Structural basis of gRNA stabilization and mRNA recognition in trypanosomal RNA editing

In Trypanosoma brucei, the editosome, composed of RNA-editing substrate-binding complex (RESC) and RNA-editing catalytic complex (RECC), orchestrates guide RNA (gRNA)-programmed editing to recode cryptic mitochondrial transcripts into messenger RNAs (mRNAs). The mechanism of information transfer from gRNA to mRNA is unclear owing to a lack of high-resolution structures for these complexes. With cryo-electron microscopy and functional studies, we have captured gRNA-stabilizing RESC-A and gRNA-mRNA-binding RESC-B and RESC-C particles. RESC-A sequesters gRNA termini, thus promoting hairpin formation and blocking mRNA access. The conversion of RESC-A into RESC-B or -C unfolds gRNA and allows mRNA selection. The ensuing gRNA-mRNA duplex protrudes from RESC-B, likely exposing editing sites to RECC-catalyzed cleavage, uridine insertion or deletion, and ligation. Our work reveals a remodeling event facilitating gRNA-mRNA hybridization and assembly of a macromolecular substrate for the editosome's catalytic modality.

CTS tag-based methods for investigating mitochondrial RNA modification factors in Trypanosoma brucei

Unicellular parasite Trypanosoma brucei maintains an elaborate mitochondrial mRNA processing pathway including 3'-5' exonucleolytic trimming of primary precursors, 5' and 3' modifications, and, in most cases, massive U-insertion/deletion editing. Whereas the role of editing in restoring protein coding sequence is apparent, recent developments suggest that terminal modifications are equally critical for generating a stable translationally competent messenger. The enzymatic activities responsible for 5' pyrophosphate hydrolysis, 3' adenylation and uridylation, and 3'-5' decay are positively and negatively regulated by pentatricopeptide repeat-containing (PPR) proteins. These sequence-specific RNA binding factors typically contain arrays of 35-amino acid repeats each of which recognizes a single nucleotide. Here, we introduce a combinatorial CTS affinity tag, which underlies a suite of methods for PPR proteins purification, in vivo RNA binding sites mapping and sub-cellular localization studies. These approaches should be applicable to most trypanosomal RNA binding proteins.

Poly(A) binding KPAF4/5 complex stabilizes kinetoplast mRNAs in Trypanosoma brucei

In Trypanosoma brucei, mitochondrial pre-mRNAs undergo 3′-5′ exonucleolytic processing, 3′ adenylation and uridylation, 5′ pyrophosphate removal, and, often, U-insertion/deletion editing. The 3′ modifications are modulated by pentatricopeptide repeat (PPR) Kinetoplast Polyadenylation Factors (KPAFs). We have shown that KPAF3 binding to the 3′ region stabilizes properly trimmed transcripts and stimulates their A-tailing by KPAP1 poly(A) polymerase. Conversely, poly(A) binding KPAF4 shields the nascent A-tail from uridylation and decay thereby protecting pre-mRNA upon KPAF3 displacement by editing. While editing concludes in the 5′ region, KPAF1/2 dimer induces A/U-tailing to activate translation. Remarkably, 5′ end recognition and pyrophosphate hydrolysis by the PPsome complex also contribute to mRNA stabilization. Here, we demonstrate that KPAF4 functions as a heterodimer with KPAF5, a protein lacking discernable motifs. We show that KPAF5 stabilizes KPAF4 to enable poly(A) tail recognition, which likely leads to mRNA stabilization during the editing process and impedes spontaneous translational activation of partially-edited transcripts. Thus, KPAF4/5 represents a poly(A) binding element of the mitochondrial polyadenylation complex. We present evidence that RNA editing substrate binding complex bridges the 5′ end-bound PPsome and 3′ end-bound polyadenylation complexes. This interaction may enable mRNA circularization, an apparently critical element of mitochondrial mRNA stability and quality control.

Pentatricopeptide repeat poly(A) binding protein KPAF4 stabilizes mitochondrial mRNAs in Trypanosoma brucei

In Trypanosoma brucei, most mitochondrial mRNAs undergo editing, and 3′ adenylation and uridylation. The internal sequence changes and terminal extensions are coordinated: pre-editing addition of the short (A) tail protects the edited transcript against 3′-5′ degradation, while post-editing A/U-tailing renders mRNA competent for translation. Participation of a poly(A) binding protein (PABP) in coupling of editing and 3′ modification processes has been inferred, but its identity and mechanism of action remained elusive. We report identification of KPAF4, a pentatricopeptide repeat-containing PABP which sequesters the A-tail and impedes mRNA degradation. Conversely, KPAF4 inhibits uridylation of A-tailed transcripts and, therefore, premature A/U-tailing of partially-edited mRNAs. This quality check point likely prevents translation of incompletely edited mRNAs. We also find that RNA editing substrate binding complex (RESC) mediates the interaction between the 5′ end-bound pyrophosphohydrolase MERS1 and 3′ end-associated KPAF4 to enable mRNA circularization. This event appears to be critical for edited mRNA stability.

Polyadenylation stabilizes edited mitochondrial mRNAs in Trypanosoma brucei, but the involved poly(A) binding protein is unknown. Here, Mesitov et al. show that a pentatricopeptide repeat factor KPAF4 binds to A-tail and prevents exonucleolytic degradation as well as translation of incompletely edited mRNAs.

PPR polyadenylation factor defines mitochondrial mRNA identity and stability in trypanosomes

In Trypanosoma brucei, most mitochondrial mRNAs undergo internal changes by RNA editing and 3' end modifications. The temporally separated and functionally distinct modifications are manifested by adenylation prior to editing, and by post-editing extension of a short A-tail into a long A/U-heteropolymer. The A-tail stabilizes partially and fully edited mRNAs, while the A/U-tail enables mRNA binding to the ribosome. Here, we identify an essential pentatricopeptide repeat-containing RNA binding protein, kinetoplast polyadenylation factor 3 (KPAF3), and demonstrate its role in protecting pre-mRNA against degradation by the processome. We show that KPAF3 recruits KPAP1 poly(A) polymerase to the 3' terminus, thus leading to pre-mRNA stabilization, or decay depending on the occurrence and extent of editing. In vitro, KPAF3 stimulates KPAP1 activity and inhibits mRNA uridylation by RET1 TUTase. Our findings indicate that KPAF3 selectively directs pre-mRNA toward adenylation rather than uridylation, which is a default post-trimming modification characteristic of ribosomal and guide RNAs. As a quality control mechanism, KPAF3 binding ensures that mRNAs entering the editing pathway are adenylated and, therefore, competent for post-editing A/U-tailing and translational activation.

Constructive edge of uridylation-induced RNA degradation

RNA uridylation is a significant transcriptome-shaping factor in protists, fungi, metazoans, and plants. The 3' U-additions are catalyzed by terminal uridyltransferases (TUTases), a diverse group of enzymes that along with non-canonical poly(A) polymerases form a distinct group in the superfamily of DNA polymerase β-like nucleotidyl transferases. Within and across studied organisms and subcellular compartments, TUTases differ in nucleotide triphosphate selectivity, interacting partners, and RNA targets. A general premise linking RNA uridylation to 3'-5' degradation received support from several studies of small RNAs and mRNA turnover. However, recent work on kinetoplastid protists typified by Trypanosoma brucei provides evidence that RNA uridylation may play a more nuanced role in generating functional small RNAs. In this pathogen's mitochondrion, most mRNAs are internally edited by U-insertions and deletions, and subjected to 3' adenylation/uridylation; guide RNAs (gRNAs) required for editing are U-tailed. The prominent role of uridylation in mitochondrial RNA metabolism stimulated identification of the first TUTase, RNA editing TUTase 1 (RET1). Here we discuss functional studies of mitochondrial uridylation in trypanosomes that have revealed an unorthodox pathway of small RNA biogenesis. The current model accentuates physical coupling of RET1 and 3'-5' RNase II/RNB-type exonuclease DSS1 within a stable complex termed the mitochondrial 3' processome (MPsome). In the confines of this complex, RET1 initially uridylates a long precursor to activate its 3'-5' degradation by DSS1, and then uridylates trimmed guide RNA to disengage the processing complex from the mature molecule. We also discuss a potential role of antisense transcription in the MPsome pausing at a fixed distance from gRNA's 5' end. This step likely defines the mature 3' end by enabling kinetic competition between TUTase and exonuclease activities.

