Prognostic significance of histopathology in canine anal sac gland adenocarcinomas: Preliminary results in a retrospective study of 39 cases

Metastatic rates and survival times of canine anal sac gland adenocarcinomas (ASGACs) vary among studies, making prognostication difficult. Little is known about the prognostic significance of histopathology of ASGACs. This retrospective study investigated associations between histological features, clinical presentation and outcome for 39 ASGACs. Most tumours were incompletely excised (62%) and had moderate to marked peripheral infiltration (74%). The predominant growth pattern was solid, tubules/rosettes/pseudorosettes and papillary in 49%, 46% and 5% of the cases, respectively. Nuclear pleomorphism was either moderate (77%) or mild (23%). Necrosis and lymphovascular invasion were present in 54% and 10% of the cases, respectively. All histological features except mitotic count and necrosis were associated with nodal metastasis at presentation. A statistically significant poorer outcome was identified for tumours with a solid growth pattern, moderate or marked peripheral infiltration, necrosis and lymphovascular invasion. These results need further validation in a larger cohort of dogs.

Parapatric distribution and sexual competition between two tick species, Amblyomma variegatum and A. hebraeum (Acari, Ixodidae), in Mozambique

Background

Amblyomma variegatum and A. hebraeum are two ticks of veterinary and human health importance in south-east Africa. In Zimbabwe they occupy parapatric (marginally overlapping and juxtaposed) distributions. Understanding the mechanisms behind this parapatry is essential for predicting the spatio-temporal dynamics of Amblyomma spp. and the impacts of associated diseases. It has been hypothesized that exclusive competition between these species results from competition at the levels of male signal reception (attraction-aggregation-attachment pheromones) or sexual competition for mates. This hypothesis predicts that the parapatry described in Zimbabwe could also be present in other countries in the region.

Methods

To explore this competitive exclusion hypothesis we conducted field surveys at the two species’ range limits in Mozambique to identify areas of sympatry (overlapping areas) and to study potential interactions (communicative and reproductive interference effects) in those areas. At sympatric sites, hetero-specific mating pairs were collected and inter-specific attractiveness/repellent effects acting at long and short distances were assessed by analyzing species co-occurrences on co-infested herds and co-infested hosts.

Results

Co-occurrences of both species at sampling sites were infrequent and localized in areas where both tick and host densities were low. At sympatric sites, high percentages of individuals of both species shared attachment sites on hosts and inter-specific mating rates were high. Although cross-mating rates were not significantly different for A. variegatum and A. hebraeum females, attraction towards hetero-specific males was greater for A. hebraeum females than for A. variegatum females and we observed small asymmetrical repellent effects between males at attachment sites.

Conclusions

Our observations suggest near-symmetrical reproductive interference between A. variegatum and A. hebraeum, despite between-species differences in the strength of reproductive isolation barriers acting at the aggregation, fixation and partner contact levels. Theoretical models predict that sexual competition coupled with hybrid inviability, greatly reduces the probability of one species becoming established in an otherwise suitable location when the other species is already established. This mechanism can explain why the parapatric boundary in Mozambique has formed within an area of low tick densities and relatively infrequent host-mediated dispersal events.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-1116-7) contains supplementary material, which is available to authorized users.

Developing a disease prevention strategy in the Caribbean: the importance of assessing animal health-related risks at regional level

In 2009 CaribVET conducted a survey among Caribbean national Veterinary Services to assess perceptions of risk assessment and to identify the principal exotic diseases of concern in the region and their means of introduction. The results showed that the introduction of live animals was considered the most likely route of introduction of exotic animal pathogens, followed by the uncontrolled introduction of animal products by boat passengers. The results were used to define a regional strategy for assessing animal health risks that highlights the importance of within-region exchanges.

Risk factors for West Nile virus seropositivity of equids in Guadeloupe

In Guadeloupe, West Nile virus (WNV) activity was first observed in equids in 2002, and a high seroprevalence was found in 2003. The objective of our study was to determine individual and environmental factors associated with the risk of WNV seropositivity during 2002-2003. Fieldwork was conducted to retrospectively determine the location of equids at the time of virus circulation and to collect information regarding environmental and individual variables. Sera were collected from 369 equids out of an estimated total population of less than 500. Thirty-four environmental and individual variables were investigated. Equids had a higher risk (p<0.001) for WNV seropositivity if they lived within the proximity "distance less than 1.5km" of marshes or swamp forests "a large freshwater formation behind mangroves" or if they remained outside after dusk. Equids living within the proximity of ouassous shrimp (Macrobrachium rosenbergii) basins or sugar cane fields had a lower risk (p<0.001) for WNV seropositivity. These results confirm that WNV circulation is more likely in the humid coastal areas of Guadeloupe. The identification of risk factors is useful for predicting future emergence sites of WNV in the archipelago and other Neotropical islands, and to better target sentinel surveillance in the region.

DWnt4 and wingless elicit similar cellular responses during imaginal development

Wnt genes encode evolutionarily conserved secreted proteins that provide critical functions during development. Although Wnt proteins share highly conserved features, they also show sequence divergence, which almost certainly contributes to the variety of their signaling activities. We previously reported that DWnt4 and wingless (wg), two divergent clustered Wnt genes, can have either antagonist or distinct functions during Drosophila embryogenesis. Here we provide evidence that both genes can elicit similar cellular responses during imaginal development. Ectopic expression of DWnt4 along the anterior/posterior (A/P) boundary of imaginal discs alters morphogenesis of adult appendages. In the wing disc, DWnt4 phenocopies ectopic Wg activity by inducing notum to wing transformation, suggesting similar signaling capabilities of both molecules. In support of this, we demonstrate that DWnt4 can rescue wg loss-of-function phenotypes in the antenna and haltere and is able to substitute for Wg in wing field specification. We also show that both genes are transcribed in overlapping domains in imaginal discs, suggesting that DWnt4 may cooperate with wg during limb patterning.

