The empty pelvis syndrome: a core data set from the PelvEx collaborative

BACKGROUND

Empty pelvis syndrome (EPS) is a significant source of morbidity following pelvic exenteration (PE), but is undefined. EPS outcome reporting and descriptors of radicality of PE are inconsistent; therefore, the best approaches for prevention are unknown. To facilitate future research into EPS, the aim of this study is to define a measurable core outcome set, core descriptor set and written definition for EPS. Consensus on strategies to mitigate EPS was also explored.

METHOD

Three-stage consensus methodology was used: longlisting with systematic review, healthcare professional event, patient engagement, and Delphi-piloting; shortlisting with two rounds of modified Delphi; and a confirmatory stage using a modified nominal group technique. This included a selection of measurement instruments, and iterative generation of a written EPS definition.

RESULTS

One hundred and three and 119 participants took part in the modified Delphi and consensus meetings, respectively. This encompassed international patient and healthcare professional representation with multidisciplinary input. Seventy statements were longlisted, seven core outcomes (bowel obstruction, enteroperineal fistula, chronic perineal sinus, infected pelvic collection, bowel obstruction, morbidity from reconstruction, re-intervention, and quality of life), and four core descriptors (magnitude of surgery, radiotherapy-induced damage, methods of reconstruction, and changes in volume of pelvic dead space) reached consensus-where applicable, measurement of these outcomes and descriptors was defined. A written definition for EPS was agreed.

CONCLUSIONS

EPS is an area of unmet research and clinical need. This study provides an agreed definition and core data set for EPS to facilitate further research.

Minimum standards of pelvic exenterative practice: PelvEx Collaborative guideline

This document outlines the important aspects of caring for patients who have been diagnosed with advanced pelvic cancer. It is primarily aimed at those who are establishing a service that adequately caters to this patient group. The relevant literature has been summarized and an attempt made to simplify the approach to management of these complex cases.

Simultaneous pelvic exenteration and liver resection for primary rectal cancer with synchronous liver metastases: results from the PelvEx Collaborative

AIM

At presentation, 15-20% of patients with rectal cancer already have synchronous liver metastases. The aim of this study was to determine the surgical and survival outcomes in patients with advanced rectal cancer who underwent combined pelvic exenteration and liver (oligometastatic) resection.

METHOD

Data from 20 international institutions that performed simultaneous pelvic exenteration and liver resection between 2007 and 2017 were accumulated. Primarily, we examined perioperative outcomes, morbidity and mortality. We also assessed the impact that margin status had on survival.

RESULTS

Of 128 patients, 72 (56.2%) were men with a median age of 60 years [interquartile range (IQR) 15 years]. The median size of the liver oligometastatic deposits was 2 cm (IQR 1.8 cm). The median duration of surgery was 406 min (IQR 240 min), with a median blood loss of 1090 ml (IQR 2010 ml). A negative resection margin (R0 resection) was achieved in 73.5% of pelvic exenterations and 66.4% of liver resections. The 30-day mortality rate was 1.6%, and 32% of patients had a major postoperative complication. The 5-year overall survival for patients in whom an R0 resection of both primary and metastatic disease was achieved was 54.6% compared with 20% for those with an R1/R2 resection (P = 0.006).

CONCLUSION

Simultaneous pelvic exenteration and liver resection is feasible, with acceptable morbidity and mortality. Simultaneous resection should only be performed where an R0 resection of both pelvic and hepatic disease is anticipated.

Abstract P2-07-04: A novel diagnostic androgen receptor gene signature links clinical outcomes and preclinical response to enzalutamide, paclitaxel or the combination in triple-negative breast cancer

Background: The androgen receptor (AR) is expressed in ≈70% of all breast cancers (BCs) and may be necessary for proliferation and survival advantage in AR+ tumors. A novel gene signature associated with AR-signaling biology (PREDICT AR) was developed by sequencing triple-negative BC (TNBC) tumors collected in a phase 2 study evaluating enzalutamide (ENZA) monotherapy1; clinical outcomes were superior in patients (pts) with PREDICT AR+ vs PREDICT AR- tumors.1,2 ENZA blocks nuclear localization and suppresses its activity.3 Paclitaxel (PTX) stabilizes microtubules and may also block AR nuclear localization. Thus we hypothesize that response to PTX-based therapy may be additive in PREDICT AR+ vs PREDICT AR- disease. This study sought to identify independent clinical datasets with PREDICT AR+ gene signature to assess outcomes following PTX-based therapy. Preclinically, we investigated the antitumor activity of ENZA, PTX, or ENZA+PTX in AR-driven TNBC models.

Methods: We probed publicly available TNBC clinical databases from Gene Expression Omnibus datasets to assess PREDICT AR status and clinical outcomes. Similarly, we assessed 21 TNBC lines for PREDICT AR status. BT549, MDA-MB-436, and MDA-MB-453 were treated with ENZA, PTX, or ENZA+PTX to determine activity. Cell signaling and pathway activation were assessed by western blot. ENZA and PTX activity was assessed in PREDICT AR+ xenograft models. Tumor RNA sequencing and immunohistochemistry were used to identify gene signatures, potentially predictive biomarkers, and potential synergistic effects of ENZA+PTX.