RNA Editing TUTase 1: structural foundation of substrate recognition, complex interactions and drug targeting

Terminal uridyltransferases (TUTases) execute 3′ RNA uridylation across protists, fungi, metazoan and plant species. Uridylation plays a particularly prominent role in RNA processing pathways of kinetoplastid protists typified by the causative agent of African sleeping sickness, Trypanosoma brucei. In mitochondria of this pathogen, most mRNAs are internally modified by U-insertion/deletion editing while guide RNAs and rRNAs are U-tailed. The founding member of TUTase family, RNA editing TUTase 1 (RET1), functions as a subunit of the 3′ processome in uridylation of gRNA precursors and mature guide RNAs. Along with KPAP1 poly(A) polymerase, RET1 also participates in mRNA translational activation. RET1 is divergent from human TUTases and is essential for parasite viability in the mammalian host and the insect vector. Given its robust in vitro activity, RET1 represents an attractive target for trypanocide development. Here, we report high-resolution crystal structures of the RET1 catalytic core alone and in complex with UTP analogs. These structures reveal a tight docking of the conserved nucleotidyl transferase bi-domain module with a RET1-specific C2H2 zinc finger and RNA recognition (RRM) domains. Furthermore, we define RET1 region required for incorporation into the 3′ processome, determinants for RNA binding, subunit oligomerization and processive UTP incorporation, and predict druggable pockets.

Antisense Transcripts Delimit Exonucleolytic Activity of the Mitochondrial 3' Processome to Generate Guide RNAs

Small, noncoding RNA biogenesis typically involves cleavage of structured precursor by RNase III-like endonucleases. However, guide RNAs (gRNAs) that direct U-insertion/deletion mRNA editing in mitochondria of trypanosomes maintain 5' triphosphate characteristic of the transcription initiation and possess a U-tail indicative of 3' processing and uridylation. Here, we identified a protein complex composed of RET1 TUTase, DSS1 3'-5' exonuclease, and three additional subunits. This complex, termed mitochondrial 3' processome (MPsome), is responsible for primary uridylation of ∼800 nt gRNA precursors, their processive degradation to a mature size of 40-60 nt, and secondary U-tail addition. Both strands of the gRNA gene are transcribed into sense and antisense precursors of similar lengths. Head-to-head hybridization of these transcripts blocks symmetrical 3'-5' degradation at a fixed distance from the double-stranded region. Together, our findings suggest a model in which gRNA is derived from the 5' extremity of a primary molecule by uridylation-induced, antisense transcription-controlled 3'-5' exonucleolytic degradation.

Losing the stem-loop structure from metazoan mitochondrial tRNAs and co-evolution of interacting factors

Conventional tRNAs have highly conserved sequences, four-armed cloverleaf secondary structures, and L-shaped tertiary structures. However, metazoan mitochondrial tRNAs contain several exceptional structures. Almost all tRNAs^Ser for AGY/N codons lack the D-arm. Furthermore, in some nematodes, no four-armed cloverleaf-type tRNAs are present: two tRNAs^Ser without the D-arm and 20 tRNAs without the T-arm are found. Previously, we showed that in nematode mitochondria, an extra elongation factor Tu (EF-Tu) has evolved to support interaction with tRNAs lacking the T-arm, which interact with C-terminal domain 3 in conventional EF-Tu. Recent mitochondrial genome analyses have suggested that in metazoan lineages other than nematodes, tRNAs without the T-arm are present. Furthermore, even more simplified tRNAs are predicted in some lineages. In this review, we discuss mitochondrial tRNAs with divergent structures, as well as protein factors, including EF-Tu, that support the function of truncated metazoan mitochondrial tRNAs.

Arabidopsis thaliana mitochondrial EF-G1 functions in two different translation steps

Translation elongation factor G (EF-G) in bacteria catalyses the translocation of transfer RNA on ribosomes in the elongation step as well as dissociation of post-termination state ribosomes into two subunits in the recycling step. In contrast, the dual functions of EF-G are exclusively divided into two different paralogues in human mitochondria, named EF-G1mt for translocation and EF-G2mt for ribosomal dissociation. Many of the two eukaryotic EF-G paralogues are phylogenetically associated with EF-G1mt and EF-G2mt groups. However, plant paralogues are associated with EF-G1mt and plastid EF-G, not with EF-G2mt. In this study, we phylogenetically and biochemically characterized Arabidopsis thaliana EF-G1mt (AtEF-G1mt) to clarify the factor responsible for the dissociation of ribosomes in plant mitochondria. We showed that eukaryotic EF-G1mts form one monophyletic group separated from bacterial EF-G and are classified into five sister groups. AtEF-G1mt is classified into a different group from its human counterpart. We also demonstrated that AtEF-G1mt catalyses both translocation and ribosomal dissociation, unlike in humans. Meanwhile, AtEF-G1mt is resistant to fusidic acid, an inhibitor of bacterial EF-G. Here, we propose that the functional division is not necessarily conserved among mitochondriate eukaryotes and also that EF-G1mt in organisms lacking EF-G2mt functions in two steps, similar to conventional bacterial EF-G.

A bacterial elongation factor G homologue exclusively functions in ribosome recycling in the spirochaete Borrelia burgdorferi

Translation elongation factor G (EF-G) in bacteria plays two distinct roles in different phases of the translation system. EF-G catalyses the translocation of tRNAs on the ribosome in the elongation step, as well as the dissociation of the post-termination state ribosome into two subunits in the recycling step. In contrast to this conventional view, it has very recently been demonstrated that the dual functions of bacterial EF-G are distributed over two different EF-G paralogues in human mitochondria. In the present study, we show that the same division of roles of EF-G is also found in bacteria. Two EF-G paralogues are found in the spirochaete Borrelia burgdorferi, EF-G1 and EF-G2. We demonstrate that EF-G1 is a translocase, while EF-G2 is an exclusive recycling factor. We further demonstrate that B. burgdorferi EF-G2 does not require GTP hydrolysis for ribosome disassembly, provided that translation initiation factor 3 (IF-3) is present in the reaction. These results indicate that two B. burgdorferi EF-G paralogues are close relatives to mitochondrial EF-G paralogues rather than the conventional bacterial EF-G, in both their phylogenetic and biochemical features.

An evolutionary 'intermediate state' of mitochondrial translation systems found in Trichinella species of parasitic nematodes: co-evolution of tRNA and EF-Tu

EF-Tu delivers aminoacyl-tRNAs to ribosomes in the translation system. However, unusual truncations found in some animal mitochondrial tRNAs seem to prevent recognition by a canonical EF-Tu. We showed previously that the chromadorean nematode has two distinct EF-Tus, one of which (EF-Tu1) binds only to T-armless aminoacyl-tRNAs and the other (EF-Tu2) binds to D-armless Ser-tRNAs. Neither of the EF-Tus can bind to canonical cloverleaf tRNAs. In this study, by analyzing the translation system of enoplean nematode Trichinella species, we address how EF-Tus and tRNAs have evolved from the canonical structures toward those of the chromadorean translation system. Trichinella mitochondria possess three types of tRNAs: cloverleaf tRNAs, which do not exist in chromadorean nematode mitochondria; T-armless tRNAs; and D-armless tRNAs. We found two mitochondrial EF-Tu species, EF-Tu1 and EF-Tu2, in Trichinella britovi. T.britovi EF-Tu2 could bind to only D-armless Ser-tRNA, as Caenorhabditis elegans EF-Tu2 does. In contrast to the case of C.elegans EF-Tu1, however, T.britovi EF-Tu1 bound to all three types of tRNA present in Trichinella mitochondria. These results suggest that Trichinella mitochondrial translation system, and particularly the tRNA-binding specificity of EF-Tu1, could be an intermediate state between the canonical system and the chromadorean nematode mitochondrial system.

