Relapse after withdrawal from anti-TNF therapy for inflammatory bowel disease: an observational study, plus systematic review and meta-analysis

BACKGROUND

Infliximab and adalimumab have established roles in inflammatory bowel disease (IBD) therapy. UK regulators mandate reassessment after 12 months' anti-TNF therapy for IBD, with consideration of treatment withdrawal. There is a need for more data to establish the relapse rates following treatment cessation.

AIM

To establish outcomes following anti-TNF withdrawal for sustained remission using new data from a large UK cohort, and assimilation of all available literature for systematic review and meta-analysis.

METHODS

A retrospective observational study was performed on 166 patients with IBD (146 with Crohn's disease (CD) and 20 with ulcerative colitis [UC) and IBD unclassified (IBDU)] withdrawn from anti-TNF for sustained remission. Meta-analysis was undertaken of all published studies incorporating 11 further cohorts totalling 746 patients (624 CD, 122 UC).

RESULTS

Relapse rates in the UK cohort were 36% by 1 year and 56% by 2 years for CD, and 42% by 1 year and 47% by 2 years for UC/IBDU. Increased relapse risk in CD was associated with age at diagnosis [hazard ratio (HR) 2.78 for age <22 years], white cell count (HR 3.22 for >5.25 × 109 /L) and faecal calprotectin (HR 2.95 for >50 μg/g) at drug withdrawal. Neither continued immunomodulators nor endoscopic remission were predictors. In the meta-analysis, estimated 1-year relapse rates were 39% and 35% for CD and UC/IBDU respectively. Retreatment with anti-TNF was successful in 88% for CD and 76% UC/IBDU.

CONCLUSIONS

Assimilation of all available data reveals remarkable homogeneity. Approximately one-third of patients with IBD flare within 12 months of withdrawal of anti-TNF therapy for sustained remission.

Effect of very high dose D-leucine6-gonadotropin-releasing hormone proethylamide on the hypothalamic-pituitary testicular axis in patients with prostatic cancer

Potent synthetic analogs of gonadotropin-releasing hormone produce parodoxical antireproductive effects when administered chronically. These compounds are minimally toxic and may exhibit no plateau of the dose-response curve even at very high doses. These considerations served as the basis for our systematic evaluation of [D-leucine6-desarginine-glycine-NH2(10)]gonadotropin-releasing hormone (GnRH-A) proethylamide in the very high dose range (i.e., 10-fold larger amounts than previously used). In rats given the analog for 12 wk, prostate, testis, and seminal vesicle weights were suppressed to a greater extent with 200 micrograms q.d. than with 40 micrograms q.d. (P less than 0.01 prostate, less than 0.01 testis, less than 0.01 seminal vesicles), indicating dose-response effects in the very high dose range. 200 micrograms of [D-Leu6-des-Gly-NH2(10]-GnRH-A consistently suppressed leutinizing hormone (LH) values at 6 and 12 wk (basal 71 +/- 9.5; 6 wk 34 +/- 3.8; 12 wk 28 +/- 5 ng/ml) whereas 40 micrograms suppressed LH variably (basal 33 +/- 3.8; 6 wk 17 +/- 3.9; 12 wk 32 +/- 5.2). Testosterone fell to 15 +/- 2.4 and 19 +/- 2.0 ng/100 ml in response to 200 micrograms q.d. and to 27 +/- 6.4 and 22 +/- 7.4 ng/100 ml with the 40-micrograms dose. These findings in the rodent prompted treatment of stage D prostate cancer patients with similarly high doses of [D-Leu6-des-Gly-NH2(10)]-GnRH-A. After treatment for 11 wk with 1,000 or 10,000 micrograms/d of the analog, testosterone and dihydrotestosterone levels transiently rose and then fell into the surgically castrate range (testosterone 19 +/- 4.4 ng/100 ml [D-Leu6-des-Gly-NH2(10)]-GnRH-A vs. surgically castrate 11 +/- 0.9 ng/100 ml, P = NS; dihydrotestosterone 15 +/- 1.7 ng/100 ml GnRH-A vs. surgically castrate 15 +/- 4.1 ng/100 ml. P = NS). However, unlike the chronic stimulatory effect on the pituitary at lower doses, very high dose therapy resulted in profound suppression of plasma and urine LH. Plasma levels fell to the limit of assay detectability, whereas the more sensitive urinary assay detected prepubertal levels of excretion (i.e., 64 +/- 8.4 mlU/h). The highly sensitive rat interstitial cell testosterone bioassay for LH also demonstrated a marked decline in LH to undetectable levels in 17/19 subjects. Clinical results with [D-Leu6-des-Gly-NH2(10)]-GnRH-A simulate those achieved by surgical castration in men with prostatic cancer as suggested by available preliminary data.

