The impact of seasonal operating room closures on wait times for oral cancer surgery

Background

Operating room slowdowns occur at specific intervals in the year as a cost-saving measure. We aim to investigate the impact of these slowdowns on the care of oral cavity cancer patients at a Canadian tertiary care centre.

Methods

A total of 585 oral cavity cancer patients seen between 1999 and 2015 at the London Health Science Centre (lhsc) Head and Neck Multidisciplinary Clinic were included in this study. Operating room hours and patient load from 2006 to 2014 were calculated. Our primary endpoint was the wait time from consultation to definitive surgery. Exposure variables were defined according to wait time intervals occurring during time periods with reduced operating room hours.

Results

Overall case volume rose significantly from 2006 to 2014 (p < 0.001), while operating room hours remained stable (p = 0.555). Patient wait times for surgery increased from 16.3 days prior to 2003 to 25.5 days in 2015 (p = 0.008). Significant variability in operating room hours was observed by month, with lowest reported for July and August (p = 0.002). The greater the exposure to these months, the more likely patients were to wait longer than 28 days for surgery (odds ratio per day [or]: 1.07, 95% confidence interval [ci]: 1.05 to 1.10, p < 0.001). Individuals seen in consultation preceding a month with below average operating room hours had a higher risk of disease recurrence and/or death (hazard ratio [hr]: 1.59, 95% ci: 1.10 to 2.30, p = 0.014).

Conclusions

Scheduled reductions in available operating room hours contribute to prolonged wait times and higher disease recurrence. Further work is needed to identify strategies maximizing efficient use of health care resources without negatively affecting patient outcomes.

Receptor for motilin identified in the human gastrointestinal system

Motilin is a 22-amino acid peptide hormone expressed throughout the gastrointestinal (GI) tract of humans and other species. It affects gastric motility by stimulating interdigestive antrum and duodenal contractions. A heterotrimeric guanosine triphosphate-binding protein (G protein)-coupled receptor for motilin was isolated from human stomach, and its amino acid sequence was found to be 52 percent identical to the human receptor for growth hormone secretagogues. The macrolide antibiotic erythromycin also interacted with the cloned motilin receptor, providing a molecular basis for its effects on the human GI tract. The motilin receptor is expressed in enteric neurons of the human duodenum and colon. Development of motilin receptor agonists and antagonists may be useful in the treatment of multiple disorders of GI motility.

The effects of irbesartan added to hydrochlorothiazide for the treatment of hypertension in patients non-responsive to hydrochlorothiazide alone

AIM

To evaluate the antihypertensive efficacy and safety of adding irbesartan to hydrochloride (HCTZ) in patients not adequately controlled by HCTZ alone.

PATIENTS AND METHODS

In this multicenter study, after a single-blind, placebo lead-in period, hypertensive patients received single-blind HCTZ 25 mg once daily. After 4 weeks, 238 patients with seated diastolic blood pressure of 93-110 mmHg continued on HCTZ 25 mg once daily and were randomized to double-blind irbesartan 75 mg once daily or matching placebo for 12 weeks. At week 6, the dosage of irbesartan or placebo was doubled for seated diastolic blood pressure > or = 90 mmHg.

RESULTS

At weeks 2, 6, and 12, irbesartan/HCTZ resulted in significantly greater (P<0.01) reductions from baseline in trough seated diastolic and systolic blood pressure compared with placebo/HCTZ. At week 12, the mean reductions in trough seated diastolic and systolic blood pressure were 7.2 mmHg (95%, C.I., 5.1-9.3 mmHg) and 11.1 mmHg (95% C.I., 7.9-14.3 mmHg) greater, respectively, with irbesartan/HCTZ compared with placebo/HCTZ. At week 12, significantly (P < 0.01) more patients were normalized (trough seated diastolic blood pressure < 90 mmHg) with irbesartan/HCTZ (67%) compared with placebo/HCTZ (29%). The frequency of adverse events, serious adverse events, and discontinuations attributed to adverse events was similar in both groups, and there were no clinically relevant changes in serum creatinine, potassium, or any other laboratory parameter.