A unique tRNA recognition mechanism of Caenorhabditis elegans mitochondrial EF-Tu2

Nematode mitochondria expresses two types of extremely truncated tRNAs that are specifically recognized by two distinct elongation factor Tu (EF-Tu) species named EF-Tu1 and EF-Tu2. This is unlike the canonical EF-Tu molecule that participates in the standard protein biosynthesis systems, which basically recognizes all elongator tRNAs. EF-Tu2 specifically recognizes Ser-tRNA(Ser) that lacks a D arm but has a short T arm. Our previous study led us to speculate the lack of the D arm may be essential for the tRNA recognition of EF-Tu2. However, here, we showed that the EF-Tu2 can bind to D arm-bearing Ser-tRNAs, in which the D-T arm interaction was weakened by the mutations. The ethylnitrosourea-modification interference assay showed that EF-Tu2 is unique, in that it interacts with the phosphate groups on the T stem on the side that is opposite to where canonical EF-Tu binds. The hydrolysis protection assay using several EF-Tu2 mutants then strongly suggests that seven C-terminal amino acid residues of EF-Tu2 are essential for its aminoacyl-tRNA-binding activity. Our results indicate that the formation of the nematode mitochondrial (mt) EF-Tu2/GTP/aminoacyl-tRNA ternary complex is probably supported by a unique interaction between the C-terminal extension of EF-Tu2 and the tRNA.

Increased expression of P-cadherin mRNA in the mouse peritoneum after carbon dioxide insufflation

BACKGROUND

Although systemic responses to carbon dioxide (CO(2)) pneumoperitoneum have been studied, there have been few reports of local responses within the peritoneum. We investigated the expression of mRNA for adhesion molecules involved in cell-cell interactions, including ICAM-1, VCAM-1, CD44, E-cadherin, P-cadherin, and N-cadherin, after the induction of a CO(2) pneumoperitoneum in mice.

METHODS

Mice were treated with CO(2) pneumoperitoneum (4-6 mmHg for 30 min) and then killed after 24 h, 48 h, and 72 h. The peritoneum of the abdominal wall was resected, and total RNA was extracted by the acid guanidinium thiocyanate-phenol-chloroform extraction procedure, cDNA were synthesized by reverse transcription. Expression of the mRNA for each gene was normalized to that of b-actin for semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The expression of P-cadherin mRNA was significantly increased at 48 h (p = 0.007) and returned to the control level by 72 h after CO(2) pneumoperitoneum. The expression of CD44 increased gradually, reaching a peak at 48 h and returning to the control value by 72 h after CO(2) pneumoperitoneum. Expression of ICAM-1 mRNA was not changed significantly after the application of CO(2).

CONCLUSION

The expression of P-cadherin mRNA in the peritoneum can be induced to repair injuries to mesothelial cells caused by CO(2) pneumoperitoneum.

Morphology of the murine peritoneum after pneumoperitoneum vs laparotomy

BACKGROUND

Although there have been studies of the effects of pneumoperitoneum on the peritoneal cavity, we still do not know whether the morphologic changes to the peritoneum are different for pneumoperitoneum vs laparotomy. Using scanning electron microscopy, we examined the murine peritoneum after pneumoperitoneum vs laparotomy and compared the changes.

METHODS

Forty-five mice were anesthetized with diethyl ether and divided into seven groups. Pneumoperitoneum was established at 5 mmHg for 30 min with carbon dioxide (CO(2)) (n = 9), helium (n = 9), and air (n = 9). One group underwent laparotomy for 30 min (n = 9), and a control group underwent anesthesia only (n = 3). CO(2) pneumoperitoneum was further established at 10 mmHg for 30 min (n = 3) and at 5 mmHg for 60 min (n = 3). After the procedures, the peritoneum was resected from the mesenterium of the small intestine in each animal and examined by scanning electron microscope for morphologic changes of the mesothelial cells.

RESULTS

Bulging up of the mesothelial cells was evident immediately after pneumoperitoneum, whereas detachment of the mesothelial cells was present immediately after laparotomy. Bulging up of the mesothelial cells was reduced at 24 h after CO(2) pneumoperitoneum and fully resolved at 72 h in all pneumoperitoneum groups, whereas the mesothelial cells remained detached at 72 h in the laparotomy group. Intercellular clefts were found immediately after helium pneumoperitoneum and were present at 24 h and 72 h after helium pneumoperitoneum, but they were not seen after air pneumoperitoneum and were only evident after CO(2) pneumoperitoneum at 10 mmHg. Depression of the mesothelial cell surface was observed when pneumoperitoneum lasted 60 min.

CONCLUSION

Morphologic peritoneal alterations after pneumoperitoneum differed from those after laparotomy and were influenced by the type of gas, amount of pressure, and duration of insufflation. These peritoneal changes after pneumoperitoneum may be associated with a specific intraperitoneal tumor spread after laparoscopic cancer surgery.

Hyaluronic acid secretion during carbon dioxide pneumoperitoneum and its association with port-site metastasis in a murine model

BACKGROUND

The mechanism of port-site metastasis after laparoscopic cancer surgery is unclear. This study aimed to determine whether carbon dioxide (CO2) pneumoperitoneum caused an increase in hyaluronic acid, which is secreted from mesothelial cells of the peritoneal cavity, and to assess the risk for port-site metastasis using a murine pneumoperitoneal model.

METHODS

Sandwich-binding protein assay was used to measure the concentration of hyaluronic acid in the peritoneal cavity at 6, 12, 18, 24, 48, and 72 h after CO2 pneumoperitoneum or laparotomy for 30 min. The concentrations of hyaluronic acid during pneumoperitoneum were compared among different gases (CO2, helium, air), intervals (5, 30, 60 min), and pressures (0-2, 4-6, 8-10 mmHg). To investigate the effects of exogenous hyaluronic acid, the development of port-site metastasis was examined using mouse adenocarcinoma cell-line colon 26 cells.

RESULTS

The intraperitoneal concentration of hyaluronic acid after CO2 pneumoperitoneum had increased already at 6 h, had reached the maximum level at 24 h, and had begun to decrease at 72 h. The concentration of hyaluronic acid at 24 h and 48 h in the CO2 pneumoperitoneum group was higher than that in the laparotomy group. This increase in hyaluronic acid also was found during helium and air pneumoperitoneum, and the concentration of hyaluronic acid in the peritoneal cavity was at its maximum when CO2 pneumoperitoneum lasted 30 min at 4 to 6 mmHg. The frequency of port-site metastasis was the highest when hyaluronic acid was injected during CO2 pneumoperitoneum (100%).

CONCLUSIONS

In a murine model, the intraperitoneal concentration of hyaluronic acid was significantly increased after CO2 pneumoperitoneum, and the increase was more evident than that after laparotomy. Increased hyaluronic acid during pneumoperitoneum may be associated with port-site metastasis after laparoscopic cancer surgery.

Effect of laparotomy and laparoscopy on the establishment of lung metastasis in a murine model

BACKGROUND

Laparoscopic surgery is now applied to patients with gastrointestinal cancer. In animal studies, extraperitoneal tumor growth has been significantly less after laparoscopy than after laparotomy, but whether hematogenous metastasis occurs less frequently after laparoscopy is unknown. The aim of this study was to compare the frequency and growth of lung metastasis and serum levels of IL-6 and tumor necrosis factor-alpha (TNF-alpha) in mice treated by laparotomy and in mice treated by laparoscopy.

METHODS

We used 182 male BALB/c mice. Colon 26 cancer cells (5 x 10(4)) were injected into the tail vein, and the mice were assigned to a laparotomy group (3-cm laparotomy), a laparoscopy group (carbon dioxide pneumoperitoneum at 6 to 8 mm Hg for 30 minutes), or a control group. Lung weight, number of lung metastases, and serum levels of IL-6 and TNF-alpha were measured and compared among the 3 groups.

