The Pediatric Toronto Extremity Salvage Score (pTESS): Validation of a Self-reported Functional Outcomes Tool for Children with Extremity Tumors

BACKGROUND

The physical function of children with sarcoma after surgery has not been studied explicitly. This paucity of research is partly because of the lack of a sufficiently sensitive pediatric functional measure. The goal of this study was to establish and validate a standardized measure of physical function in pediatric patients with extremity tumors.

QUESTIONS/PURPOSES

(1) What is the best format and content for new upper- and lower-extremity measures of physical function in the pediatric population? (2) Do the new measures exhibit floor and/or ceiling effects, internal consistency, and test-retest reliability? (3) Are the new measures valid?

METHODS

In Phase 1, interviews with 17 consecutive children and adolescents with bone tumors were conducted to modify the format and content of draft versions of the pediatric Toronto Extremity Salvage Score (pTESS). In Phase 2, the pTESS was formally translated into French. In Phase 3, 122 participants between 7 and 17.9 years old with malignant or benign-aggressive bone tumors completed the limb-specific measure on two occasions. Older adolescents also completed the adult TESS. Floor and ceiling effects, internal consistency, test-retest reliability, and validity were evaluated.

RESULTS

Feedback from interviews resulted in the removal, addition, and modification of draft items, and the pTESS-Leg and pTESS-Arm questionnaires were finalized. Both versions exhibited no floor or ceiling effects and high internal consistency (α > 0.92). The test-retest reliability was excellent for the pTESS-Leg (intraclass correlation coefficient [ICC] = 0.94; 95% CI, 0.90-0.97) and good for the pTESS-Arm (ICC = 0.86; 95% CI, 0.61-0.96). Known-group validity (ability to discriminate between groups) was demonstrated by lower mean pTESS-Leg scores for participants using gait aids or braces (mean = 68; SD = 21) than for those who did not (mean = 87; SD = 11; p < 0.001). There was no significant difference between pTESS arm scores among respondents using a brace (n = 5; mean = 73; SD = 11) and those without (n = 22; mean = 83; SD = 19; p = 0.13). To evaluate construct validity, we tested a priori hypotheses. The duration since chemotherapy correlated moderately with higher pTESS-Leg scores (r = 0.4; p < 0.001) but not with pTESS-Arm scores (r = 0.1; p = 0.80), and the duration since tumor resection correlated moderately with higher pTESS-Leg scores (r = 0.4; p < 0.001) but not pTESS-Arm scores (r = 0.2; p = 0.4). Higher VAS scores (that is, it was harder to do things) antecorrelated with both pTESS versions (pTESS-Leg: r = -0.7; p < 0.001; pTESS-Arm: r = -0.8; p < 0.001). To assess criterion validity, we compared the pTESS with the current "gold standard" (adult TESS). Among adolescents, strong correlations were observed between the TESS and pTESS-Leg (r = 0.97, p < 0.001) and pTESS-Arm (r = 0.9, p = 0.007).

CONCLUSIONS

Both pTESS versions exhibited no floor or ceiling effects and had high internal consistency. The pTESS-Leg demonstrated excellent reliability and validity, and the pTESS-Arm demonstrated good reliability and reasonable validity. The pTESS is recommended for cross-sectional evaluation of self-reported physical function in pediatric patients with bone tumors.

LEVEL OF EVIDENCE

Level II, outcome measurement development.

Randomized clinical trial of laparoscopic ultrasonography before laparoscopic colorectal cancer resection

BACKGROUND

Intraoperative ultrasonography during open surgery for colorectal cancer may be useful for the detection of unrecognized liver metastases. Laparoscopic ultrasonography (LUS) for the detection of unrecognized liver metastasis has not been studied in a randomized trial. This RCT tested the hypothesis that LUS would change the TNM stage and treatment strategy.

METHODS

Patients with colorectal cancer and no known metastases were randomized (1 : 1) to laparoscopic examination (control or laparoscopy plus LUS) in three Danish centres. Neither participants nor staff were blinded to the group assignment.