The prevalence of venous thromboembolism of the lower extremity among thermally injured patients determined by duplex sonography

BACKGROUND

Morbidity and mortality from venous thromboembolism (VTE) remains a significant problem for hospitalized patients. Despite the ample prospective literature defining the prevalence of VTE in hospitalized patient populations, the prevalence of VTE in the thermally injured population remains largely unknown.

METHODS

We prospectively studied 148 thermally injured patients with hospital stays of greater than 3 days with lower extremity duplex ultrasonograms obtained at admission and discharge.

RESULTS

Nine patients experienced VTE (6.08%). Eight of the nine deep venous thromboses were proximal. One of the two pulmonary embolisms was fatal. Treatment risk factors that were associated with VTE were the presence of a central venous line (p = 0.020) and transfusion of more than 4 units of packed red blood cells (p = 0.023). These treatment factors were significantly related to each other (p < 0.0001), to body surface area burned, and to intervention.

CONCLUSION

The prevalence of VTE in burn patients is similar to that of moderate- to high-risk general surgical patients for whom VTE prophylaxis is recommended. VTE prophylaxis of burn patients, especially those requiring central venous lines and more than 4 units of packed red blood cells, should be considered.

Thiopurine withdrawal during sustained clinical remission in inflammatory bowel disease: relapse and recapture rates, with predictive factors in 237 patients

BACKGROUND

Thiopurines (azathioprine and mercaptopurine) remain integral to most medical strategies for maintaining remission in Crohn's disease (CD) and ulcerative colitis (UC). Indefinite use of these drugs is tempered by long-term risks. While clinical relapse is noted frequently following drug withdrawal, there are few published data on predictive factors.

AIM

To investigate the success of planned thiopurine withdrawal in patients in sustained clinical remission to identify rates and predictors of relapse.

METHODS

This was a multicentre retrospective cohort study from 11 centres across the UK. Patients included had a definitive diagnosis of IBD, continuous thiopurine use ≥3 years and withdrawal when in sustained clinical remission. All patients had a minimum of 12 months follow-up post drug withdrawal. Primary and secondary end points were relapse at 12 and 24 months respectively.

RESULTS

237 patients were included in the study (129 CD; 108 UC). Median duration of thiopurine use prior to withdrawal was 6.0 years (interquartile range 4.4-8.4). At follow-up, moderate/severe relapse was observed in 23% CD and 12% UC patients at 12 months, 39% CD and 26% UC at 24 months. Relapse rate at 12 months was significantly higher in CD than UC (P = 0.035). Elevated CRP at withdrawal was associated with higher relapse rates at 12 months for CD (P = 0.005), while an elevated white cell count was predictive at 12 months for UC (P = 0.007).

CONCLUSION

Thiopurine withdrawal in the context of sustained remission is associated with a 1-year moderate-to-severe relapse rate of 23% in Crohn's disease and 12% in ulcerative colitis.

Milnacipran efficacy in the prevention of recurrent depression: a 12-month placebo-controlled study. Milnacipran recurrence prevention study group

To compare the efficacy and assess the tolerability of milnacipran 50mg p.o. b.i.d. to placebo in the prevention of recurrence in depressed patients who had responded an acute treatment and had remained in remission during a 4-month continuation phase. Remission criteria were: a Hamilton Depression Rating Scale (HDRS) (21-item) < or = 8, improvement or disappearance of the initial symptoms, and an assessment of 'very much improved' or 'much improved' on the Clinical Global Impression (CGI) Subscale: Global Improvement. Recurrence was defined by a major depressive episode according to DSM-III-R criteria and a minimum score of 18 on the HDRS, with the need to treat the recurrence. The primary analysis was the rate of recurrence as a function of time in the intent-to-treat population. Groups were compared using the Cox model. Absolute recurrence rates were 16.3% (17/104) in milnacipran-treated patients and 23.6% (26/110) in placebo-treated patients, with a significant difference in the reduction of recurrence as a function of time (Kaplan Meier Survival Analysis analysis, P < 0.05). There was no difference in tolerability between groups. This study demonstrates that milnacipran is effective with good tolerability in preventing recurrence in major depressive disorder over 1 year in patients with recurrent depression who responded to acute treatment with milnacipran and continued their response for 18 weeks.

