ApoE maintains neuronal integrity via microRNA and H3K27me3-mediated repression

ApoE regulates neurogenesis, although how it influences genetic programs remains elusive. Cortical neurons induced from isogenic control and ApoE-/- human neural stem cells (NSCs) recapitulated key transcriptomic signatures of in vivo counterparts identified from single-cell human midbrain. Surprisingly, ApoE expression in NSC and neural progenitor cells (NPCs) is not required for differentiation. Instead, ApoE prevents the over-proliferation of non-neuronal cells during extended neuronal culture when it is not expressed. Elevated miR-199a-5p level in ApoE-/- cells lowers the EZH1 protein and the repressive H3K27me3 mark, a phenotype rescued by miR-199a-5p steric inhibitor. Reduced H3K27me3 at genes linked to extracellular matrix organization and angiogenesis in ApoE-/- NPC correlates with their aberrant expression and phenotypes in neurons. Interestingly, the ApoE coding sequence, which contains many predicted miR-199a-5p binding sites, can repress miR-199a-5p without translating into protein. This suggests that ApoE maintains neurons integrity through the target-directed miRNA degradation of miR-199a-5p, imparting the H3K27me3-mediated repression of non-neuronal genes during differentiation.

Variants of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and Vaccine Effectiveness

The incidence and death toll due to SARS-CoV-2 infection varied time-to-time; and depended on several factors, including severity (viral load), immune status, age, gender, vaccination status, and presence of comorbidities. The RNA genome of SARS-CoV-2 has mutated and produced several variants, which were classified by the SARS-CoV-2 Interagency Group (SIG) into four major categories. The first category; “Variant Being Monitored (VBM)”, consists of Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), Epsilon (B.1.427, B.1.429), Eta (B.1.525), Iota (B.1.526), Kappa (B.1.617.1), Mu (B.1.621), and Zeta (P.2); the second category; “Variants of Concern” consists of Omicron (B.1.1.529). The third and fourth categories include “Variants of Interest (VOI)”, and “Variants of High Consequence (VOHC)”, respectively, and contain no variants classified currently under these categories. The surge in VBM and VOC poses a significant threat to public health globally as they exhibit altered virulence, transmissibility, diagnostic or therapeutic escape, and the ability to evade the host immune response. Studies have shown that certain mutations increase the infectivity and pathogenicity of the virus as demonstrated in the case of SARS-CoV-2, the Omicron variant. It is reported that the Omicron variant has >60 mutations with at least 30 mutations in the Spike protein (“S” protein) and 15 mutations in the receptor-binding domain (RBD), resulting in rapid attachment to target cells and immune evasion. The spread of VBM and VOCs has affected the actual protective efficacy of the first-generation vaccines (ChAdOx1, Ad26.COV2.S, NVX-CoV2373, BNT162b2). Currently, the data on the effectiveness of existing vaccines against newer variants of SARS-CoV-2 are very scanty; hence additional studies are immediately warranted. To this end, recent studies have initiated investigations to elucidate the structural features of crucial proteins of SARS-CoV-2 variants and their involvement in pathogenesis. In addition, intense research is in progress to develop better preventive and therapeutic strategies to halt the spread of COVID-19 caused by variants. This review summarizes the structure and life cycle of SARS-CoV-2, provides background information on several variants of SARS-CoV-2 and mutations associated with these variants, and reviews recent studies on the safety and efficacy of major vaccines/vaccine candidates approved against SARS-CoV-2, and its variants.

Development and cross-cultural adaptation of the vestibular disorders activities of daily living scale in the kannada language and testing its psychometric properties

Background

Vestibular Disorders Activities of Daily Living Scale (VADL) is a self-reported survey for assessing functions of individuals affected by vestibular disorders, and this survey has been translated and cross-culturally adapted into many languages.

Objective

: Kannada is one of the most-spoken languages in India, with approximately 64 million speakers. We aimed to develop the Kannada version of VADL and to assess its psychometric properties.

Materials and Methods

The translation and adaptation of the English version of VADL into Kannada were accomplished with the input of medical professional language experts. Pretesting of the Kannada VADL (VADL-K) was conducted on 30 patients with vestibular disorders. Six professional experts with medical background provided their opinion during the content validation process of VADL-K, and 50 subjects aged between 30 and 70 years with variant vestibular disorders were administered VADL-K and the Dizziness Handicap Inventory to determine the internal consistency, test-retest reliability, and concurrent validity of this assessment.

Results

This study effectively translated, adapted, and pretested VADL-K. The scale's content validity was 0.95, its internal consistency (Cronbach's alpha = α) was 0.94, its test-retest reliability with Intra Class- Correlation Coefficient was 0.97, and its concurrent validity in comparison with DHI was significant, with a moderate correlation r-value of 0.58.

Conclusion

The English version of VADL was successfully translated and adapted into the Kannada language. VADL-K is a valid and reliable measure for patients with vestibular disorders in the state of Karnataka to report their functional performance.

EHMT2 epigenetically suppresses Wnt signaling and is a potential target in embryonal rhabdomyosarcoma

Wnt signaling is downregulated in embryonal rhabdomyosarcoma (ERMS) and contributes to the block of differentiation. Epigenetic mechanisms leading to its suppression are unknown and could pave the way toward novel therapeutic modalities. We demonstrate that EHMT2 suppresses canonical Wnt signaling by activating expression of the Wnt antagonist DKK1. Inhibition of EHMT2 expression or activity in human ERMS cell lines reduced DKK1 expression and elevated canonical Wnt signaling resulting in myogenic differentiation in vitro and in mouse xenograft models in vivo. Mechanistically, EHMT2 impacted Sp1 and p300 enrichment at the DKK1 promoter. The reduced tumor growth upon EHMT2 deficiency was reversed by recombinant DKK1 or LGK974, which also inhibits Wnt signaling. Consistently, among 13 drugs targeting chromatin modifiers, EHMT2 inhibitors were highly effective in reducing ERMS cell viability. Our study demonstrates that ERMS cells are vulnerable to EHMT2 inhibitors and suggest that targeting the EHMT2-DKK1-β-catenin node holds promise for differentiation therapy.

Phosphorylation of Tet3 by cdk5 is critical for robust activation of BRN2 during neuronal differentiation

Tet3 regulates the dynamic balance between 5-methylcyotsine (5mC) and 5-hydroxymethylcytosine (5hmC) in DNA during brain development and homeostasis. However, it remains unclear how its functions are modulated in a context-dependent manner during neuronal differentiation. Here, we show that cyclin-dependent kinase 5 (cdk5) phosphorylates Tet3 at the highly conserved serine 1310 and 1379 residues within its catalytic domain, changing its in vitro dioxygenase activity. Interestingly, when stably expressed in Tet1, 2, 3 triple-knockout mouse embryonic stem cells (ESCs), wild-type Tet3 induces higher level of 5hmC and concomitant expression of genes associated with neurogenesis whereas phosphor-mutant (S1310A/S1379A) Tet3 causes elevated 5hmC and expression of genes that are linked to metabolic processes. Consistent with this observation, Tet3-knockout mouse ESCs rescued with wild-type Tet3 have higher level of 5hmC at the promoter of neuron-specific gene BRN2 when compared to cells that expressed phosphor-mutant Tet3. Wild-type and phosphor-mutant Tet3 also exhibit differential binding affinity to histone variant H2A.Z. The differential 5hmC enrichment and H2A.Z occupancy at BRN2 promoter is correlated with higher gene expression and more efficient neuronal differentiation of ESCs that expressed wild-type Tet3. Taken together, our results suggest that cdk5-mediated phosphorylation of Tet3 is required for robust activation of neuronal differentiation program.

