Mathematical modeling of Notch dynamics in Drosophila neural development

Notch signalling is a well-conserved signalling pathway that regulates cell fate through cell-cell communication. A typical feature of Notch signalling is ‘lateral inhibition’, whereby two neighbouring cells of equivalent state of differentiation acquire different cell fates. Recently, mathematical and computational approaches have addressed the Notch dynamics in Drosophila neural development. Typical examples of lateral inhibition are observed in the specification of neural stem cells in the embryo and sensory organ precursors in the thorax. In eye disc development, Notch signalling cooperates with other signalling pathways to define the evenly spaced positioning of the photoreceptor cells. The interplay between Notch and epidermal growth factor receptor signalling regulates the timing of neural stem cell differentiation in the optic lobe. In this review, we summarize the theoretical studies that have been conducted to elucidate the Notch dynamics in these systems and discuss the advantages of combining mathematical models with biological experiments.

Role for phagocytosis in the prevention of neoplastic transformation in Drosophila

Immunity is considered to be involved in the prevention of cancer. Although both humoral and cellular immune reactions may participate, underlying mechanisms have yet to be clarified. The present study was conducted to clarify this issue using a Drosophila model, in which neoplastic transformation was induced through the simultaneous inhibition of cell-cycle checkpoints and apoptosis. We first determined the location of hemocytes, blood cells of Drosophila playing a role of immune cells, in neoplasia-induced and normal larvae, but there was no significant difference between the two groups. When gene expression pattern in larval hemocytes was determined, the expression of immunity-related genes including those necessary for phagocytosis was reduced in the neoplasia model. We then asked the involvement of phagocytosis in the prevention of neoplasia examining animals where the expression of engulfment receptors instead of apoptosis was retarded. We found that the inhibition of engulfment receptor expression augmented the occurrence of neoplasia induced by a defect in cell-cycle checkpoints. This suggested a role for phagocytosis in the prevention of neoplastic transformation in Drosophila.

Dscam1 establishes the columnar units through lineage-dependent repulsion between sister neurons in the fly brain

The brain is organized morphologically and functionally into a columnar structure. According to the radial unit hypothesis, neurons from the same lineage form a radial unit that contributes to column formation. However, the molecular mechanisms that link neuronal lineage and column formation remain elusive. Here, we show that neurons from the same lineage project to different columns under control of Down syndrome cell adhesion molecule (Dscam) in the fly brain. Dscam1 is temporally expressed in newly born neuroblasts and is inherited by their daughter neurons. The transient transcription of Dscam1 in neuroblasts enables the expression of the same Dscam1 splice isoform within cells of the same lineage, causing lineage-dependent repulsion. In the absence of Dscam1 function, neurons from the same lineage project to the same column. When the splice diversity of Dscam1 is reduced, column formation is significantly compromised. Thus, Dscam1 controls column formation through lineage-dependent repulsion.

Columns are the functional and morphological unit of the brain, but how neurons assemble into this structure was unclear. Here, the authors show that Dscam gene rewires neurons that derive from the same stem cell to establish columns through the process of lineage-dependent repulsion.

Netrin Signaling Defines the Regional Border in the Drosophila Visual Center

The brain consists of distinct domains defined by sharp borders. So far, the mechanisms of compartmentalization of developing tissues include cell adhesion, cell repulsion, and cortical tension. These mechanisms are tightly related to molecular machineries at the cell membrane. However, we and others demonstrated that Slit, a chemorepellent, is required to establish the borders in the fly brain. Here, we demonstrate that Netrin, a classic guidance molecule, is also involved in the compartmental subdivision in the fly brain. In Netrin mutants, many cells are intermingled with cells from the adjacent ganglia penetrating the ganglion borders, resulting in disorganized compartmental subdivisions. How do these guidance molecules regulate the compartmentalization? Our mathematical model demonstrates that a simple combination of known guidance properties of Slit and Netrin is sufficient to explain their roles in boundary formation. Our results suggest that Netrin indeed regulates boundary formation in combination with Slit in vivo.

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Netrin regulates boundary formation in combination with Slit in the fly brain

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Dual Netrin functions as attractant and repellent explain boundary formation

Temporal patterning of neurogenesis and neural wiring in the fly visual system

During neural development, a wide variety of neurons are produced in a highly coordinated manner and form complex and highly coordinated neural circuits. Temporal patterning of neuron type specification plays very important roles in orchestrating the production and wiring of neurons. The fly visual system, which is composed of the retina and the optic lobe of the brain, is an outstanding model system to study temporal patterning and wiring of the nervous system. All of the components of the fly visual system are topographically connected, and each ommatidial unit in the retina corresponds to a columnar unit in the optic lobe. In the retina, the wave of differentiation follows the morphogenetic furrow, which progresses in a posterior-to-anterior direction. At the same time, differentiation of the optic lobe also accompanies the wave of differentiation or temporally coordinated neurogenesis. Thus, temporal patterning plays important roles in establishing topographic connections throughout the fly visual system. In this article, we review how neuronal differentiation and connectivity are orchestrated in the fly visual system by temporal patterning mechanisms.

Adaptation to dietary conditions by trehalose metabolism in Drosophila

Trehalose is a non-reducing disaccharide that serves as the main sugar component of haemolymph in insects. Trehalose hydrolysis enzyme, called trehalase, is highly conserved from bacteria to humans. However, our understanding of the physiological role of trehalase remains incomplete. Here, we analyze the phenotypes of several Trehalase (Treh) loss-of-function alleles in a comparative manner in Drosophila. The previously reported mutant phenotype of Treh affecting neuroepithelial stem cell maintenance and differentiation in the optic lobe is caused by second-site alleles in addition to Treh. We further report that the survival rate of Treh null mutants is significantly influenced by dietary conditions. Treh mutant larvae are lethal not only on a low-sugar diet but also under low-protein diet conditions. A reduction in adaptation ability under poor food conditions in Treh mutants is mainly caused by the overaccumulation of trehalose rather than the loss of Treh, because the additional loss of Tps1 mitigates the lethal effect of Treh mutants. These results demonstrate that proper trehalose metabolism plays a critical role in adaptation under various environmental conditions.

A Combination of CRISPR/Cas9 and Standardized RNAi as a Versatile Platform for the Characterization of Gene Function

Traditional loss-of-function studies in Drosophila suffer from a number of shortcomings, including off-target effects in the case of RNA interference (RNAi) or the stochastic nature of mosaic clonal analysis. Here, we describe minimal in vivo GFP interference (miGFPi) as a versatile strategy to characterize gene function and to conduct highly stringent, cell type-specific loss-of-function experiments in Drosophila miGFPi combines CRISPR/Cas9-mediated tagging of genes at their endogenous locus with an immunotag and an exogenous 21 nucleotide RNAi effector sequence with the use of a single reagent, highly validated RNAi line targeting this sequence. We demonstrate the utility and time effectiveness of this method by characterizing the function of the Polymerase I (Pol I)-associated transcription factor Tif-1a, and the previously uncharacterized gene MESR4, in the Drosophila female germline stem cell lineage. In addition, we show that miGFPi serves as a powerful technique to functionally characterize individual isoforms of a gene. We exemplify this aspect of miGFPi by studying isoform-specific loss-of-function phenotypes of the longitudinals lacking (lola) gene in neural stem cells. Altogether, the miGFPi strategy constitutes a generalized loss-of-function approach that is amenable to the study of the function of all genes in the genome in a stringent and highly time effective manner.