CONCLUSION

Irbesartan was effective and well tolerated when added to a background of HCTZ 25 mg in patients whose blood pressure was not adequately controlled by HCTZ alone.

During human thymic development, beta 1 integrins regulate adhesion, motility, and the outcome of RHAMM/hyaluronan engagement

During human thymic differentiation, interactions between fibronectin (Fn)/beta1 integrins and hyaluronan (HA)/RHAMM control motility and Fn/beta1 integrins mediate spontaneous Fn-dependent adhesion. Multinegative (MN, CD3-4-8-) thymocytes exhibit strong spontaneous adherence to Fn (75%) that was efficiently inhibited by anti-alpha5beta1 and only weakly inhibited by anti-alpha4beta1. The relatively weak adherence of unfractionated thymocytes to Fn required both alpha4beta1 and alpha5beta1. Video time-lapse microscopy indicates that a subset of thymocytes also undergo spontaneous Fn-dependent motility mediated by alpha5beta1, alpha4beta1, and the HA-receptor RHAMM, but not by CD44. The loss of motility after hyaluronidase treatment of thymocytes indicated that motility is strongly dependent on HA. Of motile cells, 55% were DP, 19% were DN, and 24% were CD4+SP, but only 1% were CD8+SP. Overall, for MN thymocytes, beta1 integrin mediated Fn-adhesion, but after expression of CD4/CD8, beta1 integrins mediated Fn-dependent motility. Treatment with the activating anti-beta1 mAb QE.2E5 inhibited thymic motility and converted otherwise nonadherent thymocytes to an adherent state. High-avidity interactions via integrins appear to supercede the motogenicity of RHAMM and HA, suggesting that integrin avidity may regulate RHAMM. During thymic development, changes in adhesion or motility appear to be mediated by integrin avidity modulation.

Characterization of murine T cell responses to peptides of the variable region of self T cell receptor beta-chains

Immunization with peptides of the TCR may regulate cellular immune responses that are dominated by a particular TCR. However, no extensive study of the immunogenicity of peptides of different regions of the V beta chain of the TCR has been done. We have tested the immunogenicity of several V beta peptides in several strains of mice and characterized the cellular response to these peptides. We examined the ability of six strains of mice of H-2b, H-2d, or H-2k and of mouse lymphocyte stimulatory (Mls)-1a or Mls-1b haplotypes to respond to several peptides of the V beta 6 region and an NH2-terminal peptide of other V beta of the TCR. These include V beta 6 peptides 1-20, 32-48, 39-60, 48-75, 58-75, and V beta 3, V beta 8.1, and V beta 8.3 peptides 1-20. The various mouse strains respond to these peptides independently of deletion of V beta 6+ T cells from peripheral lymphocytes. All of the Mls deleting and nondeleting strains tested respond weakly to one peptide of V beta 6, V beta 6(39-60). Antibody titers were also demonstrated in BALB/c and DBA/2J to V beta 6(1-20), V beta 6(39-60) and V beta 6(48-75), but not to V beta 6(32-48). We demonstrated that T cells responding to V beta 6(32-48) produce IL-2 and IFN-gamma, consistent with the Th1 subset of T cells. None of the antipeptide antibodies recognized the intact V beta 6 TCR on the cell surface. In vitro antibody blocking studies with TCR peptides show that these peptides are presented by class II MHC to CD4+ T cells. We conclude that the T cell and B cell repertoires contain cells able to respond to peptides of self TCR and immunization with peptides induces CD4+ T cells and that these cells may have an immunoregulatory role.

