Low incidence of hepatitis B virus reactivation and subsequent hepatitis in patients with chronic hepatitis C receiving direct-acting antiviral therapy.

To determine the clinical characteristics of hepatitis B virus (HBV) reactivation in patients undergoing interferon-free antihepatitis C virus (HCV) therapy, we examined HBV DNA in 25 HBV co-infected patients and 765 patients with resolved HBV infection during and after treatment with direct-acting antiviral agents (DAAs). Among those with HCV genotype 1, asunaprevir plus daclatasvir was administered to 160 patients, sofosbuvir (SOF) plus ledipasvir to 438 patients and paritaprevir plus ombitasvir and ritonavir to 25 patients. In total, 167 patients with genotype 2 were treated with SOF plus ribavirin. Three patients with an HBV DNA level ≥2000 IU/mL were treated with entecavir before anti-HCV therapy, without reactivation of HBV. In 3 of 22 (12%) HBV surface antigen (HBsAg)-positive patients with an HBV DNA level <2000 IU/mL, the viral load increased during treatment. However, hepatitis flare did not occur in these patients. There was no significant difference in clinical history between patients with and without HBV reactivation. Among 765 patients with resolved HBV infection, HBV reactivation occurred in 1 (0.1%) patient after initial resolution, whose HBV DNA level spontaneously decreased after DAA therapy. We compared anti-HBs titres at baseline with those at post-DAA therapy in 123 patients without HBsAg. There was no significant difference in anti-HBs levels between the two points (P = .79). In conclusion, HBV reactivation was rare in HBsAg-negative patients treated with DAA therapy. Additionally, hepatitis did not occur in HBV-reactivated patients with a baseline HBV DNA level <2000 IU/mL before DAA therapy.

The presence of multiple NS5A RASs is associated with the outcome of sofosbuvir and ledipasvir therapy in NS5A inhibitor-naïve patients with chronic HCV genotype 1b infection in a real-world cohort.

It is unclear whether multiple nonstructural (NS) 5A resistance-associated substitutions (RASs) correlate with the outcome of sofosbuvir (SOF) and ledipasvir (LDV) therapy. We investigated the effects of multiple NS5A RASs in NS5A inhibitor-naïve patients with chronic hepatitis C virus genotype 1b infection treated with SOF/LDV. In 313 patients treated with SOF/LDV, we assessed the effects of multiple NS5A RASs on the sustained virological response (SVR). RASs at L28, R30, L31, Q54, P58, Q62, A92, and Y93 in the NS5A region were examined by direct sequencing. The prevalence of RASs was as follows: 2.6% at L28, 8.7% at R30, 6.1% at L31, 48.7% at Q54, 9.9% at P58, 9.9% at Q62, 5.1% at A92, 13.8% at Y93, and 19.2% at L31 or Y93. A total of 133 patients had no RASs. SVR was achieved in 98.7% of the patients. SVR rates significantly differed between patients with and without the L31 or Y93 RAS (93.0% [53/57] vs 100% [250/250], P = .0011). In addition, among patients with the L31 or Y93 RAS, 29.8%, 45.6% and 24.6% had one, two and three or more NS5A RASs, respectively. The SVR rate was significantly lower in patients with the L31 or Y93 RAS with more than three NS5A RASs compared to those with fewer than three NS5A RASs (71.4% [10/14] vs 100% [43/43], P = .0025). Although the prevalence of multiple NS5A RASs at baseline was low in NS5A inhibitor-naïve patients, the presence of multiple NS5A RASs was associated with the effectiveness of SOF/LDV therapy.

Add-on combination therapy with adefovir dipivoxil induces renal impairment in patients with lamivudine-refractory hepatitis B virus.

Combination therapy with adefovir dipivoxil (ADV) and lamivudine (LAM) is recommended for patients infected with LAM-refractory hepatitis B virus (HBV). However, the effects of such therapy on renal function and serum phosphorus levels have not been fully evaluated. Combination therapy with ADV and LAM was given to 37 patients infected with LAM-refractory HBV, including 17 with hepatic cirrhosis. Serum HBV DNA levels decreased to below 2.6 log(10) copies/mL in 23 (62%) of 37 patients at 12 months, 25 (78%) of 32 patients at 24 months, and 16 (84%) of 19 patients at 36 months. Except for one cirrhotic patient, serum alanine aminotransferase levels were below 50 IU/L in all patients during combination therapy. Serum creatinine levels increased in 14 (38%) of 37 patients, and serum phosphate levels decreased to below 2.5 mg/mL in 6 (16%) of 37 patients during combination therapy. Patients who received combination therapy for 36 months or longer had a significantly incidence of elevated serum creatinine levels. Fanconi syndrome occurred in a 57-year-old woman with cirrhosis after ADV was added to LAM. Combination therapy with ADV and LAM can maintain biochemical remission in patients with LAM-refractory HBV. However, the dosing interval of ADV should be adjusted according to renal function and serum phosphate levels in patients receiving long-term treatment.