Wnt Signaling Specifies Anteroposterior Progenitor Zone Identity in the Drosophila Visual Center

During brain development, various types of neuronal populations are produced from different progenitor pools to produce neuronal diversity that is sufficient to establish functional neuronal circuits. However, the molecular mechanisms that specify the identity of each progenitor pool remain obscure. Here, we show that Wnt signaling is essential for the specification of the identity of posterior progenitor pools in the Drosophila visual center. In the medulla, the largest component of the visual center, different types of neurons are produced from two progenitor pools: the outer proliferation center (OPC) and glial precursor cells (GPCs; also known as tips of the OPC). We found that OPC-type neurons are produced from the GPCs at the expense of GPC-type neurons when Wnt signaling is suppressed in the GPCs. In contrast, GPC-type neurons are ectopically induced when Wnt signaling is ectopically activated in the OPC. These results suggest that Wnt signaling is necessary and sufficient for the specification of the progenitor pool identity. We also found that Homothorax (Hth), which is temporally expressed in the OPC, is ectopically induced in the GPCs by suppression of Wnt signaling and that ectopic induction of Hth phenocopies the suppression of Wnt signaling in the GPCs. Thus, Wnt signaling is involved in regionalization of the fly visual center through the specification of the progenitor pool located posterior to the medulla by suppressing Hth expression.

SIGNIFICANCE STATEMENT

Brain consists of considerably diverse neurons of different origins. In mammalian brain, excitatory and inhibitory neurons derive from the dorsal and ventral telencephalon, respectively. Multiple progenitor pools also contribute to the neuronal diversity in fly brain. However, it has been unclear how differences between these progenitor pools are established. Here, we show that Wnt signaling, an evolutionarily conserved signaling, is involved in the process that establishes the differences between these progenitor pools. Because β-catenin signaling, which is under the control of Wnt ligands, specifies progenitor pool identity in the developing mammalian thalamus, Wnt signaling-mediated specification of progenitor pool identity may be conserved in insect and mammalian brains.

Temporal regulation of the generation of neuronal diversity in Drosophila

For the construction of complex neural networks, the generation of neurons and glia must be tightly regulated both spatially and temporally. One of the major issues in neural development is the generation of a large variety of neurons and glia over time from a relatively small number of neural stem cells. In Drosophila, neural stem cells, called neuroblasts (NBs), have been used as a useful model system to uncover the molecular and cellular machinery involved in the establishment of neural diversity. NBs divide asymmetrically and produce another self-renewing progenitor cell and a differentiating cell. NBs are subdivided into several types based on their location in the central nervous system. Each type of NB has specific features related to the timing of cell generation, cell cycle progression, temporal patterning for neuronal specification, and termination mechanism. In this review, we focus on the molecular mechanisms that regulate the proliferation of NBs and generate a large variety of neuronal and glia subtypes during development.

A regulatory transcriptional loop controls proliferation and differentiation in Drosophila neural stem cells

Neurogenesis is initiated by a set of basic Helix-Loop-Helix (bHLH) transcription factors that specify neural progenitors and allow them to generate neurons in multiple rounds of asymmetric cell division. The Drosophila Daughterless (Da) protein and its mammalian counterparts (E12/E47) act as heterodimerization factors for proneural genes and are therefore critically required for neurogenesis. Here, we demonstrate that Da can also be an inhibitor of the neural progenitor fate whose absence leads to stem cell overproliferation and tumor formation. We explain this paradox by demonstrating that Da induces the differentiation factor Prospero (Pros) whose asymmetric segregation is essential for differentiation in one of the two daughter cells. Da co-operates with the bHLH transcription factor Asense, whereas the other proneural genes are dispensible. After mitosis, Pros terminates Asense expression in one of the two daughter cells. In da mutants, pros is not expressed, leading to the formation of lethal transplantable brain tumors. Our results define a transcriptional feedback loop that regulates the balance between self-renewal and differentiation in Drosophila optic lobe neuroblasts. They indicate that initiation of a neural differentiation program in stem cells is essential to prevent tumorigenesis.

Phase III randomised controlled trial of neoadjuvant chemotherapy plus radical surgery vs radical surgery alone for stages IB2, IIA2, and IIB cervical cancer: a Japan Clinical Oncology Group trial (JCOG 0102)

Background:

A phase III trial was conducted to determine whether neoadjuvant chemotherapy (NACT) before radical surgery (RS) improves overall survival.

Methods:

Patients with stage IB2, IIA2, or IIB squamous cell carcinoma of the uterine cervix were randomly assigned to receive either BOMP (bleomycin 7 mg days 1–5, vincristine 0.7 mg m⁻² day 5, mitomycin 7 mg m⁻² day 5, cisplatin 14 mg m⁻² days 1–5, every 3 weeks for 2 to 4 cycles) plus RS (NACT group) or RS alone (RS group). Patients with pathological high-risk factors received postoperative radiotherapy (RT). The primary end point was overall survival.

Results:

A total of 134 patients were randomly assigned to treatment. This study was prematurely terminated at the first planned interim analysis because overall survival in the NACT group was inferior to that in the RS group. Patients who received postoperative RT were significantly lower in the NACT group (58%) than in the RS group (80% P=0.015). The 5-year overall survival was 70.0% in the NACT group and 74.4% in the RS group (P=0.85).

Conclusion:

Neoadjuvant chemotherapy with BOMP regimen before RS did not improve overall survival, but reduced the number of patients who received postoperative RT.

Fat/Hippo pathway regulates the progress of neural differentiation signaling in the Drosophila optic lobe

A large number of neural and glial cell species differentiate from neuronal precursor cells during nervous system development. Two types of Drosophila optic lobe neurons, lamina and medulla neurons, are derived from the neuroepithelial (NE) cells of the outer optic anlagen. During larval development, epidermal growth factor receptor (EGFR)/Ras signaling sweeps the NE field from the medial edge and drives medulla neuroblast (NB) formation. This signal drives the transient expression of a proneural gene, lethal of scute, and we refer to its signal array as the "proneural wave," as it is the marker of the EGFR/Ras signaling front. In this study, we show that the atypical cadherin Fat and the downstream Hippo pathways regulate the transduction of EGFR/Ras signaling along the NE field and, thus, ensure the progress of NB differentiation. Fat/Hippo pathway mutation also disrupts the pattern formation of the medulla structure, which is associated with the regulation of neurogenesis. A candidate for the Fat ligand, Dachsous is expressed in the posterior optic lobe, and its mutation was observed to cause a similar phenotype as fat mutation, although in a regionally restricted manner. We also show that Dachsous functions as the ligand in this pathway and genetically interacts with Fat in the optic lobe. These findings provide new insights into the function of the Fat/Hippo pathway, which regulates the ordered progression of neurogenesis in the complex nervous system.