Apollo 11 Laser Ranging Retro-Reflector: Initial Measurements from the McDonald Observatory

Acquisition measurements of the round-trip travel time of light, from the McDonald Observatory to the Laser Ranging Retro-Reflector deployed on the moon by the Apollo 11 astronauts, were made on 20 August and on 3, 4, and 22 September 1969. The uncertainty in the round-trip travel time was +/- 15 nanoseconds, with the pulsed ruby laser and timing system used for the acquisition. The uncertainty in later measurements of a planned long-term sequence from this observatory is expected to be an order of magnitude smaller. The successful performance of the retro-reflector at several angles of solar illumination, as well as during and after a lunar night, confirms the prediction of thermal design analyses.

Prevention of recurrent depressive episodes with milnacipran: consequences on quality of life

BACKGROUND

Depression is now seen as a chronic disabling condition that spans the patient's lifetime and creates significant medical, economic and quality of life consequences.

METHODS

500 depressed patients were treated with milnacipran for 6 months. A total of 214 recovered patients were randomised to receive either milnacipran (50 mg bid) or a matching placebo for a 1-year recurrence prevention phase. Recurrence rate was the primary criteria; quality of life (QoL) consequences were evaluated through a shortened version of the French Sickness Impact Profile (SIP), the Depression Impact Profile (DIP).

RESULTS

Milnacipran demonstrated its ability to reduce recurrences (Odds-Ratio=1.5; P<0.05), with a more marked effect in recovered patients with few residual symptoms (Odds-Ratio=3.0). Responders who continued treatment with milnacipran had a dramatic improvement in their quality of life, although patients with residual symptoms still experienced some deterioration in their QoL (recreation, emotional, social, alertness and home assistance scores). Even recovered patients having zero scores on the Hamilton Depression Rating Scale-21 items (HDRS) had some QoL deterioration. The DIP emotional score was found to be more predictive of recurrence than the HDRS. Overall, the QoL was improved for those in the milnacipran group in comparison to placebo on the mobility, communication, psycho-social and total scores.

LIMITATIONS

The QoL evaluation was a secondary criteria; no a priori sample size estimate was performed. The choice of a generic QoL instrument might have reduced the sensitivity to clinical changes in depression.

CONCLUSIONS

Prevention of recurrence in MDD with milnacipran contributes to an improvement in the QoL.

Implementation of HaemScreen, a workplace-based genetic screening program for hemochromatosis

There is debate as to whether community genetic screening for the mutation(s) causing hereditary hemochromatosis (HH) should be implemented, due to issues including disease penetrance, health economic outcomes, and concerns about community acceptance. Hemochromatosis is a common preventable iron overload disease, due in over 90% of cases to C282Y homozygosity in the HFE gene. We are, therefore, piloting C282Y screening to assess understanding of genetic information and screening acceptability in the workplace setting. In this program, HaemScreen, education was by oral or video presentation in a group setting. C282Y status was assessed by polymerase chain reaction (PCR) and melt-curve analysis on DNA obtained by cheek-brush sampling. Of eligible participants, 5.8% (1.5-15.8%) attended information and screening sessions, of whom 97.7% (5571 individuals) chose to be tested. Twenty-two C282Y (1 : 253) homozygotes were identified and offered clinical follow-up. There were 638 heterozygotes (1 : 8.7). The determinants for participation have been analyzed in terms of the principles outlined in the Health Belief Model. Widespread screening for HH is readily accepted in a workplace setting, and a one-to-many education program is effective. The level of participation varies greatly and the advertizing and session logistics should be adapted to the specific features of each workplace.

Infliximab and adalimumab drug levels in Crohn's disease: contrasting associations with disease activity and influencing factors

BACKGROUND

Discriminative drug level thresholds for disease activity endpoints in patients with Crohn's disease. have been consistently demonstrated with infliximab, but not adalimumab.

AIMS

To identify threshold concentrations for infliximab and adalimumab in Crohn's disease according to different disease endpoints, and factors that influence drug levels.

