Human gut Actinobacteria boost drug absorption by secreting P-glycoprotein ATPase inhibitors.

Drug efflux transporters are a major determinant of drug efficacy and toxicity. A canonical example is P-glycoprotein (P-gp), an efflux transporter that controls the intestinal absorption of diverse compounds. Despite a rich literature on the dietary and pharmaceutical compounds that impact P-gp activity, its sensitivity to gut microbial metabolites remains an open question. Surprisingly, we found that the cardiac drug-metabolizing gut Actinobacterium Eggerthella lenta increases drug absorption in mice. Experiments in cell culture revealed that E. lenta produces a soluble factor that post-translationally inhibits P-gp ATPase efflux activity. P-gp inhibition is conserved in the Eggerthellaceae family but absent in other Actinobacteria. Comparative genomics identified genes associated with P-gp inhibition. Finally, activity-guided biochemical fractionation coupled to metabolomics implicated a group of small polar metabolites with P-gp inhibitory activity. These results highlight the importance of considering the broader relevance of the gut microbiome for drug disposition beyond first-pass metabolism.

Expansion of a bacterial operon during cancer treatment ameliorates drug toxicity.

Dose-limiting toxicities remain a major barrier to drug development and therapy, revealing the limited predictive power of human genetics. Herein, we demonstrate the utility of a more comprehensive approach to studying drug toxicity through longitudinal study of the human gut microbiome during colorectal cancer (CRC) treatment (NCT04054908) coupled to cell culture and mouse experiments. 16S rRNA gene and metagenomic sequencing revealed significant shifts in gut microbial community structure during treatment with oral fluoropyrimidines, which was validated in an independent cohort. Gene abundance was also markedly changed by oral fluoropyrimidines, including an enrichment for the preTA operon, which is sufficient for the inactivation of active metabolite 5-fluorouracil (5-FU). Higher levels of preTA led to increased 5-FU depletion by the gut microbiota grown ex vivo. Germ-free and antibiotic-treated mice had increased fluoropyrimidine toxicity, which was rescued by colonization with the mouse gut microbiota, preTA+ E. coli, or CRC patient stool with high preTA levels. preTA abundance was negatively associated with patient toxicities. Together, these data support a causal, clinically relevant interaction between a human gut bacterial operon and the dose-limiting side effects of cancer treatment. Our approach is generalizable to other drugs, including cancer immunotherapies, and provides valuable insights into host-microbiome interactions in the context of disease.

Urinary and Oral Microbiota Among Men Undergoing Buccal Urethroplasty.

OBJECTIVE: To assess changes in the urinary microbiota after buccal urethroplasty. METHODS: At the University of California San Francisco, we enrolled 9 adult males with urethral strictures undergoing buccal urethroplasty where we collected urine and oral swabs intraoperatively and 3 months postoperatively. 16S rRNA sequencing was used to profile the microbiota. RESULTS: At baseline, the mouth contains twice the number of unique bacteria (alpha diversity) and the microbial community is significantly distinct compared to the urinary tract. Despite having a buccal mucosa in the urinary tract after urethroplasty, the number of unique bacteria in the urine remained stable. However, the bacterial community composition and structure significantly changed in the urinary tract with the enrichment of Corynebacterium genus at 3 months post-urethroplasty procedure. CONCLUSION: In this pilot study, we showed that the alpha diversity in the urinary microbiota did not significantly change despite having a buccal tissue with the capacity to support high bacterial diversity in the urinary tract. To our surprise, the post-urethroplasty urinary microbiota was not a hybrid of baseline oral and urine microbiotas; the changes detected, such as an enrichment of the Corynebacterium genus, were more nuanced yet could profoundly impact surgical outcomes like graft changes and stricture recurrence. Our study not only established the feasibility but also outlined a blueprint for conducting a large-scale study to assess alterations in the urinary microbiome in relation to surgical outcomes.

