkin lymphoma survivors

Advances in cancer treatment have led to an increase in patient survival. However, exposure to genotoxic chemotherapeutic agents and ionizing radiation may induce persistent genetic damage in cancer survivors. In this study, we detected genomic instability in chromosomes of peripheral blood lymphocytes from Hodgkin lymphoma patients, 2-17 years after MOPP (nitrogen mustard, Oncovin, procarbazine, and prednisone) chemotherapy with or without radiotherapy. Samples were obtained from 11 healthy individuals, 5 pretreatment patients, and 20 posttreatment patients. Cytogenetic analysis with GTG banding was performed on 1,000 lymphocyte metaphases per donor to identify genomic instability, including numerical and structural chromosomal aberrations, at a resolution of 10 Mb across the entire genome. Our results showed that anticancer treatment did not induce significant differences in the frequency of aneuploidy among the three study groups. However, 1 of the 11 healthy individuals, and 13 of the 20 posttreatment patients had a high frequency of chromosomal breaks and gross chromosomal rearrangements. The types of aberrations observed were random and complex, consistent with persistent genomic instability that was induced by cancer treatment. Clonal expansion of cells with chromosomal lesions was observed in one posttreatment patient only. These findings show that anticancer treatments induce persistent genomic instability, but not aneuploidy. Chemotherapy may affect genes with a role in DNA damage surveillance or repair, which in turn allows the accumulation of nontargeted structural chromosomal damage in future generations of cells. This genomic instability may facilitate the development of second malignancies in Hodgkin lymphoma survivors.

Diversidad genética de 12 LOCI microsatelitales utilizados en pruebas de paternidad equina en Chile

Se investigó la diversidad genética de 12 loci microsatelitales (HMS2, HMS3, HMS6, HMS7, HTG4, HTG6, AHT4, AHT5, VHL20, ASB2, HTG7 y HTG10) utilizados en pruebas de filiación equina en Chile en una muestra poblacional de 45 caballos Criollos chilenos por medio del contenido de información polimórfica, heterocigosis y exceso o déficit de heterocigotos. Además, se estimó la probabilidad de exclusión de paternidad por locus y general considerando los 12 loci. Los resultados indican que la variabilidad genética de los microsatélites analizados es significativamente elevada en la población estudiada. Todos los loci analizados resultaron polimórficos. El número de alelos por locus, varió entre 4 y 10. La heterocigosis esperada promedio (He), considerando todos los loci, fue de 0,76, con un rango que osciló entre 0,52 y 0,88. El promedio de la heterocigosis observada (Ho) sobre el conjunto de todos los marcadores fue de 0,65. La probabilidad de exclusión de paternidad por locus osciló entre 14 a 59%. Al considerar los 12 loci en conjunto, la exclusión de paternidad se puede atribuir con 99,7% de certeza.

Valoración estroboscópica de laringitis crónicas

INTRODUCTION

The laryngostroboscopy allows analysis of the vocal fold vibrations during phonation. Disruption of normal viscoelastic properties of the superficial lamina propria results in aberrant vocal fold vibration and mucosal wave propagation. Therefore, an investigation was performed to relate the stroboscopic results with the anatomopathologic results of chronic laryngitis and glottic cancer.

MATERIAL AND METHODS

We performed a retrospective study, which included 30 direct laryngoscopies with biopsy of 25 patients and their corresponding laryngostroboscopies.

RESULTS

60% of the cases of "absence of mucosal wave" displayed severe dysplasia or carcinoma. 20% of the cases of "limited or present mucosal wave" were carcinoma.

CONCLUSIONS

The probability of finding severe dysplasia or carcinoma is significantly greater when we find absence of mucosal wave. The presence of mucosal wave does not exclude the possibility of malignant lesion of the vocal fold.