GLP inhibits heterochromatin clustering and myogenic differentiation by repressing MeCP2

Myogenic differentiation is accompanied by alterations in the chromatin states, which permit or restrict the transcriptional machinery and thus impact distinctive gene expression profiles. The mechanisms by which higher-order chromatin remodeling is associated with gene activation and silencing during differentiation is not fully understood. In this study, we provide evidence that the euchromatic lysine methyltransferase GLP regulates heterochromatin organization and myogenic differentiation. Interestingly, GLP represses expression of the methyl-binding protein MeCP2 that induces heterochromatin clustering during differentiation. Consequently, MeCP2 and HP1γ localization at major satellites are altered upon modulation of GLP expression. In GLP knockdown cells, depletion of MeCP2 restored both chromatin organization and myogenic differentiation. These results identify a novel regulatory axis between a histone methylation writer and DNA methylation reader, which is important for heterochromatin organization during differentiation.

Epigenetic Regulation of the PTEN-AKT-RAC1 Axis by G9a Is Critical for Tumor Growth in Alveolar Rhabdomyosarcoma

Alveolar rhabdomyosarcoma (ARMS) is an aggressive pediatric cancer with poor prognosis. As transient and stable modifications to chromatin have emerged as critical mechanisms in oncogenic signaling, efforts to target epigenetic modifiers as a therapeutic strategy have accelerated in recent years. To identify chromatin modifiers that sustain tumor growth, we performed an epigenetic screen and found that inhibition of lysine methyltransferase G9a significantly affected the viability of ARMS cell lines. Targeting expression or activity of G9a reduced cellular proliferation and motility in vitro and tumor growth in vivo. Transcriptome and chromatin immunoprecipitation-sequencing analysis provided mechanistic evidence that the tumor-suppressor PTEN was a direct target gene of G9a. G9a repressed PTEN expression in a methyltransferase activity-dependent manner, resulting in increased AKT and RAC1 activity. Re-expression of constitutively active RAC1 in G9a-deficient tumor cells restored oncogenic phenotypes, demonstrating its critical functions downstream of G9a. Collectively, our study provides evidence for a G9a-dependent epigenetic program that regulates tumor growth and suggests targeting G9a as a therapeutic strategy in ARMS. SIGNIFICANCE: These findings demonstrate that RAC1 is an effector of G9a oncogenic functions and highlight the potential of G9a inhibitors in the treatment of ARMS.

Chromatin Immunoprecipitation in Skeletal Myoblasts

Chromatin immunoprecipitation (ChIP) is a powerful and sensitive technique that is widely used to study DNA-protein interactions. It enables an unbiased genome-wide analysis of transcriptional changes during several biological processes including cellular differentiation. Here, we describe a step-by-step protocol to identify histone modifications, transcription factor, and co-factor binding to chromatin in skeletal myoblasts. We discuss critical steps during cell harvesting, sonication, and immunoprecipitation and provide notes to evade common pitfalls.

Unraveling the role of aurora A beyond centrosomes and spindle assembly: implications in muscle differentiation

Aurora kinases are critical mitotic serine/threonine kinases and are often implicated in tumorigenesis. Recent studies of the interphase functions for aurora kinase (Aurk)A have considerably expanded our understanding of its role beyond mitosis. To identify the unknown targets of AurkA, we used peptide array-based screening and found E2F4 to be a novel substrate. Phosphorylation of E2F4 by AurkA at Ser75 regulates its DNA binding and subcellular localization. Because E2F4 plays an important role in skeletal muscle differentiation, we attempted to gain insight into E2F4 phosphorylation in this context. We observed that a block in E2F4 phosphorylation retained it better within the nucleus and inhibited muscle differentiation. RNA sequencing analysis revealed a perturbation of the gene network involved in the process of muscle differentiation and mitochondrial biogenesis. Collectively, our findings establish a novel role of AurkA in the process of skeletal muscle differentiation.-Dhanasekaran, K., Bose, A., Rao, V. J., Boopathi, R., Shankar, S. R., Rao, V. K., Swaminathan, A., Vasudevan, M., Taneja, R., Kundu, T. K. Unravelling the role of aurora A beyond centrosomes and spindle assembly: implications in muscle differentiation.

A drive in SUVs: From development to disease

Progression of cells through distinct phases of the cell cycle, and transition into out-of-cycling states, such as terminal differentiation and senescence, is accompanied by specific patterns of gene expression. These cell fate decisions are mediated not only by distinct transcription factors, but also chromatin modifiers that establish heritable epigenetic patterns. Lysine methyltransferases (KMTs) that mediate methylation marks on histone and non-histone proteins are now recognized as important regulators of gene expression in cycling and non-cycling cells. Among these, the SUV39 sub-family of KMTs, which includes SUV39H1, SUV39H2, G9a, GLP, SETDB1, and SETDB2, play a prominent role. In this review, we discuss their biochemical properties, sub-cellular localization and function in cell cycle, differentiation programs, and cellular senescence. We also discuss their aberrant expression in cancers, which exhibit de-regulation of cell cycle and differentiation.

P/CAF mediates PAX3-FOXO1-dependent oncogenesis in alveolar rhabdomyosarcoma

Alveolar rhabdomyosarcoma (ARMS) is an aggressive paediatric cancer of skeletal muscle with poor prognosis. A PAX3-FOXO1 fusion protein acts as a driver of malignancy in ARMS by disrupting tightly coupled but mutually exclusive pathways of proliferation and differentiation. While PAX3-FOXO1 is an attractive therapeutic target, no current treatments are designed to block its oncogenic activity. The present work shows that the histone acetyltransferase P/CAF (KAT2B) is overexpressed in primary tumours from ARMS patients. Interestingly, in fusion-positive ARMS cell lines, P/CAF acetylates and stabilizes PAX3-FOXO1 rather than MyoD, a master regulator of muscle differentiation. Silencing P/CAF, or pharmacological inhibition of its acetyltransferase activity, down-regulates PAX3-FOXO1 levels concomitant with reduced proliferation and tumour burden in xenograft mouse models. Our studies identify a P/CAF-PAX3-FOXO1 signalling node that promotes oncogenesis and may contribute to MyoD dysfunction in ARMS. This work exemplifies the therapeutic potential of targeting chromatin-modifying enzymes to inhibit fusion oncoproteins that are a frequent event in sarcomas. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

G9a inhibits MEF2C activity to control sarcomere assembly

In this study, we demonstrate that the lysine methyltransferase G9a inhibits sarcomere organization through regulation of the MEF2C-HDAC5 regulatory axis. Sarcomeres are essential for muscle contractile function. Presently, skeletal muscle disease and dysfunction at the sarcomere level has been associated with mutations of sarcomere proteins. This study provides evidence that G9a represses expression of several sarcomere genes and its over-expression disrupts sarcomere integrity of skeletal muscle cells. G9a inhibits MEF2C transcriptional activity that is essential for expression of sarcomere genes. Through protein interaction assays, we demonstrate that G9a interacts with MEF2C and its co-repressor HDAC5. In the presence of G9a, calcium signaling-dependent phosphorylation and export of HDAC5 to the cytoplasm is blocked which likely results in enhanced MEF2C-HDAC5 association. Activation of calcium signaling or expression of constitutively active CaMK rescues G9a-mediated repression of HDAC5 shuttling as well as sarcomere gene expression. Our results demonstrate a novel epigenetic control of sarcomere assembly and identifies new therapeutic avenues to treat skeletal and cardiac myopathies arising from compromised muscle function.