Associations between the Gut Microbiota, Race, and Ethnicity of Patients with Colorectal Cancer: A Pilot and Feasibility Study.

BACKGROUND: Colorectal cancer (CRC) is more prevalent among some racial and ethnic minority and low socioeconomic status populations. Although the gut microbiota is a risk factor for CRC and varies with race and ethnicity, its role in CRC disparities remains poorly understood. METHODS: We examined the feasibility of recruiting sociodemographically diverse CRC patients for a microbiome study involving a home stool collection. We also explored whether race and ethnicity were associated with gut microbiome composition. We recruited Black/African American, Hispanic/Latino, and non-Hispanic White patients who were receiving care for active CRC to complete a comprehensive dietary and lifestyle survey, self-collect a stool sample, and complete an exit interview. Gut microbial diversity and composition were analyzed using 16S rRNA gene sequencing. RESULTS: 30 individuals consented (of 35 who were eligible and contacted) with 5 (17%) Black/African American, 11 (37%) Hispanic/Latino, and 14 (46%) non-Hispanic White. A total of 22 (73%) completed the dietary and lifestyle survey; 18 (63%) returned a stool sample. Even after controlling for socioeconomic, dietary, or treatment-related covariates, microbiome composition was associated with race and ethnicity. Fusobacteriota (a phylum associated with the development and progression of CRC) was significantly higher in the Black/African American group compared to others, and microbial diversity was higher in samples from non-Hispanic White individuals compared to Hispanic/Latino individuals. CONCLUSION: Our study shows that it is feasible to recruit and collect stool samples from diverse individuals with CRC and found significant associations in gut microbial structure with race and ethnicity.

Raman amplification at 2.2 µm in silicon core fibers with prospects for extended mid-infrared source generation.

Raman scattering provides a convenient mechanism to generate or amplify light at wavelengths where gain is not otherwise available. When combined with recent advancements in high-power fiber lasers that operate at wavelengths ~2 µm, great opportunities exist for Raman systems that extend operation further into the mid-infrared regime for applications such as gas sensing, spectroscopy, and biomedical analyses. Here, a thulium-doped fiber laser is used to demonstrate Raman emission and amplification from a highly nonlinear silicon core fiber (SCF) platform at wavelengths beyond 2 µm. The SCF has been tapered to obtain a micrometer-sized core diameter (~1.6 µm) over a length of 6 cm, with losses as low as 0.2 dB cm-1. A maximum on-off peak gain of 30.4 dB was obtained using 10 W of peak pump power at 1.99 µm, with simulations indicating that the gain could be increased to up to ~50 dB by extending the SCF length. Simulations also show that by exploiting the large Raman gain and extended mid-infrared transparency of the SCF, cascaded Raman processes could yield tunable systems with practical output powers across the 2-5 µm range.

Variety of Fruit and Vegetables and Alcohol Intake are Associated with Gut Microbial Species and Gene Abundance in Colorectal Cancer Survivors.

BACKGROUND: Adherence to the American Cancer Society (ACS) guidelines of avoiding obesity, maintaining physical activity, and consuming a diet rich in fruits, vegetables, and whole grains is associated with longer survival in colorectal cancer (CRC) survivors. Dietary components of the ACS guidelines may act in part by changing the microbiome, which is implicated in CRC outcomes. OBJECTIVES: We conducted a pilot cross-sectional study to explore associations between ACS guidelines and the gut microbiome. METHODS: Stool samples and questionnaires were collected from 28 CRC survivors at the University of California, San Francisco from 2019 to 2020. ACS scores were calculated based on validated questionnaires. Gut microbial community structure from 16S amplicons and gene/pathway abundances from metagenomics were tested for associations with the ACS score and its components using ANOVA and general linear models. RESULTS: The overall ACS score was not significantly associated with variations in the fecal microbiota. However, fruit and vegetable intake and alcohol intake accounted for 19% (P = 0.005) and 13% (P = 0.01) of variation in the microbiota, respectively. Fruit/vegetable consumption was associated with increased microbial diversity, increased Firmicutes, decreased Bacteroidota, and changes to multiple genes and metabolic pathways, including enriched pathways for amino acid and short-chain fatty acid biosynthesis and plant-associated sugar degradation. In contrast, alcohol consumption was positively associated with overall microbial diversity, negatively associated with Bacteroidota abundance, and associated with changes to multiple genes and metabolic pathways. The other components of the ACS score were not statistically significantly associated with the fecal microbiota in our sample. CONCLUSIONS: These results guide future studies examining the impact of changes in the intake of fruits, vegetables, and alcoholic drinks on the gut microbiome of CRC survivors.