Pontin52 and reptin52 function as antagonistic regulators of beta-catenin signalling activity

In Wnt-stimulated cells, beta-catenin becomes stabilized in the cytoplasm, enters the nucleus and interacts with HMG box transcription factors of the lymphoid-enhancing factor-1 (LEF-1)/T-cell factor (TCF) family, thereby stimulating the transcription of specific target genes. We recently identified Pontin52 as a nuclear protein interacting with beta-catenin and the TATA-box binding protein (TBP), suggesting its involvement in regulating beta-catenin-mediated transactivation. Here, we report the identification of Reptin52 as an interacting partner of Pontin52. Highly homologous to Pontin52, Reptin52 likewise binds beta-catenin and TBP. Using reporter gene assays, we show that the two proteins antagonistically influence the transactivation potential of the beta-catenin-TCF complex. Furthermore, we demonstrate the evolutionary conservation of this mechanism in Drosophila. dpontin and dreptin are essential genes that act antagonistically in the control of Wingless signalling in vivo. These results indicate that the opposite action of Pontin52 and Reptin52 on beta-catenin-mediated transactivation constitutes an additional mechanism for the control of the canonical Wingless/Wnt pathway.

dlarp, a new candidate Hox target in Drosophila whose orthologue in mouse is expressed at sites of epithelium/mesenchymal interactions

Hox complex genes are key developmental regulators highly conserved throughout evolution. They encode transcription factors that initiate genetic programs of diversified morphogenesis along the anteroposterior embryonic axis. We report the characterization of the novel Drosophila Hox target gene dlarp, isolated from a further screen of a previously described library of genomic DNA fragments associated in vivo with Ultrabithorax proteins. The dlarp spatio-temporal pattern of transcription in wild-type and homeotic mutant embryos is consistent with a positive regulation by Sex combs reduced and Ultrabithorax in the parasegment 2 ectoderm and the abdominal mesoderm, respectively. The teashirt gene product, thought to act in concert with Hox proteins, is also required for the transcriptional control of this target. Search in databases revealed that dlarp has been highly conserved during evolution. The embryonic expression pattern of the mouse orthologue does not support a function downstream of Hox proteins. It is mainly transcribed in neural structures and in developing organs characterized by epithelial-mesenchymal interactions.

Dynamic expression of d-CdGAPr, a novel Drosophila melanogaster gene encoding a GTPase activating protein

Small GTPases of the rho family function as signal transducer for extra-cellular stimuli to control cytoskeletal re-organization and a variety of other cellular processes including adhesion, proliferation and transcriptional regulation (Hall, A., 1998. RhoGTPases and the actin cytoskeleton. Science 279, 509-514). Usually widely expressed, their activities are tightly controlled by conformational changes induced by hydrolysis of the GTP bound molecule (Bourne H.R., Sanders D.A., 1990. The GTPase superfamily: a conserved switch for diverse cell functions. Nature 348, 125-132). Conversion of GTP to GDP relies on a rho intrinsic GTPase domain that requires GTPase activating proteins (GAPs) for potent activity (Lamarche, N., Hall. A., 1994. GAPs for rho-related GTPases. Trends Genet. 10, 436-440). Here we report on the identification of a novel Drosophila GAP gene, d-CdGAPr, encoding a protein related to mammalian CdGAPs. The gene is expressed throughout development as well as in adults. Spatio-temporal transcription pattern of d-CdGAPr during embryogenesis is highly dynamic. Abundant in the pre-blastoderm embryo prior to the onset of zygotic transcription, messengers accumulate at the blastoderm posterior pole after cellularisation. During gastrulation and subsequent development, all cells accumulate low levels of d-CdGAPr RNA, while a few territories transiently display stronger expression. Sites of preferential expression include the posterior pole of the early cellular blastoderm, the neuro-ectoderm prior to neuroblast delamination, rows of epidermal cells in the most posterior part of thoracic and first abdominal segments and a ring of epidermal cells at the posterior end of the embryo.

Distinct hox protein sequences determine specificity in different tissues

Hox genes encode evolutionarily conserved transcription factors that control the morphological diversification along the anteroposterior (A/P) body axis. Expressed in precise locations in the ectoderm, mesoderm, and endoderm, Hox proteins have distinct regulatory activities in different tissues. How Hox proteins achieve tissue-specific functions and why cells lying at equivalent A/P positions but in different germ layers have distinctive responses to the same Hox protein remains to be determined. Here, we examine this question by identifying parts of Hox proteins necessary for Hox function in different tissues. Available genetic markers allow the regulatory effects of two Hox proteins, Abdominal-A (AbdA) and Ultrabithorax (Ubx), to be distinguished in the Drosophila embryonic epidermis and visceral mesoderm (VM). Chimeric Ubx/AbdA proteins were tested in both tissues and used to identify protein sequences that endow AbdA with a different target gene specificity from Ubx. We found that distinct protein sequences define AbdA, as opposed to Ubx, function in the epidermis vs. the VM. These sequences lie mostly outside the homeodomain (HD), emphasizing the importance of non-HD residues for specific Hox activities. Hox tissue specificity is therefore achieved by sensing distinct Hox protein structures in different tissues.

