Changes in Viral Dynamics Following the Legal Relaxation of COVID-19 Mitigation Measures in Japan From Children to Adults: A Single Center Study, 2020-2023

INTRODUCTION

Respiratory infections are an ongoing global health challenge. The COVID-19 pandemic triggered global nonpharmacological measures that reshaped public health. In Japan, the shift from legal to individual discretion in pandemic management started on May 8, 2023. However, it still unknown how the relaxation of measures affects respiratory pathogens across age groups.

METHODS

We collected 16,946 samples from 13,526 patients between February 2020 and September 2023, analyzing the circulating respiratory pathogen dynamics using FilmArray respiratory panel.

RESULTS

Our analysis revealed significant increases in the positivity rates of respiratory pathogens across multiple age groups after relaxation. The pathogens including adenovirus, Bordetella pertussis, parainfluenza 2 and parainfluenza 4 showed increased positivity predominantly in children aged under 10 years. Conversely, some pathogens including human metapneumovirus, rhinovirus/enterovirus, and respiratory virus (RSV) increased in broad range of age groups. SARS-CoV-2 positivity rates decreased in children under 10 years but increased in those aged over 60 years.

DISCUSSION

Age-stratified analysis reveals a dynamic pattern of circulating pathogen in each age group after relaxation measures. This study provides essential epidemiologic data that can guide strategies to protect different age groups and effectively respond to respiratory infections in post-COVID-19 era.

Classification of Omicron BA.1, BA.1.1, and BA.2 sublineages by TaqMan assay consistent with whole genome analysis data

OBJECTIVES

Recently, the Omicron strain of SARS-CoV-2 has spread and replaced the previously dominant Delta strain. Several Omicron sublineages (BA.1, BA.1.1, and BA.2) have been identified, with in vitro and preclinical reports showing that the pathogenicity and therapeutic efficacy differs between BA.1 and BA.2. We sought to develop a TaqMan assay to identify these subvariants.

METHODS

A TaqMan assay was constructed for rapid identification and genotyping of Omicron sublineages with 171 samples. We analyzed three characteristic mutations of the spike gene, Δ69-70, G339D, and Q493R, by TaqMan assay. The accuracy of the TaqMan assay was examined by comparing its results with the results of whole genome sequencing (WGS) analysis.

RESULTS

A total of 171 SARS-CoV-2 positive samples were analyzed by WGS and TaqMan assay. The 127 samples determined as BA.1/BA.1.1 by WGS were all positive for Δ69-70, G339D and Q493R by TaqMan assay. A total of 42 samples, determined as BA.2 by WGS, were negative for Δ69-70 but positive for G339D and Q493R by TaqMan. Two samples with G339N were determined to be inconclusive by the TaqMan method. Except for these two samples, the concordance rate between WGS and the TaqMan assay was 100% (169/169).

CONCLUSION

TaqMan assays targeting characteristic mutations are useful for identification and discrimination of Omicron sublineages.

Non-pharmaceutical interventions during the COVID-19 epidemic changed detection rates of other circulating respiratory pathogens in Japan

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has circulated worldwide and causes coronavirus disease 2019 (COVID-19). At the onset of the COVID-19 pandemic, infection control measures were taken, such as hand washing, mask wearing, and behavioral restrictions. However, it is not fully clear how the effects of these non-pharmaceutical interventions changed the prevalence of other pathogens associated with respiratory infections. In this study, we collected 3,508 nasopharyngeal swab samples from 3,249 patients who visited the Yamanashi Central Hospital in Japan from March 1, 2020 to February 28, 2021. We performed multiplex polymerase chain reaction (PCR) using the FilmArray Respiratory Panel and singleplex quantitative reverse transcription PCR targeting SARS-CoV-2 to detect respiratory disease-associated pathogens. At least one pathogen was detected in 246 (7.0%) of the 3,508 samples. Eleven types of pathogens were detected in the samples collected from March-May 2020, during which non-pharmaceutical interventions were not well implemented. In contrast, after non-pharmaceutical interventions were thoroughly implemented, only five types of pathogens were detected, and the majority were SARS-CoV-2, adenoviruses, or human rhinoviruses / enteroviruses. The 0-9 year age group had a higher prevalence of infection with adenoviruses and human rhinoviruses / enteroviruses compared with those 10 years and older, while those 10 years and older had a higher prevalence of infection with SARS-CoV-2 and other pathogens. These results indicated that non-pharmaceutical interventions likely reduced the diversity of circulating pathogens. Moreover, differences in the prevalence of pathogens were observed among the different age groups.