Low-temperature polycrystalline silicon waveguides for low loss transmission in the near-to-mid-infrared region.

Low-temperature deposited polycrystalline silicon waveguides are emerging as a flexible platform that allows for dense optoelectronic integration. Here, the optical transmission properties of poly-silicon waveguides have been characterized from the near-to-mid-infrared wavelength regime, extending the optical transmission well beyond previous reports in the telecom band. The poly-Si waveguides with a dimension of 3 µm × âˆ¼0.6 µm have been produced from pre-patterned amorphous silicon waveguides that are post-processed through laser melting, reflowing, and crystallization using a highly localized laser induced heat treatment at a wavelength of 532 nm. Low optical transmission losses (<3 dB cm-1) have been observed at 1.55 µm as well as across the wavelength range of 2-2.25 µm, aided by the relatively large waveguide heights that are enabled by the deposition process. The results demonstrate the suitability of low-temperature poly-silicon waveguides to find wide ranging applications within integrated mid-infrared systems.

Host and gut bacteria share metabolic pathways for anti-cancer drug metabolism.

Pharmaceuticals have extensive reciprocal interactions with the microbiome, but whether bacterial drug sensitivity and metabolism is driven by pathways conserved in host cells remains unclear. Here we show that anti-cancer fluoropyrimidine drugs inhibit the growth of gut bacterial strains from 6 phyla. In both Escherichia coli and mammalian cells, fluoropyrimidines disrupt pyrimidine metabolism. Proteobacteria and Firmicutes metabolized 5-fluorouracil to its inactive metabolite dihydrofluorouracil, mimicking the major host mechanism for drug clearance. The preTA operon was necessary and sufficient for 5-fluorouracil inactivation by E. coli, exhibited high catalytic efficiency for the reductive reaction, decreased the bioavailability and efficacy of oral fluoropyrimidine treatment in mice and was prevalent in the gut microbiomes of colorectal cancer patients. The conservation of both the targets and enzymes for metabolism of therapeutics across domains highlights the need to distinguish the relative contributions of human and microbial cells to drug efficacy and side-effect profiles.

Distinctive gene and protein characteristics of extremely piezophilic Colwellia.