RESULTS

Three hundred patients were randomized, 150 in each group. After randomization, 43 patients were excluded, leaving 128 in the control group and 129 in the LUS group. Intraoperative T and N categories were not altered by LUS, but laparoscopy alone identified previously undetected M1 disease in one patient (0·8 per cent) in the control group and three (2·3 per cent) in the LUS group. In the latter group, LUS suggested that an additional six patients (4·7 per cent) had M1 disease with liver (4) or para-aortal lymph node (2) metastases. The change in treatment strategy was greater in the LUS than in the control group (7·8 (95 per cent c.i. 3·8 to 13·8) and 0·8 (0 to 4·2) per cent respectively; P = 0·010), but the suspected M1 disease was benign in half of the patients.

CONCLUSION

Routine LUS during resection of colorectal cancer is not recommended. Registration number: NCT02079389 (http://www.clinicaltrials.gov).

Early Biomarkers from Conventional and Delayed-Contrast MRI to Predict the Response to Bevacizumab in Recurrent High-Grade Gliomas

BACKGROUND AND PURPOSE

The interpretation of the radiologic response of bevacizumab-treated patients with recurrent high-grade gliomas represents a unique challenge. Delayed-contrast MR imaging was recently introduced for calculating treatment-response-assessment maps in patients with brain tumors, providing clear separation between active tumor and treatment effects. We studied the application of standard and delayed-contrast MR imaging for assessing and predicting the response to bevacizumab.

MATERIALS AND METHODS

Twenty-four patients with recurrent high-grade gliomas were scanned before and during bevacizumab treatment by standard and delayed-contrast MR imaging. The mean change in lesion volumes of responders (overall survival, ≥1 year) and nonresponders (overall survival, <1 year) was studied. The lesion volumes at baseline and the changes in lesion volumes 1 month after treatment initiation, calculated from standard and delayed-contrast MRIs, were studied as possible predictors of outcome. In scans acquired at progression, the average change in lesion volume from previous follow-up in standard and delayed-contrast MRIs was compared.

RESULTS

Response and progression patterns were identified from the mean change in lesion volumes, depicted from conventional T1WI, delayed contrast-enhanced MR imaging, and DSC MR imaging. Thresholds for early prediction of response were calculated by using these sequences. For each predictor, sensitivity, specificity, positive predictive values, and negative predictive values were calculated, reaching 85.7%, 87.5%, 75%, and 93.3% for conventional T1WI; 100%, 87.5%, 77.8%, and 100% for delayed-contrast MR imaging; and 75%, 78.6%, 50%, and 91.7% for DSC MR imaging. The benefit of delayed-contrast MR imaging in separating responders and nonresponders was further confirmed by using log-rank tests (conventional T1WI, P = .0022; delayed-contrast MR imaging, P < .0001; DSC MR imaging, P = .0232) and receiver operating characteristic analyses. At progression, the increase in lesion volumes in delayed-contrast MR imaging was 37.5% higher than the increase in conventional T1WI (P < .01); these findings suggest that progression may be depicted more effectively in treatment-response-assessment maps.

CONCLUSIONS

The benefit of contrast-enhanced MR imaging for assessing and predicting the response to bevacizumab was demonstrated. The increased sensitivity of the treatment-response-assessment maps reflects their potential contribution to the management of bevacizumab-treated patients with recurrent high-grade glioma.