Pooling RT-qPCR testing for SARS-CoV-2 in 1000 individuals of healthy and infection-suspected patients

Severe acute respiratory coronavirus 2 (SARS-CoV-2) testing reagents are expected to become scarce worldwide. However, little is known regarding whether pooling of samples accurately detects SARS-CoV-2. To validate the feasibility of pooling samples, serial dilution analysis and spike-in experiments were conducted using synthetic DNA and nucleic acids extracted from SARS-CoV-2-positive and -negative patients. Furthermore, we studied 1000 individuals, 667 of whom were “healthy” individuals (195 healthcare workers and 472 hospitalized patients with disorders other than COVID-19 infection), and 333 infection-suspected patients with cough and fever. Serial dilution analysis showed a limit of detection of around 10–100 viral genome copies according to the protocol of the National Institute of Infectious Diseases, Japan. Spike-in experiments demonstrated that RT-qPCR detected positive signals in pooled samples with SARS-CoV-2-negative and -positive patients at 5-, 10-, 20-fold dilutions. By screening with this pooling strategy, by the end of April 2020 there were 12 SARS-CoV-2-positive patients in 333 infection-suspected patients (3.6%) and zero in 667 “healthy” controls. We obtained these results with a total of 538 runs using the pooling strategy, compared with 1000 standard runs. In a prospective study, we successfully detected SARS-CoV-2 using 10- to 20-fold diluted samples of nasopharyngeal swabs from eighteen COVID-19 patients with wide ranges of viral load. Pooling sample is feasible for conserving test reagents and detecting SARS-CoV-2 in clinical settings. This strategy will help us to research the prevalence infected individuals and provide infected-status information to prevent the spread of the virus and nosocomial transmission.

Analysis of a persistent viral shedding patient infected with SARS-CoV-2 by RT-qPCR, FilmArray Respiratory Panel v2.1, and antigen detection

Various diagnostic tests utilizing different principles are currently under development for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, these tests can occasionally produce discrepant results, causing confusion in their interpretation. Here, we evaluated the performance and features of three diagnostic assays: quantitative reverse transcription polymerase chain reaction (RT-qPCR), FilmArray Respiratory Panel (RP) v2.1, and the LUMIPULSE antigen test. Twenty-seven serial nasopharyngeal swabs were collected from a prolonged viral shedding patient who had been hospitalized for 51 days. We examined the SARS-CoV-2 detection rates of the three tests. The overall agreement rate was 81% between RT-qPCR and FilmArray RP v2.1, 63% between the antigen test and FilmArray RP v2.1, and 59% between the antigen test and RT-qPCR. We obtained concordant results in samples with high viral loads (low threshold cycle values) by all three tests. RT-qPCR and FilmArray RP v2.1 accurately detected SARS-CoV-2 at the early to intermediate phases of infection, but the results varied at the late phase. The antigen test also produced a positive result at the early phase but varied at the intermediate phase and consistently produced negative results at late phase of infection. These results demonstrated FilmArray RP v2.1 could detect SARS-CoV-2 with accuracy comparable to RT-qPCR. Further, there were discrepant results using different types of diagnostic tests during the clinical course of prolonged viral shedding patient. We provided insights into how to utilize different types of kits to assess and manage SARS-CoV-2 infections.

Comparison of automated SARS-CoV-2 antigen test for COVID-19 infection with quantitative RT-PCR using 313 nasopharyngeal swabs, including from seven serially followed patients

In routine clinical practice, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is determined by reverse-transcription PCR (RT-PCR). In the current pandemic, a more rapid and high-throughput method is in growing demand. Here, we validated the performance of a new antigen test (LUMIPULSE) based on chemiluminescence enzyme immunoassay. A total of 313 nasopharyngeal swabs (82 serial samples from 7 infected patients and 231 individual samples from 4 infected patients and 215 uninfected individuals) were analyzed for SARS-CoV-2 with quantitative RT-PCR (RT-qPCR) and then subjected to LUMIPULSE. We determined the cutoff value for antigen detection using receiver operating characteristic curve analysis and compared the performance of the antigen test with that of RT-qPCR. We also compared the viral loads and antigen levels in serial samples from seven infected patients. Using RT-qPCR as the reference, the antigen test exhibited 55.2% sensitivity and 99.6% specificity, with a 91.4% overall agreement rate (286/313). In specimens with > 100 viral copies and between 10 and 100 copies, the antigen test showed 100% and 85% concordance with RT-qPCR, respectively. This concordance declined with lower viral loads. In the serially followed patients, the antigen levels showed a steady decline, along with viral clearance. This gradual decline was in contrast with the abrupt positive-to-negative and negative-to-positive status changes observed with RT-qPCR, particularly in the late phase of infection. In summary, the LUMIPULSE antigen test can rapidly identify SARS-CoV-2-infected individuals with moderate to high viral loads and may be helpful for monitoring viral clearance in hospitalized patients.