METHODS

We performed a cross-sectional service evaluation of patients receiving maintenance infliximab or adalimumab for Crohn's disease. Serum drug levels were at trough for infliximab and at any time point for adalimumab. Endpoints included Harvey-Bradshaw index, C-reactive protein and faecal calprotectin. 6-tioguanine nucleotide (TGN) concentrations were measured in patients treated with thiopurines.

RESULTS

A total of 191 patients (96 infliximab, 95 adalimumab) were included. Differences in infliximab levels were observed for clinical (P=.081) and biochemical remission (P=.003) and faecal calprotectin normalisation (P<.0001) with corresponding thresholds identified on ROC analysis of 1.5, 3.4 and 5.7 μg/mL. Adalimumab levels were similar between active disease and remission regardless of the endpoint assessed. Modelling identified that higher infliximab dose, body mass index and colonic disease independently accounted for 31% of the variation in infliximab levels, and weekly dosing, albumin and weight accounted for 23% of variation in adalimumab levels. TGN levels did not correlate with drug levels.

CONCLUSIONS

Infliximab drug levels are associated with the depth of response/remission in patients with Crohn's disease, but no such relationship was observed for adalimumab. More data are needed to explain the variation in drug levels.

Accelerated photobleaching of a cyanine dye in the presence of a ternary target DNA, PNA probe, dye catalytic complex: a molecular diagnostic

In many settings, molecular testing is needed but unavailable due to complexity and cost. Simple, rapid, and specific DNA detection technologies would provide important alternatives to existing detection methods. Here we report a novel, rapid nucleic acid detection method based on the accelerated photobleaching of the light-sensitive cyanine dye, 3,3'-diethylthiacarbocyanine iodide (DiSC(2)(3) I(-)), in the presence of a target genomic DNA and a complementary peptide nucleic acid (PNA) probe. On the basis of the UV-vis, circular dichroism, and fluorescence spectra of DiSC(2)(3) with PNA-DNA oligomer duplexes and on characterization of a product of photolysis of DiSC(2)(3) I(-), a possible reaction mechanism is proposed. We propose that (1) a novel complex forms between dye, PNA, and DNA, (2) this complex functions as a photosensitizer producing (1)O(2), and (3) the (1)O(2) produced promotes photobleaching of dye molecules in the mixture. Similar cyanine dyes (DiSC(3)(3), DiSC(4)(3), DiSC(5)(3), and DiSC(py)(3)) interact with preformed PNA-DNA oligomer duplexes but do not demonstrate an equivalent accelerated photobleaching effect in the presence of PNA and target genomic DNA. The feasibility of developing molecular diagnostic assays based on the accelerated photobleaching (the smartDNA assay) that results from the novel complex formed between DiSC(2)(3) and PNA-DNA is under way.

Benefits of multidisciplinary case conferencing using audiovisual compared with telephone communication: a randomized controlled trial

Multidisciplinary case conferencing using a video-link was compared with multidisciplinary case conferencing by telephone. One hundred patients were randomized to either videoconferencing (intervention group, 50 patients) or audioconferencing (control group, 50 patients). The effectiveness of the intervention compared with the control was evaluated in terms of: the number of conferences per patient, average length of conference, length of treatment, number of occasions of service, degree of multidisciplinary team involvement, recorded level of communication, quality of the management plan (in terms of the number of points contained in it) and staff satisfaction. The intervention and control groups showed significant differences on only two of the outcome measures: the mean number of case conferences per patient was less for the intervention group, and the intervention group had a shorter length of treatment (6 days) than the control group (10 days). The study did not demonstrate any significant differences in occasions of service or time commitment, which might have resulted in lower costs. However, the introduction of case conferencing by video-link was accompanied by a high level of satisfaction on the part of the 14 team members who were interviewed.

Application of a rapid non-radioisotopic nucleic acid analysis system to the detection of sexually transmitted disease-causing organisms and their associated antimicrobial resistances

We devised a versatile method for detecting nucleic acids in crude lysates of biological samples. A controlled network of nucleic acid hybrids composed of the target fragment, several oligonucleotide probes, branched DNA amplifiers, and labeled oligonucleotides is produced on a solid phase to ultimately incorporate 60 to 300 molecules of alkaline phosphatase, which are detected with a chemiluminescent substrate. The visible light output can be recorded on a luminometer or on instant black-and-white film. Assays have been developed for the detection of Chlamydia trachomatis, Neisseria gonorrhoeae, and for genes conferring penicillin and tetracycline resistance. Conducted much like ELISAS, the assays are performed in about 4 h (for 96 samples) in microliter dishes. The molecular detection limit of approximately 50,000 molecules of double-stranded DNA has permitted us to detect 1 to 10 x 10(3) of C. trachomatis and N. gonorrhoeae with specific probe sequences. Both plasmid and genomic target sequences can be detected by the same procedure. All of the assay components, except for a set of unmodified oligonucleotide probes, are universally applicable for all targets.