G9a promotes proliferation and inhibits cell cycle exit during myogenic differentiation

Differentiation of skeletal muscle cells, like most other cell types, requires a permanent exit from the cell cycle. The epigenetic programming underlying these distinct cellular states is not fully understood. In this study, we provide evidence that the lysine methyltransferase G9a functions as a central axis to regulate proliferation and differentiation of skeletal muscle cells. Transcriptome analysis of G9a knockdown cells revealed deregulation of many cell cycle regulatory genes. We demonstrate that G9a enhances cellular proliferation by two distinct mechanisms. G9a blocks cell cycle exit via methylation-dependent transcriptional repression of the MyoD target genes p21(Cip/Waf1) and Rb1. In addition, it activates E2F1-target genes in a methyltransferase activity-independent manner. We show that G9a is present in the E2F1/PCAF complex, and enhances PCAF occupancy and histone acetylation marks at E2F1-target promoters. Interestingly, G9a preferentially associates with E2F1 at the G1/S phase and with MyoD at the G2/M phase. Our results provide evidence that G9a functions both as a co-activator and a co-repressor to enhance cellular proliferation and inhibit myogenic differentiation.

A unique role for p53 in the regulation of M2 macrophage polarization

P53 is critically important in preventing oncogenesis but its role in inflammation in general and in the function of inflammatory macrophages in particular is not clear. Here, we show that bone marrow-derived macrophages exhibit endogenous p53 activity, which is increased when macrophages are polarized to the M2 (alternatively activated macrophage) subtype. This leads to reduced expression of M2 genes. Nutlin-3a, which destabilizes the p53/MDM2 (mouse double minute 2 homolog) complex, promotes p53 activation and further downregulates M2 gene expression. In contrast, increased expression of M2 genes was apparent in M2-polarized macrophages from p53-deficient and p53 mutant mice. Furthermore, we show, in mice, that p53 also regulates M2 polarization in peritoneal macrophages from interleukin-4-challenged animals and that nutlin-3a retards the development of tolerance to Escherichia coli lipopolysaccharide. P53 acts via transcriptional repression of expression of c-Myc (v-myc avian myelocytomatosis viral oncogene homolog) gene by directly associating with its promoter. These data establish a role for the p53/MDM2/c-MYC axis as a physiological 'brake' to the M2 polarization process. This work reveals a hitherto unknown role for p53 in macrophages, provides further insight into the complexities of macrophage plasticity and raises the possibility that p53-activating drugs, many of which are currently being trialled clinically, may have unforeseen effects on macrophage function.

Reduction of non-enzymatic browning of orange juice and semi-concentrates by removal of reaction substrate

A study was conducted to standardize the technology for the removal of amino acids (one of the browning reaction substrates) from sweet orange cv. Malta Common juice to reduce colour and quality deterioration in single strength juice and during subsequent concentration. Juice of sweet orange (Citrus sinensis) cv. Malta Common fruits was extracted by screw type juice extractor, preserved in 500 ppm SO2 and clarified by using "Pectinase CCM" enzyme (0.2% for 2 h at 50 ± 2 °C). For removal of amino acids juice was passed under gravity through a glass column packed with an acidic cation exchange resin (CER), Dowex-50 W and quantity to be treated in one lot was standardized. The CER treated and untreated juices were concentrated to 15 and 30°Brix in a rotary vacuum evaporator. Results indicate that 121 ml of orange juice when passed through a glass column (5 cm internal diameter) packed with cation exchange resin (Dowex-50 W) upto a height of 8 cm, could remove about 98.4% of the amino acids with minimum losses in other juice constituents. With cation exchange resin treatment, the non-enzymatic browning and colour deterioration of orange juice semi-concentrates was reduced to about 3 folds in comparison to untreated counterparts. The retention of vitamin C and sugars was also better in semi-concentrates prepared from cation exchange resin treated juice. Thus, cation exchange resin treatment of orange juice prior to concentration and storage is highly beneficial in reduction of non-enzymatic browning, colour deterioration and retention of nutritional, sensory quality of product during preparation and storage.

Probing p300/CBP associated factor (PCAF)-dependent pathways with a small molecule inhibitor

PCAF (KAT2B) belongs to the GNAT family of lysine acetyltransferases (KAT) and specifically acetylates the histone H3K9 residue and several nonhistone proteins. PCAF is also a transcriptional coactivator. Due to the lack of a PCAF KAT-specific small molecule inhibitor, the exclusive role of the acetyltransferase activity of PCAF is not well understood. Here, we report that a natural compound of the hydroxybenzoquinone class, embelin, specifically inhibits H3Lys9 acetylation in mice and inhibits recombinant PCAF-mediated acetylation with near complete specificity in vitro. Furthermore, using embelin, we have identified the gene networks that are regulated by PCAF during muscle differentiation, further highlighting the broader regulatory functions of PCAF in muscle differentiation in addition to the regulation via MyoD acetylation.

G9a, a multipotent regulator of gene expression

Lysine methylation of histone and non-histone substrates by the methyltransferase G9a is mostly associated with transcriptional repression. Recent studies, however, have highlighted its role as an activator of gene expression through mechanisms that are independent of its methyltransferase activity. Here we review the growing repertoire of molecular mechanisms and substrates through which G9a regulates gene expression. We also discuss emerging evidence for its wide-ranging functions in development, pluripotency, cellular differentiation and cell cycle regulation that underscore the complexity of its functions. The deregulated expression of G9a in cancers and other human pathologies suggests that it may be a viable therapeutic target in various diseases.

Scleritis and multiple systemic autoimmune manifestations in chronic natural killer cell lymphocytosis associated with elevated TCRalpha/beta+CD3+CD4-CD8- double-negative T cells

BACKGROUND/AIMS

Chronic natural killer lymphocytosis (CNKL) has been associated with systemic autoimmunity; however, its association with scleritis or ocular autoimmunity has not been characterised. The natural killer (NK) cell function and immunophenotype of a patient with CNKL who developed bilateral scleritis and multiple systemic autoimmune findings were evaluated.

METHODS

The ophthalmic records of a patient with CNKL and scleritis were reviewed over a 6-year period. Flow cytometry was performed to evaluate T cell, NK and B cell populations. NK cellular functions (ie, NK cytotoxicity and cytokine/chemokine production following interleukin 2 (IL2) stimulation) were evaluated.

RESULTS

A 56-year-old woman with vitiligo, psoriatic arthritis, thyroiditis, erythema nodosum, bilateral anterior scleritis and Sjogren syndrome was managed with multiple immunosuppressive medications, including prednisone, mycophenolate mofetil and methotrexate. Flow cytometry showed a persistent elevation of CD56(+)CD3(-) NK cells greater than 40%, which was consistent with CNKL. NK cell cytotoxicity assay identified a deficiency of K562 cell lysis in the patient (1.46 mean-fold greater in control vs patient). NK cytokine/chemokine production following IL2 stimulation was also deficient (2.5-32.5-fold greater in control). Cytokines/chemokines assessed included pro-inflammatory (interferon gamma, tumor necrosis factor alpha, IL1, monocyte chemotactic protein 1) and immunoregulatory cytokines (IL4, IL5 and IL10). An abnormal elevation of TCRalpha/beta(+) CD3(+)CD4(-)CD8(-) T cells suggestive of autoimmune lymphoproliferative syndrome was observed; however, apoptosis dysfunction was not found.