A study of the incidence of implantation cyst at anastomotic sites after low anterior resection of the rectum with the double stapling technique.

BACKGROUND: The incidence of implantation cyst occurring at sites of anastomosis after low anterior resection of the rectum were studied in two different periods depending on the type of surgical devices used to close the rectal stump. SUBJECTS: The study included 361 patients undergoing the surgery during the first 8-year period between 1996 and 2003 and 87 patients undergoing the surgery during the second 3-year period between 2004 and 2006. RESULTS: Implantation cysts were found in nine (2.5%) of the patients undergoing the surgery during the first period and one of them also had local recurrence. Implantation cysts occurred 9 to 31 months postoperatively (mean, 17.1 +/- 6.9 months). Clinical symptoms were noted in one patient and treatment of the cysts, including local recurrence, was given to two patients. Anastomosis of the distal rectum was performed with the Roticulator or the Access 55 in all patients. Although implantation cysts were found in any patient undergoing surgery during the second period, no statistically significant difference was recognized (p = 0.217). Anastomosis of the distal rectum was performed with the TX30 in all patients. CONCLUSION: The pathogenesis of implantation cysts may be explained by the production of mucus when the mucosal epithelium of the colon is caught under the submucosa, forming a cyst after closure of the rectal stump, and the difference in the incidence rates of implantation cyst was presumably due to the characteristics of the device used and progress of the operative procedure.

Analysis of autonomic nerve preservation and pouch reconstruction influencing fragmentation of defecation after sphincter-preserving surgery for rectal cancer.

Our questionnaire survey on defecation disorders after rectal cancer surgery revealed that 66.7% of postoperative patients were most annoyed with fragmentation of defecation. Therefore, we performed a change-over-time analysis on the relationship of fragmentation and factors including location of rectal cancer, surgical technique, anastomosis method, pouch reconstruction, extent of lymph node dissection, and degree of pelvic and colonic nerve preservation surrounding the superior mesenteric artery. The fragmentation decreased over time at the postoperative time points of 6 months, 2 and 5 years. A statistical analysis of factors influencing fragmentation revealed that location of cancer, reconstruction technique, anastomosis method and degree of pelvic nerve preservation were significant factors for the entire patient population and that colonic nerve preservation was a significant factor 5 years after surgery. Analysis of patients with lower rectal cancer only showed that in addition to surgical technique and anastomosis method, pouch reconstruction was effective and autonomic nerve preservation was effective 5 years after surgery. As a result, when the anastomotic site was closer to the anus, the frequency of fragmentation increased; we concluded that pouch reconstruction was an effective surgical technique and colonic nerve preservation was effective in the longer term.

Placebo-controlled pilot study of the effects of an eggshell membrane-based supplement on mobility and serum biomarkers in dogs with osteoarthritis.

Osteoarthritis (OA) is a debilitating disease in dogs. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used to treat OA; however, many dogs do not obtain adequate pain relief with an NSAID alone. This pilot study evaluated the systemic anti-inflammatory and mobility enhancing effects of an eggshell membrane-based nutritional supplement in dogs with OA-associated pain and mobility impairment. Twenty-seven dogs with OA-associated pain were enrolled into a randomized, double-masked, placebo-controlled, proof of principle pilot study and received either placebo or an eggshell membrane-based nutritional supplement over a 12-week period. Inflammatory biomarkers (IL-2, IL-6, IL-8, tumor necrosis factor-α, C-reactive protein, S100A12, and N-methylhistamine) were measured at Day 0 and Day 84. Owner questionnaires (CBPI and LOAD) were completed at Day 0, Day 42, and Day 84. Differences between groups over time were calculated. Twenty-two dogs completed the pilot study. Inflammatory biomarker IL-2 decreased in the supplement group, compared to the placebo group. Although small, the difference was statistically significant at an alpha of 0.1 (P=0.069). LOAD scores were numerically lower in the supplement group, but not significantly different from the placebo group at Day 0. Day 84 LOAD scores were significantly lower in the supplement group compared to the placebo group (P=0.034). CBPI results did not show the same pattern. The changes in biomarkers and LOAD scores were small, and do not provide definitive evidence of positive effects. However, these pilot results provide a rationale for performing a larger placebo-controlled study of the potential effects of the eggshell membrane-based nutritional supplement.