Trisomy of the short arm of chromosome 5 due to a de novo inversion and duplication (5)(p15.3 p13.3)

Partial trisomies of the short arm of chromosome 5 are uncommon. The first description was made by Lejeune et al., in 1964. It has been suggested that the critical region for 5p trisomy syndrome lies between 5p10 and 5p13. We report on a Mexican girl who developed severe mental retardation and generalized tonic clonic seizures at age 1 year. On physical examination at age 5 years, she had macrodolichocephaly, upslanted palpebral fissures, bilateral inner epicanthic folds, low nasal root, and malformed ears with posterior rotation which are clinical characteristics of 5p trisomy syndrome. The cytogenetic study with G bands and FISH with painting for chromosome 5 and with the cri-du-chat 5p15 unique sequence probe showed a duplication and inversion of 5p [46,XX, dup(5)(p15.3 p13.3)] which overlaps with the critical region for 5p trisomy syndrome. Our patient shares clinical characteristics with the patients described in the literature with involvement of this critical region. Both parents have normal karyotypes indicating the rearrangement is de novo. Only one patient has been reported in the literature with the same cytogenetic rearrangement as our patient, but this patient had a different phenotype. Since they only performed conventional cytogenetics and we performed FISH to confirm the diagnosis, the differences in the phenotypes could be explained by the presence of other genes involved in the rearrangement. The combined use of conventional and molecular cytogenetics in this case allows a more precise diagnosis and furthers knowledge in phenotype/genotype correlation.

The clastogenic response of the 1q12 heterochromatic region to DNA cross-linking agents is independent of the Fanconi anaemia pathway

Fanconi anaemia (FA) is a rare genetic syndrome of cancer susceptibility characterized by spontaneous and induced chromosome fragility, especially after treatment with cross-linking agents. Recent investigations showed interactions between FA proteins and chromatin remodelling factors. To investigate a potential uneven distribution of the FA pathway through the human genome depending on chromatin conformation, we have analysed chromosome breakage in the largest constitutively heterochromatic region in the human genome, the 1q12 band, in lymphocytes from FA patients, carriers and healthy controls after treatment with the cross-linking agents mitomycin-C (MMC) and diepoxybutane (DEB). As expected, a higher level of MMC-induced cytotoxicity and chromosome breakage was observed in cells from FA patients when compared with normal controls and carriers. However, the increase in 1q12 breakage after increasing concentrations of MMC was of a similar magnitude in FA patients, carriers and controls. Similarly, DEB induced a high level of overall genome chromosome fragility in cells from FA patients when compared with controls with no parallel increase in chromosome breaks specifically involving the heterochromatic band 1q12. We therefore conclude that, unlike the overall genome, the sensitivity of chromosome 1 constitutive heterochromatin to the chromosome breaking activity of cross-linking agents is independent of a functional FA pathway, indicating that the action of the FA pathway is unevenly distributed through the human genome.

Spatial distribution of Reissner's fiber glycoproteins in the filum terminale of the rat and rabbit

The subcommissural organ secretes into the third ventricle glycoproteins that condense to form the Reissner's fiber (RF). At the distal end of the central canal of the spinal cord, the RF-glycoproteins accumulate in the form of an irregular mass known as massa caudalis. Antibodies against RF-glycoproteins and a set of lectins were used at the light and electron microscopic level to investigate the spatial distribution of the massa caudalis material in the rat and rabbit filum terminale. In the sacral region of the rat, the central canal presents gaps between the ependymal cells through which RF-glycoproteins spread out. The bulk of massa caudalis material, however, escapes through openings in the dorsal wall of the terminal ventricle. In the rabbit, the massa caudalis is formed within the ependymal canal, at the level of the second coccygeal vertebra, it accumulates within preterminal and terminal dilatations of the central canal, and it escapes out through gaps in the dorsal ependymal wall of the terminal ventricle. The existence of wide intercellular spaces and a large orifice (neuroporous) in the dorsal ependymal wall of the terminal ventricle, and the passage of RF-material through them, appear to be conserved evolutionary features. After leaving the terminal ventricle of the rat and rabbit, RF-glycoproteins establish a close spatial association with the numerous blood vessels irrigating the filum terminale, suggesting that in these species the blood vessels are the site of destination of the RF-glycoproteins escaping from the central canal, thus resembling the situation found in lower vertebrates. When passing from the RF stage to the massa caudalis stage, the rabbit RF-glycoproteins lose their sialic acid residues, exposing galactose as the terminal residue. Since this sialic acid-galactose modification of RF-glycoproteins had also been described in lamprey larvae, it may be regarded as a conserved evolutionary feature associated with the formation of the massa caudalis.