Characterization of murine T cell responses to peptides of the variable region of self T cell receptor beta-chains

Immunization with peptides of the TCR may regulate cellular immune responses that are dominated by a particular TCR. However, no extensive study of the immunogenicity of peptides of different regions of the V beta chain of the TCR has been done. We have tested the immunogenicity of several V beta peptides in several strains of mice and characterized the cellular response to these peptides. We examined the ability of six strains of mice of H-2b, H-2d, or H-2k and of mouse lymphocyte stimulatory (Mls)-1a or Mls-1b haplotypes to respond to several peptides of the V beta 6 region and an NH2-terminal peptide of other V beta of the TCR. These include V beta 6 peptides 1-20, 32-48, 39-60, 48-75, 58-75, and V beta 3, V beta 8.1, and V beta 8.3 peptides 1-20. The various mouse strains respond to these peptides independently of deletion of V beta 6+ T cells from peripheral lymphocytes. All of the Mls deleting and nondeleting strains tested respond weakly to one peptide of V beta 6, V beta 6(39-60). Antibody titers were also demonstrated in BALB/c and DBA/2J to V beta 6(1-20), V beta 6(39-60) and V beta 6(48-75), but not to V beta 6(32-48). We demonstrated that T cells responding to V beta 6(32-48) produce IL-2 and IFN-gamma, consistent with the Th1 subset of T cells. None of the antipeptide antibodies recognized the intact V beta 6 TCR on the cell surface. In vitro antibody blocking studies with TCR peptides show that these peptides are presented by class II MHC to CD4+ T cells. We conclude that the T cell and B cell repertoires contain cells able to respond to peptides of self TCR and immunization with peptides induces CD4+ T cells and that these cells may have an immunoregulatory role.

Inhibition of superantigen recognition by peptides of the variable region of the T cell receptor beta chain

T cells bearing certain variable (V) regions of the T cell receptor (TcR), including V beta 3, V beta 6, V beta 8.1 and V beta 9, are stimulated by one or more forms of the endogenous superantigen, mouse lymphocyte stimulatory (Mls) locus, encoded by the mouse mammary tumor virus, in the context of a non-polymorphic region of the class II molecules of the major histocompatibility complex (MHC). To identify putative sites of interaction of TcR-V beta region and Mls-1a, we examined the effect of peptides derived from the protein sequence of V beta 6 on recognition of Mls-1a by T cell hybridomas and show that three peptides corresponding to amino acid positions 1 to 20, 48 to 75, and 58 to 75 of the V beta 6 peptide sequence interfere with the activation of several V beta 6+ hybridomas by Mls-1a-bearing spleen cells, but not with that of a V beta 8+ hybridoma. The Mls-reactive hybridomas are specific for a synthetic peptide poly-18, poly EYK(EYA)5 and its peptide (EYA)5, in the context of I-Ad. This peptide does not require processing and the peptides 1-20, 48-75, and 58-75 do not inhibit recognition of (EYA)5 by the same V beta 6+ T cell hybridomas. The two sequences 1-20 and 58-75 are proposed to lie outside the putative binding domain of processed antigen, indicating that recognition by TcR of Mls-1a is different from the classical MHC-restricted recognition of processed antigen. These results suggest that the recognition of superantigen/class II MHC by T cells can be inhibited by peptides related to the site of interaction of the TcR, suggesting that such peptides could have possible regulatory effects on the induction and regulation of immune responses.