DWnt-4 and Wingless have distinct activities in the Drosophila dorsal epidermis

Wnt genes are often expressed in overlapping patterns, where they affect a wide array of developmental processes. To address the way in which various Wnt signals elicit distinct effects we compared the activities of two Wnt genes in Drosophila, DWnt-4, and wingless. We show that these Wnt signals produce distinct responses in cells of the dorsal embryonic epidermis. Whereas wingless acts independently of hedgehog signaling in these cells, we show that DWnt-4 requires Hh to elicit its effects. We also show that expression of Wg signal transduction components does not mimic expression of DWnt-4, suggesting that DWnt-4 signaling proceeds through a distinct pathway. The dorsal epidermis may therefore be useful in the identification of novel Wnt signaling components.

nessy, an evolutionary conserved gene controlled by Hox proteins during Drosophila embryogenesis

From a library of DNA fragments associated with Ultrabithorax protein in vivo, we have isolated nessy, a new Drosophila gene that encodes a putative transmembrane protein conserved in evolution from Caenorhabditis elegans, to human. Zygotic expression occurs transiently in mesectodermal cells at gastrulation, proceeds in mesoderm and endoderm lineages during germ band movements and becomes then restricted to anterior and posterior domains in the visceral mesoderm. The Hox proteins Ultrabithorax, Antennapedia and AbdominalA are likely acting simultaneously to repress nessy in the other parts of the visceral mesoderm.

Antagonist activity of DWnt-4 and wingless in the Drosophila embryonic ventral ectoderm and in heterologous Xenopus assays

Wnt genes encode secreted signalling molecules involved in a number of basic developmental processes. In Drosophila, wingless and DWnt-4 are two physically clustered Wnt genes, which are transcribed in overlapping patterns during embryogenesis and, in several instances, are controlled by the same regulatory molecules. To address the question of the functional relationship of wingless and DWnt-4, we analysed how embryonic cells respond when they are exposed, simultaneously or not, to the encoded Wnt signals. We show that DWnt-4 has the capacity to antagonise Wingless signalling both in the Drosophila ventral epidermis and in a heterologous system, the Xenopus embryo. We provide evidence that DWnt-4 inhibits the Wingless/Wnt-1 signalling pathway upstream of the activation of transcriptional targets. This is the first report that antagonising Wnt signals exist in Drosophila.

The Drosophila modifier of variegation modulo gene product binds specific RNA sequences at the nucleolus and interacts with DNA and chromatin in a phosphorylation-dependent manner

modulo belongs to the modifier of Position Effect Variegation class of Drosophila genes, suggesting a role for its product in regulating chromatin structure. Genetics assigned a second function to the gene, in protein synthesis capacity. Bifunctionality is consistent with protein localization in two distinct subnuclear compartments, chromatin and nucleolus, and with its organization in modules potentially involved in DNA and RNA binding. In this study, we examine nucleic acid interactions established by Modulo at nucleolus and chromatin and the mechanism that controls the distribution and balances the function of the protein in the two compartments. Structure/function analysis and oligomer selection/amplification experiments indicate that, in vitro, two basic terminal domains independently contact DNA without sequence specificity, whereas a central RNA Recognition Motif (RRM)-containing domain allows recognition of a novel sequence-/motif-specific RNA class. Phosphorylation moreover is shown to down-regulate DNA binding. Evidence is provided that in vivo nucleolar Modulo is highly phosphorylated and belongs to a ribonucleoprotein particle, whereas chromatin-associated protein is not modified. A functional scheme is finally proposed in which modification by phosphorylation modulates Mod subnuclear distribution and balances its function at the nucleolus and chromatin.

Doppler study of mesenteric, hepatic, and portal circulation in alcoholic cirrhosis: relationship between quantitative Doppler measurements and the severity of portal hypertension and hepatic failure

To determine the relationship between quantitative Doppler parameters of portal, hepatic, and splanchnic circulation and hepatic venous pressure gradient (HVPG), variceal size, and Child-Pugh class in patients with alcoholic cirrhosis, we studied forty patients with proved alcoholic cirrhosis who underwent Doppler ultrasonography, hepatic vein catheterization, and esophagoscopy. The following Doppler parameters were recorded: time-averaged mean blood velocity, volume flow of the main portal vein flow, and resistance index (RI) of the hepatic and of the superior mesenteric artery. Doppler findings were compared with HVPG, presence and size of esophageal varices, and Child-Pugh class. There was a significant inverse correlation between portal velocity and HVPG (r = -.69), as well as between portal vein flow and HVPG (r = -.58). No correlation was found between RI in the hepatic artery or superior mesenteric artery and HVPG. No correlation was found between portal vein measurements and presence and size of varices. Severe liver failure was associated with lower portal velocity and flow. In patients with alcoholic cirrhosis, only portal vein blood velocity and flow, but neither hepatic nor mesenteric artery RI, are correlated to the severity of portal hypertension and to the severity of liver failure.

Dynamics of the sub-nuclear distribution of Modulo and the regulation of position-effect variegation by nucleolus in Drosophila

modulo belongs to the class of Drosophila genes named ‘suppressor of position-effect variegation’, suggesting the involvement of the encoded protein in chromatin compaction/relaxation processes. Using complementary procedures of cell fractionation, immunolocalisation on mitotic and polytene chromosomes and cross-linking/immunoprecipitation of genomic DNA targets, we have analysed the sub-nuclear distribution of Modulo. While actually associated to condensed chromatin and heterochromatin sites, the protein is also abundantly found at nucleolus. From a comparison of Modulo pattern on chromosomes of different cell types and mutant lines, we propose a model in which the nucleolus balances the Modulo protein available for chromatin compaction and PEV modification. At a molecular level, repetitive elements instead of rDNA constitute Modulo DNA targets, indicating that the protein directly contacts DNA in heterochromatin but not at the nucleolus. Consistent with a role for Modulo in nucleolus activity and protein synthesis capacity, somatic clones homozygous for a null mutation express a cell-autonomous phenotype consisting of growth alteration and short slender bristles, characteristic traits of Minute mutations, which are known to affect ribosome biogenesis. The results provide evidence suggesting that Modulo participates in distinct molecular networks in the nucleolus and heterochromatin and has distinct functions in the two compartments.