Analysis of Covid-19 and non-Covid-19 viruses, including influenza viruses, to determine the influence of intensive preventive measures in Japan

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The prevalence of infected patients with SARS-CoV-2 or other viruses is unknown.

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We analyzed SARS-CoV-2 and 17 viruses in 191 patients with cold-like symptom in Japan.

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21 % of patient (n = 40) was infected at least one virus, including SARS-CoV-2 (n = 8).

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No influenza virus was observed in this study.

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The data implies different infectivity between influenza and SARS-CoV2.

Background

Severe acute respiratory coronavirus 2 (SARS-CoV-2) has spread and caused death worldwide. Preventive measures and infection control are underway, and some areas show signs of convergence. Other viruses in addition to SARS-CoV-2 cause cold-like symptoms and spread in the winter. However, the extent to which SARS-CoV-2, influenza viruses and other causative viruses have prevailed since implementing preventive measures is unclear.

Objectives

We aim to investigate the incidence of causative viruses and pathogens in patients.

Study design

We collected 191 nasopharyngeal swabs from patients with cold-like symptoms in Japan. All samples were subjected to multiplex PCR with the FilmArray Respiratory Panel and reverse transcription PCR (RT-PCR) to detect SARS-CoV-2.

Results

FilmArray Respiratory Panel analysis detected at least one virus in 32 of 191 patients with cold-like symptoms (21 %). Of these, we frequently identified human rhinoviruses/enteroviruses (5.8 %, n=11), human metapneumovirus (3.7 %, n=7), coronavirus 229E (2.1 %, n=4) and coronavirus OC43 (1.6 %, n=3); while no influenza viruses were detected. RT-PCR analysis detected SARS-CoV-2 (4.2 %, n=8) in patients who were not infected with the aforementioned respiratory viruses.

Conclusions

Co-infection with SARS-CoV-2 and other viruses was not observed. Causative viruses remain prevalent after implementing preventive measures. SARS-CoV-2 differs from influenza viruses in its infectivity.

Karyotypic evolution in the Galliformes: an examination of the process of karyotypic evolution by comparison of the molecular cytogenetic findings with the molecular phylogeny

To define the process of karyotypic evolution in the Galliformes on a molecular basis, we conducted genome-wide comparative chromosome painting for eight species, i.e. silver pheasant (Lophura nycthemera), Lady Amherst's pheasant (Chrysolophus amherstiae), ring-necked pheasant (Phasianus colchicus), turkey (Meleagris gallopavo), Western capercaillie (Tetrao urogallus), Chinese bamboo-partridge (Bambusicola thoracica) and common peafowl (Pavo cristatus) of the Phasianidae, and plain chachalaca (Ortalis vetula) of the Cracidae, with chicken DNA probes of chromosomes 1-9 and Z. Including our previous data from five other species, chicken (Gallus gallus), Japanese quail (Coturnix japonica) and blue-breasted quail (Coturnix chinensis) of the Phasianidae, guinea fowl (Numida meleagris) of the Numididae and California quail (Callipepla californica) of the Odontophoridae, we represented the evolutionary changes of karyotypes in the 13 species of the Galliformes. In addition, we compared the cytogenetic data with the molecular phylogeny of the 13 species constructed with the nucleotide sequences of the mitochondrial cytochrome b gene, and discussed the process of karyotypic evolution in the Galliformes. Comparative chromosome painting confirmed the previous data on chromosome rearrangements obtained by G-banding analysis, and identified several novel chromosome rearrangements. The process of the evolutionary changes of macrochromosomes in the 13 species was in good accordance with the molecular phylogeny, and the ancestral karyotype of the Galliformes is represented.