[Pleomorphic carcinoma of the lung; report of a case].

A 66-year-old female complained of cough, and was referred to our hospital. Chest radiography and computed tomography (CT) showed a tumor mass near the right hilum and atelectasis of the middle lobe. Bronchoscopy revealed a whitish polypoid tumor obstructing the middle lobe bronchus. Histology by punch biopsy suggested adenocarcinoma Right upper and middle lobectomy was performed, due to the direct invasion of the tumor from the middle lobe to the upper lobe. Histological findings showed adenocarcinoma comprised of spindle cell component, finally diagnosing as pleomorphic carcinoma of the lung. After the operation, systemic chemotherapy, including paclitaxel and carboplatin was performed. About 42 months after operation, the patient died of multiple brain metastases.

Initial evaluation of PetPace activity monitor.

Mobility is considered a vital component of health and quality of life in humans and companion animals. Wearable devices for pets that can monitor activity and other aspects of health are increasingly being marketed to veterinarians and owners, with claims around their ability to monitor aspects of health. However, there is little scientific evidence to support the validity of these claims. To address this, the objective of this study was to assess the correlation of the activity measurement from the PetPace device compared to activity output from Actigraph and the validated Actical device. Ten client-owned, healthy dogs were used for the study. The three devices were mounted simultaneously on a dedicated collar and activity was recorded during a period of 7 days. There were moderate correlations between the Actical and the PetPace (r2=0.59, P=<0.001). There was high correlation between the PetPace and the Actigraph (r2=0.85, P=<0.001) and between the Actical and the Actigraph (r2=0.72, P=<0.001). If the Actical activity counts were limited under 50,000 per hour, there was strong correlation between the Actical and the PetPace (r2=0.71, P=<0.001) and between the Actical and the Actigraph (r2=0.86, P=<0.001). PetPace has a moderate correlation with the most validated activity monitor that has been used in veterinary medicine. Its real-time data acquisition, user friendly interface for owners and cost make this device an attractive tool for monitoring activity in dogs. Further studies maybe needed to evaluate its performance, validity and clinical utility in the field.

Modification of submerged membrane bioreactors (MBRS) by inserting baffles: pilot scale study.

Submerged membrane bioreactors (MBRs) have been gaining in popularity in various types of wastewater treatment. One drawback of submerged MBRs is difficulty in removing nitrogen as they are accompanied with intensive aeration inside the reactor and therefore principally operated under aerobic conditions. In order to address this problem, a simple modification for submerged MBRs, insertion of baffles to create alternative aerobic/anoxic conditions, was proposed. In this study, the performance of the proposed baffled membrane bioreactor (BMBR) was investigated based on a pilot-scale experiment using a real municipal wastewater. With appropriate operating conditions, the BMBR could remove more than 70% of total nitrogen contained in the feed water without any external carbon source. The BMBR demonstrated a good treatment performance in terms of TOC and phosphorus removal as well. Increase of trans-membrane pressure difference was subtle, which might be attributed to the alternative creation of aerobic/anoxic conditions.

Establishment of a clonal human chondrosarcoma cell line with cartilage phenotypes.

A clonal cell line with cartilage phenotypes and tumorigenicity during more than 3 years in culture was established from a human chondrosarcoma. In sparse cultures, the clonal line, named HCS-2/8, consisted of slightly elongated polygonal cells, which proliferated with a doubling time of 3.5 days. The cells became polygonal to spherical as they became confluent. After reaching confluence, the cells continued to proliferate slowly and formed nodules, which showed metachromasia when stained with toluidine blue. The nodules were three-dimensional in structure; cells were multilayered in the surface regions, overlying a thick layer of extracellular matrix, which showed metachromasia. Electron microscopically, the cells resembling chondrocytes in vivo were surrounded by an extracellular matrix consisting of thin collagen-like fibrils with numerous fine granules, presumably of proteoglycans. The cells actively synthesized proteoglycans as determined by [35S]sulfate incorporation. The hydrodynamic size of major proteoglycan monomers synthesized by the cells was that of so-called cartilage-specific proteoglycans, as determined by glycerol gradient centrifugation. Immunostaining identified type II collagen but not type I collagen. Fluorography and immunoblotting of collagens separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis also demonstrated the synthesis of type II collagen but not type I collagen. Inoculation of HCS-2/8 cells into athymic mice resulted in the formation of chondrosarcomas that resembled the original tumor. Because of having these characters, HCS-2/8 cells should be useful not only in studies on the differentiated phenotypes of human chondrocytes but also in basic studies on the diagnosis, treatment, and etiology of human chondrosarcomas.