From selectors to realizators

In 1975 Antonio Garcia-Bellido proposed a framework for understanding the morphogenetic function of homeotic genes in terms of selector genes and realizator genes. Since then, much has been learnt of the molecular nature and expression patterns of the Hox selector genes. Our identification of realizator genes, and our understanding of how specific sets of realizators are activated in different segments, is still far from complete, however. Here we discuss the nature of the Hox target genes identified so far and the basis of the target specificity of Hox gene products.

Doppler study of fasting and postprandial resistance indices in the superior mesenteric artery in healthy subjects and patients with cirrhosis

PURPOSE

We assessed the resistance index (RI) in the superior mesenteric artery under fasting and postprandial conditions in healthy subjects and in patients with cirrhosis to determine whether the amount of change in the RI reflects the presence or severity of liver dysfunction.

METHODS

Fifteen subjects with normal livers and 27 patients with cirrhosis underwent Doppler sonography of the superior mesenteric artery before and after ingesting a standard meal. The RI at baseline (fasting state) and the postprandial RI were compared between the 2 groups. The fasting RIs and post postprandial RIs changes in cirrhotic patients were correlated with the severity of disease.

RESULTS

No difference was found between the baseline RIs in healthy (RI = 0.85) and cirrhotic subjects (RI = 0.84), nor was there a difference in baseline RIs between subgroups of cirrhotic patients according to the severity of liver disease. The RI decreased significantly (p < 0.05) after the meal in both the healthy (13%) and cirrhotic (8%) subjects, but the postprandial decrease was significantly less pronounced (p < 0.05) in cirrhotic patients than in healthy subjects. Among cirrhotic patients, there was no correlation between the postprandial decrease of the RI and severity of liver disease.

CONCLUSIONS

The marked decrease in the postprandial RI in the SMA in healthy subjects is generally not seen in patients with cirrhosis, and changes in the postprandial RI do not reliably predict the severity of liver dysfunction.

Drosophila Hox complex downstream targets and the function of homeotic genes

Hox complex genes are key developmental regulators highly conserved throughout evolution. The encoded proteins share a 60-amino-acid DNA-binding motif, the homeodomain, and function as transcription factors to control axial patterning. An important question concerns the nature and function of genes acting downstream of Hox proteins. This review focuses on Drosophila, as little is known about this question in other organisms. The noticeable progress gained in the field during the past few years has significantly improved our current understanding of how Hox genes control diversified morphogenesis. Here we summarise the strategies deployed to identify Hox target genes and discuss how their function contributes to pattern formation and morphogenesis. The regulation of target genes is also considered with special emphasis on the mechanisms underlying the specificity of action of Hox proteins in the whole animal.

The Drosophila teashirt homeotic protein is a DNA-binding protein and modulo, a HOM-C regulated modifier of variegation, is a likely candidate for being a direct target gene

The Drosophila teashirt (tsh) gene has an homeotic function which, in combination with HOM-C genes, determines thoracic and abdominal (trunk) identities. Analysis of TSH protein distribution during embryogenesis using a specific polyclonal antibody shows that it is nuclear. The protein is present with regional modulation in several tissues within the trunk, suggesting additional tsh functions to those already studied. We identified a candidate tsh target shared with some HOM-C genes, the modifier of variegation gene modulo (mod). The TSH zinc-finger protein recognizes in vitro two specific sites within a 5' control element of the mod gene which responds in vivo to tsh activity. TSH is therefore a DNA binding protein and might directly control mod expression.

Detection of hepatic metastases: ferumoxides-enhanced MR imaging versus unenhanced MR imaging and CT during arterial portography

PURPOSE

To prospectively compare the diagnostic accuracy of computed tomography (CT) during arterial portography (CTAP) with that of unenhanced and ferumoxides-enhanced magnetic resonance (MR) imaging at 0.5 T in the detection of hepatic metastases.

MATERIALS AND METHODS

Four pairs of radiologists independently assessed the metastatic involvement of 134 hepatic segments (31 with and 103 without metastasis) in 17 patients at unenhanced and ferumoxides-enhanced spin-echo and gradient-echo MR imaging (alone and in combination) and at CTAP. The diagnostic performance of the various imaging modalities was assessed by means of receiver operating characteristic analysis.

RESULTS

The accuracy of CTAP, unenhanced MR imaging (combined unenhanced sequences), and ferumoxides-enhanced MR imaging (combined contrast material-enhanced sequences) was 0.925, 0.908, and 0.951, respectively. Ferumoxides-enhanced MR imaging was significantly more accurate (P < .05) than unenhanced MR imaging and CTAP. When 14 segments containing cysts were excluded, the difference between ferumoxides-enhanced MR imaging and CTAP was no longer statistically significant (P = .1).

CONCLUSION

Ferumoxides-enhanced MR imaging is more accurate than unenhanced MR imaging and at least as accurate as CTAP for the detection of hepatic metastases.