BACKGROUND: The deep ocean is characterized by low temperatures, high hydrostatic pressures, and low concentrations of organic matter. While these conditions likely select for distinct genomic characteristics within prokaryotes, the attributes facilitating adaptation to the deep ocean are relatively unexplored. In this study, we compared the genomes of seven strains within the genus Colwellia, including some of the most piezophilic microbes known, to identify genomic features that enable life in the deep sea. RESULTS: Significant differences were found to exist between piezophilic and non-piezophilic strains of Colwellia. Piezophilic Colwellia have a more basic and hydrophobic proteome. The piezophilic abyssal and hadal isolates have more genes involved in replication/recombination/repair, cell wall/membrane biogenesis, and cell motility. The characteristics of respiration, pilus generation, and membrane fluidity adjustment vary between the strains, with operons for a nuo dehydrogenase and a tad pilus only present in the piezophiles. In contrast, the piezosensitive members are unique in having the capacity for dissimilatory nitrite and TMAO reduction. A number of genes exist only within deep-sea adapted species, such as those encoding d-alanine-d-alanine ligase for peptidoglycan formation, alanine dehydrogenase for NADH/NAD+ homeostasis, and a SAM methyltransferase for tRNA modification. Many of these piezophile-specific genes are in variable regions of the genome near genomic islands, transposases, and toxin-antitoxin systems. CONCLUSIONS: We identified a number of adaptations that may facilitate deep-sea radiation in members of the genus Colwellia, as well as in other piezophilic bacteria. An enrichment in more basic and hydrophobic amino acids could help piezophiles stabilize and limit water intrusion into proteins as a result of high pressure. Variations in genes associated with the membrane, including those involved in unsaturated fatty acid production and respiration, indicate that membrane-based adaptations are critical for coping with high pressure. The presence of many piezophile-specific genes near genomic islands highlights that adaptation to the deep ocean may be facilitated by horizontal gene transfer through transposases or other mobile elements. Some of these genes are amenable to further study in genetically tractable piezophilic and piezotolerant deep-sea microorganisms.

Evaluation of SARS-CoV-2 serology assays reveals a range of test performance.

Appropriate use and interpretation of serological tests for assessments of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure, infection and potential immunity require accurate data on assay performance. We conducted a head-to-head evaluation of ten point-of-care-style lateral flow assays (LFAs) and two laboratory-based enzyme-linked immunosorbent assays to detect anti-SARS-CoV-2 IgM and IgG antibodies in 5-d time intervals from symptom onset and studied the specificity of each assay in pre-coronavirus disease 2019 specimens. The percent of seropositive individuals increased with time, peaking in the latest time interval tested (>20 d after symptom onset). Test specificity ranged from 84.3% to 100.0% and was predominantly affected by variability in IgM results. LFA specificity could be increased by considering weak bands as negative, but this decreased detection of antibodies (sensitivity) in a subset of SARS-CoV-2 real-time PCR-positive cases. Our results underline the importance of seropositivity threshold determination and reader training for reliable LFA deployment. Although there was no standout serological assay, four tests achieved more than 80% positivity at later time points tested and more than 95% specificity.

Test performance evaluation of SARS-CoV-2 serological assays.

BACKGROUND: Serological tests are crucial tools for assessments of SARS-CoV-2 exposure, infection and potential immunity. Their appropriate use and interpretation require accurate assay performance data. METHOD: We conducted an evaluation of 10 lateral flow assays (LFAs) and two ELISAs to detect anti-SARS-CoV-2 antibodies. The specimen set comprised 128 plasma or serum samples from 79 symptomatic SARS-CoV-2 RT-PCR-positive individuals; 108 pre-COVID-19 negative controls; and 52 recent samples from individuals who underwent respiratory viral testing but were not diagnosed with Coronavirus Disease 2019 (COVID-19). Samples were blinded and LFA results were interpreted by two independent readers, using a standardized intensity scoring system. RESULTS: Among specimens from SARS-CoV-2 RT-PCR-positive individuals, the percent seropositive increased with time interval, peaking at 81.8-100.0% in samples taken >20 days after symptom onset. Test specificity ranged from 84.3-100.0% in pre-COVID-19 specimens. Specificity was higher when weak LFA bands were considered negative, but this decreased sensitivity. IgM detection was more variable than IgG, and detection was highest when IgM and IgG results were combined. Agreement between ELISAs and LFAs ranged from 75.7-94.8%. No consistent cross-reactivity was observed. CONCLUSION: Our evaluation showed heterogeneous assay performance. Reader training is key to reliable LFA performance, and can be tailored for survey goals. Informed use of serology will require evaluations covering the full spectrum of SARS-CoV-2 infections, from asymptomatic and mild infection to severe disease, and later convalescence. Well-designed studies to elucidate the mechanisms and serological correlates of protective immunity will be crucial to guide rational clinical and public health policies.