CONCLUSION

The association of increased but dysfunctional NK cells in the context of multiple systemic and ocular manifestations suggests a role of NK cells in the pathogenesis of our patient's disease. Further studies regarding NK cell dysfunction and ocular autoimmunity are needed.

Hemifacial motor and crying seizures of temporal lobe onset: case report and review of electro-clinical localisation

OBJECTIVE

To report a case of temporal lobe epilepsy with clinical presentation of paroxysmal episodes of "tightness" over the right hemiface, and ictal crying, and review electroclinical localisation of this phenomenon.

METHODS

Clinical semiology, neurophysiological localising tests, and epilepsy surgery outcome are reported in a subject presenting with paroxysmal right hemifacial movements and ictal crying. Pertinent past reports of somato-motor signs and ictal crying in temporal lobe epilepsy are reviewed and the findings correlated with proposed human facial cortical representation.

RESULTS

Simple partial seizures caused by temporal lobe epilepsy presented with right sided tonic facial movements and ictal crying. Intracranial EEG monitoring documented a left medial temporal onset of seizures that remained asymptomatic until they propagated to the left cingulate region. Anterior temporal lobectomy with resection of the amygdala and anterior hippocampus resulted in cessation of seizures.

CONCLUSIONS

This is a rare example of epileptic seizures of medial temporal onset presenting with isolated somato-motor manifestations and ictal crying. Anatomical-electrical-clinical correlations with cortical regions controlling facial movements were highly suggestive that this case represents secondary activation of "emotional" motor cortex M3 and M4 (rostral and caudal cingulate motor cortex), giving rise to focal hemifacial movements and ictal crying.

What is the optimal age for repair of tetralogy of Fallot?

BACKGROUND

Controversy regarding the timing for the repair of tetralogy of Fallot centers around initial palliation versus primary repair for the symptomatic neonate/young infant and the optimal age for repair of the asymptomatic child. We changed our approach from one of initial palliation in the infant to one of primary repair around the age of 6 months, or earlier if clinically indicated. We examined the effects of this change in protocol and age on outcomes.

METHODS AND RESULTS

The records of 227 consecutive children who had repair of isolated tetralogy of Fallot from January 1993 to June 1998 were reviewed. The median age of repair by year fell from 17 to 8 months (P:<0.01). The presence of a palliative shunt at the time of repair decreased from 38% to 0% (P:<0.01). Mortality (6 deaths, 2. 6%) improved with time (P:=0.02), with no mortality since the change in protocol (late 1995/early 1996). Multivariate analysis for physiological outcomes of time to lactate clearance, ventilation hours, and length of stay, but not death, demonstrated that an age <3 months was independently associated with prolongation of times (P:<0.03). Each of the deaths occurred with primary repair at an age >12 months. The best survival and physiological outcomes were achieved with primary repair in children aged 3 to 11 months.

CONCLUSIONS

On the basis of mortality and physiological outcomes, the optimal age for elective repair of tetralogy of Fallot is 3 to 11 months of age.

Amplification of 4q21-q22 and the MXR gene in independently derived mitoxantrone-resistant cell lines

Molecular cytogenetic studies were conducted on three multidrug-resistant cancer sublines which are highly resistant to the chemotherapeutic agent mitoxantrone, an anthracenedione. The three independently selected sublines were derived by exposure to mitoxantrone or Adriamycin and do not overexpress MDR1 or MRP. Two sublines, MCF-7 AdVp3000 and MCF-7 MX, showed an amplification peak at 4q21-q22, as demonstrated by comparative genomic hybridization (CGH), while the third, S1-M1-80, did not. FISH using a whole chromosome 4 paint demonstrated multiple rearrangements involving chromosome 4 in MCF-7 AdVp3000 and MCF-7 MX, while S1-M1-80 contained only a simple reciprocal translocation. The parental cell lines had no chromosome 4 rearrangements and no copy number gain or amplification of chromosome 4. Spectral karyotyping (SKY) analysis revealed a balanced translocation, t(4;17)(q21-q22;p13) in S1-M1-80 and multiple clonal translocations involving chromosome 4 in MCF-7 AdVp3000 and MCF-7 MX. A novel cDNA, designated MXR, which encodes an ABC half-transporter and is highly overexpressed in the three sublines, was localized to chromosome 4 by somatic cell hybrid analysis. Southern blot analysis demonstrated amplification of the MXR gene in MCF-7 AdVp3000 and MCF-7 MX, but not in S1-M1-80. FISH studies with a BAC probe for MXR localized the gene to 4q21-22 in the normal chromosome 4 and revealed in both MCF-7 AdVp3000 and MCF-7 MX amplification of MXR at one translocation juncture, shown by SKY to be t(4;5)(4qter-->4cen-->4q21-22::5q13-->5qter++ +) in MCF-7 AdVp3000 and t(6;4;6;3)(6pter-->6q15::4q21-q22::hsr::6q?::3q?27-->+ ++3qter) in MCF MX; neither of the breakpoints in the partner chromosomes showed amplification by CGH. The data are consistent with the hypothesis of a transporter, presumably that encoded by the MXR gene, mediating mitoxantrone resistance. The MXR gene encodes a half-transporter and the absence of cytogenetic evidence of coamplification of other regions suggests that a partner may not be overexpressed, and instead the MXR half-transporter homodimerizes to mediate drug transport. Genes Chromosomes Cancer 27:110-116, 2000. Published 2000 Wiley-Liss, Inc.

Identification of a LDL-receptor in the lymphatic filarial parasiteWuchereria bancrofti

Little is known about host-parasite inter-relationship in the lymphatic filarial parasites. There is no information available about the ability of these parasites to acquire cholesterol, though it is known that in general, nematodes lack the ability to synthesise cholesterolde novo. In this study, we have shown that the filarial parasites also lack the ability to incorporate labelled acetate into cholesterol, indicating the absence of the machinery for cholesterol biosynthesis. We have further shown that they elaborate a 43 kDa surface receptor for acquiring LDL-bound cholesterol. We have shown by polymerase chain reaction the presence of a 860 bp fragment indicating the presence of the gene for LDL-related protein (LRP) in the human filarial parasiteWuchereria bancrofti in the genomic DNA. We have also shown that it is expressed as seen in the cDNA clones identified from an expression library.