Genotoxic studies of vanadium pentoxide (V(2)O(5)) in male mice. II. Effects in several mouse tissues

Vanadium pentoxide (V2O5) was tested for its ability to induce genotoxic damage in six different organs (liver, kidney, lung, spleen, heart, and bone marrow) of mice by using the alkaline Single Cell Gel Electrophoresis (SCGE) assay. Animals were sacrificed 24 h after i.p. administration of the vanadium pentoxide of 23.0, 11.5, or 5.75 microg/g (corresponding to the LD50, 1/2 LD50 and 1/4 LD50, respectively). In all tissues and organs evaluated (except for bone marrow), V2O5 increased the number of cells with damage. Our results showed that i.p. injection of V2O5 induced DNA damage in different organs and tissues, and that this kind of damage can be observed even 24 h after treatment. The analysis of DNA migration and the distribution of DNA damage showed that there are differences in sensitivity between organs and tissues to this compound. In addition the sensitivity of SCGE assay allows the detection of long term DNA damage and the possibility to compare it in various tissues and target organs.

Determination of normative criteria and validation of the SKT for use in Spanish-speaking populations

Most of the tests, questionnaires, and neuropsychological batteries for the assessment of dementia have been translated and adapted for use in the Hispanic population without having normative data, which results in a high number of false positives when age and educational level are not considered. The Short Cognitive Performance Test (SKT) is a psychometric instrument evaluating memory and attention deficits that has been developed and standardized in Germany (Erzigkeit, 1989a, 1989b). The objective of this study was to adapt the SKT, to establish normative criteria that take into consideration age and educational level, and to establish its concurrent validity in comparison to other neuropsychological tests: Brief Neuropsychological Evaluation for Spanish-Speaking Subjects (Ostrosky-Solis et al., 1994), the Mini-Mental State Examination (Folstein et al., 1975), and the Blessed Functional Scale (Blessed et al., 1968) in 238 neurologically intact subjects and 97 subjects with mild to moderate dementia. The SKT showed adequate sensitivity (80.5%) and specificity (80.3%) in subjects with medium and high educational level; however, the sensitivity and specificity diminished (75% and 56.7%) in subjects with no education or low educational level. The adapted and validated version of the SKT in the Mexican population has been shown to be a psychometric instrument that in subjects with medium educational level can detect cognitive alterations and is able to determine the severity of deterioration; however, in subjects with low educational level and severe dementia, the SKT cannot be usefully administered.

Chromosome instability with bleomycin and X-ray hypersensitivity in a boy with Nijmegen breakage syndrome

We report on a Mexican boy with microcephaly, short stature, and a high frequency of chromosome aberrations with rearrangements involving chromosomes 7 and 14, typical of ataxia telangiectasia (AT) patients. He had neither ataxia nor telangiectasia, and his immunological status and serum alpha feto protein (AFP) level were normal. Bleomycin hypersensitivity, which has been demon-strated in AT patients, was tested in the patient using AT and normal subjects for comparison. The frequency of spontaneously occurring chromosome aberrations in lymphocyte cultures was significantly higher in the patient and the AT patient than in the normal subject. Four cells from the patient showed structural rearrangements involving chromosomes 7 or 14, with breakpoints typical for AT. When exposed to 5.0 micrograms bleomycin, the lymphocytes from the AT patient showed the highest sensitivity to this agent; our patient had an intermediate sensitivity. In both patients several rearrangements involving chromosomes 7 and 14 were scored, while none were observed in the normal subject. A colony survival assay (CSA) [Huo et al., 1994: Cancer Res 54:2544-2547], using a lymphoblastoid cell line (LCL) derived from our patient, showed a survival fraction (SF) of 7%, which is in the same range as in AT patients. The clinical picture, together with the cytogenetic and radiosensitivity results, suggests that our patient fits the variable spectrum of Nijmegen breakage syndrome.

