Phosphonate consumers potentially contributing to methane production in Brazilian soda lakes.

Oxic methane production (OMP) has been reported to significantly contribute to methane emissions from oxic surface waters. Demethylation of organic compounds, photosynthesis-associated methane production, and (bacterio)chlorophyll reduction activity are some of the investigated mechanisms as potential OMP sources related to photosynthetic organisms. Recently, cyanobacteria have often been correlated with methane accumulation and emission in freshwater, marine, and saline systems. The Brazilian Pantanal is the world's largest wetland system, with approximately 10,000 shallow lakes, most of which are highly alkaline and saline extreme environments. We initiated this study with an overall investigation using genetic markers, from which we explored metagenomic and limnological data from the Pantanal soda for five potential OMP pathways. Our results showed a strong positive correlation between dissolved methane concentrations and bloom events. Metagenomic data and nutrients, mainly orthophosphate, nitrogen, iron, and methane concentrations, suggest that the organic phosphorous demethylation pathway has the most potential to drive OMP in lakes with blooms. A specialized bacterial community was identified, including the Cyanobacteria Raphidiopsis, although the bloom does not contain the genes to carry out this process. These data showed enough evidence to infer the occurrence of an OMP pathway at Pantanal soda lakes, including the microbial sources and their relation to the cyanobacterial blooms.

Comparison of pharmacokinetics and bioavailability of bedaquiline fumarate, benzoate and maleate in dogs.

BACKGROUND: Bedaquiline (BDQ) as a fumarate salt is indicated as part of a regimen to treat multidrug-resistant TB (MDR-TB). BDQ benzoate and maleate have been identified as promising alternatives that will encourage generic pharmaceutical houses to manufacture this drug. Our study compared the pharmacokinetics (PK) of BDQ fumarate vs. the maleate and benzoate salts in dogs.METHODS: The PK of BDQ and its active N-desmethyl metabolite M2 following intravenous administration of 1 mg/kg BDQ (as fumarate) and oral administration of 10 mg/kg BDQ as fumarate, benzoate, or maleate salts in suspension to fasted male beagle dogs was evaluated in a parallel-group and crossover study with N = 4 per group. BDQ and M2 plasma concentrations were determined up to 168 h post-dose. T-tests were conducted to compare the area under the curve, AUC0-t among groups.RESULTS: Orally administered fumarate, benzoate, and maleate salts, in parallel-group design, resulted in mean BDQ AUC0-t of 9,267 ± SD 10,182, 19,258 ± SD 11,803, and 15,396 ± SD 9,170 ng.h/ml, respectively; and in a crossover design of 9,267 ± SD 10,182, 17,441 ± SD 24,049, and 18,087 ± SD 19,758 ng.h/ml, respectively. P values were >0.05.CONCLUSION: There was no statistically significant difference in BDQ and M2 AUC0-t following oral administration of fumarate, benzoate and maleate salts in dogs.

Prenatal exposure to nickel and atopic dermatitis at age 3 years: a birth cohort study with cytokine profiles.

BACKGROUND: Nickel, the fifth most common element on Earth, is the leading inducer of contact allergies in humans, with potent immunological effects. Nickel-induced contact allergies predominantly affect females. Maternal exposure to nickel has been associated with several developmental abnormalities. However, how a maternal nickel exposure affects the development of atopic diathesis and immune abnormalities in children has never been addressed. OBJECTIVES: We aimed to determine whether maternal nickel exposure affects the development of atopic dermatitis and immune abnormalities in their children. METHODS: Using a birth cohort study, we analysed 140 mother-child pairs recruited in 2012-2015 from central Taiwan. Maternal exposure to nickel was estimated using urinary nickel levels measured by inductively coupled plasma mass spectrometry (ICP-MS). The serum levels of 65 analytes and IgE in 3-year-old children were profiled with a multiplex ELISA. The correlation between the maternal urinary nickel concentration and serum analyte levels was assessed using Spearmen's correlation. Multivariant regression analysis was performed to evaluate the association between maternal urinary nickel levels and serum analyte concentrations in their children. RESULTS: The geometric means of the maternal urinary nickel and the children's serum IgE levels were 2.27 µg/L and 69.71 IU/mL, respectively. The maternal nickel exposure was associated with increased serum levels of IL-1ß, IL-2, TNF-α, and leukaemia inhibitory factor (LIF) but with decreased serum levels of matrix metalloproteinase-1 (MMP-1), IL-2R, and eotaxin-1 in the children. In addition, the development of childhood atopic dermatitis at 3 years old was significantly associated with the child's serum levels of IgE and IL-2R, but it was negatively associated with the maternal nickel exposure. CONCLUSIONS: This is the first study showing the potential immunological effects of maternal nickel exposure in their children at an early developmental stage.