Coordinated sequential action of EGFR and Notch signaling pathways regulates proneural wave progression in the Drosophila optic lobe

During neurogenesis in the medulla of the Drosophila optic lobe, neuroepithelial cells are programmed to differentiate into neuroblasts at the medial edge of the developing optic lobe. The wave of differentiation progresses synchronously in a row of cells from medial to the lateral regions of the optic lobe, sweeping across the entire neuroepithelial sheet; it is preceded by the transient expression of the proneural gene lethal of scute [l(1)sc] and is thus called the proneural wave. We found that the epidermal growth factor receptor (EGFR) signaling pathway promotes proneural wave progression. EGFR signaling is activated in neuroepithelial cells and induces l(1)sc expression. EGFR activation is regulated by transient expression of Rhomboid (Rho), which is required for the maturation of the EGF ligand Spitz. Rho expression is also regulated by the EGFR signal. The transient and spatially restricted expression of Rho generates sequential activation of EGFR signaling and assures the directional progression of the differentiation wave. This study also provides new insights into the role of Notch signaling. Expression of the Notch ligand Delta is induced by EGFR, and Notch signaling prolongs the proneural state. Notch signaling activity is downregulated by its own feedback mechanism that permits cells at proneural states to subsequently develop into neuroblasts. Thus, coordinated sequential action of the EGFR and Notch signaling pathways causes the proneural wave to progress and induce neuroblast formation in a precisely ordered manner.

Recognition of pre- and postsynaptic neurons via nephrin/NEPH1 homologs is a basis for the formation of the Drosophila retinotopic map

Topographic maps, which maintain the spatial order of neurons in the order of their axonal connections, are found in many parts of the nervous system. Here, we focus on the communication between retinal axons and their postsynaptic partners, lamina neurons, in the first ganglion of the Drosophila visual system, as a model for the formation of topographic maps. Post-mitotic lamina precursor cells differentiate upon receiving Hedgehog signals delivered through newly arriving retinal axons and, before maturing to extend neurites, extend short processes toward retinal axons to create the lamina column. The lamina column provides the cellular basis for establishing stereotypic synapses between retinal axons and lamina neurons. In this study, we identified two cell-adhesion molecules: Hibris, which is expressed in post-mitotic lamina precursor cells; and Roughest, which is expressed on retinal axons. Both proteins belong to the nephrin/NEPH1 family. We provide evidence that recognition between post-mitotic lamina precursor cells and retinal axons is mediated by interactions between Hibris and Roughest. These findings revealed mechanisms by which axons of presynaptic neurons deliver signals to induce the development of postsynaptic partners at the target area. Postsynaptic partners then recognize the presynaptic axons to make ensembles, thus establishing a topographic map along the anterior/posterior axis.

Three-year cardiovascular events and disease progress in patients with peripheral arterial disease: results from the Japan Medication Therapy for Peripheral Arterial Disease (J-METHOD)

AIM

To investigate the current status of peripheral arterial disease (PAD) drug treatment in Japan, and the effects of drug treatment, risk factors, and complications on disease progress and onset of cardiovascular events in PAD patients.

METHODS

In this prospective observational cohort study, 557 PAD patients were followed up for 3 years, and the current status of PAD treatment, risk factors, and cardiovascular events were monitored.

RESULTS

Three drugs, i.e., beraprost sodium, cilostazol, and aspirin, were most frequently used. The patients who had undergone vascular reconstruction of the lower limbs before enrollment showed significant improvement in ABI. Among the patients who had not undergone vascular reconstruction before enrollment, there was a significant improvement in ABI after treatment with beraprost. During the observation period, cardiovascular deaths occurred in 35 patients (6.3%), heart diseases in 63 (11.3%), brain diseases in 39 (7.0%), and events in the lower limbs in 94 (16.9%). The factors affecting the increase of the cardiovascular events were explored by multivariate analysis (Cox regression analysis). As a result, age (75 years or older), ischemic heart disease and increase in severity on the Fontaine classification were identified as significant factors for cardiovascular deaths, whereas kidney disorders and increase in severity on the Fontaine classification were identified for heart diseases, the number of oral drugs for treating PAD was identified for brain diseases, and age (younger than 75 years), dialysis, ABI (less than 0.7) and aspirin were identified for the events in the lower limbs.

CONCLUSION

As a result of the three-year follow-up on the Japanese PAD cohort, the current status of PAD treatment, risk factors, and cardiovascular events could be identified.

Drosophila optic lobe neuroblasts triggered by a wave of proneural gene expression that is negatively regulated by JAK/STAT

Neural stem cells called neuroblasts (NBs) generate a variety of neuronal and glial cells in the central nervous system of the Drosophila embryo. These NBs, few in number, are selected from a field of neuroepithelial (NE) cells. In the optic lobe of the third instar larva, all NE cells of the outer optic anlage (OOA) develop into either NBs that generate the medulla neurons or lamina neuron precursors of the adult visual system. The number of lamina and medulla neurons must be precisely regulated because photoreceptor neurons project their axons directly to corresponding lamina or medulla neurons. Here, we show that expression of the proneural protein Lethal of scute [L(1)sc] signals the transition of NE cells to NBs in the OOA. L(1)sc expression is transient, progressing in a synchronized and ordered ;proneural wave' that sweeps toward more lateral NEs. l(1)sc expression is sufficient to induce NBs and is necessary for timely onset of NB differentiation. Thus, proneural wave precedes and induces transition of NE cells to NBs. Unpaired (Upd), the ligand for the JAK/STAT signaling pathway, is expressed in the most lateral NE cells. JAK/STAT signaling negatively regulates proneural wave progression and controls the number of NBs in the optic lobe. Our findings suggest that NBs might be balanced with the number of lamina neurons by JAK/STAT regulation of proneural wave progression, thereby providing the developmental basis for the formation of a precise topographic map in the visual center.

3-D fractal tumor growth of epithelial ovarian cancer

PURPOSE

A fractal is a shape made of parts similar to the whole. Our objective was to determine whether surface growth patterns in malignant epithelial ovarian tumors are 3-D fractal, and if the mean fractal dimension differs according to histologic types.

METHODS

After the images of photographs of 139 resected malignant epithelial ovarian tumors were digitized, the fractal dimensions of surface of solid portions were measured using 3-D fractal analysis software.

RESULTS

The mean fractal dimensions of the surface of a solid area of tumor in serous, mucinous, endometrioid, and clear cell adenocarcinoma were 2.320, 2.224, 2.229, and 2.298, respectively. Those of serous and mucinous cystadenoma of low malignant potential (LMP) were 2.398 and 2.282, respectively. These values were significantly greater than the topological dimension of a surface (= 2). The mean fractal dimensions of a solid area of tumor inside the cyst for serous, mucinous, endometrioid, and clear cell carcinoma were 2.347, 2.223, 2.228, and 2.310, respectively. The values for serous and mucinous cystadenoma of LMP were 2.398 and 2.282, respectively.

CONCLUSION

This study shows that the surface of a solid area of malignant epithelial ovarian tumors has a 3-D fractal structure, and the mean fractal dimension may differ according to histologic types.