Correction of defective IL 3 responses of T lymphocytes from autoimmune mice

MRL-+ and MRL-lpr congenic mice differ by the presence and expression of the homozygous recessive lymphoproliferation (lpr) gene. One manifestation of this gene is a massive T cell proliferation that results in a generalized lymphadenopathy in older animals. Interleukin 3 (IL 3), a recently described lymphokine, has been shown to influence lymphocyte differentiation. It was possible that abberrant IL 3 production was the mechanism responsible for the lpr controlled lymphadenopathy. Consequently, in this paper we tested the MRL congenic mice for their ability to produce IL 3. We report that the T lymphocytes from MRL-+ and MRL-lpr could neither respond to pokeweed mitogen in the induction of proliferation nor produce IL 3. Moreover, IL 3 was not produced constitutively nor could be induced at any time period up to 5 days in vitro. This hyporesponsiveness was shown to be controlled at the accessory cell level. Addition of T cell-depleted peritoneal exudate cells from normal major histocompatibility complex (MHC) compatible mice was able to restore the ability to secrete IL 3 in response to pokeweed mitogen in MRL-+ and young MRL-lpr mice. The defect in the accessory cells could be overridden by two means: the incorporation of phorbol myristate acetate in the induction system and preincubation of the cells in tissue culture.

Correction of defective IL 3 responses of T lymphocytes from autoimmune mice

MRL-+ and MRL-lpr congenic mice differ by the presence and expression of the homozygous recessive lymphoproliferation (lpr) gene. One manifestation of this gene is a massive T cell proliferation that results in a generalized lymphadenopathy in older animals. Interleukin 3 (IL 3), a recently described lymphokine, has been shown to influence lymphocyte differentiation. It was possible that abberrant IL 3 production was the mechanism responsible for the lpr controlled lymphadenopathy. Consequently, in this paper we tested the MRL congenic mice for their ability to produce IL 3. We report that the T lymphocytes from MRL-+ and MRL-lpr could neither respond to pokeweed mitogen in the induction of proliferation nor produce IL 3. Moreover, IL 3 was not produced constitutively nor could be induced at any time period up to 5 days in vitro. This hyporesponsiveness was shown to be controlled at the accessory cell level. Addition of T cell-depleted peritoneal exudate cells from normal major histocompatibility complex (MHC) compatible mice was able to restore the ability to secrete IL 3 in response to pokeweed mitogen in MRL-+ and young MRL-lpr mice. The defect in the accessory cells could be overridden by two means: the incorporation of phorbol myristate acetate in the induction system and preincubation of the cells in tissue culture.

Role of the Escherichia coli glnALG operon in regulation of ammonium transport

Escherichia coli expresses a specific ammonium (methylammonium) transport system (Amt) when cultured with glutamate or glutamine as the nitrogen source. Over 95% of this Amt activity is repressed by growth of wild-type cells on media containing ammonia. The control of Amt expression was studied with strains containing specific mutations in the glnALG operon. GlnA- (glutamine synthetase deficient) mutants, which contain polar mutations on glnL and glnG genes and therefore have the Reg- phenotype (fail to turn on nitrogen-regulated operons such as histidase), expressed less than 10% of the Amt activity observed for the parental strain. Similarly, low levels of Amt were found in GlnG mutants having the GlnA+ Reg- phenotype. However, GlnA- RegC mutants (a phenotype constitutive for histidase) contained over 70% of the parental Amt activity. At steady-state levels, GlnA- RegC mutants accumulated chemically unaltered [14C]methylammonium against a 60- to 80-fold concentration gradient, whereas the labeled substrate was trapped within parental cells as gamma-glutamylmethylamide. GlnL Reg- mutants (normal glutamine synthetase regulation) had less than 4% of the Amt activity observed for the parental strain. However, the Amt activity of GlnL RegC mutants was slightly higher than that of the parental strain and was not repressed during growth of cells in media containing ammonia. These findings demonstrate that glutamine synthetase is not required for Amt in E. coli. The loss of Amt in certain GlnA- strains is due to polar effects on glnL and glnG genes, whose products are involved in expression of nitrogen-regulated genes, including that for Amt.