Associations of a family history of lupus with the risks of lupus and major psychiatric disorders in first-degree relatives.

BACKGROUND: Genetic factors link psychiatric disorders, particularly major depressive disorder (MDD), bipolar disorder, and obsessive-compulsive disorder (OCD), with systemic lupus erythematosus (SLE). Additionally, maternal SLE is a risk factor for long-term developmental problems, particularly learning disabilities, attention disorders, autism spectrum disorder (ASD) and speech disorders, in children. AIM: We aimed to determine whether first-degree relatives (FDRs) of patients with SLE have increased risks of SLE and major psychiatric disorders. DESIGN AND METHODS: Using the Taiwan National Health Insurance Research Database, we recruited 40 462 FDRs of patients with SLE as well as 161 848 matched controls. The risks of major psychiatric disorders, including schizophrenia, bipolar disorder, OCD, MDD, ASD and attention-deficit/hyperactivity disorder (ADHD), were assessed. RESULTS: The FDRs of patients with SLE had higher risks of SLE (reported as the adjusted relative risk and 95% confidence interval: 14.54; 12.19-17.34), MDD (1.23; 1.12-1.34), ADHD (1.60; 1.55-1.65), OCD (1.41; 1.14-1.74) and bipolar disorder (1.18; 1.01-1.38) compared with controls. Specifically, male FDRs of patients with SLE had higher risks of SLE and bipolar disorder, whereas female FDRs of patients with SLE had higher risks of MDD and OCD. Differences in the familial relationship (i.e. parents, children, siblings and twins) were consistently associated with higher risks of these disorders compared with controls. CONCLUSIONS: The FDRs of patients with SLE had higher risks of SLE, MDD, ADHD, OCD and bipolar disorder than the controls.

Effects of Exercise Alone or in Combination with High-Protein Diet on Muscle Function, Aerobic Capacity, and Physical Function in Middle-Aged Obese Adults: A Randomized Controlled Trial.

BACKGROUND: Obesity accelerates and exacerbates the age-related changes on muscle function and exercise capacity. In addition, the middle-aged population is often overlooked when talking about the prevention of sarcopenia. This study investigated the effects of exercise alone or in combination with a high-protein diet on muscle function and physical fitness in middle-aged obese adults. MATERIALS AND METHODS: Sixty-nine middle-aged (50-64 years old) obese adults were randomly assigned to one of the following groups: control group (C; n=23), exercise group (E; n=23) or exercise plus high-protein group (EP; n=23). Individuals within the E and EP groups received 12 weeks of exercise training; whereas, the individuals in the EP group also received a high-protein diet intervention (1.6g/kg/day). Individuals within the C group were asked to maintain their lifestyle for 12 weeks. Participants were evaluated before and after the intervention. Outcome measures included maximal exercise capacity, muscle function and functional physical performance. Analysis of covariance was used to determine the effects of the intervention. RESULTS: After the intervention, the E and EP groups had greater maximal work rate, peak oxygen consumption, and muscle power during muscle contractions at 180°/sec than that in the C group (P<0.05). The EP group, but not the E group, showed significant improvement in the sit-to-stand test and climbing stairs test than the C group after the intervention (P<0.05). Within group comparisons showed that the anaerobic threshold only increased in the EP group (+12% from pre-test). CONCLUSIONS: For middle-aged obese adults, exercise with a high-protein diet not only improved muscle power and exercise capacity but also enhanced their functional physical performance.

The brief window of time comprising a wheelchair transfer confers a significant fracture risk on elderly Americans.