Tumor angiogenesis and polyamines: alpha-difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase, inhibits B16 melanoma-induced angiogenesis in ovo and the proliferation of vascular endothelial cells in vitro.

alpha-Difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase, inhibited B16 melanoma-induced angiogenesis in chick embryo chorioallantoic membrane and subsequently the growth of the tumor on the chorioallantoic membrane. These inhibitions were reversed by exogenous putrescine and spermidine. DFMO also inhibited rapid neovascularization in yolk sac membrane of 4-day-old chick embryos and the inhibition was reversed by exogenous putrescine and spermidine. DFMO strongly inhibited DNA synthesis and proliferation of bovine pulmonary artery endothelial (BPAE) cells in culture and decreased their ornithine decarboxylase activity and intracellular polyamine concentrations. Addition of putrescine to the culture medium of DFMO-treated BPAE cells restored their intracellular putrescine and spermidine concentrations and their DNA synthesis and proliferation. Addition of spermidine to cultures of DFMO-treated BPAE cells restored their intracellular spermidine concentration and their DNA synthesis and proliferation. DFMO inhibited the proliferation of B16 melanoma cells in culture but the inhibitory effect was much less than that on BPAE cells. When one-half the monolayer of confluent cultures of BPAE cells had been peeled off, addition of DFMO to the cultures inhibited the proliferation and extension of the BPAE cells into the vacant area but had no effect on stationary cells in the remaining half of the monolayer, suggesting that it inhibited induction of proliferation of endothelial cells. These findings suggest that the antitumor activity of DFMO against solid tumors is probably due more to its inhibition of tumor-induced angiogenesis by inhibition of proliferation of endothelial cells induced by polyamine depletion than to a direct effect on tumor cell proliferation.

Coexistence of somatic and germ-line mutations of APC gene in desmoid tumors from patients with familial adenomatous polyposis.

Desmoid tumors, which are locally invasive with recurrence but without metastasis, are frequently observed in patients with familial adenomatous polyposis after abdominal surgery or during pregnancy. This study analyzed mutation of the adenomatous polyposis coli gene in 8 desmoid tumors from 7 familial adenomatous polyposis patients using polymerase chain reaction-single-strand conformation polymorphism and the direct sequencing method. Seven somatic mutations, 1 somatic allele loss, and 6 germ-line mutations were detected. The majority of adenomatous polyposis coli gene mutations were deletions of 1 to 19 base pairs in exon 15, and all mutations led to the formation of stop codons. A somatic mutation with repetition of 82 base pairs from codon 1399 to 1426 was also observed in a desmoid, which was most likely caused by an error during replication or repair replication. No mutation was detected in exons 1 to 2 of H-ras, K-ras, and N-ras genes and in exons 5 to 8 of p53 gene, in these tumors. The simultaneous existence of somatic and germ-line alterations of adenomatous polyposis coli gene observed in all 8 tumors strongly suggests that inactivation of both alleles of adenomatous polyposis coli gene is involved in the development of desmoid tumors.

Characteristics of somatic mutation of the adenomatous polyposis coli gene in colorectal tumors.