The 3' addition of CCA to mitochondrial tRNASer(AGY) is specifically impaired in patients with mutations in the tRNA nucleotidyl transferase TRNT1

Addition of the trinucleotide cytosine/cytosine/adenine (CCA) to the 3' end of transfer RNAs (tRNAs) is essential for translation and is catalyzed by the enzyme TRNT1 (tRNA nucleotidyl transferase), which functions in both the cytoplasm and mitochondria. Exome sequencing revealed TRNT1 mutations in two unrelated subjects with different clinical features. The first presented with acute lactic acidosis at 3 weeks of age and developed severe developmental delay, hypotonia, microcephaly, seizures, progressive cortical atrophy, neurosensorial deafness, sideroblastic anemia and renal Fanconi syndrome, dying at 21 months. The second presented at 3.5 years with gait ataxia, dysarthria, gross motor regression, hypotonia, ptosis and ophthalmoplegia and had abnormal signals in brainstem and dentate nucleus. In subject 1, muscle biopsy showed combined oxidative phosphorylation (OXPHOS) defects, but there was no OXPHOS deficiency in fibroblasts from either subject, despite a 10-fold-reduction in TRNT1 protein levels in fibroblasts of the first subject. Furthermore, in normal controls, TRNT1 protein levels are 10-fold lower in muscle than in fibroblasts. High resolution northern blots of subject fibroblast RNA suggested incomplete CCA addition to the non-canonical mitochondrial tRNA(Ser(AGY)), but no obvious qualitative differences in other mitochondrial or cytoplasmic tRNAs. Complete knockdown of TRNT1 in patient fibroblasts rendered mitochondrial tRNA(Ser(AGY)) undetectable, and markedly reduced mitochondrial translation, except polypeptides lacking Ser(AGY) codons. These data suggest that the clinical phenotypes associated with TRNT1 mutations are largely due to impaired mitochondrial translation, resulting from defective CCA addition to mitochondrial tRNA(Ser(AGY)), and that the severity of this biochemical phenotype determines the severity and tissue distribution of clinical features.

[Post-surgical septic arthritis of the pubic symphysis]

The post-surgical septic arthritis of the pubic symphysis is a rare infection, often unrecognized because sometimes it is difficult to diagnose. It should be suspected in the presence of pelvic pain with fever and sometimes lameness or painful radiation to the lower limbs but the symptoms can be misleading. We report 3 cases of post surgical septic arthritis of the pubic symphysis to illustrate it. Differential diagnoses are numerous and additional tests not always specific. Computed tomography (CT) and magnetic resonance imaging (MRI) examinations are essential to substantiate the diagnosis or to guide sampling. The appropriate antibiotic treatment against the identified germ, which is extended at least six weeks, will most often, when started early, allow the healing though pain can persist for several months.

GaN wire-based Langmuir-Blodgett films for self-powered flexible strain sensors

We report a highly flexible strain sensor which exploits the piezoelectric properties of ultra-long gallium nitride (GaN) wires. Langmuir-Blodgett assembled wires are encapsulated in a dielectric material (parylene-C), which is sandwiched between two planar electrodes in a capacitor-like configuration. Through FEM simulations we show that encapsulating densely aligned conical wires in a properly designed dielectric layer can maximize the amplitude of the generated piezoelectric output potential. According to these considerations we designed and fabricated macroscopic flexible strain sensors (active area: 1.5 cm(2)). The sensor was actuated in three point configuration inducing curvature radii of less than 10 cm and has a typical force sensitivity of 30 mV N(-1).

Arrays of nanoelectromechanical biosensors functionalized by microcontact printing

The biofunctionalization of nanoelectromechanical systems (NEMS) is critical for the development of new classes of biosensors displaying improved performance and higher levels of integration. In this paper we propose a modified microcontact process (μCP) in order to biofunctionalize arrays of NEMS with a probe molecule on the active sensing areas together with an anti-fouling layer on the passive areas in a single, self-aligned step. We demonstrate the adequate functionalization/anti-fouling of arrays of freestanding nanocantilevers as dense as 10(5) nanostructures cm(-2) by using both fluorescence microscopy and dynamic measurements of the structures' resonant frequency. The proper bioactivity of an antibody deposited onto the cantilevers and the blocking property of a bovine serum albumin layer are both assessed by incubating specific and non-specific tagged secondary antibodies followed by fluorescence imaging. Furthermore, measurement of the resonant frequency of the nanocantilevers before and after functionalization and biological recognition demonstrate that using μCP for device functionalization does not damage the nanostructures and preserves the mechanical sensing capability of our NEMS.