Crimean-Congo haemorrhagic fever virus: Past, present and future insights for animal modelling and medical countermeasures

Crimean–Congo haemorrhagic fever (CCHF) is a widespread tick‐borne viral zoonosis with a case‐fatality rate ranging from 9% to 50% in humans. Although a licensed vaccine to prevent infection by the CCHF virus (CCHFV) exists, its ability to induce neutralizing antibodies is limited and its efficacy against CCHFV remains undetermined. In addition, controlling CCHF infections by eradication of the tick reservoir has been ineffective, both economically and logistically, and the treatment options for CCHF remain limited. In this review, we first critically discuss the existing animal models to evaluate therapeutics for CCHF. We then review the therapeutic options for CCHF that have been investigated in human cases, followed by investigational drugs that have been evaluated in pre‐clinical studies. We highlight the importance of understanding human prognostic factors in developing an animal model for CCHF that recapitulates hallmarks of human disease and its implication for selecting therapeutic candidates.

HCV Infection Alters Salivary Gland Histology and Saliva Composition

Hepatitis C virus (HCV) infection is the most common blood-borne chronic infection in the United States. Chronic lymphocytic sialadenitis and sicca syndrome have been reported in chronic HCV infection. Up to 55% of these patients may have xerostomia; the mechanisms of the xerostomia and salivary gland (SG) hypofunction remain controversial. The objectives of this project are to establish if xerostomia associates with SG and HCV infection and to characterize the structural changes in SG and saliva composition. Eighteen HCV-infected patients with xerostomia were evaluated for SG dysfunction; 6 of these patients (patients 1–6) were further evaluated for SG histopathological changes and changes in saliva composition. The techniques used include clinical and laboratory assessment, SG ultrasonography, histological evaluation, sialochemical and proteomics analysis, and RNA in situ hybridization. All the HCV patients had low saliva flow, chronic sialadenitis, and SG fibrosis and lacked Sjögren syndrome (SS) characteristic autoantibodies. Further evaluation of a subgroup of 6 HCV patients (patients 1–6) demonstrated diffuse lymphocytic infiltrates that are predominantly CD8+ T cells with a significant increase in the number of inflammatory cells. Alcian Blue/periodic acid–Schiff staining showed significant changes in the ratio and intensity of the acinar secretory units of the HCV patients’ minor SG. The submandibular glands showed significant ultrasonographic abnormalities in the parenchyma relative to the parotid glands. Significant changes were also observed in the concentration of sodium and mucin 5b. Although no significant correlation was observed between the lymphocytic infiltrates and the years of HCV chronic infection, a positive correlation was observed between HCV RNA–positive epithelial cells and the years of HCV infection. Consistent with the low saliva flow and xerostomia, patients showed changes in several markers of SG acinar and ductal function. Changes in the composition of the saliva suggest that HCV infection can cause xerostomia by mechanisms distinct from SS.

The isolation of Plesiomonas shigelloides in polymicrobial septicaemia originating from the biliary tree

The first two cases are reported in which Plesiomonas shigelloides was isolated from patients with mixed aerobic/anaerobic septicaemia originating from the biliary tree. The first patient who was previously well survived after removal of a gangrenous gallbladder. The second patient suffered from an extrahepatic cholangiocarcinoma and died of infection thus highlighting the poor prognostic outcome of P. shigelloides septicaemia in immunocompromised patients. Furthermore these cases demonstrate that P. shigelloides can be isolated from mixed infections and may act synergistically with other bacteria to produce disease.