A Genomic Toolkit for the Mechanistic Dissection of Intractable Human Gut Bacteria.

Despite the remarkable microbial diversity found within humans, our ability to link genes to phenotypes is based upon a handful of model microorganisms. We report a comparative genomics platform for Eggerthella lenta and other Coriobacteriia, a neglected taxon broadly relevant to human health and disease. We uncover extensive genetic and metabolic diversity and validate a tool for mapping phenotypes to genes and sequence variants. We also present a tool for the quantification of strains from metagenomic sequencing data, enabling the identification of genes that predict bacterial fitness. Competitive growth is reproducible under laboratory conditions and attributable to intrinsic growth rates and resource utilization. Unique signatures of in vivo competition in gnotobiotic mice include an adhesin enriched in poor colonizers. Together, these computational and experimental resources represent a strong foundation for the continued mechanistic dissection of the Coriobacteriia and a template that can be applied to study other genetically intractable taxa.

Test performance evaluation of SARS-CoV-2 serological assays

BackgroundSerological tests are crucial tools for assessments of SARS-CoV-2 exposure, infection and potential immunity. Their appropriate use and interpretation require accurate assay performance data. MethodWe conducted an evaluation of 10 lateral flow assays (LFAs) and two ELISAs to detect anti-SARS-CoV-2 antibodies. The specimen set comprised 128 plasma or serum samples from 79 symptomatic SARS-CoV-2 RT-PCR-positive individuals; 108 pre-COVID-19 negative controls; and 52 recent samples from individuals who underwent respiratory viral testing but were not diagnosed with Coronavirus Disease 2019 (COVID-19). Samples were blinded and LFA results were interpreted by two independent readers, using a standardized intensity scoring system. ResultsAmong specimens from SARS-CoV-2 RT-PCR-positive individuals, the percent seropositive increased with time interval, peaking at 81.8-100.0% in samples taken >20 days after symptom onset. Test specificity ranged from 84.3-100.0% in pre-COVID-19 specimens. Specificity was higher when weak LFA bands were considered negative, but this decreased sensitivity. IgM detection was more variable than IgG, and detection was highest when IgM and IgG results were combined. Agreement between ELISAs and LFAs ranged from 75.7-94.8%. No consistent cross-reactivity was observed. ConclusionOur evaluation showed heterogeneous assay performance. Reader training is key to reliable LFA performance, and can be tailored for survey goals. Informed use of serology will require evaluations covering the full spectrum of SARS-CoV-2 infections, from asymptomatic and mild infection to severe disease, and later convalescence. Well-designed studies to elucidate the mechanisms and serological correlates of protective immunity will be crucial to guide rational clinical and public health policies.

Potentiation of PBD Dimers by Lipophilicity Manipulation.

Background & Introduction: Pyrrolobenzodiazepine (PBD) dimers are highly potent DNA cross-linking agents used as warheads in Antibody Drug Conjugates (ADCs) for cancer therapy. We propose to investigate the correlation existing between the lipophilicity of those molecules and their activity (both in vitro and in vivo) as well as any effect observed during conjugation. MATERIALS AND METHODS: Reaction progress was monitored by Thin-Layer Chromatography (TLC) using Merck Kieselgel 60 F254 silica gel, with a fluorescent indicator on aluminium plates. Visualisation of TLC was achieved with UV light or iodine vapour unless otherwise stated. Flash chromatography was performed using Merck Kieselgel 60 F254 silica gel. RESULTS: We have successfully designed and synthesized a novel PBD warhead (SG3312) with enhanced physicochemical properties. The warhead also displayed increased potency in vitro. After overcoming some epimerization issues, the synthesis of enantiomerically pure payload was achieved (SG3259) and fulfilled our criteria for a simplified and more efficient conjugation. No addition of propylene glycol was required, and high DAR and excellent monomeric purity were achieved. CONCLUSION: The ADC (Herceptin-maia-SG3259) has been shown to release the active warhead (SG3312) upon exposure to Cathepsin B and demonstrated encouraging activity both in vitro and in vivo.