DWnt4 regulates the dorsoventral specificity of retinal projections in the Drosophila melanogaster visual system

In Drosophila melanogaster, the axons of retinal photoreceptor cells extend to the first optic ganglion, the lamina, forming a topographic representation. Here we show that DWnt4, a secreted protein of the Wnt family, is the ventral cue for the lamina. In DWnt4 mutants, ventral retinal axons misprojected to the dorsal lamina. DWnt4 was normally expressed in the ventral half of the developing lamina and DWnt4 protein was detected along ventral retinal axons. Dfrizzled2 and dishevelled, respectively, encode a receptor and a signaling molecule required for Wnt signaling. Mutations in both genes caused DWnt4-like defects, and both genes were autonomously required in the retina, suggesting a direct role of DWnt4 in retinal axon guidance. In contrast, iroquois homeobox genes are the dorsal cues for the retina. Dorsal axons accumulated DWnt4 and misprojected to the ventral lamina in iroquois mutants; the phenotype was suppressed in iroquois Dfrizzled2 mutants, suggesting that iroquois may attenuate the competence of Dfrizzled2 to respond to DWnt4.

DPP signaling controls development of the lamina glia required for retinal axon targeting in the visual system of Drosophila

The Drosophila visual system consists of the compound eyes and the optic ganglia in the brain. Among the eight photoreceptor (R) neurons, axons from the R1-R6 neurons stop between two layers of glial cells in the lamina, the most superficial ganglion in the optic lobe. Although it has been suggested that the lamina glia serve as intermediate targets of R axons, little is known about the mechanisms by which these cells develop. We show that DPP signaling plays a key role in this process. dpp is expressed at the margin of the lamina target region, where glial precursors reside. The generation of clones mutant for Medea, the DPP signal transducer, or inhibition of DPP signaling in this region resulted in defects in R neuron projection patterns and in the lamina morphology, which was caused by defects in the differentiation of the lamina glial cells. glial cells missing/glial cells deficient (gcm; also known as glide) is expressed shortly after glia precursors start to differentiate and migrate. Its expression depends on DPP; gcm is reduced or absent in dpp mutants or Medea clones, and ectopic activation of DPP signaling induces ectopic expression of gcm and REPO. In addition, R axon projections and lamina glia development were impaired by the expression of a dominant-negative form of gcm, suggesting that gcm indeed controls the differentiation of lamina glial cells. These results suggest that DPP signaling mediates the maturation of the lamina glia required for the correct R axon projection pattern by controlling the expression of gcm.

The DNA mismatch repair gene hMSH2 is a potent coactivator of oestrogen receptor alpha

The DNA mismatch repair gene is a key regulator in the elimination of base–base mismatches and insertion/deletion loops (IDLs). Human MutS homologue 2 (hMSH2), originally identified as a human homologue of the bacterial MutS, is a tumour suppressor gene frequently mutated in hereditary nonpolyposis colorectal cancer. Hereditary nonpolyposis colorectal cancer is characterised by the early onset of colorectal cancer and the development of extracolonic cancers such as endometrial, ovarian, and urological cancers. Oestrogen receptor (ER) α and β are members of a nuclear receptor (NR) superfamily. Ligand-dependent transcription of ER is regulated by the p160 steroid receptor coactivator family, the thyroid hormone receptor-associated proteins/the vitamin D receptor-interacting proteins (TRAP/DRIP) mediator complex, and the TATA box-binding protein (TBP)-free TBP associated factor complex (TFTC) type histone acetyltransferase complex. Here, we report the interaction between ER α/β and hMSH2. Immunoprecipitation and glutathione-S-transferase pulldown assay revealed that ER α and hMSH2 interacted in a ligand-dependent manner, whereas ER β and hMSH2 interacted in a ligand-independent manner. Oestrogen receptor α/β bound to hMSH2 through the hMSH3/hMSH6 interaction domain of hMSH2. In a transient expression assay, hMSH2 potentiated the transactivation function of liganded ER α, but not that of ER β. These results suggest that hMSH2 may play an important role as a putative coactivator in ER α dependent gene expression.

Secondary cytoreductive surgery for recurrent epithelial ovarian carcinoma: proposal for patients selection

The value of secondary cytoreductive surgery (SCS) for recurrent ovarian cancer is still controversial. The aim of this study was to clarify candidates for SCS. Between January 1987 and September 2000, we performed SCS in 44 patients with recurrent ovarian cancer, according to our selection criteria, disease-free interval (DFI) >6 months, performance status <3, no apparent multiple diseases, age <75years and no progressive disease during preoperative chemotherapy, if undertaken. The variables were investigated by univariate and multivariate analyses. Of 44 patients, 26 (59.1%) achieved complete removal of all visible tumours at SCS. Secondary cytoreductive surgery outcome, complete or incomplete resection, was significantly related to overall survival (P=0.0019). As for variables determined before SCS, DFI >12 months, no liver metastasis, solitary tumour and tumour size <6 cm were independently associated with favourable overall survival after recurrence in the multivariate analysis. Patients with three or all four variables (n=31) had significantly better survival compared with the other patients (n=13) (47 vs 20 months in median survival, P<0.0001). In these patients, fairly good median survival (40 months) was obtained even in patients with incomplete resection. Secondary cytoreductive surgery had a large impact on survival of patients with recurrent ovarian cancer when they had three or all of the above-mentioned four factors at recurrence. These patients should be considered as ideal candidates for SCS.

Analysis of the expression and localisation of a LAP protein, human scribble, in the normal and neoplastic epithelium of uterine cervix

Recently, a LAP protein, scribble, was identified in Drosophila epithelia as a basolateral protein that controls the apical-basolateral polarity. Loss of scribble causes disorganisation and overgrowth of the epithelia. Scribble has a human homologue, human scribble (hScrib), which is a substrate of ubiquitin-mediated degradation by human papillomavirus E6 and the E6AP ubiquitin-protein ligase. In the present study, we revealed that hScrib localised to the basolateral regions of the epithelial cell line MDCK and human uterine cervical epithelial tissues by immunofluorescence. Human scribble colocalised rather with the adherens junction protein E-cadherin, but not with the tight junction protein ZO-1. Histochemical analysis showed a dramatic decrease in the expression of hScrib with the progression of disease from normal uterine cervical tissues to invasive cervical cancers through the precursor lesions. In contrast, the expression of hScrib was retained in the throughout epithelial layer of the HPV-negative cervical high-grade squamous intraepithelial lesions (H-SIL). Although quantitative RT–PCR revealed no significant downregulation of hScrib mRNA expression in the H-SIL, it revealed a clear downregulation in the invasive cancers. These results suggest the possibility that degradation by HPV E6 is one of the causal roles for the progressive decrease of hScrib expression during the disease progression from low-grade squamous intraepithelial lesions to H-SIL, and a cooperative role of downregulation of hScrib mRNA expression and ubiquitin-mediated degradation of hScrib by E6 and E6AP led to the complete decrease of hScrib expression during the process of carcinogenesis from H-SIL to invasive cancer. These data underscore the importance of hScrib in the construction of tissue architecture and prevention of cancer development.