Dobutamine stress echocardiography for the detection of significant coronary artery disease in renal transplant candidates

Prophylactic coronary revascularization may reduce the risk for cardiac events in diabetic renal transplant candidates. No published data exist on the accuracy of dobutamine stress echocardiography (DSE) for the diagnosis of angiographically defined coronary artery disease (CAD) in renal transplant candidates. The purpose of this study is to examine the accuracy of DSE for the detection of CAD in high-risk renal transplant candidates compared with coronary angiography. Fifty renal transplant candidates with diabetic nephropathy (39 patients) or end-stage renal disease (ESRD) from other causes (11 patients) underwent prospectively performed DSE, followed by quantitative coronary angiography (QCA) and qualitative visual assessment of CAD severity. Twenty of 50 DSE tests were positive for inducible ischemia. Twenty-seven patients (54%) had a stenosis of 50% or greater by QCA, 12 patients (24%) had a stenosis of greater than 70% by QCA, and 16 patients (32%) had a stenosis greater than 75% by visual estimation. The sensitivity and specificity of DSE for CAD diagnosis were respectively 52% and 74% compared with QCA stenosis of 50% or greater, 75% and 71% compared with QCA stenosis greater than 70%, and 75% and 76% for stenosis greater than 75% by visual estimate. On long-term follow-up (22.5 +/- 10.1 months), 6 of 30 patients (20%) with negative DSE results and 11 of 20 patients (55%) with positive DSE results had a cardiac death, myocardial infarction (MI), or coronary revascularization. Six of 27 patients (22%) with a QCA stenosis of 50% or greater had a cardiac death or MI compared with none of the 23 patients (0%) with QCA stenosis less than 50% (P = 0.025). We conclude that DSE is a useful but imperfect screening test for angiographically defined CAD in renal transplant candidates.

Molecular determinants of the pathogenesis of disease due to non-typable Haemophilus influenzae

Non-typable Haemophilus influenzae is a common commensal organism in the human upper respiratory tract and an important cause of localized respiratory tract disease. The pathogenesis of disease begins with bacterial colonization of the nasopharynx, a process that involves establishment on the mucosal surface and evasion of local immune mechanisms. Under the proper circumstances, the organism spreads contiguously to the middle ear, the sinuses, or the lungs, and then stimulates a brisk inflammatory response, producing symptomatic infection. In this review, we summarize our present understanding of the molecular determinants of this sequence of events. Continued investigation of the molecular mechanism of non-typable H. influenzae pathogenicity should facilitate development of novel approaches to the treatment and prevention of H. influenzae disease.

Delays in the suspicion and treatment of tuberculosis among hospitalized patients

BACKGROUND

Despite increased awareness of tuberculosis, delays in management are common.

OBJECTIVE

To investigate management delays among hospitalized patients with tuberculosis.

DESIGN

Retrospective cohort study.

SETTING

The Barnes-Jewish-Christian Health System, a network of eight community and tertiary-care facilities serving the St. Louis, Missouri, metropolitan area.

PATIENTS

All 203 patients with tuberculosis hospitalized in the Barnes-Jewish-Christian Health System from 1988 to 1996.

MEASUREMENTS

Time from admission to first consideration of the diagnosis (suspicion interval), first consideration and treatment initiation (treatment interval), and admission and treatment initiation (overall management interval) were determined. Delays were defined as intervals longer than 24 hours.

RESULTS

The overall management interval (median, 6 days [5th and 95th percentiles, 1 and 52 days]) exceeded 24 hours in 152 patients (74.9% [95% CI, 68.9% to 80.9%]). The suspicion interval (median, 1 day [5th and 95th percentiles, 0 and 16 days]) exceeded 24 hours in 54 patients (26.6% [CI, 20.5% to 32.7%]), and the treatment interval (median, 3 days [5th and 95th percentiles, 0 and 51 days]) was prolonged in 130 patients (64.0% [CI, 57.4% to 70.6%]). Overall management delays of more than 10 and 25 days occurred in 33.5% (CI, 27.0% to 40.0%) and 18.7% (CI, 13.3% to 24.1%) of patients, respectively. The 55 patients with smears that were positive for acid-fast bacilli had a median treatment interval of 3 days (5th and 95th percentiles, 0 and 33 days); in 58.2% of patients (CI, 45.2% to 71.2%), this interval exceeded 24 hours.

CONCLUSIONS

Delays in initiation of treatment were more common than delays in the initial suspicion of tuberculosis. Both types of delays were common even in patients with disease that was confirmed by a positive smear. These data illustrate a need for improved education of physicians about the benefits of early initiation of therapy for tuberculosis.

The impact of comorbidity on mortality following in-hospital diagnosis of tuberculosis

STUDY OBJECTIVES

Despite the availability of curative chemotherapy, mortality remains high among patients hospitalized for tuberculosis. Although the elevated mortality rate is often attributed to the presence of multidrug resistant tuberculosis (MDRTB) or concomitant infection with the HIV, other factors must be contributory, especially among the HIV-negative population. Therefore, we performed a study to define the factors associated with mortality following the in-hospital diagnosis of tuberculosis in a region with low levels of MDRTB and coinfection with HIV.

DESIGN

Retrospective cohort study.

SETTING

The eight hospitals in the Barnes-Jewish-Christian (BJC) Health System, which is a network of community and tertiary-care level facilities serving the St. Louis, MO, metropolitan area.

PATIENTS

All 203 patients hospitalized with culture-positive tuberculosis at one of the BJC system hospitals between 1988 and 1996.

INTERVENTIONS

Follow-up information was obtained by telephone interview and review of medical and public health records. Death was verified through a search of the death certificate registry of Missouri and the records of the Social Security Administration. Mortality was defined as death from any cause during the 14 months following the initial date of hospitalization.

MEASUREMENTS AND RESULTS

The cumulative all-cause mortality rate for this cohort was 28.1%. The incidence of HIV positivity was 7.9% and of MDRTB was 1.5%. Multiple logistic regression analysis demonstrated that respiratory failure requiring mechanical ventilation (adjusted odds ratio [AOR] = 6.5; 95% confidence interval [CI] = 6.0 to 7.0; p < 0.001) and the presence of end-stage renal disease requiring dialysis (AOR = 7.0; 95% CI = 3.7 to 13.3; p = 0.002) were the largest contributors to mortality. Other variables independently associated with mortality included the presence of malnutrition (AOR = 3.2; 95% CI = 2.1 to 4.9; p = 0.007), age > 60 years (AOR = 3.5; 95% CI = 2.4 to 5.2; p < 0.001), drug-induced immunosuppression (AOR = 3.2; 95% CI = 1.6 to 5.2; p = 0.018), and dyspnea at the time of hospital presentation (AOR = 2.1; 95% CI = 1.4 to 3.1; p = 0.048). Overall, 45.3% of the patients had a > 7-day delay in the suspicion of the diagnosis of tuberculosis and the institution of antituberculosis therapy following hospital admission. There was no association between the presence of these delays and mortality.

CONCLUSIONS

Our data suggest that the 14-month mortality rate is high among patients diagnosed as having tuberculosis during hospitalization, despite low incidences of HIV infection and multidrug resistant disease. The factors that appear to contribute to this elevated mortality rate are markers of disease chronicity and severity of not only the tuberculosis, but also of the patient's underlying health status. Thus, while HIV positivity and multidrug resistance can be important determinants of mortality in some populations, other demographic factors and comorbid conditions may play a role as well. These data also suggest that tuberculosis is often superimposed on chronic illnesses that are important determinants of patient outcomes.

Utility of transbronchial biopsy in patients with acute respiratory failure: a postmortem study

STUDY OBJECTIVE

To determine the diagnostic yield of histologic specimens obtained by postmortem transbronchial biopsy (TBB) in patients with acute respiratory failure requiring mechanical ventilation.

DESIGN

Standard postmortem histologic examination of lung tissue specimens.