Modular dispensability of dysferlin C2 domains reveals rational design for mini-dysferlin molecules

Dysferlin is a large transmembrane protein composed of a C-terminal transmembrane domain, two DysF domains, and seven C2 domains that mediate lipid- and protein-binding interactions. Recessive loss-of-function mutations in dysferlin lead to muscular dystrophies, for which no treatment is currently available. The large size of dysferlin precludes its encapsulation into an adeno-associated virus (AAV), the vector of choice for gene delivery to muscle. To design mini-dysferlin molecules suitable for AAV-mediated gene transfer, we tested internally truncated dysferlin constructs, each lacking one of the seven C2 domains, for their ability to localize to the plasma membrane and to repair laser-induced plasmalemmal wounds in dysferlin-deficient human myoblasts. We demonstrate that the dysferlin C2B, C2C, C2D, and C2E domains are dispensable for correct plasmalemmal localization. Furthermore, we show that the C2B, C2C, and C2E domains and, to a lesser extent, the C2D domain are dispensable for dysferlin membrane repair function. On the basis of these results, we designed small dysferlin molecules that can localize to the plasma membrane and reseal laser-induced plasmalemmal injuries and that are small enough to be incorporated into AAV. These results lay the groundwork for AAV-mediated gene therapy experiments in dysferlin-deficient mouse models.

Corticosterone mediates some but not other behavioural changes induced by prenatal stress in rats

The effect of daily varied stress from days 13-21 of gestation in Wistar rats was investigated by tests of learning and memory and anxiogenic behaviour in the 60-day-old offspring of both sexes. Prenatal stress decreased the anogenital distance in males at 1 day of age. Anxiogenic behaviour in the elevated plus maze was seen in prenatally-stressed rats of both genders. There was no significant gender difference in the rate of spatial learning in the Morris water maze but prenatal stress only slowed that of males. In the object recognition test with an inter-trial interval of 40 min, females but not males, discriminated between a familiar and novel object. Prenatal stress did not affect object discrimination in females but feminised that in males. Maternal adrenalectomy with replacement of basal corticosterone levels in the drinking fluid prevented all of the above effects of prenatal stress in the offspring. To mimic the peak corticosterone levels and time course of elevation in response to stress, corticosterone (3 mg/kg) was injected twice (0 and 30 min) on days 13-16 and once on days 17-20 of gestation to adrenalectomised mothers. This treatment re-instated anxiogenic behaviour similar to that induced by prenatal stress, indicating that it is mediated by exposure of the foetal brain to raised levels of corticosterone. However, steroid administration to adrenalectomised dams did not decrease anogenital distance, feminise object recognition memory or slow spatial learning in their male offspring. The findings indicate that other adrenal hormones are necessary to induce these effects of prenatal stress.

Association between the oxytocin receptor (OXTR) gene and autism: relationship to Vineland Adaptive Behavior Scales and cognition

Evidence both from animal and human studies suggests that common polymorphisms in the oxytocin receptor (OXTR) gene are likely candidates to confer risk for autism spectrum disorders (ASD). In lower mammals, oxytocin is important in a wide range of social behaviors, and recent human studies have shown that administration of oxytocin modulates behavior in both clinical and non-clinical groups. Additionally, two linkage studies and two recent association investigations also underscore a possible role for the OXTR gene in predisposing to ASD. We undertook a comprehensive study of all 18 tagged SNPs across the entire OXTR gene region identified using HapMap data and the Haploview algorithm. Altogether 152 subjects diagnosed with ASDs (that is, DSM IV autistic disorder or pervasive developmental disorder--NOS) from 133 families were genotyped (parents and affected siblings). Both individual SNPs and haplotypes were tested for association using family-based association tests as provided in the UNPHASED set of programs. Significant association with single SNPs and haplotypes (global P-values <0.05, following permutation test adjustment) were observed with ASD. Association was also observed with IQ and the Vineland Adaptive Behavior Scales (VABS). In particular, a five-locus haplotype block (rs237897-rs13316193-rs237889-rs2254298-rs2268494) was significantly associated with ASD (nominal global P=0.000019; adjusted global P=0.009) and a single haplotype (carried by 7% of the population) within that block showed highly significant association (P=0.00005). This is the third association study, in a third ethnic group, showing that SNPs and haplotypes in the OXTR gene confer risk for ASD. The current investigation also shows association with IQ and total VABS scores (as well as the communication, daily living skills and socialization subdomains), suggesting that this gene shapes both cognition and daily living skills that may cross diagnostic boundaries.