Effect of hydroxyurea and normal plasma on DNA synthesis in lymphocytes from Fanconi anemia patients

Fanconi anemia (FA) is characterized at the cellular level by a high frequency of spontaneous chromosomal aberrations; crosslinking agents cause an abnormal increase in the frequency of chromosomal damage, and semiconservative DNA synthesis is severely inhibited. Deoxyribonucleotides are needed in both semiconservative and repair DNA synthesis. To investigate the involvement of deoxyribonucleotide pools in the inhibition of DNA synthesis in FA, we evaluated the effect on FA lymphocytes of hydroxyurea (HU), an inhibitor of ribonucleotide reductase which is known to alter the intracellular levels of deoxyribonucleotides. To achieve this goal, lymphocyte cultures of 4 FA patients and 4 normal individuals were used. Cultures were treated with HU and/or mitomycin C and normal human plasma. All cultures were processed to detect the number of DNA synthesizing nuclei by autoradiography. Scoring of 2000 nuclei for each kind of culture every 6 h in the last 24 h of incubation showed that, in long incubation periods, DNA synthesis in FA is largely inhibited by HU and this hypersensitivity may be partially decreased by addition of normal human plasma. It is known that recovery from damage induced by HU involves several enzymes such as flavin oxido-reductase, superoxide dismutase and catalase which are involved in the production or scavenging of O2 radicals; FA cells are deficient in the detoxification of oxygen and this could explain the response of FA cells to HU.

[Detection of aneuploidies using in situ hybridization in cells of the oral mucosa]

Aneuploidies have been traditionally diagnosed by chromosome analysis, however this method may be difficult to perform in certain cellular types or in severely ill patients. With the fluorescence in situ hybridization (FISH) technique it is possible to identify the number of specific chromosomes in interphase cells. In the present study we analyzed exfoliated epithelial cells from the oral mucosa of 15 patients with trisomy 21, and in six patients with mosaicism; five normal subjects were included for comparison. To allow the probe to reach its target DNA we first treated the keratin-surrounded membrane with pepsin during 20 minutes. In the 15 cases of trisomy 21, the cells showed five fluorescent signals indicating the presence of three chromosomes 21 and two 13, while the normal subjects showed four signals. In one girl with Turner syndrome and a karyotype 46,X+mar, the FISH analysis in 1000 cells revealed that the marker derived from chromosome X and there was a mosaicism 45,X/46,X,r(X). In the other patients with mosaicisms, we observed variations in the proportions of cells but the differences were not significant. In conclusion, interphase FISH on buccal cells showed to be a rapid, effective and non-invasive method for the diagnosis of chromosome aberrations, particularly when the cytogenetic study on lymphocytes is difficult to perform.

[Effects of the addition of conditioned media on the response of Fanconi anemia lymphocytes to mitomycin C]

It has been shown that the addition of normal plasma to Fanconi anemia (FA) lymphocyte cultures significantly decreases the frequency of mitomycin C (MMC) induced chromosome aberrations, suggesting that normal plasma contains a diffusible correction factor (CF) which is able to partially complement FA lymphocytes. On the other hand, there is evidence suggesting that FA cells are defective in the DNA postreplicative repair. CF could then be involved in DNA repair processes and in possible inducible mechanisms. In the present study MMC-treated FA lymphocytes were grown during the last 24 hours of culture, in conditioned media obtained from untreated and MMC-treated normal cells. The purpose was to investigate if MMC-stressed normal cells were induced to produce CF in vitro. The results failed to show a constant decrease of FA cells chromosome aberrations when plasma-free conditioned media from MMC-stressed normal cells were added (experiments 2 and 3). However, when the conditioned media were supplemented with normal plasma (experiments 1 and 4) a partial repair of MMC-induced damage of the FA cells was observed. The results suggest the presence of CF in normal plasma and two possible mechanisms of action are suggested: CF is involved in DNA repair of MMC-damaged FA cells or it induces cellular division selecting the less damaged cell population through mitosis.