Results: The prevalence of PREDICT AR+ tumors in one cohort of 182 pts with primary TNBC4 was 51%. Distant relapse-free survival following PTX-based adjuvant/neoadjuvant therapy was not statistically different between pts with PREDICT AR+ vs PREDICT AR- TNBC (p=0.605). Pathologic complete response rates were 12.5% for PREDICT AR+ vs 21.0% for PREDICT AR- TNBC. Additional sets of pts with primary TNBC are being evaluated. Preclinically, we observed a dose-dependent inhibition of cell viability with either ENZA or PTX in AR+ TNBC cell lines and additive effects from ENZA+PTX. In PREDICT AR+ xenograft models, ENZA or PTX treatment resulted in a dose-dependent antitumor response. Combination studies are underway. Tumor RNA sequencing are being evaluated for gene signature of synergistic antitumor response to ENZA+PTX.

Conclusion: Analyzing publicly available clinical datasets, we found that PREDICT AR+ status was not associated with differential outcomes following PTX-based therapy in primary TNBC, suggesting there is potential to provide additive benefits in PTX-based therapy with ENZA. In preclinical studies, we observed additive effects when combining ENZA+PTX in PREDICT AR+ TNBC lines compared with single agent treatments. Taken together, these data suggest ENZA combined with PTX might provide additive benefits in a clinical setting for pts with PREDICT AR+ TNBC.

References

1. Traina TA et al. J Clin Oncol 2015:33(suppl):abstr 1003.

2. Parker J et al. J Clin Oncol 2015;33(suppl):abstr 1083.

3. Tran C et al. Science 2009;324:787-90.

4. Hatzis C et al. JAMA 2011;305:1873-81.

Citation Format: Phan VT, Protter AA, Peterson AC, Parker JS, Yoon K, Tudor IC, Paton V, Noonberg S, Uppal H. A novel diagnostic androgen receptor gene signature links clinical outcomes and preclinical response to enzalutamide, paclitaxel or the combination in triple-negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-07-04.

Use of oral ketoconazole to prevent postoperative erections following penile surgery

Analgesics and topical agents ineffectively inhibit painful erections after penile and urethral surgery. Oral ketoconazole reversibly inhibits testosterone production and has been used empirically at our institution to decrease postoperative erections. We performed a retrospective review of 38 patients who had undergone penile and urethral reconstructive surgery. In all, 31 patients received 400 mg of ketoconazole three times daily for 10-14 days postoperatively (the study group) and seven patients did not receive ketoconazole (the control group). The incidence of postoperative erections, pain, side effects, surgical outcomes and patient satisfaction in each group were compared. Of the control group, 71% reported erections in the immediate postoperative period, and all these patients reported the erections were painful. Only 23% of the patient taking ketoconazole reported postoperative erections, and only 16% reported the erections were painful. We conclude that ketoconazole effectively prevents painful postoperative erections with minimal side effects.

The prevalence of testicular microlithiasis in an asymptomatic population of men 18 to 35 years old

PURPOSE

Testicular microlithiasis is an imaging entity of the testicle thought to be a marker of testicular cancer. To our knowledge the prevalence of testicular microlithiasis in an asymptomatic population at risk for testicular cancer is unknown. We report an ultrasound screening study done to establish the prevalence of testicular microlithiasis in an asymptomatic population.

MATERIALS AND METHODS

Healthy men 18 to 35 years old from the annual Army Reserve Officer Training Corps training camp volunteered for study. A screening genitourinary history was obtained, and physical examination and screening scrotal ultrasound were performed. We defined testicular microlithiasis as more than 5 high intensity signals on ultrasound with each signal larger than 2 mm. We categorized testicular microlithiasis into microcalcifications that were scant-5 to 25 per side, moderate-greater than 25 per side but no areas of near confluence and too numerous to count. In all subjects with testicular microlithiasis tumor markers were also measured.

RESULTS

Of 1,504 evaluated men with a mean age of 22.4 years, 84 (5.6%) had testicular microlithiasis, including 45 of 1,053 white (4%), 21 of 149 black (14.1%), 6 of 71 Hispanic (8.5%), 3 of 54 Asian or Pacific Island (5.6%) men and 9 of 174 (5.2%) who claimed no race affiliation. Tumor markers were normal in all subjects with testicular microlithiasis.

CONCLUSIONS

Testicular microlithiasis occurs in more than 5% of healthy young men. In contrast, testicular cancer develops in 3/100,000 to 5/100,000 men or 1,000-fold less often. The relative prevalence of testicular microlithiasis with respect to testicular cancer, increased prevalence in minorities, bilateral distribution, and inverse geographic distribution of men with testicular microlithiasis and testicular cancer represent evidence against an association of the 2 conditions. This study indicates that testicular microlithiasis is a common finding in asymptomatic men that may not be related to testicular cancer.

Plastibell template circumcision: a new technique

A novel circumcision technique using the Plastibell as a template is described. This technique is fast and ensures excellent cosmesis compared with the standard sleeve circumcision. It is easy to perform and allows the urologist to achieve consistently excellent cosmetic results. We describe the technique in detail.

Neurofilament cytoskeleton disruption does not modify accumulation of trophic factor mRNA

Previously we described a transgenic mouse model in which neurofilaments are sequestered in neuronal cell bodies and withheld from the axonal compartment. This model and other transgenic models with disrupted neurofilaments are used widely to investigate the role of the neurofilament cytoskeleton in normal neurons and in inherited or acquired diseases. To interpret such studies, it is important to establish whether the maldistribution of neurofilaments has major secondary consequences on the cell biology of the affected neurons. Notably, multiple perturbations of the nervous system simultaneously affect both the neuronal cytoskeleton and neurotrophin expression. To determine whether the expression of neurotrophic factors or their receptors is perturbed by a primary disruption in neurofilaments, we compared the accumulated mRNA levels for ciliary neuroptrophic factor (CNTF), nerve growth factor, neurotrophin 3, and the alpha CNTF receptor in mature transgenic mice and their littermate controls. Consistently with the prolonged survival of neurons expressing atypical or abnormally distributed neurofilaments, no obvious changes were observed for any of the mRNA species examined.