[Hemostatic embolization of hepatocellular carcinoma with portal vein thrombosis complicated by hemoperitoneum]

A 59-year-old chronic drinker (120 g alcohol/day) was hospitalized for sudden increase in abdominal volume found to be caused by a hemoperitonoff resulting from ruptured hepatocellular carcinoma with thrombosis of the portal vein. Emergency arterial embolization with gelatin sponge successfully stopped intraperitoneal bleeding. No surgical treatment could be attempted due the severity of the cirrhosis. This patient survived for 4.5 month. Based on this observation and a review of the literature, it can be suggested that hemostatic embolization is an effective treatment for spontaneous hemorrhage of hepatocellular carcinoma even in cases with portal vein thrombosis.

[Value of percutaneous hepatic biopsy in the diagnosis of presumed benign tumors of the liver]

The purpose of this study was to assess the accuracy of guided hepatic biopsy (GHB) and imaging techniques for presumed benign liver tumours and to determine their impact on surgical treatment. The study was carried out retrospectively in a surgical series of 15 consecutive patients with presumed benign liver tumours. The final diagnosis was 8 cases of focal nodular hyperplasia (FNH), 6 hepatic adenomas (HA) and one association FNH-HA. No morbidity was related to guided hepatic biopsy. All FNH detected on radiologic imaging or pathological examination of the biopsy specimen were true positive diagnoses. This study demonstrates that combined results of imaging techniques and percutaneous GHB could correctly diagnose three quarters of FNH before surgery. GHB is also useful when MRI imaging is indeterminate allowing a conservative approach for undiagnosed FNH.

wingless and DWnt4, 2 Drosophila Wnt genes, have related expression, regulation and function during the embryonic development

The multigenic Wnt family encode secreted signalling molecules with important regulatory functions in various developmental processes. This paper reports an analysis of the relationships, in terms of structure, expression and function, that exist between the Drosophila genes wingless, the orthologue of the mammalian Wnt1 proto-oncogene, and DWnt4, a new member of the Wnt family. The 2 genes are physically clustered, are transcribed in overlapping embryonic territories under the control of the same regulatory molecules. Co-expression and co-regulation suggest first, that the close physical linkage results from the sharing of cis-control elements and second, that the 2 Wnt signals cooperate in developmental patterning events. Antisense RNA experiments revealed that signalling by DWnt4 is essential for cells from the anterior compartment of each parasegment to adopt a denticled fate. We propose that wingless and DWnt4 achieve opposite, but complementary functions in intrasegmental cell patterning of the embryonic ectoderm.

Role of CT in the acute nontraumatic abdomen

The diagnostic workup of the acute abdomen always begins with a precise clinical history, a complete physical examination, and careful reading of plain films. Commonly performed additional imaging studies include contrast examination and, more recently, ultrasound. CT offers the advantage of allowing a comprehensive diagnostic evaluation of both solid and hollow viscera in neoplastic as well as in inflammatory and vascular disorders.

Genetic and molecular analysis of terminal deletions of chromosome 3R of Drosophila melanogaster

Terminal deletions of chromosome 3R are induced at a high frequency (3.2 x 10(-3)) by irradiating 45-4 Drosophila melanogaster females with a low dose of X-rays. The 45-4 line carries a white transgene inserted at 16 kb from the terminus and is homozygous for the mu-2 mutation, a gene involved in the repair of double-strand DNA breaks. Four of the 51 recovered deleted strains have lost modulo, the distalmost essential gene on chromosome 3R. Breakpoints of 22 deletions have been localised in a single hybridisation step, using pulsed-field gel electrophoresis to separate genomic DNA fragments obtained from digestion with a rare-cutter restriction enzyme. Breaks do not occur at random, but are rather clustered in three susceptible chromosomal domains. Backcross experiments resulting in transheterozygous (deleted chromosome/45-4) animals indicate that the activity of the white transgene is enhanced when the DNA break has occurred proximal to a critical position. This suggests that homologous chromosomal pairing distal to the critical position results in the definition of a more compact chromatin structure and, due to position effect, in the silencing of white.

DWnt-4, a novel Drosophila Wnt gene acts downstream of homeotic complex genes in the visceral mesoderm

Wnt genes encode putative cell signalling proteins which play crucial roles during development. From a library of DNA fragments associated, in vivo, with Ultrabithorax proteins, we isolated a novel Drosophila Wnt gene, DWnt-4. Neither a paralog nor an ortholog of the gene exist in the current repertoire of full-length Wnt sequences. DWnt-4 maps close (30 kb) to wingless, suggesting that the two Wnt genes derive from a duplication that occurred early in evolution, since they are significantly diverged in sequence and structure. Developmental expression of DWnt-4 partially overlaps that of wingless. The gene is transcribed following a segment polarity-like pattern in the posterior-most cells of each parasegment of the ectoderm, and at two locations that correspond to parasegments 4 and 8 of the visceral mesoderm. The control of DWnt-4 expression in the visceral mesoderm involves a network of regulatory molecules that includes Ultrabithorax and other proteins from the homeotic complex (HOM-C), as well as the TGF-beta decapentaplegic gene product.

Conservative surgery for low rectal carcinoma after high-dose radiation. Functional and oncologic results

OBJECTIVE

Using a prospective, nonrandomized study, the authors evaluated the morbidity and functional and oncologic results of conservative surgery for cancer of the lower third of the rectum after high-dose radiation.

SUMMARY BACKGROUND DATA

Colo-anal anastomosis has made sphincter conservation for low rectal carcinoma technically feasible. The limits to conservative surgery currently are oncologic rather than technical. Adjuvant radiotherapy has proven its benefit in terms of regional control, with a dose relationship.