Prolactin-independent induction of alpha-lactalbumin gene expression in mammary gland explants from pregnant Balb/c mice

A four-fold increment of alpha-lactalbumin mRNA was induced in mammary gland explants from mid-pregnant Balb/c mice cultured for 24h in media containing insulin, cortisol and T3, and this response was enhanced by 40% with the addition of prolactin. In contrast, elevated beta-casein gene expression was evident only in explants cultured in media with insulin, cortisol, T3 and prolactin. These results suggest that the induction of the alpha-lactalbumin gene was prolactin-independent and did not result from retention of endogenous prolactin, or its effects, by the mammary explants.

UK dogs eating raw meat diets have higher risk of Salmonella and antimicrobial-resistant Escherichia coli faecal carriage

Objectives

To compare detection of Salmonella species and antimicrobial‐resistant Escherichia coli in the faeces of dogs eating raw meat or non‐raw diets and examine risk factors for their carriage.

Materials and Methods

Canine faecal samples (raw fed n=114; non‐raw fed n=76) were collected from May to July 2015 from across the UK. Enrichment and selective culture and biochemical and PCR assays were used to identify isolates. Escherichia coli underwent susceptibility testing to a range of antimicrobials, including third‐generation cephalosporins; PCR assays were used to detect antimicrobial‐resistant genes. Questionnaires were used to collect data on independent variables as risks for antimicrobial‐resistant (resistant to ≥1 tested antimicrobial), multi‐drug‐resistant (resistant to ≥3 antimicrobial classes) and third‐generation cephalosporin resistant Escherichia coli.

Results

Antimicrobial‐resistant, multi‐drug‐resistant and third‐generation cephalosporin resistant Escherichia coli were significantly more likely to be detected in raw fed (54, 25 and 31%, respectively) compared to non‐raw fed (17, 4 and 4%, respectively) dogs; Salmonella species were detected in eight (4%) raw fed dogs only.

Clinical Significance

Raw fed dogs may be a source of Salmonella species and Escherichia coli, resistant to highest priority critically important antimicrobials, representing a potential animal welfare and public health issue. Owners should be aware of the risks, especially households with members, both human and canine, who are very young, elderly or immunocompromised.

Neonatal thermoregulation: bed surface transfers

PURPOSE

To describe temperature changes that occur in preterm infants following bed surface transfers.

DESIGN

The design was descriptive.

SAMPLE

The convenience sample was comprised of 20 preterm infants (< 1,500 gm birth weight).

MAIN OUTCOME VARIABLE

Temperature stability after a bed transfer (i.e., radiant warmer to incubator) was the main outcome variable.

RESULTS

There were no significant differences in temperatures after bed surface transfer. However, the temperatures one hour after bed surface transfer were lower than baseline temperature before bed surface transfer.

Attitudes towards the role of women in Cuban women attending a community college

The study examines both the attitudes towards the role of women in society and the psychological masculinity/femininity manifested by a small group of Cuban-American college women. In Miami, 31 such women completed the Attitudes Towards Women Scale and the Personal Attributes Questionnaire. Overall, the means for this group corresponded with the established American norms. The authors thought that age, number of years in the U.S., mother's educational level, position in family and relative fluency of English would affect both AWS and PAQ scores. Only the last variable appeared to have an impact, with those women who reported fluency in both English and Spanish obtaining more liberal AWS scores than those who reported being less fluent in English.

Clinical accuracy of capillary blood glucose monitoring in hospitalized patients with diabetes

This study evaluated the clinical accuracy of capillary blood glucose monitoring (CBGM) performed by nursing personnel on hospitalized patients with diabetes. We compared the results of 80 serum glucose samples obtained in a blinded fashion within 5 minutes of routine capillary glucose measurements performed during the course of clinical care. The CBGM results obtained by a diabetes nurse specialist during endocrine testing procedures were correlated with the serum results. Correlation of CBGM to serum glucose ranged from .74 to .99 depending on the method used. Visual and manual interpretation yielded the lowest correlation and variable accuracy results, per error grid analysis, with 1 in 4 patients having errors of sufficient magnitude that could lead to inappropriate therapy. Monitoring with the AccuChek II blood glucose meter produced the highest correlation and most accurate clinical readings. Bedside blood glucose monitoring of inpatients has a wide range of reliability depending on the method used.

DQ Herculis: Synchronous Photometry

Synchronous signal averaging, applied to the photometry of the steller system DQ Herculis in order to study the 71.1-second pulsations discovered by Walker in 1956, yields a light curve which is a pure sinusoid, within the accuracy of measurement. The binary period is increasing, probably as a result of mass lost from the system.