Widespread expression of netrin-1 by neurons and oligodendrocytes in the adult mammalian spinal cord

Netrins are a family of secreted proteins that function as chemotropic axon guidance cues during neural development. Here we demonstrate that netrin-1 continues to be expressed in the adult rat spinal cord at a level similar to that in the embryonic CNS. In contrast, netrin-3, which is also expressed in the embryonic spinal cord, was not detected in the adult. In situ hybridization analysis demonstrated that cells in the white matter and the gray matter of the adult spinal cord express netrin-1. Colocalization studies using the neuronal marker NeuN revealed that netrin-1 is expressed by multiple classes of spinal interneurons and motoneurons. Markers identifying glial cell types indicated that netrin-1 is expressed by most, if not all, oligodendrocytes but not by astrocytes. During neural development, netrin-1 has been proposed to function as a diffusible long-range cue for growing axons. We show that in the adult spinal cord the majority of netrin-1 protein is not freely soluble but is associated with membranes or the extracellular matrix. Fractionation of adult spinal cord white matter demonstrated that netrin-1 was absent from fractions enriched for compact myelin but was enriched in fractions containing periaxonal myelin and axolemma, indicating that netrin-1 protein may be localized to the periaxonal space. These findings suggest that in addition to its role as a long-range guidance cue for developing axons, netrin may have a short-range function associated with the cell surface that contributes to the maintenance of appropriate neuronal and axon-oligodendroglial interactions in the mature nervous system.

A unique role for Fyn in CNS myelination

We analyzed the role of Fyn tyrosine kinase in CNS myelination by using fyn(-/-) null mutant mice, which express no Fyn protein. We found a severe myelin deficit in forebrain at all ages from 14 d to 1 year. The deficit was maximal at 1 month of age and was similar regardless of mouse strain background or whether it was determined by bulk isolation of myelin or by quantitation of myelin basic protein. To determine the cellular basis of the myelin deficit, we counted oligodendrocytes in tissue sections of mice expressing oligodendrocyte-targeted beta-galactosidase, and we used light and electron microscopy to examine the number and morphology of myelinated fibers and size of myelinated CNS structures. All of these parameters were reduced in fyn(-/-) mice. Unexpectedly, there were regional differences in the myelin deficit; in contrast to forebrain, fyn(-/-) cervical spinal cord exhibited no reduction in myelin content, number of oligodendrocytes, or number of myelinated fibers, nor was myelination delayed developmentally. We found that oligodendrocytes express Src, but there was no significant reduction of myelin content in null mutants lacking the Fyn-related kinases Src, Yes, or Lyn. Finally, we investigated the molecular features of Fyn that are required for myelination and found that a single amino acid substitution, which abolishes the tyrosine kinase activity of Fyn, resulted in a myelin deficit as great as that observed in the complete absence of Fyn protein. These results demonstrate that Fyn plays a unique role in myelination, one that requires its kinase activity.

Model for focal demyelination of the spinal dorsal columns of transgenic MBP-LacZ mice by phototargeted ablation of oligodendrocytes

Focal demyelination models provide powerful tools to study demyelination and remyelination in the central nervous system. In this report, we present a novel technique, which selectively targets oligodendrocytes within the spinal cord of transgenic mice to produce focal demyelination. Transgenic mice expressing the E. coli LacZ (beta-galactosidase) gene from the myelin basic protein promotor allowed for oligodendrocyte-specific cleavage of topically applied fluorescein-di-beta-galactopyranoside liberating photoactivatable fluorescein. Subsequent fluorescence illumination generated oxygen radicals that oxidized a second exogenous substrate, 3-amino-9-ethyl carbazole, to form a toxic precipitate within oligodendrocytes. Histochemical staining of the spinal cord dorsal columns 8 days following phototargeting revealed that the treated region no longer contained beta-galactosidase-positive cells. Focal demyelination of the dorsal columns was observed to a depth of 150 microm in transverse semithin plastic sections. Numerous bundles of naked axons interspersed with myelin, debris-laden macrophages, and reactive astrocytes were evident by electron microscopy. Remyelination of axons by both oligodendrocytes and invading Schwann cells was observed within the treated region 14 days after phototargeting. Newly generated oligodendrocytes were identified within the demyelinated region by their incorporation of bromodeoxyuridine. Thus, this novel focal demyelination protocol provides: (1) a method for selective targeted ablation of oligodendrocytes in vivo, (2) control over the extent of the demyelinated region, with (3) an environment that maintains its remyelination capacity. Phototargeted ablation of oligodendrocytes may therefore be a useful model for studying axon-glia interactions, axon regeneration within a demyelinated zone, and remyelination of axons.

Outcomes of varicocele ligation done for pain

PURPOSE

Surgical ligation is an option in the management of patients with painful varicocele. Little objective data exist addressing the effectiveness of this treatment. We reviewed records from 58 patients who underwent varicocele ligation at our institution from January 1985 to May 1996 to establish success of surgical ligation of the painful varicocele.