A comparative karyological study of the blue-breasted quail (Coturnix chinensis, Phasianidae) and California quail (Callipepla californica, Odontophoridae)

We conducted comparative chromosome painting and chromosome mapping with chicken DNA probes against the blue-breasted quail (Coturnix chinensis, CCH) and California quail (Callipepla californica, CCA), which are classified into the Old World quail and the New World quail, respectively. Each chicken probe of chromosomes 1-9 and Z painted a pair of chromosomes in the blue-breasted quail. In California quail, chicken chromosome 2 probe painted chromosomes 3 and 6, and chicken chromosome 4 probe painted chromosomes 4 and a pair of microchromosomes. Comparison of the cytogenetic maps of the two quail species with those of chicken and Japanese quail revealed that there are several intrachromosomal rearrangements, pericentric and/or paracentric inversions, in chromosomes 1, 2 and 4 between chicken and the Old World quail. In addition, a pericentric inversion was found in chromosome 8 between chicken and the three quail species. Ordering of the Z-linked DNA clones revealed the presence of multiple rearrangements in the Z chromosomes of the three quail species. Comparing these results with the molecular phylogeny of Galliformes species, it was also cytogenetically supported that the New World quail is classified into a different clade from the lineage containing chicken and the Old World quail.

Molecular cloning and characterization of novel centromeric repetitive DNA sequences in the blue-breasted quail (Coturnix chinensis, Galliformes)

A new family of centromeric highly repetitive DNA sequences was isolated from EcoRI-digested genomic DNA of the blue-breasted quail (Coturnix chinensis, Galliformes), and characterized by filter hybridization and chromosome in situ hybridization. The repeated elements were divided into two types by nucleotide length and chromosomal distribution; the 578-bp element predominantly localized to microchromosomes and the 1,524-bp element localized to chromosomes 1 and 2. The 578-bp element represented tandem arrays and did not hybridize to genomic DNAs of other Galliformes species, chicken (Gallus gallus), Japanese quail (Coturnix japonica) and guinea fowl (Numida meleagris). On the other hand, the 1,524-bp element was not organized in tandem arrays, and did hybridize to the genomic DNAs of three other Galliformes species, suggesting that the 1,524-bp element is highly conserved in the Galliformes. The 578-bp element was composed of basic 20-bp internal repeats, and the consensus nucleotide sequence of the internal repeats had homologies to the 41-42 bp CNM repeat and the XHOI family repeat of chicken. Our data suggest that the microchromosome-specific highly repetitive sequences of the blue-breasted quail and chicken were derived from a common ancestral sequence, and that they are one of the major and essential components of chromosomal heterochromatin in Galliformes species.

Chromosome rearrangements between chicken and guinea fowl defined by comparative chromosome painting and FISH mapping of DNA clones

Chromosome homology between chicken (Gallus gallus) and guinea fowl (Numida meleagris) was investigated by comparative chromosome painting with chicken whole chromosome paints for chromosomes 1-9 and Z and by comparative mapping of 38 macrochromosome-specific (chromosomes 1-8 and Z) and 30 microchromosome-specific chicken cosmid DNA clones. The comparative chromosome analysis revealed that the homology of macrochromosomes is highly conserved between the two species except for two inter-chromosomal rearrangements. Guinea fowl chromosome 4 represented the centric fusion of chicken chromosome 9 with the q arm of chicken chromosome 4. Guinea fowl chromosome 5 resulted from the fusion of chicken chromosomes 6 and 7. A pericentric inversion was found in guinea fowl chromosome 7, which corresponded to chicken chromosome 8. All the chicken microchromosome-specific DNA clones were also localized to microchromosomes of guinea fowl except for several clones localized to the short arm of chromosome 4. These results suggest that the cytogenetic genome organization is highly conserved between chicken and guinea fowl.