RESULTS

The lung weight and number of metastases on the lung surface and cut section in the laparotomy group (0.44+/-0.21 g, 55.7+/-46.7, 23.0+/-19.0) were significantly larger than those in the laparoscopy group (0.32+/-0.15 g, 29.9+/- 25.5, 13.1+/-9.9) or the control group (0.28+/-0.13, 29.3+/-26.2, 11.1+/-11.1). Three hours after the procedures, the serum level of IL-6 was significantly higher in the laparotomy group (1353 +/- 790 pg/mL) than in the laparoscopy group (671+/-353 pg/mL) or the control group (333+/-341 pg/mL). The lung weight, number of lung metastases, and levels of IL-6 and TNF-alpha were not different between the laparoscopy and control groups.

CONCLUSIONS

Our results indicate that, although laparotomy accelerates tumor metastasis to the lung in this murine model, laparoscopy does not increase the frequency and growth of lung metastasis. The laparoscopic approach may suppress hematogenous metastasis to the lung because of decreased surgical stress and reduced cytokine response.

Most important lymph node information in gastric cancer: multivariate prognostic study

BACKGROUND

In gastric cancer, the level and number of lymph node metastases is useful for predicting survival, and there are several staging systems for lymph node metastasis. The aim of this study was to compare the several lymph node classifications and to clarify the most important lymph node information associated with prognosis using multivariate analysis.

METHODS

A total of 106 patients with histologically node-positive gastric cancer treated by radical gastrectomy and extended lymph node dissection (D2, D3) were studied. The level of lymph node metastasis was categorized simply as Level I nodes (perigastric, No.1-6), Level II nodes (intermediate, No.7-9), and Level III nodes (distant, No.10-16), irrespective of the tumor location. The Level II nodes included lymph nodes along the left gastric artery, common hepatic artery, and celiac trunk.

RESULTS

Overall 5-year survival rate was 51%. Univariate analysis showed that 5-year survival rate was significantly influenced by the level of positive nodes (P < .01), total number of positive nodes (P < .01), number of positive Level I nodes (P < .01), and number of positive Level II nodes (P < .01), in addition to the tumor location (P < .05), tumor size (P < .05), gross type (P < .01), and depth of wall invasion (P < .01). Of these, independent prognostic factors associated with 5-year survival rate were the number of positive Level II nodes (0-1 vs. > or =2) (62% vs. 19%, P < .01) and the depth of wall invasion (within vs. beyond muscularis) (79% vs. 43%, P < .01).

CONCLUSIONS

Among several staging systems for lymph node metastases, the number of positive Level II nodes provided the most powerful prognostic information in patients with node-positive gastric cancer. When there were two or more metastases in the Level II nodes, prognosis was poor even after D2 or D3 gastrectomy.

Cloning, overexpression and mutagenesis of cDNA encoding dihydrolipoamide succinyltransferase component of the porcine 2-oxoglutarate dehydrogenase complex

Dihydrolipoamide succinyltransferase (E2o) is the structural and catalytic core of the 2-oxoglutarate dehydrogenase (OGDH) complex. The cDNA encoding porcine E2o (PE2o) has been cloned. The PE2o cDNA spans 2547 bases encoding a presequence (68 amino-acid residues) and a mature protein (387 residues, Mr = 41 534). Recombinant porcine E2o (rPE2o) (residues 1-387), C- and N-terminal truncated PE2os, and site-directed mutant PE2os were overexpressed in Escherichia coli via the expression vector pET-11d and purified. The succinyltransferase activity of the rPE2o was about 2.2-fold higher than that of the native PE2o. Electron micrographs of the rPE2o negatively stained showed a cube-like structure very similar to that of the native PE2o. Deletion of five amino-acid residues from the C-terminus resulted in a complete loss of both enzymatic activity and formation of the cube-like structure, but the deletion of only the last two residues had no effect on either function, suggesting the important roles of the C-terminal leucine triplet (Leu383-384-385). Substitution of Ser306 with Ala, and Asp362 with Asn, Glu or Ala in the putative active site, and Leu383-384-385 with Ala or Asp abolished both functions. Substitution of His358 with Cys resulted in an 8.5-fold reduction in kcat, with little change in Km values for dihydrolipoamide and succinyl-CoA. However, self-assembly was not affected. These data indicate that Ser306, Asp362 and the Leu383-384-385 triplet are important residues in both the self-assembly and catalytic mechanism of PE2o.

Convenient murine pneumoperitoneal model for the study of laparoscopic cancer surgery

To investigate the effects of laparoscopic surgery on the progression of cancers, it is necessary to establish a reliable and economical animal model. We describe a convenient murine pneumoperitoneal model for the study of laparoscopic cancer surgery. Under anesthesia using diethyl ether, peritoneal cavity was insufflated with gas through an intravenous catheter placed in the left lower quadrant. Syringe pump was used for continuous gas insufflation, and intraperitoneal pressure was measured. Intraperitoneal pressure increased and reached 10 cm H2O when 15 mL of CO2 gas was injected, but fell to 1 cm H2O 5 min after stopping the injection. When the continuous flow was adjusted by syringe pump between 20 and 160 mL/hour, intraperitoneal pressure was easily maintained at 8 cm H2O for >60 min. We believe that this murine model for pneumoperitoneum may be useful for the study of laparoscopic cancer surgery.

Rate of detection of lymph node metastasis is correlated with the depth of submucosal invasion in early stage gastric carcinoma

BACKGROUND

Gastric carcinoma invading the submucosa is often accompanied by lymph node metastasis. However, the relation between the depth of submucosal invasion and the status of metastasis has not been investigated. The objective of this study was to clarify the relation between lymph node status and the histologic features of gastric carcinoma invading the submucosa.

METHODS

The histopathology of 118 patients who underwent gastrectomy and lymph node dissection for gastric carcinoma invading the submucosa was examined. These pT1 tumors with invasion of the submucosa were confirmed by histologic examination of the resected specimens. Tumor size, depth of submucosal invasion, histologic type, and macroscopic type were investigated in association with presence or absence of and anatomic level of lymph node metastasis.

RESULTS

Among the 118 patients, 16 (14%) had lymph node metastasis, and the status of metastasis significantly correlated with tumor size and depth of submucosal invasion. The frequency of metastasis to perigastric lymph nodes and extragastric lymph nodes was 0% and 0% for < or =1-cm tumors, 5% and 1% for 1- to 4-cm tumors, and 46% and 15% for >4-cm tumors, respectively. There was no lymph from a node metastasis in tumors with less than 300 microm of submucosal invasion. The frequency of lymph node metastasis for tumors with 300-1000 microm and >1000 microm of submucosal invasion were 19% and 14%, respectively.

CONCLUSIONS

Tumor size and depth of submucosal invasion serve as simple and useful indicators of lymph node metastasis in early stage gastric carcinoma. Optimal lymph node dissection levels are as follows: 1) local resection (D0) for lesions < or =1 cm, 2) limited lymph node dissection (D1) for 1- to 4-cm lesions, and 3) radical lymph node dissection (D2) for lesions >4 cm. When submucosal invasion of a locally resected tumor is more than 300 microm, additional gastrectomy and lymph node dissection are necessary.

Rate of detection of lymph node metastasis is correlated with the depth of submucosal invasion in early stage gastric carcinoma

BACKGROUND

Gastric carcinoma invading the submucosa is often accompanied by lymph node metastasis. However, the relation between the depth of submucosal invasion and the status of metastasis has not been investigated. The objective of this study was to clarify the relation between lymph node status and the histologic features of gastric carcinoma invading the submucosa.