SETTING

An urban university-affiliated hospital.

PATIENTS OR PARTICIPANTS

Thirty patients with diffuse pulmonary infiltrates and acute respiratory failure, who underwent postmortem examination.

INTERVENTIONS

Following removal of the lungs from the thorax. TBBs were obtained from the lower lobe of each deflated lung and comparison was made to a 1-cm3 tissue block obtained from the ipsilateral lower lobe.

MEASUREMENTS AND RESULTS

Standard postmortem histologic examination provided a specific diagnosis in 85% of the 60 lungs examined, and histologic evidence of acute pneumonia was present in 30% of the lungs. The overall yield of TBB was 48% for establishing a specific histologic diagnosis and 15% for the diagnosis of acute pneumonia. Using standard postmortem histologic examination as the gold standard, the sensitivity and specificity of TBB for making a specific diagnosis were 57% and 100% respectively, with corresponding positive and negative predictive values of 100% and 29%. For the histologic diagnosis of acute pneumonia, the sensitivity of TBB was 50%, the specificity was 100%, and the positive and negative predictive values were 100% and 82%, respectively. The kappa statistic for the agreement between the two diagnostic methods was 0.28 for establishing a specific diagnosis and 0.58 for the diagnosis of acute pneumonia. Obtaining 12 TBBs rather than six TBBs did not increase the diagnostic yield for TBB.

CONCLUSIONS

These findings suggest poor overall agreement between standard postmortem histologic examination and TBB specimens. Although not performed in a clinical setting, this postmortem investigation suggests that TBB may be of limited value in mechanically ventilated patients with acute respiratory failure because of its low sensitivity.

Posttransplant medical complications

A variety of medical, surgical, social, and psychiatric problems affect the renal allograft rejection, thromboembolic disease, infectious events and gastrointestinal disorders. Hypertension and hyperlipidemia appear around 3 months and may remain throughout the posttransplant period. The late complication are atherosclerotic cardiovascular disease, malignancy hepatic failure, chronic rejection, denovo and recurrent renal disease, posttransplant diabetes, musculoskeletal problems, cataracts and skin lesions. Routine follow up of all transplanted patients at specialized centers is critical for early detection and management of these complications. Such practice would reduce the patient morbidity and mortality and lead to an improved long-term outcome.

A randomized trial comparing cyclosporine induction with sequential therapy in renal transplant recipients

Calcium antagonists may reduce the nephrotoxicity of cyclosporine (CsA), allowing CsA to be introduced immediately after renal transplantation and thereby obviating the need for sequential induction therapy with a monoclonal or polyclonal antibody. To test this hypothesis, in a pilot feasibility trial 100 cadaveric or one-haplotype-mismatched living-related renal transplant recipients were randomized to either (1) sequential therapy with anti-thymocyte globulin (ATG) (ATGAM; Upjohn, Kalamazoo, MI) 20 mg/kg/d for 7 to 14 days until renal function was established and CsA (Sandimmune; Sandoz, East Hanover, NJ) was started, or (2) CsA 8 mg/kg/d begun immediately before surgery with diltiazem (Cardizem; Marion Merrell Dow, Kansas City, MO) 60 mg sustained release twice daily. Acute rejection episodes during the first 90 days were not different with ATG versus CsA induction (42% v 28%; P = 0.142 by chi-square analysis). Graft failures (10% v 16%; P = 0.372) and the incidence of delayed graft function (28% v 34%; P = 0.516) were also similar with ATG compared with CsA. ATG caused lower platelet counts (138 +/- 59 x 10(3) v 197 +/- 75 x 10(3) at 7 days; P < 0.001) and lower white blood cell counts (9.6 +/- 4.6 x 10(3) v 12.3 +/- 4.9 x 10(3) at 7 days; P = 0.003). Diltiazem reduced the dose of CsA required to maintain target blood levels (479 +/- 189 mg/d v 576 +/- 178 mg/d at 14 days; P = 0.015). There were no statistically significant differences between the groups in serum creatinine levels at days 1, 3, 5, 7, 14, 28, 60, or 90. The results of this pilot feasibility trial suggest that prophylactic treatment with CsA and diltiazem may be equally effective and less toxic than ATG induction after renal transplantation.

Improved preservation of rat hindlimbs with the University of Wisconsin solution and butanedione monoxime

The purpose of this study was to compare the effects of the University of Wisconsin solution plus butanedione monoxime, the University of Wisconsin solution without butanedione monoxime, and saline on the preservation of muscle tissue. Forty-nine rat hindlimbs were amputated and replanted. The study population was subdivided into four groups according to flushing solution, storage, and replantation protocols. The limbs of the control group (n = 12) were flushed with 20 ml University of Wisconsin solution and immediately replanted onto the same rat. In the remaining three groups, the limbs were immersed in solution, stored in a refrigerator at 4 degrees C for 24 hours, and then replanted onto a fresh rat. The limbs in the no flushout group (n = 7) were placed into storage in cold saline solution without being flushed. The limbs in the University of Wisconsin solution group (n = 17) were flushed with 20 ml of University of Wisconsin solution prior to storage, and those in the University of Wisconsin solution plus butanedione monoxime group (n = 13) were flushed with 20 ml University of Wisconsin solution plus 20 mM butanedione monoxime. Limb survival rate was 100 percent for the control and University of Wisconsin solution plus butanedione monoxime groups, 87 percent for the University of Wisconsin solution group, and 71 percent for the no flushout group. Seven days after replantation, ATP levels were 71 percent of control in the University of Wisconsin solution plus butanedione monoxime group, 33 percent in the University of Wisconsin solution group, and 29 percent in the no flushout group. Tissue K+/Na+ ratio showed that the University of Wisconsin solution plus butanedione monoxime group maintained electrolyte balance, whereas the balance was significantly lowered in University of Wisconsin solution and no flushout groups. The University of Wisconsin solution plus butanedione monoxime limbs did not exhibit cell swelling, whereas total tissue water values for the University of Wisconsin solution and no flushout groups increased significantly. Serum creatinine kinase, measured 24 hours after replantation, was 120 percent of control in the University of Wisconsin solution plus butanedione monoxime group, 550 percent in the University of Wisconsin solution group, and 772 percent in the no flushout group. Limbs in the University of Wisconsin solution plus butanedione monoxime group had more flexible ankle joints and pliable muscle (i.e., less contracture) than those in the University of Wisconsin solution and no flushout groups. In conclusion, rat hindlimbs can be preserved hypothermically for 24 hours using the University of Wisconsin solution, the University of Wisconsin solution plus butanedione monoxime, or saline. However, the University of Wisconsin solution plus butanedione monoxime limbs had better ATP levels and less cellular injury after replantation. Based on these results, we believe that, biochemically, flushing and storage of muscle tissue in the University of Wisconsin solution plus butanedione monoxime are the most effective means of those studied for preserving composite tissue grafts for 24 hours.