A comparative cytogenetic study of chromosome homology between chicken and Japanese quail

In order to construct a chicken (Gallus gallus) cytogenetic map, we isolated 134 genomic DNA clones as new cytogenetic markers from a chicken cosmid DNA library, and mapped these clones to chicken chromosomes by fluorescence in situ hybridization. Forty-five and 89 out of 134 clones were localized to macrochromosomes and microchromosomes, respectively. The 45 clones, which localized to chicken macrochromosomes (Chromosomes 1-8 and the Z chromosome) were used for comparative mapping of Japanese quail (Coturnix japonica). The chromosome locations of the DNA clones and their gene orders in Japanese quail were quite similar to those of chicken, while Japanese quail differed from chicken in chromosomes 1, 2, 4 and 8. We specified the breakpoints of pericentric inversions in chromosomes 1 and 2 by adding mapping data of 13 functional genes using chicken cDNA clones. The presence of a pericentric inversion was also confirmed in chromosome 8. We speculate that more than two rearrangements are contained in the centromeric region of chromosome 4. All 30 clones that mapped to chicken microchromosomes also localized to Japanese quail microchromosomes, suggesting that chromosome homology is highly conserved between chicken and Japanese quail and that few chromosome rearrangements occurred in the evolution of the two species.

Synergistic effect of CGS16949A and 5-fluorouracil on a human breast cancer cell line

The effects of the aromatase inhibitor, CGS16949A, and the fluoropyrimidine, 5-fluorouracil (5-FU), on cell cycle distribution and growth were studied using FACS analysis and MTT assay in the human breast cancer cell line, SK-BR-3. CGS16949A induced an increase in the G0-G1 fraction on SK-BR-3 cells, and the growth inhibition rate of the combination of both (65.7 +/- 3.0%) was significantly higher than 10 nM CGS16949A (37.9 +/- 6.9%) or 100 microg/ml 5-FU (45.6 +/- 4.5%); p < 0.01). Administering 5-FU after preincubation with CGS16949A significantly increased the combined cytotoxic efficacy, suggesting that clinical therapy using this combined therapy may be more efficient.

Genetic changes in colorectal carcinoma tumors with liver metastases analyzed by comparative genomic hybridization and DNA ploidy

BACKGROUND

Liver metastases are found in 10% of primary colorectal malignancies, and they affects the prognosis of patients with colorectal carcinoma. The authors investigated DNA copy number aberrations by using comparative genomic hybridization (CGH) and DNA ploidy alterations by using flow cytometry (FCM) in patients with primary colorectal carcinoma (primary tumors). To determine whether there are characteristic DNA copy number alterations that contribute to liver metastasis, cytogenetic aberrations were examined by CGH and FCM.

METHODS

The authors analyzed 35 primary tumors, including 16 primary tumors with liver metastasis, by using CGH and FCM.

RESULTS

Increases in DNA copy numbers were detected in 6q (5 of 16 tumors), 7q (6 of 16 tumors), 8q (7 of 16 tumors), 9p (5 of 16 tumors), 13q (8 of 16 tumors), 20p (9 of 16 tumors), and 20q (15 of 16 tumors) in primary tumors with liver metastases. Decreases in DNA copy numbers were found in 17p (5 of 16 tumors), 18p (6 of 19 tumors), 18q (8 of 16 tumors), and 22q (5 of 16 tumors). In contrast, primary tumors without liver metastasis showed gains in chromosome arms 8q (2 of 19 tumors), 13q (2 of 19 tumors), 20p (6 of 19 tumors), and 20q (5 of 19 tumors); however, they showed no gains in 6q or 7q and showed losses in chromosome arms 17p (2 of 19 tumors), 18p (4 of 19 tumors), 18q (6 of 19 tumors), and 22q (5 of 19 tumors). There was a significant difference in the frequency of DNA copy number gains and losses in 6q (P < 0.05), 7q (P < 0.01), 8q (P < 0.05), 13q (P < 0.05), and 20q (P < 0.01), respectively, between primary tumors with and without liver metastases. The differences in the DNA index were not significant between the two groups of primary tumors.

CONCLUSIONS

In liver metastases of primary tumors from patients with colorectal carcinoma, a correlation between DNA copy number aberrations and gains of chromosome arms 6q, 7q, 8q, 13q, and 20q is suggested.

Iodine absorption after intraoperative bowel irrigation with povidone-iodine

PURPOSE

Povidone-iodine is a commonly used intrarectal tumoricidal agent in patients undergoing colorectal surgery. The aim of this study was to assess systemic absorption of total iodine and its effect on thyroid function after intrarectal application.

METHODS

Twenty patients with carcinoma of the rectum received intraoperative irrigation with either povidone-iodine (Group A; n = 10) or physiologic saline (Group B; n = 10). Ten patients with carcinoma of the sigmoid colon (group C) were treated the same as Group A. Electrolyte, total iodine, triiodothyronine, thyroxine, and thyroid-stimulating hormone values were measured in serum preoperatively and before intraoperative irrigation and immediately, ten minutes, 1 hour, 6 hours, 24 hours, and two weeks after irrigation.