METHODS

The histopathology of 118 patients who underwent gastrectomy and lymph node dissection for gastric carcinoma invading the submucosa was examined. These pT1 tumors with invasion of the submucosa were confirmed by histologic examination of the resected specimens. Tumor size, depth of submucosal invasion, histologic type, and macroscopic type were investigated in association with presence or absence of and anatomic level of lymph node metastasis.

RESULTS

Among the 118 patients, 16 (14%) had lymph node metastasis, and the status of metastasis significantly correlated with tumor size and depth of submucosal invasion. The frequency of metastasis to perigastric lymph nodes and extragastric lymph nodes was 0% and 0% for < or =1-cm tumors, 5% and 1% for 1- to 4-cm tumors, and 46% and 15% for >4-cm tumors, respectively. There was no lymph from a node metastasis in tumors with less than 300 microm of submucosal invasion. The frequency of lymph node metastasis for tumors with 300-1000 microm and >1000 microm of submucosal invasion were 19% and 14%, respectively.

CONCLUSIONS

Tumor size and depth of submucosal invasion serve as simple and useful indicators of lymph node metastasis in early stage gastric carcinoma. Optimal lymph node dissection levels are as follows: 1) local resection (D0) for lesions < or =1 cm, 2) limited lymph node dissection (D1) for 1- to 4-cm lesions, and 3) radical lymph node dissection (D2) for lesions >4 cm. When submucosal invasion of a locally resected tumor is more than 300 microm, additional gastrectomy and lymph node dissection are necessary.

Clinicopathologic study of gastric cancer based on Dukes' classification

Dukes' classification is a useful staging system in patients with colorectal cancer. The aim of this study was to present clinicopathologic characteristics and survival of patients with gastric cancer based on Dukes' classification. A total of 273 patients with gastric cancer curatively treated by radical gastrectomy and lymph node dissection (D2, D3) were studied. With the modified Dukes' classification, A includes tumors limited to the mucosa, submucosa, or muscularis propria; B includes tumors extending into the subserosa or serosa; Ca includes tumors with one to six positive lymph nodes; and Cb includes tumors with seven or more positive lymph nodes. Dukes' classification modified by the number of positive lymph nodes well correlated with the tumor size (p < 0.01), depth of wall invasion (p < 0.01), level of lymph node metastasis (p < 0.01), and degree of lymphatic permeation (p < 0.01) and venous permeation (p< 0.01). The 5-year survival rate was significantly different among Dukes' A (98%), Dukes' B (90%), Dukes' Ca (75%), and Dukes' Cb (44%) cases. The results indicate that Dukes' classification modified by the number of positive lymph nodes (Dukes' A, B, Ca, an Cb) significantly correlates with tumor progression and patient survival; and it may be a simple and useful staging system for gastric cancer.

Laparoscopic-assisted proximal gastrectomy for early gastric carcinomas

Laparoscopic-assisted proximal gastrectomy was performed in two Japanese patients with early gastric carcinomas located in the gastric cardia. The lower esophagus and upper stomach was divided under the pneumoperitoneum and resected via a minilaparotomy through an incision, 5 cm long, made in the epigastric area. The distal esophagus was anastomosed to a gastric tube made by resecting the lesser curvature of the stomach with a linear auto-stapler. Both patients recovered quickly without any postoperative complications, such as esophagitis, developing during follow-up periods of 3 and 6 months, respectively. Thus, we conclude that laparoscopic-assisted proximal gastrectomy and reconstruction with a gastric tube may be an effective method of treatment for patients with early gastric carcinomas located in the upper stomach in this era of minimally invasive surgery.

Quality of life after laparoscopy-assisted Billroth I gastrectomy

OBJECTIVE

To evaluate the quality of life of patients who had undergone laparoscopy-assisted Billroth I gastrectomy (LAG) for cure of cancer.

SUMMARY BACKGROUND DATA

In 1994, the authors reported the first case of LAG for early gastric cancer, and this approach quickly has been adopted by Japanese surgeons. However, little is known about the subjective clinical results of this less invasive surgery.

METHODS

Quality of life was estimated using the 24-item questionnaire with a scoring system of 1, 2, and 3 and was compared between 41 consecutive patients with LAG and 35 with conventional open gastrectomy. All patients underwent Billroth I gastrectomy for early gastric cancer from January 1993 to July 1997 and were alive without recurrence.

RESULTS

Patients who had undergone LAG were taking a normal diet (100%) with >66% of volume at each meal (90%), showed no decreased performance status (90%), and were satisfied with their surgical results (88%). Patients with LAG, when compared with open gastrectomy, showed significantly better results with regard to weight loss, difficulty in swallowing, heartburn and belch, early dumping syndrome, and total score. LAG was better accepted by the patients.

CONCLUSIONS

Quality of life after Billroth I gastrectomy was significantly better in patients in whom a laparoscopic technique was used than in those who underwent a conventional method. LAG is less invasive and better accepted by patients and is the procedure of choice for the treatment of early gastric cancer.

Perigastric lymph node status as a prognostic indicator in patients with gastric cancer

BACKGROUND

The extent of lymph node dissection and histological examination of dissected lymph nodes varies among countries, which leads to the erroneous nodal stage and different surgical results in gastric cancer (stage migration, 'Will Rogers effect'). The aim of this study was to clarify the prognostic significance of the number of positive perigastric lymph nodes, which could be evaluated simply after D1 gastrectomy.

METHODS

A consecutive series of 106 patients with histologically node-positive gastric cancer treated by radical gastrectomy and lymph node dissection (D2 or D3) was studied. The number of metastatic perigastric nodes (level I, nos 1-6) was examined, and its influence on the survival of patients was analysed.

RESULTS

The overall 5-year survival rate was 50.9 per cent; the 5-year survival rate was significantly decreased when positive perigastric nodes exceeded six (62 per cent for one to six nodes versus 23 per cent for seven or more nodes, P< 0.001). Tumours having one to six positive perigastric nodes compared with those having seven or more positive perigastric nodes were more likely to have a size less than 4 cm (29 per cent versus one of 30, P< 0.001), grossly localized type (45 per cent versus seven of 30, P=0.042), absence of serosal invasion (32 per cent versus none of 30, P=0.002) and metastasis limited to the perigastric lymph nodes (70 per cent versus seven of 30, P < 0.001).

CONCLUSION

The results indicate that the number of positive perigastric nodes correlates with tumour progression and patient survival. This parameter is a simple and useful prognostic indicator for node-positive gastric cancer, and is available not only for D2 and D3 gastrectomy but also for D1 gastrectomy.

Laparoscopic intervention to relieve small bowel obstruction following laparoscopic herniorrhaphy

In this report, we present two cases of small bowel obstruction after laparoscopic herniorrhaphy (LH). One case involved incarceration of the small intestine into the port site, resulting in obstruction in an 80-year-old man on the third day after LH. The other case involved a 78-year-old man with bilateral inguinal hernia and a recurrent type on one side. In this case, a small bowel obstruction occurred due to intestinal herniation through the repaired peritoneum in the pelvic floor. In both cases, the location of the obstruction was diagnosed by means of a computed tomography scan. Subsequently, the trocar incision was extended to relieve obstruction with laparotomy in the first case, and the herniated intestinal loop was extracted followed by reclosure of the defective peritoneum under laparoscopic intervention in the second case. After the second operation, the clinical course of each patient was uneventful, and they were discharged from hospital at 10 days after the second surgery. In conclusion, (a) although patients can greatly benefit from LH, it must be kept in mind that problems can occur and (b) laparoscopic surgery to relieve small bowel obstruction following LH is the preferred procedure.

[Effects of polychlorinated biphenyls on regenerating myelin of peripheral nerve in rats]

The effects of polychlorinated biphenyls (PCB) on regenerating myelin of the peripheral nerves were investigated in rats. The sciatic nerves were crushed at the mid-thigh level on the last of 32 days of oral administration of PCB. The sciatic nerves were biopsied from the crushed regions at 4, 8 and 12 weeks after crushing. The nerves were fixed in 2.5% glutaraldehyde buffered with 0.1 M sodium cacodylate and embedded in epon 812. The ultrathin sections were analysed by JEOL JEM-1210 with EDAXDX-4. The chloride which was composed of PCB was increased in myeline on 4 weeks after crushing. Freeze fracture study of myelines of sciatic nerves on 8 and 12 weeks after crushing showed an increase of intramembranous particle on 12 weeks and an increase of caveolae on 8 weeks. These results suggest that PCB may affect the plasmamembrane of shwann cell and induce the disturbance of myeline.