METHODS

Since June 1990, 27 patients with distal rectal adenocarcinoma were treated by preoperative radiotherapy (40 + 20 Gy delivered with three fields) and curative surgery. The mean distance from the anal verge was 47 mm (27-57 mm), and none of the tumors were fixed (15 T2, 12 T3).

RESULTS

Mortality and morbidity were not increased by high-dose preoperative radiation. Twenty-one patients underwent conservative surgery (78%-17 total proctectomies and colo-anal anastomoses, 4 trans-anal resections). After colo-anal anastomosis, all patients with colonic pouch had good results; two patients had moderate results and one patient had poor results after straight colo-anal anastomosis. With a mean follow-up of 24 months, the authors noted 1 postoperative death, 2 disease-linked deaths, 1 controlled regional recurrence, 2 evolutive patients with pulmonary metastases, and 21 disease-free patients.

CONCLUSIONS

These first results confirm the possibility of conservative surgery for low rectal carcinoma after high-dose radiation. A prospective, randomized trial could be induced to determine the real role of the 20 Gy boost on the sphincter-saving decision.

Current CT/MRI examination of the upper intestinal tract

When properly performed, CT of the abdomen can provide valuable information about mural diseases of the alimentary tract. It can demonstrate the digestive origin of an abdominal mass, categorize a given lesion on the basis of its specific CT appearance and any associated CT findings, assess the extramural spread of gastrointestinal lesion, guide various interventional procedures (biopsy, drainage) and follow a patient's response to therapy.

The modifier of variegation modulo gene acts downstream of dorsoventral and HOM-C genes and is required for morphogenesis in Drosophila

Growing evidence involves chromatin structural flexibility in gene regulation during development. modulo is a dominant suppressor of position effect variegation, suggesting the participation of its product in the assembly of higher order chromatin structures. Here we report the patterns of modulo expression and regulation during embryogenesis, analyzed in correlation with phenotypical defects resulting from the amorphic mutation of the gene. Zygotic expression of modulo depends on the activity of genes which pattern the embryo along dorsoventral and anteroposterior axes and specify diversified morphogenesis, dorsal and the mesoderm-specific genes twist and snail direct modulo expression in the presumptive mesoderm. The homeotic genes Sex combs reduced and Ultrabithorax positively regulate the gene in the ectoderm of parasegment 2 and abdominal mesoderm, respectively, modulo mutants exhibit aberrant morphogenesis of tissues originating from those embryonic primordia which normally express the gene, but do not show defect in cell fate specification. We propose that down-stream of pattern-forming genes modulo controls, via chromatin structural changes, genes critical for the process of morphogenesis of several tissue types.

Hemodynamic changes after transcatheter arterial embolization of hepatocellular carcinomas

PURPOSE

To evaluate the serial hemodynamic changes that occur after transcatheter arterial embolization (TAE) of hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

Twenty patients with HCCs treated with TAE were evaluated with color and duplex Doppler sonography before, immediately after, and 2 days after TAE. The changes in hepatic artery and portal vein velocity and flow were evaluated.

RESULTS

The portal venous velocity and flow did not change significantly after TAE. The peak systolic velocity in the proximal hepatic artery decreased significantly (P < .01) immediately after TAE then returned to baseline values 2 days after TAE; the resistance index of the proximal hepatic artery increased significantly (P < .01) immediately after embolization, then returned to baseline values 2 days after TAE. Arterial signal in the distal hepatic artery, generally absent immediately after TAE, could be recorded 2 days after.

CONCLUSION

There is a rapidly reversible decrease in hepatic arterial flow induced by embolization, without any change in portal venous flow.

Acute abdomen of unknown origin: impact of CT on diagnosis and management

A prospective study was performed including 40 patients with an acute abdominal syndrome presenting difficulties in defining the etiology. All patients underwent an emergency computed tomographic (CT) scan. The CT scan made the syndrome's diagnosis in 95% of cases and it permitted the detection of a lesion in 57.5% of cases. The diagnostic impact of CT scan was significant (p less than 0.01). The value and the specific contribution of CT in various diseases were analyzed. CT allowed appropriate therapeutic decisions in 95% of cases where clinical examination performance was positive in only 60% of cases. We had two negative CT results leading to an inappropriate therapeutic decision; it consisted of two cases of undiagnosed appendicitis. CT modified the primary therapeutic strategy in 30% of cases and avoided seven laparotomies.

Cell lineage-specific expression of modulo, a dose-dependent modifier of variegation in Drosophila

Variegation in Drosophila is a manifest illustration of the important role played by chromatin structure in gene expression. We have isolated mutants of modulo (mod) and shown that this gene is a dominant suppressor of variegation. Null mutants are recessive lethal with a melanotic tumour phenotype. The mod protein directly binds DNA, which indicates that it may serve to anchor multimeric complexes promoting chromatin compaction and silencing. Using a specific monoclonal antibody we examined by immunocytochemistry the accumulation pattern of mod protein during embryogenesis. The protein is first detected before the blastoderm cellularization in all somatic nuclei, precisely when pericentromeric heterochromatin becomes visible. After the first cell division, mod protein is expressed in lineages of specific embryonic primordia. Based on its dominant phenotype, expression pattern and DNA-binding activity of its product, we propose that mod regulates chromatin structure and activity in specific cell lineages.