RESULTS

No significant changes occurred in serum electrolytes. A significant uptake of the total iodine was demonstrated in each group. Total iodine levels examined immediately, ten minutes, and one hour after irrigation in Group C were significantly higher than those examined in Group B. Maximum values were obtained one hour after irrigation in Groups A and B and six hours after irrigation in Group C. No significant changes occurred in triiodothyronine, thyroxine, and thyroid-stimulating hormone levels among the three groups. The decrease in triiodothyronine levels after surgery was demonstrated in each group. We noted a decrease after surgery in thyroxine levels for Groups A and B and in thyroid-stimulating hormone levels for Group B. Those hormones were not affected by the administration of povidone-iodine.

CONCLUSION

High serum levels of iodine did not cause organ toxicity, suggesting that a single use of intraoperative bowel irrigation with povidone-iodine may be performed with practically negligible risk.

The effect of vaginal delivery on the pelvic floor

This study was undertaken to determine the effects of vaginal deliveries on anorectal function, and to analyze the possible clinical, physiological, and radiological risk factors predisposing to damage of the pelvic floor musculature. We studied 25 consecutive women with a mean age of 32 years old, 3 months after vaginal delivery, 17 of whom were primiparae and 8, multiparae. The symptoms of anal incontinence were assessed, and anorectal manometry, rectal sensation, and radiological measurements of the anorectal angle and pelvic floor position at rest, on squeezing, and on straining were performed. As a control, six nulliparous women underwent the same examinations. Pelvic floor descent in both the primiparae and multiparae was significantly greater at rest and on squeezing than that in the nulliparous women. Furthermore, pelvic floor descent on straining was greater in the multiparae than in the nulliparous women (P = 0.028). An analysis of the 17 primiparae showed that prolonged duration of the second stage of labor and third-degree perineal tears were important factors predisposing to pelvic floor descent. In fact, 3 of the 17 primiparae (17%) had anal incontinence. These findings indicate that vaginal delivery may cause pelvic floor descent, an obtuse anorectal angle, and bowel symptoms.

Effect of povidone-iodine on anastomotic tumor growth in an experimental model of colorectal cancer surgery

Implantation of viable exfoliated tumor cells may be responsible for the local recurrence of colorectal cancer. Intraluminal colon cancer cells derived from chemically induced colon cancer in syngenic F344 rats, were introduced 2 cm proximally to a colonic anastomosis and anastomotic tumor growth was observed. Anastomotic tumor growth was found in about 30% of the animals, when sacrificed on the 3rd postoperative week. The cytotoxic efficacy of povidone-iodine (PVP-I) was tested with the same model. The administration of 10% PVP-I solution significantly reduced the incidence of tumor growth. Viable intraluminal tumor cells cause anastomotic tumor growth by becoming implanted on an anastomosis and PVP-I had effective cytotoxicity.

Anorectal function after anterior resection with side-to-side anastomosis for carcinoma of the rectum

PURPOSE

The aim of this study is to demonstrate whether anorectal function after anterior resection with side-to-side anastomosis results in better clinical outcomes than end-to-end anastomosis in patients with carcinoma of the upper half of the rectum.

METHODS

Anorectal function was studied in two groups of patients who had anterior resection, those with end-to-end anastomosis (Group E; n = 11) and those with side-to-side anastomosis (Group S; n = 11). Eight control subjects who had sigmoid colectomy for carcinoma were also studied. Each patient underwent manometric study and was questioned about clinical bowel symptoms before the operation and 3, 6, and 12 months postoperatively.

RESULTS

The median length of residual rectum in both Group S and Group E was 7 cm. No significant difference was observed in maximum anal resting pressure and maximum squeeze pressure between the groups before and after operation. Maximum tolerable volume in Group S was significantly higher than that in Group E and was close to that in the control group at each postoperative interval. Median volumes in Group S were 200 ml (3 months), 220 ml (6 months), and 220 ml (12 months). Median volumes in Group E were 140 ml (3 months), 150 ml (6 months), and 175 ml (12 months). Bowel frequency per 24 hours at three and six months postoperatively was significantly greater in Group E than in Group S or the control group. Median frequency in Group E was four times (3 months) and three times (6 months) per 24 hours. Median frequency in both Group S and the control group was two times (3 months) and two times (6 months) per 24 hours. Postoperative urgency of defecation was not found in Group S, significantly less frequent than in Group E at three months.