Association between the arginine vasopressin 1a receptor (AVPR1a) gene and autism in a family-based study: mediation by socialization skills

We examined three microsatellites in the arginine vasopressin 1a receptor gene (AVPR1a), two in the promoter region (RS1 and RS3) and an intronic microsatellite (AVR), for association with autism as well as scores on the Vineland Adaptive Behavior Scale (VABS), the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Scale-Generic (ADOS-G), measures that are widely used to diagnose autism spectrum disorders. We tested for association between the AVPR1a microsatellites and autism in 116 families (128 probands diagnosed with the ADI-R and ADOS-G using a family-based association test (UNPHASED)). Testing each individual microsatellite showed significant transmission disequilibrium in these families with the AVR intronic microsatellite (UNPHASED: LRS=11.46, global P-value=0.009, df=3). Haplotype analysis of three microsatellites also showed significant association (LRS=144.94, df=103, global P=0.004). Additionally, significant association is observed between these three microsatellite haplotypes and the VABS scores (P=0.009), with the ADI-R (P=0.009) and the ADOS-G (P=0.0000765) diagnoses of autistic disorder versus pervasive developmental disorder-not otherwise specified (PDD-NOS) that were available for 47 of these probands. This is the third consecutive report of an association between the AVPR1a gene and autism spectrum disorders and in the current study a third microsatellite is shown to be associated with autism spectrum disorders as well as haplotypes consisting of all three markers. Importantly, the association appears to be mainly mediated by the role of the AVPR1a gene in shaping socialization skills, similar to its role in lower vertebrates.Molecular Psychiatry (2006) 11, 488-494. doi:10.1038/sj.mp.4001812; published online 7 March 2006.

A comprehensive view on organ-specific callose synthesis in wheat (Triticum aestivum L.): glucan synthase-like gene expression, callose synthase activity, callose quantification and deposition

Callose ((1,3)-beta-glucan) is important during basic developmental processes of plants, but only little is known about the regulation of callose biosynthesis on molecular level. Growing evidence indicates that glucan synthase-like (GSL) genes in higher plants are involved in callose synthesis. We analyzed the expression of eight GSL genes (TaGSL) as well as callose synthase activity and total callose content in the stem, leaf blade and spike of wheat (Triticum aestivum L.). Organ-specific expression of six TaGSL genes and strong differences in expression levels were detected by quantitative real-time PCR. Differences were also determined in callose synthase (EC 2.4.1.34) activity and total amount of callose in the examined organs. Aniline blue staining in tissue sections localized callose depositions. These results allow a comprehensive reflection of callose regulation, considering gene expression, enzyme activity and enzyme product quantification as well as localization. Our data suggests that callose synthesis is highly regulated by a combination of GSL genes, which are involved either in general or in organ-specific developmental processes.