MATERIALS AND METHODS

ICD-9 billing codes were used to identify all patients who had undergone varicocele ligation for pain since 1985. We documented patient age, grade and location of varicocele, duration and quality of pain, response to conservative therapy and surgical approach to ligation. Telephone interviews and chart reviews were conducted to determine resolution of pain, complications of the procedure and if the patient would choose surgery again.

RESULTS

We obtained followup on 35 of the 58 painful varicocele patients (60%). Average patient age was 25.7 years (range 15 to 65). The varicocele was on the left side in 30 men and bilateral in 5. Of the patients 31 described the pain as a dull throbbing ache, 2 as sharp and 2 as a pulling sensation. Initial conservative therapy failed in all 35 men. Varicocele was grade III in 18 cases, grade II in 16 and grade I in 1. The inguinal or subinguinal approach was used in 24 patients, high ligation in 10 and laparoscopic repair in 1. In 30 patients there was (86%) complete resolution of pain postoperatively and 1 had partial resolution. Only 4 patients (11%) had persistent or worse symptoms.

CONCLUSIONS

This retrospective review supports the conclusion that varicocele ligation is an effective treatment for painful varicocele in properly selected patients.

Pathogenesis of two axonopathies does not require axonal neurofilaments

Neurofilaments are a major component of the axonal cytoskeleton and their abnormal accumulation is a prominent feature of the cytopathology encountered in several neurodegenerative diseases. Thus, an attractive and widely held model of pathogenesis involves the participation of disrupted neurofilaments as a common toxic intermediate. Here, in direct contrast to this hypothesis, we show that two neurodegenerative disease models in the mouse, dystonia musculorum (dt) and a superoxide dismutase 1 (SOD1)-mediated form of human motor neuron disease (amyotrophic lateral sclerosis, ALS), progress with little or no abatement on a transgenic background in which neurofilaments are withheld from the axonal compartment. By specifically excluding a necessary role for axonal neurofilaments, our observations redefine the components of the pathogenic pathway leading to axon disruption in these two degenerative diseases.

Factors contributing to recurrent carotid disease following carotid endarterectomy

BACKGROUND

Retrospective analysis was performed to assess the effect of gender, age, hypertension, diabetes, and smoking upon residual disease, recurrent disease, and progression of disease following carotid endarterectomy (CE). The effect of patch versus primary closure was also studied.

METHODS

Postoperative duplex studies were performed following 323 CEs at months 1, 6, 12, and 24. Residual disease was defined as luminal stenosis >59% at 1 month. Progression of disease was defined as stenosis at any month that was greater than stenosis at month 1. Recurrent disease was nonresidual stenosis >79%.

RESULTS

Correlation was found between age at operation <65 years and cigarette smoking; both also correlated with progression of disease on serial studies, as well as recurrent stenosis <79%. Primary closure of the arteriotomy correlated with residual disease.

CONCLUSION

Primary closure of the arteriotomy following CE increases the likelihood of residual disease. Smokers and those aged <65 years are predisposed to progression of postoperative disease, and to development of recurrent stenosis.

Tissue-specific selection for different mtDNA genotypes in heteroplasmic mice

Mammalian mitochondrial DNA (mtDNA) is a highly polymorphic, high-copy-number genome that is maternally inherited. New mutations in mtDNA segregate rapidly in the female germline due to a genetic bottleneck in early oogenesis and as a result most individuals are homoplasmic for a single species of mtDNA. Sequence variants thus accumulate along maternal lineages without genetic recombination. Most of the extant variation in mtDNA in mammalian populations has been assumed to be neutral with respect to selection; however, comparisons of the ratio of replacement to silent nucleotide substitutions between species suggest that the evolution of mammalian mtDNA is not strictly neutral. To test directly whether polymorphic mtDNAs behave as neutral variants, we examined the segregation of two different mtDNA genotypes in the tissues of heteroplasmic mice. We find evidence for random genetic drift in some tissues, but in others strong, tissue-specific and age-related, directional selection for different mtDNA genotypes in the same animal. These surprising data suggest that the coding sequence of mtDNA may represent a compromise between the competing demands of different tissues and point to the existence of unknown, tissue-specific nuclear genes important in the interaction between the nuclear and mitochondrial genomes.

Increased severity of experimental autoimmune encephalomyelitis, chronic macrophage/microglial reactivity, and demyelination in transgenic mice producing tumor necrosis factor-alpha in the central nervous system

Tumor necrosis factor-alpha (TNF-alpha) is an inflammatory cytokine implicated in a number of autoimmune diseases. Apoptotic cell death is induced by TNF-alpha in vitro, and has been suggested as one cause of autoimmune pathology, including autoimmune demyelinating diseases where oligodendrocytes are a target of immune attack. TNF-alpha also regulates macrophage activity which could contribute to autoimmune inflammation. We have expressed TNF-alpha at disease-equivalent levels in the central nervous system of transgenic mice, using a myelin basic protein (MBP) promoter. These mice were normal and showed no spontaneous pathology, but they developed experimental autoimmune encephalomyelitis (EAE) with greater severity than nontransgenic controls when immunized with MBP in adjuvant. Unlike nontransgenic controls, EAE then progressed to a nonabating demyelinating disease. Macrophage/microglial reactivity was evident in demyelinating lesions in spinal cord, but T cells were not detected during chronic disease. The participation of TNF-alpha in the demyelinating process is thus more probably due to the perpetuation of macrophage/microglial activation than to direct cytotoxicity of myelin or oligodendroglia.