Assessment of para-aortic lymph nodes by intraoperative sonography in gynecological malignancies: a preliminary report

OBJECTIVE

To investigate the usefulness of intraoperative sonography for the assessment of para-aortic lymph nodes in gynecological malignancies.

METHODS

The assessment of para-aortic lymph node swelling by computed tomography (CT), palpation during surgery and intraoperative sonography was performed in 43 women with a gynecological malignancy. The sensitivity, specificity and predictive values of each technique for assessment of node metastasis were examined in the 33 women who underwent para-aortic lymphadenectomy. For each of the three assessment techniques, the number of para-aortic lymphadenectomies that would have been performed and the number of women who would have had missed metastasis were evaluated assuming a para-aortic lymphadenectomy would be performed only when swollen nodes were detected.

RESULTS

Para-aortic nodes were assessed to be swollen by CT, palpation, and intraoperative sonography, respectively, in one, six and 10 of 43 women in total, and in one, six and nine of the 33 women who underwent para-aortic lymphadenectomy. The sensitivity and negative predictive value of intraoperative sonography were 100%, while the specificity and positive predictive value of CT were 100%. If para-aortic lymphadenectomy had been performed only when swollen nodes were detected by intraoperative sonography, the number performed would have decreased from 33 to nine without missing lymph-node metastasis.

CONCLUSION

Intraoperative sonography has potential for the assessment of para-aortic lymph nodes in gynecological malignancies.

Are smoking and chlamydial infection risk factors for CIN? Different results after adjustment for HPV DNA and antibodies

To identify the risk factors for cervical intraepithelial neoplasia (CIN), we reanalysed the data from our previous case-control study by adjusting for human papillomavirus (HPV) antibodies. Unlike our previous study based only on HPV DNA, smoking and Chlamydia trachomatis infection were revealed as significant risk factors for CIN after adjustment for HPV antibodies.

Abnormal Fhit expression is an independent poor prognostic factor for cervical cancer

We analysed the expression of the fragile histidine triad (FHIT) gene in cervical cancer to evaluate its clinical relevance in relation to human papillomavirus (HPV) infection. A total of 73 women with cervical cancer of stage Ib or more advanced (67 squamous cell carcionomas, four adenocarcinomas, two adenosquamous carcinomas) were examined for Fhit expression by immunohistochemistry. They were further analysed for the presence of HPV and its subtype. Abnormal expression of Fhit (absent or reduced Fhit expression) was observed in 52 cases (71.2%). The high-risk HPV DNAs for cervical cancer, including type 16, 18, 31, 33, 51, 52, 58, 68, were identified in 63 cases (86%). The abnormal Fhit expression was not related to the clinicopathological factors including histology, tumour stage, and HPV type. Notably, the 5-year survival of patients showing the abnormal Fhit expression was significantly poorer than those showing normal Fhit expression (64 versus 87%, P=0.035). Interestingly, the mean age of the patients with the abnormal Fhit expression was significantly less than those with the normal Fhit expression (51.6 versus 58.7 years of age, P=0.027, student's t-test). These data imply that the aberrant Fhit expression could be a poor prognostic factor independent of HPV. In the light of a high incidence of abnormal Fhit expression in younger patients and HPV as a key player in cervical carcinogenesis, abnormal Fhit expression may accelerate carcinogenesis in concert with HPV.

Analysis of E6 variants of human papillomavirus type 33, 52 and 58 in Japanese women with cervical intraepithelial neoplasia/cervical cancer in relation to their oncogenic potential

The variation of the E6 region of human papillomavirus type 16 (HPV16) is associated with a high risk for cervical carcinogenesis. To see whether the same is the case with HPV33, 52 and 58, known to have high homology with HPV16, we analyzed the E6 sequence variation of these HPVs in 107 Japanese women with cervical intraepithelial neoplasia (CIN) or invasive cervical cancer (ICC): 20 HPV33-positive, 46 HPV52-positive and 41 HPV58-positive cases. HPV33 variants were more frequently observed in CINs I/II than in CIN III/ICCs (71% (5/7) versus 15% (2/13), P=0.02). In HPV52-positive cases, a single E6 variant was detected in 98% of the cases, whereas the prototype accounted for 98% of HPV58-positive cases. In summary, the distribution of E6 variants is different among HPV types tested, suggesting a link between E6 variation and oncogenic potential being type-specific.

PTEN mutation located only outside exons 5, 6, and 7 is an independent predictor of favorable survival in endometrial carcinomas

Although the prognostic impact of PTEN mutation in endometrial carcinoma is beginning to be analyzed, the prognostic significance of mutated PTEN exons has not ever been described. Sixty-seven endometrial carcinomas were analyzed for PTEN mutations using single-strand conformation polymorphism analysis and DNA sequencing. First, survival rates were compared according to PTEN status and mutated PTEN exons. Subsequently, univariate and multivariate analyses of various favorable prognostic factors for survival were conducted. The associations between PTEN mutation and clinicopathological features were also statistically evaluated. PTEN mutations were detected in 37 of 67 (55%) specimens. Among 47 mutations, frameshifts (57%) and mutations in exon 8 (38%) were most frequent. In univariate analysis, a factor of PTEN mutation only outside exons 5-7 was associated with significantly better survival (P = 0.02), although mutation in any exon of PTEN was not (P = 0.33). Subsequent multivariate analysis revealed that factors of mutation only outside exons 5-7 of PTEN, stage I/II, and G1 were significant and independent prognostic indicators for favorable survival (P = 0.004, 0.004, and 0.0006, respectively). In the subset of advanced-stage disease, mutation only outside exons 5-7 was associated with a trend toward better survival (P = 0.13). No significant correlation was observed between PTEN mutation and estrogen-related clinicopathological features. In conclusion, we find that PTEN mutation located only outside exons 5-7 is a significant and independent positive prognostic indicator for survival. The current observation has prognostic and therapeutic implications for the management of patients with endometrial carcinoma.

Mucinous adenocarcinoma arising in a neovagina using the sigmoid colon thirty years after operation: a case report

BACKGROUND

Because of a relative rarity of the cases with an artificial vagina, the incidence of a case with malignant disease arising in the neovagina is extremely rare. A case of adenocarcinoma arising from a neovagina is presented with a review of the literature.

CASE

A neovagina was constructed using the sigmoid colon at the age of 23 for congenital agenesis of the vagina, Rokitansky-Küster-Hauser syndrome. Subsequently, the patient had regular sexual intercourse for about 20 years. At the age of 53, she came to our outpatient clinic with a complaint of vaginal bleeding, and adenocarcinoma was found at the anterior wall of the neovagina adjoining the introitus. Total resection of the neovagina and adjuvant radiotherapy was performed. The pathological diagnosis was mucinous adenocarcinoma.

CONCLUSIONS

In view of relatively low incidence of mucinous carcinoma arising in the sigmoid colon along with the ectopic localization, this case may have implications for the understanding of pathogenesis of sigmoid colon cancer.