Homeotic control in Drosophila; the scabrous gene is an in vivo target of Ultrabithorax proteins

The regulatory functions of transcription factors encoded by the Ultrabithorax (Ubx) gene initiate genetic programmes essential for segmental identity and morphogenesis in Drosophila. Based on the formation of DNA-protein adducts in intact nuclei and immunoselection procedure, we cloned genomic targets for Ubx proteins. One clone was studied in detail. It encompasses parts of the last intron and exon of the scabrous (sca) gene, which encodes a secreted protein involved in cellular communication during neurogenesis. Five motifs, presenting the ATTA core, which is shared by most homeodomain binding sites, were found in the nucleotide sequence of this clone. We detail here the dynamic pattern of sca transcript accumulation during embryogenesis and show that mutation of Ubx results in the ectopic transcription of sca in the first abdominal segment. We propose that a direct interaction of Ubx with cis-acting elements in sca negatively regulates the gene. Transcript localization in several combinations of deficiencies in the Bithorax complex (BX-C) indicates that sca is downregulated by abdominal A (abdA) and Abdominal B (AbdB), and suggests that it is a common target of the three genes of BX-C.

[The posterior interparieto-peritoneal or retroperitoneal spaces. 2: Pathological x-ray computed tomographic image]

The old reports about the interparieto-peritoneal spaces described particularly the renal space and its environment. The CT scan has modified the in vivo study of the extraperitoneal spaces (E.P.S.) and brought the question of the acquired knowledge up again. An anatomical research was performed in the first part of this study which describes the structures limited between the parietalis fascia and visceral peritoneal fascias. These are the true EPS which the main element is the propria fascia of Sappey (lateroconal fascia) and its anterior and posterior renal double layers. All these lamellar structures limits spaces variably infiltrated with fat tissue: the anterior pararenal space almost virtual, the posterior pararenal space which continues till the Bogros space and the anterior and posterior renal spaces of the renal compartment which the fat continues till the bladder and accompanies the ureter. The second part of this study precises some notions of general topography which are necessary for reading abnormal CT scan images. This part reminds the aortic and arterial general organization of the vertebrates as described by Mackay. It underlines the architectural importance of the three areas so defined: parietal or peripheral, intermediate or mesoblastic genitourinary and deep lateral or digestive endoblastic. These three areas corresponds to the three vascular aortic circles. It emphasized the importance to accept in practice the notion of visceral joining fascia which has been proved in adult people. The longitudinal architecture of the compartments is precise with respect to their appartenance to one among the three arterial arches of Mackay. What the anatomy suggest, the pathology can prove. Several pathological processes are studied on CT scan: large hemorrhagic or necrotic collections in acute pancreatitis, abnormalities or diseases of renal or adrenal compartments, extraperitoneal mesenchymomas, diseases of the psoas compartment. All these observations are analysed in order to explain anatomical and CT scan findings. This study refers not only to the oldest researches which are still valuable but also to the most recent controversies. All the questions are not solved using the clearest schemes.

[The posterior interparietoperitoneal spaces or retroperitoneal spaces. 1: Normal topographic anatomy]

The posterior spaces between the wall and peritoneum or extraperitoneal spaces are located between the visceral retrocolic and retro-duodenopancreatic fascias anteriorly and the parietalis fascia posteriorly. They were studied using an anatomic and computed tomographic comparison. The propria fascia (lateroconal fascia) divided into the anterior and posterior layers of the perirenal fascia. The fascias delimitate two anterior and posterior pararenal spaces around the kidney compartment and two anterior and posterior perirenal spaces in the compartment itself. These spaces extended above and below the renal compartment from the diaphragm to the pelvis. These large spaces composed of fat and organs can assume the guided migration of pathologic processes or their spread according to the importance of the fascias barriers. They below to the genito-urinary region. The extraperitoneal spaces are related anteriorly to the retroperitoneal alimentary organs: duodenum, pancreas, ascending and descending colon depending of the alimentary region. They are related posteriorly with the abdominal wall and its own fat. The individuality and the interdependance of these three territories (alimentary, genito-urinary and abdominal wall) and their consequences for pathologic CT scan imaging will be discussed in the second part of this paper.

Modulo, a new maternally expressed Drosophila gene encodes a DNA-binding protein with distinct acidic and basic regions

We have cloned, following an immunological screen of an expression library, five cDNA clones encoding the modulo antigen, a DNA-binding protein differentially expressed during Drosophila development. In addition a series of overlapping cDNA and genomic clones were also isolated. This protein is the product of a 2.2 kb mRNA that is encoded by a single genetic locus (100F). Analysis of the complete 544 amino-acid sequence, deduced from nucleotide sequence of cDNAs, shows that the polypeptide exhibits a primary structure with distinct charged regions, a modular structure found in several eukaryotic nuclear proteins, either transcription regulators or structural factors. The amino and carboxyl termini are rich in basic residues. The first third of the sequence contains a long domain comprised almost entirely of glutamic and aspartic acid residues. A typical cAMP dependent phosphorylation site and five potential glycosylation sites have been detected in the amino-acid sequence. Computer searches fail to reveal any significant homology with known proteins. Developmental pattern of transcription of the modulo gene indicates that messengers are maternally provided to the embryos and that zygotic transcription is required during subsequent development.

Expression of laminin and of a laminin-related antigen during early development of Drosophila melanogaster

This paper reports the characterization of two immunologically related proteins that may be involved in cell adhesion during Drosophila development. These proteins, laminin chain A and a 240K component, share the epitope recognized by monoclonal antibody RD3 (Mab RD3). The two antigens show different developmental expression profiles. Laminin is detected only from 6 to 8 h of development onwards; its concentration increases during embryogenesis to reach steady-state value in larvae, pupae and adult flies. By contrast, the 240K antigen, not found in oocytes, is present before blastoderm stages; its concentration increases during gastrulation, decreases at the end of organogenesis and the antigen is no longer detected in third instar larvae. Light and electron microscope immunolocalization in imaginal discs indicates that laminin is distributed apically in the lumen and basally in the basal membrane that surrounds the nonevaginated disc. During morphogenesis laminin is detected at the basal side of the evaginating part of the disc epithelium. Immunolocalization on paraffin sections of early embryos suggests that the 240K antigen is related to (1) cell formation and polarization in association with cytoskeleton components, (2) establishment of cell-extracellular substratum interactions during the blastoderm cell sheet organization and (3) basement membrane deposition during embryonic germ cell layer segregation. This 240K protein is poorly or not glycosylated, is resistant to chondroitinase ABC and collagenase and appears therefore as a new extracellular component that might be specifically involved in early processes of morphogenesis.