OBJECTIVES: Wheelchairs grant increased mobility to their users but can result in injuries of varying severities, including fractures which are often associated with wheelchair transfers. However, this fracture burden remains poorly characterized in elderly Americans. The purpose of this study was to report demographic and environmental risk factors for these injuries. STUDY DESIGN: We used data from the National Electronic Injury Surveillance System (NEISS) for the years 2007-2017 to perform a retrospective, cross-sectional analysis of wheelchair transfer fractures in patients aged 65 years and older. METHODS: Each yearly sample in the NEISS database was queried between 2007 and 2017 for fractures associated with wheelchair transfers in patients aged 65 years or older. The narrative sections of the database were individually read and reviewed to identify cases in which a patient explicitly transferred into or out of a wheelchair while sustaining said fracture. RESULTS: Between 2007 and 2017, the average number of patients aged 65 years and older presenting to US emergency departments was 3924 (95% confidence interval [CI] = 2792-5055). A significantly higher percentage of fractures (61.8%; 95% CI = 56.7%-66.8%) is associated with transferring out of wheelchairs. Moreover, such fractures were often associated with transferring to and from beds (29.9%; 95% CI = 25.4%-34.3%), with the hip (37.5%; 95% CI = 33.3%-41.6%) being the most commonly fractured anatomical region overall. A majority of patients required admission to the hospital (60.2%; 95%CI = 52.4%-68.0%) and most wheelchair transfer fractures occurred at home (44.1%; 95% CI = 36.7%-51.5%), with women (71.9%; 95% CI = 68.3%-75.6%) comprising the majority of these patients. CONCLUSIONS: Our findings show that wheelchair transfers are associated with significant risk of severe fracture in elderly Americans. As such, wheelchair transfer events merit extra attention from healthcare providers because they comprise a brief window of time relative to the number of occupancy hours in full-time wheelchair users yet can result in significant morbidity and mortality. Preventative measures and patient education should be encouraged to preserve patient mobility and reduce injury.

Non-vitamin K antagonist oral anticoagulants (NOACs) for thromboembolic prevention, are they safe in congenital heart disease? Results of a worldwide study.

BACKGROUND: Current guidelines consider vitamin K antagonists (VKA) the oral anticoagulant agents of choice in adults with atrial arrhythmias (AA) and moderate or complex forms of congenital heart disease, significant valvular lesions, or bioprosthetic valves, pending safety data on non-VKA oral anticoagulants (NOACs). Therefore, the international NOTE registry was initiated to assess safety, change in adherence and quality of life (QoL) associated with NOACs in adults with congenital heart disease (ACHD). METHODS: An international multicenter prospective study of NOACs in ACHD was established. Follow-up occurred at 6 months and yearly thereafter. Primary endpoints were thromboembolism and major bleeding. Secondary endpoints included minor bleeding, change in therapy adherence (≥80% medication refill rate, ≥6 out of 8 on Morisky-8 questionnaire) and QoL (SF-36 questionnaire). RESULTS: In total, 530 ACHD patients (mean age 47 SD 15 years; 55% male) with predominantly moderate or complex defects (85%), significant valvular lesions (46%) and/or bioprosthetic valves (11%) using NOACs (rivaroxaban 43%; apixaban 39%; dabigatran 12%; edoxaban 7%) were enrolled. The most common indication was AA (91%). Over a median follow-up of 1.0 [IQR 0.0-2.0] year, thromboembolic event rate was 1.0% [95%CI 0.4-2.0] (n = 6) per year, with 1.1% [95%CI 0.5-2.2] (n = 7) annualized rate of major bleeding and 6.3% [95%CI 4.5-8.5] (n = 37) annualized rate of minor bleeding. Adherence was sufficient during 2 years follow-up in 80-93% of patients. At 1-year follow-up, among the subset of previous VKA-users who completed the survey (n = 33), QoL improved in 6 out of 8 domains (p ≪ 0.05). CONCLUSIONS: Initial results from our worldwide prospective study suggest that NOACs are safe and may be effective for thromboembolic prevention in adults with heterogeneous forms of congenital heart disease.

The cellular basis of fetal endoplasmic reticulum stress and oxidative stress in drug-induced neurodevelopmental deficits.

Prenatal substance exposure is a growing public health concern worldwide. Although the opioid crisis remains one of the most prevalent addiction problems in our society, abuse of cocaine, methamphetamines, and other illicit drugs, particularly amongst pregnant women, are nonetheless significant and widespread. Evidence demonstrates prenatal drug exposure can affect fetal brain development and thus can have long-lasting impact on neurobehavioral and cognitive performance later in life. In this review, we highlight research examining the most prevalent drugs of abuse and their effects on brain development with a focus on endoplasmic reticulum stress and oxidative stress signaling pathways. A thorough exploration of drug-induced cellular stress mechanisms during prenatal brain development may provide insight into therapeutic interventions to combat effects of prenatal drug exposure.

Quantum Simulation of the Universal Features of the Polyakov Loop.