Prevalence of endometriosis in ovarian cancer

Endometriosis may be the precursor of clear cell or endometrioid ovarian cancer. In this review, we focus on the prevalence of endometriosis in ovarian cancer and related clinical and epidemiological issues. According to 15 published reports, the rank order of the prevalence of endometriosis in each histologic type was clear cell (39.2%) > endometrioid (21.2%) > serous (3.3%) > mucinous type (3.0%). The high prevalence of endometriosis in clear cell and endometrioid types is a consistent finding in Japan and western countries. However, the incidence of the clear cell type is much higher (15-20% vs. 7-8%), and that of the endometrioid type is lower (7-16% vs. 18-26%), in Japan compared with western countries. This review is also concerned with the relationship between the presence of ovarian endometriosis and clinical features such as age, parity, menopausal status, clinical stage, and survival in ovarian cancer patients.

Ubiquitous presence of E6 and E7 transcripts in human papillomavirus-positive cervical carcinomas regardless of its type

The presence of human papillomavirus (HPV) DNA in almost all of the cervical carcinomas is one of the most compelling evidence for the viral carcinogenesis. HPVs are thought to induce cervical carcinoma most likely through the expression of E6 and E7 genes presumably by inactivating the tumor suppressor proteins, p53 and pRb, respectively. Thus far, the presence of HPV E6 and E7 transcripts have been identified only in cervical carcinoma-derived cell lines harboring type 16 or 18, and in a limited number of cervical neoplasia specimens positive for type 16, 18, 33 or 51. To see whether the expression of E6 and E7 genes is an essential finding in HPV-positive cervical carcinoma and cervical intraepithelial neoplasia (CIN), we constructed a reverse transcription-polymerase chain reaction (RT-PCR) assay using a pair of consensus primers in the E6 and E7 regions. Using the assay, E6 transcripts (full-length E6/E7 transcripts) and E7 transcripts (spliced E6/E7 transcripts, E6* mRNA) were identified in 97% (30/31) and 100% (all 31) of cervical carcinomas and in 100% (all 23) and 74% (17/23) of CINs, respectively. This assay also revealed unknown splice donor and acceptor sites of E6* mRNA of less frequent HPV types 31, 35, 52, 56, 58 and 59 based on sequence analyses of the PCR products. Thus, the present study demonstrates that E6 and E7 transcripts of HPV exist in virtually all HPV-positive cervical neoplasia specimens except for the absence of E7 transcripts in some of CINs.

Enhanced oncogenicity of human papillomavirus type 16 (HPV16) variants in Japanese population

To investigate whether HPV16 E6 variants carry an elevated risk for cervical cancer in Japanese population, we investigated the E6 sequence variation in 40 cervical intraepithelial neoplasias (CINs) I-III and 43 invasive cervical cancers (ICCs), all positive for HPV16. HPV16 E6 variants were frequently found in ICCs than in CINs (88 vs. 65%, P=0.01). The E6 D25E, a rare variant in Western countries, was most frequently observed in ICC (44%). CIN I/II lesions with HPV16 variants were less likely to regress than those with HPV16 prototype (P=0.048). The finding that HPV16 E6 variants represent a significant risk factor is common between Western and Japanese women despite the different distribution of each variant.

Balance of IgG subclasses toward human papillomavirus type 16 (HPV16) L1-capsids is a possible predictor for the regression of HPV16-positive cervical intraepithelial neoplasia

Human papillomavirus type 16 (HPV16) is known to be a major causative agent of cervical cancer. To test the hypothesis that an enhanced Th1 response favors the natural course of cervical intraepithelial neoplasia (CIN), we measured IgG subclasses toward HPV16 L1-capsids because IgG1/IgG2 balance reflects Th2 and Th1 responses, respectively. We examined IgG2/IgG1 ratios in sera from 67 anti-HPV16 L1-positive women; 18 were cytologically normal women, 29 were CIN patients, and 20 were cervical cancer patients. The IgG2 dominance (IgG2/IgG1 ratio >1) was observed in 94, 48, and 5%, respectively (p < 0.001). The regression rate of CIN lesions was significantly different between patients with and without IgG2 dominance: 83.3% (5/6) versus 16.7% (1/6), respectively (p < 0.05). These findings raise the possibility that IgG2 dominance toward HPV16 L1-capsids, i.e., Th1 dominance, may be a useful marker to predict viral clearance or the regression of HPV16-positive CIN.

Elderly Japanese women with cervical carcinoma show higher proportions of both intermediate-risk human papillomavirus types and p53 mutations

The p53 mutation has been found only in 0-6% of cervical carcinomas. In light of recent studies demonstrating that mutation of p53 gene was found in over 20% of the patients with vulvar carcinoma, a disease of elderly women and a known human papillomavirus (HPV)-related malignancy, we analysed mutation of the p53 gene in 46 women with cervical carcinomas at the age of 60 or more (mean; 71 years, range; 60-96 years). The presence of HPV and its type were analysed by polymerase chain reaction (PCR)-based assay using the consensus primers for L1 region. Mutation of the p53 gene was analysed by PCR-based single-strand conformation polymorphism and DNA sequencing technique. Point mutation of the p53 gene was detected in 5 out of 46 (11%) cervical carcinomas: 1 of 17 (6%) samples associated with high-risk HPVs (HPV 16 and HPV 18) and 4 of 27 samples (15%) with intermediate-risk HPVs (P= 0.36) whereas no mutation was found in 2 HPV negative cases. The mutated residues resided in the selective sequence known as a DNA-binding domain. The immunohistochemistry revealed the overexpression in cancer tissues positive for p53 mutation. All of the observed mutations of the p53 gene were transition type, suggesting that the mutation may be caused by endogenous mutagenesis. Although falling short of statistical significance reduces the strength of the conclusion, data presented here imply that p53 gene mutation, particularly along with intermediate-risk HPV types, may constitute one pathogenetic factor in cervical carcinoma affecting elderly women.

A possible involvement of aberrant expression of the FHIT gene in the carcinogenesis of squamous cell carcinoma of the uterine cervix

To investigate involvement of an aberrant expression of the FHIT (fragile histidine triad) gene in the process of carcinogenesis and progression in cervical carcinoma, we examined its expression by the reverse transcriptase polymerase chain reaction (RT-PCR) and cDNA sequence method in 32 cervical invasive carcinomas (25 squamous cell carcinomas and seven adeno- or adenosquamous carcinomas) and 18 of its precursor lesions [four low-grade and 14 high-grade cervical intraepithelial neoplasias (CINs)]. We also examined a link between the occurrence of the aberrant expression and human papillomavirus (HPV). We detected the aberrant FHIT transcripts in 11 of 25 (44%) cervical invasive squamous cell carcinomas and in 5 of 14 (36%) high-grade CINs (CIN 2 or 3), whereas they were not found in seven non-squamous type and four low-grade CINs (CIN 1). The alteration patterns of the FHIT gene expression in high-grade CINs were virtually similar to those found in invasive carcinomas, such that the exons 5-7 were consistently deleted associated or unassociated with loss of the exon 4 and/or 8. The incidence of the aberrant expression was not related to the presence of HPV and its type. These data indicate that the aberrant expression of the FHIT gene is observed in precursor lesions of cervical carcinoma as well as invasive carcinomas, with its incidence not increasing with advance of clinical stage. Given the squamous cell type dominant expression, the aberrant expression may play a critical role in the generation of squamous cell carcinoma of the uterine cervix, but not the consequence of the progression of the cancer.