Mutation of the adenomatous polyposis coli (APC) gene was analyzed in 500 colorectal tumors from 70 familial adenomatous polyposis (FAP) and 102 non-FAP patients and in normal tissues from 119 FAP patients, using polymerase chain reaction-single-strand conformation polymorphism and direct sequencing methods. These tumors were histopathologically diagnosed. Sixty-eight germ line mutations (62% deletion, 9% insertion, and 29% single-base substitution) and 241 somatic mutations (56% deletion, 12% insertion, and 32% single-base substitution) were detected. All mutations formed stop codons resulting in truncated APC proteins, except for one germ line mutation. Differences were found between somatic and germ line mutations, including 3 new hot spots of mutation at codons 1378, 1450, and 1487-1490, which frequently occurred in somatic mutations but not in germ lines. The frequency of mutation in each histopathological type of FAP tumor was 53% in moderate adenoma, 64% in severe adenoma, 52% in intramucosal carcinoma, and 33% in invasive carcinoma, whereas the loss of heterozygosity including the APC gene increased with development to each histopathological type. A similar tendency was observed in non-FAP tumors. Additionally, we found 10 FAP tumors that had both somatic mutation and loss of heterozygosity. These tumors were assumed to have developed from moderate adenomas with germ line and somatic mutations, followed by deletion of the allele with germ line mutation. These results suggest that inactivation of the APC gene by two mutations is involved in the development of moderate adenoma, and loss of heterozygosity of the APC gene is associated with further development to carcinoma. It was also observed that the distribution of 75 somatic mutations from one FAP patient on the APC sequence was similar to the distribution of 159 somatic mutations from 83 patients with FAP and non-FAP, which suggests that the position of somatic mutation is mostly due to the APC sequence itself.

Statins alter smooth muscle cell accumulation and collagen content in established atheroma of watanabe heritable hyperlipidemic rabbits.

BACKGROUND: Acute coronary syndromes often result from rupture of vulnerable plaques. The collagen content of plaques probably regulates their stability. This study tested whether HMG-CoA reductase inhibitors (statins) alter interstitial collagen gene expression or matrix metalloproteinase (MMP) levels in rabbit atheroma. METHODS AND RESULTS: We administered equihypocholesterolemic doses of pravastatin (a hydrophilic statin, 50 mg. kg(-1). d(-1), n=9), fluvastatin (a cell-permeant lipophilic statin, 20 mg. kg(-1). d(-1), n=10), or placebo (n=10) to mature Watanabe heritable hyperlipidemic rabbits for 52 weeks. The fluvastatin group achieved a much higher peak plasma concentration (23.7 micromol/L) than did the pravastatin group (1.3 micromol/L) under these conditions. Immunohistochemistry revealed that MMP-1, MMP-3, and MMP-9 expression by macrophages in the intima was lower in both the pravastatin and fluvastatin groups than in the placebo group, whereas there was no difference in macrophage numbers. Numbers of intimal smooth muscle cells (SMCs) (identified by immunohistochemistry) and expression of type I procollagen mRNA (detected by in situ hybridization), however, were significantly higher in the pravastatin group than in the fluvastatin group. Treatment with pravastatin, but not fluvastatin, preserved interstitial collagen content in vivo (detected by picrosirius red polarization). In vitro, fluvastatin, but not pravastatin, decreased numbers of rabbit and human aortic SMCs without altering procollagen I mRNA expression. CONCLUSIONS: This study showed that statins can reduce MMP expression in atheroma and that cell-permeant statins can decrease SMC number and collagen gene expression in vivo.

Deletion formation between the two Salmonella typhimurium flagellin genes encoded on the mini F plasmid: Escherichia coli ssb alleles enhance deletion rates and change hot-spot preference for deletion endpoints.

Deletion formation between the 5'-mostly homologous sequences and between the 3'-homeologous sequences of the two Salmonella typhimurium flagellin genes was examined using plasmid-based deletion-detection systems in various Escherichia coli genetic backgrounds. Deletions in plasmid pLC103 occur between the 5' sequences, but not between the 3' sequences, in both RecA-independent and RecA-dependent ways. Because the former is predominant, deletion formation in a recA background depends on the length of homologous sequences between the two genes. Deletion rates were enhanced 30- to 50-fold by the mismatch repair defects, mutS, mutL and uvrD, and 250-fold by the ssb-3 allele, but the effect of the mismatch defects was canceled by the delta recA allele. Rates of the deletion between the 3' sequences in plasmid pLC107 were enhanced 17- to 130-fold by ssb alleles, but not by other alleles. For deletions in pLC107, 96% of the endpoints in the recA+ background and 88% in delta recA were in the two hot spots of the 60- and 33-nucleotide (nt) homologous sequences, whereas in the ssb-3 background > 50% of the endpoints were in four- to 14-nt direct repeats dispersed in the entire 3' sequences. The deletion formation between the homeologous sequences in RecA-independent but depends on the length of consecutive homologies. The mutant ssb allele lowers this dependency and results in the increase in deletion rates. Roles of mutant SSB are discussed with relation to misalignment in replication slippage.