CONCLUSION

Side-to-side anastomosis may lead to a better clinical outcome than end-to-end anastomosis for carcinoma of the upper half of the rectum in the adaptation phase.

Antitumor effect of hepatocyte growth factor on hepatoblastoma

A six month-old girl presented with an abdominal mass, and high serum level of alpha-fetoprotein. She was diagnosed as having a well-differentiated hepatoblastoma by open biopsy. The biopsy specimen was transplanted on a nude mouse, and a xenograft was successfully established. Because the xenograft maintained the characteristics of the original tumor, the effect of hepatocyte growth factor (HGF) on hepatoblastoma xenograft was investigated. Recently HGF was reported to be involved in growth, invasion, and metastasis of tumor cells. Contrary to our expectations, the treatment of hepatoblastoma xenograft with recombinant 20 ng/ml HGF produced a marked inhibition of cell growth and a suppression of producing alpha-fetoprotein.

Genetic changes in primary colorectal cancer by comparative genomic hybridization

Comparative genomic hybridization (CGH) is a powerful new technique for the molecular cytogenetic analysis of cancer. In this method, at first the cancer DNA and normal DNA are labeled with biotin and digoxigenin, respectively, and then the labeled DNAs are applied onto normal lymphocyte metaphase preparations in hybridization. After hybridization, they are stained with FITC and rhodamine, respectively, so chromosomal gains and losses in cancer are thus detected by using a green:red ratio. In this study, we analyzed the abnormal chromosomes in nine cases with human primary colon cancer. A gain in chromosomes 11p, 12q, 16p, 20p, and 20q were observed, while a loss of 18q and 22q were discovered. CGH may thus provide us with important information for analyzing the genes in colon cancer.

[Adjuvant chemotherapy with UFT or UFT with OK-432 to patients with gastric and colorectal cancer. Kanto Adjuvant Study Group]

In Japan, long-term oral therapy with tegafur in combination with immunopotentiators is commonly used as adjuvant therapy after curative resection of gastric or colorectal can for gastric and colorectal cancer. When the outcome was analyzed in terms of the relative performance (R.P.) and the individual dose intensity (I.D.I.) of OK-432, gastric cancer patients with a R.P. of 0.5 or higher tended to have a better survival curve. There were no marked differences in lymphocytes subsets, except that the Leu 7 level at 3 months after gastric cancer resection was significantly higher (p < 0.05) in group B than in group A. Thus, no inhibition of the anticancer effect of UFT was noted during long term combination therapy with UFT and an immunopotentiator as postoperative adjuvant therapy for patients who underwent curative resection of gastric or colorectal cancer. The results suggest that UFT combined with long-term OK-432 maintenance therapy may contribute to improve survival rates in gastric cancer patients.

Antitumor effect of S-1 on DMH induced colon cancer in rats

The aim of this study was to establish an autochthonous colon cancer model in the rat as an in vivo secondary screen for the general evaluation of new anticancer agents against colorectal cancer, and also to evaluate practically the antitumor activity of 1M tegafur-0.4M 5- chloro-2,4-dihydroxypyridine-1M potassium oxonate(S-1), a new p.o. fluoropyrimidine. Thirty-two Sprague-Dawley rats received dimethlhydrazine(40 mg/kg) s.c. once weekly for 10 weeks to induce colon cancer.20 weeks after beginning the carcinogen treatment, a barium enema was performed to visualize tumors. The animals were divided into a control group and S-1 treatment group. After 5 weeks of treatment, the barium enema was repeated. The mean doubling time of 24 tumors in the control group was 19.0 + 8.4 (SD) days. Response to S-1 was judged as effective when the doubling time exceeded 35.8 days, calculated from the mean + 2SDs in the control group. The response rate of S-1 was 55%, 34% of the tumors were decreased in size after treatment. This figure was higher than that of clinically-used 5-fluorouracil(5-FU) derivatives; 5-FU;6%, Tegafur(FT):6%, 1M tegafur-4M uracil(UFT):14%, reported in our previous study. An autochthonous colon cancer model is useful to evaluate the clinical therapeutic efficacy of drugs for colorectal cancer, and S-1 is expected to have a high therapeutic effect on human colorectal cancer.