Multipotent CNS stem cells are present in the adult mammalian spinal cord and ventricular neuroaxis

Neural stem cells in the lateral ventricles of the adult mouse CNS participate in repopulation of forebrain structures in vivo and are amenable to in vitro expansion by epidermal growth factor (EGF). There have been no reports of stem cells in more caudal brain regions or in the spinal cord of adult mammals. In this study we found that although ineffective alone, EGF and basic fibroblast growth factor (bFGF) cooperated to induce the proliferation, self-renewal, and expansion of neural stem cells isolated from the adult mouse thoracic spinal cord. The proliferating stem cells, in both primary culture and secondary expanded clones, formed spheres of undifferentiated cells that were induced to differentiate into neurons, astrocytes, and oligodendrocytes. Neural stem cells, whose proliferation was dependent on EGF+bFGF, were also isolated from the lumbar/sacral segment of the spinal cord as well as the third and fourth ventricles (but not adjacent brain parenchyma). Although all of the stem cells examined were similarly multipotent and expandable, quantitative analyses demonstrated that the lateral ventricles (EGF-dependent) and lumbar/sacral spinal cord (EGF+bFGF-dependent) yielded the greatest number of these cells. Thus, the spinal cord and the entire ventricular neuroaxis of the adult mammalian CNS contain multipotent stem cells, present at variable frequency and with unique in vitro activation requirements.

Random genetic drift in the female germline explains the rapid segregation of mammalian mitochondrial DNA

Mitochondrial DNA (mtDNA) is maternally inherited in mammals. Despite the high genome copy number in mature oocytes (10(5)) and the relatively small number of cell divisions in the female germline, mtDNA sequence variants segregate rapidly between generations. To investigate the molecular basis for this apparent paradox we created lines of heteroplasmic mice carrying two mtDNA genotypes. We show that the pattern of segregation can be explained by random genetic drift occurring in early oogenesis, and that the effective number of segregating units for mtDNA is approximately 200 in mice. These results provide the basis for estimating recurrence risks for mitochondrial disease due to pathogenic mtDNA mutations and for predicting the rate of fixation of neutral mtDNA mutations in maternal lineages.

Visualization of slow axonal transport in vivo

In axons, cytoskeletal constituents move by slow transport. However, it remains controversial whether axonal neurofilaments are dynamic structures in which only subunits are transported or whether filaments assemble in the proximal axon and are transported intact as polymers to the axon terminus. To investigate the form neurofilament proteins take during transport, neurons of transgenic mice lacking axonal neurofilaments were infected with a recombinant adenoviral vector encoding epitope-tagged neurofilament M. Confocal and electron microscopy revealed that the virally encoded neurofilament M was transported in unpolymerized form along axonal microtubules. Thus, neurofilament proteins are probably transported as subunits or small oligomers along microtubules, which are major routes for slow axonal transport.

Determination of neuroepithelial cell fate: induction of the oligodendrocyte lineage by ventral midline cells and sonic hedgehog

Near the floor plate of the embryonic neural tube there is a group of neuroepithelial precursor cells that are specialized for production of the oligodendrocyte lineage. We performed experiments to test whether specification of these neuroepithelial oligodendrocyte precursors, like other ventral neural cell types, depends on signals from the notochord and/or floor plate. We analyzed heterozygous Danforth's short tail (Sd/+) mutant mice, which lack a notochord and floor plate in caudal regions of the neural tube, and found that oligodendrocyte precursors did not appear at the ventricular surface where there was no floor plate. Moreover, oligodendrocytes did not develop in explant cultures of Sd/+ spinal cord in the absence of a floor plate. When a second notochord was grafted into an ectopic position dorsolateral to the endogenous notochord of a chicken embryo, an additional floor plate was induced along with an ectopic focus of oligodendrocyte precursors at the ventricular surface. Oligodendrocytes developed in explants of intermediate neural tube only when they were cocultured with fragments of notochord or in the presence of purified Sonic hedgehog (Shh) protein. Thus, signals from the notochord/floor plate, possibly involving Shh, are necessary and sufficient to induce the development of ventrally derived oligodendroglia. These signals appear to act by specifying the future fate(s) of neuroepithelial cells at the ventricular surface rather than by influencing the proliferation or differentiation of prespecified progenitor cells in the parenchyma of the cord.

Chlorhexidine gluconate 0.12% oral rinse reduces the incidence of total nosocomial respiratory infection and nonprophylactic systemic antibiotic use in patients undergoing heart surgery

STUDY OFJECTIVE: The purpose of this study was to test the effectiveness of oropharyngeal decontamination on nosocomial infections in a comparatively homogeneous population of patients undergoing heart surgery.

DESIGN

This was a prospective, randomized, double-blind, placebo-controlled clinical trial. Experimental and control groups were selected for similar infection risk parameters. SEETTING: Cardiovascular ICU of a tertiary care hospital.

PATIENTS

Three hundred fifty-three consecutive patients undergoing coronary artery bypass grafting, valve, or other open heart surgical procedures were randomized to an experimental (n=173) or control (n=180) group. Heart and lung transplantations were excluded.

INTERVENTIONS

The experimental drug chosen was 0.12% chlorhexidine gluconate (CHX) oral rinse.

MEASUREMENTS AND RESULTS

The overall nosocomial infection rate was decreased in the CHX-treated patients by 65% (24/180 vs 8/173; p<0.01). We also noted a 69% reduction in the incidence of total respiratory tract infections in the CHX-treated group (17/180 vs 5/173; p<0.05). Gram-negative organisms were involved in significantly less (p<0.05) of the nosocomial infections and total respiratory tract infections by 59% and 67%, respectively. No change in bacterial antibiotic resistance patterns in either group was observed. The use of nonprophylactic IV antibiotics was lowered by 43% (42/180 vs 23/173; p<0.05). A reduction in mortality in the CHX-treated group was also noted (1.16% vs 5.56%).