Fine-structure deletion map and complementation analysis of the glnA-glnL-glnG region in Escherichia coli

A total of 399 independent mutants of Escherichia coli were obtained which have point and insertion mutations in the glnA region. Mutants isolated included Gln- and Reg- strains (unable to utilize arginine as a nitrogen source). Mutations were mapped with 73 deletion-containing derivatives of a lambda gln phage. Complementation analysis was performed with lambda gln derivatives containing point mutations which conferred a Gln- or Reg- phenotype. Deletion mapping and complementation analysis assigned 104 mutations in 24 deletion intervals to glnA. Mutations in Reg- strains were assigned to two genes, glnL and glnG. glnL contained 131 mutations in 12 deletion intervals, and glnG contained 164 mutations in 10 deletion intervals. The gene order is glnA-glnL-glnG, transcribed from left to right. Polarity of insertion mutations indicates that glnL and glnG form from left to right. Polarity of insertion mutations indicates that glnL and glnG form an operon. Complementation analysis of glnA insertion mutations with glnL and glnG mutations showed polarity of glnA onto most glnL and glnG alleles, suggesting that transcription of glnA may proceed into the glnL-glnG operon. All mutations analyzed in glnA conferred a Gln- phenotype. However, we also found that over half of the Gln- strains isolated ater chemical mutagenesis contained point mutations in glnG. Mutants which synthesized a high level of glutamine synthetase in the presence of ammonia (GlnC phenotype) were selected as revertants of a strain with a Tn10 insertion in glnD and were mapped with chromosomal deletions. Results indicate that mutations in 12 and 15 examined strains clearly map outside of glnA, probably in glnL.

General method, using Mu-Mud1 dilysogens, to determine the direction of transcription of and generate deletions in the glnA region of Escherichia coli

A general, genetic technique for determining the direction of transcription for bacterial genes is presented. By comparing the phenotype of Mu-Mud1 dilysogens with the phenotype of deletion-containing derivatives, the direction of transcription for the gene containing Mud1 can be unambiguously determined. This method can generate a series of strains containing deletions with predetermined endpoints, and strains with duplications of the region containing the Mud1 insertion. In Escherichia coli, the glnA and glnG genes are transcribed in the same direction.

Regulation of nitrogen fixation in Klebsiella pneumoniae: isolation and characterization of strains with nif-lac fusions

Strains with lac fused to each of the seven nif operons were isolated by two different methods. Repressing conditions prevented expression of all nif operons, whereas derepressing conditions led to the expression of all nif operons. No differences in Nif regulation were observed between Escherichia coli and Klebsiella pneumoniae with the same nif-lac fusions. Most derivatives of nif-lac fusion strains selected on lactose and NH4+ contained nif operator mutations. Some derivative contained deletions, which establishes that the direction of transcription of all seven nif operons is toward his

Mutations in nif genes that cause Klebsiella pneumoniae to be derepressed for nitrogenase synthesis in the presence of ammonium

Four Nif+ revertants from strains with polar insertions in nifL, were insensitive to ammonium and amino acid repression of nitrogenase synthesis. These strains have mutations located in or near the nifL region. The derepressed phenotype was dominant in a merodiploid containing a nif+ plasmid. These nif regulatory mutations also suppressed the Nif- phenotype of Gln- strains. Thus, regulation by fixed nitrogen (possible via glutamine synthetase) occurs on the nifLA operon but not on the other six nif operons.

Isolation and characterization of lambda specialized transducing bacteriophages carrying Klebsiella pneumoniae nif genes

Seve lambda dnif specialized transducing bacteriophages were isolated from Escherichia coli strains containing plasmids carrying the his-nif region of Klebsiella pneumoniae. These phages collectively carry deoxyribonucleic acid for all of the genes in the nif regulon and adjacent deoxyribonucleic acid of K. pneumoniae. The phages were isolated by using Mu insertions in the nif region to direct the integration of lambda pMu phages in nif via formation of lambda pMu-Mu dilysogens which, upon induction, yielded lambda dnif phages. This procedure should be generally applicable for isolating lambda specialized transducing phages carrying genes from E. coli or other bacteria.