Redox-dependent MAP kinase signaling by Ang II in vascular smooth muscle cells: role of receptor tyrosine kinase transactivation

We investigated the role of receptor tyrosine kinases in Ang II-stimulated generation of reactive oxygen species (ROS) and assessed whether MAP kinase signaling by Ang II is mediated via redox-sensitive pathways. Production of ROS and activation of NADPH oxidase were determined by DCFDA (dichlorodihydrofluorescein diacetate; 2 micromol/L) fluorescence and lucigenin (5 micromol/L) chemiluminescence, respectively, in rat vascular smooth muscle cells (VSMC). Phosphorylation of ERK1/2, p38MAP kinase and ERK5 was determined by immunoblotting. The role of insulin-like growth factor-1 receptor (IGF-1R) and epidermal growth factor receptor (EGFR) was assessed with the antagonists AG1024 and AG1478, respectively. ROS bioavailability was manipulated with Tiron (10(-5) mol/L), an intracellular scavenger, and diphenylene iodinium (DPI; 10(-6) mol/L), an NADPH oxidase inhibitor. Ang II stimulated NADPH oxidase activity and dose-dependently increased ROS production (p < 0.05). These actions were reduced by AG1024 and AG1478. Ang II-induced ERK1/2 phosphorylation (276% of control) was decreased by AG1478 and AG1024. Neither DPI nor tiron influenced Ang II-stimulated ERK1/2 activity. Ang II increased phosphorylation of p38 MAP kinase (204% of control) and ERK5 (278% of control). These effects were reduced by AG1024 and AG1478 and almost abolished by DPI and tiron. Thus Ang II stimulates production of NADPH-inducible ROS partially through transactivation of IGF-1R and EGFR. Inhibition of receptor tyrosine kinases and reduced ROS bioavaliability attenuated Ang II-induced phosphorylation of p38 MAP kinase and ERK5, but not of ERK1/2. These findings suggest that Ang II activates p38MAP kinase and ERK5 via redox-dependent cascades that are regulated by IGF-1R and EGFR transactivation. ERK1/2 regulation by Ang II is via redox-insensitive pathways.

Increased angiotensin II-mediated Src signaling via epidermal growth factor receptor transactivation is associated with decreased C-terminal Src kinase activity in vascular smooth muscle cells from spontaneously hypertensive rats

We investigated whether upregulation of Src by Ang II leads to increased extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) and whether these processes are associated with altered activation of C-terminal Src kinase (Csk), a negative regulator of Src. Furthermore, the role of epidermal growth factor receptor (EGFR) transactivation by angiotensin II (Ang II) was determined. Ang II-mediated c-Src phosphorylation was significantly greater (approximately 4-fold, P<0.01) in SHR than in Wistar-Kyoto rats (WKY). Ang II increased Csk phosphorylation 2-to 3-fold in WKY but not in SHR. Treatment of the cells with AG1478, a selective EGFR tyrosine kinase inhibitor, decreased Ang II-mediated c-Src phosphorylation, particularly in SHR. Phosphorylation of cortactin and Pyk2/focal adhesion kinase, Src-specific substrates, was increased by Ang II >3-fold, with significantly greater responses in SHR than in WKY (P<0.05). Ang II-induced ERK1/2 activation was significantly augmented (P<0.05) and sustained in VSMCs from SHR. PP2, a selective Src inhibitor, attenuated these effects and normalized the responses in SHR. Irbesartan, a selective Ang II type 1 receptor blocker, but not PD123319, a selective Ang II type 2 receptor blocker, inhibited Ang II actions. Our results demonstrate that c-Src phosphorylation and Src-dependent ERK1/2 signaling by Ang II are increased in VSMCs from SHR. These processes are associated with blunted Ang II-induced phosphorylation of Csk. EGFR transactivation contributes to Ang II-mediated Src-dependent ERK1/2 signaling. In conclusion, altered regulation of Ang II type 1 receptor-activated c-Src by Csk may be an important upstream modulator of abnormal ERK1/2 signaling in VSMCs from SHR.