Abdominal wall lifting with spinal anesthesia vs pneumoperitoneum with general anesthesia for laparoscopic herniorrhaphy

BACKGROUND

Laparoscopic herniorrhaphy has generally been very successful since any postoperative inguinal pain or tension is considerably less troublesome than after other open methods. The conventional laparoscopic approach in the treatment of inguinal hernia involves the use of pneumoperitoneum and general anesthesia. Nevertheless, some complications can be encountered and the procedure is costly. We, therefore, examined the possibility of using a more practical and cost efficient method.

MATERIALS AND METHODS

Based on our findings, we propose the use of a Kirschner lifting wire as a means of separating the abdominal wall during laparoscopic herniorrhaphy. Two Kirschner wires are introduced through the subcutaneous tissue, between the umbilicus and inguinal ligament, and parallel to the inguinal ligament. Furthermore, we recommend the use of spinal anesthesia as a means by which the problems associated with general anesthesia and the potential cardiopulmonary complications of carbon dioxide insufflation, are circumvented. Fifteen cases of inguinal hernia have been treated with this new method and compared to the more conventional procedure of pneumoperitoneum under general anesthesia.

RESULTS

Visibility of the operative field when used in the inguinal region was not limited at all, and Kirschner wire is considerably less expensive. The postoperative course for the patients who were operated by the new method was uneventful.

CONCLUSIONS

Our results indicate that this new method can be useful for the treatment of inguinal hernia.

Evaluation of the cell kinetics of MNNG-treated rat gastric mucosa based on AgNOR and ODC activity

To investigate the process of carcinogenesis in gastric cancer, we studied the histological features and cell kinetics in the gastric mucosa of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-treated rats. Samples of gastric mucosa from both MNNG-treated and control rats were histologically examined by staining with nucleolar argylophilic nonhistone (AgNOR) proteins, and their ornithine decarboxylase (ODC) activity was determined every 2 months for 10 months. In 40% of the MNNG-treated rats, atrophy of the gastric mucosa was observed after 2 months, followed by adenomatous proliferation. More AgNOR-positive granules were found in the pyloric glands than in the fundic glands, and the total number of positive granules increased over time. Cancerous and hyperplastic lesions preferentially developed in the pyloric glands and showed significantly more AgNOR-positive granules than the normal mucosa. After 6 months the ODC activity in the MNNG-treated rats was significantly higher than that in the control rats. These results thus suggest that the pyloric glands have a high growth activity, while in addition, adenomatous proliferation is a characteristic pathological feature of precancerous lesions in the stomach in MNNG-treated rats.

Distribution of acetylcholinesterase activity in the rat embryonic heart with reference to HNK-1 immunoreactivity in the conduction tissue

Acetylcholinesterase (AChE) activity was topographically investigated in the presumptive cardiac conduction tissue regions visualized by HNK-1 immunoreactivity in rat embryos, and AChE-positive cells were examined with the electron microscope. On embryonic day (ED) 14.5, when HNK-1 was most intensely visualized, AChE activity could not be detected enzyme-histochemically in the conduction tissue regions, except in the ventricular trabeculae and part of the AV node. On ED 16.5, however, the AChE activity was clearly demonstrated in some parts of the developing conduction tissue. One exception was the AV node region, where an AChE-positive area was in close proximity to an area showing HNK-1 immunoreactivity but did not overlap. Furthermore, AChE activity was demonstrated predominantly in the ventricular trabeculae, including cardiac myocytes, but was rather weak in the atrium. With the electron microscope, AChE reaction products were observed predominantly intracellularly in both developing conduction tissue cells and developing ordinary myocytes, and no reactivity was found in neuronal components. From ED 18.5 until birth, both AChE activity and HNK-1 immunoreactivity faded away in the conduction tissue. Thus, transient AChE activity in the embryonic heart seems to be different from the developing adult form and may be related to a morphogenetic function in embryonic tissues, as proposed by other authors.

[Complete response in a case of unresectable gastric cancer treated by combined chemoimmunotherapy of MMC, 5-FU and OK-432]

A 68-year-old female patient with unresectable advanced gastric cancer was treated by combined administration of MMC (10 mg/month), 5-FU (200 mg/day) and OK-432 (5KE/2 weeks). Two months after starting the treatment, there was a diminution in the serum CEA level. Six months later, the CEA had decreased to the normal level, primary and metastatic sites completely disappeared and no cancer cell was confirmed by endoscopic biopsy. The patient has survived for 33 months of a state of complete response.

[Surgical treatment of gastric cancer with hepatic cirrhosis]

42 cases of gastric cancer associated with hepatic cirrhosis were reviewed retrospectively. These patients represented 2.8% of 1496 patients with gastric cancer who were treated over the 13 years period from 1980 to 1992. The male to female ratio was 3.7:1. On the basis of a detailed classification of the preoperative hepatic function into three risk groups, we have established a preoperative means of assessing surgical indication. Among the 42 patients, four patients were inoperable, and thirty-eight patients underwent gastric resection. One patient was died due to postoperative complication. In the preoperative assessment of operative risk, K-ICG was the most important factor.

Total gastrectomy for gastric cancer: 12-year data and review of the effect of performing lymphadenectomy

A total of 1,272 patients with gastric cancer were admitted to our institute for surgery during 12 years (1975-1986). Of these, 1,059 (83.4%) underwent gastrectomy. Among these, 252 (23.8%) were total gastrectomy (TG), involving 160 (63.5%) cases of cancer mainly located in the upper third of the stomach, 81 (32.1%) in the middle third and 11 (4.4%) in the lower third. Radical TG was performed in 65.9% and palliative TG in 34.1%. Roux-en-Y reconstruction was selected in 80%, jejunal interposition in 17.6% and double tract in 2.4%. The survival rate was improved by introducing extended lymph node dissection, especially in the cases of stage III & IV cancer in which a combined pancreatico-splenectomy could lead to cure when associated with lymphadenectomy. In cases of a positive serosal exposure, the 5-year survival rate was increased by extended lymphadenectomy from 21% to 46% (p < 0.02). Anastomotic leakage occurred in 4.2%. The postoperative mortality rate was 1.6%, occurring in only 4 patients.

Demonstration of primary tracheobronchial amyloidosis by 99mTc-HMDP bone SPECT

A case of primary tracheobronchial amyloidosis is reported. A 61-year-old man presented with a 2-year history of intermittent hemoptysis. Chest X-ray and CT scanning showed tracheobronchial thickening. Bronchoscopic examination revealed diffuse tracheobronchial narrowing, and tracheobronchial biopsy detected amyloid deposits. Both 99mTc-HMDP planar and SPECT images were obtained in this patient. Coronal SPECT images revealed more precisely that the activity was not in the thoracic cage but in the bilateral hilar region. Localization of the amyloid deposits could be better determined on SPECT images than on planar images.

Chronological observation in early radiation myelopathy of the cervical spinal cord: gadolinium-enhanced MRI findings in two cases

Gd-enhanced MR images of two patients with clinically and histopathologically diagnosed chronic progressive radiation myelitis (CPRM) were observed chronologically. One of them had had nasopharyngeal cancer and received radiotherapy at a dose of 100 Gy to the C1-2 level of the spinal cord. She developed CPRM 25 months after the termination of radiotherapy. The other had had malignant lymphoma originating from the tonsil and received chemoradiotherapy. The dose delivered to her cervical spinal cord was 40 Gy, and she developed CPRM 30 months later. Gd-enhanced MRI in the early phase revealed a small crescent-shaped nidus with or without a very small central nonenhanced area in both cases. Enhancement was not great. At that time, patients noticed only the inability to perceive pain and temperature or paresthsia in the opposite side. In a few months, MRI revealed a much more strongly enhanced and larger nidus with enlargement of a central nonenhanced area accompanied by long segmental cord enlargement. The patients' neurological symptoms had also progressed, with hemiparesis developing, for example.