Patients with ovarian carcinoma upstaged to stage III after systematic lymphadenctomy have similar survival to Stage I/II patients and superior survival to other Stage III patients

BACKGROUND

Patients with epithelial ovarian carcinoma upstaged from Stage I/II to Stage IIIC based on lymph node involvement are known to have poor prognoses. The authors investigated whether systematic aortic and pelvic lymphadenectomy would affect the prognoses of these patients.

METHODS

During the period 1987-1996, 103 patients in Stage I-III underwent optimal cytoreductive surgery with systematic aortic and pelvic lymphadenectomy at initial surgery. All patients except for those in Stage IA received adjuvant cisplatin-based chemotherapy after surgery. Of 67 patients with intraperitoneal tumors limited to the pelvis, 14 were upstaged to Stage III based on lymph node positivity (Group A). The authors compared the survival of Group A patients with that of 53 patients who had intraperitoneal tumors limited to the pelvis and negative lymph nodes (Group B), and also with that of 36 patients who had intraperitoneal tumors beyond the pelvis irrespective of lymph node status (Group C).

RESULTS

The 5-year survival of Group A patients in Stage III based only on lymph node positivity had fairly good survival, although it was not significantly different from that of Group B patients in Stage I/II (84% vs. 96%, P=0.107). Group A had much better 5-year survival than Group C patients who were considered to be Stage III because they had intraperitoneal tumors beyond the pelvis (84% vs. 26%, P=0.042).

CONCLUSIONS

Relatively good survival was observed for patients with intraperitoneal tumors limited to the pelvis and lymph node involvement who underwent systematic aortic and pelvic lymphadenectomy.

Direct activation of human CD8+ cytotoxic T lymphocytes by interleukin-18

Direct activation of human cytotoxic T lymphocytes (CTL) by interleukin (IL)-18 was observed in a system in which CTL effective against autologous tumor cells were generated. Peripheral blood mononuclear cells (PBMC) from tumor-bearing patients, after removal of natural killer (NK) cells, were cultured in a medium containing IL-1, -2, -4, and -6, with or without IL-18, and stimulated with autologous tumor cells. IL-18 increased the activity of the CTL and the proportion of autologous CD8+ T cells present after 28 days in the induction culture. When purified CD8+ T cells were cultured in the presence of IL-18 and IL-2 for 7 days, the CTL showed enhanced cytotoxic activity against autologous tumor cells. Moreover, a purified CD8+ T cell population, which did not exhibit any apparent cytotoxic activity against autologous tumor cells, displayed cytotoxic activity after 7-day incubation with IL-18. These results suggest that IL-18 may be useful to generate autologous CTL in humans and may thereby contribute to adoptive immunotherapy for tumors.

Types of organic solvents used in workplaces and work environment conditions with special references to reproducibility of work environment classification

A survey of solvent was conducted for 196 unit work areas in 95 plants in 1994 to 1996 in Hiroshima Prefecture, Japan. The survey had been repeated every 6 months (i.e., twice a year) during the 3-year period. Sampling and analysis of the solvent vapors were carried out after national protocols set by the regulation. Toluene was most frequently detected regardless of the type of solvent work (except for degreasing), whereas the second- and the third-most common solvents varied depending on the type of solvent works. Among chlorinated hydrocarbon solvents for degreasing, dichloromethane was most widely used. Solvent concentrations were generally low as none of the median concentrations exceeded corresponding Administrative Control Levels set by the regulation, either individually or even when the assumption of additiveness was applied. Among the 1176 cases analyzed, 80% of the unit work areas were evaluated as adequate (i.e., classified as Class I). Furthermore, about 57% stayed in Class I throughout the 3 years, suggesting that solvent exposure conditions were generally quite stable. In regulatory evaluation by classification, A-sampling was decisive in most cases, whereas the role of B-sampling was limited.

Prevalence of ovarian endometriosis in epithelial ovarian cancer

OBJECTIVE

The objective of this study was to examine the occurrence of ovarian endometriosis in epithelial ovarian cancer in Japan.

METHOD

The presence of ovarian endometriosis was determined by reviewing the sections of resected specimens in 172 epithelial ovarian cancers.

RESULTS

The incidence of ovarian endometriosis in ovarian cancer (14.5%) was higher than that in Western countries. The rank order of incidence of endometriosis in each histologic type was clear cell (40.6%)>endometrioid (23.1%)>serous (8.7%)>mucinous (2.9%). The incidence in serous type was higher when compared with that reported in Western countries. The higher incidence of endometriosis in Japan can be explained by a greater proportion of clear cell type, comprising 18.6% of all the cases and a higher incidence of endometriosis in the serous type.

CONCLUSION

The association of ovarian endometriosis with epithelial ovarian cancer was more frequently found in Japan.

Two classes of human papillomavirus type 16 E1 mutants suggest pleiotropic conformational constraints affecting E1 multimerization, E2 interaction, and interaction with cellular proteins

Random mutagenesis of human papillomavirus type 16 (HPV16) E1 was used to generate E1 missense mutants defective for interaction with either hUBC9 or 16E1-BP, two cDNAs encoding proteins that have been identified by their ability to interact with HPV16 E1 in two-hybrid assays. hUBC9, the human counterpart of Saccharomyces cerevisiae UBC9, is a ubiquitin-conjugating enzyme known to be involved in cell cycle progression. 16E1-BP encodes a protein of no known function but does contain an ATPase signature motif. Eight hUBC9 or 16E1-BP interaction-defective HPV16 E1 missense mutants were identified and characterized for origin-dependent transient DNA replication, ATPase activity, and various protein-protein interaction phenotypes. Six of these mutant E1 proteins were significantly impaired for replication. Among these, two classes of replication-defective HPV16 E1 missense mutants were observed. One class, represented by the S330R replication-defective mutant (containing an S-to-R change at position 330), remained competent for all protein-protein interactions tested, with the exception of hUBC9 association. Furthermore, this mutant, unlike the other replication-defective HPV16 E1 missense mutants, had a strong dominant negative replication phenotype in transient-replication assays. The other class, represented by five of the missense mutants, was defective for multiple protein-protein interactions, usually including, but not limited to, the interaction defect for which each mutant was originally selected. In many cases, a single missense mutation in one region of HPV16 E1 had pleiotropic effects, even upon activities thought to be associated with other domains of HPV16 E1. This suggests that E1 proteins are not modular but may instead be composed of multiple structurally and/or functionally interdependent domains.