Mapping by transposons of the inversion termini in Escherichia coli K-12 strain 1485IN.

Strain 1485IN carries a chromosomal inversion which corresponds to 35% of the chromosome and includes proC, trp and his genes. The termini of the inversion lie between the lac and proC loci and between his and cdd of the normal strain. Using Tn10 and Tn5 in transduction crosses between the normal and inversion strains, the termini were mapped to sites located approximately 0.25 min and 1.6 min away from proC and his, respectively within a region of roughly 4 kb long. The crosses where the normal strains carrying Tn10 near the terminus are donors and the inversion strain is a recipient, yielded unusual Tetr His- recombinants, which arose from illegitimate recombination leading to the replacement of a chromosomal his+ region with a transducing fragment carrying proC. Another rearrangement was detected between the normal and inversion strains in a region outside the inverted segment near the cdd locus.

Large inversion in Escherichia coli K-12 1485IN between inversely oriented IS3 elements near lac and cdd.

A companion study has shown that the inversion carried by strain 1485IN has one terminus between lac and proC and the other between his and cdd of the normal strain. Starting with this mapping data, we have done molecular work demonstrating that the inversion occurred by recombination between inversely oriented two IS3 elements, one present near lac and the other near the cdd locus; i.e., the inversion is IN(is3B-is3E). Evidence supporting this conclusion includes: (i) Normal and inversion strains share two short regions with identical restriction maps. One of these regions is near lac and the other near cdd. (ii) IS3 homology was detected in each of the terminus regions of both the normal and inversion strains. (iii) The sequence on one side of the original IS3 element near lac has been exchanged with the sequence on one side of the IS3 near cdd. Whether the inversion has occurred by one event of homologous recombination between the two IS3 elements or has been caused by involvement of IS3 elements on an F factor is discussed. Another rearrangement, probably related to inversion and deletion, was detected between the IS3 and cdd of the inversion strain.

Integration, at hag or elsewhere, of H2 (phase-2 flagellin) genes transduced from Salmonella to Escherichia coli.

A fla mutant of E. coli K12 was given fla+ and H1-i by phage P1kc cotransduction from S. typhimurium, then made Fla- by transduction of ah1 from S. typhimurium. Motile clones expressing a Salmonella phase-2 antigen, e,n,x or 1,2, were obtained from the K12 i ah1 (therefore Fla-) line by P1kc transduction of flagellin-specifying genes, H2-e,n,x or H2-1,2, from Salmonella donors. Of eighteen such transductants sixteen failed to show phase variation, and on transduction back to Salmonella each structural gene for a phase-2 flagellin (or at least for its antigenically determinant part) now behaved as an allele of H1, presumably in consequence of incorporation in the hag region of the K12 recipient, in place of H1-i ah1. The e,n,x- and 1,2-specifying genes were shown to have been integrated in the K12 chromosome without the linked H1-repressor gene or the adjacent vh2 gene (controlling rate of phase-variation) and they responded to the repressing activity of an H2 allele elsewhere in the cell, in this respect resembling H1 alleles of Salmonella or hag alleles of E. coli. Two K12 e,n,x transductants had flagellin-specifying genes which when transduced back to Salmonella were integrated at H2; they are inferred to have resulted from integration of H2-e,n,x in the K12 chromosome elsewhere than the hag region. These two clones showed phase variation, between a Fla+ phase, with antigen e,n,x, and a Fla- phase (with e,n,x determinant in the nonactive state and the determinant of antigen i inactivated by ah1). The two integrated e,n,x genes when in the "active" state retained the ability to repress expression of exogenote H1 alleles, which indicates that the closely linked H1-repressor gene also was integrated. One of the two exceptional transductants derived its e,n,x gene from a Salmonella donor with the linked vh2- gene, which in Salmonella almost entirely prevents change of phase, and transduction of this e,n,x gene back to Salmonella recipients proved that vh2- had been incorporated into the E. coli chromosome along with the e,n,x determinant and the H1-repressor gene. The high frequency of change of phase (Fla+ in equilibrium Fla-) in the K12 e,n,x vh2- transductant concerned suggests that vh2- fails to prevent frequent change of state of the phase-determined part of H2 when vh2- and H2 are incorporated in the E. coli chromosome.