[Effect of gamma radiations on robertsonian translocations]

Centromeric breaks and the dissociation of Robertsonian translocations have been regarded as the possible cause of a few reported cases of mosaicism. In a previous study we suggested that the dissociative phenomenon is influenced by an instability of the point of fusion, when it is located on a heterochromatic region, which appears to be a preferential mitomycin C (MMC) breakpoint. In this study lymphocytes from 6 robertsonian translocation carriers were treated with gamma rays. In one case who was a mosaic, the MMC induced a statistically significant increase in the number of cells with the dissociation. In the remaining cases, centromeric breaks or complete fissions were observed in 1.8% of the cells. In addition, the analysis of the distribution of breakage points on heterochromatic or euchromatic regions showed that almost 50% of the breaks on translocation chromosomes were located on pericentromeric heterochromatin. We postulate that the dissociation which occurs in robertsonian translocations may be caused by instability of the point of fusion since it is located on a heterochromatic region, susceptible to breakage by clastogenic agents such as MMC and gamma rays.

[Effect of mitomycin C (MMC) on the fusion points of reciprocal translocations]

Lymphocytes from five patients having a reciprocal translocation were exposed to MMC to test the stability of the point of reunion which was localized in an euchromatic region. The results showed that the point of fusion in this type of translocations in not a preferential breakpoint. In a patient carrier of a (1;7) translocation, the derivate chromosome showed a significant increased number of breaks compared with the homologous chromosomes. No explanation is available for this finding. Our results support the hypothesis that the observed dissociation of Robertsonian translocation is related to the fact that the point of reunion is located in a heterochromatic region.

[A new syndrome of mental retardation and chromosomic instability in 3 siblings]

We report on three brothers with mental retardation, microcephaly and prominent ears whose cytogenetic studies showed no fragile X. However, an elevated frequency of spontaneous chromosome aberrations compared with that in normal individuals was found. The chromosome aberrations included acentric fragments, rings, dicentrics and radial figures. The lymphocytes did not show an increased sensitivity to mitomycin C nor to gamma radiation. It is suggested that this is a new hereditary syndrome of mental retardation with chromosome instability, probably recessive X linked.

Pulmonary management during extracorporeal membrane oxygenation

Traditional lung management during extracorporeal membrane oxygenation (ECMO) calls for low inspiratory and expiratory pressures with low ventilator rate to achieve lung rest. However, rapid weaning of pressures to severely injured lungs commonly leads to marked increase in pulmonary opacification as seen on chest x-ray and loss of volume. We postulated that a sufficiently high level of PEEP could prevent this deterioration. Forty-six newborns, who required ECMO therapy for refractory respiratory failure, were maintained on 8 to 14 cm H2O PEEP. The peak pressure was 20 to 24 cm H2O, rate 10 to 15 breath/min, and FIO2 0.21. Forty-one (89%) of 46 patients survived to discharge. The duration of ECMO was significantly decreased compared to the national average (82.4 +/- 43 vs. 117.5 +/- 59 h). The lungs of most patients remained adequately expanded and free of severe pulmonary opacification. Eleven of 40 patients did show significant worsening of chest x-ray compared to baseline, but only one of 18 who were on PEEP of greater than or equal to 12 cm H2O showed such deterioration. No unexpected complications were encountered. These data suggest that the use of high PEEP during ECMO safely prevents deterioration of lung function and promotes more rapid lung recovery. PEEP levels of 12 to 14 cm H2O appear to be most effective.

[Synergism of bromodeoxyuridine and mitomycin C in the production of chromosomal aberrations in Fanconi's anemia]

Synergism of BrdU and MMC on the production of chromosome aberrations in lymphocytes of patients with Fanconi's anemia (FA) was studied. With this purpose, the lymphocytes of an FA patient and of a normal subject were cultured and exposed to BrdU and to MMC in 6 different experiments. The results showed no synergism of these two agents in normal cells. However FA cells exposed to BrdU and MMC showed an increased frequency of aberrations suggesting synergism. Furthermore the chromosome damage produced by MMC was significantly increased by the presence of BrdU in the medium. These results support the hypothesis of a defect of DNA repair in FA cells.