CONCLUSIONS

Inexpensive and easily applied oropharyngeal decontamination with CHX oral rinse reduces the total nosocomial respiratory infection rate and the use of nonprophylactic systemic antibiotics in patients undergoing heart surgery. This results in significant cost savings for those patients who avoid additional antibiotic treatment.

Annexin IV is a marker of roof and floor plate development in the murine CNS

Midline structures, such as the notochord and floor plate, are crucial to the developing central nervous system (CNS). Previously, we demonstrated that annexin IV is an excellent marker of midline structures. In the present study, we explore the possible role of annexin IV in development of the CNS midline. Using immunocytochemistry with an antibody to annexin IV, we have elucidated the temporal and spatial expression of this molecule. Annexin IV is present in the notochord at embryonic day (E) 8.5, prior to its expression in any structures within the neural tube. Subsequently, annexin IV is expressed by floor plate cells at E9.5. Annexin IV is also expressed in the roof plate, but not until E10.5. To determine if normal morphogenesis of these midline structures is essential for annexin IV expression, we analyzed two strains of mutant mice that have defective formation of either the floor or the roof plate. In Danforth's short-tail mice, the floor plate is absent from the caudal spinal cord, and annexin IV immunopositivity disappears at the level where the floor plate is missing. In curly tail mutant mice, there can be a failure of the neural tube to close, and in these regions there is no annexin IV expression in presumptive roof plate cells. Finally, annexin IV immunolabeling is present from the caudal spinal cord, through the brainstem up to the diencephalon and lamina terminalis. Thus, annexin IV is an excellent marker for differentiated midline cells, is temporally and spatially correlated with development of the floor and roof plates, and is expressed in a rostral-caudal manner that supports the hypothesis that the floor plate extends the full length of the original neural tube.

Durability of emergency coronary artery bypass for complications of failed angioplasty

Although emergency coronary artery bypass for complications of percutaneous transluminal coronary angioplasty (PTCA) has proved to be a relatively successful 'bail-out' procedure, little is known about the durability of revascularization under these potentially disastrous circumstances. The authors therefore retrospectively examined their results with this procedure. Emergency coronary artery bypass for complications of PTCA was performed in 112 patients between 1 January 1984 and 19 May 1992. Fifteen patients underwent PTCA for acute myocardial infarction. Eleven patients (9.8%) were stable, and underwent emergency coronary artery bypass after PTCA because of suboptimal angiographic results from percutaneous transluminal coronary angioplasty. None of these stable patients died. The remainder of the patients underwent emergency coronary artery bypass after PTCA because of ongoing documented ischemia, including cardiac arrest requiring cardiopulmonary resuscitation during transit to the operating room in 11 patients (9.8%) and preoperative intra-aortic counterpulsation in 24 (21.4%). The average number of coronary arteries bypassed at emergency coronary artery bypass was 2.2, and 19 patients (17%) received at least one mammary artery conduit. The perioperative incidence of myocardial infarction was 8.9% (10/112), and the operative mortality rate 8% (9/112). During follow-up, which averaged 55 months, the survival rate (including operative mortality) was 85% while 98% of patients experienced freedom from reoperative coronary bypass, 89% experienced freedom from myocardial infarction (including postoperative) and 90% experienced freedom from subsequent catheterization or PTCA. In conclusion, emergency coronary artery bypass for PTCA complications successfully avoids subsequent untoward cardiac events. When compared with published results of PTCA without emergency coronary artery bypass, emergency coronary bypass is more reliable for avoiding subsequent cardiac catheterization (with or without PTCA) than PTCA alone.

Clinical heparin coated cardiopulmonary bypass: reduction of systemic heparin requirements for redo cardiac surgery

The authors compared blood loss, transfusion requirements, and heparin doses for reoperative cardiac surgery using either: a) a Duraflow (Baxter Corporation, Irvine, CA) heparin coated cardiopulmonary bypass (CPB) system or b) standard CPB. Twenty patients underwent redo cardiac surgery while supported with heparin coated CPB, and 17 patients underwent redo cardiac surgery with standard CPB. The following data are presented as mean +/- standard deviation. The heparin coated CPB circuit group received significantly less heparin than the standard CPB group (322 +/- 80 IU/kg versus 448 +/- 80 IU/kg, p < 0.01). There was no difference in blood loss in the first 24 postoperative hrs or mean transfusion requirements for the two groups. Despite the reduced dose of heparin, the mean activated clotting time in the heparin coated group was similar to the mean activated clotting time of the standard CPB group (577 +/- 98 sec versus 612 +/- 117 sec, p = ns). In conclusion, heparin coated CPB without reduced activated clotting time does not reduce transfusion requirements or blood loss in reoperative cardiac surgery. The heparin coated CPB system allows maintenance of the activated clotting time level despite reduced heparin doses.