Mapping and characterization of the interaction domains of human papillomavirus type 16 E1 and E2 proteins

The papillomavirus E1 and E2 proteins are both necessary and sufficient in vivo for efficient origin-dependent viral DNA replication. The ability of E1 and E2 to complex with each other appears to be essential for efficient viral DNA replication. In this study, we used the yeast two-hybrid system and in vitro binding assays to map the domains of the human papillomavirus type 16 (HPV16) E1 and E2 proteins required for complex formation. The amino-terminal 190-amino-acid domain of HPV16 E2 was both required and sufficient for E1 binding. The carboxyl-terminal 229 amino acids of E 1 were essential for binding E2, and the amino-terminal 143 amino acids of HPV16 E1 were dispensable. Although the ability of the E1 minimal domain (amino acids [aa] 421 to 649) to interact with E2 was strong at 4 degrees C, it was significantly reduced at temperatures above 25 degrees C. A larger domain of E1 from aa 144 to 649 bound E2 efficiently at any temperature, suggesting that aa 144 to 420 of E1 may play a role in the HPV16 E1-E2 interaction at physiological temperatures.

Assessment of metastases to aortic and pelvic lymph nodes in epithelial ovarian carcinoma. A proposal for essential sites for lymph node biopsy

BACKGROUND

In staging epithelial ovarian carcinoma, it is necessary to assess the presence of lymph node metastases. However, the essential sites of selective lymph node biopsy have yet to be determined.

METHODS

The distribution of metastatic aortic and pelvic lymph nodes was studied in 48 patients with positive lymph nodes of 110 patients with ovarian carcinoma who underwent systematic lymphadenectomy of the aortic and pelvic regions extending to the level of the renal vessels. For purpose of analysis, the lymph nodes were classified into five subgroups: the aortic lymph nodes above the inferior mesenteric artery (A1), the aortic lymph nodes below the inferior mesenteric artery (A2), the common iliac and sacral lymph nodes (P1), the internal and external iliac and obturator lymph nodes (P2), and the suprainguinal (the lowest external iliac) lymph nodes (P3).

RESULTS

The incidence of metastases to A1, A2, P1, P2, and P3 was 79%, 71%, 46%, 77%, and 40%, respectively. Provided that 2 of the 5 lymph node subgroups were selected for biopsy, the combination of A1 and P2 gave the best results in sensitivity (94% [45 of 48 patients]) and negative (95% [62 of 65 patients]) predictive value for detection of lymph node metastases.

CONCLUSIONS

These data indicate that aortic lymph nodes above the inferior mesenteric artery and the internal and external iliac and obturator lymph nodes are essential sites for selective lymph node biopsy in staging epithelial ovarian carcinoma.

Identification of the structural and functional human homolog of the yeast ubiquitin conjugating enzyme UBC9

Ubiquitin conjugating enzymes (UBCs) are a family of proteins directly involved in ubiquitination of proteins. Ubiquitination is known to be involved in control of a variety of cellular processes, including cell proliferation, through the targeting of key regulatory proteins for degradation. The ubc9 gene of the yeast Saccharomyces cerevisiae (Scubc9) is an essential gene which is required for cell cycle progression and is involved in the degradation of S phase and M phase cyclins. We have identified a human homolog of Scubc9 (termed hubc9) using the two hybrid screen for proteins that interact with the human papillomavirus type 16 E1 replication protein. The hubc9 encoded protein shares a very high degree of amino acid sequence similarity with ScUBC9 and with the homologous hus5+ gene product of Schizosaccharomyces pombe. Genetic complementation experiments in a S.cerevisiae ubc9ts mutant reveal that hUBC9 can substitute for the function of ScUBC9 required for cell cycle progression.

Targeted mutagenesis of the human papillomavirus type 16 E2 transactivation domain reveals separable transcriptional activation and DNA replication functions

The E2 gene products of papillomavirus play key roles in viral replication, both as regulators of viral transcription and as auxiliary factors that act with E1 in viral DNA replication. We have carried out a detailed structure-function analysis of conserved amino acids within the N-terminal domain of the human papillomavirus type 16 (HPV16) E2 protein. These mutants were tested for their transcriptional activation activities as well as transient DNA replication and E1 binding activities. Analysis of the stably expressed mutants revealed that the transcriptional activation and replication activities of HPV16 E2 could be dissociated. The 173A mutant was defective for the transcriptional activation function but retained wild-type DNA replication activity, whereas the E39A mutant wild-type transcriptional activation function but was defective in transient DNA replication assays. The E39A mutant was also defective for HPV16 E1 binding in vitro, suggesting that the ability of E2 protein to form a complex with E1 appears to be essential for its function as an auxiliary replication factor.

Monitoring of exposure to methylpentanes by diffusive sampling and urine analysis for alcoholic metabolites

OBJECTIVES

To investigate the possibilities of personal ambient monitoring and biological monitoring for methylpentane isomers.

METHODS

The performance of activated carbon cloth to absorb 2- and 3-methylpentane was studied by experimental vapour exposure followed by solvent extraction and gas chromatography (GC). Urine from workers and rats exposed to 2- and 3-methylpentane was analysed by GC with or without acid or enzymatic hydrolysis.

RESULTS

Carbon cloth absorbed 2- and 3-methylpentane linearly to exposures up to eight hours and to 400 ppm, and was sensitive enough to detect a 15 minute peak of exposure. The two isomers were clearly separated from hexane on a DB-1 column. For analysis of the urine, enzymatic hydrolysis was superior to acid hydrolysis. Exposure of rats to methylpentane vapours showed that 2-methyl-2-pentanol and 3-methyl-2-pentanol were excreted in urine in proportion to the dose of 2-methylpentane and 3-methylpentane, respectively. 2-Methyl derivatives of 1-, 3-, and 4-propanol, 2-methylpentane-2,4-diol, and 3-methyl-2-pentanol were minor metabolites. Analysis of urine from the exposed workers showed that 2-methyl- and 3-methyl-2-pentanol are leading urinary metabolites after exposure to the corresponding methylpentane.

CONCLUSIONS

Diffusive sampling is applicable to monitor 2- and 3-methylpentane vapours as is the case for hexane vapour. 2-Methyl-2-pentanol and 3-methyl-2-pentanol will be markers of occupational exposure to 2-methylpentane and 3-methylpentane, respectively. Also, 2-methylpentane-2,4-diol might be a marker of exposure to 2-methylpentane.

Effects of methanol on styrene metabolism among workers occupationally exposed at low concentrations

A survey was conducted in the second half of a work week on 39 male workers who were occupationally exposed to styrene in combination with methanol and methyl acetate during the production of plastic buttons. Time-weighted average exposure during an 8-h shift to styrene (Sty-A) and methyl acetate was monitored by carbon cloth-equipped personal samplers and to methanol by water-equipped ones. Urine samples were collected near the end of the shift and analyzed for mandelic (MA-U) and phenylglyoxylic acids (PhGA-U) by HPLC. Geometric mean styrene concentration was 12.4 ppm (micrograms/g) with the maximum of 46 ppm, whereas the values for methanol and methyl acetate in combination were 23.5 ppm and 229 ppm, respectively. The relationship of MA-U and PhGA-U with Sty-A was examined by linear regression analysis. The equations for the regression lines were compared with the results from a previous survey (Ikeda et al. 1983) in which workers were exposed only to styrene, and the methods employed were identical with that in the present study. The comparison showed no evidence to suggest that styrene metabolism is suppressed by coexposure to methanol and methyl acetate at low concentrations below the current occupational exposure limit of 200 ppm.