Combined high-frequency jet ventilation in a meconium aspiration model

To evaluate the effectiveness of high-frequency jet ventilation (HFJV) in the treatment of meconium aspiration, 28 puppies were assigned randomly to one of three ventilator techniques. After aspiration of 4 ml/kg of 20% meconium and baseline measurements on conventional ventilation (CV), the animals were ventilated for 6 h with either CV, HFJV, or HFJV combined with slow conventional ventilation (combined HFJV). Arterial and mixed venous blood gases, systemic and pulmonary arterial pressures, pulmonary capillary wedge pressure, and cardiac output were measured. Combined HFJV proved superior to the other two techniques, resulting in significantly better oxygenation and ventilation at a lower mean airway pressure (Paw). Oxygenation with standard HFJV was comparable to CV, producing Paw and PCO2 values intermediate between those of CV and combined HFJV. There were no significant intergroup differences in cardiac output or the incidence of pneumothorax. Improved gas exchange was attributed to alveolar recruitment and prevention of atelectasis. Alteration of the distribution and/or clearance of meconium may also be important.

Crossed atrioventricular connections

Four cases of crossed atrioventricular connections are described. All of them were diagnosed at cardiac catheterization by angiocardiography and one was examined pathologically. Two possessed situs solitus, one with concordant connections and the other with discordant connections; the other had two situs inversus, both of them with concordant connections. Two had double-outlet right ventricle, one had transposition of the great arteries, and the other had normally related and connected great arteries. These cases have been interpreted as representing abnormal rotation of the ventricles following sepatation. A review of 36 cases previously reported on and our own cases, suggests that most patients have concordant atrioventricular connections. There are many types of ventriculo-arterial connections, the most frequent being transposition of the great arteries. There has not been any case reported with persistent truncus arteriosus. On the basis of atrioventriculo-arterial connections, we propose a classification for this malformation. We discuss the importance of the bulboventricular loop in the type of atrioventricular connections, some clinical implications for the diagnosis, and analyze the value of the rules to localize the ventricles by means of the position of the great arteries.

[Diagnostic problems in visceral heterotaxia]

Due to the lack of uniformity in the criteria for formulating the diagnosis of the syndrome of heterotaxy, 12 cases with this abnormality were reviewed. The patients were selected on the following basis: symmetrical liver, changeable P waves in consecutive electrocardiograms, bronchial isomerism, hematological disturbances, anomalous relationship of the inferior vena cava and abdominal aorta, anomalous systemic and pulmonary venous drainage and complex cardiac malformations. The most frequent findings were: symmetrical liver, changeable P waves, anomalous systemic venous return, anomalies of the atrio-ventricular valves, particularly atrioventricular canal, aorto-cava juxtaposition, single atrium, anomalous pulmonary venous return, transposition of the great arteries and pulmonary stenosis. Less frequent anomalies were: atrial and ventricular septal defects, atrial isomerism, truncus arteriosus and partial distortion of the great arteries. The hematological disturbances as well as the radioisotope scanning of the liver and the spleen were of little help. Suggestions are given for the diagnosis of the syndrome and for the evaluation of present diagnostic procedures making necessary to use the data gathered with more precision.

[Type A Wolff-Parkinson-White syndrome associated with left bundle-branch block. Electrocardiographic, vectorcardiographic, and endocavitary electrophysiological study]

The rate association of a "type A" W.P.W. syndrome with a left bundle branch block gives a characteristic electrocardiographic picture:--the left bundle branch block is partially masked, the delay in the basial region of the left ventricle being in part cancelled by pre-excitation--the features of the W.P.W. syndrome are also modified, since the ventricular axis is corrected by the left bundle branch block. The electrocardiographic tracings taken during the various tachycardias and during treatment for arrhythmia, together with the intra-cavitary recordings allow a precise diagnosis to be made. In this case, vectocardiography was particularly useful as it gave a clear demonstration of the median delay of the ventricular loop, the only pathognomic feature of left bundle branch block, during a period when the left bundle of Kent was functioning.