Order of genes near nif in Klebsiella pneumoniae

Analysis of strains with deletions of all or part of nif have ordered the Klebsiella pneumoniae genetic loci as thi rbt dal udk gnd rfb has nif shiA. The his-nif plasmids pRD1 and pTM4010 contain the genes gnd rfb his nif shiA.

Fine-structure mapping and complementation analysis of nif (nitrogen fixation) genes in Klebsiella pneumoniae

Four hundred and eighty-nine independent Nif- strains containing 260 point, 130 millimicron-induced, and 99 deletion mutations in nif in the Klebsiella pneumoniae chromosome were isolated. Three hundred and ninety insertion and point mutations were mapped with millimicron-induced deletions carried on 44 plasmids derived from pTM4010, a recombinant R factor containing the his-nif region of K. pneumoniae. The 99 chromosomal deletions in the nif region were mapped with 69 derivatives of pTM4010 carrying insertion and point mutations in nif. Complementation analysis between 84 derivatives of pTM4010 carrying nif mutations and Rec- derivatives of the 390 Nif- mutants identified 14 genes. The nif mutations were ordered into 49 deletion groups with a gene order of his...nifQBALFMVSNEKDHJ. Complementation analysis of millimicron-induced, amber, frameshift, and deletion mutations indicates there are five polycistronic and two monocistronic operons: nifQ nifB, nifA nifL, nifF, nifM nifV nifS, nifN nifE, nifK nifD nifH, and nifJ. Transcription is from right to left in all polycistronic operons.

6-cyanopurine, a color indicator useful for isolating mutations in the nif (nitrogen fixation) genes of Klebsiella pneumoniae

6-Cyanopurine (6-CP) can be used as a color indicator for certain classes of nif (N2 fixation) mutations in Klebsiella pneumoniae. Under N2-fixing conditions, Nif+ colonies and most Nif- colonies are purple on media containing 6-CP. Twenty-two Nif- mutants with altered color on medium containing 6-CP were isolated. All white mutants contained mutations in the regulatory genes, nifAA-nifL. Mutants which were more darkly colored than the wild type had mutations distributed among six nif genes. Medium with 6-CP was used to isolate Nif- mutants with deletions internal to the nif genes, and 6-CP was used to identify strains depressed for nitrogenase synthesis in the presence of NH4+.

Regulation and characterization of protein products coded by the nif (nitrogen fixation) genes of Klebsiella pneumoniae

Two hundred and thirty-five Nif- strains of Klebsiella pneumoniae were characterized by two-dimensional polyacrylamide gel electrophoresis. Forty-two of these strains were tested further by in vitro acetylene reduction assays. By these techniques, nine nif-coded polypeptides were identified, and eight of these were assigned to specific nif genes. Nitrogenase component I required nifK and nifD, which coded for the beta and alpha subunits, and nifB, -E, and -N were required for the iron-molybdenum cofactor, which is a part of the active site of nitrogenase. nifH coded for the structural protein of component II, and nifM and nifS products seemed to be necessary for the synthesis of an active component II. There were two genes, nifF and nifJ, that were required for N2 fixation in vivo but not for N2 fixation in vitro. There were at least two cases (nifE and nifN, nifK and nifD) of two proteins that seemed to require each other for stability in vivo. Regulation of N2 fixation is apparently complex, and this is reflected by the assignment of regulatory functions to the gene products of nifA, nifL, nifK, nifD, nifH, and NIFJ.

Terminal redundancy heterozygotes involving the first-step-transfer region of the bacteriophage T5 chromosome

Individual progeny of two-factor crosses between A1am and A2am T5 phages give rise to bursts containing more than one type of plaque. The simplest explanation for these mixed bursts is that the A1 and A2 genes are located within the terminally repeated portion of the T5 genome and that the mixed bursts are made by "terminal redundancy heterozygotes". The observation of genetic heterozygosity means that the A1 and A2 genes are repeated intact. This implies that the terminal segments of T5 are genetically interchangeable.