A Unified Dose Response Relationship to Predict High Dose Fractionation Response in the Lung Cancer Stereotactic Body Radiation Therapy.

AIM: This study is designed to investigate the superiority and applicability of the model among the linear-quadratic (LQ), linear-quadratic-linear (LQ-L) and universal-survival-curve (USC) models by fitting published radiation cell survival data of lung cancer cell lines. MATERIALS AND METHOD: The radiation cell survival data for small cell (SC) and non-small cell (NSC) lung cancer cell lines were obtained from published reports, and were used to determine the LQ and cell survival curve parameters, which ultimately were used in the curve fitting of the LQ, LQ-L and USC models. RESULTS: The results of this study demonstrate that the LQ-L(Dt-mt) model, compared with the LQ and USC models, provides best fit with smooth and gradual transition to the linear portion of the curve at transition dose Dt-mt, where the LQ model loses its validity, and the LQ-L(Dt-2α/ß) and USC(Dt-mt) models do not transition smoothly to the linear portion of the survival curve. CONCLUSION: The LQ-L(Dt-mt) model is able to fit wide variety of cell survival data over a very wide dose range, and retains the strength of the LQ model in the low-dose range.

Colwellia marinimaniae sp. nov., a hyperpiezophilic species isolated from an amphipod within the Challenger Deep, Mariana Trench.

An obligately piezophilic strain was isolated from an amphipod crustacean obtained in the Challenger Deep region of the Mariana Trench during the DEEPSEA CHALLENGE expedition. The strain, MTCD1T, grew at extremely high hydrostatic pressures, with a growth range of 80-140 MPa (optimum, 120 MPa) at 6 °C. Phylogenetic analyses based on the 16S rRNA gene sequence indicate that it is closely affiliated with the genus Colwellia. Comparative 16S rRNA gene sequence analyses revealed 95.7, 95.5 and 95.2 % similarity to Colwellia maris ABE-1T, Colwellia piezophila Y233GT and Colwellia psychrerythraea ATCC 27364T, respectively. The major cellular fatty acids were C16 : 1, C16 : 0 and C22 : 6 (docosahexaenoic acid), and the sole isoprenoid quinone produced was ubiqinone-8. DNA G+C content was 48.6 mol%. The strain was positive for oxidase and catalase activities. Based on the results from this study, strain MTCD1T is a novel Gram-negative species of the genus Colwellia, and the name Colwellia marinimaniae sp. nov. (type strain MTCD1T=ATCC TSD-5T=JCM 30270T) is proposed. It is the most piezophilic organism yet described.

Anatomy-based definition of point A utilizing three-dimensional volumetric imaging approach for high-dose-rate (HDR) intracavitary brachytherapy dose prescription when treating cervical cancer using limited resources.

This study was designed to determine whether volumetric imaging could identify consistent alternative prescription methods to Manchester/point A when prescribing radiation dose in the treatment of cervical cancer using HDR intracavitary brachy-therapy (ICBT). One hundred and twenty-five treatment plans of 25 patients treated for carcinoma of the cervix were reviewed retrospectively. Each patient received 5 fractions of HDR ICBT following initial cisplatin-based pelvic chemoradiation, and radiation dose was originally prescribed to point A (ICRU-38). The gross tumor volume (GTV) and high-risk clinical target volume (HR-CTV) were contoured in three dimensions on the CT datasets, and inferior-superior, anterior-posterior, and left-right dimensions HR-CTV were recorded along with multiple anatomic and skeletal dimensions for each patient. The least square-best fit regression lines were plotted between one half of the HR-CTV width and pelvic cavity dimension at femoral head level and at maximum cavity dimension. The points in both plots lie reasonably close to straight lines and are well defined by straight lines with slopes of 0.15 and 0.17; intercept on y-axes of -0.08 and -0.03, point A, at the same level as defined based on applicator coordinates, is defined using this correlation, which is a function of distance between femoral heads/dimensions of maximum pelvic cavity width. Both relations, defined by straight lines, provide an estimated location of point A, which provides adequate coverage to the HR-CTV compared to the point A defined based on applicator coordinates. The point A defined based on femoral head distance would, therefore, be a reasonable surrogate to use for dose prescription because of subjective variation of cavity width dimension. Simple surrogate anatomic/skeletal landmarks can be useful for prescribing radiation dose when treating cervical cancer using intracavitary brachytherapy in limited-resource settings. Our ongoing work will continue to refine these models.