Lattice gauge theories are fundamental to our understanding of high-energy physics. Nevertheless, the search for suitable platforms for their quantum simulation has proven difficult. We show that the Abelian Higgs model in 1+1 dimensions is a prime candidate for an experimental quantum simulation of a lattice gauge theory. To this end, we use a discrete tensor reformulation to smoothly connect the space-time isotropic version used in most numerical lattice simulations to the continuous-time limit corresponding to the Hamiltonian formulation. The eigenstates of the Hamiltonian are neutral for periodic boundary conditions, but we probe the nonzero charge sectors by introducing either a Polyakov loop or an external electric field. In both cases we obtain universal functions relating the mass gap, the gauge coupling, and the spatial size, which are invariant under the deformation of the temporal lattice spacing. We propose to use a physical multileg ladder of atoms trapped in optical lattices and interacting with Rydberg-dressed interactions to quantum simulate the model and check the universal features. Our results provide a path to the analog quantum simulation of lattice gauge theories with atoms in optical lattices.

[Peritoneal dialysis-related eosinophilic peritonitis: a case report and literature review].

Peritoneal dialysis (PD)-related peritonitis is recognized as a common complication of peritoneal dialysis. Eosinophilic peritonitis is a rare type of non-infection PD-related peritonitis. Eosinophilic peritonitis in continuous ambulatory peritoneal dialysis (CAPD) patients was first reported in 1967. The cause of eosinophilic peritonitis is obscure, however it may be related to some etiologies: (1) hypersensitivity to PD materials, including catheter or dialysate; (2) bacteria, fungal or mycobacterium tuberculosis infection. Clinical investigations include asymptomatic cloudy PD effluent, fever, abdominal pain and eosinophil count elevate in PD effluent. Eosinophilic peritonitis is usually mild and self-limited. With the development of PD, more eosinophilic peritonitis cases and researches were reported. Here, we report a patient on CAPD with eosinophilic peritonitis. A 71-year-old female patient developed end-stage renal disease for 4 years and underwent CAPD (2 000 mL of 1.5% dialysis solution with four exchanges daily) for 5 months. With a history of unclean food, she was hospitalized for complaints of diarrhea, fever and cloudy peritoneal effluent for 10 days. Dialysis effluent showed an elevated white blood cell (WBC) count of 1 980 cell/mm3, with 60% polymorphonuclear cells. She was diagnosed as PD-related peritonitis, and therapy was initiated with intraperitoneal ceftazidime 1 g once a day and vancomycin 500 mg every other day. She was admitted to the hospital as the symptoms were not relieved. Her peripheral blood cell count showed a total WBC count of 6 940 cells/mm3, 36.8% eosinophil. Her PD effluent analysis showed turbidity, total WBC count of 1 480 cells/mm3, and 83% polymorphonuclear cells. Her dialysate bacteria culture, fungus culture, polymerase chain reaction for Mycobacterium tuberculosis (TB-PCR), acid-fast stain were all negative. On admission day 4, the treatments were changed to levofloxacin 200 mg once a day and vancomycin 500 mg every other day. After two weeks of antibiotics treatment, patient's symptoms were not completely improved and her dialysis effluent remained cloudy. Her blood eosinophil count elevated to 36.8%，eosinophil proportion in PD effluent>90% and PD effluent pathological findings showed eosinophil>90%. Eosinophilic peritonitis was diagnosed and a decision was made to give loratadine daily dose of 10 mg orally. The possible reasons might be the patient's allergy to some components of PD solution or connection systems in the beginning of PD, and this bacterial peritonitis episode, as well as the application of vancomycin, might lead to the fact that eosinophilic peritonitis acutely developed. For there was no improvement in clinical symptoms, loratadine was stopped, and the patient was discharged 18 days later, and received follow-up closely. Two months later, eosinophil count in blood and PD fluid decreased to normal range with no symptom. This case reminds us that in any PD-related peritonitis patient with prolonged symptoms after appropriate antibiotic therapy, and typical clinical symptoms, the diagnosis of eosinophilic peritonitis should be considered. For the count and percentage of eosinophils are not routinely reported in most laboratories, doctors need to contact the department of laboratory and the department of pathology, to confirm the cell count and proportion of eosinophils in dialysis effluent, so as to make the definite diagnosis, which can not only avoid antibiotics overuse, but also avoid antibiotics-induced eosinophilic peritonitis (such as vancomycin).

Inchworm bipedal nanowalker.