Molecular executors of cell death--differential intrarenal expression of Fas ligand, Fas, granzyme B, and perforin during acute and/or chronic rejection of human renal allografts

Two distinct cytolytic pathways have been characterized: one in which the interaction between the Fas antigen and its ligand results in apoptosis, and another in which the pore forming protein perforin and the serine protease granzyme B contribute to DNA fragmentation and cell death. We investigated intrarenal expression of these molecular executors of cell death in light of the potential participation of cytolytically active cellular elements in the antiallograft repertory. Reverse transcriptase-polymerase chain reaction was used to identify intrarenal expression of Fas antigen, Fas ligand, granzyme B and perforin in eighty human renal allograft biopsies; mRNA display was correlated with the Banff histological diagnosis of renal allografts. Our studies demonstrate that: (1) intrarenal expression of Fas ligand mRNA and of granzyme B mRNA are correlates of acute but not chronic rejection; (2) Fas ligand mRNA is not detectable in allografts in the absence of rejection; (3) intrarenal coexpression of members of each lytic pathway (Fas ligand and Fas, granzyme B, and perforin) and that of both pathways (e.g., Fas ligand and granzyme B) are correlates of acute rejection; and (4) a direct correlation exists between the histological severity of acute rejection and intrarenal coexpression of mRNA encoding Fas ligand, Fas, granzyme B, and perforin. Our studies identify, for the first time, the differential expression of the two major lytic pathways in acute and chronic allograft rejection and suggest that specific therapy directed at the cytotoxic attack molecules might be efficacious in the prevention and/or treatment of acute rejection.

Absence of wild poliovirus circulation among healthy children in a rural area with high oral poliovirus vaccination coverage

Poliovirus circulation in a rural community was studied by a stool sample survey. No acute paralytic poliomyelitis case had been reported from the study area during the previous 5 months. Immunization coverage in age groups 7 to 12 months and 12 to 60 months was 95.8 and 94 per cent, respectively. Of the 257 children from whom stool samples were collected (about 6% of the child population), 161 (62.6%) were positive for virus isolation. Poliovirus was isolated from 60 (23.3%) children. All three poliovirus types were detected (41 type 1, 16 type 2 and 3 type 3). Intratypic differentiation tests classified these isolates as vaccine-like. Among the children excreting poliovirus, the proportion of those who did not receive polio vaccine within 30 days prior to the sample collection was 46.3, and 68.7 per cent for poliovirus type 1 and 2, respectively. It was concluded that these poliovirus excreting children were infected by the vaccine strains circulating in the environment. The survey showed that wild poliovirus was not detectable within five months after the last case of acute poliomyelitis. Displacement of the wild virus from the environment and circulation of vaccine virus was achieved by high vaccination coverage in this area.

Pancreas transplantation for diabetes mellitus

Pancreas transplantation has become a viable option for the patient wi th insulin-dependent diabetes mellitus with progressive renal failure. The most common type of pancreas transplantation is a simultaneous pancreas and kidney transplantation performed from a single cadaver donor (SPK). The next most common is pancreas transplantation after successful kidney transplantation (PAK). A few centers are performing pancreas transplantation alone (PTA) in diabetic recipients without renal disease but who have significant complications from their diabetes. Pancreas transplantation is associated with a higher morbidity than kidney transplantation alone. Most pancreas transplantation centers report a significant increase in acute rejection, which can lead to increased hospitalization and risk of opportunistic infection. In addition, the early era of pancreas transplantation was associated with significant surgical complications. However, with bladder drainage of the pancreas exocrine secretions, the surgical complication rate has decreased significantly. Despite medical and surgical complications, the overall results for pancreas transplantation are excellent, with 1 -year graft survival of 75% for SPK transplantations and 48% for PAK and PTA transplant recipients. The effects of a pancreas transplantation on the secondary complications of diabetes have been studied extensively. Most studies have shown a modest improvement in secondary complications with the exception of diabetic retinopathy. The major benefit of pancreas transplantation appears to be enhanced quality of life for patients successfully transplanted. For these reasons, the Kidney-Pancreas Committee of the American Society of Transplant Physicians believes the current results of pancreas-kidney transplantation justify its use as a valid option for insulin-dependent diabetic transplant recipients.

An evaluation of cold chain in Maharashtra & Karnataka states by potency testing of field samples of oral poliovirus vaccine

The cold chain for oral poliovirus vaccine was monitored in Maharashtra and Karnataka by potency testing of vaccine vials collected from various stages of the delivery system. Results showed that cold chain maintenance improved in the state of Maharashtra within a period of three years as the monitoring began in 1987. Of the 6289 samples of trivalent OPV collected from all 30 districts of the state during 1990 to 1992, 5834 (92.8%) had retained virus titre of at least 10(5.81) TCID50/dose. In comparison, 72 per cent of the 1660 samples collected from the state of Karnataka during the same period were found to contain this minimum required virus titre. Defects in cold chain maintenance in Karnataka could be demonstrated by plotting virus titre of samples of individual batches collected from different outlets. It was concluded that potency retesting of OPV samples for cold chain monitoring will ensure proper storage, transport and use of potent vaccine in the field.

Prevalence of antibodies to polioviruses & enteroviruses excreted by healthy children in Bombay

A total of 132 healthy children between the ages one month and 12 yr were surveyed to determine the prevalence of antibodies to the three poliovirus serotypes. Among infants up to six months of age, 73.2, 85.4 and 56.1 per cent had antibodies to poliovirus types 1, 2 and 3, respectively. In children of age groups 7 months to 3 yr and above 3 yr, antibody prevalence to the three poliovirus serotypes was 90.2, 86.9 and 57.4, and 83.3, 96.7 and 76.7 per cent, respectively. Immunization coverage with three doses of OPV exceeded 85 per cent in children above 7 months of age. Low seroprevalence to type 3 poliovirus in the children was conspicuous. Of the 80 faecal samples studied from these children, 24 (30%) were positive for virus. Among these isolates, 16 were poliovirus type 1 and three type 2. Intratypic differentiation revealed that 15 of the 16 poliovirus type 1 isolates were of wild origin. Two out of the three poliovirus type 2 isolates were of oral poliovaccine origin. Our data indicate that in spite of good vaccination coverage wild poliovirus type 1 circulation was endemic in Bombay and; that a large number of children were susceptible to poliovirus type 3 infections.

Biomechanical analysis of dorsal plate fixation in proximal phalangeal fractures

The biomechanical properties of three minifragment plate and screw systems were compared to determine whether plate systems primarily designed for maxillofacial reconstruction are biomechanically sound for use in proximal phalangeal fracture fixation. A middiaphyseal transverse osteotomy was created in each of 30 fresh-frozen human proximal phalanges to simulate an unstable fracture. Each osteotomy was then fixed with four 2.0ml screws through one of three different four-hole minifragment plates in a middorsal position. Plating systems tested included a vitallium plate with self-tapping screws (Luhr), a stainless steel plate with tapped screws (Synthes), and a titanium plate with tapped screws (Synthes). Testing was performed to failure in an apex volar three-point bending mode. The titanium-plated phalanges were the stiffest construct and required the greatest load and total energy absorbed to failure. However, only the load to failure for titanium versus stainless steel was significantly different. Therefore, there is no biomechanical disadvantage to using the titanium or vitallium plate and screw systems in the setting of unstable proximal phalangeal fractures.

Microvascular reconstruction of the upper extremity with the rectus abdominis muscle

Large soft-tissue defects of the upper extremity are difficult to reconstruct. Defects in 21 patients (15-75 years old) were treated by free tissue transfer of the rectus abdominis muscle. The defects were the result of trauma or resection of tumor and measured more than 15 x 15 cm. The muscle was transferred on the inferior epigastric pedicle and covered with a skin graft within 48 hours. All transfers were successful, and early soft-tissue healing occurred. This procedure offers the advantages of easy positioning, large donor vessels, and a highly vascular soft tissue reconstruction. The long-term functional and cosmetic results have been excellent.