Species-specific double-strand break repair and genome evolution in plants

Even closely related eukaryotic species may differ drastically in genome size. While insertion of retroelements represents a major source of genome enlargement, the mechanism mediating species- specific deletions is fairly obscure. We analyzed the formation of deletions during double-strand break (DSB) repair in Arabidopsis thaliana and tobacco, two dicotyledonous plant species differing >20-fold in genome size. DSBs were induced by the rare cutting restriction endonuclease I-SCE:I and deletions were identified by loss of function of a negative selectable marker gene containing an I-SCE:I site. Whereas the partial use of micro-homologies in junction formation was similar in both species, in tobacco 40% of the deletions were accompanied by insertions. No insertions could be detected in Arabidopsis , where larger deletions were more frequent, indicating a putative inverse correlation between genome size and the average length of deletions. Such a correlation has been postulated before by a theoretical study on the evolution of related insect genomes and our study now identifies a possible molecular cause for the phenomenon, indicating that species-specific differences in DSB repair might indeed influence genome evolution.

Capture of genomic and T-DNA sequences during double-strand break repair in somatic plant cells

To analyze genomic changes resulting from double-strand break (DSB) repair, transgenic tobacco plants were obtained that carried in their genome a restriction site of the rare cutting endonuclease I-SceI within a negative selectable marker gene. After induction of DSB repair via Agrobacterium-mediated transient expression of I-SceI, plant cells were selected that carried a loss-of-function phenotype of the marker. Surprisingly, in addition to deletions, in a number of cases repair was associated with the insertion of unique and repetitive genomic sequences into the break. Thus, DSB repair offers a mechanism for spreading different kinds of sequences into new chromosomal positions. This may have evolutionary consequences particularly for plants, as genomic alterations occurring in meristem cells can be transferred to the next generation. Moreover, transfer DNA (T-DNA), carrying the open reading frame of I-SceI, was found in several cases to be integrated into the transgenic I-SceI site. This indicates that DSB repair also represents a pathway for the integration of T-DNA into the plant genome.

Hamster to rat kidney transplantation: technique, functional outcome and complications

Hamster to rat kidney transplantation has only recently been introduced as model of concordant xenografting. The kidney model offers unique possibilities for studying both immunological and functional aspects of xenografts as opposed to the widely used heterotopic heart model. This article provides a detailed description of surgical technique as well as data on functional outcome and complications. The renal artery with a small segment of the aorta is sutured end-to-side to the abdominal aorta of the recipient, and the renal vein is anastomosed end-to-side to the inferior vena cava. The urinary system is reconstructed by bladder-to-bladder anastomosis. Xenografts will maintain close to normal serum-creatinine levels for 2-3 days, after which they are rejected. Complications occurred in 22% of xenografts. Postrenal obstruction due to severe hematuria or ureter stenosis was the most frequent problem encountered.

Sequential, morphological, and antidonor antibody analysis in a hamster-to-rat heart transplantation model

The pathogenesis and the mechanism of accelerated graft rejection in concordant xenotransplantation are unclear. The histopathological features and kinetics neither fulfill the criteria of classic hyperacute rejection nor resemble an accelerated type of first-set allograft reaction. The aim of this study was to investigate the mechanism of concordant xenograft rejection in relation to the early morphological changes in hamster hearts transplanted to unmodified rat recipients by sequential, immunohistological analysis of grafts, regional lymph nodes, and spleens and to correlate these results to the production of antidonor antibodies, as determined by a flow cytometric assay. Histopathological features were characterized by a gradually increasing myocytolysis with fragmentation and loss of myofilaments. The first slight signs were observed a few hours after transplantation. Later, vascular changes developed, evolving into a leukocytoclastic type of vasculitis, eventually with thrombosis. No significant interstitial lymphocyte infiltration was present, but neutrophilic granulocytes and macrophages appeared. In addition, a distinct increase in B cells in spleens and lymph nodes was noted. Low levels of preformed antidonor antibodies did not increase during the first 48 h; however, significant amounts of species-, but not donor-, specific antibodies were demonstrated at the time of rejection. These data, together with the morphological observations, indicate a primarily humoral xenograft rejection in this model. Minor damage to graft myocytes a few hours after transplantation, progressing to vascular changes within 24-48 h, further suggests that preformed antidonor antibodies directed against endothelial or myocyte determinants may play an initiating role in the pathogenesis of unmodified, concordant xenograft rejection.

An approach to gas evacuation in the dental operatory

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