Nanowalkers take either inchworm (IW) or hand-over-hand (HOH) gait. The IW nanowalkers are advantageous over HOH ones in force generation, processivity and high-density integration, though both gaits occur in intracellular nanowalkers from biology. Artificial IW nanowalkers have been realized or proposed, but all rely on different 'head' and 'tail' to gain an adventitious direction. Here we report an inherently unidirectional IW nanowalker that is a biped with two identical legs (i.e., indistinguishable 'head' and 'tail'). This walker is made of DNA, and driven by a light-powered G-quadruplex engine. The directional inchworm motion is confirmed by operating the walker on a DNA duplex track that is designed to show a distinctive fluorescence pattern for IW walkers as compared to HOH ones. Interestingly, this walker exhibits stride-controlled IW-to-HOH gait switch and direction reversal when the track's periodic binding sites have wider and wider separation. The results altogether present an integrated mechanism for implementing nanowalkers of different gaits and directions on molecular tracks, optical potentials or even solid-state surfaces.

Urinary Liver Type Fatty Acid Binding Protein Is Negatively Associated With Estimated Glomerular Filtration Rate in Renal Transplant Recipients With Graft Loss.

BACKGROUND: Liver type fatty acid binding protein (L-FABP) is abundant not only in the liver but also in the kidney and is excreted in urine. Its primary function is to facilitate intracellular long chain fatty acid transport and it might also act as an endogenous antioxidant molecular. The purpose of this study was to investigate whether plasma or urinary L-FABP levels were associated with graft function in renal transplant recipients. PATIENTS AND METHODS: Sixty-seven renal transplant recipients with a mean age of 48.8 years were recruited. The mean duration of renal transplantation was 4131 days. Recipients were divided into 2 groups based on their estimated glomerular filtration rate (eGFR) values: moderate graft function (eGFR ≥60 mL/min/1.73 m2) and low graft function (eGFR <60 mL/min/1.73 m2). Fasting plasma and urinary L-FABP levels were measured. RESULTS: There was no significant difference in plasma L-FABP level between the 2 groups, although recipients in the low graft function group had significantly lower urinary L-FABP level when compared with recipients in the moderate graft function group. Plasma and urinary L-FABP levels were not associated with eGFR in the 67 recipients; however, urinary L-FABP level (ß = -1.24, P = .037) and level adjusted by urinary creatinine (ß = -0.75, P = .046) were significantly negatively associated with eGFR in recipients with low graft function after adjusting for potential confounders. CONCLUSION: Increased urinary L-FABP level seems to be a significant indicator of decreased graft function in renal transplant recipients with loss of graft function.

Indoor air quality in hairdressing salons in Taipei.

To improve indoor air quality and to protect public health, Taiwan has enacted the "Indoor Air Quality Act (IAQ Act)" in 2012. For the general public, the indoor air quality in hair salons is important because it is a popular location that people will often visit for hair treatments. However, only a few exposure assessments regarding air pollutants have previously been performed in hair salons. To assess the air quality of hairdressing environments in Taipei, ten hairdressing salons were included for a walk-through survey in this study. In addition, the airborne concentrations of formaldehyde, volatile organic compounds (VOCs), CO2 , and phthalate esters were also determined in 5 salons. Charcoal, XAD-2, and OVS-Tenax tubes were used for the air sampling, while the samples were analyzed with gas chromatography/mass spectrometer. It was found that the products used in hair salons contained various chemicals. In fact, from the walk-through survey, a total of 387 different ingredients were found on 129 hair product labels. The hair salons were not well ventilated, with CO2 levels of 600 to 3576 ppm. The formaldehyde concentrations determined in this study ranged from 12.40 to 1.04 × 103  µg m-3 , and the maximum level was above the permissible exposure limit (PEL) of US Occupational Safety and Health Administration (US OSHA). Additionally, 83% of the samples were with levels higher than the standard regulated by Taiwan's IAQ Act. The concentrations of VOCs and phthalate esters were below the occupational exposure limits (OELs), but higher than what was found in general residential environments. The hair products were considered as the major source of air pollutants because significantly higher concentrations were found around the working areas. The number of perming treatments, the number of workers, and the frequency of using formaldehyde releasing products, were found to be associated with the levels of formaldehyde. This study indicates that efforts are needed to improve the indoor air quality in hairdressing salons in Taipei.

Co-aggregation of major psychiatric disorders in individuals with first-degree relatives with schizophrenia: a nationwide population-based study.