Development of a genetic system for Eikenella corrodens: transfer of plasmids pFM739 and pLES2

Eikenella corrodens is a Gram-negative microaerophilic rod which is emerging as an important human pathogen. Elucidation of the mechanisms by which it causes disease require efficient methods for the transfer of DNA to E. corrodens. Plasmids pFM739 and pLES2 have been transferred by conjugation from Escherichia coli S17-1 to E. corrodens ATCC 23834 at frequencies of 2.5 x 10(-7) and 2.42 x 10(-7), respectively. In addition, both plasmids could be transferred to four additional, clinical strains of E. corrodens at a similar frequency. The use of bacteriophage T4 as a counterselecting agent is also described.

Preoperative evaluation of giant cell tumors of the radius with magnetic resonance angiography

We report three clinical cases of giant cell tumor of the distal radius in which reconstructions were performed with vascularized fibular grafts. Magnetic resonance angiography, a newer and noninvasive technique, was used in addition to preoperative magnetic resonance imaging. All patients had routine digital subtraction arteriography, with which magnetic resonance angiography compared favorably, demonstrating the carpal arch anatomy and other major vessels at the tumor site. In two patients the trifurcation vessels of both legs were also studied with magnetic resonance angiography before fibular harvest. In one case, the fibula graft was successfully harvested on the basis of the magnetic resonance angiographic findings. In the other case, digital subtraction arteriography had been done to evaluate suspected peripheral vascular disease. In that case magnetic resonance angiography correlated well with the digital subtraction arteriographic study, showing bilateral anterior tibial artery occlusions and patent posterior tibial and peroneal arteries. Magnetic resonance angiography has the potential to replace conventional angiography in preoperative evaluation of upper-extremity tumors.

Cloning, characterization and sequencing of two haemagglutinin genes from Eikenella corrodens

Eikenella corrodens is emerging as an important human pathogen, in both extra-oral and periodontal infections. From a clone bank of Eikenella corrodens chromosomal DNA produced in Escherichia coli JM109, twenty-two clones expressed Eikenella antigens and of these, two expressed functional haemagglutinins. By virtue of different restriction maps and a lack of homology by Southern hybridization, the two cloned fragments encoding the two haemagglutinins have been shown to be distinct. Maxicell analysis revealed that clone 1, carrying plasmid pVKR201, produces three Eikenella proteins, one of 31.5 kDa and two of approximately 14 kDa each. Expression of each of the proteins appears to be under the control of an Eikenella promoter(s). Clone 2, carrying plasmid pVKR301, produces two proteins, one of 93 kDa and the second of 17 kDa. Expression of both of these proteins in E. coli requires the lac promoter in the vector. By preparing a series of subclones and testing each by maxicell analysis and for haemagglutination activity, a functional map of the insert of clone 1 was deduced and the 31.5 kDa polypeptide identified as the haemagglutinin. Using similar methods, the 17 kDa protein was found to be the haemagglutinin of clone 2. The nucleotide sequences of both haemagglutinin genes were determined and are presented. Computer analysis revealed no homology between the two haemagglutinins, and no homology to any previously sequenced proteins. These are the first genes of this genus to be cloned and sequenced.

Cloning and sequencing of two type 4 (N-methylphenylalanine) pilin genes from Eikenella corrodens

Eikenella corrodens is a Gram-negative microaerophilic rod which is gaining recognition as an important human pathogen. We have previously reported the cloning and expression in Escherichia coli of a 3.6 kb Eik. corrodens genomic DNA fragment which encodes a 31.5 kDa haemagglutinin. Maxicell analysis revealed that this fragment also encodes two proteins of approximately 14 kDa. Nucleotide sequencing of the 2.2 kb fragment upstream of the haemagglutinin gene revealed two open reading frames with strong homology to genes encoding pilin subunit proteins of the type 4 or N-methylphenylalanine class. The two pilin genes, ecpA and ecpB, are complete and are expressed in E. coli. Southern analysis of ten additional Eik. corrodens strains revealed that all possess fragments homologous to ecpA. These data represent the first molecular evidence for pili in E. corrodens.

Immunotherapy for metastatic renal cell cancer: effect on the primary tumor

The traditional approach to immunotherapy for metastatic renal cell cancer, to first reduce the tumor burden by nephrectomy and then offer systemic therapy, has been challenged recently. There is mounting evidence that objective responses in the metastatic disease can be achieved without prior nephrectomy, although responses in the primary tumor are much less frequent. We describe our experience that some patients may, in fact, have significant responses in extensive local disease and become surgical candidates after systemic immunotherapy. A 46-year-old patient who presented with a large renal primary tumor and pulmonary metastases was treated with high-dose interleukin 2 therapy. A complete response in the lung and partial response in the primary tumor was achieved. The patient then underwent resection of his primary tumor, and on histological evaluation only minimal residual cancer was present. He has no evidence of disease at 14 months. This case demonstrates that immunotherapy can achieve not only objective responses at metastatic sites but also in the primary tumor.

Alteration of reactivity of native arteries induced by venous graft placement

Occlusion of aortocoronary venous grafts can be due to thrombosis, atherosclerosis, or vasospasm. Investigations have focused on properties of the graft itself, and little is known about the vascular reactivity and function of the native arteries proximal and distal to the vein graft, although spasm of the native artery distal to the graft site has been observed in patients. We hypothesized that the function of the endothelium of the native arteries may be altered after surgery. Autogenous venous grafts were placed in femoral arteries of rabbits to study the reactivity of the native arteries after grafting. Four weeks after graft implantation, the vein graft, ipsilateral vein, and native artery proximal and distal to the graft were removed for in vitro studies. Morphological evaluation by scanning electron microscopy and fluorescence microscopy after labeling with acetylated low density lipoprotein labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate indicated the presence of an intact, metabolically active endothelial layer. There was no alteration in the contractile responses to phenylephrine of the arteries, vein grafts, or veins. Precontracted vein grafts, veins, and arterial segments proximal to the grafts relaxed when exposed to endothelium-dependent vasodilators (acetylcholine, arachidonic acid, and substance P), but the native arteries distal to the grafts did not. In bioassay cascade experiments, the distal artery did not release any measurable relaxing factor when exposed to acetylcholine. We conclude that the endothelium of the distal artery did not function normally. The extent and reversibility of altered endothelial function remain to be determined. This observation may help to explain the occurrence of myocardial infarction after aortocoronary bypass grafting in some patients.

High-pressure injection injuries of the hand

High pressure injection trauma to the upper extremity is a rare but potentially limb-threatening injury. The index finger on the non-dominant hand of young male workers is most commonly involved. Injected materials include paint, grease and diesel oil. Prompt recognition and initiation of treatment is necessary if a disastrous outcome is to be avoided. Primary treatment consists of surgical decompression and debridement. Amputation may be necessary. With early aggressive treatment, satisfactory results can be obtained. The use of high-pressure devices in industry has resulted in an unusual but potentially limb-threatening injury to the upper extremity known as the "high-pressure injection injury." This injury is a surgical emergency that demands prompt diagnosis and treatment if a disastrous outcome is to be avoided. The purpose of this paper is to present our recent experience and review the clinical features, evaluation and treatment principles.