Visualization of ultraviolet light-induced thymine dimers in DNA by immunoelectron microscopy

To see the damage of DNA due to ultraviolet-B more distinctly, immunoelectron microscopic studies using a monoclonal antibody against cyclobutane-type thymine dimers were performed. As a result, we could detect the existence of thymine dimers on human genomic DNA and pUC18 plasmid DNA visually. This technique can be useful to locate the photoproducts formed on DNA.

[Radiotherapy for vulvar cancer]

Fifteen patients who had primary vulvar cancer treated with radiotherapy as an initial treatment at Hyogo Medical Center for Adults and Hyogo Cancer Center from January 1971 to December 1990 are presented. Two patients were stage 0, one stage I, three stage II and nine stage III. Nine patients received electron irradiation with or without interstitial irradiation and intracavitary vaginal irradiation. Five patients received megavoltage X-ray irradiation using AP/PA parallel opposed fields including the pelvic nodes and perineum followed by boost irradiation of electrons, interstitial irradiation and intracavitary vaginal irradiation. The total dose delivered to the primary tumor ranged from 50 to 100 Gy (73 Gy on average). The actuarial 5-year survival rate of the patients was 43.6%. Complete regression (CR) was achieved in 60% of the patients. However, CR was not achieved in any of five patients with palpable inguinal nodes. In contrast, all the patients who had tumors of less than 2 cm in diameter achieved CR. Five of nine CR cases relapsed. First sites of failure were vagina, groin and vulvar region. Recurrence occurred more than four years after treatment in three cases. Necrosis occurred in five of nine CR cases.

Retrospective studies of synchronous double early gastric cancer

From 1984 to 1990, 922 cases of gastric cancer underwent resection in the First Department of Surgery, at Kurume University Hospital. Of these, 381 (41.3%) cases were early gastric cancer (EGC). Among these EGC, synchronous double early gastric cancer (double EGC), according to the diagnostic criteria of Moertel, was found in 49 (12.9%) cases involving 98 foci. In cases of a double EGC, the primary and secondary foci can be distinguished. Double EGC occurred more frequently in males than females (7.1:1). In the elderly, the incidence of a double EGC was higher than the incidence of a single EGC. Double EGC occurred more frequently in the lower third of the stomach than a single EGC. And a macroscopically elevated and histologically differentiated type primary focus was more frequently found in double EGC than in single EGC. Of the 49 secondary foci in the double EGC, 12 (24.5%) foci were a microcarcinoma of less than 5 mm in greatest diameter, and 48 (98%) were limited to the mucosa (m-cancer). Therefore, a preoperative detailed examination of the whole stomach by endoscopy and an intraoperative careful search under gastrotomy must be made in the remnant of the stomach in cases of distal or proximal partial gastrectomy to ensure adequate excision.

Para-aortic lymph node dissection for the treatment of advanced gastric cancer

Para-aortic lymph node (No. 16) metastasis has been accepted as a factor responsible for non-curability in gastric cancer surgery. Recently in Japan, after detailed experimental and clinical studies of the lymph flows from the stomach and/or perigastric nodes to these No. 16 nodes, it is now considered to be curable. From 5 autopsy cases, the mean number of No. 16 nodes has been determined to be 43. The frequency of positive No. 16 metastasis (No. 16(+)) was found to be 24%, occurring in 35 of 144 cases with advanced gastric cancer following R3 gastrectomy plus No. 16 dissection. The 5 year-survival rate of R3+ No. 16 dissection was 70.1% in n1(+), 49.8% in n2(+) and 24.3% in n3(+) and had better prognoses (by Kaplan-Meier statistics) than those without dissection of the No. 16 nodes. Only 37 patients in the Japanese literature have had No. 16 dissections, and were confirmed histologically to have had No. 16(+) and subsequently survived more than 5 years. The number of those surviving No. 16(+) can be expected to increase in the near future with the adoption of R3 gastrectomy plus No. 16 dissection.

SPECT demonstration of splenosis

Splenosis is defined as the heterotopic autotransplantation of splenic tissue. The main cause of splenosis is splenic rupture following abdominal trauma, in which fragments of splenic tissue are seeded throughout the peritoneal cavity. Demonstration of splenosis by scintigraphy or CT imaging has been reported, but there is no previous report of simultaneous demonstration by SPECT and CT imaging. Autotransplantation of splenic tissue in the abdominal cavity forms a solid tumor-like image on CT and is difficult to differentiate from other abdominal masses. In such cases, SPECT demonstration of splenosis is very important for identification of its exact site. A case report of splenosis is presented, in which simultaneous demonstration by SPECT and CT was performed. This was confirmed at laparotomy for gastrectomy.

[Diffusely increased uptake in the skull in normal bone scans]

Diffusely increased skull uptake (a hot skull) is often seen in patients with bone metastases and metabolic diseases. This finding is also, however, noticed in normal bone scans of aged women. To determine whether the hot skull could be considered a normal variant in elderly women and is associated to menopause, we studied 282 normal bone scans (166 women and 116 men without metabolic and hormonal disease; age range 11 to 84 yr). We divided the patients into eight age groups--ages 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, and 80-89 yrs. Measurements of skull uptake were obtained from anterior total body views using contrast-to-noise ratio (CNR). CNR for the skull was calculated using the following equation: (counts skull - counts femur)/square root of counts skull+counts femur, where the denominator signifies a measure of the noise and the numerator represents the contrast between the skull and the midfemur. Counts skull and femur are the number of average counts per one pixel recorded over the skull and midfemur, respectively. The sex dependent difference in skull uptake began to develop in the age group 30-39 yrs (p less than 0.05). The skull showed greater activity in women than in men for age groups from 30-39 to 80-89 yrs. In the age groups 50-59 and 60-69, the difference was particularly large (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[SPECT images after intravenous injection of 99mTc-DTPA in lung tumors--comparison with delayed 123I-IMP lung scintigraphy]

The aim of this study was to assess the efficacy of SPECT imaging of the thorax with 99mTc-DTPA, which accumulates at sites of increased capillary permeability and expanded extracellular space, by comparing it with delayed 123I-IMP lung scintigraphy. We have previously reported that increased uptake on delayed 123I-IMP lung scintigraphy was associated with atelectasis and inflammation. Thirteen patients with lung cancer (4 with atelectasis and 3 with pleurisy), one patient with malignant lymphoma complicated by pneumonia and pleurisy, and one patient with pneumonia were studied. 99mTc-DTPA scintigraphy was performed twice, 20-160 minutes and 2-4 hours after the intravenous administration of 370 MBq of 99mTc-DTPA. 123I-IMP scintigraphy was performed 24 hours after the intravenous injection of 111 MBq of 123I-IMP. SPECT images were obtained with both types of scintigraphy. 99mTc-DTPA scintigraphy was compared with 123I-IMP scintigraphy for its ability to detect atelectasis and pneumonia. All patients showed increased accumulation corresponding to the lesions on both 123I-IMP and 99mTc-DTPA scintigraphy. 123I-IMP scintigraphy showed a defect corresponding to the tumor with increased accumulation around the tumor, whereas 99mTc-DTPA scintigraphy showed accumulation corresponding to the tumor. Ten of 11 tumors showed accumulation of an intensity equal to that of the soft tissue of the chest wall on 20-60 min 99mTc-DTPA images. The 2-4 hr images showed that 99mTc-DTPA leaked from the periphery of the tumor toward its center. All the patients with pleurisy showed increased accumulation in effusion on 2-4 hr 99mTc-DTPA scintigraphy.(ABSTRACT TRUNCATED AT 250 WORDS)