Dramatically different phenotypes in mouse models of human Tay-Sachs and Sandhoff diseases

We have generated mouse models of human Tay-Sachs and Sandhoff diseases by targeted disruption of the Hexa (alpha subunit) or Hexb (beta subunit) genes, respectively, encoding lysosomal beta-hexosaminidase A (structure, alpha) and B (structure, beta beta). Both mutant mice accumulate GM2 ganglioside in brain, much more so in Hexb -/- mice, and the latter also accumulate glycolipid GA2. Hexa -/- mice suffer no obvious behavioral or neurological deficit, while Hexb -/- mice develop a fatal neurodegenerative disease, with spasticity, muscle weakness, rigidity, tremor and ataxia. The Hexb -/- but not the Hexa -/- mice have massive depletion of spinal cord axons as an apparent consequence of neuronal storage of GM2. We propose that Hexa -/- mice escape disease through partial catabolism of accumulated GM2 via GA2 (asialo-GM2) through the combined action of sialidase and beta-hexosaminidase B.

The distribution of linkage disequilibrium over anonymous genome regions

Linkage disequilibrium (LD), the association of alleles at different loci, is a powerful tool for genetic mapping and for investigating, at the population level, processes such as recombination, selection, mutation and admixture. Little is known about the distribution of LD across mammalian genomes. Therefore, a survey was undertaken, using microsatellite loci, to evaluate the distribution of LD over several regions of human chromosome 4. Radiation hybrid (RH) and linkage maps provided information on physical and genetic distances between these loci. A Finnish population sample was genotyped using 32 microsatellite loci, and partial marker haplotypes were determined. Assessment of LD was performed, between all pairs of loci, using the Fisher's exact test. LD was detected between several loci that were separated by more than 1 Mb or 1 cM. Detection of LD was strongly associated with small physical distance; its relation to genetic distance was more equivocal. This result may support the hypothesis that linkage maps are relatively inaccurate over small distances. Our results suggest that LD is widely distributed in anonymous regions of the human genome and its use may allow more accurate measurement of small genetic distances than does standard linkage analysis. Alternative explanations are considered for comparisons in which LD is not detected between tightly linked loci.

Inhibition of Rhizobium etli Polysaccharide Mutants by Phaseolus vulgaris Root Compounds

Crude bean root extracts of Phaseolus vulgaris were tested for inhibition of the growth of several polysaccharide mutants of Rhizobium etli biovar phaseoli CE3. Mutants deficient only in exopolysaccharide and some mutants deficient only in the O-antigen of the lipopolysaccharide were no more sensitive than the wild-type strain to the extracts, whereas mutants defective in both lipopolysaccharide and exopolysaccharide were much more sensitive. The inhibitory activity was found at much higher levels in roots and nodules than in stems or leaves. Inoculation with either wild-type or polysaccharide-deficient R. etli did not appear to affect the level of activity. Sequential extractions of the crude root material with petroleum ether, ethyl acetate, methanol, and water partitioned inhibitory activity into each solvent except methanol. The major inhibitors in the petroleum ether and ethyl acetate extracts were purified by C 18 high-performance liquid chromatography. These compounds all migrated very similarly in both liquid and thin-layer chromatography but were distinguished by their mass spectra. Absorbance spectra and fluorescence properties suggested that they were coumestans, one of which had the mass spectrum and nuclear magnetic resonances of coumestrol. These results are discussed with regard to the hypothesis that one role of rhizobial polysaccharides is to protect against plant toxins encountered during nodule development.

Mutational processes of simple-sequence repeat loci in human populations

Mutational processes of simple sequence repeats (SSRs) in complex genomes are poorly understood. We examined these processes by introducing a two-phase mutation model. In this model, most mutations are single-step changes, but infrequent large jumps in repeat number also occur. We used computer simulations to determine expected values of statistics that reflect frequency distributions of allele size for the two-phase model and two alternatives, the one-step and geometric models. The theoretical expectations for each model were tested by comparison with observed values for 10 SSR loci genotyped in the Sardinian population, whose genetic and demographic histories have been previously reconstructed. The two-phase model provided the best fit to the data for most of these loci in this population. In the analysis we assumed that the loci were neutral and that this population had undergone rapid population growth. Recent observations made for unstable trinucleotide repeats support our suggestion that frequent small changes and rare large changes in repeat number represent two distinct classes of mutation at SSR loci. We genotyped the same 10 loci in Egyptian and sub-Saharan African samples to assess the utility of SSRs for studying the divergence of populations and found that estimates of interpopulation distances from SSRs were similar to those derived from analysis of mitochondrial DNA.

Expression of a lacZ transgene reveals floor plate cell morphology and macromolecular transfer to commissural axons

The floor plate is situated at the ventral midline of the neural tube and is an important intermediate target for commissural axons. During elongation, these axons converge bilaterally on the ventral midline neural tube and after crossing the floor plate make an abrupt rostral turn. Ample evidence indicates that the initial projection of commissural axons to the floor plate is guided by a chemotropic factor secreted by floor plate cells. However, the way in which the subsequent interaction of these axons with the floor plate leads them to make further trajectory changes remains undefined. In an effort to gain further understanding of the structure and function of floor plate cells, we have taken advantage of a line of transgenic mice in which these cells express beta-galactosidase and thus can be stained by histochemical means. In this line, a genomic imprinting mechanism restricts the expression of the lacZ transgene to only a proportion of the floor plate cells, allowing their morphology to be appreciated with particular clarity. Our analysis revealed that the basal processes of floor plate cells are flattened in their rostrocaudal dimension and possess fine lateral branches which are aligned with commissural axons. Unexpectedly, beta-galactosidase activity was also detected within longer transverse linear profiles traversing the floor plate whose ultrastructural appearance was not that of floor plate cells but instead corresponded to that of commissural axons. Enzyme activity was not detected in more proximal axonal segments or in the neuronal cell bodies from which these axons originated. Therefore, we propose that the transgene product, and potentially other proteins synthesized by floor plate cells, can be transferred to decussating axons.