Spatiotemporal relationship between adult census size and genetic population size across a wide population size gradient.

Adult census population size (N) and effective number of breeders (Nb ) are highly relevant for designing effective conservation strategies. Both parameters are often challenging to quantify, however, making it of interest to determine whether one parameter can be generalized from the other. Yet, the spatiotemporal relationship between N and Nb has not been well characterized empirically in many taxa. We analysed this relationship for 5-7 consecutive years in twelve brook trout populations varying greatly in N (49-10032) and Nb (3-567) and identified major environmental variables affecting the two parameters. N or habitat size alone explained 47-57% of the variance in Nb , and Nb was strongly correlated with effective population size. The ratio Nb /N ranged from 0.01 to 0.45 and increased at small N or following an annual decrease in N, suggesting density-dependent constraints on Nb . We found no evidence for a consistent, directional difference between variability in Nb and/or Nb /N among small and large populations; however, small populations had more varying temporal variability in Nb /N ratios than large populations. Finally, Nb and Nb /N were 2.5- and 2.3-fold more variable among populations than temporally within populations. Our results demonstrate a clear linkage between demographic and evolutionary parameters, suggesting that Nb could be used to approximate N (or vice versa) in natural populations. Nevertheless, using one variable to infer the other to monitor trends within populations is less recommended, perhaps even less so in small populations given their less predictable Nb vs. N dynamics.

A Follow-Up Study of the Prevalence of Valvular Heart Abnormalities in Hyperprolactinemic Patients Treated With Cabergoline.

CONTEXT: Uncertainty exists whether the long-term use of ergot-derived dopamine agonist (DA) drugs for the treatment of hyperprolactinemia may be associated with clinically significant valvular heart disease and whether current regulatory authority guidelines for echocardiographic screening are clinically appropriate. OBJECTIVE: Our objective was to provide follow-up echocardiographic data on a previously described cohort of patients treated with DA for lactotrope pituitary tumors and to explore possible associations between structural and functional valve abnormalities with the cumulative dose of drug used. DESIGN: Follow-up echocardiographic data were collected from a proportion of our previously reported cohort of patients; all had received continuous DA therapy for at least 2 years in the intervening period. Studies were performed according to British Society of Echocardiography minimum standards for adult transthoracic echocardiography. Generalized estimating equations with backward selection were used to determine odds ratios of valvular heart abnormalities according to tertiles of cumulative cabergoline dose, using the lowest tertile as the reference group. SETTING: Thirteen centers of secondary/tertiary endocrine care across the United Kingdom were included. RESULTS: There were 192 patients (81 males; median age, 51 years; interquartile range [IQR], 42-62). Median (IQR) cumulative cabergoline doses at the first and second echocardiograms were 97 mg (20-377) and 232 mg (91-551), respectively. Median (IQR) duration of uninterrupted cabergoline therapy between echocardiograms was 34 months (24-42). No associations were observed between cumulative doses of dopamine agonist used and the age-corrected prevalence of any valvular abnormality. CONCLUSION: This large UK follow-up study does not support a clinically significant association between the use of DA for the treatment of hyperprolactinemia and cardiac valvulopathy.