Pararenal pseudotumors of the diaphragm: computed tomographic features

Two cases of diaphragmatic pseudotumors in the right posterolateral pararenal space are reported to highlight their unusual location and their confusing computed tomographic pattern.

CT features of perirectal fascia thickening after transurethral resection of prostatic adenoma

Thickening of the perirectal fascia (PRF) has been described as a CT sign of local extension of pelvic cancers. It has been observed also after radiation therapy and various pelvic surgical procedures. To demonstrate prospectively its nonspecificity, we systematically looked for such thickening before and after consecutive uneventful transurethral prostatic resections in 17 patients presenting with benign adenomas and in one patient with an unexpected prostatic carcinoma. In six patients (33%) obvious PRF thickening appeared on postoperative CT. Thus, this cause of fascial thickening must be considered when evaluating pelvic cancers.

Nuclear antigens differentially expressed during early development of Drosophila melanogaster

To obtain specific immunological probes for studying molecular events involved in gene activation during early development of Drosophila, we have produced monoclonal antibodies directed against nuclear proteins differentially expressed in time and space during embryogenesis. Twenty-five antibodies against nuclear antigens detected after the onset of zygotic genome transcription were obtained. These antigens have been distributed into six categories depending on their reactivity in dot-blot, in Western-blot and in immunofluorescence on embryo frozen section assays. Six antigens (fifth and sixth categories) are stage-, but not tissue-specific and are present in all nuclei of the embryo after the blastoderm stage. Ten antigens, the third and fourth categories, did not react on immunofluorescence and have not been characterized for a possible tissue specificity. Antigens of the first and second categories are stage- and tissue- specific. Two of them are of particular interest. The first (250 kd, recognized by the monoclonal antibody GB7) is preferentially expressed in nuclei of the ventral nerve cord, whereas the other (65 kd, recognized by the monoclonal antibody LA9) is located in nuclei of the gut and associated structures.

Cystic renal cancers: CT characteristics

The preoperative distinction between renal cyst and tumor has long been a dilemma. A cystic renal adenocarcinoma may appear similar to a largely necrotic tumor or a cancer incorporated into a cyst or arising from a cyst wall. Overall, these cystic cancers present the same preoperative features. In our series of 15 cases, the characteristic pattern on computed tomography scans included size greater than or equal to 10 cm, localized thickening of cyst walls with contrast enhancement, and irregularly and poorly defined implantation in the kidney.

Local recurrence after nephrectomy for primary renal cancer: computerized tomography recognition

We diagnosed by computerized tomography 15 local recurrences in 88 patients who had undergone nephrectomy for renal cancer, with no false positives and 1 false negative. This over-all low rate (17 per cent) probably is owing to the fact that computerized tomography scans were done in patients in good clinical condition. Local recurrence was noted in 3 of 59 asymptomatic patients and in 12 of 19 patients with local symptoms. No recurrence was noted in 10 patients with general symptoms. Thus, 20 per cent of local recurrences were asymptomatic and 80 per cent presented with local symptoms. High local recurrence rates were found in cases of transitional cell carcinoma with whole wall involvement or extension to adjacent tissues (4 of 8 patients, 50 per cent), clear cell adenocarcinoma with lymph node involvement (3 of 7 patients, 43 per cent) and partial nephrectomy (3 of 6 patients, 50 per cent). Therefore, we consider such patients to be at high risk. Our study demonstrates that computerized tomography enables earlier, accurate diagnosis of smaller local recurrence in asymptomatic patients and provides a sensitive, reliable, noninvasive, repetitive method of evaluation of clinical treatment trials. Routine followup should be reserved for high risk patients.

Sodium cromoglycate, verapamil and nicardipine antagonism to leukotriene D4 bronchoconstriction

1--The effects of nicardipine, verapamil and sodium cromoglycate (SCG) on the increase in pulmonary airway resistance(RAw) and decrease in pulmonary dynamic compliance (CDyn) induced by leukotriene D4 (LTD4) 0.5 micrograms kg-1 and acetylcholine (ACh) 3 micrograms kg-1 were investigated in anaesthetized guinea-pigs. The effects of these three agents on the contractile effects of LTD4 and ACh were tested on isolated tracheal preparations of the guinea-pig. 2--Nicardipine and verapamil (0.3 and 1 mg kg-1), as well as SCG (3 and 10 mg kg-1), partially but significantly inhibited the effects of LTD4 on RAw. Partial inhibition of the effect of LTD4 on CDyn was only observed with verapamil (0.3 and 1 mg kg-1). Nicardipine and verapamil had no effect on ACh-induced bronchoconstriction in vivo. 3--In concentrations higher than 10(-5) M, nicardipine and verapamil inhibited the contractile effects of LTD4 and ACh on guinea-pig isolated trachea. SCG had no effect on this preparation. 4--These results suggest that nicardipine, verapamil and SCG partially reduce the component of bronchoconstriction associated with stimulation of irritant receptors by LTD4. However, the site and mechanism of action of Ca2+-entry antagonists remain uncertain.