[Lymphoscintigraphy with 99mTc-DTPA-HSA: detection of metastases to iliopelvic lymph nodes]

The purpose of this study was to evaluate 99mTc-DTPA-HSA as an iliopelvic lymphoscintigraphic agent in 5 normal volunteers and 10 patients with metastases of malignant tumors (cancer, 9; and malignant lymphoma, 1) to the iliopelvic lymph nodes. The subjects underwent intradermal injection of 185 MBq of 99mTc-DTPA-HSA into digital web spaces of the feet. Massage was applied at the injection sites for 30 sec; the subjects then walked around for 2 min. Whole-body scintigrams were obtained 5 min after injection. The whole-body scanning speed was 20 cm/min. The tracer transport was prompt. Within 15 min after injection, the tracer reached the termination of the thoracic duct in all normal volunteers. Normal whole-body images of excellent quality delineated the lymph nodes and channels almost without background radioactivity. The images of 9 patients with metastases of cancer showed clearly the following abnormal patterns: a) obstruction of lymphatic system (5/9, 55.6%); b) absence of visualization of the thoracic duct (44.4%); c) decreased uptake in lymph nodes (88.9%); d) visualization of collateral circulation (44.4%); e) tracer extravasation into more proximal soft tissue (22.2%). The image in the patient with malignant lymphoma showed increased uptake in the enlarged lymph nodes in addition to the all abnormal findings mentioned above. We concluded that 99mTc-DTPA-HSA is an excellent radiopharmaceutical for iliopelvic lymphoscintigraphy.

[Clinical results of N0 tongue cancer treated with interstitial brachytherapy and management of occult cervical node metastases]

One hundred patients with T1-2NO squamous cell carcinoma of the oral tongue were treated with interstitial brachytherapy at the Hyogo Medical Center for Adults between 1962 and 1983. These patients were followed for more than two years. The cumulative five-year survival rate was 89% in T1N0 and 66% in T2N0. The relapse-free survival rate was 88% in T1N0 and 51% in T2N0. The two-year local control rate in the primary site was 100% in T1N0 and 73% in T2N0. Cervical node metastases developed in 41% (T1N0: 33%, T2N0: 43%) of the patients. The five-year survival rate of the patients with subsequent cervical node metastases was 42%, while that of patients without subsequent cervical node metastases was 92% (p less than 0.001). Twenty-seven patients also received prophylactic neck irradiation (average dose: 33.8 Gy). In patients treated with prophylactic neck irradiation, the rate of subsequent cervical node metastases was 37% and the cumulative five-year survival rate was 62%. In the patients without prophylactic neck irradiation, these figures were 41% and 73%, respectively. There was no statistically significant difference between the two groups. Between 1984 and 1986, 28 patients with T1-2 N0 squamous cell carcinoma of the oral tongue were treated with interstitial brachytherapy. These patients were prospectively examined for the ability of chemotherapy to prevent the development of cervical node metastasis. In 13 patients treated with chemotherapy (CDDP 80 mg/m2 + PEP 6 mg/m2 x 5 days), the two-year local control rate was 90%, the incidence of cervical node metastases was 38% and the incidence of distant metastases was 15%.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical value of Gd-DTPA enhanced MRI of pulmonary and mediastinal tumors]

Gd-DTPA (Gd) enhanced Magnetic Resonance (MR) early images and delayed images of 28 patients with pulmonary or mediastinal tumors were analyzed and compared with the computed tomography scans and the plain MR images. Numbers of relative signal intensity of the tumors, secondary lesions (adjacent pneumonia or collapse) and pleural effusions were calculated and graphed on time intensity curves. Gd-enhanced MR early images were more useful than other methods in delineating viable areas from necrotic areas. However, Gd-enhanced MR delayed images better delineated margins of necrotic areas than Gd-enhanced MR early images did in some cases. In distinguishing tumors from secondary lesions, Gd-enhanced MR early images were the most useful, too. We considered Gd gradually penetrated into pleural effusions after intravenous administration, just in the same way into necrotic areas. Therefore pleural effusions showed very high intensity on Gd-enhanced MR delayed images. Time intensity curves of the tumors and pleural effusions showed characteristic patterns, but those of secondary lesions showed different patterns among the individual cases. We presumed this was due to the variances of the water and fibrous components among them.

[A case report of reversible collateral vessels between right and left coronary artery]

We report a case of reversible collateral flow between the right coronary artery (RCA) and the left coronary artery (LCA). A 55 year-old woman was admitted to our hospital because of chest oppression. Cardiac catheterization revealed 99% stenosis to seg. 1. We found good collateral vessels from LCA to RCA. We performed PTCA (Percutaneous Transluminal Coronary Angioplasty) on this lesion. PTCA was successful and this lesion improved (99%----40%). After PTCA, collateral vessels had disappeared. After one year, the patient had chest oppression on effort again. We performed cardiac catheterization and found 90% stenosis to seg. 6. So we performed PTCA on the new lesion. During balloon inflation, we found good collateral vessels from RCA to LCA (reversible collateral flow). We considered that reversible collateral flow was important for myocardial protection.

[A case of increased 123I-IMP uptake in adenocarcinoma of the lung]

It has been reported that delayed 123I-IMP lung scintigraphy shows a defect corresponding to the tumor with increased accumulation around the tumor, and that an increased accumulation is associated with atelectasis and inflammation. We presented a case of increased uptake of 123I-IMP in lung cancer. None of the other reported case of increased uptake in lung cancer, to our knowledge, occurred. A 55-year-old man had a 6 cm mass in the lower lobe of the right lung. Cytologic examination with a small curette diagnosed the case as an adenocarcinoma. The 123I-IMP scintigraphy was performed 24 hours after intravenous injection of 111 MBq of 123I-IMP. The 123I-IMP SPECT lung images showed an area of increased 123I-IMP concentration corresponding to the tumor mass. The patient's subsequent course was characterized by massive pleural effusion caused by extensive invasion to the pleura despite chemotherapy. He died about 2 months after the 123I-IMP scintigraphy. The right lung removed at necropsy confirmed that the area of high 123I-IMP concentration corresponded to the mass, which proved a poorly differentiated adenocarcinoma. One should note that there is an unusual case with high 123I-IMP uptake in lung cancer.

[Evaluation of delayed I-123 IMP lung studies in atelectatic and inflammatory diseases in comparison with Ga-67-citrate scintigraphy]

We have previously reported that increased tracer accumulation on delayed 123I-IMP scintigraphy is associated with atelectasis and inflammation. The purpose of this study was to evaluate the diagnostic values of delayed 123I-IMP lung scintigraphy, compared with gallium scintigraphy. Ten patients with atelectasis caused by lung cancer and 7 patients with inflammatory diseases were studied. Inflammatory lung disease included 4 cases of pneumonia, 2 of interstitial pneumonitis, and 1 of diffuse panbronchiolitis. Delayed 123I-IMP scintigraphy was performed 24 hours after intravenous injection of 111 MBq of 123I-IMP. In 14 patients, the SPECT images were obtained. Gallium scintigraphy was done within 7 days of 123I-IMP scintigraphy and the images were obtained 72 hours after the administration of 111 MBq of 67Ga-citrate. 123I-IMP scintigraphy was compared with gallium scintigraphy for its ability to detect atelectasis. The degree of uptake by the collapsed lobes was judged visually on planar images and rated using four grades: negative, slight, moderate and heavy. All the cases showed moderate or intense uptake on the 123I-IMP images, whereas with gallium scintigraphy there was no change corresponding with lobar collapse in 8 out of 10 cases. Of the remaining 2 cases, one had tumor in the collapsed lobe and the other had obstructive pneumonia. In inflammatory lung diseases, the correlation of 123I-IMP and gallium images regarding degree of change shown on chest X-ray film was studied. The degree of correlation was classified using four grade: poor, fair, good and excellent.(ABSTRACT TRUNCATED AT 250 WORDS)