A previous genetic study has suggested that schizophrenia, bipolar disorder, major depressive disorder, autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) share common disease-associated genes. However, whether individuals with first-degree relatives (FDRs) with schizophrenia have a higher risk of these major psychiatric disorders requires further investigation. This study used Taiwan's National Health Insurance Research Database and identified 151 650 patients with schizophrenia and 227 967 individuals with FDRs with schizophrenia. The relative risks (RRs) of schizophrenia and other major psychiatric disorders were assessed in individuals with FDRs with schizophrenia. The individuals with FDRs with schizophrenia exhibited higher RRs (95% confidence interval) of major psychiatric disorders, namely schizophrenia (4.76, 4.65-4.88), bipolar disorder (3.23, 3.12-3.35), major depressive disorder (2.05, 2.00-2.10), ASD (2.55, 2.35-2.77) and ADHD (1.31, 1.25-1.37) than were found in the total population. Several sensitivity analyses were conducted to confirm these results. A dose-dependent relationship was observed between the risks of major psychiatric disorders and the numbers of FDRs with schizophrenia. The increased risks of major psychiatric disorders were consistent in different family relationships, namely among parents, offspring, siblings and twins. Our study supports the familial dose-dependent co-aggregation of schizophrenia, bipolar disorder, major depressive disorder, ASD and ADHD, and our results may prompt governmental public health departments and psychiatrists to focus on the mental health of individuals with FDRs with schizophrenia.

Valproic acid attenuates the risk of acute respiratory failure in patients with subarachnoid hemorrhage.

BACKGROUND: Valproic acid (VPA) has shown potent anti-inflammatory effect and attenuates acute lung injury. AIM: To determine whether the use of VPA is associated with a decreased risk of acute respiratory failure (ARF) in patients with subarachnoid hemorrhage (SAH). DESIGN: The Taiwan National Health Insurance Research Database was used to analyse all patients newly diagnosed with SAH from 2000 to 2010. The VPA users were matched for age, gender and index date in 1:2 ratios with randomly selected non-VPA users as a comparison group. METHODS: Multivariate Cox regression was used to identify the predictors of ARF and to compare the incidence rates of ARF among SAH patients using and not using VPA. RESULTS: The study cohort included 16 228 newly diagnosed SAH patients, from which 521 VPA users and 1042 matched non-VPA-exposed individuals were selected. In the VPA-treated cohort and the non-VPA-treated cohort, 117 and 289 patients developed ARF, respectively. Any use of VPA was associated with a 16% decreased risk of ARF requiring mechanical ventilation in 30-day tracking of the SAH patients (adjusted hazard ratio [HR], 0.840, 95% confidence interval [CI], 0.676-0.945). Age, sepsis and pneumonia were identified as independent predictors of ARF in patients with SAH. After stratification, VPA users showed a lower risk of ARF among SAH patients complicated with pneumonia compared with non-users of VPA (adjusted HR, 0.816, 95% CI, 0.652-0.921). CONCLUSIONS: Any use of VPA was associated with a reduced risk of ARF in patients with SAH. VPA may be beneficial for decreasing the risk of pneumonia-induced ARF in patients with SAH.

Shrinking microbubbles with microfluidics: mathematical modelling to control microbubble sizes.

Microbubbles have applications in industry and life-sciences. In medicine, small encapsulated bubbles (<10 µm) are desirable because of their utility in drug/oxygen delivery, sonoporation, and ultrasound diagnostics. While there are various techniques for generating microbubbles, microfluidic methods are distinguished due to their precise control and ease-of-fabrication. Nevertheless, sub-10 µm diameter bubble generation using microfluidics remains challenging, and typically requires expensive equipment and cumbersome setups. Recently, our group reported a microfluidic platform that shrinks microbubbles to sub-10 µm diameters. The microfluidic platform utilizes a simple microbubble-generating flow-focusing geometry, integrated with a vacuum shrinkage system, to achieve microbubble sizes that are desirable in medicine, and pave the way to eventual clinical uptake of microfluidically generated microbubbles. A theoretical framework is now needed to relate the size of the microbubbles produced and the system's input parameters. In this manuscript, we characterize microbubbles made with various lipid concentrations flowing in solutions that have different interfacial tensions, and monitor the changes in bubble size along the microfluidic channel under various vacuum pressures. We use the physics governing the shrinkage mechanism to develop a mathematical model that predicts the resulting bubble sizes and elucidates the dominant parameters controlling bubble sizes. The model shows a good agreement with the experimental data, predicting the resulting microbubble sizes under different experimental input conditions. We anticipate that the model will find utility in enabling users of the microfluidic platform to engineer bubbles of specific sizes.