Prophylaxis of heart transplant rejection with either antithymocyte globulin-, Minnesota antilymphocyte globulin-, or an OKT3-based protocol

We compared an equine antithymocyte globulin (ATGAM)-based protocol with a Minnesota antilymphocyte globulin (MALG)-based protocol and a murine monoclonal CD-3 (OKT-)-based protocol in 3 groups of heart transplant (HT) recipients. Thirty-four recipients received a four-day course of ATGAM. Thirty HT recipients received a 14-day course of OKT3. Fifteen HT recipients received MALG for an average of 10 days. The ATGAM group received cyclosporine beginning preoperatively, while the OKT3 and MALG groups received CyA beginning on post-transplant day 4. All three groups received identical azathioprine and similar steroid therapy. The 3 groups were similar in age, donor/recipient HLA mismatches, and donor/recipient gender mismatches. The MALG and OKT3 groups had 20% and 17% females, respectively, while the ATG group had 41% (p < 0.05). Average follow-up exceeded 14 months for each group. The ATGAM group received a higher dose of CyA during "induction" therapy than the OKT3 and MALG groups, and experienced a greater rise in post-transplant serum creatinine levels. We found no difference between the 3 groups in: preoperative creatinine levels, one-year post-transplant creatinine levels, number of patients who could be successfully "weaned" from steroids, or one-year survival. Other data are tabulated as episodes/patient: [table: see text] We conclude that ATG plus preoperative CyA is superior for rejection prophylaxis following heart transplantation when compared with either MALG plus postoperative CyA or OKT3 plus postoperative CyA.

Myelin acquisition in the central nervous system of the mouse revealed by an MBP-Lac Z transgene

Myelin has pronounced effects upon the morphology, function, and growth of axons in the mammalian CNS. Consequently, oligodendrocyte development and myelination have been investigated using a wide variety of histological, immunocytochemical, ultrastructural, and biochemical techniques. While many of the spatial and temporal features of myelin appearance have been characterized, for any one species only limited regions of the CNS have been investigated. To address this limitation, we have derived transgenic mice in which the bacterial Lac Z gene is regulated by promoter elements of the myelin basic protein gene. When differentiating oligodendrocytes begin to elaborate recognizable myelin, they initiate expression of the MBP-Lac Z transgene and accumulate readily detectable levels of beta-galactosidase. Here, we exploit the sensitivity, resolution, and ease of beta-galactosidase histochemical assays to characterize the temporal and spatial patterns of CNS myelination in the mouse. Many features of the myelination program revealed by this approach were predicted by the immunocytochemical and ultrastructural data derived from other species. Nonetheless, previously undocumented patterns were also encountered. beta-Galactosidase was expressed first by oligodendrocytes in the ventral spinal cord, 1 d prior to birth. There, myelination proceeded in a strictly rostral-caudal direction, whereas in the dorsal cord, myelination initiated in the cervical enlargement and proceeded in both rostral and caudal directions. In the cerebellum, deep regions myelinated first, and in the optic nerve, myelination initiated at the retinal end. In contrast, the lateral olfactory tracts, pons, and optic chiasm initiated myelination along their entire course.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac isoenzymes following heart transplantation

Creatine phosphokinase (CPK) isoenzymes are commonly obtained after heart transplantation (HT) to assess myocardial injury of the donor heart. This investigation retrospectively evaluated the utility of this practice. Fifty-six recipients of orthotopic heart transplants had at least two daily CPK-MB studies following HT. All patients were followed up for at least one year (or until death). Nineteen patients had entirely negative CPK-MB determinations (NEG). Eighteen patients had a single positive CPK-MB determination, and were considered to be equivocal (EQUIV). Nineteen patients had more than one daily positive CPK-MB determination (POS). To evaluate the influence of positive CPK-MB determinations on the outcome of HT, we compared the results in the NEG and POS groups. There was no difference in the donor organ ischemic times between the two groups. The duration of follow-up for the two groups was also similar (1,192 days vs 1,020 days). The NEG and POS groups had no significant difference in: 1 year survival (84 percent vs 74 percent); freedom from treated rejection episodes in 3 months (39 percent vs 42 percent); and freedom from coronary artery disease (CAD) at 3 years (83 percent vs 86 percent). Additionally, the ejection fractions of the donor hearts were similar at 1 year post-transplant for the 2 groups (64 percent vs 59 percent). We conclude that myocardial injury, as reflected by post-transplant CPK-MB levels, does not predict one-year mortality, predisposition to rejection, predisposition to coronary artery disease, or ultimate graft dysfunction. In an effort to perform HT more economically, we no longer obtain CPK-MB levels following HT.

An intrinsic neuronal defect operates in dystonia musculorum: a study of dt/dt<==>+/+ chimeras

In the mouse mutant dystonia musculorum (dt), peripheral and central sensory axons develop focal swellings and degenerate. To identify the primary cellular target of the mutation, we have analyzed the spinal cords of dt/dt<==>+/+ aggregation chimeras. In these chimeras, characteristic swellings appeared only on the axons of mutant genotype neurons; the axons of wild-type neurons, identified by their expression of a transgene-encoded human neurofilament protein, were normal. This direct correlation of genotype and phenotype indicates that the dt mutation acts via a mechanism intrinsic to affected neurons. In addition, we show here that the dt mutation leads to a disorder of neurofilament processing in which phosphorylated neurofilament epitopes accumulate inappropriately in neuronal perikarya.